Baicalin inhibits Staphylococcus aureus-induced apoptosis by regulating TLR2 and TLR2-related apoptotic factors in the mouse mammary glands

Baicalin, the major active constituent of the isolated root of Scutellaria, baicalensis, is widely used in China and Southeast Asian countries. Evidence has indicated that baicalin has multiple biological activities, including anti-apoptotic properties. Mastitis is a severe problem in humans and other animals and is characterized by mammary gland cell apoptosis. Staphylococcus aureus (S. aureus) is the major pathogen that causes mastitis. This study was designed to evaluate the protective effects of baicalin on the mammary glands during S. aureus-induced mastitis. In the present study, a mouse model was infected with S. (wrens to induce mammary gland injury. Baicalin treatment was administered between 6 and 24 h after infection. Toll like receptor 2, p53, BAX, BCL-2 and caspase-3 expression were analyzed using qPCR and Western blotting. The results indicated that baicalin significantly attenuated pathological damage and cell death in the mammary glands. Further studies revealed that baicalin down-regulated the expression of Toll like receptor 2 (TLR2) and the phosphorylalion of p53 in the mammary glands after S. aureus-induced mastitis. Baicalin also promoted the expression of BCL-2 at the mRNA and protein levels but inhibited BAX and caspase-3 (CASP-3) cleavage. Baicalin inhibited apoptosis and had prolective effects on mammary gland tissues during S. aureus-induced mastitis, These effects were displayed by reductions in TLR2 expression and p53 phosphorylalion and the regulation of apoptosis-related factors (BCL-2, BAX and CASP-3) in mammary gland tissues. (C) 2013 Elsevier B.V. All rights reserved