title: Melatonin modulates TLR4-mediated inflammatory genes through MyD88- and TRIF-dependent signaling pathways in lipopolysaccharide-stimulated RAW264.7 cells.
abstract: Increasing evidence demonstrates that melatonin has an anti-inflammatory effect. Nevertheless, the molecular mechanisms remain obscure. In this study, we investigated the effect of melatonin on toll-like receptor 4 (TLR4)-mediated molecule myeloid differentiation factor 88 (MyD88)-dependent and TRIF-dependent signaling pathways in lipopolysaccharide (LPS)-stimulated macrophages. RAW264.7 cells were incubated with LPS (2.0 μg/mL) in the absence or presence of melatonin (10, 100, 1000 μm). As expected, melatonin inhibited TLR4-mediated tumor necrosis factor alpha (TNF-α), interleukin (IL)-1β, IL-6, IL-8, and IL-10 in LPS-stimulated macrophages. In addition, melatonin significantly attenuated LPS-induced upregulation of cyclooxygenase (COX)-2 and inducible nitric oxide synthase (iNOS) in macrophages. Further analysis showed that melatonin inhibited the expression of MyD88 in LPS-stimulated macrophages. Although it had no effect on TLR4-mediated phosphorylation of c-Jun N-terminal kinase (JNK), p38, and extracellular regulated protein kinase (ERK), melatonin significantly attenuated the activation of nuclear factor kappa B (NF-κB) in LPS-stimulated macrophages. In addition, melatonin inhibited TLR4-mediated Akt phosphorylation in LPS-stimulated macrophages. Moreover, melatonin significantly attenuated the elevation of interferon (IFN)-regulated factor-3 (IRF3), which was involved in TLR4-mediated TRIF-dependent signaling pathway, in LPS-stimulated macrophages. Correspondingly, melatonin significantly alleviated LPS-induced IFN-β in macrophages. In conclusion, melatonin modulates TLR4-mediated inflammatory genes through MyD88-dependent and TRIF-dependent signaling pathways.
authors.affiliation: Life Science College, Anhui Agricultural University, Hefei, China.
authors.forename: Mi-Zhen
authors.initials: MZ
authors.lastname: Xia
authors.forename: Ying-Li
authors.initials: YL
authors.lastname: Liang
authors.forename: Hua
authors.initials: H
authors.lastname: Wang
authors.forename: Xi
authors.initials: X
authors.lastname: Chen
authors.forename: Yin-Yin
authors.initials: YY
authors.lastname: Huang
authors.forename: Zhi-Hui
authors.initials: ZH
authors.lastname: Zhang
authors.forename: Yuan-Hua
authors.initials: YH
authors.lastname: Chen
authors.forename: Chen
authors.initials: C
authors.lastname: Zhang
authors.forename: Mei
authors.initials: M
authors.lastname: Zhao
authors.forename: De-Xiang
authors.initials: DX
authors.lastname: Xu
authors.forename: Li-Hua
authors.initials: LH
authors.lastname: Song
mesh_terms: D033942:Adaptor Proteins, Vesicular Transport / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D000893:Anti-Inflammatory Agents / Q000494:pharmacology*; D002460:Cell Line; D051546:Cyclooxygenase 2 / Q000235:genetics / Q000378:metabolism; D016207:Cytokines / Q000235:genetics / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004789:Enzyme Activation; D005786:Gene Expression Regulation; D007249:Inflammation / Q000235:genetics / Q000276:immunology / Q000378:metabolism / Q000517:prevention & control*; D018836:Inflammation Mediators / Q000378:metabolism*; D008070:Lipopolysaccharides / Q000494:pharmacology*; D008264:Macrophages / Q000187:drug effects* / Q000276:immunology / Q000378:metabolism; D008550:Melatonin / Q000494:pharmacology*; D051379:Mice; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D053594:Myeloid Differentiation Factor 88 / Q000235:genetics / Q000378:metabolism*; D016328:NF-kappa B / Q000378:metabolism; D052247:Nitric Oxide Synthase Type II / Q000235:genetics / Q000378:metabolism; D010766:Phosphorylation; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects*; D013997:Time Factors; D051197:Toll-Like Receptor 4 / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism
chemical_list: D033942:Adaptor Proteins, Vesicular Transport; D000893:Anti-Inflammatory Agents; D051546:Cyclooxygenase 2; D016207:Cytokines; D018836:Inflammation Mediators; D008070:Lipopolysaccharides; D008550:Melatonin; D020928:Mitogen-Activated Protein Kinases; D053594:Myeloid Differentiation Factor 88; D016328:NF-kappa B; D052247:Nitric Oxide Synthase Type II; D051057:Proto-Oncogene Proteins c-akt; D012333:RNA, Messenger; D051197:Toll-Like Receptor 4; C507780:Myd88 protein, mouse; C476286:Ticam1 protein, mouse; C493487:Tlr4 protein, mouse; C496317:Nos2 protein, mouse; C077623:Ptgs2 protein, mouse