Role of necroptosis in hyperoxia-induced acute lung injury in preadolescent rats

Objective To evaluate the role of necroptosis in hyperoxia-induced acute lung injury (ALI) in preadolescent rats. Methods A total of 72 clean-grade healthy male Sprague-Dawley rats, aged 14 days, weighing 40-50 g, were divided into 3 groups (n=24 each) by using a random number table method: control group (group C), hyperoxia-induced ALI group (group ALI) and hyperoxia-induced ALI and necrostatin-1 group (group ALI+ N). The rats of group ALI+ N was intraperitoneally injected with necrostatin-1 1.0 mg/kg once a day for 3 consecutive days.The rats were intraperitoneally injected with dimethyl sulfoxide 0.2 ml/kg once a day for 3 consecutive days in C and ALI groups.The animals were sacrificed at 72 h after inhaling oxygen, and bronchoalveolar lavage fluid (BALF) was collected for determination of interleukin-6 (IL-6) and IL-8 concentrations (by enzyme-linked immunosorbent assay), superoxide dismutase (SOD) activity (by xanthine oxidase method), and malondialdehyde (MDA) concentration (by thiobarbituric acid method). Lung tissues were taken for measurement of wet/dry weight ratio (W/D ratio) and for examination of the pathological changes (with a light microscope) and ultrastructure of lung tissues (with an electron microscope). The injured alveolus rate (IAR) was calculated.The expression of receptor-interacting protein kinase 1 (RIPK1), RIPK3 and mixed-lineage kinase domain-like protein (MLKL) in lung tissues was detected by Western blot. Results Compared with group C, the concentrations of IL-6, IL-8 and MDA in BALF were significantly increased, the activity of SOD in BALF was decreased, the W/D ratio and IAR of lung tissues were increased, the expression of RIPK1, RIPK3 and MLKL in lung tissues was up-regulated (P<0.05), and the pathological damage was accentuated in group ALI.Compared with group ALI, the concentrations of IL-6, IL-8 and MDA in BALF were significantly deceased, the activity of SOD in BALF was increased, the W/D ratio and IAR of lung tissues were decreased, the expression of RIPK1, RIPK3 and MLKL in lung tissues was down-regulated (P<0.05), and the pathological damage was significantly attenuated in group ALI+ N. Conclusion Necroptosis is involved in the pathophysiological process of hyperoxia-induced ALI in preadolescent rats. Key words: Necrosis; Infant; Hyperoxia; Acute lung injury