TIMP3 interplays with apelin to regulate cardiovascular metabolism in hypercholesterolemic mice.
OBJECTIVE
Tissue inhibitor of metalloproteinase 3 (TIMP3) is an extracellular matrix (ECM) bound protein, which has been shown to be downregulated in human subjects and experimental models with cardiometabolic disorders, including type 2 diabetes mellitus, hypertension and atherosclerosis. The aim of this study was to investigate the effects of TIMP3 on cardiac energy homeostasis during increased metabolic stress conditions.


METHODS
ApoE(-/-)TIMP3(-/-) and ApoE(-/-) mice on a C57BL/6 background were subjected to telemetric ECG analysis and experimental myocardial infarction as models of cardiac stress induction. We used Western blot, qRT-PCR, histology, metabolomics, RNA-sequencing and in vivo phenotypical analysis to investigate the molecular mechanisms of altered cardiac energy metabolism.


RESULTS
ApoE(-/-)TIMP3(-/-) revealed decreased lifespan. Telemetric ECG analysis showed increased arrhythmic episodes, and experimental myocardial infarction by left anterior descending artery (LAD) ligation resulted in increased peri-operative mortality together with increased scar formation, ventricular dilatation and a reduction of cardiac function after 4 weeks in the few survivors. Hearts of ApoE(-/-)TIMP3(-/-) exhibited accumulation of neutral lipids when fed a chow diet, which was exacerbated by a high fat, high cholesterol diet. Metabolomics analysis revealed an increase in circulating markers of oxidative stress with a reduction in long chain fatty acids. Using whole heart mRNA sequencing, we identified apelin as a putative modulator of these metabolic defects. Apelin is a regulator of fatty acid oxidation, and we found a reduction in the levels of enzymes involved in fatty acid oxidation in the left ventricle of ApoE(-/-)TIMP3(-/-) mice. Injection of apelin restored the hitherto identified metabolic defects of lipid oxidation.


CONCLUSIONS
TIMP3 regulates lipid metabolism as well as oxidative stress response via apelin. These findings therefore suggest that TIMP3 maintains metabolic flexibility in the heart, particularly during episodes of increased cardiac stress.
Department of Systems Medicine, University of Rome Tor Vergata, 00133 Rome, Italy ; Department of Internal Medicine I, University Hospital Aachen, Pauwelsstraße 30, 52074 Aachen, Germany.
Robert
R
Stöhr
Department of Systems Medicine, University of Rome Tor Vergata, 00133 Rome, Italy ; Department of Internal Medicine I, University Hospital Aachen, Pauwelsstraße 30, 52074 Aachen, Germany.
Ben Arpad
BA
Kappel
Department of Angiocardioneurology and Translational Medicine, IRCCS Neuromed, 86077 Pozzilli, IS, Italy ; Department of Molecular Medicine, Sapienza University of Rome, 00161 Rome, Italy.
Daniela
D
Carnevale
Department of Systems Medicine, University of Rome Tor Vergata, 00133 Rome, Italy.
Michele
M
Cavalera
Department of Systems Medicine, University of Rome Tor Vergata, 00133 Rome, Italy.
Maria
M
Mavilio
Genomics Facility, European Brain Research Institute, Rome, Italy.
Ivan
I
Arisi
Department of Angiocardioneurology and Translational Medicine, IRCCS Neuromed, 86077 Pozzilli, IS, Italy.
Valentina
V
Fardella
Department of Angiocardioneurology and Translational Medicine, IRCCS Neuromed, 86077 Pozzilli, IS, Italy.
Giuseppe
G
Cifelli
Department of Systems Medicine, University of Rome Tor Vergata, 00133 Rome, Italy.
Viviana
V
Casagrande
Department of Systems Medicine, University of Rome Tor Vergata, 00133 Rome, Italy.
Stefano
S
Rizza
European Brain Research Institute, Rome, Italy ; Scuola Normale Superiore, Pisa, Italy.
Antonino
A
Cattaneo
Department of Biomedicine and Prevention, University of Rome Tor Vergata, 00133 Rome, Italy.
Alessandro
A
Mauriello
Department of Systems Medicine, University of Rome Tor Vergata, 00133 Rome, Italy.
Rossella
R
Menghini
Department of Angiocardioneurology and Translational Medicine, IRCCS Neuromed, 86077 Pozzilli, IS, Italy.
Giuseppe
G
Lembo
Department of Systems Medicine, University of Rome Tor Vergata, 00133 Rome, Italy ; Center for Atherosclerosis, Department of Medicine, Policlinico Tor Vergata, 00133 Rome, Italy.
Massimo
M
Federici
Apelin; Arrhythmia; Heart; Lipid metabolism; Oxidative stress; TIMP3