Interleukin-10 blocked endoplasmic reticulum stress in intestinal epithelial cells: impact on chronic inflammation.
OBJECTIVE
The initiation of endoplasmic reticulum (ER)-mediated stress responses in intestinal epithelial cells (IEC) may contribute to the pathogenesis of chronic intestinal inflammation. The aim of the study was to use functional epithelial cell proteomics to characterize anti-inflammatory mechanisms of interleukin 10 (IL-10).


METHODS
Primary IEC were isolated from Enterococcus faecalis-monoassociated IL-10-deficient (IL-10-/-) and wild-type mice to perform 2D-gel sodium-dodecyl-sulfate polyacrylamide gel electrophoresis and matrix-assisted laser desorption/ionization-time of flight mass spectrometry. In addition, IEC from 6 patients with active Crohn's disease, ulcerative colitis, and sigmoid diverticulitis as well as noninflamed controls were purified. Molecular protective mechanisms of IL-10 were characterized in tumor necrosis factor (TNF)-stimulated IL-10 receptor (IL-10R) reconstituted epithelial cells.


RESULTS
Primary IEC from IL-10-/- mice as well as inflammatory bowel disease patients revealed increased expression levels of the glucose-regulated ER stress protein (grp)-78 under conditions of chronic inflammation. Consistent with the observation that TNF induced ER stress responses through grp-78 redistribution from the ER lumen to the cytoplasmic IkappaB kinase complex, grp-78 knockdown completely abolished TNF-induced nuclear factor-kappaB RelA phosphorylation in epithelial cell cultures. Interestingly, IL-10 inhibited grp-78 protein and messenger RNA expression in IL-10R reconstituted IEC. Chromatin immunoprecipitation analysis and immunofluorescence microscopy revealed that IL-10-mediated p38 signaling inhibited TNF-induced recruitment of the ER-derived activating transcription factor (ATF)-6 to the grp-78 promoter likely through the blockade of ATF-6 nuclear translocation.


CONCLUSIONS
Primary IEC from inflamed IL-10-/- mice and inflammatory bowel disease patients revealed activated ER stress responses in the intestinal epithelium. IL-10 inhibits inflammation-induced ER stress response mechanisms by modulating ATF-6 nuclear recruitment to the grp-78 gene promoter.
Shkoda
Anna
A
Else-Kroener-Fresenius Center for Experimental Nutritional Medicine, Technical University of Munich, 85350 Freising-Weihenstephan, Germany.
Ruiz
Pedro A
PA
Daniel
Hannelore
H
Kim
Sandra C
SC
Rogler
Gerhard
G
Sartor
R Balfour
RB
Haller
Dirk
D
D051702:Activating Transcription Factor 6 / Q000378:metabolism; D000818:Animals; D002467:Cell Nucleus / Q000378:metabolism; D002478:Cells, Cultured; D002908:Chronic Disease; D004721:Endoplasmic Reticulum / Q000276:immunology / Q000378:metabolism*; D000091342:Endoplasmic Reticulum Chaperone BiP; D013293:Enterococcus faecalis; D004847:Epithelial Cells / Q000166:cytology / Q000276:immunology; D016908:Gram-Positive Bacterial Infections / Q000276:immunology / Q000378:metabolism; D006360:Heat-Shock Proteins / Q000235:genetics / Q000378:metabolism; D006801:Humans; D015212:Inflammatory Bowel Diseases / Q000276:immunology* / Q000378:metabolism / Q000382:microbiology; D016753:Interleukin-10 / Q000235:genetics / Q000276:immunology* / Q000378:metabolism; D007413:Intestinal Mucosa / Q000166:cytology / Q000276:immunology* / Q000473:pathology; D051379:Mice; D008815:Mice, Inbred Strains; D008817:Mice, Mutant Strains; D018832:Molecular Chaperones / Q000235:genetics / Q000378:metabolism; D011401:Promoter Regions, Genetic / Q000276:immunology; D040901:Proteomics; D015398:Signal Transduction / Q000276:immunology; D051996:Transcription Factor RelA / Q000378:metabolism; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism
D051702:Activating Transcription Factor 6; C497112:Atf6 protein, mouse; D000091342:Endoplasmic Reticulum Chaperone BiP; D006360:Heat-Shock Proteins; D018832:Molecular Chaperones; C498144:Rela protein, mouse; D051996:Transcription Factor RelA; D014409:Tumor Necrosis Factor-alpha; D016753:Interleukin-10; D048051:p38 Mitogen-Activated Protein Kinases