CROI 2019 Abstract eBook

Abstract eBook

Poster Abstracts

238 CHLAMYDIA AND CERVICOVAGINAL MICROBIOTA MODULATE GENITAL- TRACT CD4+ T-CELL SUBSETS Seth M. Bloom 1 , Nondumiso N. Xulu 2 , Nomfuneko A. Mafunda 2 , Mara Farcasanu 2 , Matthew R. Hayward 2 , Kendall R. Jackson 2 , Douglas Kwon 2 1 Massachusetts General Hospital, Boston, MA, USA, 2 Ragon Institute of MGH, MIT and Harvard, Cambridge, MA, USA Background: Mucosal CD4+ T cells are critical to female genital tract (FGT) health, helping control bacterial, viral, and fungal infections while serving as primary targets for HIV transmission. Immune responses to FGT infections are known to depend on T helper subsets including Th17 and regulatory (Treg) cells in mouse models, but human studies have been hampered by paucicellular samples, small cohort size, and sexually transmitted infections (STIs). FGT Th17 cells (often experimentally defined by markers CCR6 and/or CD161) have been studied in context of inflammation and HIV, but FGT Tregs remain poorly characterized. Importantly, different T helper subsets are differentially permissive to HIV infection. We hypothesized that mucosal CD4+ T cell subset composition was modulated by both chlamydia and the non-STI genital tract microbiota. Methods: We examined FGT CD4+ T cell subsets in a cohort of 119 HIV- negative South African women (ages 18-24). We used flow cytometry of cervical cytobrush samples to enrich for Th17 cells and Tregs by gating on CD161+CCR6+ and CD25+CD127Lo- cells respectively. We identified bacterial STIs via commercial laboratory testing and characterized the microbiota using bacterial 16S gene rDNA sequencing. Data were analyzed with DADA2 and custom R scripts. Results: Median cervical CD161+CCR6+ and CD25+CD127Lo- CD4+ T cell frequencies were 48.0% and 12.4% respectively. Subjects with chlamydia had higher numbers of activated CD4+ T cells, as well as higher frequency of CD25+CD127Lo- (Fig A), lower frequency of CD161+CCR6+, and lower ratio of CD161+CCR6+ / CD25+CD127Lo- CD4+ T cells (p < 0.002 for each, Mann- Whitney U test). Using 16S sequencing, we classified STI-negative women into microbial cervicotypes and found significant cervicotype-related differences in T helper subsets, attributable in large part to Gardnerella vaginalis . Subjects with G. vaginalis -high communities (defined as exceeding median G. vaginalis abundance of 6.7%) had higher CD25+CD127Lo- CD4+ T cell frequency (p < 0.001; Fig B) and lower CD161+CCR6+ / CD25+CD127Lo- ratio (p = 0.012). We saw no differences in paired peripheral blood samples, confirming the effects were due to local rather than systemic factors. Conclusion: We characterized FGT CD4+ T cell subsets and showed they were associated with both chlamydia and the non-STI microbiota. Future work will investigate the mechanistic basis for these findings and implications for adaptive immunity and HIV.

237 GENITAL AND SYSTEMIC INFLAMMATION ASSOCIATED WITH FACTORS THAT MAY ALTER HIV RISK Randy Stalter 1 , Margot Plews 2 , Romel Mackelprang 1 , Adam Burgener 3 , Rena Patel 1 , Renee Heffron 1 , Kavita Nanda 4 , Florian Hladik 5 , Sean Hughes 5 , Jared Baeten 1 , Nelly R. Mugo 1 , Athena Kourtis 6 , Adrienne Meyers 2 , Jairam Lingappa 1 , for the Partners PrEP Study Team 1 University of Washington, Seattle, WA, USA, 2 Public Health Agency of Canada, Winnipeg, MB, Canada, 3 University of Manitoba, Winnipeg, MB, Canada, 4 FHI 360, Durham, NC, USA, 5 Fred Hutchinson Cancer Research Center, Seattle, WA, USA, 6 CDC, Atlanta, GA, USA Background: Evidence suggests that epidemiologic factors modify susceptibility to HIV-1 acquisition by modulating innate inflammatory responses, and defining these changes may identify novel HIV-1 prevention interventions. However, few studies have assessed host responses to varied HIV risk altering exposures in the genital (vaginal and cervical) as well as systemic compartments. Here we compare vaginal, cervical and systemic inflammatory responses to potential HIV-1 risk modulating exposures ([depot] medroxyprogesterone acetate [MPA], bacterial vaginosis [BV], genital herpes [HSV-2], and oral HIV pre-exposure prophylaxis [PrEP]) to identify compartment-specific cytokine signatures. Methods: We analyzed vaginal and cervical swabs and serum samples collected at 90 visits from 68 HIV-negative Kenyan and Ugandan women enrolled in the Partners PrEP Study. We measured compartment-specific concentrations of 28 cytokines using Milliplex beads, and tested for associations with PrEP use, serum MPA concentrations, BV and non-lactobacillus dominant (NLD) vaginal flora, and HSV-2 infection. We defined inflammation status as: 1) elevated IL1α or IL1β, or lowered IP10 (based on published literature), or 2) cytokine sets associated with each exposure from the 28 measured. We used logistic regression to assess associations of exposures with the IL1α/IL1β/IP10 signature and LASSO regularization to identify exposure-specific cytokine sets. Results: In multivariable models, NLD flora (OR=13.4, 95%: CI 2.96-60.4) were associated with increased odds, and MPA (OR=0.15, 95% CI: 0.02-0.92) and PrEP exposure (OR=0.11, 95% CI: 0.02-0.59) were associated with reduced odds of the IL1α/IL1β/IP10 signature in the vagina (Table 1). No HIV risk modulators were associated with cervical or systemic inflammation. By LASSO regression, NLD flora were associated with IFNα2, IL-12 p40, IL-17A, IL1β, IL-1RA, IL-33, IL-8, IP-10, TNFα and sCD40L concentrations in the vagina. BV was associated with IP-10 concentration in the cervix. PrEP cessation was associated with concentrations of IFNα2 and IL-21 in the vagina and IL-15, IL-1β, IL-1RA, IL-2, IL-21 and MIP-1β in the cervix. No systemic exposure-specific cytokine sets were identified. Conclusion: We identified associations between inflammatory signatures in vaginal and cervical compartments and potential HIV risk exposures that warrant further investigation. To this end, we intend to assess for similar signatures in a larger, more diverse sample of HIV-1 seronegative African women.

Poster Abstracts

84

CROI 2019