IL-10 protects mouse intestinal epithelial cells from Fas-induced apoptosis via modulating Fas expression and altering caspase-8 and FLIP expression

• Published in: American journal of physiology: Gastrointestinal and liver physiology Vol. 291; no. 5; pp. G820 - G829
• Main Authors: Bharhani, Mantej S, Borojevic, Rajka, Basak, Shibesh, Ho, Edwin, Zhou, Pengfei, Croitoru, Kenneth
• Format: Journal Article
• Language: English
• Published: United States American Physiological Society 01.11.2006
• Subjects: Animals; Annexin A5 - metabolism; Antibodies, Monoclonal; Apoptosis; Apoptosis - drug effects; Blotting, Western; CASP8 and FADD-Like Apoptosis Regulating Protein - genetics; Caspase 8 - biosynthesis; Caspase 8 - genetics; Cell culture; Cytokines; Cytokines - metabolism; Digestive system; Dose-Response Relationship, Drug; Electrophoresis, Polyacrylamide Gel; Epithelial Cells - drug effects; fas Receptor - biosynthesis; fas Receptor - genetics; fas Receptor - physiology; Interferon-gamma - pharmacology; Interleukin-10 - pharmacology; Intestinal Mucosa - cytology; Intestinal Mucosa - drug effects; Mice; Mice, Inbred C3H; Monoclonal antibodies; Rodents; Tissues; Tumor Necrosis Factor-alpha - pharmacology; Up-Regulation - drug effects
• ISSN: 0193-1857; 1522-1547
• DOI: 10.1152/ajpgi.00438.2005

We have previously shown that the absence of Fas/Fas ligand significantly reduced tissue damage and intestinal epithelial cell (IEC) apoptosis in an in vivo model of T cell-mediated enteropathy. This enteropathy was more severe in IL-10-deficient mice, and this was associated with increased serum levels of IFN-gamma and TNF-alpha and an increase in Fas expression on IECs. In this study, we investigated the potential of IL-10 to directly influence Fas expression and Fas-induced IEC apoptosis. Mouse intestinal epithelial cell lines MODE-K and IEC4.1 were cultured with IFN-gamma, TNF-alpha, or anti-Fas monoclonal antibody (mAb) in the presence or absence of IL-10. Fas expression and apoptosis were determined by FACScan analysis of phycoerythrin-anti-Fas mAb staining and annexin V staining, respectively. Treatment with a combination of IFN-gamma and TNF-alpha induced significant apoptosis. Anti-Fas mAb alone did not induce much apoptosis unless cells were pretreated with IFN-gamma and TNF-alpha. These IECs constitutively expressed low levels of Fas, which significantly increased by preincubation of the cells with IFN-gamma and TNF-alpha. Treatment with cytokine or cytokine plus anti-Fas mAb increased apoptosis, which correlated with a decreased Fas-associated death domain IL-1-converting enzyme-like inhibitory protein (FLIP) level, increased caspase-8 activity, and subsequently increased caspase-3 activity. IL-10 diminished both cytokine- and anti-Fas mAb-induced apoptosis, and this was correlated with decreased cytokine-induced Fas expression, increased FLIP, and decreased caspase-8 and caspase-3 activity. In conclusion, IL-10 modulated cytokine induction of Fas expression on IEC cell lines and regulated IEC susceptibility to TNF-alpha, IFN-gamma, and Fas-mediated apoptosis. These findings suggest that IL-10 directly modulates IEC responses to T cell-mediated apoptotic signals.