Blood biomarkers for HIV infection with focus on neurologic complications-A review

Although clinical examinations, neuroimaging, and cerebrospinal fluid analyses are the most important ways to evaluate the impact of HIV infection on the brain and in diagnosis of opportunistic infections, several blood biomarkers including HIV RNA concentrations, CD4 +T-cell count, and neurofilament light chain protein (NfL) concentration, along with tests for opportunistic infections can provide important information for clinical decisions

Rebound of residual plasma viremia after initial decrease following addition of intravenous immunoglobulin to effective antiretroviral treatment of HIV

<p>Abstract</p> <p>Background</p> <p>High dosage of intravenous immunoglobulin (IVIG) has been observed as a possible activator of HIV gene expression in latently infected resting CD4⁺T-cells, leading to a substantial decrease in both the reservoir and the residual plasma viremia when added to effective ART. IVIG treatment has also been reported to expand T regulatory cells (Tregs). The aim of this study was to evaluate possible long-term effect of IVIG treatment on residual viremia and T-lymphocyte activation.</p> <p>Methods</p> <p>Nine HIV-infected subjects on effective ART included in a previously reported study on IVIG treatment were evaluated 48-104 weeks after therapy. In addition, 14 HIV-infected controls on suppressive ART were included. HIV-1 RNA was analyzed in cell-free plasma by using an ultrasensitive PCR-method with a detection limit of 2 copies/mL. T-lymphocyte activation markers and serum interleukins were measured.</p> <p>Results</p> <p>Plasma residual viremia rebounded to pre-treatment levels, 48-104 weeks after the initial decrease that was observed following treatment with high-dosage IVIG. No long-term effect was observed regarding T-lymphocyte activation markers, T-regulatory cells or serum interleukins. In a post-hoc analysis, a correlation between plasma HIV-1-RNA and CD4⁺T-cell count was found in both IVIG-treated patients and controls.</p> <p>Conclusions</p> <p>These results indicate that the decrease in the latent HIV-1 pool observed during IVIG treatment is transient. Although not our primary objective, we found a correlation between HIV-1 RNA and CD4⁺T-cell count suggesting the possibility that patients with a higher CD4⁺T-cell count might harbor a larger residual pool of latently infected CD4⁺T-cells.</p

Reduction of the HIV-1 reservoir in resting CD4+ T-lymphocytes by high dosage intravenous immunoglobulin treatment: a proof-of-concept study

<p>Abstract</p> <p>Background</p> <p>The latency of HIV-1 in resting CD4⁺T-lymphocytes constitutes a major obstacle for the eradication of virus in patients on antiretroviral therapy (ART). As yet, no approach to reduce this viral reservoir has proven effective.</p> <p>Methods</p> <p>Nine subjects on effective ART were included in the study and treated with high dosage intravenous immunoglobulin (IVIG) for five consecutive days. Seven of those had detectable levels of replication-competent virus in the latent reservoir and were thus possible to evaluate. Highly purified resting memory CD4⁺T-cells were activated and cells containing replication-competent HIV-1 were quantified. HIV-1 from plasma and activated memory CD4⁺T-cells were compared with single genome sequencing (SGS) of the <it>gag </it>region. T-lymphocyte activation markers and serum interleukins were measured.</p> <p>Results</p> <p>The latent HIV-1 pool decreased with in median 68% after IVIG was added to effective ART. The reservoir decreased in five, whereas no decrease was found in two subjects with detectable virus. Plasma HIV-1 RNA ≥ 2 copies/mL was detected in five of seven subjects at baseline, but in only one at follow-up after 8–12 weeks. The decrease of the latent HIV-1 pool and the residual plasma viremia was preceded by a transitory low-level increase in plasma HIV-1 RNA and serum interleukin 7 (IL-7) levels, and followed by an expansion of T regulatory cells. The magnitude of the viral increase in plasma correlated to the size of the latent HIV-1 pool and SGS of the <it>gag </it>region showed that viral clones from plasma clustered together with virus from activated memory T-cells, pointing to the latent reservoir as the source of HIV-1 RNA in plasma.</p> <p>Conclusion</p> <p>The findings from this uncontrolled proof-of-concept study suggest that the reservoir became accessible by IVIG treatment through activation of HIV-1 gene expression in latently-infected resting CD4⁺T-cells. We propose that IVIG should be further evaluated as an adjuvant to effective ART.</p

Cerebrospinal Fluid Viral Load Across the Spectrum of Untreated Human Immunodeficiency Virus Type 1 (HIV-1) Infection: A Cross-Sectional Multicenter Study

Background The aim of this large multicenter study was to determine variations in cerebrospinal fluid (CSF) HIV-RNA in different phases of untreated human immunodeficiency virus type 1 (HIV-1) infection and its associations with plasma HIV-RNA and other biomarkers. Methods Treatment naive adults with available CSF HIV-RNA quantification were included and divided into groups representing significant disease phases. Plasma HIV-RNA, CSF white blood cell count (WBC), neopterin, and albumin ratio were included when available. Results In total, 1018 patients were included. CSF HIV-RNA was in median (interquartile range [IQR]) 1.03 log(10) (0.37-1.86) copies/mL lower than in plasma, and correlated with plasma HIV-RNA (r = 0.44, P &lt; .01), neopterin concentration in CSF (r = 0.49, P &lt; .01) and in serum (r = 0.29, P &lt; .01), CSF WBC (r = 0.34, P &lt; .01) and albumin ratio (r = 0.25, P &lt; .01). CSF HIV-RNA paralleled plasma HIV-RNA in all groups except neuroasymptomatic patients with advanced immunodeficiency (CD4 &lt; 200) and patients with HIV-associated dementia (HAD) or opportunistic central nervous system (CNS) infections. Patients with HAD had the highest CSF HIV-RNA (in median [IQR] 4.73 (3.84-5.35) log(10) copies/mL). CSF &gt; plasma discordance was found in 126 of 972 individuals (13%) and varied between groups, from 1% in primary HIV, 11% in neuroasymptomatic groups, up to 30% of patients with HAD. Conclusions Our study confirms previous smaller observations of variations in CSF HIV-RNA in different stages of HIV disease. Overall, CSF HIV-RNA was approximately 1 log(10) copies/mL lower in CSF than in plasma, but CSF discordance was found in a substantial minority of subjects, most commonly in patients with HAD, indicating increasing CNS compartmentalization paralleling disease progression. HIV-RNA is detectable in cerebrospinal fluid (CSF) across all stages of untreated HIV and usually parallel plasma HIV-RNA at a lower level. A substantial proportion (13%) of patients have CSF&gt;plasma HIV-RNA, most commonly in patients with HIV-associated dementia

Viral Antigen and Inflammatory Biomarkers in Cerebrospinal Fluid in Patients With COVID-19 Infection and Neurologic Symptoms Compared With Control Participants Without Infection or Neurologic Symptoms

Importance: Neurologic symptoms are common in COVID-19, but the central nervous system (CNS) pathogenesis is unclear, and viral RNA is rarely detected in cerebrospinal fluid (CSF). / Objective: To measure viral antigen and inflammatory biomarkers in CSF in relation to neurologic symptoms and disease severity. Design, Setting, and / Participants: This cross-sectional study was performed from March 1, 2020, to June 30, 2021, in patients 18 years or older who were admitted to Sahlgrenska University Hospital, Gothenburg, Sweden, with COVID-19. All patients had CSF samples taken because of neurologic symptoms or within a study protocol. Healthy volunteer and prepandemic control groups were included. / Exposure: SARS-CoV-2 infection. / Main Outcomes and Measures: Outcomes included CSF SARS-CoV-2 nucleocapsid antigen (N-Ag) using an ultrasensitive antigen capture immunoassay platform and CSF biomarkers of immune activation (neopterin, β2-microglobulin, and cytokines) and neuronal injury (neurofilament light protein [NfL]). / Results: Forty-four patients (median [IQR] age, 57 [48-69] years; 30 [68%] male; 26 with moderate COVID-19 and 18 with severe COVID-19 based on the World Health Organization Clinical Progression Scale), 10 healthy controls (median [IQR] age, 58 [54-60] years; 5 [50%] male), and 41 patient controls (COVID negative without evidence of CNS infection) (median [IQR] age, 59 [49-70] years; 19 [46%] male) were included in the study. Twenty-one patients were neuroasymptomatic and 23 were neurosymptomatic (21 with encephalopathy). In 31 of 35 patients for whom data were available (89%), CSF N-Ag was detected; viral RNA test results were negative in all. Nucleocapsid antigen was significantly correlated with CSF neopterin (r = 0.38; P = .03) and interferon γ (r = 0.42; P = .01). No differences in CSF N-Ag concentrations were found between patient groups. Patients had markedly increased CSF neopterin, β2-microglobulin, interleukin (IL) 2, IL-6, IL-10, and tumor necrosis factor α compared with controls. Neurosymptomatic patients had significantly higher median (IQR) CSF interferon γ (86 [47-172] vs 21 [17-81] fg/mL; P = .03) and had a significantly higher inflammatory biomarker profile using principal component analysis compared with neuroasymptomatic patients (0.54; 95% CI, 0.03-1.05; P = .04). Age-adjusted median (IQR) CSF NfL concentrations were higher in patients compared with controls (960 [673-1307] vs 618 [489-786] ng/L; P = .002). No differences were seen in any CSF biomarkers in moderate compared with severe disease. / Conclusions and Relevance: In this study of Swedish adults with COVID-19 infection and neurologic symptoms, compared with control participants, viral antigen was detectable in CSF and correlated with CNS immune activation. Patients with COVID-19 had signs of neuroaxonal injury, and neurosymptomatic patients had a more marked inflammatory profile that could not be attributed to differences in COVID-19 severity. These results highlight the clinical relevance of neurologic symptoms and suggest that viral components can contribute to CNS immune responses without direct viral invasion

HIV Persistence and Viral Reservoirs

Although antiretroviral therapy (ART) can effectively inhibit replication of human immunodeficiency virus type 1 (HIV-1), the virus is able to persist in cellular and anatomical viral reservoirs. Latently infected resting memory CD4+ T-cells are an important cellular reservoir, and the central nervous system (CNS) an important anatomical reservoir for HIV-1 infection. The overall aim of this thesis was to gain greater understanding of HIV-1 persistence, in regards to latent infection as well as the central nervous system. The initial viral decay rate after initiation of ART has been proposed as a measure of relative regimen potency. We compared initial viral decay in subjects treated with three ART regimens, and found that efavirenz-based therapy gave a faster initial viral decay than protease inhibitor (PI) treated subjects. In turn, lopinavir/ritonavir-based therapy gave a faster initial viral decay than atazanavir/ritonavir-based therapy. This may reflect different inherent antiretroviral potency between the treatment regimens. Latently infected CD4+ T-cells constitute a major barrier for the eradication of HIV-1 infection. We investigated if a high dose of intravenous immunoglobulin (IVIG) given in addition to effective ART could reduce the size of the pool of latently infected resting cells, and found a reduction in the pool size in five of seven individuals where the latent reservoir was quantifiable. Our findings suggest that the reservoir became accessible through IVIG treatment, and indicate that novel modes of intervention can have an effect on the latent reservoir. Increased levels of intrathecal immune activation are often found in cerebrospinal fluid (CSF) of treated patients despite effective systemic suppression of HIV-1. We investigated intrathecal immune activation, measured as neopterin and IgG-index, in patients with several years of successful therapy, and found that although ART has a substantial effect on lowering viral replication and immune activation in the CSF, a majority of patients still have ongoing intrathecal immune activation despite effective suppression of the virus for extended periods of time. Occasional cases of CSF viral escape have been reported. We investigated the occurrence of CSF viral escape in neuroasymptomatic patients effectively treated with commonly used ART regimens. We found that 7 (10%) of 69 patients had evidence of CSF viral escape, which is more common than previously recognized and may have important implications for future treatment strategies and the use of new drug combinations

Longitudinal decline of plasma neurofilament light levels after antiretroviral initiation in people living with HIV

OBJECTIVES: This retrospective follow-up study aims to investigate the dynamic longitudinal change of plasma neurofilament light (NfL) levels after antiretroviral (ART) initiation in a cohort of people living with HIV (PWH). METHODS: We tested a convenience sample of 116 patients from the NORTHIV study. Plasma NfL levels-measured using Single molecule array (Simoa) technology-as well as other laboratory parameters, were collected at baseline, week 4, week 48, week 96, and week 144. Linear mixed-effects models were estimated to evaluate longitudinal change over time. Baseline CD4+ T-cell levels, CDC classification, and HIV RNA levels were considered. Models were adjusted by age, sex, treatment regimen, and baseline serum creatinine levels. RESULTS: Plasma NfL levels were higher at baseline, and also declined faster during the follow-up for participants with CD4+ count 100 cells/μl. No significant difference was found between the CD4+ strata 100-199/μl versus 200-499/μl. Participants with CDC classification stages B and C had higher levels of plasma NfL at baseline, as well as faster decline compared with participants with stage A. No significant main effects or change over time were found in baseline HIV RNA levels, treatment regimen, or sex. CONCLUSION: Plasma NfL is a sensitive biomarker to assess ongoing CNS injury in PWH. Plasma NfL concentrations decline relatively fast following ART initiation, and then stabilize after 48 weeks. Plasma NfL concentrations are associated with CD4+ count and stage of HIV disease. No correlations were seen with different ART regimens. This article is protected by copyright. All rights reserved

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