Epithelial myosin light chain kinase activation induces mucosal interleukin-13 expression to alter tight junction ion selectivity.
Intestinal barrier function is reduced in inflammatory bowel disease (IBD). Tumor necrosis factor (TNF) and interleukin (IL)-13, which are up-regulated in IBD, induce barrier defects that are associated with myosin light chain kinase (MLCK) activation and increased claudin-2 expression, respectively, in cultured intestinal epithelial monolayers. Here we report that these independent signaling pathways have distinct effects on tight junction barrier properties and interact in vivo. MLCK activation alters size selectivity to enhance paracellular flux of uncharged macromolecules without affecting charge selectivity and can be rapidly reversed by MLCK inhibition. In contrast, IL-13-dependent claudin-2 expression increases paracellular cation flux in vitro and in vivo without altering tight junction size selectivity but is unaffected by MLCK inhibition in vitro. In vivo, MLCK activation increases paracellular flux of uncharged macromolecules and also triggers IL-13 expression, claudin-2 synthesis, and increased paracellular cation flux. We conclude that reversible, MLCK-dependent permeability increases cause mucosal immune activation that, in turn, feeds back on the tight junction to establish long-lasting barrier defects. Interactions between these otherwise distinct tight junction regulatory pathways may contribute to IBD pathogenesis.
Weber
Christopher R
CR
Department of Pathology, The University of Chicago, Chicago, Illinois 60637, USA.
Raleigh
David R
DR
Su
Liping
L
Shen
Le
L
Sullivan
Erika A
EA
Wang
Yingmin
Y
Turner
Jerrold R
JR
D000818:Animals; D001483:Base Sequence; D018938:Caco-2 Cells; D002460:Cell Line; D057167:Claudins; D004789:Enzyme Activation; D006801:Humans; D015212:Inflammatory Bowel Diseases / Q000209:etiology; D018793:Interleukin-13 / Q000096:biosynthesis* / Q000494:pharmacology; D007413:Intestinal Mucosa / Q000187:drug effects / Q000276:immunology / Q000378:metabolism*; D017136:Ion Transport; D008565:Membrane Proteins / Q000037:antagonists & inhibitors / Q000096:biosynthesis / Q000235:genetics; D051379:Mice; D008822:Mice, Transgenic; D009219:Myosin-Light-Chain Kinase / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D034741:RNA, Small Interfering / Q000235:genetics; D011994:Recombinant Proteins / Q000037:antagonists & inhibitors / Q000096:biosynthesis / Q000235:genetics / Q000494:pharmacology; D019108:Tight Junctions / Q000378:metabolism; D046509:Tissue Culture Techniques; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology
C491875:CLDN2 protein, human; D057167:Claudins; C113371:Cldn2 protein, mouse; D018793:Interleukin-13; D008565:Membrane Proteins; D012333:RNA, Messenger; D034741:RNA, Small Interfering; D011994:Recombinant Proteins; D014409:Tumor Necrosis Factor-alpha; D009219:Myosin-Light-Chain Kinase