Plasma CXCL10 correlates with HAND in HIV-infected women.

HIV-associated neurocognitive disorder (HAND) is characterized by chronic immune activation. We aimed to identify biomarkers associated with HAND and to investigate their association with cognitive function and sex, in a homogenous cohort of HIV-infected (HIV+) young adults, parenterally infected during early childhood. One hundred forty-four HIV+ Romanian participants (51% women) without major confounders underwent standardized neurocognitive and medical evaluation in a cross-sectional study. IFN-γ, IL-1ß, IL-6, CCL2, CXCL8, CXCL10, and TNF-α were measured in plasma in all participants and in cerebrospinal fluid (CSF) in a subgroup of 56 study participants. Biomarkers were compared with neurocognitive outcomes, and the influence of sex and HIV disease biomarkers was assessed. In this cohort of young adults (median age of 24 years), the rate of neurocognitive impairment (NCI) was 36.1%. Median current CD4+ count was 479 cells/mm3 and 36.8% had detectable plasma viral load. Women had better HIV-associated overall status. In plasma, controlling for sex, higher levels of IL-6 and TNF-α were associated with NCI (p < 0.05). Plasma CXCL10 showed a significant interaction with sex (p = 0.02); higher values were associated with NCI in women only (p = 0.02). Individuals with undetectable viral load had significantly lower plasma CXCL10 (p < 0.001) and CCL2 (p = 0.02) levels, and CSF CXCL10 (p = 0.01), IL-6 (p = 0.04), and TNF-α (p = 0.04) levels. NCI in young men and women living with HIV was associated with higher IL-6 and TNF-α in plasma, but not in the CSF. CXCL10 was identified as a biomarker of NCI specifically in women with chronic HIV infection.

Vitamin D is not associated with HIV-associated neurocognitive disorder in Rakai, Uganda.

We investigated whether vitamin D is associated with HIV-associated neurocognitive disorder (HAND). HIV-infected (HIV+) antiretroviral therapy (ART)-naïve adults in rural Uganda underwent a neurocognitive battery for determination of HAND stage at baseline and after 2 years. Baseline serum 25-hydroxyvitamin D (25OH-D) and serum and cerebrospinal fluids (CSF) vitamin D-binding protein (VDBP) were obtained. Of the 399 participants, 4% (n = 16) were vitamin D deficient (25OH-D < 20 ng/mL). There was no association between 25OH-D, serum or CSF VDBP, and HAND stage at baseline or follow-up. Future studies in a population with higher levels of vitamin D deficiency may be warranted.

Plasma neuronal exosomes serve as biomarkers of cognitive impairment in HIV infection and Alzheimer's disease.

Fluid biomarkers for cognitive impairment have the advantage of being relatively noninvasive and capable of monitoring neuronal and other brain cell health in real time. Biomarkers can predict the onset of dementing illness, but also correlate with cognition in a dynamic way allowing us to follow treatment responses and determine brain recovery. Chronic HIV infection causes cognitive impairment in a subset of individuals suggesting "premature aging." Exosomes are small extracellular vesicles that are shed from all cells. They are important in normal cell-to-cell communication as they contain cellular proteins, mRNA transcripts, and miRNAs. Exosome cargo varies depending on the health of the cell and pathological state; specific proteins/mRNAs and/or miRNAs are present and may serve as biomarkers. Exosomes of variable cellular origin can be isolated from peripheral blood by various methods. Neuron-derived exosomes (NDEs) can be isolated using a precipitation/immunoaffinity approach using antibodies against neuronal cell adhesion molecule L1CAM and the contents queried for central nervous system (CNS) disorders including HIV-associated neurological disorders (HAND) and Alzheimer's disease (AD). As these studies are recent, numerous questions arise including which neuronal proteins are in NDEs and whether their contents differ in different CNS pathologies or with age. In addition, can the NDE cargo predict as well as diagnose cognitive impairment and could exosomal contents be used as therapeutic biomarkers, or theramarkers, of neuronal recovery from effective treatment? This mini-review will show some new data and review recent studies on NDE from individuals with HIV infection and AD. HIV-associated neurocognitive disorders (HAND) are pathologies seen in a subset of individuals with chronic HIV infection. They belong to the spectrum of neurodegenerative diseases that result in death or dysfunction of neurons with similarities to Alzheimer disease (AD) but also distinctive differences (reviewed (Canet et al., Front Cell Neurosci 12: 307, 2018)). Both disorders are difficult to diagnose without neuropsychological testing and both need new biomarkers to judge progression as well as recovery with treatment. Both disorders involve neuroinflammation and several common targets. AD is associated with aging and HIV is thought to initiate premature aging. In HIV infection, amyloid beta (Aß), which is deposited in "plaques" in AD, is soluble and its relevance to HIV-associated cognitive impairment is controversial (Achim et al., J Neuroimmune Pharmacol 4: 190-199, 2009; Rempel and Pulliam, AIDS 19: 127-135, 2005). Aß deposition is required for AD pathological diagnosis, but is not necessarily causative (Barage and Sonawane, Neuropeptides 52: 1-18, 2015; Hardy and Selkoe, Science 297: 353-356, 2002; Morris et al., Acta Neuropathol Commun 2: 135, 2014). Neurofilament light (NF-L) is a surrogate marker in plasma and cerebrospinal fluid (CSF) for neurodegeneration (Abu-Rumeileh et al., Alzheimers Res Ther 10: 3, 2018; Mattsson et al., JAMA Neurol 74: 557-566, 2017) but continues to be a controversial biomarker for both HAND and AD (Gisslen et al., EBioMedicine 3: 135-140, 2016; Kovacs et al., Eur J Neurol 24:1326-e77, 2017; Norgren et al., Brain Res 987: 25-31, 2003; Rolstad et al., J Alzheimers Dis 45: 873-881, 2015; Yilmaz et al., Expert Rev Mol Diagn 17: 761-770, 2017). Blood biomarkers are needed to advance both HAND and AD fields, as blood draws are less costly than neuroimaging and are minimally invasive compared to lumbar punctures required for CSF acquisition. Extracellular vesicles (EVs) are nanoscale membranous vesicles shed from all cells including those of the central nervous system (CNS) and found in all biofluids; they are divided into exosomes (30-150 nm) originating from late endosomes/multivesicular bodies and microvesicles (150-1000 nm) produced through budding of the plasma membrane. Both types of vesicles are implicated in the pathogenesis of neurodegenerative diseases and may provide biomarkers (Bellingham et al., Front Physiol 3: 124, 2012). In this report, we call the vesicles exosomes, since they are the predominant vesicles in our preparations. They are involved in cell-to-cell communication in normal homeostasis and can be carriers of toxic proteins (Aß, tau) (Sardar Sinha et al., Acta Neuropathol 136: 41-56, 2018) shed by cells as waste or actively secreted in a degenerative process (review Gupta and Pulliam, J Neuroinflammation 11: 68, 2014). The idea that exosomes originating from a specific cell can be recovered in the plasma using cellular surface markers of interest is intriguing. Neuron derived exosomes (NDEs) were first described in 2015 and isolated using antibodies against neural cell adhesion molecules NCAM or L1CAM, after total plasma exosome isolation (Fiandaca et al., Alzheimers Dement 11: 600-607 e1, 2015). Characterization of NDEs follows guidelines endorsed by the International Society for Extracellular Vesicles and includes Nanoparticle Tracking Analysis (NTA) to determine EV concentration and average diameter; Western Blots for EV markers; ELISAs for neuronal proteins and transmission EM for visualization (Sun et al., AIDS 31: F9-F17, 2017; Tang et al., FASEB J 30: 3097-106, 2016). This innovative isolation of an exosome sub-population has generated interest in using NDE as biomarkers for neurodegenerative diseases like AD, HAND, traumatic brain injury, posttraumatic stress disorder and more (reviews Agoston et al., Brain Inj 31: 1195-1203, 2017; Gupta and Pulliam, J Neuroinflammation 11: 68, 2014; Hu et al., Cell Death Dis 7: e2481, 2016; Karnati et al., J Neurotrauma, 2018; Osier et al., Mol Neurobiol, 2018). Several biomarkers from plasma NDEs were recently reported by the Pulliam lab to be elevated in general cognitive impairment (Sun et al., AIDS 31: F9-F17, 2017). We review our collective data here on HAND and AD and add to the characterization of plasma NDEs as exciting biomarkers of neurodegeneration.

Diagnostic and prognostic biomarkers for HAND.

In 2007, the nosology for HIV-1-associated neurocognitive disorders (HAND) was updated to a primarily neurocognitive disorder. However, currently available diagnostic tools lack the sensitivity and specificity needed for an accurate diagnosis for HAND. Scientists and clinicians, therefore, have been on a quest for an innovative biomarker to diagnose (i.e., diagnostic biomarker) and/or predict (i.e., prognostic biomarker) the progression of HAND in the post-combination antiretroviral therapy (cART) era. The present review examined the utility and challenges of four proposed biomarkers, including neurofilament light (NFL) chain concentration, amyloid (i.e., sAPPα, sAPPß, amyloid ß) and tau proteins (i.e., total tau, phosphorylated tau), resting-state functional magnetic resonance imaging (fMRI), and prepulse inhibition (PPI). Although significant genotypic differences have been observed in NFL chain concentration, sAPPα, sAPPß, amyloid ß, total tau, phosphorylated tau, and resting-state fMRI, inconsistencies and/or assessment limitations (e.g., invasive procedures, lack of disease specificity, cost) challenge their utility as a diagnostic and/or prognostic biomarker for milder forms of neurocognitive impairment (NCI) in the post-cART era. However, critical evaluation of the literature supports the utility of PPI as a powerful diagnostic biomarker with high accuracy (i.e., 86.7-97.1%), sensitivity (i.e., 89.3-100%), and specificity (i.e., 79.5-94.1%). Additionally, the inclusion of multiple CSF and/or plasma markers, rather than a single protein, may provide a more sensitive diagnostic biomarker for HAND; however, a pressing need for additional research remains. Most notably, PPI may serve as a prognostic biomarker for milder forms of NCI, evidenced by its ability to predict later NCI in higher-order cognitive domains with regression coefficients (i.e., r) greater than 0.8. Thus, PPI heralds an opportunity for the development of a brief, noninvasive diagnostic and promising prognostic biomarker for milder forms of NCI in the post-cART era.

Neurofilament light chain in blood is negatively associated with neuropsychological performance in HIV-infected adults and declines with initiation of antiretroviral therapy.

HIV-associated neurocognitive disorder (HAND) persists in the combination antiretroviral therapy (cART) era and is associated with diminished quality of life. The disorder remains challenging to diagnose given the requirement for comprehensive neuropsychological testing. Blood biomarkers are needed to facilitate the diagnosis of HAND and to gauge neurological response to antiretroviral therapy. We performed a study of plasma neurofilament light chain (NFL) that included 37 HIV-infected and 54 HIV-negative adults. In the univariate mixed-effect model involving HIV-infected participants, there was a statistically significant linear relationship between composite neuropsychological score (NPT-11) and plasma NFL (slope = - 9.9, standard error = 3.0 with 95% confidence interval - 3.2 to - 16.6 and p = 0.008 when testing slope = 0). Similarly, in the multivariate mixed-effect model, higher plasma NFL was significantly associated with worse NPT-11 (slope = - 11.5, standard error = 3.3 with 95% confidence interval - 3.7 to - 19.0 and p = 0.01 when testing slope = 0). The association between NPT-11 and NFL appeared to be driven by the group of individuals off cART. In a subset of participants who had visits before and after 24 weeks on cART (n = 11), plasma NFL declined over time (median = 22.7 versus 13.4 pg/ml, p = 0.02). In contrast, plasma NFL tended to increase over time among HIV-negative participants (median 10.3 versus 12.6 pg/ml, p = 0.065, n = 54). Plasma NFL therefore shows promise as a marker of neuropsychological performance during HIV. Larger studies are needed to determine if NFL could serve as a diagnostic tool for HAND during suppressive cART.

Plasma HIV RNA level is associated with neurocognitive function among HIV-1-infected patients in Nigeria.

Plasma HIV RNA level has been shown to correlate with HIV disease progression, morbidity, and mortality. We examined the association between levels of plasma HIV RNA and cognitive function among patients in Nigeria. A total of 179 HIV-1-infected participants with available plasma HIV RNA results and followed longitudinally for up to 2 years were included in this study. Blood samples from participants were used for the measurement of plasma HIV RNA and CD4+ T cell count. Utilizing demographic and practice effect-adjusted T scores obtained from a seven-domain neuropsychological test battery, cognitive status was determined by the global deficit score (GDS) approach, with a GDS ≥ 0.5 indicating cognitive impairment. In a longitudinal multivariable linear regression analysis, adjusting for CD4 cell count, Beck's Depression Score, age, gender, years of education, and antiretroviral treatment status, global T scores decreased by 0.35 per log10 increase in plasma HIV RNA [p = 0.033]. Adjusting for the same variables in a multivariable logistic regression, the odds of neurocognitive impairment were 28% higher per log10 increase in plasma HIV RNA (OR 1.28 [95% CI 1.08, 1.51]; p = 0.005). There were statistically significant associations for the speed of information processing, executive, and verbal fluency domains in both linear and logistic regression analyses. We found a significant association between plasma HIV RNA levels and cognitive function in both baseline (cross-sectional) and longitudinal analyses. However, the latter was significantly attenuated due to weak association among antiretroviral-treated individuals.

Variability in C-reactive protein is associated with cognitive impairment in women living with and without HIV: a longitudinal study.

Despite the availability of effective antiretroviral therapies, cognitive impairment (CI) remains prevalent in HIV-infected (HIV+) individuals. Evidence from primarily cross-sectional studies, in predominantly male samples, implicates monocyte- and macrophage-driven inflammatory processes linked to HIV-associated CI. Thus, peripheral systemic inflammatory markers may be clinically useful biomarkers in tracking HIV-associated CI. Given sex differences in immune function, we focused here on whether mean and intra-individual variability in inflammatory marker-predicted CI in HIV+ and HIV- women. Seventy-two HIV+ (36 with CI) and 58 HIV- (29 with CI) propensity-matched women participating in the Women's Interagency HIV Study completed a neuropsychological battery once between 2009 and 2011, and performance was used to determine CI status. Analysis of 13 peripheral immune markers was conducted on stored biospecimens at three time points (7 and 3.5 years before neuropsychological data collection and concurrent with data collection). HIV+ women showed alterations in 8 immune markers compared to HIV- women. The strongest predictors of CI across HIV+ and HIV- women were lower mean soluble tumor necrosis factor receptor I (sTNFRI) levels, higher mean interleukin (IL)-6 levels, and greater variability in C-reactive protein (CRP) and matrix metalloproteinase (MMP)-9 (p values < 0.05). Stratified by HIV, the only significant predictor of CI was greater variability in CRP for both HIV+ and HIV- women (p values < 0.05). This variability predicted lower executive function, attention/working memory, and psychomotor speed in HIV+ but only learning in HIV- women (p values < 0.05). Intra-individual variability in CRP levels over time may be a good predictor of CI in predominately minority low-socioeconomic status midlife women.

Compartmentalized replication of R5 T cell-tropic HIV-1 in the central nervous system early in the course of infection.

Compartmentalized HIV-1 replication within the central nervous system (CNS) likely provides a foundation for neurocognitive impairment and a potentially important tissue reservoir. The timing of emergence and character of this local CNS replication has not been defined in a population of subjects. We examined the frequency of elevated cerebrospinal fluid (CSF) HIV-1 RNA concentration, the nature of CSF viral populations compared to the blood, and the presence of a cellular inflammatory response (with the potential to bring infected cells into the CNS) using paired CSF and blood samples obtained over the first two years of infection from 72 ART-naïve subjects. Using single genome amplification (SGA) and phylodynamics analysis of full-length env sequences, we compared CSF and blood viral populations in 33 of the 72 subjects. Independent HIV-1 replication in the CNS (compartmentalization) was detected in 20% of sample pairs analyzed by SGA, or 7% of all sample pairs, and was exclusively observed after four months of infection. In subjects with longitudinal sampling, 30% showed evidence of CNS viral replication or pleocytosis/inflammation in at least one time point, and in approximately 16% of subjects we observed evolving CSF/CNS compartmentalized viral replication and/or a marked CSF inflammatory response at multiple time points suggesting an ongoing or recurrent impact of the infection in the CNS. Two subjects had one of two transmitted lineages (or their recombinant) largely sequestered within the CNS shortly after transmission, indicating an additional mechanism for establishing early CNS replication. Transmitted variants were R5 T cell-tropic. Overall, examination of the relationships between CSF viral populations, blood and CSF HIV-1 RNA concentrations, and inflammatory responses suggested four distinct states of viral population dynamics, with associated mechanisms of local viral replication and the early influx of virus into the CNS. This study considerably enhances the generalizability of our results and greatly expands our knowledge of the early interactions of HIV-1 in the CNS.

Peripheral blood lymphocyte HIV DNA levels correlate with HIV associated neurocognitive disorders in Nigeria.

Mononuclear cells play key roles in the pathogenic mechanisms leading to HIV-associated neurocognitive disorders (HANDs). We examined the association between HIV DNA within peripheral blood mononuclear cell (PBMC) subsets and HAND in Nigeria. PBMCs were collected at baseline from 36 antiretroviral naive participants. CD14+ cells and T&B lymphocyte fractions were isolated by, respectively, positive and negative magnetic bead separation. Total HIV DNA within CD14+ and T&B cells were separately quantified using real-time PCR assay targeting HIV LTR-gag and cell input numbers determined by CCR5 copies/sample. Utilizing demographically adjusted T scores obtained from a 7-domain neuropsychological test battery, cognitive status was determined by the global deficit score (GDS) approach, with a GDS of ≥0.5 indicating cognitive impairment. In a linear regression adjusting for plasma HIV RNA, CD4 and lymphocyte count, Beck's depression score, and years of education, there was 0.04 lower log10 HIV DNA copies within T&B lymphocytes per unit increase in global T score (p = 0.02). Adjusting for the same variables in a logistic regression, the odds of cognitive impairment were 6.2 times greater per log10 increase in HIV DNA within T&B lymphocytes (p = 0.048). The association between cognitive impairment and HIV DNA within CD14+ monocytes did not reach statistical significance. In this pretreatment cohort with mild cognitive dysfunction, we found a strong association between levels of HIV DNA within the lymphocyte subset and HAND independent of plasma HIV RNA. These findings likely reflect the neurologic impact of a larger HIV reservoir and active viral replication.

Nef exosomes isolated from the plasma of individuals with HIV-associated dementia (HAD) can induce Aß(1-42) secretion in SH-SY5Y neural cells.

In the era of combined antiretroviral therapy (CART), many of the complications due to HIV-1 infection have diminished. One exception is HIV-associated neurocognitive disorder (HAND). HAND is a spectrum of disorders in cognitive function that ranges from asymptomatic disease to severe dementia (HAD). The milder form of HAND has actually remained the same or slightly increased in prevalence in the CART era. Even in individuals who have maintained undetectable HIV RNA loads, viral proteins such as Nef and Tat can continue to be expressed. In this report, we show that Nef protein and nef messenger RNA (mRNA) are packaged into exosomes that remain in circulation in patients with HAD. Plasma-derived Nef exosomes from patients with HAD have the ability to interact with the neuroblastoma cell line SH-SY5Y and deliver nef mRNA. The mRNA can induce expression of Nef in target cells and subsequently increase expression and secretion of beta-amyloid (Aß) and Aß peptides. Increase secretion of amyloid peptide could contribute to cognitive impairment seen in HAND.

Soluble insulin receptor as a source of insulin resistance and cognitive impairment in HIV-seropositive women.

Insulin resistance occurs in HIV-infected individuals and is associated with HIV-associated neurocognitive disorders (HAND). However, the mechanisms involved are not well understood. Previously, we showed a correlation between soluble insulin receptor (sIR) and HAND. Here, we investigated if binding of free insulin to sIR and soluble insulin-like growth factor-1 receptor (sIGF1-R) levels are associated with sIR in HAND. Thirty-four (34) HIV-seropositive women stratified by cognitive status and five HIV-seronegative women were evaluated. In a subgroup of 20 HIV positive and 5 donors, binding of plasma insulin to sIR was determined by ELISA assay of residual insulin levels in plasma immuno-depleted with anti-IR-monoclonal antibody-Sepharose beads. sIR and sIGF1-R levels were determined by ELISA. Nonparametric statistics were used. Higher percentages of insulin bound to sIR significantly correlated with sIR levels and were associated with HAND status. Higher levels of plasma sIGF1-R had a positive correlation with sIR levels (p = 0.011) and were associated with HAND (p = 0.006). No correlations were observed with age, viral-immune profile, antiretroviral therapy, or TNF. This study suggests that changes in sIGF1-R levels and insulin binding to sIR may contribute to HAND.

Complement and HIV-I infection/HIV-associated neurocognitive disorders.

The various neurological complications associated with HIV-1 infection, specifically HIV-associated neurocognitive disorders (HAND) persist as a major public health burden worldwide. Despite the widespread use of anti-retroviral therapy, the prevalence of HAND is significantly high. HAND results from the direct effects of an HIV-1 infection as well as secondary effects of HIV-1-induced immune reaction and inflammatory response. Complement, a critical mediator of innate and acquired immunity, plays important roles in defeating many viral infections by the formation of a lytic pore or indirectly by opsonization and recruitment of phagocytes. While the role of complement in the pathogenesis of HIV-1 infection and HAND has been previously recognized for over 15 years, it has been largely underestimated thus far. Complement can be activated through HIV-1 envelope proteins, mannose-binding lectins (MBL), and anti-HIV-1 antibodies. Complement not only fights against HIV-1 infection but also enhances HIV-1 infection. In addition, HIV-1 can hijack complement regulators such as CD59 and CD55 and can utilize these regulators and factor H to escape from complement attack. Normally, complement levels in brain are much lower than plasma levels and there is no or little complement deposition in brain cells. Interestingly, local production and deposition of complement are dramatically increased in HIV-1-infected brain, indicating that complement may contribute to the pathogenesis of HAND. Here, we review the current understanding of the role of complement in HIV-1 infection and HAND, as well as potential therapeutic approaches targeting the complement system for the treatment and eradications of HIV-1 infection.

HIV associated neurocognitive disorders in the modern antiviral treatment era: prevalence, characteristics, biomarkers, and effects of treatment.

The introduction of combination antiretroviral treatment (cART) has significantly reduced the mortality secondary to opportunistic infections in HIV patients by restoring the immune system. In the central nervous system (CNS), there has also been benefit with a marked reduction of HIV associated dementia. However, the milder forms of HIV associated neurocognitive disorder (HAND), namely asymptomatic neurocognitive impairment and mild neurocognitive disorder, remain prevalent in the cART era. In this article, we will discuss how cART interacts with HAND in terms of clinical characteristics and biomarkers. We will then review the outcomes of recent clinical studies focused on the CNS penetrating antiretroviral regimens and some novel therapeutic approaches.

Relevance of lipopolysaccharide levels in HIV-associated neurocognitive impairment: the Neuradapt study.

Contributory factors to HIV-associated neurocognitive disorders (HAND) have been shown to include age, co-morbid infections, medication toxicity, virological, genetic and vascular mechanisms, as well as microbial translocation of lipopolysaccharide (LPS), which is suspected to trigger monocyte activation and increase trafficking of infected cells into the brain. In this study, our aim was to assess the degree of neurocognitive impairment in a group of randomly selected HIV-infected patients and investigate potential risk factors, including LPS plasma levels. Furthermore, we evaluated the relevance of LPS as a potential marker for screening patients with mild neurocognitive impairment. LPS plasma levels were compared among patients with HAND and those with no HAND. As LPS has also been shown to be elevated in hepatitis C co-infection, the analysis was stratified according to the presence or not of hepatitis C virus (HCV) co-infection. Differences between groups were evaluated using chi-square tests and Kruskal-Wallis non-parametric tests. Stepwise logistic regression was performed to identify independent risk factors for HAND in the subgroups of HCV-positive and negative patients. A p value <0.05 was considered significant. Analyses were conducted using SPSS® software. From December 2007 to July 2009, 179 patients were tested (mean age 44, 73 % male, 87 % on treatment, 30 % HCV co-infected, median CD4 504/ml and 67 % with viral load below 40 copies/ml). HAND was identified in 40/179 patients (22 %), the majority displaying asymptomatic neurocognitive impairment or mild neurocognitive disorder. Univariate analysis showed that age, illicit drug use, hepatitis C co-infection, prior AIDS-defining events, CD4/CD8 ratio and LPS plasma levels were significantly associated with HAND. The median LPS level was 98.2 pg/ml in the non-HAND group versus 116.1 pg/ml in the HAND group (p < 0.014). No differences were found in LPS values between subgroups of impairment. There was a clear association between LPS levels and HAND in the HCV-positive group (p = 0.036), while there was none in the HCV-negative group (p = 0.502). No difference in degree of hepatic fibrosis was found between the HAND and non-HAND groups. In conclusion, LPS levels were associated with HAND in the HCV-positive group, while, in the HCV-negative group, age and pro-viral DNA were the only variables independently associated with HAND. There was no difference in degree of liver disease as predicted by score of fibrosis between HAND and non-HAND groups. The role of HCV co-infection and higher LPS levels in the pathogenesis of HAND in patients with viral suppression on treatment requires further investigation.

Apolipoprotein E4 genotype does not increase risk of HIV-associated neurocognitive disorders.

This is a cross-sectional, observational study to evaluate the hypothesis that HIV-seropositive (HIV+) apolipoprotein E4 (APOE4) carriers are at increased risk for HIV-associated neurocognitive disorders (HAND) compared to APOE4 noncarriers with HIV in the CNS HIV Antiretroviral Therapy Effects Research (CHARTER) Group sample. APOE genotype was determined in 466 CHARTER participants with varying disease stages and histories of antiretroviral treatment who did not have severe psychiatric or medical comorbid conditions that preclude diagnosis of HAND. HAND diagnoses were based on results of comprehensive neurobehavioral evaluation and use of current neuroAIDS diagnostic criteria. HAND status consists of two levels: neuropsychologically normal status (i.e., no HAND) and any HAND diagnosis (i.e., asymptomatic neurocognitive impairment, minor neurocognitive disorder, HIV-associated dementia). Logistic regression analyses revealed no association between APOE4 carrier status and HAND, and there were no interactions between APOE4 carrier status and ethnicity, age, substance use disorders, duration of infection, or nadir CD4. Results did not differ when analysis was restricted to symptomatic HAND, and no APOE4 gene dose-dependent relationship to HAND emerged. APOE4 status was not associated with concurrent HAND in this large, well-characterized sample. This does not preclude emergence of an association between APOE4 status and HAND as this population ages. Prospective, longitudinal studies are needed to examine APOE4 as a risk factor for neurocognitive decline, incident HAND at older ages, and potential associations with cerebrospinal fluid amyloid.

Discordant genotypic resistance and HIV-1 genetic diversity from paired plasma and cerebrospinal fluid samples in Chinese settings.

In the highly active antiretroviral therapy era, the incidence of human immunodeficiency virus (HIV)-associated neurocognitive disorder remains high with the improved survival. The prevalence of resistance differs across geographical areas and HIV subtypes. Currently, little information on the resistance patterns in the central nervous system (CNS) is available in Chinese settings. In this study, we sequenced and analyzed the pol gene from paired cerebrospinal fluid and plasma samples of 34 Chinese HIV-infected patients. We found that eight subjects harbored mutations that confer drug resistance, and of these, six subjects exhibited discordant resistance patterns between the CNS and the blood. The levels of viral diversity in the CNS were significantly higher than those in the blood (p < 0.0001). Our results contribute to improving our understanding of HIV neuropathogenesis and help to optimize neuro-acquired immunodeficiency syndrome treatment.

Antiplatelet activity of valproic acid contributes to decreased soluble CD40 ligand production in HIV type 1-infected individuals.

CD40L is a type II membrane glycoprotein of the TNF family that is found on activated T cells, B cells, and platelets. We previously reported that the soluble form of this inflammatory mediator (sCD40L) is elevated in the plasma and cerebrospinal fluid of HIV-1-infected, cognitively impaired individuals. In this study, we demonstrate that the mood-stabilizing drug valproic acid (VPA) reduces sCD40L levels in plasma samples of HIV-1-infected patients (n = 23) and in washed human platelets, which are the main source of circulating sCD40L. VPA also inhibited HIV-1 transactivator of transcription-induced release of sCD40L and platelet factor 4 in C57BL/6 mice. The mechanism by which VPA was able to do so was investigated, and we demonstrate that VPA, a known glycogen synthase kinase 3ß inhibitor, blocks platelet activating factor-induced activation of glycogen synthase kinase 3ß in platelets in a manner that alters sCD40L release from platelets. These data reveal that VPA has antiplatelet activity, and they convey important implications for the potential of VPA as an adjunct therapy not only for cognitively impaired patients with HIV-1 infection, but also numerous inflammatory diseases for which such antiplatelet therapies are currently lacking.

Genetic features of cerebrospinal fluid-derived subtype B HIV-1 tat.

Since HIV-1 Tat has been associated with neurocognitive dysfunction, we investigated 60 HIV-1 subtype B-infected individuals who were characterized for neurocognitive functioning and had paired CSF and blood plasma samples available. To avoid issues with repeated sampling, we generated population-based HIV-1 tat sequences from each compartment and evaluated these data using a battery of phylogenetic, statistical, and machine learning tools. These analyses identified position HXB2 5905 within the cysteine-rich domain of tat as a signature of CSF-derived HIV-1, and a higher number of mixed bases in CSF, as measure of diversity, was associated with HIV-associated neurocognitive disorder. Since identified mutations were synonymous, we evaluated the predicted secondary RNA structures, which showed that this mutation altered secondary structure. As a measure of divergence, the genetic distance between the blood and CSF-derived tat was inversely correlated with current and nadir CD4+ T cell counts. These data suggest that specific HIV-1 features of tat influence neurotropism and neurocognitive impairment.

Clinical factors related to brain structure in HIV: the CHARTER study.

Despite the widening use of combination antiretroviral therapy (ART), neurocognitive impairment remains common among HIV-infected (HIV+) individuals. Associations between HIV-related neuromedical variables and magnetic resonance imaging indices of brain structural integrity may provide insight into the neural bases for these symptoms. A diverse HIV+ sample (n = 251) was studied through the CNS HIV Antiretroviral Therapy Effects Research initiative. Multi-channel image analysis produced volumes of ventricular and sulcal cerebrospinal fluid (CSF), cortical and subcortical gray matter, total cerebral white matter, and abnormal white matter. Cross-sectional analyses employed a series of multiple linear regressions to model each structural volume as a function of severity of prior immunosuppression (CD4 nadir), current CD4 count, presence of detectable CSF HIV RNA, and presence of HCV antibodies; secondary analyses examined plasma HIV RNA, estimated duration of HIV infection, and cumulative exposure to ART. Lower CD4 nadir was related to most measures of the structural brain damage. Higher current CD4, unexpectedly, correlated with lower white and subcortical gray and increased CSF. Detectable CSF HIV RNA was related to less total white matter. HCV coinfection was associated with more abnormal white matter. Longer exposure to ART was associated with lower white matter and higher sulcal CSF. HIV neuromedical factors, including lower nadir, higher current CD4 levels, and detectable HIV RNA, were associated with white matter damage and variability in subcortical volumes. Brain structural integrity in HIV likely reflects dynamic effects of current immune status and HIV replication, superimposed on residual effects associated with severe prior immunosuppression.

Early detection of neuropathophysiology using diffusion-weighted magnetic resonance imaging in asymptomatic cats with feline immunodeficiency viral infection.

HIV infection results in a highly prevalent syndrome of cognitive and motor disorders designated as HIV-associated dementia (HAD). Neurologic dysfunction resembling HAD has been documented in cats infected with strain PPR of the feline immunodeficiency virus (FIV), whereas another highly pathogenic strain (C36) has not been known to cause neurologic signs. Animals experimentally infected with equivalent doses of FIV-C36 or FIV-PPR, and uninfected controls were evaluated by magnetic resonance diffusion-weighted imaging (DW-MRI) and spectroscopy (MRS) at 17.5-18 weeks post-infection, as part of a study of viral clade pathogenesis in FIV-infected cats. The goals of the MR imaging portion of the project were to determine whether this methodology was capable of detecting early neuropathophysiology in the absence of outward manifestation of neurological signs and to compare the MR imaging results for the two viral strains expected to have differing degrees of neurologic effects. We hypothesized that there would be increased diffusion, evidenced by the apparent diffusion coefficient as measured by DW-MRI, and altered metabolite ratios measured by MRS, in the brains of FIV-PPR-infected cats relative to C36-infected cats and uninfected controls. Increased apparent diffusion coefficients were seen in the white matter, gray matter, and basal ganglia of both the PPR and C36-infected (asymptomatic) cats. Thalamic MRS metabolite ratios did not differ between groups. The equivalently increased diffusion by DW-MRI suggests similar indirect neurotoxicity mechanisms for the two viral genotypes. DW-MRI is a sensitive tool to detect neuropathophysiological changes in vivo that could be useful during longitudinal studies of FIV.