CROI 2018 Abstract eBook

Abstract eBook

Poster Abstracts

Conclusion: These results highlight a potential role for Nef in modulating viral reactivation from latency in response to LRAs. Additional studies to assess the impact of natural nef sequence variation on this activity are necessary to determine the clinical relevance of this observation.

384 ALTERED PD-1/PD-L1 INTERACTIONS IN GERMINAL CENTERS OF TREATED HIV-INFECTED SUBJECTS Riddhima Banga , Caterina Rebecchini, Francesco Procopio, Stephanie D. Georget, Fabio Candotti, Matthias Cavassini, Jean-Marc Corpataux, Laurence de Leval, Giuseppe Pantaleo, Matthieu Perreau Lausanne University Hospital, Lausanne, Switzerland Background: One of the major obstacles to HIV cure resides in the capacity of HIV to establish a transcriptionally silent reservoir, which is not targeted by the immune system or by ART. However, under certain circumstances, HIV transcription might be reactivated. In this context, we recently demonstrated that the levels of HIV transcription in PD-1+/Tfh cells were significantly higher as compared to any other blood and lymph node (LN) memory CD4 T-cell populations. On the basis of this observation, we hypothesized that increased HIV transcription in Tfh cells may be facilitated by the reduction in the inhibitory signals delivered through PD-1/PD-L1 interaction in the germinal centers (GCs). Methods: To test this hypothesis, we assessed 1) the expression of PD-1 and PD-L1 by mass cytometry and immunohistochemistry (IHC) and 2) the impact of PD-1/PD-L1 interaction on HIV production in blood and LN memory CD4 T cells from viremic and aviremic, ART-treated HIV-infected subjects. Results: We show that PD-1 was highly expressed in blood and LN memory CD4 T-cell populations and particularly in Tfh cells. In contrast, PD-L1 expression was predominant in extra-follicular areas and restricted to macrophages and dendritic cells ( P <0.05). Interestingly, IHC revealed that the PD-1/PD-L1 ratio was significantly higher in GCs as compared to extra-follicular areas of aviremic, ART-treated HIV-1 infected subjects ( P <0.05). In addition, PD-1/PD-L1 ratio in GCs was about 20-fold higher in ART-treated than viremic, HIV-infected subjects ( P <0.05), suggesting that PD-1/PD-L1 interactions might be altered in GCs of ART-treated HIV-infected subjects. We then showed that TCR-mediated HIV production from latently infected memory CD4 T cells was significantly inhibited in presence of PD-L1 recombinant protein ( P <0.05), indicating that PD-1/PD-L interactions substantially reduced TCR-induced HIV production. Finally, we demonstrated that the anti-PD-1 mAb, pembrolizumab efficiently reactivated HIV replication from latently infected blood memory CD4 T cells ( P <0.05). Conclusion: This study suggests that an imbalance in the PD-1/PDL-1 signaling may contribute to the persistence of HIV in memory CD4 T cells and to the presence of active HIV transcription in LN Tfh cells. Taken together, these data provide the rationale for the development of intervention strategies targeting PD-1 and/or PD-L1 to reactivate HIV replication. 385 CD32 EXPRESSION IS ASSOCIATED TO T CELL ACTIVATION AND UPREGULATED BY HIV Roger Badia , Edurne García Vidal, Maria Pujantell, Bonaventura Clotet, Miguel Angel Martinez, Ester Ballana, Eva Riveira-Muñoz, Jose A. Este IrsiCaixa Institute for AIDS Research, Badalona, Spain Background: HIV infection establishes a subset of latently infected CD4+ T cells thought not to produce viral proteins and remain indistinguishable from uninfected cells. However, the overexpression of the gene encoding for the transmembrane protein FCGR2A (CD32a+) has been proposed as a potential marker of HIV+ latently infected cells. The study of molecular signatures that allow the identification of resting, latently infected cells would facilitate the development of new therapeutic approaches. Methods: Cell surface markers, including CD32 and activation markers HLA-DR and CD69, were measured in PBMC and CD4+ T lymphocytes from healthy donors and HIV+ individuals by flow cytometry and mRNA by qPCR. Effect of

383 HIGHER RECTAL P24 LEVELS CORRELATE WITH POOR CD4 RECOVERY IN TREATED HIV INFECTION Bonnie J. Howell 1 , Guoxin Wu 1 , Shih Lin Goh 1 , Paul Zuck 1 , Montha Pao 2 , Monika Deswal 2 , Rebecca Hoh 2 , Jeffrey N. Martin 2 , Steven G. Deeks 2 , Ma Somsouk 2 , Daria Hazuda 1 , Peter W. Hunt 2 1 Merck & Co, Inc, West Point, PA, USA, 2 University of California San Francisco, San Francisco, CA, USA Background: Gut-associated lymphoid tissue is a major persistent reservoir of HIV DNA and RNA during antiretroviral therapy (ART)-mediated viral suppression, but less is known about HIV protein expression in this compartment, which is required for immune-based clearance strategies and may be more likely than total HIV transcripts to impact systemic immune activation and CD4+ T cell recovery. Methods: HIV gag p24 protein was measured using an ultrasensitive digital ELISA in CD4+ T cells isolated from cryopreserved rectal tissue biopsies (and PBMC in those with available samples) from viremic (n=10 with plasma HIV RNA level >4 log 10 copies/ml), ART-suppressed (n=7 immunologic non-responders [INR] with CD4+ T cell counts <350 and n=7 immunologic responders [IR] with CD4+ T cell counts>500 cells/mm 3 ) and HIV-uninfected participants (n=5) in the SCOPE cohort. Correlations between rectal p24, peripheral blood p24, plasma HIV RNA levels, and immunologic status were assessed with non- parametric tests. Results: Levels of HIV gag p24 protein in rectal and peripheral blood (PB) CD4+ T cells were moderately correlated among all participants (r: 0.54, P=0.0169); however, when restricted to ART-suppressed participants, there was no evidence for a correlation between peripheral blood and rectal CD4+ T cell p24 levels (P=0.35). Rectal p24 levels were also not well correlated to plasma viral load in viremic participants. Nevertheless, rectal CD4 p24 levels discriminated between viremic, ART-suppressed, and HIV-uninfected participants much better than PB CD4 p24 levels (see Figure). Furthermore, while there was no evidence for a difference in PB p24 levels, ART-suppressed immunologic non-responders had significantly higher median rectal p24 levels than immunologic responders (0.024 vs. 0.009 per million rectal CD4+ T cells, P=0.009). Among all ART- suppressed participants, higher rectal p24 levels were associated with lower CD4 counts (r: -0.69, P=0.006) and a trend toward lower CD4/CD8 ratio (r: -0.48, P=0.079). Conclusion: Greater HIV gag p24 protein expression in rectal tissue is strongly associated with poor CD4+ T cell recovery in PB during ART-mediated viral suppression and may not be accurately reflected by PB p24 expression. These findings suggest a potential impact of gut HIV protein expression on immune recovery during ART and highlight the need to assess HIV protein expression in gut tissue (as opposed to simply PB) in studies of immune-based clearance interventions.

Poster Abstracts

CROI 2018 134