1
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Calado M, Ferreira R, Pires D, Santos-Costa Q, Anes E, Brites D, Azevedo-Pereira JM. Unravelling the triad of neuroinvasion, neurodissemination, and neuroinflammation of human immunodeficiency virus type 1 in the central nervous system. Rev Med Virol 2024; 34:e2534. [PMID: 38588024 DOI: 10.1002/rmv.2534] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2023] [Revised: 03/05/2024] [Accepted: 03/28/2024] [Indexed: 04/10/2024]
Abstract
Since the identification of human immunodeficiency virus type 1 (HIV-1) in 1983, many improvements have been made to control viral replication in the peripheral blood and to treat opportunistic infections. This has increased life expectancy but also the incidence of age-related central nervous system (CNS) disorders and HIV-associated neurodegeneration/neurocognitive impairment and depression collectively referred to as HIV-associated neurocognitive disorders (HAND). HAND encompasses a spectrum of different clinical presentations ranging from milder forms such as asymptomatic neurocognitive impairment or mild neurocognitive disorder to a severe HIV-associated dementia (HAD). Although control of viral replication and suppression of plasma viral load with combination antiretroviral therapy has reduced the incidence of HAD, it has not reversed milder forms of HAND. The objective of this review, is to describe the mechanisms by which HIV-1 invades and disseminates in the CNS, a crucial event leading to HAND. The review will present the evidence that underlies the relationship between HIV infection and HAND. Additionally, recent findings explaining the role of neuroinflammation in the pathogenesis of HAND will be discussed, along with prospects for treatment and control.
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Affiliation(s)
- Marta Calado
- Host-Pathogen Interactions Unit, Research Institute for Medicines, iMed-ULisboa, Faculty of Pharmacy, Universidade de Lisboa, Lisboa, Portugal
| | - Rita Ferreira
- Host-Pathogen Interactions Unit, Research Institute for Medicines, iMed-ULisboa, Faculty of Pharmacy, Universidade de Lisboa, Lisboa, Portugal
| | - David Pires
- Host-Pathogen Interactions Unit, Research Institute for Medicines, iMed-ULisboa, Faculty of Pharmacy, Universidade de Lisboa, Lisboa, Portugal
- Center for Interdisciplinary Research in Health, Católica Medical School, Universidade Católica Portuguesa, Estrada Octávio Pato, Rio de Mouro, Portugal
| | - Quirina Santos-Costa
- Host-Pathogen Interactions Unit, Research Institute for Medicines, iMed-ULisboa, Faculty of Pharmacy, Universidade de Lisboa, Lisboa, Portugal
| | - Elsa Anes
- Host-Pathogen Interactions Unit, Research Institute for Medicines, iMed-ULisboa, Faculty of Pharmacy, Universidade de Lisboa, Lisboa, Portugal
| | - Dora Brites
- Neuroinflammation, Signaling and Neuroregeneration Unit, Research Institute for Medicines, iMed-ULisboa, Faculty of Pharmacy, Universidade de Lisboa, Lisboa, Portugal
| | - José Miguel Azevedo-Pereira
- Host-Pathogen Interactions Unit, Research Institute for Medicines, iMed-ULisboa, Faculty of Pharmacy, Universidade de Lisboa, Lisboa, Portugal
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2
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Kaur J, Boyd ED, Ding G, Zhang L, Luo H, Li Q, Li L, Wei M, Landschoot-Ward J, Chopp M, Zhang Z, Jiang Q. The Association between Glymphatic System and Perivascular Macrophages in Brain Waste Clearance. Diagnostics (Basel) 2024; 14:731. [PMID: 38611644 PMCID: PMC11011895 DOI: 10.3390/diagnostics14070731] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2024] [Revised: 03/13/2024] [Accepted: 03/14/2024] [Indexed: 04/14/2024] Open
Abstract
The glymphatic system suggests the convective bulk flow of cerebrospinal fluid (CSF) through perivascular spaces and the interstitial spaces of the brain parenchyma for the rapid removal of toxic waste solutes from the brain. However, the presence of convective bulk flow within the brain interstitial spaces is still under debate. We first addressed this argument to determine the involvement of the glymphatic system in brain waste clearance utilizing contrast-enhanced 3D T1-weighted imaging (T1WI), diffusion tensor imaging (DTI), and confocal microscopy imaging. Furthermore, perivascular macrophages (PVMs), which are immune cells located within perivascular spaces, have not been thoroughly explored for their association with the glymphatic system. Therefore, we investigated tracer uptake by PVMs in the perivascular spaces of both the arteries/arterioles and veins/venules and the potential association of PVMs in assisting the glymphatic system for interstitial waste clearance. Our findings demonstrated that both convective bulk flow and diffusion are responsible for the clearance of interstitial waste solutes from the brain parenchyma. Furthermore, our results suggested that PVMs may play an important function in glymphatic system-mediated interstitial waste clearance. The glymphatic system and PVMs could be targeted to enhance interstitial waste clearance in patients with waste-associated neurological conditions and aging.
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Affiliation(s)
- Jasleen Kaur
- Department of Neurology, Henry Ford Health System, Detroit, MI 48202, USA; (J.K.); (E.D.B.); (G.D.); (L.Z.); (H.L.); (Q.L.); (L.L.); (M.W.); (J.L.-W.); (M.C.); (Z.Z.)
- Department of Physics, Oakland University, Rochester, MI 48309, USA
| | - Edward D. Boyd
- Department of Neurology, Henry Ford Health System, Detroit, MI 48202, USA; (J.K.); (E.D.B.); (G.D.); (L.Z.); (H.L.); (Q.L.); (L.L.); (M.W.); (J.L.-W.); (M.C.); (Z.Z.)
- Department of Radiology, Michigan State University, East Lansing, MI 48824, USA
| | - Guangliang Ding
- Department of Neurology, Henry Ford Health System, Detroit, MI 48202, USA; (J.K.); (E.D.B.); (G.D.); (L.Z.); (H.L.); (Q.L.); (L.L.); (M.W.); (J.L.-W.); (M.C.); (Z.Z.)
- Department of Radiology, Michigan State University, East Lansing, MI 48824, USA
| | - Li Zhang
- Department of Neurology, Henry Ford Health System, Detroit, MI 48202, USA; (J.K.); (E.D.B.); (G.D.); (L.Z.); (H.L.); (Q.L.); (L.L.); (M.W.); (J.L.-W.); (M.C.); (Z.Z.)
- Department of Physiology, Michigan State University, East Lansing, MI 48824, USA
| | - Hao Luo
- Department of Neurology, Henry Ford Health System, Detroit, MI 48202, USA; (J.K.); (E.D.B.); (G.D.); (L.Z.); (H.L.); (Q.L.); (L.L.); (M.W.); (J.L.-W.); (M.C.); (Z.Z.)
| | - Qingjiang Li
- Department of Neurology, Henry Ford Health System, Detroit, MI 48202, USA; (J.K.); (E.D.B.); (G.D.); (L.Z.); (H.L.); (Q.L.); (L.L.); (M.W.); (J.L.-W.); (M.C.); (Z.Z.)
| | - Lian Li
- Department of Neurology, Henry Ford Health System, Detroit, MI 48202, USA; (J.K.); (E.D.B.); (G.D.); (L.Z.); (H.L.); (Q.L.); (L.L.); (M.W.); (J.L.-W.); (M.C.); (Z.Z.)
| | - Min Wei
- Department of Neurology, Henry Ford Health System, Detroit, MI 48202, USA; (J.K.); (E.D.B.); (G.D.); (L.Z.); (H.L.); (Q.L.); (L.L.); (M.W.); (J.L.-W.); (M.C.); (Z.Z.)
| | - Julie Landschoot-Ward
- Department of Neurology, Henry Ford Health System, Detroit, MI 48202, USA; (J.K.); (E.D.B.); (G.D.); (L.Z.); (H.L.); (Q.L.); (L.L.); (M.W.); (J.L.-W.); (M.C.); (Z.Z.)
| | - Michael Chopp
- Department of Neurology, Henry Ford Health System, Detroit, MI 48202, USA; (J.K.); (E.D.B.); (G.D.); (L.Z.); (H.L.); (Q.L.); (L.L.); (M.W.); (J.L.-W.); (M.C.); (Z.Z.)
- Department of Physics, Oakland University, Rochester, MI 48309, USA
- Department of Physiology, Michigan State University, East Lansing, MI 48824, USA
- Department of Neurology, Wayne State University, Detroit, MI 48202, USA
| | - Zhenggang Zhang
- Department of Neurology, Henry Ford Health System, Detroit, MI 48202, USA; (J.K.); (E.D.B.); (G.D.); (L.Z.); (H.L.); (Q.L.); (L.L.); (M.W.); (J.L.-W.); (M.C.); (Z.Z.)
- Department of Physiology, Michigan State University, East Lansing, MI 48824, USA
- Department of Neurology, Wayne State University, Detroit, MI 48202, USA
| | - Quan Jiang
- Department of Neurology, Henry Ford Health System, Detroit, MI 48202, USA; (J.K.); (E.D.B.); (G.D.); (L.Z.); (H.L.); (Q.L.); (L.L.); (M.W.); (J.L.-W.); (M.C.); (Z.Z.)
- Department of Physics, Oakland University, Rochester, MI 48309, USA
- Department of Radiology, Michigan State University, East Lansing, MI 48824, USA
- Department of Neurology, Wayne State University, Detroit, MI 48202, USA
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3
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White KS, Walker JA, Wang J, Autissier P, Miller AD, Abuelezan NN, Burrack R, Li Q, Kim WK, Williams KC. Simian immunodeficiency virus-infected rhesus macaques with AIDS co-develop cardiovascular pathology and encephalitis. Front Immunol 2023; 14:1240946. [PMID: 37965349 PMCID: PMC10641955 DOI: 10.3389/fimmu.2023.1240946] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2023] [Accepted: 10/03/2023] [Indexed: 11/16/2023] Open
Abstract
Despite effective antiretroviral therapy, HIV co-morbidities remain where central nervous system (CNS) neurocognitive disorders and cardiovascular disease (CVD)-pathology that are linked with myeloid activation are most prevalent. Comorbidities such as neurocogntive dysfunction and cardiovascular disease (CVD) remain prevalent among people living with HIV. We sought to investigate if cardiac pathology (inflammation, fibrosis, cardiomyocyte damage) and CNS pathology (encephalitis) develop together during simian immunodeficiency virus (SIV) infection and if their co-development is linked with monocyte/macrophage activation. We used a cohort of SIV-infected rhesus macaques with rapid AIDS and demonstrated that SIV encephalitis (SIVE) and CVD pathology occur together more frequently than SIVE or CVD pathology alone. Their co-development correlated more strongly with activated myeloid cells, increased numbers of CD14+CD16+ monocytes, plasma CD163 and interleukin-18 (IL-18) than did SIVE or CVD pathology alone, or no pathology. Animals with both SIVE and CVD pathology had greater numbers of cardiac macrophages and increased collagen and monocyte/macrophage accumulation, which were better correlates of CVD-pathology than SIV-RNA. Animals with SIVE alone had higher levels of activated macrophage biomarkers and cardiac macrophage accumulation than SIVnoE animals. These observations were confirmed in HIV infected individuals with HIV encephalitis (HIVE) that had greater numbers of cardiac macrophages and fibrosis than HIV-infected controls without HIVE. These results underscore the notion that CNS and CVD pathologies frequently occur together in HIV and SIV infection, and demonstrate an unmet need for adjunctive therapies targeting macrophages.
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Affiliation(s)
- Kevin S. White
- Department of Biology, Boston College, Chestnut Hill, MA, United States
| | - Joshua A. Walker
- Department of Biology, Boston College, Chestnut Hill, MA, United States
| | - John Wang
- Department of Biology, Boston College, Chestnut Hill, MA, United States
| | - Patrick Autissier
- Department of Biology, Boston College, Chestnut Hill, MA, United States
| | - Andrew D. Miller
- Department of Biomedical Sciences, Section of Anatomic Physiology, Cornell University College of Veterinary Medicine, Ithaca, NY, United States
| | - Nadia N. Abuelezan
- Connel School of Nursing, Boston College, Chestnut Hill, MA, United States
| | - Rachel Burrack
- Nebraska Center for Virology, School of Biological Sciences, University of Nebraska-Lincoln, Lincoln, NE, United States
| | - Qingsheng Li
- Nebraska Center for Virology, School of Biological Sciences, University of Nebraska-Lincoln, Lincoln, NE, United States
| | - Woong-Ki Kim
- Division of Microbiology, Tulane National Primate Research Center, Covington, LA, United States
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4
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Kaur J, Boyd E, Ding G, Zhang L, Luo H, Li Q, Li L, Wei M, Landschoot-Ward J, Chopp M, Zhang Z, Jiang Q. The Association between Glymphatic System and Perivascular Macrophages in Brain Waste Clearance. RESEARCH SQUARE 2023:rs.3.rs-3390074. [PMID: 37886481 PMCID: PMC10602168 DOI: 10.21203/rs.3.rs-3390074/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/28/2023]
Abstract
The glymphatic system suggests the convective bulk flow of cerebrospinal fluid (CSF) through perivascular spaces and the interstitial spaces of the brain parenchyma for the rapid removal of toxic waste solutes from the brain. However, the presence of convective bulk flow within the brain interstitial spaces is still under debate. We first addressed this argument to determine the involvement of the glymphatic system in brain waste clearance utilizing contrast-enhanced 3D T1-weighted imaging (T1WI), diffusion tensor imaging (DTI), and confocal microscopy imaging. Furthermore, perivascular macrophages (PVMs), which are immune cells located within perivascular spaces, have not been thoroughly explored for their association with the glymphatic system. Therefore, we investigated tracer uptake by PVMs in the perivascular spaces of both the arteries/arterioles and veins/venules and the potential association of PVMs in assisting the glymphatic system for interstitial waste clearance. Our findings demonstrated that both convective bulk flow and diffusion are responsible for the clearance of interstitial waste solutes from the brain parenchyma. Furthermore, our results suggested that PVMs play an important function in glymphatic system-mediated interstitial waste clearance. The glymphatic system and PVMs could be targeted to enhance interstitial waste clearance in patients with waste-associated neurological conditions and aging.
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Affiliation(s)
- Jasleen Kaur
- Department of Neurology, Henry Ford Health System, Detroit, MI, USA
- Department of Physics, Oakland University, Rochester, MI, USA
| | - Edward Boyd
- Department of Neurology, Henry Ford Health System, Detroit, MI, USA
- Department of Radiology, Michigan State University, Lasing, MI, USA
| | - Guangliang Ding
- Department of Neurology, Henry Ford Health System, Detroit, MI, USA
- Department of Radiology, Michigan State University, Lasing, MI, USA
| | - Li Zhang
- Department of Neurology, Henry Ford Health System, Detroit, MI, USA
- Department of Physiology, Michigan State University, Lasing, MI, USA
| | - Hao Luo
- Department of Neurology, Henry Ford Health System, Detroit, MI, USA
| | - Qingjiang Li
- Department of Neurology, Henry Ford Health System, Detroit, MI, USA
| | - Lian Li
- Department of Neurology, Henry Ford Health System, Detroit, MI, USA
| | - Min Wei
- Department of Neurology, Henry Ford Health System, Detroit, MI, USA
| | | | - Michael Chopp
- Department of Neurology, Henry Ford Health System, Detroit, MI, USA
- Department of Physics, Oakland University, Rochester, MI, USA
- Department of Physiology, Michigan State University, Lasing, MI, USA
- Department of Neurology, Wayne State University, Detroit, MI, USA
| | - Zhenggang Zhang
- Department of Neurology, Henry Ford Health System, Detroit, MI, USA
- Department of Physiology, Michigan State University, Lasing, MI, USA
- Department of Neurology, Wayne State University, Detroit, MI, USA
| | - Quan Jiang
- Department of Neurology, Henry Ford Health System, Detroit, MI, USA
- Department of Physics, Oakland University, Rochester, MI, USA
- Department of Radiology, Michigan State University, Lasing, MI, USA
- Department of Neurology, Wayne State University, Detroit, MI, USA
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5
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Wahl A, Al-Harthi L. HIV infection of non-classical cells in the brain. Retrovirology 2023; 20:1. [PMID: 36639783 PMCID: PMC9840342 DOI: 10.1186/s12977-023-00616-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2022] [Accepted: 01/02/2023] [Indexed: 01/15/2023] Open
Abstract
HIV-associated neurological disorders (HAND) affect up to 50% of people living with HIV (PLWH), even in the era of combination antiretroviral therapy (cART). HIV-DNA can be detected in the cerebral spinal fluid (CSF) of approximately half of aviremic ART-suppressed PLWH and its presence is associated with poorer neurocognitive performance. HIV DNA + and HIV RNA + cells have also been observed in postmortem brain tissue of individuals with sustained cART suppression. In this review, we provide an overview of how HIV invades the brain and HIV infection of resident brain glial cells (astrocytes and microglia). We also discuss the role of resident glial cells in persistent neuroinflammation and HAND in PLWH and their potential contribution to the HIV reservoir. HIV eradication strategies that target persistently infected glia cells will likely be needed to achieve HIV cure.
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Affiliation(s)
- Angela Wahl
- grid.10698.360000000122483208International Center for the Advancement of Translational Science, University of North Carolina at Chapel Hill, Chapel Hill, NC USA ,grid.10698.360000000122483208Division of Infectious Diseases, Department of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC USA ,grid.10698.360000000122483208Center for AIDS Research, University of North Carolina at Chapel Hill, Chapel Hill, NC USA
| | - Lena Al-Harthi
- grid.240684.c0000 0001 0705 3621Department of Microbial Pathogens and Immunity, Rush University Medical Center, Chicago, IL USA
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6
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Sharma V, Creegan M, Tokarev A, Hsu D, Slike BM, Sacdalan C, Chan P, Spudich S, Ananworanich J, Eller MA, Krebs SJ, Vasan S, Bolton DL. Cerebrospinal fluid CD4+ T cell infection in humans and macaques during acute HIV-1 and SHIV infection. PLoS Pathog 2021; 17:e1010105. [PMID: 34874976 PMCID: PMC8683024 DOI: 10.1371/journal.ppat.1010105] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2021] [Revised: 12/17/2021] [Accepted: 11/10/2021] [Indexed: 12/30/2022] Open
Abstract
HIV-1 replication within the central nervous system (CNS) impairs neurocognitive function and has the potential to establish persistent, compartmentalized viral reservoirs. The origins of HIV-1 detected in the CNS compartment are unknown, including whether cells within the cerebrospinal fluid (CSF) produce virus. We measured viral RNA+ cells in CSF from acutely infected macaques longitudinally and people living with early stages of acute HIV-1. Active viral transcription (spliced viral RNA) was present in CSF CD4+ T cells as early as four weeks post-SHIV infection, and among all acute HIV-1 specimens (N = 6; Fiebig III/IV). Replication-inactive CD4+ T cell infection, indicated by unspliced viral RNA in the absence of spliced viral RNA, was even more prevalent, present in CSF of >50% macaques and human CSF at ~10-fold higher frequency than productive infection. Infection levels were similar between CSF and peripheral blood (and lymph nodes in macaques), indicating comparable T cell infection across these compartments. In addition, surface markers of activation were increased on CSF T cells and monocytes and correlated with CSF soluble markers of inflammation. These studies provide direct evidence of HIV-1 replication in CD4+ T cells and broad immune activation in peripheral blood and the CNS during acute infection, likely contributing to early neuroinflammation and reservoir seeding. Thus, early initiation of antiretroviral therapy may not be able to prevent establishment of CNS viral reservoirs and sources of long-term inflammation, important targets for HIV-1 cure and therapeutic strategies. Neurological pathologies are associated with HIV-1 infection and remain common in the ongoing AIDS epidemic. Despite the advent of successful viremia suppression by anti-retroviral therapy, increased life expectancies and co-morbidities have led to higher prevalence of milder forms of neurocognitive dysfunction. How HIV-1 causes neurocognitive dysfunction is currently unclear, though it is widely believed that viral replication within the central nervous system (CNS) prior to therapy triggers these detrimental processes. The appearance of HIV-1 in the cerebrospinal fluid during the earliest stages of infection suggests that these processes may begin very early. Here, we use novel techniques to probe cells for viral infection during the first few weeks of infection in the CNS of humans and animals to determine the source of this virus. We found HIV-1 replication in T cells in the cerebrospinal fluid during this early window. In addition, infected T cells were present at similar frequencies in the CNS and other anatomic compartments, suggesting equilibration of T cell infection levels across these sites and potential for establishment of long-term reservoirs in the CNS. Our study provides new insights to the early events of viral entry and replication in the CNS with implications for subsequent viral persistence and neuronal injury.
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Affiliation(s)
- Vishakha Sharma
- Military HIV Research Program, Walter Reed Army Institute of Research, Silver Spring, Maryland, United States of America
- Henry M. Jackson Foundation for the Advancement of Military Medicine, Bethesda, Maryland, United States of America
| | - Matthew Creegan
- Military HIV Research Program, Walter Reed Army Institute of Research, Silver Spring, Maryland, United States of America
- Henry M. Jackson Foundation for the Advancement of Military Medicine, Bethesda, Maryland, United States of America
| | - Andrey Tokarev
- Military HIV Research Program, Walter Reed Army Institute of Research, Silver Spring, Maryland, United States of America
- Henry M. Jackson Foundation for the Advancement of Military Medicine, Bethesda, Maryland, United States of America
| | - Denise Hsu
- Military HIV Research Program, Walter Reed Army Institute of Research, Silver Spring, Maryland, United States of America
- Henry M. Jackson Foundation for the Advancement of Military Medicine, Bethesda, Maryland, United States of America
- Department of Retrovirology, Armed Forces Research Institute of Medical Sciences, Bangkok, Thailand
| | - Bonnie M. Slike
- Military HIV Research Program, Walter Reed Army Institute of Research, Silver Spring, Maryland, United States of America
- Henry M. Jackson Foundation for the Advancement of Military Medicine, Bethesda, Maryland, United States of America
| | - Carlo Sacdalan
- Institute of HIV Research and Innovation, Bangkok, Thailand
| | - Phillip Chan
- Institute of HIV Research and Innovation, Bangkok, Thailand
| | - Serena Spudich
- Department of Neurology, Yale University, New Haven, Connecticut, United States of America
| | - Jintanat Ananworanich
- Military HIV Research Program, Walter Reed Army Institute of Research, Silver Spring, Maryland, United States of America
- Henry M. Jackson Foundation for the Advancement of Military Medicine, Bethesda, Maryland, United States of America
| | - Michael A. Eller
- Military HIV Research Program, Walter Reed Army Institute of Research, Silver Spring, Maryland, United States of America
- Henry M. Jackson Foundation for the Advancement of Military Medicine, Bethesda, Maryland, United States of America
| | - Shelly J. Krebs
- Military HIV Research Program, Walter Reed Army Institute of Research, Silver Spring, Maryland, United States of America
- Henry M. Jackson Foundation for the Advancement of Military Medicine, Bethesda, Maryland, United States of America
| | - Sandhya Vasan
- Military HIV Research Program, Walter Reed Army Institute of Research, Silver Spring, Maryland, United States of America
- Henry M. Jackson Foundation for the Advancement of Military Medicine, Bethesda, Maryland, United States of America
- Department of Retrovirology, Armed Forces Research Institute of Medical Sciences, Bangkok, Thailand
| | - Diane L. Bolton
- Military HIV Research Program, Walter Reed Army Institute of Research, Silver Spring, Maryland, United States of America
- Henry M. Jackson Foundation for the Advancement of Military Medicine, Bethesda, Maryland, United States of America
- * E-mail:
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7
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Yadav-Samudrala BJ, Fitting S. Mini-review: The therapeutic role of cannabinoids in neuroHIV. Neurosci Lett 2021; 750:135717. [PMID: 33587986 DOI: 10.1016/j.neulet.2021.135717] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2020] [Revised: 02/02/2021] [Accepted: 02/04/2021] [Indexed: 12/25/2022]
Abstract
In the era of combined antiretroviral therapy (cART), human immunodeficiency virus type 1 (HIV-1) is considered a chronic disease with an inflammatory component that specifically targets the brain and causes a high prevalence of HIV-1-associated neurocognitive disorders (HAND). The endocannabinoid (eCB) system has attracted interest as a target for treatment of neurodegenerative disorders, due to the potential anti-inflammatory and neuroprotective properties of cannabinoids, including its potential therapeutic use in HIV-1 neuropathogenesis. In this review, we summarize what is currently known about the structural and functional changes of the eCB system under conditions of HAND. This will be followed by summarizing the current clinical and preclinical findings on the effects of cannabis use and cannabinoids in the context of HIV-1 infection, with specifically focusing on viral load, cognition, inflammation, and neuroprotection. Lastly, we present some potential future directions to better understand the involvement of the eCB system and the role that cannabis use and cannabinoids play in neuroHIV.
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Affiliation(s)
- Barkha J Yadav-Samudrala
- Department of Psychology and Neuroscience, University of North Carolina, Chapel Hill, NC, 27599, USA
| | - Sylvia Fitting
- Department of Psychology and Neuroscience, University of North Carolina, Chapel Hill, NC, 27599, USA.
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8
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Yang T, Guo R, Zhang F. Brain perivascular macrophages: Recent advances and implications in health and diseases. CNS Neurosci Ther 2019; 25:1318-1328. [PMID: 31749316 PMCID: PMC7154594 DOI: 10.1111/cns.13263] [Citation(s) in RCA: 54] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2019] [Revised: 10/24/2019] [Accepted: 10/25/2019] [Indexed: 12/20/2022] Open
Abstract
Brain perivascular macrophages (PVMs) belong to a distinct population of brain‐resident myeloid cells located within the perivascular space surrounding arterioles and venules. Their characterization depends on the combination of anatomical localization, phagocytic capacity, and molecular markers. Under physiological status, they provide structural and functional support for maintaining brain homeostasis, including facilitation of blood‐brain barrier integrity and lymphatic drainage, and exertion of immune functions such as phagocytosis and antigen presentation. Increasing evidence also implicates their specific roles in diseased brain, ranging from cerebrovascular diseases, Aβ pathologies, infections, and autoimmunity. Collectively, PVMs are key components of the brain‐resident immune system, actively participate in a broad‐spectrum of processes in normal and diseased status. Details of the processes are largely underexplored. Targeting PVMs would lead to new insights and be a promising strategy for a broad array of human diseases.
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Affiliation(s)
- Tuo Yang
- Department of Neurology, Pittsburgh Institute of Brain Disorders and Recovery, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Ruiming Guo
- Department of Neurology, Pittsburgh Institute of Brain Disorders and Recovery, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Feng Zhang
- Department of Neurology, Pittsburgh Institute of Brain Disorders and Recovery, University of Pittsburgh, Pittsburgh, Pennsylvania
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9
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Delery E, Bohannon DG, Irons DL, Allers C, Sugimoto C, Cai Y, Merino KM, Amedee AM, Veazey RS, MacLean A, Kuroda MJ, Kim WK. Lack of susceptibility in neonatally infected rhesus macaques to simian immunodeficiency virus-induced encephalitis. J Neurovirol 2019; 25:578-588. [PMID: 31119711 PMCID: PMC6751025 DOI: 10.1007/s13365-019-00755-w] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2018] [Revised: 02/15/2019] [Accepted: 04/23/2019] [Indexed: 12/18/2022]
Abstract
Despite combination antiretroviral therapies making HIV a chronic rather than terminal condition for many people, the prevalence of HIV-associated neurocognitive disorders (HAND) is increasing. This is especially problematic for children living with HIV. Children diagnosed HAND rarely display the hallmark pathology of HIV encephalitis in adults, namely infected macrophages and multinucleated giant cells in the brain. This finding has also been documented in rhesus macaques infected perinatally with simian immunodeficiency virus (SIV). However, the extent and mechanisms of lack of susceptibility to encephalitis in perinatally HIV-infected children remain unclear. In the current study, we compared brains of macaques infected with pathogenic strains of SIV at different ages to determine neuropathology, correlates of neuroinflammation, and potential underlying mechanisms. Encephalitis was not found in the macaques infected within 24 h of birth despite similar high plasma viral load and high monocyte turnover. Macaques developed encephalitis only when they were infected after 4 months of age. Lower numbers of CCR5-positive cells in the brain, combined with a less leaky blood-brain barrier, may be responsible for the decreased virus infection in the brain and consequently the absence of encephalitis in newborn macaques infected with SIV.
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MESH Headings
- Age Factors
- Animals
- Animals, Newborn
- Blood-Brain Barrier/immunology
- Blood-Brain Barrier/pathology
- Blood-Brain Barrier/virology
- Brain Stem/immunology
- Brain Stem/pathology
- Brain Stem/virology
- Capillary Permeability/immunology
- Disease Resistance
- Encephalitis, Viral/genetics
- Encephalitis, Viral/immunology
- Encephalitis, Viral/pathology
- Encephalitis, Viral/virology
- Frontal Lobe/immunology
- Frontal Lobe/pathology
- Frontal Lobe/virology
- Gene Expression
- Macaca mulatta/virology
- Macrophages/immunology
- Macrophages/pathology
- Macrophages/virology
- Monocytes/immunology
- Monocytes/pathology
- Monocytes/virology
- RNA, Viral/genetics
- RNA, Viral/metabolism
- Receptors, CCR5/genetics
- Receptors, CCR5/immunology
- Receptors, Virus/genetics
- Receptors, Virus/immunology
- Simian Acquired Immunodeficiency Syndrome/genetics
- Simian Acquired Immunodeficiency Syndrome/immunology
- Simian Acquired Immunodeficiency Syndrome/pathology
- Simian Acquired Immunodeficiency Syndrome/virology
- Simian Immunodeficiency Virus/pathogenicity
- Simian Immunodeficiency Virus/physiology
- Viral Load
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Affiliation(s)
- Elizabeth Delery
- Tulane National Primate Research Center, Covington, LA, USA
- Department of Microbiology & Immunology, Tulane Medical School, New Orleans, LA, USA
| | - Diana G Bohannon
- Department of Microbiology and Molecular Cell Biology, Eastern Virginia Medical School, Norfolk, VA, USA
| | - Derek L Irons
- Department of Microbiology and Molecular Cell Biology, Eastern Virginia Medical School, Norfolk, VA, USA
| | | | - Chie Sugimoto
- Tulane National Primate Research Center, Covington, LA, USA
- Dokkyo Medical University, Tochigi, Japan
| | - Yanhui Cai
- Tulane National Primate Research Center, Covington, LA, USA
- The Wistar Institute, Philadelphia, PA, USA
| | | | - Angela M Amedee
- Louisiana State University School of Medicine, New Orleans, LA, USA
| | | | - Andrew MacLean
- Tulane National Primate Research Center, Covington, LA, USA
- Department of Microbiology & Immunology, Tulane Medical School, New Orleans, LA, USA
- Tulane Brain Institute, New Orleans, LA, USA
- Tulane Center for Aging, New Orleans, LA, USA
| | - Marcelo J Kuroda
- Tulane National Primate Research Center, Covington, LA, USA
- University of California Davis, Davis, CA, USA
| | - Woong-Ki Kim
- Department of Microbiology and Molecular Cell Biology, Eastern Virginia Medical School, Norfolk, VA, USA.
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10
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Quitadamo B, Peters PJ, Koch M, Luzuriaga K, Cheng-Mayer C, Clapham PR, Gonzalez-Perez MP. No detection of CD4-independent human immunodeficiency virus 1 envelope glycoproteins in brain tissue of patients with or without neurological complications. Arch Virol 2018; 164:473-482. [PMID: 30415390 PMCID: PMC6369005 DOI: 10.1007/s00705-018-4094-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2018] [Accepted: 10/20/2018] [Indexed: 11/27/2022]
Abstract
Macrophage (mac)-tropic human immnunodeficiency virus type 1 (HIV-1) and simian immnunodeficiency virus (SIV) in brain are associated with neurological disease. Mac-tropic HIV-1 evolves enhanced CD4 interactions that enable macrophage infection via CD4, which is in low abundance. In contrast, mac-tropic SIV is associated with CD4-independent infection via direct CCR5 binding. Recently, mac-tropic simian-human immunodeficiency virus (SHIV) from macaque brain was also reported to infect cells via CCR5 without CD4. Since SHIV envelope proteins (Envs) are derived from HIV-1, we tested more than 100 HIV-1 clade B Envs for infection of CD4-negative, CCR5+ Cf2Th/CCR5 cells. However, no infection was detected. Our data suggest that there are differences in the evolution of mac-tropism in SIV and SHIV compared to HIV-1 clade B due to enhanced interactions with CCR5 and CD4, respectively.
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Affiliation(s)
- Briana Quitadamo
- Biotech 2, Program in Molecular Medicine, University of Massachusetts Medical School, Suite 315, 373 Plantation Street, Worcester, MA, 01605, USA
| | - Paul J Peters
- Biotech 2, Program in Molecular Medicine, University of Massachusetts Medical School, Suite 315, 373 Plantation Street, Worcester, MA, 01605, USA
| | - Matthew Koch
- Biotech 2, Program in Molecular Medicine, University of Massachusetts Medical School, Suite 315, 373 Plantation Street, Worcester, MA, 01605, USA
| | - Katherine Luzuriaga
- Biotech 2, University of Massachusetts Medical School, Suite 318, 373 Plantation Street, Worcester, MA, 01605, USA
| | - Cecilia Cheng-Mayer
- The Aaron Diamond AIDS Research Center, 455 First Avenue, 7th Floor, New York, NY, 10016, USA
| | - Paul R Clapham
- Biotech 2, Program in Molecular Medicine, University of Massachusetts Medical School, Suite 315, 373 Plantation Street, Worcester, MA, 01605, USA
| | - Maria Paz Gonzalez-Perez
- Biotech 2, Program in Molecular Medicine, University of Massachusetts Medical School, Suite 315, 373 Plantation Street, Worcester, MA, 01605, USA.
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11
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Abstract
Endothelins were discovered more than thirty years ago as potent vasoactive compounds. Beyond their well-documented cardiovascular properties, however, the contributions of the endothelin pathway have been demonstrated in several neuroinflammatory processes and the peptides have been reported as clinically relevant biomarkers in neurodegenerative diseases. Several studies report that endothelin-1 significantly contributes to the progression of neuroinflammatory processes, particularly during infections in the central nervous system (CNS), and is associated with a loss of endothelial integrity at the blood brain barrier level. Because of the paucity of clinical trials with endothelin-1 antagonists in several infectious and non-infectious neuroinflammatory diseases, it remains an open question whether the 21 amino acid peptide is a mediator/modulator rather than a biomarker of the progression of neurodegeneration. This review focuses on the potential roles of endothelins in the pathology of neuroinflammatory processes, including infectious diseases of viral, bacterial or parasitic origin in which the synthesis of endothelins or its pharmacology have been investigated from the cell to the bedside in several cases, as well as in non-infectious inflammatory processes such as neurodegenerative disorders like Alzheimers Disease or central nervous system vasculitis.
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12
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Abstract
Viral infection in the brain can be acute or chronic, with the responses often producing foci of increasingly cytotoxic inflammation. This can lead to effects beyond the central nervous system (CNS). To stimulate discussion, this commentary addresses four questions: What drives the development of human immunodeficiency virus (HIV)-associated neurocognitive disorders, does the phenotype of macrophages in the CNS spur development of HIV encephalitis (HIVE), does continual activation of astrocytes drive the development of HIV-associated neurocognitive disorders/subclinical disease, and neuroinflammation: friend or foe? A unifying theory that connects each question is the issue of continued activation of glial cells, even in the apparent absence of simian immunodeficiency virus/HIV in the CNS. As the CNS innate immune system is distinct from the rest of the body, it is likely there could be a number of activation profiles not observed elsewhere.
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Affiliation(s)
- Elizabeth C. Delery
- Tulane National Primate Research Center, Covington, Louisiana
- Tulane Program in Biomedical Sciences, Tulane Medical School, New Orleans, Louisiana
- Department of Microbiology and Immunology, Tulane Medical School, New Orleans, Louisiana
| | - Andrew G. MacLean
- Tulane National Primate Research Center, Covington, Louisiana
- Tulane Program in Biomedical Sciences, Tulane Medical School, New Orleans, Louisiana
- Department of Microbiology and Immunology, Tulane Medical School, New Orleans, Louisiana
- Tulane Brain Institute, Tulane University, New Orleans, Louisiana
- Center for Aging, School of Medicine, Tulane University, New Orleans, Louisiana
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13
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Brese RL, Gonzalez-Perez MP, Koch M, O'Connell O, Luzuriaga K, Somasundaran M, Clapham PR, Dollar JJ, Nolan DJ, Rose R, Lamers SL. Ultradeep single-molecule real-time sequencing of HIV envelope reveals complete compartmentalization of highly macrophage-tropic R5 proviral variants in brain and CXCR4-using variants in immune and peripheral tissues. J Neurovirol 2018; 24:439-453. [PMID: 29687407 PMCID: PMC7281851 DOI: 10.1007/s13365-018-0633-5] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2017] [Revised: 02/28/2018] [Accepted: 03/19/2018] [Indexed: 01/07/2023]
Abstract
Despite combined antiretroviral therapy (cART), HIV+ patients still develop neurological disorders, which may be due to persistent HIV infection and selective evolution in brain tissues. Single-molecule real-time (SMRT) sequencing technology offers an improved opportunity to study the relationship among HIV isolates in the brain and lymphoid tissues because it is capable of generating thousands of long sequence reads in a single run. Here, we used SMRT sequencing to generate ~ 50,000 high-quality full-length HIV envelope sequences (> 2200 bp) from seven autopsy tissues from an HIV+/cART+ subject, including three brain and four non-brain sites. Sanger sequencing was used for comparison with SMRT data and to clone functional pseudoviruses for in vitro tropism assays. Phylogenetic analysis demonstrated that brain-derived HIV was compartmentalized from HIV outside the brain and that the variants from each of the three brain tissues grouped independently. Variants from all peripheral tissues were intermixed on the tree but independent of the brain clades. Due to the large number of sequences, a clustering analysis at three similarity thresholds (99, 99.5, and 99.9%) was also performed. All brain sequences clustered exclusive of any non-brain sequences at all thresholds; however, frontal lobe sequences clustered independently of occipital and parietal lobes. Translated sequences revealed potentially functional differences between brain and non-brain sequences in the location of putative N-linked glycosylation sites (N-sites), V1 length, V3 charge, and the number of V4 N-sites. All brain sequences were predicted to use the CCR5 co-receptor, while most non-brain sequences were predicted to use CXCR4 co-receptor. Tropism results were confirmed by in vitro infection assays. The study is the first to use a SMRT sequencing approach to study HIV compartmentalization in tissues and supports other reports of limited trafficking between brain and non-brain sequences during cART. Due to the long sequence length, we could observe changes along the entire envelope gene, likely caused by differential selective pressure in the brain that may contribute to neurological disease.
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Affiliation(s)
- Robin L Brese
- Program in Molecular Medicine, University of Massachusetts Medical School, Biotech 2, 373 Plantation Street, Worcester, MA, 01605, USA
| | - Maria Paz Gonzalez-Perez
- Program in Molecular Medicine, University of Massachusetts Medical School, Biotech 2, 373 Plantation Street, Worcester, MA, 01605, USA
| | - Matthew Koch
- Program in Molecular Medicine, University of Massachusetts Medical School, Biotech 2, 373 Plantation Street, Worcester, MA, 01605, USA
| | - Olivia O'Connell
- Program in Molecular Medicine, University of Massachusetts Medical School, Biotech 2, 373 Plantation Street, Worcester, MA, 01605, USA
| | - Katherine Luzuriaga
- Program in Molecular Medicine, University of Massachusetts Medical School, Biotech 2, 373 Plantation Street, Worcester, MA, 01605, USA
| | - Mohan Somasundaran
- Program in Molecular Medicine, University of Massachusetts Medical School, Biotech 2, 373 Plantation Street, Worcester, MA, 01605, USA
| | - Paul R Clapham
- Program in Molecular Medicine, University of Massachusetts Medical School, Biotech 2, 373 Plantation Street, Worcester, MA, 01605, USA
| | | | - David J Nolan
- Bioinfoexperts, LLC, 718 Bayou Ln, Thibodaux, LA, 70301, USA
| | - Rebecca Rose
- Bioinfoexperts, LLC, 718 Bayou Ln, Thibodaux, LA, 70301, USA.
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14
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Central Nervous System Inflammation and Infection during Early, Nonaccelerated Simian-Human Immunodeficiency Virus Infection in Rhesus Macaques. J Virol 2018; 92:JVI.00222-18. [PMID: 29563297 PMCID: PMC5952152 DOI: 10.1128/jvi.00222-18] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2018] [Accepted: 03/17/2018] [Indexed: 02/02/2023] Open
Abstract
Studies utilizing highly pathogenic simian immunodeficiency virus (SIV) and simian-human immunodeficiency virus (SHIV) have largely focused on the immunopathology of the central nervous system (CNS) during end-stage neurological AIDS and SIV encephalitis. However, this may not model pathophysiology in earlier stages of infection. In this nonaccelerated SHIV model, plasma SHIV RNA levels and peripheral blood and colonic CD4+ T cell counts mirrored early human immunodeficiency virus (HIV) infection in humans. At 12 weeks postinfection, cerebrospinal fluid (CSF) detection of SHIV RNA and elevations in IP-10 and MCP-1 reflected a discrete neurovirologic process. Immunohistochemical staining revealed a diffuse, low-level CD3+ CD4− cellular infiltrate in the brain parenchyma without a concomitant increase in CD68/CD163+ monocytes, macrophages, and activated microglial cells. Rare SHIV-infected cells in the brain parenchyma and meninges were identified by RNAScope in situ hybridization. In the meninges, there was also a trend toward increased CD4+ infiltration in SHIV-infected animals but no differences in CD68/CD163+ cells between SHIV-infected and uninfected control animals. These data suggest that in a model that closely recapitulates human disease, CNS inflammation and SHIV in CSF are predominantly mediated by T cell-mediated processes during early infection in both brain parenchyma and meninges. Because SHIV expresses an HIV rather than SIV envelope, this model could inform studies to understand potential HIV cure strategies targeting the HIV envelope. IMPORTANCE Animal models of the neurologic effects of HIV are needed because brain pathology is difficult to assess in humans. Many current models focus on the effects of late-stage disease utilizing SIV. In the era of antiretroviral therapy, manifestations of late-stage HIV are less common. Furthermore, new interventions, such as monoclonal antibodies and therapeutic vaccinations, target HIV envelope. We therefore describe a new model of central nervous system involvement in rhesus macaques infected with SHIV expressing HIV envelope in earlier, less aggressive stages of disease. Here, we demonstrate that SHIV mimics the early clinical course in humans and that early neurologic inflammation is characterized by predominantly T cell-mediated inflammation accompanied by SHIV infection in the brain and meninges. This model can be utilized to assess the effect of novel therapies targeted to HIV envelope on reducing brain inflammation before end-stage disease.
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15
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Insights into the Impact of CD8 + Immune Modulation on Human Immunodeficiency Virus Evolutionary Dynamics in Distinct Anatomical Compartments by Using Simian Immunodeficiency Virus-Infected Macaque Models of AIDS Progression. J Virol 2017; 91:JVI.01162-17. [PMID: 28931681 DOI: 10.1128/jvi.01162-17] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2017] [Accepted: 08/24/2017] [Indexed: 12/16/2022] Open
Abstract
A thorough understanding of the role of human immunodeficiency virus (HIV) intrahost evolution in AIDS pathogenesis has been limited by the need for longitudinally sampled viral sequences from the vast target space within the host, which are often difficult to obtain from human subjects. CD8+ lymphocyte-depleted macaques infected with simian immunodeficiency virus (SIV) provide an increasingly utilized model of pathogenesis due to clinical manifestations similar to those for HIV-1 infection and AIDS progression, as well as a characteristic rapid disease onset. Comparison of this model with SIV-infected non-CD8+ lymphocyte-depleted macaques also provides a unique opportunity to investigate the role of CD8+ cells in viral evolution and population dynamics throughout the duration of infection. Using several different phylogenetic methods, we analyzed viral gp120 sequences obtained from extensive longitudinal sampling of multiple tissues and enriched leukocyte populations from SIVmac251-infected macaques with or without CD8+ lymphocyte depletion. SIV evolutionary and selection patterns in non-CD8+ lymphocyte-depleted animals were characterized by sequential population turnover and continual viral adaptation, a scenario readily comparable to intrahost evolutionary patterns during human HIV infection in the absence of antiretroviral therapy. Alternatively, animals that were depleted of CD8+ lymphocytes exhibited greater variation in population dynamics among tissues and cell populations over the course of infection. Our findings highlight the major role for CD8+ lymphocytes in prolonging disease progression through continual control of SIV subpopulations from various anatomical compartments and the potential for greater independent viral evolutionary behavior among these compartments in response to immune modulation.IMPORTANCE Although developments in combined antiretroviral therapy (cART) strategies have successfully prolonged the time to AIDS onset in HIV-1-infected individuals, a functional cure has yet to be found. Improvement of drug interventions for a virus that is able to infect a wide range of tissues and cell types requires a thorough understanding of viral adaptation and infection dynamics within this target milieu. Although it is difficult to accomplish in the human host, longitudinal sampling of multiple anatomical locations is readily accessible in the SIV-infected macaque models of neuro-AIDS. The significance of our research is in identifying the impact of immune modulation, through differing immune selective pressures, on viral evolutionary behavior in a multitude of anatomical compartments. The results provide evidence encouraging the development of a more sophisticated model that considers a network of individual viral subpopulations within the host, with differing infection and transmission dynamics, which is necessary for more effective treatment strategies.
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16
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Ruhanya V, Jacobs GB, Glashoff RH, Engelbrecht S. Clinical Relevance of Total HIV DNA in Peripheral Blood Mononuclear Cell Compartments as a Biomarker of HIV-Associated Neurocognitive Disorders (HAND). Viruses 2017; 9:E324. [PMID: 29088095 PMCID: PMC5707531 DOI: 10.3390/v9110324] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2017] [Revised: 10/24/2017] [Accepted: 10/26/2017] [Indexed: 12/19/2022] Open
Abstract
The pathogenesis of HIV-associated neurocognitive disorders is complex and multifactorial. It is hypothesized that the critical events initiating this condition occur outside the brain, particularly in the peripheral blood. Diagnoses of HIV-induced neurocognitive disorders largely rely on neuropsychometric assessments, which are not precise. Total HIV DNA in the peripheral blood mononuclear cells (PBMCs), quantified by PCR, correlate with disease progression, which is a promising biomarker to predict HAND. Numerous PCR assays for HIV DNA in cell compartments are prone to variation due to the lack of standardization and, therefore, their utility in predicting HAND produced different outcomes. This review evaluates the clinical relevance of total HIV DNA in circulating mononuclear cells using different published quantitative PCR (qPCR) protocols. The rationale is to shed light on the most appropriate assays and sample types used to accurately quantify HIV DNA load, which predicts severity of neurocognitive impairment. The role of monocytes as a vehicle for trafficking HIV into the CNS makes it the most suitable sample for determining a HAND associated reservoir. Studies have also shown significant associations between monocyte HIV DNA levels with markers of neurodamage. However, qPCR assays using PBMCs are cheaper and available commercially, thus could be beneficial in clinical settings. There is need, however, to standardise DNA extraction, normalisation and limit of detection.
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Affiliation(s)
- Vurayai Ruhanya
- Division of Medical Virology, Department of Pathology, Faculty of Medicine and Health Sciences, Stellenbosch University, Francie van Zijl Avenue, P.O. Box 241, Cape Town 8000, South Africa.
- Department of Medical Microbiology, College of Health Sciences, University of Zimbabwe, P.O. Box A178, Avondale Harare 00263, Zimbabwe.
| | - Graeme B Jacobs
- Division of Medical Virology, Department of Pathology, Faculty of Medicine and Health Sciences, Stellenbosch University, Francie van Zijl Avenue, P.O. Box 241, Cape Town 8000, South Africa.
| | - Richard H Glashoff
- Division of Medical Microbiology and Immunology, Department of Pathology, Faculty of Medicine and Health Sciences, Stellenbosch University, Francie van Zijl Avenue, P.O. Box 241, Cape Town 8000, South Africa.
- Division of Medical Microbiology and Immunology, National Health Laboratory Service (NHLS), Tygerberg Business Unit, P.O. Box 241, Cape Town 8000, South Africa.
| | - Susan Engelbrecht
- Division of Medical Virology, Department of Pathology, Faculty of Medicine and Health Sciences, Stellenbosch University, Francie van Zijl Avenue, P.O. Box 241, Cape Town 8000, South Africa.
- Division of Medical Virology, National Health Laboratory Service (NHLS), Tygerberg Business Unit, P.O. Box 241, Cape Town 8000, South Africa.
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17
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Identification of Emerging Macrophage-Tropic HIV-1 R5 Variants in Brain Tissue of AIDS Patients without Severe Neurological Complications. J Virol 2017; 91:JVI.00755-17. [PMID: 28768859 DOI: 10.1128/jvi.00755-17] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2017] [Accepted: 07/19/2017] [Indexed: 11/20/2022] Open
Abstract
Untreated HIV-positive (HIV-1+) individuals frequently suffer from HIV-associated neurocognitive disorders (HAND), with about 30% of AIDS patients suffering severe HIV-associated dementias (HADs). Antiretroviral therapy has greatly reduced the incidence of HAND and HAD. However, there is a continuing problem of milder neurocognitive impairments in treated HIV+ patients that may be increasing with long-term therapy. In the present study, we investigated whether envelope (env) genes could be amplified from proviral DNA or RNA derived from brain tissue of 12 individuals with normal neurology or minor neurological conditions (N/MC individuals). The tropism and characteristics of the brain-derived Envs were then investigated and compared to those of Envs derived from immune tissue. We showed that (i) macrophage-tropic R5 Envs could be detected in the brain tissue of 4/12 N/MC individuals, (ii) macrophage-tropic Envs in brain tissue formed compartmentalized clusters distinct from non-macrophage-tropic (non-mac-tropic) Envs recovered from the spleen or brain, (iii) the evidence was consistent with active viral expression by macrophage-tropic variants in the brain tissue of some individuals, and (iv) Envs from immune tissue of the N/MC individuals were nearly all tightly non-mac-tropic, contrasting with previous data for neuro-AIDS patients where immune tissue Envs mediated a range of macrophage infectivities, from background levels to modest infection, with a small number of Envs from some patients mediating high macrophage infection levels. In summary, the data presented here show that compartmentalized and active macrophage-tropic HIV-1 variants are present in the brain tissue of individuals before neurological disease becomes overt or serious.IMPORTANCE The detection of highly compartmentalized macrophage-tropic R5 Envs in the brain tissue of HIV patients without serious neurological disease is consistent with their emergence from a viral population already established there, perhaps from early disease. The detection of active macrophage-tropic virus expression, and probably replication, indicates that antiretroviral drugs with optimal penetration through the blood-brain barrier should be considered even for patients without neurological disease (neuro-disease). Finally, our data are consistent with the brain forming a sanctuary site for latent virus and low-level viral replication in the absence of neuro-disease.
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18
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Feline Immunodeficiency Virus Neuropathogenesis: A Model for HIV-Induced CNS Inflammation and Neurodegeneration. Vet Sci 2017; 4:vetsci4010014. [PMID: 29056673 PMCID: PMC5606611 DOI: 10.3390/vetsci4010014] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2017] [Revised: 02/22/2017] [Accepted: 03/01/2017] [Indexed: 12/11/2022] Open
Abstract
Feline Immunodeficiency virus (FIV), similar to its human analog human immunodeficiency virus (HIV), enters the central nervous system (CNS) soon after infection and establishes a protected viral reservoir. The ensuing inflammation and damage give rise to varying degrees of cognitive decline collectively known as HIV-associated neurocognitive disorders (HAND). Because of the similarities to HIV infection and disease, FIV has provided a useful model for both in vitro and in vivo studies of CNS infection, inflammation and pathology. This mini review summarizes insights gained from studies of early infection, immune cell trafficking, inflammation and the mechanisms of neuropathogenesis. Advances in our understanding of these processes have contributed to the development of therapeutic interventions designed to protect neurons and regulate inflammatory activity.
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19
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Marks WD, Paris JJ, Schier CJ, Denton MD, Fitting S, McQuiston AR, Knapp PE, Hauser KF. HIV-1 Tat causes cognitive deficits and selective loss of parvalbumin, somatostatin, and neuronal nitric oxide synthase expressing hippocampal CA1 interneuron subpopulations. J Neurovirol 2016; 22:747-762. [PMID: 27178324 PMCID: PMC5107352 DOI: 10.1007/s13365-016-0447-2] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2015] [Revised: 04/02/2016] [Accepted: 04/10/2016] [Indexed: 02/08/2023]
Abstract
Memory deficits are characteristic of HIV-associated neurocognitive disorders (HAND) and co-occur with hippocampal pathology. The HIV-1 transactivator of transcription (Tat), a regulatory protein, plays a significant role in these events, but the cellular mechanisms involved are poorly understood. Within the hippocampus, diverse populations of interneurons form complex networks; even subtle disruptions can drastically alter synaptic output, resulting in behavioral dysfunction. We hypothesized that HIV-1 Tat would impair cognitive behavior and injure specific hippocampal interneuron subtypes. Male transgenic mice that inducibly expressed HIV-1 Tat (or non-expressing controls) were assessed for cognitive behavior or had hippocampal CA1 subregions evaluated via interneuron subpopulation markers. Tat exposure decreased spatial memory in a Barnes maze and mnemonic performance in a novel object recognition test. Tat reduced the percentage of neurons expressing neuronal nitric oxide synthase (nNOS) without neuropeptide Y immunoreactivity in the stratum pyramidale and the stratum radiatum, parvalbumin in the stratum pyramidale, and somatostatin in the stratum oriens, which are consistent with reductions in interneuron-specific interneuron type 3 (IS3), bistratified, and oriens-lacunosum-moleculare interneurons, respectively. The findings reveal that an interconnected ensemble of CA1 nNOS-expressing interneurons, the IS3 cells, as well as subpopulations of parvalbumin- and somatostatin-expressing interneurons are preferentially vulnerable to HIV-1 Tat. Importantly, the susceptible interneurons form a microcircuit thought to be involved in feedback inhibition of CA1 pyramidal cells and gating of CA1 pyramidal cell inputs. The identification of vulnerable CA1 hippocampal interneurons may provide novel insight into the basic mechanisms underlying key functional and neurobehavioral deficits associated with HAND.
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Affiliation(s)
- William D Marks
- Department of Pharmacology & Toxicology, Virginia Commonwealth University School of Medicine, Kontos Medical Sciences Building, 1217 East Marshall Street, Richmond, VA, 23298-0613, USA
| | - Jason J Paris
- Department of Pharmacology & Toxicology, Virginia Commonwealth University School of Medicine, Kontos Medical Sciences Building, 1217 East Marshall Street, Richmond, VA, 23298-0613, USA
| | - Christina J Schier
- Department of Pharmacology & Toxicology, Virginia Commonwealth University School of Medicine, Kontos Medical Sciences Building, 1217 East Marshall Street, Richmond, VA, 23298-0613, USA
| | - Melissa D Denton
- Department of Pharmacology & Toxicology, Virginia Commonwealth University School of Medicine, Kontos Medical Sciences Building, 1217 East Marshall Street, Richmond, VA, 23298-0613, USA
| | - Sylvia Fitting
- Department of Psychology & Neuroscience, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599-3270, USA
| | - A Rory McQuiston
- Department of Anatomy & Neurobiology, Virginia Commonwealth University School of Medicine, Richmond, VA, 23298-0709, USA
| | - Pamela E Knapp
- Department of Pharmacology & Toxicology, Virginia Commonwealth University School of Medicine, Kontos Medical Sciences Building, 1217 East Marshall Street, Richmond, VA, 23298-0613, USA
- Department of Anatomy & Neurobiology, Virginia Commonwealth University School of Medicine, Richmond, VA, 23298-0709, USA
- Institute for Drug and Alcohol Studies, Virginia Commonwealth University, Richmond, VA, 23298-0059, USA
| | - Kurt F Hauser
- Department of Pharmacology & Toxicology, Virginia Commonwealth University School of Medicine, Kontos Medical Sciences Building, 1217 East Marshall Street, Richmond, VA, 23298-0613, USA.
- Department of Anatomy & Neurobiology, Virginia Commonwealth University School of Medicine, Richmond, VA, 23298-0709, USA.
- Institute for Drug and Alcohol Studies, Virginia Commonwealth University, Richmond, VA, 23298-0059, USA.
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20
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Proliferation of Perivascular Macrophages Contributes to the Development of Encephalitic Lesions in HIV-Infected Humans and in SIV-Infected Macaques. Sci Rep 2016; 6:32900. [PMID: 27610547 PMCID: PMC5017189 DOI: 10.1038/srep32900] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2016] [Accepted: 08/17/2016] [Indexed: 11/09/2022] Open
Abstract
The aim of the present study was to investigate if macrophage proliferation occurs in the brain during simian immunodeficiency virus (SIV) infection of adult macaques. We examined the expression of the Ki-67 proliferation marker in the brains of uninfected and SIV-infected macaques with or without encephalitis. Double-label immunohistochemistry using antibodies against the pan-macrophage marker CD68 and Ki-67 showed that there was a significant increase in CD68+Ki-67+ cells in macaques with SIV encephalitis (SIVE) compared to uninfected and SIV-infected animals without encephalitis, a trend that was also confirmed in brain samples from patients with HIV encephalitis. Multi-label immunofluorescence for CD163 and Ki-67 confirmed that the vast majority of Ki-67+ nuclei were localized to CD163+ macrophages in perivascular cuffs and lesions. The proliferative capacity of Ki-67+ perivascular macrophages (PVM) was confirmed by their nuclear incorporation of bromodeoxyuridine. Examining SIVE lesions, using double-label immunofluorescence with antibodies against SIV-Gag-p28 and Ki-67, showed that the population of Ki-67+ cells were productively infected and expanded proportionally with lesions. Altogether, this study shows that there are subpopulations of resident PVM that express Ki-67 and are SIV-infected, suggesting a mechanism of macrophage accumulation in the brain via PVM proliferation.
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Evolution of Neuroadaptation in the Periphery and Purifying Selection in the Brain Contribute to Compartmentalization of Simian Immunodeficiency Virus (SIV) in the Brains of Rhesus Macaques with SIV-Associated Encephalitis. J Virol 2016; 90:6112-6126. [PMID: 27122578 DOI: 10.1128/jvi.00137-16] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2016] [Accepted: 04/16/2016] [Indexed: 12/25/2022] Open
Abstract
UNLABELLED The emergence of a distinct subpopulation of human or simian immunodeficiency virus (HIV/SIV) sequences within the brain (compartmentalization) during infection is hypothesized to be linked to AIDS-related central nervous system (CNS) neuropathology. However, the exact evolutionary mechanism responsible for HIV/SIV brain compartmentalization has not been thoroughly investigated. Using extensive viral sampling from several different peripheral tissues and cell types and from three distinct regions within the brain from two well-characterized rhesus macaque models of the neurological complications of HIV infection (neuroAIDS), we have been able to perform in-depth evolutionary analyses that have been unattainable in HIV-infected subjects. The results indicate that, despite multiple introductions of virus into the brain over the course of infection, brain sequence compartmentalization in macaques with SIV-associated CNS neuropathology likely results from late viral entry of virus that has acquired through evolution in the periphery sufficient adaptation for the distinct microenvironment of the CNS. IMPORTANCE HIV-associated neurocognitive disorders remain prevalent among HIV type 1-infected individuals, whereas our understanding of the critical components of disease pathogenesis, such as virus evolution and adaptation, remains limited. Building upon earlier findings of specific viral subpopulations in the brain, we present novel yet fundamental results concerning the evolutionary patterns driving this phenomenon in two well-characterized animal models of neuroAIDS and provide insight into the timing of entry of virus into the brain and selective pressure associated with viral adaptation to this particular microenvironment. Such knowledge is invaluable for therapeutic strategies designed to slow or even prevent neurocognitive impairment associated with AIDS.
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Persisting Rickettsia typhi Causes Fatal Central Nervous System Inflammation. Infect Immun 2016; 84:1615-1632. [PMID: 26975992 DOI: 10.1128/iai.00034-16] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2016] [Accepted: 03/06/2016] [Indexed: 01/03/2023] Open
Abstract
Rickettsioses are emerging febrile diseases caused by obligate intracellular bacteria belonging to the family Rickettsiaceae. Rickettsia typhi belongs to the typhus group (TG) of this family and is the causative agent of endemic typhus, a disease that can be fatal. In the present study, we analyzed the course of R. typhi infection in C57BL/6 RAG1(-/-) mice. Although these mice lack adaptive immunity, they developed only mild and temporary symptoms of disease and survived R. typhi infection for a long period of time. To our surprise, 3 to 4 months after infection, C57BL/6 RAG1(-/-) mice suddenly developed lethal neurological disorders. Analysis of these mice at the time of death revealed high bacterial loads, predominantly in the brain. This was accompanied by a massive expansion of microglia and by neuronal cell death. Furthermore, high numbers of infiltrating CD11b(+) macrophages were detectable in the brain. In contrast to the microglia, these cells harbored R. typhi and showed an inflammatory phenotype, as indicated by inducible nitric oxide synthase (iNOS) expression, which was not observed in the periphery. Having shown that R. typhi persists in immunocompromised mice, we finally asked whether the bacteria are also able to persist in resistant C57BL/6 and BALB/c wild-type mice. Indeed, R. typhi could be recultivated from lung, spleen, and brain tissues from both strains even up to 1 year after infection. This is the first report demonstrating persistence and reappearance of R. typhi, mainly restricted to the central nervous system in immunocompromised mice.
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He X, Shi X, Puthiyakunnon S, Zhang L, Zeng Q, Li Y, Boddu S, Qiu J, Lai Z, Ma C, Xie Y, Long M, Du L, Huang SH, Cao H. CD44-mediated monocyte transmigration across Cryptococcus neoformans-infected brain microvascular endothelial cells is enhanced by HIV-1 gp41-I90 ectodomain. J Biomed Sci 2016; 23:28. [PMID: 26897523 PMCID: PMC4761181 DOI: 10.1186/s12929-016-0247-2] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2015] [Accepted: 02/15/2016] [Indexed: 12/19/2022] Open
Abstract
Background Cryptococcus neoformans (Cn) is an important opportunistic pathogen in the immunocompromised people, including AIDS patients, which leads to fatal cryptococcal meningitis with high mortality rate. Previous researches have shown that HIV-1 gp41-I90 ectodomain can enhance Cn adhesion to and invasion of brain microvascular endothelial cell (BMEC), which constitutes the blood brain barrier (BBB). However, little is known about the role of HIV-1 gp41-I90 in the monocyte transmigration across Cn-infected BBB. In the present study, we provide evidence that HIV-1 gp41-I90 and Cn synergistically enhance monocytes transmigration across the BBB in vitro and in vivo. The underlying mechanisms for this phenomenon require further study. Methods In this study, the enhancing role of HIV-1 gp41-I90 in monocyte transmigration across Cn-infected BBB was demonstrated by performed transmigration assays in vitro and in vivo. Results Our results showed that the transmigration rate of monocytes are positively associated with Cn and/or HIV-1 gp41-I90, the co-exposure (HIV-1 gp41-I90 + Cn) group showed a higher THP-1 transmigration rate (P < 0.01). Using CD44 knock-down HBMEC or CD44 inhibitor Bikunin in the assay, the facilitation of transmigration rates of monocyte enhanced by HIV-1 gp41-I90 was significantly suppressed. Western blotting analysis and biotin/avidin enzyme-linked immunosorbent assays (BA-ELISAs) showed that Cn and HIV-1 gp41-I90 could increase the expression of CD44 and ICAM-1 on the HBMEC. Moreover, Cn and/or HIV-1 gp41-I90 could also induce CD44 redistribution to the membrane lipid rafts. By establishing the mouse cryptococcal meningitis model, we found that HIV-1 gp41-I90 and Cn could synergistically enhance the monocytes transmigration, increase the BBB permeability and injury in vivo. Conclusions Collectively, our findings suggested that HIV-1 gp41-I90 ectodomain can enhance the transmigration of THP-1 through Cn-infected BBB, which may be mediated by CD44. This novel study enlightens the future prospects to elaborate the inflammatory responses induced by HIV-1 gp41-I90 ectodomain and to effectively eliminate the opportunistic infections in AIDS patients.
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Affiliation(s)
- Xiaolong He
- Department of Microbiology, Guangdong Provincial Key Laboratory of Tropical Disease Research, School of Public Health and Tropical Medicine, Southern Medical University, Guangzhou, 510515, China.
| | - Xiaolu Shi
- Department of Microbiology, Guangdong Provincial Key Laboratory of Tropical Disease Research, School of Public Health and Tropical Medicine, Southern Medical University, Guangzhou, 510515, China.
| | - Santhosh Puthiyakunnon
- Department of Microbiology, Guangdong Provincial Key Laboratory of Tropical Disease Research, School of Public Health and Tropical Medicine, Southern Medical University, Guangzhou, 510515, China.
| | - Like Zhang
- Department of Microbiology, Guangdong Provincial Key Laboratory of Tropical Disease Research, School of Public Health and Tropical Medicine, Southern Medical University, Guangzhou, 510515, China.
| | - Qing Zeng
- Department of Microbiology, Guangdong Provincial Key Laboratory of Tropical Disease Research, School of Public Health and Tropical Medicine, Southern Medical University, Guangzhou, 510515, China.
| | - Yan Li
- Department of Microbiology, Guangdong Provincial Key Laboratory of Tropical Disease Research, School of Public Health and Tropical Medicine, Southern Medical University, Guangzhou, 510515, China.
| | - Swapna Boddu
- Department of Microbiology, Guangdong Provincial Key Laboratory of Tropical Disease Research, School of Public Health and Tropical Medicine, Southern Medical University, Guangzhou, 510515, China.
| | - Jiawen Qiu
- Department of Microbiology, Guangdong Provincial Key Laboratory of Tropical Disease Research, School of Public Health and Tropical Medicine, Southern Medical University, Guangzhou, 510515, China.
| | - Zhihao Lai
- The Second School of Clinical Medicine, Southern Medical University, Guangzhou, 510515, China.
| | - Chao Ma
- The Second School of Clinical Medicine, Southern Medical University, Guangzhou, 510515, China.
| | - Yulong Xie
- The Second School of Clinical Medicine, Southern Medical University, Guangzhou, 510515, China.
| | - Min Long
- Department of Microbiology, Guangdong Provincial Key Laboratory of Tropical Disease Research, School of Public Health and Tropical Medicine, Southern Medical University, Guangzhou, 510515, China.
| | - Lei Du
- Department of Microbiology, Guangdong Provincial Key Laboratory of Tropical Disease Research, School of Public Health and Tropical Medicine, Southern Medical University, Guangzhou, 510515, China.
| | - Sheng-He Huang
- Department of Microbiology, Guangdong Provincial Key Laboratory of Tropical Disease Research, School of Public Health and Tropical Medicine, Southern Medical University, Guangzhou, 510515, China. .,Saban Research Institute, Children's Hospital Los Angeles, University of Southern California, Los Angeles, CA, 90027, USA.
| | - Hong Cao
- Department of Microbiology, Guangdong Provincial Key Laboratory of Tropical Disease Research, School of Public Health and Tropical Medicine, Southern Medical University, Guangzhou, 510515, China.
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Nowlin BT, Burdo TH, Midkiff CC, Salemi M, Alvarez X, Williams KC. SIV encephalitis lesions are composed of CD163(+) macrophages present in the central nervous system during early SIV infection and SIV-positive macrophages recruited terminally with AIDS. THE AMERICAN JOURNAL OF PATHOLOGY 2015; 185:1649-65. [PMID: 25963554 DOI: 10.1016/j.ajpath.2015.01.033] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/07/2014] [Revised: 01/16/2015] [Accepted: 01/30/2015] [Indexed: 10/23/2022]
Abstract
Macrophage recruitment to the central nervous system (CNS) during AIDS pathogenesis is poorly understood. We measured the accumulation of brain perivascular (CD163(+)) and inflammatory (MAC387(+)) macrophages in SIV-infected monkeys. Monocyte progenitors were 5-bromo-2'-deoxyuridine (BrdU) labeled in bone marrow, and CNS macrophages were labeled serially with fluorescent dextrans injected into the cisterna magna. MAC387(+) macrophages accumulated in the meninges and choroid plexus in early inflammation and in the perivascular space and SIV encephalitis (SIVE) lesions late. CD163(+) macrophages accumulated in the perivascular space and SIVE lesions with late inflammation. Most of the BrdU(+) cells were MAC387(+); however, CD163(+)BrdU(+) macrophages were present in the meninges and choroid plexus with AIDS. Most (81.6% ± 1.8%) of macrophages in SIVE lesions were present in the CNS before SIVE lesion formation. There was a 2.9-fold increase in SIVp28(+) macrophages entering the CNS late compared with those entering early (P < 0.05). The rate of CD163(+) macrophage recruitment to the CNS inversely correlated with time to death (P < 0.03) and increased with SIVE. In SIVE animals, soluble CD163 correlated with CD163(+) macrophage recruitment (P = 0.02). Most perivascular macrophages that comprise SIVE lesions and multinucleated giant cells are present in the CNS early, before SIVE lesions are formed. Most SIV-infected macrophages traffic to the CNS terminally with AIDS.
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Affiliation(s)
- Brian T Nowlin
- Biology Department, Boston College, Chestnut Hill, Massachusetts
| | - Tricia H Burdo
- Biology Department, Boston College, Chestnut Hill, Massachusetts
| | - Cecily C Midkiff
- Division of Comparative Pathology, Tulane National Primate Research Center, Tulane University Health Science Center, Covington, Louisiana
| | - Marco Salemi
- Department of Pathology, Immunology, and Laboratory Medicine, Emerging Pathogens Institute, University of Florida, Gainesville, Florida
| | - Xavier Alvarez
- Division of Comparative Pathology, Tulane National Primate Research Center, Tulane University Health Science Center, Covington, Louisiana
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Emergence of CD4 independence envelopes and astrocyte infection in R5 simian-human immunodeficiency virus model of encephalitis. J Virol 2014; 88:8407-20. [PMID: 24829360 DOI: 10.1128/jvi.01237-14] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
UNLABELLED Human immunodeficiency virus type 1 (HIV-1) infection in the central nervous system (CNS) is characterized by replication in macrophages or brain microglia that express low levels of the CD4 receptor and is the cause of HIV-associated dementia and related cognitive and motor disorders that affect 20 to 30% of treatment-naive patients with AIDS. Independent viral envelope evolution in the brain has been reported, with the need for robust replication in resident CD4(low) cells, as well as CD4-negative cells, such as astrocytes, proposed as a major selective pressure. We previously reported giant-cell encephalitis in subtype B and C R5 simian-human immunodeficiency virus (SHIV)-infected macaques (SHIV-induced encephalitis [SHIVE]) that experienced very high chronic viral loads and progressed rapidly to AIDS, with varying degrees of macrophage or microglia infection and activation of these immune cells, as well as astrocytes, in the CNS. In this study, we characterized envelopes (Env) amplified from the brains of subtype B and C R5 SHIVE macaques. We obtained data in support of an association between severe neuropathological changes, robust macrophage and microglia infection, and evolution to CD4 independence. Moreover, the degree of Env CD4 independence appeared to correlate with the extent of astrocyte infection in vivo. These findings further our knowledge of the CNS viral population phenotypes that are associated with the severity of HIV/SHIV-induced neurological injury and improve our understanding of the mechanism of HIV-1 cellular tropism and persistence in the brain. IMPORTANCE Human immunodeficiency virus type 1 (HIV-1) infection of astrocytes in the brain has been suggested to be important in HIV persistence and neuropathogenesis but has not been definitively demonstrated in an animal model of HIV-induced encephalitis (HIVE). Here, we describe a new nonhuman primate (NHP) model of R5 simian-human immunodeficiency virus (SHIV)-induced encephalitis (SHIVE) with several classical HIVE features that include astrocyte infection. We further show an association between severe neuropathological changes, robust resident microglia infection, and evolution to CD4 independence of viruses in the central nervous system (CNS), with expansion to infection of truly CD4-negative cells in vivo. These findings support the use of the R5 SHIVE models to study the contribution of the HIV envelope and viral clades to neurovirulence and residual virus replication in the CNS, providing information that should guide efforts to eradicate HIV from the body.
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Endothelin-1 and its role in the pathogenesis of infectious diseases. Life Sci 2014; 118:110-9. [PMID: 24780317 DOI: 10.1016/j.lfs.2014.04.021] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2014] [Revised: 04/08/2014] [Accepted: 04/15/2014] [Indexed: 12/12/2022]
Abstract
Endothelins are potent regulators of vascular tone, which also have mitogenic, apoptotic, and immunomodulatory properties (Rubanyi and Polokoff, 1994; Kedzierski and Yanagisawa, 2001; Bagnato et al., 2011). Three isoforms of endothelin have been identified to date, with endothelin-1 (ET-1) being the best studied. ET-1 is classically considered a potent vasoconstrictor. However, in addition to the effects of ET-1 on vascular smooth muscle cells, the peptide is increasingly recognized as a pro-inflammatory cytokine (Teder and Noble, 2000; Sessa et al., 1991). ET-1 causes platelet aggregation and plays a role in the increased expression of leukocyte adhesion molecules, the synthesis of inflammatory mediators contributing to vascular dysfunction. High levels of ET-1 are found in alveolar macrophages, leukocytes (Sessa et al., 1991) and fibroblasts (Gu et al., 1991). Clinical and experimental data indicate that ET-1 is involved in the pathogenesis of sepsis (Tschaikowsky et al., 2000; Goto et al., 2012), viral and bacterial pneumonia (Schuetz et al., 2008; Samransamruajkit et al., 2002), Rickettsia conorii infections (Davi et al., 1995), Chagas disease (Petkova et al., 2000, 2001), and severe malaria (Dai et al., 2012; Machado et al., 2006; Wenisch et al., 1996a; Dietmann et al., 2008). In this minireview, we will discuss the role of endothelin in the pathogenesis of infectious processes.
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Abstract
The spectrum of HIV-associated neurocognitive disorder (HAND) has been dramatically altered in the setting of widely available effective antiretroviral therapy (ART). Once culminating in dementia in many individuals infected with HIV, HAND now typically manifests as more subtle, though still morbid, forms of cognitive impairment in persons surviving long-term with treated HIV infection. Despite the substantial improvement in severity of this disorder, the fact that neurologic injury persists despite ART remains a challenge to the community of patients, providers and investigators aiming to optimize quality of life for those living with HIV. Cognitive dysfunction in treated HIV may reflect early irreversible CNS injury accrued before ART is typically initiated, ongoing low-level CNS infection and progressive injury in the setting of ART, or comborbidities including effects of treatment which may confound the beneficial reduction in viral replication and immune activation effected by ART.
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Abstract
Neurological sequelae of human immunodeficiency virus (HIV) infection have been and remain a significant problem. Monocytes and macrophages in humans and monkeys are susceptible to infection by HIV and simian immunodeficiency virus (SIV), and are considered to be a main mechanism by which the central nervous system (CNS) is infected. Within the infected CNS, perivascular macrophages and, in some cases, parenchymal microglia are infected as are multinucleated giant cells when present. While neurons are not themselves directly infected, neuronal damage occurs within the infected CNS. Despite the success of antiretroviral therapy (ART) in limiting virus in plasma to non-detectable levels, neurological deficits persist. This review discusses the continued neurological dysfunctions that persist in the era of ART, focusing on the roles of monocyte and macrophage as targets of continued viral infection and as agents of pathogenesis in what appears to be emergent macrophage-mediated disease resulting from long-term HIV infection of the host. Data discussed include the biology of monocyte/macrophage activation with HIV and SIV infection, traffic of cells into and out of the CNS with infection, macrophage-associated biomarkers of CNS and cardiac disease, the role of antiretroviral therapy on these cells and CNS disease, as well as the need for effective adjunctive therapies targeting monocytes and macrophages.
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Affiliation(s)
- Tricia H. Burdo
- Department of Biology, Boston College, Chestnut Hill, MA, USA
| | - Andrew Lackner
- Tulane National Primate Research Center, Covington, LA, USA
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Loss of a tyrosine-dependent trafficking motif in the simian immunodeficiency virus envelope cytoplasmic tail spares mucosal CD4 cells but does not prevent disease progression. J Virol 2012; 87:1528-43. [PMID: 23152518 DOI: 10.1128/jvi.01928-12] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
A hallmark of pathogenic simian immunodeficiency virus (SIV) and human immunodeficiency virus (HIV) infections is the rapid and near-complete depletion of mucosal CD4(+) T lymphocytes from the gastrointestinal tract. Loss of these cells and disruption of epithelial barrier function are associated with microbial translocation, which has been proposed to drive chronic systemic immune activation and disease progression. Here, we evaluate in rhesus macaques a novel attenuated variant of pathogenic SIVmac239, termed ΔGY, which contains a deletion of a Tyr and a proximal Gly from a highly conserved YxxØ trafficking motif in the envelope cytoplasmic tail. Compared to SIVmac239, ΔGY established a comparable acute peak of viremia but only transiently infected lamina propria and caused little or no acute depletion of mucosal CD4(+) T cells and no detectable microbial translocation. Nonetheless, these animals developed T-cell activation and declining peripheral blood CD4(+) T cells and ultimately progressed with clinical or pathological features of AIDS. ΔGY-infected animals also showed no infection of macrophages or central nervous system tissues even in late-stage disease. Although the ΔGY mutation persisted, novel mutations evolved, including the formation of new YxxØ motifs in two of four animals. These findings indicate that disruption of this trafficking motif by the ΔGY mutation leads to a striking alteration in anatomic distribution of virus with sparing of lamina propria and a lack of microbial translocation. Because these animals exhibited wild-type levels of acute viremia and immune activation, our findings indicate that these pathological events are dissociable and that immune activation unrelated to gut damage can be sufficient for the development of AIDS.
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Renner NA, Redmann RK, Moroney-Rasmussen T, Sansing HA, Aye PP, Didier PJ, Lackner AA, Maclean AG. S100β as a novel and accessible indicator for the presence of monocyte-driven encephalitis in AIDS. Neuropathol Appl Neurobiol 2012; 38:162-74. [PMID: 21696421 DOI: 10.1111/j.1365-2990.2011.01200.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
AIMS The pathogenesis of human/simian immunodeficiency virus encephalitis (HIVE/SIVE) remains incompletely understood, but is associated with alterations in the blood-brain barrier. At present, it is not possible to easily determine if an individual has HIVE/SIVE before post mortem examination. METHODS We have examined serum levels of the astroglial protein S100β in SIV-infected macaques and show that it can be used to determine which animals have SIVE. We also checked for correlations with inflammatory markers such as CCL2/MCP-1, IL-6 and C-reactive protein. RESULTS We found that increased S100β protein in serum correlated with decreased expression of the tight junction protein zonula occludens-1 on brain microvessels. Furthermore, the decrease in zonula occludens-1 expression was spatially related to SIVE lesions and perivascular deposition of plasma fibrinogen. There was no correlation between encephalitis and plasma levels of IL-6, MCP-1/CCL2 or C-reactive protein. CONCLUSIONS Together, these data indicate that SIVE lesions are associated with vascular leakage that can be determined by S100β protein in the periphery. The ability to simply monitor the presence of SIVE will greatly facilitate studies of the neuropathogenesis of AIDS.
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Affiliation(s)
- N A Renner
- Division of Comparative Pathology, Tulane National Primate Research Center, Tulane School of Medicine, Covington, LA 70433, USA.
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Gonzalez-Perez MP, O'Connell O, Lin R, Sullivan WM, Bell J, Simmonds P, Clapham PR. Independent evolution of macrophage-tropism and increased charge between HIV-1 R5 envelopes present in brain and immune tissue. Retrovirology 2012; 9:20. [PMID: 22420378 PMCID: PMC3362761 DOI: 10.1186/1742-4690-9-20] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2011] [Accepted: 03/15/2012] [Indexed: 01/05/2023] Open
Abstract
Background Transmitted HIV-1 clade B or C R5 viruses have been reported to infect macrophages inefficiently, while other studies have described R5 viruses in late disease with either an enhanced macrophage-tropism or carrying envelopes with an increased positive charge and fitness. In contrast, our previous data suggested that viruses carrying non-macrophage-tropic R5 envelopes were still predominant in immune tissue of AIDS patients. To further investigate the tropism and charge of HIV-1 viruses in late disease, we evaluated the properties of HIV-1 envelopes amplified from immune and brain tissues of AIDS patients with neurological complications. Results Almost all envelopes amplified were R5. There was clear compartmentalization of envelope sequences for four of the five subjects. However, strong compartmentalization of macrophage-tropism in brain was observed even when brain and immune tissue envelope sequences were not segregated. R5 envelopes from immune tissue of four subjects carried a higher positive charge compared to brain envelopes. We also confirm a significant correlation between macrophage tropism and sensitivity to soluble CD4, a weak association with sensitivity to the CD4 binding site antibody, b12, but no clear relationship with maraviroc sensitivity. Conclusions Our study shows that non-macrophage-tropic R5 envelopes carrying gp120s with an increased positive charge were predominant in immune tissue in late disease. However, highly macrophage-tropic variants with lower charged gp120s were nearly universal in the brain. These results are consistent with HIV-1 R5 envelopes evolving gp120s with an increased positive charge in immune tissue or sites outside the brain that likely reflect an adaptation for increased replication or fitness for CD4+ T-cells. Our data are consistent with the presence of powerful pressures in brain and in immune tissues selecting for R5 envelopes with very different properties; high macrophage-tropism, sCD4 sensitivity and low positive charge in brain and non-macrophage-tropism, sCD4 resistance and high positive charge in immune tissue.
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Affiliation(s)
- Maria Paz Gonzalez-Perez
- Department of Microbiology and Physiological Systems, University of Massachusetts Medical School, Worcester, Massachusetts 01605-2377, USA
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Meeker RB, Bragg DC, Poulton W, Hudson L. Transmigration of macrophages across the choroid plexus epithelium in response to the feline immunodeficiency virus. Cell Tissue Res 2012; 347:443-55. [PMID: 22281685 DOI: 10.1007/s00441-011-1301-8] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2011] [Accepted: 12/08/2011] [Indexed: 12/23/2022]
Abstract
Although lentiviruses such as human, feline and simian immunodeficiency viruses (HIV, FIV, SIV) rapidly gain access to cerebrospinal fluid (CSF), the mechanisms that control this entry are not well understood. One possibility is that the virus may be carried into the brain by immune cells that traffic across the blood-CSF barrier in the choroid plexus. Since few studies have directly examined macrophage trafficking across the blood-CSF barrier, we established transwell and explant cultures of feline choroid plexus epithelium and measured trafficking in the presence or absence of FIV. Macrophages in co-culture with the epithelium showed significant proliferation and robust trafficking that was dependent on the presence of epithelium. Macrophage migration to the apical surface of the epithelium was particularly robust in the choroid plexus explants where 3-fold increases were seen over the first 24 h. Addition of FIV to the cultures greatly increased the number of surface macrophages without influencing replication. The epithelium in the transwell cultures was also permissive to PBMC trafficking, which increased from 17 to 26% of total cells after exposure to FIV. Thus, the choroid plexus epithelium supports trafficking of both macrophages and PBMCs. FIV significantly enhanced translocation of macrophages and T cells indicating that the choroid plexus epithelium is likely to be an active site of immune cell trafficking in response to infection.
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Affiliation(s)
- Rick B Meeker
- Department of Neurology and Curriculum in Neurobiology, University of North Carolina, CB #7025, 6109F Neuroscience Research Building 103 Mason Farm Road, Chapel Hill, NC 27599, USA.
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Krings T, Mandell DM, Kiehl TR, Geibprasert S, Tymianski M, Alvarez H, terBrugge KG, Hans FJ. Intracranial aneurysms: from vessel wall pathology to therapeutic approach. Nat Rev Neurol 2011; 7:547-59. [DOI: 10.1038/nrneurol.2011.136] [Citation(s) in RCA: 114] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Depboylu C, Weihe E, Eiden LE. COX1 and COX2 expression in non-neuronal cellular compartments of the rhesus macaque brain during lentiviral infection. Neurobiol Dis 2011; 42:108-15. [PMID: 21220019 PMCID: PMC3066154 DOI: 10.1016/j.nbd.2011.01.011] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2010] [Revised: 12/16/2010] [Accepted: 01/02/2011] [Indexed: 11/17/2022] Open
Abstract
Recent evidence suggests that cyclooxygenases COX1 and COX2 differentially affect brain immunity. Limited data exist about their expressional changes in neurodegenerative diseases such as neuro-AIDS. Here, we analyzed the regulation of non-neuronal COX1/2 expression in rhesus macaque brain during infection with SIV(δ670) and antiretroviral treatment. COX1 was constitutively expressed in microglia and endothelial cells and was not changed in early SIV infection. Late stage of disease was characterized by increased COX1 expression in globally activated microglia, macrophage nodules, infiltrates, and multinucleated giant cells. Endothelial COX1 expression was unaltered. In contrast, COX2 was not expressed in non-neuronal cells in the brain of uninfected and asymptomatically SIV-infected monkeys but was induced in nodule- and syncytium-forming macrophages and in endothelial cells in areas with infiltrates and SIV in monkeys with AIDS. Antiretroviral treatment of AIDS-diseased monkeys with 6-chloro-2',3'-dideoxyguanosine markedly reduced SIV burden, appearance of COX1-positive macrophage nodules, giant cells, and infiltrates, and COX2 induction in the brain. However, the number of COX1-positive diffuse microglia was still increased in antiretrovirally treated animals as compared to uninfected or asymptomatic SIV-infected monkeys. Our data imply that both COX isoforms are differentially regulated and may distinctly modulate local immune responses in the brain during lentiviral disease.
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Affiliation(s)
- Candan Depboylu
- Molecular Neuroscience, Department of Anatomy and Cell Biology, Philipps University, Marburg, Germany
- Experimental Neurology, Department of Neurology, Philipps University, Marburg, Germany
| | - Eberhard Weihe
- Molecular Neuroscience, Department of Anatomy and Cell Biology, Philipps University, Marburg, Germany
| | - Lee E. Eiden
- Section on Molecular Neuroscience, Laboratory of Cellular and Molecular Regulation, National Institute of Mental Health, Bethesda, USA
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Huang X, Stone DK, Yu F, Zeng Y, Gendelman HE. Functional proteomic analysis for regulatory T cell surveillance of the HIV-1-infected macrophage. J Proteome Res 2010; 9:6759-73. [PMID: 20954747 PMCID: PMC3108468 DOI: 10.1021/pr1009178] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Regulatory T cells (Treg) induce robust neuroprotection in murine models of neuroAIDS, in part, through eliciting anti-inflammatory responses for HIV-1-infected brain mononuclear phagocytes (MP; macrophage and microglia). Herein, using both murine and human primary cell cultures in proteomic and cell biologic tests, we report that Treg promotes such neuroprotection by an even broader range of mechanisms than previously seen including inhibition of virus release, killing infected MP, and inducing phenotypic cell switches. Changes in individual Treg-induced macrophage proteins were quantified by iTRAQ labeling followed by mass spectrometry identifications. Reduction in virus release paralleled the upregulation of interferon-stimulated gene 15, an ubiquitin-like protein involved in interferon-mediated antiviral immunity. Treg killed virus-infected macrophages through caspase-3 and granzyme and perforin pathways. Independently, Treg transformed virus-infected macrophages from an M1 to an M2 phenotype by down- and up- regulation of inducible nitric oxide synthase and arginase 1, respectively. Taken together, Treg affects a range of virus-infected MP functions. The observations made serve to challenge the dogma of solitary Treg immune suppressor functions and provides novel insights into how Treg affects adaptive immunosurveillance for control of end organ diseases, notably neurocognitive disorders associated with advanced viral infection.
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Affiliation(s)
- Xiuyan Huang
- Department of Pharmacology, University of Nebraska Medical Center, Omaha, Nebraska 68198, United States
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Reeve AB, Pearce NC, Patel K, Augustus KV, Novembre FJ. Neuropathogenic SIVsmmFGb genetic diversity and selection-induced tissue-specific compartmentalization during chronic infection and temporal evolution of viral genes in lymphoid tissues and regions of the central nervous system. AIDS Res Hum Retroviruses 2010; 26:663-79. [PMID: 20518690 DOI: 10.1089/aid.2009.0168] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
SIVsmmFGb is a lentivirus swarm that induces neuropathology in over 90% of infected pigtailed macaques and reliably models central nervous system HIV infection in people. We have previously studied SIVsmmFGb genetic diversity and compartmentalization during acute infection, but little is understood about diversity and intertissue compartmentalization during chronic infection. Tissue-specific pressure appeared to affect the diversity of Nef sequences between tissues, but changes to the Env V1 region and Int diversity were similar across all tissues. At 2 months postinfection, compartmentalization of the SIVsmmFGb env V1 region, nef, and int was noted between different brain regions and between brain regions and lymph nodes. Convergent evolution of the nef and env V1 region, and divergent evolution of int, was noted between compartments and all genes demonstrated intratissue temporal segregation. For the env V1 region and nef, temporal segregation was stronger in the brain regions than the periphery, but little difference between tissues was noted for int. Positive selection of the env V1 region appeared in most tissues at 2 months postinfection, whereas nef and int faced negative selection in all tissues. Positive selection of the env V1 region sequences increased in some brain regions over time. SIVsmmFGb nef and int sequences each saw increased negative selection in brain regions, and one lymph node, over the course of infection. Functional differences between tissue compartments decreased over time for int and env V1 region sequences, but increased for nef sequences.
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Affiliation(s)
- Aaron B. Reeve
- Division of Microbiology and Immunology, Yerkes National Primate Research Center, Atlanta, Georgia
| | - Nicholas C. Pearce
- Division of Microbiology and Immunology, Yerkes National Primate Research Center, Atlanta, Georgia
| | - Kalpana Patel
- Division of Microbiology and Immunology, Yerkes National Primate Research Center, Atlanta, Georgia
| | - Katherine V. Augustus
- Division of Microbiology and Immunology, Yerkes National Primate Research Center, Atlanta, Georgia
| | - Francis J. Novembre
- Division of Microbiology and Immunology, Yerkes National Primate Research Center, Atlanta, Georgia
- Department of Microbiology and Immunology, Emory University, Atlanta, Georgia
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Compartmentalization and clonal amplification of HIV-1 variants in the cerebrospinal fluid during primary infection. J Virol 2009; 84:2395-407. [PMID: 20015984 DOI: 10.1128/jvi.01863-09] [Citation(s) in RCA: 124] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Human immunodeficiency virus type 1 (HIV-1)-associated dementia (HAD) is a severe neurological disease that affects a subset of HIV-1-infected individuals. Increased compartmentalization has been reported between blood and cerebrospinal fluid (CSF) HIV-1 populations in subjects with HAD, but it is still not known when compartmentalization arises during the course of infection. To assess HIV-1 genetic compartmentalization early during infection, we compared HIV-1 populations in the peripheral blood and CSF in 11 primary infection subjects, with analysis of longitudinal samples over the first 18 months for a subset of subjects. We used heteroduplex tracking assays targeting the variable regions of env and single-genome amplification and sequence analysis of the full-length env gene to identify CSF-compartmentalized variants and to examine viral genotypes within the compartmentalized populations. For most subjects, HIV-1 populations were equilibrated between the blood and CSF compartments. However, compartmentalized HIV-1 populations were detected in the CSF of three primary infection subjects, and longitudinal analysis of one subject revealed that compartmentalization during primary HIV-1 infection was resolved. Clonal amplification of specific HIV-1 variants was identified in the CSF population of one primary infection subject. Our data show that compartmentalization can occur in the central nervous system (CNS) of subjects in primary HIV-1 infection in part through persistence of the putative transmitted parental variant or via viral genetic adaptation to the CNS environment. The presence of distinct HIV-1 populations in the CSF indicates that independent HIV-1 replication can occur in the CNS, even early after HIV-1 transmission.
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Yang X, Du L, Tang X, Jung SY, Zheng B, Soh BY, Kim SY, Gu Q, Park H. Brevicompanine E reduces lipopolysaccharide-induced production of proinflammatory cytokines and enzymes in microglia by inhibiting activation of activator protein-1 and nuclear factor-kappaB. J Neuroimmunol 2009; 216:32-8. [PMID: 19815299 DOI: 10.1016/j.jneuroim.2009.09.004] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2009] [Revised: 08/18/2009] [Accepted: 09/04/2009] [Indexed: 12/19/2022]
Abstract
Excessive release of proinflammatory cytokines by activated microglia can cause neurotoxicity in neurodegenerative diseases. We found that Brevicompanine E (BE), isolated from a deep ocean sediment derived fungus Penicillium sp., inhibited lipopolysaccharide (LPS)-induced tumor necrosis factor-alpha (TNF-alpha), interleukin-1beta (IL-1beta), inducible nitric oxide (iNOS) and cyclooxygenase-2 (COX-2) production in microglia. Moreover, electrophoretic mobility shift assay (EMSA) demonstrated that BE attenuated nuclear factor-kappaB (NF-kappaB) and activator protein-1 (AP-1) DNA binding activity in LPS-induced microglia. Consistent with this finding, BE inhibited LPS-induced IkappaBalpha degradation, NF-kappaB nuclear translocation, and also Akt, c-Jun NH2-terminal kinase (JNK) phosphorylation. Thus, BE may be potentially useful for modulating neuroinflammation.
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Affiliation(s)
- Xinying Yang
- Zoonosis Research Center, Wonkwang University School of Medicine, Iksan, Chonbuk, South Korea
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Early antiretroviral treatment prevents the development of central nervous system abnormalities in simian immunodeficiency virus-infected rhesus monkeys. AIDS 2009; 23:1187-95. [PMID: 19455015 DOI: 10.1097/qad.0b013e32832c4af0] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
OBJECTIVE Neurocognitive disorders are devastating consequences of HIV infection. Although antiretroviral regimens have been efficacious in both improving life expectancy and decreasing dementia, there has not been an effect on the overall prevalence of HIV-associated neurocognitive disorders. Whether early institution of treatment, or treatment with drugs that effectively penetrate the blood-brain barrier, would help protect from such conditions is not known. Using the simian immunodeficiency virus/macaque model, we investigated the hypothesis that early introduction of antiretroviral treatment can protect the brain. DESIGN AND METHODS Animals were inoculated with simian immunodeficiency virus, and upon resolution of the acute infection period divided into two groups and treated, or not, with combination antiretroviral therapy. Viral, immune, and physiological parameters were measured during the course of infection, followed by assessment of viral, immune, and molecular parameters in the brain. RESULTS We observed that even with agents that show poor penetration into the central nervous system, early antiretroviral treatment prevented characteristic neurophysiological and locomotor alterations arising after infection and resulted in a significant decrease in brain viral load. Although the number of infiltrating immune cells in the brain did not change with treatment, their phenotype did, favoring an enrichment of effector T cells. Early treatment also significantly lowered brain levels of interferon-alpha, a cytokine that can lead to neurocognitive and behavioral alterations. CONCLUSION Early antiretroviral treatment prevents central nervous system dysfunction by decreasing brain viral load and interferon-alpha levels, which can have a profound impact over the course of infection.
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Valcour VG, Shiramizu BT, Sithinamsuwan P, Nidhinandana S, Ratto-Kim S, Ananworanich J, Siangphoe U, Kim JH, de Souza M, Degruttola V, Paul RH, Shikuma CM. HIV DNA and cognition in a Thai longitudinal HAART initiation cohort: the SEARCH 001 Cohort Study. Neurology 2009; 72:992-8. [PMID: 19289739 DOI: 10.1212/01.wnl.0000344404.12759.83] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
OBJECTIVES The extent to which highly active antiretroviral therapy (HAART) era cognitive disorders are due to active processes, incomplete clearance of reservoirs, or comorbidities is controversial. This study aimed to determine if immunologic and virologic factors influence cognition after first-time HAART in Thai individuals with HIV-associated dementia (HAD) and Thai individuals without HAD (non-HAD). METHODS Variables were captured longitudinally to determine factors predictive of degree of cognitive recovery after first-time HAART. Neuropsychological data were compared to those of 230 HIV-negative Thai controls. RESULTS HIV RNA and CD4 lymphocyte counts were not predictive of HAD cross-sectionally or degree of cognitive improvement longitudinally. In contrast, baseline and longitudinal HIV DNA isolated from monocytes correlated to cognitive performance irrespective of plasma HIV RNA and CD4 lymphocyte counts pre-HAART (p < 0.001) and at 48 weeks post HAART (p < 0.001). Levels exceeding 3.5 log(10) copies HIV DNA/10(6) monocyte at baseline distinguished all HAD and non-HAD cases (p < 0.001). At 48 weeks, monocyte HIV DNA was below the level of detection of our assay (10 copies/10(6) cells) in 15/15 non-HAD compared to only 4/12 HAD cases, despite undetectable plasma HIV RNA in 26/27 cases. Baseline monocyte HIV DNA predicted 48-week cognitive performance on a composite score, independently of concurrent monocyte HIV DNA and CD4 count (p < 0.001). CONCLUSIONS Monocyte HIV DNA level correlates to cognitive performance before highly active antiretroviral therapy (HAART) and 48 weeks after HAART in this cohort and baseline monocyte HIV DNA may predict 48-week cognitive performance. These findings raise the possibility that short-term incomplete cognitive recovery with HAART may represent an active process related to this peripheral reservoir.
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Affiliation(s)
- V G Valcour
- Hawaii AIDS Clinical Research Program, John A. Burns School of Medicine, University of Hawaii, Honolulu, HI 96816, USA.
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Clements JE, Mankowski JL, Gama L, Zink MC. The accelerated simian immunodeficiency virus macaque model of human immunodeficiency virus-associated neurological disease: from mechanism to treatment. J Neurovirol 2009; 14:309-17. [PMID: 18780232 DOI: 10.1080/13550280802132832] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
Highly active antiretroviral therapy has been effective in lowering viral loads in the peripheral blood, restoring immune function and reducing the incidence of opportunistic infections and dementia in human immunodeficiency virus (HIV)-infected individuals. However, motor and cognitive deficits and peripheral neuropathy continue, with some studies reporting an increase in prevalence of nervous system disease. The authors developed an accelerated, consistent simian model of HIV infection in which pigtailed macaques are dual inoculated with a neurovirulent simian immunodeficiency virus (SIV) clone and an immunosuppressive SIV strain. Infected animals invariably develop acquired immunodeficiency syndrome (AIDS) and over 90% develop central nervous system disease as well as peripheral nervous system disease with neurodegeneration by 3 months postinoculation. This model provides outstanding opportunities to delineate the pathogenesis of infection, to study the regulation of virus gene expression, and to identify host immune responses throughout the acute, clinically silent and late stages of infection. Using this model, the authors have demonstrated that the virus enters the brain within days after inoculation, that CCL2 (monocyte chemoattractant protein [MCP]-1) plays a major role in recruiting monocytes/macrophages to the brain, and that type I interferons are critical in suppressing early virus replication and inducing viral latency. This model provides a rigorous platform for the testing of potential antiretroviral, immune reconstituting, and/or neuroprotective agents and already has been used to confirm the neuroprotective properties of minocycline, which now is being tested in clinical trials of HIV-infected individuals.
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Affiliation(s)
- Janice E Clements
- Department of Molecular and Comparative Pathobiology, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA
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Williams R, Bokhari S, Silverstein P, Pinson D, Kumar A, Buch S. Nonhuman primate models of NeuroAIDS. J Neurovirol 2009; 14:292-300. [PMID: 18780230 DOI: 10.1080/13550280802074539] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
Human Immunodeficiency virus (HIV), the virus that causes acquired immunodeficiency syndrome (AIDS), also manifests neurological complications. HIV-associated dementia (HAD) is the most severe form of HIV-induced neurocognitive disorders. HIV encephalitis (HIVE), the pathological correlate of HAD, is characterized by the formation of multinucleated giant cells and microglial nodules, astrocytosis, and neuronal damage and loss. Pathological evaluation of HAD disease progression in humans is not possible, with the only data collected being from individuals who have succumbed to the disorder, a snap shot of end-stage disease at best. Therefore, pertinent animal models have been developed to alleviate this gap of knowledge in the field of neurovirology and neuroinflammation. In general, the most widely used animal models are the simian immunodeficiency virus (SIV) and the chimeric simian/human immunodeficiency virus (SHIV) macaque model systems. Although both SIV and SHIV model systems are able to potentiate neuroinvasion and the concomitant neuropathology similar to that seen in the human syndromes, the innate differences between the two in disease pathogenesis and progression make for two separate, yet effective, systems for the study of HIV-associated neuropathology.
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Affiliation(s)
- Rachel Williams
- Department of Molecular and Integrative Physiology, University of Kansas Medical Center, Kansas City, Kansas 66103, USA
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Monocyte chemotactic protein-1 regulates voltage-gated K+ channels and macrophage transmigration. J Neuroimmune Pharmacol 2008; 4:47-59. [PMID: 19034671 DOI: 10.1007/s11481-008-9135-1] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2008] [Accepted: 10/31/2008] [Indexed: 10/21/2022]
Abstract
Progressive human immunodeficiency virus (HIV)-1 infection and virus-induced neuroinflammatory responses effectuate monocyte-macrophage transmigration across the blood-brain barrier (BBB). A key factor in mediating these events is monocyte chemotactic protein-1 (MCP-1). Upregulated glial-derived MCP-1 in HIV-1-infected brain tissues generates a gradient for monocyte recruitment into the nervous system. We posit that the inter-relationships between MCP-1, voltage-gated ion channels, cell shape and volume, and cell mobility underlie monocyte transmigration across the BBB. In this regard, MCP-1 serves both as a chemoattractant and an inducer of monocyte-macrophage ion flux affecting cell shape and mobility. To address this hypothesis, MCP-1-treated bone marrow-derived macrophages (BMM) were analyzed for gene and protein expression, electrophysiology, and capacity to migrate across a laboratory constructed BBB. MCP-1 enhanced K+ channel gene (KCNA3) and channel protein expression. Electrophysiological studies revealed that MCP-1 increased outward K+ currents in a dose-dependent manner. In vitro studies demonstrated that MCP-1 increased BMM migration across an artificial BBB, and the MCP-1-induced BMM migration was blocked by tetraethylammonium, a voltage-gated K+ channel blocker. Together these data demonstrated that MCP-1 affects macrophage migratory movement through regulation of voltage-gated K+ channels and, as such, provides a novel therapeutic strategy for neuroAIDS.
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Marcondes MCG, Lanigan CMS, Burdo TH, Watry DD, Fox HS. Increased expression of monocyte CD44v6 correlates with the deveopment of encephalitis in rhesus macaques infected with simian immunodeficiency virus. J Infect Dis 2008; 197:1567-76. [PMID: 18471064 DOI: 10.1086/588002] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
In people infected with human immunodeficiency virus type 1 (HIV-1), the accumulation of macrophages in the brain correlates with encephalitis and dementia. We hypothesized that a pattern of surface marker expression in blood monocytes may serve as a marker for central nervous system (CNS) disease. Using the simian immunodeficiency virus (SIV)-rhesus monkey model, we analyzed functionally relevant surface markers on monocytes and macrophages from the blood and brain in animals that did or did not develop SIV encephalitis. At necropsy, multiple markers (CD44v6, CCR2, and CCR5 on blood monocytes and brain microglia and/or macrophages, and CX3CR1 on blood monocytes) allowed us to distinguish animals with encephalitis from those without. Furthermore, the level of expression of CD44v6 on the 2 main populations of blood monocytes--those that express either low or high levels of CD16--was significantly increased in animals with encephalitis. A longitudinal analysis of blood monocyte markers revealed that as early as 28 days after inoculation, CD44v6 staining could distinguish the 2 groups. This provides a potential peripheral biomarker to identify individuals who may develop the HIV-induced CNS disease. Furthermore, given its role in cellular adhesion and as an osteopontin receptor, CD44v6 upregulation on monocytes offers functional clues to the pathogenesis of such complications, and provides a target for preventative and therapeutic measures.
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Affiliation(s)
- Maria Cecilia G Marcondes
- Molecular and Integrative Neurosciences Department, The Scripps Research Institute, 10550 North Torrey Pines Road, SP302030, La Jolla, California 92037, USA
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NeuroAIDS: characteristics and diagnosis of the neurological complications of AIDS. Mol Diagn Ther 2008; 12:25-43. [PMID: 18288880 DOI: 10.1007/bf03256266] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Abstract
The neurological complications of AIDS (NeuroAIDS) include neurocognitive impairment and HIV-associated dementia (HAD; also known as AIDS dementia and HIV encephalopathy). HAD is the most significant and devastating central nervous system (CNS) complications associated with HIV infection. Despite recent advances in our knowledge of the clinical features, pathogenesis, and neurobiological aspects of HAD, it remains a formidable scientific and therapeutic challenge. An understanding of the mechanisms of HIV neuroinvasion, CNS proliferation, and HAD pathogenesis provide a basis for the interpretation of the diagnostic features of HAD and its milder form, HIV-associated minor cognitive/motor disorder (MCMD). Current diagnostic strategies are associated with significant limitations, but it is hoped that the use of biomarkers may assist researchers and clinicians in predicting the onset of the disease process and in evaluating the effects of new therapies.
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Characterization of the early steps of infection of primary blood monocytes by human immunodeficiency virus type 1. J Virol 2008; 82:6557-65. [PMID: 18417568 DOI: 10.1128/jvi.02321-07] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Blood-circulating monocytes migrate in tissues in response to danger stimuli and differentiate there into two major actors of the immune system: macrophages and dendritic cells. Given their migratory behavior and their pivotal role in the orchestration of immune responses, it is not surprising that cells of the monocyte lineage are the target of several viruses, including human immunodeficiency virus type 1 (HIV-1). HIV-1 replicates in monocytoid cells to an extent that is influenced by their differentiation status and modulated by exogenous stimulations. Unstimulated monocytes display a relative resistance to HIV infection mostly exerted during the early steps of the viral life cycle. Despite intensive studies, the identity of the affected step remains controversial, although it is generally assumed to take place after viral entry. We reexamine here the early steps of viral infection of unstimulated monocytes using vesicular stomatitis virus G protein-pseudotyped HIV-1 virions. Our data indicate that a first block to the early steps of infection of monocytes with these particles occurs at the level of viral entry. After entry, reverse transcription and integration proceed with extremely slow kinetics rather than being blocked. Once completed, viral DNA molecules delay entry into the nucleus and integration for up to 5 to 6 days. The inefficacy of these steps accounts for the resistance of monocytes to HIV-1 during the early steps of infection.
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Systemic and brain macrophage infections in relation to the development of simian immunodeficiency virus encephalitis. J Virol 2008; 82:5031-42. [PMID: 18337567 DOI: 10.1128/jvi.02069-07] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The brains of individuals with lentiviral-associated encephalitis contain an abundance of infected and activated macrophages. It has been hypothesized that encephalitis develops when increased numbers of infected monocytes traffic into the central nervous system (CNS) during the end stages of immunosuppression. The relationships between the infection of brain and systemic macrophages and circulating monocytes and the development of lentiviral encephalitis are unknown. We longitudinally examined the extent of monocyte/macrophage infection in blood and lymph nodes of pigtailed macaques that did or did not develop simian immunodeficiency virus encephalitis (SIVE). Compared to levels in macaques that did not develop SIVE, more ex vivo virus production was detected from monocyte-derived macrophages and nonadherent peripheral blood mononuclear cells (PBMCs) from macaques that did develop SIVE. Prior to death, there was an increase in the number of circulating PBMCs following a rise in cerebrospinal fluid viral load in macaques that did develop SIVE but not in nonencephalitic macaques. At necropsy, macaques with SIVE had more infected macrophages in peripheral organs, with the exception of lymph nodes. T cells and NK cells with cytotoxic potential were more abundant in brains with encephalitis; however, T-cell and NK-cell infiltration in SIVE and human immunodeficiency virus encephalitis was more modest than that observed in classical acute herpes simplex virus encephalitis. These findings support the hypothesis that inherent differences in host systemic and CNS monocyte/macrophage viral production are associated with the development of encephalitis.
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Borda JT, Alvarez X, Mohan M, Hasegawa A, Bernardino A, Jean S, Aye P, Lackner AA. CD163, a marker of perivascular macrophages, is up-regulated by microglia in simian immunodeficiency virus encephalitis after haptoglobin-hemoglobin complex stimulation and is suggestive of breakdown of the blood-brain barrier. THE AMERICAN JOURNAL OF PATHOLOGY 2008; 172:725-37. [PMID: 18276779 DOI: 10.2353/ajpath.2008.070848] [Citation(s) in RCA: 88] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Macrophages and microglia are the major cell types infected by human immunodeficiency virus and simian immunodeficiency virus (SIV) in the central nervous system. Microglia are likely infected in vivo, but evidence of widespread productive infection (ie, presence of viral RNA and protein) is lacking. This conclusion is controversial because, unlike lymphocytes, macrophages and microglia cannot be discreetly immunophenotyped. Of particular interest in the search for additional monocyte/macrophage-lineage cell markers is CD163; this receptor for haptoglobin-hemoglobin (Hp-Hb) complex, which forms in plasma following erythrolysis, is expressed exclusively on cells of monocyte/macrophage lineage. We examined CD163 expression in vitro and in vivo by multiple techniques and at varying times after SIV infection in macaques with or without encephalitis. In normal and acutely SIV-infected animals, and in SIV-infected animals without encephalitis, CD163 expression was detected in cells of monocyte/macrophage lineage, including perivascular macrophages, but not in parenchymal microglia. However, in chronically infected animals with encephalitis, CD163 expression was detected in activated microglia surrounding SIV encephalitis lesions in the presence of Hp-Hb complex, suggesting leakage of the blood-brain barrier. CD163 expression was also induced on microglia in vitro after stimulation with Hp-Hb complex. We conclude that CD163 is a selective marker of perivascular macrophages in normal macaques and during the early phases of SIV infection; however, later in infection in animals with encephalitis, CD163 is also expressed by microglia, which are probably activated as a result of vascular compromise.
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Affiliation(s)
- Juan T Borda
- Division of Comparative Pathology, Tulane National Primate Research Center, Tulane University Health Sciences Center, Covington, Louisiana 70433, USA
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Peters PJ, Duenas-Decamp MJ, Sullivan WM, Brown R, Ankghuambom C, Luzuriaga K, Robinson J, Burton DR, Bell J, Simmonds P, Ball J, Clapham PR. Variation in HIV-1 R5 macrophage-tropism correlates with sensitivity to reagents that block envelope: CD4 interactions but not with sensitivity to other entry inhibitors. Retrovirology 2008; 5:5. [PMID: 18205925 PMCID: PMC2268948 DOI: 10.1186/1742-4690-5-5] [Citation(s) in RCA: 70] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2007] [Accepted: 01/18/2008] [Indexed: 11/13/2022] Open
Abstract
Background HIV-1 R5 viruses cause most of the AIDS cases worldwide and are preferentially transmitted compared to CXCR4-using viruses. Furthermore, R5 viruses vary extensively in capacity to infect macrophages and highly macrophage-tropic variants are frequently identified in the brains of patients with dementia. Here, we investigated the sensitivity of R5 envelopes to a range of inhibitors and antibodies that block HIV entry. We studied a large panel of R5 envelopes, derived by PCR amplification without culture from brain, lymph node, blood and semen. These R5 envelopes conferred a wide range of macrophage tropism and included highly macrophage-tropic variants from brain and non-macrophage-tropic variants from lymph node. Results R5 macrophage-tropism correlated with sensitivity to inhibition by reagents that inhibited gp120:CD4 interactions. Thus, increasing macrophage-tropism was associated with increased sensitivity to soluble CD4 and to IgG-CD4 (PRO 542), but with increased resistance to the anti-CD4 monoclonal antibody (mab), Q4120. These observations were highly significant and are consistent with an increased affinity of envelope for CD4 for macrophage-tropic envelopes. No overall correlations were noted between R5 macrophage-tropism and sensitivity to CCR5 antagonists or to gp41 specific reagents. Intriguingly, there was a relationship between increasing macrophage-tropism and increased sensitivity to the CD4 binding site mab, b12, but decreased sensitivity to 2G12, a mab that binds a glycan complex on gp120. Conclusion Variation in R5 macrophage-tropism is caused by envelope variation that predominantly influences sensitivity to reagents that block gp120:CD4 interactions. Such variation has important implications for therapy using viral entry inhibitors and for the design of envelope antigens for vaccines.
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Affiliation(s)
- Paul J Peters
- Center for AIDS Research, Program in Molecular Medicine and Department of Molecular Genetics and Microbiology, 373 Plantation Street, University of Massachusetts Medical School, Worcester, MA 01605, USA.
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Müller N, Schwarz MJ. The immune-mediated alteration of serotonin and glutamate: towards an integrated view of depression. Mol Psychiatry 2007; 12:988-1000. [PMID: 17457312 DOI: 10.1038/sj.mp.4002006] [Citation(s) in RCA: 454] [Impact Index Per Article: 26.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Beside the well-known deficiency in serotonergic neurotransmission as pathophysiological correlate of major depression (MD), recent evidence points to a pivotal role of increased glutamate receptor activation as well. However, cause and interaction of these neurotransmitter alterations are not understood. In this review, we present a hypothesis integrating current concepts of neurotransmission and hypothalamus-pituitary-adrenal (HPA) axis dysregulation with findings on immunological alterations and alterations in brain morphology in MD. An immune activation including increased production of proinflammatory cytokines has repeatedly been described in MD. Proinflammatory cytokines such as interleukin-2, interferon-gamma, or tumor necrosis factor-alpha activate the tryptophan- and serotonin-degrading enzyme indoleamine 2,3-dioxygenase (IDO). Depressive states during inflammatory somatic disorders are also associated with increased proinflammatory cytokines and increased consumption of tryptophan via activation of IDO. An enhanced consumption of serotonin and its precursor tryptophan through IDO activation could well explain the reduced availability of serotonergic neurotransmission in MD. An increased activation of IDO and its subsequent enzyme kynurenine monooxygenase by proinflammatory cytokines, moreover, leads to an enhanced production of quinolinic acid, a strong agonist of the glutamatergic N-methyl-D-aspartate receptor. In inflammatory states of the central nervous system, IDO is mainly activated in microglial cells, which preferentially metabolize tryptophan to the NMDA receptor agonist quinolinic acid, whereas astrocytes - counteracting this metabolism due to the lack of an enzyme of this metabolism - have been observed to be reduced in MD. Therefore the type 1/type 2 immune response imbalance, associated with an astrocyte/microglia imbalance, leads to serotonergic deficiency and glutamatergic overproduction. Astrocytes are further strongly involved in re-uptake and metabolic conversion of glutamate. The reduced number of astrocytes could contribute to both, a diminished counterregulation of IDO activity in microglia and an altered glutamatergic neurotransmission. Further search for antidepressant agents should take into account anti-inflammatory drugs, for example, cyclooxygenase-2 inhibitors, might exert antidepressant effects by acting on serotonergic deficiency, glutamatergic hyperfunction and antagonizing neurotoxic effects of quinolinic acid.
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Affiliation(s)
- N Müller
- Department for Psychiatry and Psychotherapy, Ludwig-Maximilians-Universität München, München, Germany.
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