Effect of hyperoxia exposure on expression of microRNA-125b and tumor necrosis factor alpha, interleukin-6 in lung tissues of premature newborn rats

Objective To observe the expression of microRNA-125b (miR-125), tumor necrosis factor alpha (TNF-α) and interleukin-6(IL-6) in premature rats exposed to hyperoxia. Methods Eighty 1-day old Sprague Dawley (SD) rats were randomly divided into an air group and a hyperoxia group.The rats in the hyperoxia group were continuously exposed to oxygen chamber for 1-3 L/min, oxygen volume fraction was maintained at (800±50) mL/L, and the rats in air group were placed in the same room with the oxygen volume fraction at 210 mL/L.The feeding conditions were same in 2 groups.Lung tissues of premature rats were extracted at different time (1, 4, 7, 10, 14 days). The pathologic changes in the lung tissues were observed by hematoxylin-eosin (HE) staining.The levels of miR-125b and TNF-α, IL-6 in lung tissues were detected by reverse transcription polymerase chain reaction (qRT-PCT) and enzyme-linked immunosorbent assay (ELISA). Results Compared with the air group, miR-125b in the hyperoxia group increased slowly after day 1, reached the highest in day 10 (2.554±0.323), and the relative expression in day 14 decreased slightly(2.329±0.263), and there were significant differences between 2 groups at di-fferent time (all P 0.05), but there was significant correlation between miR-125b and IL-6 in hyperoxia groups(r=0.439, P<0.05). Conclusions The levels of miR-125b, TNF-α and IL-6 are involved in the pathological process of bronchopulmonary dysplasia induced by hyperoxia, and IL-6 may be the key factor for miR-125b. Key words: Hyperoxia exposure; Rat, premature; Lung injury; MicroRNA-125b; Tumor necrosis factor alpha; Interleukin-6