TY - JOUR
T1 - TNFR2 activates mlck-dependent tight junction dysregulation to cause apoptosis-mediated barrier loss and experimental colitis
AU - Su, Liping
AU - Nalle, Sam C.
AU - Shen, Le
AU - Turner, Emily S.
AU - Singh, Gurminder
AU - Breskin, Lydia A.
AU - Khramtsova, Ekaterina A.
AU - Khramtsova, Galina
AU - Tsai, Pei Yun
AU - Fu, Yang Xin
AU - Abraham, Clara
AU - Turner, Jerrold R.
N1 - Funding Information:
Funding Supported by the National Institutes of Health ( R01DK61931 , R01DK68271 , P01D067887 , P30DK042086 , P30CA14599 , UL1RR024999 , T32HL007237 , K01DK09238 , R01DK77905 ), Department of Defense ( W81XWH-09-1-0341 ), the Broad Medical Research Foundation ( IBD-022 ), the Crohn’s and Colitis Foundation of America , the Chicago Biomedical Consortium (with support from The Searle Funds at The Chicago Community Trust ), and the National Natural Science Foundation of China ( 30900670, 81272749 ).
PY - 2013/8
Y1 - 2013/8
N2 - Background & Aims Tight junction dysregulation and epithelial damage contribute to barrier loss in patients with inflammatory bowel disease. However, the mechanisms that regulate these processes and their relative contributions to disease pathogenesis are not completely understood. We investigated these processes using colitis models in mice. Methods We induced colitis by adoptive transfer of CD4+CD45RBhi cells or administration of dextran sulfate sodium to mice, including those deficient in tumor necrosis factor receptor (TNFR) 1, TNFR2, or the long isoform of myosin light chain kinase (MLCK). Intestinal tissues and isolated epithelial cells were analyzed by immunoblot, immunofluorescence, enzyme-linked immunosorbent assay, and real-time polymerase chain reaction assays. Results Induction of immune-mediated colitis by CD4+CD45RBhi adoptive transfer increased intestinal permeability, epithelial expression of claudin-2, the long isoform of MLCK, and TNFR2 (but not TNFR1) and phosphorylation of the myosin II light chain. Long MLCK upregulation, myosin II light chain phosphorylation, barrier loss, and weight loss were attenuated in TNFR2-/-, but not TNFR1 -/-, recipients of wild-type CD4+CD45RBhi cells. Similarly, long MLCK-/- mice had limited increases in myosin II light chain phosphorylation, claudin-2 expression, and intestinal permeability and delayed onset of adoptive transfer-induced colitis. However, coincident with onset of epithelial apoptosis, long MLCK-/- mice ultimately developed colitis. This indicates that disease progresses via apoptosis in the absence of MLCK-dependent tight junction regulation. In support of this conclusion, long MLCK-/- mice were not protected from epithelial apoptosis-mediated, damage-dependent dextran sulfate sodium colitis. Conclusions In immune-mediated inflammatory bowel disease models, TNFR2 signaling increases long MLCK expression, resulting in tight junction dysregulation, barrier loss, and induction of colitis. At advanced stages, colitis progresses by apoptosis and mucosal damage that result in tight junction- and MLCK-independent barrier loss. Therefore, barrier loss in immune-mediated colitis occurs via two temporally and morphologically distinct mechanisms. Differential targeting of these mechanisms can lead to improved inflammatory bowel disease therapies.
AB - Background & Aims Tight junction dysregulation and epithelial damage contribute to barrier loss in patients with inflammatory bowel disease. However, the mechanisms that regulate these processes and their relative contributions to disease pathogenesis are not completely understood. We investigated these processes using colitis models in mice. Methods We induced colitis by adoptive transfer of CD4+CD45RBhi cells or administration of dextran sulfate sodium to mice, including those deficient in tumor necrosis factor receptor (TNFR) 1, TNFR2, or the long isoform of myosin light chain kinase (MLCK). Intestinal tissues and isolated epithelial cells were analyzed by immunoblot, immunofluorescence, enzyme-linked immunosorbent assay, and real-time polymerase chain reaction assays. Results Induction of immune-mediated colitis by CD4+CD45RBhi adoptive transfer increased intestinal permeability, epithelial expression of claudin-2, the long isoform of MLCK, and TNFR2 (but not TNFR1) and phosphorylation of the myosin II light chain. Long MLCK upregulation, myosin II light chain phosphorylation, barrier loss, and weight loss were attenuated in TNFR2-/-, but not TNFR1 -/-, recipients of wild-type CD4+CD45RBhi cells. Similarly, long MLCK-/- mice had limited increases in myosin II light chain phosphorylation, claudin-2 expression, and intestinal permeability and delayed onset of adoptive transfer-induced colitis. However, coincident with onset of epithelial apoptosis, long MLCK-/- mice ultimately developed colitis. This indicates that disease progresses via apoptosis in the absence of MLCK-dependent tight junction regulation. In support of this conclusion, long MLCK-/- mice were not protected from epithelial apoptosis-mediated, damage-dependent dextran sulfate sodium colitis. Conclusions In immune-mediated inflammatory bowel disease models, TNFR2 signaling increases long MLCK expression, resulting in tight junction dysregulation, barrier loss, and induction of colitis. At advanced stages, colitis progresses by apoptosis and mucosal damage that result in tight junction- and MLCK-independent barrier loss. Therefore, barrier loss in immune-mediated colitis occurs via two temporally and morphologically distinct mechanisms. Differential targeting of these mechanisms can lead to improved inflammatory bowel disease therapies.
KW - Inflammatory Bowel Disease Epithelial Barrier Intestinal Permeability Disease Progression
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U2 - 10.1053/j.gastro.2013.04.011
DO - 10.1053/j.gastro.2013.04.011
M3 - Article
C2 - 23619146
AN - SCOPUS:84880611949
SN - 0016-5085
VL - 145
SP - 407
EP - 415
JO - Gastroenterology
JF - Gastroenterology
IS - 2
ER -