Phyloanatomic characterization of the distinct T cell and monocyte contributions to the peripheral blood HIV population within the host

Human immunodeficiency virus (HIV) is a rapidly evolving virus, allowing its genetic sequence to act as a fingerprint for epidemiological processes among, as well as within, individual infected hosts. Though primarily infecting the CD4+ T-cell population, HIV can also be found in monocytes, an immune cell population that differs in several aspects from the canonical T-cell viral target. Using single genome viral sequencing and statistical phylogenetic inference, we investigated the viral RNA diversity and relative contribution of each of these immune cell types to the viral population within the peripheral blood. Results provide evidence of an increased prevalence of circulating monocytes harboring virus in individuals with high viral load in the absence of suppressive antiretroviral therapy. Bayesian phyloanatomic analysis of three of these individuals demonstrated a measurable role for these cells, but not the circulating T-cell population, as a source of cell-free virus in the plasma, supporting the hypothesis that these cells can act as an additional conduit of virus spread.

Very Early Initiation of Antiretroviral Therapy During Acute HIV Infection Is Associated With Normalized Levels of Immune Activation Markers in Cerebrospinal Fluid but Not in Plasma

BACKGROUND

Chronic immune activation in the blood and central nervous system is a consequence of human immunodeficiency virus (HIV) infection that contributes to disease morbidity and can occur despite virally suppressive antiretroviral therapy (ART). The trajectory of HIV-related inflammation may vary with the timing of ART initiation. We examined immune activation markers in cerebrospinal fluid (CSF) and blood specimens collected over 96 weeks from participants who initiated ART during acute HIV infection (AHI).

METHODS

RV254/SEARCH010 study participants with AHI underwent CSF (n = 89) and plasma (n = 146) sampling before initiating ART and at weeks 24 and 96 of treatment. A majority participants (64.4%) received a standard ART regimen (hereafter, "standard ART"), with some (34.7%) also receiving maraviroc and raltegravir for the first 24 weeks (hereafter, "ART plus"). We compared neopterin, CXCL10, CCL2, and interleukin 6 (IL-6) levels in the AHI group to those in 18 healthy, uninfected controls.

RESULTS

Following 24 and 96 weeks of treatment, levels of all CSF markers normalized while levels of several plasma markers remained elevated in the AHI group (P < .001). Participants receiving the ART-plus regimen had lower median plasma CCL2 levels at week 24 and lower plasma neopterin levels at week 96.

CONCLUSIONS

ART initiation during AHI differentially impacts the brain compartment, with markers of inflammation returning to normal levels in the CSF, where they were sustained at week 96, but not in plasma.

Acute Retroviral Syndrome Is Associated With High Viral Burden, CD4 Depletion, and Immune Activation in Systemic and Tissue Compartments

Background

Many individuals with acute human immunodeficiency virus infection (AHI) experience acute retroviral syndrome (ARS), which is associated with adverse long-term clinical outcomes.

Methods

Participants presenting for voluntary human immunodeficiency virus (HIV) testing were enrolled during AHI in Bangkok, Thailand. ARS was defined by ≥3 qualifying signs/symptoms. HIV burden, immunophenotypes, and biomarkers were stratified by ARS diagnosis at enrollment and after up to 96 weeks of antiretroviral therapy (ART).

Results

From 212382 samples screened, 430 participants were enrolled during AHI, including 335 (78%) with ARS. Median age was 26 years and 416 (97%) were men. Sixty (14%) underwent sigmoid biopsy and 105 (24%) underwent lumbar puncture during AHI. Common symptoms included fever (93%), fatigue (79%), pharyngitis (67%), and headache (64%). Compared to those without ARS, participants with ARS were in later Fiebig stages with higher HIV RNA in blood, colon, and cerebrospinal fluid; higher total HIV DNA in blood; CD4 depletion in blood and colon; and elevated plasma tumor necrosis factor alpha (TNF-α), C-reactive protein, and D-dimer (all P < .05). Subgroup analyses of Fiebig I/II participants (95 with ARS, 69 without) demonstrated similar findings. After 96 weeks of ART, TNF-α and interleukin 6 were elevated in the ARS group (P < .05) but other biomarkers equilibrated.

Conclusions

ARS was associated with high viral burden, CD4 depletion, and immune activation across multiple body compartments during AHI and prior to ART. Persistent inflammation despite suppressive ART could contribute to increased morbidity in individuals who experience ARS.

Characterization of Cellular Immune Responses in Thai Individuals With and Without HIV-Associated Neurocognitive Disorders

HIV-associated neurocognitive disorder (HAND) remains a challenge despite antiretroviral therapy (ART), and has been linked to monocyte/macrophage (M/M) migration to the brain. Due to the potential impact of T cell effector mechanisms in eliminating activated/HIV-infected M/M, T cell activation may play a role in the development of HAND. We sought to investigate the relationship between cognition and both CD8⁺ T cell activation (HLA-DR⁺/CD38⁺) and HIV-specific CD8⁺ T cell responses at the time of HIV diagnosis and 12 months postinitiation of ART. CD8⁺ T cell activation was increased in HAND compared to cognitive normal (NL) individuals and correlated directly with plasma viral load and inversely with the cognitive status. In addition, Gag-specific cytolytic activity (CD107a/b⁺) was decreased in HAND compared with NL individuals and correlated with their neurological testing, suggesting a potential role of cytotoxic CD8⁺ T cells in the mechanism of HAND development.

Structural and functional brain imaging in acute HIV

Background

HIV RNA is identified in cerebrospinal fluid (CSF) within eight days of estimated viral exposure. Neurological findings and impaired neuropsychological testing performance are documented in a subset of individuals with acute HIV infection (AHI). The purpose of this study was to determine whether microstructural white matter and resting-state functional connectivity (rsFC) are disrupted in AHI.

Methods

We examined 49 AHI (100% male; mean age = 30 ± SD 9.9) and 23 HIV-uninfected Thai participants (78% male; age = 30 ± 5.5) with diffusion tensor imaging (DTI) and rsFC acquired at 3 Tesla, and four neuropsychological tests (summarized as NPZ-4). MRI for the AHI group was performed prior to combination antiretroviral treatment (ART) in 26 participants and on average two days (range:1–5) after ART in 23 participants. Fractional anisotropy (FA), mean (MD), axial (AD), and radial diffusivity (RD) were quantified for DTI. Seed-based voxelwise rsFC analyses were completed for the default mode (DMN), fronto-parietal, and salience and 6 subcortical networks. rsFC and DTI analyses were corrected for family-wise error, with voxelwise comparisons completed using t-tests. Group-specific voxelwise regressions were conducted to examine relationships between imaging indices, HIV disease variables, and treatment status.

Results

The AHI group had a mean (SD) CD4 count of 421(234) cells/mm³ plasma HIV RNA of 6.07(1.1) log₁₀ copies/mL and estimated duration of infection of 20(5.5) days. Differences between AHI and CO groups did not meet statistical significance for DTI metrics. Within the AHI group, voxelwise analyses revealed associations between brief exposure to ART and higher FA and lower RD and MD bilaterally in the corpus callosum, corona radiata, and superior longitudinal fasciculus (p < 0.05). Diffusion indices were unrelated to clinical variables or NPZ-4. The AHI group had reduced rsFC between left parahippocampal cortex (PHC) of the DMN and left middle frontal gyrus compared to CO (p < 0.002). Within AHI, ART status was unrelated to rsFC. However, higher CD4 cell count associated with increased rsFC for the right lateral parietal and PHC seeds in the DMN. Direct associations were noted between NPZ-4 correspond to higher rsFC of the bilateral caudate seed (p < 0.002).

Conclusions

Study findings reveal minimal disruption to structural and functional brain integrity in the earliest stages of HIV. Longitudinal studies are needed to determine if treatment with ART initiated in AHI is sufficient to prevent the evolution of brain dysfunction identified in chronically infected individuals.

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DTI indicates no significant differences between acute HIV and uninfected controls.

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rsfMRI reflects limited reduced rsFC in acute HIV compared to uninfected controls.

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Relatively preserved brain integrity identified in acute HIV vs uninfected controls.

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Cognitive testing and CD4 lymphocyte counts associate with rsFC activity in acute HIV.

Delayed differentiation of potent effector CD8+ T cells reducing viremia and reservoir seeding in acute HIV infection

CD8⁺ T cells play a critical role in controlling HIV viremia and could be important in reducing HIV-infected cells in approaches to eradicate HIV. The simian immunodeficiency virus model provided the proof of concept for a CD8⁺ T cell-mediated reservoir clearance but showed conflicting evidence on the role of these cells to eliminate HIV-infected cells. In humans, HIV-specific CD8⁺ T cell responses have not been associated with a reduction of the HIV-infected cell pool in vivo. We studied HIV-specific CD8⁺ T cells in the RV254 cohort of individuals initiating ART in the earliest stages of acute HIV infection (AHI). We showed that the HIV-specific CD8⁺ T cells generated as early as AHI stages 1 and 2 before peak viremia are delayed in expanding and acquiring effector functions but are endowed with higher memory potential. In contrast, the fully differentiated HIV-specific CD8⁺ T cells at peak viremia in AHI stage 3 were more prone to apoptosis but were associated with a steeper viral load decrease after ART initiation. Their capacity to persist in vivo after ART initiation correlated with a lower HIV DNA reservoir. These findings demonstrate that HIV-specific CD8⁺ T cell magnitude and differentiation are delayed in the earliest stages of infection. These results also demonstrate that potent HIV-specific CD8⁺ T cells contribute to the reduction of the pool of HIV-producing cells and the HIV reservoir seeding in vivo and provide the rationale to design interventions aiming at inducing these potent responses to cure HIV infection.

HIV DNA Set Point is Rapidly Established in Acute HIV Infection and Dramatically Reduced by Early ART

HIV DNA is a marker of HIV persistence that predicts HIV progression and remission, but its kinetics in early acute HIV infection (AHI) is poorly understood. We longitudinally measured the frequency of peripheral blood mononuclear cells harboring total and integrated HIV DNA in 19 untreated and 71 treated AHI participants, for whom 50 were in the earliest Fiebig I/II (HIV IgM −) stage, that is ≤ 2 weeks from infection. Without antiretroviral therapy (ART), HIV DNA peaked at 2 weeks after enrollment, reaching a set-point 2 weeks later with little change thereafter. There was a marked divergence of HIV DNA values between the untreated and treated groups that occurred within the first 2 weeks of ART and increased with time. ART reduced total HIV DNA levels by 20-fold after 2 weeks and 316-fold after 3 years. Therefore, very early ART offers the opportunity to significantly reduce the frequency of cells harboring HIV DNA.

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The HIV DNA set-point is established early in acute HIV infection.

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Over three years without antiretroviral therapy, persons with acute HIV infection have total HIV DNA in peripheral blood mononuclear cells that is 300-fold and integrated HIV DNA that is 100-fold higher than those on treatment.

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Early antiretroviral therapy provides an opportunity to markedly reduce proviral HIV DNA burden,

HIV is difficult to cure because it infects long-lived cells in the body, also called “reservoirs”. Having a small HIV reservoir size may benefit health. We show that HIV DNA in peripheral blood cells, a marker of the HIV reservoir size, establishes a set-point level during the first 6 weeks of infection and changes little over time without HIV medications. However, if HIV medications are started early, the reservoir size declines rapidly, and is 300-fold lower than that seen in untreated persons. Currently the most effective way to significantly lower the HIV reservoir size is with very early treatment.

Impact of early cART in the gut during acute HIV infection

Early after HIV infection there is substantial depletion of CD4⁺ T cells in the gastrointestinal (GI) tract lamina propria (LP), with associated epithelial barrier damage, leading to microbial translocation and systemic inflammation and immune activation. In this study, we analyzed these early events in the GI tract in a cohort of Thai acute HIV-infected patients and determined the effect of early combination antiretroviral treatment (cART). HIV-uninfected and chronically and acutely HIV-infected patients at different Fiebig stages (I-V) underwent colonic biopsies and then received cART. Immunohistochemistry and quantitative image analysis were performed on cross-sectional and longitudinal colon biopsy specimens (day 0 to week 96) to measure GI tract damage (infiltration of polymorphonuclear cells), inflammation (M×1, TNF-α), immune activation (Ki-67), and the CD4⁺ T cell population in the LP. The magnitude of GI tract damage, immune activation, and inflammation was significantly increased, with significantly depleted CD4⁺ T cells in the LP in all acutely infected groups prior to cART compared with HIV-uninfected control participants. While most patients treated during acute infection resolved GI tract inflammation and immune activation back to baseline levels after 24 weeks of cART, most acutely infected participants did not restore their CD4⁺ T cells after 96 weeks of cART.

Initiation of Antiretroviral Therapy During Acute HIV-1 Infection Leads to a High Rate of Nonreactive HIV Serology

BACKGROUND

Third- and fourth-generation immunoassays (IAs) are widely used in the diagnosis of human immunodeficiency virus (HIV) infection. Antiretroviral therapy (ART) during acute HIV infection (AHI) may impact HIV-specific antibodies, with failure to develop antibody or seroreversion. We report on the ability of diagnostic tests to detect HIV-specific antibodies in Thai participants initiating ART during AHI.

METHODS

Participants with detectable plasma HIV RNA but nonreactive HIV-specific immunoglobulin G, enrolled in an AHI study, were offered immediate initiation of ART. Participants were tested at initiation and at 12 and 24 weeks following treatment using standard second-, third-, and fourth-generation IAs and Western blot (WB).

RESULTS

Participants (N = 234) initiating ART at a median of 19 days (range, 1-62 days) from HIV exposure demonstrated different frequencies of reactivity prior to and following 24 weeks of ART depending on the IA. Third-generation IA nonreactivity prior to ART was 48%, which decreased to 4% following ART (P < .001). Fourth-generation IA nonreactivity was 18% prior to ART and 17% following ART (P = .720). Negative WB results were observed in 89% and 12% of participants prior to and following 24 weeks of ART, respectively (P < .001). Seroreversion to nonreactivity during ART was observed to at least one of the tests in 20% of participants, with fourth-generation IA demonstrating the highest frequency (11%) of seroreversion.

CONCLUSIONS

HIV-specific antibodies may fail to develop and, when detected, may decline when ART is initiated during AHI. Although fourth-generation IA was the most sensitive at detecting AHI prior to ART, third-generation IA was the most sensitive during treatment.

CLINICAL TRIALS REGISTRATION

NCT00796146 and NCT00796263.

Neurologic signs and symptoms frequently manifest in acute HIV infection

OBJECTIVE

To determine the incidence, timing, and severity of neurologic findings in acute HIV infection (pre-antibody seroconversion), as well as persistence with combination antiretroviral therapy (cART).

METHODS

Participants identified with acute HIV were enrolled, underwent structured neurologic evaluations, immediately initiated cART, and were followed with neurologic evaluations at 4 and 12 weeks. Concurrent brain MRIs and both viral and inflammatory markers in plasma and CSF were obtained.

RESULTS

Median estimated HIV infection duration was 19 days (range 3-56) at study entry for the 139 participants evaluated. Seventy-three participants (53%) experienced one or more neurologic findings in the 12 weeks after diagnosis, with one developing a fulminant neurologic manifestation (Guillain-Barré syndrome). A total of 245 neurologic findings were noted, reflecting cognitive symptoms (33%), motor findings (34%), and neuropathy (11%). Nearly half of the neurologic findings (n = 121, 49%) occurred at diagnosis, prior to cART initiation, and most of these (n = 110, 90%) remitted concurrent with 1 month on treatment. Only 9% of neurologic findings (n = 22) persisted at 24 weeks on cART. Nearly all neurologic findings (n = 236, 96%) were categorized as mild in severity. No structural neuroimaging abnormalities were observed. Participants with neurologic findings had a higher mean plasma log10 HIV RNA at diagnosis compared to those without neurologic findings (5.9 vs 5.4; p = 0.006).

CONCLUSIONS

Acute HIV infection is commonly associated with mild neurologic findings that largely remit while on treatment, and may be mediated by direct viral factors. Severe neurologic manifestations are infrequent in treated acute HIV.

Absence of Cerebrospinal Fluid Signs of Neuronal Injury Before and After Immediate Antiretroviral Therapy in Acute HIV Infection

BACKGROUND

It is unknown whether neuronal injury begins during acute human immunodeficiency virus (HIV) infection, and whether immediate initiation of combination antiretroviral therapy (cART) prevents neuronal injury.

METHODS

Cerebrospinal fluid (CSF) neurofilament light chain (NFL), a measure of axonal injury, was assessed before and after cART initiation in individuals starting treatment during acute or chronic HIV infection. Nonparametric statistics examined relationships between NFL and disease progression, neuroinflammation, and cognitive performance.

RESULTS

Before treatment, subjects with acute infection had lower CSF NFL levels, with elevations for their age in 1 of 32 subjects with acute infection (3.1%) and 10 of 32 with chronic infection (31%) (P = .006). This persisted after cART initiation, with 1 of 25 acute (4%) and 4 of 9 chronic subjects (44%) showing elevated NFL levels (P = .01). In acute infection, pre-cART NFL levels were inversely correlated with proton magnetic resonance spectroscopic findings of N-acetylaspartate/creatine in frontal gray matter (r = -0.40; P = .03), frontal white matter (r = -0.46; P = .01), and parietal gray matter (r = -0.47; P = .01); correlations persisted after treatment in the frontal white matter (r = -0.51; P = .02) and parietal gray matter (r = -0.46; P = .04).

CONCLUSIONS

CSF NFL levels are not elevated in untreated acute HIV infection or after 6 months of immediately initiated cART but are abnormal in chronic HIV infection before and after treatment. In acute HIV infection, CSF NFL levels are inversely associated with neuroimaging markers of neuronal health.

Practice effect and normative data of an HIV-specific neuropsychological testing battery among healthy Thais

OBJECTIVE

A longitudinal cohort study was conducted in Bangkok, Thailand between 2008 and 2013 in order to determine the practice effect of serial neuropsychological testing and establish normative data among normal (HIV-uninfected) Thai volunteers.

MATERIAL AND METHOD

The authors enrolled 511 cognitively healthy individuals (HIV-uninfected, no drug abuse or other previous/current neurological or psychological conditions) to assess baseline performance on a HIV-specific neuropsychological testing battery. Ninety-nine subjects were re-assessed at 6 and 12 months to evaluate practice effects.

RESULTS

The mean age of the 99 subjects completing longitudinal visits was 49.2 years and 53 were male. The authors identified improved mean raw scores on most neuropsychological tests with repeated measurements; however only change in WHO Auditory Verbal Learning Test (AVLT) scores (learning, attention, immediate and delayed recall tasks) met statistical significance, with larger differences seen between baseline and 6-month compared to 6 and 12 months follow-up. Older age correlated with poorer baseline raw score, and was a predictor of worse performance at 6 months and 12 months on several tasks. Level of education was associated with practice effects on several tests. No similar effects were observed with gender.

CONCLUSION

The authors identified improved performance after repeated measurements revealing a significant practice effect on an HIV-specific neuropsychological testing battery employed in Bangkok, Thailand. Main predictors were age and educational attainment.

HIV DNA reservoir increases risk for cognitive disorders in cART-naïve patients

Objectives

Cognitive impairment remains frequent in HIV, despite combination antiretroviral therapy (cART). Leading theories implicate peripheral monocyte HIV DNA reservoirs as a mechanism for spread of the virus to the brain. These reservoirs remain present despite cART. The objective of this study was to determine if the level of HIV DNA in CD14⁺ enriched monocytes predicted cognitive impairment and brain injury.

Methods

We enrolled 61 cART-naïve HIV-infected Thais in a prospective study and measured HIV DNA in CD14⁺ enriched monocyte samples in a blinded fashion. We determined HAND diagnoses by consensus panel and all participants underwent magnetic resonance spectroscopy (MRS) to measure markers of brain injury. Immune activation was measured via cytokines in cerebrospinal fluid (CSF).

Results

The mean (SD) age was 35 (6.9) years, CD4 T-lymphocyte count was 236 (139) and log₁₀ plasma HIV RNA was 4.8 (0.73). Twenty-eight of 61 met HAND criteria. The log₁₀ CD14⁺ HIV DNA was associated with HAND in unadjusted and adjusted models (p = 0.001). There was a 14.5 increased odds ratio for HAND per 1 log-value of HIV DNA (10-fold increase in copy number). Plasma CD14⁺ HIV DNA was associated with plasma and CSF neopterin (p = 0.023) and with MRS markers of neuronal injury (lower N-acetyl aspartate) and glial dysfunction (higher myoinositol) in multiple brain regions.

Interpretation

Reservoir burden of HIV DNA in monocyte-enriched (CD14⁺) peripheral blood cells increases risk for HAND in treatment-naïve HIV+ subjects and is directly associated with CSF immune activation and both brain injury and glial dysfunction by MRS.

A novel acute HIV infection staging system based on 4th generation immunoassay

BACKGROUND

Fourth generation (4thG) immunoassay (IA) is becoming the standard HIV screening method but was not available when the Fiebig acute HIV infection (AHI) staging system was proposed. Here we evaluated AHI staging based on a 4thG IA (4thG staging).

FINDINGS

Screening for AHI was performed in real-time by pooled nucleic acid testing (NAT, n=48,828 samples) and sequential enzyme immunoassay (EIA, n=3,939 samples) identifying 63 subjects with non-reactive 2nd generation EIA (Fiebig stages I (n=25), II (n=7), III (n=29), IV (n=2)). The majority of samples tested (n=53) were subtype CRF_01AE (77%). NAT+ subjects were re-staged into three 4thG stages: stage 1 (n=20; 4th gen EIA-, 3rd gen EIA-), stage 2 (n=12; 4th gen EIA+, 3rd gen EIA-), stage 3 (n=31; 4th gen EIA+, 3rd gen EIA+, Western blot-/indeterminate). 4thG staging distinguishes groups of AHI subjects by time since presumed HIV exposure, pattern of CD8+ T, B and natural killer cell absolute numbers, and HIV RNA and DNA levels. This staging system further stratified Fiebig I subjects: 18 subjects in 4thG stage 1 had lower HIV RNA and DNA levels than 7 subjects in 4thG stage 2.

CONCLUSIONS

Using 4th generation IA as part of AHI staging distinguishes groups of patients by time since exposure to HIV, lymphocyte numbers and HIV viral burden. It identifies two groups of Fiebig stage I subjects who display different levels of HIV RNA and DNA, which may have implication for HIV cure. 4th generation IA should be incorporated into AHI staging systems.

Trail Making Test A improves performance characteristics of the International HIV Dementia Scale to identify symptomatic HAND

Although HIV-associated dementia (HAD) occurs in less than 5 % of individuals with access to combination antiretroviral therapy, rates of milder forms of HIV-associated neurocognitive disorder (HAND) are much higher. We sought to define an optimal cut point for the International HIV Dementia Scale (IHDS) in Thailand for the identification of symptomatic HAND, defined as both HAD and mild neurocognitive disorder. We then sought to determine if adding a simple test from a larger neuropsychological battery could improve the performance characteristics for identifying symptomatic HAND. In this study, subjects comprising 75 seropositive adults in Bangkok, Thailand, completed neuropsychological tests and underwent a full neurological assessment. HAND diagnoses were determined by consensus conference using the 2007 Frascati criteria, blinded to the IHDS results. The optimal IHDS cut point was determined by receiver operating characteristic analysis with cross-validation. Individual neuropsychological tests were then evaluated and combined with the IHDS to test performance characteristics. The IHDS was poor at detecting symptomatic HAND at the optimized cut point of ≤ 10 (sensitivity, 53.3 %; specificity, 89.8 %). Trail Making Test A was most effective in improving performance characteristics when combined with the IHDS, with net sensitivity of 86 % and specificity of 79 %. In this setting, the IHDS performed poorly in identifying symptomatic HAND, but was substantially improved by the addition of Trail Making Test A, which typically requires less than 2 min to complete. This combination should be validated in a larger setting since it may address the critical need for HAND screening instruments in international settings.