Ben Arpad Kappel

ITCH modulates SIRT6 and SREBP2 to influence lipid metabolism and atherosclerosis in ApoE null mice.

Atherosclerosis is a chronic inflammatory disease characterized by the infiltration of pro-inflammatory macrophages into a lipid-laden plaque. ITCH is an E3 ubiquitin ligase that has been shown to polarize macrophages to an anti-inflammatory phenotype. We therefore investigated the effect of ITCH deficiency on the development of atherosclerosis. ApoE−/−ITCH−/− mice fed a western diet for 12 weeks showed increased circulating M2 macrophages together with a reduction in plaque formation. Bone marrow transplantation recreated the haemopoietic phenotype of increased circulating M2 macrophages but failed to affect plaque development. Intriguingly, the loss of ITCH lead to a reduction in circulating cholesterol levels through interference with nuclear SREBP2 clearance. This resulted in increased LDL reuptake through upregulation of LDL receptor expression. Furthermore, ApoE−/−ITCH−/− mice exhibit reduced hepatic steatosis, increased mitochondrial oxidative capacity and an increased reliance on fatty acids as energy source. We found that ITCH ubiquitinates SIRT6, leading to its breakdown, and thus promoting hepatic lipid infiltration through reduced fatty acid oxidation. The E3 Ubiquitin Ligase ITCH modulates lipid metabolism impacting on atherosclerosis progression independently from effects on myeloid cells polarization through control of SIRT6 and SREBP2 ubiquitination. Thus, modulation of ITCH may provide a target for the treatment of hypercholesterolemia and hyperlipidemia.

Effect of Empagliflozin on the Metabolic Signature of Patients With Type 2 Diabetes Mellitus and Cardiovascular Disease

In the recent EMPA-REG OUTCOME trial (Empagliflozin Cardiovascular Outcome Event Trial in Type 2 Diabetes Mellitus Patients), treatment with empagliflozin, a member of the group of antidiabetic sodium-glucose cotransporter 2 inhibitors, reduced cardiovascular mortality and hospitalization for heart failure in patients with type 2 diabetes mellitus and cardiovascular disease.1 In heart failure and type 2 diabetes mellitus, cardiac metabolic flexibility is impaired, and alteration in glucose or fatty acid (FA) metabolism and changes in the use of ketone bodies and branched chain amino acids (BCAAs) occur.2 Because sodium-glucose cotransporter 2 inhibitors lead to a mild increase in ketones, it has been hypothesized that empagliflozin may exhibit some of its beneficial effects through a shift in myocardial metabolism toward an energy-efficient use of ketone bodies, which may improve myocardial work efficiency and function.3,4 Still, these hypotheses are not proven yet, and data are lacking on the metabolic signature of sodium-glucose cotransporter 2 inhibitor-treated patients. Therefore, we performed an untargeted metabolomics approach in a group of empagliflozin-treated patients with type 2 diabetes mellitus and cardiovascular disease. In a prospective study (http://www.clinicaltrials.org; unique identifier: NCT03131232; ethics committee approved, and all patients gave informed consent), we enrolled 25 patients with type 2 diabetes mellitus and cardiovascular disease with a clinical indication for intensification of their glucose-lowering therapy and treated them with empagliflozin 10 mg/day. Serum was taken at baseline and after 1 month. Untargeted …

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. Conclusion 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.

A Role for Timp3 in Microbiota-Driven Hepatic Steatosis and Metabolic Dysfunction

The effect of gut microbiota on obesity and insulin resistance is now recognized, but the underlying host-dependent mechanisms remain poorly undefined. We find that tissue inhibitor of metalloproteinase 3 knockout (Timp3(-/-)) mice fed a high-fat diet exhibit gut microbiota dysbiosis, an increase in branched chain and aromatic (BCAA) metabolites, liver steatosis, and an increase in circulating soluble IL-6 receptors (sIL6Rs). sIL6Rs can then activate inflammatory cells, such as CD11c(+) cells, which drive metabolic inflammation. Depleting the microbiota through antibiotic treatment significantly improves glucose tolerance, hepatic steatosis, and systemic inflammation, and neutralizing sIL6R signaling reduces inflammation, but only mildly impacts glucose tolerance. Collectively, our results suggest that gut microbiota is the primary driver of the observed metabolic dysfunction, which is mediated, in part, through IL-6 signaling. Our findings also identify an important role for Timp3 in mediating the effect of the microbiota in metabolic diseases.

Oral hypoglycemic agents and the heart failure conundrum: Lessons from and for outcome trials

AIM Type 2 diabetes is not only an independent risk factor for cardiovascular (CV) disease but is also associated with a greater incidence of heart failure (HF). The aim of this review is to examine the effects of oral antidiabetic drugs on CV disease and HF. DATA SYNTHESIS Trials of anti-diabetic agents are now designed to assess CV safety, but frequently HF is not included as a primary endpoint. However, HF in patients with diabetes is more frequent than other CV events and seems to be underestimated. A burning question is therefore if the most used trial design to monitor CV safety, i.e. non-inferiority, allows clinical translation of trial findings. Available data further suggest that the CV effects of anti-diabetic drugs may be rather class-specific and are only partly due to their glucose-lowering actions. Metformin, recommended as first line in most guidelines, shows positive CV effects while other classes like thiazolidinediones may precipitate HF. Experimental results on the relatively novel dipeptidyl peptidase IV (DPP IV) inhibitors imply CV protective effects, but the non-inferiority trials published to date show an overall neutral CV outcome and a potential increase in HF by saxagliptin. However, results on sitagliptin of the recently released TECOS indicate that HF is not a class-dependent effect of DPP IV inhibitors. CONCLUSION Further basic research and long-term outcome studies to clarify the effects of antidiabetic agents on CV and HF are required so that we can select the optimal antidiabetic therapy for our patients.

The PDE4 inhibitor roflumilast reduces weight gain by increasing energy expenditure and leads to improved glucose metabolism.

To investigate the metabolic effects of the phosphodiesterase‐4 (PDE4) inhibitor roflumilast, a clinically approved anti‐inflammatory drug used for the treatment of chronic obstructive pulmonary disease.

Erratum: A Role for Timp3 in Microbiota-Driven Hepatic Steatosis and Metabolic Dysfunction (Cell Reports (2016) 16(3) (731–743) (S2211124716307677) (10.1016/j.celrep.2016.06.027))

Department of Systems Medicine, University of Rome Tor Vergata, 00133 Rome, Italy 5 Research Unit for Multi-Factorial Diseases, Obesity and Diabetes Scientific Directorate, Bambino 6 Gesù Children Hospital, 00146 Rome, Italy 7 3 Department of Internal Medicine I, University Hospital Aachen, D-52074 Aachen, Germany 8 INSERM U1048, Université Paul Sabatier, IMC, F-31432 Toulouse, France 9 5 Department of Public Health and Infectious Diseases, Sapienza University of Rome, 00161 Rome, 10 Italy 11 *Drs. Mavilio and Marchetti equally contributed 12

2-hydroxycaproate predicts cardiovascular mortality in patients with atherosclerotic disease

BACKGROUND AND AIMS We aimed to identify novel biomarkers for cardiovascular mortality through a non-targeted metabolomics approach in patients with established atherosclerotic disease from the Tor Vergata Atherosclerosis Registry (TVAR). METHODS We compared the serum baseline metabolome of 19 patients with atherosclerosis suffering from cardiovascular death during follow-up with the baseline serum metabolome of 20 control patients matched for age, gender, body mass index (BMI) and atherosclerotic disease status, who survived during the observation period. RESULTS Three metabolites were significantly different in the cardiovascular mortality (CVM) group compared to controls: 2-hydroxycaproate, gluconate and sorbitol. 2-hydroxycaproate (otherwise known as alpha hydroxy caproate) was also significantly correlated with time to death. The metabolites performed better when combined together rather than singularly on the identification of CVM status. CONCLUSIONS Our analysis led to identify few metabolites potentially amenable of translation into the clinical practice as biomarkers for specific metabolic changes in the cardiovascular system in patients with established atherosclerotic disease.

Can renin inhibition by Aliskiren prove itself in atherosclerosis prevention

The renin-angiotensin-aldosterone system (RAAS) regulates inflammation and vascular remodeling thus playing an important role in atherosclerosis, kidney disease and heart failure. As an example of this, the effector hormone Angiotensin II (AngII) was shown to promote oxidative stress, endothelial dysfunction and vascular inflammation [1], all of which would be detrimental. However, inhibiting the RAAS now goes beyond blood pressure reduction and is an important component of the baseline treatment of heart failure, cardiorenal syndrome and diabetic nephropathy. As an example of its protective role in atherosclerosis, the HOPE (Heart Outcomes Prevention Evaluation) trial showed a 37% risk reduction in cardiovascular death by Ramipril in people with diabetes [2]. Angiotensin receptor blockers (ARBs) and angiotensinconverting enzyme inhibitors (ACEIs) reduce effectively the production of AngII, but consequently increase plasma renin concentration because of the loss of negative feedback by AngII on renin. On one hand this might lead to a limited blockade of the RAAS, on the other it could lead to activation of possible alternative pathways by renin [3]. This issue raised the demand for different RAAS inhibitors. In 2007 the US Food and Drug Administration first approved Aliskiren. This orally active drug acts a direct renin antagonist, thereby antagonizing the rate-limiting step of the RAAS without raising the plasma renin activity. Plasma renin activity has