Intraamniotic LPS, IL-1β or U.parvum Injection is Uniquely Associated with Altered Intrauterine Microbiome in Primates

Chorioamnionitis is associated with just over 1/3 of PTBs. Historically, it is thought to be a result of ascending infection with relatively low-virulence organisms. However, pathophysiology studies in humans suggest that it results from focal membrane colonization. Here, we aimed to determine if sterile intraamniotic injection (IAI) of IL1β, LPS, or Ureaplasma parvum (UP) induced-chorioamnionitis in primates is associated with alterations in the resident metagenomic composition and its function. Under ultrasound guidance, IAI 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=40) (Fig 1A). Oral and vaginal swabs, stool, placental tissue, meconium, and amniotic fluid were collected for DNA extraction after cesarean delivery of fetuses. DNA was subjected to NextGen sequencing using appropriate contamination “kit” controls, and established computational pipelines were used for analyses. IL-1β or LPS-induced histologic chorioamnionitis co-occurred with significant (p < 0.01) increases in neutrophils and proinflammatory cytokines in amniotic fluid (AF) or the chorion/amnion, but not colon. Intra-amniotic inflammation was not accompanied by altered alpha diversity of the sparse placental and AF microbiome (Fig 1B) but was seen with alterations in the sparse and low-abundant metagenomic community of largely commensal organisms in the placenta (Fig 2A) or AF, but not the maternal gut (Fig 2B), nor oral or vaginal samples. Chorioamnionitis is a localized infection rather than a systemic infection, with variations observed in amniotic and placental microbiome due to treatments. This also reinstates the notion of sparse but present resident microbiome in amniotic fluid.View Large Image Figure ViewerDownload Hi-res image Download (PPT)