Morphine suppresses peripheral responses and transforms brain myeloid gene expression to favor neuropathogenesis in SIV infection

Transcriptional impacts of substance use disorder and HIV on human ventral midbrain neurons and microglia

For people with HIV (PWH), substance use disorders (SUDs) are a prominent neurological risk factor, and the impacts of both on dopaminergic pathways are a potential point of deleterious convergence. Here, we profile, at single nucleus resolution, the substantia nigra (SN) transcriptomes of 90 postmortem donors in the context of chronic HIV and opioid/cocaine SUD, including 67 prospectively characterized PWH. We report altered microglial expression for hundreds of pro- and anti-inflammatory regulators attributable to HIV, and separately, to SUD. Stepwise, progressive microglial dysregulation, coupled to altered SN dopaminergic and GABAergic signaling, was associated with SUD/HIV dual diagnosis and further with lack of viral suppression in blood. In virologically suppressed donors, SUD comorbidity was associated with microglial transcriptional changes permissive for HIV infection. We report HIV-related downregulation of monoamine reuptake transporters specifically in dopaminergic neurons regardless of SUD status or viral load, and additional transcriptional signatures consistent with selective vulnerability of SN dopamine neurons.

Primary Literature for Teaching Neuroimmunology - An Instructor's Resource

Supplementing textbooks with primary literature in teaching neuroscience is a growing practice associated with several positive outcomes, such as increased content knowledge, research and data skills, and critical thinking. This pedagogical approach, however, still needs further development to make it accessible to instructors and valuable to students. This article describes a series of published articles we used in an undergraduate neuroimmunology course. Articles were selected to supplement the teaching of significant principles in the neuroimmunology of disease in neuro-infections, autoimmune diseases, and neurodegenerative diseases. Specifically, articles on multiple sclerosis, experimental autoimmune encephalitis, Herpes Simplex Virus 1, SIV/HIV infections, Alzheimer's, and Parkinson's diseases are described, and the pedagogical value of each is enunciated. These sources could be incorporated into a range of undergraduate and graduate courses to introduce several topics and principles of neuroimmunology.

Microglia and macrophages alterations in the CNS during acute SIV infection: A single-cell analysis in rhesus macaques

Human Immunodeficiency Virus (HIV) is widely acknowledged for its profound impact on the immune system. Although HIV primarily affects peripheral CD4 T cells, its influence on the central nervous system (CNS) cannot be overlooked. Within the brain, microglia and CNS-associated macrophages (CAMs) serve as the primary targets for HIV and the simian immunodeficiency virus (SIV) in nonhuman primates. This infection can lead to neurological effects and establish a viral reservoir. Given the gaps in our understanding of how these cells respond in vivo to acute CNS infection, we conducted single-cell RNA sequencing (scRNA-seq) on myeloid cells from the brains of three rhesus macaques 12 days after SIV infection, along with three uninfected controls. Our analysis revealed six distinct microglial clusters including homeostatic microglia, preactivated microglia, and activated microglia expressing high levels of inflammatory and disease-related molecules. In response to acute SIV infection, the homeostatic and preactivated microglia population decreased, while the activated and disease-related microglia increased. All microglial clusters exhibited upregulation of MHC class I molecules and interferon-related genes, indicating their crucial roles in defending against SIV during the acute phase. All microglia clusters also upregulated genes linked to cellular senescence. Additionally, we identified two distinct CAM populations: CD14lowCD16hi and CD14hiCD16low CAMs. Interestingly, during acute SIV infection, the dominant CAM population changed to one with an inflammatory phenotype. Specific upregulated genes within one microglia and one macrophage cluster were associated with neurodegenerative pathways, suggesting potential links to neurocognitive disorders. This research sheds light on the intricate interactions between viral infection, innate immune responses, and the CNS, providing valuable insights for future investigations.

Immune response and cytokine profiles in post-laminectomy pain syndrome: comparative analysis after treatment with intrathecal opioids, oral opioids, and non-opioid therapies

INTRODUCTION

This study explores the interaction between cytokines, cell-mediated immunity (T cells, B cells, and NK cells), and prolonged morphine administration in chronic neuropathic pain patients without cancer-related issues. Despite evidence of opioid immunomodulation, few studies have compared these interactions.

METHODS

In a cross-sectional and comparative study, 50 patients with chronic low back radicular pain ("Failed Back Surgery Syndrome") were categorized into intrathecal morphine infusion (IT group, n = 18), oral morphine (PO group, n = 17), and non-opioid treatment (NO group, n = 15). Various parameters, including plasma and cerebrospinal fluid (CSF) cytokine concentrations, lymphocyte immunophenotyping, opioid escalation indices, cumulative morphine dose, and treatment duration, were assessed.

RESULTS

CSF IL-8 and IL-1β concentrations exceeded plasma levels in all patients. No differences in T, B, and NK lymphocyte numbers were observed between morphine-treated and non-treated patients. Higher plasma IL-5 and GM-CSF concentrations were noted in IT and PO groups compared to NO. CSF IFNγ concentrations were higher in PO and NO than IT. Positive correlations included CD4 concentrations with opioid escalation indices, and negative correlations involved NK cell concentrations, CSF TNFα concentrations, and opioid escalation indices. Positive correlations were identified between certain cytokines and pain intensity in IT patients, and between NK cells and cumulative morphine dose. Negative correlations were observed between CSF IL-5 concentrations and pain intensity in IT and PO, and between opioid escalation indices and CSF cytokine concentrations in PO and IT.

CONCLUSION

Associations between cytokines, cellular immunity, and prolonged morphine treatment, administered orally and intrathecally were identified.

CNS Viral Infections-What to Consider for Improving Drug Treatment: A Plea for Using Mathematical Modeling Approaches

Neurotropic viruses may cause meningitis, myelitis, encephalitis, or meningoencephalitis. These inflammatory conditions of the central nervous system (CNS) may have serious and devastating consequences if not treated adequately. In this review, we first summarize how neurotropic viruses can enter the CNS by (1) crossing the blood-brain barrier or blood-cerebrospinal fluid barrier; (2) invading the nose via the olfactory route; or (3) invading the peripheral nervous system. Neurotropic viruses may then enter the intracellular space of brain cells via endocytosis and/or membrane fusion. Antiviral drugs are currently used for different viral CNS infections, even though their use and dosing regimens within the CNS, with the exception of acyclovir, are minimally supported by clinical evidence. We therefore provide considerations to optimize drug treatment(s) for these neurotropic viruses. Antiviral drugs should cross the blood-brain barrier/blood cerebrospinal fluid barrier and pass the brain cellular membrane to inhibit these viruses inside the brain cells. Some antiviral drugs may also require intracellular conversion into their active metabolite(s). This illustrates the need to better understand these mechanisms because these processes dictate drug exposure within the CNS that ultimately determine the success of antiviral drugs for CNS infections. Finally, we discuss mathematical model-based approaches for optimizing antiviral treatments. Thereby emphasizing the potential of CNS physiologically based pharmacokinetic models because direct measurement of brain intracellular exposure in living humans faces ethical restrictions. Existing physiologically based pharmacokinetic models combined with in vitro pharmacokinetic/pharmacodynamic information can be used to predict drug exposure and evaluate efficacy of antiviral drugs within the CNS, to ultimately optimize the treatments of CNS viral infections.

Microglia and macrophages alterations in the CNS during acute SIV infection: a single-cell analysis in rhesus macaques

Human Immunodeficiency Virus (HIV) is widely acknowledged for its profound impact on the immune system. Although HIV primarily affects peripheral CD4 T cells, its influence on the central nervous system (CNS) cannot be overlooked. Within the brain, microglia and CNS-associated macrophages (CAMs) serve as the primary targets for HIV, as well as for the simian immunodeficiency virus (SIV) in nonhuman primates. This infection can lead to neurological effects and the establishment of a viral reservoir. Given the gaps in our understanding of how these cells respond in vivo to acute CNS infection, we conducted single-cell RNA sequencing (scRNA-seq) on myeloid cells from the brains of three rhesus macaques 12-days after SIV infection, along with three uninfected controls. Our analysis revealed six distinct microglial clusters including homeostatic microglia, preactivated microglia, and activated microglia expressing high levels of inflammatory and disease-related molecules. In response to acute SIV infection, the population of homeostatic and preactivated microglia decreased, while the activated and disease-related microglia increased. All microglial clusters exhibited upregulation of MHC class I molecules and interferon-related genes, indicating their crucial roles in defending against SIV during the acute phase. All microglia clusters also upregulated genes linked to cellular senescence. Additionally, we identified two distinct CAM populations: CD14lowCD16hi and CD14hiCD16low CAMs. Interestingly, during acute SIV infection, the dominant CAM population changed to one with an inflammatory phenotype. Notably, specific upregulated genes within one microglia and one macrophage cluster were associated with neurodegenerative pathways, suggesting potential links to neurocognitive disorders. This research sheds light on the intricate interactions between viral infection, innate immune responses, and the CNS, providing valuable insights for future investigations.

Endogenous opiates and behavior: 2022

This paper is the forty-fifth consecutive installment of the annual anthological review of research concerning the endogenous opioid system, summarizing articles published during 2022 that studied the behavioral effects of molecular, pharmacological and genetic manipulation of opioid peptides and receptors as well as effects of opioid/opiate agonists and antagonists. The review is subdivided into the following specific topics: molecular-biochemical effects and neurochemical localization studies of endogenous opioids and their receptors (1), the roles of these opioid peptides and receptors in pain and analgesia in animals (2) and humans (3), opioid-sensitive and opioid-insensitive effects of nonopioid analgesics (4), opioid peptide and receptor involvement in tolerance and dependence (5), stress and social status (6), learning and memory (7), eating and drinking (8), drug abuse and alcohol (9), sexual activity and hormones, pregnancy, development and endocrinology (10), mental illness and mood (11), seizures and neurologic disorders (12), electrical-related activity and neurophysiology (13), general activity and locomotion (14), gastrointestinal, renal and hepatic functions (15), cardiovascular responses (16), respiration and thermoregulation (17), and immunological responses (18).

Beyond the Syndemic of Opioid Use Disorders and HIV: The Impact of Opioids on Viral Reservoirs

People with HIV are more likely to have opioid use disorder and to be prescribed opioids for chronic pain than the general population; however, the effects of opioids on the immune system and HIV persistence have not been fully elucidated. Opioids may affect HIV reservoirs during their establishment, maintenance, and reactivation by enhancing HIV infectivity and replication due to upregulation of co-receptors and impairment of innate antiviral responses. Opioids may also modulate immune cell functioning and microbial translocation and can reverse viral latency. In this review, we summarize the current findings for and against the modulating effects of opioids on HIV cellular and anatomical reservoirs, highlighting the current limitations that affect in vitro, ex vivo, and in vivo studies in the field. We propose further research targets and potential strategies to approach this topic.

Opioid abuse and SIV infection in non-human primates

Human immunodeficiency virus (HIV) and drug abuse are intertwined epidemics, leading to compromised adherence to combined antiretroviral therapy (cART) and exacerbation of NeuroHIV. As opioid abuse causes increased viral replication and load, leading to a further compromised immune system in people living with HIV (PLWH), it is paramount to address this comorbidity to reduce the NeuroHIV pathogenesis. Non-human primates are well-suited models to study mechanisms involved in HIV neuropathogenesis and provide a better understanding of the underlying mechanisms involved in the comorbidity of HIV and drug abuse, leading to the development of more effective treatments for PLWH. Additionally, using broader behavioral tests in these models can mimic mild NeuroHIV and aid in studying other neurocognitive diseases without encephalitis. The simian immunodeficiency virus (SIV)-infected rhesus macaque model is instrumental in studying the effects of opioid abuse on PLWH due to its similarity to HIV infection. The review highlights the importance of using non-human primate models to study the comorbidity of opioid abuse and HIV infection. It also emphasizes the need to consider modifiable risk factors such as gut homeostasis and pulmonary pathogenesis associated with SIV infection and opioid abuse in this model. Moreover, the review suggests that these non-human primate models can also be used in developing effective treatment strategies for NeuroHIV and opioid addiction. Therefore, non-human primate models can significantly contribute to understanding the complex interplay between HIV infection, opioid abuse, and associated comorbidities.

Inflammation-Associated Lung Tissue Remodeling and Fibrosis in Morphine-Dependent SIV-Infected Macaques

With the advent of antiretroviral therapy, improved survival of people with HIV (PWH) is accompanied with increased prevalence of HIV-associated comorbidities. Chronic lung anomalies are recognized as one of the most devastating sequelae in PWH. The limited available data describing the lung complications in PWH with a history of opioid abuse warrants more research to better define the course of disease pathogenesis. The current study was conducted to investigate the progression of lung tissue remodeling in a morphine (Mor)-exposed rhesus macaque model of SIV infection. Pathologic features of lung remodeling, including histopathologic changes, oxidative stress, inflammation, and proliferation of fibroblasts, were investigated in archival lung tissues of SIVmac-251/macaque model with or without Mor dependence. Lungs of Mor-exposed, SIV-infected macaques exhibited significant fibrotic changes and collagen deposition in the alveolar and the bronchiolar region. There was increased oxidative stress, profibrotic transforming growth factor-β, fibroblast proliferation and trans-differentiation, epithelial-mesenchymal transition, and matrix degradation in SIV-infected macaques, which was further exacerbated in the lungs of Mor-exposed macaques. Interestingly, there was decreased inflammation-associated remodeling in Mor-dependent SIV-infected macaques compared with SIV-infected macaques that did not receive Mor. Thus, the current findings suggest that SIV independently induces fibrotic changes in macaque lungs, which is further aggravated by Mor.