Preclinical Diastolic Dysfunction in Type 2 Diabetes

Mayo Clinic Rochester, Rochester MN

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Abstract

PROJECT SUMMARY The broad objective of the current application is to advance our understanding of the pathophysiological mechanisms of preclinical left ventricular diastolic dysfunction (PDD) (Stage B heart failure) in humans with type 2 diabetes mellitus (DM) and to develop novel therapeutic strategies to prevent the progression to symptomatic heart failure (Stage C heart failure). Centers for Disease Control and Prevention reported that the number of Americans with DM has grown to 30 million people, or 9.3% of the U.S. population, with 90% to 95% of cases being type 2 DM. This application will focus only on type 2 DM. DM is strongly associated with the development of heart failure (HF) which is a major cause of death. We have previously reported that between 23-54% of DM patients have preclinical diastolic dysfunction (PDD) or Stage B heart failure determined by echo Doppler. More importantly, we determined that diastolic dysfunction was associated with increased risk of the subsequent development of HF after adjustment for age, sex, body mass index, hypertension, coronary disease and echo parameters (HR=1.67, 95% CI=1.27-2.23; p<0.001). The cumulative probability of development of HF for DM patients with PDD was 37% at 5 years compared to 17% at 5 years for DM patients without diastolic dysfunction (P<0.001). Cyclic guanosine 3',5'-monophosphate (cGMP) is the second messenger of the natriuretic peptide system and the nitric oxide system. cGMP plays an important role in the preservation of myocardial, vascular and renal function. Disruption of this signal transduction process may contribute to the development of cardiorenal dysfunction. Preclinical studies and the applicant's preliminary clinical data suggest that there is an impaired cGMP generation in response to the activation of the endogenous natriuretic peptides (NPs) in DM. The mechanism of impaired cGMP generation in DM to endogenous NPs is not well defined and may be due to the lack of biologically active NPs, increased NPs degradation or down regulation of NP receptors. Neprilysin is a zinc-dependent metalloprotease that cleaves peptides at the amino side of hydrophobic residues and inactivates several peptide hormones, including the NPs. Angiotensin receptor neprilysin inhibitor (ARNI) is a new class of therapeutic agents that combines neprilysin and angiotensin receptor inhibitor, potentiates the cGMP system and is approved for the management of Stage C systolic HF. However, the cardiorenal renal action of ARNI in human DM with and without PDD (Stage B HF) has not been well defined. We have previously demonstrated that neprilysin inhibition in experimental HF improves cardio-renal function associated with increasing endogenous NPs. Hence, ARNI may be used as a tool to provide insight into the mechanism of impaired cGMP generation in DM by inhibition of endogenous NPs degradation. Building on our know-how in protein biology, we have succeeded in creating a bivalent chimeric peptide that can activate 2 distinct molecular signaling pathways: CRRL 094 is a unique peptide that combines the biological properties of natriuretic peptide and Insulin, resulting in the activation of cGMP and the secretion of insulin. This novel peptide may be beneficial in DM with PDD to control hyperglycemia and the cardiorenal protective actions of the NPs to prevent the development of stage C HF.Our Specific Aims are as follows: Specific Aim 1: To perform high definition phenotyping of DM with and without PDD, defining the differential cardiorenal response to acute saline volume expansion. Hypothesis: DM with PDD has greater impaired cGMP and cardiorenal response to acute volume expansion Specific Aim 2: To determine the effects of exogenous B-type natriuretic peptide (BNP) or neprilysin inhibition with ARNI (LCZ 696) on the cardiorenal and humoral response to acute saline volume expansion in DM with and without PDD. Hypothesis: DM with PDD has an attenuated response to ARNI but preserved response to exogenous BNP. Specific Aim 3: To define in an experimental model of type 2 Diabetic cardiomyopathy, the biological and potential therapeutic actions of a novel bivalent chimeric insulin secreting natriuretic peptide, CRRL 094 Hypothesis: The bivalent chimeric peptide will control hyperglycemia and have beneficial cardiorenal actions beyond insulin alone or insulin + ARNI. To address these objectives related to PDD with DM, we will pursue translational high definition physiological human and animal studies taking advantage of the extensive clinical facilities, patient populations, the NIH funded Center for Clinical and Translational Science (CCaTS) at the Mayo Clinic and also the cardiorenal research laboratory, which makes our proposed research highly feasible, innovative and of significant clinical importance.