CROI 2017 Abstract e-Book

Abstract eBook

Poster and Themed Discussion Abstracts

(CD57) and memory (CD45RO) surface markers by flow cytometry. We compared T cell surface marker expression in paired blood and AT using Wilcoxon Signed Rank tests, and the correlation using Spearman’s tests. We performed T cell receptor (TCR) sequencing on sorted CD8+ cells and compared the repertoire diversity in blood versus AT using the tcR R statistics package. Proportional downsampling and bootstrapping were used to account for read count distribution differences between tissue compartments. Results: Six subjects were female, median age was 46 years, median CD4+ count was 819 cells/µl, and median antiretroviral therapy duration was 9.6 years. AT had a higher overall percentage of CD8+ T cells compared to blood, and was also enriched for activated CD8+ T cells (p<=0.01 for all; see Table). The percentages of memory CD4+ T cells in AT and blood were correlated, as were the percentages of activated HLA-DR+ CD8+ T cells. The 10 most prevalent CD8+ TCR clones comprised a larger percentage of total clones in the AT compared to blood (25% vs. 16%, p=0.04), and the Shannon’s Entropy index, a measure of overall repertoire diversity, was lower in AT compared to blood (4.39 vs. 4.46; p=0.05). Conclusion: In this pilot study, subcutaneous AT from HIV+ patients was enriched for activated CD8+ T cells, which promote adipocyte insulin resistance, and TCR analysis showed less repertoire diversity and a disproportionate expansion of specific CD8+ T cell clones in AT compared to blood. The percentages of memory CD4+ T cells and activated CD8+ T cells were correlated between blood and AT, which may be relevant to understanding the epidemiologic association of peripheral T cell activation and diabetes risk.

Poster and Themed Discussion Abstracts

231 REDUCED APOPTOSIS CONTRIBUTES TO GASTROINTESTINAL NEUTROPHIL INFILTRATION IN HIV Tiffany Hensley-McBain 1 , Jennifer Manuzak 1 , Charlene Miller 1 , Alexander S Zevin 1 , Eric Lee 2 , Cara Wilson 2 , Thomas Hope 3 , Adam Burgener 4 , Nichole Klatt 1 1 Univ of Washington, Seattle, WA, USA, 2 Univ of Colorado Anschutz Med Campus, Aurora, CO, USA, 3 Northwestern Univ, Evanston, IL, USA, 4 Pub Hlth Agency of Canada, Winnipeg, Canada Background: HIV infection is associated with mucosal dysfunction and inflammation, which is associated with morbidities and mortality. However, the mechanisms underlying these dysfunctions are not resolved. Imaging studies indicate increased neutrophils in the GI tract during HIV infection, potentially contributing to mucosal inflammation. In inflammatory bowel disease, neutrophils contribute to pathogenesis and GI infiltration is linked to delayed homeostatic apoptosis and longer lifespan, yet GI neutrophil apoptosis in HIV remains unexamined. Further, given the well-described shift in the GI microbiome in HIV and the fact that bacterial ligands affect neutrophil lifespan, there is potential for altered bacteria to contribute to increased GI neutrophils in HIV. Our study aimed to better assess neutrophil infiltration in the GI in HIV infection and investigate Caspase-3 dependent homeostatic apoptosis. We further sought to understand how HIV altered mucosal bacteria (HAMBs), or those increased or decreased in the GI, affect neutrophil apoptosis. Methods: Isolated leukocytes from rectosigmoid colon biopsies taken from treated, HIV-infected (n=10) and uninfected (n=8) individuals were phenotyped by flow cytometry to examine neutrophil frequency and active Caspase-3 expression. In additional experiments, blood from infected and uninfected individuals (n=8) was stimulated for 20 hours with a panel of six HAMBs that included Gram-negative and Gram-positive bacteria and those increased or decreased in HIV prior to phenotyping. Results: We found increased neutrophils (p=0.0219) and reduced active Caspase-3 expression in neutrophils (p<0.0001) in the GI of HIV-infected indviduals compared to uninfected controls. Further, neutrophil frequency negatively correlated with Caspase-3 expression (p=0.0207). Blood stimulations demonstrated that while dysbiotic bacteria decreased Caspase-3 expression compared to media controls, beneficial Lactobacillus increased Caspase-3 (p=0.0219). Conclusion: These are the first data demonstrating that increased neutrophils in the GI in HIV may be a consequence of delayed homeostatic apoptosis. Our data also suggest dysbiosis that results in decreased anti-inflammatory bacteria such as Lactobacillus species and increased bacteria such as Prevotella species may alter neutrophil apoptosis and prolong GI neutrophil lifespan in HIV. These data provide a novel mechanism by which microbial dysbiosis in HIV infection may contribute to neutrophil accumulation and mucosal dysfunction. 232 HIV INDUCES LIPID ACCUMULATION IN ALVEOLAR MACROPHAGES IN VITRO Amy K. Dickey 1 , Bjorn Corleis 2 , Abigail Schiff 3 , Antonella Lisante 2 , Benjamin Medoff 1 , Josalyn Cho 1 , Douglas Kwon 2 1 Massachusetts General Hosp, Boston, MA, USA, 2 Ragon Inst of MGH, MIT, and Harvard, Cambridge, MA, USA, 3 Harvard Univ, Boston, MA, USA Background: In patients with HIV, infection with respiratory pathogens is an important cause of morbidity and mortality. Alveolar macrophages are the predominant immune cell in the airways in non-disease states and are thought to act as the initial defense against pulmonary pathogens. Monocytes from HIV+ individuals are known to have decreased expression of ABCA1, a gene responsible for lipid efflux, and these monocytes are more likely to become lipid-laden macrophages in arterial walls, promoting atherosclerosis. Lipid-laden macrophages are of particular interest in airway immunity because they are deficient in uptake of M. tuberculosis (Mtb) and impaired in Mtb intracellular killing, while simultaneously acting as promoter of Mtb latency. Because these studies on lipid-laden macrophages have been performed using monocyte-derived macrophages (MDMs) in vitro, it is unclear whether or not these lipid-laden macrophages are abundant in the alveolar space in patients with HIV, and, if present, what effect these cells would have on airway immunity.

90

CROI 2017