Abstract:

Abstract:Objective To measure the level of interleukin-15 (IL-15) in serum and its expression in lung tissues，and analyze the correlations between IL-15 and IL-4，IFN-γ，eosinophil(Eos)，and explore the effect of IL-15 on bronchial asthma.Methods  Thirty femal BALB/C mice were randomly divided into three group (n=10),group A (asthma model),group B (corticosteroid treatment) and group C (normal control).All mice were killed 24　h after final OVA challenge.Blood were obtained for measurement of serum IgE，IL-4，IFN-γ and IL-15 levels by enzyme-linked immunoabsorbent assay (ELISA).Bronchoalveolar lavage fluid (BLAF) was collected for  Eos  count.The left lungs were isolated for pathological examination.The lung sections were stained with hematoxylin and eosin (HE).The expressions of IL-15 in lung tissues were measured by immunohistochemical SP method.Results ① The mouse asthma model appeared ethological changes  specific to asthma，the Eos count in BALF was increased，and IgE and IL-4 levels in serum were also increased compared with control group(P<0.01）.The lung tissues also appeared typical pathological changes and the inflammation cell score elevated.The level of serum IFN-γ was decreased（P<0.01）.Correlation analysis showed negative relationship between IL-4 and IFN-γ（r=－0.859，P<0.01），there existed Th1／Th2 imbalance.② The level of serum IL-15 in group A (77.97 ng·L-1±2.75 ng·L-1) was higher than that in group C (34.63 ng·L-1±1.44 ng·L-1)（P<0.01）.There were positive correlations between the  serum IL-15 and IgE，IL-4 levels(r= 0.681，P<0.01；r= 0.738，P<0.01），while the  serum IL-15 level had no correlation with IFN-γ. ③ The expression of IL-15 in lung tissues in group A was higher than that in group C (P<0.01）.There was a positive correlation between the expression of IL-15 in lung tissues and the Eos count in BALF (r= 0.787，P<0.01）.④ In mice treated with inhaled budesonide (group B），the Eos count in BALF ，the level of serum IgE ，the level of serum IL-15  and the expression of IL-15 in lung tissues were lower than those in group A（all P<0.01）.Conclusion IL-15 might contribute to promoting Th2 cells to secret cytokine IL-4，while not contribute to promoting Th1 cells to secret cytokine IFN-γ.IL-15 might be involved in the elevation of Eos and IgE，which suggests that IL-15 might be involved in the chronic inflammation of bronchial asthma.The inflammation of bronchial asthma could be inhibited by inhaled glucocorticoid.

Key words: asthma；disease models,animal；interleukin-15；Th1／Th2；eosinophil；glucocorticoid