843: Chorioamnionitis induced by intra-amniotic injection of IL-1, LPS, or ureaplasma parvum is associated with an altered microbiome in a primate model of inflammatory preterm birth


      Chorioamnionitis historically has been attributed to an ascending infection to the placenta and amniotic cavity. While identification of causative bacteria has been unyielding, our previous work examining the placental membrane microbiome in association with chorioamnionitis demonstrated the presence of both vaginal and oral commensal flora. Therefore, it’s plausible that alternative routes of microbial invasion may result in chorioamnionitis. Here, we aimed to examine the changes in the maternal and fetal microbiome that occur in a non-human primate model of inflammatory preterm birth.

      Study Design

      Under ultrasound guidance, sterile intra-amniotic injections (IA) of saline, lipopolysaccharide (LPS), IL-1β, or Ureaplasma parvum were given to preterm (126-132 days) Rhesus macaques (n=45). Fetuses were delivered within one week post-injection via cesarean. Oral swabs, stool, placental tissue, vaginal swabs, meconium and amniotic fluid were collected for DNA extraction using sterile technique. DNA was subjected to next-generation sequencing (16S and whole genome shotgun (WGS)) using negative controls. 16S sequencing was performed on the V1V3 and V3V5 region (454) or V1V3 (MiSeq) and data was analyzed with QIIME, LEfSe, and PICRUSt. WGS sequencing was performed on an Illumina HiSeq platform. Resulting sequences were filtered and analyzed using HUMAnN and MG-RAST. Integrative analysis was used to determine the relationships of the microbiome alterations in each cohort with relation to bacterial metabolic pathways.


      Unsurprisingly, intra-amniotic injection of LPS, IL-1β, nor U. parvum did not alter the maternal oral (p=0.5) or vaginal (p=0.7) microbiomes (Fig. A). However, injection of inflammatory inducers significantly altered (p=0.02) the beta diversity of the placental microbiome in comparison to control animals (Fig.A). Although no significant differences in taxonomy were apparent at the phylum level (Fig. B), we saw by inferred metabolic pathway analysis that glycosphingolipid metabolism was significantly altered (p > 0.05, Fig. C).


      This study demonstrates that inflammatory mediators significantly alter the placental microbiome in a clinically relevant primate model.
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