大剂量维生素C对哮喘小鼠肺部感染的影响

Influence of Mega-dose vitamin C on lung inlammation in mouse asthma model

目的观察维生素c对小鼠哮喘模型中肺部感染的作用。方法用100Ixg卵白蛋白诱导小鼠哮喘，每组小鼠腹腔内注射3mg或5mg[溶于100ul磷酸盐缓冲液（PBS）]维生素c，或同体积的PBS，每组8只小鼠。第24天用气道阻力描计法测定气道阻力。小鼠第25天在深度麻醉下处死得到支气管肺泡灌洗液和肺组织，对肺部炎性细胞总数以及血管和支气管周围炎性细胞浸润层数进行计数。用酶联免疫吸附试验（ELISA）评估其对Th1／Th2平衡的影响。结果在哮喘模型中，只注射PBS组中的气道阻力均明显高于正常对照组（P〈0．05）。6．25、12．50、25．00g／L维生素c治疗乙酰胆碱激发哮喘组与正常对照组气道阻力相似。而50g/L乙酰胆碱激发哮喘组中使用维生素c治疗明显高于正常对照组，但低于PBS处理组，维生素C可以降低呼吸道对乙酰胆碱的敏感性（P〈0．05）。在实验组支气管肺泡灌洗液细胞中巨噬细胞和嗜酸细胞在PBS组及维生素c治疗组细胞中分别占33．6％和63．1％、20．2％和63．1％。维生素c可减少支气管肺泡灌洗液中炎性细胞的数量（P〈0．05），并可减少血管周围炎性细胞（5．0±2．9比6．4±1．5，P〈0．05）及细支气管周围炎性细胞（1．2±0．9比2．6±1．8，P〉0．05）浸润厚度。维生素C不能调节Th1／Th2之间的平衡（P〉0．05）。结论维生素c虽不能转换Th1／Th2的之间的平衡，但有明显抗炎作用。

Objective To explore whether vitamin C exerted beneficial effects in asthma animal model. Methods Asthma was induced in mice by sensitizing and challenging with 100 ug ovalbumin. mice were given an intraperitoneal injection of either 3 or 5 mg vitamin C dissolved in 100 ul PBS or of a same volume of PBS. Each experimental group consisted of 8 mice. On day 24, plethysmography was done. Mice were sacrificed on day 25, bronchoalveolar lavage fluid （BALF） and lung tissue were obtained immediately after sacrifice, the total number of lung inflammatory cells and the layers of perivascular and inflammatory peribronchiolar cells were counted, and enzyme linked immunosorbent assay （ELISA） was used to detect the influence on Th1/Th2 balance. Results Airway resistances in PBS-injected asthma group were significantly higher with all concentrations of methacholine （ P 〈 0. 05 ）, vitamin C-treated asthma group showed similar resistances to those of normal control group with 6. 25, 12. 50, 25. 00 g/L of methacholine, however, resistance with 50 g/L of methacholine was elevated compared to normal control group. BALF cells were mainly composed of macrophages and eosinophils which comprised 33.6% and 63.1%, and 20. 2% and 65. 4% of total cells in PBS-treated and vitamin C-treated groups respectively These Vitamin C did not modulate Th1/Th2 balance in asthma model （P 〉 0. 05）. However, it decreased airway hyperreactivity to methacholine （ P 〈 0. 05 ）, decreased inflammatory cell numbers in brochoalveolar lavage fluid （ P 〈 0. 05 ）, and moderate reduction of perivascular （5.0 -＋ 2. 9 vs PBS control group 6.4 ± 1.5, P 〈 0. 05） and peribronchiolar （ 1.2 ± 0. 9 vs PBS control group 2. 6 ± 1.8, P 〉 0.05 ） inflammatory cell infiltration. Conclusion Even though vitamin C did not show any Th1/Th2 shifting effects in this experiment, it still exerted moderate anti-inflammatory effects.