Salmonella enterica serovar Typhi exposure elicits ex vivo cell-type-specific epigenetic changes in human gut cells

Salmonella enterica serovar Typhi (S. Typhi) causes substantial morbidity and mortality worldwide, particularly among young children. Humans develop an array of mucosal immune responses following S. Typhi infection. Whereas the cellular mechanisms involved in S. Typhi infection have been intensively studied, very little is known about the early chromatin modifications occurring in the human gut microenvironment that influence downstream immune responses. To address this gap in knowledge, cells isolated from human terminal ileum exposed ex vivo to the wild-type S. Typhi strain were stained with a 33-metal-labeled antibody panel for mass cytometry analyses of the early chromatin modifications modulated by S. Typhi. We measured the cellular levels of 6 classes of histone modifications, and 1 histone variant in 11 major cell subsets (i.e., B, CD3+T, CD4+T, CD8+T, NK, TCR-gamma delta, Mucosal associated invariant (MAIT), and NKT cells as well as monocytes, macrophages, and epithelial cells). We found that arginine methylation might regulate the early-differentiation of effector-memory CD4+T-cells following exposure to S. Typhi. We also found S. Typhi-induced post-translational modifications in histone methylation and acetylation associated with epithelial cells, NKT, MAIT, TCR-gamma delta, Monocytes, and CD8+T-cells that are related to both gene activation and silencing.