激素对哮喘小鼠气道黏液分泌作用的研究

目的研究糖皮质激素对小鼠哮喘模型气道黏液过度分泌的作用及机制。方法将24只 BALB/c 小鼠随机分为对照组、哮喘组和哮喘+地塞米松组,每组8只。各组小鼠于末次激发24 h 后进行麻醉,留取不同标本,观察支气管肺泡灌洗液(BALF)中细胞总数和嗜酸性粒细胞数,AB-PAS 染色了解气道杯状细胞变化,用 RT-PCR 和免疫组织化学染色分别检测肺组织黏蛋白基因MUC5AC mRNA 和蛋白、白细胞介素4(IL-4)mRNA。结果与对照组相比,哮喘组 BALF 嗜酸性粒细胞和气道杯状细胞均明显增多,而哮喘+地塞米松组明显减少;哮喘组肺组织 MUC5AC mRNA(0.5341±0.0303)和蛋白(0.1906±0.0008)、IL-4 mRNA(0.6265±0.0932)均较对照组(分别为0.1994±0.0128、0.1194±0.0007和0.2389±0.0289)明显增加(P 均<0.01),哮喘+地塞米松组(分别为0.2729±0.0345、0.1456±0.0003和0.2424±0.0260)均明显高于哮喘组(P 均<0.05),但哮喘+地塞米松组 IL-4 mRNA 和对照组差异无统计学意义(P>0.05),MUC5AC mRNA和蛋白较对照组均明显降低(P 均<0.01)。结论糖皮质激素可减轻哮喘小鼠肺组织炎症,并可能通过下调MUC5AC 和 IL-4表达在气道黏液过度分泌中起治疗作用。

Effects of glucocorticoid on airway mucus secretion in asthma: experiment with asthmatic mouse model

OBJECTIVE: To study the effects of glucocorticoid on airway mucus secretion in asthma. METHODS: Twenty-four BALB/c mice were randomly divided into 3 equal groups: asthma group ovalbumin (OVA) and aluminum hydroxide were injected intraperitoneally on day 0 and day 14 so as to establish mouse asthma model and aerosol inhalation of OVA PBS was conducted for 30 min on the days 21, 22, and 24], asthma + dexamethasone group (OVA and aluminum hydroxide were injected intraperitoneally on days 0 and 14, aerosol inhalation of OVA PBS was conducted for 30 min on the days 21, 22, and 24, and dexamethasone was injected intraperitoneally 1 hour before the aerosol inhalation), and control group (aerosol inhalation of PBS was conducted instead). Twenty-fours hours after the last exposure the mice were anesthetized deeply and their left lungs were excised to collect the bronchoalveolar lavage fluid (BALF) to calculate the numbers of total cells and eosinophils, then Alcian blue/periodic acid-Schiff staining and immunohistochemistry of the air passage were conducted to measure the expression levels of MUC5AC mRNA and protein and interleukin-4 (IL-4) mRNA. RESULTS: The numbers of total cells in the BALF of the asthma group were (12.50 +/- 0.14) x 10(9)/L and (1.12 +/- 0.10) x 10(9)/L respectively, both significantly higher than those of the control group, (6.49 +/- 0.05) x 10(9)/L and (0.05 +/- 0.02) x 10(9)/L respectively (both P < 0.01), and were significantly higher than those of the asthma + dexamethasone group, (6.68 +/- 0.03) x 10(9)/L and (0.06 +/- 0.01) x 10(9)/L respectively too (both P < 0.01). The levels of MUC5AC mRNA, MUC5AC protein, and IL-4 mRNA of the asthma group were 0.5341 +/- 0.303, 0.1906 +/- 0.0008, and 0.6265 +/- 0.0932 respectively, all significantly higher than those of the control group (0.1994 +/- 0.0128, 0.1194 +/- 0.0007, and 0.2389 +/- 0.0289 respectively, all P < 0.01), and those of the asthma + dexamethasone group (0.2729 +/- 0.0345, 0.1456 +/- 0.0003, and 0.2424 +/- 0.0260, all P < 0.05). The MUC5AC protein expression and mRNA expression, and IL-4 mRNA expression of the asthma group were 0.1906 +/- 0.0008, 0.5341 +/- 0.0303, and 0.6265 +/- 0.0932 respectively, all significantly higher than those of the control group (0.1194 +/- 0.0007, 0.1994 +/- 0.0128, and 0.2398 +/- 0.0289 respectively, all P < 0.01). The MUC5AC protein expression and mRNA expression, and IL-4 mRNA expression of the asthma + dexamethasone group were 0.1456 +/- 0.0003, 0.2729 +/- 0.0345, and 0.2424 +/- 0.0260 respectively, all significantly lower than those of the asthma group (all P < 0.01). The MUC5AC protein expression and mRNA expression of the asthma + dexamethasone group were still significantly higher than those of the control group (both P < 0.01), however, the IL-4 mRNA expression of the asthma + dexamethasone group was not significantly different from that of the control group (P > 0.05). CONCLUSION: Relieving the inflammation, glucocorticoid may play a role in the treatment of excessive mucus production through down-regulating the expression of MUC5AC and of IL-4.