胆碱能抗炎通路对大鼠呼吸机相关性肺损伤的影响

目的 研究胆碱能抗炎通路对呼吸机相关性肺损伤(VILI)的影响.方法 36只SD大鼠按随机数字表法分为自主呼吸对照组、机械通气组、烟碱治疗组,每组12只.采用大潮气量(VT)通气制作大鼠VILI模型.于机械通气前10 min腹腔注射烟碱生理盐水2 mg/kg,其余两组注射等量生理盐水.各组大鼠均行血流动力学和动脉血气监测;通气2 h处死大鼠取肺组织,测定肺湿/干重(W/D)比值和髓过氧化物酶(MPO)活性,采用酶联免疫吸附法(ELISA)测定支气管肺泡灌洗液(BALF)中白细胞介素-8(IL-8)含量及肺组织匀浆细胞间黏附分子-1(ICAM-1)含量;苏木素-伊红(HE)染色观察肺组织病理改变,按修改后弥漫性肺泡损伤评分系统(DAD)进行评分.结果 机械通气期间,机械通气组和烟碱治疗组动脉血pH值呈升高趋势,动脉血氧分压(PaO2)、动脉血二氧化碳分压(PaCO2)、平均动脉压(MAP)均呈下降趋势.机械通气2 h,烟碱治疗组PaO2(mm Hg,1 mm Hg=0.133 kPa)显著高于机械通气组(85±4比76±3,P<0.05).机械通气组肺W/D比值和MPO活性显著高于对照组W/D比值:5.66±0.33比4.53±0.21,P<0.01;MPO(U/g):1.73±0.50比0.89±0.17,P<0.05];烟碱治疗组肺W/D比值(5.02±0.37)和MPO活性(1.11±0.33)显著低于机械通气组(均P<0.05).与对照组比较,机械通气组和烟碱治疗组DAD评分(分:10.40±1.85、7.90±1.67比1.60±1.20)、IL-8(ng/L:1 625.3±271.7、965.5±310.5比428.5±120.6)及ICAM-1(μg/L:589.4±87.5、452.5±89.3比247.5±73.7)显著升高(均P<0.01),但烟碱治疗组各指标明显低于机械通气组(P<0.05或P<0.01).结论 胆碱能抗炎通路可抑制VILI大鼠肺组织中IL-8、ICAM-1的表达,减少中性粒细胞在肺内的黏附与渗出,从而减轻肺损伤.

Effects of cholinergic anti-inflammatory pathway on ventilator-induced lung injury in rats

Objective To investigate the effects of cholinergic anti-inflammatory pathway on ventilator-induced lung injury (VILI) in rats. Methods Thirty-six healthy Sprague-Dawley (SD) rats were randomly divided into three groups: control group, in which rats did not receive ventilation; high-tidal volume (HVT) ventilation group; nicotine treatment (HVT+nicotine) group, in which rats received intraperitoneal injection of nicotine (2 mg/kg) 10 minutes before HVT ventilation; equal amount of normal saline was given to rats in other two groups. A rat model of VILI was reproduced by volume-controlled mechanical ventilation with HVT. Hemodynamic parameters were measured throughout the study period. Arterial blood gases were measured every 1 hour. After maintaining ventilation for 2 hours, rats were sacrificed and lung tissue specimens were harvested. Lung wet-dry weight ratio (W/D) and myeloperoxidase (MPO) activity were measured. Interleukin-8 (IL-8) level in bronchoalveolar lavage fluid (BALF) and intercellular adhesion molecule-1 (ICAM-1) level in lung tissue homogenate were measured by enzyme-linked immunosorbent assay (ELISA), respectively. After hematoxylin and eosin (HE) staining, pathological examination of lung tissue was performed, and diffuse alveolar damage (DAD) score was estimated. Results Mean pH of arterial blood in HVT group and HVT+nicotine group tended to be higher than the baseline value during the ventilation. Mean partial pressure of oxygen in arterial blood (PaO2), mean partial pressure of carbon dioxide in arterial blood (PaCO2), and mean arterial pressure (MAP) in HVT group and HVT+nicotine group were lower than baseline value during the ventilation. Mean PaO2 (mm Hg, 1 mm Hg=0.133 kPa) in HVT+nicotine group was significantly higher than that in HVT group after 2 hours of ventilation (85±4 vs. 76±3, P<0.05). Mean W/D ratio and mean MPO activity in HVT group were significantly higher than those in control group W/D ratio: 5.66±0.33 vs. 4.53±0.21, P<0.01; MPO (U/g): 1.73±0.50 vs. 0.89±0.17, P<0.05]. Mean W/D ratio (5.02±0.37) and mean MPO activity (1.11±0.33) in HVT+nicotine group were significantly lower than those in HVT group (both P<0.05). Compared with control group, DAD scores in HVT group and HVT+nicotine group (10.40±1.85, 7.90±1.67 vs. 1.60±1.20), IL-8 concentration (ng/L: 1 625.3±271.7, 965.5±310.5 vs. 428.5±120.6) and ICAM-1 concentration (μg/L: 589.4±87.5, 452.5±89.3 vs. 247.5±73.7) were significantly higher (all P<0.01). But DAD score, IL-8 concentration, ICAM-1 concentration in HVT+nicotine group were significantly lower than those in HVT group (P<0.05 or P<0.01). Conclusion Activation of cholinergic anti-inflammatory pathway can protect the lung against VILI by suppressing IL-8 and ICAM-1 expression, inhibiting neutrophil aggregation and infiltration.