Objective: To observe the effects of Qingzao Jiufei Tang (QJT) on the ultrastructure and the expression of cytotoxin MPN372

aquaporin 5 (AQP5) and pulmonary surfactant related protein-A (SP-A) in lung tissue of mice infected with mycoplasma pneumoniae (MP)

and explore its molecular mechanism on ‘moistening dryness’. Method: Totally 96 SPF BABL/c mice were randomly divided into normal group

model group

QJT group (0.3 mL/mice) and Azithromycin group (0.3 mL/mice)

n=24 in each group. Except the normal group

the the mice in other 3 groups were induced into MP infection models. On day 3

7

10

14 after modeling

the degree of pathological inflammation in lung tissue of mice was scored; the lung index and ratio of wet and dry was calculated; the ultrastructure of lung tissue was observed by electron microscope; the mRNA expression levels of MPN372 and SP-A in lung tissue were detected by real time fluorescence quantitative polymerase chain reaction(Real-time PCR) and the protein expression of AQP5 was detected by immunohistochemical method and Western blot method. Result: After MP infection

lung pathology score and lung index were increased; the ratio of dry and wet was reduced

and the inflammation was the most serious on day 7 as compared with the normal group; on day 7

microvilli fell off

mitochondria swollen

and alveolar septum thickening could be observed by electron microscope; the mRNA expression of MPN372 in lung tissue of mice was increased and reached the peak on the seventh day

while AQP5 protein expression and the SP-A mRNA expression were decreased and reached the valley on the seventh day (P<0.05). As compared with the model group

the inflammation of lung tissue could be controlled; the inflammatory changes under the electron microscope were relieved; the mRNA expression of MPN372 was decreased

AQP5 protein expression and SP-A mRNA expression were increased after treatment with QJT (P<0.05); SP-A and AQP5 expression levels were significantly different between QJT group and Azithromycin group on day 14 (P<0.05). Conclusion: QJT can embody the effect of “moistening dryness” by reducing the inflammation of the lung

reducing the content of the toxin and increasing the content of the active substance in the lung tissue.