Abstract: The Toll-like receptor/MyD88 signaling pathway has been shown to mediate protective functions during intestinal exposure to various noxious events. The goal of this study was to define the role of bacteria and MyD88 signaling in intestinal response to damage using an ischemia–reperfusion (I/R)-induced injury model. We showed that conventionalized mice displayed a better outcome to I/R-induced injury than germ-free mice (3.8 ± 1.98 vs. 11.8 ± 1.83, P < 0.05). However, mice with intestinal epithelial cell (IEC)-specific deletion of Myd88 (Myd88IEC−/−) were protected from I/R-induced injury compared with Myd88f/f control mice. Myd88IEC−/− mice also displayed a significantly reduced bacterial translocation (∼85%) into lymph nodes compared with Myd88f/f mice. Expression of ccl2 and cxcl1 mRNA was significantly reduced (85% and 62%, respectively) in intestinal tissue of Myd88IEC−/− mice compared with Myd88f/f mice, which associated with a reduced number of myeloperoxidase-positive cells in intestinal tissues of I/R-exposed Myd88IEC−/− mice. Immunohistochemistry analysis showed a reduced IgA deposition and complement staining in ischemic tissue of Myd88IEC−/− mice compared with Myd88f/f mice. These findings suggest that I/R-induced intestinal injury involves IEC-derived MyD88 signaling leading to increased IgA deposition/degradation, and complement activation in conjunction with an influx of neutrophils mediated by chemokine production.
Article first published online 17 October 2013
*Departments of Medicine, Microbiology and Immunology, and Pharmacology, University of North Carolina, Chapel Hill, North Carolina; and
†Department of Medicine and Department of Infectious Diseases & Pathology, University of Florida, Gainesville, Florida.
Reprints: Christian Jobin, PhD, Department of Medicine, University of Florida, Gainesville, FL 32608 (e-mail: firstname.lastname@example.org).
Supported by National Institutes of Health grants R01DK047700 and R01DK073338 (C.J.) and Crohn's and Colitis Foundation of America (M.M.). The funders had no role in the study design, data collection and analysis, decision to publish, or preparation of the article.
The authors have no conflicts of interest to disclose.
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Received August 13, 2013
Accepted September 11, 2013