Association of depressed cardiac gp130-mediated antiapoptotic pathways with stimulated cardiomyocyte apoptosis in hypertensive patients with heart failure

Objective To investigate whether the glycoprotein ( gp130)mediated survival pathway, which protects cardiomyocytes from apoptosis, is depressed in left ventricular hypertrophy hypertensive patients with chronic heart failure. Methods Transvenous endomyocardial biopsies were obtained in 52 hypertensive patients with left ventricular hypertrophy: 28 without heart failure and 24 with heart failure. gp130 and gp130- dependent antiapoptotic pathways p42/ 44 mitogen- activated protein kinase ( MAPK) and phosphatidylinositol- 3 kinase ( PI3K)/ protein kinase B ( Akt) as well as gp130 agonist cardiotrophin- 1 were analyzed by reverse transcriptase- polymerase chain reaction and western blot. Apoptosis was assessed by DNA end- labeling ( TUNEL), caspase- 3 immunostaining and caspase substrate poly( ADP- ribose) polymerase cleavage. Results gp130 protein expression ( P< 0.05) and p42/ 44 MAPK and PI3K/ Akt activation ( P< 0.01) were decreased in heart- failure hypertensive patients compared with nonheart- failure hypertensive individuals. No changes in gp130 mRNA expression were found between the two groups. Cardiotrophin- 1 was increased ( P< 0.05) at both the mRNA and protein levels in heart- failure hypertensive individuals compared with nonheart- failure hypertensive individuals. Cardiomyocyte apoptosis was increased ( P< 0.01) in heart- failure hypertensive individuals compared with nonheart- failure hypertensive individuals. Inverse correlations ( P< 0.01) occurred between cardiomyocyte apoptosis and p42/ 44 MAPK and PI3K/ Akt activation in all hypertensive patients. Cardiotrophin- 1 correlated inversely ( r=0.554, P< 0.05) with gp130 in all hypertensive individuals. In cultured HL- 1 cardiomyocytes, cardiotrophin- 1 decreased ( P< 0.05) the gp130: phosphorylated gp130 ( at Ser782) ratio and increased ( P< 0.05) gp130ubiquitination. Conclusions An association exists between depression of the gp130 cytoprotective pathway and stimulation of cardiomyocyte apoptosis in hypertensive patients that develop heart failure. Whether the excess of cardiotrophin- 1 induces ligand- induced receptor down- regulation in these patients requires further study.