Empagliflozin (EMPA), a drug approved for type 2 diabetes management, reduced cardiovascular death but is unknown if it reduces myocardial infarction. We sought to investigate: (i) the effect of EMPA on myocardial function and infarct size after ischemia/reperfusion in mice fed with western diet (WD), (ii) the underlying signaling pathways, (iii) its effects on cell survival in rat embryonic-heart-derived cardiomyoblasts (H9C2) and endothelial cells (ECs). To facilitate the aforementioned aims, mice were initially randomized in Control and EMPA groups and were subjected to 30 min ischemia and 2 h reperfusion. EMPA reduced body weight, blood glucose levels, and mean arterial pressure. Cholesterol, triglyceride, and AGEs remained unchanged. Left ventricular fractional shortening was improved (43.97 ± 0.92 vs. 40.75 ± 0.61%) and infarct size reduced (33.2 ± 0.01 vs. 17.6 ± 0.02%). In a second series of experiments, mice were subjected to the above interventions up to the 10th min of reperfusion and myocardial biopsies were obtained for assessment of the signaling cascade. STAT3 was increased in parallel with reduced levels of malondialdehyde (MDA) and reduced expression of myocardial iNOS and interleukin-6. Cell viability and ATP content were increased in H9C2 and in ECs. While, STAT3 phosphorylation is known to bestow infarct sparing properties through interaction with mitochondria, we observed that EMPA did not directly alter the mitochondrial calcium retention capacity (CRC); therefore, its effect in reducing myocardial infarction is STAT3 dependent. In conclusion, EMPA improves myocardial function and reduces infarct size as well as improves redox regulation by decreasing iNOS expression and subsequently lipid peroxidation as shown by its surrogate marker MDA. The mechanisms of action implicate the activation of STAT3 anti-oxidant and anti-inflammatory properties.

Background-Toll-like receptors (TLRs) have long been considered to be major culprits in the development of atherosclerosis, contributing both to its progression and clinical complications. However, evidence for most TLRs beyond TLR2 and TLR4 is lacking. Methods and Results-We used experimental mouse models, human atheroma cultures, and well-established human biobanks to investigate the role of TLR7 in atherosclerosis. We report the unexpected finding that TLR7, a receptor recognizing self-nucleic acid complexes, is protective in atherosclerosis. In Apoe Ϫ/Ϫ mice, functional inactivation of TLR7 resulted in accelerated lesion development, increased stenosis, and enhanced plaque vulnerability as revealed by Doppler ultrasound and/or histopathology. Mechanistically, TLR7 interfered with macrophage proinflammatory responses to TLR2 and TLR4 ligands, reduced monocyte chemoattractant protein-1 production, and prevented expansion of Ly6C hi inflammatory monocytes and accumulation of inflammatory M1 macrophages into developing atherosclerotic lesions. In human carotid endarterectomy specimens TLR7 levels were consistently associated with an M2 anti-inflammatory macrophage signature (interleukin [IL]-10, IL-1RA, CD163, scavenger and C-type lectin receptors) and collagen genes, whereas they were inversely related or unrelated to proinflammatory mediators (IL-12/IL-23, interferon beta, interferon gamma, CD40L) and platelet markers. Moreover, in human atheroma cultures, TLR7 activation selectively suppressed the production of key proatherogenic factors such as monocyte chemoattractant protein-1 and tumor necrosis factor without affecting IL-10. Conclusions-These findings provide evidence for a beneficial role of TLR7 in atherosclerosis by constraining inflammatory macrophage activation and cytokine production. This challenges the prevailing concept that all TLRs are pathogenic and supports the exploitation of the TLR7 pathway for therapy. (Circulation. 2012;126:952-962.)Key Words: atherosclerosis Ⅲ immune system Ⅲ inflammation Ⅲ macrophage Ⅲ Toll-like receptor C hronic inflammation is an integral part of the pathogenesis of atherosclerosis. 1,2 Accumulation of lipoproteins in the vessel wall, especially at areas of disturbed blood flow such as bifurcations and the lesser curvature of the aortic arch, induces a chronic inflammatory response characterized by the mobilization of monocytes in the periphery, the infiltration of macrophages, dendritic cells, and lymphocytes in the arterial intima, and the expression of proinflammatory cytokines, chemokines, and matrix metalloproteinases. This leads to luminal narrowing and often plaque rupture and myocardial infarction or stroke, the most severe clinical complications of atherosclerosis. Therefore, identifying ratelimiting molecular processes and pathways that contribute to the development or persistence of inflammation in the vessel wall is key to the future treatment of this disease. 3 Clinical Perspective on p 962Toll-like receptors (TLRs) have recently taken center stage in a...

Carfilzomib (Cfz), an irreversible proteasome inhibitor licensed for relapsed/refractory myeloma, is associated with cardiotoxicity in humans. We sought to establish the optimal protocol of Cfz-induced cardiac dysfunction, to investigate the underlying molecular-signaling and, based on the findings, to evaluate the cardioprotective potency of metformin (Met). Mice were randomized into protocols 1 and 2 (control and Cfz for 1 and 2 consecutive days, respectively); protocols 3 and 4 (control and alternate doses of Cfz for 6 and 14 days, respectively); protocols 5A and 5B (control and Cfz, intermittent doses on days 0, 1 [5A] and 0, 1, 7, and 8 [5B] for 13 days); protocols 6A and 6B (pharmacological intervention; control, Cfz, Cfz+Met and Met for 2 and 6 days, respectively); and protocol 7 (bortezomib). Cfz was administered at 8 mg/kg (IP) and Met at 140 mg/kg (per os). Cfz resulted in significant reduction of proteasomal activity in heart and peripheral blood mononuclear cells in all protocols except protocols 5A and 5B. Echocardiography demonstrated that Cfz led to a significant fractional shortening (FS) depression in protocols 2 and 3, a borderline dysfunction in protocols 1 and 4, and had no detrimental effect on protocols 5A and 5B. Molecular analysis revealed that Cfz inhibited AMPKα/mTORC1 pathways derived from increased PP2A activity in protocol 2, whereas it additionally inhibited phosphatidylinositol 3-kinase/Akt/endothelial nitric oxide synthase pathway in protocol 3. Coadministration of Met prevented Cfz-induced FS reduction and restored AMPKα phosphorylation and autophagic signaling. Conclusively, Cfz decreased left ventricular function through increased PP2A activity and inhibition of AMPKα and its downstream autophagic targets, whereas Met represents a novel promising intervention against Cfz-induced cardiotoxicity.

Cardiomyocyte death due to desmin deficiency leads to inflammation and subsequent overexpression of a series of remodelling modulators. Among them, OPN seems to be a major regulator of des(-/-) adverse myocardial remodelling and it functions at least by potentiating galectin-3 up-regulation and secretion.

The association of desmin with the α-crystallin Β-chain (αΒ-crystallin; encoded by CRYAB), and the fact that mutations in either one of them leads to heart failure in humans and mice, suggests a potential compensatory interplay between the two in cardioprotection. To address this hypothesis, we investigated the consequences of αΒ-crystallin overexpression in the desmin-deficient (Des) mouse model, which possesses a combination of the pathologies found in most cardiomyopathies, with mitochondrial defects as a hallmark. We demonstrated that cardiac-specific αΒ-crystallin overexpression ameliorates all these defects and improves cardiac function to almost wild-type levels. Protection by αΒ-crystallin overexpression is linked to maintenance of proper mitochondrial protein levels, inhibition of abnormal mitochondrial permeability transition pore activation and maintenance of mitochondrial membrane potential (Δψ m ). Furthermore, we found that both desmin and αΒ-crystallin are localized at sarcoplasmic reticulum (SR)-mitochondria-associated membranes (MAMs), where they interact with VDAC, Mic60 -the core component of mitochondrial contact site and cristae organizing system (MICOS) complex -and ATP synthase, suggesting that these associations could be crucial in mitoprotection at different levels.