Treatment with CBA-NP a Novel Chimeric Natriuretic Peptide Attenuates Cardiorenal Fibrosis and Improves Diastolic Dysfunction in Diabetic Rat Model

Abstract

IntroductionDiabetes is a major risk factor for left ventricular dysfunction with cardiac and renal fibrosis. C-type natriuretic peptide (CNP) is a 22 amino-acid peptide produced mainly in the cardiac endothelium with potent cardiac unloading, anti-fibrotic and antihypertensive effects, but minimal renal actions. Using this knowledge we designed a natriuretic peptide CBA-NP by fusing a 6 AA sequence (KVLRRH) from BNP to the C-terminus and a 5 AA sequence (RMDRI) from ANP to the N-terminus of CNP to enhance beneficial renal effects while maintaining CNP's inherent cardioprotective properties.HypothesisChronic treatment with CBA-NP will have direct anti-fibrotic and humoral effects in a rat model of diabetic cardiomyopathy.MethodsUsing three groups of six male Wistar rats, (normal control, diabetic control, and diabetic treated with CBA-NP) one dose of streptozotocin was administered to induce diabetes. One month after induction of diabetes ALZET pumps with 0.1μg/kg/min of CBA-NP or saline were serially implanted subcutaneously every 14 days over the course of 2 months. Cardiac function was assessed by echocardiography. Neurohormones by RIA. Fibrosis by picrosirius red staining. Ultrastructural features by electron microscopy.ResultsCBA-NP treatment attenuated LV hypertrophy (0.24±.01 mg/g body weight) compared to diabetic control (0.26±.01) and was comparable to the normal control (0.24±.01). LV interstitial and perivascular fibrosis percentage was significantly reduced in the CBA-NP treated group (3.27 to 1.80 and 3.87 to 1.77) as compared to the diabetic control. Ejection fraction (84.0± 1.2% vs. 78.0±1.7%) and fractional shortening (48±1.2% vs. 41±1%) were significantly improved after CBA-NP treatment compared to diabetic control. Kidney cortical and medullary percent fibrosis was significantly reduced (4.58±0.80 to 2.16±0.14 and 4.43±0.6 to 1.23±0.3) after CBA-NP treatment as compared to the untreated group. GFR significantly improved (1.74±0.18 to 2.42±0.18) with reduction in glomerular basement membrane thickness. There was a significant decrease in plasma renin, aldosterone and BNP, while plasma cGMP increased in the treated group compared to the untreated group.ConclusionsCBA-NP treatment attenuated LV hypertrophy, reduced cardiac and renal fibrosis, and improved cardiac and renal function with suppression of renin and aldosterone, suggesting a potential therapeutic benefit in diabetic cardiomyopathy. IntroductionDiabetes is a major risk factor for left ventricular dysfunction with cardiac and renal fibrosis. C-type natriuretic peptide (CNP) is a 22 amino-acid peptide produced mainly in the cardiac endothelium with potent cardiac unloading, anti-fibrotic and antihypertensive effects, but minimal renal actions. Using this knowledge we designed a natriuretic peptide CBA-NP by fusing a 6 AA sequence (KVLRRH) from BNP to the C-terminus and a 5 AA sequence (RMDRI) from ANP to the N-terminus of CNP to enhance beneficial renal effects while maintaining CNP's inherent cardioprotective properties. Diabetes is a major risk factor for left ventricular dysfunction with cardiac and renal fibrosis. C-type natriuretic peptide (CNP) is a 22 amino-acid peptide produced mainly in the cardiac endothelium with potent cardiac unloading, anti-fibrotic and antihypertensive effects, but minimal renal actions. Using this knowledge we designed a natriuretic peptide CBA-NP by fusing a 6 AA sequence (KVLRRH) from BNP to the C-terminus and a 5 AA sequence (RMDRI) from ANP to the N-terminus of CNP to enhance beneficial renal effects while maintaining CNP's inherent cardioprotective properties. HypothesisChronic treatment with CBA-NP will have direct anti-fibrotic and humoral effects in a rat model of diabetic cardiomyopathy. Chronic treatment with CBA-NP will have direct anti-fibrotic and humoral effects in a rat model of diabetic cardiomyopathy. MethodsUsing three groups of six male Wistar rats, (normal control, diabetic control, and diabetic treated with CBA-NP) one dose of streptozotocin was administered to induce diabetes. One month after induction of diabetes ALZET pumps with 0.1μg/kg/min of CBA-NP or saline were serially implanted subcutaneously every 14 days over the course of 2 months. Cardiac function was assessed by echocardiography. Neurohormones by RIA. Fibrosis by picrosirius red staining. Ultrastructural features by electron microscopy. Using three groups of six male Wistar rats, (normal control, diabetic control, and diabetic treated with CBA-NP) one dose of streptozotocin was administered to induce diabetes. One month after induction of diabetes ALZET pumps with 0.1μg/kg/min of CBA-NP or saline were serially implanted subcutaneously every 14 days over the course of 2 months. Cardiac function was assessed by echocardiography. Neurohormones by RIA. Fibrosis by picrosirius red staining. Ultrastructural features by electron microscopy. ResultsCBA-NP treatment attenuated LV hypertrophy (0.24±.01 mg/g body weight) compared to diabetic control (0.26±.01) and was comparable to the normal control (0.24±.01). LV interstitial and perivascular fibrosis percentage was significantly reduced in the CBA-NP treated group (3.27 to 1.80 and 3.87 to 1.77) as compared to the diabetic control. Ejection fraction (84.0± 1.2% vs. 78.0±1.7%) and fractional shortening (48±1.2% vs. 41±1%) were significantly improved after CBA-NP treatment compared to diabetic control. Kidney cortical and medullary percent fibrosis was significantly reduced (4.58±0.80 to 2.16±0.14 and 4.43±0.6 to 1.23±0.3) after CBA-NP treatment as compared to the untreated group. GFR significantly improved (1.74±0.18 to 2.42±0.18) with reduction in glomerular basement membrane thickness. There was a significant decrease in plasma renin, aldosterone and BNP, while plasma cGMP increased in the treated group compared to the untreated group. CBA-NP treatment attenuated LV hypertrophy (0.24±.01 mg/g body weight) compared to diabetic control (0.26±.01) and was comparable to the normal control (0.24±.01). LV interstitial and perivascular fibrosis percentage was significantly reduced in the CBA-NP treated group (3.27 to 1.80 and 3.87 to 1.77) as compared to the diabetic control. Ejection fraction (84.0± 1.2% vs. 78.0±1.7%) and fractional shortening (48±1.2% vs. 41±1%) were significantly improved after CBA-NP treatment compared to diabetic control. Kidney cortical and medullary percent fibrosis was significantly reduced (4.58±0.80 to 2.16±0.14 and 4.43±0.6 to 1.23±0.3) after CBA-NP treatment as compared to the untreated group. GFR significantly improved (1.74±0.18 to 2.42±0.18) with reduction in glomerular basement membrane thickness. There was a significant decrease in plasma renin, aldosterone and BNP, while plasma cGMP increased in the treated group compared to the untreated group. ConclusionsCBA-NP treatment attenuated LV hypertrophy, reduced cardiac and renal fibrosis, and improved cardiac and renal function with suppression of renin and aldosterone, suggesting a potential therapeutic benefit in diabetic cardiomyopathy. CBA-NP treatment attenuated LV hypertrophy, reduced cardiac and renal fibrosis, and improved cardiac and renal function with suppression of renin and aldosterone, suggesting a potential therapeutic benefit in diabetic cardiomyopathy.