1099 LPS, IL-1β or U.parvum-induced chorioamnionitis in primates alters inflammation and the resident microbiome

Abstract

Historically, chorioamnionitis has been thought to result from ascending microbes driving inflammation of the chorioamnion, and is associated with preterm labor, perinatal morbidity, and adverse fetal outcomes. However, pathophysiology studies in humans suggest that it results from focal membrane colonization, and we and many others have shown that there is a sparse but present resident intrauterine microbiome. Recently, in some situations preterm chorioamnionitis can be “treated” and pregnancies can continue. Here, we aimed to determine if sterile intraamniotic injection (IA) of IL1β, LPS, or Ureaplasma parvum (UP) induced-chorioamnionitis is associated with alterations in the resident metagenomics composition and its function. Under ultrasound guidance, IA of saline, 1mg LPS (E. coli 055:B5), 10μg IL-1β, or 107 CFU UP were given to preterm (126-132 days) Rhesus macaques (n=54). Fetuses were delivered via sterile cesarean one-week post injection. Oral and vaginal swabs, stool, placental tissue, meconium and amniotic fluid were collected for DNA extraction. DNA was subjected to next-generation sequencing using appropriate contamination “kit” controls. 16S sequencing (n=211) was performed on the V1V3 (454) and was analyzed using QIIME2. WGS sequencing (n=196) was performed on Illumina HiSeq platform, and were filtered and analyzed using krakenuniq. IA injection of IL-1β or LPS induces histologic chorioamnionitis, with significant (p<0.01) increases in neutrophils and proinflammatory cytokines in amniotic fluid. Similar changes were not observed in parallel colon samples (Fig.1) indicating absence of systemic inflammation. These changes were accompanied by significant alterations in the beta diversity of the sparse placental and amniotic fluid microbiome, to control but not in the vaginal, oral or stool microbiomes (Fig.2). Chorioamnionitis is a localized phenomenon rather than a systemic infection, and the variations in amniotic and placental microbiome are consistent with localized inflammation and which alters the sparse but present resident microbiome.View Large Image Figure ViewerDownload Hi-res image Download (PPT)