α1-抗胰蛋白酶对急性呼吸窘迫综合征大鼠机械通气肺损伤的治疗作用

目的评估α1-抗胰蛋白酶(AAT)是否可减轻急性呼吸窘迫综合征(ARDS)大鼠接受机械通气后的呼吸机相关肺损伤(VILI)。方法大鼠随机分为假手术组(S组)、机械通气组(V组)和机械通气/AAT组(VA组)。S组大鼠仅接受麻醉,V组和VA组大鼠接受脂多糖模拟ARDS,然后机械通气4 h。在通气开始时,V组大鼠股静脉给予盐水,VA组大鼠接受股静脉给予AAT。测量氧合指数(PaO2/FiO2)、肺湿/干重比(W/D),检测支气管肺泡灌洗液(BALF)中总蛋白浓度、弹性蛋白酶浓度、中性粒细胞和巨噬细胞计数,检测BALF中的炎症因子和血清中的细胞间黏附分子-1(ICAM-1)和巨噬细胞炎性蛋白-2(MIP-2)浓度,测量肺内氧化应激反应,观察肺组织学损伤和细胞凋亡情况。结果与S组比较,V组和VA组大鼠PaO2/FiO2显著降低,BALF中的蛋白质浓度和肺W/D明显升高,BALF和外周血中炎症因子浓度显著升高,BALF中炎症细胞计数增高;丙二醛(MDA)浓度、髓过氧化物酶(MPO)和还原型辅酶Ⅱ(NADPH)活性显著增加;V组和VA组损伤严重,凋亡细胞数明显增加。与V组比较,VA组PaO2/FiO2显著提高,肺W/D和BALF蛋白浓度降低,BALF中的巨噬细胞和中性粒细胞的数量以及弹性蛋白酶的浓度显著降低;BALF中的肿瘤坏死因子-α、白细胞介素-1β、白细胞介素-6降低,白细胞介素-10升高;外周血中的ICAM-1和MIP-2降低;MDA浓度、MPO和NADPH活性显著降低,组织损伤明显减轻,细胞凋亡数量明显减少;Bax、凝溶胶蛋白和裂解的胱天蛋白酶-3表达降低,但Bcl-2的表达增强(P<0.05)。结论 AAT可减轻ARDS大鼠的VILI。AAT给予的保护作用可能与AAT的抗炎、抗氧化应激反应和抗细胞凋亡作用有关。

Alpha 1-antitrypsin for treatment of ventilator-associated lung injury in acute respiratory distress syndrome rats

Objective To estimate whether alpha 1-antitrypsin(AAT) can reduce ventilator-induced lung injury(VILI) in acute respiratory distress syndrome(ARDS) rats after mechanical ventilation. Methods The rats were randomly divided into 3 groups: a sham(S) group, a mechanical ventilation(V) group and a mechanical ventilation/AAT(VA) group. The rats in the S group only received anesthesia, and the rats in the V and VA groups received endotoxin to simulate ARDS followed by mechanical ventilation for 4 hours. At the beginning of ventilation, the rats in the V group received saline, and the rats in the VA group received AAT. The PaO2/FiO2 ratio and the lung wet/dry(W/D) weight ratio were tested. The total protein and neutrophil elastase concentrations and the neutrophil and macrophage counts in bronchoalveolar lavage fluid(BALF) were tested. Proinflammatory factors in BALF and intercellular cell adhesion molecule-1(ICAM-1) and microphage inflammatory protein-2(MIP-2) in the serum were also detected. Furthermore, the oxidative stress response was detected, and histological injury and apoptosis were evaluated. Results Compared with the S group, PaO2/FiO2 was significantly decreased in the V group and the VA group, the protein concentration in the BALF and the lung W/D weight ratio were significantly increased, the concentration of inflammatory factors in BALF and peripheral blood was significantly increased, and inflammatory cells in BALF also increased. Meanwhile, malondialdehyde(MDA)concentration, myeloperoxidase(MPO) and nicotinamide adenine dinucleotide phosphate(NADPH) activity increased significantly. The V group and VA group were severely damaged, and the number of apoptotic cells increased significantly. Compared with the V group, the PaO2/FiO2 in the VA group significantly increased;the W/D weight ratio and the BALF protein concentration decreased;the number of macrophages and neutrophils in the BALF, and the concentration of elastase significantly decreased;tumor necrosis factor-α, interleukin(IL)-1β, and IL-6 in BALF decreased,IL-10 increased;ICAM-1 and MIP-2 in peripheral blood decreased. At the same time, the MDA concentration, MPO and NADPH activities in the VA group were significantly lower than those in the V group;the tissue damage was significantly reduced, and the number of apoptosis was significantly reduced. In addition, compared with the V group, the expression of Bax, gelsolin and cleaved caspase-3 decreased in the VA group, but the expression of Bcl-2 was increased(all P<0.05).Conclusions AAT can relieve VILI in ARDS rats. The protection conferred by AAT may be associated with the antiinflammatory, antioxidative stress response and antiapoptotic effect of AAT.