CROI 2020 Abstract eBook

Abstract eBook

Poster Abstracts

mice was monitored by the National Gnotobiotic Rodent Resource Center with Gram stain, culture and PCR. BLT mice colonized with gut microbiome were also constructed. To directly evaluate the effect of gut microbiota on HIV acquisition risk after oral exposure, germ-free BLT mice (n=8) and colonized BLT mice (n=10) were exposed to HIV via oral gavage. HIV-RNA levels were monitored longitudinally in the peripheral blood plasma of mice weekly by real-time PCR analysis. At necropsy, we also measured HIV-DNA levels in tissues. Results: Following a single oral HIV exposure, HIV-RNA was detected in the plasma of 4/10 colonized BLT mice. Remarkably, no HIV-RNA was detected in the plasma of germ-free BLT mice. Given that breastfed infants are repeatedly exposed to HIV, we administered a second dose of HIV to BLT mice with a negative HIV viral load. Following a second HIV exposure, 5/6 colonized BLT mice became positive for HIV. In sharp contrast, only 2/8 germ-free BLT mice became positive for HIV. Overall, gut microbiota significantly increased oral HIV acquisition of colonized BLT mice (9/10 vs 2/8, p=0.01). Conclusion: To our knowledge, these results provide the first direct evidence that gut microbiota facilitate HIV acquisition. 206 KYNURENINE PATHWAY ACTIVITY REMAINS ABNORMAL DESPITE VERY EARLY ART INITIATION Samuel R. Schnittman 1 , Amelia Deitchman 1 , Gabriele B. Beck-Engeser 1 , HaeLee Ahn 1 , Vanessa A. York 1 , Heather Hartig 1 , Rebecca Hoh 1 , Frederick M. Hecht 1 , Jeffrey N. Martin 1 , Steven G. Deeks 1 , Francesca Aweeka 1 , Peter W. Hunt 1 1 University of California San Francisco, San Francisco, CA, USA Background: Despite early ART initiation, ART-suppressed people living with HIV (PLWH) remain at higher risk for tuberculosis (TB) and infection-related malignancies than the general population. The immunologic pathways that remain abnormal in this setting—and may plausibly drive these complications—are unclear. Methods: PLWH maintaining ART-mediated viral suppression >1 year and HIV-negative controls, all CMV+ and enriched for HIV risk factors, were sampled from a study of influenza vaccine response. PLWH were stratified by timing of ART initiation (within 6 months of HIV infection [early ART] vs. later), and among later initiators, by nadir CD4 count (>350, 200-350, <200 cells/mm 3 ). Plasma kynurenine/tryptophan (KT) ratio (by LC-MS) and both sTNFR2 and sCD14 (by ELISA) were assessed before vaccination. Between-group differences adjusted for age, sex, # lifetime male sexual partners, and ART type were assessed by linear regression, transforming biomarkers as necessary. Results: A total of 164 PLWH and 41 HIV-negative participants were enrolled. Median age was 54 years and 91%were men. Of HIV-negatives, 56%were MSM, 41% had >100 lifetime male sexual partners, and 15% had distant IDU. Of the PLWH, 34 were early ART initiators and the remainder had a range of nadir CD4 counts: >350 (n=32), 200-350 (n=43), and <200 cells/mm 3 (n=55). Median duration of viral suppression was 8 years (IQR 5-11 years). Compared to HIV-negatives, PLWH with later ART initiation had higher KT ratio, sCD14, and sTNFR2 after adjustment for age and sex, but only KT ratio and sCD14 remained abnormal in the early ART initiators (see figure). Both efavirenz use (P<0.001) and # lifetime male sex partners (P=0.03) were associated with higher sCD14, but not KT ratio or sTNFR2. After additional adjustment for EFV use and # male sex partners, early ART initiators continued to have a mean 22% higher KT ratio (P=0.001), but not sCD14 (+7%, P=0.11), than HIV-negative controls. Conclusion: While PLWH initiating ART in the first 6 months of infection appear to restore near-normal levels of many immune activation markers that predict morbidity and mortality, the kynurenine pathway of tryptophan catabolism—a biomarker of indoleamine 2,3-dioxygenase-1 (IDO) activity—remains abnormal. As IDO confers adaptive immune defects and contributes to TB and cancer pathogenesis in animal models, the persistent induction of this pathway in PLWH with early ART initiation may plausibly contribute to persistent risks of these complications in this setting.

207 TREHALOSE INHIBITS HIV IN CD4+ LYMPHOCYTES AND MACROPHAGES BY 2 DISTINCT MECHANISMS Pratima Rawat 1 , Simson Hon 2 , Carmen Teodorof-Diedrich 1 , Stephen A. Spector 1 1 University of California San Diego, La Jolla, CA, USA, 2 University of California Davis, Davis, CA, USA Background: We previously showed that induction of autophagy through the inhibition of mTOR inhibits HIV replication. However, inhibition of mTOR may have cellular effects other than autophagy that could affect HIV infection. Here, we examined trehalose, a naturally occurring glucose mTOR-independent inducer of autophagy, to determine the effects on HIV replication. Methods: Human macrophages (MO) and CD4+ T lymphocytes (T-cells) treated with trehalose with or without HIV infection were assessed for cytotoxicity by LDH release assay and viral replication by p24 ELISA. Autophagy proteins were assessed by immunoblotting, qRT-PCR and fluorescence microscopy combined with assessment of LC3B lipidation. Viral entry was measured by intracellular p24. Data were analyzed using the Student paired T-test and one-way Anova. Results: Pretreatment of T-cells and MO with trehalose resulted in a dose dependent inhibition of HIV reaching ~90% inhibition at 100mM in both cell types without cytotoxicity. Trehalose induced autophagic flux in T-cells and MO as indicated by increased LC3B lipidation and LC3B-II accumulation following treatment with the autophagic flux inhibitor bafilomycin. Inhibition of HIV was at least partially dependent on induction of autophagy since knockdown of ATG5 by RNAi significantly increased p24 release by 42% and 47% in trehalose-treated HIV-infected T-cells and MO. Surprisingly, trehalose also decreased HIV entry into T-cells and MO in a dose dependent manner reaching ~80% reduction of intracellular virus in both cell types. The inhibition of viral entry was associated with ~3-fold decrease in CD4 expression (p<0.001) and CCR5 expression (p<0.001) in T-cells, and a 4.6-fold decrease in CD4 expression (p=0.002) but no significant change in CCR5 expression in MO. Conclusion: These data demonstrate that the naturally occurring sugar, trehalose, at doses safely achieved in humans inhibits HIV through two mechanisms: 1) decreased entry through the down-regulation of CCR5 in T-cells, and decreased CD4 expression in both T-cells and MO; and 2) degradation of intracellular HIV through the induction of mTOR independent autophagy. These findings demonstrate that cellular mechanisms can be modulated to inhibit HIV entry and intracellular replication using a naturally occurring, non-toxic sugar. Trehalose may be a useful adjunct in the maintenance of patients who achieve an HIV functional cure. 208 FECAL MICROVESICLES UNIQUELY INFLUENCE TRANSLOCATING BACTERIA AFTER SIV INFECTION Alexander Ortiz 1 , Jacob K.Flynn 1 , Jason Brenchley 1 NIH, Bethesda, MD, USA Background: Microbial translocation contributes to persistent inflammation in both treated and untreated HIV infection. Although translocation is due in part to a disintegration of the intestinal epithelial barrier, there is a bias towards the translocation of Proteobacteria. In murine models, epithelial-derived microvesicles (MVs) have been shown to influence bacterial gene expression and growth. We hypothesize that intestinal epithelial MVs biologically differ after HIV infection, which may contribute to biased translocation. Methods: We isolated fecal MVs from 12 healthy and 12 SIV-infected rhesus macaques (RM, Macaca mulatta) and co-cultured these MVs with isolates of translocated bacterial species. Viable bacteria that had translocated were isolated frommesenteric lymph nodes, livers, and spleens obtained from

Poster Abstracts

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CROI 2020