NGF对哮喘豚鼠下呼吸道及内脏感觉传入部位IL-1β表达的影响

为探讨神经生长因子(NGF)在哮喘发病中的作用及其神经免疫调节机制,本研究应用免疫组织化学方法检测各组豚鼠下呼吸道和内脏感觉传入部位白介素-1β(IL-1β)免疫反应的变化。用Western blot方法分别检测各组豚鼠肺、C7~T5段脊神经节和相应节段脊髓背角NGF和IL-1β的表达。用Luzex-F实时图像分析系统和凝胶成像分析系统分别对结果进行图像分析。免疫组织化学结果显示(染色反应强度用灰度值表示):生理盐水组与单纯致敏组豚鼠IL-1β阳性免疫反应产物的平均灰度值没有显著差异(P>0.05);与这两个对照组相比,哮喘豚鼠气道上皮、肺内炎性细胞、血管平滑肌内的神经末梢、C7~T5段脊神经节及相应节段脊髓背角内IL-1β阳性反应产物的平均灰度值均明显降低(P<0.01);在哮喘+NGF抗体组(鼻腔吸入NGF抗体),上述部位内IL-1β阳性反应产物的平均灰度值均明显高于哮喘组(P<0.01)。Western blot结果显示:与生理盐水组和单纯致敏组比较,哮喘组豚鼠肺、C7~T5段脊神经节及相应节段脊髓样品中IL-1β或NGF目标带的IDV(integrated density value)与内参照IDV的比值均明显升高(P<0.01),而哮喘+NGF抗体组上述部位样品中IL-1β或NGF目标带的IDV与内参照IDV的比值均明显低于哮喘组(P<0.01),表明NGF可上调IL-1β的表达。这些结果提示NGF诱发IL-1β的表达可能是NGF参与哮喘发病的机制之一,NGF抗体抑制哮喘时下呼吸道和内脏感觉传入部位IL-1β的表达可能是治疗哮喘的新途径。

THE UPREGULATIVE EFFECT OF NGF ON IL-1 β IN THE LOWER RESPIRATORY TRACT AND VISCEROSENSORY AFFERENT SITES OF THE ASTHMATIC GUINEA PIG

To explore the role and neuroimmune mechanism of nerve growth factor (NGF) in the pathogenesis of asthma. The changes of interleukin-1β (IL-1β) immunoreactivity were investigated by means of immunohistochemistry in lower respiratory tract and viscerosensory afferent sites of the guinea pigs among different groups. The expression of NGF and IL-1β were observed respectively by Western blot in the lung, C_7-T_5 spinal ganglia and the corresponding spinal dorsal horn of all the groups. The results were analyzed by the Luzex-F real time image analysis system and the gel imaging analysis system respectively. Immunohistochemistry results showed that The intensity of staining reactivity, determined by means of an image analysis system, was expressed as grey value (0-black to 255-white)]: there was no obvious difference in the mean grey values of IL-1β positive products between normal saline control group and simply sensitized group (P>0.05). The mean grey values of IL-1β positive products decreased significantly in the lower respiratory tract, nerve terminals in vascular smooth muscle, C_7-T_5 spinal ganglia and corresponding spinal dorsal horn of the asthmatic guinea pigs compared with the normal saline control group and the simply sensitized group (P<0.01). However, the mean grey values of IL-1β positive products in the lower respiratory tract, nerve terminals in vascular smooth muscle, C_7-T_5 spinal ganglia and corresponding spinal dorsal horn was much higher in NGF antibody group (inhalation of NGF antibody into nasal cavity) than in asthmatic group (P<0.01). Western blot results showed that: compared with normal saline control group and simply sensitized group, the ratios between integrated density value (IDV) for IL-1β or NGF protein band and IDV for β-actin protein band increased markedly in the lung, C_7-T_5 spinal ganglia and the corresponding spinal dorsal horn of asthmatic group (P<0.01), however, the ratios between IDV for IL-1β or NGF protein band and IDV for β-actin protein band of NGF antibody group reduced markedly in comparison with asthmatic group (P<0.01), indicating that NGF can upregulate the expression of IL-1β. The present results indicate that the overexpression of IL-1β induced by NGF might be one of the mechanisms for the involvement of NGF in the pathogenesis of asthma, and inhibitory expression of IL-1β by NGF antibody in the lower respiratory tract and viscerosensory afferent sites might be a new route for the prevention and treatment of the bronchial asthma.