Effect of TLR4 antagonist on immune responses of bovine endometrial cells

Abstract

Bovine endometritis is one of the most common reproductive diseases and causes important economic losses. Lipopolysaccharide (LPS) from Gram-negative bacteria is recognized by Toll-like receptor 4 (TLR4). Binding of LPS and TLR4 mediates the expression of proinflammatory cytokines and chemokines. This study aimed to access the effect of TLR4 antagonist (RsLPS) on the immune responses of bovine endometrial cells. Primary culture of bovine endometrial cells were challenged with LPS (100 ng/ml) after treated with and without RsLPS (5000 ng/ml). Endometrial cells without RsLPS and LPS treatment served as control. The mRNA expression of TLR4, CD14, TNF, IL1B and IL8 were investigated by using qPCR. The secretory protein of IL8 was measured by using ELISA. As expected, LPS up-regulated the mRNA expression of TNF, IL1B, IL8 and the secretion of IL8 (p < 0.01). Meanwhile, endometrial cells pre-treated with RsLPS, after challenging with LPS showed an increased mRNA expression of all candidate genes (p < 0.05) except only CD14 compared to control group. Interestingly, the secretion of IL8 was significantly decreased in LPS challenged endometrial cells pre-treated with RsLPS (p < 0.01) compared to LPS treatment group. Our findings suggested that RsLPS may act as antagonist for TLR4 in bovine endometrial cells. Nevertheless, other signaling pathways may involve with the link between innate immune responses and TLR4 antagonist. Therefore, the signaling mechanisms of RsLPS that related to the expression of proinflammatory mediators should be further investigated.