CROI 2025 Abstract eBook

Abstract eBook

Poster Abstracts

Addition of recACBP to PBMCs before stimulation with anti CD3 or HIV peptides prevented CD4 and CD8 T-cell cytokine secretion as well as cell proliferation. Also, recACBP addition decreased expression of autophagy markers Beclin1, p62 and ULK1 in both CD4 and CD8 T-cells stimulated with anti-CD3. Addition of GABAArg2 peptides had no influence on ACBP inhibiting T-cell cytokine production and proliferation upon anti-CD3 or HIV peptide stimulation. Conclusions: Higher plasma ACBP levels in PLWH on ART were associated with inflammation, and markers of T-cell dysfunction. Extracellular ACBP directly inhibited autophagy and T-cell function. Our results indicate that another receptor than the GABAA receptor might be involved, compelling the assessment of ACBP inhibitory mechanism to develop new inhibitors aimed at improving anti-HIV T-cell responses in PLWH, towards an HIV cure. Gut Microbiome Dynamics and Immune Responses in People With HIV Receiving N-803 Ashma Chakrawarti 1 , Chris Basting 1 , Ross T. Cromarty 1 , Jodi Anderson 1 , Ty Schroeder 1 , Kevin Escandon 1 , Patrick Soon-Shiong 2 , Jeffrey Safrit 2 , Jeffrey Miller 1 , Joshua Rhein 1 , Timothy Schacker 1 , Nichole Klatt 1 1 University of Minnesota, Minneapolis, MN, USA, 2 ImmunityBio, San Diego, CA, USA Background: The gut microbiota plays a crucial role in host immune modulation. N-803, an IL-15 superagonist primarily developed for cancer immunotherapy, has shown potential to enhance immune responses in people with HIV (PWH). This pilot study investigated the relationship between gut microbiota and immune responses during a clinical trial of N-803 in PWH. Methods: N-803 was administered subcutaneously to 10 PWH at a dose of 6 mcg/kg on Days 0, 21, and 42. Stool samples were collected prior to day 0 (baseline), day 28, day 49-56 (postdrug) and day 137-141. Shotgun metagenomic sequencing was performed to analyze taxonomic composition and functional profiles of the gut microbiota bioinformatically. We also investigated associations between microbial diversity and immune markers, including NKG2A, viral (v)RNA levels, and CD8 T cell counts in lymph nodes (LNs), rectum, and ileum. Statistical analyses were conducted using R. Results: Two distinct enterotypes were identified among the participants, which significantly differed in both alpha and beta diversity. A significantly positive correlation was observed between Shannon diversity and NKG2A cell counts in the LNs after treatment while a negative trend was seen with vRNA levels in the LNs. We split the individuals into two groups: viral responders (VRs) who had decreased vRNA levels in LNs from baseline to post-drug infusion and viral non-responders (VNRs) who had increased vRNA levels in LNs from baseline to post-drug infusion. VNRs had a notably higher abundance of Faecalibacterium sp. CYL33 . Furthermore, microbial pathways that correlated positively with CD8 T cell counts often showed inverse correlations with vRNA levels, particularly in pathways related to lysine, colanic acid, and chorismate biosynthesis. Conclusions: This pilot study shows that gut microbiota composition remains relatively stable during N-803 therapy in PWH. However, microbial and metabolic differences are apparent in individuals who have immune responses to N-803 therapy compared to those who do not. These differences suggest specific microbial functions may influence immune activity and/or virus control. The trends observed in this study highlight the intricate relationships between microbiota diversity and immune markers in HIV infection. Further research with larger sample sizes is necessary to better understand the role of the gut microbiome in modulating immune responses during N-803 therapy and its implications for HIV immunotherapy. Heterogeneity of PD-1 Expression in PLHIV and Its Relationship With Host and Viral-Related Factors Adriana Navas 1 , Jéssica dos Santos 1 , Vasiliki Matzaraki 1 , Nadira Vadaq 1 , Maartje Jacobs-Cleophas 1 , Albert L. Groenendijk 2 , Wilhelm A. Vos 3 , Marc J. T. Blaauw 4 , Louise E. van Eekeren 1 , Mareva Delporte 5 , Mihai G. Netea 1 , Linos Vandekerckhove 5 , Leo Joosten 1 , Hans Koenen 1 , Andre van der Ven 1 , for the 2000HIV Human Functional Genomics Partnership Program 1 Radboud University Medical Center, Nijmegen, Netherlands, 2 Erasmus University Medical Center, Rotterdam, Netherlands, 3 OLVG, Amsterdam, Netherlands, 4 Elisabeth-TweeSteden Ziekenhuis, Tilburg, Netherlands, 5 HIV Cure Research Center, Ghent University, Ghent, Belgium Background: Anti-PD-1 immunotherapy (API) can potentially reverse T-cell exhaustion, reinvigorate HIV-specific T-cell responses, and reduce the HIV reservoir in people living with HIV (PLHIV). API responsiveness is not direct associated with PD-1 expression on T-cells, suggesting that receptor

heterogeneity might influence therapeutic outcomes. Therefore, we aimed to assess 1. whether PD-1 expression varies among T-cells subsets, 2. which host factors contributed to PD-1 heterogeneity, 3. correlate PD-1 expression with cell functionality. Methods: High-dimensional flowcytometric PD-1 measurements from viral suppressed PLHIV using ART of the 2000HIV cohort (NCT03994835) were analyzed, separated into discovery cohort (n=1147) and validation cohort (n=225). We assessed percentages and MFI of PD1 in 21 T-cell subsets (Tc). Participants were categorized into high, intermediate, and low consistent PD-1 expression groups when >75% of Tc had PD-1 values in one of the following tertiles of PD-1 distribution, T3, T2 and T1 respectively. We explored the relationship of PD-1 expression with clinical and HIV-related factors as well as ex-vivo PBMC cytokine production capacity after stimulation using Spearman rank correlation analysis. Results: Less than 40% of the participants had a consistent PD1 expression (both proportions and MFI) across Tc evaluated, regardless of the category. Lower percentage of exhausted CD4Tc was significantly correlated with female sex, high CD4 nadir, COVID-19 vaccination, and spontaneous HIV control (HIC) phenotype, while higher percentage of exhausted cells was significantly correlated with older age, immunological non-responders (INR) phenotype, CMV titers and larger HIV reservoir size (Fig.A). Exhausted CD8+ naïve Tc were linked to older age, CMV titers and intact HIV reservoir. Higher PD-1 expression on CD4 Tc was negatively correlated with IFN-γ, IL-17, IL-22, and IL-10 secretion upon microbial stimulation (Fig.B, FDR < 0.05, discovery; p < 0.05, validation). Conclusions: PLHIV exhibited a heterogeneous PD-1 expression across all Tc subsets, which negatively impacted cytokines production, indicating immune exhaustion. Notably, our study suggests that PLHIV with higher CMV reactivity, higher HIV reservoir size, males and immunological non-responders show highest PD-1 expression and may react differently to API than other groups. A careful consideration of clinical host factors and functional immune response is crucial for an effective API in PLHIV.

461

Poster Abstracts

The figure, table, or graphic for this abstract has been removed.

462

CROI 2025 114