Brain-derived neurotrophic factor (BDNF) and its associated, specific tropomyosin related kinase B (TrkB) receptor modulates basal myocardial function and low circulating BDNF levels correlate with worsening of symptoms in heart failure (HF) subjects. Deleting BDNF in myocytes leads to prominent LV dilation at baseline, but basal and stress-stimulated left ventricle (LV) function was never tested in cBDNF-/- mice. Our pilot data suggest that left ventricles from human and experimental HF subjects are massively BDNF depleted. Despite this experimental and clinical evidence, cardiac BDNF/TrkB remains largely understudied. The long-term goal is to determine factors accounting for loss in BDNF/TrkB signal in failing hearts, and mechanisms whereby re- introducing BDNF via TrkB stimulation in BDNF-depleted failing hearts affords protection against ischemic and non-ischemic stress. Here we advance the following three novel hypotheses: 1) that myocardial BDNF generation prevents chronic cardiac decompensation in infarcted hearts, and proper ?AR activity is involved in this generation; 2) that direct S1PRs stimulation enhances myocardial BDNF production, preventing LV decompensation in infarcted mice, and that selective ?1AR-blockers rescue ?3AR down-regulation in post-MI hearts, increasing myocardial BDNF levels via ?3-AR/S1PRs signal; 3) that cardiac TrkB stimulation rescues ?-AR sensitivity and improves decompensation in a dog model of non-ischemic cardiomyopathy. The rationale for the proposal is that understanding how loss in BDNF/TrkB signal contributes to myocardial adaptation to ischemic or non-ischemic cardiac stress will advance efforts to therapeutically harness this capacity for clinical relevant conditions associated to loss of cardiomyocytes due to ischemic or non-ischemic cardiac diseases. The central hypotheses will be tested in three integrated Specific Aims.
In Aim 1, we will determine if deleting myocardial BDNF worsens outcome in mice with myocardial infarction, and to test whether TrkB agonists rescues BDNF expression and ?-AR sensitivity in infarcted hearts, the latter by inhibited GRK2, the major kinase liable for cardiac ?-AR desensitization.
In Aim 2, we will test if direct ?3-AR or S1PRs stimulation enhances myocardial BDNF content to protect the myocardium against myocardial infarction;
In Aim 3, we will test whether the chronic infusion of TrkB agonists rescues LV function in dogs with tachypacing-induced HF via improved myocardial efficiency and restored ?-AR sensitivity. The proposed research is significant, because it is expected to foster our understanding of a novel compensatory mechanism, BDNF/TrkB signal that can enable the heart to preserve functional integrity and energetic efficiency in myocardial cells under condition of ischemic or non-ischemic stress, and to determine whether TrkB agonists merit further consideration for clinical testing in HF.

Public Health Relevance

Brain-derived neurotrophic factor (BDNF) and its tropomyosin related kinase B (TrkB) receptor are required for normal cardiac contraction and relaxation. Loss in BDNF/TrkB signal can account for LV decompensation after myocardial infarction (MI). Here we will determine mechanisms accounting for loss in myocardial BDNF in ischemic or non-ischemic cardiomyopathy, focusing on alterations in ?-AR and associate signaling as main factors accounting for such loss. In parallel, we will test if chronic infusion of TrkB agonists can delay HF progression in ischemically or non-ischemically stressed hearts, in part via restored ?-AR signal.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Project (R01)
Project #
1R01HL136918-01A1
Application #
9447993
Study Section
Cardiac Contractility, Hypertrophy, and Failure Study Section (CCHF)
Program Officer
Desvigne-Nickens, Patrice
Project Start
2018-01-11
Project End
2021-12-31
Budget Start
2018-01-11
Budget End
2018-12-31
Support Year
1
Fiscal Year
2018
Total Cost
Indirect Cost
Name
Johns Hopkins University
Department
Internal Medicine/Medicine
Type
Schools of Medicine
DUNS #
001910777
City
Baltimore
State
MD
Country
United States
Zip Code
21205