| Cardiac hypertrophy is the secondary reaction of myocardial cells to pathological stimulation such as hypertension,hypoxia,pulmonary hypertension.Heart failure resulting from cardiac hypertrophy is an important cause of death in these patients.Currently,antihypertensive drugs are the main drugs used in the clinical treatment of cardiac hypertrophy,which are mostly used to reduce pressure load and relieve symptoms,but there are no specific drugs to improve cardiac hypertrophy.Therefore,it is significant to develop specific drugs for prevention and treatment of cardiac hypertrophy.G protein is an important signal converter and plays a crucial role in the signal transduction pathway that mediates cardiac hypertrophy.The polypeptide GCIP-27developed by our department for Gq has been proved to improve myocardial hypertrophy in NE-induced mice and spontaneously hypertensive rats in previous studies,and has a good effect on right ventricular hypertrophy caused by monocrotaline（MCT）.But its effect on hypoxic-induced right ventricular hypertrophy remains to be studied.As with other peptides,water solubility of GCIP-27 is poor.Therefore,a new polypeptide ACTY116 with better water solubility was obtained by further structural optimization.In this study,our aims were to explore the ameliorative effect of ACTY116 on pulmonary hypertension,right ventricular hypertrophy,and its mechanism in hypoxic-induced mice and in MCT-induced rats,as well as in Ang II-induced cardiomyocytes.Phillyrin（PHI）,a natural product extracted from a traditional Chinese medicine Forsythia suspensa（Thunb.）Vahl,has anti-inflammatory and antioxidant effects.It has been reported by other scholars that PHI reduce myocardial fibrosis in mice with myocardial infarction.In our previous study,PHI could inhibit liver inflammation and fibrosis.In this study,our aims were to further explore effects of PHI on cardiac hypertrophy and inflammation in NE-induced mice and in NE-induced or Ang II-induced cardiomyocytes.Methods1.Improving effect of ACTY116 on pulmonary hypertension and right ventricular hypertrophy.SD rats were intraperitoneally injected with MCT（60 mg/kg）to establish right ventricular hypertrophy models.The treatment group received intraperitoneal injection of30,100,300μg/kg or subcutaneous injection of 300μg/kg ACTY116 for 28 days.C57BL/6mice were injected subcutaneously with SU5416（20 mg/kg）once a week,and then kept in10%hypoxia environment to establish pulmonary hypertension and right ventricular hypertrophy models.The treatment group received intraperitoneal injection of 100,300μg/kg or subcutaneous injection of 300μg/kg ACTY116 for 35 consecutive days.Valsartan（Val）was used as a positive control.Small animal ultrasonography,ELISA detection,morphology analysis and transmission electron microscopy were used in animal experiment.Also,1μM AngⅡ-induced cardiomyocyte hypertrophy model was designed to study the effect of ACTY116 on cardiomyocyte hypertrophy in vitro.2.Study on the mechanism of ACTY116 improving cardiac hypertrophy.SU5416/hypoxia-induced mice and AngⅡ-induced cardiomyocytes were used.ELISA,calcium ion detection,RT-q PCR and protein western blotting were also used to study the mechanism of ACTY116 in improving cardiac hypertrophy.3.Inhibitory effect of PHI on cardiomyocyte hypertrophy and its mechanism in vitro.The inhibitory effect of PHI on 1μM AngⅡ-treated or 4μM NE-treated cardiomyocytes in vitro was studied by cell morphology analysis and RT-q PCR.4.Effect and mechanism of PHI on cardiac hypertrophy induced by NE in mice.Mice were injected subcutaneously with 3 mg/kg NE every day for 15 days to establish the model,and the treatment group was subcutaneously injected with 30 or 100mg/kg PHI every day.The effect of PHI on cardiac hypertrophy induced by NE and its mechanism were studied using immunohistochemistry and RT-q PCR.Results1.ACTY116 significantly improved the survival rate of MCT-induced rats,reduced the thickness of pulmonary artery wall,inhibited the right ventricular tissue fibrosis,and improved the right ventricular hypertrophy and tissue ultrastructural damage.And ACTY116 significantly improved the general condition of hypoxic-induced mice,reduced pulmonary hypertension,improved right ventricular hypertrophy.ACTY116 also inhibited AngⅡ-induced cardiomyocyte hypertrophy in vitro.2.ACTY116 significantly reduced the expression of hypertrophy gene,AngⅡand AT1receptor gene in hypoxic-induced mice,and inhibited the phosphorylation of PLCβ,p38and ERK1/2 and dephosphorylation of NFAT2 in right ventricular tissue.And ACTY116reduced the concentration of calcium ion in cardiomyocytes induced by AngⅡ,inhibited the phosphorylation of PLCβ,p38 and ERK1/2 and dephosphorylation of NFAT2 in cardiomyocytes in vitro.3.PHI showed no obvious improvement on AngⅡ-stimulated cardiomyocyte hypertrophy in vitro,but showed obvious inhibition on NE-stimulated cardiomyocyte hypertrophy,and inhibited the expression of inflammatory factor genes.4.In NE-induced mice,PHI significantly inhibited the infiltration of macrophages in cardiac tissue,inhibited inflammatory response and improved cardiac hypertrophy in mice.ConclusionThe polypeptide ACTY116 significantly improved the survival rate of MCT-induced rats,the living condition of hypoxic-induced mice,and improved pulmonary hypertension and right ventricular hypertrophy through the inhibition of PLCβ/Ca2+/NFAT2 and p38/ERK1/2 pathways.PHI effectively improved cardiac hypertrophy,and its mechanism may be related to inhibiting the expression of cardiac inflammatory factors and inflammatory cell infiltration. |
