NRF2 Exerts Anti‐Inflammatory Effects in LPS‐Induced gEECs by Inhibiting the Activation of the NF‐<i>κ</i>B
Hongchu Bao, Qinglan Qu, Wei Zhang, Xinrong Wang, Jianye Fang, Jinwen Xue, Zhenteng Liu, Shunzhi He
Abstract
Nuclear factor E2‐related factor 2 (NRF2) plays an anti‐inflammatory role in several pathological processes, but its function in lipopolysaccharide‐ (LPS‐) induced goat endometrial epithelial cells (gEECs) is still unknown. We designed a study to investigate the function of NRF2 in LPS‐induced gEECs. LPS was found to increase the NRF2 expression and the nuclear abundance of NRF2 in gEECs in a dose‐dependent manner. NRF2 knockout (KO) not only increased the expression of LPS‐induced proinflammatory cytokines (TNF‐ α , IL‐1 β , IL‐6 and IL‐8) but also increased the expression of TLR4, p‐I κ B α /I κ B α , and p‐p65/p65 proteins. Immunoprecipitation experiments showed that NRF2 directly binds to p65 in the nucleus and inhibits the binding of p65 to downstream target genes (TNF‐ α , IL‐1 β , IL‐6, and IL‐8). Even though a NF‐ κ B/p65 inhibitor (PDTC) reduced the LPS‐induced NRF2 expression and nuclear abundance of NRF2, overexpressing TNF‐ α reversed the inhibitory effects of PDTC on the NRF2 expression and on its abundance in the nucleus. Similarly, knockdown of the proinflammatory cytokines (TNF‐ α , IL‐1 β , IL‐6, or IL‐8) significantly decreased the LPS‐induced NRF2 expression and NRF2 in the nucleus. In conclusion, our data suggest that proinflammatory cytokines induced by LPS through the TLR4/NF‐ κ B pathway promote the NRF2 expression and its translocation into the nucleus. Our work also suggests that NRF2 inhibits the expression of proinflammatory cytokines by directly binding to p65.