Geniposide Plays an Anti-inflammatory Role via Regulating TLR4 and Downstream Signaling Pathways in Lipopolysaccharide-Induced Mastitis in Mice
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Geniposide is a medicine isolated from Gardenia jasminoides Ellis, which is a traditional Chinese herb that is widely used in Asia for the treatment of inflammation, brain diseases, and hepatic disorders. Mastitis is a highly prevalent and important infectious disease. In this study, we used a lipopolysaccharide (LPS)-induced mouse mastitis model and LPS-stimulated primary mouse mammary epithelial cells (mMECs) to explore the anti-inflammatory effect and the mechanism of action of geniposide. Using intraductal injection of LPS as a mouse model of mastitis, we found that geniposide significantly reduced the infiltration of inflammatory cells and downregulated the production of tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), and interleukin-6 (IL-6). To further investigate the anti-inflammatory mechanism, we used LPS-stimulated mMECs as an in vitro mastitis model. The results of enzyme-linked immunosorbent assay (ELISA) and quantitative real-time polymerase chain reaction (qRT-PCR) showed that geniposide inhibited the expression of TNF-α, IL-1β, and IL-6 in a dose-dependent manner. Western blot analysis demonstrated that geniposide could suppress the phosphorylation of inhibitory kappa B (IκBα), nuclear factor-κB (NF-κB), p38, extracellular signal-regulated kinase (ERK), and c-Jun N-terminal kinase (JNK). Geniposide also inhibited the expression of toll-like receptor 4 (TLR4) in the LPS-stimulated mMECs. In conclusion, geniposide exerted its anti-inflammatory effect by regulating TLR4 expression, which affected the downstream NF-κB and mitogen-activated protein kinase (MAPK) signaling pathways. Thus, geniposide may be a potential drug for mastitis therapy.
KEY WORDSgeniposide lipopolysaccharide (LPS) anti-inflammatory toll-like receptor nuclear factor-κB (NF-κB) mitogen-activated protein kinase (MAPK)
This work was supported by a grant from the National Natural Science Foundation of China (Nos. 31272622, 31201925), the Research Fund for the Doctoral Program of Higher Education of China (Nos. 20110061130010, 20120061120098), and Jilin Province Science Foundation for Youths (No. 20130522087JH).
Conflict of Interest
All authors declare that they have no conflict of interest.
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