P016 Pregnancy in IBD: direct effect of sex-hormones on epithelial barrier function
van der Giessen J., van der Woude C., Peppelenbosch M., Fuhler G.
Erasmus Medical Center, Gastroenterology and Hepatology, Rotterdam, Netherlands
Inflammatory bowel disease (IBD) is a chronic inflammatory diseases of the gastrointestinal tract. The epithelial barrier is known to be compromised in active IBD. Previously we have demonstrated that some of the patients can stop maintenance therapy during pregnancy without a disease relapse. While pregnancy is an immune-tolerant state, the direct effect of pregnancy hormones on epithelial barrier cells is unknown but might play an important role in the favorable disease course during pregnancy. We aimed to study the direct effect of pregnancy hormones on barrier cells and their function.
The effect of progesterone and estrogen on intestinal epithelial cell barrier functions was investigated using human colonic adenocarcinoma cell lines (CACO2 and HCT116) as model system. Endoplasmic reticulum (ER) stress (earlier shown to induce epithelial cell death, barrier dysfunction and pro-inflammatory responses in IBD) was induced by treatment of cells with tunicamycin, followed by Western blot analysis of the ER stress marker GRP78. Epithelial barrier function was analyzed by transepithelial electrical resistance measurement (TEER), wound healing was determined by scratch assay, and cell viability was measured by MTT assays. IL-8 production by CACO2 cells was determined by enzyme-linked immuno sorbent assay (ELISA).
Progesterone and estrogen were able to reduce tunicamycin-induced ER stress in intestinal epithelial cells. This effect was dependent on the amount of ER stress induced and GRP78 reduction was most efficient in CACO2 cells (progesterone p=0.029, estrogen p=0.02). Scratch assays showed a faster wound closure in the presence of pregnancy hormones (estrogen and progesterone double treatment, p=0.034 for CACO2 cells and p=0.019 for HCT116 cells). This was not due to increased proliferation, as determined by MTT assay. Barrier function as determined by TEER measurement improved in the presence of estrogen and progesterone. IL-8 cytokine production by CACO2 cells increased in the presence of progesterone alone and in combination with estrogen.
Our study shows that estrogen and progesterone alleviate ER stress, increase IL-8 production, stimulate wound healing and increase barrier function of epithelial cells, thereby suggesting that in toto these pregnancy hormones can have beneficial effects on disease activity by positive modulatory action on the intestinal epithelial lining.