Clcn5 knockout mice exhibit novel immunomodulatory effects and are more susceptible to dextran sulfate sodium-induced colitis.
Although the intracellular Cl(-)/H(+) exchanger Clc-5 is expressed in apical intestinal endocytic compartments, its pathophysiological role in the gastrointestinal tract is unknown. In light of recent findings that CLC-5 is downregulated in active ulcerative colitis (UC), we tested the hypothesis that loss of CLC-5 modulates the immune response, thereby inducing susceptibility to UC. Acute dextran sulfate sodium (DSS) colitis was induced in Clcn5 knockout (KO) and wild-type (WT) mice. Colitis, monitored by disease activity index, histological activity index, and myeloperoxidase activity were significantly elevated in DSS-induced Clcn5 KO mice compared with those in WT mice. Comprehensive serum multiplex cytokine profiling demonstrated a heightened Th1-Th17 profile (increased TNF-alpha, IL-6, and IL-17) in DSS-induced Clcn5 KO mice compared with that in WT DSS colitis mice. Interestingly, Clcn5 KO mice maintained on a high vitamin D diet attenuated DSS-induced colitis. Immunofluorescence and Western blot analyses of colonic mucosa validated the systemic cytokine patterns and further revealed enhanced activation of the NF-kappaB pathway in DSS-induced Clcn5 KO mice compared with those in WT mice. Intriguingly, high baseline levels of IL-6 and phospho-IkappaB were observed in Clcn5 KO mice, suggesting a novel immunopathogenic role for the functional defects that result from the loss of Clc-5. Our studies demonstrate that the loss of Clc-5 1) exhibits IL-6-mediated immunopathogenesis, 2) significantly exacerbated DSS-induced colitis, which is influenced by dietary factors, including vitamin D, and 3) portrays distinct NF-kappaB-modulated Th1-Th17 immune dysregulation, implying a role for CLC-5 in the immunopathogenesis of UC.
Alex
Philip
P
Division of Gastroenterology, Department of Medicine, Johns Hopkins University, Baltimore, MD 21205, USA.
Ye
Mei
M
Zachos
Nicholas C
NC
Sipes
Jennifer
J
Nguyen
Thuan
T
Suhodrev
Maxim
M
Gonzales
Liberty
L
Arora
Zubin
Z
Zhang
Ting
T
Centola
Michael
M
Guggino
Sandra E
SE
Li
Xuhang
X
D000818:Animals; D015153:Blotting, Western; D018118:Chloride Channels / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D003092:Colitis / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D016207:Cytokines / Q000096:biosynthesis / Q000276:immunology; D016264:Dextran Sulfate / Q000633:toxicity; D005455:Fluorescent Antibody Technique; D020381:Interleukin-17 / Q000276:immunology / Q000378:metabolism; D015850:Interleukin-6 / Q000276:immunology / Q000378:metabolism; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D016328:NF-kappa B / Q000276:immunology / Q000378:metabolism; D018417:Th1 Cells / Q000276:immunology / Q000378:metabolism; D014807:Vitamin D / Q000494:pharmacology
C097503:CLC-5 chloride channel; D018118:Chloride Channels; D016207:Cytokines; D020381:Interleukin-17; D015850:Interleukin-6; D016328:NF-kappa B; D014807:Vitamin D; D016264:Dextran Sulfate