Ligation Of Left Anterior Descending Artery Research Articles

SLAMF1-derived peptide exhibits cardio protection after permanent left anterior descending artery ligation in mice.

Acute myocardial infarction (MI) results in tissue damage to affected areas of the myocardium. The initial inflammatory response is the most damaging for residual cardiac function, while at later stages inflammation is a prerequisite for proper healing and scar formation. Balancing the extent and duration of inflammation during various stages after MI is thus pivotal for preserving cardiac function. Recently, a signaling lymphocytic activation molecule 1 (SLAMF1)-derived peptide (P7) was shown to reduce the secretion of inflammatory cytokines and protected against acute lipopolysaccharide-induced death in mice. In the present study, we experimentally induced MI by permanent ligation of the left anterior descending artery (LAD) in mice and explored the beneficial effect of immediately administering P7, with the aim of dampening the initial inflammatory phase without compromising the healing and remodeling phase. Blood samples taken 9h post-LAD surgery and P7 administration dampened the secretion of inflammatory cytokines, but this dampening effect of P7 was diminished after 3 days. Echocardiography revealed less deterioration of cardiac contraction in mice receiving P7. In line with this, less myocardial damage was observed histologically in P7-treated mice. In conclusion, the administration of a SLAMF1-derived peptide (P7) immediately after induction of MI reduces the initial myocardial inflammation, reduces infarct expansion, and leads to less deterioration of cardiac contraction.

Abstract 18418: Osteoprotegerin Mediates T-Cell Response in Myocardial Wound Healing Post-Ischemic Injury

Introduction: Myocardial Infarction (MI) triggers an inflammatory response associated with cardiac wound healing. T-regulatory cells (Tregs) play a crucial role in the MI heart during this inflammatory response via their regulation of cardiac repair and function. Stimulating and sustaining the pro-reparative T cell response after MI would aid in preserving cardiac structure and function. Cortical Bone derived Stem Cells (CBSCs) possess a diverse array of inflammatory signaling molecules that can influence the inflammatory microenvironment of the heart after MI. A paracrine factor, Osteoprotegerin (OPG), is abundantly present in CBSCs, but it is unknown if OPG can mediate Tregs in myocardial injury. Hypothesis: CBSCs-derived Osteoprotegerin can regulate cardiac wound healing post-MI by modulating T cell response. Methods and Results: T cells exposed to CBSC secretome underwent an upregulation of a Treg population (p≤0.0001) characterized by the expression of Tumor Necrosis Factor Receptor II (TNFRII). Further investigation into the CBSC secretome highlighted OPG as a potent signaling molecule responsible for inducing TNFRII+ Tregs (p≤0.0001) measured by FACS analysis. siRNA-mediated depletion of OPG studies showed compromised TNFRII+ Treg induction (p≤0.0001). In vivo studies, adult FoxP3-GFP (12-16 week) mice underwent left anterior descending artery ligation followed by intramyocardial injection of CBSCs, Mesenchymal Stem Cells (MSCs), or vehicle (saline) along the infarct border zone. Resident T-lymphocyte populations were assessed at 1- and 8-weeks post-MI via flow cytometry. CBSC-treated hearts yielded a greater prevalence of TNFRII+ Tregs at 1- and 8-weeks following MI compared to MSCs (p≤0.01; p≤0.0001) and vehicle (p≤0.0001; p≤0.05). CBSC induction following MI reduced infarct size compared to the vehicle (p≤0.05). Ablation of the Treg population in the ischemic zone following MI increased infarct size and solicited adverse cardiac remodeling (p≤0.05). Conclusion: Osteoprotegerin can promote cardiac wound healing by facilitating the expansion and preservation of pro-reparative TNFRII+ Tregs.

Abstract 17513: Decreased Sensory Neurotransmission Due to Neuronal Mitochondrial Dysfunction Mediates Sex Differences in Vagal Remodeling After Myocardial Infarction

Background: Vagal dysfunction after chronic myocardial infarction (MI) exacerbates heart failure and predisposes to ventricular tachyarrhythmias (VT/VF). VT/VF after MI is more common in males than females. The mechanisms behind these sex differences are unknown. Hypothesis: We hypothesized that differences in autonomic remodeling in the vagal ganglia, which in a healthy state, provide beat-to-beat sensory neurotransmission and modulate efferent cardiac vagal tone, may serve as the mechanisms behind the sex differences in the incidence of VT/VF. Methods: MI was created (left anterior descending artery ligation) in male and female mice expressing channel rhodopsin in glutamatergic vagal neurons (VGlut2-ChR2-EYFP mice). Sham animals underwent thoracotomy only. Two weeks post-MI, heart rate (HR) responses were assessed following in vivo vagal afferent nerve activation via optogenetic stimulation (5 sec duration, 20 Hz, 10 ms and 20 ms stimulations). Ventricular fibrosis was quantified. Mitochondrial oxygen consumption rates (OCR), glutamate levels, and the levels of oxidative stress marker, 4-hydroxy nonenal (4HNE), were measured in the vagal ganglia. Results: Male MI animals demonstrated significantly reduced HR responses to optogenetic stimulation than female MI animals. No sex differences in the degree of ventricular fibrosis was observed. A decrease in glutamate content accompanied by decreased mitochondrial OCR and increased 4HNE levels was observed in the vagal ganglia of male infarcted vs. female infarcted mice, figure. There were no differences in the HR responses, glutamate content, mitochondrial OCR, and 4HNE levels between sham males vs. sham females. Conclusion: This study demonstrates significant sex differences in vagal remodeling post-MI, with decreased efferent vagal tone in males mediated at least in part by reduced vagal afferent glutamatergic signaling associated with impaired neuronal mitochondrial function.

Myocardial stretch-induced compliance is abrogated under ischemic conditions and restored by cGMP/PKG-related pathways.

Introduction: Management of acute myocardial infarction (MI) mandates careful optimization of volemia, which can be challenging due to the inherent risk of congestion. Increased myocardial compliance in response to stretching, known as stretch-induced compliance (SIC), has been recently characterized and partly ascribed to cGMP/cGMP-dependent protein kinase (PKG)-related pathways. We hypothesized that SIC would be impaired in MI but restored by activation of PKG, thereby enabling a better response to volume loading in MI. Methods: We conducted experiments in ex vivo rabbit right ventricular papillary muscles under ischemic and non-ischemic conditions as well as pressure-volume hemodynamic evaluations in experimental in vivo MI induced by left anterior descending artery ligation in rats. Results: Acutely stretching muscles ex vivo yielded increased compliance over the next 15min, but not under ischemic conditions. PKG agonists, but not PKC agonists, were able to partially restore SIC in ischemic muscles. A similar effect was observed with phosphodiesterase-5 inhibitor (PDE5i) sildenafil, which was amplified by joint B-type natriuretic peptide or nitric oxide donor administration. In vivo translation revealed that volume loading after MI only increased cardiac output in rats infused with PDE5i. Contrarily to vehicle, sildenafil-treated rats showed a clear increase in myocardial compliance upon volume loading. Discussion: Our results suggest that ischemia impairs the adaptive myocardial response to acute stretching and that this may be partly prevented by pharmacological manipulation of the cGMP/PKG pathway, namely, with PDE5i. Further studies are warranted to further elucidate the potential of this intervention in the clinical setting of acute myocardial ischemia.

Novel approaches to determine the functional role of cardiomyocyte specific E3 ligase, Pellino-1 following myocardial infarction

ObjectivesUbiquitination plays a vital role in controlling vascular inflammation, cellular protein quality control, and minimizing misfolded protein toxicity. Pellino-1 (Peli1), a type of E3 ubiquitin ligase, has emerged as a critical regulator of the innate immune response; however, its role in the repair and regeneration of ischemic myocardium remains to be elucidated. MethodsMice (8-12 weeks old, male and females) were divided into (i) Wild type (ii) cardiomyocyte-specific Peli1 overexpressed (AMPEL1Tg/+), (iii) cardiomyocyte-specific Peli1 knockout (CP1KO) and were subjected to sham and left anterior descending artery ligation. The tissues were collected at various time points after surgery for Western blot, and immunohistochemical analyses. Echocardiography is performed 30 days after myocardial infarction. Cardiomyocytes isolated from wild-type, Peli1 overexpressed and knockout mice were used to study the interaction between cardiomyocytes and endothelial cells in vitro under oxidative stress and cells were used for Western blot, flow cytometric analysis, and scratch assay. ResultsWe observed faster wound closure and increased expression of angiogenic factors with MCECs treated with conditioned media obtained from the AMPEL1Tg/+ cardiomyocytes compared to CPIKO and WT cardiomyocytes. Again, AMPEL1Tg/+MI mice showed preserved systolic function and reduced fibrosis compared to the CPIKOMI and WTMI groups. Capillary and arteriolar density were found to be increased in AMPEL1Tg/+MI compared to CP1KOMI. Increased survival and angiogenic factors such as p-Akt, p-MK2, p-IkBα, VEGF, cIAP2, and Bcl2 were observed in AMPEL1Tg/+ compared to CP1KO and WT mice subjected to MI. ConclusionThe present study uncovers the crucial role of cardiac Peli1 as a regulator of the repair and regeneration of ischemic myocardium by using multiple genetically engineered mouse models.

Inhibition of gasdermin D palmitoylation by disulfiram is crucial for the treatment of myocardial infarction

To investigate the role of S-palmitoylation in pyroptosis following acute myocardial infarction (AMI). Myocardial ischemic injury is mainly related to the death of terminally differentiated cardiomyocytes. Pyroptosis is a new form of programmed cell death and recently is identified a potential mechanism of cardiomyocyte loss. However, the role of S-palmitoylation in pyroptosis following MI remains elusive. AMI was mimicked by permanent left anterior descending artery ligation. The palmitoylated proteins labeled by Click-iT palmitic acid were precipitated using streptavidin magnetic bead conjugate. The short-term palmitic acid dietary intake by modified western diet with palm oil for 7 days is compared with modified western diet with olive oil. Palmitoylation is increased in myocardial infarction and anoxic cardiomyocytes. Pyroptosis, but not apoptosis and necrosis, is more relevant with palmitoylation in the process of myocardial ischemia injury. The gasdermin D (GSDMD) Cys192 palmitoylation promotes its cytomembrane localization by ZDHHC14. GSDMD Cys192 palmitoylation aggravates in vitro cardiomyocyte pyroptosis. The short-term palmitic acid dietary intake or ML348 deteriorates myocardial pyroptosis, infarct size and cardiac function in AMI mice by GSDMD palmitoylation. Disulfiram antagonizes Cys192 palmitoylation of GSDMD-N-terminal and reduces myocardial pyroptosis and injury in AMI mice. We identifies ZHDDC14 induced palmitoylation as a crucial node for modulating GSDMD-N-terminal cytomembrane localization and establishes Disulfiram targeting GSDMD Cys192 palmitoylation as a potential clinical intervention for myocardial pyroptosis.

ALKBH5 induces fibroblast-to-myofibroblast transformation during hypoxia to protect against cardiac rupture after myocardial infarction

IntroductionN6-methyladenosine (m6A) methylation produces a marked effect on cardiovascular diseases. The m6A demethylase AlkB homolog 5 (ALKBH5), as an m6A “eraser”, is responsible for decreased m6A modification. However, its role in cardiac fibroblasts during the post-myocardial infarction (MI) healing process remains elusive. ObjectivesTo investigate the effect of ALKBH5 in cardiac fibroblasts during infarct repair. MethodsMI was mimicked by permanent left anterior descending artery ligation in global ALKBH5-knockout, ALKBH5-knockin, and fibroblast-specific ALKBH5-knockout mice to study the function of ALKBH5 during post-MI collagen repair. Methylated RNA immunoprecipitation sequencing was performed to explore potential ALKBH5 targets. ResultsDramatic alterations in ALKBH5 expression were observed during the early stages post-MI and in hypoxic fibroblasts. Global ALKBH5 knockin reduced infarct size and ameliorated cardiac function after MI. The global and fibroblast-specific ALKBH5-knockout mice both exhibited low survival rates along with poor collagen repair, impaired cardiac function, and cardiac rupture. Both in vivo and in vitro ALKBH5 loss resulted in impaired fibroblast activation and decreased collagen deposition. Additionally, hypoxia, but not TGF-β1 or Ang II, upregulated ALKBH5 expression in myofibroblasts by HIF-1α-dependent transcriptional regulation. Mechanistically, ALKBH5 promoted the stability of ErbB4 mRNA and the degradation of ST14 mRNA via m6A demethylation. Fibroblast-specific ErbB4 overexpression ameliorated the impaired fibroblast-to-myofibroblast transformation and poor post-MI repair due to ALKBH5 knockout. ConclusionFibroblast ALKBH5 positively regulates post-MI healing by stabilization of ErbB4 mRNA in an m6A-dependent manner. ALKBH5/ErbB4 might be potential therapeutic targets for post-MI cardiac rupture.

Pleiotropic effects of extracellular vesicles from induced pluripotent stem cell–derived cardiomyocytes on ischemic cardiomyopathy: A preclinical study

Stem cell-secreted extracellular vesicles (EVs) play essential roles in intercellular communication and restore cardiac function in animal models of ischemic heart disease. However, few studies have used EVs derived from clinical-grade stem cells and their derivatives with stable quality. Moreover, there is little information on the mechanism and time course of the multifactorial effect of EV therapy from the acute to the chronic phase, the affected cells, and whether the effects are direct or indirect. Induced pluripotent stem cell-derived cardiomyocytes (iPSCM) were produced using a clinical-grade differentiation induction system. EVs were isolated from the conditioned medium by ultracentrifugation and characterized in silico, in vitro, and in vivo. A rat model of myocardial infarction was established by left anterior descending artery ligation and treated with iPSCM-derived EVs. iPSCM-derived EVs contained microRNAs and proteins associated with angiogenesis, antifibrosis, promotion of M2 macrophage polarization, cell proliferation, and antiapoptosis. iPSCM-derived EV treatment improved left ventricular function and reduced mortality in the rat model by improving vascularization and suppressing fibrosis and chronic inflammation in the heart. EVs were uptaken by cardiomyocytes, endothelial cells, fibroblasts, and macrophages in the cardiac tissues. The pleiotropic effects occurred due to the direct effects of microRNAs and proteins encapsulated in EVs and indirect paracrine effects on M2 macrophages. Clinical-grade iPSCM-derived EVs improve cardiac function by regulating various genes and pathways in various cell types and may have clinical potential for treating ischemic heart disease.

Abstract P2151: A Novel, Micellized Naringenin Nanoparticle Rescues Hemodynamic Function Post-Myocardial Infarction Via MARK4 Inhibition

Impaired contractility and associated shock are significant contributors to morbidity after myocardial infarction (MI). Elevated MARK4 activity after MI impairs contractility by increasing α-tubulin detyrosination. As such, we developed a nanoparticle-based therapeutic strategy to enhance myocyte function with a small molecule MARK4 inhibitor (naringenin) and tested its ability to improve myocyte function in a rat model of MI. Naringenin was encapsulated in PEO-PCL to augment bioavailability. Adult Wistar rats underwent thoracotomy and were randomized to receive either: MI + myocardial injection of micellized naringenin (0.3 mg/kg) [MI-Nar], MI + empty micelle [MI-Mic], MI alone [MI-Untreated], or no MI [Sham]. MI was achieved with left anterior descending artery ligation. On pressure-volume hemodynamic assessment 24 hours post-thoracotomy, MI-Nar rats had higher ejection fractions than MI-Mic or MI-Untreated rats (63±3% v. 48±5% vs. 39±4%, p<0.05) and similar levels to Sham rats (61±1%, p=0.97). MI-Nar rats had greater stroke work, and lower end-diastolic pressure and tau than MI-Untreated rats (all p<0.05). Isolated myocytes from infarct border zones had increased contraction and relaxation velocity in MI-Nar versus MI-Untreated rats (both p<0.0001; Fig. 1A, B). Improved function was associated with decreased α-tubulin detyrosination in MI-Nar versus MI-Untreated rats on Western blot (p<0.05; Fig. 1C, D). These data support small molecule inhibition of MARK4 via micellized naringenin as a novel strategy to rescue hemodynamics post-MI by mitigating myocardial α-tubulin detyrosination and enhancing myocyte function.

Protective effects of liriodendrin on myocardial infarction-induced fibrosis in rats via the PI3K/Akt autophagy pathway: A network pharmacology study.

Liriodendrin (LIR) has been reported to improve cardiac function in rats following myocardial infarction. However, its role and mechanism in reparative myocardial fibrosis remain unclear. In this study, a rat model of myocardial fibrosis was established via left anterior descending artery ligation and randomly divided into three groups (n = 6 per group): sham-operated, myocardial infarction, and LIR intervention (100 mg/kg/day) groups. The pharmacological effects of LIR were assessed using echocardiography, hematoxylin, and eosin (H&E) staining, and Masson staining. Network pharmacology and bioinformatics were utilized to identify potential mechanisms of LIR, which were further validated via western blot analysis. Our findings demonstrated that LIR improved cardiac function, histology scores, and collagen volume fraction. Moreover, LIR downregulated the expression of Beclin-1, LC3-II, and LC3-I while upregulating the expression of p62, indicating LIR-activated autophagy in the heart after myocardial infarction. Further analysis revealed that the PI3K/Akt signaling pathway was significantly enriched and validated by western blot. This analysis suggested that the ratios of p-PI3K/PI3K, p Akt/Akt, and p-mTOR/mTOR were significantly increased. LIR may attenuate myocardial infarction-induced fibrosis in rats by inhibiting excessive myocardial autophagy, with the potential mechanism involving the activation of the PI3K/Akt/mTOR pathway.

CTRP12 ameliorates post-myocardial infarction heart failure through down-regulation of cardiac apoptosis, oxidative stress and inflammation by influencing the TAK1-p38 MAPK/JNK pathway.

C1q/tumour necrosis factor-related protein 12 (CTRP12) is closely related to coronary artery disease and has an outstanding cardioprotective effect. However, whether CTRP12 participates in heart failure (HF) has not been well studied. This work aimed to explore the role and mechanism of CTRP12 in post-myocardial infarction (MI) HF. Rats were subjected to left anterior descending artery ligation and then raised for six weeks to establish post-MI HF. Recombinant adeno-associated virus-mediated gene transfer was applied to overexpress or silence CTRP12 in rat hearts. RT-qPCR, Immunoblot, Echocardiography, Haematoxylin-eosin (HE) staining, Masson's trichrome staining, TUNEL staining and ELISA were carried out. CTRP12 levels were decreased in the hearts of rats with post-MI HF. The overexpression of CTRP12 improved cardiac function and attenuated cardiac hypertrophy and fibrosis in rats with post-MI HF. CTRP12 silencing exacerbated cardiac dysfunction, hypertrophy and fibrosis in rats with post-MI HF. The cardiac apoptosis, oxidative stress and inflammatory response induced by post-MI HF were weakened by CTRP12 overexpression or aggravated by CTRP12 silencing. CTRP12 inhibited the activation of the transforming growth factor-β activated kinase 1 (TAK1)-p38 mitogen-activated protein kinase (MAPK)/c-Jun N-terminal kinase (JNK) pathway in the hearts of rats with post-MI HF. Treatment with the TAK1 inhibitor reversed the adverse effects of CTRP12 silencing on post-MI HF. CTRP12 protects against post-MI HF by modulating the TAK1-p38 MAPK/JNK pathway. CTRP12 may be a therapeutic target for the treatment of post-MI HF.

Monomeric C-reactive protein: A novel biomarker predicting neurodegenerative disease and vascular dysfunction.

Circulating C-reactive protein (pCRP) concentrations rise dramatically during both acute (e.g., following stroke) or chronic infection and disease (e.g., autoimmune conditions such as lupus), providing complement fixation through C1q protein binding. It is now known, that on exposure to the membranes of activated immune cells (and microvesicles and platelets), or damaged/dysfunctional tissue, it undergoes lysophosphocholine (LPC)-phospholipase-C-dependent dissociation to the monomeric form (mCRP), concomitantly becoming biologically active. We review histological, immunohistochemical, and morphological/topological studies of post-mortem brain tissue from individuals with neuroinflammatory disease, showing that mCRP becomes stably distributed within the parenchyma, and resident in the arterial intima and lumen, being "released" from damaged, hemorrhagic vessels into the extracellular matrix. The possible de novo synthesis via neurons, endothelial cells, and glia is also considered. In vitro, in vivo, and human tissue co-localization analyses have linked mCRP to neurovascular dysfunction, vascular activation resulting in increased permeability, and leakage, compromise of blood brain barrier function, buildup of toxic proteins including tau and beta amyloid (Aβ), association with and capacity to "manufacture" Aβ-mCRP-hybrid plaques, and, greater susceptibility to neurodegeneration and dementia. Recently, several studies linked chronic CRP/mCRP systemic expression in autoimmune disease with increased risk of dementia and the mechanisms through which this occurs are investigated here. The neurovascular unit mediates correct intramural periarterial drainage, evidence is provided here that suggests a critical impact of mCRP on neurovascular elements that could suggest its participation in the earliest stages of dysfunction and conclude that further investigation is warranted. We discuss future therapeutic options aimed at inhibiting the pCRP-LPC mediated dissociation associated with brain pathology, for example, compound 1,6-bis-PC, injected intravenously, prevented mCRP deposition and associated damage, after temporary left anterior descending artery ligation and myocardial infarction in a rat model.

P2Y4 nucleotide receptor: A novel target for anti-inflammatory therapies to improve myocardial infarction outcome

Human P2Y4 is a UTP receptor, while in mice it is activated by both ATP and UTP. P2Y4 knockout (KO) in mice protects against myocardial infarction and leads to increased adiponectin secretion by adipocytes and lower cardiac inflammation under ischemia. The main objective is to investigate the anti-inflammatory mechanisms of cardioprotection in P2Y4 KO ischemic mice, and explore the relevance of these data in humans. We performed left anterior descending artery ligation on wild-type and P2Y4 KO mice to investigate the inflammatory state of their pericardial adipose tissue under ischemia. In parallel, in a population study comprising patients with coronary artery disease (CAD) and age-matched control individuals, we analyzed P2RY4 gene mutations and their potential association with CAD severity and fasting plasma parameters. We demonstrated that P2Y4 KO mice displayed adipocyte beiging with increased PD-L1 expression and a higher number of regulatory leukocytes in their pericardial adipose tissue after left anterior descending artery ligation, compared to wild-type mice. Interestingly, the reduction of T cell infiltration and cardiac fibrosis observed in P2Y4 KO heart was lost after injection of anti-PD-L1 blocking antibody in ischemic mice. We also identified a N178T loss-of-function mutation of the human P2Y4 receptor found less frequently in CAD patients than in control individuals. In coronary patients, carriers of the N178T variant had significantly reduced Duke jeopardy and Gensini cardiac severity scores, as well as lower resting heart rates and reduced plasma levels of N-terminal pro-brain natriuretic peptide and fasting glucose. Accordingly, P2Y4 KO mice had significantly improved glucose tolerance and insulin sensitivity compared with their wild-type littermate controls. The present study defines P2Y4 receptor as a negative regulator of PD-L1 and adiponectin, and as a potential target for anti-inflammatory therapies. The combined effect of P2Y4 loss on adipocyte beiging and regulatory leukocyte increase highlights this nucleotide receptor as an important player in post-ischemic cardiac response. We also identified a frequent loss-of-function P2Y4 variant associated with less severe coronary artery atherosclerosis and lower fasting plasma glucose in CAD patients. P2Y4 antagonists could thus have therapeutic applications in the treatment of myocardial infarction and type 2 diabetes.

BS-452758-2 RESCUE OF ISCHEMIC DILATED CARDIOMYOPATHY IN CANINES

Ischemic cardiomyopathy and resultant heart failure (HF) are significant causes of morbidity and mortality worldwide. Mainstay therapeutic options are limited to the blockade of neurohormonal stress pathways. An unmet need in HF therapy is the development of targeted myocardium-specific therapies. Cardiac bridging integrator 1 (cBIN1), a membrane scaffolding protein in transverse-tubule microdomains, organizes the calcium handling apparatus proteins in cardiomyocytes. cBIN1 is transcriptionally reduced in failing hearts, impairing calcium transients and systolic and diastolic function. This study explored cBIN1 as a gene therapy-based rescue of ischemic cardiomyopathy. To investigate whether cBIN1 gene therapy rescues failing myocardium in a preclinical canine model of chronic ischemic HF. Nine healthy adult mongrel dogs (30±3 kg) underwent a lateral thoracotomy followed by left anterior descending artery ligation to induce myocardial infarctions. Animals developed progressive dilated cardiomyopathy and chronic ischemic HF over 10 – 16 weeks. When their left ventricular ejection fraction (LVEF) decreased below 40%, animals received a single intramyocardial injection of either adeno-associated virus serotype 9 (AAV9)-cBIN1 gene (n=6) or AAV9-green fluorescent protein (GFP) (Control, n=3) in the LV. Weekly echocardiography, laboratory testing and daily clinical examinations were performed up to 7 weeks post-therapy. From therapy to post-injection week 5, LV function in the GFP-treated cohort continued to decline. By week 5, all control animals developed progressive dilated cardiomyopathy and had to be euthanized due to worsening prognostic factors. In contrast, the cBIN1-treated cohort never developed HF symptoms, and LVEF statistically improved by 4% gain (Figure, p=0.003 – reclassifying the animals from HF with reduced ejection fraction to HF with mildly reduced ejection fraction), whereas the control cohort lost an additional 7% in LV function. In cBIN1-treated animals, there was no significant further LV dilation and positive remodeling to smaller dimensions. Cardiac biomarkers of HF continued to increase in the control cohort and decreased in the cBIN1-treated cohort. In a canine model of chronic ischemic HF, cBIN1 gene therapy significantly rescued and improved LV function. This work suggests that recovery of transverse-tubule microdomains and normalizing excitation-contraction coupling by cBIN1 gene therapy can restore contractility in ischemic HF.

Treatment for Myocardial Infarction: In Vivo Evaluation of Curcumin-Loaded PEGylated-GQD Nanoparticles.

Curcumin (Cur) has been suggested as a complementary treatment for cardiovascular diseases. Its efficiency, however, is modest due to poor biocompatibility. This study examined the effects of curcumin loaded on polyethylene glycol-graphene quantum dots (Cur-PEG-GQDs) on hemodynamic and cardiac function in rats with myocardial infarction (MI). The study groups included control, MI, MI+Cur-3, MI + Cur-7, MI + Cur-15, MI + PEG-GQDs-5, MI + PEG-GQDs-10, MI + Cur-PEG-GQDs-5, and MI + Cur-PEG-GQDs-10. MI was established by left anterior descending artery ligation. Two weeks after intraperitoneal administration of vehicle, Cur, PEG-GQDs, and Cur-PEG-GQDs, blood pressure and heart contractility indices were measured. Triphenyl tetrazolium chloride, colorimetry, and clinical laboratory methods were used to measure the infarct size, the oxidant and antioxidant content, and the kidney and liver function parameters, respectively. In the MI animals, Cur-7, PEG-GQDs-10, Cur-PEG-GQDs-5, and Cur-PEG-GQDs-10 recovered systolic blood pressure, diastolic blood pressure, left ventricular systolic pressure, and ±dp/dt max disturbances and reduced myocardial infarct size, fibrosis, and left ventricular end-diastolic pressure. Curcumin lowered antioxidant markers and elevated 1 oxidant marker in the heart in a dose-dependent manner. Although Cur-PEG-GQDs-5 and Cur-PEG-GQDs-10 reduced curcumin's oxidative stress effects, the superoxide dismutase, glutathione peroxidase, and total antioxidant capacity levels were significantly lower in Cur-PEG-GQDs-5 and Cur-PEG-GQDs-10 groups compared with the MI group. Malondialdehyde levels were lower in Cur-PEG-GQDs-5 and -10 groups compared with the Cur-3, Cur-7, and Cur-15 groups. The glutathione/glutathione disulfide ratio improved in the groups treated by Cur-7, PEG-GQDs-10, Cur-PEG-GQDs-5, and Cur-PEG-GQDs-10. The findings indicated that Cur-PEG-GQDs mitigated MI-induced cardiac dysfunction. However, because of the increase in oxidative stress in the heart, nonclassic mechanisms may be involved in the beneficial effect of Cur-PEG-GQDs on MI-induced cardiac dysfunction.

Fucoxanthin alleviated myocardial ischemia and reperfusion injury through inhibition of ferroptosis via the NRF2 signaling pathway.

Background: Myocardial ischemia and reperfusion injury (MIRI) is a severe complication of revascularization therapy in patients with myocardial infarction. Therefore, there is an urgent requirement to find more therapeutic solutions for MIRI. Recently, ferroptosis, which is characterized by lipid peroxidation, was considered a critical contributor to MIRI. Fucoxanthin (FX), a natural antioxidant carotenoid, which is abundant in brown seaweed, exerts protective effects under various pathological conditions. However, whether FX alleviates MIRI is unclear. This study aims to clarify the effects of FX on MIRI. Methods: Mice with left anterior descending artery ligation and reperfusion were used as in vivo models. Neonatal rat cardiomyocytes (NRCs) induced with hypoxia and reperfusion were used as in vitro models. TTC-Evans blue staining was performed to validate the infarction size. Transmission electron microscopy was employed to detect mitochondrial injury in cardiomyocytes. In addition, 4 weeks after MIRI, echocardiography was performed to measure cardiac function; fluorescent probes and western blots were used to detect ferroptosis. Results: TTC-Evans blue staining showed that FX reduced the infarction size induced by MIRI. Transmission electron microscopy showed that FX ameliorated the MIRI-induced myofibril loss and mitochondrion shrinkage. Furthermore, FX improved LVEF and LVFS and inhibited myocardial hypertrophy and fibrosis after 4 weeks in mice with MIRI. In the in vitro study, calcein AM/PI staining and TUNEL staining showed that FX reduced cell death caused by hypoxia and reperfusion treatment. DCFH-DA and MitoSOX probes indicated that FX inhibited cellular and mitochondrial reactive oxygen species (ROS). Moreover, C11-BODIPY 581/591 staining, ferro-orange staining, MDA assay, Fe2+ assay, 4-hydroxynonenal enzyme-linked immunosorbent assay, and western blot were performed and the results revealed that FX ameliorated ferroptosis in vitro and in vivo, as indicated by inhibiting lipid ROS and Fe2+ release, as well as by modulating ferroptosis hallmark FTH, TFRC, and GPX4 expression. Additionally, the protective effects of FX were eliminated by the NRF2 inhibitor brusatol, as observed from western blotting, C11-BODIPY 581/591 staining, and calcein AM/PI staining, indicating that FX exerted cardio-protective effects on MIRI through the NRF2 pathway. Conclusion: Our study showed that FX alleviated MIRI through the inhibition of ferroptosis via the NRF2 signaling pathway.

Central role of PD-L1 in cardioprotection resulting from P2Y4 nucleotide receptor loss.

A better understanding of the immune function of pericardial adipose tissue is essential to adapt treatments after myocardial infarction. We showed previously that inactivation of mouse P2Y4 nucleotide receptor induces adiponectin overexpression and protection against myocardial infarction. We investigated here the inflammatory state of pericardial adipose tissue in ischemic P2Y4-deficient mice. We demonstrated that P2Y4-deficient mice displayed adipocyte beiging with increased PD-L1 expression and a higher number of regulatory leukocytes in their pericardial adipose tissue after left anterior descending artery ligation, compared to wild type mice. Effectively, a higher level of anti-inflammatory M2c macrophages and regulatory T cells was observed in pericardial adipose tissue of P2Y4 KO mice and correlated with reduced post-ischemic expansion of fat-associated lymphoid clusters. Interestingly, the anti-inflammatory effects observed in P2Y4 KO mice, were no more observed in P2Y4/adiponectin double KO ischemic mice. Finally, the reduction of T cell infiltration and cardiac fibrosis observed in P2Y4-deficient heart was lost after injection of anti-PD-L1 blocking antibody in ischemic mice. The present study defines P2Y4 as a regulator of PD-L1 and adiponectin, and as a potential target for anti-inflammatory therapies to improve myocardial infarction outcome. The combined effect of P2Y4 loss on adipocyte beiging and regulatory leukocyte increase highlights this nucleotide receptor as an important player in post-ischemic cardiac response.

Sacubitril Valsartan Enhances Cardiac Function and Alleviates Myocardial Infarction in Rats through a SUV39H1/SPP1 Axis.

Sacubitril valsartan (lcz696) has been demonstrated as a substitute for angiotensin-converting enzyme inhibitors and angiotensin receptor blockers for the treatment of heart failure. This research is aimed at examining the effects of lcz696 and its target molecules on myocardial infarction (MI). A rat model of MI was induced by left anterior descending artery ligation and treated with lcz696. Lcz696 treatment significantly reduced cardiac injury and heart failure, restored the left ventricular fractional shortening and ejection fraction, and reduced oxidative stress and inflammatory responses in rat myocardium. By analyzing the heart failure-related GSE47495 dataset and performing gene ontology (GO) functional enrichment analysis, we obtained histone lysine methyltransferase SUV39H1 and secreted phosphoprotein 1 (SPP1) as two molecules implicated in the oxidative stress and inflammation processes. An elevation of SUV39H1 whereas a decline of SPP1 were detected in cardiac tissues after lcz696 treatment. Enrichments of SUV39H1 and H3K9me3 at the SPP1 promoter were identified by chromatin immunoprecipitation assay. SUV39H1 catalyzed H3K9me3 modification to suppress the expression of SPP1. Preconditioning of SUV39H1 silencing blocked the protective roles of lcz696, but SPP1 silencing alleviated the myocardial injury. In conclusion, this study demonstrates that lcz696 enhances cardiac function and alleviates MI in rats through a SUV39H1/SPP1 axis.

Dynamic regulation of HIF-1 signaling in the rhesus monkey heart after ischemic injury

BackgroundHypoxia inducible factor-1 (HIF-1) plays a key role in modulating post-infarct healing after myocardial ischemic injury through transcriptional regulation of hundreds of genes involved in diverse cardiac remodeling processes. However, the dynamic changes in HIF-1 target gene expression in the ischemic heart after myocardial infarction (MI) have not been well characterized.MethodsWe employed a rhesus monkey model of MI induced by left anterior descending artery ligation and examined the expression pattern of HIF-1 target genes in the ischemic heart at 1, 7, and 28 days after injury by bulk RNA-sequencing analysis.ResultsMyocardial transcriptomic analysis demonstrated a temporal-specific regulation of genes associated with the inflammatory response, cell proliferation, fibrosis and mitochondrial metabolism during the pathological progression of MI. HIF-1 target genes involved in processes related to glycolysis, angiogenesis, and extracellular matrix (ECM) remodeling also exhibited distinct expression patterns during MI progression. Copper concentrations were gradually decreased in the heart after ischemic injury, which was positively correlated with the expression of HIF-1-mediated angiogenic and glycolytic genes but negatively correlated with the expression of HIF-1-mediated ECM remodeling genes. Moreover, genes related to intracellular copper trafficking and storage were suppressed along with the loss of myocardial copper in the ischemic heart.ConclusionsThis study demonstrated a dynamic, functional-specific regulation of HIF-1 target gene expression during the progression of MI. The fine-tuning of HIF-1 signaling in the ischemic heart may be relate to the alteration in myocardial copper homeostasis. These findings provide transcriptomic insights into the distinct roles of HIF-1 signaling in the heart after ischemic injury, which will help determine the beneficial cutoff point for HIF-1 targeted therapy in ischemic heart diseases.

Activation of the sigma-1 receptor exerts cardioprotection in a rodent model of chronic heart failure by stimulation of angiogenesis

BackgroundAngiogenesis plays a critical role on post-infarction heart failure (PIHF), the presence of which facilitates additional blood supply to maintain the survival of residual cardiomyocytes. The sigma-1 receptor (S1R) has been substantiated to stimulate angiogenesis, with the effect on a model of PIHF remaining unknown.AimsThis study aims to investigate the effects of S1R on PIHF and the underlying mechanisms involved.MethodsRats were implemented left anterior descending artery ligation followed by rearing for 6 weeks to induce a phenotype of heart failure. Daily intraperitoneal injection of S1R agonist or antagonist for 5 weeks was applied from 2nd week after surgery. The effects exerted by S1R were detected by echocardiography, hemodynamic testing, western blot, Sirius red dyeing, ELISA, immunohistochemistry and fluorescence. We also cultured HUVECs to verify the mechanisms in vitro.ResultsStimulation of S1R significantly ameliorated the cardiac function resulted from PIHF, in addition to the observation of reduced fibrosis in the peri-infarct region and the apoptosis of residual cardiomyocytes, which were associated with augmentation of microvascular density in peri-infarct region through activation of the JAK2/STAT3 pathway. We also indicated that suppression of JAK2/STAT3 pathway by specific inhibitor in vitro reversed the pro-angiogenic effects of S1R on HUVECs, which further confirmed that angiogenesis, responsible for PIHF amelioration, by S1R stimulation was in a JAK2/STAT3 pathway-dependent manner.ConclusionS1R stimulation improved PIHF-induced cardiac dysfunction and ventricular remodeling through promoting angiogenesis by activating the JAK2/STAT3 pathway.