Fibroblast Growth Factor 9 Inhibits Phenotypic Transformation On Pulmonary Artery Smooth Muscle Cells

Objective: Pulmonary arterial hypertension(PAH)is a relatively rare pulmonary vascular disease,which is mainly manifested by increased pulmonary artery pressure,and its pathological characteristics are mainly vascular remodeling.The transformation of pulmonary artery smooth muscle cells from contractile phenotype to synthetic phenotype is one of the important factors for pulmonary vascular remodeling.Fibroblast growth factor 9 is an autocrine or paracrine cytokine involved in pathophysiological processes such as tumor growth,embryonic development,inflammation and angiogenesis.This study mainly explored whether FGF9 played a role in the pathological process of pulmonary hypertension by regulating the phenotypic transformation of pulmonary artery smooth muscle cells(PASMCs).Methods: Animal models of pulmonary arterial hypertension induced by monocrotaline(MCT),and the expression of FGF9 in the PAH model was detected by Western blot.Rat primary PASMCs were cultured in vitro,platelet-derived growth factor BB(PDGF-BB)and hypoxia induced phenotypic transformation of pulmonary artery smooth muscle cells,the expression of FGF9 and shrinkage phenotype marker α-smooth muscle actin(α-SMA)were detected by Western blot.Exogenous recombinant human FGF9(rhFGF9)interfered with cells under pathological stimulation,the expression of shrinkage phenotype marker α-SMA,Synthetic phenotypic marker osteopontin(OPN),and platelet-derived growth factor receptor β(PDGFR-β)were detected by Western blot,and the effect of rhFGF9 on cell migration was detected by the scratch assay.Specifically knock down FGF9,the expression of FGF9 and α-SMA and OPN were detected by Western blot.Results:(1)Compared with the Control group,Western blot results showed that the expression of FGF9 protein in MCT decreased(p<0.05).(2)In PASMCs study,the expression of FGF9 protein in the PDGF-BB group and hypoxia group were significantly reduced compared with the Control group(p<0.05).(3)After treated with rhFGF9 in PASMCs,in the cell scratch assay,rhFGF9 significantly inhibited the migration of PASMCs induced by PDGF-BB.Western blot results showed that compared with the Control group,cells transform from contractile phenotype to synthetic phenotype in the PDGF-BB group and hypoxia group,the expression ofα-SMA decreased(p<0.05),accompanied by up-regulation of synthetic phenotypic marker OPN(p<0.05),and the expression of PDGFR-βdecreased(p<0.05);compared with PDGF-BB group and hypoxia group,in the rhFGF9+ PDGF-BB group and rhFGF9+hypoxia group,the expression of α-SMA was significantly increased(p<0.05)and the expression of OPN was decreased(p<0.05),and the expression of PDGFR-β in rhFGF9+PDGF-BB group did not change significantly,the difference was not statistically significant,this suggesting that rhFGF9 inhibited PDGF-BB and hypoxia-induced cell phenotypic transformation.(4)After knocking down FGF9,the expression of α-SMA protein was significantly reduced(p<0.05),while the expression of OPN did not change significantly,the difference was not statistically significantConclusions: FGF9 inhibits phenotypic transformation and migration induced by PDGF-BB and hypoxia of pulmonary artery smooth muscle cells,without affecting PDGF-BB activated receptor PDGFR-β,at the same time,the down-regulation of FGF9 affected the contractile phenotype of cells.FGF9 is involved in the phenotypic transformation of PASMCs,FGF9 is closely related to the occurrence of pulmonary hypertension.