Tu1247 The Relationship Between Cystic Fibrosis Epithelial Cells and Intestinal Inflammation -Evolving Mechanisms of the Lung-Gut Axis

Background: Cystic fibrosis (CF) is the most common autosomal recessive disorder in the Western world primarily affecting the lung and digestive organs. Accumulating evidence suggests a potential role for the lung-gut axis in the pathogenesis of gut inflammation in CF. Despite this, the influence of the CF lung on gut health is poorly investigated. Recent studies have indicated that modulating lung inflammation by targeting the cycloxygenase pathway and its major metabolite prostaglandin E2 (PGE2) can slow the progression of lung disease in people with CF. Increased PGE2 synthesis is associated with inflammatory disease and can regulate immune responses during bacterial pathogenesis. Aim: To investigate if pro-inflammatory changes in the lung in turn affect the gut epithelium. Methods: Human bronchial epithelial cells (16HBEo-) and CF bronchial epithelial cells (δF508 homozygote, CFBE41o-) were seeded at 2x105 cells/ml. Cells were treated with PGE2 and cell supernatant was harvested. HT29 colon epithelial cells were seeded at 2x105 cells/ml and stimulated with the supernatant of untreated or PGE2 treated cell supernatant. Cell proliferation of HT29 cells in vitro was assessed by resazurin reduction and changes in cytokine levels of IL-6, IL-8 and TNFα were detected by ELISA. Results: Supernatant from CF lung cells augmented IL-6, IL-8 and TNFα production by HT29 cells. Secretion of IL-6, IL-8 and TNFα by HT29 cells incubated with CFBE41o- CF cell supernatant was significantly increased 2.7 fold, 1.8 fold and 1.4 fold respectively, relative to HT29 cells cultured in normal bronchial 16HBEo- epithelial cells. This increase in IL-6, IL-8 and TNFα expression by HT29 cells was further augmented upon culture of the cells in PGE2-treated CF cell supernatant relative to PGE2-treated normal bronchial epithelial cells. No significant change in cell proliferation of HT29 intestinal epithelium cells was detected. Conclusion: Our results demonstrate that inflammatory changes in the CF lung can increase cytokine production in the gut. This mechanism may regulate intestinal inflammation independent of active CF lung infection.