Cerebrospinal Fluid HIV Research Articles

Asymptomatic Cerebrospinal Fluid HIV-1 Viral Blips and Viral Escape During Antiretroviral Therapy: A Longitudinal Study.

We examined longitudinal cerebrospinal fluid (CSF) samples (median, 5 samples/patients; interquartile range [IQR], 3-8 samples/patient) in 75 neurologically asymptomatic human immunodeficiency virus (HIV)-infected patients receiving antiretroviral therapy. Twenty-seven patients (36%) had ≥1 CSF HIV RNA load of >20 copies/mL (23% had ≥1 load of >50 copies/mL), with a median HIV RNA load of 50 copies/mL (IQR, 32-77 copies/mL). In plasma, 42 subjects (52%) and 22 subjects (29%) had an HIV RNA load of >20 and >50 copies/mL, respectively. Two subjects had an increasing virus load in consecutive CSF samples, representing possible CSF escape. Of 418 samples, 9% had a CSF HIV RNA load of >20 copies/mL (5% had a load of >50 copies/mL) and 19% had a plasma HIV RNA load of >20 copies/mL (8% had a load of >50 copies/mL). A CSF-associated virus load of >20 copies/mL was associated with higher CSF level of neopterin. In conclusion, CSF escape was rare, and increased CSF HIV RNA loads usually represented CSF virus load blips.

Cerebrospinal fluid viral load and neopterin in HIV-positive patients with undetectable viraemia.

Cerebrospinal fluid (CSF) HIV RNA is commonly used as a marker of compartmental antiviral activity in HIV-positive patients. Undetectable CSF HIV RNA levels have been associated with low CSF neopterin levels and better neurocognitive performances. The aim of this study was to analyse the prevalence and predictors of non-detectable CSF HIV RNA using a commercial assay. In adult HIV-positive HAART-treated patients with confirmed plasma HIV RNA <50 copies/ml, CSF HIV RNA (with Roche Amplicor Assay) and neopterin were measured. 112 adult patients were included. Plasma and CSF HIV RNA were non-detectable (target not detected [TND]) in 29 (25.9%) and 36 (32.1%) patients, respectively. CSF TND was observed more frequently in patients with plasma TND (P=0.005, OR=3.87). CSF neopterin levels were associated with age (rho =0.333, P=0.002) and current (rho= -0.272, P=0.015) and nadir (rho =-0.240, P=0.038) CD4+ T-lymphocytes; the lowest CSF neopterin concentration was observed in patients with CSF TND versus other viral load strata (0.62 mg/dl versus 0.78 mg/dl; P=0.048). Efficaciously treated HIV-positive patients with detectable plasma HIV RNA might imperfectly control CSF viral replication. Prospective studies addressing the management and neurocognitive consequences of CSF low-level viraemia are warranted.

Evaluation of cerebrospinal fluid virological escape in patients on long-term protease inhibitor monotherapy.

A strategy of protease inhibitor (PI) monotherapy with re-introduction of triple therapy in those who rebound has been shown to be a safe and effective treatment simplification approach for long-term management. We sought evidence for cerebrospinal fluid (CSF) virological escape in patients on long-term PI monotherapy. We performed lumbar puncture in asymptomatic participants with suppressed plasma HIV RNA after 96 weeks on the PI monotherapy arm (PI-mono) of the PIVOT trial. We also report CSF HIV RNA concentration in trial participants who were investigated for neurological/neurocognitive symptoms during the trial regardless of study arm allocation. All 11 asymptomatic participants on PI-mono who were tested had undetectable CSF HIV RNA at week 96. One of the three symptomatic participants on PI-mono had CSF HIV RNA of 1,895 copies/ml (undetectable in plasma) and neither of two symptomatic participants on triple therapy had CSF HIV RNA detected. CSF virological escape appears rare in asymptomatic patients on PI monotherapy and may not warrant routine CSF monitoring, but patients with symptoms merit more concern.

HIV-1 replication in central nervous system increases over time on only protease inhibitor therapy.

There are concerns about central nervous system (CNS)-replication of HIV-1 in patients on boosted protease inhibitors. Purpose of this study was to compare HIV-1 viral loads (VLs) from patients treated with only boosted dual protease inhibitor (bdPI), versus combination antiretroviral therapy (cART group), containing two nucleoside analogue reverse transcriptase inhibitors (NRTI) and a third partner. All patients from a large German HIV-treatment cohort with available medication, clinical and demographic data, including results from simultaneous HIV-1 viral load (VL) assessments in cerebrospinal fluid (CSF) and blood plasma, were retrospectively evaluated as controlled cross-sectional study. CSF had been obtained from patients with variable neurological symptoms during 2005-2014. Statistical analysis comprised nonparametric tests, regression and correlation techniques accounting for undetectable quantifications. Statistical analysis comprised nonparametric tests, regression and correlation techniques accounting for undetectable quantifications. Overall, 155 patients were evaluable (bdPI: 24; cART: 131). At time of CSF-collection, both groups were comparable in age, gender, CD4-cell counts, or primary HIV-transmission risks, though bdPI patients were clinically more advanced. The proportion of patients with undetectable HIV-1 (<50 copies/ml) in CSF was lower for bdPI group (25 vs 49.6%; p=0.026), but similar in plasma (46 vs 41%). Median CSF-VL was higher in bdPI group (600 vs 50 copies/ml; p=0.027) and similar in plasma. Mean VL CSF/plasma ratio was 342.91 for bdPI- and 54.48 for cART patients (p<0.001). Pearson's regression analysis revealed a trend for an elevated VL-ratio over time within bdPI group. HIV-1 replication was higher and more frequently detectable in CSF from bdPI patients, indicating a worse CNS penetration effectiveness of used boosted PI. Within bdPI group, measured CNS-viral replication was increasing over time, suggesting an over time impaired HIV-1 suppression in CSF.

Association between Plasma Homocysteine Levels and Neuronal Injury in HIV Infection.

ObjectiveTo investigate the role of homocysteine in neuronal injury in HIV infection.MethodsUsing a cross-sectional design and archived samples, we compared concentrations of plasma homocysteine and cerebrospinal fluid (CSF) neurofilament light protein (NFL), a sensitive marker of neuronal injury, in 83 HIV-1-infected subjects without antiretroviral treatment. We also analyzed plasma vitamin B12, serum folate, CSF, and plasma HIV RNA, the immune activation marker neopterin in CSF and serum, and albumin ratio as a marker of blood-brain barrier integrity. Twenty-two subjects provided a second sample median of 12.5 months after antiretroviral treatment initiation.ResultsA significant correlation was found between plasma homocysteine and CSF NFL concentrations in untreated individuals (r = 0.52, p < 0.0001). As expected, there was a significant inverse correlation between homocysteine and B12 (r = –0.41, p < 0.001) and folate (r = –0.40, p = < 0.001) levels. In a multiple linear regression analysis homocysteine stood out as an independent predictor of CSF NFL in HIV-1-infected individuals. The correlation of plasma homocysteine and CSF NFL was also present in the group receiving antiretroviral therapy (r = 0.51, p = 0.016).ConclusionA correlation between plasma homocysteine and axonal injury, as measured by CSF NFL, was found in both untreated and treated HIV. While this study is not able to prove a causal link, homocysteine and functional B12/folate deficiency appear to play a role in neural injury in HIV-infected individuals.

Neuropsychological Impairment in Acute HIV and the Effect of Immediate Antiretroviral Therapy

To investigate neuropsychological performance (NP) during acute HIV infection (AHI) before and after combination antiretroviral therapy (cART). Prospective study of Thai AHI participants examined at 3 and 6 months after initiation of cART. Thirty-six AHI participants were evaluated pre-cART at median 19 days since HIV exposure and 3 and 6 months after cART with the Grooved Pegboard test, Color Trails 1 & 2 (CT1, CT2), and Trail Making Test A. Raw scores were standardized to 251 age- and education-matched HIV-uninfected Thais. To account for learning effects, change in NP performance was compared with that of controls at 6 months. Analyses included multivariable regression, nonparametric repeated measures analysis of variance, and Mann-Whitney U test. Baseline NP scores for the AHI group were within normal range (z-scores range: -0.26 to -0.13). NP performance improved on CT1, CT2, and Trail Making Test A in the initial 3 months (P < 0.01) with no significant change during the last 3 months. Only improvement in CT1 was greater than that seen in controls at 6 months (P = 0.018). Participants who performed >1 SD below normative means on ≥2 tests (n = 8) exhibited higher baseline cerebrospinal fluid HIV RNA (P = 0.047) and had no improvement after cART. Most AHI individuals had normal NP performance, and early cART slightly improved their psychomotor function. However, approximately 25% had impaired NP performance, which correlated with higher cerebrospinal fluid HIV RNA, and these abnormalities were not reversed by early cART possibly indicating limited reversibility of cognitive impairment in a subset of AHI individuals.

Cerebrospinal fluid concentrations of tenofovir and emtricitabine in the setting of HIV-1 protease inhibitor-based regimens.

In the combination antiretroviral therapy (cART) era, prevalence of HIV-associated neurocognitive disorders (HAND) remains high: 36.2-44.8% 1, contributing to morbidity 1 and mortality 2. Suboptimal control of HIV in the central nervous system (CNS) likely plays a role in this phenomenon, as supported by elevated neopterin and detectable HIV-1 RNA in cerebrospinal fluid (CSF) of patients on long term cART 3. Studies have shown that limited CNS penetration by antiretroviral (ARV) drugs is associated with HAND 4,5. Multiple factors impact CNS drug penetration, including molecular size, lipophilicity, plasma protein binding, and affinity for efflux pump transporters 6. For example, the ATP-binding cassette (ABC) superfamily of efflux transporters, including p-glycoprotein and multidrug-resistance associated proteins (MRPs), are expressed at blood-brain and blood-CSF barriers and can limit drug disposition7. Because many ARVs are substrates and/or inhibitors of ABC transporters, complex drug-drug interactions can occur. Specifically, protease inhibitors (PIs) atazanavir (ATV) and darunavir (DRV) are common in cART regimens when given with ritonavir (RTV) plus a backbone of tenofovir disoproxil fumarate (TDF), the tenofovir (TFV) pro-drug, and emtricitabine (FTC) 8. Both ATV and DRV inhibit p-glycoprotein and MRP-1 9-11 ; these transporters are found at blood-brain and blood-CSF barriers and are important for TFV 12 and FTC transport 13. We compared CSF TFV and FTC concentrations between patients receiving two different RTV-boosted PI regimens: ATV vs DRV. We also examined associations between CSF drug concentrations and CSF HIV-1 RNA detection.

Deep sequencing of HIV-1 variants from paired plasma and cerebrospinal fluid during primary HIV infection

BackgroundLimited data exist comparing viral quasispecies between cerebrospinal fluid (CSF) and plasma compartments during primary HIV infection. Deep sequencing is a new method to examine the HIV plasma and CSF quasispecies. MethodsIn this pilot study, deep sequencing of protease (PR) and reverse transcriptase (RT) was performed in plasma and CSF from participants during primary HIV infection. Estimated mutational load was calculated by mutant variant frequency multiplied by HIV-RNA level. ResultsPaired plasma and CSF samples were studied from five antiretroviral therapy-naïve male participants with median 109 days post estimated transmission, age 32 years, CD4 cell count 580 cells/μL, HIV-RNA 5.18 log10 copies/mL in plasma and 3.67 log10 copies/mL in CSF. Plasma samples averaged 7,124 reads of PR and 2,448 reads of RT, whereas CSF samples averaged 7,082 and 2,792 reads, respectively. A distinct drug-resistance pattern with linked mutations present at significant levels (5–10%) was detected in one participant in CSF. Other low abundance variants (>0.2%) were detected in plasma and CSF of four out of five participants. ConclusionsDeep sequencing of CSF HIV is technically possible with sufficient HIV-RNA levels. Differences between the quasispecies in the two compartments detected in one participant, which were present with a high mutational load in CSF at an estimated 3.6 months after HIV infection, suggest that early CNS compartmentalisation may be revealed by sensitive deep-sequencing methods. The presence of distinct low abundance (<1%) resistance variants in plasma and CSF of three other subjects may be significant, but further investigation is needed.

High frequency of neurosyphilis in HIV-positive patients diagnosed with early syphilis.

Syphilis is an infection frequently seen with HIV, and European guidelines on the management of syphilis suggest that HIV-infected patients may have an increased risk of early neurological involvement, sometimes asymptomatic. Recent study shows a relationship between neurosyphilis and cerebrospinal fluid (CSF) HIV viral load (VL), which in turn may be associated with subsequent neurocognitive decline. The aim of the study was estimation of the frequency of neurosyphilis among HIV-positive patients with early syphilis. The study included all patients diagnosed with early syphilis who had lumbar puncture performed in the years 2008-2012. Analysis included CSF parameters (serology, mononuclear cells, protein, glucose, chloride and lactate levels), CD4 count, serum VL and highly active antiretroviral therapy (HAART). Diagnosis of neurosyphilis was confirmed by CSF serology [positive fluorescent treponemal antibody and/or Venereal Disease Research Laboratory (VDRL) test(s)] and increased number of mononuclear cells. Statistical analysis included χ(2) tests with an accepted significance level of P < 0.05. Lumbar puncture was performed in 72 patients, all men, with median age 33 (interquartile range 11) years. Neurosyphilis was confirmed in 65 (90.28%) of the patients. No statistically significant association between CSF parameters and CD4 count was found. However, statistically significant associations were found only between pleocytosis and serum VL > 1000 HIV-1 RNA copies/mL (P = 0.0451), as well as HAART treatment (P = 0.0328). The proportion of confirmed neurosyphilis cases, also in patients with low serum VDRL titres, was very high. Considering the high proportion of patients who objected to having LP performed in the absence of neurological symptoms and the risk associated with this procedure, it may be preferable to use treatments with good CNS penetration in all HIV-positive patients with early syphilis.

Cerebrospinal Fluid HIV Escape from Antiretroviral Therapy.

CNS infection is a nearly constant facet of systemic CNS infection and is generally well controlled by suppressive systemic antiretroviral therapy (ART). However, there are instances when HIV can be detected in the cerebrospinal fluid (CSF) despite suppression of plasma viruses below the clinical limits of measurement. We review three types of CSF viral escape: asymptomatic, neuro-symptomatic, and secondary. The first, asymptomatic CSF escape, is seemingly benign and characterized by lack of discernable neurological deterioration or subsequent CNS disease progression. Neuro-symptomatic CSF escape is an uncommon, but important, entity characterized by new or progressive CNS disease that is critical to recognize clinically because of its management implications. Finally, secondary CSF escape, which may be even more uncommon, is defined by an increase of CSF HIV replication in association with a concomitant non-HIV infection, as a consequence of the local inflammatory response. Understanding these CSF escape settings not only is important for clinical diagnosis and management but also may provide insight into the CNS HIV reservoir.

APOE ε4 moderates abnormal CSF-abeta-42 levels, while neurocognitive impairment is associated with abnormal CSF tau levels in HIV+ individuals - a cross-sectional observational study.

BackgroundCerebrospinal fluid (CSF) biomarkers Aβ1-42, t-tau and p-tau have a characteristic pattern in Alzheimer’s Disease (AD). Their roles in HIV-associated neurocognitive disorder (HAND) remains unclear.MethodsAdults with chronic treated HIV disease were recruited (n = 43, aged 56.7 ± 7.9; 32% aged 60+; median HIV duration 20 years, >95% plasma and CSF HIV RNA <50 cp/mL, on cART for a median 24 months). All underwent standard neuropsychological testing (61% had HAND), APOE genotyping (30.9% carried APOE ε4 and 7.1% were ε4 homozygotes) and a lumbar puncture. Concentrations of Aβ1-42, t-tau and p-tau were assessed in the CSF using commercial ELISAs. Current neurocognitive status was defined using the continuous Global Deficit Score, which grades impairment in clinically relevant categories. History of HAND was recorded. Univariate correlations informed multivariate models, which were corrected for nadir CD4-T cell counts and HIV duration.ResultsCarriage of APOE ε4 predicted markedly lower levels of CSF Aβ1-42 in univariate (r = -.50; p = .001) and multivariate analyses (R2 = .25; p < .0003). Greater levels of neurocognitive impairment were associated with higher CSF levels of p-tau in univariate analyses (r = .32; p = .03) and multivariate analyses (R2 = .10; p = .03). AD risk prediction cut-offs incorporating all three CSF biomarkers suggested that 12.5% of participants had a high risk for AD. Having a CSF-AD like profile was more frequent in those with current (p = .05) and past HIV-associated dementia (p = .03).ConclusionsSimilarly to larger studies, APOE ε4 genotype was not directly associated with HAND, but moderated CSF levels of Aβ1-42 in a minority of participants. In the majority of participants, increased CSF p-tau levels were associated with current neurocognitive impairment. Combined CSF biomarker risk for AD in the current HIV+ sample is more than 10 times greater than in the Australian population of the same age. Larger prospective studies are warranted.Electronic supplementary materialThe online version of this article (doi:10.1186/s12883-015-0298-0) contains supplementary material, which is available to authorized users.

Cerebrospinal fluid (CSF) CD8+ T-cells that express interferon-gamma contribute to HIV associated neurocognitive disorders (HAND).

BackgroundHIV associated neurocognitive disorders (HAND) continue to affect cognition and everyday functioning despite anti-retroviral treatment (ART). Previous studies focused on mechanisms related to monocyte/macrophage mediated inflammation. However, in the ART era, there is increasing evidence for the involvement of CD8+ T-cells in CNS pathogenesis.MethodsTo investigate the relationship between T-cell responses and neurocognitive impairment (NCI), cerebrospinal fluid (CSF) and peripheral blood CD4+ and CD8+ T-cell intracellular cytokine (IFNγ, IL-2, TNFα) and lytic marker (CD107a) expression were assessed in HIV infected subjects who underwent comprehensive neurocognitive (NC) evaluation and either initiated or changed ART.ResultsData were collected from 31 participants at 70 visits. The frequency of cytokine expressing T-cells in CSF was significantly higher than in peripheral blood for CD4+T-cells: TNFα, IL-2, IFNγ and CD8+T-cells: IL-2 and IFNγ. Analysis of T-cell activity and NCI as a function of CSF HIV RNA levels suggested a general association between NCI, high CSF CD8+ (but not CD4+T-cell) cytokine expression and CSF HIV RNA <103 copies/ml (p<0.0001). Specifically, CSF CD8+ T-cell IFNγ expression correlated with severity of NCI (r = 0.57, p = 0.004). Multivariable analyses indicated that CSF CD8+T-cell IFNγ and myeloid activation (CD163) contributed equally and independently to cognitive status and a composite variable produced the strongest correlation with NCI (r = 0.83, p = 0.0001). In contrast, CD8+ cytolytic activity (CD107a expression) was negatively correlated with NCI (p = 0.05) but was dependent on CD4 levels >400/μl and low CSF HIV RNA levels (<103 copies/ml). In our longitudinal analysis of 16 subjects, higher CSF CD8+IFNγ expression at baseline predicted NC decline at follow-up (p = 0.02). Severity of NCI at follow-up correlated with level of residual HIV RNA in CSF.ConclusionsPresence of IFNγ expressing CD8+ T-cells, absence of cytolytic CD8+ T-cells, high myeloid activation, and failure of ART to suppress HIV replication in CSF contribute to increased risk of HAND.

Longitudinal Analysis of Cerebrospinal Fluid and Plasma HIV-1 Envelope Sequences Isolated From a Single Donor with HIV Asymptomatic Neurocognitive Impairment.

Combined antiretroviral treatment (cART) has changed the clinical presentation of HIV-associated neurocognitive disorders (HAND) to that of the milder forms of the disease. Asymptomatic neurocognitive impairment (ANI) is now more prevalent and is associated with increased morbidity and mortality risk in HIV-1-infected people. HIV-1 envelope (env) genetic heterogeneity has been detected within the central nervous system (CNS) of individuals with ANI. Changes within env determine co-receptor use, cellular tropism, and neuropathogenesis. We hypothesize that compartmental changes are associated with HIV-1 env C2V4 during ANI and sought to analyze paired HIV-1 env sequences from plasma and cerebrospinal fluid (CSF) of a female subject undergoing long-term cART. Paired plasma and CSF samples were collected at 12-month intervals and HIV-1 env C2V4 was cloned and sequenced. Phylogenetic analysis of paired samples consistently showed genetic variants unique to the CSF. Phenotypic prediction showed CCR5 (R5) variants for all CSF-derived sequences and showed minor X4 variants (or dual-tropic) in the plasma at later time points. Viral compartmentalization was evident throughout the study, suggesting that the occurrence of distinctive env strains may contribute to the neuropathogenesis of HAND. Our study provides new insights about the genetic characteristics within the C2V4 of HIV-1 env that persist after long-term cART and during the course of persistent ANI.

Cerebrospinal fluid cytokines, matrix metalloproteinases, HIV, and tuberculous meningitis.

Cerebrospinal fluid cytokines, matrix metalloproteinases, HIV, and tuberculous meningitis.

Viro-immunological characterization of naïve patients with high cerebrospinal fluid (CSF) HIV RNA.

BackgroundHIV can spread into the central nervous system (CNS) early in the course of infection and this turns into intrathecal inflammation and neuronal damage. We aimed to investigate clinical and immunological parameters associated with elevated CSF VL in HIV-infected ART-naïve patients.Materials and MethodsHIV+ ART-naïve patients underwent a comprehensive battery of neurocognitive (NC) tests and lumbar puncture (LP) for CSF HIV-RNA detection. Plasma HIV-RNA and peripheral T-cell immune-phenotypes (CD38/CD45RA/CD45R0/CD127 on CD4/CD8) were also assessed (flow cytometry). High-CSF HIV RNA was defined as≥10000cp/mL (H-CSF), while CSF HIV RNA<10000cp/mL characterized low VL patients (L-CSF). Chi-square and Mann-Whitney tests were used. Parameters independently associated with CSF VL were explored by multivariate regression.ResultsA total of 131 patients were retrospectively enrolled. Forty-two patients (32%) had CSF VL >10000 cp/mL.Table 1 shows the features of H- versus L-CSF patients. Compared to L-CSF patients, H-CSF patients displayed lower current CD4+%, lower CD4/CD8 ratio and higher CD8%. No differences in NC tests performance were observed between groups (p=0.6). Regarding T-cell immuno-phenotypes, H-CSF patients displayed a higher proportion of CD45R0+CD38+CD8+ (11 vs 7%, p=0.02) and lower expression of CD45RA+CD8+ % (16 vs 20%, p=0.007), in comparison to L-CSF patients. In multivariate analysis CD45RA+CD8+ T-cells % (OR 0.917, CI 95% 0.852–0.987, p=0.002) was associated with H-CSF, even after adjustment for plasma VL, CD8 and CD4 count. Globally, in univariate CSF VL inversely correlated with CD45RA+CD8+ % (r=−0.223, p=0.0217) and CD127+CD4+ % (r= −0.204, p= 0.0225), while a positive association was found between CSF and plasma VL (r=0.303, p=0.0004) and CD8 % (r=0.211, p=0.016). In multivariate linear regression, in addition to positive association between plasma and CSF VL (β: 0.212, 95% CI 0.02–0.41, p=0.032), also CD45RA+CD8+ % were confirmed inversely associated to CSF VL (β: 0.21, 95% CI −0.5 to −0.002, p=0.036), adjusting for CD4/CD8 and CD4CD127 %.ConclusionsWe hereby describe a 32% prevalence of H-CSF in a cohort of HIV+ ART-naïve patients. Subjects with high-CSF viral replication are mostly with higher systemic immune activation, in particular the percentage of naïve CD8 T-cell is positively associated with CSF VL, irrespective of plasma VL. In HIV+ ART-naïve patients, especially if featuring a hyperactivated T-cell immune-phenotype, lumbar puncture should be considered to further guide CNS-targeted cART.

Neuropathogenesis of HIV-associated neurocognitive disorders: roles for immune activation, HIV blipping and viral tropism.

The purpose of this study is to discuss why HIV-associated neurocognitive disorders (HAND) persist despite apparently effective HIV suppression by highly active antiretroviral therapy (ART). As many as 50% of HIV-infected individuals suffer from HAND despite ART suppression of HIV replication to apparently undetectable levels in most treated individuals. Prior to ART, HIV-associated dementia (HAD), the severest form of HAND, affected nearly 20% of infected individuals; HAD now affects only nearly 2% of ART-treated persons, although less severe HAND forms persist. Recent studies link persistent immune activation, inflammation and viral escape/blipping in ART-treated individuals, as well as comorbid conditions, to HIV disease progression and increased HAND risk. Despite sustained HIV suppression in most ART-treated individuals, indicated by routine plasma monitoring and occasional cerebrospinal fluid (CSF) monitoring, 'blips' of HIV replication are often detected with more frequent monitoring, thus challenging the concept of viral suppression. Although the causes of HIV blipping are unclear, CSF HIV blipping associates with neuroinflammation and, possibly, central nervous system (CNS) injury. The current theory that macrophage-tropic HIV strains within the CNS predominate in driving HAND and these associated factors is now also challenged. Protection of the CNS by ART is incomplete, probably due to combined effects of incomplete HIV suppression, persistent immune activation and host comorbidity factors. Adjunctive therapies to ART are necessary for more effective protection.

Cerebrospinal-fluid exposure of efavirenz and its major metabolites when dosed at 400 and 600 mg once daily; a randomized controlled trial.

Introduction The optimal penetration of antiretroviral agents into central nervous system (CNS) may be a balance between providing adequate drug exposure to inhibit HIV-replication whilst avoiding concentrations associated with toxicities.Methods Cerebrospinal-fluid (CSF) exposure of efavirenz and metabolites 7-hydroxy (7OH-) and 8OH-efavirenz were assessed after at least 12 weeks of antiretroviral therapy in HIV-infected subjects randomized to commence antiretroviral regimens containing efavirenz at either 400 mg or 600 mg once daily. Clinical, pharmacokinetic and pharmacogenomic factors associated with CSF efavirenz and its metabolite concentrations were assessed.Results Of 28 subjects who completed all study procedures (14/14 on efavirenz 400 mg/600 mg), CSF HIV RNA was below 20 copies/mL in all at the time of examination. Concentrations of efavirenz and 7OH-efavirenz in the CSF were slightly lower when dosed at 400 mg versus 600 mg, although this was not statistically significant. A different trend was observed regarding 8OH-efavirenz concentrations where CSF exposure was slightly increased in the 400 mg efavirenz arm (see Table 1). Efavirenz concentration in the CSF was above 0.51 ng/mL (proposed CSF IC50 for WT virus) in all subjects and 8OH-efavirenz concentration in the CSF was above 3.3 ng/mL (a proposed toxicity threshold, reference) in 11/14 and 7/14 subjects randomized to the 400 mg and 600 mg doses of efavirenz, respectively. Whilst CSF efavirenz concentration was significantly associated with plasma concentration (P<0.001) and CYP2B6 genotype (CSF efavirenz GG to GT/TT GM ratio 0.56, 90% CI 0.42–0.74), CSF 8OH-efavirenz concentration was not (P=0.242 for association with plasma concentration and CSF 8OH-efavirenz GG to GT/TT GM ratio 1.52, 90% CI 0.97–2.36). Lastly, CSF 8OH-efavirenz concentration was associated with efavirenz symptom questionnaire results at one year (Spearman's correlation 0.13, P=0.05). Conclusions With both doses of efavirenz studied, CSF concentrations were considered adequate to inhibit HIV-replication, although concentrations of 8OH-efavirenz were greater than that reportedly associated with neuronal toxicity. CSF exposure of 8OH-efavirenz was not dependent on plasma exposure and we postulate may be subject to saturable pharmacokinetic effects.

Low levels of HIV-1 RNA detected in the cerebrospinal fluid after up to 10 years of suppressive therapy are associated with local immune activation.

Though combination antiretroviral therapy reduces the concentration of HIV-1 RNA in both plasma and cerebrospinal fluid (CSF) below the detection limit of clinical assays, low levels of HIV-1 RNA are frequently detectable in plasma using more sensitive assays. We examined the frequency and magnitude of persistent low-level HIV-1 RNA in CSF and its relation to the central nervous system (CNS) immune activation. CSF and plasma HIV-1 RNA were measured using the single-copy assay with a detection limit of 0.3 copies/ml in 70 CSF and 68 plasma samples from 45 treated HIV-1-infected patients with less than 40 copies/ml of HIV-1 RNA in both fluids by standard clinical assays. We also measured CSF neopterin to assess intrathecal immune activation. Theoretical drug exposure was estimated using the CNS penetration-efficacy score of treatment regimens. CSF HIV-1 RNA was detected in 12 of the 70 CSF samples (17%) taken after up to 10 years of suppressive therapy, compared to 39 of the 68 plasma samples (57%) with a median concentration of less than 0.3 copies/ml in CSF compared to 0.3 copies/ml in plasma (P < 0.0001). CSF samples with detectable HIV-1 RNA had higher CSF neopterin levels (mean 8.2 compared to 5.7 nmol/l; P = 0.0085). Patients with detectable HIV-1 RNA in CSF did not differ in pretreatment plasma HIV-1 RNA levels, nadir CD4 cell count or CNS penetration-efficacy score. Low-level CSF HIV-1 RNA and its association with elevated CSF neopterin highlight the potential for the CNS to serve as a viral reservoir and for persistent infection to cause subclinical CNS injury.

Peripheral Neuropathy in Primary HIV Infection Associates With Systemic and Central Nervous System Immune Activation

Peripheral neuropathy (PN) is a frequent complication of chronic HIV infection. We prospectively studied individuals with primary HIV infection (<1 year after transmission) to assess the presence of and laboratory associations with PN in this early stage. Standardized examination and analysis of blood and cerebrospinal fluid (CSF) was performed in participants with laboratory-confirmed primary HIV infection. PN was defined as ≥1 of the following unilateral or bilateral signs: decreased distal limb position, vibration, or temperature sense or hyporeflexia; symptomatic PN (SPN) was defined as the presence of these signs with symptoms. Analysis used nonparametric statistics. Overall, 20 (35%) of 58 antiretroviral-naive male subjects without diabetes evaluated at a median of 107 days post HIV transmission met criteria for PN. Thirteen (65%) of 20 PN subjects met criteria for SPN; 6 (30%) of 20 had bilateral findings. PN subjects and no PN subjects (NPN) did not differ in median age, days post HIV transmission, blood CD4 or CD8 counts, CSF or plasma HIV RNA levels, CSF white blood cell counts, or CSF to blood albumin ratio. PN and SPN subjects had elevated CSF neopterin (P = 0.003 and P = 0.0005), CSF monocyte chemoattractant protein-1 (P = 0.006 and P = 0.01), and blood neopterin (P = 0.006 and P = 0.009) compared with NPN subjects. PN subjects had a higher percentage of activated phenotype CSF CD8 T lymphocytes than NPN subjects (P = 0.009). Signs of PN were detected by detailed neurologic examination in 35% of men enrolled in a neurological study at a median of 3.5 months after HIV transmission. PN during this early period may be mediated by systemic and nervous system immune responses to HIV.

Effect of protein binding on unbound atazanavir and darunavir cerebrospinal fluid concentrations

HIV-1 protease inhibitors (PIs) exhibit different protein binding affinities and achieve variable plasma and tissue concentrations. Degree of plasma protein binding may impact central nervous system penetration. This cross-sectional study assessed cerebrospinal fluid (CSF) unbound PI concentrations, HIV-1 RNA, and neopterin levels in subjects receiving either ritonavir-boosted darunavir (DRV), 95% plasma protein bound, or atazanavir (ATV), 86% bound. Unbound PI trough concentrations were measured using rapid equilibrium dialysis and liquid chromatography/tandem mass spectrometry. Plasma and CSF HIV-1 RNA and neopterin were measured by Ampliprep/COBAS® Taqman® 2.0 assay (Roche) and enzyme-linked immunosorbent assay (ALPCO), respectively. CSF/plasma unbound drug concentration ratio was higher for ATV, 0.09 [95% confidence interval (CI) 0.06-0.12] than DRV, 0.04 (95%CI 0.03-0.06). Unbound CSF concentrations were lower than protein adjusted wild-type inhibitory concentration-50 (IC50 ) in all ATV and 1 DRV-treated subjects (P < 0.001). CSF HIV-1 RNA was detected in 2/15 ATV and 4/15 DRV subjects (P = 0.65). CSF neopterin levels were low and similar between arms. ATV relative to DRV had higher CSF/plasma unbound drug ratio. Low CSF HIV-1 RNA and neopterin suggest that both regimens resulted in CSF virologic suppression and controlled inflammation.