title: Mucosal IL-10 and TGF-beta play crucial roles in preventing LPS-driven, IFN-gamma-mediated epithelial damage in human colon explants.
abstract: IL-10 is an immunomodulatory cytokine that plays an obligate role in preventing spontaneous enterocolitis in mice. However, little is known about IL-10 function in the human intestinal mucosa. We showed here that IL-10 was constitutively expressed and secreted by the human normal colonic mucosa, including epithelial cells. Depletion of IL-10 in mucosal explants induced both downregulation of the IL-10-inducible, immunosuppressive gene BCL3 and upregulation of IFN-gamma, TNF-alpha, and IL-17. Interestingly, TGF-beta blockade also strongly induced IFN-gamma production. In addition, the high levels of IFN-gamma produced upon IL-10 depletion were responsible for surface epithelium damage and crypt loss, mainly by apoptosis. Polymyxin B, used as a scavenger of endogenous LPS, abolished both IFN-gamma production and epithelial barrier disruption. Finally, adding a commensal bacteria strain to mucosa explant cultures depleted of both IL-10 and LPS reproduced the ability of endogenous LPS to induce IFN-gamma secretion. These findings demonstrate that IL-10 ablation leads to an endogenous IFN-gamma-mediated inflammatory response via LPS from commensal bacteria in the human colonic mucosa. We also found that both IL-10 and TGF-beta play crucial roles in maintaining human colonic mucosa homeostasis.
authors.affiliation: INSERM U539, Nantes, France. ajarry@univ-nantes.fr
authors.forename: Anne
authors.initials: A
authors.lastname: Jarry
authors.forename: Céline
authors.initials: C
authors.lastname: Bossard
authors.forename: Chantal
authors.initials: C
authors.lastname: Bou-Hanna
authors.forename: Damien
authors.initials: D
authors.lastname: Masson
authors.forename: Eric
authors.initials: E
authors.lastname: Espaze
authors.forename: Marc G
authors.initials: MG
authors.lastname: Denis
authors.forename: Christian L
authors.initials: CL
authors.lastname: Laboisse
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003106:Colon / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D005260:Female; D006801:Humans; D007371:Interferon-gamma / Q000502:physiology*; D016753:Interleukin-10 / Q000502:physiology*; D007413:Intestinal Mucosa / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D008070:Lipopolysaccharides / Q000037:antagonists & inhibitors / Q000633:toxicity*; D008297:Male; D008875:Middle Aged; D016212:Transforming Growth Factor beta / Q000502:physiology*
chemical_list: D008070:Lipopolysaccharides; D016212:Transforming Growth Factor beta; D016753:Interleukin-10; D007371:Interferon-gamma