CROI 2016 Abstract eBook

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Poster Abstracts

(intracellular p24), activation (CD38/HLA-DR; CD25), proliferation (CFSE) and HIV-1 co-receptor expression (CCR5, CD4). Levels of CD4 T cell depletion were also determined. Non- parametric statistical analyses were performed. Results: The majority of HAMB significantly (p<0.05) increased LP CD4 T cell infection and depletion, but GN HAMB enhanced T cell infection to a greater degree than GP HAMB . Most GN HAMB enhanced T cell infection and depletion similarly to E. coli despite lower HAMB stimulation of T cell activation and proliferation. GN HAMB and GN bacterial cell wall Lipopolysaccharide (LPS) induced upregulation of CCR5 expression on LP CD4 T cells (p<0.05), whereas GP cell wall lipoteichoic acid (LTA) did not (p=0.3). GN HAMB-induced CCR5 upregulation was largely abrogated in CD4 T cell-enriched cultures suggesting an indirect mode of stimulation. Conclusions: GN commensal bacteria that are altered in abundance in the colonic mucosa of HIV-1 infected individuals have the capacity to enhance productive CCR5-tropic HIV-1 infection and depletion of LP CD4 T cells in vitro . Enhanced infection likely results from increased expression of the HIV-1 co-receptor CCR5 on LP CD4 T cells, mediated by indirect exposure to LPS. This represents a novel mechanism that potentially links intestinal dysbiosis to HIV-1 mucosal pathogenesis. 263 Enhancement of Microbiota in Macaques Leads to Beneficial Immune Function Modulation Jennifer A. Manuzak 1 ;Tiffany Hensley-McBain 1 ; Charlene Miller 1 ; Alexander Zevin 1 ; Jason M. Brenchley 2 ; Jacob D. Estes 3 ; Stanley Langevin 1 ; R. Keith Reeves 4 ; Elias Haddad 5 ; Nichole Klatt 1 1 Univ of Washington, Seattle, WA, USA; 2 Frederick Natl Lab for Cancer Rsr, Frederick, MD, USA; 3 Frederick Natl Lab, Leidos Biomed Rsr, Frederick, MD, USA; 4 Harvard Univ, Boston, MA, USA; 5 Drexel Univ, Philadelphia, PA, USA Background: With more than thirty million HIV-infected individuals worldwide, developing an effective vaccine to prevent new HIV infections remains a top priority in contemporary biomedical research. Given the critical role of mucosal surfaces in susceptibility to HIV, it is imperative that we induce effective mucosal responses. However, current approaches to enhance mucosal immunity have not been successful in preventing HIV acquisition. Modulating the microbiota in the GI tract is a safe and well-tolerated approach to enhance mucosal and overall health. We assessed the longitudinal impact of daily treatment with the VSL#3 probiotic (PBio) on cellular and humoral immunity and inflammation in healthy macaques. Methods: Five macaques (SIV-) were treated with the PBio VSL#3. Colon, jejunum and LN were sampled prior to PBio treatment (PBio-tx) and at days 28 and 77/80 post-treatment. Indicators of cellular and humoral immunity and inflammation were assessed using multi-parameter flow cytometry. Results: PBio-tx resulted in significantly increased frequencies of B cells expressing IgA in the colon ( p =0.0072) and LN ( p =0.0151) d80 post-PBio-tx, likely due to persistently increased LN T follicular helper cell (Tfh) frequencies (d28: p =0.0085; d80: p =0.0173). Increased frequencies of IL-23+ antigen presenting cells (APCs) in the colon ( p =0.0173) and LN ( p =0.0475) were found d28 post-PBio-tx, and colon IL-23+ APCs correlated with the frequency of LN Tfh ( p =0.0358, r =0.5446). Increased frequencies of ILC3 in the jejunum were observed ( p =0.005) d80 post-PBio-tx. The frequencies of activated (HLA-DR+) and proliferating (Ki-67+) CD4+ T cells were significantly decreased in the colon at d28 (p=0.0310 and 0.0042, respectively) and d80 (p=0.0612 and 0.0013, respectively) post-pBio-tx. Finally, VSL#3 significantly down-modulated the response of TLR2-, 3-, 4-, and 9-expressing HEK293 cells to stimulation with Pam3CSK4, Poly(I:C), LPS, and ODN2006, respectively ( p <0.0001). Conclusions: These data provide a mechanism for the beneficial impact of PBio on mucosal health and has potential implications for using PBio-tx to alter mucosal immunity in the context of vaccination or preventative approaches. In particular, the immunomodulatory properties of PBio-tx in conjunction with HIV vaccination may provide an opportunity for enhanced mucosal HIV vaccine responses that could improve protection from infection by improving immune defenses at the mucosal portal of entry and regulating the frequency of potential target cells. 264 Background: Despite antiretroviral therapy (ART), a substantial number of HIV-infected individuals exhibit chronic systemic inflammation. Many treated HIV-infected individuals exhibit marked alterations in the gut microbiome, and the degree of dysbiosis correlates positively with plasma markers of inflammation. Whether interventions to modulate the microbiome can affect systemic inflammation is not known. Methods: A single-arm colonoscopically delivered fecal microbial transplantation (FMT) was employed. Participants with CD4 T cell count <500 cells/mL and CD4 to CD8 ratio < 1.0 were preferentially recruited. Participants were screened for infectious pathogens in stool. OpenBiome provided donor material for FMT. Participants will be followed for 6 months post-FMT for adverse events, blood draws, dietary history, and stool samples. Stool was examined for engraftment of donor microbes and peripheral blood was assayed for biomarkers of immune activation at weeks -2, 1, and 8 relative to FMT. HIV-infected participants undergoing clinical colonoscopy served as controls. Appropriate regulatory approvals were obtained (FDA IND 15926, UCSF IRB 13-12675, NCT02256592). Results: Nine individuals were screened and 6 were enrolled for FMT. One was excluded because of multiple comorbidities and two declined participation. All enrolled participants were men, median age was 61 (range 31-72), median CD4 was 431 (range 357-835), and median CD4 to CD8 ratio was 0.44 (range 0.33-1.36). All 6 who received FMT had at least 8 weeks of follow-up post-FMT with no serious adverse effects (range of follow-up, 8-24 weeks). One participant reported increased dizziness at week 8 however vital signs were stable and there were no episodes of syncope. Two participants with baseline loose stools reported that their stool quality improved (Bristol stool scale 5-6 to 4). Preliminary bacterial community sequence analyses indicated that FMT recipients exhibited greater compositional changes in their fecal microbiome beyond those observed over a comparable time period in control subjects although comparison with donor community is still pending. Kynurenine to tryptophan ratio showed no evidence for change pre- and post-FMT. Conclusions: FMT was well tolerated in HIV-infected ART-suppressed individuals without significant adverse effects. The impact of FMT to alter the fecal and mucosal microbial communities and its effects on systemic inflammation is currently being investigated and will be discussed. Fecal Microbial Transplantation: Safety and Engraftment During Treated HIV Infection Ma Somsouk 1 ; IvanVujkovic-Cvijin 2 ; Montha Pao 1 ; PeterW. Hunt 1 ; SusanV. Lynch 1 ; Joseph M. McCune 1 1 Univ of California San Francisco, San Francisco, CA, USA; 2 NIH, Bethesda, MD, USA

Poster Abstracts

102

CROI 2016