Anti-inflammatory action of 2-carbomethoxy-2,3-epoxy-3-prenyl-1,4-naphthoquinone (CMEP-NQ) suppresses both the MyD88-dependent and TRIF-dependent pathways of TLR4 signaling in LPS-stimulated RAW264.7 cells
| Autor: | Chae Ha Yang, Sook Jahr Park, Ji-Young Lee, Sang Chan Kim, Hyun Ju Woo, Mi Hee Woo, Hae Sun Park, Do Youn Jun, Young Ho Kim |
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| Rok vydání: | 2017 |
| Předmět: |
Lipopolysaccharides
0301 basic medicine MAPK/ERK pathway p38 mitogen-activated protein kinases Anti-Inflammatory Agents Stimulation Plant Roots Mice 03 medical and health sciences 0302 clinical medicine Drug Discovery Animals Pharmacology Molecular Structure Chemistry Rubia In vitro Cell biology Toll-Like Receptor 4 Adaptor Proteins Vesicular Transport RAW 264.7 Cells 030104 developmental biology Gene Expression Regulation Biochemistry TRIF 030220 oncology & carcinogenesis Myeloid Differentiation Factor 88 TLR4 Phosphorylation lipids (amino acids peptides and proteins) Intracellular Naphthoquinones Signal Transduction |
| Zdroj: | Journal of Ethnopharmacology. 205:103-115 |
| ISSN: | 0378-8741 |
| DOI: | 10.1016/j.jep.2017.04.029 |
| Popis: | Ethnopharmacological relevance The roots of Rubia cordifolia L. have been widely used as a traditional herbal medicine in Northeast Asia for treating inflammatory diseases. Aim of the study To elucidate the anti-inflammatory mechanism of 2-carbomethoxy-2,3-epoxy-3- prenyl-1,4-naphthoquinone (CMEP-NQ), purified from the roots of R. cordifolia L. as the major anti-inflammatory component, in LPS-treated RAW264.7 murine macrophage cells. Materials and methods Anti-inflammatory activity of CMEP-NQ was investigated in LPS-treated RAW264.7 cells by measuring the levels of NO, PGE2, and cytokines (IL1β, IL-6, TNF-α) in the culture supernatants and the TLR4-mediated intracellular events including association of MyD88 with IRAK1, activation of IRAK1, TAK1, MAPKs, NF-κB/AP-1, and IRF3, and generation of ROS. Results Pretreatment of RAW264.7 cells with CMEP-NQ reduced LPS-induced production of NO and PGE2 by suppressing iNOS and COX-2 gene expression. CMEP-NQ also reduced the secretion of IL-1β, IL-6, and TNF-α by down-regulating mRNA levels. Under these conditions, TLR4-mediated MyD88-dependent events were inhibited by CMEP-NQ, including the association of MyD88 with IRAK1, phosphorylation of IRAK1, TAK1, and MAPKs (ERK, JNK and p38 MAPK), and activation of NF-κB and AP-1. As TRIF-dependent events of TLR4 signaling, phosphorylation of IRF3 and induction of iNOS protein expression were also inhibited by CMEP-NQ. However, the binding of FITC-conjugated LPS to cell surface TLR4 was not affected by CMEP-NQ. Following LPS stimulation, intracellular ROS production was first detected by DCFH-DA staining at 1 h; then it continuously increased until 16 h. Although CMEP-NQ failed to exhibit DPPH radical- or ABTS radical-scavenging activity in vitro, LPS-induced ROS production in RAW264.7 cells was more efficiently blocked by CMEP-NQ than by NAC. Conclusions These results demonstrate that the suppressive effect of CMEP-NQ on LPS-induced inflammatory responses in RAW264.7 cells was mainly exerted via its inhibition of TLR4-mediated proximal events, such as MyD88-dependent NF-κB/AP-1 activation and ROS production, and TRIF-dependent IRF3 activation. |
| Databáze: | OpenAIRE |
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