Effect of triterpene acids of Eriobotrya japonica (Thunb.) Lindl. leaf on inflammatory cytokine and mediator induction from alveolar macrophages of chronic bronchitic rats

Abstract

The study was to evaluate the effect of triterpene acids of Eriobotrya japonica (thunb.) lindl. leaf (TAL) on inflammatory cytokine and mediator expression in alveolar macrophages (AM) of chronic bronchitic (CB) rats. CB was induced by endotracheal instillation of lipopolysaccharide (LPS) followed by Bacillus Calmette Guerin (BCG) injection via the caudal vein one week later. Treatment groups received TAL at there different doses (50, 150, or 450 mg/kg daily i. g.), Ketotifen fumarate (5 mg/kg daily i. g.) or dexamethasone (1.2 mg/kg daily i. g.) for two weeks, 7 days after LPS injection. AM were then isolated and incubated for 24 h. IL-1, TNF-alpha and PGE2 levels in cultured supernatants were measured by thymocyte co-stimulating assay and radioimmunoassay. Immunocytochemistry staining and western-blot were used for intracellular location and activation of p65 subunit of NF-kB. LTB(4) level was analyzed by reverse-phase high performance liquid chromatography (RP-HPLC). The levels of TNF-alpha, IL-1, NF-kB, PGE2 and LTB(4) expression in AM of TAL groups were significantly decreased compared to the CB group (P < 0.05 or P < 0.01), in a dose dependent manner. TAL inhibited NF-kB activation in AM from CB rats and led to down regulation of TNF-alpha, IL-1, PGE(2) and LTB(4) expression, which might be a mechanism for its anti-inflammatory effects in CB rats.