CROI 2017 Abstract e-Book

Abstract eBook

Poster and Themed Discussion Abstracts

215 TWO-YEAR CART DOES NOT RESTORE PERIPHERAL BLOOD AND INTESTINAL HIV-RELATED DYSBIOSIS Camilla Tincati 1 , Giuseppe Ancona, Esther Merlini, Antonella d’Arminio Monforte, Giulia Marchetti Univ of Milan, Milan, Italy

Background: Microbial dysbiosis features HIV+ individuals, both naïve and cART-treated, and is linked to anatomical/structural changes in the gastrointestinal (GI) tract, leading to microbial translocation (MT) and immune activation. Given that data on microbiota modifications during long-term therapy are lacking, we investigated gut/blood microbiota during the first 2 years of suppressive cART. Methods: We enrolled 41 HIV+, naive subjects and 14 uninfected controls. In HIV+, stool/plasma were collected at baseline (T0), after 12 (T12) and 24 months (T24) of cART. DNA extraction and 16S Metagenomic Sequencing (MiSeq Illumina®) were performed to study the relative abundance at each taxonomic level, α- and β-diversity. GI permeability (LAC/ MAN test)/damage (I-FABP; E-cadherin), inflammation (faecal calprotectin) and MT (sCD14, EndocAb, LPS) were measured in HIV+ at T0 and T12 and analysed by Wilcoxon test. Results: In our cohort 12%were female, 68%MSM, 5% HCV+; median age, CD4+ count, HIV RNA and duration of infection were respectively 42 years, 342/mmc, 5 log10cp/ mL and 14 months. We did not detect major changes in plasma microbiota at T12 and T24 or differences between HIV+ and uninfected subjects in relative abundance, α- and β-diversity. With the exception of a selective increase of Negativicutes (class; T0: 6%, T12: 15%; T24: 14%), also the relative abundance of the faecal microbiota did not show significant variations during cART, with stable representation of bacterial families, genera, species. Further, compared to controls, HIV+ constantly displayed lower Ruminhococcaceae (family) and Bacteroides (genera), higher Gammaproteobacteria (class), and an overall trend to increased α-diversity measures (Figure 1A) regardless treatment status/follow-up. While PCoA plots for the study of β-diversity did not show clustering of faecal samples on the basis of the HIV serostatus and length of cART, Lefse analyses (LDS >2.0) confirmed many differences between HIV+ at all study time-points and controls (Figure 1B). At T12, HIV+ experienced a rise in IFABP (p=0.04), a reduction in calprotectin (p=0.01), with no other modifications in MT, gut structure and function. Conclusion: HIV-related modifications of the microbiota occur within the GI tract and not in the blood and are minimally affected by long-term effective cART, despite evidence of the containment of gut inflammation. These data suggest the ability of the virus to irreversibly impact the microbiological core of chronically-infected individuals.

Poster and Themed Discussion Abstracts

216 ANTIBIOTICS DISRUPT GASTROINTESTINAL BACTERIA AND HOST IMMUNITY IN RHESUS MACAQUES Alexander S. Zevin , Jennifer A. Manuzak, Tiffany Hensley-McBain, Ryan Cheu, Charlene Miller, Jacob Modesitt, Jeremy Smedley, Nichole Klatt Univ of Washington, Seattle, WA, USA

Background: Antibiotics are widely used throughout the world to treat bacterial infections that occur independently or as a result of HIV infection. However, mounting evidence suggests that antibiotic therapies can disrupt the composition of the gastrointestinal (GI) microbiome. Further, HIV infection is associated with disrupted GI microbiota in individuals independent of antibiotic use. GI-resident microbiota are critical for maintaining host immune homeostasis and protecting against the expansion of pathobionts. Additionally, microbiota-derived metabolites, such as short chain fatty acids (SCFAs), are key energy sources for colonic epithelial cells. Thus, we hypothesized that antibiotic therapies would disrupt the GI microbiome and host mucosal immunity. Methods: We administered antibiotics each to four groups of healthy female rhesus macaques and collected GI biopsies and with stool (Group 1 – enrofloxacin, Group 2 – cephalexin, Group 3 – paramomycin, Group 4 – clindamycin). We evaluated host mucosal immunity throughout the antibiotic treatment at each GI site, and tracked bacterial abundance using qPCR. Finally, we used GC-MS to evaluate the concentration of SCFAs in the stool. Results: We found that the antibiotic treatments were linked to quantitative shifts in the bacterial abundance in the stool. Intriguingly, we found that the antibiotic treatments dramatically decreased the concentration of all measured SCFAs in the stool, some below the detection limit, including butyrate, the major energy source for colonic epithelial cells. We also demonstrated changes in mucosal immunity during the antibiotic treatment, including a significant increase in colonic and rectal mucosal neutrophils during the treatment, which returned to normal values after cessation of antibiotics. We also found increased frequencies of colonic activated IL-23-producing antigen presenting cells, activated CD4+ T-cells, and IL-17 producing CD4+ T-cells, although this did not reach statistical significance. Conclusion: Our data demonstrate that antibiotic therapies can alter GI bacterial abundance, lead to a decrease in SCFAs, and that these changes were linked to a distinct signature of mucosal inflammation. These data demonstrate how altering the structure and function of GI bacterial communities can have a profound effect on mucosal immunity. Thus, in HIV infection, resolving bacterial dysbiosis and limiting antibiotic use may be key to maintaining mucosal health.

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CROI 2017