Development and characterization of a rat model of chronic obstructive pulmonary disease (COPD) induced by sidestream cigarette smoke.

Cigarette smoke (CS) induced chronic obstructive pulmonary disease (COPD) has been emerging as a great health problem in China. However, lack of appropriate animal model slows down the progress in understanding pathogenesis of the disease. The aim of current study is to establish and evaluate a more adequate rat model of COPD. Study was performed with rats exposed to sidestream cigarette smoke 2h/d and 7d/wk for 2, 4, 6, 8, 10, 12, 24 and 36 wk in a CS chamber (carbon monoxide concentration was 231+/-11ppm). The lung function was determined by using the forced oscillation technique. Pathologic changes were determined by using histological analyses and mucin measurement. Following 36-wk exposure, airway resistance (Raw) and respiratory system elastance (Ers) in CS group rats was elevated by 28.5% and 37.5%, respectively. Up to 4.1-, 2.3- and 1.4-fold increase in the number of neutrophils, macrophages and lymphocytes was observed in the BALF of CS rats. Using quantitative histomorphology techniques, it was found that mean linear intercept (MLI) and mean alveolar airspace (MAA) of CS rats increased by 44.8% and 43.7%, respectively, indicating the occurrence of emphysema. The characteristics of chronic bronchitis including hyperplasia of bronchial epithelial cells, hypersecretion of mucus and development of peribronchial fibrosis were also found in rat lungs. CS group rats showed 43% body weight gain reduction. To conclude, a more adequate sidestream cigarette smoke rat COPD model was established, which will be beneficial for understanding the pathogenesis of the disease and for evaluation of drug effectiveness.

Modulation of expression and function of Toll-like receptor 3 in A549 and H292 cells by histamine.

It was reported recently that histamine induced Toll-like receptor (TLR)2 and TLR4 expression in endothelial cells and enhanced their sensitivity to Gram-positive and Gram-negative bacteria; and that TLRs were expressed in airway epithelial cells and that several inflammatory mediators modulated their expression. However, little is known of potential influence of histamine on TLRs in pulmonary epithelial cells. In the present study, effects of histamine on expression of TLRs in both human A549 and NCI-H292 cell lines were examined by using real-time quantitative RT-PCR analysis, flow cytometry and immunofluorescent staining. The results revealed that both cell types constitutively expressed mRNAs for TLR1-TLR10. Histamine up-regulated the expression of TLR3 mRNA by 12.3- and 11.6-fold, respectively in both cell types. The time course showed that histamine induced TLR3 mRNA expression was initiated at 30 min, nearly reached peak levels after 2 h and was sustained at least until 12 h. Histamine also induced TLR3 protein expression in A549 and NCI-H292 cells. Histamine and poly (I:C), a specific TLR3 ligand stimulated interleukin (IL)-8 secretion from both cell types. Moreover, histamine enhanced poly (I:C)-induced IL-8 secretion and phosphorylation of NF-kappaB in the two cell types, and histamine H1 receptor antagonists inhibited the action of histamine. In conclusion, histamine selectively up-regulated expression of TLR3, and stimulated IL-8 secretion from the cells. Histamine also enhanced poly (I:C) induced IL-8 secretion and phosphorylation of NF-kappaB. These observations suggest that histamine might play an important role in enhancing the innate immune responses of airway to viral infection.