Cathelicidin-related Antimicrobial Peptide Suppresses Pathological Cardiac Hypertrophy And Its Underlying Mechanism

Objective:Heart failure is one of the leading causes of morbidity and mortality in the worldwide.Pathological cardiac hypertrophy is an important pathologic process in heart failure.The delay or reverse of pathological cardiac hypertrophy is the key to prevent or treat heart failure.Cathelicidin related antimicrobial petide(also known as CRAMP in mice/rat,LL-37 in human)is an endogenous antimicrobial peptide,which contributed to myocardial cell apoptosis and protected against myocardial dysfunction during myocardial ischemia reperfusion injury.However,the role and mechanism of CRAMP in pathological cardiac hypertrophy and heart failure remain unclear.Methods:The CRAMP expression was examined in angiotensin?(ANG ?)and phenylephrine(PE)treated cardiomyocytes hypertrophy model,and in the myocardium of thoracic aortic constriction(TAC)or isoproterenol(ISO)induced cardiac hypertrophy murine model by ELISA.In vitro,we performed functional experiemnts by CRAMP treatment in ANG ? and PE treated primary neonatal rat cardiomyocytes(NRCM).In addition,cell area and hypertrophic genes(ANP,BNP)were determined by ?-actinin immunolabeling and q RT-PCR.In vivo,CRAMP intraperitoneal injection and knockout mouse were generated and subjected to TAC,ISO or ANG ? to investigate the effect of CRAMP in pathological cardiac hypertrophy.In addition,cardiac function,hypertrophy,fibrosis,apoptosis and hypertrophic genes were determined by echocardiography,wheat germ agglutinin(WGA)staining,hematoxylin-eosin(HE)staining,masson staining,sirius red staining,immunoblotting and q RT-PCR.Furthermore,immunoblotting and functional rescue assays with NF-?B agonist(Betulinic acid)were performed to confirm NF-?B as a downstream mediator of CRAMP in pathological cardiac hypertrophy.Finally,human serum LL-37 were measured by ELISA in acute heart failure(AHF)patients and hearlthy controls,and correlation and ROC curve were analyzed.Results:The expression of CRAMP was significantly decreased in cardiomyocytes and cellular supernatant from ANG ? and PE-induced cardiomyocyte hypertrophy model,and in the heart and serum from TAC or ISO mouse model.CRAMP treatment significantly attenuated ANG ? and PE-induced cardiomyocyte hypertrophy in vitro.CRAMP intraperitoneal injection displayed improved cardiac function and reduced cardiac hypertrophy,fibrosis,apoptosis and the expression of hypertrophic genes after TAC,ISO or ANG ? treatment in vivo.However,CRAMP knockout mouse reduced cardiac function and aggravated cardiac hypertrophy,fibrosis,apoptosis and the expression of hypertrophic genes after ANG ? treatment.Moreover,CRAMP suppressed phosphorylation of NF-?B.And the NF-?B agonist reversed the inhibition of CRAMP in ANG ? and PE-induced cardiomyocyte hypertrophy.Finally,the expression of human serum LL-37 was decreased from acute heart failure(AHF)patients as compared to healthy controls,and ROC curve analysis for the diagnosis of AHF by using serum LL-37 showed an area under curve of 0.616.Conclusion:CRAMP can prevent pathological cardiac hypertrophy and heart failure.LL-37 could be a diagnostic biomarker for human AHF.CRAMP attenuates cardiac hypertrophy by inhibition of NF-?B.Targeting CRAMP represents a novel therapeutic strategy for pathological cardiac hypertrophy and heart failure.