Germ-free and Antibiotic-treated Mice are Highly Susceptible to Epithelial Injury in DSS Colitis Hernández Chirlaque, Cristina Aranda, Carlos J. Ocón, Borja Capitán Cañadas, Fermín Ortega González, Mercedes Suárez Ortega, María Dolores Zarzuelo Zurita, Antonio Sánchez De Medina López-Huertas, Fermín Martínez Augustín, María Olga Germ-free Mucosal Barrier function Microbiota Background and Aims: Intestinal microbiota is required to maintain immune homeostasis and intestinal barrier function. At the same time, intraluminal bacteria are considered to be involved in inflammatory bowel disease and are required for colitis induction in animal models, with the possible exception of dextran sulphate sodium [DSS] colitis. This study was carried out to ascertain the mechanism underlying the induction of colitis by DSS in the absence of bacteria. Methods: Conventional and germ-free [GF] Naval Medical Research Institute [NMRI] mice were used, plus conventional mice treated with an antibiotic cocktail to deplete the intestinal microbiota [‘pseudo-GF’ or PGF mice]. The differential response to DSS was assessed. Results: Conventional mice developed DSS-induced colitis normally, whereas GF mice showed only minimal inflammation [no colonic thickening, lower myeloperoxidase activity, IL-6, IL-17, TNF- α, and IFN-γ secretion by splenocytes and mesenteric cell cultures, etc.]. However, these mice suffered enhanced haemorrhage, epithelial injury and mortality as a consequence of a weakened intestinal barrier, as shown by lower occludin, claudin 4, TFF3, MUC3, and IL-22. In contrast, PGF mice had a relatively normal, albeit attenuated, inflammatory response, but were less prone to haemorrhage and epithelial injury than GF mice. This was correlated with an increased expression of IL-10 and Foxp3 and preservation barrier-related markers. Conclusions: We conclude that enteric bacteria are essential for the development of normal DSSinduced colitis. The absence of microbiota reduces DSS colonic inflammation dramatically but it also impairs barrier function, whereas subtotal microbiota depletion has intermediate effects at both levels. 2020-11-03T10:10:24Z 2020-11-03T10:10:24Z 2016-04-26 info:eu-repo/semantics/article Hernández-Chirlaque, C., Aranda, C. J., Ocón, B., Capitán-Cañadas, F., Ortega-González, M., Carrero, J. J., ... & Martínez-Augustin, O. (2016). Germ-free and antibiotic-treated mice are highly susceptible to epithelial injury in DSS colitis. Journal of Crohn's and Colitis, 10(11), 1324-1335. [doi:10.1093/ecco-jcc/jjw096] http://hdl.handle.net/10481/64011 10.1093/ecco-jcc/jjw096 eng http://creativecommons.org/licenses/by/3.0/es/ info:eu-repo/semantics/openAccess Atribución 3.0 España Oxford Univ Press