Studies on Functional Differentiation of Small Intestinal Epithelial Cells

ABSTRACT

PURPOSE: We investigated compounds from food sources given to children that may induce the differentiation of small intestinal epithelial cells in order to signal pathways that induce the prolif eration and differentiation of small intestinal epithelial cells. METHODS: We analyzed small intestinal epithelial cell differentiation using in vitro IEC-6 cells model. The growth curve of IEC-6 cells was obtained by standard MTT assay. Alkaline phospha tase(ALP) activities were determined using the paranitrophenol colorimetric assay for the differ entiation of IEC-6 cells. We did ALP and Brdu double-staining of cultured IEC-6 cells to distin guish between differentiation and proliferation, and investigated compounds' potential for inducing differentiation of small intestinal epithelial cells and protein kinase signal pathway. RESULTS: The calcium ion was essential for the differentiation of IEC-6 cells. Retinol and retinoic acid induced the differentiation of IEC-6 cells. beta-LG stabilized and increased cell permeation of retinoic acid. IEC-6 cells showed 3 or 4 times more ALP activity with co-treatment of retinoic acid and beta-LG. BSA and OVA accelerated differentiation of IEC-6 cells in a similiar fashion to beta -LG. But, pepton and casein didn't. Heat destruction of beta-LG, BSA and OVA lead to loss in the ability of these compounds to induce cellular differentiation. The PKA signal pathway involved differentiation of IEC-6 cells. IEC-6 cells proliferation increased by the activation of PKC signal pathway and decreased differentiation by PKC signal pathway. CONCLUSION: Our results confirm that signal pathways are related to the proliferation and differ entiation of small intestinal epithelial cells and various compounds from food sources of childhood, such as beta-LG, BSA, OVA, and retinoic acid. These compounds appear to induce differentiation of small intestinal epithelial cells and may play a role in stimulating regeneration of epithelial cells after small intestinal mucosal injury.