Activation of Ubiquitin-Proteasome Pathway in Lung Injury Rat Induced by Hyperoxia in Early Stage

Objective To explore the extent of lung injury induced by hyperoxia,and the activity of ubiquitin-proteasome pathway(UPP) in pathophysiological progress of lung tissue in early stages.Methods Adopted completely random design,20 SD rats were divided into hyperoxia group and air control group.For the air control group,the oxygen concentration exiting the cages was analyzed with oxygen monitor and oxygen concentration remained at 210 mL/L for 72 hours;while in the hyperoxia group,the condition changed into high-density oxygen(950 mL/L) for 72 hours to estimate the hyperoxia lung injury in rats model.The contents linked morphology as pathological classification in gross finding,pathological score of lung injury and the index of pneumonedema-the ratio of moist to dry weight of lungs were mea-sured.The expressions of ubiquitin protein and the activity of proteasome 20 S and the active statement of ubiquitin-proteasome pathway were detected by immunohistochemistry and Western blot methods.Results 1.The hyperoxia lung injury rat model was successfully duplicated.2.In hyperoxia group,pulmonary edema with increased ratio of moist to dry weight of lungs could be found(P=0).3.Macroscopic observation: bright red and full-stacked lung tissue,foliated or local hemorrhage on the surface,but little pleural effusion was observed in hyperoxia group.There was statistical significance of pathological classification in gross finding between hyperoxia group and air control group(P=0.005).Light microscope observation:swelled alveolar epithelium,widened alveoli wall,capillary engorgement and telangiectasis,obvious edema in interstitial tissue of pulmonary aveolus and alveolar space,increased inflammatory cells were observed in hyperoxia group.The findings of pathological score of lung injury indicated more serious injure than control group(P=0).4.The increased expression of ubiquitin protein in lung tissue was discoved by using immunohistochemistry and Western blot findings after hyperoxia exposure 72 hours.(P=0).5.The acti-vity of proteasomes 20 S in hyperoxia group was higher than that in control group(P=0).Conclusions The mainly pathological changes of lung are generated through hyperoxic exposure for 72 hours,including alveolar epithelial cell and vascular endothelial cell injury diffusely,inflammatory cell infiltration and pulmonary edema.Active the ubiquitin-proteasome pathway is connected with the pathophysiological process of lung injury in the initial stages of hyperoxia-exposure.