Effects of interleukin-1β and Astragalus on the expression of insulin-like growth factor-1 in cultured airway epithelial cells

Objective To investigate the effects of IL-1β and astragalus on the expression of IGF-1 in cultured airway epithelial cells by detecting IGF-1 protein in rabbit airway epithelial cells treated with IL-1β alone and in combination with astragalus. Methods The cultured airway epithelial cells in vivo were randomly divided into treatment groups and normal control groups. Three series of experiment were designed as follows: ① The treatment group was treated with 1 ng/ml IL-1β. After 4,8,16,24 and 48 hours,culture supernatant and cell-coated glass slips were collected from all the groups;② Treatment group was randomized into subgroups treated with IL-1β at levels of 0.05,0.1,1 and 10 ng/ml respectively,while normal control group were treated with equal volume of culture medium. After 16 hours,culture supernatant and cell-coated glass slips were collected from all the groups. ③ Treatment group was randomized into subgroups treated with astragalus at levels of 50,200,500 mg/ml,respectively,as added on 10 ng/ml IL-1β treatment,while the control group were treated with 10 ng/ml IL-1β alone. After 16 hours,culture supernatant and cell-coated glass slips were collected from all the groups. For all experiment series,the expression of IGF-1 was measured by double antibody sandwich ELISA and immunohistochemistry. The time-and/or dose-effects of IL-1β and astragalus on expression of IGF-1 in cultured airway epithelial cells were evaluated. Results ① The expression levels of IGF-1 in airway epithelial cells and culture supernatant from the group treated with 1ng/ml IL-1β were 0.577±0.036 and 0.141±0.017 at 16 h,0.537±0.041 and 0.114±0.032 at 24 h,0.527±0.067 and 0.107±0.027 at 48 h,respectively,significantly higher than those from normal control groups (0.259±0.012 and 0.054±0.014 at 16 h,0.260±0.012 and 0.053±0.005 at 24 h,0.267±0.004 and 0.056±0.009 at 48 h,respectively) (all P﹤0.05). Within the treatment group,level of IGF-1 increased with adding of IL-1β until peaking at 16 hour,and tended to show a plateau thereafter,indicating no significant differences among 16,24 and 48 hours. ② The expression levels of IGF-1 in airway epithelial cells and culture supernatant were 0.328±0.012 and 0.084±0.021 in the 0.1 ng/ml IL-1β group,0.471±0.018 and 0.113±0.019 in the 1 ng/ml IL-1β group,0.569±0.031 and 0.145±0.021 in the 10 ng/ml IL-1β group,respectively,higher than those from normal control group (0.260±0.019,0.051±0.012) and 0.05ng/ml IL-1β group (0.282±0.027,0.053±0.031) (all P0.05). The level of IGF-1 was significantly higher in the 10 ng/ml IL-1β group than in the other groups (all P0.05). ③ The expression levels of IGF-1 in airway epithelial cells and culture supernatant were 0.454±0.050 and 0.104±0.013 in 50 mg/ml astragalus group,0.391±0.080 and 0.085±0.014 in 200 mg/ml astragalus group,0.296±0.074 and 0.073±0.014 in 500 mg/ml astragalus group,respectively,much lower than those in 10 ng/ml IL-1β group (0.561±0.034 and 0.141±0.161) (all P0.05). The levels of IGF-1 from 500 mg/ml astragalus group were significantly higher than in 50 mg/ml astragalus group and 10 ng/ml IL-1β group (all P0.05),but were not different from those in 200 mg/ml astragalus group (P0.05). Conclusion IL-1β appeared to accelerate airway remodeling by enhancing IGF-1 expression. Such effects may be inhibited by astraglaus,which may be attributed to its anti-inflammatory action.