Mechanism of Astragalus Polysaccharide in Alleviating Bovine Mammary Fibrosis through ROS/NLRP3 Inhibition and EMT Regulation

Mastitis in dairy cows, typically caused by bacterial infection, is a common inflammatory condition of the mammary tissue that leads to fibrosis, adversely affecting cow health, milk production, and dairy product quality. Astragalus polysaccharide (APS) has shown effectiveness in alleviating inflammation and fibrosis in various organs. In this study, a lipopolysaccharide (LPS)-induced fibrosis model was established using a bovine mammary epithelial cell line (MAC-T) and Kunming rats. Key parameters, including relative gene mRNA expression, protein levels, and reactive oxygen species (ROS) content, were assessed using RT-qPCR, Western blotting (WB), and DCFH-DA techniques, while histological analysis of breast tissue was performed using H&E and Masson trichrome staining. Oxidative stress markers, such as malondialdehyde (MDA) concentration and enzymatic activities of superoxide dismutase (SOD) and catalase (CAT), were also evaluated in mouse mammary glands. APS treatment modulated fibrosis markers (E-cadherin, N-cadherin, and α-SMA) and inflammation markers (NLRP3, ASC, Caspase-1, and IL-1β) at both mRNA and protein levels, significantly reduced ROS concentrations (P<0.01), restored oxidative stress balance in mice (P<0.05), and mitigated fibrosis and inflammation, as revealed by histological observations. These findings demonstrate that APS can mitigate ROS accumulation, reduce inflammation, and inhibit epithelial-mesenchymal transition (EMT) in vitro and mammary fibrosis in vivo, supporting its potential as an alternative therapeutic agent for mammary fibrosis treatment.