| Summary: | Bovine endometritis can be caused by <i>Escherichia coli</i> (<i>E. coli</i>), from which the lipopolysaccharide (LPS) triggers TLR4/NF-κB-mediated inflammation and reactive oxygen species (ROS) overproduction, resulting in impaired reproductive performance. While NADPH oxidase (NOX) is a critical source of ROS generation, its role in bovine endometrial epithelial cells (BEEC) and modulation by selenium remains unexplored. In this study, primary BEEC was challenged by LPS to assess NOX2/4 expression kinetics. Inhibitors of NOX and NF-κB were applied to observe the role of NOX-derived ROS in BEEC inflammation and in selenomethionine (SeMet)-modulated anti-inflammation. ROS levels were measured by flow cytometry. The changes in inflammatory cytokines, and the proteins related to NOX4 and NF-κB, were analyzed via qPCR and Western blot. As a result, the inhibition of NOX decreased LPS-induced proinflammatory cytokine expression, ROS accumulation, NOX4 level, and the phosphorylation of NF-κB P65 and IκBα. Conversely, the suppression of NF-κB downregulated the levels of ROS and NOX4. Cotreatment with SeMet and a NOX inhibitor further suppressed the inflammatory response, ROS level, and NF-κB pathway activation compared to individual treatment, but had no additive effect on the NOX4 protein level. In conclusion, the NOX4/ROS/NF-κB axis forms a proinflammatory feedback loop in LPS-stimulated BEEC. SeMet mitigates oxidative stress and inflammation partially through NOX4 inhibition.
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