Protective effects of liquiritin apioside on cigarette smoke-induced lung epithelial cell injury.

Cigarette smoking is associated with an increased incidence of chronic obstructive pulmonary disease (COPD). In this study, we hypothesized that liquiritin apioside (LA), a main flavonoid component from Glycyrrhiza uralensis, had antioxidant properties by inducing glutathione (GSH) biosynthesis via the inhibition of cytokines and protected lung epithelial cells against cigarette smoke-mediated oxidative stress. A549 cells were treated with cigarette smoke extract (CSE) and/or LA. ICR mice were exposed to cigarette smoke (CS) for four days with increasing exposure time for up to 6 h per day to elicit epithelial cells injury. One hour before smoke exposure, mice were treated with LA by gavage; 18 h after the last CS exposure all examinations were performed. Treatment with LA concentration-dependently prevented CSE-induced cytotoxicity, increase of TGF-ß and TNF-α mRNA expression, depletion of GSH and apoptosis in A549 cells. LA at doses 3, 10 and 30 mg/kg dose-dependently inhibited pulmonary neutrophil and macrophage inflammation. Lung sections of the CS-exposed LA treated mice showed an apparently reduced pulmonary inflammation and a significant inhibitory effect on mucus containing goblet cells in the large airways. Furthermore, the CS-induced pulmonary release of TGF-ß, TNF-α and myeloperoxidase activity was reduced, and superoxide dismutase activity was enhanced.These results indicate that protective roles of LA on CS-induced the lung epithelial cell injury are mediated by inhibiting TGF-ß and TNF-α expression and increasing anti-oxidative levels of GSH, suggesting that LA might be effective as protective agent against epithelial injury in COPD.

M(3) muscarinic receptor antagonist bencycloquidium bromide attenuates allergic airway inflammation, hyperresponsiveness and remodeling in mice.

M(3) muscarinic receptors are localized on inflammatory cells, airway smooth muscle, and submucosal glands, known to mediate bronchoconstriction, mucus secretion, and airway remodeling. It is hypothesized bencycloquidium bromide (BCQB), a novel M(3) receptor antagonist, might have potential effects on airway hyperresponsiveness, inflammation and airway remodeling in a murine model of asthma. Mice sensitized and challenged with ovalbumin developed airway inflammation. Bronchoalveolar lavage fluid was examined to determine the total and differential cell counts, and cytokine levels. Lung tissues were evaluated for cell infiltration, mucus hypersecretion, airway remodeling, and the expression of inflammatory biomarkers. Airway hyperresponsiveness was monitored by direct airway resistance analysis. Inhalation administration of BCQB significantly not only reduced ovalbumin-induced airway hyperresponsiveness comparing to methacholine, and prevented the ovalbumin-induced increase in total cell counts and eosinophil counts. Reverse transcriptase polymerase chain reaction analysis of whole lung lysates revealed that BCQB markedly suppressed ovalbumin-induced mRNA expression of eotaxin, IL-5, IL-4 and MMP-9, and increased mRNA expression of IFN-γ and TIMP-1 in a dose-dependent manner. Substantial IFN-γ/IL-4 (Th1/Th2) levels were recovered in bronchoalveolar lavage fluid after BCQB treatment. In addition, histological studies showed that BCQB dramatically inhibited ovalbumin-induced lung tissue eosinophil infiltration, airway mucus production and collagen deposition in lung tissues. Results reported in current paper suggest that M(3) receptors antagonist may provide a novel therapeutic approach to treat airway inflammation, hyperresponsiveness and remodeling.