Mechanisms of neuroimmunity and neurodegeneration associated with HIV-1 infection and AIDS

Self-reported neurocognitive complaints in the Swiss HIV Cohort Study: a viral genome-wide association study

People with HIV may report neurocognitive complaints, with or without associated neurocognitive impairment, varying between individuals and populations. While the HIV genome could play a major role, large systematic viral genome-wide screens to date are lacking. The Swiss HIV Cohort Study biannually enquires neurocognitive complaints. We quantified broad-sense heritability estimates using partial 'pol' sequences from the Swiss HIV Cohort Study resistance database and performed a viral near full-length genome-wide association study for the longitudinal area under the curve of neurocognitive complaints. We performed all analysis (i) restricted to HIV Subtype B and (ii) including all HIV subtypes. From 8547 people with HIV with neurocognitive complaints, we obtained 6966 partial 'pol' sequences and 2334 near full-length HIV sequences. Broad-sense heritability estimates for presence of memory loss complaints ranged between 1% and 17% (Subtype B restricted 1-22%) and increased with the stringency of the phylogenetic distance thresholds. The genome-wide association study revealed one amino acid (Env L641E), after adjusting for multiple testing, positively associated with memory loss complaints (P = 4.3 * 10-6). Other identified mutations, while insignificant after adjusting for multiple testing, were reported in other smaller studies (Tat T64N, Env *291S). We present the first HIV genome-wide association study analysis of neurocognitive complaints and report a first estimate for the heritability of neurocognitive complaints through HIV. Moreover, we could identify one mutation significantly associated with the presence of memory loss complaints. Our findings indicate that neurocognitive complaints are polygenetic and highlight advantages of a whole genome approach for pathogenicity determination.

Non-Coding RNAs in HIV Infection, NeuroHIV, and Related Comorbidities

NeuroHIV affects approximately 30-60% of people living with HIV-1 (PLWH) and is characterized by varying degrees of cognitive impairments, presenting a multifaceted challenge, the underlying cause of which is chronic, low-level neuroinflammation. Such smoldering neuroinflammation is likely an outcome of lifelong reliance on antiretrovirals coupled with residual virus replication in the brains of PLWH. Despite advancements in antiretroviral therapeutics, our understanding of the molecular mechanism(s) driving inflammatory processes in the brain remains limited. Recent times have seen the emergence of non-coding RNAs (ncRNAs) as critical regulators of gene expression, underlying the neuroinflammatory processes in HIV infection, NeuroHIV, and their associated comorbidities. This review explores the role of various classes of ncRNAs and their regulatory functions implicated in HIV infection, neuropathogenesis, and related conditions. The dysregulated expression of ncRNAs is known to exacerbate the neuroinflammatory responses, thus contributing to neurocognitive impairments in PLWH. This review also discusses the diagnostic and therapeutic potential of ncRNAs in HIV infection and its comorbidities, suggesting their utility as non-invasive biomarkers and targets for modulating neuroinflammatory pathways. Understanding these regulatory roles could pave the way for novel diagnostic strategies and therapeutic interventions in the context of HIV and its comorbidities.

An exploratory investigation of the CSF metabolic profile of HIV in a South African paediatric cohort using GCxGC-TOF/MS

INTRODUCTION

 Because cerebrospinal fluid (CSF) samples are difficult to obtain for paediatric HIV, few studies have attempted to profile neurometabolic dysregulation.

AIM AND OBJECTIVE

The aim of this exploratory study was to profile the neurometabolic state of CSF from a South African paediatric cohort using GCxGC-TOF/MS. The study included 54 paediatric cases (< 12 years), 42 HIV-negative controls and 12 HIV-positive individuals.

RESULTS

The results revealed distinct metabolic alterations in the HIV-infected cohort. In the PLS-DA model, 18 metabolites significantly discriminated between HIV-infected and control groups. In addition, fold-change analysis, Mann-Whitney U tests, and effect size measurements verified these findings. Notably, lactose, myo-inositol, and glycerol, although not significant by p-value alone, demonstrated practical significance based on the effect size.

CONCLUSIONS

This study provided valuable insights on the impact of HIV on metabolic pathways, including damage to the gut and blood-brain barrier, disruption of bioenergetics processes, gliosis, and a potential marker for antiretroviral therapy. Nevertheless, the study recognized certain constraints, notably a limited sample size and the absence of a validation cohort. Despite these limitations, the rarity of the study's focus on paediatric HIV research underscores the significance and unique contributions of its findings.

Significant loss of retinal nerve fibre layer and contrast sensitivity in people with well controlled HIV disease: implications for aging with HIV

Objective

Antiretroviral therapy has decreased the prevalence of retinal opportunistic infections in people living with HIV (PLWH). However, abnormalities in visual function are evident and may be associated with an early onset of aging in PLWH. In this study, we examined the Retinal Nerve Fibre Layer (RNFL) thickness and visual function in PLWH and HIV non-infected controls in Malaysia.

Design

Cross-sectional study.

Methods

Two hundred and two (202) PLWH without retinal opportunistic infection and 182 age-matched, HIV seronegative individuals were enrolled. PLWH were recruited from the Infectious Disease clinic at the University Malaya Medical Centre. Controls were recruited among the hospital staff and community volunteers. RNFL thickness was measured with spectral domain optical coherence tomography (SDOCT). Visual functions include visual acuity using LogMAR chart and contrast sensitivity using Pelli- Robson Chart.

Results

All PLWH (mean age 46.1 years ± 9.9 years) in the study were on ART and 61.2% had a CD4+ T-cell count more than 500 cell/μl. The mean visual acuity was similar between the two groups (LogMAR 0.05 vs. 0.07, p = 0.115). Contrast sensitivity was lower in PLWH compared to HIV seronegative individuals (1.90 vs 1.93, p = 0.032). RNFL thickness was significantly thinner in the temporal quadrant for PLWH compared to controls (68.89 μm vs 74.08 μm, p = 0.001).

Conclusion

Changes in RNFL thickness and contrast sensitivity were seen in PLWH despite their relatively young age and well controlled HIV disease. The changes reflect structural and functional deficits, and could have long-term implications on their health trajectory.

The Neuroimmune System and the Cerebellum

The recognition that there is an innate immune system of the brain, referred to as the neuroimmune system, that preforms many functions comparable to that of the peripheral immune system is a relatively new concept and much is yet to be learned. The main cellular components of the neuroimmune system are the glial cells of the brain, primarily microglia and astrocytes. These cell types preform many functions through secretion of signaling factors initially known as immune factors but referred to as neuroimmune factors when produced by cells of the brain. The immune functions of glial cells play critical roles in the healthy brain to maintain homeostasis that is essential for normal brain function, to establish cytoarchitecture of the brain during development, and, in pathological conditions, to minimize the detrimental effects of disease and injury and promote repair of brain structure and function. However, dysregulation of this system can occur resulting in actions that exacerbate or perpetuate the detrimental effects of disease or injury. The neuroimmune system extends throughout all brain regions, but attention to the cerebellar system has lagged that of other brain regions and information is limited on this topic. This article is meant to provide a brief introduction to the cellular and molecular components of the brain immune system, its functions, and what is known about its role in the cerebellum. The majority of this information comes from studies of animal models and pathological conditions, where upregulation of the system facilitates investigation of its actions.

Low levels of peripheral blood activated and senescent T cells characterize people with HIV-1-associated neurocognitive disorders

Background

HIV infection induces a 75% increase in the risk of developing neurocognitive impairment (NCI), which has been linked to immune activation. We therefore looked for immune activation markers correlating with NCI.

Method

Sixty-five people aged 55-70 years living with controlled HIV-1 infection were enrolled in the study and their neurocognitive ability was assessed according to the Frascati criteria. Fifty-nine markers of T4 cell, T8 cell, NK cell, and monocyte activation, inflammation and endothelial activation were measured in their peripheral blood. White matter hyperintensities (WMH) were identified by magnetic resonance imaging. Double hierarchical clustering was performed for the activation markers and 240 patients including the 65 whose neurocognitive performance had been evaluated.

Results

Thirty-eight percent of volunteers presented NCI. Twenty-four percent of them were asymptomatic and fourteen percent had a mild disorder. Strikingly, activated (HLA-DR+) as well as senescent (CD57+CD28-CD27±) T4 cells and T8 cells were less prevalent in the peripheral blood of participants with NCI than in participants without the disorder. Accordingly, the percentage of HLA-DR+ T4 cells was lower in volunteers with periventricular and deep WMH. The double hierarchical clustering unveiled six different immune activation profiles. The neurocognitive performances of participants with two of these six profiles were poor. Here again, these two profiles were characterized by a low level of T4 and T8 cell activation and senescence.

Conclusion

Our observation of low circulating levels of activated and senescent T cells in HIV-1 patients with NCI raises the interesting hypothesis that these lymphocytes may be recruited into the central nervous system.

HIV-Associated Insults Modulate ADAM10 and Its Regulator Sirtuin1 in an NMDA Receptor-Dependent Manner

Neurologic deficits associated with human immunodeficiency virus (HIV) infection impact about 50% of persons with HIV (PWH). These disorders, termed HIV-associated neurocognitive disorders (HAND), possess neuropathologic similarities to Alzheimer’s disease (AD), including intra- and extracellular amyloid-beta (Aβ) peptide aggregates. Aβ peptide is produced through cleavage of the amyloid precursor protein (APP) by the beta secretase BACE1. However, this is precluded by cleavage of APP by the non-amyloidogenic alpha secretase, ADAM10. Previous studies have found that BACE1 expression was increased in the CNS of PWH with HAND as well as animal models of HAND. Further, BACE1 contributed to neurotoxicity. Yet in in vitro models, the role of ADAM10 and its potential regulatory mechanisms had not been examined. To address this, primary rat cortical neurons were treated with supernatants from HIV-infected human macrophages (HIV/MDMs). We found that HIV/MDMs decreased levels of both ADAM10 and Sirtuin1 (SIRT1), a regulator of ADAM10 that is implicated in aging and in AD. Both decreases were blocked with NMDA receptor antagonists, and treatment with NMDA was sufficient to induce reduction in ADAM10 and SIRT1 protein levels. Furthermore, decreases in SIRT1 protein levels were observed at an earlier time point than the decreases in ADAM10 protein levels, and the reduction in SIRT1 was reversed by proteasome inhibitor MG132. This study indicates that HIV-associated insults, particularly excitotoxicity, contribute to changes of APP secretases by downregulating levels of ADAM10 and its regulator.

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.

HIV Infection and Related Mental Disorders

Over the more than thirty-year period of the human immunodeficiency virus type 1 (HIV-1) epidemic, many data have been accumulated indicating that HIV infection predisposes one to the development of mental pathologies. It has been proven that cognitive disorders in HIV-positive individuals are the result of the direct exposure of the virus to central nervous system (CNS) cells. The use of antiretroviral therapy has significantly reduced the number of cases of mental disorders among people infected with HIV. However, the incidence of moderate to mild cognitive impairment at all stages of HIV infection is still quite high. This review describes the most common forms of mental pathology that occur in people living with HIV and presents the current concepts on the possible pathogenetic mechanisms of the influence of human immunodeficiency virus (HIV-1) and its viral proteins on the cells of the CNS and the CNS’s functions. This review also provides the current state of knowledge on the impact of the antiretroviral therapy on the development of mental pathologies in people living with HIV, as well as current knowledge on the interactions between antiretroviral and psychotropic drugs that occur under their simultaneous administration.

Modeling HIV-1 neuropathogenesis using three-dimensional human brain organoids (hBORGs) with HIV-1 infected microglia

HIV-1 associated neurocognitive disorder (HAND) is characterized by neuroinflammation and glial activation that, together with the release of viral proteins, trigger a pathogenic cascade resulting in synaptodendritic damage and neurodegeneration that lead to cognitive impairment. However, the molecular events underlying HIV neuropathogenesis remain elusive, mainly due to lack of brain-representative experimental systems to study HIV-CNS pathology. To fill this gap, we developed a three-dimensional (3D) human brain organoid (hBORG) model containing major cell types important for HIV-1 neuropathogenesis; neurons and astrocytes along with incorporation of HIV-infected microglia. Both infected and uninfected microglia infiltrated into hBORGs resulting in a triculture system (MG-hBORG) that mirrors the multicellular network observed in HIV-infected human brain. Moreover, the MG-hBORG model supported productive viral infection and exhibited increased inflammatory response by HIV-infected MG-hBORGs, releasing tumor necrosis factor (TNF-α) and interleukin-1 (IL-1β) and thereby mimicking the chronic neuroinflammatory environment observed in HIV-infected individuals. This model offers great promise for basic understanding of how HIV-1 infection alters the CNS compartment and induces pathological changes, paving the way for discovery of biomarkers and new therapeutic targets.

Mental health and HIV/AIDS: the need for an integrated response

Tremendous biomedical advancements in HIV prevention and treatment have led to aspirational efforts to end the HIV epidemic. However, this goal will not be achieved without addressing the significant mental health and substance use problems among people living with HIV (PLWH) and people vulnerable to acquiring HIV. These problems exacerbate the many social and economic barriers to accessing adequate and sustained healthcare, and are among the most challenging barriers to achieving the end of the HIV epidemic. Rates of mental health problems are higher among both people vulnerable to acquiring HIV and PLWH, compared with the general population. Mental health impairments increase risk for HIV acquisition and for negative health outcomes among PLWH at each step in the HIV care continuum. We have the necessary screening tools and efficacious treatments to treat mental health problems among people living with and at risk for HIV. However, we need to prioritize mental health treatment with appropriate resources to address the current mental health screening and treatment gaps. Integration of mental health screening and care into all HIV testing and treatment settings would not only strengthen HIV prevention and care outcomes, but it would additionally improve global access to mental healthcare.

Neurocognitive dysfunction in HIV-infected youth: investigating the relationship with immune activation

BACKGROUND

HIV-infected individuals are at increased risk of neurocognitive impairment compared to the general population. Studies suggest that, despite combination antiretroviral therapy (cART), HIV infection causes immune activation which results in neural damage; however, few data exist in HIV-infected youth.

METHODS

HIV-infected youth 8-26-years-old on cART with virological suppression were prospectively enrolled along with healthy controls. Neurocognitive performance was assessed by age-appropriate Wechsler Intelligence Scales. Soluble and cellular markers of T-lymphocyte and monocyte activation were measured by ELISA and flow cytometry, respectively.

RESULTS

45 HIV-infected subjects and 21 controls were enrolled. Markers of T-cell and monocyte activation were higher in the HIV-infected subjects compared to controls, but proportions of inflammatory and patrolling monocytes were similar. Although there were no significant differences in neurocognitive scores between the HIV-infected and control groups, scores were low-average for four of five testing domains for the HIV-infected subjects and average for all five in the controls, and % of HIV-infected subjects with scores classified as 'low average' or below was higher than in the controls. Variables most associated with neurocognitive performance among HIV-infected subjects included activated CD4⁺ T-cells (% CD4+CD38+HLA-DR), monocyte activation (soluble CD14), HIV duration, age and sex.

CONCLUSIONS

HIV-infected youth on cART with virological suppression show subtle evidence of neurocognitive impairment compared to healthy controls, and increased immune activation appears to play a role. Additional studies are needed to develop strategic interventions beyond cART to potentially improve neurocognitive performance and/or minimize further impairment in this vulnerable population. ClinicalTrials.gov Identifier: NCT01523496.

Association between Sex, CD4 Cell Counts, Antiretroviral Medications, and Olfactory and Gustatory Functions of HIV-Infected Adults

Objective To investigate the olfactory and gustatory functions of human immunodeficiency virus (HIV)-infected adults in Ibadan, Nigeria. Study Design A cross-sectional study of olfactory and gustatory functions of HIV-infected adults between March 2015 and December 2015. Setting Tertiary health institution. Subjects and Methods A structured questionnaire was administered to participants to obtain relevant sociodemographic and clinical information. Participants' nadir and most recent CD4 cell count and viral loads were obtained from their medical records. Participants' body mass indices were determined, and each subjectively rated their olfactory and gustatory performances. Objective olfactory and gustatory functions were determined using validated "Sniffin' Sticks" and "Taste Strips" impregnated with 4 different concentrations of sucrose, quinine hydrochloride, sodium chloride, and citric acid. Results In total, 135 HIV-infected adults, comprising 41 (30.4%) men and 94 (69.6%) women, were evaluated. Their ages ranged from 20 to 70 years, mean 43.4 ± 10.4 years. Participants were on highly active antiretroviral therapy for a mean duration of 75.8 ± 36.9 months. The proportions of male participants in HIV stages 1, 2, and 3 were 18 (43.9%), 19 (46.3%), and 4 (9.8%), respectively, while female participants were 46 (48.9%), 41 (43.6%), and 7 (7.4%), respectively. Participants' mean olfactory threshold, discrimination, identification, and TDI scores were 8.0 ± 4.9, 9.9 ± 4.7, 8.8 ± 4.5, and 26.7 ± 11.1, respectively, while total taste score was 25.1 ± 5.7. Conclusion HIV-infected adults have tendency to develop hyposmia and hypogeusia. These are worse with advanced stage of HIV infection.

Differential Effects of Antiretroviral Drugs on Neurons In Vitro: Roles for Oxidative Stress and Integrated Stress Response

Mounting evidence suggests that antiretroviral drugs may contribute to the persistence of HIV-associated neurocognitive disorders (HAND), which impact 30%-50% of HIV-infected patients in the post-antiretroviral era. We previously reported that two first generation HIV protease inhibitors, ritonavir and saquinavir, induced oxidative stress, with subsequent neuronal death in vitro, which was reversed by augmentation of the endogenous antioxidant response by monomethyl fumarate. We herein determined whether two newer-generation PIs, darunavir and lopinavir, were deleterious to neurons in vitro. Further, we expanded our assessment to include three integrase strand transfer inhibitors, raltegravir, dolutegravir, and elvitegravir. We found that only lopinavir and elvitegravir were neurotoxic to primary rat neuroglial cultures as determined by the loss of microtubule-associated protein 2 (MAP2). Intriguingly, lopinavir but not elvitegravir led to oxidative stress and induced the endogenous antioxidant response (EAR). Furthermore, neurotoxicity of lopinavir was blocked by pharmacological augmentation of the endogenous antioxidant heme oxygenase-1 (HO-1), expanding our previous finding that protease inhibitor-induced neurotoxicity was mediated by oxidative stress. Conversely, elvitegravir but not lopinavir led to increased eIF2α phosphorylation, indicating the activation of a common adaptive pathway termed the integrated stress response (ISR), and elvitegravir-mediated neurotoxicity was partially alleviated by the ISR inhibitor trans-ISRIB, suggesting ISR as a promoter of elvitegravir-associated neurotoxicity. Overall, we found that neurotoxicity was induced only by a subset of protease inhibitors and integrase strand transfer inhibitors, providing evidence for class- and drug-specific neurotoxic effects of antiretroviral drugs. Future in vivo studies will be critical to confirm the neurotoxicity profiles of these drugs for incorporation of these findings into patient management. The EAR and ISR pathways are potential access points for the development of adjunctive therapies to complement antiretroviral therapies and limit their contribution to HAND persistence.

Insulin Treatment Prevents Neuroinflammation and Neuronal Injury with Restored Neurobehavioral Function in Models of HIV/AIDS Neurodegeneration

HIV-1 infection of the brain causes the neurodegenerative syndrome HIV-associated neurocognitive disorders (HAND), for which there is no specific treatment. Herein, we investigated the actions of insulin using ex vivo and in vivo models of HAND. Increased neuroinflammatory gene expression was observed in brains from patients with HIV/AIDS. The insulin receptor was detected on both neurons and glia, but its expression was unaffected by HIV-1 infection. Insulin treatment of HIV-infected primary human microglia suppressed supernatant HIV-1 p24 levels, reduced CXCL10 and IL-6 transcript levels, and induced peroxisome proliferator-activated receptor gamma (PPAR-γ) expression. Insulin treatment of primary human neurons prevented HIV-1 Vpr-mediated cell process retraction and death. In feline immunodeficiency virus (FIV) infected cats, daily intranasal insulin treatment (20.0 IU/200 μl for 6 weeks) reduced CXCL10, IL-6, and FIV RNA detection in brain, although PPAR-γ in glia was increased compared with PBS-treated FIV⁺ control animals. These molecular changes were accompanied by diminished glial activation in cerebral cortex and white matter of insulin-treated FIV⁺ animals, with associated preservation of cortical neurons. Neuronal counts in parietal cortex, striatum, and hippocampus were higher in the FIV⁺/insulin-treated group compared with the FIV⁺/PBS-treated group. Moreover, intranasal insulin treatment improved neurobehavioral performance, including both memory and motor functions, in FIV⁺ animals. Therefore, insulin exerted ex vivo and in vivo antiviral, anti-inflammatory, and neuroprotective effects in models of HAND, representing a new therapeutic option for patients with inflammatory or infectious neurodegenerative disorders including HAND.

SIGNIFICANCE STATEMENT

HIV-associated neurocognitive disorders (HAND) represent a spectrum disorder of neurocognitive dysfunctions resulting from HIV-1 infection. Although the exact mechanisms causing HAND are unknown, productive HIV-1 infection in the brain with associated neuroinflammation is a potential pathogenic mechanism resulting in neuronal damage and death. We report that, in HIV-infected microglia cultures, insulin treatment led to reduced viral replication and inflammatory gene expression. In addition, intranasal insulin treatment of experimentally feline immunodeficiency virus-infected animals resulted in improved motor and memory performances. We show that insulin restored expression of the nuclear receptor peroxisome proliferator-activated receptor gamma (PPAR-γ), which is suppressed by HIV-1 replication. Our findings indicate a unique function for insulin in improving neurological outcomes in lentiviral infections, implicating insulin as a therapeutic intervention for HAND.

Topographies of Cortical and Subcortical Volume Loss in HIV and Aging in the cART Era

OBJECTIVES

Studies of HIV-associated brain atrophy often focus on a priori brain regions of interest, which can introduce bias. A data-driven, minimally biased approach was used to analyze changes in brain volumetrics associated with HIV and their relationship to aging, viral factors, combination antiretroviral therapy (cART), and gender, and smoking.

DESIGN

A cross-sectional study of 51 HIV-uninfected (HIV-) and 146 HIV-infected (HIV+) participants.

METHODS

Structural MRI of participants was analyzed using principal component analysis (PCA) to reduce dimensionality and determine topographies of volumetric changes. Neuropsychological (NP) assessment was examined using global and domain-specific scores. The effects of HIV disease factors (eg, viral load, CD4, etc.) on brain volumes and neuropsychological were investigated using penalized regression (LASSO).

RESULTS

Two components of interest were visualized using principal component analysis. An aging effect predominated for both components. The first component, a cortically weighted topography, accounted for a majority of variance across participants (43.5% of variance) and showed independent effects of HIV and smoking. A secondary, subcortically weighted topography (4.6%) showed HIV-status accentuated age-related volume loss. In HIV+ patients, the cortical topography correlated with global neuropsychological scores and nadir CD4, whereas subcortical volume loss was associated with recent viral load.

CONCLUSIONS

Cortical regions showed the most prominent volumetric changes because of aging and HIV. Within HIV+ participants, cortical volumes were associated with immune history, whereas subcortical changes correlated with current immune function. Cognitive function was primarily associated with cortical volume changes. Observed volumetric changes in chronic HIV+ patients may reflect both past infection history and current viral status.

Methamphetamine potentiates HIV-1gp120-induced microglial neurotoxic activity by enhancing microglial outward K+ current

Methamphetamine (Meth) abuse not only increases the risk of human immunodeficiency virus-1 (HIV-1) infection, but exacerbates HIV-1-associated neurocognitive disorders (HAND) as well. The mechanisms underlying the co-morbid effect are not fully understood. Meth and HIV-1 each alone interacts with microglia and microglia express voltage-gated potassium (K_V) channel K_V1.3. To understand whether K_V1.3 functions an intersecting point for Meth and HIV-1, we studied the augment effect of Meth on HIV-1 glycoprotein 120 (gp120)-induced neurotoxic activity in cultured rat microglial cells. While Meth and gp120 each alone at low (subtoxic) concentrations failed to trigger microglial neurotoxic activity, Meth potentiated gp120-induced microglial neurotoxicity when applied in combination. Meth enhances gp120 effect on microglia by enhancing microglial K_V1.3 protein expression and K_V1.3 current, leading to an increase of neurotoxin production and resultant neuronal injury. Pretreatment of microglia with a specific K_V1.3 antagonist 5-(4-Phenoxybutoxy)psoralen (PAP) or a broad spectrum K_V channel blocker 4-aminopyridine (4-AP) significantly attenuated Meth/gp120-treated microglial production of neurotoxins and resultant neuronal injury, indicating an involvement of K_V1.3 in Meth/gp120-induced microglial neurotoxic activity. Meth/gp120 activated caspase-3 and increased caspase-3/7 activity in microglia and inhibition of caspase-3 by its specific inhibitor significantly decreased microglial production of TNF-α and iNOS and attenuated microglia-associated neurotoxic activity. Moreover, blockage of K_V1.3 by specific blockers attenuated Meth/gp120 enhancement of caspase-3/7 activity. Taking together, these results suggest an involvement of microglial K_V1.3 in the mediation of Meth/gp120 co-morbid effect on microglial neurotoxic activity via caspase-3 signaling.

Loss of cerebellar neurons in the progression of lentiviral disease: effects of CNS-permeant antiretroviral therapy

BACKGROUND

The majority of investigations on HIV-associated neurocognitive disorders (HAND) neglect the cerebellum in spite of emerging evidence for its role in higher cognitive functions and dysfunctions in common neurodegenerative diseases.

METHODS

We systematically investigated the molecular and cellular responses of the cerebellum as contributors to lentiviral infection-induced neurodegeneration, in the simian immunodeficiency virus (SIV)-infected rhesus macaque model for HIV infection and HAND. Four cohorts of animals were studied: non-infected controls, SIV-infected asymptomatic animals, and SIV-infected AIDS-diseased animals with and without brain-permeant antiretroviral treatment. The antiretroviral utilized was 6-chloro-2',3'-dideoxyguanosine (6-Cl-ddG), a CNS-permeable nucleoside reverse transcriptase inhibitor. Quantitation of granule cells and Purkinje cells, of an established biomarker of SIV infection (gp41), of microglial/monocyte/macrophage markers (IBA-1, CD68, CD163), and of the astroglial marker (GFAP) were used to reveal cell-specific cerebellar responses to lentiviral infection and antiretroviral therapy (ART). The macromolecular integrity of the blood brain barrier was tested by albumin immunohistochemistry.

RESULTS

Productive CNS infection was observed in the symptomatic stage of disease, and correlated with extensive microglial/macrophage and astrocyte activation, and widespread macromolecular blood brain barrier defects. Signs of productive infection, and inflammation, were reversed upon treatment with 6-Cl-ddG, except for a residual low-grade activation of microglial cells and astrocytes. There was an extensive loss of granule cells in the SIV-infected asymptomatic cohort, which was further increased in the symptomatic stage of the disease and persisted after 6-Cl-ddG (administered after the onset of symptoms of AIDS). In the symptomatic stage, Purkinje cell density was reduced. Purkinje cell loss was likewise unaffected by 6-Cl-ddG treatment at this time.

CONCLUSIONS

Our findings suggest that neurodegenerative mechanisms are triggered by SIV infection early in the disease process, i. e., preceding large-scale cerebellar productive infection and marked neuroinflammation. These affect primarily granule cells early in disease, with later involvement of Purkinje cells, indicating differential vulnerability of the two neuronal populations. The results presented here indicate a role for the cerebellum in neuro-AIDS. They also support the conclusion that, in order to attenuate the development of motor and cognitive dysfunctions in HIV-positive individuals, CNS-permeant antiretroviral therapy combined with anti-inflammatory and neuroprotective treatment is indicated even before overt signs of CNS inflammation occur.

No support for premature central nervous system aging in HIV-1 when measured by cerebrospinal fluid phosphorylated tau (p-tau)

BACKGROUND

The prevalence of neurocognitive deficits are reported to be high in HIV-1 positive patients, even with suppressive antiretroviral treatment, and it has been suggested that HIV can cause accelerated aging of the brain. In this study we measured phosphorylated tau (p-tau) in cerebrospinal fluid (CSF) as a potential marker for premature central nervous system (CNS) aging. P-tau increases with normal aging but is not affected by HIV-associated neurocognitive disorders.

METHODS

With a cross-sectional retrospective design, p-tau, total tau (t-tau), neopterin and HIV-RNA were measured in CSF together with plasma HIV-RNA and blood CD4⁺ T-cells of 225 HIV-infected patients <50 y of age, subdivided into 3 groups: untreated neuroasymptomatic (NA) (n = 145), on suppressive antiretroviral treatment (cART) (n = 49), and HIV-associated dementia (HAD) (n = 31). HIV-negative healthy subjects served as controls (n = 79).

RESULTS

P-tau was not significantly higher in any HIV-infected group compared to HIV-negative controls. Significant increases in t-tau were found as expected in patients with HAD compared to NA, cART, and control groups (p < 0.001 ).

CONCLUSIONS

P-tau was not higher in HIV-infected patients compared to uninfected controls, thus failing to support a role for premature or accelerated brain aging in HIV infection.

Neurometabolite Alterations Associated With Cognitive Performance in Perinatally HIV-Infected Children

Despite treatment with combination antiretroviral therapy (cART), cognitive impairment is still observed in perinatally HIV-infected children. We aimed to evaluate potential underlying cerebral injury by comparing neurometabolite levels between perinatally HIV-infected children and healthy controls. This cross-sectional study evaluated neurometabolites, as measured by Magnetic Resonance Spectroscopy (MRS), in perinatally HIV-infected children stable on cART (n = 26) and healthy controls (n = 36).Participants were included from a cohort of perinatally HIV-infected children and healthy controls, matched group-wise for age, gender, ethnicity, and socio-economic status. N-acetylaspartate (NAA), glutamate (Glu), myo-inositol (mI), and choline (Cho) levels were studied as ratios over creatine (Cre). Group differences and associations with HIV-related parameters, cognitive functioning, and neuronal damage markers (neurofilament and total Tau proteins) were determined using age-adjusted linear regression analyses.HIV-infected children had increased Cho:Cre in white matter (HIV-infected = 0.29 ± 0.03; controls = 0.27 ± 0.03; P value = 0.045). Lower nadir CD4+ T-cell Z-scores were associated with reduced neuronal integrity markers NAA:Cre and Glu:Cre. A Centers for Disease Control and Prevention (CDC) stage C diagnosis was associated with higher glial markers Cho:Cre and mI:Cre. Poorer cognitive performance was mainly associated with higher Cho:Cre in HIV-infected children, and with lower NAA:Cre and Glu:Cre in healthy controls. There were no associations between neurometabolites and neuronal damage markers in blood or CSF.Compared to controls, perinatally HIV-infected children had increased Cho:Cre in white matter, suggestive of ongoing glial proliferation. Levels of several neurometabolites were associated with cognitive performance, suggesting that MRS may be a useful method to assess cerebral changes potentially linked to cognitive outcomes.

Potent in vitro antiviral activity of Cistus incanus extract against HIV and Filoviruses targets viral envelope proteins

Novel therapeutic options are urgently needed to improve global treatment of virus infections. Herbal products with confirmed clinical safety features are attractive starting material for the identification of new antiviral activities. Here we demonstrate that Cistus incanus (Ci) herbal products inhibit human immunodeficiency virus (HIV) infections in vitro. Ci extract inhibited clinical HIV-1 and HIV-2 isolates, and, importantly, a virus isolate with multiple drug resistances, confirming broad anti-HIV activity. Antiviral activity was highly selective for virus particles, preventing primary attachment of the virus to the cell surface and viral envelope proteins from binding to heparin. Bioassay-guided fractionation indicated that Ci extract contains numerous antiviral compounds and therefore has favorably low propensity to induce virus resistance. Indeed, no resistant viruses emerged during 24 weeks of continuous propagation of the virus in the presence of Ci extracts. Finally, Ci extracts also inhibited infection by virus particles pseudotyped with Ebola and Marburg virus envelope proteins, indicating that antiviral activity of Ci extract extends to emerging viral pathogens. These results demonstrate that Ci extracts show potent and broad in vitro antiviral activity against viruses that cause life-threatening diseases in humans and are promising sources of agents that target virus particles.

Natural Products as Anti-HIV Agents and Role in HIV-Associated Neurocognitive Disorders (HAND): A Brief Overview

As the threat of Human Immunodeficiency Virus (HIV)/Acquired Immunodeficiency Syndrome (AIDS) persists to rise, effective drug treatments are required to treat the infected people. Even though combination antiretroviral therapy (cART) provides stable viral suppression, it is not devoid of undesirable side effects, especially in persons undergoing long-term treatment. The present therapy finds its limitations in the emergence of multidrug resistance and accordingly finding new drugs and novel targets is the need of the hour to treat the infected persons and further to attack HIV reservoirs in the body like brain, lymph nodes to achieve the ultimate goal of complete eradication of HIV and AIDS. Natural products such as plant-originated compounds and plant extracts have enormous potential to become drug leads with anti-HIV and neuroprotective activity. Accordingly, many research groups are exploring the biodiversity of the plant kingdom to find new and better anti-HIV drugs with novel mechanisms of action and for HIV-associated neurocognitive disorders (HAND). The basic challenge that still persists is to develop viral replication-targeted therapy using novel anti-HIV compounds with new mode of action, accepted toxicity and less resistance profile. Against this backdrop, the World Health Organization (WHO) suggested the need to evaluate ethno-medicines for the management of HIV/AIDS. Consequently, there is need to evaluate traditional medicine, particularly medicinal plants and other natural products that may yield effective and affordable therapeutic agents. Although there are a good number of reports on traditional uses of plants to treat various diseases, knowledge of herbal remedies used to manage HIV/AIDS and HAND are scanty, vague and not well documented. In this review, plant substances showing a promising action that is anti-HIV and HAND will be explored along with what they interact. Since some plant substances are also known to modulate several cellular factors which are also involved in the replication of HIV and hence their role as potential candidates will be discussed. HIV/AIDS being an exceptional epidemic, demands an exceptional approach and that forms very much focus for the current review.

HIV-1 Tat-induced changes in synaptically-driven network activity adapt during prolonged exposure

HIV-associated neurocognitive disorders (HAND) afflict approximately half of HIV-infected patients. The HIV-1 transactivator of transcription (Tat) protein is released by infected cells and contributes to the pathogenesis of HAND, but many of the underlying mechanisms remain poorly understood. Here we used fura-2-based Ca(2+) imaging and whole-cell patch-clamp recording to study the effects of Tat on the spontaneous synaptic activity that occurs in networked rat hippocampal neurons in culture. Tat triggered aberrant network activity that exhibited a decrease in the frequency of spontaneous action potential bursts and Ca(2+) spikes with a simultaneous increase in burst duration and Ca(2+) spike amplitude. These network changes were apparent after 4 h treatment with Tat and required the low-density lipoprotein receptor-related protein (LRP). Interestingly, Tat-induced changes in network activity adapted during 24 h exposure. The activity returned to control levels in the maintained presence of Tat for 24 h. These observations indicate that Tat causes aberrant network activity, which is dependent on LRP, and adapts following prolonged exposure. Changes in network excitability may contribute to Tat-induced neurotoxicity in vitro and seizure disorders in vivo. Adaptation of neural networks may be a neuroprotective response to the sustained presence of the neurotoxic protein Tat and could underlie the behavioral and electrophysiological changes observed in HAND.

Increased CD38 expression on T lymphocytes as a marker of HIV dissemination into the central nervous system

Cross-sectional analysis on 20 HIV-1 patients with neurological symptoms admitted to two infectious disease units. Cut-off of HIV-RNA (VL) was 20 copies/ml for plasma and cerebral spinal fluid (CSF). Flow cytometry was used to analyze the phenotype of circulating and CSF T lymphocytes. CD38 mean fluorescence intensity (MFI) was higher on circulating CD4+T lymphocytes from patients with VL>20 copies/ml in plasma (P=0.001) or CSF (P=0.001). The frequency of circulating CD8+CD38+T cells and CD38 MFI on these cells were higher in patients with VL>20 copies/ml than in those with undetectable plasma VL (P=0.030 and P=0.023). The frequency of CSF CD4+CD38+T, as well as their CD38 and CD95 MFI, were increased in patients with detectable than non-detectable plasma VL (P=0.01, P=0.03, and P=0.05). The % CD38+CD8+T in CSF correlated with time of virological suppression (ρ=-0.462, P=0.040) and the CNS penetration-effectiveness (CPE) score (ρ=-0.467, P=0.038). In conclusion, (a) the expression of CD38+ on both CD4+, CD8+T lymphocytes from peripheral blood and CSF discriminated between viremic and non-viremic patients and (b) T cell activation/apoptosis markers inversely correlated with CPE to remark the importance for therapy to restore immunological functions.

The dual action of poly(ADP-ribose) polymerase -1 (PARP-1) inhibition in HIV-1 infection: HIV-1 LTR inhibition and diminution in Rho GTPase activity

Multifactorial mechanisms comprising countless cellular factors and virus-encoded transactivators regulate the transcription of HIV-1 (HIV). Since poly(ADP-ribose) polymerase 1 (PARP-1) regulates numerous genes through its interaction with various transcription factors, inhibition of PARP-1 has surfaced recently as a powerful anti-inflammatory tool. We suggest a novel tactic to diminish HIV replication via PARP-1 inhibition in an in vitro model system, exploiting human primary monocyte-derived macrophages (MDM). PARP-1 inhibition was capable to lessen HIV replication in MDM by 60–80% after 7 days infection. Tat, tumor necrosis factor α (TNFα), and phorbol 12-myristate 13-acetate (PMA) are known triggers of the Long Terminal Repeat (LTR), which can switch virus replication. Tat overexpression in MDM transfected with an LTR reporter plasmid resulted in a 4.2-fold increase in LTR activation; PARP inhibition caused 70% reduction of LTR activity. LTR activity, which increased 3-fold after PMA or TNFα treatment, was reduced by PARP inhibition (by 85–95%). PARP inhibition in MDM exhibited 90% diminution in NFκB activity (known to mediate TNFα- and PMA-induced HIV LTR activation). Cytoskeleton rearrangements are important in effective HIV-1 infection. PARP inactivation reduced actin cytoskeleton rearrangements by affecting Rho GTPase machinery. These discoveries suggest that inactivation of PARP suppresses HIV replication in MDM by via attenuation of LTR activation, NFκB suppression and its effects on the cytoskeleton. PARP appears to be essential for HIV replication and its inhibition may provide an effective approach to management of HIV infection.

Determinants of HIV-induced brain changes in three different periods of the early clinical course: A data mining analysis

To inform an understanding of brain status in HIV infection, quantitative imaging measurements were derived at structural, microstructural and macromolecular levels in three different periods of early infection and then analyzed simultaneously at each stage using data mining. Support vector machine recursive feature elimination was then used for simultaneous analysis of subject characteristics, clinical and behavioral variables, and immunologic measures in plasma and CSF to rank features associated with the most discriminating brain alterations in each period. The results indicate alterations beginning in initial infection and in all periods studied. The severity of immunosuppression in the initial virus host interaction was the most highly ranked determinant of earliest brain alterations. These results shed light on the initial brain changes induced by a neurotropic virus and their subsequent evolution. The pattern of ongoing alterations occurring during and beyond the period in which virus is suppressed in the systemic circulation supports the brain as a viral reservoir that may preclude eradication in the host. Data mining capabilities that can address high dimensionality and simultaneous analysis of disparate information sources have considerable utility for identifying mechanisms underlying onset of neurological injury and for informing new therapeutic targets.

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The brain was examined in initial stages of HIV using imaging and data mining.

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Brain alterations were identified in all studied periods of the early course.

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Severity of immunosuppression was the highest ranked determinant of onset.

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MMP-1 and CD33+CD36+ monocytes were identified as determinants in every period.

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The brain may represent an early reservoir that precludes viral eradication.

Curcumin improves synaptic plasticity impairment induced by HIV-1gp120 V3 loop

Curcumin has been shown to significantly improve spatial memory impairment induced by HIV-1 gp120 V3 in rats, but the electrophysiological mechanism remains unknown. Using extracellular microelectrode recording techniques, this study confirmed that the gp120 V3 loop could suppress long-term potentiation in the rat hippocampal CA1 region and synaptic plasticity, and that curcumin could antagonize these inhibitory effects. Using a Fura-2/AM calcium ion probe, we found that curcumin resisted the effects of the gp120 V3 loop on hippocampal synaptosomes and decreased Ca²⁺ concentration in synaptosomes. This effect of curcumin was identical to nimodipine, suggesting that curcumin improved the inhibitory effects of gp120 on synaptic plasticity, ameliorated damage caused to the central nervous system, and might be a potential neuroprotective drug.

Activation of Cannabinoid Type Two Receptors (CB2) Diminish Inflammatory Responses in Macrophages and Brain Endothelium

Chronic neuroinflammatory disorders (such as HIV associated neurodegeneration) require treatment that decreases production of inflammatory factors by activated microglia and macrophages and protection of blood brain barrier (BBB) injury secondary to activation of brain endothelium. Cannabioid type 2 receptor (CB2) is highly expressed on macrophages and brain microvasular enndothelial cells (BMVEC) and is upregulated in inflammation and HIV infection. It has been shown that CB2 activation dampened inflammatory responses in macrophages and BMVEC. In this study, we assessed by PCR array the expression of a wide range of genes increased in macrophages and BMVEC in inflammation. TNFα treatment upregulated 33 genes in primary human BMVEC, and two highly selective CB2 agonists diminished expression of 31 and 32 genes. These results were confirmed by functional assays (BBB protection after inflammatory insult and decreased migration of monocytes across BMVEC monolayers after CB2 stimulation). Similarly, CB2 stimulation in primary human macrophages led to the suppression of 35 genes out of the 50 genes upregulated by LPS. Such changes in gene expression paralleled diminished secretion of proinflammatory factors. These results indicate the potential utility of CB2 agonists for the treatment of neuroinflammation.

HIV-1, HCV and alcohol in the CNS: potential interactions and effects on neuroinflammation

Approximately 25% of the HIV-1 positive population is also infected with HCV. The effects of alcohol on HIV-1 or HCV infection have been a research topic of interest due to the high prevalence of alcohol use in these infected patient populations. Although it has long been known that HIV-1 infects the brain, it has only been a little more than a decade since HCV infection of the CNS has been characterized. Both viruses are capable of infecting and replicating in microglia and increasing the expression of proinflammatory cytokines and chemokines, including IL-6 and IL-8. Investigations focusing on the effects of HIV-1, HCV or alcohol on neuroinflammation have demonstrated that these agents are capable of acting through overlapping signaling pathways, including MAPK signaling molecules. In addition, HIV-1, HCV and alcohol have been demonstrated to increase permeability of the blood-brain barrier. Patients infected with either HIV-1 or HCV, or those who use alcohol, exhibit metabolic abnormalities in the CNS that result in altered levels of n-acetyl aspartate, choline and creatine in various regions of the brain. Treatment of HIV/HCV co-infection in alcohol users is complicated by drug-drug interactions, as well as the effects of alcohol on drug metabolism. The drug-drug interactions between the antiretrovirals and the antivirals, as well as the effects of alcohol on drug metabolism, complicate existing models of CNS penetration, making it difficult to assess the efficacy of treatment on CNS infection.

Mutations at tyrosine 88, lysine 92 and tyrosine 470 of human dopamine transporter result in an attenuation of HIV-1 Tat-induced inhibition of dopamine transport

HIV-1 transactivator of transcription (Tat) protein disrupts the dopamine (DA) neurotransmission by inhibiting DA transporter (DAT) function, leading to increased neurocognitive impairment in HIV-1 infected individuals. Through integrated computational modeling and pharmacological studies, we have demonstrated that mutation of tyrosine470 (Y470H) of human DAT (hDAT) attenuates Tat-induced inhibition of DA uptake by changing the transporter conformational transitions. The present study examined the functional influences of other substitutions at tyrosine470 (Y470F and Y470A) and tyrosine88 (Y88F) and lysine92 (K92M), two other relevant residues for Tat binding to hDAT, in Tat-induced inhibitory effects on DA transport. Y88F, K92M and Y470A attenuated Tat-induced inhibition of DA transport, implicating the functional relevance of these residues for Tat binding to hDAT. Compared to wild type hDAT, Y470A and K92M but not Y88F reduced the maximal velocity of [(3)H]DA uptake without changes in the Km. Y88F and K92M enhanced IC50 values for DA inhibition of [(3)H]DA uptake and [(3)H]WIN35,428 binding but decreased IC50 for cocaine and GBR12909 inhibition of [(3)H]DA uptake, suggesting that these residues are critical for substrate and these inhibitors. Y470F, Y470A, Y88F and K92M attenuated zinc-induced increase of [(3)H]WIN35,428 binding. Moreover, only Y470A and K92M enhanced DA efflux relative to wild type hDAT, suggesting mutations of these residues differentially modulate transporter conformational transitions. These results demonstrate Tyr88 and Lys92 along with Tyr470 as functional recognition residues in hDAT for Tat-induced inhibition of DA transport and provide mechanistic insights into identifying target residues on the DAT for Tat binding.

Depression in HIV infected patients: a review

Depression is the most common neuropsychiatric complication in HIV-infected patients and may occur in all phases of the infection. Accurately, diagnosing major depressive disorder in the context of HIV is an ongoing challenge to clinicians and researchers, being complicated by the complex biological, psychological, and social factors associated with the HIV illness. Evidences exist to support the importance of improving the identification of depressive symptoms and their adequate treatment. Depression has long been recognized as a predictor of negative clinical outcomes in HIV-infected patients, such as reducing medication adherence, quality of life, and treatment outcome, and possibly worsening the progression of the illness and increasing mortality. By analyzing the most relevant studies (MEDLINE, EMBASE, PsycLit, Cochrane Library), the review discusses the epidemiology and the main clinical features of depression in HIV-infected patients, the causal pathways linking depression and HIV infection, the validity of screening tools, and the efficacy of different treatment approaches, including psychosocial interventions, psychopharmacology as well as HIV-specific health psychology health service models.

HIV-1 Nef induces CCL5 production in astrocytes through p38-MAPK and PI3K/Akt pathway and utilizes NF-kB, CEBP and AP-1 transcription factors

The prevalence of HIV-associated neurocognitive disorders (HAND) remains high in patients infected with HIV-1. The production of pro-inflammatory cytokines by astrocytes/microglia exposed to viral proteins is thought to be one of the mechanisms leading to HIV-1- mediated neurotoxicity. In the present study we examined the effects of Nef on CCL5 induction in astrocytes. The results demonstrate that CCL5 is significantly induced in Nef-transfected SVGA astrocytes. To determine the mechanisms responsible for the increased CCL5 caused by Nef, we employed siRNA and chemical antagonists. Antagonists of NF-κB, PI3K, and p38 significantly reduced the expression levels of CCL5 induced by Nef transfection. Furthermore, specific siRNAs demonstrated that the Akt, p38MAPK, NF-κB, CEBP, and AP-1 pathways play a role in Nef-mediated CCL5 expression. The results demonstrated that the PI3K/Akt and p38 MAPK pathways, along with the transcription factors NF-κB, CEBP, and AP-1, are involved in Nef-induced CCL5 production in astrocytes.

Neuroprotective activity of pDING in response to HIV-1 Tat

Although neurons are not productively infected with HIV-1, neuronal injury and death are frequently seen in the brains of AIDS patients with neurological and neurocognitive disorders. Evidently, viral proteins including Tat and cellular inflammatory factors released by activated and/or infected microglia, macrophages, and astrocytes contribute to neuronal cell death. Several studies have demonstrated that HIV-1 associated neuronal cell injury is mediated by dysregulation of signaling pathways that are controlled, in part, by a class of serine/threonine kinases. In this study, we demonstrate that pDING, a novel plant-derived phosphate binding protein has the capacity to reduce the severity of injury and death caused by HIV-1 and its neurotoxic Tat protein. We demonstrate that pDING, also called p27SJ/p38SJ, protects cells from the loss of neuronal processes induced by Tat and promotes neuronal outgrowth after Tat-mediated injury. Further, expression of pDING prevents Tat-induced oxidative stress and mitochondrial permeability. With its profound phosphatase activity, pDING controls the activity of several kinases including MAPK, Cdk5, and their downstream target protein, MEF2, which is implicated in neuronal cell protection. Our results show that expression of pDING in neuronal cells diminishes the level of hyperphosphorylated forms of Cdk5 and MEF2 caused by Tat and the other neurotoxic agents that are secreted by the HIV-1 infected cells. These observations suggest that pDING, through its phosphatase activity, has the ability to manipulate the state of phosphorylation and activity of several factors involved in neuronal cell health in response to HIV-1.

Commentary on the interactions of HIV and alcohol in the central nervous system

This commentary is to highlight the relevance and public interest of the review published by Silverstein and Kumar, which focuses on the mechanisms by which alcohol and HIV-1 infection cause increased in central nervous system (CNS) damage. The overall review is based on previous literature with cell culture systems and animal models that have demonstrated that exposure to alcohol and HIV infection or HIV viral proteins result in synergistic up-regulation of pro-inflammatory cytokines and oxidative stress. The authors discuss the effects of alcohol on cells in the CNS, followed by a brief discussion on the impact of HIV-1 and HIV proteins on the CNS, and the final section focuses on the combined effects of HIV and alcohol on the CNS as determined by in vitro, in vivo, and clinical studies.

HIV-1 and alcohol: interactions in the central nervous system

The use of alcohol has been associated with both an increased risk of acquisition of HIV-1 infection and an increased rate of disease progression among those already infected by the virus. The potential for alcohol to exacerbate the effects of HIV infection is especially important in the central nervous system (CNS) because this area is vulnerable to the combined effects of alcohol and HIV infection. The effects of alcohol on glial cells are mediated through receptors such as Toll-like receptor 4 and N-methyl-d-aspartate receptor. This causes the activation of signaling molecules such as interleukin-1 receptor-associated kinase and various members of the P38 mitogen-activated protein kinase family and subsequent activation of transcription factors such as nuclear factor-kappa beta and activator protein 1. The eventual outcome is an increase in pro-inflammatory cytokine production by glial cells. Alcohol also induces higher levels of NADPH oxidase in glial cells, which leads to an increased production of reactive oxygen species (ROS). Viral invasion of the CNS occurs early after infection, and HIV proteins have also been demonstrated to increase levels of pro-inflammatory cytokines and ROS in glial cells through activation of some of the same pathways activated by alcohol. Both cell culture systems and animal models have demonstrated that concomitant exposure to alcohol and HIV/HIV proteins results in increased levels of expression of pro-inflammatory cytokines such as interleukin-1 beta and tumor necrosis factor-alpha, along with increased levels of oxidative stress. Clinical studies also suggest that alcohol exacerbates the CNS effects of HIV-1 infection. This review focuses on the mechanisms by which alcohol causes increased CNS damage in HIV-1 infection.

CB2 receptor agonists protect human dopaminergic neurons against damage from HIV-1 gp120

Despite the therapeutic impact of anti-retroviral therapy, HIV-1-associated neurocognitive disorder (HAND) remains a serious threat to AIDS patients, and there currently remains no specific therapy for the neurological manifestations of HIV-1. Recent work suggests that the nigrostriatal dopaminergic area is a critical brain region for the neuronal dysfunction and death seen in HAND and that human dopaminergic neurons have a particular sensitivity to gp120-induced damage, manifested as reduced function (decreased dopamine uptake), morphological changes, and reduced viability. Synthetic cannabinoids inhibit HIV-1 expression in human microglia, suppress production of inflammatory mediators in human astrocytes, and there is substantial literature demonstrating the neuroprotective properties of cannabinoids in other neuropathogenic processes. Based on these data, experiments were designed to test the hypothesis that synthetic cannabinoids will protect dopaminergic neurons against the toxic effects of the HIV-1 protein gp120. Using a human mesencephalic neuronal/glial culture model, which contains dopaminergic neurons, microglia, and astrocytes, we were able to show that the CB1/CB2 agonist WIN55,212-2 blunts gp120-induced neuronal damage as measured by dopamine transporter function, apoptosis and lipid peroxidation; these actions were mediated principally by the CB2 receptor. Adding supplementary human microglia to our cultures enhances gp120-induced damage; WIN55,212-2 is able to alleviate this enhanced damage. Additionally, WIN55,212-2 inhibits gp120-induced superoxide production by purified human microglial cells, inhibits migration of human microglia towards supernatants generated from gp120-stimulated human mesencephalic neuronal/glial cultures and reduces chemokine and cytokine production from the human mesencephalic neuronal/glial cultures. These data suggest that synthetic cannabinoids are capable of protecting human dopaminergic neurons from gp120 in a variety of ways, acting principally through the CB2 receptors and microglia.

Transcriptome sequencing of gene expression in the brain of the HIV-1 transgenic rat

The noninfectious HIV-1 transgenic (HIV-1Tg) rat was developed as a model of AIDs-related pathology and immune dysfunction by manipulation of a noninfectious HIV-1^gag-pol virus with a deleted 3-kb SphI-MscI fragment containing the 3′ -region of gag and the 5′ region of pol into F344 rats. Our previous studies revealed significant behavioral differences between HIV-1Tg and F344 control rats in their performance in the Morris water maze and responses to psychostimulants. However, the molecular mechanisms underlying these behavioral differences remain largely unknown. The primary goal of this study was to identify differentially expressed genes and enriched pathways affected by the gag-pol-deleted HIV-1 genome. Using RNA deep sequencing, we sequenced RNA transcripts in the prefrontal cortex, hippocampus, and striatum of HIV-1Tg and F344 rats. A total of 72 RNA samples were analyzed (i.e., 12 animals per group × 2 strains × 3 brain regions). Following deep-sequencing analysis of 50-bp paired-end reads of RNA-Seq, we used Bowtie/Tophat/Cufflinks suites to align these reads into transcripts based on the Rn4 rat reference genome and to measure the relative abundance of each transcript. Statistical analyses on each brain region in the two strains revealed that immune response- and neurotransmission-related pathways were altered in the HIV-1Tg rats, with brain region differences. Other neuronal survival-related pathways, including those encoding myelin proteins, growth factors, and translation regulators, were altered in the HIV-1Tg rats in a brain region-dependent manner. This study is the first deep-sequencing analysis of RNA transcripts associated the HIV-1Tg rat. Considering the functions of the pathways and brain regions examined in this study, our findings of abnormal gene expression patterns in HIV-1Tg rats suggest mechanisms underlying the deficits in learning and memory and vulnerability to drug addiction and other psychiatric disorders observed in HIV-positive patients.

The spatial relationship between neurons and astrocytes in HIV-associated dementia

Specific neuronal spatial distributional patterns have previously been correlated with increasing severity of HIV-associated dementia (HAD). As astrocytes are also a putative site of neurotoxicity, we investigated the spatial relationships of astrocytes with pyramidal and interneurons in the superior frontal gyrus from 29 patients who died from acquired immunodeficiency syndrome. Frontal cortical brain tissue was taken from diseased HIV patients who had been assessed for the presence and severity of HAD using the Memorial Sloan-Kettering Scale. No correlation was found between neuronal density and severity of dementia. However, the pattern of astrocytes became more clustered as dementia progressed. Bivariate spatial pattern analysis of neuronal populations with astrocytes revealed that, with increasing dementia severity, astrocytes and large pyramidal neurons increasingly "repelled" each other, while astrocytes and interneurons evidenced increasing "attraction." This implies that astrocytes may be more likely to be situated in the vicinity of surviving interneurons but less likely to be situated near surviving large pyramidal neurons in the setting of progressing HAD.

Expression of ephrin receptors and ligands in postmortem brains of HIV-infected subjects with and without cognitive impairment

Despite the successes of combination antiretroviral therapy, HIV-associated neurocognitive disorders persist in many infected individuals. Earlier studies showed that neurocognitive impairment was associated with glutamate toxicity and synaptodendritic damage. We examined alterations in expression of four ephrin genes that are involved in synapse formation and recruitment of glutamate receptors to synapses, in the caudate and anterior cingulate in postmortem brain of cognitively characterized HIV-infected subjects, along with expression of neuronal and astroglial/macroglial markers. Postmortem tissues of HIV-infected and control subjects were obtained from the Manhattan HIV Brain Bank. HIV-infected subjects underwent neurocognitive assessment prior to death. Quantification of mRNA of genes of chemokine receptors and chemokines (CCR5, CXCR4, CCL2), astroglial/microglial markers (GFAP, CD163, CD68), the neuronal marker SNAP25, ephrin receptors EPHA4 and EPHB2, and ephrin ligands EFNB1 and EFNB2 was performed using SYBR Green RT-PCR. Proinflammatory chemokine and glial/macrophage mRNA levels in both regions were significantly greater in HIV+ than in HIV- subjects. Levels of EPHA4 and EFNB2 mRNA in the caudate, and EPHB2 mRNA in anterior cingulate were significantly lower in HIV+ subjects (p < 0.002, p < 0.02, p < 0.05, respectively). These transcripts also showed correlations with immune status and cognitive function within the HIV-infected group. Decreased levels of EFNB2 mRNA in the caudate correlated with lower CD4 counts (P < 0.05). Cognitive associations were limited to the cingulate, where decreased levels of EPHB2 mRNA were associated with better global cognitive status. Decreased cingulate expression of EPHB2 may represent a compensatory mechanism minimizing excitotoxic injury in the face of chronic inflammation.

Synergistic cooperation between methamphetamine and HIV-1 gsp120 through the P13K/Akt pathway induces IL-6 but not IL-8 expression in astrocytes

HIV-1 envelope protein gp120 has been extensively studied for neurotoxic effects that have been attributed to the increased expression of various proinflammatory cytokines in the CNS. Recently we have shown that methamphetamine (MA) also increases expression of proinflammatory cytokines in astrocytes. However, combined effect of gp120 and MA is not known. The present study was undertaken to determine cumulative effect and the mechanism(s)/pathways involved in the functional interaction between gp120 and MA in SVGA astrocytes. Our results clearly suggest that gp120 and MA affect IL-6 but not IL-8 in a synergistic manner and this synergy was mediated by PI3K/Akt and NF-κB pathways. Inhibition of either of these pathways could abrogate the increased expression of IL-6 due to MA or gp120 alone, as well as the increased expression of IL-6 when the astrocytes were treated with both gp120 and MA. These results were confirmed by both, using chemical inhibitors/siRNA as well as western blotting. This study therefore provides novel information regarding the interaction between MA and gp120 in terms of the expression of IL-6 and the mechanisms underlying potential synergy between MA and gp120 in astrocytes.

Pathogenesis of HIV-associated sensory neuropathy: evidence from in vivo and in vitro experimental models

HIV-associated sensory neuropathy (HIV-SN) is a frequent neurological complication of HIV infection and its treatment with some antiretroviral drugs. We review the pathogenesis of the viral- and drug-induced causes of the neuropathy, and its primary symptom, pain, based on evidence from in vivo and in vitro models of HIV-SN. Viral coat proteins mediate nerve fibre damage and hypernociception through direct and indirect mechanisms. Direct interactions between viral proteins and nerve fibres dominate axonal pathology, while somal pathology is dominated by indirect mechanisms that occur secondary to virus-mediated activation of glia and macrophage infiltration into the dorsal root ganglia. The treatment-induced neuropathy and resulting hypernociception arise primarily from drug-induced mitochondrial dysfunction, but the sequence of events initiated by the mitochondrial dysfunction that leads to the nerve fibre damage and dysfunction are still unclear. Overall, the models that have been developed to study the pathogenesis of HIV-SN, and hypernociception associated with the neuropathy, are reasonable models and have provided useful insights into the pathogenesis of HIV-SN. As new models are developed they may ultimately lead to identification of therapeutic targets for the prevention or treatment of this common neurological complication of HIV infection.

Neuronal apoptosis by HIV-1 Vpr: contribution of proinflammatory molecular networks from infected target cells

Background

Human immunodeficiency virus type 1 (HIV-1) induces neuronal dysfunction through host cellular factors and viral proteins including viral protein R (Vpr) released from infected macrophages/microglia. Vpr is important for infection of terminally differentiated cells such as macrophages. The objective of this study was to assess the effect of Vpr in the context of infectious virus particles on neuronal death through proinflammatory cytokines released from macrophages.

Methods

Monocyte-derived macrophages (MDM) were infected with either HIV-1 wild type (HIV-1^wt), Vpr deleted mutant (HIV-1∆Vpr) or mock. Cell lysates and culture supernatants from MDMs were analyzed for the expression and release of proinflammatory cytokines by quantitative reverse transcription-PCR and enzyme-linked immunosorbent assay respectively. Mitogen-activated protein kinases (MAPK) were analyzed in activated MDMs by western blots. Further, the effect of Vpr on neuronal apoptosis was examined using primary neurons exposed to culture supernatants from HIV-1^wt, HIV-1∆Vpr or mock-infected MDMs by Annexin-V staining, MTT and Caspase - Glo® 3/7 assays. The role of interleukin (IL)-1β, IL-8 and tumor necrosis factor (TNF)-α on neuronal apoptosis was also evaluated in the presence or absence of neutralizing antibodies against these cytokines.

Results

HIV-1∆Vpr-infected MDMs exhibited reduced infection over time and specifically a significant downregulation of IL-1β, IL-8 and TNF-α at the transcriptional and/or protein levels compared to HIV-1^wt-infected cultures. This downregulation was due to impaired activation of p38 and stress-activated protein kinase (SAPK)/c-Jun N-terminal kinase (JNK) in HIV-1∆Vpr-infected MDMs. The association of SAPK/JNK and p38 to IL-1β and IL-8 production was confirmed by blocking MAPKs that prevented the elevation of IL-1β and IL-8 in HIV-1^wt more than in HIV-1∆Vpr-infected cultures. Supernatants from HIV-1∆Vpr-infected MDMs containing lower concentrations of IL-1β, IL-8 and TNF-α as well as viral proteins showed a reduced neurotoxicity compared to HIV-1^wt-infected MDM supernatants. Reduction of neuronal death in the presence of anti-IL-1β and anti-IL-8 antibodies only in HIV-1^wt-infected culture implies that the effect of Vpr on neuronal death is in part mediated through released proinflammatory factors.

Conclusion

Collectively, these results demonstrate the ability of HIV-1∆Vpr to restrict neuronal apoptosis through dysregulation of multiple proinflammatory cytokines in the infected target cells either directly or indirectly by suppressing viral replication.

Soy isoflavones genistein and daidzein exert anti-apoptotic actions via a selective ER-mediated mechanism in neurons following HIV-1 Tat(1-86) exposure

Background

HIV-1 viral protein Tat partially mediates the neural dysfunction and neuronal cell death associated with HIV-1 induced neurodegeneration and neurocognitive disorders. Soy isoflavones provide protection against various neurotoxic insults to maintain neuronal function and thus help preserve neurocognitive capacity.

Methodology/Principal Findings

We demonstrate in primary cortical cell cultures that 17β-estradiol or isoflavones (genistein or daidzein) attenuate Tat_1–86-induced expression of apoptotic proteins and subsequent cell death. Exposure of cultured neurons to the estrogen receptor antagonist ICI 182,780 abolished the anti-apoptotic actions of isoflavones. Use of ERα or ERβ specific antagonists determined the involvement of both ER isoforms in genistein and daidzein inhibition of caspase activity; ERβ selectively mediated downregulation of mitochondrial pro-apoptotic protein Bax. The findings suggest soy isoflavones effectively diminished HIV-1 Tat-induced apoptotic signaling.

Conclusions/Significance

Collectively, our results suggest that soy isoflavones represent an adjunctive therapeutic option with combination anti-retroviral therapy (cART) to preserve neuronal functioning and sustain neurocognitive abilities of HIV-1 infected persons.

Psychiatric comorbidity in injecting drug users in Asia and Africa

PURPOSE OF REVIEW

The prevalence of psychiatric co-morbidity in injecting drug users (IDUs) in the Western countries is high and is associated with lower quality of life and reduces the effectiveness of treatment programs. The aim of this study is to provide a review about psychiatric comorbidity in IDUs in Asia and Africa, where HIV prevalence is high and still increasing.

RECENT FINDINGS

Studies focusing on psychiatric comorbidity in Asia and Africa are scarce. The prevalence of psychiatric comorbidity is comparable with the prevalence in western countries. Psychiatric disorders can occur before or during drug abuse and are also associated with substance abuse and physical comorbidity and its treatments. Childhood trauma followed by post-traumatic disorders is a significant risk factor for substance abuse. Psychiatric co-occurring disorders influence the adherence to the physical and drug use treatment. Evidence-based treatment for psychiatric comorbidity in IDUs is still limited.

SUMMARY

A better understanding of the prevalence of psychiatric disorders in IDUs and its impact on the overall treatments is growing. However, more studies focusing on the treatment for psychiatric comorbidity in IDUs in Asia and Africa are needed.

Lessons learned at the intersection of immunology and neuroscience

Neurobiologists and immunologists study concepts often signified with identical terminology. Scientists in both fields study a structure known as the synapse, and each group analyzes a subject called memory. Is this a quirk of human language, or are there real similarities between these two physiological systems? Not only are the linguistic concepts expressed in the words "synapse" and "memory" shared between the fields, but the actual molecules of physiologic importance in one system play parallel roles in the other: complement, the major histocompatibility molecules, and even "neuro"-transmitters all have major impacts on health and on disease in both the brain and the immune system. Not only are the same molecules found in diverse roles in each system, but we have learned that there is real "hard-wired" crosstalk between nerves and lymphoid organs. This issue of the JCI highlights some of the lessons learned from experts who are working at this scintillating intersection between immunology and neuroscience.

Prefrontal dopaminergic and enkephalinergic synaptic accommodation in HIV-associated neurocognitive disorders and encephalitis

Changes in synapse structure occur in frontal neocortex with HIV encephalitis (HIVE) and may contribute to HIV-associated neurocognitive disorders (HAND). A postmortem survey was conducted to determine if mRNAs involved in synaptic transmission are perturbed in dorsolateral prefrontal cortex (DLPFC) in subjects with HIVE or HAND. Expression of the opioid neurotransmitter preproenkephalin mRNA (PENK) was significantly decreased in a sampling of 446 brain specimens from HIV-1 infected people compared to 67 HIV negative subjects. Decreased DLPFC PENK was most evident in subjects with HIVE and/or increased expression of interferon regulatory factor 1 mRNA (IRF1). Type 2 dopamine receptor mRNA (DRD2L) was decreased significantly, but not in the same set of subjects with PENK dysregulation. DRD2L downregulation occurred primarily in the subjects without HIVE or neurocognitive impairment. Subjects with neurocognitive impairment often failed to significantly downregulate DRD2L and had abnormally high IRF1 expression. Conclusion: Dysregulation of synaptic preproenkephalin and DRD2L in frontal neocortex can occur with and without neurocognitive impairment in HIV-infected people. Downregulation of DRD2L in the prefrontal cortex was associated with more favorable neuropsychological and neuropathological outcomes; the failure to downregulate DRD2L was significantly less favorable. PENK downregulation was related neuropathologically to HIVE, but was not related to neuropsychological outcome independently. Emulating endogenous synaptic plasticity pharmacodynamically could enhance synaptic accommodation and improve neuropsychological and neuropathological outcomes in HIV/AIDS.

HIV-associated neurological disorders: a guide to pharmacotherapy

In the era of highly active antiretroviral therapy (HAART), HIV-1-associated neurocognitive disorder (HAND) continues to be a common and significant morbidity among individuals infected with HIV. The term HAND encompasses a spectrum of progressively severe CNS involvement, ranging from asymptomatic neurocognitive impairment and minor neurocognitive disorder through to the most severe form of HIV-associated dementia (HAD). While the incidence of HAD has declined significantly with HAART, the milder forms of HAND persist. In addition, HAND now develops in individuals with less advanced immunosuppression. The reasons for the persistence of milder forms of HAND in individuals treated with HAART are not entirely known. There are several hypotheses to explain this phenomenon that include the legacy effect, a failure of antiretroviral agents to reverse neurological damage, poor access of antiretroviral agents to the CNS, chronic systemic immune activation associated with microbial translocation products, sustained CNS inflammation, the improved survival of HIV-seropositive individuals and the possible contribution from aging, amyloid deposition and other co-morbidities. In contrast, the incidence of HIV-associated CNS opportunistic processes including progressive multifocal leukoencephalopathy, tuberculosis, CNS toxoplasmosis, cytomegalovirus encephalitis, cryptococcosis and primary CNS lymphoma has declined dramatically with the introduction of HAART. This review briefly summarizes our current understanding of HAND and the pathological mechanisms involved, namely direct injury from HIV-1 and viral proteins, indirect neurotoxicity from proinflammatory cytokines and chronic, sustained immune activation in the CNS. To date, only HAART has been shown to benefit HAND despite numerous controlled trials of adjunctive 'anti-inflammatory' agents. Although HAART has a profound impact on the incidence and severity of HAND, there exists a 'therapeutic gap' as even HAART that is effective at inducing durable virological suppression may only partially reverse HAND. In addition, there may be potential CNS adverse effects of antiretroviral agents. There is an ongoing multicentre clinical trial to investigate the role of the CNS Penetration-Effectiveness index, an indicator of drug permeability and availability in the CNS, to help guide the choice of antiretroviral agents in the treatment of HAND. With recent recommendations for earlier treatment intervention with HAART for HIV-1 infection, it remains to be seen the effects of this on HAND. There is an urgent need to better define the therapeutic guidelines for the prevention and treatment of HAND.

A plasma microRNA signature of acute lentiviral infection: biomarkers of central nervous system disease

OBJECTIVE

Plasma microRNAs (miRNAs) are modulated during disease and are emerging biomarkers; they have not been characterized in HIV infection. Using our macaque/simian immunodeficiency virus (SIV) model of HIV, we sought to identify a plasma miRNA profile of acute lentiviral infection, evaluate its relationship with known cellular and viral determinants of lentivirus-associated central nervous system (CNS) disease, and explore the potential of miRNAs to predict CNS disease.

DESIGN

Plasma samples were obtained before inoculation and 10 days after inoculation from SIV-infected macaques.

METHODS

Plasma miRNA expression profiles were determined by TaqMan low-density array for six individuals. miRNA expression was compared with levels of cytokines, virus, and plasma platelet count. miRNA results were confirmed by single miRNA-specific assays for 10 macaques. Nineteen individuals were used to validate a disease prediction test.

RESULTS

A 45-miRNA signature of acute infection (differential expression with P < 0.05 after multiple comparison correction) classified plasma as infected or not. Several differentially expressed miRNAs correlated with CNS disease-associated cytokines interleukin-6 and CCL2 and included predicted and/or validated regulators of the corresponding mRNAs. miRNAs tracked with viral load and platelet count were also predictors of CNS disease. At least six miRNAs were significantly differentially expressed in individuals with severe versus no CNS disease; in an unweighted expression test, they predicted CNS disease.

CONCLUSION

Acute-phase differential expression of plasma miRNAs predicts CNS disease and suggests that CNS damage or predisposition to disease progression begins in the earliest phase of infection. Plasma miRNAs should be investigated further as leading indicators of HIV diseases as early as acute infection.

HIV-1 and IL-1β regulate astrocytic CD38 through mitogen-activated protein kinases and nuclear factor-κB signaling mechanisms

Background

Infection with human immunodeficiency virus type-1 (HIV)-1 leads to some form of HIV-1-associated neurocognitive disorders (HAND) in approximately half of the cases. The mechanisms by which astrocytes contribute to HIV-1-associated dementia (HAD), the most severe form of HAND, still remain unresolved. HIV-1-encephalitis (HIVE), a pathological correlate of HAD, affects an estimated 9-11% of the HIV-1-infected population. Our laboratory has previously demonstrated that HIVE brain tissues show significant upregulation of CD38, an enzyme involved in calcium signaling, in astrocytes. We also reported an increase in CD38 expression in interleukin (IL)-1β-activated astrocytes. In the present investigation, we studied regulatory mechanisms of CD38 gene expression in astrocytes activated with HIV-1-relevant stimuli. We also investigated the role of mitogen-activated protein kinases (MAPKs) and nuclear factor (NF)-κB in astrocyte CD38 regulation.

Methods

Cultured human astrocytes were transfected with HIV-1_YU-2 proviral clone and levels of CD38 mRNA and protein were measured by real-time PCR gene expression assay, western blot analysis and immunostaining. Astrocyte activation by viral transfection was determined by analyzing proinflammatory chemokine levels using ELISA. To evaluate the roles of MAPKs and NF-κB in CD38 regulation, astrocytes were treated with MAPK inhibitors (SB203580, SP600125, U0126), NF-κB interfering peptide (SN50) or transfected with dominant negative IκBα mutant (IκBαM) prior to IL-1β activation. CD38 gene expression and CD38 ADP-ribosyl cyclase activity assays were performed to analyze alterations in CD38 levels and function, respectively.

Results

HIV-1_YU-2-transfection significantly increased CD38 mRNA and protein expression in astrocytes (p < 0.01) in a dose-dependent manner and induced astrocyte activation. IL-β-activation of HIV-1_YU-2-transfected astrocytes significantly increased HIV-1 gene expression (p < 0.001). Treatment with MAPK inhibitors or NF-κB inhibitor SN50 abrogated IL-1β-induced CD38 expression and activity in astrocytes without altering basal CD38 levels (p < 0.001). IκBαM transfection also significantly inhibited IL-1β-mediated increases in CD38 expression and activity in astrocytes (p < 0.001).

Conclusion

The present findings demonstrate a direct involvement of HIV-1 and virus-induced proinflammatory stimuli in regulating astrocyte-CD38 levels. HIV-1_YU-2-transfection effectively induced HIV-1p24 protein expression and activated astrocytes to upregulate CCL2, CXCL8 and CD38. In astrocytes, IL-1β-induced increases in CD38 levels were regulated through the MAPK signaling pathway and by the transcription factor NF-κB. Future studies may be directed towards understanding the role of CD38 in response to infection and thus its role in HAND.