Mucosal IL-10 and TGF-β play crucial roles in preventing LPS-driven, IFN-γ–mediated epithelial damage in human colon explants
Anne Jarry, … , Marc G. Denis, Christian L. Laboisse
Anne Jarry, … , Marc G. Denis, Christian L. Laboisse
Published February 7, 2008
Citation Information: J Clin Invest. 2008;118(3):1132-1142. https://doi.org/10.1172/JCI32140.
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Research Article Gastroenterology

Mucosal IL-10 and TGF-β play crucial roles in preventing LPS-driven, IFN-γ–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-γ, TNF-α, and IL-17. Interestingly, TGF-β blockade also strongly induced IFN-γ production. In addition, the high levels of IFN-γ 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-γ 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-γ secretion. These findings demonstrate that IL-10 ablation leads to an endogenous IFN-γ–mediated inflammatory response via LPS from commensal bacteria in the human colonic mucosa. We also found that both IL-10 and TGF-β play crucial roles in maintaining human colonic mucosa homeostasis.

Authors

Anne Jarry, Céline Bossard, Chantal Bou-Hanna, Damien Masson, Eric Espaze, Marc G. Denis, Christian L. Laboisse

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Figure 2

Validation of IL-10 depletion in colonic mucosa explants by neutralizing antibodies: decrease in BLC3, an IL-10–inducible gene.

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Validation of IL-10 depletion in colonic mucosa explants by neutralizing...
(A) BCL3 immunohistochemistry on paraffin sections of human normal colonic mucosa. BCL3 was present in the nuclei of the majority of epithelial cells (brown) and in a few lamina propria mononuclear cells. Hematoxylin counterstaining. Original magnification, ×400. (B) Relative expression of BCL3 mRNA levels in 24- and 48-h mucosa explant cultures, incubated with anti–IL-10 neutralizing monoclonal antibodies (1 μg/ml) or with isotype mouse IgG1 (control). Total RNA was isolated from each sample and reverse transcribed. BCL3 and β-actin mRNAs were quantified by real-time PCR (see Methods), and the BCL3/β-actin ratio was calculated. Each point represents the mean of duplicate measurements for 1 sample. Horizontal lines represent mean values of 6 different experiments at 24 h and 5 experiments at 48 h.