Objective:To investigate the effect of interleukin-13 and interleukin-18 on the expression of nerve growth factor mRNA in bronchial asthma model of rats.Methods:Four Wistar rats were sensitized and challenged with ovalbumin to establish an asthma model

and the rat splenic lymphocytes were isolated and cultured with ConA.The expression of NGF mRNA was detected by reverse transcription-polymerase chain reaction(RT-PCR)

and were observed after the lymphocytes were exogenously added with IL-18 or IL-13.Results:The lymphocytes of the asthma model stimulated by ConA in vitro expressed NGF mRNA in a time-dependent manner.After the lymphocytes had been cultured with IL-13 for 12

24 h and 48 h

IL-13 upregulated the expressions of NGF mRNA in a time-dependent manner and all the NGF mRNA expressions were signif-icantly higher than the basal values at the same time(P<0.05).After 0

10

50μg/L and 100μg/L IL-13 had been added for 24 h

IL-13 upregulated the expressions of NGF mRNA in a dose-dependent manner and the NGF mRNA expressions were all significantly higher than the values of the lower dose IL-13(P<0.05).After the lymphocytes had been cultured with 10μg/L IL-18 for 0

12

24 h and 48 h

IL-18 downregulated the expressions of NGF mRNA in a time-dependent manner and all the NGF mRNA expressions were significantly lower than the basal values at the same tim(eP<0.05).After 0

1

10

and 50μg/L IL-18 have been added for 24 h

IL-18 downregulat-ed the expressions of NGF mRNA in a dose-dependent manner and all the NGF mRNA expressions were significantly lower than the val-ues of the lower IL-18 dose(all P<0.05).Conclusion:In the asthma model of rats

IL-13

one of the Th2 cytokines

can upregulate the expressions of NGF;IL-18

one of the Thl cytokines

and downregulate the expressions of NGF

both in a time-dependent manner and dose-dependent manner.Th1/Th2 cytokine immune imbalance may indirectly induce the airway neurogenic inflammation by regulating the NGF mRNA expression.