CROI 2025 Abstract eBook

Abstract eBook

Poster Abstracts

modulate antiviral immune responses, untargeted global metabolomics using mass spectrometry was performed on plasma. We also stimulated full PBMC and purified monocytes with a panel of sulfated and non-sulfated BAs to measure cytokine production in supernatant and intracellularly with flow cytometry, and we tested the activation of surface (TGR5) and nuclear BAs receptors (FXR and VDR) with sulfated and non-sulfated BAs with a luciferase assay. Results: From the earliest hospitalization time point, levels of non-sulfated BAs were higher in mild COVID-19 individuals while high levels of sulfated BAs were associated with increased viral load (VL), aberrant pro-inflammatory milieu and severe COVID-19, including mortality. We observed that full PBMC treated with non-sulfated BAs triggered significantly higher levels of IFN-a2a and immune regulators as TGF, compared to their sulfated version. Purified monocytes showed the same response in addition to higher levels of IL-10 and TNF-a. Notably, sulfated BAs didn’t activate any BAs receptors, which is relevant, since FXR is known to trigger type 1 IFN production. This was seen for primary and secondary BAs, suggesting a global role for sulfation, consistently with the findings at IMPACC. We made similar observations in flu infection where severe flu was characterized by heightened levels of Sulfated BAs. Conclusions: Our results confirm the importance of BAs and their homeostasis during a viral infection. Myeloid cells are the main population expressing BAs receptors. Therefore, the main producers of type 1 IFN and modulate the antiviral innate immune response. Since sulfated BAs do not interact with BAs receptors in a way that enhances the anti-viral response, as non-sulfated bile acids do, the imbalance between these metabolites could potentially impact on the clinical progression of COVID-19.

IFN-α2a and TGF-β. In myeloid cells, we demonstrate that unlike sulfated BAs, non-sulfated BAs induce type I interferon (IFN), pERK/pCREB and pSTAT1 in TGR5-positive populations. Single-cell RNA/DNA analysis identified monocytes as a critical population due to their upregulation in Gene Set Enrichment Analysis (GSEA) of IFN signaling, inflammation, and bile acid signaling, as well as TGR5 expression. GSEA revealed heightened IFN signaling, antigen-presentation pathways, and IRF motif enrichment in monocytes from mild COVID-19 cases. In contrast, severe COVID-19 cases exhibited more inflammatory pathways, including IL-6/STAT6 and apoptotic pathways, along with AP1 motif enrichment. Importantly, only TGR5 positive cells expressed IFN antiviral pathways. Conclusions: Our findings highlight the critical role of BA sulfation in modulating immune responses and its potential as a prognostic biomarker for COVID-19 disease severity. Moreover, this study underscores the impact of the complexity of BAs on modulation of the antiviral immune response. The figure, table, or graphic for this abstract has been removed. The Influence of Chronic HIV Inflammation on Post-COVID Immune Activation Skye Opsteen, Mildred Perez, Carson Norwood, Aoyjai Montgomery, Emily Levitan, Paul Goepfert, Nathan Erdmann University of Alabama at Birmingham, Birmingham, AL, USA Background: People with HIV (PWH) appear to be 2-4x more likely to develop long COVID after SARS-CoV-2 infection than people without HIV (PWOH). This is potentially linked to the heightened immune activation and inflammatory state typical of chronic HIV despite effective antiretroviral therapy. Here, we evaluated whether the shifts in monocyte and T cell populations typical of chronic HIV are exacerbated in long COVID, and how the immune features of long COVID in PWH compare to PWOH. Methods: We performed flow cytometric analyses on peripheral blood mononuclear cells from PWH with (n=9) and without (n=15) long COVID and groups of PWOH with (n=28) and without (n=36) long COVID. Participant clinical and demographic features were blinded prior to data collection, leading to a skewed racial and gender distribution. Samples were collected an average of 30 months after participants’ first reported COVID-19 infection. Cells were stained for surface markers of activation/exhaustion (with and without SARS CoV-2-specific antigen stimulation) and for monocyte subsets (CD14+ classical, CD14+CD16+ intermediate, CD14-CD16+ nonclassical). Electronic health record data including acute COVID-19 infection history, SARS-CoV-2 vaccination history, and long COVID symptom burden were collected. Results: PWH had increased expression of activation markers OX40 (p=0.034) and PDL1 (p=0.035) on CD4+ T cells as compared to PWOH who recovered from COVID-19. Regardless of long COVID status, PWH had increased CD14+CD16+ intermediate monocytes as compared to PWOH (p=0.048). When stimulated with a SARS-CoV-2 peptide pool containing membrane, nucleocapsid, and envelope proteins, the majority of PWH with long COVID had an antigen-specific CD4+ T cell response, whereas few responses were detected in PWOH with long COVID (p=0.016). When comparing post-COVID symptom burden, PWH with long COVID reported higher frequencies of shortness of breath (p=0.044), bladder incontinence (p=0.499), dry mouth (p=0.0475), excessive thirst (p=0.047), and problems with their teeth (p=0.031) as compared to PWOH with long COVID. Conclusions: Our findings demonstrate that PWH with long COVID exhibit increased CD4+ T cell activation and an increase in intermediate monocyte frequencies as compared to PWOH with long COVID. Our research explores potential differences in long COVID pathogenesis and provides evidence for potential diagnostic markers and therapeutic targets for patients with inflammatory phenotypes of long COVID and other post-viral syndromes.

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Poster Abstracts

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The Bile Acids Complexity Underlies an Antiviral Interferon Innate Signaling During COVID-19 Disease Diego A. Diaz-Dinamarca 1 , Slim Fourati 2 , Eileen F. Serrano 1 , Felipe Ten-Caten 1 , Valentino D'Onofrio 3 , Ali Muhammad 1 , Nadine Rouphael 1 , Grace A. McComsey 4 , Elias Haddad 5 , Jeffrey A. Tomalka 1 , Rafick P. Sekaly 1 , for the IMPACC Network 1 Emory University, Atlanta, GA, USA, 2 Northwestern University, Chicago, IL, USA, 3 Ghent University, Ghent, Belgium, 4 Case Western Reserve University, Cleveland, OH, USA, 5 Drexel University, Philadelphia, PA, USA Background: Bile acids (BAs), synthesized by hepatocytes (primary BAs) and modified by commensal bacteria (secondary BAs), are important regulators of immune cell function, particularly in innate immunity. While the role of BAs in influencing immune responses to various viral infections is established, the specific impact of nonsulfated BAs on immune cells remains underexplored. BAs can directly regulate the transcriptional responses of cells by binding to a range of BA receptors, including those expressed on immune cells such as TGR5. Methods: We utilized integrated omics and single-cell RNA/DNA analysis from the Immunophenotyping Assessment in a COVID-19 Cohort (IMPACC), a prospective longitudinal study with detailed clinical, virological, and immunological data, to investigate the impact of BAs on the progression of COVID-19. Additionally, we employed flow cytometry and multiplex cytokine detection to evaluate the activation of BAs in peripheral blood mononuclear cells (PBMCs) from healthy donors. Results: We found that serum levels of sulfated bile acids, as early as the day of hospitalization, correlated with disease trajectories leading to severe disease and death. In contrast, levels of nonsulfated bile acids were associated with mild disease, survival, and lower viral loads. PCA analysis of supernatants stimulated with sulfated and nonsulfated BAs reveals a dichotomy with nosulfated being associated with high levels of

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CROI 2025