Background and Aims The MUC13 transmembrane mucin is highly and constitutively expressed in the small and large intestine. Although MUC13 polymorphisms have been associated with human inflammatory bowel diseases and susceptibility to Escherichia coli infection in pigs, the biological functions of MUC13 are unknown. This study aimed to explore whether MUC13 modulates intestinal inflammation.
Methods Muc13−/− mice were generated, phenotyped and challenged with the colitis-inducing agent, dextran sodium sulphate (DSS). Colitis was assessed by clinical symptoms and intestinal histopathology. Intestinal epithelial cell apoptosis and proliferation, macrophage infiltration and cytokine production were also quantified. Apoptosis of human LS513 intestinal epithelial cells in response to apoptotic agents, including DSS, was also measured, following knockdown of MUC13 with siRNA.
Results Muc13−/− mice were viable, fertile and developed normally, with no spontaneous intestinal pathology except mild focal neutrophilic inflammation in the small and large intestines of old mice. In response to DSS challenge, Muc13−/− mice developed more severe acute colitis, as reflected by increased weight loss, rectal bleeding, diarrhoea and histological colitis scores compared with wild-type mice. Increased numbers of F4/80+ macrophages in inflamed mucosa of Muc13−/− mice were accompanied by increased expression of intestinal IL-1β and TNFα mRNA. Muc13−/− mice had significantly increased intestinal epithelial cell apoptosis within 3 days of DSS exposure. LS513 cells were more susceptible to DSS, actinomycin-D, ultraviolet irradiation and TRAIL-induced apoptosis when MUC13 was knocked down by siRNA.
Conclusions These novel findings indicate a protective role for Muc13 in the colonic epithelium by inhibiting toxin-induced apoptosis and have important implications for intestinal infections, inflammatory diseases and the development of intestinal cancer.
- epithelial barrier
- gut inflammation
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RL, PLJ and SKL contributed equally to this study.
Funding Supported by NHMRC project grant 543704, MAM is supported by a NHMRC Senior Research Fellowship, THJF is supported by a NHMRC Practitioner Fellowship. SKL is supported by the Swedish Research Council (Vetenskapsrådet), PLJ is supported by a Queensland Government Smart Futures Fellowship.
Competing interests None.
Patient consent Obtained.
Ethics approval This study was conducted with the approval of the Mater Health Services Health and Research Ethics Committee.
Provenance and peer review Not commissioned; externally peer reviewed.