Objective: To explore the effects of glycyrrhizic acid (GA) on Extracellular regulated protein kinases (ERK1/2) and p38 mitogen-activated protein kinases (p38 MAPK) signaling pathways in a murine model of asthma. Methods: Sixty female BALB/c mice were randomly divided into 6 groups (n=10 each): a control group, an asthmatic group, two treatment groups with low and high doses of GA, U0126 group and SB203580 group. Within 24 hours after the last OVA challenge, histological studies of lung were conducted with the hematoxylin and eosin staining (HE) and alcian blue-periodic acid-Schiff (AB-PAS), the relative protein expression of ERK1/2 and p38 MAPK were detected by immunohistochemistry and Western blotting in vivo. CD4(+) T cells were purified from spleens of OVA-sensitized and challenged mice by using the Mouse CD4 Cell Positive Isolation Kit and incubated with anti-CD3 mAb (1 μg/ml) in the presence of various concentrations of GA (10 and 100 μg/ml), U0126 (10 μmol/L) or SB203580(10 μmol/L). After 72 h of incubation, the relative protein expression of ERK1/2 and p38 MAPK of CD4(+) T cells were detected by Western blotting in vitro. Results: The asthmatic mice induced infiltration of inflammatory cells around airways and blood vessels, airway goblet cell hyperplasia and mucus production. Administration of GA at a dose of 100 mg/kg, U0126 or SB203580 significantly reduced the infiltration of inflammatory cells in the peribronchial areas and goblet cell hyperplasia compared with the asthmatic mice. The protein expressions of p-ERK1/2 were lower in GA at a dose of 100 mg/kg (0.090±0.022) and U0126 group (0.072±0.017) than those in asthmatic group (0.143±0.022) (all P<0.05). The protein expressions of p-p38 MAPK were lower in GA at a dose of 100 mg/kg (0.072±0.019) and SB203580 group (0.061±0.015) than those in asthmatic group (0.121±0.022) (all P<0.05) by immunohistochemistry. Compared with asthmatic group (0.783±0.133, 0.649±0.095), the protein expressions of p-ERK1/2 and p-p38 MAPK in GA at a high dose group (0.385±0.186, 0.275±0.089) and in U0126 group (0.117±0.051) or in SB203580 group (0.108±0.043) were decreased by Western blotting (all P<0.05). The expressions of p-ERK1/2 in CD4(+) T cells after 72 h incubation were lower in 100 μg/ml concentrations of GA (0.579±0.184) and group U0126 (0.249±0.082) and the expressions of p-p38 MAPK were much lower in 100 μg/ml concentrations of GA (0.445±0.081) and group SB203580 (0.249±0.082) compared with those in group CD3 (1.028±0.147, 0.902±0.107) (all P<0.05). Conclusion: ERK1/2 and p38 MAPK signaling pathways are activated in asthmatic mice and GA may negative regulate this activation.
目的： 探讨甘草酸对支气管哮喘(简称哮喘)小鼠细胞外调节蛋白激酶(ERK)1/2和p38丝裂原活化蛋白激酶(MAPK)信号通路的影响。 方法： (1)体内实验：BALB/c小鼠60只按随机数字表法随机分为对照组、哮喘组、低浓度甘草酸(25 mg/kg)组、高浓度甘草酸(100 mg/kg)组、U0126(0.1 mg/kg)干预组及SB203580(5 mg/kg)干预组各10只。末次激发24 h后，肺组织HE和AB－PAS染色，免疫组化法和Western印迹法检测肺组织ERK1/2和p38 MAPK的相对表达量。(2)体外实验：磁珠分选哮喘小鼠脾脏CD4(＋)T细胞，经抗CD3单抗(1 μg/ml)(CD3组)预处理后，分别以不同浓度甘草酸(10 μg/ml、100 μg/ml)、U0126(10 μmol/L)及SB203580(10 μmol/L)干预，培养72 h后，Western印迹法检测CD4(＋)T细胞ERK1/2和p38 MAPK的相对表达量。 结果： (1)体内实验：哮喘组气管黏膜充血水肿，血管壁及管周有大量炎症细胞浸润，气管上皮杯状细胞化生，管腔黏液高分泌，高浓度甘草酸组和U0126及SB203580干预组的气道炎症反应和上皮杯状细胞化生程度较哮喘组轻。免疫组化结果：高浓度甘草酸组和U0126干预组肺组织p－ERK1/2表达(0.090±0.022、0.072±0.017)均显著低于哮喘组(0.143±0.022)(均P<0.05)；高浓度甘草酸组和SB203580干预组肺组织p－p38 MAPK表达(0.072±0.019、0.061±0.015)均显著低于哮喘组(0.121±0.022)(均P<0.05)。Western印迹法结果：高浓度甘草酸组和U0126干预组肺组织p－ERK1/2表达(0.385±0.186、0.117±0.051)均显著低于哮喘组(0.783±0.133)(均P<0.05)；高浓度甘草酸组和SB203580干预组肺组织p－p38 MAPK表达(0.275±0.089、0.108±0.043)均显著低于哮喘组(0.649±0.095)(均P<0.05)。(2)体外实验：高浓度甘草酸组和U0126干预组p－ERK1/2表达(0.579±0.184、0.249±0.082)均显著低于CD3组(1.028±0.147)(均P<0.05)；高浓度甘草酸组和SB203580干预组p－p38 MAPK表达(0.445±0.081、0.249±0.082)均显著低于CD3组(0.902±0.107)(均P<0.05)。 结论： 哮喘小鼠存在ERK1/2和p38 MAPK信号通路激活，甘草酸可抑制哮喘小鼠ERK1/2和p38 MAPK信号通路。.
Keywords: Asthma; Extracellular regulated protein kinases; Glycyrrhizic acid; Mice; p38 mitogen-activated protein kinases.