title: Coordinated epithelial NHE3 inhibition and barrier dysfunction are required for TNF-mediated diarrhea in vivo.
abstract: Acute T cell-mediated diarrhea is associated with increased mucosal expression of proinflammatory cytokines, including the TNF superfamily members TNF and LIGHT. While we have previously shown that epithelial barrier dysfunction induced by myosin light chain kinase (MLCK) is required for the development of diarrhea, MLCK inhibition does not completely restore water absorption. In contrast, although TNF-neutralizing antibodies completely restore water absorption after systemic T cell activation, barrier function is only partially corrected. This suggests that, while barrier dysfunction is critical, other processes must be involved in T cell-mediated diarrhea. To define these processes in vivo, we asked whether individual cytokines might regulate different events in T cell-mediated diarrhea. Both TNF and LIGHT caused MLCK-dependent barrier dysfunction. However, while TNF caused diarrhea, LIGHT enhanced intestinal water absorption. Moreover, TNF, but not LIGHT, inhibited Na+ absorption due to TNF-induced internalization of the brush border Na+/H+ exchanger NHE3. LIGHT did not cause NHE3 internalization. PKCalpha activation by TNF was responsible for NHE3 internalization, and pharmacological or genetic PKCalpha inhibition prevented NHE3 internalization, Na+ malabsorption, and diarrhea despite continued barrier dysfunction. These data demonstrate the necessity of coordinated Na+ malabsorption and barrier dysfunction in TNF-induced diarrhea and provide insight into mechanisms of intestinal water transport.
authors.affiliation: Department of Pathology, University of Chicago, Chicago, Illinois 60637, USA.
authors.forename: Daniel R
authors.initials: DR
authors.lastname: Clayburgh
authors.forename: Mark W
authors.initials: MW
authors.lastname: Musch
authors.forename: Michael
authors.initials: M
authors.lastname: Leitges
authors.forename: Yang-Xin
authors.initials: YX
authors.lastname: Fu
authors.forename: Jerrold R
authors.initials: JR
authors.lastname: Turner
mesh_terms: D000818:Animals; D000242:Cyclic AMP / Q000378:metabolism; D003967:Diarrhea / Q000139:chemically induced / Q000378:metabolism / Q000503:physiopathology*; D015870:Gene Expression / Q000235:genetics; D007408:Intestinal Absorption / Q000187:drug effects; D007413:Intestinal Mucosa / Q000187:drug effects / Q000378:metabolism / Q000503:physiopathology*; D007583:Jejunum / Q000187:drug effects / Q000378:metabolism / Q000503:physiopathology; D008213:Lymphocyte Activation / Q000502:physiology; D053259:Lymphotoxin beta Receptor / Q000235:genetics; D008565:Membrane Proteins / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008954:Models, Biological; D009219:Myosin-Light-Chain Kinase / Q000037:antagonists & inhibitors / Q000378:metabolism; D062793:Occludin; D010539:Permeability / Q000187:drug effects; D010766:Phosphorylation / Q000187:drug effects; D051571:Protein Kinase C-alpha / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D000074083:Sodium-Hydrogen Exchanger 3; D017923:Sodium-Hydrogen Exchangers / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D013601:T-Lymphocytes / Q000276:immunology; D019108:Tight Junctions / Q000187:drug effects / Q000378:metabolism; D053326:Tumor Necrosis Factor Ligand Superfamily Member 14 / Q000235:genetics; D014409:Tumor Necrosis Factor-alpha / Q000235:genetics / Q000378:metabolism* / Q000633:toxicity; D014867:Water / Q000378:metabolism
chemical_list: D053259:Lymphotoxin beta Receptor; D008565:Membrane Proteins; D062793:Occludin; C568986:Ocln protein, mouse; C000613386:Slc9a3 protein, mouse; D000074083:Sodium-Hydrogen Exchanger 3; D017923:Sodium-Hydrogen Exchangers; C505915:Tnfsf14 protein, mouse; D053326:Tumor Necrosis Factor Ligand Superfamily Member 14; D014409:Tumor Necrosis Factor-alpha; D014867:Water; D000242:Cyclic AMP; C496630:Prkca protein, mouse; D051571:Protein Kinase C-alpha; D009219:Myosin-Light-Chain Kinase