Anti-Inflammatory Effects of 1,8-cineol(Eucalyptol) via NF-κB/COX-2 pathway in BEAS-2B cells and alleviates bronchoconstriction and airway hyperreactivity in ovalbumin sensitized mice

Abstract

Objective and Design: Asthma is becoming an inflammatory disease of the airways involving a variety of inflammatory cells and cell components.In this study,we attempted to investigate the protective effect and underlying mechanism potential of a plant derived natural compound,1,8-cineol.Transforming growth factor-beta TGF-β1-induced epithelial-mesenchymal transition (EMT) in bronchial epithelial cells contributes to airway wall remodeling in asthma. Epithelial-mesenchymal transition (EMT) represents an important source of myofibroblasts, contributing to airway remodelling. This study aims to explore the detailed mechanism in TGF-β1-stimulated BEAS-2B cells by which 1,8-cineol might exert effects on the development of asthma. Here, we investigated the role of 1,8-cineol,an active ingredient in Eucalyptus globulus Labill,in TGF-β1-induced EMT in bronchial epithelial cells and to elucidate the possible mechanisms underlying its biological effects. Material: We used a murine model of airway hyperreactivity, which mimicked some of the characteristic features of asthma. Male BALB/c mice (6–8 weeks) were used for this study. BEAS-2B cells were used to assess the effect of 1,8-cineol on EMT and its interaction with TGF-β1 signalling. To assess the role of 1,8-cineol in vivo and its impact on lung function. Methods: OVA-induced asthma and PSA model were used to evaluate the effect of 1,8-cineol in vivo.Lung tissues were collected for H&E and PAS staining. ELISA was used to determine level of IgE and chemokines (IL-4, IL-13, and IL-17). Nuclear factor-κB (NF-κB) and cyclooxygenase-2 (COX-2) signaling pathway were assessed. Human bronchial epithelial cells (BEAS-2B) were treated with different concentrations (1,10,and 100 mg/L,30 min) of 1,8-cineol to select its suitable concentration. A human bronchial epithelial cell line were incubated with transforming growth factor-beta (TGF-β) to induce EMT, whose phenotype of cells were evaluated by the expressions of EMT markers [alpha-smooth muscle actin (α-SMA), E-cadherin, and N-cadherin] and cell migration capacity. Results:In asthmatic model mice, 1,8-cineol treatment relieved airway wall remodeling and decreased expressions of EMT markers (α-SMA and N-cadherin). In TGF-β-treated bronchial epithelial cells, 1,8-cineol treatment decreased the mRNA and protein levels of EMT markers (α-SMA and N-cadherin) without impairing cell viability.Our results showed that OVA induction resulted in a significant increase in R_L, accompanied by a significant decrease in C_dyn.Various inflammatory cells such as eosinophils and lymphocytes were infiltrated and aggregated around the airway of mice in OVA group.1,8-cineol and BAY-11-7083 can improve the pathological changes of airway smooth muscle spasm and lumen stenosis. Compared with Control group, OVA specific antibody IgE content in serum in other groups was up-regulated. The levels of interleukin- IL-4, IL-13,OVA-specific IgE in BALF, and the percentage of IL-17 in the lungs were markedly increased.Furthermore,the expression of NF-κB p-P65,NF-κB P65 and COX-2 in airways were significantly upregulated.Protein expression of N-cadherin,COX-2,NF-κB p-P65/NF-κB P65 was up-regulated in TGF-β1 group compared with Control group. Conclusion:Our study showed that 1,8-cineol inhibited TGF-β1-induced EMT in bronchial epithelial cells and found that the anti-EMT activity of 1,8-cineol might be related to its regulatory effect on NF-κB/COX-2 pathway.