Maternal infection promotes offspring tissue-specific immune fitness

The mammalian immune system has evolved in the face of microbial exposure. How maternal infection experienced at distinct developmental stages shapes the offspring immune system remains poorly understood. Here we show that during pregnancy, maternally restricted infection can have permanent and tissue-specific impacts on offspring immunity. Mechanistically, maternal IL-6 produced in response to infection can specifically and directly impose epigenetic changes on fetal intestinal epithelial cells. Such imprinting is associated with long-lasting impacts on intestinal immune homeostasis, characterized by enhanced tonic immunity to the microbiota and heightened Th17 responses within the gut, but not at other barrier sites. Furthermore, the offspring from IL-6-exposed dams developed enhanced protective immunity to gastrointestinal infection. Together, this work demonstrates that maternal infection experienced during pregnancy can be coopted by the fetus to promote long-term tissue-specific fitness. Summary sentence Infection-induced maternal IL-6 impacts offspring epithelial cells, resulting in heightened immunity to the microbiota and pathogens.