Monocyte activation markers in cerebrospinal fluid associated with impaired neurocognitive testing in advanced HIV infection

Cerebrospinal fluid biomarkers of inflammation and immune activation associated with neurocognitive impairment among US Latinos with HIV

OBJECTIVE

Examine the association between markers of inflammation in the cerebrospinal fluid (CSF) and neurocognitive impairment (NCI) among diverse persons with HIV (PWH).

BACKGROUND

Latino PWH are at higher risk for NCI than non-Latino White PWH (NLW). Evidence of inflammation in CSF can be higher among racial and ethnic minority PWH and has been linked to NCI.

METHODS

We performed a retrospective cross-sectional analysis of 363 PWH who identified as Latinos or NLW. Neurocognitive performance was measured by a comprehensive battery. A focused panel of biomarkers [interleukin-6 (IL-6), soluble CD14 (sCD14), interferon-γ-inducible protein-10 (IP-10), neurofilament light chain (NFL)] was measured in CSF by immunoassay. Covariates included demographic, HIV disease, medical, psychiatric, and substance use characteristics.

RESULTS

The cohort consisted of 126 Latinos and 237 NLW (age: M  = 42.5, SD  = 11.0, 88% male, 51.5% AIDS history; 64% on antiretroviral therapy). Latinos had significantly higher NFL levels than NLW ( P  < 0.0001, adjusted Cohen's d 1.15), but not among virally-suppressed PWH. In the entire cohort, higher sCD14 was associated with NCI (adjusted odds ratio (aOR) = 2.6, confidence interval (CI) = 1.1-6.5] after adjusting for statistically significant covariates.

CONCLUSIONS

We did not identify a relationship between ethnicity, inflammation and NCI in this cohort. Future studies might examine sociocultural factors leading to increased inflammation in the CSF in diverse PWH.

Neuropathogenesis of acute HIV: mechanisms, biomarkers, and therapeutic approaches

PURPOSE OF REVIEW

The neuropathogenesis of acute HIV leads to rapid central nervous system (CNS) involvement, characterized by early viral entry, immune activation, and the formation of viral reservoirs. Despite effective antiretroviral therapy (ART), these reservoirs persist, drive neuroinflammation and injury and lead to HIV-associated neurodegenerative disorders (HAND). This review provides an updated synthesis of the mechanisms in acute HIV neuropathogenesis, biomarkers of CNS injury and emerging therapeutic approaches. A deeper understanding of these mechanisms is critical for addressing persistent HAND in ART-treated individuals.

RECENT FINDINGS

Growing evidence now supports the principal role of infected CD4 + T cells in mediating HIV neuroinvasion alongside monocytes, resulting in seeding in perivascular macrophages, pericytes, and adjacent microglia and astrocytes. These reservoirs contribute to ongoing transcriptional activity and viral persistence despite antiretroviral therapy. Neuroinflammation, driven by activated microglia, astrocytes, inflammasomes, and neurotoxic viral proteins, disrupts neuronal homeostasis. Emerging therapies, including latency-reversing agents and transcription inhibitors, show promise in reducing neuroinflammation and reservoir activity.

SUMMARY

Understanding the mechanisms of HIV neuropathogenesis and reservoir persistence has significant implications for developing targeted therapies to mitigate HAND. Strategies to eliminate CNS reservoirs and reduce neuroinflammation should be prioritized to improve long-term cognitive outcomes in people with HIV.

CD8+T cells and monocytes were associated with brain alterations in human immunodeficiency virus-infected individuals with cognitive impairment

Cognitive impairment (CI) continues to be a concern for people living with HIV-1 (PLWH) in the era of antiretroviral therapy (ART), yet the underlying mechanisms remain unclear. We aimed to elucidate the structural and functional brain alterations and peripheral immune profile of PLWH with CI, as well as the correlation between them. PLWH were divided into CI (n = 30) and cognitive normal (CN, n = 59) groups based on the Montreal Cognitive Assessment, and underwent multi-modal magnetic resonance imaging. Mass cytometry was utilized to profile immune cells, while the liquid chip technique was employed to measure plasma levels of cytokines and chemokines. Spearman correlation analyses were conducted for correlation analysis. Here, we found that the gray matter volume in left supramarginal gyrus was reduced, and the ReHo in the right middle frontal gyrus and the functional connectivity between right middle frontal gyrus and left postcentral gyrus were enhanced in CI group compared to CN group. Additionally, the frequencies of naïve CD8+T cells (Tn) and CD31lowCD8+ Tn were significantly correlated with gray matter volume in the left supramarginal gyrus. The amplitude of low frequency fluctuations in a specific brain region of frontal-middle lobe was negatively correlated with the frequencies of non-classical monocytes (nCM) and their subpopulations (CCR2lownCM, CD57lownCM and CD127+nCM), and positively associated with the plasma interleukin 25 and transforming growth factor-α levels. These findings suggest the association between peripheral immunity and the brain abnormalities in PLWH, highlighting a potential role of the immune-brain-cognition axis in the pathogenesis of CI in Chinese PLWH.

HIV Cerebrospinal Fluid Escape: Interventions for the Management, Current Evidence and Future Perspectives

Neurocognitive impairment is an important cause of HIV-associated morbidity. The advent of antiretroviral therapy (ART) has shifted the spectrum of HIV-associated cognitive impairment from HIV-associated dementia to milder forms of cognitive impairment. Independent replication of HIV within the central nervous system in those on effective ART with peripheral suppression is a recognised phenomenon known as cerebrospinal fluid (CSF) HIV RNA escape. CSF HIV RNA escape is independently associated with neurocognitive impairment but has also been detected in asymptomatic persons with HIV. The current consensus for management of CSF HIV RNA escape is based on expert opinion rather than empirical evidence. The current evidence suggests having a low threshold to investigate for CSF HIV RNA escape and optimising ART based on resistance profiles. The use of central nervous system (CNS) penetration effectiveness scores is no longer recommended. The evidence for statins, SSRIs, minocycline, lithium and valproate is limited to small-scale studies. There are potential new developments in the form of nanoparticles, Janus Kinase inhibitors and latency reversal agents.

Nef mediates neuroimmune response, myelin impairment, and neuronal injury in EcoHIV-infected mice

The introduction of antiretroviral therapy has markedly improved the management of HIV-associated neurocognitive disorders (HAND). However, HAND still affects nearly half of HIV-infected individuals, presenting significant challenges to their well-being. This highlights the critical need for a deeper understanding of HAND mechanisms. Among HIV viral proteins, Nef is notable for its multifaceted role in HIV pathogenesis, though its specific involvement in HAND remains unclear. To investigate this, we used a murine model infected with Nef-expressing (EcoHIV) and Nef-deficient (EcoHIVΔNef) murine HIV. Comparative analyses revealed increased neuroinflammation and reduced myelin and neuronal integrity in EcoHIV-infected brains compared with those with EcoHIVΔNef. Both viruses induced astrogliosis, with stronger GFAP activation in Nef-deficient infections. These findings suggest that Nef contributes to neuroinflammation, primarily through microglial targeting and demyelination, although other factors may regulate astrogliosis. Our results indicate that Nef may significantly contribute to neuronal injury in EcoHIV-infected mice, offering insights into Nef-induced neuropathology in HAND and guiding future research.

Inflammation biomarkers and neurobehavioral performance in rural adolescents

Background

Systemic inflammation has been associated with lower neurobehavioral performance in diverse populations, yet the evidence in adolescents remains lacking. Cytokines can alter neural network activity to induce neurocognitive changes. This work seeks to investigate the association between inflammation and neurobehavior in adolescents living in a rural region of Ecuador.

Methods

We examined 535 adolescents in rural communities of Ecuador (ESPINA study), 508 of which had neurobehavioral assessments (NEPSY-II) and circulating plasma levels of inflammatory markers (CRP, IL-6, TNF-⍺, sICAM-1, sVCAM-1, SAA, and sCD14). Associations between inflammatory biomarker concentrations and neurobehavioral scores were examined using adjusted bivariate semi-parametric models with generalized estimating equations. A partial least squares regression approach was used to create composite variables from multiple inflammation biomarkers and model their association with cognitive outcomes.

Results

Higher sCD14 and TNF-α concentrations were significantly associated with lower social perception scores, by -0.465 units (95% CI: -0.80, -0.13) and -0.418 units (-0.72, -0.12) for every 50% increase in inflammatory marker concentration, respectively. Similarly, every 50% increase in the inflammation summary score was associated with a significantly lower Social Perception score by -0.112 units (-0.19, -0.03). A greater inflammatory composite variable from seven markers was associated with lower scores in language (β = -0.11, p = 0.043), visuospatial processing (β = -0.15, p = 0.086), and social perception (β = -0.22, p = 0.005) domains.

Conclusions

Higher levels of inflammation were associated with lower neurobehavioral performance in adolescents, especially with social perception. In addition, using a robust analytic method to examine an association between a composite inflammatory variable integrating seven markers led to additional findings, including the domains of language and visuospatial processing. A longitudinal follow-up of such investigations could unveil potential changes in inflammation-neurobehavior performance links through developmental stages and intervention opportunities.

Nicotine is an Immunosuppressant: Implications for Women's Health and Disease

A plethora of evidence supports that nicotine, the primary alkaloid in tobacco products that is generally accepted for maintaining use, is immunoregulatory and may function as an immunosuppressant. Women have unique experiences with use of nicotine-containing products and also undergo significant reproductive transitions throughout their lifespan which may be impacted by nicotine use. Within the extant literature, there is conflicting evidence that nicotine may confer beneficial health effects in specific disease states (e.g., in ulcerative colitis). Use prevalence of nicotine-containing products is exceptionally high in individuals presenting with some comorbid disease states that impact immune system health and can be a risk factor for the development of diseases which disproportionately impact women; however, the mechanisms underlying these relationships are largely unclear. Further, little is known regarding the impacts of nicotine's immunosuppressive effects on women's health during the menopausal transition, which is arguably an inflammatory event characterized by a pro-inflammatory peri-menopause period. Given that post-menopausal women are at a higher risk than men for the development of neurodegenerative diseases such as Alzheimer's disease and are also more vulnerable to negative health effects associated with diseases such as HIV-1 infection, it is important to understand how use of nicotine-containing products may impact the immune milieu in women. In this review, we define instances in which nicotine use confers immunosuppressive, anti-inflammatory, or pro-inflammatory effects in the context of comorbid disease states, and focus on how nicotine impacts neuroimmune signaling to maintain use. We posit that regardless of potential health benefits, nicotine use cessation should be a priority in the clinical care of women. The synthesis of this review demonstrates the importance of systematically defining the relationships between volitional nicotine use, immune system function, and comorbid disease states in women to better understand how nicotine impacts women's health and disease.

Innate immune memory in chronic HIV and HIV-associated neurocognitive disorders (HAND): potential mechanisms and clinical implications

Although antiretroviral therapy (ART) has dramatically improved the outlook of the HIV/AIDS pandemic, people living with HIV (PLWH) on suppressive therapy are still at higher risk for a range of comorbidities including cardiovascular disease (CVD) and HIV-associated neurocognitive disorders (HAND), among others. Chronic inflammation and immune activation are thought to be an underlying cause of these comorbidities. Many of the factors thought to drive chronic inflammation and immune activation in HIV overlap with factors known to induce trained immunity. Trained immunity is a form of innate immune memory that metabolically and epigenetically reprograms innate immune cells to mount enhanced inflammatory responses upon secondary encounter with unrelated inflammatory stimuli. While this phenotype has been characterized in a variety of disease states in animals and humans, very little is known about its potential contribution to chronic HIV pathogenesis. In this review, a broad overview of innate immune memory in the periphery and the central nervous system (CNS) is provided and the evidence for trained immunity in the context of HIV is considered. In PLWH on ART, this phenotype could contribute to the chronic inflammation and immune activation associated with HIV comorbidities and could complicate HIV cure strategies due to the potential persistence of the phenotype after eradication of the virus. Further research into this immune state in the context of HIV may open the door for new therapeutics aimed at treating HIV comorbidities like HAND.

Inflammation biomarkers and neurobehavioral performance in rural adolescents

Background

Systemic inflammation has been associated with lower neurobehavioral performance in diverse populations, yet the evidence in adolescents remains lacking. Cytokines can alter neural network activity to induce neurocognitive changes. This work seeks to investigate the association between inflammation and neurobehavior in adolescents living in a rural region of Ecuador.

Methods

We examined 535 adolescents in rural communities of Ecuador (ESPINA study), 508 of which had neurobehavioral assessments (NEPSY-II) and circulating plasma levels of inflammatory markers (CRP, IL-6, TNF-⍺, sICAM-1, sVCAM-1, SAA, and sCD14). Associations between inflammatory biomarker concentrations and neurobehavioral scores were examined using adjusted bivariate semi-parametric models with generalized estimating equations. A partial least square regression approach was used to create composite variables from multiple inflammation biomarkers and model their association with cognitive outcomes.

Results

Higher sCD14 and TNF-α concentrations were significantly associated with lower social perception scores, by -0.47 units (95% CI: -0.80, -0.13) and -0.42 (-0.72, -0.12) for every 50% increase in inflammatory marker concentration, respectively. Similarly, every 50% increase in the inflammation summary score was associated with a significantly lower Social Perception score by -0.11 units (-0.19, -0.03). A unit increase in inflammatory composites of seven markers were associated with lower scores in language (-0.11 units, p=0.04), visuospatial processing (-0.15, p= 0.09), and social perception (-0.22, p=0.005) domains.

Conclusions

Higher levels of inflammation were associated with lower neurobehavioral performance in adolescents, especially with social perception. In addition, using a robust analytic method to examine an association between a composite inflammatory variable integrating seven markers led to additional findings, including the domains of language and visuospatial processing. A longitudinal follow-up of such investigations could unveil potential changes in inflammation-neurobehavior performance links through developmental stages and intervention opportunities.

CD14+CD16+ monocyte transmigration across the blood-brain barrier is associated with HIV-NCI despite viral suppression

HIV-associated neurocognitive impairment (HIV-NCI) affects 15%-50% of people with HIV (PWH), despite viral suppression with antiretroviral therapy (ART). HIV neuropathogenesis is mediated, in part, by transmigration of infected CD14+CD16+ monocytes across the blood-brain barrier (BBB) into the central nervous system (CNS). In the CNS, CD14+CD16+ monocytes contribute to infection and activation of parenchymal cells, resulting in production of neurotoxic viral and host factors that cause neuronal damage. Mechanisms by which CD14+CD16+ monocytes contribute to HIV-NCI have not been characterized in a study population of PWH on ART without contribution from confounders that affect cognition (e.g., substance use, hepatitis C virus coinfection). We assessed cognitive function, PBMC transmigration across the BBB, and neuronal health markers in a well-defined cohort of 56 PWH on ART using stringent criteria to eliminate confounding factors. We demonstrated that PWH on ART with HIV-NCI have significantly increased transmigration of their CD14+CD16+ monocytes across the BBB compared with those with normal cognition. We showed that hypertension and diabetes may be effect modifiers on the association between CD14+CD16+ monocyte transmigration and cognition. This study underscored the persistent role of CD14+CD16+ monocytes in HIV-NCI, even in PWH with viral suppression, suggesting them as potential targets for therapeutic interventions.

Changes in cerebrospinal fluid proteins across the spectrum of untreated and treated chronic HIV-1 infection

Using the Olink Explore 1536 platform, we measured 1,463 unique proteins in 303 cerebrospinal fluid (CSF) specimens from four clinical centers contributed by uninfected controls and 12 groups of people living with HIV-1 infection representing the spectrum of progressive untreated and treated chronic infection. We present three initial analyses of these measurements: an overview of the CSF protein features of the sample; correlations of the CSF proteins with CSF HIV-1 RNA and neurofilament light chain protein (NfL) concentrations; and comparison of CSF proteins in HIV-associated dementia (HAD) and neurosymptomatic CSF escape (NSE). These reveal a complex but coherent picture of CSF protein changes with highest concentrations of many proteins during CNS injury in the HAD and NSE groups and variable protein changes across the course of systemic HIV-1 progression that included two common patterns, designated as lymphoid and myeloid patterns, related to principal involvement of their underlying inflammatory cell lineages. Antiretroviral therapy reduced CSF protein perturbations, though not always to control levels. The dataset of these CSF protein measurements, along with background clinical information, is posted online. Extended studies of this unique dataset will supplement this report to provide more detailed characterization of the dynamic impact of HIV-1 infection on the CSF proteome across the spectrum of HIV-1 infection, advancing the mechanistic understanding of HIV-1-related CNS pathobiology.

Age-associated dementia among older people aging with HIV in the United States: a modeling study

OBJECTIVE

Almost 400 000 people with HIV (PWH) in the United States are over age 55 years and at risk for age-associated dementias (AAD), including Alzheimer's disease and vascular contributions to cognitive impairment and dementia (VCID). We projected the cumulative incidence and mortality associated with AAD among PWH at least 60 years in the United States compared with the general population.

DESIGN/METHODS

Integrating the CEPAC and AgeD-Pol models, we simulated two cohorts of 60-year-old male and female individuals: PWH, and the general US population. We estimated AAD incidence and AAD-associated mortality rates. Projected outcomes included AAD cumulative incidence, life expectancy, and quality-adjusted life-years (QALYs). We performed sensitivity and scenario analyses on AAD-specific (e.g. incidence) and HIV-specific (e.g. disengagement from HIV care) parameters, as well as premature aging among PWH.

RESULTS

We projected that 22.1%/16.3% of 60-year-old male individuals/female individuals with HIV would develop AAD by 80 years compared with 15.9%/13.3% of male individuals/female individuals in the general population. Accounting for age-associated and dementia-associated quality of life, 60-year-old PWH would have a lower life expectancy (QALYs): 17.4 years (14.1 QALYs) and 16.8 years (13.4 QALYs) for male and female individuals, respectively, compared with the general population [male individuals, 21.7 years (18.4 QALYs); female individuals, 24.7 years (20.2 QALYs)]. AAD cumulative incidence was most sensitive to non-HIV-related mortality, engagement in HIV care, and AAD incidence rates.

CONCLUSION

Projected estimates of AAD-associated morbidity, mortality, and quality of life can inform decision-makers and health systems planning as the population of PWH ages. Improved AAD prevention, treatment, and supportive care planning are critical for people aging with HIV.

Changes in Cerebrospinal Fluid Proteins across the Spectrum of Untreated and Treated Chronic HIV-1 Infection

Using the Olink Explore 1536 platform, we measured 1,463 unique proteins in 303 cerebrospinal fluid (CSF) specimens from four clinical centers that included uninfected controls and 12 groups of people living with HIV-1 infection representing the spectrum of progressive untreated and treated chronic infection. We present three initial analyses of these measurements: an overview of the CSF protein features of the sample; correlations of the CSF proteins with CSF HIV-1 RNA and neurofilament light chain protein (NfL) concentrations; and comparison of the CSF proteins in HIV-associated dementia ( HAD ) and neurosymptomatic CSF escape ( NSE ). These reveal a complex but coherent picture of CSF protein changes that includes highest concentrations of many proteins during CNS injury in the HAD and NSE groups and variable protein changes across the course of neuroasymptomatic systemic HIV-1 progression, including two common patterns, designated as lymphoid and myeloid patterns, related to the principal involvement of their underlying inflammatory cell lineages. Antiretroviral therapy reduced CSF protein perturbations, though not always to control levels. The dataset of these CSF protein measurements, along with background clinical information, is posted online. Extended studies of this unique dataset will provide more detailed characterization of the dynamic impact of HIV-1 infection on the CSF proteome across the spectrum of HIV-1 infection, and further the mechanistic understanding of HIV-1-related CNS pathobiology.

Multimodal Approach to Neurocognitive Function in People Living with HIV in the cART Era: A Comprehensive Review

Combination antiretroviral treatment (cART) has revolutionized the management of human immunodeficiency virus (HIV) and has markedly improved the disease burden and life expectancy of people living with HIV. HIV enters the central nervous system (CNS) early in the course of infection, establishes latency, and produces a pro-inflammatory milieu that may affect cognitive functions, even in the cART era. Whereas severe forms of neurocognitive impairment (NCI) such as HIV-associated dementia have declined over the last decades, milder forms have become more prevalent, are commonly multifactorial, and are associated with comorbidity burdens, mental health, cART neurotoxicity, and ageing. Since 2007, the Frascati criteria have been used to characterize and classify HIV-associated neurocognitive disorders (HAND) into three stages, namely asymptomatic neurocognitive impairment (ANI), mild neurocognitive disorder (MND), and HIV-associated dementia (HAD). These criteria are based on a comprehensive neuropsychological assessment that presupposes the availability of validated, demographically adjusted, and normative population data. Novel neuroimaging modalities and biomarkers have been proposed in order to complement NCI assessments, elucidate neuropathogenic mechanisms, and support HIV-associated NCI diagnosis, monitoring, and prognosis. By integrating neuropsychological assessments with biomarkers and neuroimaging into a holistic care approach, clinicians can enhance diagnostic accuracy, prognosis, and patient outcomes. This review interrogates the value of these modes of assessment and proposes a unified approach to NCI diagnosis.

Intrathecal production of anti-Epstein-Barr virus viral capsid antigen IgG is associated with neurocognition and tau proteins in people with HIV

OBJECTIVE

HIV and Epstein-Barr virus (EBV) co-infection has been linked to increased immune activation and larger HIV reservoir. We assessed whether anti-EBV humoral responses are associated with increased cerebrospinal fluid (CSF) inflammation and with neurocognitive impairment (NCI) in people with HIV (PWH).

DESIGN

Cross-sectional analysis in 123 EBV-seropositive PWH either on antiretroviral therapy ( n  = 70) or not.

METHODS

Serum and CSF anti-EBV viral capsid antigen immunoglobulin G (anti-EVI) and CSF EBV DNA were measured by commercial immunoassay and RT-PCR. Seventy-eight participants without neurological confounding factors underwent neurocognitive assessment (Global Deficit Score, GDS). CSF total tau and 181-phosphorylated-tau (ptau) were measured by immunoassays together with biomarkers of blood-brain barrier (BBB) integrity, immune activation, astrocytosis, and intrathecal synthesis. Logistic and linear regressions and moderation analysis were used to investigate the relationships between CSF anti-EVI, GDS, and biomarkers.

RESULTS

Twenty-one (17.1%) and 22 participants (17.9%) had detectable CSF anti-EVI (10.5-416.0 U/ml) and CSF EBV DNA (25-971 copies/ml). After adjusting for BBB integrity, age, and clinical factors, the presence of CSF anti-EVI was only associated with serum levels of anti-EVI, and not with CSF EBV DNA. CSF anti-EVI, tau and ptau showed reciprocal interactions affecting their associations with GDS. After adjusting for demographics and clinical parameters, higher CSF anti-EVI levels were associated with worse GDS (aβ 0.45, P  < 0.001), and CSF levels of tau and ptau had a moderation effect on the strength of this association (models' P  < 0.001).

CONCLUSION

Humoral immune responses against EBV within the central nervous system may contribute to NCI in PWH through mechanisms that involve neuronal injury.

The relationship between HIV-1 neuroinflammation, neurocognitive impairment and encephalitis pathology: A systematic review of studies investigating post-mortem brain tissue

The activities of HIV-1 in the central nervous system (CNS) are responsible for a dysregulated neuroinflammatory response and the subsequent development of HIV-associated neurocognitive disorders (HAND). The use of post-mortem human brain tissue is pivotal for studying the neuroimmune mechanisms of CNS HIV infection. To date, numerous studies have investigated HIV-1-induced neuroinflammation in post-mortem brain tissue. However, from the commonly investigated studies in this line of research, it is not clear which neuroinflammatory markers are consistently associated with HIV neurocognitive impairment (NCI) and neuropathology (i.e., HIV-encephalitis, HIVE). Therefore, we conducted a systematic review of the association between neuroinflammation and NCI/HIVE from studies investigating post-mortem brain tissue. Our aim was to synthesise the published data to date to provide commentary on the most noteworthy markers that are associated with NCI/HIVE. PubMed, Scopus, and Web of Science databases were searched using a search protocol designed specifically for this study. Sixty-one studies were included that investigated the levels of inflammatory markers based on their gene and protein expression in association with NCI/HIVE. The findings revealed that the (1) transcript expressions of IL-1β and TNF-α were consistently associated with NCI/HIVE, whereas CCL2 and IL-6 were commonly not associated with NCI/HIVE, (2) protein expressions of CD14, CD16, CD68, Iba-1, IL-1β and TNF-α were consistently associated with NCI/HIVE, while CD45, GFAP, HLA-DR, IL-1 and IL-6 were commonly not associated with NCI/HIVE, and (3) gene and protein expressions of CNS IL-1β and TNF-α were consistently associated with NCI/HIVE, while IL-6 was consistently not associated with NCI/HIVE. These markers highlight the commonly investigated markers in this line of research and elucidates the neuroinflammatory mechanisms in the HIV-1 brain that are involved in the pathophysiology of NCI/HIVE. These markers and related pathways should be investigated for the development of improved diagnostics, prognostics, and therapeutics of HAND.

Pillars of long-term antiretroviral therapy success

BACKGROUND

Meeting the challenge of antiretroviral therapy (ART) whose efficacy can last a lifetime requires continuous updating of the virological, pharmacological, and quality of life outcomes to be pursued and a continuous review of literature data on the efficacy and tolerability of new drugs and therapeutic strategies.

METHODS

With the aim of identifying open questions and answers about the current controversies in modern ART, we adapted the Design Thinking methodology to the needs of the design phase of a scientific article, involving a team of experts in HIV care.

RESULTS

Five main pillars of treatment success were discussed: sustained virologic suppression over time; immunological recovery; pharmacological attributes; long-term tolerability and safety of ART; and people's satisfaction and quality of life. The definition of the outcomes to be achieved in each thematic area and the tools to achieve them were reviewed and discussed.

CONCLUSIONS

Long-term treatment success should be intended as a combination of HIV-RNA suppression, immune recovery, and high quality of life. To achieve this, the regimen should be well-tolerated, with high potency, genetic barrier, and forgiveness, and should be tailored by a person-centered perspective, based on individual needs, preferences, and therapeutic history.

Probing bundle-wise abnormalities in patients infected with human immunodeficiency virus using fixel-based analysis: new insights into neurocognitive impairments

BACKGROUND

Changes in white matter (WM) underlie the neurocognitive damages induced by a human immunodeficiency virus (HIV) infection. This study aimed to examine using a bundle-associated fixel-based analysis (FBA) pipeline for investigating the microstructural and macrostructural alterations in the WM of the brain of HIV patients.

METHODS

This study collected 93 HIV infected patients and 45 age/education/handedness matched healthy controls (HCs) at the Beijing Youan Hospital between January 1, 2016 and December 30, 2016.All HIV patients underwent neurocognitive evaluation and laboratory testing followed by magnetic resonance imaging (MRI) scanning. In order to detect the bundle-wise WM abnormalities accurately, a specific WM bundle template with 56 tracts of interest was firstly generated by an automated fiber clustering method using a subset of subjects. Fixel-based analysis was used to investigate bundle-wise differences between HIV patients and HCs in three perspectives: fiber density (FD), fiber cross-section (FC), and fiber density and cross-section (FDC). The between-group differences were detected by a two-sample t -test with the false discovery rate (FDR) correction ( P <0.05). Furthermore, the covarying relationship in FD, FC and FDC between any pair of bundles was also accessed by the constructed covariance networks, which was subsequently compared between HIV and HCs via permutation t -tests. The correlations between abnormal WM metrics and the cognitive functions of HIV patients were explored via partial correlation analysis after controlling age and gender.

RESULTS

Among FD, FC and FDC, FD was the only metric that showed significant bundle-wise alterations in HIV patients compared to HCs. Increased FD values were observed in the bilateral fronto pontine tract, corona radiata frontal, left arcuate fasciculus, left corona radiata parietal, left superior longitudinal fasciculus III, and right superficial frontal parietal (SFP) (all FDR P <0.05). In bundle-wise covariance network, HIV patients displayed decreased FD and increased FC covarying patterns in comparison to HC ( P <0.05) , especially between associated pathways. Finally, the FCs of several tracts exhibited a significant correlation with language and attention-related functions.

CONCLUSIONS

Our study demonstrated the utility of FBA on detecting the WM alterations related to HIV infection. The bundle-wise FBA method provides a new perspective for investigating HIV-induced microstructural and macrostructural WM-related changes, which may help to understand cognitive dysfunction in HIV patients thoroughly.

CSF Inflammation Markers Associated with Asymptomatic Viral Escape in Cerebrospinal Fluid of HIV-Positive Individuals on Antiretroviral Therapy

HIV establishes a viral reservoir in the CNS despite viral suppression in the blood on antiretroviral therapy (ART). In a minority of people with HIV (PWH), HIV RNA is detectable in CSF when HIV RNA in plasma is undetectable or HIV RNA levels are higher in CSF compared with plasma, an event termed CSF viral escape that can occur with or without neurological symptoms. Asymptomatic CSF viral escape occurs in 3-20% of PWH on ART, yet associated biomarkers are unclear. To identify biomarkers associated with asymptomatic CSF viral escape, we performed a matched group study of PWH on ART with vs. without CSF viral escape (n = 10 and n = 60, respectively, matched for age, duration of HIV infection, nadir CD4 count, and ART regimen) and 50 HIV-negative controls. PWH were on 3 or more ART drugs for >1 year, and the group with no CSF viral escape was suppressed below 50 copies/mL in plasma and CSF. Biomarkers of inflammation (IFN-γ, IL-1β, IL-6, IL-8, IL-15, IP-10, MCP-1, VEGF), cell adhesion (ICAM-1, VCAM-1), CNS injury (NFL), and glial activation (GFAP, YKL-40) were measured in paired plasma and CSF using the Meso Scale Discovery platform. PWH with vs. without CSF viral escape had more individuals (40%) with a plasma viral load (VL) > 50 copies/mL, higher CSF VL (median 156 vs. 40 copies/mL; p < 0.0001), lower CD4 count (318 vs. 512; p = 0.045), and higher CSF WBC (median [IQR] 4 [0-22] vs. 2 [0-4] cells/µL; p = 0.15) but similar proportions with HIV-associated neurocognitive disorders (HAND) (50% vs. 47%). CSF viral escape was associated with increased IL-1β, IFN-γ, IP-10, ICAM-1, and VCAM-1 in CSF but not plasma; IP-10 had the strongest association (p = 0.0008). CSF VL and WBC correlated with IFN-γ, IP-10, ICAM-1, and VCAM-1 (p < 0.05). Although markers of CNS injury showed no significant association with asymptomatic CSF viral escape, CSF YKL-40 correlated positively with CSF IL-1β (p = 0.003), IFN-γ (p = 0.0008), IP-10 (p < 0.0001), and NFL (p = 0.06) and negatively with neurocognitive T scores (p = 0.02). These findings identify CSF inflammation and glial activation markers that may serve as surrogate measures of HIV persistence in the CNS for future studies on therapeutics targeting the CNS reservoir.

Microglial/macrophage activation in the cerebrospinal fluid of neuromyelitis optica spectrum disorders

AIM

The aims of this pilot study were to investigate the levels of biomarkers of microglial/macrophage activation-YKL-40, sCD163, and sCD14-in patients with neuromyelitis optica spectrum disorder (NMOSD) and determine the possible associations between these biomarkers and Expanded Disability Status Scale (EDSS) scores.

METHODS

We measured the levels of three microglia-/macrophage-related proteins (YKL-40, soluble CD163, and soluble CD14) in cerebrospinal fluid (CSF) using enzyme-linked immunosorbent assays. In addition, patients' neurological disability levels were assessed using EDSS scores.

RESULTS

NMOSD patients had significantly higher CSF levels of YKL-40(210.52 ± 161.62 for NMOSD and 63.18 ± 9.22 for control), sCD163 (87.23 ± 56.85 for NMOSD and 58.14 ± 7.66 for control), and sCD14 (68.22 ± 24.11 for NMOSD and 55.75 ± 9.48 for control) compared with controls. Furthermore, these biomarker levels were positively correlated with EDSS scores in patients with NMOSD (r = 0.303, p = .002 for YKL-40; r = 0310, p = .001 for sCD14; r = 0.250, p = .011 for sCD163), but not in patients with multiple sclerosis or glial fibrillary acidic protein astrocytopathy.

CONCLUSION

Our findings suggest that microglial/macrophage activation may be implicated in the pathogenesis of NMOSD.

Buprenorphine reverses neurocognitive impairment in EcoHIV infected mice: A potential therapy for HIV-NCI

Thirty-eight million people worldwide are living with HIV, PWH, a major public health problem. Antiretroviral therapy (ART) revolutionized HIV treatment and significantly increased the lifespan of PWH. However, approximately 15-50% of PWH develop HIV associated neurocognitive disorders (HIV-NCI), a spectrum of cognitive deficits, that negatively impact quality of life. Many PWH also have opioid use disorder (OUD), and studies in animal models of HIV infection as well as in PWH suggest that OUD can contribute to HIV-NCI. The synthetic opioid agonist, buprenorphine, treats OUD but its effects on HIV-NCI are unclear. We reported that human mature inflammatory monocytes express the opioid receptors MOR and KOR, and that buprenorphine reduces important steps in monocyte transmigration. Monocytes also serve as HIV reservoirs despite effective ART, enter the brain, and contribute to HIV brain disease. Using EcoHIV infected mice, an established model of HIV infection and HIV-NCI, we previously showed that pretreatment of mice prior to EcoHIV infection reduces mouse monocyte entry into the brain and prevents NCI. Here we show that buprenorphine treatment of EcoHIV infected mice with already established chronic NCI completely reverses the disease. Disease reversal was associated with a significant reduction in brain inflammatory monocytes and reversal of dendritic injury in the cortex and hippocampus. These results suggest that HIV-NCI persistence may require a continuing influx of inflammatory monocytes into the brain. Thus, we recommend buprenorphine as a potential therapy for mitigation of HIV brain disease in PWH with or without OUD.

Non-Human Primate Models of HIV Brain Infection and Cognitive Disorders

Human Immunodeficiency virus (HIV)-associated neurocognitive disorders are a major burden for people living with HIV whose viremia is stably suppressed with antiretroviral therapy. The pathogenesis of disease is likely multifaceted, with contributions from viral reservoirs including the brain, chronic and systemic inflammation, and traditional risk factors including drug use. Elucidating the effects of each element on disease pathogenesis is near impossible in human clinical or ex vivo studies, facilitating the need for robust and accurate non-human primate models. In this review, we describe the major non-human primate models of neuroHIV infection, their use to study the acute, chronic, and virally suppressed infection of the brain, and novel therapies targeting brain reservoirs and inflammation.

Neuropathogenesis of HIV-1: insights from across the spectrum of acute through long-term treated infection

This review outlines the neuropathogenesis of HIV, from initial HIV entry into the central nervous system (CNS) to chronic infection, focusing on key advancements in the last 5 years. Discoveries regarding acute HIV infection reveal timing and mechanisms of early HIV entry and replication in the CNS, early inflammatory responses, and establishment of genetically distinct viral reservoirs in the brain. Recent studies additionally explore how chronic HIV infection is maintained in the CNS, examining how the virus remains in a latent "hidden" state in diverse cells in the brain, and how this leads to sustained pathological inflammatory responses. Despite viral suppression with antiretroviral therapy, HIV can persist and even replicate in the CNS, and associate with ongoing neuropathology including CD8 + T-lymphocyte mediated encephalitis. Crucial investigation to advance our understanding of the immune mechanisms that both control viral infection and lead to pathological consequences in the brain is necessary to develop treatments to optimize long-term neurologic health in people living with HIV.

Application of Diffusion Tensor Imaging (DTI) in the Diagnosis of HIV-Associated Neurocognitive Disorder (HAND): A Meta-Analysis and a System Review

Background

The patients with HIV-associated neurocognitive disorder (HAND) are often accompanied by white matter structure damage. Diffusion tensor imaging (DTI) is an important tool to detect white matter structural damage. However, the changes in DTI values reported in many studies are diverse in different white matter fiber tracts and brain regions.

Purpose

Our research is dedicated to evaluating the consistency and difference of the correlation between HAND and DTI measures in different studies. Additionally, the value of DTI in HAND evaluation is used to obtain consensus and independent conclusions between studies.

Methods

We searched PubMed and Web of Science to collect relevant studies using DTI for the diagnosis of HAND. After screening and evaluating the search results, meta-analysis is used for quantitative research on data. Articles that cannot collect data but meet the research relevance will be subjected to a system review.

Results

The meta-analysis shows that the HAND group has lower fractional anisotropy (standardized mean difference = −0.57 p < 0.0001) and higher mean diffusivity (standardized mean difference = 0.04 p < 0.0001) than the healthy control group in corpus callosum. In other white matter fibers, we found similar changes in fractional anisotropy (standardized mean difference = −1.18 p < 0.0001) and mean diffusivity (standardized mean difference = 0.69 p < 0.0001). However, the heterogeneity (represented by I²) between the studies is high (in corpus callosum 94, 88%, in other matter fibers 95, 81%). After subgroup analysis, the heterogeneity is obtained as 19.5, 40.7% (FA, MD in corpus callosum) and 0, 0% (FA, MD among other white matter fibers).

Conclusion

The changes in white matter fibers in patients with HAND are statistically significant at the observation level of DTI compared with healthy people. The differences between the studies are mainly derived from demographics, start and maintenance time of antiretroviral therapy, differences in nadir CD4+T cells, and the use of different neurocognitive function scales. As an effective method to detect the changes in white matter fibers, DTI is of great significance for the diagnosis of HAND, but there are still some shortcomings. In the absence of neurocognitive function scales, independent diagnosis remains difficult.

Systematic Review Registration:https://inplasy.com/inplasy-2021-10-0079/.

Soluble CD14 is subtype-dependent in serum but not in cerebrospinal fluid in people with HIV

Monocytes and macrophages activation are crucial in human immunodeficiency virus (HIV) central nervous system (CNS) infection and HIV associated neurocognitive disorders (HAND) pathogenesis. The soluble form of CD14 (sCD14) is a marker of monocyte activation. We hypothesized that sCD14 levels would be lower in people with HIV-1 subtype C (HIV-1C) than in HIV-1B owing to a variant Tat cysteine dimotif (C30S31) with reduced chemotactic activity. A total of 68 paired cerebrospinal fluid (CSF) and blood samples from people with HIV (PWH); 27 samples of the HIV-1B subtype and 40 of the non-B HIV-1 subtypes (including 26,HIV-1C), and 18 HIV-negative controls were included. sCD14 levels were quantified using a high-sensitivity enzyme-linked immunosorbent assay. sCD14 increase in serum, but not in CSF, was higher in samples from HIV-1B than HIV-1C (p = 0.002; Cohen's d, 0.7). CSF or serum sCD14 values were not correlated with global deficit score or specific cognitive domains. The impact of HIV-1 on monocyte stimulation biomarkers evaluated by sCD14 in serum was subtype-dependent, higher in HIV-1B than HIV-1C, consistent with reduced chemotactic activity as hypothesized.

Elevated Cerebrospinal Fluid Anti-CD4 Autoantibody Levels in HIV Associate with Neuroinflammation

The mechanisms of persistent central nervous system (CNS) inflammation in people with HIV (PWH) despite effective antiretroviral therapy (ART) are not fully understood. We have recently shown that plasma anti-CD4 IgGs contribute to poor CD4⁺ T cell recovery during suppressive ART via antibody-mediated cytotoxicity (ADCC) against CD4⁺ T cells, and that plasma anti-CD4 IgG levels are associated with worse cognitive performance and specific brain area atrophy. However, the role of anti-CD4 IgGs in neuroinflammation remains unclear. In the current study, plasma and cerebrospinal fluid (CSF) samples from 31 ART-naive and 26 treated, virologically suppressed PWH, along with 16 HIV-seronegative controls, were evaluated for CSF levels of anti-CD4 IgG, white blood cell (WBC) counts, soluble biomarkers of neuroinflammation, and neurofilament light chain (NfL). We found that 37% of the PWH exhibited elevated CSF anti-CD4 IgG levels, but few or none of the PWH were observed with elevated CSF anti-CD4 IgM, anti-CD8 IgG, or anti-double-strand DNA IgG. CSF anti-CD4 IgG levels in PWH were directly correlated with neuroinflammation (WBC counts, neopterin, and markers of myeloid cell activation), but not with CSF NfL levels. Using cells from one immune nonresponder to ART, we generated a pathogenic anti-CD4 monoclonal IgG (JF19) presenting with ADCC activity; JF19 induced the production of soluble CD14 (sCD14) and interleukin-8 (IL-8) in human primary monocyte-derived macrophages via CD4 binding in vitro. This study demonstrates for the first time that elevated CSF anti-CD4 IgG levels present in a subgroup of PWH which may play a role in neuroinflammation in HIV.

IMPORTANCE This study reports that an autoantibody presents in the CNS of HIV patients and that its levels in the CSF correlate with some markers of neuroinflammation.

Persistent Inflammation and Non-AIDS Comorbidities During ART: Coming of the Age of Monocytes

Monocytes are innate immune cells that serve as the first line of defense against pathogens by engulfing and destroying pathogens or by processing and presenting antigens to initiate adaptive immunity and stimulate immunological responses. Monocytes are classified into three types: classical, intermediate, and non-classical monocytes, each of which plays a particular function in response to pathogens. Human immunodeficiency virus type 1 (HIV-1) infection disrupts the balance of monocyte subsets, and the quantity and function of monocytes will not fully recover even with long-term antiretroviral therapy (ART). Monocytes are vital for the establishment and maintenance of HIV-1 latent viral reservoirs and are closely related to immune dysfunction even after ART. Therefore, the present review focuses on the phenotypic function of monocytes and their functions in HIV-1 infection to elucidate their roles in HIV patients.

Immune Dysregulation Is Associated with Neurodevelopment and Neurocognitive Performance in HIV Pediatric Populations-A Scoping Review

HIV-1 is known for its complex interaction with the dysregulated immune system and is responsible for the development of neurocognitive deficits and neurodevelopmental delays in pediatric HIV populations. Considering that HIV-1-induced immune dysregulation and its association with neurodevelopmental and neurocognitive impairments in pediatric populations are not well understood, we conducted a scoping review on this topic. The study aimed to systematically review the association of blood and cerebrospinal fluid (CSF) immune markers with neurocognitive deficits and neurodevelopmental delays in pediatric HIV populations. PubMed, Scopus, and Web of Science databases were searched using a search protocol designed specifically for this study. Studies were selected based on a set eligibility criterion. Titles, abstracts, and full texts were assessed by two independent reviewers. Data from the selected studies were extracted and analyzed by two independent reviewers. Seven studies were considered eligible for use in this context, which included four cross-sectional and three longitudinal studies. An average of 130 (±70.61) children living with HIV, 138 (±65.37) children exposed to HIV but uninfected and 90 (±86.66) HIV-negative participants were included across the seven studies. Results indicate that blood and CSF immune markers are associated with neurocognitive development/performance in pediatric HIV populations. Only seven studies met the inclusion criteria, therefore, these limited the number of significant conclusions which could have been made by using such an approach. All considered, the evidence suggests that immune dysregulation, as in the case of adult HIV populations, also has a significant association with neurocognitive performance in pediatric HIV populations.

Soluble Biomarkers of Cognition and Depression in Adults with HIV Infection in the Combination Therapy Era

PURPOSE OF REVIEW

Cognitive impairment and depression continue to be common among people with HIV (PWH) in the combination antiretroviral therapy (ART) era. A better understanding of the biological mechanisms that may underpin these disorders is needed. The purpose of this review is to describe published findings on soluble biomarkers from blood and cerebrospinal fluid (CSF) that have been associated with either cognition or depression among PWH in the setting of ART.

RECENT FINDINGS

Several biomarkers, including those that reflect viral persistence, monocyte/macrophage activation, and other processes, are associated with cognition and depressive symptoms. Some but not all results have been consistent across multiple studies. More research has been published on biomarkers of cognition relative to biomarkers of depression (particularly from CSF). More studies are needed that investigate multiple biomarkers to understand the role of distinct but additive pathways in these disorders and to guide the development of new therapies.

Cerebrovascular Contributions to Neurocognitive Disorders in People Living With HIV

BACKGROUND

To investigate a comprehensive array of magnetic resonance imaging (MRI)-based biomarkers of cerebrovascular disease (CVD) in a cohort of people living with HIV (PLWH) and relate these imaging biomarkers to cognition.

SETTINGS

Cross-sectional, community-based study.

METHODS

Participants were PLWH in New York City, aged 50 years or older. They underwent a brain magnetic resonance angiography or MRI to ascertain 7 MRI markers of CVD: silent brain infarcts, dilated perivascular spaces, microhemorrhages, white matter hyperintensity volume, white matter fractional anisotropy and mean diffusivity (measures of white matter integrity), and intracranial large artery stenosis. Participants underwent a battery of neurocognitive tests to obtain individual and global cognitive scores representative of various aspects of cognition.

RESULTS

We included 85 participants (mean age 60 ± 6 years, 48% men, 78% non-Hispanic Black), most of them with well-controlled HIV (75% with CD4 cell count > 200 cells/mm3 and viral load < 400 copies/mL at or near the time of the MRI scan). Silent brain infarcts, intracranial large artery stenosis, and poor white matter integrity were associated with poorer performance in at least one cognitive domain, but the sum of these 3 MRI markers of CVD was associated with lower working memory (B = -0.213, P = 0.028), list learning (B = -0.275, P = 0.019), and global cognition (B = -0.129, P = 0.007).

CONCLUSIONS

We identified silent brain infarcts, intracranial large artery stenosis, and poor white matter integrity as exposures that may be modifiable and may, therefore, influence cognitive decline. In addition, these MRI markers of CVD may help in identifying PLWH at higher risk of cognitive decline, which may be more amenable to targeted therapies.

Advances in the Experimental Models of HIV-Associated Neurological Disorders

PURPOSE OF REVIEW

Involvement of the central nervous system (CNS) in HIV-1 infection is commonly associated with neurological disorders and cognitive impairment, commonly referred to as HIV-associated neurocognitive disorders (HAND). Severe and progressive neurocognitive impairment is rarely observed in the post-cART era; however, asymptomatic and mild neurocognitive disorders still exist, despite viral suppression. Additionally, comorbid conditions can also contribute to the pathogenesis of HAND.

RECENT FINDINGS

In this review, we summarize the characterization of HAND, factors contributing, and the functional impairments in both preclinical and clinical models. Specifically, we also discuss recent advances in the animal models of HAND and in in vitro cultures and the potential role of drugs of abuse in this model system of HAND. Potential peripheral biomarkers associated with HAND are also discussed. Overall, this review identifies some of the recent advances in the field of HAND in cell culture studies, animal models, clinical findings, and the limitations of each model system, which can play a key role in developing novel therapeutics in the field.

Co-receptor signaling in the pathogenesis of neuroHIV

The HIV co-receptors, CCR5 and CXCR4, are necessary for HIV entry into target cells, interacting with the HIV envelope protein, gp120, to initiate several signaling cascades thought to be important to the entry process. Co-receptor signaling may also promote the development of neuroHIV by contributing to both persistent neuroinflammation and indirect neurotoxicity. But despite the critical importance of CXCR4 and CCR5 signaling to HIV pathogenesis, there is only one therapeutic (the CCR5 inhibitor Maraviroc) that targets these receptors. Moreover, our understanding of co-receptor signaling in the specific context of neuroHIV is relatively poor. Research into co-receptor signaling has largely stalled in the past decade, possibly owing to the complexity of the signaling cascades and functions mediated by these receptors. Examining the many signaling pathways triggered by co-receptor activation has been challenging due to the lack of specific molecular tools targeting many of the proteins involved in these pathways and the wide array of model systems used across these experiments. Studies examining the impact of co-receptor signaling on HIV neuropathogenesis often show activation of multiple overlapping pathways by similar stimuli, leading to contradictory data on the effects of co-receptor activation. To address this, we will broadly review HIV infection and neuropathogenesis, examine different co-receptor mediated signaling pathways and functions, then discuss the HIV mediated signaling and the differences between activation induced by HIV and cognate ligands. We will assess the specific effects of co-receptor activation on neuropathogenesis, focusing on neuroinflammation. We will also explore how the use of substances of abuse, which are highly prevalent in people living with HIV, can exacerbate the neuropathogenic effects of co-receptor signaling. Finally, we will discuss the current state of therapeutics targeting co-receptors, highlighting challenges the field has faced and areas in which research into co-receptor signaling would yield the most therapeutic benefit in the context of HIV infection. This discussion will provide a comprehensive overview of what is known and what remains to be explored in regard to co-receptor signaling and HIV infection, and will emphasize the potential value of HIV co-receptors as a target for future therapeutic development.

Lack of Atorvastatin Effect on Monocyte Gene Expression and Inflammatory Markers in HIV-1-infected ART-suppressed Individuals at Risk of non-AIDS Comorbidities

BACKGROUND

Many people living with HIV have persistent monocyte activation despite viral suppression by antiretroviral therapy (ART), which contributes to non-AIDS complications including neurocognitive and other disorders. Statins have immunomodulatory properties that might be beneficial by reducing monocyte activation.

METHODS

We previously characterized monocyte gene expression and inflammatory markers in 11 HIV-positive individuals on long-term ART (HIV/ART) at risk for non-AIDS complications because of low nadir CD4+ counts (median 129 cells/uL) and elevated hsCRP. Here, these individuals participated in a double-blind, randomized, placebo-controlled crossover study of 12 weeks of atorvastatin treatment. Monocyte surface markers were assessed by flow cytometry, plasma mediators by ELISA and Luminex, and monocyte gene expression by microarray analysis.

RESULTS

Among primary outcome measures, 12 weeks of atorvastatin treatment led to an unexpected increase in CCR2+ monocytes (P=0.04), but did not affect CD16+ or CD163+ monocytes, nor levels in plasma of CCL2/MCP-1 or sCD14. Among secondary outcomes, atorvastatin treatment was associated with decreased plasma hsCRP (P=0.035) and IL-2R (P=0.012). Treatment was also associated with increased total CD14+ monocytes (P=0.015), and increased plasma CXCL9 (P=0.003) and IL-12 (P<0.001). Comparable results were seen in a subgroup that had inflammatory marker elevations at baseline. Atorvastatin treatment did not significantly alter monocyte gene expression or normalize aberrant baseline transcriptional patterns.

CONCLUSIONS

In this study of aviremic HIV+ individuals at high risk of non-AIDS events, 12 weeks of atorvastatin did not normalize monocyte gene expression patterns nor lead to significant changes in monocyte surface markers or plasma mediators linked to non-AIDS comorbidities.

Cannabis and Inflammation in HIV: A Review of Human and Animal Studies

Persistent inflammation occurs in people with HIV (PWH) and has many downstream adverse effects including myocardial infarction, neurocognitive impairment and death. Because the proportion of people with HIV who use cannabis is high and cannabis may be anti-inflammatory, it is important to characterize the impact of cannabis use on inflammation specifically in PWH. We performed a selective, non-exhaustive review of the literature on the effects of cannabis on inflammation in PWH. Research in this area suggests that cannabinoids are anti-inflammatory in the setting of HIV. Anti-inflammatory actions are mediated in many cases through effects on the endocannabinoid system (ECS) in the gut, and through stabilization of gut–blood barrier integrity. Cannabidiol may be particularly important as an anti-inflammatory cannabinoid. Cannabis may provide a beneficial intervention to reduce morbidity related to inflammation in PWH.

Insult to Injury-Potential Contribution of Coronavirus Disease-19 to Neuroinflammation and the Development of HIV-Associated Neurocognitive Disorders

Severe acute respiratory syndrome (SARS)-coronavirus (CoV)-2 is responsible for a new coronavirus disease known as coronavirus disease-19 (COVID-19). SARS-CoV-2 reports neurotropic properties and may have neurological implications, and this creates another health burden for people living with HIV. As yet, the impact of COVID-19 on (neuro)inflammation and the development of HIV-associated neurocognitive disorders (HAND) is not fully known. Here, we reviewed preliminary evidence that provides clues that COVID-19 may exacerbate inflammatory mechanisms related to the development of HAND.

Cerebrovascular Disease Correlates With Longitudinal Brain Atrophy in Virally Suppressed Older People Living With HIV

BACKGROUND

Mild cognitive difficulties and progressive brain atrophy are observed in older people living with HIV (PLWH) despite persistent viral suppression. Whether cerebrovascular disease (CVD) risk factors and white matter hyperintensity (WMH) volume correspond to the observed progressive brain atrophy is not well understood.

METHODS

Longitudinal structural brain atrophy rates and WMH volume were examined among 57 HIV-infected participants and 40 demographically similar HIV-uninfected controls over an average (SD) of 3.4 (1.7) years. We investigated associations between CVD burden (presence of diabetes, hypertension, hyperlipidemia, obesity, smoking history, and atrial fibrillation) and WMH with atrophy over time.

RESULTS

The mean (SD) age was 64.8 (4.3) years for PLWH and 66.4 (3.2) years for controls. Participants and controls were similar in age and sex (P > 0.05). PLWH were persistently suppressed (VL <375 copies/mL with 93% <75 copies/mL). The total number of CVD risk factors did not associate with atrophy rates in any regions of interests examined; however, body mass index independently associated with progressive atrophy in the right precentral gyrus (β = -0.30; P = 0.023), parietal lobe (β = -0.28; P = 0.030), and frontal lobe atrophy (β = -0.27; P = 0.026) of the HIV-infected group. No associations were found in the HIV-uninfected group. In both groups, baseline WMH was associated with progressive atrophy rates bilaterally in the parietal gray in the HIV-infected group (β = -0.30; P = 0.034) and the HIV-uninfected participants (β = -0.37; P = 0.033).

CONCLUSIONS

Body mass index and WMH are associated with atrophy in selective brain regions. However, CVD burden seems to partially contribute to progressive brain atrophy in older individuals regardless of HIV status, with similar effect sizes. Thus, CVD alone is unlikely to explain accelerated atrophy rates observed in virally suppressed PLWH. In older individuals, addressing modifiable CVD risk factors remains important to optimize brain health.

Amyloidogenic, neuroinflammatory and memory dysfunction effects of HIV-1 gp120

Human immunodeficiency virus 1 (HIV-1) infection can cause several HIV-associated neurocognitive disorders a variety of neurological impairments characterized by the loss of cortical and subcortical neurons and decreased cognitive and motor function. HIV-1 gp120, the major envelope glycoprotein on viral particles, acts as a binding protein for viral entry and is known to be an agent of neuronal cell death. To determine the mechanism of HIV-1 gp120-induced memory dysfunction, we performed mouse intracerebroventricular (i.c.v.) infusion with HIV-1 gp120 protein (300 ng per mouse) and investigated memory impairment and amyloidogenesis. Infusion of the HIV-1 gp120 protein induced memory dysfunction, which was evaluated using passive avoidance and water maze tests. Infusion of HIV-1 gp120 induced neuroinflammation, such as the release of iNOS and COX-2 and the activation of astrocytes and microglia and increased the mRNA and protein levels of IL-6, ICAM-1, M-CSF, TIM, and IL-2. In particular, we found that the infusion of HIV-1 gp120 induced the accumulation of amyloid plaques and signs of elevated amyloidogenesis, such as increased expression of amyloid precursor protein and BACE1 and increased β-secretase activity. Therefore, these studies suggest that HIV-1 gp120 may induce memory impairment through Aβ accumulation and neuroinflammation.

Improvement of HIV-associated neurocognitive disorders after antiretroviral therapy intensification: the Neuro+3 study

OBJECTIVES

Despite the effectiveness of antiretroviral (ARV) therapy to control HIV infection, HIV-associated neurocognitive disorders (HAND) remain frequent. The Neuro+3 study assessed the cognitive improvement associated with ARV intensification based on increased CNS penetration effectiveness (CPE) scoring ≥+3 and total CPE score ≥9.

METHODS

Thirty-one patients, aged 18-65 years, with confirmed diagnosis of HAND and effective ARV therapy were included. The cognitive improvement was measured using Frascati three-stage classification and global deficit score (GDS) after 48 and 96 weeks of ARV intensification. Ultrasensitive HIV-RNA, neopterin, soluble CD14, CCL2, CXCL10, IL6, IL8 and NF-L were measured in plasma and cerebrospinal fluid at Day 0 (baseline), Week 48 (W48) and W96.

RESULTS

The intensified ARV was associated with a median (IQR) CPE score increase from 6 (4-7) at baseline to 10 (9-11). From baseline to W96, the median (IQR) GDS decreased from 1.4 (0.8-2.2) to 1.0 (0.6-2.0) (P = 0.009); HAND classification improved from 2 to 1 HIV-associated dementia, 22 to 8 mild neurocognitive disorders, 7 to 17 asymptomatic neurocognitive impairment and 0 to 5 patients without any neurocognitive alterations (P = 0.001). In multivariable linear regression analysis, GDS improvement at W96 was significantly associated with CPE score ≥9 after intensification (P = 0.014), CD4 lymphocyte increase at W48 (P < 0.001) and plasma CXCL10 decrease at W96 (P = 0.001).

CONCLUSIONS

In patients with HAND, a significant cognitive improvement was observed after the ARV intensification strategy, with a higher CPE score. Cognitive improvement was more often observed in the case of a switch of two drug classes, arguing for better control of CNS HIV immune activation.

Daily Cannabis Use is Associated With Lower CNS Inflammation in People With HIV

OBJECTIVE

Recent cannabis exposure has been associated with lower rates of neurocognitive impairment in people with HIV (PWH). Cannabis's anti-inflammatory properties may underlie this relationship by reducing chronic neuroinflammation in PWH. This study examined relations between cannabis use and inflammatory biomarkers in cerebrospinal fluid (CSF) and plasma, and cognitive correlates of these biomarkers within a community-based sample of PWH.

METHODS

263 individuals were categorized into four groups: HIV- non-cannabis users (n = 65), HIV+ non-cannabis users (n = 105), HIV+ moderate cannabis users (n = 62), and HIV+ daily cannabis users (n = 31). Differences in pro-inflammatory biomarkers (IL-6, MCP-1/CCL2, IP-10/CXCL10, sCD14, sTNFR-II, TNF-α) by study group were determined by Kruskal-Wallis tests. Multivariable linear regressions examined relationships between biomarkers and seven cognitive domains, adjusting for age, sex/gender, race, education, and current CD4 count.

RESULTS

HIV+ daily cannabis users showed lower MCP-1 and IP-10 levels in CSF compared to HIV+ non-cannabis users (p = .015; p = .039) and were similar to HIV- non-cannabis users. Plasma biomarkers showed no differences by cannabis use. Among PWH, lower CSF MCP-1 and lower CSF IP-10 were associated with better learning performance (all ps < .05).

CONCLUSIONS

Current daily cannabis use was associated with lower levels of pro-inflammatory chemokines implicated in HIV pathogenesis and these chemokines were linked to the cognitive domain of learning which is commonly impaired in PWH. Cannabinoid-related reductions of MCP-1 and IP-10, if confirmed, suggest a role for medicinal cannabis in the mitigation of persistent inflammation and cognitive impacts of HIV.

Cerebrospinal fluid immune markers and HIV-associated neurocognitive impairments: A systematic review

HIV-1 is responsible for the development of a spectrum of cognitive impairments known as HIV-associated neurocognitive disorder (HAND). In the era of antiretroviral therapy (ART), HAND remains prevalent in people living with HIV (PLWH), despite low or undetectable viral loads. Persistent neuroinflammation likely plays an important role in the contributing biological mechanisms. Multiple cerebrospinal fluid (CSF) immune markers have been studied but it is unclear which markers most consistently correlate with neurocognitive impairment. We therefore conducted a systematic review of studies of the association of CSF immune markers with neurocognitive performance in ART-experienced PLWH. We aimed to synthesize the published data to determine consistent findings and to indicate the most noteworthy CSF markers of HAND. Twenty-nine studies were included, with 20 cross-sectional studies and 9 longitudinal studies. From the group of markers most often assayed, specific monocyte activation (higher levels of Neopterin, sCD163, sCD14) and neuroinflammatory markers (higher levels of IFN-γ, IL-1α, IL-7, IL-8, sTNFR-II and lower levels of IL-6) showed a consistent direction in association with HIV-associated neurocognitive impairment. Furthermore, significant differences exist in CSF immune markers between HIV-positive people with and without neurocognitive impairment, regardless of viral load and nadir/current CD4⁺ count. These markers may be useful in furthering our understanding of the neuropathology, diagnosis and prognosis of HAND. Studies using prospective designs (i.e. pre- and post-interventions), "multi-modal" methods (e.g. imaging, inflammation and neurocognitive evaluations) and utilizing a combination of the markers most commonly associated with HAND may help delineate the mechanisms of HAND.

Role of Brain Arterial Remodeling in HIV-Associated Cerebrovascular Outcomes

As the life expectancy of people living with HIV (PLWH) on combination antiretroviral therapy (cART) increases, so does morbidity from cerebrovascular disease and neurocognitive disorders. Brain arterial remodeling stands out as a novel investigational target to understand the role of HIV in cerebrovascular and neurocognitive outcomes. We therefore conducted a review of publications in PubMed, EMBASE, Web of Science and Wiley Online Library, from inception to April 2021. We included search terms such as HIV, cART, brain, neuroimmunity, arterial remodeling, cerebrovascular disease, and neurocognitive disorders. The literature shows that, in the post-cART era, PLWH continue to experience an increased risk of stroke and neurocognitive disorders (albeit milder forms) compared to uninfected populations. PLWH who are immunosuppressed have a higher proportion of hemorrhagic strokes and strokes caused by opportunistic infection and HIV vasculopathy, while PLWH on long-term cART have higher rates of ischemic strokes, compared to HIV-seronegative controls. Brain large artery atherosclerosis in PLWH is associated with lower CD4 nadir and higher CD4 count during the stroke event. HIV vasculopathy, a form of non-atherosclerotic outward remodeling, on the other hand, is associated with protracted immunosuppression. HIV vasculopathy was also linked to a thinner media layer and increased adventitial macrophages, suggestive of non-atherosclerotic degeneration of the brain arterial wall in the setting of chronic central nervous system inflammation. Cerebrovascular architecture seems to be differentially affected by HIV infection in successfully treated versus immunosuppressed PLWH. Brain large artery atherosclerosis is prevalent even with long-term immune reconstitution post-cART. HIV-associated changes in brain arterial walls may also relate to higher rates of HIV-associated neurocognitive disorders, although milder forms are more prevalent in the post-cART era. The underlying mechanisms of HIV-associated pathological arterial remodeling remain poorly understood, but a role has been proposed for chronic HIV-associated inflammation with increased burden on the vasculature. Neuroimaging may come to play a role in assessing brain arterial remodeling and stratifying cerebrovascular risk, but the data remains inconclusive. An improved understanding of the different phenotypes of brain arterial remodeling associated with HIV may reveal opportunities to reduce rates of cerebrovascular disease in the aging population of PLWH on cART.

Compartmentalization of cerebrospinal fluid inflammation across the spectrum of untreated HIV-1 infection, central nervous system injury and viral suppression

OBJECTIVE

To characterize the evolution of central nervous system (CNS) inflammation in HIV-1 infection applying a panel of cerebrospinal fluid (CSF) inflammatory biomarkers to grouped subjects representing a broad spectrum of systemic HIV-1 immune suppression, CNS injury and viral control.

METHODS

This is a cross-sectional analysis of archived CSF and blood samples, assessing concentrations of 10 functionally diverse soluble inflammatory biomarkers by immunoassays in 143 HIV-1-infected subjects divided into 8 groups: untreated primary HIV-1 infection (PHI); four untreated groups defined by their blood CD4+ T lymphocyte counts; untreated patients presenting with subacute HIV-associated dementia (HAD); antiretroviral-treated subjects with ≥1 years of plasma viral suppression; and untreated elite controllers. Twenty HIV-1-uninfected controls were included for comparison. Background biomarkers included blood CD4+ and CD8+ T lymphocytes, CSF and blood HIV-1 RNA, CSF white blood cell (WBC) count, CSF/blood albumin ratio, CSF neurofilament light chain (NfL), and CSF t-tau.

FINDINGS

HIV-1 infection was associated with a broad compartmentalized CSF inflammatory response that developed early in its course and changed with systemic disease progression, development of neurological injury, and viral suppression. CSF inflammation in untreated individuals without overt HAD exhibited at least two overall patterns of inflammation as blood CD4+ T lymphocytes decreased: one that peaked at 200-350 blood CD4+ T cells/μL and associated with lymphocytic CSF inflammation and HIV-1 RNA concentrations; and a second that steadily increased through the full range of CD4+ T cell decline and associated with macrophage responses and increasing CNS injury. Subacute HAD was distinguished by a third inflammatory profile with increased blood-brain barrier permeability and robust combined lymphocytic and macrophage CSF inflammation. Suppression of CSF and blood HIV-1 infections by antiretroviral treatment and elite viral control were associated with reduced CSF inflammation, though not fully to levels found in HIV-1 seronegative controls.

Plasma Cytokine Levels As Predictors of Global and Domain-Specific Human Immunodeficiency Virus-Associated Neurocognitive Impairment in Treatment-Naive Individuals

Central nervous system dysfunction, associated with human immunodeficiency virus (HIV) infection, remains a significant clinical concern, affecting at least 50% of infected people. Imbalances in cytokine expression levels have been linked to HIV-associated neurocognitive disorders. The aim of this study was to evaluate plasma cytokine levels as predictor neurocognitive impairment in HIV infection using a multiplex profiling kit. Stepwise regression model was used to identify cytokine biomarkers of overall and domain-specific cognitive performance. Higher interleukin (IL)-2 (β = 0.04; P = 0.001) and eotaxin (β = 0.01; P = 0.017) were predictors of global neurocognitive, whereas higher IL-5 (β = 0.005; P = 0.007) was negative predictor of global cognitive deficit. IL-2 was a negative predictor of most cognitive domain functions, including recall (β = 0.24; P = 0.005), recognition (β = 0.04; P = 0.026), mental control (β = 0.38; P = 0.005), symbol search (β = -0.55; P = 0.001), and digital symbol (β = -0.79; P = 0.019). IL-6 was associated with 3 impaired domains, mental processing (β = -0.468; P = 0.027), recognition (β = -0.044; P = 0.012), and learning (β = 0.02668; P = 0.020) These results show that plasma cytokines/chemokines may serve as markers of neurocognitive impairment in HIV infection.

Comparison of [11C]-PBR28 Binding Between Persons Living With HIV and HIV-Uninfected Individuals

OBJECTIVE

Despite combined antiretroviral therapy, neuroinflammation may persist in persons living with HIV (PLWH) and contribute to cognitive impairment in this population. Positron emission tomography (PET) imaging targeting 18 kDa translocator protein (TSPO) has been used to localize neuroinflammation. We aimed to use TSPO-PET imaging to evaluate neuroinflammation in PLWH.

DESIGN

Twenty-four virologically suppressed PLWH on combined antiretroviral therapy and 13 HIV-negative (HIV-) controls completed TSPO-PET imaging using the radiotracer [C]PBR28. Because of tracer complexity and differing procedures used in previous studies, we employed an expansive methodological approach, using binding potential (BP) and standard uptake value ratio and multiple different reference regions to estimate [C]PBR28 binding.

METHODS

[C]PBR28 binding was measured in 30 cortical and subcortical regions and compared between PLWH and HIV- controls. Pearson correlation evaluated the association between [C]PBR28 binding and cognition and clinical measures of HIV.

RESULTS

Analyses conducted using multiple reference regions and measures of tracer uptake revealed no significant differences between [C]PBR28 binding in PLWH compared with HIV- controls. In addition, [C]PBR28 binding in PLWH was not significantly associated with clinical measures of HIV or plasma biomarkers of inflammation. [C]PBR28 binding was not significantly elevated in cognitively impaired PLWH compared with unimpaired PLWH, but there were inverse relationships between cognitive performance (executive and global function) and [C]PBR28 binding in PLWH.

CONCLUSIONS

Our results suggest that neuroinflammation may play a role in cognitive deficits, but overall neuroinflammatory levels as measured by TSPO-PET imaging in PLWH are not significantly different from those seen in HIV- controls.

Central Nervous System (CNS) Viral Seeding by Mature Monocytes and Potential Therapies To Reduce CNS Viral Reservoirs in the cART Era

The human immunodeficiency virus (HIV) enters the central nervous system (CNS) within a few days after primary infection, establishing viral reservoirs that persist even with combined antiretroviral therapy (cART). We show that monocytes from people living with HIV (PLWH) on suppressive cART harboring integrated HIV, viral mRNA, and/or viral proteins preferentially transmigrate across the blood-brain barrier (BBB) to CCL2 and are significantly enriched post-transmigration, and even more highly enriched posttransmigration than T cells with similar properties. Using HIV-infected ART-treated mature monocytes cultured in vitro, we recapitulate these findings and demonstrate that HIV+ CD14+ CD16+ ART-treated monocytes also preferentially transmigrate. Cenicriviroc and anti-JAM-A and anti-ALCAM antibodies significantly and preferentially reduce/block transmigration of HIV+ CD14+ CD16+ ART-treated monocytes. These findings highlight the importance of monocytes in CNS HIV reservoirs and suggest targets to eliminate their formation and reseeding.IMPORTANCE We characterized mechanisms of CNS viral reservoir establishment/replenishment using peripheral blood mononuclear cells (PBMC) of PLWH on cART and propose therapeutic targets to reduce/block selective entry of cells harboring HIV (HIV+) into the CNS. Using DNA/RNAscope, we show that CD14+ CD16+ monocytes with integrated HIV, transcriptionally active, and/or with active viral replication from PBMC of PLWH prescribed cART and virally suppressed, selectively transmigrate across a human BBB model. This is the first study to our knowledge demonstrating that monocytes from PLWH with HIV disease for approximately 22 years and with long-term documented suppression can still carry virus into the CNS that has potential to be reactivated and infectious. This selective entry into the CNS-and likely other tissues-indicates a mechanism of reservoir formation/reseeding in the cART era. Using blocking studies, we propose CCR2, JAM-A, and ALCAM as targets on HIV+ CD14+ CD16+ monocytes to reduce and/or prevent CNS reservoir replenishment and to treat HAND and other HIV-associated comorbidities.

Treatment with buprenorphine prior to EcoHIV infection of mice prevents the development of neurocognitive impairment

Approximately 15-40% of people living with HIV develop HIV-associated neurocognitive disorders, HAND, despite successful antiretroviral therapy. There are no therapies to treat these disorders. HIV enters the CNS early after infection, in part by transmigration of infected monocytes. Currently, there is a major opioid epidemic in the United States. Opioid use disorder in the context of HIV infection is important because studies show that opioids exacerbate HIV-mediated neuroinflammation that may contribute to more severe cognitive deficits. Buprenorphine is an opioid derivate commonly prescribed for opiate agonist treatment. We used the EcoHIV mouse model to study the effects of buprenorphine on cognitive impairment and to correlate these with monocyte migration into the CNS. We show that buprenorphine treatment prior to mouse EcoHIV infection prevents the development of cognitive impairment, in part, by decreased accumulation of monocytes in the brain. We propose that buprenorphine has a novel therapeutic benefit of limiting the development of neurocognitive impairment in HIV-infected opioid abusers as well as in nonabusers, in addition to decreasing the use of harmful opioids. Buprenorphine may also be used in combination with HIV prevention strategies such as pre-exposure prophylaxis because of its safety profile.

Blue Monday: Co-occurring Stimulant Use and HIV Persistence Predict Dysregulated Catecholamine Synthesis

BACKGROUND

This longitudinal study examined whether co-occurring stimulant use and HIV disease processes predicted greater risk for depression via dysregulated metabolism of amino acid precursors for neurotransmitters.

METHODS

In total, 110 sexual minority men (ie, gay, bisexual, and other men who have sex with men) living with HIV who had biologically confirmed recent methamphetamine use were enrolled in a randomized controlled trial. The kynurenine/tryptophan (K/T) and phenylalanine/tyrosine (P/T) ratios were measured over 15 months to index dysregulated metabolism of amino acid precursors for serotonin and catecholamines. Markers of gut-immune dysregulation such as lipopolysaccharide binding protein and soluble CD14 (sCD14), HIV persistence in immune cells (ie, proviral HIV DNA), and stimulant use were examined as predictors. These bio-behavioral measures, including the K/T and P/T ratios, were also examined as predictors of greater risk for depression over 15 months.

RESULTS

Higher time-varying sCD14 levels (β = 0.13; P = 0.04) and time-varying detectable viral loads (β = 0.71; P < 0.001) were independent predictors of a higher K/T ratio. Time-varying reactive urine toxicology results for stimulants (β = 0.53; P < 0.001) and greater proviral HIV DNA at baseline (β = 0.34; P < 0.001) independently predicted an increased P/T ratio. Greater time-varying, self-reported methamphetamine use uniquely predicted higher odds of screening positive for depression (Adjusted Odds Ratio = 1.08; 95% confidence interval: 1.01 to 1.17).

CONCLUSIONS

Ongoing stimulant use and HIV persistence independently predict dysregulated metabolism of amino acid precursors for catecholamines, but this did not explain amplified risk for depression.

Chronic inflammation mediates brain injury in HIV infection: relevance for cure strategies

PURPOSE OF REVIEW

Chronic inflammation is a major component of HIV infection, the effects of which can be devastating in the central nervous system (CNS). Protecting the brain is, therefore, critical as efforts proceed to cure HIV infection by reactivating latent viral reservoirs and driving immune responses. We review the clinical presentation and pathology findings of inflammatory processes in the CNS in patients managed with ART and the drivers of these processes.

RECENT FINDINGS

Chronic inflammation is associated with increased mortality and morbidity and HIV infection increases the risk for chronic diseases, especially cognitive impairment. Latent viral reservoirs, including microglia and tissue macrophages, contribute to inflammation in the CNS. Inflammation is generated and maintained through residual viral replication, dysregulation of infected cells, continuously produced viral proteins and positive feedback loops of chronic inflammation. Novel therapeutics and lifestyle changes may help to protect the CNS from immune-mediated damage.

SUMMARY

As therapies are developed to cure HIV, it is important to protect the CNS from additional immune-mediated damage. Adjunctive therapies to restore glial function, reduce neuroinflammation and systemic inflammation, and inhibit expression of viral proteins are needed.

Targeting Cannabinoid Receptor 2 on Peripheral Leukocytes to Attenuate Inflammatory Mechanisms Implicated in HIV-Associated Neurocognitive Disorder

HIV infection affects an estimated 38 million people. Approximately 50% of HIV patients exhibit neurocognitive dysfunction termed HIV-Associated Neurocognitive Disorder (HAND). HAND is a consequence of chronic low-level neuroinflammation due to HIV entry into the brain. Initially, monocytes become activated in circulation and traffic to the brain. Monocytes, when activated, become susceptible to infection by HIV and can then carry the virus across the blood brain barrier. Once in the brain, activated monocytes secrete chemokines, which recruit virus-specific CD8+ T cells into the brain to further promote neuroinflammation. HAND is closely linked to systemic inflammation driven, in part, by HIV but is also due to persistent translocation of microorganisms across the GI tract. Persistent anti-viral responses in the GI tract compromise microbial barrier integrity. Indeed, HIV patients can exhibit remarkably high levels of activated (CD16+) monocytes in circulation. Recent studies, including our own, show that HIV patients using medical marijuana exhibit lower levels of circulating CD16+ monocytes than non-cannabis using HIV patients. Cannabis is a known immune modulator, including anti-inflammatory properties, mediated, in part, by ∆9-tetrahydrocannabinol (THC), as well as less characterized minor cannabinoids, such as cannabidiol (CBD), terpenes and presumably other cannabis constituents. The immune modulating activity of THC is largely mediated through cannabinoid receptors (CB) 1 and 2, with CB1 also responsible for the psychotropic properties of cannabis. Here we discuss the anti-inflammatory properties of cannabinoids in the context of HIV and propose CB2 as a putative therapeutic target for the treatment of neuroinflammation. Graphical Abstract HIV-associated neurocognitive disorder is a systemic inflammatory disease leading to activation of plasmacytoid dendritic cells, monocytes and T cells. Monocyte and CD8 T cell migration across the BBB and interaction with astrocytes promotes neurotoxic inflammatory mediators release. CB2 ligands are proposed as therapeutics capable of suppressing systemic and localized inflammation.