CROI 2019 Abstract eBook

Abstract eBook

Poster Abstracts

Methods: Patients with chronic HIV (pts) naïve to ART prior to start darunavir/ ritovavir/ tenofovir disoproxil fumarate/ emtricitabine underwent duodenal biopsies (gut) and phlebotomy at baseline (BL) and at 12 mo of ART. 17 age, sex and risk group (MSM) matched HIV- controls (C) underwent identical procedures one time. T-cell subsets by FACS and lamina propria density by immunohistochemistry (IHC) in gut and PBC and a panel of inflammatory biomarkers were measured by ELISA at BL and 12-mo. Values are expressed as median [interquartile range] and non-parametric were used where appropriate. Results: 18 HIV-positive men with a median baseline CD4+ count of 431 cells/ dL[272-559] and HIV load of 40,500 copies/mL[19,750-84,250], were enrolled. HIV load became undetectable and CD4+ increased to 742 cells/mm3 [561,861] at 12-mo; p=0.001. 17 C were of similar demographics and age. Activated gut CD8+ and central memory (cm) T-cell subsets positively correlated with their peripheral counterparts (Spearman’s rho (SpR)=0.721 and 0.835 respectively; p=0.001). After 48-weeks of treatment only correlation in CD8+ central memory persisted (SpR 0.628;p=0.01). However, no correlations between the total CD4+ CD8+ T-cell between both sites were found suggesting that only activated phenotypes are in equilibrium between compartments. Gut T-cell density (IHC) were lower in pts at baseline 80 CD8+ /mm2 (34-190) and 769 CD4+/mm2 (61-967) compared to C 268 CD8+/mm2 (164-408); p=0.002 and 475 CD4+/mm2 (389-627); p=0.006 respectively. Although partially recovered, differences with controls persisted after 12-months 268 CD8+ /mm2 (164-408) p=0.02 and 475 CD4+/mm2 (389-627);p=0.03. A significant correlation was found at baseline between CD8+ gut density and I-FABP (SpR 0.568;p=0.013) and Thromboplastin (SpR 0.668;p=0.002). Moreover, I-FABP levels at entry were negatively correlated with peripheral CD4+T-cell recovery after ART (SpR -0.577;p=0.012). Conclusion: Our data suggests the potential trafficking between activation phenotypes from GALT and peripheral T-cell subpopulations, and that these drive gut integrity biomarkers. Inflammation and immune changes within the small intestine compartment are associated with immune recovery at that level. 206 ALTERED GUT IMMUNITY IN IMMUNOLOGICAL NONRESPONDERS PARTLY RESTORED BY PROBIOTICS Malin H. Meyer-Myklestad , Martin Kummen, Birgitte Stiksrud, Kristian Holm, Anne Ma D. Riise, Dag Kvale, Ingebjørg Seljeflot, Marius Troseid, Johannes R. Hov, Asle W. Medhus, Dag Henrik Reikvam Oslo University Hospital, Oslo, Norway Background: Immunological non-responders (INR) have increased non-AIDS morbidity. A proposed mechanism for INR’s inferior prognosis is microbial translocation across gut mucosa, which promotes chronic immune activation. In-depth immune function in gut mucosa of INR has not been systematically assessed, nor have the effects of probiotics. Methods: In a cross-sectional study, we included three groups of Caucasian age-matched men: 20 INR (ART>4 years with HIV RNA <50 copies/ml and CD4 count <400 cells/µL for >3.5 years); 20 immunological responders (IR) (ART>4 years with HIV RNA <50 copies/mL and CD4 count >600 cells/µL for >3.5 years) matched on nadir CD4 count; and 20 HIV-negative controls. Mucosal biopsies from the terminal ileum and the sigmoid colon, fecal samples and blood were collected. INR received probiotics (>1.2*1010 cfu/day with five mixed probiotic strains) for 8 weeks in an open-label phase II exploratory interventional trial (NCT02640625), followed by an end-of-study colonoscopy. Lamina propria mononuclear cells were isolated and after mitogenic stimulation, frequencies of Th17 (CD4+IL-17+), Th22 (CD4+IL-22+) and Th1 (CD4+IFNγ+) were measured by flow cytometry. Soluble CD14, IL-6, CD163, CRP, Zonulin, IL-18, intestinal fatty acid binding protein (iFABP), lipopolysaccharide binding protein (LBP), LPS and CD25 were analyzed by ELISA. The microbiome was characterized by 16S rRNA gene sequencing (V3-V4). Results: INR had increased serum levels of iFABP and sCD14 compared with controls (p<0.05). The frequencies of gut mucosal Th17 and Th22 were not significantly different between the three groups. After stratifying INR and IR according to blood CD4/CD8 T cell ratio, INR with low (<0.5) CD4/CD8-ratio had significantly higher frequencies of gut mucosal Th17, Th22 and Th1 cells than IR with high (>1.0) CD4/CD8 T cell ratio (p<0.01). In INR, probiotics for 8 weeks significantly reduced the frequency of Th22 cells in terminal ileum (p<0.05), with a corresponding increase in mucosa-adherent bacterial diversity (Shannon Diversity Index, p<0.01 and Phylogenetic Diversity, p<0.05), whereas no significant changes were observed for the soluble markers.

204 THE ROLE OF CS1 FIBRONECTIN IN HIV-1 INFECTION OF GUT-HOMING T CELLS David A. Plotnik, Wenjin Guo, Brad Cleveland, Shiu-Lok Hu University of Washington, Seattle, WA, USA Background: The intestines are the principle site of HIV replication, and are severely damaged during acute infection. Gut-homing CD4+ T lymphocytes expressing the α4β7 integrin are preferentially targeted by HIV and are implicated in intestinal pathology. Previous studies indicated that gut-homing T cells are targeted through binding of HIV envelope protein to α4β7; however, we demonstrated that purified envelope proteins do not bind to α4β7 (Plotnik et al., J. Virol. 2017). Instead, we discovered that envelope-α4β7 interactions are mediated by the extracellular matrix protein CS1 fibronectin. In the present study, we extended this observation and tested the hypothesis that CS1 fibronectins facilitate infection of α4β7+ T cells. Methods: The recombinant CS1 fibronectin fragment RetroNectin™ (TaKaRa Inc.) was used in our studies. RetroNectin was used to capture HIV on polystyrene plates. Infection of primary α4β7+ T cells by RetroNectin-associated or free viruses was measured by p24 ELISA of culture supernatants. The effects of HIV-neutralizing antibodies and α4β7–blocking antibodies on both modes of infection were compared. Cell-to-cell virus transmission between autologous T cells was measured by flow cytometry. The effect of infection on CS1 fibronectin expression was assessed by co-culturing fibroblasts with infected or uninfected lymphocytes, and measuring CS1 fibronectin mRNA by quantitative PCR. Results: Infection by RetroNectin-captured viruses resulted in threefold higher peak p24 output compared to infection with free viruses. RetroNectin-mediated infection was reduced by α4β7–blocking antibodies Act-1 and 2B4. Importantly, unlike infection by free viruses, infection by RetroNectin-captured viruses was resistant to neutralizing antibodies VRC01, PG16, and 2G12. Cell-to-cell virus transmission was threefold higher in the presence of RetroNectin. CS1 fibronectin mRNA levels were twofold higher in fibroblasts co-cultured with HIV-infected vs. uninfected cells. Conclusion: Results from these studies indicate that CS1 fibronectin may have previously unrecognized roles in HIV infection. These include facilitating α4β7+ cell infection through co-localizing viruses and α4β7+ T cells, and promoting cell-to-cell virus transmission while protecting captured viruses from neutralizing antibodies. Since HIV infection also induces CS1 fibronectin expression in vitro, we hypothesize that CS1 fibronectins may amplify HIV infection in vivo through a positive feedback mechanism. 205 INFLAMMATION WITHIN THE SMALL INTESTINE IS ASSOCIATED WITH IMMUNE RECONSTITUTION Robert C. Güerri-Fernández 1 , Netanya S. Utay 2 , Zhong-Min Ma 1 , Surinder Mann 1 , Talía Sainz 3 , Marjorie Pion 4 , Richard Pollard 1 , Alan Landay 5 , David M. Asmuth 1 1 University of California Davis, Davis, CA, USA, 2 University of Texas at Houston, Houston, TX, USA, 3 La Paz University Hospital, Madrid, Spain, 4 Hospital General Universitario Gregorio Marañón, Madrid, Spain, 5 Rush University, Chicago, IL, USA Background: The relationship between immune reconstitution after starting cART in gut, peripheral blood and persistent systemic inflammation is poorly understood. We sought to investigate how gut immune reconstitution impacts residual systemic inflammation.

Poster Abstracts

73

CROI 2019