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Despite the success in the management of HIV with antiretroviral therapy (ART), people with HIV (PWH) have a heightened state of immune activation and inflammation, and an estimated 10%-40% demonstrate poor CD4 T-cell reconstitution, thereby increasing their mortality and morbidity risk burden. Soluble immunoregulatory proteins that function in lymphocyte activation or inhibition are elevated in PWH and associate with T-cell dysfunction, HIV persistence, and are predictive of comorbid outcomes. Here, we measured a panel of 35 circulating immunoregulatory proteins in 116 PWH with variations in CD4 T-cell counts (poor CD4 trajectory: <200 cells/μl, n = 34 or immune competent: CD4 >500 cells/μl, n = 82) by Luminex. Participants were enrolled in the AIDS Clinical Trials Group Longitudinal Linked Randomized Trials cohort, had initiated ART on enrollment, and had been on suppressive ART for 1 year. Using non-parametric analysis, we found that the levels of CD276, ICOSL, BAFF, OX40, galectin-1, and galectin-9 were significantly higher in PWH with poor CD4 trajectories compared to individuals with immune-competent CD4 T-cell count. Notably, in logistic models, ICOSL and OX40 remained significant after adjusting for age and baseline plasma HIV RNA. Furthermore, Extreme Gradient Boosting machine learning models comprising co-stimulatory and inhibitory checkpoint proteins yielded high accuracy in classification of individuals with poor CD4 trajectories. In summary, we identified a novel signature of circulating immunoregulatory proteins indicative of poor CD4 trajectories that may serve as potential targets to monitor and manage immune perturbations more accurately in PWH during suppressive ART.

Importance: It is essential to track immune perturbations related to insufficient CD4 T-cell recovery in PWH on suppressive ART as those with incomplete reconstitution are at a greater risk of non-AIDS-related morbidity and mortality. Several inflammatory soluble mediators have associated with poor immune reconstitution and adverse morbid outcomes in PWH, yet their implementation into routine clinical care to guide management remains inconsistent. Circulating immune checkpoint proteins have been linked to dysregulated immune pathways during suppressive ART and may serve as improved surrogate markers of clinical relevance. Here we investigate soluble lymphocyte-associated immunoregulatory proteins in virally suppressed PWH with no reported co-morbid outcomes and varying CD4 T-cell counts, to reveal underlying pathways that remain perturbed despite ART. This novel signature of immunoregulatory markers pertaining to poor CD4 T-cell trajectories uncover previously overlooked immune checkpoints as important targets for clinical monitoring of PWH in the setting of durable viral suppression by ART.

Objective: Adolescents with perinatally acquired HIV (AWH) are at an increased risk of poor cognitive development yet the underlying mechanisms remain unclear. Circulating galectin-9 (Gal-9) has been associated with increased inflammation and multimorbidity in adults with HIV despite antiretroviral therapy (ART); however, the relationship between Gal-9 in AWH and cognition remain unexplored.

Design: A cross-sectional study of two independent age-matched cohorts from India [AWH on ART (n = 15), ART-naive (n = 15), and adolescents without HIV (AWOH; n = 10)] and Myanmar [AWH on ART (n = 54) and AWOH (n = 22)] were studied. Adolescents from Myanmar underwent standardized cognitive tests.

Methods: Plasma Gal-9 and soluble mediators were measured by immunoassays and cellular immune markers by flow cytometry. We used Mann – Whitney U tests to determine group-wise differences, Spearman’s correlation for associations and machine learning to identify a classifier of cognitive status (impaired vs. unimpaired) built from clinical (age, sex, HIV status) and immunological markers.

Results: Gal-9 levels were elevated in ART-treated AWH compared with AWOH in both cohorts (all P < 0.05). Higher Gal-9 in AWH correlated with increased levels of inflammatory mediators (sCD14, TNFa, MCP-1, IP-10, IL-10) and activated CD8+ T cells (all P < 0.05). Irrespective of HIV status, higher Gal-9 levels correlated with lower cognitive test scores in multiple domains [verbal learning, visuospatial learning, memory, motor skills (all P < 0.05)]. ML classification identified Gal-9, CTLA-4, HVEM, and TIM-3 as significant predictors of cognitive deficits in adolescents [mean area under the curve (AUC) = 0.837].

Conclusion: Our results highlight a potential role of Gal-9 as a biomarker of inflammation and cognitive health among adolescents with perinatally acquired HIV. 

Multiple cellular HIV reservoirs in diverse anatomical sites can undergo clonal expansion and persist for years despite suppressive antiretroviral therapy, posing a major barrier toward an HIV cure. Commonly adopted assays to assess HIV reservoir size mainly consist of PCR-based measures of cell-associated total proviral DNA, intact proviruses and transcriptionally competent provirus (viral RNA), flow cytometry and microscopy-based methods to measure translationally competent provirus (viral protein), and quantitative viral outgrowth assay, the gold standard to measure replication-competent provirus; yet no assay alone can provide a comprehensive view of the total HIV reservoir or its dynamics. Furthermore, the detection of extant provirus by these measures does not preclude defects affecting replication competence. An accurate measure of the latent reservoir is essential for evaluating the efficacy of HIV cure strategies. Recent approaches have been developed, which generate proviral sequence data to create a more detailed profile of the latent reservoir. These sequencing approaches are valuable tools to understand the complex multicellular processes in a diverse range of tissues and cell types and have provided insights into the mechanisms of HIV establishment and persistence. These advancements over previous sequencing methods have allowed multiplexing and new assays have emerged, which can document transcriptional activity, chromosome accessibility, and in-depth cellular phenotypes harboring latent HIV, enabling the characterization of rare infected cells across restrictive sites such as the brain. In this manuscript, we provide a review of HIV sequencing-based assays adopted to address challenges in quantifying and characterizing the latent HIV reservoir. 

Galectin-9 (Gal-9) is a β-galactoside binding lectin known for its immunomodulatory role in various microbial infections. Gal-9 is expressed in all organ systems and localized in the nucleus, cell surface, cytoplasm and the extracellular matrix. It mediates host-pathogen interactions and regulates cell signalling via binding to its receptors. Gal-9 is involved in many physiological functions such as cell growth, differentiation, adhesion, communication and death. However, recent studies have emphasized on the elevated levels of Gal-9 in autoimmune disorders, viral infections, parasitic invasion, cancer, acute liver failure, atopic dermatitis, chronic kidney disease, type-2 diabetes, coronary artery disease, atherosclerosis and benign infertility-related gynecological disorders. In this paper we have reviewed the potential of Gal-9 as a reliable, sensitive and non-invasive biomarker of disease severity. Tracking changes in Gal-9 levels and its implementation as a biomarker in clinical practice will be an important tool to monitor disease activity and facilitate personalized treatment decisions.