Epithelial myosin light chain kinase-dependent barrier dysfunction mediates T cell activation-induced diarrhea in vivo

J Clin Invest. 2005 Oct;115(10):2702-15. doi: 10.1172/JCI24970. Epub 2005 Sep 22.


Disruption of the intestinal epithelial barrier occurs in many intestinal diseases, but neither the mechanisms nor the contribution of barrier dysfunction to disease pathogenesis have been defined. We utilized a murine model of T cell-mediated acute diarrhea to investigate the role of the epithelial barrier in diarrheal disease. We show that epithelial barrier dysfunction is required for the development of diarrhea. This diarrhea is characterized by reversal of net water flux, from absorption to secretion; increased leak of serum protein into the intestinal lumen; and altered tight junction structure. Phosphorylation of epithelial myosin II regulatory light chain (MLC), which has been correlated with tight junction regulation in vitro, increased abruptly after T cell activation and coincided with the development of diarrhea. Genetic knockout of long myosin light chain kinase (MLCK) or treatment of wild-type mice with a highly specific peptide MLCK inhibitor prevented epithelial MLC phosphorylation, tight junction disruption, protein leak, and diarrhea following T cell activation. These data show that epithelial MLCK is essential for intestinal barrier dysfunction and that this barrier dysfunction is critical to pathogenesis of diarrheal disease. The data also indicate that inhibition of epithelial MLCK may be an effective non-immunosuppressive therapy for treatment of immune-mediated intestinal disease.

Publication types

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

MeSH terms

  • Animals
  • Autoimmune Diseases / chemically induced
  • Autoimmune Diseases / metabolism*
  • Autoimmune Diseases / pathology
  • Blood Proteins / metabolism
  • Diarrhea / chemically induced
  • Diarrhea / metabolism*
  • Diarrhea / pathology
  • Intestinal Mucosa / metabolism*
  • Intestinal Mucosa / ultrastructure
  • Lymphocyte Activation* / drug effects
  • Mice
  • Mice, Knockout
  • Myosin Light Chains / metabolism
  • Myosin-Light-Chain Kinase / genetics
  • Myosin-Light-Chain Kinase / metabolism*
  • T-Lymphocytes / metabolism*
  • T-Lymphocytes / ultrastructure
  • Tight Junctions / metabolism
  • Tight Junctions / ultrastructure
  • Water / metabolism


  • Blood Proteins
  • Myosin Light Chains
  • Water
  • Myosin-Light-Chain Kinase