| Aims:In patients with heart failure(HF),plasma B-type natriuretic peptide(BNP)levels are increased,but their anti-HF effects are weakened.Being called as BNP paradox,this phenomenon has unclear mechanisms.The possible explanation is that with full-length form of BNP decreasing,its truncated forms are increased in patients with HF,which have weaker activation of NP receptor-A(NPR-A)and biological functions.From the perspective of receptor interaction,this study was to explore the interaction of different BNP forms with NPR-A and their biological roles.From the perspective of gene regulation,the mechanisms affecting the transcription of NPPB gene and the development of HF and AF were explored through analyzing gene mutation[single nucleotide polymorphism(SNP)]and epigenetics[deoxyribonucleic acid(DNA)methylation and micro ribonucleic acids(miRNAs)in exosomes].From the perspective of clinical application,prognostic abilities of N-terminal pro-B-type natriuretic peptide(NT-proBNP)were analyzed in older patients with HF and AF.These will help us clarify the mechanisms of BNP paradox,understand the process of HF and AF,and explore innovative therapeutic targets.Methods:Enzyme-linked immunosorbent and surface plasma resonance techniques were applied to analyze the interaction between different BNP forms and NPR-A.Cell migration,proliferation and apoptosis were analyzed with CCK-8,Transwell and flow cytometry.SNP and DNA methylation of NPPB gene were analyzed with sequencing and MassArray technology.MiRNAs in exosomes of AF were analyzed with high-throughput sequencing.Prognostic abilities of NT-proBNP were analyzed with COX regression and ROC curve in older patients with HF(306 cases)and AF(219 cases).Results:1.The interaction of NPR-A protein and HEK293T cells highly expressing NPR-A with C-terminal truncated and substituted peptides(BNP 1-29 and so on)of BNP was significantly weaker than full-length(BNP 1-32)and N-terminal truncated(BNP3-32 and so on)peptides of BNP(P<0.05 for all).Biological roles,such as promoting the proliferation and migration of HEK293T cells highly expressing NPR-A and inhibiting the apoptosis of HEK293T cells,of C-terminal truncated and substituted peptides(BNP 1-29 and so on)of BNP were significantly weaker than full-length(BNP 1-32)and N-terminal truncated(BNP3-32 and so on)peptides of BNP(P<0.05 for all);2.No SNP site was found in 3 exons and 2 introns of NPPB gene,suggesting that BNP truncated peptides are not generated by gene mutation.Three SNP sites were found in non-coding region:rs198389 in promoter region,rs3753581 in 5' non-coding region,and rs198388 in 3' non-coding region.Rs 198389 mutation in promoter region was significantly negatively correlated with ejection fraction,and luciferase activity was significantly reduced in mutant group(P<0.05 for all);3.Methylated site of NPPB gene had different degrees between HF group and non-HF group(P<0.05);4.Plasma NT-proBNP levels were significantly and independently associated with all-cause mortality of older patients with HF and AF(P<0.05 for all).Plasma NT-proBNP levels and the model based on them had similar C-statistics compared with Seattle heart failure score(P>0.05 for all).Plasma NT-proBNP levels and the model based on them had higher C-statistics compared with CHADS2 ? CHA2DS2VASc(P<0.05 for all);5.Numbers of known miRNAs and corresponding target genes in patients with persistent AF were significantly more than those in non-AF patients(P<0.05 for all);Conclusions:Lacking C-terminus of BNP significantly weakened the binding of BNP to NPR-A and its biological functions.Rs198389 mutation may induce the deterioration of cardiac function by reducing the synthesis of BNP.Methylation of NPPB gene may be related to the development of HF.NT-proBNP was a biomarker independently associated with poor prognosis of older patients with HF and AF. |
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