Changes of serum IL-12 and IL-18 levels in asthmatic rat models and their correlation

AIM:To investigate the levels of serum interleukin-12(IL-l2) and interleukin-18(IL-l8) in asthmatic rat,so as to analyze the relation between the two cytokines and airway inflammation.METHODS:Forty-eight Wistar rats were randomly divided into 3 groups:asthma group,dexamethasone group,and normal control group.Rats in asthma and dexamethasone groups were sensitized by intraperitoneal injections of ovalbumin(OVA) and Al(OH)3 on day 0 and 7.From day 8,rats were challenged with 1% OVA aerosol for 30 min,contineously for 7 d.Rats in dexamethasone group were intraperitoneally injected dexamethasone before each challenge.Rats in normal group were only sensitized and challenged with saline instead.Twenty-four hours after last challenge,the measurement of serum IL-12 and IL-18 levels with enzyme linked immunosorbent assay and the count of eosinophils in bronchoalveolar lavage fluid BALF were performed.RESULTS:Serum IL-12 levels in asthma group,dexamethasone group,and normal control group were(53.1±9.6) ng/L,(82.4±8.1)ng/L and(140.1±13.4)ng/L,respectively.Compared with asthma group,IL-12 level in dexamethasone group increased significantly,but it was lower than normal group(P0.01).IL-18 levels in these 3 groups were(353.5±11.9)ng/L,(250.6±8.4)ng/L and(100.5±12.7)ng/L,respectively;they were higher in asthma and dexamethasone groups than in normal group(P0.01).Eosinophils from BALF in the 3 groups were(49.3±4.0)×l05/L,(31.9±3.6)×105/L and(14.8±4.1)×105/L,respectively;they were significantly more in asthma and dexamethasone groups than in normal group(P0.01).Correlation analysis of IL-12,IL-18 levels with eosinophil count in BALF of asthma group rats revealed that there was a negative correlation between IL-12 and eosinophil(r=-0.746,P0.01),while there was a positive correlation between IL-18 and eosinophil(r=0.682,P0.01).CONCLUSION:IL-12 and IL-18 might play roles in the pathogenesis of asthma,and their effects are antagonistic.