Human immunodeficiency virus type 1 clade B and C gp120 differentially induce neurotoxin arachidonic acid in human astrocytes: implications for neuroAIDS

A pilot investigation of the association between HIV-1 Vpr amino acid sequence diversity and the tryptophan-kynurenine pathway as a potential mechanism for neurocognitive impairment

HIV infection compromises both the peripheral and central immune systems due to its pathogenic and neuropathogenic features. The mechanisms driving HIV-1 pathogenesis and neuropathogenesis involve a series of events, including metabolic dysregulation. Furthermore, HIV-subtype-specific variations, particularly alterations in the amino acid sequences of key viral proteins, are known to influence the severity of clinical outcomes in people living with HIV. However, the impact of amino acid sequence variations in specific viral proteins, such as Viral protein R (Vpr), on metabolites within the Tryptophan (Trp)-kynurenine (Kyn) pathway in people living with HIV remains unclear. Our research aimed to explore the relationship between variations in the Vpr amino acid sequence (specifically at positions 22, 41, 45, and 55, as these have been previously linked to neurocognitive function) and peripheral Trp-Kyn metabolites. Additionally, we sought to clarify the systems biology of Vpr sequence variation by examining the link between Trp-Kyn metabolism and peripheral inflammation, as a neuropathogenic mechanism. In this preliminary study, we analyzed a unique cohort of thirty-two (n = 32) South African cART naïve people living with HIV. We employed Sanger sequencing to ascertain blood-derived Vpr amino acid sequence variations and a targeted LC-MS/MS metabolomics platform to assess Trp-Kyn metabolites, such as Trp, Kyn, kynurenic acid (KA), and quinolinic acid (QUIN). Particle-enhanced turbidimetric assay and Enzyme-linked immunosorbent assays were used to measure immune markers, hsCRP, IL-6, suPAR, NGAL and sCD163. After applying Bonferroni corrections (p =.05/3) and adjusting for covariates (age and sex), only the Vpr G41 and A55 groups was nearing significance for higher levels of QUIN compared to the Vpr S41 and T55 groups, respectively (all p =.023). Multiple regression results revealed that Vpr amino acid variations at position 41 (adj R2 = 0.049, β = 0.505; p =.023), and 55 (adj R2 = 0.126, β = 0.444; p =.023) displayed significant associations with QUIN after adjusting for age and sex. Lastly, the higher QUIN levels observed in the Vpr G41 group were found to be correlated with suPAR (r =.588, p =.005). These results collectively underscore the importance of specific Vpr amino acid substitutions in influencing QUIN and inflammation (specifically suPAR levels), potentially contributing to our understanding of their roles in the pathogenesis and neuropathogenesis of HIV-1.

Phospholipase B Is Critical for Cryptococcus neoformans Survival in the Central Nervous System

Cryptococcus neoformans (Cn) is an opportunistic, encapsulated, yeast-like fungus that causes severe meningoencephalitis, especially in countries with high HIV prevalence. In addition to its well-known polysaccharide capsule, Cn has other virulence factors such as phospholipases, a heterogeneous group of enzymes that hydrolyze ester linkages in glycerophospholipids. Phospholipase B (PLB1) has been demonstrated to play a key role in Cn pathogenicity. In this study, we used a PLB1 mutant (plb1) and its reconstituted strain (Rec1) to assess the importance of this enzyme on Cn brain infection in vivo and in vitro. Mice infected with the plb1 strain survive significantly longer, have lower peripheral and central nervous system (CNS) fungal loads, and have fewer and smaller cryptococcomas or biofilm-like brain lesions compared to H99- and Rec1-infected animals. PLB1 causes extensive brain tissue damage and changes microglia morphology during cryptococcal disease, observations which can have important implications in patients with altered mental status or dementia as these manifestations are related to poorer survival outcomes. plb1 cryptococci are significantly more phagocytosed and killed by NR-9460 microglia-like cells. plb1 cells have altered capsular polysaccharide biophysical properties which impair their ability to stimulate glial cell responses or morphological changes. Here, we provide significant evidence demonstrating that Cn PLB1 is an important virulence factor for fungal colonization of and survival in the CNS as well as in the progression of cryptococcal meningoencephalitis. These findings may potentially help fill in a gap of knowledge in our understanding of cerebral cryptococcosis and provide novel research avenues in Cn pathogenesis. IMPORTANCE Cryptococcal meningoencephalitis (CME) is a serious disease caused by infection by the neurotropic fungal pathogen Cryptococcus neoformans. Due to the increasing number of cases in HIV-infected individuals, as well as the limited therapies available, investigation into potential targets for new therapeutics has become critical. Phospholipase B is an enzyme synthesized by Cn that confers virulence to the fungus through capsular enlargement, immunomodulation, and intracellular replication. In this study, we examined the properties of PLB1 by comparing infection of a Cn PLB1 mutant strain with both the wild-type and a PLB1-reconstituted strain. We show that PLB1 augments the survival and proliferation of the fungus in the CNS and strengthens virulence by modulating the immune response and enhancing specific biophysical properties of the fungus. PLB1 expression causes brain tissue damage and impacts glial cell functions, which may be responsible for the dementia observed in patients which may persist even after resolving from CME. The implications of PLB1 inhibition reveal its involvement in Cn infection and suggest that it may be a possible molecular target in the development of antifungal therapies. The results of this study support additional investigation into the mechanism of PLB1 to further understand the intricacies of cerebral Cn infection.

Cocaine Self-Administration Influences Central Nervous System Immune Responses in Male HIV-1 Transgenic Rats

Cocaine use increases the neurotoxic severity of human immunodeficiency virus-1 (HIV-1) infection and the development of HIV-associated neurocognitive disorders (HAND). Among the studied cellular mechanisms promoting neurotoxicity in HIV-1 and cocaine use, central nervous system (CNS) immunity, such as neuroimmune signaling and reduced antiviral activity, are risk determinants; however, concrete evidence remains elusive. In the present study, we tested the hypothesis that cocaine self-administration by transgenic HIV-1 (HIV-1_Tg) rats promotes CNS inflammation. To test this hypothesis, we measured cytokine, chemokine, and growth factor protein levels in the frontal cortex (fCTX) and caudal striatum (cSTR). Our results demonstrated that cocaine self-administration significantly increased fCTX inflammation in HIV-1_Tg rats, but not in the cSTR. Accordingly, we postulate that cocaine synergizes with HIV-1 proteins to increase neuroinflammation in a region-selective manner, including the fCTX. Given the fCTX role in cognition, this interaction may contribute to the hyperimmunity and reduced antiviral activity associated with cocaine-mediated enhancement of HAND.

Arachidonic Acid Cascade and Eicosanoid Production Are Elevated While LTC4 Synthase Modulates the Lipidomics Profile in the Brain of the HIVgp120-Transgenic Mouse Model of NeuroHIV

BACKGROUND

Combination antiretroviral therapy (cART) has transformed HIV infection from a terminal disease to a manageable chronic health condition, extending patients' life expectancy to that of the general population. However, the incidence of HIV-associated neurocognitive disorders (HANDs) has persisted despite virological suppression. Patients with HIV display persistent signs of immune activation and inflammation despite cART. The arachidonic acid (AA) cascade is an important immune response system responsible for both pro- and anti-inflammatory processes.

METHODS

Lipidomics, mRNA and Western blotting analysis provide valuable insights into the molecular mechanisms surrounding arachidonic acid metabolism and the resulting inflammation caused by perturbations thereof.

RESULTS

Here, we report the presence of inflammatory eicosanoids in the brains of a transgenic mouse model of NeuroHIV that expresses soluble HIV-1 envelope glycoprotein in glial cells (HIVgp120tg mice). Additionally, we report that the effect of LTC4S knockout in HIVgp120tg mice resulted in the sexually dimorphic transcription of COX- and 5-LOX-related genes. Furthermore, the absence of LTC4S suppressed ERK1/2 and p38 MAPK signaling activity in female mice only. The mass spectrometry-based lipidomic profiling of these mice reveals beneficial alterations to lipids in the brain.

CONCLUSION

Targeting the AA cascade may hold potential in the treatment of neuroinflammation observed in NeuroHIV and HANDs.

HIV-1 Tat and cocaine impact mitochondrial epigenetics: effects on DNA methylation

Human immunodeficiency virus (HIV) infection and the psychostimulant drug cocaine are known to induce epigenetic changes in DNA methylation that are linked with the severity of viral replication and disease progression, which impair neuronal functions. Increasing evidence suggests that changes in DNA methylation and hydroxymethylation occur in mitochondrial DNA (mtDNA) and represent mitochondrial genome epigenetic modifications (mitoepigenetic modifications). These modifications likely regulate both mtDNA replication and gene expression. However, mtDNA methylation has not been studied extensively in the contexts of cocaine abuse and HIV-1 infection. In the present study, epigenetic factors changed the levels of the DNA methyltransferases (DNMTs) DNMT1, DNMT3a, and DNMT3b, the Ten-eleven translocation (TET) enzymes 1, 2, and 3, and mitochondrial DNMTs (mtDNMTs) both in vitro and in vivo. These changes resulted in alterations in mtDNA methylation levels at CpG and non-CpG sites in human primary astrocytes as measured using targeted next-generation bisulphite sequencing (TNGBS). Moreover, mitochondrial methylation levels in the MT-RNR1, MT-ND5, MT-ND1, D-loop and MT-CYB regions of mtDNA were lower in the HIV-1 Tat and cocaine treatment groups than in the control group. In summary, the present findings suggest that mitoepigenetic modification in the human brain causes the mitochondrial dysfunction that gives rise to neuro-AIDS.

HIV-Tat and Cocaine Impact Brain Energy Metabolism: Redox Modification and Mitochondrial Biogenesis Influence NRF Transcription-Mediated Neurodegeneration

HIV infection and drugs of abuse induce oxidative stress and redox imbalance, which cause neurodegeneration. The mechanisms by which HIV infection and cocaine consumption affect astrocyte energy metabolism, and how this leads to neurodegenerative dysfunction, remain poorly understood. Presently, we investigated how oxidative injury causes the depletion of energy resources and glutathione synthetase (GSS), which in turn activates 5' AMP-activated protein kinase (AMPK), glycolytic enzymes, and mitochondrial biogenesis, finally resulting in nuclear factor erythroid (NRF) transcription in astrocytes. Both human primary astrocytes incubated with HIV-1 Tat protein in vitro and HIV-inducible Tat (iTat) mice exposed to cocaine showed decreased levels of GSS and increased superoxide dismutase (SOD) levels. These changes, in turn, significantly activated AMPK and raised the concentrations of several glycolytic enzymes, along with oxidative phosphorylation, the mitochondrial biogenesis of peroxisome proliferator-activated receptor-γ coactivator (PGC-1α) and mitochondrial transcription factor (TFAM), and Nrf1 and Nrf2 gene transcription and protein expression. Moreover, neurons exposed to HIV-1Tat/cocaine-conditioned media showed reductions in dendritic formation, spine density, and neuroplasticity compared with control neurons. These results suggest that redox inhibition of GSS altered AMPK activation and mitochondrial biogenesis to influence Nrf transcription. These processes are important components of the astrocyte signaling network regulating brain energy metabolism in HIV-positive cocaine users. In conclusion, HIV-1 Tat alters redox inhibition, thus increasing glycolytic metabolic profiles and mitochondrial biogenesis, leading to Nrf transcription, and ultimately impacting astrocyte energy resource and metabolism. Cocaine exacerbated these effects, leading to a worsening of neurodegeneration.

Opioid and neuroHIV Comorbidity - Current and Future Perspectives

With the current national opioid crisis, it is critical to examine the mechanisms underlying pathophysiologic interactions between human immunodeficiency virus (HIV) and opioids in the central nervous system (CNS). Recent advances in experimental models, methodology, and our understanding of disease processes at the molecular and cellular levels reveal opioid-HIV interactions with increasing clarity. However, despite the substantial new insight, the unique impact of opioids on the severity, progression, and prognosis of neuroHIV and HIV-associated neurocognitive disorders (HAND) are not fully understood. In this review, we explore, in detail, what is currently known about mechanisms underlying opioid interactions with HIV, with emphasis on individual HIV-1-expressed gene products at the molecular, cellular and systems levels. Furthermore, we review preclinical and clinical studies with a focus on key considerations when addressing questions of whether opioid-HIV interactive pathogenesis results in unique structural or functional deficits not seen with either disease alone. These considerations include, understanding the combined consequences of HIV-1 genetic variants, host variants, and μ-opioid receptor (MOR) and HIV chemokine co-receptor interactions on the comorbidity. Lastly, we present topics that need to be considered in the future to better understand the unique contributions of opioids to the pathophysiology of neuroHIV.

Graphical Abstract

Differential Contribution of HIV-1 Subtypes B and C to Neurological Disorders: Mechanisms and Possible Treatments

With the introduction of combinatory antiretroviral therapy, patients infected with human immunodeficiency virus type 1 (HIV-1) can live much longer than before. However, the identification of HIV-associated neurocognitive disorder (HAND), especially HIV-associated dementia in 15-20% of patients infected with HIV-1, indicates additional complexity. These disorders turn out to be subtype dependent. Recently, many studies are ongoing trying to understand how the virus induces neuronal injury which could lead to neurological dysfunction. Most of these studies are focusing on the HIV-1 release of proteins such as Tat. However, the exact role of these proteins and their involvement in neuronal degeneration remains unidentified; this is especially true since viral proteins from different HIV-1 subtypes differ in their ability to cause neuronal damage. This review describes the role of different HIV-1 subtypes, identifies probable pathways involved in neuronal damage, the contribution of different HIV-1 subtypes to the progression of HAND, and potential treatments for HAND.

Executive Dyscontrol of Learning and Memory: Findings from a Clade C HIV-positive South African Sample

OBJECTIVE

Although pre-clinical work suggests there might be differences in neurovirulence across HIV-1 clades, few studies investigate neuropsychological deficits in the globally predominant clade C infection. The purpose of this study was to investigate verbal learning and memory performance in HIV-positive individuals in Cape Town, South Africa, where clade C is the most prevalent subtype of the virus.

METHOD

Using a case-control design, we recruited 53 isiXhosa-speaking, cART-naïve HIV-positive adults and 53 demographically matched HIV-negative controls. Participants were administered a comprehensive neuropsychological test battery. The test of interest was the Hopkins Verbal Learning Test-Revised (HVLT-R); previous studies have used that instrument to identify executive dyscontrol of verbal learning and memory processes in clade B HIV-positive participants.

RESULTS

HIV-positive participants showed only partial impairment on the HVLT-R's learning/memory components (e.g., they recalled significantly fewer words across learning trials, but displayed relatively intact performance on delayed recall trials). They also displayed little executive dyscontrol over encoding and retrieval processes (e.g., there were no significant between-group differences on measures of semantic or serial clustering).

CONCLUSIONS

Post-cART era studies suggest that verbal learning and memory performance is impaired in clade B samples, at least partially due to executive dyscontrol over encoding and retrieval processes. We found few such impairments in the current clade C sample. These preliminary findings suggest different CNS vulnerability across clades that would have implications for delineating clade-specific neuropathological and neurocognitive clinical features.

HIV-1, methamphetamine and astrocytes at neuroinflammatory Crossroads

As a popular psychostimulant, methamphetamine (METH) use leads to long-lasting, strong euphoric effects. While METH abuse is common in the general population, between 10 and 15% of human immunodeficiency virus-1 (HIV-1) patients report having abused METH. METH exacerbates the severity and onset of HIV-1-associated neurocognitive disorders (HAND) through direct and indirect mechanisms. Repetitive METH use impedes adherence to antiretroviral drug regimens, increasing the likelihood of HIV-1 disease progression toward AIDS. METH exposure also directly affects both innate and adaptive immunity, altering lymphocyte numbers and activity, cytokine signaling, phagocytic function and infiltration through the blood brain barrier. Further, METH triggers the dopamine reward pathway and leads to impaired neuronal activity and direct toxicity. Concurrently, METH and HIV-1 alter the neuroimmune balance and induce neuroinflammation, which modulates a wide range of brain functions including neuronal signaling and activity, glial activation, viral infection, oxidative stress, and excitotoxicity. Pathologically, reactive gliosis is a hallmark of both HIV-1- and METH-associated neuroinflammation. Significant commonality exists in the neurotoxic mechanisms for both METH and HAND; however, the pathways dysregulated in astroglia during METH exposure are less clear. Thus, this review highlights alterations in astrocyte intracellular signaling pathways, gene expression and function during METH and HIV-1 comorbidity, with special emphasis on HAND-associated neuroinflammation. Importantly, this review carefully evaluates interventions targeting astrocytes in HAND and METH as potential novel therapeutic approaches. This comprehensive overview indicates, without a doubt, that during HIV-1 infection and METH abuse, a complex dialog between all neural cells is orchestrated through astrocyte regulated neuroinflammation.

HIV-1 subtypes B and C Tat differentially impact synaptic plasticity expression and implicates HIV-associated neurocognitive disorders

Earlier studies have established that infection with HIV-1 subtypes (clades) might differentially influence the neuropathogenesis of HIV-1-associated neurocognitive dysfunction (HAND). HIV-1 Trans activator of transcription protein (Tat) is of considerable significance and plays a major role in the central nervous system (CNS) dysfunction. However, these HIV-1 clades exert diverse cellular effects that leads to neuropathogenic dysfunction has not been well established. We hypothesized that the HIV-1 clade B and clade C Tat proteins effect synaptic plasticity expression in neuroblastoma cells (SK-N-MC) by diverse methods, and accordingly modulates the development of HAND. In the present study, we have analyzed important and highly expressed 84 key human synaptic plasticity genes expression which differentially impact in clade B and clade C Tat treated SK-N-MC cells using RT(2) Profile PCR Array human Synaptic Plasticity kit. Observed results demonstrate that out of 84 key synaptic plasticity genes, 36 and 25 synaptic genes were substantially (≥3 fold) up-regulated and 5 and 5 genes considerably (≥3 fold) down-regulated in clade B and clade C Tat treated cells, respectively, compared to the control SK-N-MC. We have also estimated the levels of glutamine and glutamate in HIV-1 clade B and C Tat exposed SK-N-MC cells compared to untreated cells. Our results indicate that levels of glutamate, glutamine and expression of synaptic plasticity genes were highly dysregulated by HIV-1 clade B Tat compared to clade C Tat in SK-N-MC cells. In summary, this study suggests that clade B Tat substantially potentiates neuronal toxicity and further dysregulated synaptic plasticity genes in SK-N-MC may contribute to the severe neuropathogenesis linked with HAND.

Interactive effects of cocaine on HIV infection: implication in HIV-associated neurocognitive disorder and neuroAIDS

Substantial epidemiological studies suggest that not only, being one of the reasons for the transmission of the human immunodeficiency virus (HIV), but drug abuse also serves its role in determining the disease progression and severity among the HIV infected population. This article focuses on the drug cocaine, and its role in facilitating entry of HIV into the CNS and mechanisms of development of neurologic complications in infected individuals. Cocaine is a powerfully addictive central nervous system stimulating drug, which increases the level of neurotransmitter dopamine (DA) in the brain, by blocking the dopamine transporters (DAT) which is critical for DA homeostasis and neurocognitive function. Tat protein of HIV acts as an allosteric modulator of DAT, where as cocaine acts as reuptake inhibitor. When macrophages in the CNS are exposed to DA, their number increases. These macrophages release inflammatory mediators and neurotoxins, causing chronic neuroinflammation. Cocaine abuse during HIV infection enhances the production of platelet monocyte complexes (PMCs), which may cross transendothelial barrier, and result in HIV-associated neurocognitive disorder (HAND). HAND is characterized by neuroinflammation, including astrogliosis, multinucleated giant cells, and neuronal apoptosis that is linked to progressive virus infection and immune deterioration. Cocaine and viral proteins are capable of eliciting signaling transduction pathways in neurons, involving in mitochondrial membrane potential loss, oxidative stress, activation of JNK, p38, and ERK/MAPK pathways, and results in downstream activation of NF-κB that leads to HAND. Tat-induced inflammation provokes permeability of the blood brain barrier (BBB) in the platelet dependent manner, which can potentially be the reason for progression to HAND during HIV infection. A better understanding on the role of cocaine in HIV infection can give a clue in developing novel therapeutic strategies against HIV-1 infection in cocaine using HIV infected population.

HIV-1 gp120 and morphine induced oxidative stress: role in cell cycle regulation

HIV infection and illicit drugs are known to induce oxidative stress and linked with severity of viral replication, disease progression, impaired cell cycle regulation and neurodegeneration. Studies have shown that morphine accelerates HIV infection and disease progression mediated by Reactive oxygen species (ROS). Oxidative stress impact redox balance and ROS production affect cell cycle regulation. However, the role of morphine in HIV associated acceleration of oxidative stress and its link to cell cycle regulation and neurodegeneration has not been elucidated. The aim of present study is to elucidate the mechanism of oxidative stress induced glutathione synthases (GSS), super oxide dismutase (SOD), and glutathione peroxidase (GPx) impact cell cycle regulated protein cyclin-dependent kinase 1, cell division cycle 2 (CDK-1/CDC-2), cyclin B, and cell division cycle 25C (CDC-25C) influencing neuronal dysfunction by morphine co-morbidity with HIV-1 gp120. It was observed that redox imbalance inhibited the GSS, GPx and increased SOD which, subsequently inhibited CDK-1/CDC-2 whereas cyclin B and CDC-25C significantly up regulated in HIV-1 gp120 with morphine compared to either HIV-1 gp120 or morphine treated alone in human microglial cell line. These results suggest that HIV positive morphine users have increased levels of oxidative stress and effect of cell cycle machinery, which may cause the HIV infection and disease progression.

HIV Subtypes B and C gp120 and Methamphetamine Interaction: Dopaminergic System Implicates Differential Neuronal Toxicity

HIV subtypes or clades differentially induce HIV-associated neurocognitive disorders (HAND) and substance abuse is known to accelerate HIV disease progression. The HIV-1 envelope protein gp120 plays a major role in binding and budding in the central nervous system (CNS) and impacts dopaminergic functions. However, the mechanisms utilized by HIV-1 clades to exert differential effects and the methamphetamine (METH)-associated dopaminergic dysfunction are poorly understood. We hypothesized that clade B and C gp120 structural sequences, modeling based analysis, dopaminergic effect, and METH potentiate neuronal toxicity in astrocytes. We evaluated the effect of clade B and C gp120 and/or METH on the DRD-2, DAT, CaMKs and CREBP transcription. Both the structural sequence and modeling studies demonstrated that clade B gp120 in V1-V4, α -2 and N-glycosylated sites are distinct from clade C gp120. The distinct structure and sequence variation of clade B gp120 differentially impact DRD-2, DAT, CaMK II and CaMK IV mRNA, protein and intracellular expression compared to clade C gp120. However, CREB transcription is upregulated by both clade B and C gp120, and METH co-treatment potentiated these effects. In conclusion, distinct structural sequences of HIV-1 clade B and C gp120 differentially regulate the dopaminergic pathway and METH potentiates neurotoxicity.

The role of arachidonic acid in the regulation of nitric oxide synthase isoforms by HIV gp120 protein in astroglial cells

HIV-associated neurocognitive disorder (HAND) is a common cognitive impairment in AIDS that affects 15 to 50% of adults infected with human immunodeficiency virus (HIV). Excessive amounts of nitric oxide (NO), as produced by inducible NO synthase (iNOS) upon exposure of activated microglia and astrocytes to cytokines and/or viral proteins (e.g., HIV tat and gp120), are assumed to contribute to neuronal abnormalities in HAND. Evidence exists supporting the notion that iNOS induction takes place after an early decline in physiological NO levels (i.e., NO released by constitutive NOS). Here, we demonstrate that HIV-1 gp120 is able to inhibit neuronal NOS through a cytosolic phospholipase A2 (cPLA2)-dependent arachidonic acid (AA) production, this response being critical for allowing activation of the transcriptional factor NF-κB and subsequent iNOS and interleukin-1β transcription in astroglial cells. In this context, AA seems to act as an upstream proinflammatory effector. In view of the pathogenic role of cPLA2 in HAND, a deeper insight into the molecular and cellular mechanisms of its modulation may be helpful in finding new drugs to manage cognitive impairment in HIV-1 patients.

Immunopathogenesis of HIV infection in cocaine users: role of arachidonic acid

Arachidonic acid (AA) is known to be increased in HIV infected patients and illicit drug users are linked with severity of viral replication, disease progression, and impaired immune functions. Studies have shown that cocaine accelerates HIV infection and disease progression mediated by immune cells. Dendritic cells (DC) are the first line of antigen presentation and defense against immune dysfunction. However, the role of cocaine use in HIV associated acceleration of AA secretion and its metabolites on immature dendritic cells (IDC) has not been elucidated yet. The aim of this study is to elucidate the mechanism of AA metabolites cyclooxygenase-2 (COX-2), prostaglandin E2 synthetase (PGE₂), thromboxane A2 receptor (TBXA₂R), cyclopentenone prostaglandins (CyPG), such as 15-deoxy-Δ12,14-PGJ2 (15d-PGJ2), 14-3-3 ζ/δ and 5-lipoxygenase (5-LOX) mediated induction of IDC immune dysfunctions in cocaine using HIV positive patients. The plasma levels of AA, PGE_2, 15d-PGJ2, 14-3-3 ζ/δ and IDC intracellular COX-2 and 5-LOX expression were assessed in cocaine users, HIV positive patients, HIV positive cocaine users and normal subjects. Results showed that plasma concentration levels of AA, PGE₂ and COX-2, TBXA₂R and 5-LOX in IDCs of HIV positive cocaine users were significantly higher whereas 15d-PGJ2 and 14-3-3 ζ/δ were significantly reduced compared to either HIV positive subjects or cocaine users alone. This report demonstrates that AA metabolites are capable of mediating the accelerative effects of cocaine on HIV infection and disease progression.

HIV clades B and C are associated with reduced brain volumetrics

The human immunodeficiency virus (HIV) has multiple genetic clades with varying prevalence throughout the world. Both HIV clade C (HIV-C) and HIV clade B (HIV-B) can cause cognitive impairment, but it is unclear if these clades are characterized by similar patterns of brain dysfunction. We examined brain volumetrics and neuropsychological performance among highly active antiretroviral therapy (HAART)-naïve HIV-B and HIV-C participants. Thirty-four HAART-naïve HIV-infected (HIV+) participants [17 HIV-B (USA); 17 HIV-C (South Africa)] and 34 age- and education-matched HIV-uninfected (HIV−) participants were evaluated. All participants underwent similar laboratory, neuropsychological, and neuroimaging studies. Brain volume measures were assessed within the caudate, putamen, amygdala, thalamus, hippocampus, corpus callosum, and cortical (gray and white matter) structures. A linear model that included HIV status, region, and their interaction assessed the effects of the virus on brain volumetrics. HIV− and HIV+ individuals were similar in age. On laboratory examination, HIV-C participants had lower CD4 cell counts and higher plasma HIV viral loads than HIV-B individuals. In general, HIV+ participants performed significantly worse on neuropsychological measures of processing speed and memory and had significantly smaller relative volumetrics within the thalamus, hippocampus, corpus callosum, and cortical gray and white matter compared to the respective HIV− controls. Both HIV-B and HIV-C are associated with similar volumetric declines when compared to matched HIV− controls. HIV-B and HIV-C were associated with significant reductions in brain volumetrics and poorer neuropsychological performance; however, no specific effect of HIV clade subtype was evident. These findings suggest that HIV-B and HIV-C both detrimentally affect brain integrity.

Effect of HIV clade differences on the onset and severity of HIV-associated neurocognitive disorders

The effects of evolutionary pressure on human immunodeficiency virus-1 (HIV) have resulted in a variety of clades and recombinants. The functional implications of HIV clades on disease onset and progression of HIV-associated neurocognitive disorders (HAND) have been suggested by clinical and basic science studies, which will be reviewed in detail. Some clinical studies suggest that patients infected with clade D show the greatest propensity for developing HIV-associated dementia (HAD) followed by clades B, C, and A, respectively. However, there are conflicting reports. This review summarizes clinical studies that have assessed behavioral abnormalities and HIV clade type in HAND patients, focusing on the clades stated above. The limitations include variations in testing used to define the cohorts, patient sample size, lack of HIV clade characterization, combination antiretroviral therapy (cART) availability, and other factors, which are highlighted and compared between clinical studies performed primarily in Africa and India. Basic science studies provide substantial evidence that HIV clade differences can result in varying degrees of neuropathology and are also reviewed in some detail. These studies indicate that there are a number of clade differences, most notably in Tat, that result in different degrees of neurovirulence or neuropathological effects in vitro and in a mouse model of HAND. In order to confirm the hypothesis that HIV clade differences are important determinants of HAND pathogenesis, larger, longitudinal studies that employ standard definitions of HAND and HIV clade testing must be performed. In a larger sense, HAND continues to be highly prevalent despite the advent of cART, and therefore, further studies into HAND pathogenesis are critical to develop better therapies.

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.

Neuroimaging markers of human immunodeficiency virus infection in South Africa

Previous studies have reported cognitive deficits among HIV-positive individuals infected with clade C virus. However, no study has examined whether individuals predominately infected with clade C virus exhibit brain atrophy relative to healthy controls. This study examined volumetric differences between 28 HIV+ individuals and 23 HIV- controls from South Africa. Volumetric measures were obtained from six regions of interest -- caudate, thalamus, corpus callosum, total cortex, total gray matter, and total white matter. HIV+ participants had significantly lower volumes in the total white matter (p<0.01), thalamus (p<0.01) and total gray matter (inclusive of cortical and subcortical regions, p<0.01). This study is the first to provide evidence of brain atrophy among HIV+ individuals in South Africa, where HIV clade C predominates. Additional research that integrates neuroimaging, comprehensive neuropsychological testing, genetic variance in clade-specific proteins, and the impact of treatment with Antiretrovirals (ARV) are necessary to understand the development of HIV-related neurocognitive disorders in South Africa.

Interactions between prostaglandins, leukotrienes and HIV-1: possible implications for the central nervous system

In HIV-1-infected individuals, there is often discordance between viremia in peripheral blood and viral load found in the central nervous system (CNS). Although the viral burden is often lower in the CNS compartment than in the plasma, neuroinflammation is present in most infected individuals, albeit attenuated by the current combined antiretroviral therapy. The HIV-1-associated neurological complications are thought to result not only from direct viral replication, but also from the subsequent neuroinflammatory processes. The eicosanoids - prostanoids and leukotrienes - are known as potent inflammatory lipid mediators. They are often present in neuroinflammatory diseases, notably HIV-1 infection. Their exact modulatory role in HIV-1 infection is, however, still poorly understood, especially in the CNS compartment. Nonetheless, a handful of studies have provided evidence as to how these lipid mediators can modulate HIV-1 infection. This review summarizes findings indicating how eicosanoids may influence the progression of neuroAIDS.