Cerebrospinal fluid HIV infection and pleocytosis: relation to systemic infection and antiretroviral treatment

Effects of antiretroviral therapy on cognitive impairment

Since the introduction of combination antiretroviral therapy, the manifestations of HIV-associated central nervous system (CNS) involvement have generally become less severe and more manageable. Patients initiating antiretroviral therapy have demonstrated improvement in cognitive functioning. Reduction of viral burden has been correlated with improved CNS functioning. Recent studies have focused on the importance of CNS-penetrating antiretroviral regimens to target active replication in this protected compartment. There were initial conflicting reports of whether CNS-penetrating antiretrovirals improved cognitive functioning, with more evidence supporting the importance of CNS penetration in reducing viral burden and improving cognitive outcomes. Cognitive loss remains a feature of HIV infection, and some patients still suffer from incident or progressing cognitive and motor dysfunction even on combination therapy. Because the virus enters the CNS within days of initial infection, latent infection may be chipping away at the brain during the long asymptomatic period in HIV. When to start antiretrovirals for the maximum cognitive benefit remains to be determined.

Nerve growth factor stimulation promotes CXCL-12 attraction of monocytes but decreases human immunodeficiency virus replication in attracted population

The neurotrophins nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF), neurotrophin-3 (NT-3), and neurotrophin-4 (NT-4) are key molecules in the central nervous system development, which also exert specific effects on cells of the immune system. With regard to the latter, in vitro as well as in vivo data suggested that neurotrophins may play a role in human immunodeficiency virus (HIV) infection, especially in perivascular spaces where infiltrated macrophages express NGF. In the present study, we examined the expression of neurotrophins and their receptors in human monocyte-derived macrophages (MDMs) during infection by the R5 prototype HIV1/Ba-L strain. We then assessed to what extent neurotrophins themselves modulate infected macrophage survival and the level of virus production. The data show that neurotrophins and neurotrophin receptors are not modulated during HIV replication. Likewise, exogenous neurotrophins, or alternatively the blocking of neurotrophin receptors, neither modulated MDM sensitivity to HIV infection and replication nor altered their viability. In contrast, NGF clearly increased CD184 expression in macrophages, but this did not sensitize them to the X4 isolate HIV-1/Lai infection. Nevertheless, NGF enhanced monocyte chemotactic response to low CXCL-12 concentration regardless of infection. Surprisingly, CXCL-12-attracted monocytes from NGF-stimulated, HIV-infected cultures produced decreased amounts of virus progeny than their non-NGF-stimulated counterparts. This suggests a preferential effect on uninfected monocytes. Together these findings suggest a role for NGF in the continuous attraction of activated monocytes to the perivascular spaces, contributing to the chronic inflammatory state rather than neuroinvasion by HIV.

OTK18 levels in plasma and cerebrospinal fluid correlate with viral load and CD8 T-cells in normal and AIDS patients

OTK18 is a C2H2 type zinc finger protein expressed by human macrophages following HIV infection. OTK18 possesses antiretroviral activity, and its processing products accumulate in the cytoplasm of perivascular brain macrophages in advanced HIV encephalitis cases. Since the regulation of OTK18 expression in living patients following human immunodeficiency virus-1 (HIV-1) infection is unknown, our objective is to investigate the first cohort study on OTK18 protein levels in living patients. We assessed OTK18 levels in plasma and cerebrospinal fluid (CSF) in 44 living patients with or without HIV-1 infection, with diverse demographic and clinical background. A novel high-sensitivity OTK18 ELISA system was developed to measure OTK18 levels in CSF and plasma using custom made biotinylated monoclonal antibodies against OTK18. The correlation of OTK18 levels with epidemiological parameters was statistically analyzed. Multiple linear regression modeling suggested that plasma OTK18 levels for HIV-1-positive subjects were only about one sixth of that for HIV-1-negative subjects. Higher CD8 T-cell counts were associated with higher levels of OTK18. Using proportional odds logistic regression, we showed that HIV-1-positive patients have significantly lower OTK18 in CSF samples, but we did not observe significant correlation between CD8 T-cell counts and CSF OTK18 levels. OTK18 levels in both plasma and CSF are significantly lower in HIV-1-positive subjects as compared to HIV-1-negative subjects. Plasma OTK18 levels are positively correlated to CD8 T-cell counts, independent of HIV-1 status.

Antiretroviral therapy and central nervous system HIV type 1 infection

Central nervous system (CNS) human immunodeficiency virus type 1 (HIV-1) infection begins during primary viremia and continues throughout the course of untreated systemic infection. Although frequently accompanied by local inflammatory reactions detectable in cerebrospinal fluid (CSF), CNS HIV-1 infection usually is not clinically apparent. In a minority of patients, CNS HIV-1 infection evolves into encephalitis during the late stages of systemic infection, which compromises brain function and presents clinically as acquired immunodeficiency syndrome dementia complex (ADC). Combination antiretroviral therapy (ART) has had a major impact on all aspects of CNS HIV-1 infection and disease. In those with asymptomatic infection, ART usually effectively suppresses HIV-1 in CSF and markedly reduces the incidence of symptomatic ADC. In those presenting with ADC, ART characteristically prevents neurological progression and leads to variable, and at times substantial, recovery. Similarly, treatment has reduced CNS opportunistic infections. With better control of these severe disorders, attention has turned to the possible consequences of chronic silent infection and the issue of whether indolent, low-grade brain injury might require earlier treatment intervention.

Antiretroviral treatment effect on immune activation reduces cerebrospinal fluid HIV-1 infection

OBJECTIVE

To define the effect of antiretroviral therapy (ART) on activation of T cells in cerebrospinal fluid (CSF) and blood, and interactions of this activation with CSF HIV-1 RNA concentrations.

DESIGN

Cross-sectional analysis of 14 HIV-negative subjects and 123 neuroasymptomatic HIV-1-infected subjects divided into 3 groups: not on ART (termed "offs"), on ART with plasma HIV-1 RNA >500 copies/mL ("failures"), and on ART with plasma HIV-1 RNA <or=500 copies/mL ("successes"). T-cell activation was measured by coexpression of CD38 and human leukocyte antigen DR (HLA-DR). Other measurements included CSF neopterin and white blood cell (WBC) counts.

RESULTS

CD8 T-cell activation in CSF and blood was highly correlated across all subjects and was highest in the offs, lower in the failures, and lower still in the successes. While CD8 activation was reduced in failures compared to offs across the range of plasma HIV-1, it maintained a coincident relation to CSF HIV-1 in both viremic groups. In addition to correlation with CSF HIV-1 concentrations, CD8 activation in blood and CSF correlated with CSF WBCs and CSF neopterin. Multivariate analysis confirmed the association of blood CD8 T-cell activation, along with plasma HIV-1 RNA and CSF neopterin, with CSF HIV-1 RNA levels.

CONCLUSIONS

The similarity of CD8 T-cell activation in blood and CSF suggests these cells move from blood to CSF with only minor changes in CD38/HLA-DR expression. Differences in the relation of CD8 activation to HIV-1 concentrations in the blood and CSF in the 2 viremic groups suggest that changes in immune activation not only modulate CSF HIV-1 replication but also contribute to CSF treatment effects. The magnitude of systemic HIV-1 infection and intrathecal macrophage activation are also important determinants of CSF HIV-1 RNA levels.

Cerebrospinal fluid viral load and intrathecal immune activation in individuals infected with different HIV-1 genetic subtypes

Background

HIV-1 exhibits a high degree of genetic diversity and is presently divided into 3 distinct HIV-1 genetic groups designated major (M), non-M/non-O (N) and outlier (O). Group M, which currently comprises 9 subtypes (A-D, F-H, J and K), at least 34 circulating recombinant forms (CRFs) and several unique recombinant forms (URFs) is responsible for most of the HIV-1 epidemic. Most of the current knowledge of HIV-1 central nervous system (CNS) infection is based on subtype B. However, subtypes other than subtype B account for the majority of global HIV-1 infections. Therefore, we investigated whether subtypes have any influence on cerebrospinal fluid (CSF) markers of HIV-1 CNS infection.

Methodology/Principal Findings

CSF HIV-1 RNA, CSF neopterin and CSF white blood cell (WBC) count were measured in patients infected with different HIV-1 subtypes. Using multivariate regression analysis, no differences in the CSF WBC count, neopterin and viral load were found between various HIV-1 subtypes.

Conclusions

We did not find any subtype-dependent differences in the markers evaluated in this study.

Enfuvirtide Cerebrospinal Fluid (CSF) Pharmacokinetics and Potential use in Defining CSF HIV-1 Origin

Background

Enfuvirtide is a potent inhibitor of systemic HIV-1 replication, but its penetration into the human central nervous system (CNS) has not been analysed. Here, we define cerebrospinal fluid (CSF) enfuvirtide pharmacokinetics and present a case illustrating the use of enfuvirtide as a probe to trace the origins of CSF HIV-1 quasispecies.

Methods

Enfuvirtide CSF pharmacokinetics were assessed in 18 CSF and plasma sample pairs from four HIV-1-infected individuals. Enfuvirtide levels were measured by liquid chromatography tandem mass spectrometry using known standards and controls that included spiked CSF samples from untreated, HIV-negative individuals. A segment of the gp41 coding region encompassing the heptad repeat HR-1 and HR-2 domains was amplified from selected CSF and plasma samples and independent clones sequenced to assess resistance-associated mutations.

Results

CSF and plasma samples obtained between 2 and 20 h after enfuvirtide injection showed plasma concentrations similar to previous reports (mean 3.687 SD ±1.828 mg/ml) with prolonged decay. By contrast, enfuvirtide in all CSF samples was below the assay detection limit of 0.025 mg/ml. In one individual, who developed a transient increase in CSF HIV-1 RNA, seven of seven CSF and plasma clones had identical enfuvirtide resistance-associated V38A mutations, suggesting that the CSF quasispecies derived from that of blood.

Conclusions

Enfuvirtide penetration into CSF is negligible; thus, in clinical settings, where direct CNS drug exposure is crucial, this drug Is not likely to directly contribute to the local therapeutic effect. Enfuvirtide can be used as a tool to dissect the origin of the CNS virus.

Enfuvirtide cerebrospinal fluid (CSF) pharmacokinetics and potential use in defining CSF HIV-1 origin

BACKGROUND

Enfuvirtide is a potent inhibitor of systemic HIV-1 replication, but its penetration into the human central nervous system (CNS) has not been analysed. Here, we define cerebrospinal fluid (CSF) enfuvirtide pharmacokinetics and present a case illustrating the use of enfuvirtide as a probe to trace the origins of CSF HIV-1 quasispecies.

METHODS

Enfuvirtide CSF pharmacokinetics were assessed in 18 CSF and plasma sample pairs from four HIV-1-infected individuals. Enfuvirtide levels were measured by liquid chromatography tandem mass spectrometry using known standards and controls that included spiked CSF samples from untreated, HIV-negative individuals. A segment of the gp41 coding region encompassing the heptad repeat HR-1 and HR-2 domains was amplified from selected CSF and plasma samples and independent clones sequenced to assess resistance-associated mutations.

RESULTS

CSF and plasma samples obtained between 2 and 20 h after enfuvirtide injection showed plasma concentrations similar to previous reports (mean 3.687 SD +/- 1.828 mg/ml) with prolonged decay. By contrast, enfuvirtide in all CSF samples was below the assay detection limit of 0.025 mg/ml. In one individual, who developed a transient increase in CSF HIV-1 RNA, seven of seven CSF and plasma clones had identical enfuvirtide resistance-associated V38A mutations, suggesting that the CSF quasispecies derived from that of blood.

CONCLUSIONS

Enfuvirtide penetration into CSF is negligible; thus, in clinical settings, where direct CNS drug exposure is crucial, this drug Is not likely to directly contribute to the local therapeutic effect. Enfuvirtide can be used as a tool to dissect the origin of the CNS virus.

Factors influencing cerebrospinal fluid and plasma HIV-1 RNA detection rate in patients with and without opportunistic neurological disease during the HAART era

Background

In the central nervous system, HIV replication can occur relatively independent of systemic infection, and intrathecal replication of HIV-1 has been observed in patients with HIV-related and opportunistic neurological diseases. The clinical usefulness of HIV-1 RNA detection in the cerebrospinal fluid (CSF) of patients with opportunistic neurological diseases, or the effect of opportunistic diseases on CSF HIV levels in patients under HAART has not been well defined. We quantified CSF and plasma viral load in HIV-infected patients with and without different active opportunistic neurological diseases, determined the characteristics that led to a higher detection rate of HIV RNA in CSF, and compared these two compartments.

Methods

A prospective study was conducted on 90 HIV-infected patients submitted to lumbar puncture as part of a work-up for suspected neurological disease. Seventy-one patients had active neurological diseases while the remaining 19 did not.

Results

HIV-1 RNA was quantified in 90 CSF and 70 plasma samples. The HIV-1 RNA detection rate in CSF was higher in patients with neurological diseases, in those with a CD4 count lower than 200 cells/mm³, and in those not receiving antiretroviral therapy, as well as in patients with detectable plasma HIV-1 RNA. Median viral load was lower in CSF than in plasma in the total population, in patients without neurological diseases, and in patients with toxoplasmic encephalitis, while no significant difference between the two compartments was observed for patients with cryptococcal meningitis and HIV-associated dementia. CSF viral load was lower in patients with cryptococcal meningitis and neurotoxoplasmosis under HAART than in those not receiving HAART.

Conclusion

Detection of HIV-1 RNA in CSF was more frequent in patients with neurological disease, a CD4 count lower than 200 cells/mm³ and detectable plasma HIV-1. Median HIV-1 RNA levels were generally lower in CSF than in plasma but some patients showed higher CSF levels, and no difference between these two compartments was observed in patients with cryptococcal meningitis and HIV-associated dementia, suggesting the presence of intrathecal viral replication in these patients. HAART played a role in the control of CSF HIV levels even in patients with cryptococcal meningitis and neurotoxoplasmosis in whom viral replication is potentially higher.

Interpreting cerebrospinal fluid pleocytosis in HIV in the era of potent antiretroviral therapy

Background

Cerebrospinal fluid (CSF) pleocytosis may be seen in asymptomatic HIV-infected individuals. This finding complicates interpretation of CSF abnormalities when such individuals are evaluated for other central nervous system infections. The goal of this study was to determine the relationship between CSF pleocytosis, central nervous system (CNS) antiretroviral penetration, adherence to antiretroviral medication regimens, neurological symptoms and performance on neuropsychological tests.

Methods

Clinically stable HIV-infected individuals at any peripheral blood CD4+ T cell count or any plasma viral load were asked to attend study visits at entry and every 6 months thereafter for at least one year. At each visit, they underwent a standardized neurological and medication history; neurological examination; a brief neuropsychological test battery: venipuncture; lumbar puncture; and assessment of medication adherence. Generalized estimating equations (GEE) were used to assess the relationships between CSF pleocytosis and other variables.

Results

CSF pleocytosis was independently and significantly related to lack of current antiretroviral use (OR 5.9, 95% CI 1.8–18.6, p = 0.003), CD4 count > 200/ul (OR 23.4, 95% CI 3.1–177.3, p = 0.002) and detectable plasma HIV RNA (OR 3.3, 95% CI 1.1–9.4, p = 0.03). At visits where antiretrovirals were used, and taking into account detectable plasma HIV RNA, an antiretroviral regimen that contained two or more agents with good CNS penetration conferred a trend toward lower odds of CSF pleocytosis (OR 0.45, 95% CI 0.18–1.12, p = 0.087).

Conclusion

CSF pleocytosis is a characteristic of HIV disease that varies significantly with easily identifiable clinical and laboratory features. Use of antiretroviral agents decreases the odds of pleocytosis. This association may be stronger when the regimen contains two or more agents with good CNS penetration.

CSF neurofilament protein (NFL) — a marker of active HIV-related neurodegeneration

BACKGROUND AND METHODS

The light subunit of the neurofilament protein (NFL), a major structural component of myelinated axons, is a sensitive indicator of axonal injury in the central nervous system (CNS) in a variety of neurodegenerative disorders. Cerebrospinal fluid (CSF) NFL concentrations were measured by ELISA (normal < 250 ng/l) in archived samples from 210 HIV-infected patients not taking antiretroviral treatment: 55 with AIDS dementia complex (ADC), 44 with various CNS opportunistic infections/tumours (CNS OIs), 95 without neurological symptoms or signs, and 16 with primary HIV infection (PHI). The effect of highly active antiretroviral treatment (HAART) was studied by repeated CSF sampling in four of the ADC patients initiating treatment.

RESULTS

CSF NFL concentrations were significantly higher in patients with ADC (median 2590 ng/l, IQR 780-7360) and CNS OIs (2315 ng/l, 985-7390 ng/l) than in neuroasymptomatic patients (<250 ng/l, <250-300) or PHI (<250 ng/l, <250-280), p < 0.001. Among patients with ADC, those with more severe disease (stage 2-4) had higher levels than those with milder disease (stage 0.5-1), p < 0.01. CSF NFL declined during HAART to the limit of detection in parallel with virological response and neurological improvement in ADC.CSF NFL concentrations were higher in neuroasymptomatic patients with lower CD4-cell strata than higher, p < 0.001. This increase was less marked than in the ADC patients and noted in 26/58 neuroasymptomatic patients with CD4 counts <200/microl compared to 1/37 with CD4-cells > or =200/microl.

CONCLUSIONS

The findings of this study support the value of CSF NFL as a useful marker of ongoing CNS damage in HIV infection. Markedly elevated CSF NFL concentrations in patients without CNS OIs are associated with ADC, follow the grade of severity, and decrease after initiation of effective antiretroviral treatment. Nearly all previously suggested CSF markers of ADC relate to immune activation or HIV viral load that do not directly indicate brain injury. By contrast NFL is a sensitive marker of such injury, and should prove useful in evaluating the presence and activity of ongoing CNS injury in HIV infection.

[One episode of meningoencephalitis, three diagnoses]

Meningo-encephalitis is a set of threatening diseases. The treatment needs to be started quickly for pathogens such as herpes simplex virus type 1 or Listeria monocytogenes. Apart from these classical etiologies, many other diseases may induce meningo-encephalitis. We report the case of a patient, infected with HIV, who presented a history of meningo-encephalitis due to herpes simplex type 1. Three weeks later, he presented an encephalopathy due to aciclovir and then we discovered a chronic meningitis in relation with his HIV infection.

Viral load determines the B-cell response in the cerebrospinal fluid during human immunodeficiency virus infection

OBJECTIVE

Human immunodeficiency virus (HIV) infection of the central nervous system (CNS) is frequently associated with intrathecal immunoglobulin synthesis and cerebrospinal fluid (CSF) pleocytosis, but little is known about the B-cell response in the CSF of these patients. In this study, we investigated the relation between virus load and the frequency and phenotype of B cells in the CSF of HIV-infected patients.

METHODS

The distribution of T cells, B cells, short-lived plasmablasts, and long-lived plasma cells was analyzed by flow cytometry in CSF and peripheral blood of 33 patients with HIV infection compared with 12 patients with noninfectious CNS diseases. HIV RNA copy number in CSF and serum was quantified by kinetic polymerase chain reaction.

RESULTS

B-cell and plasmablast levels were increased in the CSF of HIV-infected patients compared with patients with noninfectious CNS diseases. Whereas CSF B cells were found at similar frequency during early and late stages of HIV infection, plasmablasts were more prevalent in the CSF during early infection. Plasmablasts in the CSF correlated with intrathecal IgG synthesis and even stronger with HIV RNA copy numbers in CSF, in particular, in untreated, early HIV-infected individuals. Initiation of antiviral treatment in therapy-naive patients strongly decreased HIV copy numbers and plasmablasts in CSF.

INTERPRETATION

Our findings demonstrate that HIV infection of the CNS triggers an early profound B-cell response, with plasmablasts serving as the main virus-related B-cell subset in the CSF.

Defining and evaluating HIV-related neurodegenerative disease and its treatment targets: a combinatorial approach to use of cerebrospinal fluid molecular biomarkers

There are a number of reasons that the accomplishments of clinical trials related to HIV-related neurodegenerative disease (HRND) and the AIDS dementia complex (ADC) have had such limited impact on clinical practice. These include: rapid evolution and progress in the treatment of systemic HIV infection that has quickly outpaced neurological efforts and has markedly reduced disease incidence; ethical constraints that (rightly) demand neurologically compromised patients receive the best available treatment before experimental therapeutics; complicated backgrounds and comorbidities of patients now most susceptible to HRND; and reluctance of general AIDS clinicians and drug companies to look beyond systemic or pivotal outcomes. However, the field has also been slow to adopt methods that better exploit advances in understanding of the pathogenesis of central nervous system (CNS) infection and brain injury, and that might circumvent some of these constraints. Using a simple model of pathogenesis, we propose an approach to characterizing patients, selecting treatment targets, and evaluating outcomes that emphasize a combination of cerebrospinal fluid (CSF) markers. This model begins by using three markers related to cardinal components of HRND: CNS HIV infection (measurement of CSF HIV RNA), intrathecal immunoactivation (CSF neopterin), and brain injury [CSF light chain neurofilament (NFL)]. Careful analysis of this and other marker combinations promises more rational trial design and more rapid progress in managing CNS HIV infection and HRND using both antiviral and adjuvant treatment approaches.

Cerebrospinal fluid HIV-1 RNA, intrathecal immunoactivation, and drug concentrations after treatment with a combination of saquinavir, nelfinavir, and two nucleoside analogues: the M61022 study

BACKGROUND

The way various antiretroviral drugs and drug combinations affect HIV-1 infection in the central nervous system is still largely unknown. The aim of this study was to determine the cerebrospinal fluid (CSF) steady-state concentrations of saquinavir and nelfinavir in relation to plasma concentrations, and to study their effect in combination with two nucleoside reverse transcriptase inhibitors (NRTIs) on CSF viral loads, intrathecal immunoactivation, and blood-brain barrier integrity.

METHODS

Paired CSF and plasma samples from 8 antiretroviral-naïve HIV-1 infected patients starting combination therapy with saquinavir, nelfinavir, and two nucleoside analogues were collected prior to treatment, and again after approximately 12 and 48 weeks of antiretroviral therapy. Additional plasma samples were taken at weeks 2, 4, 8, 24, and 36. The concentrations of protease inhibitors were analysed, as were levels of HIV-1 RNA, CD4+ T-cell count, beta2-microglobulin, neopterin, albumin ratio, IgG index, and monocytic cell count.

RESULTS

None of the patients in the study presented with HIV-1 RNA < 50 copies/mL in CSF or plasma prior to treatment, compared to 5/7 at the end of the study. Signs of cell-mediated intrathecal immunoactivation, measured by neopterin and beta2-microglobulin, decreased significantly in both CSF and serum, although only 1/7 reached normal CSF neopterin levels after 48 weeks of treatment. There was no significant reduction of albumin ratio, IgG index or CSF monocytic cell count. Saquinavir median (range) concentrations were < 2.5 (< 2.5-96.0) nM unbound in plasma, and < 2.5 (< 2.5-9.0) nM total in CSF. Nelfinavir median (range) concentrations were 10.0 (< 2.0-31.0) nM unbound in plasma, and < 2.0 (< 2.0-23.0) nM total in CSF. Saquinavir and nelfinavir were detectable in 7/15 and 9/15 CSF samples, respectively.

CONCLUSION

Saquinavir and nelfinavir, in combination with two NRTIs, decrease the CSF viral load and, to a lesser extent, intrathecal immunoactivation. We found reasonably high CSF concentrations of nelfinavir, but suboptimal concentrations of saquinavir.