The Effect Of Calcium-binding Protein S100A8/A9 On Rats With Chronic Obstructive Pulmonary Disease

Objective: In order to explore the role of S100A8/A9 in the airway inflammation of Chronic Obstructive Pulmonary Disease(COPD) rats to cigarette smoke and infection exposure,we measured the concentrations of S100A8/A9 protein in serum and bronchoalveolar lavage fluid(BALF)of rats,the proportion of inflammatory cells in BALF of rats,the expression levels of S100A8 mRNA, S100A9 mRNA, S100A8/A9 protein as well as toll-like receptor4(TLR4), myeloid differentiation factor 88(MyD88)mRNA and protein in rats lung tissue.Methods: 12 wistar rats were randomly divided into normal control group and COPD group.COPD model was established by exposing the rats to cigarette smoke and injected lipopolysaccharide(LPS) in bronchus 1month.The pathological changes of the lung tissue of both groups rats were observed under light microscope, and then the emphysema indexes of MLI,MAN and PAA were analyzed by image analysis system. The proportions of neutrophils, lymphocytes, alveolar macrophages in BALF of two groups rats were measured by Wright’s staining methods and the concentrations of S100A8/A9 in serum and BALF were measured by ELISA. The expression levels of S100A8,S100A9,TLR4 and MyD88 mRNA were measured by Real time PCR. The expression of S100A8/A9,TLR4 and MyD88 protein of lung tissues were detected by immunohistochemistry.Results:(1)After smoked cigarette and injected LPS 1 month, the rat lung tissue appeared in accordance with the typical pathological changes ofCOPD,the MLI, MAN and PAA had obvious difference compared with normal control group(P<0.05).(2)The number of total cells and inflammatory cells in BALF of COPD rats were obviously higher than those of normal control rats(P<0.05).The proportions of neutrophils and lymphocytes in BALF of COPD rats were obviously higher than those of normal control rats(P<0.05).The proportion of macrophages in BALF of COPD group was obviously lower than that of normal control group(P<0.05).(3)The concentrations of S100A8/A9 protein in serum and BALF of COPD group were obviously higher than those of normal control group(P<0.05).(4)The levels of S100A8, S100A9, TLR4 and MyD88 mRNA of lung tissues in COPD group were obviously higher than those in normal control group(P<0.05),and each other have a positive correlation(P<0.05).(5)The S100A8/A9 protein mainly expressed in cytoplasm and membrane, TLR4 protein mainly expressed in membrane and Myd88 protein mainly expressed in cytoplasm. The levels of S100A8/A9,TLR4 and MyD88 protein of lung tissues in COPD group were obviously higher than those in normal control group(P<0.05),and each other have a positive correlation(P<0.05).Conclusion:(1)The model of COPD rats can be established successfully by exposing the rats to cigarette smoking daily and injecting LPS in bronchus;(2)The levels of S100A8/A9 in plasma, BALF and lung tissues were increased in COPD rats, indicate that cigarette smoke and infection can stimulate the expression and release of S100A8/A9 in lung tissues. As a new inflammatory mediators, the S100A8/A9 protein may involved in the development of COPD;(3)The expression levels of TLR4 and MyD88 were increased in lung tissues of COPD rats,The levels of S100A8, S100A9 had a positive correlation with TLR4 and MyD88 respectively, indicate thatS100A8/A9 can upregulate the expression of TLR4 and MyD88, activate the classic TLR4-MyD88 inflammatory pathways,amplify inflammatory reaction,and then promote the development of COPD.