title: Indirubin Inhibits LPS-Induced Inflammation via TLR4 Abrogation Mediated by the NF-kB and MAPK Signaling Pathways.
abstract: Indirubin plays an important role in the treatment of many chronic diseases and exhibits strong anti-inflammatory activity. However, the molecular mode of action during mastitis prophylaxis remains poorly understood. In this study, a lipopolysaccharide (LPS)-induced mastitis mouse model showed that indirubin attenuated histopathological changes in the mammary gland, local tissue necrosis, and neutrophil infiltration. Moreover, indirubin significantly downregulated the production of interleukin (IL)-1β, IL-6, and tumor necrosis factor-α (TNF-α). We explored the mechanism whereby indirubin exerts protective effects against LPS-induced inflammation of mouse mammary epithelial cells (MMECs). The addition of different concentrations of indirubin before exposure of cells to LPS for 1 h significantly attenuated inflammation and reduced the concentrations of the three inflammatory cytokines in a dose-dependent manner. Indirubin downregulated LPS-induced cyclooxygenase-2 (COX-2) and Toll-like receptor 4 (TLR4) expression, inhibited phosphorylation of the LPS-induced nuclear transcription factor-kappa B (NF-kB) P65 protein and its inhibitor IkBα of the NF-kB signaling pathway. Furthermore, indirubin suppressed phosphorylation of P38, extracellular signal-regulated kinase (ERK), and c-Jun NH2-terminal kinase (JNK) of the mitogen-activated protein kinase (MAPK) signal pathways. Thus, indirubin effectively suppressed LPS-induced inflammation via TLR4 abrogation mediated by the NF-kB and MAPK signaling pathways and may be useful for mastitis prophylaxis.
authors.affiliation: The Faculty of Veterinary Medicine, Huazhong Agricultural University, Wuhan, 430070, China.
authors.forename: Jin-Lun
authors.initials: JL
authors.lastname: Lai
authors.affiliation: The Faculty of Veterinary Medicine, Huazhong Agricultural University, Wuhan, 430070, China.
authors.forename: Yu-Hui
authors.initials: YH
authors.lastname: Liu
authors.affiliation: The Faculty of Veterinary Medicine, Huazhong Agricultural University, Wuhan, 430070, China.
authors.forename: Chang
authors.initials: C
authors.lastname: Liu
authors.affiliation: The Faculty of Veterinary Medicine, Huazhong Agricultural University, Wuhan, 430070, China.
authors.forename: Ming-Pu
authors.initials: MP
authors.lastname: Qi
authors.affiliation: The Faculty of Veterinary Medicine, Huazhong Agricultural University, Wuhan, 430070, China.
authors.forename: Rui-Ning
authors.initials: RN
authors.lastname: Liu
authors.affiliation: The Faculty of Veterinary Medicine, Huazhong Agricultural University, Wuhan, 430070, China.
authors.forename: Xi-Fang
authors.initials: XF
authors.lastname: Zhu
authors.affiliation: The Faculty of Veterinary Medicine, Huazhong Agricultural University, Wuhan, 430070, China.
authors.forename: Qiu-Ge
authors.initials: QG
authors.lastname: Zhou
authors.affiliation: The Faculty of Veterinary Medicine, Huazhong Agricultural University, Wuhan, 430070, China.|State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan, 430070, China.
authors.forename: Ying-Yu
authors.initials: YY
authors.lastname: Chen
authors.affiliation: The Faculty of Veterinary Medicine, Huazhong Agricultural University, Wuhan, 430070, China. aizhen@mail.hzau.edu.cn.|State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan, 430070, China. aizhen@mail.hzau.edu.cn.
authors.forename: Ai-Zhen
authors.initials: AZ
authors.lastname: Guo
authors.affiliation: The Faculty of Veterinary Medicine, Huazhong Agricultural University, Wuhan, 430070, China. hcm@mail.hzau.edu.cn.|State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan, 430070, China. hcm@mail.hzau.edu.cn.
authors.forename: Chang-Min
authors.initials: CM
authors.lastname: Hu
mesh_terms: D000818:Animals; D016207:Cytokines / Q000187:drug effects / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D005260:Female; D007211:Indoles / Q000494:pharmacology / Q000627:therapeutic use; D007249:Inflammation / Q000188:drug therapy*; D018836:Inflammation Mediators / Q000378:metabolism; D008070:Lipopolysaccharides; D020935:MAP Kinase Signaling System / Q000187:drug effects*; D008413:Mastitis / Q000188:drug therapy; D051379:Mice; D016328:NF-kappa B / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects; D051197:Toll-Like Receptor 4 / Q000502:physiology*
chemical_list: D016207:Cytokines; D007211:Indoles; D018836:Inflammation Mediators; D008070:Lipopolysaccharides; D016328:NF-kappa B; C493487:Tlr4 protein, mouse; D051197:Toll-Like Receptor 4; C027185:indirubin
keywords: MAPK; NF-kB; TLR4; indirubin; inflammation; lipopolysaccharide (LPS)