MiR-15b-5p Participate "New BPD" By Modifying VEGF In Hyperoxia-Induced Newborn Rats

Objective:The aim of our study is to probe the role and mechanism of miR-15b-5p regulating VEGF in the development of new Bronchopulmonary Dysplasia(BPD).Methods:1.A total of 48 neonatal rats were equally assigned to BPD group and control group.The rats in BPD group were raised under 60% oxygen concentration to establish BPD model,while control group were raised under room air condition.On postnatal days(PN)7,14 and21,the lung tissues were collected for pathological analysis and detection of miR-15b-5p and VEGF.2.RLE-6TN cells were cultured and transfected by mimic and inhibitor to over-express and down-regulate miR-15b-5p.3.After overexpression of miR-15b-5p in RLE-6TN,cell proliferation was detected by CCK8 assay.4.Quantitative real-time polymerase chain reaction(qRT-PCR)was applied to determine relative expressions of VEGF m RNA and miR-15b-5p.The expression levels of VEGF protein were tested by ELISA and Western blot analysis.Results:1.Lung pathological change of BPD group at PN14 and PN21 demonstrated enlargement of distal air spaces with a simplification of lung structure.Meanwhile,compared to control group,the MAN of BPD gourp decreased,and MAA and MAD increased at day 14 and 21.2.The expression levels of VEGF mRNA and protein at PN7 had no differences between the control group and the BPD group.However,VEGF m RNA and protein level in BPD group incrementally decreased at PN14 and PN21 compared to PN7 and that were significantly lower than control group(P<0.05).3.MiR-15b-5p expression between control group and BPD group had no difference at PN7 and PN14.However,the results showed higher expression of miR-15b-5p in BPD group than control group at PN21(fold change >4.0;P<0.01).4.In vitro result showed that upload the expression of miR-15b-5p decreased the expression level of VEGF m RNA in RLE-6TN cells.In contrast,inhibition of miR-15b-5p led to increased VEGF m RNA level(P<0.05).In addition,RLE-6TN cells proliferation was inhibited when overexpress miR-15b-5p.Conclusion:The results indicated that it was possible that miR-15b-5p was an upstream regulator of VEGF in “new BPD”,which provided a therapeutic option to prevent or ameliorate BPD.