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

Characterization of HIV variants from paired Cerebrospinal fluid and Plasma samples in primary microglia and CD4+ T-cells

Despite antiretroviral therapy (ART), HIV persistence in the central nervous system (CNS) continues to cause a range of cognitive impairments in people living with HIV (PLWH). Upon disease progression, transmigrating CCR5-using T-cell tropic viruses are hypothesized to evolve into macrophage-tropic viruses in the CNS that can efficiently infect low CD4-expressing cells, such as microglia. We examined HIV-1 RNA concentration, co-receptor usage, and CSF compartmentalization in paired CSF and blood samples from 19 adults not on treatment. Full-length envelope CSF- and plasma-derived reporter viruses were generated from 3 subjects and phenotypically characterized in human primary CD4+ T-cells and primary microglia. Median HIV RNA levels were higher in plasma than in CSF (5.01 vs. 4.12 log10 cp/mL; p = 0.004), and coreceptor usage was mostly concordant for CCR5 across the paired samples (n = 17). Genetically compartmentalized CSF viral populations were detected in 2 subjects, one with and one without neurological symptoms. All viral clones could replicate in T-cells (R5 T cell-tropic). In addition, 3 CSF and 1 plasma patient-derived viral clones also had the capacity to replicate in microglia/macrophages and, therefore have an intermediate macrophage tropic phenotype. Overall, with this study, we demonstrate that in a subset of PLWH, plasma-derived viruses undergo genetic and phenotypic evolution within the CNS, indicating viral infection and replication in CNS cells. It remains to be studied whether the intermediate macrophage-tropic phenotype observed in primary microglia represents a midpoint in the evolution towards a macrophage-tropic phenotype that can efficiently replicate in microglial cells and propagate viral infection in the CNS.

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.

Cerebrospinal fluid pleocytosis is associated with HIV-1 neuroinvasion during acute infection

OBJECTIVE

HIV-1 invades the brain within days post-transmission. This study quantitated cerebrospinal fluid (CSF) white blood cell count (WBC) and investigated whether it associated with plasma and CSF HIV-1 RNA during untreated acute HIV infection (AHI).

DESIGN

Seventy participants underwent lumbar puncture during Fiebig stages I-V AHI.

METHOD

WBC and HIV-1 RNA with a lower limit of quantification (LLQ) of 80 copies/ml were measured in CSF.

RESULTS

Sixty-nine (99%) participants were men, with a median age of 26. Their blood CD4 + and CD8 + T-cell counts were 335 [interquartile range (IQR) 247-553) and 540 (IQR 357-802) cells/μl, respectively. Forty-five (64%) were in Fiebig stages III-V whereas 25 (36%) were in Feibig stages I-II. Fifty-two (74%) experienced acute retroviral syndrome. Median plasma and CSF HIV-1 RNA were 6.10 (IQR 5.15-6.78) and 3.15 (IQR 1.90-4.11) log 10 copies/ml, respectively. Sixteen (23%) CSF samples had HIV-1 RNA below LLQ. Median CSF WBC was 2.5 (IQR 1-8) cells/μl. CSF pleocytosis (WBC >5) was observed in 33% and was only present in CSF samples with detectable HIV-1 RNA. The frequencies of CSF pleocytosis during Fiebig stages III-V and among CSF samples of higher viral load (>1000 copies/ml) were 42 and 45%, respectively. Pleocytosis independently associated with CSF HIV-1 RNA in multivariate analysis [adjusted coefficient: 0.79, 95% confidence interval (CI) 0.41-1.14), P  < 0.001] and a lower plasma to CSF HIV-1 RNA ratio ( P  < 0.001).

CONCLUSION

CSF pleocytosis was present in one-third of participants with AHI. It associated with higher CSF HIV-1 RNA and a lower plasma to CSF HIV-1 RNA ratio, suggesting a potential association with HIV-1 neuroinvasion.

Honokiol hexafluoro confers reversal of neuropathological markers of HIV infection in a murine SCID model

Cognitive impairment remains a persistent challenge in people living with HIV (PWLH) despite antiretroviral therapy (ART) due to ART's inability to eliminate brain HIV. HIV-induced cognitive dysfunction results from immune dysregulation, ongoing neuroinflammation, and the continuous virus presence, collectively contributing to cognitive deficits. Therefore, adjunctive therapies are needed to reduce cerebral HIV reservoirs, mitigate neuroinflammation, and impede cognitive dysfunction progression. Our study focused on Honokiol, known for its anti-inflammatory and neuroprotective properties, in an experimental mouse model simulating HIV-induced cognitive dysfunction. Using Honokiol Hexafluoro (HH), a synthetic analogue, we comprehensively evaluated its potential to ameliorate cognitive dysfunction and cerebral pathology in HIV-associated cognitive dysfunction. Our findings showed that HH treatment effectively reversed HIV-induced cognitive dysfunction, concurrently suppressing astrocyte activation, restoring neuronal dendritic arborization, and reducing microglial activation. Furthermore, HH remodeled the metabolic profile of HIV-infected human monocyte-derived macrophages, resulting in decreased activation and the promotion of a quiescent state in vitro.

Longitudinal analysis of CSF HIV RNA in untreated people with HIV: Identification of CSF controllers

Interindividual variation of human immunodeficiency virus (HIV) RNA setpoint in cerebrospinal fluid (CSF) and its determinants are poorly understood, but relevant for HIV neuropathology, brain reservoirs, viral escape, and reseeding after antiretroviral interruptions. Longitudinal multicentric study on demographic, clinical, and laboratory correlates of CSF HIV RNA in 2000 follow-up visits from 597 people with HIV (PWH) off antiretroviral therapy (ART) and with plasma HIV RNA > the lower limit of quantification (LLQ). Factors associated with CSF control (CSFC; CSF HIV RNA < LLQ while plasma HIV RNA > LLQ) and with CSF/plasma discordance (CSF > plasma HIV RNA > LLQ) were also assessed through mixed-effects models. Posthoc and sensitivity analyses were performed for persistent CSFC and ART-naïve participants, respectively. Over a median follow-up of 2.1 years, CSF HIV RNA was associated with CD4+ and CD8+ T cells, CSF leukocytes, blood-brain barrier (BBB) integrity, biomarkers of iron and lipid metabolism, serum globulins, past exposure to lamivudine, and plasma HIV RNA (model p < 0.0001). CSFC (persistent in 7.7% over 3 years) and CSF/plasma discordance (persistent in <0.01% over 1 year) were variably associated with the same parameters (model p < 0.001). Sensitivity analyses confirmed most of the previous associations in participants never exposed to ART. Persistent CSFC was associated with higher CD4+ T-cell count nadir (p < 0.001), lower serum globulins (p = 0.003), and lower CSF leukocytes (p < 0.001). Without ART, one in 13 PWH had persistently undetectable CSF HIV RNA, while persistent CSF/plasma discordance was extremely rare over years. Immune responses, inflammation, BBB permeability, and iron and lipid metabolism were all associated with HIV replication in CSF.

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.

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.

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.

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.

Reversal of CSF HIV-1 Escape during Treatment of HIV-Associated Cryptococcal Meningitis in Botswana

Cerebrospinal fluid (CSF) viral escape has been poorly described among people with HIV-associated cryptococcal meningitis. We determined the prevalence of CSF viral escape and HIV-1 viral load (VL) trajectories in individuals treated for HIV-associated cryptococcal meningitis. A retrospective longitudinal study was performed using paired CSF and plasma collected prior to and during the antifungal treatment of 83 participants recruited at the Botswana site of the phase-3 AMBITION-cm trial (2018−2021). HIV-1 RNA levels were quantified then CSF viral escape (CSF HIV-1 RNA ≥ 0.5 log10 higher than plasma) and HIV-1 VL trajectories were assessed. CSF viral escape occurred in 20/62 (32.3%; 95% confidence interval [CI]: 21.9−44.6%), 13/52 (25.0%; 95% CI: 15.2−38.2%) and 1/33 (3.0%; 95% CI: 0.16−15.3%) participants at days 1, 7 and 14 respectively. CSF viral escape was significantly lower on day 14 compared to days 1 and 7, p = 0.003 and p = 0.02, respectively. HIV-1 VL decreased significantly from day 1 to day 14 post antifungal therapy in the CSF but not in the plasma (β = −0.47; 95% CI: −0.69 to −0.25; p < 0.001). CSF viral escape is high among individuals presenting with HIV-associated cryptococcal meningitis; however, antifungal therapy may reverse this, highlighting the importance of rapid initiation of antifungal therapy in these patients.

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.

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

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