Effects And Mechanisms Of Influenza A Virus On Cigarettesmoke Induced Inflammatory Responses Of COPD

COPD is a chronic lung disease characterized by persistent airway inflammation and limited airflow. Because of the wide epidemicity and high mortality, the pathogenesis of COPD has become a new hotspot in recent years. Cigarette smoke extract(CSE) is the main inducing factors of COPD. Research shows that 70% of COPD patients are smokers for a long time, 20% of smokers may be COPD. However, the mechanisms by which CSE induces COPD have not been established. CSE causes lung inflammation with accumulating macrophages and neutrophils and other inflammatory cells in lung. Bronchia and pulmonary mucosa promote inflammatory cytokines and chemokine factors secretion. It produces systematic inflammatory reaction and damages to the cardiovascular system and nervous system and respiratory system. Acute exacerbation of chronic obstructive pulmonary disease(AECOPD) is the main factors of high hospitalization rate and mortality. Viral infection of the respiratory tract is the main induced factor of AECOPD, such as rhinovirus, influenza virus and respiratory syncytial virus. In recent years, influenza virus infection in AECOPD in the world tends to rise. In recent years, along with the continuously deep the understanding of the innate immune response, influenza virus infection induces AECOPD is likely to be the impact of the innate immune response, thereby aggravates inflammation of COPD. Therefore, researching the effects and mechanisms of influenza A virus on cigarette smoke induced inflammatory responses of COPD has significance.This research includes two parts, in vitro and in vivo. In vitro, COPD cell model designed by smoke exposure. The half maximal inhibitory concentration determined by MTT. The groups of experiment are control group(cell culture fluid), CSE group(CSE), virus group(100TCID50), virus with CSE group(100TCID50+CSE cell culture fluid). The expression of inflammatory cytokines in A549 determined by ELISA including IL-6, IL-8, IL-1β and TNF-α. The relative expression of NLRP3 and Caspase-1 m RNA determined by Real-time PCR. In vivo, COPD mouse model designed by passive smoking. The groups of experiment are control group(feed routinely), CSE group(passive smoking), virus group(100TCID50), virus with CSE group(100TCID50+passive smoking). The trachea and lung tissue was obtained and stained by HE and AB-PAS. The content of NLRP3 and Caspase-1 determined by immunohistochemistry. The relative expression of inflammatory cytokines in mice lung tissue homogenate determined by ELISA including IL-6, IL-1β and TNF-α.The result show that IC50 is 20%CSE. The expression of IL-6, IL-8, IL-1β and TNF- α in CSE group improved significantly compared with control group. The pathologic changes of trachea and lung tissue in experiment group(CSE group, virus group, virus with CSE group) consistent with COPD clinical pathological changes. The degeneration and necrosis of tracheal epithelial cell, increased goblet cells, inflammatory cell infiltration in tracheal bronchial submucosa and lung, incomplete lung tissue structure appear in CSE group and virus group. A considerable number of degeneration and necrosis of tracheal epithelial cell, increased significantly goblet cells, a large amount of inflammatory cell infiltration in tracheal bronchial submucosa and lung, the severe destruction of lung tissue structure appear in virus with CSE group. The expression of NLRP3 and Caspase-1 is not significant increase in CSE group compared with control group, but the expression is significant increase in virus with CSE group compared with CSE group and virus group.In conclusion, the inflammation of the lung epithelial cells caused by CSE though activating natural immune molecules such as IL-6, IL-8, IL-1βand TNF-α. Influenza A virus increases inflammation of respiratory tract by regulating NLRP3 and Caspase-1 expression.