Gut inflammation in polytrauma and hemorrhagic shock

Severe injuries are frequently accompanied by hemorrhagic shock and harbor an increased risk for complications. Local or systemic inflammation after trauma/hemorrhage may lead to a leaky intestinal epithelial barrier and subsequent translocation of gut microbiota, potentially worsening outcome. To evaluate the extent with which trauma affects the gut microbiota composition, we performed a post hoc analysis of a murine model of polytrauma and hemorrhage. Four hours after injury, organs and plasma samples were collected, and the diversity and composition of the cecal microbiome were evaluated using 16S rRNA gene sequencing. Although cecal microbial composition was not found to be different between experimental groups, catecholamine support in shock animals resulted in higher numbers of distinct microbial features. We observed that the concentrations of pro-inflammatory mediators in plasma and intestinal tissue were associated with measures of microbial alpha- and beta-diversity and the presence of specific microbial drivers of inflammation. In conclusion, we found associations between measures of gut microbial alpha- and beta-diversity and the severity of systemic and local gut inflammation. Furthermore, our data suggest that four hours following injury is too early for development of global changes in the intestinal microbiome. Future investigations with increased temporal-spatial resolution are needed in order to fully elucidate the effects of trauma and shock on the gut microbiome, biological signatures of inflammation, and proximal and distal outcomes.