Luteoloside is a flavonoid extracted from several natural herbs that exhibits anti-microbial and anti-inflammation properties. Our study mainly identified the anti-inflammatory mechanism of action of luteoloside in Staphylococcus aureus-induced endometritis. Histopathological observations and myeloperoxidase (MPO) activity showed that luteoloside could protect the uterus from S. aureus-induced damage and ameliorate the infiltration of inflammatory cells. Quantitative PCR (qPCR) and ELISA analysis also revealed that luteoloside could decrease the expression of the pro-inflammatory cytokines TNF-α, IL-1β, and IL-6 and increase the expression of the anti-inflammatory cytokine IL-10 both in vivo and in vitro. However, western blot analysis revealed that luteoloside inhibited the expression of TLR2 and IL-8 and inhibited the phosphorylation of IκBα and NF-κB p65. Moreover, luteoloside inhibited the apoptosis of endometrial epithelial cells (EECs), suppressed the phosphorylation of p53, and decreased the expression of caspase-3 induced by S. aureus. Furthermore, this study showed that luteoloside inhibited the expression of Bax but increased the expression of Bcl-2. These results indicate that luteoloside has anti-inflammatory properties by inhibiting the TLR2 and NF-κB signaling pathways and plays an anti-apoptotic role in S. aureus-induced endometritis, which may be valuable for the clinical treatment of S. aureus-induced inflammation.
Keywords: Bax; Bcl-2; NF-κB; Toll-like receptor 2; caspase-3; endometritis; luteoloside; p-p53.