CSF antiretroviral drug penetrance and the treatment of HIV-associated psychomotor slowing

Cocaine regulates antiretroviral therapy CNS access through pregnane-x receptor-mediated drug transporter and metabolizing enzyme modulation at the blood brain barrier

BACKGROUND

Appropriate interactions between antiretroviral therapies (ART) and drug transporters and metabolizing enzymes at the blood brain barrier (BBB) are critical to ensure adequate dosing of the brain to achieve HIV suppression. These proteins are modulated by demographic and lifestyle factors, including substance use. While understudied, illicit substances share drug transport and metabolism pathways with ART, increasing the potential for adverse drug:drug interactions. This is particularly important when considering the brain as it is relatively undertreated compared to peripheral organs and is vulnerable to substance use-mediated damage.

METHODS

We used an in vitro model of the human BBB to determine the extravasation of three first-line ART drugs, emtricitabine (FTC), tenofovir (TFV), and dolutegravir (DTG), in the presence and absence of cocaine, which served as our illicit substance model. The impact of cocaine on BBB integrity and permeability, drug transporters, metabolizing enzymes, and their master transcriptional regulators were evaluated to determine the mechanisms by which substance use impacted ART central nervous system (CNS) availability.

RESULTS

We determined that cocaine had a selective impact on ART extravasation, where it increased FTC's ability to cross the BBB while decreasing TFV. DTG concentrations that passed the BBB were below quantifiable limits. Interestingly, the potent neuroinflammatory modulator, lipopolysaccharide, had no effect on ART transport, suggesting a specificity for cocaine. Unexpectedly, cocaine did not breach the BBB, as permeability to albumin and 4 kDa FITC-dextran, as well as tight junction proteins and adhesion molecules remained unchanged. Rather, cocaine selectively decreased the pregnane-x receptor (PXR), but not constitutive androstane receptor (CAR). Consequently, drug transporter expression and activity decreased in endothelial cells of the BBB, including p-glycoprotein (P-gp), breast cancer resistance protein (BCRP), and multidrug resistance-associated protein 4 (MRP4). Further, cytochrome P450 3A4 (CYP3A4) enzymatic activity increased following cocaine treatment that coincided with decreased expression. Finally, cocaine modulated adenylate kinases that are required to facilitate biotransformation of ART prodrugs to their phosphorylated, pharmacologically active counterparts.

CONCLUSION

Our findings indicate that additional considerations are needed in CNS HIV treatment strategies for people who use cocaine, as it may limit ART efficacy through regulation of drug transport and metabolizing pathways at the BBB.

Cocaine Regulates Antiretroviral Therapy CNS Access Through Pregnane-X Receptor-Mediated Drug Transporter and Metabolizing Enzyme Modulation at the Blood Brain Barrier

Background

Appropriate interactions between antiretroviral therapies (ART) and drug transporters and metabolizing enzymes at the blood brain barrier (BBB) are critical to ensure adequate dosing of the brain to achieve HIV suppression. These proteins are modulated by demographic and lifestyle factors, including substance use. While understudied, illicit substances share drug transport and metabolism pathways with ART, increasing the potential for adverse drug:drug interactions. This is particularly important when considering the brain as it is relatively undertreated compared to peripheral organs and is vulnerable to substance use-mediated damage.

Methods

We used an in vitro model of the human BBB to determine the extravasation of three first-line ART drugs, emtricitabine (FTC), tenofovir (TFV), and dolutegravir (DTG), in the presence and absence of cocaine, which served as our illicit substance model. The impact of cocaine on BBB integrity and permeability, drug transporters, metabolizing enzymes, and their master transcriptional regulators were evaluated to determine the mechanisms by which substance use impacted ART central nervous system (CNS) availability.

Results

We determined that cocaine had a selective impact on ART extravasation, where it increased FTC's ability to cross the BBB while decreasing TFV. DTG concentrations that passed the BBB were below quantifiable limits. Interestingly, the potent neuroinflammatory modulator, lipopolysaccharide, had no effect on ART transport, suggesting a specificity for cocaine. Unexpectedly, cocaine did not breach the BBB, as permeability to albumin and tight junction proteins and adhesion molecules remained unchanged. Rather, cocaine selectively decreased the pregnane-x receptor (PXR), but not constitutive androstane receptor (CAR). Consequently, drug transporter expression and activity decreased in endothelial cells of the BBB, including p-glycoprotein (P-gp), breast cancer resistance protein (BCRP), and multidrug resistance-associated protein 4 (MRP4). Further, cytochrome P450 3A4 (CYP3A4) enzymatic activity increased following cocaine treatment that coincided with decreased expression. Finally, cocaine modulated adenylate kinases are required to facilitate biotransformation of ART prodrugs to their phosphorylated, pharmacologically active counterparts.

Conclusion

Our findings indicate that additional considerations are needed in CNS HIV treatment strategies for people who use cocaine, as it may limit ART efficacy through regulation of drug transport and metabolizing pathways at the BBB.

Cognitive Assessment of Young Adults Before and After Initiation of Combination Antiretroviral Therapy

Objective

In the determination and monitoring of neurocognitive disorders in human immunodeficiency virus (HIV)-positive individuals, there is a need for significantly more practical methods which provide results in a shorter time than the tests that require challenging and specialized expertise. This study aimed to evaluate cognitive functions and the factors affecting them in naïve HIV-positive patients using by Montreal Cognitive Assessment (MoCA) test before and after the initiation of combination antiretroviral therapy.

Materials and Methods

HIV-positive, treatment-naïve patients monitored between January-June 2017 were included in the study. The MoCA test was performed at the beginning and the sixth month of the treatment.

Results

Forty male patients were included in the study. The mean age was calculated as 29.1±4.0. When the factors affecting the MoCA score were examined, there was a significant relationship between the education level and the MoCA score. Smoking, using alcohol, and substance did not have a significant impact on baseline MoCA values. A significant correlation was found between cluster differentiation 4 (CD4) count and HIV RNA level and attention function. There was a significant increase in the total MoCA score and the MoCA subgroup scores at the end of the sixth month of the treatment.

Conclusion

MoCA test is one of the most practical tests that can be applied in a short time period, and it was found useful in evaluating the changes in the cognitive functions of HIV-positive patients during antiretroviral treatment.

HIV Antiretroviral Medication Neuropenetrance and Neurocognitive Outcomes in HIV+ Adults: A Review of the Literature Examining the Central Nervous System Penetration Effectiveness Score

This literature review summarizes the existing research examining the CNS penetration effectiveness (CPE) score and neurocognitive outcomes (i.e., neuropsychological assessment and neurocognitive screening) in HIV+ individuals. Despite the effectiveness of Combined Antiretroviral Therapy (CART) in reducing mortality and morbidity in HIV and controlling viral replication, HIV often persists in the Central Nervous System (CNS), and rates of neurocognitive impairment remain higher than predicted in the post-CART era. The CPE score was developed to rank antiretroviral regimens on their ability to penetrate the CNS and potency in inhibiting the virus, and it has been examined in relation to neurocognitive functioning for over a decade. Based on the results of 23 studies, we conclude that CPE is not as strongly associated with neurocognitive outcomes as initially hypothesized, although higher CPE ARV regimens may be associated with modest, improved outcomes in global neurocognitive functioning, and to a lesser extent attention/working memory and learning/memory. Conclusions, however, are limited by the heterogeneity in study design and methods, and the lack of a more recent CPE metric update. It is recommended that future research in this area employ comprehensive, standardized neuropsychological test batteries and examine domain-level performance, and use the newer 2010 CPE metric, although an updated CPE ranking is urgently needed.

Druggable targets of the endocannabinoid system: Implications for the treatment of HIV-associated neurocognitive disorder

HIV-associated neurocognitive disorder (HAND) affects nearly half of all HIV-infected individuals. Synaptodendritic damage correlates with neurocognitive decline in HAND, and many studies have demonstrated that HIV-induced neuronal injury results from excitotoxic and inflammatory mechanisms. The endocannabinoid (eCB) system provides on-demand protection against excitotoxicity and neuroinflammation. Here, we discuss evidence of the neuroprotective and anti-inflammatory properties of the eCB system from in vitro and in vivo studies. We examine the pharmacology of the eCB system and evaluate the therapeutic potential of drugs that modulate eCB signaling to treat HAND. Finally, we provide perspective on the need for additional studies to clarify the role of the eCB system in HIV neurotoxicity and speculate that strategies that enhance eCB signaling might slow cognitive decline in HAND.

Endothelins in inflammatory neurological diseases

Endothelins were discovered more than thirty years ago as potent vasoactive compounds. Beyond their well-documented cardiovascular properties, however, the contributions of the endothelin pathway have been demonstrated in several neuroinflammatory processes and the peptides have been reported as clinically relevant biomarkers in neurodegenerative diseases. Several studies report that endothelin-1 significantly contributes to the progression of neuroinflammatory processes, particularly during infections in the central nervous system (CNS), and is associated with a loss of endothelial integrity at the blood brain barrier level. Because of the paucity of clinical trials with endothelin-1 antagonists in several infectious and non-infectious neuroinflammatory diseases, it remains an open question whether the 21 amino acid peptide is a mediator/modulator rather than a biomarker of the progression of neurodegeneration. This review focuses on the potential roles of endothelins in the pathology of neuroinflammatory processes, including infectious diseases of viral, bacterial or parasitic origin in which the synthesis of endothelins or its pharmacology have been investigated from the cell to the bedside in several cases, as well as in non-infectious inflammatory processes such as neurodegenerative disorders like Alzheimers Disease or central nervous system vasculitis.

Neuropathogenesis of human immunodeficiency virus infection

Human immunodeficiency virus (HIV)-associated neurocognitive disorders (HAND) remain a common end-organ manifestation of viral infection. Subclinical and mild symptoms lead to neurocognitive and behavioral abnormalities. These are associated, in part, with viral penetrance and persistence in the central nervous system. Infections of peripheral blood monocytes, macrophages, and microglia are the primary drivers of neuroinflammation and neuronal impairments. While current antiretroviral therapy (ART) has reduced the incidence of HIV-associated dementia, milder forms of HAND continue. Depression, comorbid conditions such as infectious liver disease, drugs of abuse, antiretroviral drugs themselves, age-related neurodegenerative diseases, gastrointestinal maladies, and concurrent social and economic issues can make accurate diagnosis of HAND challenging. Increased life expectancy as a result of ART clearly creates this variety of comorbid conditions that often blur the link between the virus and disease. With the discovery of novel biomarkers, neuropsychologic testing, and imaging techniques to better diagnose HAND, the emergence of brain-penetrant ART, adjunctive therapies, longer life expectancy, and better understanding of disease pathogenesis, disease elimination is perhaps a realistic possibility. This review focuses on HIV-associated disease pathobiology with an eye towards changing trends in the face of widespread availability of ART.

Cortical brain atrophy and intra-individual variability in neuropsychological test performance in HIV disease

To characterize the relationship between dispersion-based intra-individual variability (IIVd) in neuropsychological test performance and brain volume among HIV seropositive and seronegative men and to determine the effects of cardiovascular risk and HIV infection on this relationship. Magnetic Resonance Imaging (MRI) was used to acquire high-resolution neuroanatomic data from 147 men age 50 and over, including 80 HIV seropositive (HIV+) and 67 seronegative controls (HIV-) in this cross-sectional cohort study. Voxel Based Morphometry was used to derive volumetric measurements at the level of the individual voxel. These brain structure maps were analyzed using Statistical Parametric Mapping (SPM2). IIVd was measured by computing intra-individual standard deviations (ISD's) from the standardized performance scores of five neuropsychological tests: Wechsler Memory Scale-III Visual Reproduction I and II, Logical Memory I and II, Wechsler Adult Intelligence Scale-III Letter Number Sequencing. Total gray matter (GM) volume was inversely associated with IIVd. Among all subjects, IIVd -related GM atrophy was observed primarily in: 1) the inferior frontal gyrus bilaterally, the left inferior temporal gyrus extending to the supramarginal gyrus, spanning the lateral sulcus; 2) the right superior parietal lobule and intraparietal sulcus; and, 3) dorsal/ventral regions of the posterior section of the transverse temporal gyrus. HIV status, biological, and cardiovascular disease (CVD) variables were not linked to IIVd -related GM atrophy. IIVd in neuropsychological test performance may be a sensitive marker of cortical integrity in older adults, regardless of HIV infection status or CVD risk factors, and degree of intra-individual variability links with volume loss in specific cortical regions; independent of mean-level performance on neuropsychological tests.

Changing clinical phenotypes of HIV-associated neurocognitive disorders

HIV-associated neurocognitive disorder (HAND) remains a common cause of cognitive impairment and persists in 15-55% of HIV+ individuals in the combination antiretroviral therapy (CART) era. CART is now the primary treatment for HAND, but it is effective in only a subset of patients. In the pre-CART era, HIV-associated dementia was the most common form of HAND. However, in CART-treated patients, the prevalence of HIV-associated dementia has declined substantially, and milder stages of HAND, i.e., ANI and MND predominate. HIV+ patients with mild neurocognitive disorder (MND) can still have significant functional impairment in some activities of daily living. There have been several other significant changes in the clinical features of HAND in the CART era. The mean survival for an individual diagnosed with HIV dementia has increased dramatically. In HIV+ individuals on CART with a suppressed systemic viral load, the majority of individuals with HAND remain stable, with a small proportion showing deterioration. Extrapyramidal signs are now less common in patients with HAND on CART. In the CART era, HAND may have a mixed pattern of both cortical and subcortical features with greater deficits in executive functioning and working memory. Despite the milder clinical phenotype, in the CART era, patients with HAND still have persistent laboratory and neuroimaging abnormalities in the central nervous system even with systemic viral suppression. As the HIV+ patient population ages, cerebrovascular disease risk factors such as hypertension, diabetes, and hypercholesterolemia are increasingly recognized as risk factors for cognitive impairment in HIV+ patients on CART. HAND remains a common neurological condition globally in the CART era, necessitating the need for new animal models to examine pathogenesis and potential treatments for HAND.

Association of midlife smoking status with change in processing speed and mental flexibility among HIV-seropositive and HIV-seronegative older men: the Multicenter AIDS Cohort Study

Smoking is a potential risk factor for age-related cognitive decline. To date, no study has examined the association between smoking and cognitive decline in men living with human immunodeficiency virus (HIV). The aim of this present study is to examine whether smoking status and severity in midlife is associated with a rate of decline in cognitive processing speed among older HIV-seropositive and HIV-seronegative men who have sex with men. Data from 591 older HIV-seropositive and HIV-seronegative men who have sex with men from the Multicenter AIDS Cohort Study were examined. All participants had information on smoking history collected before age 50 years and at least 5 years of follow-up after age 50. Smoking history was categorized as never smoker, former smoker, and current smoker and cumulative pack years was calculated. The raw scores of three neuropsychological tests (Trail Making A, Trail Making B, and Symbol Digit Modalities tests) were log transformed (Trail Making A and B) and used in linear mixed models to determine associations between smoking history and at least subsequent 5-year decline in cognitive processing speed. There were no significant differences in the rates of neurological decline among never smokers, former smokers, and current smokers. Findings were similar among HIV-seropositive participants. However, an increase of 5 pack-years was statistically significantly associated with a greater rate of decline in the Trail Making Test B score and Composite Score (β -0.0250 [95% CI, -0.0095 to -0.0006] and -0.0077 [95% CI, -0.0153 to -0.0002], respectively). We found no significant association between smoking treated as a categorical variable (never smoked, former smoker, or current smoker) and a small change in every increase of 5 pack-years on measures of psychomotor speed and cognitive flexibility. To optimize healthy aging, interventions for smoking cessation should be tailored to men who have sex with men.

Synaptic Plasticity and Neurological Disorders in Neurotropic Viral Infections

Based on the type of cells or tissues they tend to harbor or attack, many of the viruses are characterized. But, in case of neurotropic viruses, it is not possible to classify them based on their tropism because many of them are not primarily neurotropic. While rabies and poliovirus are considered as strictly neurotropic, other neurotropic viruses involve nervous tissue only secondarily. Since the AIDS pandemic, the interest in neurotropic viral infections has become essential for all clinical neurologists. Although these neurotropic viruses are able to be harbored in or infect the nervous system, not all the neurotropic viruses have been reported to cause disrupted synaptic plasticity and impaired cognitive functions. In this review, we have discussed the neurotropic viruses, which play a major role in altered synaptic plasticity and neurological disorders.

Intra-ventral tegmental area HIV-1 Tat1-86 attenuates nicotine-mediated locomotor sensitization and alters mesocorticolimbic ERK and CREB signaling in rats

Cigarette smoking prevalence in the HIV-positive individuals is profoundly higher than that in the HIV-negative individuals. We have demonstrated that HIV-1 transgenic rats exhibit attenuated nicotine-mediated locomotor activity, altered cAMP response element binding protein (CREB) and extracellular regulated kinase (ERK1/2) signaling in the mesocorticolimbic regions. This study investigated the role of HIV-1 transactivator of transcription (Tat) protein in the alterations of nicotine-mediated behavior and the signaling pathway observed in the HIV-1 transgenic rats. Rats received bilateral microinjection of recombinant Tat1-86 (25 μg/side) or vehicle directed at ventral tegmental area (VTA) followed by locomotor testing in response to 13 daily intravenous injections of nicotine (0.05 mg/kg, freebase, once/day) or saline. Further, we examined the phosphorylated levels of CREB (pCREB) and ERK1/2 (pERK1/2) in the prefrontal cortex (PFC), nucleus accumbens (NAc) and VTA. Tat diminished baseline activity in saline control rats, and attenuated nicotine-induced behavioral sensitization. Following repeated saline injection, the basal levels of pERK1 in the NAc and VTA and pERK2 in VTA were lower in the vehicle control group, relative to the Tat group. After repeated nicotine injection, pERK1 in NAc and VTA and pERK2 in VTA were increased in the vehicle group, but not in the Tat group. Moreover, repeated nicotine injections decreased pCREB in the PFC and VTA in the Tat group but not in the vehicle group. Thus, these findings indicate that the direct injection of Tat at the VTA may mediate CREB and ERK activity in response to nicotine-induced locomotor activity.

Emergence of CD4 independence envelopes and astrocyte infection in R5 simian-human immunodeficiency virus model of encephalitis

Human immunodeficiency virus type 1 (HIV-1) infection in the central nervous system (CNS) is characterized by replication in macrophages or brain microglia that express low levels of the CD4 receptor and is the cause of HIV-associated dementia and related cognitive and motor disorders that affect 20 to 30% of treatment-naive patients with AIDS. Independent viral envelope evolution in the brain has been reported, with the need for robust replication in resident CD4(low) cells, as well as CD4-negative cells, such as astrocytes, proposed as a major selective pressure. We previously reported giant-cell encephalitis in subtype B and C R5 simian-human immunodeficiency virus (SHIV)-infected macaques (SHIV-induced encephalitis [SHIVE]) that experienced very high chronic viral loads and progressed rapidly to AIDS, with varying degrees of macrophage or microglia infection and activation of these immune cells, as well as astrocytes, in the CNS. In this study, we characterized envelopes (Env) amplified from the brains of subtype B and C R5 SHIVE macaques. We obtained data in support of an association between severe neuropathological changes, robust macrophage and microglia infection, and evolution to CD4 independence. Moreover, the degree of Env CD4 independence appeared to correlate with the extent of astrocyte infection in vivo. These findings further our knowledge of the CNS viral population phenotypes that are associated with the severity of HIV/SHIV-induced neurological injury and improve our understanding of the mechanism of HIV-1 cellular tropism and persistence in the brain.

IMPORTANCE

Human immunodeficiency virus type 1 (HIV-1) infection of astrocytes in the brain has been suggested to be important in HIV persistence and neuropathogenesis but has not been definitively demonstrated in an animal model of HIV-induced encephalitis (HIVE). Here, we describe a new nonhuman primate (NHP) model of R5 simian-human immunodeficiency virus (SHIV)-induced encephalitis (SHIVE) with several classical HIVE features that include astrocyte infection. We further show an association between severe neuropathological changes, robust resident microglia infection, and evolution to CD4 independence of viruses in the central nervous system (CNS), with expansion to infection of truly CD4-negative cells in vivo. These findings support the use of the R5 SHIVE models to study the contribution of the HIV envelope and viral clades to neurovirulence and residual virus replication in the CNS, providing information that should guide efforts to eradicate HIV from the body.

Pattern of neurocognitive function in patients receiving boosted protease inhibitor monotherapy: a detailed neuropsychological study

It is unknown if, compared to a triple drug antiretroviral therapy, boosted protease inhibitor monotherapy leads to worse results in specific neuropsychological processes. In our study, we included patients virologically suppressed (≥1 year), on antiretroviral therapy, without concomitant major neurocognitive confounders, receiving boosted lopinavir or darunavir as monotherapy (n = 96) or as triple therapy with two nucleoside reverse transcriptase inhibitors (n = 95). All patients underwent a comprehensive neuropsychological test battery (14 neuropsychological measures, covering seven domains). Both groups were compared in average score distributions and rates of neuropsychological deficits. Similar comparisons were conducted only for patients with neurocognitive impairment. In the adjusted analysis, we found only small differences between groups in the entire sample: better verbal learning (p = 0.02; d = 0.28) and verbal recall scores (p < 0.01; d = 0.25) in patients on boosted protease inhibitor monotherapy and slightly better motor skills with dominant hand (p = 0.02; d = 0.23) scores in patients on triple therapy. No greater proportion of deficits in the protease inhibitor monotherapy group was found in any neuropsychological measure. In neurocognitively impaired patients, we found similar outcomes in verbal learning, verbal recall, and motor skills with dominant hand but with larger effect sizes. Close similarities in the neurocognitive pattern between groups question the clinical relevance of the number of neuroactive drugs included in the regimen. These results also suggest that peripheral viral load control may be a good indicator of brain protection.

NeuroHIV and use of addictive substances

In the past three decades, substance abuse has been identified as a key comorbidity of human immunodeficiency virus-1 (HIV-1) infection. Many studies have found that the use and abuse of addictive substances hastens the progression of HIV-1 infection and HIV-associated neurocognitive disorders. Advances in highly active antiretroviral therapy (HAART) in the mid-1990s have been successful in limiting the HIV-1 viral load and maintaining a relatively healthy immune response, allowing the life expectancy of patients infected with HIV to approach that of the general population. However, even with HAART, HIV-1 viral proteins are still expressed and eradication of the virus, particularly in the brain, the key reservoir organ, does not occur. In the post-HAART era, the clinical challenge in the treatment of HIV infection is inflammation of the central nervous system (CNS) and its subsequent neurological disorders. To date, various explicit and implicit connections have been identified between the neuronal circuitry involved in immune responses and brain regions affected by and implicated in substance abuse. This chapter discusses past and current medical uses of prototypical substances of abuse, including morphine, alcohol, cocaine, methamphetamine, marijuana, and nicotine, and the evidence that systemic infections, particularly HIV-1 infection, cause neurological dysfunction as a result of inflammation in the CNS, which can increase the risk of substance abuse.

Cognitive impairment and antiretroviral treatment in a Peruvian population of patients with human immunodeficiency virus

BACKGROUND

HIV-associated cognitive impairment occurs even in the early stages of infection. Short-term memory, psychomotor speed, attention, and executive functioning are the main capacities affected. Controversy exists regarding whether highly active antiretroviral therapy (HAART) is helpful in combating this process. The objective of the present study is to determine the association between cognitive impairment and HAART in HIV-infected patients from Hospital Regional de Huacho.

METHODS

Prospective study of HIV patients meeting criteria to start HAART. Twenty-one HIV-positive patients were recruited between April and July 2011. Researchers administered a standardised neuropsychological test battery before and 4 weeks after onset of HAART. Psychomotor speed, executive function, short term memory (visual and verbal), attention, and visuospatial performance were evaluated.

RESULTS

Nineteen patients completed the study (14 males and 5 females). In the pre-HAART evaluation, most patients scored below average on the executive function and psychomotor speed subtests. Psychomotor speed and immediate visual memory improved significantly after four months of treatment with HAART.

CONCLUSIONS

Some degree of cognitive decline may present even in the early and asymptomatic stages of HIV infection. The benefits of antiretroviral treatment for cognitive performance can be detected after only a few weeks of follow-up.

Human synaptic plasticity gene expression profile and dendritic spine density changes in HIV-infected human CNS cells: role in HIV-associated neurocognitive disorders (HAND)

HIV-associated neurocognitive disorders (HAND) is characterized by development of cognitive, behavioral and motor abnormalities, and occur in approximately 50% of HIV infected individuals. Our current understanding of HAND emanates mainly from HIV-1 subtype B (clade B), which is prevalent in USA and Western countries. However very little information is available on neuropathogenesis of HIV-1 subtype C (clade C) that exists in Sub-Saharan Africa and Asia. Therefore, studies to identify specific neuropathogenic mechanisms associated with HAND are worth pursuing to dissect the mechanisms underlying this modulation and to prevent HAND particularly in clade B infection. In this study, we have investigated 84 key human synaptic plasticity genes differential expression profile in clade B and clade C infected primary human astrocytes by using RT(2) Profile PCR Array human Synaptic Plasticity kit. Among these, 31 and 21 synaptic genes were significantly (≥3 fold) down-regulated and 5 genes were significantly (≥3 fold) up-regulated in clade B and clade C infected cells, respectively compared to the uninfected control astrocytes. In flow-cytometry analysis, down-regulation of postsynaptic density and dendrite spine morphology regulatory proteins (ARC, NMDAR1 and GRM1) was confirmed in both clade B and C infected primary human astrocytes and SK-N-MC neuroblastoma cells. Further, spine density and dendrite morphology changes by confocal microscopic analysis indicates significantly decreased spine density, loss of spines and decreased dendrite diameter, total dendrite and spine area in clade B infected SK-N-MC neuroblastoma cells compared to uninfected and clade C infected cells. We have also observed that, in clade B infected astrocytes, induction of apoptosis was significantly higher than in the clade C infected astrocytes. In conclusion, this study suggests that down-regulation of synaptic plasticity genes, decreased dendritic spine density and induction of apoptosis in astrocytes may contribute to the severe neuropathogenesis in clade B infection.

Cognitive neurorehabilitation of HIV-associated neurocognitive disorders: a qualitative review and call to action

Despite significant advances in the virologic management of HIV infection over the last two decades, effective treatments for HIV-associated neurocognitive disorders (HAND) remain elusive. While pharmacological interventions have yielded some success in improving neurocognitive outcomes in HIV, there is a dearth of rigorous studies examining the efficacy of cognitive rehabilitation for remediating HIV-associated neurocognitive impairment. This qualitative review summarizes and critiques the emerging literature on cognitive and behavioral treatments for HAND, which provides many reasons for optimism, but also has major limitations that underscore the scope of the work that lies ahead. Considering the notable real-world consequences of HAND, the development, validation, and clinical deployment of cognitive neurorehabilitation interventions tailored to the needs of persons living with HIV infection is a priority for clinical neuroAIDS investigators. In describing potential future directions for this endeavor, particular attention was paid to the application of cognitive neuropsychological principles in developing theory-driven approaches to managing HAND, improving everyday functioning, and enhancing HIV health outcomes.

Successful treatment of Epstein-Barr virus encephalitis in the setting of HIV-associated neurocognitive disorder: a diagnostic and therapeutic challenge

We report a challenging case of HIV-associated neurocognitive disorder with superimposed Epstein-Barr virus (EBV) encephalitis. The patient presented with an abnormal MRI brain scan, and EBV DNA that was detected in the cerebrospinal fluid and brain biopsy, which also demonstrated histopathological findings consistent with the diagnosis. This occurred on the background of a 12-month period of gradual cognitive decrease secondary to HIV-associated dementia. Invasive testing was required to reach the diagnosis in this case, highlighting the importance of thorough investigation of neurological impairment in HIV-positive patients. Clinicopathological recovery was achieved through optimization of antiretroviral therapy and use of valganciclovir.

Virological Response in Cerebrospinal Fluid to Antiretroviral Therapy in a Large Italian Cohort of HIV-Infected Patients with Neurological Disorders

The aim of the present study was to analyse the effect of antiretroviral (ARV) therapy and single antiretroviral drugs on cerebrospinal fluid (CSF) HIV-RNA burden in HIV-infected patients affected by neurological disorders enrolled in a multicentric Italian cohort. ARVs were considered “neuroactive” from literature reports. Three hundred sixty-three HIV-positive patients with available data from paired plasma and CSF samples, were selected. One hundred twenty patients (33.1%) were taking ARVs at diagnosis of neurological disorder. Mean CSF HIV-RNA was significantly higher in naïve than in experienced patients, and in patients not taking ARV than in those on ARV. A linear correlation between CSF HIV-RNA levels and number of neuroactive drugs included in the regimen was also found (r = −0.44, P < 0.001). Low -plasma HIV-RNA and the lack of neurocognitive impairment resulted in independently associated to undetectable HIV-RNA. Taking nevirapine or efavirenz, or regimen including NNRTI, NNRTI plus PI or boosted PI, was independently associated to an increased probability to have undetectable HIV-RNA in CSF. The inclusion of two or three neuroactive drugs in the ARV regimen was independently associated to undetectable viral load in CSF. Our data could be helpful in identifying ARV regimens able to better control HIV replication in the CNS sanctuary, and could be a historical reference for further analyses.

Neurocognitive impairment in HIV-infected naïve patients with advanced disease: the role of virus and intrathecal immune activation

Objective. To investigate intrathecal immune activation parameters and HIV-RNA in HIV-associated neurocognitive disorders (HAND) of advanced naïve HIV-infected patients and to evaluate their dynamics before and after initiation of antiretroviral therapy (ART). Methods. Cross-sectional and longitudinal analysis of HIV RNA, proinflammatory cytokines (IL-6, IL-10, INF-γ, TNF-α, TGF-β1, and TGF-β2) and chemokines (MIP-1α, MIP-1β, and MCP-1) in plasma and cerebrospinal fluid (CSF) of HIV-infected patients with CD4 <200/μL. Results. HAND was diagnosed at baseline in 6/12 patients. Baseline CSF HIV-RNA was comparable in patients with or without HAND, whereas CSF concentration of IL-6 and MIP-1β, proinflammatory cytokines, was increased in HAND patients. CSF evaluation at 12 weeks was available in 10/12 cases. ART greatly reduced HIV-RNA in all patients. Nevertheless, IL-6 and MIP-1β remained elevated after 12 weeks of therapy in HAND patients, in whom CSF HIV RNA decay was slower than the plasmatic one as well. Conclusion. Immune activation, as indicated by inflammatory cytokines, but not higher levels of HIV-RNA is observed in advanced naïve HIV-infected patients with HAND. In HAND patients, ART introduction resulted in a less rapid clearance of CSF viremia compared to plasma and no modifications of intratechal immune activation.

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.

Central nervous system antiretroviral efficacy in HIV infection: a qualitative and quantitative review and implications for future research

Background

There is conflicting information as to whether antiretroviral drugs with better central nervous system (CNS) penetration (neuroHAART) assist in improving neurocognitive function and suppressing cerebrospinal fluid (CSF) HIV RNA. The current review aims to better synthesise existing literature by using an innovative two-phase review approach (qualitative and quantitative) to overcome methodological differences between studies.

Methods

Sixteen studies, all observational, were identified using a standard citation search. They fulfilled the following inclusion criteria: conducted in the HAART era; sample size > 10; treatment effect involved more than one antiretroviral and none had a retrospective design. The qualitative phase of review of these studies consisted of (i) a blind assessment rating studies on features such as sample size, statistical methods and definitions of neuroHAART, and (ii) a non-blind assessment of the sensitivity of the neuropsychological methods to HIV-associated neurocognitive disorder (HAND). During quantitative evaluation we assessed the statistical power of studies, which achieved a high rating in the qualitative analysis. The objective of the power analysis was to determine the studies ability to assess their proposed research aims.

Results

After studies with at least three limitations were excluded in the qualitative phase, six studies remained. All six found a positive effect of neuroHAART on neurocognitive function or CSF HIV suppression. Of these six studies, only two had statistical power of at least 80%.

Conclusions

Studies assessed as using more rigorous methods found that neuroHAART was effective in improving neurocognitive function and decreasing CSF viral load, but only two of those studies were adequately statistically powered. Because all of these studies were observational, they represent a less compelling evidence base than randomised control trials for assessing treatment effect. Therefore, large randomised trials are needed to determine the robustness of any neuroHAART effect. However, such trials must be longitudinal, include the full spectrum of HAND, ideally carefully control for co-morbidities, and be based on optimal neuropsychology methods.

Human immunodeficiency virus-1 evolutionary patterns associated with pathogenic processes in the brain

The interplay between pathology and human immunodeficiency virus (HIV) expansion in brain tissues has not been thoroughly assessed in the highly active antiretroviral therapy (HAART) era. HIV-associated dementia (HAD) is marked by progressive brain infection due to recruitment and migration of macrophages in brain tissues; however, the cellular and viral events occurring prior to HAD development and death are under debate. In this study, 66 brain tissues from 11 autopsies were analyzed to assess HIV-1 DNA concentration in brain tissues. In most patients without HAD, it was impossible to amplify HIV-1 from brain tissues. Amplifiable DNA was obtained from three cases of patients on HAART who died due to primary pathology other than HAD: (1) cardiovascular disease, a disease associated with HAART therapy; (2) bacterial infections, including Mycobacterium avium complex, rapid occurrence of extreme dementia; and (3) acquired immunodeficiency syndrome (AIDS)-related lymphoma with meningeal involvement. HIV-1 DNA was also amplified from multiple tissues of two HAD patients. Analysis of HIV-1 nef, gp120, and gp41 sequences showed reduced viral evolution within brain tissues for the non-HAD cases relative to patients with clinical and histological HAD. The present study is the first to show a potential correlation between HIV-1 evolutionary patterns in the brain and different neuropathologies.

HIV-associated neurocognitive disorder: pathogenesis and therapeutic opportunities

Human immunodeficiency virus type 1 (HIV) infection presently affects more that 40 million people worldwide, and is associated with central nervous system (CNS) disruption in at least 30% of infected individuals. The use of highly active antiretroviral therapy has lessened the incidence, but not the prevalence of mild impairment of higher cognitive and cortical functions (HIV-associated neurocognitive disorders) as well as substantially reduced a more severe form dementia (HIV-associated dementia). Furthermore, improving neurological outcomes will require novel, adjunctive therapies that are targeted towards mechanisms of HIV-induced neurodegeneration. Identifying such molecular and pharmacological targets requires an understanding of the events preceding irreversible neuronal damage in the CNS, such as actions of neurotoxins (HIV proteins and cellular factors), disruption of ion channel properties, synaptic damage, and loss of adult neurogenesis. By considering the specific mechanisms and consequences of HIV neuropathogenesis, unified approaches for neuroprotection will likely emerge using a tailored, combined, and non-invasive approach.

Neurological disease: the effects of HIV and antiretroviral therapy and the implications for early antiretroviral therapy initiation

PURPOSE OF REVIEW

The purpose of this review is to examine the literature regarding HIV-associated neurocognitive disorders, early HIV infection of the central nervous system (CNS), the role of the peripheral immune system in controlling HIV infection and disease within the brain and the potential role that early antiretroviral treatment may play in the preservation of neurocognitive health in patients with more than 500 CD4+ cells/microl.

RECENT FINDINGS

In the post highly active antiretroviral therapy (HAART) era, HIV-associated neurocognitive disorders remain prevalent and even mild-moderate immunosuppression carries a risk for the development of HIV-associated dementia. HIV infection of the CNS occurs early in the illness, and data suggest that a robust peripheral immune system is key to the long-term control of CNS HIV infection. HAART results in clinical, neuropsychological and neuroradiological improvement in patients with HIV-associated neurocognitive disorders, and the prescription of HAART regimens with good cerebrospinal fluid penetration appears to be preferable in this setting. There is little evidence that HAART causes CNS toxicity. The benefits and risks of HAART in the preservation or enhancement of neurocognitive function in well, HIV-infected patients with more than 500 CD4+ cells/microl are unknown.

SUMMARY

The prescription of HAART in well, HIV-infected patients with high CD4+ cell counts may afford enhanced control of CNS HIV infection as a result of the benefits of HAART upon peripheral immune function. In turn, this may result in superior or preserved neurocognitive performance in comparison to the current practice of commencing HAART when CD4+ cells reach 350 cells/microl or lower. This hypothesis will be tested in an upcoming randomized clinical trial.

Efficacy of nelfinavir-based treatment in the central nervous system of HIV-1 infected patients

We studied the HIV-1 load and nelfinavir (NFV) concentrations in cerebrospinal fluid (CSF) after long-term successful NFV-based therapy, using ultrasensitive methods of detection. 19 patients without virological failure in plasma, who had been treated with 2 nucleoside analogue reverse transcripaste inhibitors (NRTI) and NFV for a minimum of 18 months were included. HIV-RNA was determined in plasma and CSF using an ultrasensitive method (<2 copies/ml). Total and free concentrations of NFV were analysed using high liquid chromatography with UV-light detection. 12 out of 19 (63%) patients had <2 copies HIV-RNA/ml in CSF. Seven subjects ranged between 3 and 39 copies/ml, 2 of whom had a slightly higher viral load in CSF than in plasma. NFV was detected in CSF in 16 out of 18 patients analysed and was quantifiable in 8 patients, at concentrations ranging from 6 to 29 nM. There was no correlation between NFV concentration and HIV-RNA levels. Long-term therapy with NFV + 2 NRTI showed no increased rate of virological treatment failure within the central nervous system (CNS) in compliant patients, despite earlier reports of lack of NFV penetration to CNS. Using a highly sensitive method, NFV was detected and quantified in the CSF, although at low values, which could have contributed to the high anti-HIV-1 efficacy of the therapy seen in our subjects.

High level HIV-1 DNA concentrations in brain tissues differentiate patients with post-HAART AIDS dementia complex or cardiovascular disease from those with AIDS

Highly active antiretroviral treatment (HAART) has had a significant impact on survival of individuals with acquired immunodeficiency syndrome (AIDS); however, with the longer life-span of patients with AIDS, there is increasing prevalence of AIDS dementia complex (ADC) and other non-AIDS-defining illness, and cardiovascular diseases (CVD) are also common. The influence of these varied disease processes on HIV-1 DNA concentration in brain tissues has not been thoroughly assessed in the post-HAART era. The purpose of the current study is to clarify the impacts of ADC and other complications of HIV disease on the viral load in the brains in AIDS patients with post-HARRT. We examined autopsy specimens from the brains of thirteen patients who died from complications of AIDS with quantitative polymerase chain reaction (QPCR). All but one patient had received HAART prior to death since 1995. Two patients died with severe CVD, multiple cerebrovascular atherosclerosis (CVA) throughout the brain and five patients died with ADC. Six patients had no ADC/CVA. A QPCR was used to measure the presence of HIV-1 DNA in six brain tissues (meninges, frontal grey matter, frontal white matter, temporal subcortex, cerebellum and basal ganglia). In the post-HARRT era, for non-ADC/CVA patients, HIV-1 DNA concentration in brain tissues was statistically higher than that in patients with ADC. In a new finding, two patients who suffered from severe CVD, especially CVA, also had high concentrations of HIV-1 in brain compartments not showing ADC related changes. To our knowledge, this is the first report of a relationship between the CVA and HIV-1 viral burden in brain. The current observations suggest that HAART-resistant HIV reservoirs may survive within ADC lesions of the brain as well as the macrophage rich atherosclerosis, which needs to be confirmed by more AIDS cases with CVA.

Preventing brain damage in HIV infection

HIV-1 is a virus with neurotropic features causing major morbidity and also mortality if untreated. Mild symptoms of neurocognitive impairment are common and precede more severe forms of dementia, termed AIDS dementia complex (ADC). The pathogenesis of neurodegeneration in HIV-1 infection is not fully understood, and we lack specific markers to verify the diagnosis. Fortunately, antiretroviral treatment is effective in treating both systemic and CNS infection, and neurocognitive symptoms and ADC will, in most cases, improve on treatment. This review focuses on current research regarding cerebral spinal fluid biomarkers and effects of highly active antiretroviral treatment on HIV-1 CNS disease.

Relative sensitivity of magnetic resonance spectroscopy and quantitative magnetic resonance imaging to cognitive function among nondemented individuals infected with HIV

In the present study, we examined the relationships among cognitive function, magnetic resonance spectroscopy (MRS) brain metabolite indices measured in the basal ganglia, and quantitative magnetic resonance imaging (MRI) of the caudate nucleus and the putamen in the earliest stages of HIV-related cognitive involvement. Participants included 22 HIV-positive individuals and 20 HIV-negative individuals. HIV-positive individuals performed significantly more poorly than the HIV-negative individuals on several cognitive measures. In addition, the choline/creatine ratio was significantly higher and the N-acetyl aspartate/choline ratio was significantly lower among HIV patients. The caudate and putamen sizes were smaller among HIV-positive patients compared with controls; however, the differences did not reach statistical significance. Correlation analyses revealed associations between cognitive function and select MRS indices. In addition, caudate size was significantly correlated with performances on higher-order thinking tests whereas putamen size was significantly correlated with performances on motor tests. The results suggest that MRS differences are more pronounced than area size differences between seropositive and seronegative individuals in mild stages of HIV-related cognitive impairment. However, basal ganglia size remains an important contributor to cognitive status in this population. Longitudinal studies are needed to determine the evolution of these imaging correlates of HIV-cognitive impairment in HIV.

Changes in the incidence and predictors of human immunodeficiency virus-associated dementia in the era of highly active antiretroviral therapy

OBJECTIVE

Though effective anti-human immunodeficiency virus (HIV) therapies are now available, they have variable penetration into the brain. We therefore aimed to assess changes over calendar time in the risk for HIV-associated dementia (HIV-D), and factors associated with HIV-D risk.

METHODS

Using Concerted Action on Seroconversion to AIDS and Death in Europe (CASCADE) data, we analyzed factors associated with time from HIV seroconversion to HIV-D using Cox models with time-updated covariates. The effect of duration of infection was explored using flexible parametric survival models.

RESULTS

222 of 15,380 seroconverters developed HIV-D. The incidence per 1,000 person-years was 6.49 pre-1997 (before highly active antiretroviral therapy was available), declining to 0.66 by 2003 to 2006. Compared with most recent CD4 count > or = 350 cells/mm3, the adjusted relative risk (95% confidence interval) of HIV-D was 3.47 (1.91-6.28), 10.19 (5.72-18.15), and 39.03 (22.96-66.36) at 200 to 349, 100 to 199, and 0 to 99 cells/mm3, respectively. In 2003 to 2006, older age at seroconversion (relative risk = 3.24 per 10-year increase [95% confidence interval, 2.00-5.24]) and previous acquired immune deficiency syndrome diagnosis (relative risk = 4.92 [95% confidence interval, 1.43-16.92]) were associated with HIV-D risk, independently of current CD4 count. HIV-D risk appeared to increase during chronic infection, by 48% at 10 years after seroconversion compared with the lowest risk at 1.8 years.

INTERPRETATION

HIV-D incidence has reduced markedly since 1997. However, patients with low (<200 cells/mm3) or even intermediate (200-349 cells/mm3) CD4 counts, previous acquired immune deficiency syndrome diagnosis, longer HIV infection duration, and older age at seroconversion are at increased risk and should be closely monitored for neurocognitive disorders.

Effects of highly active antiretroviral therapy (HAART) on psychomotor performance in children with HIV disease

OBJECTIVE

This study assesses the effects of HAART on psychomotor performance of symptomatic HIV-infected children. It is one of the first studies to look at neurobehavioral functioning in children infected with HIV in resource-limited countries.

DESIGN

A longitudinal pilot study of vertically HIV-infected children at the HIV Netherlands Australia Thailand Research Collaboration Center in Bangkok, Thailand.

METHODS

A total of 34 children participated in the study of whom 16 had never received antiretroviral (ARV) therapy and were about to start HAART (Newly treated children), 7 did not receive antiretroviral therapy (Untreated children) and 11 had been treated with HAART for more than one year (HAART experienced children). All children were administered 4 psychomotor tasks at baseline and after 4 months. The Newly treated and the Untreated children were also evaluated after 12 months.

RESULTS

In general, the children performed similarly on all psychomotor tasks at baseline. After 12 months of HAART, there was a significant increase in CD4% in the Newly treated group. Overall, psychomotor performance did not change at the 4-month evaluation in all groups. At the 12-month evaluation psychomotor performance had deteriorated substantially on all tasks in both the Newly treated and the Untreated children.

CONCLUSIONS

There was no significant difference in psychomotor functioning between children newly treated, previously treated and untreated with HAART over the course of one year. Psychomotor performance deteriorated after 12 months of HAART, which provides important indications concerning the lack of benefits of HAART on psychomotor functions in children despite immunologic reconstitution. Further research with larger sample sizes is needed to confirm these findings.

Cerebrospinal and peripheral human immunodeficiency virus type 1 load in a multisite, randomized, double-blind, placebo-controlled trial of D-Ala1-peptide T-amide for HIV-1-associated cognitive-motor impairment

D-Ala1-peptide T-amide (DAPTA) has shown neuroprotection in vitro against gp120-induced loss of dendritic arborization and is promulgated as a CCR5 antagonist. A multisite, randomized, double-blind clinical trial of DAPTA versus placebo prior to combination antiretroviral therapy conducted with human immunodeficiency virus (HIV)-1 seropositive participants having cognitive impairment showed no overall cognitive effect, though subgroups with greater impairment and CD4 cell counts of 201 to 500 cells/mm3 at baseline showed significant improvement. The objective of this study was to examine whether intranasal administration of DAPTA at a dose of 2 mg three times per day (tid) was associated with a reduction of cerebrospinal fluid (CSF) and peripheral (plasma and serum) viral load among a subgroup of participants completing 6 months of treatment. Baseline and 6-month CSF (n = 92) and peripheral (plasma n = 33; serum n = 24) viral load were measured by the Roche Ultrasensitive assay, version 1.5, with reflexive use of the AMPLICOR assay and preservation of the blind. A DAPTA treatment indicator variable was tested using generalized linear models on change in viral load. Peripheral load (combined plasma and serum) was significantly reduced in the DAPTA-treated group. No group differences in CSF viral load were found. This retrospective study on a limited subgroup of the original trial sample indicated that DAPTA treatment may reduce peripheral viral load without concomitant CSF effects. Future studies should be undertaken to confirm the existence of this result and the CSF-periphery dissociation observed with respect to HIV-1-associated cognitive-motor impairment.

Simian immunodeficiency virus envelope compartmentalizes in brain regions independent of neuropathology

Simian immunodeficiency virus (SIV) and human immunodeficiency virus (HIV) gp160s obtained from the brain are often genetically distinct from those isolated from other organs, suggesting the presence of brain-specific selective pressures or founder effects that result in the compartmentalization of viral quasi-species. Whereas HIV has also been found to compartmentalize within different regions of the brain, the extent of brain-regional compartmentalization of SIV in rhesus macaques has not been characterized. Furthermore, much is still unknown about whether phenotypic differences exist in envelopes from different brain regions. To address these questions, env DNA sequences were amplified from four SIVmac239-infected macaques and subjected to phylogenetic and phenetic analysis. The authors demonstrated that sequences from different areas of the brain form distinct clades, and that the long-term progressing macaques demonstrated a greater degree of regional compartmentalization compared to the rapidly progressing macaques. In addition, regional compartmentalization occurred regardless of the presence of giant-cell encephalitis. Nucleotide substitution rates at synonymous and nonsynonymous sites (ds:dn rates) indicated that positive selection varied among envelopes from different brain regions. In one macaque, envelopes from some but not all brain regions acquired changes in a conserved CD4-binding motif GGGDPE at amino acids 382 to 387. Furthermore, gp160s with the mutation G383E were able to mediate cell-to-cell fusion in a CD4-independent manner and were more susceptible to fusion inhibition by pooled plasma from infected macaques. Reversion of this mutation by site-directed mutagenesis resulted in reduction of CD4-independence and resistance to fusion inhibition in cell fusion assays. These studies demonstrate that SIV evolution within the brain results in a heterogeneous viral population with different phenotypes among different regions.

HIV-TAT protein upregulates expression of multidrug resistance protein 1 in the blood-brain barrier

Central nervous system (CNS) complications of human immunodeficiency virus (HIV) infection remain a serious health risk in HIV/acquired immunodeficiency syndrome despite significant advances in highly active antiretroviral therapy (HAART). Specific drugs used for HAART are substrates for the efflux transport systems, such as the multidrug resistance-associated proteins (MRPs), which are present on brain microvascular endothelial cells (BMEC) and astrocytes, that is, the main cell types that form the blood-brain barrier (BBB). Thus, drugs employed in HAART are actively removed from the CNS and do not efficiently inhibit HIV replication in the brain. To study the potential mechanisms of this process, the aim of the present research was to address the hypothesis that HIV Tat protein can contribute to upregulation of MRP expression at the BBB level. Tat is a protein produced and released by HIV-infected cells, which may play an important role in brain vascular pathology in the course of HIV infection. Among the family of MRPs, exposure to Tat specifically induced MRP1 messenger ribonucleic acid and protein expression both in BMEC and astrocytes. These alterations were accompanied by enhanced MRP1-mediated efflux functions. Furthermore, activation of the mitogen-activated protein kinase signaling cascade was identified as the mechanism involved in Tat-mediated overexpression of MRP1. These results indicate that Tat exposure can lead to alterations of the BBB functions and decrease HAART efficacy in the CNS through overexpression of drug efflux transporters.

Neuroactive antiretroviral drugs do not influence neurocognitive performance in less advanced HIV-infected patients responding to highly active antiretroviral therapy

OBJECTIVE

To analyze the effect of antiretroviral therapy, including drugs that have good penetration in cerebrospinal fluid (CSF), on neuropsychologic performance.

METHODS

One hundred sixty-five HIV-1-infected patients exposed to a stable highly active antiretroviral therapy (HAART) regimen were studied. Neuropsychologic examinations were performed for all patients.

RESULTS

A total of 50.3% of patients were impaired. In multivariate analysis, older age (for 10-year increase, odds ratio [OR] = 4.8, 95% confidence interval [CI]: 2.2 to 10.4; P< 0.0001) and higher plasma HIV-1 RNA levels (OR = 1.90, 95% CI: 1.1 to 3.2; P = 0.021) at testing were independently associated with an increased probability of impaired neurocognitive performance, whereas higher educational level was a protective factor (OR = 0.76, 95% CI: 0.65 to 0.90; P=0.001). A significant linear correlation was observed between the neuropsychologic z score for 8 tests (NPZ8) score, a quantitative parameter of neurocognitive impairment, and CD4 cell count at neuropsychologic testing (R = 0.273, P = 0.001) and between the NPZ8 score and the patient's age (R = 0.288, P = 0.001).

CONCLUSIONS

Our study indicates that the use of stable HAART, including multiple drugs that have good CSF penetration, was not associated with neuropsychologic performance. To prevent independent replication of HIV in CSF with better control of a relevant reservoir of HIV is one of the crucial aims of therapeutic strategy.

Using gene delivery to protect HIV-susceptible CNS cells: inhibiting HIV replication in microglia

Antiretroviral chemotherapy penetrates the CNS poorly. CNS HIV, thus sheltered, may injure the brain and complicate control of systemic HIV infection. Microglial cells play a major role in HIV persistence in the CNS but are rarely targeted for gene delivery. Because recombinant SV40 vectors (rSV40s) transduce other phagocytic cells efficiently, we tested rSV40 delivery of anti-HIV genetic therapy to microglial cells. Microglia prepared as enriched cultures from human fetal brain, were transduced with marker vectors, SV(RFP) and SV(Nef/FLAG), respectively, carrying DsRed and HIV-1 Nef bearing a FLAG epitope. By immunostaining and FACS, 95% of unselected cells expressed the transgenes, without detectable toxicity. Microglia were transduced with SV(AT), carrying human alpha1-antitrypsin (alpha1AT), which blocks Env and Gag processing. SV(AT)-treated microglia strongly resisted challenge with HIV-1BaL, even when microglia were transduced with SV(AT) following HIV challenge. Thus, rSV40s effectively transduce microglia and protect them from HIV.

Atteintes du système nerveux central et infection par le VIH-1

Central nervous system complications are common in HIV-1 infected patients and occur either as a result of concomitant immunosuppression (opportunistic infections, lymphoma and tumors), as a primary manifestation of HIV infection, or as an adverse effect of therapy (immune restoration and toxicity). These complications contribute largely to patient morbidity and mortality. In the era of highly active antiretroviral therapy (HAART) these disease states have changed in presentation, outcome and incidence. We review in detail the epidemiology, pathogenesis, clinical features, diagnosis, and management of these disorders.

HIV-1 RNA levels in cerebrospinal fluid and plasma and their correlation with opportunistic neurological diseases in a Brazilian AIDS reference hospital

BACKGROUND: Plasma HIV RNA levels reflect systemic viral replication but in CNS it may occur relatively independent of systemic infection, yet clinical application of CSF HIV-1 RNA levels is less clear. OBJECTIVE: to compare CSF and plasma HIV-1 RNA levels of patients with different opportunistic neurological diseases to those without neurological disease, as well as to correlate these levels with the outcome of the disease and use of HAART. METHOD: 97 patients who had lumbar puncture for routine work up of suspected neurological diseases, were divided in 2 groups: without neurological disease (23) and with neurological disease (74). NASBA was used for plasma and CSF HIV RNA. RESULTS: Median CSF viral load was higher in toxoplasmic encephalitis, cryptococcal meningitis, HIV dementia and neurological diseases without a defined etiology when compared to patients without neurological disease. There was no difference between plasma viral load in patients with and without neurological diseases. Median viral load was higher in plasma and CSF among patients who died when compared to those successfully treated. CSF and plasma viral load were lower in patients with opportunistic diseases on HAART than without HAART. CONCLUSION: CSF viral load was higher in patients with any neurological disease, but this difference was not present in plasma viral load, suggesting that neurological disease influences more the CSF than plasma compartments. Notwithstanding different neurological diseases were not possible to be diferentiated by the levels of CSF HIV-1.

Potential role for white matter lysosome expansion in HIV-associated dementia

Expansion of the lysosomal apparatus occurs in subcortical white matter in brains from persons with AIDS. This study examined whether HIV-associated subcortical dementia (HAD) is significantly related to this lysosomal anomaly. Brain cortex and adjacent white matter from the middle frontal gyrus were obtained from the National NeuroAIDS Tissue Consortium. Lysosomal hydrolase activity was assayed in 57 subjects who underwent neuropsychological testing within 6 months prior to autopsy. Decedents were evaluated from 4 geographical sites in the United States: Galveston/Houston, Texas (n = 36), Los Angeles, California (n = 5), New York, New York (n = 5), and San Diego, California (n = 11). Increased beta-glucuronidase activity, a representative lysosomal glycosidase, was correlated with the amount of neurocognitive impairment. Significant correlation was present in 5 of 7 functional testing domains, including some that draw upon frontal lobe output (r = 0.419; P < 0.002). The biochemical anomaly was negligible in cerebral cortex and cerebrospinal fluid and was not correlated with brain dysfunction in those compartments. Glycosidase activation was associated significantly with increased HIV RNA concentration in brain tissue (r = 0.469; P < 0.021) and possibly with HIV RNA in cerebrospinal fluid (r = 0.266; P < 0.067). HIV RNA in blood plasma was not correlated. These results support the suggestion that abnormal metabolism in white matter glial cells contributes to cognitive slowing in persons with HAD. Because membrane turnover is routed through the endosome-lysosome apparatus, these data are in agreement with brain spectroscopic data that have suggested that there is an increase in membrane turnover in white matter glia.

Neurological complications of HIV infection

Cognitive disorders, vacuolar myelopathy, and sensory neuropathies associated with HIV are the most common disorders in patients with HIV AIDS, and are the focus of this review. These disorders are treatable and of those associated with HIV AIDS the pathogenic mechanisms are the most understood. Although triggered by productive HIV macrophage infections, aberrant immune activation plays a major role in inducing the CNS disorders. Novel therapies aimed at these inflammatory mechanisms can be effective. The sensory neuropathies associated with HIV infection are a major cause of morbidity; incidence may be increased by the toxic effects of specific antiretroviral drugs within the peripheral nervous system.