β-Patchoulene from patchouli oil protects against LPS-induced acute lung injury via suppressing NF-κB and activating Nrf2 pathways

beta-Patchoulene (beta-PAE), a tricyclic sesquiterpene isolated from the essential oil of the leaves and stems of Pogostemon cablin (Blanco) Benth., has been reported to have potent anti-inflammatory activity. The aim of this study was to evaluate the potential protective effect of beta-PAE on lipopolysaccharide (LPS)-induced acute lung injury (ALI) in mice and to illuminate the underlying mechanisms. ALI was induced by intracheal instillation of LPS into lung, and dexamethasone (DEX) was used as a positive control. Results indicated that pretreatment with beta-PAE significantly decreased the mortality rate of mice and lung W/D weight ratio, ameliorated lung pathological changes as compared to model group. Meanwhile, beta-PAE pretreatment markedly inhibited the increase of TNF-alpha, IL-6 and IL-1 beta secretions in the bronchoalveolar lavage fluid, and prevented LPS-induced elevations of MPO activity and MDA level in the lung. Additionally, beta-PAE pretreatment significantly elevated miR-146a expression and suppressed the LPS-induced activation of NF-kappa B and expression of its mediated genes (TNF-alpha, IL-6 and IL-1 beta). beta-PAE was also observed to markedly upregulate the Nrf2 and HO-1 expression and activate the antioxidant genes (NQO-1, GCLC and HO-1). Taken together, beta-PAE possessed protective effect against LPS-induced ALI, which might be associated with its differential regulation of NF-kappa B and Nrf2 activities and upregulation of expression of miR-146a. The results rendered beta-PAE a promising anti-inflammatory agent worthy of further development into a pharmaceutical drug for the treatment of ALI.