Objective: To study the mechanisms of regulating airway neurogenic inflammation in asthma by never growth factor (NGF) and leukemia inhibitory factor (LIF), and then to explore new targets in treating asthma.
Methods: Adult male SD rats (n 36) were divided into the normal group, the asthmatic group and the anti-NGF group at random. There were 12 rats in each group. The asthma models were established by sensitization and challenge with ovalbumin, and the asthma model was treated with anti-NGF. The expression of NGF, LIF and substance P (SP) in lung tissue or in doral root ganglion of each rat were detected by immunohistochemistry and hybridisation in situ.
Results: (1) The gray-levels of NGF protein/NGF mRNA, LIF protein/LIF mRNA in the lungs were 157 +/- 7, 138 +/- 8, 156 +/- 6, 141 +/- 10 for the asthmatic group respectively, 183 +/- 7, 190 +/- 7, 187 +/- 7, 181 +/- 8 for the normal control group respectively, and 177 +/- 6, 169 +/- 9, 178 +/- 7, 172 +/- 9 for the asthmatic group with anti-NGF treatment. There were significant differences in gray-level of NGF protein/NGF mRNA, LIF protein/LIF mRNA among those three groups (t = 19.40, 15.80, 20.38, [corrected] 14.79, all P < 0.01). (2) The gray-levels of NGF protein/LIF protein, SP protein/SP mRNA in the doral root ganglions were 136 +/- 8, 148 +/- 6, 140 +/- 8, 128 +/- 8 for the asthmatic group respectively, 185 +/- 7, 187 +/- 8, 174 +/- 7, 180 +/- 8 for the normal control group respectively, and 164 +/- 6, 170 +/- 8, 163 +/- 9, 157 +/- 7 for the asthmatic group with anti-NGF treatment. There were also significant differences in gray-level of NGF protein/LIF protein, SP protein/SP mRNA among those three groups (t = 29.50, 22.65, 23.12, 28.71, all P < 0.01).
Conclusion: Enhancing the synthesis and release of SP in doral root ganglion may be one of the mechanisms by which NGF and LIF regulate airway neurogenic inflammation in asthmatic rats, and this mechanism can be depressed by the intervention of anti-NGF.