Relationship between gene expression of basic fibroblast growth factor and transforming growth factor-beta 1 and atrial fibrosis in human atria during atrial fibrillation

Objective To investigate the significance and alteration of gene expression of type I collagen(Col Ⅰ),basic fibroblast growth factor(bFGF) and transforming growth factor-beta 1(TGF-β1) related to atrial fibrosis in patients with atrial fibrillation(AF).Methods The right atrial tissue samples were taken from 75 patients with rheumatic heart disease who underwent heart valve replacement surgery.34 patients were in sinus rhythm,11 patients had paroxysmal AF and 30 patients had persistent AF.The mRNA and protein level of Col Ⅰ,bFGF and TGF-β1 were measured by semi-quantitative reverse transcription polymerase chain reaction(RT-PCR) and immunohistochemical technique. Results Atrial fibrosis tissue content significantly increased in both the paroxysmal AF and persistent AF groups than that in the sinus rhythm group,the significant difference was also observed between the persistent AF and paroxysmal AF groups(all P0.05).Collagen volume fraction significantly correlated with AF duration and left atria(LA) dimension.Compared to sinus rhythm group,the mRNA and protein level of Col Ⅰ,bFGF and TGF-β1 increased significantly in both paroxysmal AF and persistent AF group.And all gene expression at mRNA and protein level increased more significantly in the persistent AF group than the paroxysmal AF group(all P0.05).The mRNA and protein level of Col I was positively correlated with AF duration and left atrial dimension.The mRNA and protein level of bFGF was positively correlated with AF duration and left atrial dimension.Conclusion The increased level of bFGF and TGF-β1 gene expression in atrium may contribute to atrial fibrosis during AF through influencing fibroblast proliferation.