Endocytosis of commensal antigens by intestinal epithelial cells regulates mucosal T cell homeostasis

Science. 2019 Mar 8;363(6431):eaat4042. doi: 10.1126/science.aat4042.

Abstract

Commensal bacteria influence host physiology, without invading host tissues. We show that proteins from segmented filamentous bacteria (SFB) are transferred into intestinal epithelial cells (IECs) through adhesion-directed endocytosis that is distinct from the clathrin-dependent endocytosis of invasive pathogens. This process transfers microbial cell wall-associated proteins, including an antigen that stimulates mucosal T helper 17 (TH17) cell differentiation, into the cytosol of IECs in a cell division control protein 42 homolog (CDC42)-dependent manner. Removal of CDC42 activity in vivo led to disruption of endocytosis induced by SFB and decreased epithelial antigen acquisition, with consequent loss of mucosal TH17 cells. Our findings demonstrate direct communication between a resident gut microbe and the host and show that under physiological conditions, IECs acquire antigens from commensal bacteria for generation of T cell responses to the resident microbiota.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Antigens, Bacterial / immunology*
  • Bacteria / immunology
  • Endocytosis / genetics
  • Endocytosis / immunology*
  • Gastrointestinal Microbiome / immunology*
  • Homeostasis / genetics
  • Host Microbial Interactions / immunology*
  • Intestinal Mucosa / immunology*
  • Intraepithelial Lymphocytes / immunology*
  • Lymphocyte Activation
  • Mice, Inbred BALB C
  • Mice, Inbred C57BL
  • Mice, Inbred NOD
  • Symbiosis
  • Th17 Cells / immunology*
  • cdc42 GTP-Binding Protein / genetics
  • cdc42 GTP-Binding Protein / physiology

Substances

  • Antigens, Bacterial
  • Cdc42 protein, mouse
  • cdc42 GTP-Binding Protein