Molecular mechanism of capillarisin-mediated inhibition of MyD88/TIRAP inflammatory signaling in in vitro and in vivo experimental models

초록

Ethnopharmacological relevance: Artemisia capillaris Thunberg (Compositae) have been used as traditional medicine as a diuretic, liver protective agent, and for amelioration of inflammatory and analgesic disorders. The present study was carried out to establish the scientific rationale for treating inflammation and to find active principles from A. capillaris. The aim of the present study is to investigate the possible anti-inflammatory mechanism of the major component (capillarisin) isolated from A. capillaris via inhibition of MyD88/TIRAP inflammatory signaling both in vitro and in vivo models. Materials and methods: The nitrite, PGE(2), and TNE-alpha productions were evaluated by Griess reagent and ELISA kits. The protein and mRNA expression levels were investigated by Western blot and RT-PCR. The NE-kappa B and AP-1 DNA-binding was performed by electrophoretic mobility shift assay. The CFA- and carrageenan-induced paw edema was performed in ICR mice in which 20 and 80 mg/kg body weight of capillarisin was administered intraperitoneally (i.p.). Results: The results demonstrated that pretreatment with capillarisin effectively inhibited the LPS-induced activation of NE-kappa B, Akt, and MAP kinase-activated inflammatory genes, which is mediated by MyD88 and TIRAP. Treatment with capillarisin reduced the mRNA and protein levels of iNOS and COX-2 in RAW 264.7 cells as assessed by RT-PCR and Western blot. Capillarisin suppressed LPS-induced inhibitory kappa kinase (IKK) phosphorylation and the degradation of inhibitory kappa B (I kappa B alpha) and prevented the nuclear translocation of p65 and p50. Capillarisin also exhibited a promising inhibitory effect on the LPS-induced NF-kappa B and AP-1 DNA binding activity based on an electrophoretic mobility shift assay. The LPS-induced activation of p-JNK, p-p38, p-ERK, and p-Akt was significantly inhibited. In addition, the TNF-alpha level in the media was effectively reduced by capillarisin. In vivo experimental analysis revealed that capillarisin (20 and 80 mg/kg, i.p.) inhibited complete Freund's adjuvant (CFA)-and carrageenan-induced paw edema, nitrite production in plasma, and TNE-alpha, a pro-inflammatory cytoldne production. Conclusion: The results presented here demonstrate that capillarisin has consistent anti-inflammatory properties and acts by inhibiting inflammatory mediators in in vitro and in vivo experimental models, and suggest its potential utility in the control of inflammatory disorders. (C) 2012 Elsevier Ireland Ltd. All rights reserved.

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