HIV-1 viral escape in cerebrospinal fluid of subjects on suppressive antiretroviral treatment

Neurosymptomatic HIV-1 CSF escape is associated with replication in CNS T cells and inflammation

During antiretroviral therapy (ART), most people living with HIV-1 have undetectable HIV-1 RNA in their plasma. However, they occasionally present with new or progressive neurologic deficits and detectable HIV-1 RNA in the cerebrospinal fluid (CSF), a condition defined as neurosymptomatic HIV-1 CSF escape (NSE). We explored the source of neuropathogenesis and HIV-1 RNA in the CSF during NSE by characterizing HIV-1 populations and inflammatory biomarkers in CSF from 25 individuals with NSE. HIV-1 populations in the CSF were uniformly drug resistant and adapted to replication in CD4+ T cells, but differed greatly in genetic diversity, with some having low levels of diversity similar to those observed during untreated primary infection and others having high levels like those during untreated chronic infection. Higher diversity in the CSF during NSE was associated with greater CNS inflammation. Finally, optimization of ART regimen was associated with viral suppression and improvement of neurologic symptoms. These results are consistent with CNS inflammation and neurologic injury during NSE being driven by replication of partially drug-resistant virus in CNS CD4+ T cells. This is unlike nonsuppressible viremia in the plasma during ART, which typically lacks clinical consequences and is generated by virus expression without replication.

CSF1R inhibition depletes brain macrophages and reduces brain virus burden in SIV-infected macaques

Perivascular macrophages (PVMs) and, to a lesser degree, microglia are targets and reservoirs of HIV and simian immunodeficiency virus (SIV) in the brain. Previously, we demonstrated that colony-stimulating factor 1 receptor (CSF1R) in PVMs was upregulated and activated in chronically SIV-infected rhesus macaques with encephalitis, correlating with SIV infection of PVMs. Herein, we investigated the role of CSF1R in the brain during acute SIV infection using BLZ945, a brain-penetrant CSF1R kinase inhibitor. Apart from three uninfected historic controls, nine Indian rhesus macaques were infected acutely with SIVmac251 and divided into three groups (n = 3 each): an untreated control and two groups treated for 20-30 days with low- (10 mg/kg/day) or high- (30 mg/kg/day) dose BLZ945. With the high-dose BLZ945 treatment, there was a significant reduction in cells expressing CD163 and CD206 across all four brain areas examined, compared with the low-dose treatment and control groups. In 9 of 11 tested regions, tissue viral DNA (vDNA) loads were reduced by 95%-99% following at least one of the two doses, and even to undetectable levels in some instances. Decreased numbers of CD163+ and CD206+ cells correlated significantly with lower levels of vDNA in all four corresponding brain areas. In contrast, BLZ945 treatment did not significantly affect the number of microglia. Our results indicate that doses as low as 10 mg/kg/day of BLZ945 are sufficient to reduce the tissue vDNA loads in the brain with no apparent adverse effect. This study provides evidence that infected PVMs are highly sensitive to CSF1R inhibition, opening new possibilities to achieve viral clearance.

"Evaluation of ELITE InGenius® integrative system for detection, quantification and monitoring of HIV-1 RNA in Cerebrospinal Fluid."

INTRODUCTION

Human Immunodeficiency virus (HIV) is effectively suppressed in the blood by the Antiretroviral Therapy in people living with HIV, but in rare cases can be present in some tissues and body fluids. In recent years, integrated systems were validated for detecting HIV-1 in plasma or serum. but not in cerebrospinal fluid (CSF). We evaluated the performance of ELITE InGenius® in comparison with the cobas® in this area.

METHODS

To test the diagnostic accuracy of the HIV-1 ELITe MGB® kit on CSF samples, we tested CSF samples previously characterised with the cobras® HIV1 test. Archived CSF samples were also spiked with serial dilutions of the 4th WHO International Standard for HIV-1 NAT and assays and tested to assess the repeatability and reproducibility of the ELITechGroup assay.

RESULTS

The HIV-1 ELITe MGB® Kit confirmed all the HIV-1 negative CSF samples from patients HIV positive in plasma and from non-HIV1 patients. All the CSF samples that were HIV-1 positive by the cobas®, were confirmed positive by the ELITe InGenius®. Concordance across the methods was also observed when processing the CSF dilutions spiked at medium-low titre, mimicking HIV-1 low-load infections.

CONCLUSIONS

The two systems were equivalent in the detection and quantification of HIV-1 RNA in CSF samples.

Changes in cerebrospinal fluid proteins across the spectrum of untreated and treated chronic HIV-1 infection

Using the Olink Explore 1536 platform, we measured 1,463 unique proteins in 303 cerebrospinal fluid (CSF) specimens from four clinical centers contributed by uninfected controls and 12 groups of people living with HIV-1 infection representing the spectrum of progressive untreated and treated chronic infection. We present three initial analyses of these measurements: an overview of the CSF protein features of the sample; correlations of the CSF proteins with CSF HIV-1 RNA and neurofilament light chain protein (NfL) concentrations; and comparison of CSF proteins in HIV-associated dementia (HAD) and neurosymptomatic CSF escape (NSE). These reveal a complex but coherent picture of CSF protein changes with highest concentrations of many proteins during CNS injury in the HAD and NSE groups and variable protein changes across the course of systemic HIV-1 progression that included two common patterns, designated as lymphoid and myeloid patterns, related to principal involvement of their underlying inflammatory cell lineages. Antiretroviral therapy reduced CSF protein perturbations, though not always to control levels. The dataset of these CSF protein measurements, along with background clinical information, is posted online. Extended studies of this unique dataset will supplement this report to provide more detailed characterization of the dynamic impact of HIV-1 infection on the CSF proteome across the spectrum of HIV-1 infection, advancing the mechanistic understanding of HIV-1-related CNS pathobiology.

Prevalence of detectable HIV-DNA and HIV-RNA in cerebrospinal fluid of youth with perinatal HIV and impaired cognition on antiretroviral therapy

OBJECTIVE

Central nervous system (CNS) HIV infection can impact cognition and may be an obstacle to cure in adolescents and young adults with perinatal HIV (AYAPHIV). IMPAACT2015 enrolled AYAPHIV on suppressive antiretroviral therapy (ART) with cognitive impairment to detect and quantify HIV in blood and cerebrospinal fluid (CSF).

DESIGN

IMPAACT2015 was a U.S.-based multi-site, exploratory, observational study.

METHODS

Cognitive impairment was defined as NIH Toolbox Fluid Cognition Composite score (FCCS) more than 1 standard deviation below age-adjusted normative group mean. Cell-free HIV-RNA and cell-associated HIV pol/gag -DNA and 10 biomarkers of inflammation/neuronal injury were measured in paired CSF and blood. ART exposure concentrations were quantified in hair.

RESULTS

Among 24 participants, 20 had successful CSF collection and 18 also met viral suppression criteria. Nine of 18 (50%) were female sex-at-birth, and 14 of 18 (78%) were black. Median (range) age was 20 years (13-27), time on ART was 18.3 years (8.0-25.5), and FCCS was 68 (53-80). HIV-DNA was detected in PBMCs from all participants. In CSF, two of 18 (11%, 95% CI: 1.4-34.7%) participants had detectable cell-free HIV-RNA, while HIV gag or pol -DNA was detectable in 13 of 18 (72%, 95% confidence interval: 47-90). Detectable HIV-DNA in CSF was associated with male sex-at-birth ( P  = 0.051), lower CD4 + cell count at enrollment ( P  = 0.016), and higher PBMC HIV pol -DNA copies ( P  = 0.058). Hair antiretroviral concentrations and biomarkers were not associated with CSF HIV-DNA detection.

CONCLUSION

We found that a high proportion of AYAPHIV with neurocognitive impairment had CSF cells harboring HIV-DNA during long-term virologic suppression. This evidence of persistent HIV-DNA in CSF suggests that the CNS should be considered in treatment and cure studies.

HIV-Associated Neurocognitive Disorder and CNS Viral Escape: A Case Report

HIV-associated neurocognitive disorder (HAND) encompasses a spectrum of cognitive impairments prevalent in individuals infected with HIV, despite effective combination antiretroviral therapy. This case report discusses a 42-year-old male with a history of HIV infection since 2014 who is currently on antiretroviral therapy (ART). The patient presented with cognitive impairment and generalized weakness, with subsequent investigations revealing HAND and CNS viral escape. The patient's management involved a switch to a different ART regimen, resulting in significant clinical improvement. This case highlights the importance of considering CNS-specific HIV replication in patients with neurocognitive symptoms and underscores the need for tailored ART regimens. The exclusion of progressive multifocal leukoencephalopathy through negative JC virus PCR was crucial in directing appropriate management. Comprehensive diagnostic evaluations, including CSF analysis and brain imaging, are essential for the accurate diagnosis and effective treatment of HAND, particularly in cases of CNS viral escape.

In situ analysis of neuronal injury and neuroinflammation during HIV-1 infection

BACKGROUND

Since the introduction of combination antiretroviral therapy (cART) the brain has become an important human immunodeficiency virus (HIV) reservoir due to the relatively low penetration of many drugs utilized in cART into the central nervous system (CNS). Given the inherent limitations of directly assessing acute HIV infection in the brains of people living with HIV (PLWH), animal models, such as humanized mouse models, offer the most effective means of studying the effects of different viral strains and their impact on HIV infection in the CNS. To evaluate CNS pathology during HIV-1 infection in the humanized bone marrow/liver/thymus (BLT) mouse model, a histological analysis was conducted on five CNS regions, including the frontal cortex, hippocampus, striatum, cerebellum, and spinal cord, to delineate the neuronal (MAP2ab, NeuN) and neuroinflammatory (GFAP, Iba-1) changes induced by two viral strains after 2 weeks and 8 weeks post-infection.

RESULTS

Findings reveal HIV-infected human cells in the brain of HIV-infected BLT mice, demonstrating HIV neuroinvasion. Further, both viral strains, HIV-1JR-CSF and HIV-1CH040, induced neuronal injury and astrogliosis across all CNS regions following HIV infection at both time points, as demonstrated by decreases in MAP2ab and increases in GFAP fluorescence signal, respectively. Importantly, infection with HIV-1JR-CSF had more prominent effects on neuronal health in specific CNS regions compared to HIV-1CH040 infection, with decreasing number of NeuN+ neurons, specifically in the frontal cortex. On the other hand, infection with HIV-1CH040 demonstrated more prominent effects on neuroinflammation, assessed by an increase in GFAP signal and/or an increase in number of Iba-1+ microglia, across CNS regions.

CONCLUSION

These findings demonstrate that CNS pathology is widespread during acute HIV infection. However, neuronal loss and the magnitude of neuroinflammation in the CNS is strain dependent indicating that strains of HIV cause differential CNS pathologies.

Changes in Cerebrospinal Fluid Proteins across the Spectrum of Untreated and Treated Chronic HIV-1 Infection

Using the Olink Explore 1536 platform, we measured 1,463 unique proteins in 303 cerebrospinal fluid (CSF) specimens from four clinical centers that included uninfected controls and 12 groups of people living with HIV-1 infection representing the spectrum of progressive untreated and treated chronic infection. We present three initial analyses of these measurements: an overview of the CSF protein features of the sample; correlations of the CSF proteins with CSF HIV-1 RNA and neurofilament light chain protein (NfL) concentrations; and comparison of the CSF proteins in HIV-associated dementia ( HAD ) and neurosymptomatic CSF escape ( NSE ). These reveal a complex but coherent picture of CSF protein changes that includes highest concentrations of many proteins during CNS injury in the HAD and NSE groups and variable protein changes across the course of neuroasymptomatic systemic HIV-1 progression, including two common patterns, designated as lymphoid and myeloid patterns, related to the principal involvement of their underlying inflammatory cell lineages. Antiretroviral therapy reduced CSF protein perturbations, though not always to control levels. The dataset of these CSF protein measurements, along with background clinical information, is posted online. Extended studies of this unique dataset will provide more detailed characterization of the dynamic impact of HIV-1 infection on the CSF proteome across the spectrum of HIV-1 infection, and further the mechanistic understanding of HIV-1-related CNS pathobiology.

gp120-derived amyloidogenic peptides form amyloid fibrils that increase HIV-1 infectivity

Apart from mediating viral entry, the function of the free HIV-1 envelope protein (gp120) has yet to be elucidated. Our group previously showed that EP2 derived from one β-strand in gp120 can form amyloid fibrils that increase HIV-1 infectivity. Importantly, gp120 contains ~30 β-strands. We examined whether gp120 might serve as a precursor protein for the proteolytic release of amyloidogenic fragments that form amyloid fibrils, thereby promoting viral infection. Peptide array scanning, enzyme degradation assays, and viral infection experiments in vitro confirmed that many β-stranded peptides derived from gp120 can indeed form amyloid fibrils that increase HIV-1 infectivity. These gp120-derived amyloidogenic peptides, or GAPs, which were confirmed to form amyloid fibrils, were termed gp120-derived enhancers of viral infection (GEVIs). GEVIs specifically capture HIV-1 virions and promote their attachment to target cells, thereby increasing HIV-1 infectivity. Different GAPs can cross-interact to form heterogeneous fibrils that retain the ability to increase HIV-1 infectivity. GEVIs even suppressed the antiviral activity of a panel of antiretroviral agents. Notably, endogenous GAPs and GEVIs were found in the lymphatic fluid, lymph nodes, and cerebrospinal fluid (CSF) of AIDS patients in vivo. Overall, gp120-derived amyloid fibrils might play a crucial role in the process of HIV-1 infectivity and thus represent novel targets for anti-HIV therapeutics.

Cerebrospinal Fluid Viral Escape on Highly Active Antiretroviral Therapy: Analysis from Single Tertiary Care Centre

HIV-infected individuals receiving regular antiretroviral therapy (ART) can present with a high viral load in cerebrospinal fluid (CSF) at times when it is suppressed in blood. This study presents data of HIV-infected patients who had undetectable or low plasma viral load in blood but presented with neurological signs and symptoms and were diagnosed to have CSF HIV viral escape. Records were reviewed for clinical manifestations, details of opportunistic or coinfection, and HIV viral copies in plasma and CSF at time of diagnosis of CSF escape. A total of 10,200 HIV-infected individuals were registered in HIV care till December 31, 2021. Nineteen individuals (14 virologically confirmed and 5 clinically) were diagnosed with high viral copies in CSF from June 2014 to December 2021. Mean age was 41.5 ± 9.2 (median, 39.5; range, 30-62) years. Average duration of antiretroviral treatment received at the time of diagnosis of CSF escape was 10.1 years. Median plasma HIV-viral copies were 2,469.8 (undetectable to 29,418) and in CSF were 12,773.7 (n = 14, range, 1,340-48,530) copies/mL. HIV viral copies in CSF were significantly higher than in plasma at the time of presentation (p = .003). ART regimen switch was done after identification of HIV CSF escape. Seventeen patients were alive with a regular follow-up of average 35 (range 7-66) months. All had documented clinical improvement with reversal of neurological impairment after ART switch. There was one death and one lost to follow-up. Early identification and timely intervention in CSF viral escape could revert severe neurological impairment and improves treatment outcome.

Is the Central Nervous System Reservoir a Hurdle for an HIV Cure?

There is currently no cure for HIV infection although adherence to effective antiretroviral therapy (ART) suppresses replication of the virus in blood, increases CD4+ T-cell counts, reverses immunodeficiency, and increases life expectancy. Despite these substantial advances, ART is a lifelong treatment for people with HIV (PWH) and upon cessation or interruption, the virus quickly rebounds in plasma and anatomic sites, including the central nervous system (CNS), resulting in disease progression. With recent advances in quantifying viral burden, detection of genetically intact viral genomes, and isolation of replication-competent virus from brain tissues of PWH receiving ART, it has become apparent that the CNS viral reservoir (largely comprised of macrophage type cells) poses a substantial challenge for HIV cure strategies. Other obstacles impacting the curing of HIV include ageing populations, substance use, comorbidities, limited antiretroviral drug efficacy in CNS cells, and ART-associated neurotoxicity. Herein, we review recent findings, including studies of the proviral integration sites, reservoir decay rates, and new treatment/prevention strategies in the context of the CNS, together with highlighting the next steps for investigations of the CNS as a viral reservoir.

CSF Inflammation Markers Associated with Asymptomatic Viral Escape in Cerebrospinal Fluid of HIV-Positive Individuals on Antiretroviral Therapy

HIV establishes a viral reservoir in the CNS despite viral suppression in the blood on antiretroviral therapy (ART). In a minority of people with HIV (PWH), HIV RNA is detectable in CSF when HIV RNA in plasma is undetectable or HIV RNA levels are higher in CSF compared with plasma, an event termed CSF viral escape that can occur with or without neurological symptoms. Asymptomatic CSF viral escape occurs in 3-20% of PWH on ART, yet associated biomarkers are unclear. To identify biomarkers associated with asymptomatic CSF viral escape, we performed a matched group study of PWH on ART with vs. without CSF viral escape (n = 10 and n = 60, respectively, matched for age, duration of HIV infection, nadir CD4 count, and ART regimen) and 50 HIV-negative controls. PWH were on 3 or more ART drugs for >1 year, and the group with no CSF viral escape was suppressed below 50 copies/mL in plasma and CSF. Biomarkers of inflammation (IFN-γ, IL-1β, IL-6, IL-8, IL-15, IP-10, MCP-1, VEGF), cell adhesion (ICAM-1, VCAM-1), CNS injury (NFL), and glial activation (GFAP, YKL-40) were measured in paired plasma and CSF using the Meso Scale Discovery platform. PWH with vs. without CSF viral escape had more individuals (40%) with a plasma viral load (VL) > 50 copies/mL, higher CSF VL (median 156 vs. 40 copies/mL; p < 0.0001), lower CD4 count (318 vs. 512; p = 0.045), and higher CSF WBC (median [IQR] 4 [0-22] vs. 2 [0-4] cells/µL; p = 0.15) but similar proportions with HIV-associated neurocognitive disorders (HAND) (50% vs. 47%). CSF viral escape was associated with increased IL-1β, IFN-γ, IP-10, ICAM-1, and VCAM-1 in CSF but not plasma; IP-10 had the strongest association (p = 0.0008). CSF VL and WBC correlated with IFN-γ, IP-10, ICAM-1, and VCAM-1 (p < 0.05). Although markers of CNS injury showed no significant association with asymptomatic CSF viral escape, CSF YKL-40 correlated positively with CSF IL-1β (p = 0.003), IFN-γ (p = 0.0008), IP-10 (p < 0.0001), and NFL (p = 0.06) and negatively with neurocognitive T scores (p = 0.02). These findings identify CSF inflammation and glial activation markers that may serve as surrogate measures of HIV persistence in the CNS for future studies on therapeutics targeting the CNS reservoir.

Viral co-infection, autoimmunity, and CSF HIV antibody profiles in HIV central nervous system escape

Antiretroviral therapy (ART) suppresses plasma and cerebrospinal fluid (CSF) HIV replication. Neurosymptomatic (NS) CSF escape is a rare exception in which CNS HIV replication occurs in the setting of neurologic impairment. The origins of NS escape are not fully understood. We performed a case-control study of asymptomatic (AS) escape and NS escape subjects with HIV-negative subjects as controls in which we investigated differential immunoreactivity to self-antigens in the CSF of NS escape by employing neuroanatomic CSF immunostaining and massively multiplexed self-antigen serology (PhIP-Seq). Additionally, we utilized pan-viral serology (VirScan) to deeply profile the CSF anti-viral antibody response and metagenomic next-generation sequencing (mNGS) for pathogen detection. We detected Epstein-Barr virus (EBV) DNA more frequently in the CSF of NS escape subjects than in AS escape subjects. Based on immunostaining and PhIP-Seq, there was evidence for increased immunoreactivity against self-antigens in NS escape CSF. Finally, VirScan revealed several immunodominant epitopes that map to the HIV envelope and gag proteins in the CSF of AS and NS escape subjects. Whether these additional inflammatory markers are byproducts of an HIV-driven process or whether they independently contribute to the neuropathogenesis of NS escape will require further study.

HIV-1 Tat Upregulates TREM1 Expression in Human Microglia

Because microglia are a reservoir for HIV and are resistant to the cytopathic effects of HIV infection, they are a roadblock for any HIV cure strategy. We have previously identified that triggering receptor expressed on myeloid cells 1 (TREM1) plays a key role in human macrophage resistance to HIV-mediated cytopathogenesis. In this article, we show that HIV-infected human microglia express increased levels of TREM1 and are resistant to HIV-induced apoptosis. Moreover, upon genetic inhibition of TREM1, HIV-infected microglia undergo cell death in the absence of increased viral or proinflammatory cytokine expression or the targeting of uninfected cells. We also show that the expression of TREM1 is mediated by HIV Tat through a TLR4, TICAM1, PG-endoperoxide synthase 2, PGE synthase, and PGE2-dependent manner. These findings highlight the potential of TREM1 as a therapeutic target to eradicate HIV-infected microglia without inducing a proinflammatory response.

Cerebrospinal fluid virology in people with HIV

OBJECTIVE

Our objectives were to investigate the recent frequency of cerebrospinal fluid (CSF) HIV RNA escape and other CSF viral nucleic acid detection in people with HIV with neurological symptoms and to assess associated clinical factors.

METHOD

This was a retrospective cohort analysis of people with HIV who underwent CSF examination for clinical indications between 2017 and 2022. Individuals were identified from pathology records, and clinical data were recorded. CSF HIV RNA escape was defined as CSF HIV RNA concentrations greater than in plasma. CSF viral screen included herpes simplex virus types 1 (HSV-1) and 2 (HSV-2), varicella zoster virus (VZV), Epstein Barr virus (EBV), cytomegalovirus (CMV), human herpesvirus 6 (HHV-6) and JC virus. When cases were detected in five or more people with HIV, associated clinical factors were assessed using linear regression modelling.

RESULTS

CSF HIV RNA escape was observed in 19 of 114 individuals (17%) and was associated with the presence of HIV drug resistance mutations and non-integrase strand transfer inhibitor-based antiretroviral therapy (p < 0.05 for all) when compared to people with HIV without escape. Positive viral nucleic acid testing included EBV (n = 10), VZV (3), CMV (2), HHV-6 (2) and JC virus (4). Detectable CSF EBV was not considered related to neurological symptoms and was associated with concomitant CSF infections in eight of ten individuals and with CSF pleocytosis, previous AIDS, lower nadir and current CD4 T-cell count (p < 0.05 for all).

CONCLUSION

In people with HIV with neurological symptoms, the frequency of CSF HIV RNA escape remains similar to that in historical reports. Detectable EBV viral nucleic acid in the CSF was observed frequently and, in the absence of clinical manifestations, may be a consequence of CSF pleocytosis.

Cohort profile: a longitudinal study of HIV infection in the central nervous system with focus on cerebrospinal fluid - the Gothenburg HIV CSF Study Cohort

PURPOSE

In order to enable long-term follow-up of the natural course of HIV infection in the central nervous system, a longitudinal cohort study with repeated cerebrospinal fluid (CSF) analyses at intervals over time was initiated in 1985. When antiretrovirals against HIV were introduced in the late 1980s, short-term and long-term effects of various antiretroviral treatment (ART) regimens were added to the study.

PARTICIPANTS

All adult people living with HIV (PLWH) who were diagnosed at or referred to the Department of Infectious Diseases, Sahlgrenska University Hospital, Gothenburg, Sweden were asked to participate in the Gothenburg HIV CSF Study Cohort. PLWH with neurological symptoms or other clinical symptoms of HIV, as well as those with no symptoms of HIV infection, were included. Most participants were asymptomatic, which distinguishes this cohort from most other international HIV CSF studies. In addition, HIV-negative controls were recruited. These included people on HIV pre-exposure prophylaxis who served as lifestyle-matched controls to HIV-infected men who have sex with men. Since lumbar puncture (LP) is an invasive procedure, some PLHW only consented to participate in one examination. Furthermore, at the beginning of the study, several participants were lost to follow-up having died from AIDS. Of 662 PLWH where an initial LP was done, 415 agreed to continue with follow-up. Among the 415, 56 only gave permission to be followed with LP for less than 1 year, mainly to analyse the short-term effect of ART. The remaining 359 PLWH were followed up with repeated LP for periods ranging from >1 to 30 years. This group was defined as the 'longitudinal cohort'. So far, on 7 April 2022, 2650 LP and samplings of paired CSF/blood had been performed, providing a unique biobank.

FINDINGS TO DATE

A general finding during the 37-year study period was that HIV infection in the central nervous system, as mirrored by CSF findings, appears early in the infectious course of the disease and progresses slowly in the vast majority of untreated PLWH. Combination ART has been highly effective in reducing CSF viral counts, inflammation and markers of neural damage. Minor CSF signs of long-term sequels or residual inflammatory activity and CSF escape (viral CSF blips) have been observed during follow-up. The future course of these changes and their clinical impact require further studies.

FUTURE PLANS

PLWH today have a life expectancy close to that of non-infected people. Therefore, our cohort provides a unique opportunity to study the long-term effects of HIV infection in the central nervous system and the impact of ART and is an ongoing study.

The comorbidity of depression and neurocognitive disorder in persons with HIV infection: call for investigation and treatment

Depression and neurocognitive disorder continue to be the major neuropsychiatric disorders affecting persons with HIV (PWH). The prevalence of major depressive disorder is two to fourfold higher among PWH than the general population (∼6.7%). Prevalence estimates of neurocognitive disorder among PWH range from 25 to over 47% - depending upon the definition used (which is currently evolving), the size of the test battery employed, and the demographic and HIV disease characteristics of the participants included, such as age range and sex distribution. Both major depressive disorder and neurocognitive disorder also result in substantial morbidity and premature mortality. However, though anticipated to be relatively common, the comorbidity of these two disorders in PWH has not been formally studied. This is partly due to the clinical overlap of the neurocognitive symptoms of these two disorders. Both also share neurobehavioral aspects - particularly apathy - as well as an increased risk for non-adherence to antiretroviral therapy. Shared pathophysiological mechanisms potentially explain these intersecting phenotypes, including neuroinflammatory, vascular, and microbiomic, as well as neuroendocrine/neurotransmitter dynamic mechanisms. Treatment of either disorder affects the other with respect to symptom reduction as well as medication toxicity. We present a unified model for the comorbidity based upon deficits in dopaminergic transmission that occur in both major depressive disorder and HIV-associated neurocognitive disorder. Specific treatments for the comorbidity that decrease neuroinflammation and/or restore associated deficits in dopaminergic transmission may be indicated and merit study.

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

BACKGROUND

This retrospective follow-up study aims to investigate the dynamic longitudinal change of plasma neurofilament light (NfL) levels after antiretroviral therapy (ART) initiation in a cohort of people living with human immunodeficiency virus (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, weeks 4, 48, 96, and 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 compared with >100 cells/µl. No significant difference was found between the CD4⁺ strata 100-199 and 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 was found in baseline HIV RNA levels, treatment regimen, or sex.

CONCLUSION

Plasma NfL is a sensitive biomarker to assess ongoing central nervous system 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.

The presence of resistance‐associated mutations in reverse transcriptase gene is associated with cerebrospinal fluid HIV‐1 escape: A multicentric retrospective analysis

Higher risk of cerebrospinal fluid escape (CVE) has been associated with the use of specific antiretroviral (ARV) classes, such as protease inhibitors. We assessed whether archived resistance-associated mutations (RAMs) can mediate this relationship by identifying patients treated with incompletely active antiretroviral regimens. A retrospective multicentric study on 282 adult people with HIV on antiretroviral therapy (ART) and available historical plasma genotype resistance testing (HGRT) for reverse transcriptase (RT) and protease genes between 2001 and 2021. The odds ratio for demographic, clinic-, and ART-related variables and CVE was estimated by multivariable modeling. HGRT-adjusted central nervous system effectiveness penetration (CPE) score was computed in modeling the risk. Median age, plasma VL, and CD4 count were 49 years, <50 copies/mL, and 310 cells/μL. CVE was detected in 51 participants (17.0%). No difference in CVE prevalence was observed according to ART type, number of ARVs or ARV classes. Participants with CVE had more frequently plasma (52.9% vs. 32.1%, p = 0.005) and CSF RAMs in RT (n = 63, 57.1% vs. 28.6%, p = 0.029), but not in protease gene. The presence of plasma RAMs in RT associated with increased odds of CVE in adjusted analyses (aOR 3.9, p < 0.001) and in models restricted to plasma viral load ≤50 copies/mL (n = 202; aOR 4.3, p = 0.003). CVE risk decreased by 40% per each point increase in HGRT-adjusted CPE score in multivariable models (p < 0.001). Rather than the type of ARV classes or of ART regimens, functional mono or dual regimens caused by the presence of RAMs affecting ART components may explain the majority of cases of CVE.

Cohort profile: InfCareHIV, a prospective registry-based cohort study of people with diagnosed HIV in Sweden

PURPOSE

The Swedish InfCareHIV cohort was established in 2003 to ensure equal and effective care of people living with HIV (PLHIV) and enable long-term follow-up. InfCareHIV functions equally as a decision support system as a quality registry, ensuring up-to-date data reported in real time.

PARTICIPANTS

InfCareHIV includes data on >99% of all people with diagnosed HIV in Sweden and up to now 13 029 have been included in the cohort. InfCareHIV includes data on HIV-related biomarkers and antiretroviral therapies (ART) and also on demographics, patient-reported outcome measures and patient-reported experience measures.

FINDINGS TO DATE

Sweden was in 2015 the first country to reach the UNAIDS (United Nations Programme on HIV/AIDS)/WHO's 90-90-90 goals. Late diagnosis of HIV infection was identified as a key problem in the Swedish HIV-epidemic, and low-level HIV viraemia while on ART associated with all-cause mortality. Increased HIV RNA load in the cerebrospinal fluid (CSF) despite suppression of the plasma viral load was found in 5% of PLHIV, a phenomenon referred to as 'CSF viral escape'. Dolutegravir-based treatment in PLHIV with pre-existing nucleoside reverse transcriptase inhibitor-mutations was non-inferior to protease inhibitor-based regimens. An increase of transmitted drug resistance was observed in the InfCareHIV cohort. Lower efficacy for protease inhibitors was not due to lower adherence to treatment. Incidence of type 2 diabetes and insulin resistance was high in the ageing HIV population. Despite ART, the risk of infection-related cancer as well as lung cancer was increased in PLHIV compared with HIV-negative. PLHIV were less likely successfully treated for cervical precancer and more likely to have human papillomavirus types not included in current HPV vaccines. Self-reported sexual satisfaction in PLHIV is improving and is higher in women than men.

FUTURE PLANS

InfCareHIV provides a unique base to study and further improve long-term treatment outcomes, comorbidity management and health-related quality of life in people with HIV in Sweden.

Role of microglia in HIV-1 infection

The usage of antiretroviral treatment (ART) has considerably decreased the morbidity and mortality related to HIV-1 (human immunodeficiency virus type 1) infection. However, ART is ineffective in eradicating the virus from the persistent cell reservoirs (e.g., microglia), noticeably hindering the cure for HIV-1. Microglia participate in the progression of neuroinflammation, brain aging, and HIV-1-associated neurocognitive disorder (HAND). Some methods have currently been studied as fundamental strategies targeting microglia. The purpose of this study was to comprehend microglia biology and its functions in HIV-1 infection, as well as to look into potential therapeutic approaches targeting microglia.

Residual Central Nervous System Immune Activation Is Not Prevented by Antiretroviral Therapy Initiated During Early Chronic HIV Infection

Background

Antiretroviral therapy (ART) initiated during acute infection can potentially impact the central nervous system (CNS) reservoir, but the differential long-term effects of ART initiation during early or late chronic infection are unknown.

Methods

We included neuroasymptomatic people with human immunodeficiency virus (HIV) with suppressive ART initiated during chronic (>1 year since transmission) HIV with archived cerebrospinal fluid (CSF) and serum samples after 1 and/or ≥3 years of ART from a cohort study. CSF and serum neopterin was measured using a commercial immunoassay (BRAHMS, Germany).

Results

In total, 185 people with HIV (median, 79 [interquartile range, 55-128] months on ART) were included. A significant inverse correlation was found between CD4⁺ T-cell count and CSF neopterin only at baseline (r = -0.28, P = .002), but not after 1 (r = -0.026, P = .8) or ≥3 (r -0.063, P = .5) years of ART. No significant differences were seen in CSF or serum neopterin concentrations between different pretreatment CD4⁺ T-cell strata after 1 or ≥3 (median, 6.6) years of ART.

Conclusions

In people with HIV initiating ART during chronic infection, occurrence of residual CNS immune activation was not correlated with pretreatment immune status, even when treatment was initiated at high CD4⁺ T-cell counts, suggesting that the CNS reservoir, once established, is not differentially affected by the timing of ART initiation during chronic infection.

CNS efficacy parameters of combination antiretroviral therapy in chronic HIV infection: A multi-voxel magnetic resonance spectroscopy study

This study aimed to determine the correlations of combination antiretroviral therapy (cART) efficacy parameters in the central nervous system (CNS) with a neurometabolic profile on magnetic resonance spectroscopy (MRS) in virally suppressed, neurologically asymptomatic HIV+ individuals. In total, 32 HIV+ individuals on stable cART with an average age of 41.97 ± 10.12 years and with available clinical data, CNS penetration effectiveness (CPE), and monocyte efficacy (ME) scores underwent multi-voxel MRS. The parameters of neuronal number/function (NAA/Cr), membrane turnover (Cho/Cr), and glial proliferation (mI/Cr) were analyzed in supratentorial white and gray matter. Correlations of CPE and ME with neurometabolic ratios were performed using Pearson's correlation test. Statistical significance was set at p < 0.05. A strong positive correlation was observed between Cho/Cr and CPE in the left parietal subcortical white matter (r = 0.577, p = 0.001). A strong positive correlation between NAA/Cr and ME was obtained in the left (r = 0.521, p = 0.003) and the right (r = 0.494, p = 0.005) posterior cingulate. A strong negative correlation between ME and Cho/Cr ratios was observed in the right frontal deep white matter (r = -0.569, p = 0.001). Indices designed to assess cART efficacy in CNS failed to present significant correlations with the neurometabolic profile obtained using MRS. There is a need to define more potent non-invasive tools for neuroinflammation assessment given the prolonged life expectancy in the HIV+ population.

Elevation of brain ADC (apparent diffusion coefficient) in HIV-associated neurocognitive disorders and evolution after treatment: A pilot study

BACKGROUND

Thirty to 50% of HIV-infected patients develop HIV-Associated Neurocognitive Disorders (HAND) despite virological control. The previously published Neuro+3 study showed their neurocognitive status can be improved by intensifying antiviral therapy. Our study is a part of the Neuro3+ study and aims to study apparent diffusion coefficient (ADC) as a biomarker for neurological improvement.

PATIENTS AND METHODS

We prospectively included 31 patients with HAND. They received therapy with better CNS Penetration Effectiveness (CPE) score with two-year follow-up. Cognitive status was assessed at day 0 (D0) and week 96 (W96) using Frascati 3-stage classification and Global Deficit Score (GDS). Brain MRI at D0 and W96 assessed morphological data (white matter hyperintensities, opportunistic infections, ischemic lesions, atrophy) and measured whole brain apparent diffusion coefficient (ADC). We compared their data with a control group of 20 healthy patients with similar ages and sex ratio.

RESULTS

After ARV intensification, cognitive status was significantly improved: GDS (n = 1,4 vs 1,0 p = 0.01) and Frascati scale (2HAD/22MND/7ANI vs 1HAD/8MND/17ANI p = 0.001). Mean ADC was significantly higher in patients at inclusion than in controls (0.88 × 10^-3 mm²/s ± 0.06 vs 0.81 × 10^-3 mm²/s ± 0.04, p = 0.0001). ADC decreased after treatment (0.88 × 10^-3 mm²/s ± 0.06 vs 0.85 × 10^-3 mm²/s ± 0.06 (p = 0,04). In subgroup analysis, ADC significantly decreased in clinically improved patients (0.89 × 10^-3 mm²/s ± 0.07 vs 0.85 × 10^-3 mm²/s ± 0.07 (p = 0,03)) and did not significantly change in non-clinically improved patients (0.86 × 10^-3 mm²/s ± 0.07 vs 0.84 × 10^-3 mm²/s ± 0.07 (p = 0,31)). After treatment, there was no significant difference between patients and controls (0.85 × 10^-3 mm²/s ± 0.06 vs 0.81 × 10^-3 mm²/s ± 0.04, p = 0.17).

CONCLUSION

Whole-brain ADC is a good biomarker of HIV-associated neurocognitive disorders. It is significantly increased in patients with HAND compared with controls and significantly decreases after treatment. It is all the more important to have a quantitative biomarker as conventional imaging does not contribute to the diagnosis.

Animal models for studies of HIV-1 brain reservoirs

The HIV-1 often evades a robust antiretroviral-mediated immune response, leading to persistent infection within anatomically privileged sites including the CNS. Continuous low-level infection occurs in the presence of effective antiretroviral therapy (ART) in CD4+ T cells and mononuclear phagocytes (MP; monocytes, macrophages, microglia, and dendritic cells). Within the CNS, productive viral infection is found exclusively in microglia and meningeal, perivascular, and choroidal macrophages. MPs serve as the principal viral CNS reservoir. Animal models have been developed to recapitulate natural human HIV-1 infection. These include nonhuman primates, humanized mice, EcoHIV, and transgenic rodent models. These models have been used to study disease pathobiology, antiretroviral and immune modulatory agents, viral reservoirs, and eradication strategies. However, each of these models are limited to specific component(s) of human disease. Indeed, HIV-1 species specificity must drive therapeutic and cure studies. These have been studied in several model systems reflective of latent infections, specifically in MP (myeloid, monocyte, macrophages, microglia, and histiocyte cell) populations. Therefore, additional small animal models that allow productive viral replication to enable viral carriage into the brain and the virus-susceptible MPs are needed. To this end, this review serves to outline animal models currently available to study myeloid brain reservoirs and highlight areas that are lacking and require future research to more effectively study disease-specific events that could be useful for viral eradication studies both in and outside the CNS.

Developments in Neuroprotection for HIV-Associated Neurocognitive Disorders (HAND)

PURPOSE OF REVIEW

Reducing the risk of HIV-associated neurocognitive disorders (HAND) is an elusive treatment goal for people living with HIV. Combination antiretroviral therapy (cART) has reduced the prevalence of HIV-associated dementia, but milder, disabling HAND is an unmet challenge. As newer cART regimens that more consistently suppress central nervous system (CNS) HIV replication are developed, the testing of adjunctive neuroprotective therapies must accelerate.

RECENT FINDINGS

Successes in modifying cART regimens for CNS efficacy (penetrance, chemokine receptor targeting) and delivery (nanoformulations) in pilot studies suggest that improving cART neuroprotection and reducing HAND risk is achievable. Additionally, drugs currently used in neuroinflammatory, neuropsychiatric, and metabolic disorders show promise as adjuncts to cART, likely by broadly targeting neuroinflammation, oxidative stress, aerobic metabolism, and/or neurotransmitter metabolism. Adjunctive cognitive brain therapy and aerobic exercise may provide additional efficacy. Adjunctive neuroprotective therapies, including available FDA-approved drugs, cognitive therapy, and aerobic exercise combined with improved cART offer plausible strategies for optimizing the prevention and treatment of HAND.

Risk Factors for CSF/Plasma HIV-1 RNA Discordance in HIV-Infected Patients

BACKGROUND

Few large investigations have evaluated the association of cerebrospinal fluid/plasma (CSF/plasma) discordance with opportunistic neurological infections. We aimed to determine risk factors for CSF/plasma discordance to further assess whether CSF/plasma discordance is associated with antiretroviral therapy (ART) and opportunistic neurological infections.

METHODS

A retrospective study was conducted based on HIV RNA viral load and associated risk factors in plasma and CSF samples from 491 HIV-infected patients. HIV RNA levels higher in CSF compared with plasma was defined as CSF/plasma discordance.

RESULTS

In this study, the rate of CSF/plasma discordance was 18.3%. We observed that headache, cryptococcal antigen, CSF cell count, Treponema pallidum particle assay positivity, and ART use were significantly associated with CSF/plasma discordance in the multivariate logistic regression model. The CSF RNA/plasma RNA ratio was significantly higher in HIV-infected patients with neurological infections than in HIV-infected cases without neurological infections (P < 0.001). CSF/plasma discordance was significantly different between HIV-infected patients without central nervous system (CNS) infection and those with CNS infection, tuberculous meningitis, cryptococcal meningitis, and neurosyphilis (P < 0.05).

CONCLUSIONS

ART and CNS inflammation may influence CSF/plasma discordance.

Neuropathogenesis of HIV-1: insights from across the spectrum of acute through long-term treated infection

This review outlines the neuropathogenesis of HIV, from initial HIV entry into the central nervous system (CNS) to chronic infection, focusing on key advancements in the last 5 years. Discoveries regarding acute HIV infection reveal timing and mechanisms of early HIV entry and replication in the CNS, early inflammatory responses, and establishment of genetically distinct viral reservoirs in the brain. Recent studies additionally explore how chronic HIV infection is maintained in the CNS, examining how the virus remains in a latent "hidden" state in diverse cells in the brain, and how this leads to sustained pathological inflammatory responses. Despite viral suppression with antiretroviral therapy, HIV can persist and even replicate in the CNS, and associate with ongoing neuropathology including CD8 + T-lymphocyte mediated encephalitis. Crucial investigation to advance our understanding of the immune mechanisms that both control viral infection and lead to pathological consequences in the brain is necessary to develop treatments to optimize long-term neurologic health in people living with HIV.

Neuropathogenesis of HIV and emerging therapeutic targets

INTRODUCTION

HIV infection causes a wide range of neurological complications, many of which are among the most common complications of chronic HIV infection in the era of combined antiretroviral therapy. These neurological conditions arise due to complex interactions between HIV viral proteins and neuronal and glial cells that lead to the activation of various inflammatory and neurotoxic pathways across the nervous system.

AREAS COVERED

This review summarizes the current literature on the pathogenesis and clinical manifestations of neurological injuries associated with HIV in the brain, spinal cord, and peripheral nervous system. Molecular pathways relevant for possible therapeutic targets or advancements are emphasized. Gaps in knowledge and current challenges in therapeutic design are also discussed.

EXPERT OPINION

Several challenges exist in the development of therapeutic targets for HIV-associated cognitive impairments. However, recent developments in drug delivery systems and treatment strategies are encouraging. Treatments for HIV-associated pain and peripheral sensory neuropathies currently consist of symptomatic management, but a greater understanding of their pathogenesis can lead to the development of targeted molecular therapies and disease-modifying therapies. HIV-associated autonomic dysfunction may affect the course of systemic disease via disrupted neuro-immune interactions; however, more research is needed to facilitate our understanding of how these processes present clinically.

Association of High Ratio of CSF/Plasma HIV-1 RNA with Central Nervous System Co-Infection in HIV-1-Positive Treatment-Naive Patients

Cerebrospinal fluid (CSF) human immunodeficiency virus-1 (HIV-1) ribonucleic acid (RNA) at higher levels than in plasma has been observed in HIV-1-positive patients and defined as CSF/plasma discordance or CSF escape. Discordance is particularly seen in untreated patients with antiretroviral agents. Quantitative data regarding its association with blood−brain barrier (BBB) damage and intracranial co-infection with other pathogens are limited. Therefore, we used the CSF to plasma HIV-1 RNA ratio (HRR) to determine its relation to central nervous system (CNS) co-infection in HIV-1-positive treatment-naïve individuals. We retrospectively recruited the subjects with HIV-1-positive and potential neurological deficits. A lumbar puncture was performed before the antiretroviral therapy. The paired CSF/plasma HIV-1 RNA samples were analyzed. Univariate and multivariate logistic regression models and multiple spine regression analyses were performed to assess the association between the HRR and CNS co-infection. A total of 195 patients with 78% males (median age: 49 years) were included in this study, of whom 98 (50.2%) had CNS co-infection with other pathogens. The receiver-operating characteristic curve analysis showed that the optimal cutoff value for the HRR to predict the CNS co-infection was 1.00. Higher HRR (≥1) was significantly associated with tuberculous meningitis (OR 6.50, 95% CI 2.08−20.25, p = 0.001), cryptococcus meningitis (OR 7.58, 95% CI 2.10−27.32, p = 0.001), and multiple co-infection (OR 4.04, 95% CI 1.02−16.04, p = 0.047). Higher HRR (≥1) (OR 3.01, 95% CI 1.09−8.73, p = 0.032) was independently associated with the CNS co-infection after adjusting for covariates. No significant nonlinear association was found between the HRR and CNS co-infection in the multivariate spline regression (p > 0.05) and a positive relationship was found between the HRR and CNS co-infection when the HRR was ≥0.78. Higher HRR was associated with an increased risk of CNS co-infection in HIV-1-positive patients. The relationship between the HRR and CNS co-infection may be related to the BBB disturbance and warrants further investigation with a large, longitudinal cohort.

Neuroimmunology of CNS HIV Infection: A Narrative Review

This short review provides an overview of the interactions of human immunodeficiency virus type 1 (HIV), immune and inflammatory reactions, and CNS injury over the course of infection. Systemic infection is the overall driver of disease and serves as the “platform” for eventual CNS injury, setting the level of immune dysfunction and providing both the HIV seeding and immune-inflammatory responses to the CNS. These systemic processes determine the timing of and vulnerability to HIV-related neuronal injury which occurs in a separate “compartment” with features that parallel their systemic counterparts but also evolve independently. Direct CNS HIV infection, along with opportunistic infections, can have profound neurological consequences for the infected individual. HIV-related CNS morbidities are of worldwide importance but are enhanced by the particular epidemiological, socioeconomic and environmental factors that heighten the impact of HIV infection in Africa.

HIV Compartmentalization in the CNS and Its Impact in Treatment Outcomes and Cure Strategies

PURPOSE OF REVIEW

This review focuses on the cerebrospinal fluid (CSF) findings in connection to the central nervous system (CNS) reservoir in treatment-naïve and virally suppressed PLWH, followed by the findings in CSF HIV-1 escape and analytical treatment interruption studies.

RECENT FINDINGS

Compared to chronic infection, initiating antiretroviral therapy (ART) during acute HIV-1 infection results in more homogeneous longitudinal benefits in the CNS. Viral variants in CSF HIV-1 escape are independently linked to infected cells from the systemic reservoir and in the CNS, highlighting the phenomenon as a consequence of different mechanisms. HIV-infected cells persist in CSF in nearly half of the individuals on stable ART and are associated with worse neurocognitive performance. Future studies should probe into the origin of the HIV-infected cells in the CSF. Examining the capacity for viral replication would provide new insight into the CNS reservoir and identify strategies to eradicate it or compensate for the insufficiency of ART.

HIV Latency in Myeloid Cells: Challenges for a Cure

The use of antiretroviral therapy (ART) for Human Immunodeficiency Virus (HIV) treatment has been highly successful in controlling plasma viremia to undetectable levels. However, a complete cure for HIV is hindered by the presence of replication-competent HIV, integrated in the host genome, that can persist long term in a resting state called viral latency. Resting memory CD4+ T cells are considered the biggest reservoir of persistent HIV infection and are often studied exclusively as the main target for an HIV cure. However, other cell types, such as circulating monocytes and tissue-resident macrophages, can harbor integrated, replication-competent HIV. To develop a cure for HIV, focus is needed not only on the T cell compartment, but also on these myeloid reservoirs of persistent HIV infection. In this review, we summarize their importance when designing HIV cure strategies and challenges associated to their identification and specific targeting by the “shock and kill” approach.

Crucial Role of Central Nervous System as a Viral Anatomical Compartment for HIV-1 Infection

The chronic infection established by the human immunodeficiency virus 1 (HIV-1) produces serious CD4+ T cell immunodeficiency despite the decrease in HIV-1 ribonucleic acid (RNA) levels and the raised life expectancy of people living with HIV-1 (PLWH) through treatment with combined antiretroviral therapies (cART). HIV-1 enters the central nervous system (CNS), where perivascular macrophages and microglia are infected. Serious neurodegenerative symptoms related to HIV-associated neurocognitive disorders (HAND) are produced by infection of the CNS. Despite advances in the treatment of this infection, HAND significantly contribute to morbidity and mortality globally. The pathogenesis and the role of inflammation in HAND are still incompletely understood. Principally, growing evidence shows that the CNS is an anatomical reservoir for viral infection and replication, and that its compartmentalization can trigger the evolution of neurological damage and thus make virus eradication more difficult. In this review, important concepts for understanding HAND and neuropathogenesis as well as the viral proteins involved in the CNS as an anatomical reservoir for HIV infection are discussed. In addition, an overview of the recent advancements towards therapeutic strategies for the treatment of HAND is presented. Further neurological research is needed to address neurodegenerative difficulties in people living with HIV, specifically regarding CNS viral reservoirs and their effects on eradication.

T cell derived HIV-1 is present in the CSF in the face of suppressive antiretroviral therapy

HIV cerebrospinal fluid (CSF) escape, where HIV is suppressed in blood but detectable in CSF, occurs when HIV persists in the CNS despite antiretroviral therapy (ART). To determine the virus producing cell type and whether lowered CSF ART levels are responsible for CSF escape, we collected blood and CSF from 156 neurosymptomatic participants from Durban, South Africa. We observed that 28% of participants with an undetectable HIV blood viral load showed CSF escape. We detected host cell surface markers on the HIV envelope to determine the cellular source of HIV in participants on the first line regimen of efavirenz, emtricitabine, and tenofovir. We confirmed CD26 as a marker which could differentiate between T cells and macrophages and microglia, and quantified CD26 levels on the virion surface, comparing the result to virus from in vitro infected T cells or macrophages. The measured CD26 level was consistent with the presence of T cell produced virus. We found no significant differences in ART concentrations between CSF escape and fully suppressed individuals in CSF or blood, and did not observe a clear association with drug resistance mutations in CSF virus which would allow HIV to replicate. Hence, CSF HIV in the face of ART may at least partly originate in CD4+ T cell populations.

Doravirine Achieves Adequate CSF Exposure and is Mostly Unbound to Proteins

We determined total and unbound concentrations of Doravirine (DOR) in cerebrospinal fluid (CSF) and blood plasma. Total and unbound DOR concentrations in CSF exceeded the EC50 value against wild-type virus (5.1 ng/mL) in all subjects suggesting that DOR may contribute to inhibit viral replication in this compartment.

Association between Veterans Aging Cohort Study (VACS) index and neurocognitive function among people living with HIV-a cross sectional study in coastal South India

Background

HIV is an infectious disease affecting 36.7 million people worldwide. In recent times, Antiretroviral Therapy (ART) has become accessible to the majority of People Living with HIV (PLHIV) and this has transformed the course of infection to one that is chronic, characterized by fewer diseases pathognomonic of AIDS. In view of this, there is a pressing need for better markers, apart from the routine HIV indicators, to detect comorbidities such as Neurocognitive Impairment (NCI). The aim of this study was to find out the association between Veterans Aging Cohort Study (VACS) index and Neurocognitive function in HIV positive patients.

Methods

In our study, we included 97 HIV positive patients and their Neurocognitive function was assessed using a combination of Montreal Cognitive Assessment and Grooved Pegboard Test, while VACS index was calculated using the most recent laboratory values. Binomial Logistics Regression analyses, adjusting for potential confounding variables, was performed to determine the association between VACS score and Neurocognitive Impairment.

Results

We found that a higher VACS Index was associated with global and domain-wise Neurocognitive impairment (p < 0.01), specifically in the domains of attention (p < 0.01) and fine motor skills (p = 0.01). Our study also showed that among all the VACS components, older age (p = 0.02) and lower hemoglobin (p < 0.01) values were associated with global NCI. After plotting an ROC curve, a VACS cut-off score of 11.00 was identified as it had good sensitivity (87.0%) and specificity (71.4%) in identifying Global NCI.

Conclusion

Our findings extend prior research on the use of VACS Index to predict global and domain-wise NCI in HIV-positive patients. However, further research with more comprehensive neurocognitive testing is required in our setting before VACS Index can be used as a tool to screen for neurocognitive dysfunction among PLHIV.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12981-021-00368-6.

HIV-1 persistence in the CNS: Mechanisms of latency, pathogenesis and an update on eradication strategies

Despite four decades of research into the human immunodeficiency virus (HIV-1), a successful strategy to eradicate the virus post-infection is lacking. The major reason for this is the persistence of the virus in certain anatomical reservoirs where it can become latent and remain quiescent for as long as the cellular reservoir is alive. The Central Nervous System (CNS), in particular, is an intriguing anatomical compartment that is tightly regulated by the blood-brain barrier. Targeting the CNS viral reservoir is a major challenge owing to the decreased permeability of drugs into the CNS and the cellular microenvironment that facilitates the compartmentalization and evolution of the virus. Therefore, despite effective antiretroviral (ARV) treatment, virus persists in the CNS, and leads to neurological and neurocognitive deficits. To date, viral eradication strategies fail to eliminate the virus from the CNS. To facilitate the improvement of the existing elimination strategies, as well as the development of potential therapeutic targets, the aim of this review is to provide an in-depth understanding of HIV latency in CNS and the onset of HIV-1 associated neurological disorders.

Interrogating the impact of combination antiretroviral therapies on HIV-associated neurocognitive disorders

OBJECTIVES

Although the advent of Combination Antiretroviral Therapy (cART) has greatly reduced the prevalence of HIV-Associated Dementia, the most severe form of HIV-Associated Neurocognitive Disorder (HAND), the incidence of the milder forms of HAND have risen. The explanations proposed include persistent central nervous system (CNS) viraemia and the neurotoxicity of chronic cART regimens. Nonetheless, controversies in HAND prevalence estimates, alongside a lack of consensus on the significance of CNS Penetration Effectiveness (CPE) have added to the complexity of elucidating the role of cART in HAND. The present review will evaluate the evidence underlying these explanations, as well as highlighting the need for improved trial designs and the incorporation of emerging biomarkers and neuroimaging tools.

METHODS

A review of the current literature investigating cART neurotoxicity, controversies in HAND prevalence estimates, CNS Penetration Effectiveness, and neuroprotective adjuvant therapies.

CONCLUSIONS

Ultimately, the inadequacy of cART in achieving complete preservation of the CNS underscores the imminent need for neuroprotective adjuvant therapies, where the efficacy of combining multiple adjuvant classes presents a potential therapeutic frontier which must be interrogated.

Improved delivery of broadly neutralizing antibodies by nanocapsules suppresses SHIV infection in the CNS of infant rhesus macaques

Broadly neutralizing antibodies (bNAbs) directed to HIV-1 have shown promise at suppressing viremia in animal models. However, the use of bNAbs for the central nervous system (CNS) infection is confounded by poor penetration of the blood brain barrier (BBB). Typically, antibody concentrations in the CNS are extremely low; with levels in cerebrospinal fluid (CSF) only 0.1% of blood concentrations. Using a novel nanotechnology platform, which we term nanocapsules, we show effective transportation of the human bNAb PGT121 across the BBB in infant rhesus macaques upon systemic administration up to 1.6% of plasma concentration. We demonstrate that a single dose of PGT121 encased in nanocapsules when delivered at 48h post-infection delays early acute infection with SHIV_SF162P3 in infants, with one of four animals demonstrating viral clearance. Importantly, the nanocapsule delivery of PGT121 improves suppression of SHIV infection in the CNS relative to controls.

In patients where HIV-1 is fully suppressed by antiretroviral drugs, HIV-1 still persists in reservoirs. If antiretroviral drugs are stopped, the virus will emerge from these reservoirs and re-seeds systemically. The central nervous system (CNS) is proposed to be a tissue compartment that harbors other HIV-1 reservoirs. A key obstacle that constrains the treatment for the CNS infection is the blood–brain barrier (BBB), a highly restrictive barrier separating the circulating blood from the brain and extracellular fluid in the CNS, which impedes ~98% of the small molecule therapeutics and almost all macromolecules including broadly neutralizing antibodies (bNAbs) directed to HIV-1. Our “nanocapsule” strategy is based on a nanotechnology wherein bNAb molecules are encapsulated within nanocapsules of which the surface contains abundant choline and acetylcholine analogues. This design allows the nanocapsules to effectively cross the BBB to deliver bNAbs into the CNS upon systemic administration and show an impact of bNAb on CNS reservoirs in SHIV infected infant macaques.

Improvement of HIV-associated neurocognitive disorders after antiretroviral therapy intensification: the Neuro+3 study

OBJECTIVES

Despite the effectiveness of antiretroviral (ARV) therapy to control HIV infection, HIV-associated neurocognitive disorders (HAND) remain frequent. The Neuro+3 study assessed the cognitive improvement associated with ARV intensification based on increased CNS penetration effectiveness (CPE) scoring ≥+3 and total CPE score ≥9.

METHODS

Thirty-one patients, aged 18-65 years, with confirmed diagnosis of HAND and effective ARV therapy were included. The cognitive improvement was measured using Frascati three-stage classification and global deficit score (GDS) after 48 and 96 weeks of ARV intensification. Ultrasensitive HIV-RNA, neopterin, soluble CD14, CCL2, CXCL10, IL6, IL8 and NF-L were measured in plasma and cerebrospinal fluid at Day 0 (baseline), Week 48 (W48) and W96.

RESULTS

The intensified ARV was associated with a median (IQR) CPE score increase from 6 (4-7) at baseline to 10 (9-11). From baseline to W96, the median (IQR) GDS decreased from 1.4 (0.8-2.2) to 1.0 (0.6-2.0) (P = 0.009); HAND classification improved from 2 to 1 HIV-associated dementia, 22 to 8 mild neurocognitive disorders, 7 to 17 asymptomatic neurocognitive impairment and 0 to 5 patients without any neurocognitive alterations (P = 0.001). In multivariable linear regression analysis, GDS improvement at W96 was significantly associated with CPE score ≥9 after intensification (P = 0.014), CD4 lymphocyte increase at W48 (P < 0.001) and plasma CXCL10 decrease at W96 (P = 0.001).

CONCLUSIONS

In patients with HAND, a significant cognitive improvement was observed after the ARV intensification strategy, with a higher CPE score. Cognitive improvement was more often observed in the case of a switch of two drug classes, arguing for better control of CNS HIV immune activation.

Mechanisms of residual immune activation in HIV-1-infected human lymphoid tissue ex vivo

OBJECTIVE

HIV-1 infection triggers immune activation, as reflected by the upregulation of various cytokines. This immune activation remains elevated despite antiretroviral therapy (ART) and leads to early age-related diseases. Here, we addressed the mechanisms of sustained immune activation in HIV-1-infected human lymphoid tissues ex vivo.

DESIGN/METHOD

We investigated several potential causes of immunoactivation, including: a proinflammatory effect of ART drugs themselves; an early HIV-1-triggered cytokine storm, which could in turn trigger a sustained cytokine dysregulation; herpesvirus reactivation; HIV-1 protein release; and production of defective virions and extracellular vesicles. Tissue immune activation was evaluated from measurements of cytokines in culture medium using multiplexed immunoassays.

RESULTS

Neither ART itself nor simulated cytokine storms nor exogenously added HIV-1 proteins triggered a sustained cytokine upregulation. In contrast, defective (replicative-incompetent) virions and extracellular vesicles induced sustained cytokine upregulation, as did infectious virus. Tissue immune activation was accompanied by reactivation of cytomegalovirus.

CONCLUSION

The system of ex-vivo human lymphoid tissue allowed investigation, under laboratory-controlled conditions, of possible mechanisms involved in persistent immune activation in HIV-1 patients under ART. Mechanisms of this immunoactivation identified in ex-vivo tissues may indicate potential therapeutic targets for restoration of immune system homeostasis in HIV-1-infected patients.

Central nervous system (CNS) transcriptomic correlates of human immunodeficiency virus (HIV) brain RNA load in HIV-infected individuals

To generate new mechanistic hypotheses on the pathogenesis and disease progression of neuroHIV and identify novel therapeutic targets to improve neuropsychological function in people with HIV, we investigated host genes and pathway dysregulations associated with brain HIV RNA load in gene expression profiles of the frontal cortex, basal ganglia, and white matter of HIV+ patients. Pathway analyses showed that host genes correlated with HIV expression in all three brain regions were predominantly related to inflammation, neurodegeneration, and bioenergetics. HIV RNA load directly correlated particularly with inflammation genesets representative of cytokine signaling, and this was more prominent in white matter and the basal ganglia. Increases in interferon signaling were correlated with high brain HIV RNA load in the basal ganglia and the white matter although not in the frontal cortex. Brain HIV RNA load was inversely correlated with genesets that are indicative of neuronal and synaptic genes, particularly in the cortex, indicative of synaptic injury and neurodegeneration. Brain HIV RNA load was inversely correlated with genesets that are representative of oxidative phosphorylation, electron transfer, and the tricarboxylic acid cycle in all three brain regions. Mitochondrial dysfunction has been implicated in the toxicity of some antiretrovirals, and these results indicate that mitochondrial dysfunction is also associated with productive HIV infection. Genes and pathways correlated with brain HIV RNA load suggest potential therapeutic targets to ameliorate neuropsychological functioning in people living with HIV.

Anti-HIV Activity of Cucurbitacin-D against Cigarette Smoke Condensate-Induced HIV Replication in the U1 Macrophages

Chemodietary agents are emerging as promising adjuvant therapies in treating various disease conditions. However, there are no adjuvant therapies available to minimize the neurotoxicity of currently existing antiretroviral drugs (ARVs). In this study, we investigated the anti-HIV effect of a chemodietary agent, Cucurbitacin-D (Cur-D), in HIV-infected macrophages using an in-vitro blood-brain barrier (BBB) model. Since tobacco smoking is prevalent in the HIV population, and it exacerbates HIV replication, we also tested the effect of Cur-D against cigarette smoke condensate (CSC)-induced HIV replication. Our results showed that Cur-D treatment reduces the viral load in a dose-dependent (0-1 μM) manner without causing significant toxicity at <1 μM concentration. Further, a daily dose of Cur-D (0.1 μM) not only reduced p24 in control conditions, but also reduced CSC (10 μg/mL)-induced p24 in U1 cells. Similarly, Cur-D (single dose of 0.4 μM) significantly reduced the CSC (single dose of 40 μg/mL)-induced HIV replication across the BBB model. In addition, treatment with Cur-D reduced the level of pro-inflammatory cytokine IL-1β. Therefore, Cur-D, as an adjuvant therapy, may be used not only to suppress HIV in the brain, but also to reduce the CNS toxicity of currently existing ARVs.

Compartmentalization of cerebrospinal fluid inflammation across the spectrum of untreated HIV-1 infection, central nervous system injury and viral suppression

OBJECTIVE

To characterize the evolution of central nervous system (CNS) inflammation in HIV-1 infection applying a panel of cerebrospinal fluid (CSF) inflammatory biomarkers to grouped subjects representing a broad spectrum of systemic HIV-1 immune suppression, CNS injury and viral control.

METHODS

This is a cross-sectional analysis of archived CSF and blood samples, assessing concentrations of 10 functionally diverse soluble inflammatory biomarkers by immunoassays in 143 HIV-1-infected subjects divided into 8 groups: untreated primary HIV-1 infection (PHI); four untreated groups defined by their blood CD4+ T lymphocyte counts; untreated patients presenting with subacute HIV-associated dementia (HAD); antiretroviral-treated subjects with ≥1 years of plasma viral suppression; and untreated elite controllers. Twenty HIV-1-uninfected controls were included for comparison. Background biomarkers included blood CD4+ and CD8+ T lymphocytes, CSF and blood HIV-1 RNA, CSF white blood cell (WBC) count, CSF/blood albumin ratio, CSF neurofilament light chain (NfL), and CSF t-tau.

FINDINGS

HIV-1 infection was associated with a broad compartmentalized CSF inflammatory response that developed early in its course and changed with systemic disease progression, development of neurological injury, and viral suppression. CSF inflammation in untreated individuals without overt HAD exhibited at least two overall patterns of inflammation as blood CD4+ T lymphocytes decreased: one that peaked at 200-350 blood CD4+ T cells/μL and associated with lymphocytic CSF inflammation and HIV-1 RNA concentrations; and a second that steadily increased through the full range of CD4+ T cell decline and associated with macrophage responses and increasing CNS injury. Subacute HAD was distinguished by a third inflammatory profile with increased blood-brain barrier permeability and robust combined lymphocytic and macrophage CSF inflammation. Suppression of CSF and blood HIV-1 infections by antiretroviral treatment and elite viral control were associated with reduced CSF inflammation, though not fully to levels found in HIV-1 seronegative controls.

Review of the neurological aspects of HIV infection

There are almost 40 million people in the world who live with the human immunodeficiency virus (HIV). The neurological manifestations associated with HIV contribute to significant morbidity and mortality despite the advances made with anti-retroviral therapy (ART). This review presents an approach to classification of neurological disorders in HIV, differentiating diseases due to the virus itself and those due to opportunistic infection. The effects of antiretroviral therapy are also discussed. The emphasis is on the developing world where advanced complications of HIV itself and infections such as tuberculosis (TB), toxoplasmosis and cryptococcal meningitis remain prevalent.

Minimal detection of cerebrospinal fluid escape after initiation of antiretroviral therapy in acute HIV-1 infection

OBJECTIVE

Despite suppression of HIV-1 replication in the periphery by antiretroviral therapy (ART), up to 10% of treated individuals have quantifiable HIV-1 in the CSF, termed CSF escape. CSF escape may be asymptomatic but has also been linked to progressive neurological disease, and may indicate persistence of HIV in the central nervous system (CNS). CSF escape has not yet been assessed after initiation of ART during acute HIV-1 infection (AHI).

DESIGN

Prospective cohort study.

SETTING

Major voluntary counseling and testing site in Bangkok, Thailand.

PARTICIPANTS

Participants identified and initiated on ART during AHI who received an optional study lumbar puncture at pre-ART baseline or after 24 or 96 weeks of ART.

MAIN OUTCOME MEASURES

Paired levels of CSF and plasma HIV-1 RNA, with CSF greater than plasma HIV-1 RNA defined as CSF escape.

RESULTS

Two hundred and four participants had paired blood and CSF sampling in at least one visit at baseline, week 24, or week 96. Twenty-nine participants had CSF sampling at all three visits. CSF escape was detected in 1/90 at week 24 (CSF HIV-1 RNA 2.50 log10 copies/ml, plasma HIV-1 RNA <50 copies/ml), and 0/55 at week 96.

CONCLUSION

Although levels of CSF HIV-1 RNA in untreated AHI are high, initiating treatment during AHI results in a very low rate of CSF escape in the first 2 years of treatment. Early treatment may improve control of HIV-1 within the CNS compared with treatment during chronic infection, which may have implications for long-term neurological outcomes and CNS HIV-1 persistence.

μ-Lat: A mouse model to evaluate human immunodeficiency virus eradication strategies

A critical barrier to the development of a human immunodeficiency virus (HIV) cure is the lack of a scalable animal model that enables robust evaluation of eradication approaches prior to testing in humans. We established a humanized mouse model of latent HIV infection by transplanting "J-Lat" cells, Jurkat cells harboring a latent HIV provirus encoding an enhanced green fluorescent protein (GFP) reporter, into irradiated adult NOD.Cg-Prkdcscid Il2rgtm1Wjl /SzJ (NSG) mice. J-Lat cells exhibited successful engraftment in several tissues including spleen, bone barrow, peripheral blood, and lung, in line with the diverse natural tissue tropism of HIV. Administration of tumor necrosis factor (TNF)-α, an established HIV latency reversal agent, significantly induced GFP expression in engrafted cells across tissues, reflecting viral reactivation. These data suggest that our murine latency ("μ-Lat") model enables efficient determination of how effectively viral eradication agents, including latency reversal agents, penetrate, and function in diverse anatomical sites harboring HIV in vivo.

Dual antiretroviral therapies are effective and safe regimens in the central nervous system of neurologically symptomatic people living with HIV

OBJECTIVE

Aim of this study was to compare cerebrospinal fluid (CSF) virological control, biomarkers and neurocognition of neurologically symptomatic patients on dual antiretroviral therapies (dual therapy) vs. 2 nucleoside reverse transcriptase inhibitors-based three-drug regimens (triple therapy).

DESIGN

Retrospective monocentric cross-sectional study.

METHODS

We analysed data from people living with HIV undergoing lumbar puncture for clinical/research reasons with plasma HIV-RNA less than 200 copies/ml and neurological/neurocognitive symptoms without significant contributing comorbidities. We measured CSF HIV-RNA, inflammation, blood-brain barrier integrity, neuronal damage and astrocytosis biomarkers (five biomarkers by ELISA and five indices by immunoturbidimetry) and recorded the neurocognitive performance (14 tests). CSF escape was defined as any case of CSF HIV-RNA 0.5 Log10 higher than viraemia or any case of detectable CSF HIV-RNA coupled with undetectable viraemia.

RESULTS

A total of 78 patients on triple therapy and 19 on dual therapy were included. Overall, 75.3% male, median age 51 years (46-58), current CD4 count 545 cells/μl (349-735), time on current regimens 18 months (8-29), but length of plasma suppression 32 months (14-94). The two groups did not differ in terms of HIV-associated neurological diagnoses, demographic and viro-immunological features. Undetectable CSF HIV-RNA (73.7% in dual therapy vs. 78.2% in triple therapy, p.67) and CSF escape (21.1% in dual therapy vs. 19.2% in triple therapy, p.86) did not differ. No difference was observed in depression, anxiety, neurocognition (in 63 participants) nor in any tested biomarker.

CONCLUSION

In people living with HIV with neurological/neurocognitive symptoms, peripherally effective dual therapy can show CSF virosuppression, inflammation, neuronal and astrocyte integrity and neurocognition comparable to triple therapy.

A rare case of HIV CNS escape in a patient previously considered a viral controller

Human immunodeficiency virus (HIV) ribonucleic acid (RNA) levels generally remain undetectable in the cerebrospinal fluid of people living with HIV with peripheral viral suppression. Secondary HIV central nervous system (CNS) escape refers to the rare independent replication of HIV RNA in the central nervous system despite peripheral viral suppression that occurs in the setting of a concomitant non-HIV infection. We describe here a young man with perinatal HIV infection considered a viral controller who developed secondary HIV CNS escape in the setting of a presumed fungal CNS infection.