Andrographolide attenuates inflammatory response induced by LPS via activating Nrf2 signaling pathway in bovine endometrial epithelial cells

Endometritis is one of the main causes of bovine infertility, which causes serious economic losses to the industry. The endometrium is the first line of defense against invading microbial pathogens in the uterus. Andrographolide is the primary active component of A. paniculate, and has been shown to have anti-inflammatory and antioxidant effects. However, its effects on the LPS-induced signaling pathway in bovine endometrial epithelial cells (bEECs) have not been reported yet. The aim of this study was to investigate the anti-inflammatory effects and mechanism of andrographolide in the LPS-induced inflammatory response of bEECs. We found that andrographolide strongly reduced LPS-induced NO and iNOS expression. The production of cytokines that were upregulated by LPS was significantly suppressed. To investigate the anti-inflammatory mechanism of andrographolide, we examined the activation of Nrf2. The results shown that andrographolide inhibited the expression of Keap1 but increased the expression of Nrf2. The expression levels of target genes of Nrf2 including Ho-1 and Nqo-1 were increased by andrographolide. Taken together, these results suggest that andrographolide may serve as a candidate to protect against the LPS-induced inflammatory response by inducing Nrf2 activation.