CROI 2025 Abstract eBook

Abstract eBook

Poster Abstracts

post-treatment controllers (PTCs), experience sustained virologic control following ATI, whilst non-controllers (NCs) require re-initiation of antiretroviral therapy (ART) to suppress rebounding viremia. We investigated the immune response in two PTCs (ID107 and 142) and two NCs (ID104 and 112) to uncover immunological mechanisms of PTC. Methods: We characterized the distribution of CD8+ T subsets and HIV-1 specific memory T cells using a spectral flow cytometry-based intracellular cytokine staining assay on PBMCs from HIV-1 study participants collected pre-ATI and at either viral rebound (NCs) or at several time points during long term ATI (PTCs). PBMCs were stimulated with HIV-1 peptide mix (Pol, Gag, Nef, or Env), negative control (DMSO), and secretion inhibitors. The spectral flow panel consisted of markers of differentiation (CD45RA, CCR7, CD27, CD95), cytokines/ degranulation (IFNγ, TNF, IL2, IL4/13, CD107a), proliferation, transcription, effector proteins, and immune checkpoints. Results: In PTCs, the CD8+ transitional memory population was expanded compared to NCs (25-50 % and 10-20 %, respectively). Conversely, the naïve, effector memory, and terminally differentiated populations were contracted in PTCs. Both PTCs had high frequencies of HIV-1-specific polyfunctional CD8+ and CD4+ memory T cells. ID107 exhibited a Gag-specific CD8+ T cell response, which declined during 6-year ATI. ID142 exhibited a Pol- and Nef-specific response which remained stable during 2.5-year ATI. Both PTCs exhibited a broader CD4+ T cell response, mainly towards Gag, Pol and Nef, increasing from pre-ATI to follow-up during ATI. The CD8+ T cell responses were dominated by IFN+TNF+ responses, while the CD4+ T cell responses were predominantly IFN+TNF+IL2+ and IL4/13+ in ID142. NCs had fewer primarily monofunctional, HIV-1-specific CD8+ and CD4+ memory T cells (Figure 1). The response profile of the PTCs correlated with results from IFNγ ELISpot assay. Conclusions: PTC was associated with higher proportions of CD8+ transitional memory populations and lower naïve, effector memory and terminally differentiated populations. Further, PTCs showed a CD4+ and CD8+ memory phenotype with better capacity for viral control by their higher frequency of HIV-1-specific polyfunctional CD8+ and CD4+ T cells. The figure, table, or graphic for this abstract has been removed. Impact of Gender-Affirming Hormone Therapy on T-Cell Phenotypes in Transgender Women With HIV Elizabeth Hastie 1 , Alan Wells 1 , Antoine Chaillon 1 , Stephen A. Rawlings 2 , Brendon Woodworth 1 , Vanessa Gomez-Moreno 1 , Megha S. Srivatsa 1 , Jill Blumenthal 1 , Marvin Hanashiro 1 , Jordan E. Lake 3 , Sarah LaMere 1 , Timothy Wilkin 1 , Jonathan Karn 4 , Eileen Scully 5 1 University of California San Diego, La Jolla, CA, USA, 2 Maine Medical Center, Portland, ME, USA, 3 University of Texas Health Science Center at Houston, Houston, TX, USA, 4 Case Western Reserve University, Cleveland, OH, USA, 5 The Johns Hopkins University School of Medicine, Baltimore, MD, USA Background: Understanding the impact of gender-affirming hormone therapy (GAHT) on immune regulation in transgender women living with HIV (TWH) is essential for improving HIV care and developing cure strategies. Methods: TWH on suppressive ART initiating estradiol-based GAHT were recruited from HIV clinics in San Diego, CA, and Houston, TX. Blood samples were collected before and longitudinally 2, 4, 6, 9, 12, and 18-months post GAHT initiation. Historical samples from cisgender men with HIV were matched by age, CD4 + T cell count, duration of HIV and time on ART. Flow cytometry assessed markers of T cell activation (HLA-DR + CD38 + ), cytotoxicity (CD107a + ), proliferation (Ki67 + ), and exhaustion (TIGIT + PD-1 + ) in CD4 + and CD8 + memory subsets. A partial least squares-discriminant analysis (PLS-DA) distinguished between transgender and cisgender groups using all flow cytometry features. Post-hoc analysis with generalized mixed-effects models examined markers with variable importance for projection (VIP) ≥ 1, adjusting p-values for multiple comparisons using the false discovery rate method. Results: A total of 22 TWH were enrolled. Nine were lost of follow-up including one suicide, one homicide, and two imprisonments. 75 samples from TWH and 53 samples from 13 historical cisgender controls were analyzed. The PLS-DA model accurately predicted gender groups with an error rate of 17.2% ( Figure ). Four T cell phenotypes were significantly different between groups in post-hoc analysis: TWH had more cycling (Ki67+) effector memory and terminally differentiated CD8 + T cells (p=0.015, incidence rate ratio (IRR)=2.31 and p=0.021, IRR=2.16, respectively) but fewer exhausted (expressing TIGIT + ) effector CD8 + T cells (p=0.027, IRR=0.45). TWH also had a significantly higher

proportion of naïve CD8 + T cells (p=0.027, IRR=2.03). There were no significant differences in T cell phenotypes over time. Conclusions: Immunophenotypic analysis of TWH compared to historical cisgender male controls revealed differences in the CD8 + T cell compartment, including increased cell cycling and lower TIGIT expression. Prior studies have shown disparities in activation and exhaustion markers (e.g., PD-1) between cisgender men and women living with HIV. Our findings indicate a unique immune profile for TGW, potentially influenced by chronic immune activation, pre-existing variations in TWH, or hormonal factors. Further investigation will determine underlying mechanisms and their relationship with virologic outcomes.

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Differential Restoration of HIV-Specific CD8+ T Cells by Amino Acid and Lipid Metabolism Modulation Ilya Tsukalov 1 , Marta Calvet-Mirabent 2 , Ildefonso Sánchez-Cerrillo 1 , María Agudo-Lera 3 , Lucio Jesús Garcia Fraile Fraile 1 , Paula Vera-Tome 3 , Alba Roca Portoles 4 , Arantzazu Alfranca 1 , Ana Dopazo 5 , Aranzazu Rosado-Diez 5 , Ana Quintas 5 , Ignacio de los Santos 1 , Francisco Sánchez-Madrid 1 , Eduardo Balsa 4 , Enrique Martin Gayo 3 1 Hospital Universitario de La Princesa, Madrid, Spain, 2 Gladstone Institute, San Francisco, CA, USA, 3 Universidad Autónoma de Madrid, Madrid, Spain, 4 Centro de Biología Molecular Severo Ochoa, Madrid, Spain, 5 Centro Nacional de Investigaciones Cardiovasculares, Madrid, Spain Background: Priming of CD8+T cells with dendritic cells (DC) is a promising approach to reduce viral reservoirs in people with HIV (PWH). HIV-specific CD8+T responses in PWH are affected by PD-1, TIGIT and TIM3 expression in these cells. Here, we studied transcriptional, metabolic and functional characteristics of memory CD8+T cells differentially expressing these checkpoint receptors and identified new modulators potentially improving HIV-1 Gag-specific responses in PWH. Methods: CD8+T cells were co-cultured with DC activated with STING and TLR3 agonists and PD-1-TIGIT-TIM3- (TN), PD-1+TIGIT+TIM3- (PD-1/TIGITDP) and PD 1-TIGIT-TIM3+ (TIM3SP) memory CD8+T cells were sorted for RNA-seq analysis (n=4). Relevant transcriptional metabolic and functional pathways were identified by IPA. Selected differentially expressed genes (DEG) were validated by FACS (n=13). Mitochondrial mass and Reactive oxygen specie (ROS) content was assessed using MitroTracker and MitoSOX probes, respectively. Dependence of OXPHOS on lipid metabolism was tested in CD8+T cell subsets by SeaHorse. Effect of lipid (LTC4) and aminoacid (Ornithine) metabolites in the polarization of HIV-1-specific CD8+T cells (n=9) was evaluated by analysis of IFNg, TNFa, IL-13, CD107a and Granzyme B and by elimination of autologous p24+CD4+T cells (n=8). Results: 1671 DEG identified in TIM3SP cells were associated with upregulation of modulators of OXPHOS, TCA cycle, and amino acid/lipid metabolism. In contrast, 866 DEG from PD-1/TIGITDP lymphocytes associated with immune function and mitochondrial dysfunction. PD-1/TIGITDP CD8+T cells exhibited higher (p=0.002) ROS accumulation than TIM3SP from PWH. In addition, TIM3SP CD8+T cells from PWH contained higher Arginase2+ (p=0.0002) and MGST2+ (p=0.0156) cells compared to TN cells. Consistently, maximal mitochondrial-dependent respiration in TIM3SP CD8+T cells was dependent on fatty acid b-oxidation (p=0.0156). Notably, an increase of Gag-specific IFNg+CD107a+CD8+T cells was observed after Ornithine (p=0.0034) and LCT4 (p= 0.0371) modulation. TNFa expression was also induced in the presence of Ornithine (p=0.0049). Finally, modulation of CD8+T cells with DC, TIGIT/PD1

Poster Abstracts

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CROI 2025