[Effect of Th1/Th2 cytokine immune imbalance on the expression of nerve growth factors in asthma].

Objective: To explore the effect of Th1/Th2 cytokines on the expression of nerve growth factor(NGF)in splenic lymphocytes in asthmatic model.

Methods: Four SD rats were sensitized and challenged with ovalbumin to establish an asthmatic model, and the rat splenic lymphocytes were isolated and cultured with ConA. The expressions of NGF mRNA were detected by reverse transcription-polymerase chain reaction (RT-PCR), and were observed after the lymphocytes were exogenously added with interferon-gamma(IFN-gamma) or interleukin-4 (IL-4).

Results: The lymphocytes of the asthmatic model stimulated by ConA in vitro expressed NGF mRNA in a time-dependent manner. After the lymphocytes had been cultured with IL-4 for 12 h, 24 h, 36 h, and 48 h, 50 microg/L IL-4 upregulated the expressions of NGF mRNA in a time-dependent manner and all the NGF mRNA expressions were significantly higher than the basal values at the same time(all Ps<0.01). After 0, 10, 50, and 100 microg/L IL-4 had been added for 24 h, IL-4 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-4(all Ps<0.05). After the lymphocytes had been cultured with 10 mug/L IFN-gamma for 0 h, 12 h, 24 h, 36 h, and 48 h, IFN-gamma 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 time(all Ps<0.01). After 0, 1, 10, and 50 microg/L IFN-gamma have been added for 24 h, IFN-gamma downregulated the expressions of NGF mRNA in a dose-dependent manner and all the NGF mRNA expressions were significantly lower than the values of the lower IFN-gamma dose(all Ps<0.05).

Conclusion: In the splenic lymphocytes of asthmatic rats, IL-4, one of the Th2 cytokines, can upregulate the expressions of NGF; IFN-gamma, one of the Th1 cytokines, can downregulate the expressions of NGF both in a time-dependent manner and in a dose-dependent manner. Th1/Th2 cytokine immune imbalance may indirectly induce the airway neurogenic inflammation by regulating the NGF mRNA expression.