Magnus Gisslén

HIV-1 Viral Escape in Cerebrospinal Fluid of Subjects on Suppressive Antiretroviral Treatment

BACKGROUND Occasional cases of viral escape in cerebrospinal fluid (CSF) despite suppression of plasma human immunodeficiency virus type 1 (HIV-1) RNA have been reported. We investigated CSF viral escape in subjects treated with commonly used antiretroviral therapy regimens in relation to intrathecal immune activation and central nervous system penetration effectiveness (CPE) rank. METHODS Sixty-nine neurologically asymptomatic subjects treated with antiretroviral therapy >6 months and plasma HIV-1 RNA <50 copies/mL were cross-sectionally included in the analysis. Antiretroviral therapy regimens included efavirenz, lopinavir/ritonavir or atazanavir/ritonavir combined with tenofovir, abacavir, or zidovudine and emtricitabine or lamivudine. HIV-1 RNA was analyzed with real-time polymerase chain reaction assays. Neopterin was analyzed by enzyme-linked immunosorbent assay. RESULTS Seven (10%) of the 69 subjects had detectable CSF HIV-1 RNA, in median 121 copies/mL (interquartile range, 54-213 copies/mL). Subjects with detectable CSF virus had significantly higher CSF neopterin and longer duration of treatment. Previous treatment interruptions were more common in subjects with CSF escape. Central nervous system penetration effectiveness rank was not a significant predictor of detectable CSF virus or CSF neopterin levels. CONCLUSIONS Viral escape in CSF is more common than previously reported, suggesting that low-grade central nervous system infection may continue in treated patients. Although these findings need extension in longitudinal studies, they suggest the utility of monitoring CSF responses, as new treatment combinations and strategies modify clinical practice.

HIV-1 infection and cognitive impairment in the cART era: a review.

With the introduction of combination antiretroviral therapy AIDS dementia complex or HIV-associated dementia, as it was termed later, largely disappeared in clinical practice. However, in the past few years, patients, long-term infected and treated, including those with systemically well controlled infection, started to complain about milder memory problems and slowness, difficulties in concentration, planning, and multitasking. Neuropsychological studies have confirmed that cognitive impairment occurs in a substantial (15-50%) proportion of patients. Among HIV-1-infected patients cognitive impairment was and is one of the most feared complications of HIV-1 infection. In addition, neurocognitive impairment may affect adherence to treatment and ultimately result in increased morbidity for systemic disease. So what may be going on in the CNS after so many years of apparently controlled HIV-1 infection is an urgent and important challenge in the field of HIV medicine. In this review we summarize the key currently available data. We describe the clinical neurological and neuropsychological findings, the preferred diagnostic approach with new imaging techniques and cerebrospinal fluid analysis. We try to integrate data on pathogenesis and finally discuss possible therapeutic interventions.

Immune Activation of the Central Nervous System Is Still Present after 4 Years of Effective Highly Active Antiretroviral Therapy

Highly active antiretroviral therapy (HAART) effectively reduces human immunodeficiency virus (HIV) RNA in cerebrospinal fluid (CSF), as well as in plasma. The effect on intrathecal immunoactivation is less well studied. We had earlier found that a substantial number of patients still have evidence of intrathecal immunoactivation after up to 2 years of treatment. We identified 15 patients treated with HAART for > or =4 years who had plasma HIV-RNA levels of <50 copies/mL for > or =3.5 years. CSF samples were available from 10 patients before treatment. We measured white-blood-cell count, HIV-RNA level, neopterin level, and IgG index. During treatment, all patients had HIV-RNA levels of <50 copies/mL in plasma and CSF. In CSF, both neopterin level and IgG index decreased significantly. After 4 years, 9 (60%) of the 15 patients still had neopterin levels in CSF that were above the upper normal reference value (5.8 nmol/L). During HAART, 9 (60%) of the 15 patients had an abnormal IgG index (>0.63). HAART significantly decreases intrathecal immunoactivation, but, despite effective treatment for >4 years, with HIV-RNA levels <50 copies/mL for > or =3.5 years, a substantial proportion of patients continue to show signs of macrophage/microglia activation and intrathecal immunoglobulin production in the CNS.

Cerebrospinal fluid neopterin: an informative biomarker of central nervous system immune activation in HIV-1 infection.

HIV-1 invades the central nervous system (CNS) in the context of acute infection, persists thereafter in the absence of treatment, and leads to chronic intrathecal immunoactivation that can be measured by the macrophage activation marker, neopterin, in cerebrospinal fluid (CSF). In this review we describe our experience with CSF neopterin measurements in 382 untreated HIV-infected patients across the spectrum of immunosuppression and HIV-related neurological diseases, in 73 untreated AIDS patients with opportunistic CNS infections, and in 233 treated patients.In untreated patients, CSF neopterin concentrations are almost always elevated and increase progressively as immunosuppression worsens and blood CD4 cell counts fall. However, patients with HIV dementia exhibit particularly high CSF neopterin concentrations, above those of patients without neurological disease, though patients with CNS opportunistic infections, including CMV encephalitis and cryptococcal meningitis, also exhibit high levels of CSF neopterin. Combination antiretroviral therapy, with its potent effect on CNS HIV infection and CSF HIV RNA, mitigates both intrathecal immunoactivation and lowers CSF neopterin. However, despite suppression of plasma and CSF HIV RNA to below the detection limits of clinical assays (<50 copies HIV RNA/mL), CSF neopterin often remains mildly elevated, indicating persistent low-level intrathecal immune activation and raising the important questions of whether this elevation is driven by continued CNS infection and whether it causes continued indolent CNS injury.Although nonspecific, CSF neopterin can serve as a useful biomarker in the diagnosis of HIV dementia in the setting of confounding conditions, in monitoring the CNS inflammatory effects of antiretroviral treatment, and give valuable information to the cause of ongoing brain injury.

Cerebrospinal fluid HIV escape associated with progressive neurologic dysfunction in patients on antiretroviral therapy with well controlled plasma viral load.

Objective:To characterize HIV-infected patients with neurosymptomatic cerebrospinal fluid (CSF) ‘escape’, defined as detectable CSF HIV RNA in the setting of treatment-suppressed plasma levels or CSF RNA more than 1-log higher than plasma RNA. Design:Retrospective case series. Setting:Four urban medical centers in the United States and Europe. Participants:Virologically controlled HIV-infected patients on antiretroviral therapy (ART) with progressive neurologic abnormalities who were determined to have CSF ‘escape’. Intervention:Optimization of ART based upon drug susceptibility and presumed central nervous system exposure. Main outcome measures:Levels of CSF HIV RNA and inflammatory markers, clinical signs and symptoms, and MRI findings. Results:Ten patients presented with new neurologic abnormalities, which included sensory, motor, and cognitive manifestations. Median CSF HIV RNA was 3900 copies/ml (range 134–9056), whereas median plasma HIV RNA was 62 copies/ml (range <50 to 380). Median CD4+ T-cell count was 482 cells/&mgr;l (range 290–660). All patients had been controlled to less than 500 copies/ml for median 27.5 months (range 2–96) and five of 10 had been suppressed to less than 50 copies/ml for median 19.5 months (range 2–96). Patients had documentation of a stable ART regimen for median 21 months (range 9–60). All had CSF pleocytosis or elevated CSF protein; seven of eight had abnormalities on MRI; and six of seven harbored CSF resistance mutations. Following optimization of ART, eight of nine patients improved clinically. Conclusion:The development of neurologic symptoms in patients on ART with low or undetectable plasma HIV levels may be an indication of CSF ‘escape’. This study adds to a growing body of literature regarding this rare condition in well controlled HIV infection.

The definition of HIV-associated neurocognitive disorders: are we overestimating the real prevalence?

BackgroundA substantial prevalence of mild neurocognitive disorders has been reported in HIV, also in patients treated with combination antiretroviral therapy (cART). This includes a new disorder that has been termed asymptomatic neurocognitive impairment (ANI).DiscussionANI is identified by performance on formal neuropsychological testing that is at least 1 SD below the mean of normative scores in at least two cognitive domains out of at least five examined in patients without associated symptoms or evident functional impairment in daily living. While two tests are recommended to assess each domain, only one is required to fulfill this diagnostic criterion. Unfortunately, this definition necessitates that about 20% of the cognitively normal HIV-infected population is classified as suffering ANI. This liberal definition raises important ethical concerns and has as well diagnostic and therapeutic implications. Since neither its biological substrate, prognostic significance nor therapeutic implications are clearly established, we recommend that this diagnosis be modified or applied cautiously.SummaryThe diagnoses of less severe forms of neurocognitive disorders in HIV relies on the outcomes of neuropsychological testing, and a high proportion of HIV-infected patients with effective cART may be classified as neurocognitively abnormal using the current criteria. The definition of ANI is not stringent, and results in approximately 20% of the population being classified as abnormal. To us this seems an unacceptable false-positive rate.Please see related article: http://www.biomedcentral.com/1741-7015/9/138

Cerebrospinal fluid and neuroimaging biomarker abnormalities suggest early neurological injury in a subset of individuals during primary HIV infection

BACKGROUND Cerebrospinal fluid (CSF) and neuroimaging abnormalities demonstrate neuronal injury during chronic AIDS, but data on these biomarkers during primary human immunodeficiency virus (HIV) infection is limited. METHODS We compared CSF concentrations of neurofilament light chain, t-tau, p-tau, amyloid precursor proteins, and amyloid-beta 42 in 92 subjects with primary HIV infection and 25 controls. We examined relationships with disease progression and neuroinflammation, neuropsychological testing, and proton-magnetic resonance spectroscopy (MRS)-based metabolites. RESULTS Neurofilament light chain was elevated in primary HIV infection compared with controls (P = .0004) and correlated with CSF neopterin (r = 0.38; P = .0005), interferon gamma-induced protein 10 (r = 0.39; P = .002), white blood cells (r = 0.32; P = .004), protein (r = 0.59; P < .0001), and CSF/plasma albumin ratio (r = 0.60; P < .0001). Neurofilament light chain correlated with decreased N-acteylaspartate/creatine and glutamate/creatine in the anterior cingulate (r = -0.35, P = .02; r = -0.40, P = .009, respectively), frontal white matter (r = -0.43, P = .003; r = -0.30, P = .048, respectively), and parietal gray matter (r = -0.43, P = .003; r = -0.47, P = .001, respectively). Beta-amyloid was elevated in the primary infection group (P = .0005) and correlated with time infected (r = 0.34; P = .003). Neither marker correlated with neuropsychological abnormalities. T-tau and soluble amyloid precursor proteins did not differ between groups. CONCLUSIONS Elevated neurofilament light chain and its correlation with MRS-based metabolites suggest early neuronal injury in a subset of participants with primary HIV infection through mechanisms involving central nervous system inflammation.

Central Nervous System Immune Activation Characterizes Primary Human Immunodeficiency Virus 1 Infection Even in Participants With Minimal Cerebrospinal Fluid Viral Burden

BACKGROUND Central nervous system (CNS) human immunodeficiency virus (HIV) infection and immune activation lead to brain injury and neurological impairment. Although HIV enters the nervous system soon after transmission, the magnitude of infection and immunoactivation within the CNS during primary HIV infection (PHI) has not been characterized. METHODS This cross-sectional study analyzed cerebrospinal fluid (CSF) and blood from 96 participants with PHI and compared them with samples from neuroasymptomatic participants with chronic infection and ≥ 200 or < 200 blood CD4 T cells/μL, and with samples from HIV-seronegative participants with respect to CSF and plasma HIV RNA, CSF to serum albumin ratio, and CSF white blood cell counts (WBC), neopterin levels, and concentrations of chemokines CXCL10 and CCL2. RESULTS The PHI participants (median 77 days post transmission) had CSF HIV RNA, WBC, neopterin, and CXCL10 concentrations similar to the chronic infection participants but uniquely high albumin ratios. 18 participants had ≤ 100 copies/mL CSF HIV RNA, which was associated with low CSF to plasma HIV ratios and levels of CSF inflammation lower than in other PHI participants but higher than in HIV-seronegative controls. CONCLUSIONS Prominent CNS infection and immune activation is evident during the first months after HIV transmission, though a proportion of PHI patients demonstrate relatively reduced CSF HIV RNA and inflammation during this early period.

Amyloid and tau cerebrospinal fluid biomarkers in HIV infection

BackgroundBecause of the emerging intersections of HIV infection and Alzheimers disease, we examined cerebrospinal fluid (CSF) biomarkers related of amyloid and tau metabolism in HIV-infected patients.MethodsIn this cross-sectional study we measured soluble amyloid precursor proteins alpha and beta (sAPPα and sAPPβ), amyloid beta fragment 1-42 (Aβ1-42), and total and hyperphosphorylated tau (t-tau and p-tau) in CSF of 86 HIV-infected (HIV+) subjects, including 21 with AIDS dementia complex (ADC), 25 with central nervous system (CNS) opportunistic infections and 40 without neurological symptoms and signs. We also measured these CSF biomarkers in 64 uninfected (HIV-) subjects, including 21 with Alzheimers disease, and both younger and older controls without neurological disease.ResultsCSF sAPPα and sAPPβ concentrations were highly correlated and reduced in patients with ADC and opportunistic infections compared to the other groups. The opportunistic infection group but not the ADC patients had lower CSF Aβ1-42 in comparison to the other HIV+ subjects. CSF t-tau levels were high in some ADC patients, but did not differ significantly from the HIV+ neuroasymptomatic group, while CSF p-tau was not increased in any of the HIV+ groups. Together, CSF amyloid and tau markers segregated the ADC patients from both HIV+ and HIV- neuroasymptomatics and from Alzheimers disease patients, but not from those with opportunistic infections.ConclusionsParallel reductions of CSF sAPPα and sAPPβ in ADC and CNS opportunistic infections suggest an effect of CNS immune activation or inflammation on neuronal amyloid synthesis or processing. Elevation of CSF t-tau in some ADC and CNS infection patients without concomitant increase in p-tau indicates neural injury without preferential accumulation of hyperphosphorylated tau as found in Alzheimers disease. These biomarker changes define pathogenetic pathways to brain injury in ADC that differ from those of Alzheimers disease.

Plasma Concentration of the Neurofilament Light Protein (NFL) is a Biomarker of CNS Injury in HIV Infection: A Cross-Sectional Study

Background Cerebrospinal fluid (CSF) neurofilament light chain protein (NFL) is a sensitive marker of neuronal injury in a variety of neurodegenerative conditions, including the CNS dysfunction injury that is common in untreated HIV infection. However, an important limitation is the requirement for lumbar puncture. For this reason, a sensitive and reliable blood biomarker of CNS injury would represent a welcome advance in both clinical and research settings. Methods To explore whether plasma concentrations of NFL might be used to detect CNS injury in HIV infection, an ultrasensitive Single molecule array (Simoa) immunoassay was developed. Using a cross-sectional design, we measured NFL in paired CSF and plasma samples from 121 HIV-infected subjects divided into groups according to stage of their systemic disease, presence of overt HIV-associated dementia (HAD), and after antiretroviral treatment (ART)-induced viral suppression. HIV-negative controls were also examined. Findings Plasma and CSF NFL concentrations were very highly correlated (r = 0.89, P < 0.0001). While NFL was more than 50-fold lower plasma than CSF it was within the quantifiable range of the new plasma assay in all subjects, including the HIV negatives and the HIV positives with normal CSF NFL concentrations. The pattern of NFL changes were almost identical in plasma and CSF, both exhibiting similar age-related increases in concentrations along with highest values in HAD and substantial elevations in ART-naïve neuroasymptomatic subjects with low blood CD4+ T cells. Interpretation These results show that plasma NFL may prove a valuable tool to evaluate ongoing CNS injury in HIV infection that may be applied in the clinic and in research settings to assess the presence if active CNS injury. Because CSF NFL is also elevated in a variety of other CNS disorders, sensitive measures of plasma NFL may similarly prove useful in other settings.