CROI 2025 Abstract eBook

Abstract eBook

Poster Abstracts

341

WITHDRAWN

Lastly, HIV replication in CD101 CRISPR-ablated CD4 + T cells was comparable to mock controls. Conclusions: CD101 downregulation by HIV occurs primarily in monocytes and Tregs, is influenced by cell-to-cell interactions and CD101 genotype, and inversely correlates with the cells’ proinflammatory response. Our results suggest that CD101 may affect HIV infection risk indirectly, via effects on inflammation, rather than directly on HIV replication. Candidate CD101 alleles may accentuate this effect. CD40L/IL-4 Stimulated B Cells as Efficient Mediators of HIV-1 Binding and Trans Infection Abigail Gerberick, Allison DePuyt, Peter Shoucair, Robbie Mailliard, Nicolas Sluis Cremer, Charles Rinaldo University of Pittsburgh, Pittsburgh, PA, USA Background: Cell-to-cell HIV-1 transmission is a potent mechanism of HIV-1 pathogenesis. B and CD4 + T cells frequently interact in secondary lymphoid organs (SLO), thus potentially promoting B cell mediated HIV-1 trans infection. In SLO, B cells are stimulated through both stromal (BAFF) and CD4 + T cell (IL-4, IFN-g, CD40L) signals, however the impact of these signals on the efficiency of HIV-1 binding and trans infection remains unknown. Methods: Human B and CD4 + T cells were isolated from blood of people without HIV. B cells were left unstimulated or stimulated with CD40L/IL-4, CD40L/IFN-g, BAFF/IL-4, or BAFF/IFN-g. For trans infection, B cells were incubated with HIV-1 BaL (MOI 10 -3 ) prior to culture with CD4 + T cells. HIV-1 infection was measured by HIV-1 p24 ELISA on co-culture supernatants. For HIV-1 binding, B cells were incubated with HIV-1 Gag-iGFP-JRFL (MOI 10 -1 ) and analyzed by flow cytometry. ScRNAseq was performed via the BD Rhapsody and Illumina platforms and data were analyzed using the Seurat package in R. Results: CD40L/IL-4 stimulated B cells efficiently bound HIV-1 (p<0.0001) and mediated HIV-1 trans infection of CD4 + T cells (p<0.0001) as compared to the other stimulation conditions. Exposure to CD40L was the main driver of HIV-1 binding by B cells, although IL-4 also contributed to some extent (p=0.01). Single cell transcriptomics of B cells stimulated for 10h provided unique insights into the gene expression profiles associated with these conditions. CD40L/IL-4 stimulated B cells exhibited significantly higher expression of activation markers CD80/CD86 as well as C-type lectin CD205 (p<0.01), which flow cytometry confirmed (p<0.0001). Antibody-mediated blocking of CD205 on CD40L/IL-4 stimulated B cells reduced HIV-1 binding. Biological processes analysis further highlighted that CD40L/IL-4 upregulates genes involved in actin pathways in B cells, including actin filament organization (p<0.01). When actin polymerization was blocked in CD40L/IL-4 stimulated B cells, HIV-1 binding was also reduced. Conclusions: B:T cell interactions in SLO likely play a key role in HIV-1 pathogenesis by facilitating HIV-1 trans infection. This study identifies the signals (CD40L/IL-4) and gene/receptor expression (CD205/actin) that enable B cells to bind HIV-1 and transfer virus to CD4 + T cells. This information could lead to the development of treatments to reduce persistent HIV-1 infection and maintenance of the viral reservoir. Feminizing Hormone Therapy and the Rectal Mucosal Immune Environment Stacey Smith 1 , Mengyu He 1 , Phillip M. Murray 2 , Cassie G. Ackerley 2 , Suparat Khemnark 4 , Vin Tangpricha 1 , Yijuan Hu 1 , Colleen Kelley 2 1 Emory University, Atlanta, GA, USA, 2 Emory Vaccine Center, Atlanta, GA, USA, 4 Bamrasnaradura Infectious Diseases Institute, Bangkok, Thailand Background: Transgender women (TGW) have historically been grouped with cisgender men who have sex with men (CGMSM) in HIV prevention research. However, the effects of feminizing hormone therapy (FHT) on the rectal mucosal immune environment, a primary site of HIV exposure, remain insufficiently understood. Methods: In Bangkok, Thailand, 100 TGW taking FHT for >6 months and 50 MSM without HIV were enrolled into a cross-sectional study with blood and rectal mucosal sampling. An additional 21 HIV-negative TGW were enrolled and underwent blood and rectal mucosal sampling before and 3-12 months after FHT initiation. Flow cytometry was performed on PBMC and rectal biopsies to quantify 30 and 31 immune cell subsets respectively. Three biopsies were challenged with HIV BaL ex vivo , and p24 production was quantified (Day 3-14). Cellular and p24 outcomes were compared between the groups with linear decomposition modeling controlling for multiple comparisons. Bulk

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Poster Abstracts

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Untangling the Impact of CD101 on HIV-1 Transmission Phuong Vo 1 , German Gornalusse 2 , Shahrokh Paktinat 1 , Sean M. Hughes 1 , Matthew H. Ikuma 1 , Claire N. Levy 1 , Hannah L. Itell 3 , Adino T. Tsegaye 1 , Lucia N. Vojtech 1 , Julia Lemas 1 , Sachi Saxena 1 , Jairam Lingappa 1 , Florian Hladik 1 , for the International Clinical Research Center 1 University of Washington, Seattle, WA, USA, 2 University of California San Francisco, San Francisco, CA, USA, 3 Fred Hutchinson Cancer Center, Seattle, WA, USA Background: Variants in the extracellular Ig-like domain of the CD101 gene are associated with increased HIV acquisition risk, but the biological mechanism is unknown. CD101 inhibits T cell activation and is mostly expressed on antigen-presenting cells (APCs) and T cells. Here, we tested the hypothesis that CD101 regulates inflammatory homeostasis in immune cells. We also explored the impact of CD101 genetic variation on this regulation and the risk of HIV-1 infection. Methods: We evaluated the effect of Toll-like receptor agonists (TLR1 to TLR9) on CD101 mRNA levels in peripheral blood mononuclear cells (PBMC) and purified monocytes. We used flow cytometry to measure CD101 expression on PBMC subsets. We compared individuals with (n=14) and without (n=5) candidate CD101 variants to assess the effect of CD101 variation on PBMC responses to TLR8 stimulation. We also used CRISPR to knock out CD101 in primary CD4+ T cells to test its impact on HIV infectivity. Results: TLR2, 4, 5, 7 and 8 stimulation reduced CD101 mRNA expression in PBMC and monocytes. The strongest effect was from HIV ssRNA (a TLR8 agonist) (-77.0% in PBMC, -90.9% in monocytes; n=4). Challenge with infectious HIV also reduced CD101 mRNA (-49.1%; n=4). CD25 + CD127 low Tregs and HLA-DR + APCs were most sensitive to CD101 downregulation upon TLR8 stimulation (-41.4% and -63.0%, respectively; n=4). However, CD101 downregulation was much weaker if Tregs were purified before stimulation (-8.1%; n=5). For PBMC genotyped for CD101 , following TLR8 stimulation, we observed significant mRNA increases for IFNβ1 (mean 11.1-fold), IL-6 (644.4-fold), and IFIT1 (83.8 fold), and a significant decrease for CD101 (74.1% +/- 22.5%; n=17), in 17 out of 19 donors. Cytokine increases correlated strongly with CD101 reduction (e.g. for IL-6/CD101 Spearman’s r=0.67, p=0.0017; n=19). In an exploratory analysis, CD101 mRNA reductions upon TLR8 stimulation were greater in cells from people with a CD101 variant than reference (β=-32 vs. β=-19, interaction p=0.006).

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CROI 2025