Protective mechanism of cysteinyl aspartate-specific protease-3 inhibitors on lung ischemia-reperfusion injury in rats

Objective To investigate the protective effects of cysteinyl aspartate-specific protease (Caspase)-3 inhibitors on lung ischemia-reperfusion injury in rats. Methods 45 models of lung ischemia-reperfusion injury rats were randomly divided into model group, low dose group and high dose group.15 rats were selected as sham operation group. The rats in low dose group and the high dose group were injected with z-VAD-FMK, 5 mg/kg and 15 mg/kg by tail vein respectively and rats in model group and the sham operation group were injected with the normal saline. After 12 h treatment, the oxidative stress index [malondialdehyde (MDA), superoxide dismutase (SOD) and reactive oxygen species (ROS)] and inflammatory factors [interleukin (IL)-1β, IL-6 and tumor necrosis factor-α (TNF-α) ] were analyzed. The related protein levels of apoptosis [apoptosis inducing factor (AIF), Caspase-3, B cell lymphoma/leukemia-2 (bcl-2) and bcl-2 associated X protein (bax)] were analyzed by Western blotting. The level of apoptosis in lung tissue was analyzed by TdT-mediated dUTP nick end labeling (TUNEL) staining. Results Compared with the control group, the levels of MDA and ROS significantly increased in the model group, low-dose group and high dose group, while the level of SOD significantly decreased. Compared with the model group, the levels of MDA and ROS in the low dose group and the high dose group obviously decreased, while the level of SOD increased significantly. Compared with the sham group, TNF-α, IL-1β and IL-6 in model group, low dose group and high dose group significantly increased. Compared with model group, TNF-α, IL-1β and IL-6 in low dose group and high dose group significantly reduced. Compared with the sham operation group, AIF, Caspase-3 and bax protein level and cell apoptosis index in model group, low dose group and high dose group significantly increased and bcl-2 levels significantly increased; Compared with Sham group (3.43±0.67), cell apoptosis indexs in model group, low dose group and high dose group (25.32±3.21, 17.39±2.97 and 11.33±2.56) significantly increased (P=0.000). Compared with the model group, cell apoptosis indexs in low dose group and high dose groupsignificantly reduced (P=0.000). Compared with low dose group, cell apoptosis indexs in high dose groupsignificantly reduced (P=0.000). Conclusion Caspase-3 inhibitor z-VAD-FMK can significantly reduce oxidative stress, inflammation and lung apoptosis, and play a protective role in lung tissue. Key words: Cysteinyl aspartate-specific protease-3 inhibitors; Ischemia reperfusion injury; Oxidative stress; Inflammation; Apoptosis