6-Bromoindirubin-3'-Oxime Suppresses LPS-Induced Inflammation via Inhibition of the TLR4/NF-κB and TLR4/MAPK Signaling Pathways.

Abstract

We investigated the efficacy of the traditional herbal extract 6-bromoindirubin-3'-oxime (BIO) against lipopolysaccharide (LPS)-induced mastitis in mice and inflammatory signaling in mouse mammary epithelial cells (MMECs). In vivo, breast inflammation scores and enzyme-linked immunosorbent assay (ELISA) detection of pro-inflammatory factor expression were used to assess the effect of BIO against mastitis. In vitro, the effects of BIO on LPS-induced changes in the expression levels of pro-inflammatory factors, anti-inflammatory cytokines, and signaling factors of the toll-like receptor 4 (TLR4)/nuclear factor-κB (NF-κB) and TLR4/mitogen-activated protein kinase (MAPK) pathways were examined by qRT-PCR and ELISA. In LPS-injected mice, BIO pretreatment downregulated the expression of the pro-inflammatory factors interleukin (IL)-1β, IL-6, tumor necrosis factor (TNF)-α, and myeloperoxidase (MPO) in mammary glands and reduced inflammatory lesions in breast tissue. In MMECs, BIO pretreatment downregulated the LPS-induced expression of IL-1β, IL-6, and TNF-α. Further, BIO inhibited both the expression and phosphorylation of TLR4/NF-κB and TLR4/MAPK signaling factors. Thus, BIO downregulates IL-6, IL-1β, TNF-α, and MPO expression, upregulates IL-10 expression, and suppresses LPS-induced inflammation by inhibiting the TLR4/NF-κB and TLR4/MAPK pathways. BIO may be a potential treatment agent for mastitis and other inflammatory diseases.