Jennifer Marquie-Beck

Validation of the CNS Penetration-Effectiveness Rank for Quantifying Antiretroviral Penetration Into the Central Nervous System

OBJECTIVE To evaluate whether penetration of a combination regimen into the central nervous system (CNS), as estimated by the CNS Penetration-Effectiveness (CPE) rank, is associated with lower cerebrospinal fluid (CSF) viral load. DESIGN Data were analyzed from 467 participants who were human immunodeficiency virus (HIV) seropositive and who reported antiretroviral (ARV) drug use. Individual ARV drugs were assigned a penetration rank of 0 (low), 0.5 (intermediate), or 1 (high) based on their chemical properties, concentrations in CSF, and/or effectiveness in the CNS in clinical studies. The CPE rank was calculated by summing the individual penetration ranks for each ARV in the regimen. RESULTS The median CPE rank was 1.5 (interquartile range, 1-2). Lower CPE ranks correlated with higher CSF viral loads. Ranks less than 2 were associated with an 88% increase in the odds of detectable CSF viral load. In multivariate regression, lower CPE ranks were associated with detectable CSF viral loads even after adjusting for total number of ARV drugs, ARV drug adherence, plasma viral load, duration and type of the current regimen, and CD4 count. CONCLUSIONS Poorer penetration of ARV drugs into the CNS appears to allow continued HIV replication in the CNS as indicated by higher CSF HIV viral loads. Because inhibition of HIV replication in the CNS is probably critical in treating patients who have HIV-associated neurocognitive disorders, ARV treatment strategies that account for CNS penetration should be considered in consensus treatment guidelines and validated in clinical studies.

Hepatitis C augments cognitive deficits associated with HIV infection and methamphetamine

Objective: To examine the contribution of hepatitis C virus (HCV) infection to neurocognitive dysfunction in individuals with comorbid HIV infection or methamphetamine (METH) dependence. Methods: Neurocognitive functioning was examined in 430 study participants who were either normal controls or had HCV infection, HIV infection, history of METH dependence, or combinations of these factors as risks for cognitive deficits. Results: Rates of global and domain-specific neuropsychological (NP) impairment increased with the number of risk factors. HCV serostatus was a significant predictor of NP performance both globally and in the areas of learning, abstraction, and motor skills, with trends in speeded information processing and delayed recall. HCV serostatus did not predict scores in attention/working memory or verbal fluency. Conclusion: Hepatitis C virus infection contributes to the neuropsychological deficits observed among HIV-infected and stimulant-dependent populations.

Genetic Composition of Human Immunodeficiency Virus Type 1 in Cerebrospinal Fluid and Blood without Treatment and during Failing Antiretroviral Therapy

ABSTRACT Human immunodeficiency virus (HIV) infection of the central nervous system (CNS) is a significant cause of morbidity. The requirements for HIV adaptation to the CNS for neuropathogenesis and the value of CSF virus as a surrogate for virus activity in brain parenchyma are not well established. We studied 18 HIV-infected subjects, most with advanced immunodeficiency and some neurocognitive impairment but none with evidence of opportunistic infection or malignancy of the CNS. Clonal sequences of C2-V3 env and population sequences of pol from HIV RNA in cerebrospinal fluid (CSF) and plasma were correlated with clinical and virologic variables. Most (14 of 18) subjects had partitioning of C2-V3 sequences according to compartment, and 9 of 13 subjects with drug resistance exhibited discordant resistance patterns between the two compartments. Regression analyses identified three to seven positions in C2-V3 that discriminated CSF from plasma HIV. The presence of compartmental differences at one or more of the identified positions in C2-V3 was highly associated with the presence of discordant resistance (P = 0.007), reflecting the autonomous replication of HIV and the independent evolution of drug resistance in the CNS. Discordance of resistance was associated with severity of neurocognitive deficits (P = 0.07), while low nadir CD4 counts were linked both to the severity of neurocognitive deficits and to discordant resistance patterns (P = 0.05 and 0.09, respectively). These observations support the study of CSF HIV as an accessible surrogate for HIV virions in the brain, confirm the high frequency of discordant resistance in subjects with advanced disease in the absence of opportunistic infection or malignancy of the CNS, and begin to identify genetic patterns in HIV env associated with adaptation to the CNS.

The effects of hepatitis C, HIV, and methamphetamine dependence on neuropsychological performance : biological correlates of disease

Objective:To determine the effects of hepatitis C virus (HCV) infection on neuropsychological (NP) performance. Design:Cross-sectional analysis of a prospectively enrolled cohort. Methods:A total of 239 HIV-seropositive and 287 HIV-seronegative subjects enrolled in prospective cohort studies at a single center. Subjects underwent standardized assessments, including comprehensive neuropsychological testing, substance use inventory neuromedical examination, venipuncture, and lumbar puncture. HCV antibody was measured in serum. In seropositive individuals, HCV RNA was measured in plasma and cerebrospinal fluid (CSF). Results:HCV-seropositive subjects performed worse on neuropsychological testing and were almost twice as likely to be diagnosed as globally impaired, compared with those who were HCV seronegative. In a multivariate analysis, HCV, HIV, and methamphetamine dependence were independently associated with worse performance, even after adjusting for Centers for Disease Control stage and antiretroviral use. HCV-RNA levels in plasma were higher in those with memory, but not global, impairment. In cerebrospinal fluid, HCV RNA was below 100 copies/ml in all specimens. In HIV-infected subjects, HCV was associated with higher levels of HIV RNA in CSF, but not in plasma. HCV was also associated with higher levels of monocyte chemotactic protein 1, TNF-α, and soluble TNF receptor II. HCV-seropositive subjects did not appear to have advanced liver disease. Conclusions:HIV, HCV, and methamphetamine independently injure the central nervous system, leading to global neuropsychological impairment. HCV may injure the brain by viral or immune-mediated mechanisms. HCV-associated brain injury may be preventable or reversible because HCV infection is potentially curable.

Lopinavir concentrations in cerebrospinal fluid exceed the 50% inhibitory concentration for HIV.

Introduction:Lopinavir (LPV) is highly bound to plasma proteins and is a substrate for active drugs transporters, which may greatly limit the access of LPV to the central nervous system (CNS). However, even low lopinavir concentrations may be sufficient to inhibit HIV replication. Prior anecdotal reports indicated that lopinavir concentrations were below detection in cerebrospinal fluid (CSF). Methods:LPV was measured by liquid chromatography/mass spectrometry in 31 CSF–plasma pairs from 26 HIV-infected individuals who were taking LPV-containing antiretroviral regimens. The lower limit of quantification was 3.7 μg/l. Results:Seven of the sample pairs had very low plasma (and CSF) LPV concentrations, with a mean estimated plasma trough of 274 μg/l (range, < 3.7 to 608; typical trough values ∼4000 μg/l), suggesting poor recent adherence. In the remaining 24 sample pairs, the median LPV concentration was 5889 μg/l [interquartile range (IQR), 4805–9620] and all CSF samples had measurable LPV concentrations: median 17.0 μg/l (IQR, 12.1–22.7). The median CSF–plasma ratio was 0.23% (range, 0.12–0.75). All CSF concentrations in these samples were more than double the 50% inhibitory concentration for wild-type HIV virus. Conclusions:In patients with typical plasma levels of LPV, the drug is detectable in the CSF at concentrations that exceed those needed to inhibit HIV replication. Despite being > 98% bound to plasma proteins, LPV penetrates into the CNS and may contribute to the control of HIV in this potential reservoir.

Role of obesity, metabolic variables, and diabetes in HIV-associated neurocognitive disorder

Objective: To evaluate relationships between HIV-associated neurocognitive disorder and metabolic variables in a subgroup of HIV+ participants examined in a prospective, observational, multicenter cohort study. Methods: In a cross-sectional substudy of the CNS HIV Anti-Retroviral Therapy Effects Research (CHARTER) cohort, 130 HIV+ participants provided fasting blood samples. Neurocognitive impairment (NCI) was defined by performance on neuropsychological tests adjusting for age, education, gender, and race/ethnicity. Global ratings and global deficit scores were determined. Demographics, biomarkers of HIV disease, metabolic variables, combination antiretroviral therapy (CART) history, other drug exposures, and self-reported diabetes were examined in multivariate models predicting NCI. Separate models were used for body mass index (BMI) alone (n = 90) and BMI and waist circumference (WC) together (n = 55). Results: NCI (global impairment rating ≥5) was diagnosed in 40%. In univariate analyses, age, longer duration of HIV infection, obesity, and WC, but not BMI, were associated with NCI. Self-reported diabetes was associated with NCI in the substudy and in those >55 in the entire CHARTER cohort. Multivariate logistic regression analyses demonstrated that central obesity (as measured by WC) increased the risk of NCI and that greater body mass may be protective if the deleterious effect of central obesity is accounted for. Conclusions: As in HIV-uninfected persons, central obesity, but not more generalized increases in body mass (BMI), was associated with a higher prevalence of NCI in HIV+ persons. Diabetes appeared to be associated with NCI only in older patients. Avoidance of antiretroviral drugs that induce central obesity might protect from or help to reverse neurocognitive impairment in HIV-infected persons.

Relationship of antiretroviral treatment to postmortem brain tissue viral load in human immunodeficiency virus–infected patients

Human immunodeficiency virus (HIV)-1 invades the central nervous system (CNS) soon after infection and is partially protected there from host immunity and antiretroviral drugs (ARVs). Sanctuary from highly active antiretroviral therapy (HAART) in the CNS could result in ongoing viral replication, promoting the development of drug resistance and neurological disease. Despite the importance of these risks, no previous study has directly assessed HAART’s effects on brain tissue viral load (VL). The authors evaluated 61 HIV-infected individuals for whom both histories of HAART treatment and postmortem brain tissue VL measurements were available. Two groups were defined based on HAART use in the 3 months prior to death: HAART(+) subjects had received HAART, and HAART(−) subjects had not received HAART. HIV RNA was quantified in postmortem brain tissue (log10 copies/10 μg total tissue RNA) and antemortem plasma (log10 copies/ml) by reverse transcriptase—polymerase chain reaction (RT-PCR). Brain tissue VLs were significantly lower among HAART(+) subjects compared to HAART(−) subjects (median 2.6 versus 4.1; P = .0007). These findings suggest that despite the limited CNS penetration of many antiretroviral medications, HAART is at least partially effective in suppressing CNS viral replication. Because some HAART regimens may be better than others in this regard, regimen selection strategies could be used to impede CNS viral activity, limit neuronal dysfunction, and prevent or treat clinical neurocognitive disorders in HIV-infected patients. Furthermore, such strategies might help to prevent the development of ARV resistance.

Chemokines in cerebrospinal fluid correlate with cerebral metabolite patterns in HIV-infected individuals

Chemokines influence HIV neuropathogenesis by affecting the HIV life cycle, trafficking of macrophages into the nervous system, glial activation, and neuronal signaling and repair processes; however, knowledge of their relationship to in vivo measures of cerebral injury is limited. The primary objective of this study was to determine the relationship between a panel of chemokines in cerebrospinal fluid (CSF) and cerebral metabolites measured by proton magnetic resonance spectroscopy (MRS) in a cohort of HIV-infected individuals. One hundred seventy-one stored CSF specimens were assayed from HIV-infected individuals who were enrolled in two ACTG studies that evaluated the relationship between neuropsychological performance and cerebral metabolites. Concentrations of six chemokines (fractalkine, IL-8, IP-10, MCP-1, MIP-1β, and SDF-1) were measured and compared with cerebral metabolites individually and as composite neuronal, basal ganglia, and inflammatory patterns. IP-10 and MCP-1 were the chemokines most strongly associated with individual cerebral metabolites. Specifically, (1) higher IP-10 levels correlated with lower N-acetyl aspartate (NAA)/creatine (Cr) ratios in the frontal white matter and higher MI/Cr ratios in all three brain regions considered and (2) higher MCP-1 levels correlated with lower NAA/Cr ratios in frontal white matter and the parietal cortex. IP-10, MCP-1, and IL-8 had the strongest associations with patterns of cerebral metabolites. In particular, higher levels of IP-10 correlated with lower neuronal pattern scores and higher basal ganglia and inflammatory pattern scores, the same pattern which has been associated with HIV-associated neurocognitive disorders (HAND). Subgroup analysis indicated that the effects of IP-10 and IL-8 were influenced by effective antiretroviral therapy and that memantine treatment may mitigate the neuronal effects of IP-10. This study supports the role of chemokines in HAND and the validity of MRS as an assessment tool. In particular, the findings identify relationships between the immune response—particularly an interferon-inducible chemokine, IP-10—and cerebral metabolites and suggest that antiretroviral therapy and memantine modify the impact of the immune response on neurons.

Human Immunodeficiency Virus Protease Inhibitors and Risk for Peripheral Neuropathy

Two recent analyses found that exposure to protease inhibitors (PIs) in the context of antiretroviral (ARV) therapy increased the risk for distal sensory polyneuropathy (DSPN) in subjects with human immunodeficiency virus (HIV) infection. These findings were supported by an in vitro model in which PI exposure produced neurite retraction and process loss in dorsal root ganglion sensory neurons. Confirmation of peripheral nerve toxicity with PIs could substantially limit their long‐term use in highly active ARV therapy.

Incidence of Post‐Dural Puncture Headache in Research Volunteers

Objective.— To determine the frequency and risk factors of post‐dural puncture headache (PDPH) in research volunteers.