Diastolic heart failure (HF), also known as "heart failure-preserved-ejection fraction", accounts for up to 50% of all HF presentations, but unlike systolic HF, therapies remain ineffective despite increasing morbidity and mortality. This stems, in part, from a lack of mechanistic understanding about diastolic HF. Hypertension is the major cause of diastolic HF and the prevalence of diastolic HF is projected to increase as the incidence of hypertension rises. Obese individuals also have a high incidence of poorly controlled blood pressure and diastolic HF. This raises the possibility that factors secreted by fa may play a role in hypertension-related diastolic HF. Although a causal link exists between aldosterone and arterial hypertension, increasing evidence demonstrates a link between aldosterone and obesity with evidence that adipocytes, in addition to secreting adiponectin (APN), may release secreted factors that stimulate aldosterone release independent of angiotensin-II. APN, an adipose-derived plasma protein, exerts anti-inflammatory and anti-hypertrophic effects by modulating phosphorylation signals in cardiovascular cells and is implicated in the development of hypertension and systolic HF. APN levels are decreased in obesity and hypertension, but elevated in systolic HF, also known as "heart failure-reduced-ejection fraction". Conversely aldosterone is increased in obesity, hypertension and in HF. Recently our lab showed that hypoadiponectinemia in hypertension-induced diastolic HF exacerbates left ventricular hypertrophy, diastolic dysfunction and diastolic HF. We seek to examine the contribution of APN to the relative increase in aldosterone in diastolic HF. The broad objective of this proposal is that dysregulation between aldosterone and APN contributes to the pathogenesis of diastolic HF and adverse cardiac remodeling. To our knowledge this conceptual model has not been tested nor hypothesized. We will test the hypothesis that an alteration in APN levels facilitates an increase in aldosterone increasing the propensity to diastolic HF and diastolic dysfunction. To address this hypothesis we will test the following aims:
Aim 1) to investigate if dysregulation of APN levels are associated with alterations in aldosterone levels in human diastolic HF. Hypothesis 1. Aldosterone and APN levels are elevated in stable diastolic HF patients and are associated with left ventricular (LV) diastolic dysfunction measurements. Hypothesis 2. Changes in aldosterone and APN levels (between acutely, decompensated and stable, ambulatory diastolic HF) are associated with disease progression (as determined by echocardiographic derived measures of LV diastolic dysfunction) in diastolic HF.
Aim 2) To determine if APN ameliorates the transition from hypertension to diastolic dysfunction and diastolic HF in a mouse model of diastolic HF and dysfunction.
Aim 3) To investigate the role of autophagy in diastolic dysfunction in cardiac myocytes and the signaling mechanisms involved in cell-to-cell communication between cardiac myocytes and adipocytes in diastolic HF.
Hypertension is the most significant risk factor for the development of diastolic heart failure. Diastolic heart failure accounts for up to 50% of all heart failure presentations;but despite increasing mortality and morbidity a paucity of therapies is evident, which may be partly due to a lack of understanding of the mechanisms underlying diastolic heart failure. Our proposed studies will examine the role of inter-tissue communication, in humans and animal models, and how this contributes to diastolic heart failure.
|Tanaka, Komei; Wilson, Richard M; Essick, Eric E et al. (2014) Effects of adiponectin on calcium-handling proteins in heart failure with preserved ejection fraction. Circ Heart Fail 7:976-85|