Effect Of Chronic Exposure To PM_2.5 On Mucociliary Clearance In Rats And The Intervention Of Myrtol Standardized

Objective : We investigated the effect of chronic PM_2.5 exposure on mucociliary clearance?MCC?,and analyzed the effect of Myrtol Standardized on it.Methods:1 Modal building:A total 48 male SD rats?220�20g?were randomly divided into 3 groups: exposure to Filtered air?FA?,exposure to PM_2.5?PM?,PM_2.5 plus Myrtol Standardized treatment?PM+CS?,each group was divided into 2 groups?n=8?.PM group and PM+CS group exposed to ambient air of Shijiazhuang city.we respectively give physiological saline1ml/Kg�d and CS 300mg/Kg�d intragastric administration.The FA groups inhaled filtered clean air indoor and were given by gavage once a day with physiological saline 1ml/Kg.Eight rats of each group were sacrificed after three months and six months separately.2 The number of total cells and classification in the bronchoalveolar lavage fluid?BALF?were detected by microscopy.3 Part of the lung and tracheal tissues were sliced and stained with hematoxylin�eosin?HE?,and HE staining was used to observe themorphological changes.4 The changes of cilia ultrastructure were observed by scanning electron microscope.5 Mucous cells metaplasla were visualized Alcian blue-periodic acid chiff staining?AB-PAS?and were observed by light microscope.6 The gene and protein expressional level of MUC5 AC in lung were respectively measured by immunohistochemistry,western blot and reverse transcriptase polymerase chain reaction?RT-PCR?.7 The gene expressional level of AQP5 in lung were detected by reverse transcriptase polymerase chain reaction?RT-PCR?.Results:1 The comparison of PM_2.5 concentration in each group: The statistical results showed that during three months and six months,the PM_2.5concentration in PM group and outdoor group was significantly higher than that of FA group?P<0.05?.The PM_2.5 concentration between PM group and outdoor group had no significant difference?P>0.05?.2 The total number of WBC,and neutrophils count and percentage of neutrophils in BALF of different groups:PM groups were significantly increased than that of FA group and PM+CS groups?P<0.05?,whereas no difference was observed between PM3+CS group and FA3 group?P>0.05?.Compared to the FA6 group,PM6+CS group had significantly higher levels of the total number of WBC,and neutrophils count and percentage of neutrophils in BALF?P<0.05?.The total number of WBC,and neutrophils count and percentage of neutrophils in BALF of PM6 group were significantly increased compared with that of PM3 group?P<0.05?.3 The histological manifestation of lung tissue and tracheal tissue in different groups?HE?: The results of lung histopathologic score showed that the histopathological grades of PM groups were higher than that of FA groups and PM+CS groups?P<0.05?,whereas no difference was observed between PM3+CS group and FA3 group?P>0.05?.The results of lung histopathologic score showed that the histopathological grades of PM6+CS group were higher than that of FA6 group,and the pathologic scores of PM6 group were higher than PM3 months group?P<0.05?.4 Scanning electron micrograph of rat trachea cilia ultrastructure in different groups:Scanning electron micrograph of rat trachea cilia ultrastructure in FA groups were generally normal.The adhesion,disturbance,lodge and squamous metaplasia of cilia in tracheal epithelium of PM groups were observed.The cilie ultrastructure impairment after PM_2.5 exposure could be significantly attenuated by the administration of Myrtol standardized.5 Mucous cells metaplasla were visualized Alcian blue-periodic acid chiffstaining?AB-PAS?in different groups: The results showed that the percentage of mucus-positive area of the whole bronchial epithelium?AB-PAS/Aep?of PM groups were significantly increased than that of FA groups?P<0.05?,whereas no difference was observed between PM6+CS group and PM6group?P>0.05?.Compared to the PM3+CS group,PM3 group had significantly higher levels of the percentage of mucus-positive area of the whole bronchial epithelium?P<0.05?.There was no difference observed between PM3+CS group and FA3 group?P>0.05?.The results showed that the AB-PAS/Aep of PM6 +CSgroup were significantly increased than that of FA6 group?P<0.05?,and the AB-PAS/Aep of PM6 group were higher than PM3 group?P<0.05?.6 The results of immunohistochemistry show that the protein expressional level of MUC5 AC in lung of different groups: The protein expressional level of MUC5 AC in lung of PM groups was significantly higher than that of FA groups and PM+CS groups?P<0.05?,whereas no difference was observed between PM3+CS group and FA3 group?P>0.05?.Compared to the FA6 group,PM6+CS group had significantly higher protein expressional level of MUC5 AC in lung?P<0.05?.The protein expressional level of MUC5 AC in lung of PM6 group was significantly higher than that of PM3group?P<0.05?.7 The results of western blot show that the protein expressional level of MUC5 AC in lung of different groups:The protein expressional level of MUC5 AC in lung of PM groups was significantly higher than that of FA groups and PM+CS groups?P<0.05?.Compared to the FA groups,PM+CS groups had significantly higher protein expressional level of MUC5 AC in lung?P<0.05?.The protein expressional level of MUC5 AC in lung of PM6 group was significantly higher than that of PM3 group?P<0.05?.8 The m RNA level of MCU5 AC gene in lung tissue : The results of RT-PCR showed that the m RNA level of MCU5 AC gene in the lung tissues of PM groups were significantly increased than that of FA groups and PM+CS groups?P<0.05?.Compared to the PM3+CSgroup,FA3 group had significantly higher gene expressional level of MUC5 AC in lung?P<0.05?.The geneexpressional level of MUC5 AC in lung of PM6+CS group was significantly higher than that of FA6 group?P<0.05?.Compared to the PM3 group,PM6group had significantly higher gene expressional level of MUC5 AC in lung?P<0.05?.9 The m RNA level of AQP5 gene in different groups:The results of RT-PCR showed that the m RNA level of AQP5 gene in the PM groups was significantly lower compared to the FA groups and PM+CS groups?P<0.05?.Compared to the FA groups,PM+CS groups had significantly lower gene expressional level of AQP5 in lung?P<0.05?.The gene expressional level of AQP5 in lung of PM6 group was significantly lower than that of PM3 group?P<0.05?.10 The result of correlation analysis:Compared with the FA groups,the expression of m RNA of AQP5 were weakened,but the expression of MUC5 AC m RNA were enhanced in PM groups,the expression of AQP5 gene was negatively correlated with MUC5 AC gene in the lung tissue of PM groups?r3=-0.98,P<0.05;r6=-0.954,P<0.05?.Compared PM+CS groups with the PM groups,the expression of AQP5 gene was enhanced.However,the expression of MUC5 AC gene was decreased,the expression of AQP5 gene was negatively correlated with MUC5 AC gene in the lung tissue?r3=-0.987,P<0.05;r6=-0.834,P<0.05?.Conclusion:1 Chronic PM_2.5 exposure can induce the trachea and lung inflammation.2 Chronic PM_2.5 exposure induced the MCC damage concomitant with damage the cilia ultrastrecture,increase the numbers of mucous cell metaplasia,enhance the expression of m RNA and protein of MUC5 AC and decrease the expression of m RNA of AQP5.These results provide a possible mechanism for the association between PM_2.5 exposure and the pulmonary impairment.3 The mechanism of Myrtol Standardized decreasing MCC damage and pulmonary impairment which were induced by PM_2.5 may reduce the trachea and lung tissue inflammatory injury,reduce the cilia ultrastrecture damage,attenuate the numbers of mucous cell metaplasia,inhibit the expression of m RNA and protein of MUC5 AC and increase the expression of m RNA of AQP5.