CROI 2019 Abstract eBook

Abstract eBook

Poster Abstracts

Conclusion: INR had increased markers of impaired mucosal barrier function. INR with low blood CD4/CD8 T cell ratio had elevated frequencies of mucosal CD4 subsets, indicating a more pro-inflammatory tissue environment. The alterations were partially reversed by probiotics, providing a rationale for further trials of gut targeted treatment in INR. 207 INCREASED ADENOSINE SIGNALING WITH DIPYRIDAMOLE DECREASES GUT MUCOSAL TREG FREQUENCY Bernard J. Macatangay 1 , Edwin Jackson 1 , Kaleab Abebe 1 , Ashley Myerski 1 , Cynthia Klamar-Blain 1 , Delbert Gillespie 1 , Diane` Comer 1 , Kyle Holleran 1 , Karin L. Klingman 2 , Charles Rinaldo 1 , Ian McGowan 1 , Sharon Riddler 1 1 University of Pittsburgh, Pittsburgh, PA, USA, 2 National Institute of Allergy and Infectious Diseases, Bethesda, MD, USA Background: Adenosine (ADO) production is increased during inflammatory states to limit tissue damage. In a study evaluating the anti-inflammatory effect of dipyridamole (DP) among virally suppressed people with HIV (PWH), we evaluated how DP-induced increase in ADO signaling can affect gut mucosal T cell populations. Methods: Virally-suppressed adults on ART were enrolled, randomized 1:1, to receive DP (100mg 4x/day) or placebo, double blinded, for 12 weeks. In a subset of participants, we obtained rectosigmoid biopsies at baseline and 12 weeks, and processed these biopsies into mucosal mononuclear cells (MMC) for flow cytometry studies. We evaluated frequencies of T cells in gut MMC, including frequencies of the regulatory T cell (Treg) and Th17 cell subset to assess changes after 12 weeks of DP vs placebo. Plasma levels of DP, inosine (initial ADO metabolite and surrogate for ADO levels), and urine cAMP (produced when ADO binds to its receptor) were measured by mass spectrometry. Linear regression models on log-transformed outcomes were used for the primary 12-week analysis. Results: Nine DP and 9 placebo participants with data from both baseline and 12 weeks were included in the analyses. Median peripheral blood baseline CD4+ T cell counts were 718 and 666 cells/mm3 for DP and placebo, respectively (p=0.70). At visits when participants had detectable plasma DP (9/9 in DP and 0/9 in placebo), median plasma inosine and urine cAMP levels were higher compared with each participant’s baseline (p=0.03 and p=0.05, respectively). Compared to placebo, DP participants had a significant decrease in absolute %Treg in gut mucosal CD4+ T cells from baseline to week 12 (5.99 to 2.09% for DP vs 2.91 to 4.76% for placebo; p=0.008). There was also a trend for increased gut mucosal %CD8+ T cells in the DP arm (36.0 to 40.9% in DP vs 40.7 to 35.3% in placebo; p=0.054). No differences were observed in the baseline to week 12 change in gut mucosal %CD4+ T cells, %Th17, and Th17:Treg ratios, or in baseline to week 12 change in peripheral blood CD4+ and CD8+ T cells and Treg. Conclusion: Oral dipyridamole administered to PWH on ART was associated with a significant decrease in gut mucosal Treg frequencies and a trend for increased frequencies of gut CD8+ T cells. Our results suggest that modulating adenosine signaling among virally-suppressed PWH on ART could regulate gut mucosal immunity. How this regulation affects control of the gut HIV reservoir should be further studied. 208 PD-1HI CD4+ T CELLS ARE ASSOCIATED WITH REDUCED HIV-SPECIFIC RESPONSES Bernard J. Macatangay 1 , Rajesh T. Gandhi 2 , R. Brad Jones 3 , Deborah McMahon 1 , Allison S. Thomas 4 , Christina Lalama 5 , Ronald Bosch 5 , Luann Borowski 1 , Evelyn Hogg 6 , Joseph J. Eron 7 , John W. Mellors 1 , Charles Rinaldo 1 , for the ACTG A5321 Study Team 1 University of Pittsburgh, Pittsburgh, PA, USA, 2 Harvard Medical School, Boston, MA, USA, 3 New York Presbyterian Hospital, New York, NY, USA, 4 Boston University, Boston, MA, USA, 5 Harvard University, Boston, MA, USA, 6 Social & Scientific Systems, Silver Spring, MD, USA, 7 University of North Carolina at Chapel Hill, Chapel Hill, NC, USA Background: T cells with high expression of PD-1 (PD-1HI), a marker of T cell exhaustion, persist among people with HIV on antiretroviral therapy (ART).To assess whether PD-1HI expression may reflect exhaustion of T cells targeting HIV, we determined whether the frequency of PD-1HI T cells is associated with reduced HIV-specific T cell responses. Methods: Peripheral blood mononuclear cells from participants in ACTG A5321 with documented viral suppression on ART for at least 4 years (N=93) were analyzed for percentage of CD4+ and CD8+ T cells with PD-1HI expression as determined by flow cytometry. HIV-specific T cell immunity was determined

by IFNγ ELISPOT in response to Gag, Pol, Env, Nef/Tat/Rev, Vpr/Vpf/Vpu peptide pools as well as CMV-pp65 and EBV BZLF-1 peptide pools. Results: Frequencies of both CD4+ and CD8+ PD-1HI T cells pre-ART significantly correlated with levels of pre-ART HIV-1 RNA (r=0.28, p=0.01 and r=0.24, p=0.03, respectively; Spearman correlation). At 4 years of viral suppression with a median CD4+ T cell count of 681 cells/mm3, participants had the same median (Q1-Q3) frequencies of PD-1HI CD4+ (0.3%; 0.1-0.5) and CD8+ (0.3%; 0.2-0.6) T cells. Both CD4+ and CD8+ PD-1HI T cell frequencies showed negative correlations with IFNγ responses to all HIV peptides, although not all reached statistical significance. The %CD4+ PD-1HI T cells had significant negative correlations with Gag- and Env-specific responses (r= -0.24, p=0.04 and r= -0.32, p=0.005; Figure 1). A modest negative trend was observed with Pol (r= -0.2; p=0.08) and combined Vpr/Vif/Vpu (r= -0.22, p=0.07) peptide pools. The %CD8+ PD-1HI T cells showed a trend for a negative correlation with the same HIV peptide pools (Gag, r= -0.22, p=0.06; Env, r= -0.21, p=0.07). By contrast, no significant correlations were observed between PD-1HI T cell frequencies and responses to CMV or EBV peptides. Conclusion: Peripheral blood frequencies of PD-1HI CD4+ T cells of people with HIV on ART were negatively associated with HIV-specific IFNγ responses, but not with CMV or EBV responses. These findings suggest that the PD-1HI CD4+ T cell subset contains HIV-specific cells that have decreased helper function and should be targeted to reverse immune dysfunction and improve immune control of HIV.

Poster Abstracts

209 PROPORTION OF SIV-INFECTED MEMORY T HELPER SUBSETS CORRELATED TO SIZE OF POPULATION Stephen Lai , Jason Brenchley, Joseph Mudd NIH, Bethesda, MD, USA

Background: Naïve CD4 T cells can differentiate into multiple functionally- defined memory CD4 T cell subsets. The types of memory CD4 T cells which exist in tissues of HIV/SIV-infected individuals are perturbed compared to healthy individuals. The mechanisms underlying these functional perturbations remain unclear. Here we assess whether viral infection of functionally-defined memory CD4 T cells might contribute, and how these populations of memory CD4 T cells contribute to, the total pool of infected CD4 T cells and plasma viremia. Methods: Lymphocytes from Peripheral Blood Mononuclear Cells (PBMC), spleen, and Mesenteric Lymph Nodes (MLN) of SIV+ rhesus macaques were isolated and simulated for 6 hours with PMA and ionomycin in the presence of Brefeldin A. CD28+memory CD4 T cells were studied and CCR6+/IL-17+ and IL-17- CD4 T cells (Th17 cells), CCR4-/IFNg+ and IFNg- CD4 T cells (Th1 cells), CCR4+/IFNg-/IL-17- CD4 T cells (Th2 cells) and FoxP3+ CD4 T cells (Tregs) were then flow cytometrically isolated, and the proportions of cells harboring SIV DNA were then assessed through qPCR. Results: Viral DNA was detected in all subsets of memory CD4 T cells (irrespective of functionality, phenotype, or anatomic location). However, irrespective of anatomic site studied, we found that no one population of isolated memory, CD28+, CD4 T cells harbored more (or less) viral DNA than any other population of memory CD4 T cells. Conclusion: Loss of CD4 T cells is a hallmark of progressive HIV/SIV infection and several studies have shown that Th17 cells are preferentially loss from mucosal tissues and lymph nodes that drain mucosal tissues. However, our data suggest that preferential infection of Th17 cells is unlikely to cause this immunological perturbation. Moreover, we see a positive correlation between the size of a T helper subset population and its contribution to the infected memory pool. Thus, functional differentiation of memory CD4 T cells is unlikely to influence their susceptibility to infection in vivo.

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CROI 2019