Basic Research in Cardiology最新文献

Mitochondrial calcium (Ca²⁺) signals play a central role in cardiac homeostasis and disease. In the healthy heart, mitochondrial Ca²⁺ levels modulate the rate of oxidative metabolism to match the rate of adenosine triphosphate consumption in the cytosol. During ischemia/reperfusion (I/R) injury, pathologically high levels of Ca²⁺ in the mitochondrial matrix trigger the opening of the mitochondrial permeability transition pore, which releases solutes and small proteins from the matrix, causing mitochondrial swelling and ultimately leading to cell death. Pharmacological and genetic approaches to tune mitochondrial Ca²⁺ handling by regulating the activity of the main Ca²⁺ influx and efflux pathways, i.e., the mitochondrial Ca²⁺ uniporter and sodium/Ca²⁺ exchanger, represent promising therapeutic strategies to protect the heart from I/R injury.

Understanding the mechanisms underlying vascular regeneration in the heart is crucial for developing novel therapeutic strategies for myocardial ischemia. This study investigates the contribution of bone marrow-derived cells to endothelial cell populations in the heart, and their role in cardiac function and coronary circulation following repetitive ischemia (RI). Chimeric rats were created by transplanting BM cells from GFP female rats into irradiated male recipients. After engraftment chimeras were subjected to RI for 17 days. Vascular growth was assessed from recovery of cardiac function and increases in myocardial blood flow during LAD occlusion. After sorting GFP⁺ BM cells from heart and bone of Control and RI rats, single-cell RNA sequencing was implemented to determine the fate of BM cells. Our in vivo RI model demonstrated an improvement in cardiac function and myocardial blood flow after 17 days of RI with increased capillary density in the rats subjected to RI compared to Controls. Single-cell RNA sequencing of bone marrow cells isolated from rats' hearts identified distinct endothelial cell (EC) subpopulations. These ECs exhibited heterogeneous gene expression profiles and were enriched for markers of capillary, artery, lymphatic, venous, and immune ECs. Furthermore, BM-derived ECs in the RI group showed an angiogenic profile, characterized by upregulated genes associated with blood vessel development and angiogenesis. This study elucidates the heterogeneity of bone marrow-derived endothelial cells in the heart and their response to repetitive ischemia, laying the groundwork for targeting specific subpopulations for therapeutic angiogenesis in myocardial ischemia.

Placental growth factor (PlGF)-2 induces angio- and arteriogenesis in rodents but its therapeutic potential in a clinically representative post-infarction left ventricular (LV) dysfunction model remains unclear. We, therefore, investigated the safety and efficacy of recombinant human (rh)PlGF-2 in the infarcted porcine heart in a randomized, placebo-controlled blinded study. We induced myocardial infarction (MI) in pigs using 75 min mid-LAD balloon occlusion followed by reperfusion. After 4 w, we randomized pigs with marked LV dysfunction (LVEF < 40%) to receive continuous intravenous infusion of 5, 15, 45 µg/kg/day rhPlGF-2 or PBS (CON) for 2 w using osmotic pumps. We evaluated the treatment effect at 8 w using comprehensive MRI and immunohistochemistry and measured myocardial PlGF-2 receptor transcript levels. At 4 w after MI, infarct size was 16-18 ± 4% of LV mass, resulting in significantly impaired systolic function (LVEF 34 ± 4%). In the pilot study (3 pigs/dose), PIGF administration showed sustained dose-dependent increases in plasma concentrations for 14 days without systemic toxicity and was associated with favorable post-infarct remodeling. In the second phase (n = 42), we detected no significant differences at 8 w between CON and PlGF-treated pigs in infarct size, capillary or arteriolar density, global LV function and regional myocardial blood flow at rest or during stress. Molecular analysis showed significant downregulation of the main PlGF-2 receptor, pVEGFR-1, in dysfunctional myocardium. Chronic rhPIGF-2 infusion was safe but failed to induce therapeutic neovascularization and improve global cardiac function after myocardial infarction in pigs. Our data emphasize the critical need for properly designed trials in representative large animal models before translating presumed promising therapies to patients.

The mitochondrial metabolite succinate is a key driver of ischemia/reperfusion injury (IRI). Targeting succinate metabolism by inhibiting succinate dehydrogenase (SDH) upon reperfusion using malonate is an effective therapeutic strategy to achieve cardioprotection in the short term (< 24 h reperfusion) in mouse and pig in vivo myocardial infarction (MI) models. We aimed to assess whether inhibiting IRI with malonate given upon reperfusion could prevent post-MI heart failure (HF) assessed after 28 days. Male C57BL/6 J mice were subjected to 30 min left anterior coronary artery (LAD) occlusion, before reperfusion for 28 days. Malonate or without-malonate control was infused as a single dose upon reperfusion. Cardiac function was assessed by echocardiography and fibrosis by Masson's trichrome staining. Reperfusion without malonate significantly reduced ejection fraction (~ 47%), fractional shortening (~ 23%) and elevated collagen deposition 28 days post-MI. Malonate, administered as a single infusion (16 mg/kg/min for 10 min) upon reperfusion, gave a significant cardioprotective effect, with ejection fraction (~ 60%) and fractional shortening (~ 30%) preserved and less collagen deposition. Using an acidified malonate formulation, to enhance its uptake into cardiomyocytes via the monocarboxylate transporter 1, both 1.6 and 16 mg/kg/min 10 min infusion led to robust long-term cardioprotection with preserved ejection fraction (> 60%) and fractional shortening (~ 30%), as well as significantly less collagen deposition than control hearts. Malonate administration upon reperfusion prevents post-MI HF. Acidification of malonate enables lower doses of malonate to also achieve long-term cardioprotection post-MI. Therefore, the administration of acidified malonate upon reperfusion is a promising therapeutic strategy to prevent IRI and post-MI HF.

Succinate accumulates during myocardial ischemia and is rapidly oxidized during reperfusion, leading to reactive oxygen species (ROS) production through reverse electron transfer (RET) from mitochondrial complex II to complex I, and favoring cell death. Given that connexin 43 (Cx43) modulates mitochondrial ROS production, we investigated whether Cx43 influences RET using inducible knock-out Cx43^Cre-ER(T)/fl mice. Oxygen consumption, ROS production, membrane potential and coenzyme Q (CoQ) pool were analyzed in subsarcolemmal (SSM, expressing Cx43) and interfibrillar (IFM) cardiac mitochondria isolated from wild-type Cx43^fl/fl mice and Cx43^Cre-ER(T)/fl knock-out animals treated with 4-hydroxytamoxifen (4OHT). In addition, infarct size was assessed in isolated hearts from these animals submitted to ischemia-reperfusion (IR), and treated or not with malonate, a complex II inhibitor attenuating RET. Succinate-dependent ROS production and RET were significantly lower in SSM, but not IFM, from Cx43-deficient animals. Mitochondrial membrane potential, a RET driver, was similar between groups, whereas CoQ pool (2.165 ± 0.338 vs. 4.18 ± 0.55 nmol/mg protein, p < 0.05) and its reduction state were significantly lower in Cx43-deficient animals. Isolated hearts from Cx43^Cre-ER(T)/fl mice treated with 4OHT had a smaller infarct size after IR compared to Cx43^fl/fl, despite similar concentration of succinate at the end of ischemia, and no additional protection by malonate. Cx43 deficiency attenuates ROS production by RET in SSM, but not IFM, and was associated with a decrease in CoQ levels and a change in its redox state. These results may partially explain the reduced infarct size observed in these animals and their lack of protection by malonate.

Sodium glucose cotransporter 2 inhibitors (SGLT2i) constitute the only medication class that consistently prevents or attenuates human heart failure (HF) independent of ejection fraction. We have suggested earlier that the protective mechanisms of the SGLT2i Empagliflozin (EMPA) are mediated through reductions in the sodium hydrogen exchanger 1 (NHE1)-nitric oxide (NO) pathway, independent of SGLT2. Here, we examined the role of SGLT2, NHE1 and NO in a murine TAC/DOCA model of HF. SGLT2 knockout mice only showed attenuated systolic dysfunction without having an effect on other signs of HF. EMPA protected against systolic and diastolic dysfunction, hypertrophy, fibrosis, increased Nppa/Nppb mRNA expression and lung/liver edema. In addition, EMPA prevented increases in oxidative stress, sodium calcium exchanger expression and calcium/calmodulin-dependent protein kinase II activation to an equal degree in WT and SGLT2 KO animals. In particular, while NHE1 activity was increased in isolated cardiomyocytes from untreated HF, EMPA treatment prevented this. Since SGLT2 is not required for the protective effects of EMPA, the pathway between NHE1 and NO was further explored in SGLT2 KO animals. In vivo treatment with the specific NHE1-inhibitor Cariporide mimicked the protection by EMPA, without additional protection by EMPA. On the other hand, in vivo inhibition of NOS with L-NAME deteriorated HF and prevented protection by EMPA. In conclusion, the data support that the beneficial effects of EMPA are mediated through the NHE1-NO pathway in TAC/DOCA-induced heart failure and not through SGLT2 inhibition.

Immune checkpoint inhibitor (ICI) therapy represents a ground-breaking paradigm in cancer treatment, harnessing the immune system to combat malignancies by targeting checkpoints such as cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) and programmed cell death protein 1 (PD-1). The use of ICI therapy generates distinctive immune-related adverse events (irAEs) including cardiovascular toxicity, necessitating targeted research efforts. This comprehensive review explores preclinical models dedicated to ICI-mediated cardiovascular complications including myocarditis. Tailored preclinical models of ICI-mediated myocardial toxicities highlight the key role of CD8⁺ T cells, emphasizing the profound impact of immune checkpoints on maintaining cardiac integrity. Cytokines and macrophages were identified as possible driving factors in disease progression, and at the same time, initial data on possible cardiac antigens responsible are emerging. The implications of contributing factors including thoracic radiation, autoimmune disorder, and the presence of cancer itself are increasingly understood. Besides myocarditis, mouse models unveiled an accelerated progression of atherosclerosis, adding another layer for a thorough understanding of the diverse processes involving cardiovascular immune checkpoint signalling. This review aims to discuss current preclinical models of ICI cardiotoxicity and their potential for improving enhanced risk assessment and diagnostics, offering potential targets for innovative cardioprotective strategies. Lessons from ICI therapy can drive novel approaches in cardiovascular research, extending insights to areas such as myocardial infarction and heart failure.

Immune checkpoint inhibitors (ICIs) have revolutionized cancer therapy by unleashing the power of the immune system against malignant cells. However, their use is associated with a spectrum of adverse effects, including cardiovascular complications, which can pose significant clinical challenges. Several mechanisms contribute to cardiovascular toxicity associated with ICIs. First, the dysregulation of immune checkpoints, such as cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) and programmed cell death protein-1 (PD-1) and its ligand (PD-L1), and molecular mimicry with cardiac autoantigens, leads to immune-related adverse events, including myocarditis and vasculitis. These events result from the aberrant activation of T cells against self-antigens within the myocardium or vascular endothelium. Second, the disruption of immune homeostasis by ICIs can lead to autoimmune-mediated inflammation of cardiac tissues, manifesting as cardiac dysfunction and heart failure, arrhythmias, or pericarditis. Furthermore, the upregulation of inflammatory cytokines, particularly tumor necrosis factor-alpha, interferon-γ, interleukin-1β, interleukin-6, and interleukin-17 contributes to cardiac and endothelial dysfunction, plaque destabilization, and thrombosis, exacerbating cardiovascular risk on the long term. Understanding the intricate mechanisms of cardiovascular side effects induced by ICIs is crucial for optimizing patient care and to ensure the safe and effective integration of immunotherapy into a broader range of cancer treatment protocols. The clinical implications of these mechanisms underscore the importance of vigilant monitoring and early detection of cardiovascular toxicity in patients receiving ICIs. Future use of these key pathological mediators as biomarkers may aid in prompt diagnosis of cardiotoxicity and will allow timely interventions.

Propionic acidemia (PA), arising from PCCA or PCCB variants, manifests as life-threatening cardiomyopathy and arrhythmias, with unclear pathophysiology. In this work, propionyl-CoA metabolism in rodent hearts and human pluripotent stem cell-derived cardiomyocytes was investigated with stable isotope tracing analysis. Surprisingly, gut microbiome-derived propionate rather than the propiogenic amino acids (valine, isoleucine, threonine, and methionine) or odd-chain fatty acids was found to be the primary cardiac propionyl-CoA source. In a Pcca^-/-(A138T) mouse model and PA patients, accumulated propionyl-CoA and diminished acyl-CoA synthetase short-chain family member 3 impede hepatic propionate disposal, elevating circulating propionate. Prolonged propionate exposure induced significant oxidative stress in PCCA knockdown HL-1 cells and the hearts of Pcca^-/-(A138T) mice. Additionally, Pcca^-/-(A138T) mice exhibited mild diastolic dysfunction after the propionate challenge. These findings suggest that elevated circulating propionate may cause oxidative damage and functional impairment in the hearts of patients with PA.

Sodium-glucose cotransporter 2 inhibitors (SGLT2i), a new drug class initially designed and approved for treatment of diabetes mellitus, have been shown to exert pleiotropic metabolic and direct cardioprotective and nephroprotective effects that extend beyond their glucose-lowering action. These properties prompted their use in two frequently intertwined conditions, heart failure and chronic kidney disease. Their unique mechanism of action makes SGLT2i an attractive option also to lower the rate of cardiac events and improve overall survival of oncological patients with preexisting cardiovascular risk and/or candidate to receive cardiotoxic therapies. This review will cover biological foundations and clinical evidence for SGLT2i modulating myocardial function and metabolism, with a focus on their possible use as cardioprotective agents in the cardio-oncology settings. Furthermore, we will explore recently emerged SGLT2i effects on hematopoiesis and immune system, carrying the potential of attenuating tumor growth and chemotherapy-induced cytopenias.