CROI 2024 Abstract eBook

Abstract eBook

Poster Abstracts

Results: HIV-specific CD8+ T cell reactivity post-TI as measured by ELISpot was significantly lower in PTCs compared to TCs (P<0.01), with no significant differences observed between TCs and NCs. Of note, median plasma viral loads at time of analysis were 50, 638, and 36200 copies/mL in the PTCs, TCs, and NCs respectively. In contrast, both PTCs and TCs had significantly stronger proliferative responses to HIV epitopes than NCs (P<0.01 and P<0.05, respectively). Additionally, we calculated the capacity for antigen-specific CD8+ T cells to expand after antigen exposure by normalizing the magnitude of proliferation to direct ex vivo ELISpot magnitude and observed an even substantially higher proliferative capacity in both PTCs and TCs compared to NCs (P<0.001 and P<0.05, respectively). Conclusion: Compared to NCs, PTCs exhibited a distinct HIV-specific CD8+ T cell profile, with less direct ex vivo reactivity but greater proliferative capacity following antigen exposure. These findings warrant further investigation into the mechanisms by which highly expandible antigen-specific CD8+ T cell populations are formed and maintained, and lend further support to therapeutic vaccine strategies aimed at inducing T cell responses that retain high proliferative capacity.

Methods: We previously reported a higher-than-expected rate of post intervention control after a single-arm combination clinical trial (NCT04357821) in which people with treated HIV received a DNA/MVA vaccine regimen, followed by two bNAbs (10-1074, VRC07-523LS) plus a TLR-9 agonist (lefitolimod), then two bNAbs at the time of ATI. Seven of 10 participants achieved a low viral load (VL) set point ~1000 copies/mL while three had typical rebound (median set point 48,043 cpm). Before rebound and at an early timepoint (within 1 month) after rebound (median VL 775 cpm; n=8), we performed intracellular cytokine staining (by flow cytometry with overlapping peptide pools) and CyTOF on PBMCs. In a second study (NCT04359186), we performed single cell transcriptional analysis (10X 5' scRNA/TCRseq) of lymph node (LN) mononuclear cells before an ATI and at or near the time of rebound in 5 participants, two of whom had controlled HIV pre-ART and then re-controlled post-ATI. Results: In the trial, early post-rebound, the frequency of IFNg+ HIV-specific CD8+ T cells (sum: Gag+Pol+Nef+Env) increased in those who exhibited control (median fold-change [FC] vs pre-rebound: 1.8x) but not in those who failed to control (FC 0.9x). Similarly, the frequency of proliferating (Ki67+) non naïve CD8+ T cells increased robustly in controllers (FC 2.8x; 2.7 to 8.8%) but not in non-controllers (FC 1.2x; 2.8 to 3.3%). Higher %Ki67+ non-naïve CD8+ T cells early post-rebound was associated with lower VL set point (r=-0.81, p=0.02). Similarly, post-ATI in the second study, the fraction of proliferating CD8+ T cells (expressing MKI67) in the LN was higher in controllers vs non-controllers (3.6% vs 0.8%). Conclusion: To our knowledge, these studies are the first to demonstrate a relationship between the early in vivo CD8+ T cell proliferative response to viral reactivation and HIV control post-ART. The results support continued focus on developing HIV cure strategies that enhance HIV-specific CD8+ T cell proliferative capacity.

Poster Abstracts

448

Cannabis-Induced DNA Methylation Changes Mediate Immune Response in PLHIV Xun Jiang 1 , Elise M. Meeder 2 , Manoj K. Gupta 1 , Zhenhua Zhang 1 , Yang Li 1 , Mihai Netea 2 , Andre J. van der Ven 2 , Cheng-Jian Xu 1 1 Medizinische Hochschule Hannover, Hannover, Germany, 2 Radboud University Medical Center, Nijmegen, Netherlands Background: Cannabis use is prevalent among people living with HIV (PLHIV). Cannabis is mostly smoked leading to inhalation of the psychoactive tetrahydrocannabinol as well as reactive particles, toxins, and oxidants that may induce epigenetic changes and affect immune responses. We therefore analyzed the effect of cannabis on DNA methylation and immune function in PLHIV. Methods: Participants were recruited from the 2000HIV study (NTC03994835), a Dutch multi-center study amongst virally suppressed PLHIV, separated into a discovery cohort (n=1512, 280 cannabis users) and a validation cohort (n=317, 47 cannabis users). Cannabis use and tobacco smoking were recorded through a self- reported questionnaire. Genome-wide DNA methylation data was obtained using the Illumina Infinium MethylationEPIC array. Plasma proteins were assessed by targeted proteomics (Olink Explore). PBMC ex vivo cytokine production capacity was measured upon bacterial, fungal, and viral stimulation. The differential DNA Methylation Sites (DMSs) were identified by an epigenome-wide association study, followed by integration with the proteomics, and cytokine secretion data from the same individuals. Results: In the discovery cohort, 3741 cannabis-associated DMSs were identified, with 293 DMSs being replicated in the validation cohort. The most significant DMS is cg01940273 (p=1.3e-50) also strongly associated with tobacco smoking in 2000HIV and other studies. After accounting for tobacco smoking effects, 98% DMSs showed reduced significance but the methylation trend remained consistent and 81% DMSs were demethylated. Validated DMSs associated genes were enriched in nervous system development and leukocyte differentiation. The DMS-associated plasma proteins suggested that DMSs are associated with leukocyte differentiation and cytokine expression, such as IL6 upregulation and CXCL10 downregulation (Figure1). The causal inference test suggested that cannabis-induced DMSs may modulate immune response in PLHIV, such as increased IL22 and decreased INF-y production after PBMC stimulation.

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HIV Post-Treatment Controllers Show Enhanced CD8+ T-Cell Proliferative Capacity After ART Cessation Charles R Crain 1 , Anusha Nathan 1 , Behzad Etemad 2 , Prerana Shrestha 2 , Rachel L. Rutishauser 3 , Steven G. Deeks 3 , Jonathan Z. Li 2 , Gaurav D. Gaiha 1 1 Ragon Institute of MGH, MIT and Harvard, Cambridge, MA, USA, 2 Brigham and Women's Hospital, Boston, MA, USA, 3 University of California San Francisco, San Francisco, CA, USA Background: HIV post-treatment controllers (PTCs) are individuals who control viremia to low or undetectable levels following ART discontinuation. While functional CD8+ T cell responses have been shown to be a defining feature of spontaneous ("elite") control of HIV, characterization of features of CD8+ T cell responses in PTCs has been limited. Here, we aimed to characterize the frequency, functionality, and specificity of CD8+ T cells in PTCs following ART cessation. Methods: We evaluated HIV-specific CD8+ T cell responses of 7 PTCs alongside a group of 8 spontaneous controllers who had received and later discontinued ART (treated controllers, TC) and 11 non-controllers (NC) during the post treatment interruption (TI) period. Both PTCs and TCs were defined as having plasma viral loads <10,000 copies/mL for at least 52 weeks post-TI; individuals meeting these criteria were defined as TC if their viral load immediately preceding ART initiation was <10,000 copies/mL, and PTC if otherwise. Ex-vivo CD8+ T cell reactivity was evaluated by IFN-γ ELISpot and functional proliferative capacity through a six-day CFSE-based proliferation assay with individual optimal clade B epitopes matched to each participant's HLA haplotype.

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