Selenium Yeast Attenuated Lipopolysaccharide-Induced Inflammation in Porcine Mammary Epithelial Cells by Modulating MAPK and NF-κB Signaling Pathways

Mastitis, a prevalent inflammatory disease in mammals, disrupts mammary gland function, compromises milk quality, and can contribute to increased offspring morbidity and mortality. Maintaining the health of porcine mammary epithelial cells (PMECs), the primary cell type in the mammary gland, is crucial for minimizing the adverse effects of this disease. Selenium yeast (SeY), an organic selenium compound known for its antioxidant and immune-enhancing properties, has yet to be fully understood in its role in modulating inflammation in mammary gland. In this study, lipopolysaccharide (LPS) (50 mu g/mL, 24 h) significantly upregulated the expression of pro-inflammatory cytokines, including tumor necrosis factor-alpha (TNF-alpha), interleukin-6 (IL-6), interleukin-8 (IL-8), and interleukin-1 beta (IL-1 beta) (p < 0.05). Pretreatment with 1 <mu>M SeY significantly attenuated the LPS-induced inflammatory response by reducing the levels of TNF-alpha, IL-6, IL-8, and IL-1 beta (p < 0.05). Additionally, SeY enhanced cellular antioxidant defenses by increasing total antioxidant capacity (T-AOC), superoxide dismutase (SOD) activity, glutathione (GSH) levels, and glutathione peroxidase (GSH-Px) activity, while concurrently decreasing malondialdehyde (MDA) accumulation (p < 0.05). SeY also restored both intracellular and extracellular triglyceride levels and rescued lipid droplet formation, which were disrupted by LPS treatment. Furthermore, SeY upregulated key regulators involved in milk synthesis (p < 0.05). These findings suggest that SeY effectively mitigates LPS-induced inflammation and oxidative stress while preserving critical pathways for milk fat and protein synthesis in PMECs.