IFN-τ Attenuates LPS-Induced Endometritis by Restraining HMGB1/NF-κB Activation in bEECs

Endometritis is a common inflammatory disease in uterine tissues that leads to animal infertility. Among the causes, Escherichia coli infection is one of the main reasons. Interferon-tau (IFN-τ) is the initial pregnancy signal for ruminant embryos and can induce immune tolerance in humans and other species. However, there are scarce reports on whether IFN-τ has a regulatory effect on endometrial inflammatory damage through HMGB1-NF-κB signalling. The purpose of this study was to investigate the regulatory mechanism of IFN-τ in HMGB1-NF-κB signalling in LPS-induced endometritis. ELISA and qPCR were used to detect the expression of LPS-induced pro-inflammatory cytokines in bovine endometrial epithelial cells (bEECs or BEND) under IFN-τ intervention, and the levels of HMGB1, p-IKK and p-p65 were detected by Western blotting. The nuclear translocation of NF-κB p65 was determined through immunofluorescence. In addition, bEECs were transfected with si-HMGB1 to elucidate the key role of HMGB1 and IFN-τ in the endometrial inflammatory cascade. The results indicated that IFN-τ inhibits the expression of related pro-inflammatory cytokines in an inflammatory injury model of bovine endometrial epithelial cells induced by LPS. Furthermore, experiments have proven that IFN-τ has protective effects on E. coli endotoxin-induced endometritis in mice in vivo. IFN-τ inhibited the HMGB1-NF-κB axis and significantly reduced the secretion of pro-inflammatory cytokines, the expression of HMGB1 protein and the levels of IKK and NF-κB p65 phosphorylation. In summary, our results showed that IFN-τ resists E. coli endotoxin-induced endometritis by attenuating HMGB1/NF-κB signalling.