Methods 36 female C57BL mice were equally randomly divided into three groups:NA group, NA treated with AG490（NAAG）group, and normal control(NC) group.The above mice were treated as fowllow: Mice in NA group or NAAG group were sensitized by a mixture consists 100ug of ovalbumin(OVA,Grade V) and 0.1ug of lipopolysaccharide(LPS) via airway delivery on the experiment days 0，6，13. Besides, NAAG mice were injected intraperitoneally with AG490 in the dose of 500ug three times a week. In the case of intervention of AG490 encountering sentisization with OVA and LPS,we injected the mice with AG490 30 minutes before they were sensitised through airway dilivery.Once the sensitization stage were finished, mice in NA group and NAAG group were challenged consecutively by exposure to a 1% OVA aerosol produced by an inhalation delivery system for one hour once a day, from day 21 to 22.At the time of 24 hours after the last challenge, all mice were disposed and relative index were measured in time.Bronchoalveolar lavage fluid(BALF) was collected and total white blood cell count was determined on blood cell counting plate, and classification of proportion was determined under the optical microscope with Diff-Quick staining. Lung tissue was separated and HE and PAS stain were done to obseve pathologic changes and goblet cell hyperplasia under the optical microscope. BALF IL-17A cytokine concentration was determined by means of enzyme-linked-immunosorbent serologic assay(ELISA).Percentages of Th17 cells and Treg cells in the lung tissue were determined by means of Flow cytometry(FCM).
Results BALF total cell count, neutrophil percentages and eosinophil percentages count in the NAAG group were lower than that of the NA group (P<0.05), but were still higher than that of the NC group(each P<0.05)； Lung tissue pathologic changes and goblet cell hyperplasia were markedly improved in NAAG group compared with that of the NA group,but there were still significant change compared with that of the NC group；BALF IL-17 cytokine concentrations in the NAAG group was lower than that of the NA group, but was still higher than that of the NC group(each P<0.05)；Th17 cell percentage in the lung of the NAAG group was lower than that of the NA group, but was still higher than that of the NC group(each P<0.05).Treg cell percentage in the lung of the NA group was higher than that of the NAAG group (each P<0.05).
Conclusions Airway inflammation in the mouse model of neutrophilic asthma was improved by early treatment of AG490,which probably via down-regulating the espression of Th17 cells and up-regulating the espression of Tregs.