Regulation of Innate Immune Function in Bovine Oviduct Epithelial Cells in Culture: The Homeostatic Role of Epithelial Cells in Balancing Th1/Th2 Response

This study aimed to investigate the role of epithelial cells in regulating innateimmunity in bovine oviduct epithelial cell (BOEC) culture. We studied the effect ofEscherichia coli lipopolysaccharide (LPS) and its interaction withovarian steroids, estradiol (E2) and progesterone (P4), and luteinizing hormone (LH) atconcentrations observed during the preovulatory period on immune responses in BOECculture. Immunohistochemistry of oviduct tissue showed intensive expression of Toll-likereceptor-4 (TLR-4) and TLR-2 in epithelial cells. A dose of 10 ng/ml LPS stimulatedTLR-4, cyclooxygenase-2 (COX-2), nuclear factor kappaB inhibitor A (NFKBIA), interleukin 1β (IL-1β) and tumornecrosis factor α (TNF-α) expression, indicating an earlypro-inflammatory response. A dose of 100 ng/ml LPS did not induce expression of thesegenes but stimulated TLR-2, IL-10,IL-4and microsomal prostaglandin E synthase-1 (mPGES-1) expression and PGE2secretion, indicating an anti-inflammatory response. Ovarian steroids and LH completelyblock LPS (10 ng/ml)-induced TLR-4, IL-1β andTNF-α expression as well as LPS (100 ng/ml)-inducedTLR-2 expression. Taken together, this study suggests the existence ofan early signaling system to respond to infection in the BOEC. In addition, ovariansteroids and LH may play a critical role in inducing homeostasis and in controllinghyperactive pro-inflammatory responses detrimental to epithelial cells, sperm and theembryo.