Megakaryocytic Leukemia 1 Bridges Epigenetic Activation of NADPH Oxidase in Macrophages to Cardiac Ischemia-Reperfusion Injury

Mitigation of Injury from Myocardial Infarction by Pentamidine, an Inhibitor of the Acetyltransferase Tip60

PURPOSE

There is an urgent unmet need for new pharmacologic approaches that promote re-muscularization and repair following myocardial infarction (MI). We previously reported that genetic depletion of the acetyltransferase Tip60 after MI in a mouse model activates the CM cell-cycle, reduces scarring, and restores cardiac function, and that these beneficial effects are mimicked by the Tip60-selective inhibitor TH1834. Here, we investigated whether the FDA-approved anti-microbial agent pentamidine, a Tip60 inhibitor from which TH1834 is derived, also protects from the damaging effects of MI.

METHODS

Adult (10-14 weeks old) C57Bl/6 mice were subjected to permanent left coronary artery ligation to induce MI. Subsequently, echocardiography, electrocardiography, cardiac staining, and molecular analyses were performed to monitor the effects of treatment with pentamidine on cardiac injury and function.

RESULTS

We report that transient systemic administration of pentamidine on days 3-16 post-MI at a daily dose of 3 mg/kg efficiently improved cardiac function for up to ten months. This was accompanied by improved survival, diminished scarring, and increased activation of cell-cycle markers in CMs located in the infarct border zone in the absence of hypertrophy. Histological assessments suggested that post-MI treatment with pentamidine reduced site-specific acetylation of the minor histone variant H2A.Z at lysines K4 and K7 in CMs, indicative of the dedifferentiation process which must occur prior to CM proliferation. Treating mice with pentamidine post-MI produced no prominent electrophysiological changes.

CONCLUSIONS

These findings support the translational potential of pentamidine for treatment of MI, and provide evidence that functional improvement is mediated, in part, by CM renewal due to inhibition of the acetyltransferase activity of Tip60.

Metabolic Adaptations and Therapies in Cardiac Hypoxia: Mechanisms and Clinical Implications/ Potential Strategies

Cardiac hypoxia triggers a cascade of responses and functional changes in myocardial and non-myocardial cells, profoundly affecting cellular metabolism, oxygen-sensing mechanisms, and immune responses. Myocardial cells, being the primary cell type in cardiac tissue, undergo significant alterations in energy metabolism, including glycolysis, fatty acid metabolism, ketone body utilization, and branched-chain amino acid metabolism, to maintain cardiac function under hypoxic conditions. Non-myocardial cells, such as fibroblasts, endothelial cells, and immune cells, although fewer in number, play crucial roles in regulating cardiac homeostasis, maintaining structural integrity, and responding to injury. This review discusses the metabolic reprogramming of immune cells, particularly macrophages, during ischemia-reperfusion injury and explores various therapeutic strategies that modulate these metabolic pathways to protect the heart during hypoxia. Understanding these interactions provides valuable insights and potential therapeutic targets for heart disease treatment.

Magea13 attenuates myocardial injury in acute myocardial infarction by inhibiting the cAMP-PKA signaling pathway

OBJECT

Acute myocardial infarction (AMI) is a serious cardiovascular disease for which there are still no effective therapeutic options available, and melanoma-associated antigen-A13 (Magea13), a member of the MAGE superfamily, has an unknown role in AMI. This study aims to investigate the potential role and molecular mechanisms of Magea13 in myocardial injury associated with AMI through in vivo and in vitro experiments.

METHODS

Firstly, differentially expressed genes (DEGs) and signaling pathways were screened by RNA sequencing. Cardiac-specific Magea13 overexpression was achieved with the adeno-associated virus type 9 serotype system. Subsequently, these rats underwent left anterior descending coronary artery (LAD) ligation, followed by histopathological examination, biochemical assay, and Western blot analysis to evaluate the efficacy and feasibility of Magea13 in AMI. Meanwhile, the Magea13-overexpressing rat cardiomyocyte cell line (H9c2) was also subjected to hypoxia-glucose deficiency/reperfusion to mimic AMI injury to further validate its effects in vitro.

RESULTS

The cardiomyocyte-specific overexpression of Magea13 was observed to attenuate myocardial injury in rats with acute myocardial infarction. Furthermore, Magea13 overexpression was demonstrated to attenuate OGD/R-induced H9c2 cell injury. Mechanistic studies have suggested that the protective effect of Magea13 may be mediated through the cAMP-PKA pathway.

CONCLUSION

Magea13 has been demonstrated to offer protection against AMI myocardial injury through the cAMP-PKA signaling pathway and is therefore a promising therapeutic and predictive target for AMI myocardial injury.

Activation of megakaryocytic leukemia 1 in endothelial cells contributes to diabetic retinopathy in mice

AIMS

Diabetic retinopathy (DR) represents one of the most devastating sequences in patients with diabetes. Endothelial dysfunction is a key pathological feature of and contributing factor to DR. In the present study we investigated the role of megakaryocytic leukemia 1 (MKL1) in DR pathogenesis.

METHODS AND MATERIALS

DR was induced in mice by feeding with a high-fat diet (HFD). The Mkl1-Rosa26-KI mice were crossed to the Cdh5-CreERT2 mice to generate endothelial-specific MKL1 knock-in mice (MKL1EC-KI).

KEY FINDINGS

In cultured human primary retinal endothelial cells exposure to high glucose promoted nuclear translocation of MKL1 without altering its mRNA or protein expression. MKL1 knockdown ameliorated whereas MKL1 over-expression exacerbated high glucose induced impairment of endothelial barrier function. Compared to wild type littermates, MKL1EC-KI mice fed on HFD displayed worsened insulin resistance and accelerated DR pathogenesis. Consistently, administration of an MKL1 inhibitor CCG-1423 protected the mice from HFD feeding induced metabolic disorders and DR pathogenesis.

SIGNIFICANCE

Our data demonstrate that MKL1 may contribute to diabetic retinopathy by regulating endothelial behavior. Targeting MKL1 with small-molecule inhibitors can be considered as a therapeutic solution for the treatment of diabetic retinopathy.

MG149 suppresses anaplastic thyroid cancer progression by inhibition of lysine acetyltransferase KAT5-mediated c-Myc acetylation

BACKGROUND

Anaplastic thyroid cancer (ATC) is a highly lethal form of thyroid cancer. lysine acetyltransferase 5 (KAT5) has been found to promote ATC development via c-Myc stabilization by previous study. We thus designed experiments to confirm the anti-tumor effect of a KAT5 inhibitor (MG149) in ATC.

METHODS

Western blotting assessed the level of KAT5, c-Myc, and epithelial-mesenchymal transition (EMT)-related proteins in ATC cells and xenograft tumor tissues. Cell counting kit-8, flow cytometry, wound healing, and transwell assays revealed the effect of MG149 on cell proliferation, apoptosis, migration, and invasion in ATC cell lines. Immunofluorescence detected the level of E-cadherin and N-cadherin in ATC cell lines. The effect of MG149 on KAT5-mediated c-Myc stabilization was detected using co-immunoprecipitation assay. Tumor volume and tumor weight in ATC xenograft models were evaluated. H&E staining showed the effect of MG149 on lung metastasis in vivo. We further investigated whether MG149 can enhance the sensitivity of ATC to cisplatin (CDDP).

RESULTS

MG149 inhibited cell proliferation and increased the apoptosis of cells. MG149 suppressed the migratory and invasive ability of ATC cells. The EMT in CAL-62 and 8505C cells was significantly inhibited by MG149. MG149 suppressed the KAT5-mediated c-Myc acetylation. MG149 inhibited tumor growth and lung metastasis in vivo. Additionally, MG149 potentiated the sensitivity to CDDP in ATC cells in vitro and in vivo.

CONCLUSION

MG149 suppresses ATC progression and metastasis by inhibiting the acetylation of c-Myc mediated by KAT5.

The Emergence of Nanotechnology in the Prognosis and Treatment of Myocardial Infarctions

Myocardial infarction (MI), commonly known as a heart attack, is a critical cardiovascular condition associated with high morbidity and mortality rates worldwide. Despite significant advancements in traditional treatment modalities, there remains a need for innovative approaches to improve the prognosis and treatment outcomes of MI. The emergence of nanotechnology has provided a promising avenue for revolutionizing the management of this life-threatening condition. This manuscript aims to explore the role of nanotechnology in the prognosis and treatment of myocardial infarctions. Nanotechnology offers unique advantages in the field of cardiovascular medicine, including targeted drug delivery, precise imaging and diagnosis, regenerative medicine approaches, biosensors and monitoring, and the integration of therapy and diagnostics (theragnostic). One of the key advantages of nanotechnology is the ability to deliver therapeutic agents directly to the affected site. Nanoparticles can be engineered to carry drugs specifically to damaged heart tissue, enhancing their efficacy while minimizing off-target effects. Additionally, nanoparticles can serve as contrast agents, facilitating high-resolution imaging and accurate diagnosis of infarcted heart tissue. Furthermore, nanotechnology-based regenerative approaches show promise in promoting tissue healing and regeneration after MI. Nanomaterials can provide scaffolding structures or release growth factors to stimulate the growth of new blood vessels and support tissue repair. This regenerative potential holds significant implications for restoring cardiac function and minimizing long-term complications. Nanotechnology also enables real-time monitoring of critical parameters within the heart, such as oxygen levels, pH, and electrical activity, through the utilization of nanoscale devices and sensors. This capability allows for the early detection of complications and facilitates timely interventions. Moreover, the integration of therapy and diagnostics through nanotechnology- based platforms, known as theragnostic, holds tremendous potential. Nanoparticles can simultaneously deliver therapeutic agents while providing imaging capabilities, enabling personalized treatment strategies tailored to individual patients. This manuscript will review the recent advancements, clinical trials, and patents in nanotechnology for the prognosis and treatment of myocardial infarctions. By leveraging nanotechnology's unique properties and applications, researchers and clinicians can develop innovative therapeutic approaches that enhance patient outcomes, improve prognosis, and ultimately revolutionize the management of myocardial infarctions.

Chromatin accessibility: biological functions, molecular mechanisms and therapeutic application

The dynamic regulation of chromatin accessibility is one of the prominent characteristics of eukaryotic genome. The inaccessible regions are mainly located in heterochromatin, which is multilevel compressed and access restricted. The remaining accessible loci are generally located in the euchromatin, which have less nucleosome occupancy and higher regulatory activity. The opening of chromatin is the most important prerequisite for DNA transcription, replication, and damage repair, which is regulated by genetic, epigenetic, environmental, and other factors, playing a vital role in multiple biological progresses. Currently, based on the susceptibility difference of occupied or free DNA to enzymatic cleavage, solubility, methylation, and transposition, there are many methods to detect chromatin accessibility both in bulk and single-cell level. Through combining with high-throughput sequencing, the genome-wide chromatin accessibility landscape of many tissues and cells types also have been constructed. The chromatin accessibility feature is distinct in different tissues and biological states. Research on the regulation network of chromatin accessibility is crucial for uncovering the secret of various biological processes. In this review, we comprehensively introduced the major functions and mechanisms of chromatin accessibility variation in different physiological and pathological processes, meanwhile, the targeted therapies based on chromatin dynamics regulation are also summarized.

Kirenol Ameliorates Myocardial Ischemia-Reperfusion Injury by Promoting Mitochondrial Function and Inhibiting Inflammasome Activation

PURPOSE

Macrophage-mediated inflammation plays a crucial role in the pathophysiological process of myocardial ischemia/reperfusion (I/R) injury. Recent studies have highlighted the importance of mitochondrial function and inflammasome activation in the inflammatory process. Kirenol, a well-known natural compound, has been shown to regulate inflammation in various diseases. This study investigated whether Kirenol could exert anti-inflammatory effects on macrophages during myocardial I/R injury.

METHODS

Mouse myocardial I/R models were established by 45 min of ischemia followed by 24 h of reperfusion. Saline or Kirenol treatment was administered. In vivo assessments included the evaluation of cardiac function, infarcted area, and immune cell infiltration. Subsequently, bone marrow-derived macrophages (BMDMs) were isolated, and mitochondrial function and pyroptosis were assessed. Furthermore, the study compared the cardioprotective effects of Kirenol with a specific NOX1/NOX4 inhibitor, GKT137831.

RESULTS

Kirenol gavage improved cardiac function, decreased infarct area, and alleviated inflammatory infiltration in mice subjected to myocardial I/R injury. Mechanistically, Kirenol inhibited NOX1 and NOX4 and enhanced mitochondrial function, ultimately attenuating the pyroptosis of macrophages. The therapeutic effects of Kirenol and GKT137831 were not significantly different.

CONCLUSION

This study demonstrates that Kirenol mitigates myocardial I/R injury by inhibiting NOX1 and NOX4, restoring mitochondrial function, and ameliorating macrophage pyroptosis.

Advances in macrophage metabolic reprogramming in myocardial ischemia-reperfusion

Acute myocardial infarction (AMI) is the leading cause of death worldwide, and reperfusion therapy is a critical therapeutic approach to reduce myocardial ischemic injury and minimize infarct size. However, ischemia/reperfusion (I/R) itself also causes myocardial injury, and inflammation is an essential mechanism by which it leads to myocardial injury, with macrophages as crucial immune cells in this process. Macrophages are innate immune cells that maintain tissue homeostasis, host defence during pathogen infection, and repair during tissue injury. During the acute phase of I/R, M1-type macrophages generate a pro-inflammatory milieu, clear necrotic myocardial tissue, and further recruit mononuclear (CCR2+) macrophages. Over time, the reparative (M2 type) macrophages gradually became dominant. In recent years, metabolic studies have shown a clear correlation between the metabolic profile of macrophages and their phenotype and function. M1-type macrophages are mainly characterized by glycolytic energy supply, and their tricarboxylic acid (TCA) cycle and mitochondrial oxidative phosphorylation (OXPHOS) processes are impaired. In contrast, M2 macrophages rely primarily on OXPHOS for energy. Changing the metabolic profile of macrophages can alter the macrophage phenotype. Altered energy pathways are also present in macrophages during I/R, and intervention in this process contributes to earlier and greater M2 macrophage infiltration, which may be a potential target for the treatment of myocardial I/R injury. Therefore, this paper mainly reviews the characteristics of macrophage energy metabolism alteration and phenotypic transition during I/R and its mechanism of mediating myocardial injury to provide a basis for further research in this field.

Macrophage MKL1 contributes to cardiac fibrosis in a mouse model of myocardial infarction

AIMS

Cardiac fibrosis is characterized by aberrant collagen deposition in the heart. Macrophage polarization or infiltration is the main reason to accelerate the collagen deposition. We attempted to investigate the involvement of MKL1 in macrophages during the development of cardiac fibrosis.

MATERIALS AND METHODS

Cardiac fibrosis is induced by myocardial infarction (MI). The MKL1f/f mice were crossed to the Lyz2-cre mice to generate macrophage conditional MKL1 knockout mice (MKL1ΔMφ). In addition, macrophage conditional MKL1 overexpression mice (MKL1Mϕ-OE) were constructed by crossing Lyz2-cre mice to MKL1ΔN200-Rosa26 mice.

KEY FINDINGS

MKL1 expression was significantly increased in macrophages of both ischemic cardiomyopathy (ICM) patients and mice induced to develop myocardial infarction. Deletion of MKL1 in macrophages improved the heart function after MI-induced cardiac fibrosis. Consistently, MKL1Mϕ-OE mice displayed more severe cardiac fibrosis and worsened heart function than the control mice after MI. Moreover, administration of a small-molecule MKL1 inhibitor CCG-1423 also decreased the collagen deposition after MI.

SIGNIFICANCE

Our data demonstrate that MKL1 in macrophages contributes to cardiac fibrosis pathogenesis and reinforce the notion that targeting MKL1 may yield effective antifibrotic therapeutics in the heart.

EPHB2 Knockdown Mitigated Myocardial Infarction by Inhibiting MAPK Signaling

Myocardial infarction (MI) is a common type of cardiovascular disease. The incidence of ventricular remodeling dysplasia and heart failure increases significantly after MI. The objective of this study is to investigate whether erythropoietin hepatocellular receptor B2 (EPHB2) can regulate myocardial injury after MI and explore its regulatory pathways. EPHB2 is significantly overexpressed in the heart tissues of MI mice. The downregulation of EPHB2 alleviates the cardiac function damage after MI. Knockdown EPHB2 alleviates MI-induced myocardial tissue inflammation and apoptosis, and myocardial fibrosis in mice. EPHB2 knockdown significantly inhibits the activation of mitogen activated kinase-like protein (MAPK) pathway in MI mice. Moreover, EPHB2 overexpression significantly promotes the phosphorylation of MAPK pathway-related protein, which can be reversed by MAPK-IN-1 (an MAPK inhibitor) treatment. In conclusion, silencing EPHB2 can mitigate MI-induced myocardial injury by inhibiting MAPK signaling in mice, suggesting that targeting EPHB2 can be a promising therapeutic target for MI-induced myocardial injury.

The Role of Antioxidants in the Therapy of Cardiovascular Diseases-A Literature Review

Antioxidants are endogenous and exogenous substances with the ability to inhibit oxidation processes by interacting with reactive oxygen species (ROS). ROS, in turn, are small, highly reactive substances capable of oxidizing a wide range of molecules in the human body, including nucleic acids, proteins, lipids, carbohydrates, and even small inorganic compounds. The overproduction of ROS leads to oxidative stress, which constitutes a significant factor contributing to the development of disease, not only markedly diminishing the quality of life but also representing the most common cause of death in developed countries, namely, cardiovascular disease (CVD). The aim of this review is to demonstrate the effect of selected antioxidants, such as coenzyme Q10 (CoQ10), flavonoids, carotenoids, and resveratrol, as well as to introduce new antioxidant therapies utilizing miRNA and nanoparticles, in reducing the incidence and progression of CVD. In addition, new antioxidant therapies in the context of the aforementioned diseases will be considered. This review emphasizes the pleiotropic effects and benefits stemming from the presence of the mentioned substances in the organism, leading to an overall reduction in cardiovascular risk, including coronary heart disease, dyslipidaemia, hypertension, atherosclerosis, and myocardial hypertrophy.

Heat stress induces IL-1β and IL-18 overproduction via ROS-activated NLRP3 inflammasome: implication in neuroinflammation in mice with heat stroke

Heat stroke induced cerebral damage via neuroinflammation. This study aimed to approach whether heat stress would promote NOD-like receptor protein 3 (NLRP3) inflammasome via reactive oxygen species (ROS). The mice were randomly divided into the sham group, the heat stress group, and the heat stress + TEMPOL (ROS scavenger) group. And the NLRP3 -/- mice were applied and divided into the NLRP3 -/-  + sham group and the NLRP3 -/-  + heat stress group. Furthermore, the BV2 cells were divided into four groups following the intervention measures: the heat stress + TEMPOL group, the heat stress + Z-VAD-FMK (caspase-1 inhibitor) group, the heat stress group, and the control group. ROS levels were examined. The expression levels of NLRP3, caspase-1, IL-1β, and IL-18 were detected by western blotting and double immunofluorescence. We found that heat stress attack induced excessive ROS in microglia and subsequently activated NLRP3 inflammasome in both mice and BV2 cells. When ROS scavenged, the expression level of NLRP3 was downregulated. Furthermore, with NLRP3 inflammasome activation, the expression levels of caspase-1, IL-1β, and IL-18 were increased. In NLRP3 -/- mice, however, the caspase-1, IL-1β, and IL-18 were significantly declined. Further experiments showed that pretreatment of caspase-1 inhibitor decreased the expression levels of IL-1β and IL-18. These results suggest that heat stress attack caused neuroinflammation via excessive ROS activating the NLRP3 inflammasome in microglia cells.

The m6A methylation enzyme METTL14 regulates myocardial ischemia/reperfusion injury through the Akt/mTOR signaling pathway

Herein, we investigated the role of the m6A methylation enzyme METTL14 in regulating myocardial ischemia/reperfusion injury (IR/I) through the Akt/mTOR signaling pathway and related biological mechanisms. Enzyme-linked immunosorbent assay (ELISA) and fluorescence quantitative polymerase chain reaction (qPCR) were performed to detect the m6A mRNA and METTL3, METTL14, WTAP, and KIAA1429 levels in a mouse myocardial IR/I model. An oxygen-glucose deprivation/reperfusion (OGD/R) model was constructed by transfecting neonatal rat cardiomyocytes (NRCM) with METTL14-knockdown lentivirus. METTL14, Bax, and cleaved-caspase3 mRNA expression levels were detected using fluorescence qPCR. Apoptosis was detected using TUNEL staining. After the IR/I surgery following the adeno-associated virus injection, the METTL14 mRNA and apoptosis-related BAX/BCL2 protein expression was detected using fluorescence qPCR and western blotting, respectively. Degree of cell necrosis was detected using an LDH assay. The oxidative stress response of the myocardial tissue was detected, and IL-6 and IL-1β serum levels were detected using ELISAs. The mice injected with METTL14-knockdown AAV9 adeno-associated virus underwent IR/I surgery after the injection of an Akt/mTOR pathway inhibitor (MK2206) into the myocardial layer. Elevated mRNA m6A modification and m6A methyltransferase METTL14 levels were observed in the IR/I-injured mouse heart tissues. METTL14 knockdown significantly inhibited the OGD/R- and IR/I-induced apoptosis and necrosis in cardiac myocytes, inhibited IR/I-induced oxidative stress and inflammatory factor secretion, and activated the Akt/ mTOR pathway in vitro and in vivo. Akt/mTOR pathway inhibition significantly attenuated the alleviating effect of METTL14 knockdown on myocardial IR/I injury-induced apoptosis. Knocking down m6A methylase METTL14 inhibits IR/I-induced myocardial apoptosis and necrosis, inhibits myocardial oxidative stress and secretion of inflammatory cytokines, and activates the Akt/mTOR signaling pathway. Hence, METTL14 regulated myocardial apoptosis and necrosis in mice with IR/I through the Akt/mTOR signaling pathway.

KAT8 compound inhibition inhibits the initial steps of PINK1-dependant mitophagy

It has recently been shown that KAT8, a genome-wide association study candidate risk gene for Parkinson's Disease, is involved in PINK1/Parkin-dependant mitophagy. The KAT8 gene encodes a lysine acetyltransferase and represents the catalytically active subunit of the non-specific lethal epigenetic remodelling complex. In the current study, we show that contrary to KAT5 inhibition, dual inhibition of KAT5 and KAT8 via the MG149 compound inhibits the initial steps of the PINK1-dependant mitophagy process. More specifically, our study shows that following mitochondrial depolarisation induced by mitochondrial toxins, MG149 treatment inhibits PINK1-dependant mitophagy initiation by impairing PINK1 activation, and subsequent phosphorylation of Parkin and ubiquitin. While this inhibitory effect of MG149 on PINK1-activation is potent, MG149 treatment in the absence of mitochondrial toxins is sufficient to depolarise the mitochondrial membrane, recruit PINK1 and promote partial downstream recruitment of the autophagy receptor p62, leading to an increase in mitochondrial delivery to the lysosomes. Altogether, our study provides additional support for KAT8 as a regulator of mitophagy and autophagy processes.

Remimazolam attenuates myocardial ischemia-reperfusion injury by inhibiting the NF-ĸB pathway of macrophage inflammation

BACKGROUND

Inflammation is a major contributing factor in myocardial ischemia/reperfusion (I/R) injury, and targeting macrophage inflammation is an effective strategy for myocardial I/R therapy. Though remimazolam is approved for sedation, induction, and the maintenance of general anesthesia in cardiac surgery, its effect on cardiac function during the perioperative period has not been reported. Therefore, this research aimed to explore the impact of remimazolam on inflammation during myocardial ischemia/reperfusion (I/R) injury.

METHODS

An in vivo myocardial I/R mice model and an in vitro macrophage inflammation model were used to confirm remimazolam's cardiac protective effect. In vivo, we used echocardiography, hematoxylin and eosin (HE), and terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) staining to determine remimazolam's therapeutic effects on myocardial I/R injury and inflammation. In vitro, we employed enzyme-linked immunosorbent assay (ELISA), Western blot, Real-time Quantitative PCR (qPCR), flow cytometry, and immunofluorescence staining to assess inflammatory responses, especially remimazolam's effects on macrophage polarization after I/R. Furthermore, molecular docking was used to identify its potential binding targets on the inflammatory pathway to explore the mechanism of remimazolam.

RESULTS

Remimazolam exhibited significant anti-myocardial I/R injury activity by inhibiting macrophage-mediated inflammation to reduce myocardial infarction, enhancing cardiac function. In addition, macrophage depletion counteracted improved cardiac function by remimazolam treatment. Mechanistically, the activated NF-ĸB signaling pathway and phosphorylation of p50 and p65 were repressed for anti-inflammatory effect. Consistently, two binding sites on p50 and p65 were identified by molecular docking to affect their phosphorylation of the Ser, Arg, Asp, and His residues, thus regulating NF-κB pathway activity.

CONCLUSION

Our results unveil the therapeutic potential of remimazolam against myocardial I/R injury by inhibiting macrophages polarizing into the M1 type, alleviating inflammation.

Phosphatidic acid-enabled MKL1 contributes to liver regeneration: Translational implication in liver failure

Liver regeneration following injury aids the restoration of liver mass and the recovery of liver function. In the present study we investigated the contribution of megakaryocytic leukemia 1 (MKL1), a transcriptional modulator, to liver regeneration. We report that both MKL1 expression and its nuclear translocation correlated with hepatocyte proliferation in cell and animal models of liver regeneration and in liver failure patients. Mice with MKL1 deletion exhibited defective regenerative response in the liver. Transcriptomic analysis revealed that MKL1 interacted with E2F1 to program pro-regenerative transcription. MAPKAPK2 mediated phosphorylation primed MKL1 for its interaction with E2F1. Of interest, phospholipase d2 promoted MKL1 nuclear accumulation and liver regeneration by catalyzing production of phosphatidic acid (PA). PA administration stimulated hepatocyte proliferation and enhanced survival in a MKL1-dependent manner in a pre-clinical model of liver failure. Finally, PA levels was detected to be positively correlated with expression of pro-regenerative genes and inversely correlated with liver injury in liver failure patients. In conclusion, our data reveal a novel mechanism whereby MKL1 contributes to liver regeneration. Screening for small-molecule compounds boosting MKL1 activity may be considered as a reasonable approach to treat acute liver failure.

Macrophage Heterogeneity and Its Impact on Myocardial Ischemia-Reperfusion Injury: An Integrative Review

The coronary reperfusion following acute myocardial infarction can paradoxically trigger myocardial ischemia-reperfusion (IR) injury. This complex phenomenon involves the intricate interplay of different subsets of macrophages. These macrophages are crucial players in the post-infarction inflammatory response and subsequent myocardial anti-inflammatory repair. However, their diverse functions can lead to both beneficial and detrimental effects. On one hand, these macrophages play a crucial role in orchestrating the inflammatory response, aiding in the clearance of cellular debris and initiating tissue repair mechanisms. On the other hand, their excessive infiltration and activation can contribute to the perpetuation of the inflammatory cascade, leading to additional myocardial injury and adverse cardiac remodeling. Multiple mechanisms contribute to the IR injury mediated by macrophages, including oxidative stress, apoptosis, and autophagy. These processes further exacerbate the damage to the already vulnerable myocardial tissue. To address this delicate balance, therapeutic strategies aiming to target and modulate macrophage polarization and function are being explored. By fine-tuning the immune inflammatory response, such interventions hold promise in mitigating post-infarction myocardial injury and fostering a more favorable environment for myocardial healing and recovery. Through advancements in this area of research, potential anti-inflammatory interventions may pave the way for improved clinical outcomes and better management of patients after acute myocardial infarction.

Mettl13 protects against cardiac contractile dysfunction by negatively regulating C-Cbl-mediated ubiquitination of SERCA2a in ischemic heart failure

Ischemic heart failure (HF) remains a leading cause of morbidity and mortality. Maintaining homeostasis of cardiac function and preventing cardiac remodeling deterioration are critical to halting HF progression. Methyltransferase-like protein 13 (Mettl13) has been shown to regulate protein translation efficiency by acting as a protein lysine methyltransferase, but its role in cardiac pathology remains unexplored. This study aims to characterize the roles and mechanisms of Mettl13 in cardiac contractile function and HF. We found that Mettl13 was downregulated in the failing hearts of mice post-myocardial infarction (MI) and in a cellular model of oxidative stress. Cardiomyocyte-specific overexpression of Mettl13 mediated by AAV9-Mettl13 attenuated cardiac contractile dysfunction and fibrosis in response to MI, while silencing of Mettl13 impaired cardiac function in normal mice. Moreover, Mettl13 overexpression abrogated the reduction in cell shortening, Ca2+ transient amplitude and SERCA2a protein levels in the cardiomyocytes of adult mice with MI. Conversely, knockdown of Mettl13 impaired the contractility of cardiomyocytes, and decreased Ca2+ transient amplitude and SERCA2a protein expression in vivo and in vitro. Mechanistically, Mettl13 impaired the stability of c-Cbl by inducing lysine methylation of c-Cbl, which in turn inhibited ubiquitination-dependent degradation of SERCA2a. Furthermore, the inhibitory effects of knocking down Mettl13 on SERCA2a protein expression and Ca2+ transients were partially rescued by silencing c-Cbl in H2O2-treated cardiomyocytes. In conclusion, our study uncovers a novel mechanism that involves the Mettl13/c-Cbl/SERCA2a axis in regulating cardiac contractile function and remodeling, and identifies Mettl13 as a novel therapeutic target for ischemic HF.

The role of NADPH oxidase 1 in alcohol-induced oxidative stress injury of intestinal epithelial cells

Alcohol-mediated reactive oxygen species (ROS) play a vital role in intestinal barrier injury. However, the mechanism of ROS accumulation in enterocytes needs to be explored further. In our study, we found that chronic-binge ethanol-fed mice had increased levels of gut oxidative stress and high intestinal permeability. The transcription profiles of the colonic epithelial cells showed that the level of NADPH oxidase 1 (NOX1) was significantly elevated in alcohol-exposed mice compared with isocaloric-exposed mice. In vitro, NOX1 silencing alleviated ROS accumulation and the apoptosis of human colonic epithelial cells (NCM460), while NOX1 overexpression accelerated oxidative stress injury of NCM460 cells. Propionic acid was reduced in the gut of chronic-binge ethanol-fed mice, compared with isocaloric-fed mice, as observed through untargeted metabolomic analysis. Supplementation with propionate relieved ethanol-induced liver and intestinal barrier injuries and reduced the level of ROS accumulation and apoptosis of ethanol-induced colonic epithelial cells. Propionate alleviating NOX1 induced ROS injury of colonic epithelial cells, independent of G protein-coupled receptors. Propionate significantly inhibited histone deacetylase 2 (HDAC2) expressions both in ethanol-exposed colonic epithelial cells and TNF-α-treated NCM460. Chromatin immunoprecipitation (ChIP) assays showed that propionate suppressed the NOX1 expression by regulating histone acetylation in the gene promoter region. In conclusion, NOX1 induces oxidative stress injury of colonic epithelial cells in alcohol-related liver disease. Propionate, which can act as an endogenous HDAC2 inhibitor, can decrease levels of apoptosis of intestinal epithelial cells caused by oxidative stress.

Cardiac macrophages and emerging roles for their metabolism after myocardial infarction

Interest in cardioimmunology has reached new heights as the experimental cardiology field works to tap the unrealized potential of immunotherapy for clinical care. Within this space is the cardiac macrophage, a key modulator of cardiac function in health and disease. After a myocardial infarction, myeloid macrophages both protect and harm the heart. To varying degrees, such outcomes are a function of myeloid ontogeny and heterogeneity, as well as functional cellular plasticity. Diversity is further shaped by the extracellular milieu, which fluctuates considerably after coronary occlusion. Ischemic limitation of nutrients constrains the metabolic potential of immune cells, and accumulating evidence supports a paradigm whereby macrophage metabolism is coupled to divergent inflammatory consequences, although experimental evidence for this in the heart is just emerging. Herein we examine the heterogeneous cardiac macrophage response following ischemic injury, with a focus on integrating putative contributions of immunometabolism and implications for therapeutically relevant cardiac injury versus cardiac repair.

Communications between macrophages and cardiomyocytes

The heart is a muscular organ that pumps blood throughout the body and is one of the most vital organs in human body. While cardiomyocytes are essential for maintaining the normal function of the heart, a variety of cardiovascular diseases such as coronary artery occlusion, arrhythmia, and myocarditis can lead to cardiomyocyte death, resulting in deterioration of heart function. The adult mammalian heart is incapable of regenerating sufficient cardiomyocytes following cardiac injuries, eventually leading to heart failure and death. Cardiac macrophages are ubiquitously distributed in the healthy heart and accumulated at the site of injury. Macrophages play essential roles in regulating homeostasis and proliferation of cardiomyocyte, promoting electrical conduction, and removing dead cardiomyocytes and debris through direct and indirect cell-cell crosstalk. In this review, we summarize the latest insights into the role of macrophages in maintaining cardiac homeostasis and the macrophage-cardiomyocyte crosstalk in both healthy and injured scenarios. Video Abstract.

The phagocytic role of macrophage following myocardial infarction

Myocardial infarction (MI) is one of the cardiovascular diseases with high morbidity and mortality. MI causes large amounts of apoptotic and necrotic cells that need to be efficiently and instantly engulfed by macrophage to avoid second necrosis. Phagocytic macrophages can dampen or resolve inflammation to protect infarcted heart. Phagocytosis of macrophages is modulated by various factors including proteins, receptors, lncRNA and cytokines. A better understanding of mechanisms in phagocytosis will be beneficial to regulate macrophage phagocytosis capability towards a desired direction in cardioprotection after MI. In this review, we describe the phagocytosis effect of macrophages and summarize the latest reported signals regulating phagocytosis after MI, which will provide a new thinking about phagocytosis-dependent cardiac protection after MI.

Pharmacological inhibition of the acetyltransferase Tip60 mitigates myocardial infarction injury

Pharmacologic strategies that target factors with both pro-apoptotic and anti-proliferative functions in cardiomyocytes (CMs) may be useful for the treatment of ischemic heart disease. One such multifunctional candidate for drug targeting is the acetyltransferase Tip60, which is known to acetylate both histone and non-histone protein targets that have been shown in cancer cells to promote apoptosis and to initiate the DNA damage response, thereby limiting cellular expansion. Using a murine model, we recently published findings demonstrating that CM-specific disruption of the Kat5 gene encoding Tip60 markedly protects against the damaging effects of myocardial infarction (MI). In the experiments described here, in lieu of genetic targeting, we administered TH1834, an experimental drug designed to specifically inhibit the acetyltransferase domain of Tip60. We report that, similar to the effect of disrupting the Kat5 gene, daily systemic administration of TH1834 beginning 3 days after induction of MI and continuing for 2 weeks of a 4-week timeline resulted in improved systolic function, reduced apoptosis and scarring, and increased activation of the CM cell cycle, effects accompanied by reduced expression of genes that promote apoptosis and inhibit the cell cycle and reduced levels of CMs exhibiting phosphorylated Atm. These results support the possibility that drugs that inhibit the acetyltransferase activity of Tip60 may be useful agents for the treatment of ischemic heart disease.

Myocardin-related transcription factor A, regulated by serum response factor, contributes to diabetic cardiomyopathy in mice

AIMS

Diabetic cardiomyopathy is a significant contributor to the global pandemic of heart failure. In the present study we investigated the involvement of myocardin-related transcription factor A (MRTF-A), a transcriptional regulator, in this process.

MATERIALS AND METHODS

Diabetic cardiomyopathy was induced in mice by feeding with a high-fat diet (HFD) or streptozotocin (STZ) injection.

KEY FINDINGS

We report that MRTF-A was up-regulated in the hearts of mice with diabetic cardiomyopathy. MRTF-A expression was also up-regulated by treatment with palmitate in cultured cardiomyocytes in vitro. Mechanistically, serum response factor (SRF) bound to the MRTF-A gene promoter and activated MRTF-A transcription in response to pro-diabetic stimuli. Knockdown of SRF abrogated MRTF-A induction in cardiomyocytes treated with palmitate. When cardiomyocytes conditional MRTF-A knockout mice (MRTF-A CKO) and wild type (WT) mice were placed on an HFD to induce diabetic cardiomyopathy, it was found that the CKO mice and the WT mice displayed comparable metabolic parameters including body weight, blood insulin concentration, blood cholesterol concentration, and glucose tolerance. However, both systolic and diastolic cardiac function were exacerbated by MRTF-A deletion in the heart.

SIGNIFICANCE

These data suggest that MRTF-A up-regulation might serve as an important compensatory mechanism to safeguard the deterioration of cardiac function during diabetic cardiomyopathy.

MKL1 fuels ROS-induced proliferation of vascular smooth muscle cells by modulating FOXM1 transcription

Reactive oxygen species (ROS) promotes vascular injury and neointima formation in part by stimulating proliferation of vascular smooth muscle cells (VSMC). The underlying transcriptional mechanism, however, is not completely understood. Here we report that VSMC-specific deletion of MKL1 in mice suppressed neointima formation in a classic model of vascular injury. Likewise, pharmaceutical inhibition of MKL1 activity by CCG-1423 similarly mollified neointima formation in mice. Over-expression of a constitutively active MKL1 in vascular smooth muscle cells enhanced proliferation in a ROS-dependent manner. On the contrary, MKL1 depletion or inhibition attenuated VSMC proliferation. PCR array based screening identified forkhead box protein M1 (FOXM1) as a direct target for MKL1. MKL1 interacted with E2F1 to activate FOXM1 expression. Concordantly, FOXM1 depletion ameliorated MKL1-dependent VSMC proliferation. Of interest, ROS-induced MKL1 phosphorylation through MK2 was essential for its interaction with E2F1 and consequently FOXM1 trans-activation. Importantly, a positive correlation between FOXM1 expression and VSMC proliferation was identified in arterial specimens from patients with restenosis. Taken together, our data suggest that a redox-sensitive phosphorylation-switch of MKL1 activates FOXM1 transcription and mediates ROS fueled vascular smooth muscle proliferation. Targeting the MK-2/MKL1/FOXM1 axis may be considered as a reasonable approach for treatment of restenosis.

Reactive Oxygen Species Scavenging Nanomedicine for the Treatment of Ischemic Heart Disease

Ischemic heart disease (IHD) is the leading cause of disability and mortality worldwide. Reactive oxygen species (ROS) have been shown to play key roles in the progression of diabetes, hypertension, and hypercholesterolemia, which are independent risk factors that lead to atherosclerosis and the development of IHD. Engineered biomaterial-based nanomedicines are under extensive investigation and exploration, serving as smart and multifunctional nanocarriers for synergistic therapeutic effect. Capitalizing on cell/molecule-targeting drug delivery, nanomedicines present enhanced specificity and safety with favorable pharmacokinetics and pharmacodynamics. Herein, the roles of ROS in both IHD and its risk factors are discussed, highlighting cardiovascular medications that have antioxidant properties, and summarizing the advantages, properties, and recent achievements of nanomedicines that have ROS scavenging capacity for the treatment of diabetes, hypertension, hypercholesterolemia, atherosclerosis, ischemia/reperfusion, and myocardial infarction. Finally, the current challenges of nanomedicines for ROS-scavenging treatment of IHD and possible future directions are discussed from a clinical perspective.

L-Cysteine Alleviates Myenteric Neuron Injury Induced by Intestinal Ischemia/Reperfusion via Inhibitin the Macrophage NLRP3-IL-1β Pathway

Ischemia/reperfusion injury is a common pathophysiological process in the clinic. It causes various injuries, multiple organ dysfunction, and even death. There are several possible mechanisms about ischemia/reperfusion injury, but the influence on intestinal myenteric neurons and the underlying mechanism are still unclear. C57BL6/J mice were used to establish the ischemia/reperfusion model in vivo. Peritoneal macrophages were used for ATP depletion and hypoxia/reoxygenation experiment in vitro. L-cysteine, as the substrate of hydrogen sulfide, is involved in many physiological and pathological processes, including inflammation, metabolism, neuroprotection, and vasodilation. In the current study, we confirmed that intestinal ischemia/reperfusion led to the injury of myenteric neurons. From experiments in vitro and in vivo, we demonstrated that L-cysteine protected myenteric neurons from the injury. AOAA reversed the protective effect of L-cysteine. Also, L-cysteine played a protective role mainly by acting on intestinal macrophages via decreasing the expression of NLRP3, cleaved caspase-1, and mature IL-1β. L-cysteine increased cystathionine beta synthase and H₂S produced by intestinal macrophages to protect myenteric mature neurons and enteric neural precursor cells from apoptosis. Moreover, the addition of IL-1β-neutralizing antibody alleviated the injury of myenteric neurons and enteric neural precursor cells caused by intestinal ischemia/reperfusion. Our study provided a new target for the protection of myenteric neurons in clinical intestinal ischemia/reperfusion injury.

Ubiquitin-specific protease 7 regulates myocardial ischemia/reperfusion injury by stabilizing Keap1

Myocardial ischemia/reperfusion (I/R) injury is a complex pathological process that is still not fully understood. The oxidative stress response has a critical role in the occurrence and progression of myocardial ischemia/reperfusion injury. This study investigated the specific mechanism of ubiquitin-specific protease 7 (USP7) regulation of myocardial ischemia/reperfusion injury from the perspective of proteasome degradation and its relation with the Keap1 pathway, a vital regulator of cytoprotective responses to endogenous and exogenous stress induced by reactive oxygen species (ROS) and electrophiles. Our data indicated that USP7 expression is increased during myocardial ischemia/reperfusion injury in mice, while its inhibiting suppressed the generation of oxygen free radicals and myocardial cell apoptosis, reduced myocardial tissue damage, and improved heart function. Mechanistically, USP7 stabilizes Keap1 by regulating its ubiquitination. Taken together, these findings demonstrate the potential therapeutic effect of USP7 on myocardial ischemia/reperfusion injury.

The Non-Specific Lethal (NSL) Histone Acetyltransferase Complex Transcriptionally Regulates Yin Yang 1-Mediated Cell Proliferation in Human Cells

The human males absent on the first (MOF)-containing non-specific lethal (NSL) histone acetyltransferase (HAT) complex acetylates histone H4 at lysine K5, K8, and K16. This complex shares several subunits with other epigenetic regulatory enzymes, which highlights the complexity of its intracellular function. However, the effect of the NSL HAT complex on the genome and target genes in human cells is still unclear. By using a CRISPR/Cas9-mediated NSL3-knockout 293T cell line and chromatin immunoprecipitation-sequencing (ChIP-Seq) approaches, we identified more than 100 genes as NSL HAT transcriptional targets, including several transcription factors, such as Yin Yang 1 (YY1) which are mainly involved in cell proliferation, biological adhesion, and metabolic processes. We found here that the ChIP-Seq peaks of MOF and NSL3 co-localized with H4K16ac, H3K4me2, and H3K4me3 at the transcriptional start site of YY1. In addition, both the mRNA and protein expression levels of YY1 were regulated by silencing or overexpressing NSL HAT. Interestingly, the expression levels of cell division cycle 6, a downstream target gene of YY1, were regulated by MOF or NSL3. In addition, the suppressed clonogenic ability of HepG2 cells caused by siNSL3 was reversed by overexpressing YY1, suggesting the involvement of YY1 in NSL HAT functioning. Additionally, de novo motif analysis of MOF and NSL3 targets indicated that the NSL HAT complex may recognize the specific DNA-binding sites in the promoter region of target genes in order to regulate their transcription.

The histone demthylase KDM3A protects the myocardium from ischemia/reperfusion injury via promotion of ETS1 expression

Our prior studies have characterized the participation of histone demethylase KDM3A in diabetic vascular remodeling, while its roles in myocardial ischemia/reperfusion (I/R) injury (MIRI) remain to be illustrated. Here we show that KDM3A was significantly downregulated in rat I/R and cellular hypoxia/reoxygenation (H/R) models. Subsequently, gain- and loss-of-function experiments were performed to investigate the effects of KDM3A in the settings of MIRI. KDM3A knockout exacerbated cardiac dysfunction and cardiomyocytes injury both in vivo and in vitro. The deteriorated mitochondrial apoptosis, reactive oxygen species, and inflammation were simultaneously observed. Conversely, KDM3A overexpression developed the ameliorated alternations in MIRI. Mechanistically, the MIRI-alleviating effects of KDM3A were associated with the enhancement of ETS1 expression. ChIP-PCR affirmed that KDM3A bound to the ETS1 promoter and removed dimethylation of histone H3 lysine 9 (H3K9me2), thus promoting ETS1 transcription. Our findings suggest that KDM3A is available for alleviating multi-etiologies of MIRI through the regulation of ETS1.

Prevention of cardiac injury requires a deeper mechanistic understanding of ischemia/reperfusion (I/R) episodes. Here, the authors find that the epigenetic modifier KDM3A plays a crucial role in myocardial I/R injury through its activation of the gene ETS1 and suggest boosting KDM3A expression could be a potential treatment strategy.

Histone Methylation and Oxidative Stress in Cardiovascular Diseases

Oxidative stress occurs when ROS overproduction overwhelms the elimination ability of antioxidants. Accumulated studies have found that oxidative stress is regulated by histone methylation and plays a critical role in the development and progression of cardiovascular diseases. Targeting the underlying molecular mechanism to alter the interplay of oxidative stress and histone methylation may enable creative and effective therapeutic strategies to be developed against a variety of cardiovascular disorders. Recently, some drugs targeting epigenetic modifiers have been used to treat specific types of cancers. However, the comprehensive signaling pathways bridging oxidative stress and histone methylation need to be deeply explored in the contexts of cardiovascular physiology and pathology before clinical therapies be developed. In the present review, we summarize and update information on the interplay between histone methylation and oxidative stress during the development of cardiovascular diseases such as atherosclerosis, coronary artery disease, pulmonary hypertension, and diabetic macro- and microvascular pathologies.

Isolevuglandins Scavenger Ameliorates Myocardial Ischemic Injury by Suppressing Oxidative Stress, Apoptosis, and Inflammation

Augmented levels of reactive isolevuglandins (IsoLGs) are responsible for cardiovascular diseases. The role of IsoLGs in myocardial infarction (MI) remains elusive. Here we explored the effect of IsoLGs scavenger 2-hydroxybenzylamine (2-HOBA) in post-infarction cardiac repair. We observed that infarcted cardiac tissues expressed high IsoLGs in mice. Following MI injury, 2-HOBA treated mice displayed decreased infarction area and improved heart function compared with the saline-treated group. Moreover, 2-HOBA effectively attenuated MI-induced cardiac remodeling, oxidative stress, apoptosis, and inflammation. 4-hydroxybenzylamine (4-HOBA), a less reactive isomer of 2-HOBA, barely antagonized the MI-induced injury. These findings suggest that IsoLGs elimination may be helpful in MI therapy.

Macrophage-targeting gene silencing orchestrates myocardial microenvironment remodeling toward the anti-inflammatory treatment of ischemia-reperfusion (IR) injury

Ischemia-reperfusion (IR) injury represents a major cause of myocardial dysfunction after infarction and thrombolytic therapy, and it is closely related to the free radical explosion and overwhelming inflammatory responses. Herein, macrophage-targeting nanocomplexes (NCs) are developed to mediate efficient co-delivery of siRNA against MOF (siMOF) and microRNA-21 (miR21) into myocardial macrophages, cooperatively orchestrating the myocardial microenvironment against IR injury. Bioreducible, branched poly(β-amino ester) (BPAE-SS) is designed to co-condense siMOF and miR21 into NCs in a multivalency-reinforced approach, and they are surface-decorated with carboxylated mannan (Man-COOH) to shield the positive surface charges and enhance the serum stability. The final MBSsm NCs are efficiently internalized by myocardial macrophages after systemic administration, wherein BPAE-SS is degraded into small segments by intracellular glutathione to promote the siMOF/miR21 release, finally provoking efficient gene silencing. Thus, cardiomyocyte protection and macrophage modulation are realized via the combined effects of ROS scavenging, inflammation inhibition, and autophagy attenuation, which ameliorates the myocardial microenvironment and restores the cardiac function via positive cellular crosstalk. This study renders promising solutions to address the multiple systemic barriers against in vivo nucleic acid delivery, and it also offers new options for IR injury by manipulating multiple reciprocal bio-reactions.

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Macrophage-targeting and reduction-dissociable NCs mediate efficient siMOF/miR21 co-delivery.

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siMOF and miR21 cooperatively inhibit ROS production, inflammation, and autophagy.

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siMOF and miR21 orchestrate microenvironment remodeling via cellular cross-talk.

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NCs mediate efficient treatment of myocardial ischemia reperfusion injury.

Targeting Epigenetic Mechanisms in Vascular Aging

Environment, diseases, lack of exercise, and aged tendency of population have becoming crucial factors that induce vascular aging. Vascular aging is unmodifiable risk factor for diseases like diabetes, hypertension, atherosclerosis, and hyperlipidemia. Effective interventions to combat this vascular function decline is becoming increasingly urgent as the rising hospitalization rate caused by vascular aging-related diseases. Fortunately, recent transformative omics approaches have enabled us to examine vascular aging mechanisms at unprecedented levels and precision, which make our understanding of slowing down or reversing vascular aging become possible. Epigenetic viz. DNA methylation, histone modifications, and non-coding RNA-based mechanisms, is a hallmark of vascular aging, its deregulation leads to aberrant transcription changes in tissues. Epigenetics mechanisms by mediating covalent modifications to DNA and histone proteins, consequently, influence the sensitivity and activities of signaling pathways in cells and tissues. A growing body of evidence supports correlations between epigenetic changes and vascular aging. In this article, we will provide a comprehensive overview of epigenetic changes associated with vascular aging based on the recent findings with a focus on molecular mechanisms of action, strategies to reverse epigenetic changes, and future perspectives.

Beta3-Adrenergic Receptor Activation Alleviates Cardiac Dysfunction in Cardiac Hypertrophy by Regulating Oxidative Stress

BACKGROUND

Excessive myocardial oxidative stress could lead to the congestive heart failure. NADPH oxidase is involved in the pathological process of left ventricular (LV) remodeling and dysfunction. β3-Adrenergic receptor (AR) could regulate cardiac dysfunction proved by recent researches. The molecular mechanism of β3-AR regulating oxidative stress, especially NADPH oxidase, remains to be determined.

METHODS

Cardiac hypertrophy was constructed by the transverse aortic constriction (TAC) model. ROS and NADPH oxidase subunits expression were assessed after β3-AR agonist (BRL) or inhibitor (SR) administration in cardiac hypertrophy. Moreover, the cardiac function, fibrosis, heart size, oxidative stress, and cardiomyocytes apoptosis were also detected.

RESULTS

β3-AR activation significantly alleviated cardiac hypertrophy and remodeling in pressure-overloaded mice. β3-AR stimulation also improved heart function and reduced cardiomyocytes apoptosis, oxidative stress, and fibrosis. Meanwhile, β3-AR stimulation inhibited superoxide anion production and decreased NADPH oxidase activity. Furthermore, BRL treatment increased the neuronal NOS (nNOS) expression in cardiac hypertrophy.

CONCLUSION

β3-AR stimulation alleviated cardiac dysfunction and reduced cardiomyocytes apoptosis, oxidative stress, and fibrosis by inhibiting NADPH oxidases. In addition, the protective effect of β3-AR is largely attributed to nNOS activation in cardiac hypertrophy.

Reactive oxygen species-based nanomaterials for the treatment of myocardial ischemia reperfusion injuries

Interventional coronary reperfusion strategies are widely adopted to treat acute myocardial infarction, but morbidity and mortality of acute myocardial infarction are still high. Reperfusion injuries are inevitable due to the generation of reactive oxygen species (ROS) and apoptosis of cardiac muscle cells. However, many antioxidant and anti-inflammatory drugs are largely limited by pharmacokinetics and route of administration, such as short half-life, low stability, low bioavailability, and side effects for treatment myocardial ischemia reperfusion injury. Therefore, it is necessary to develop effective drugs and technologies to address this issue. Fortunately, nanotherapies have demonstrated great opportunities for treating myocardial ischemia reperfusion injury. Compared with traditional drugs, nanodrugs can effectively increase the therapeutic effect and reduces side effects by improving pharmacokinetic and pharmacodynamic properties due to nanodrugs’ size, shape, and material characteristics. In this review, the biology of ROS and molecular mechanisms of myocardial ischemia reperfusion injury are discussed. Furthermore, we summarized the applications of ROS-based nanoparticles, highlighting the latest achievements of nanotechnology researches for the treatment of myocardial ischemia reperfusion injury.

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Cardiovascular diseases are the leading cause of death worldwide. Researches of the myocardial infarction pathology and development of new treatments have very important scientific significance in the biomedical field.

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Many nanomaterials have shown amazing therapeutic effects to reduce myocardial damage by eliminating ROS.

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Nanomaterials effectively reduced myocardial damage through eliminating ROS from NOXs, M-ETC, M-Ca²⁺, M-mPTP, and RIRR.

Physiological interrelationships between NADPH oxidases and chromatin remodelling

The epigenetic landscape describes the chromatin structure of the eukaryotic genome and is therefore the major determinant of gene transcription and hence cellular phenotype. The molecular processes which act to shape the epigenetic landscape through cellular differentiation are thus central to cellular determination and specification. In addition, cellular adaptation to (patho)-physiological stress requires dynamic and reversible chromatin remodelling. It is becoming clear that redox-dependent molecular mechanisms are important determinants of this epigenetic regulation. NADPH oxidases generate reactive oxygen species (ROS) to activate redox-dependent signalling pathways in response to extracellular and intracellular environmental cues. This mini review aims to summarise the current knowledge of the role of NADPH oxidases in redox-dependent chromatin remodelling, and how epigenetic changes might feedback and impact upon the transcriptional expression of these ROS-producing enzymes themselves. The potential physiological significance of this relationship in the control of cellular differentiation and homeostasis by Nox4, specifically, is discussed.

Exercise-induced peptide TAG-23 protects cardiomyocytes from reperfusion injury through regulating PKG-cCbl interaction

Recent studies have revealed that proper exercise can reduce the risk of chronic disease and is beneficial to the body. Peptides have been shown to play an important role in various pathological processes, including cardiovascular diseases. However, little is known about the role of exercise-induced peptides in cardiovascular disease. We aimed to explore the function and mechanism of TAG-23 peptide in reperfusion injury and oxidative stress. Treatment with TAG-23 peptide significantly improved cell viability, the mitochondrial membrane potential, and ROS levels and reduced LDH release, the apoptosis rate and caspase 3 activation in vitro. In vivo, TAG-23 ameliorated MI and heart failure induced by I/R or DOX treatment. Pull-down assays showed that TAG-23 can bind to PKG . The TAG-23-PKG complex inhibited PKG degradation through the UPS. We also identified cCbl as the E3 ligase of PKG and found that the interaction between these proteins was impaired by TAG-23 treatment. In addition, we provided evidence that TAG-23 mediated Lys48-linked polyubiquitination and subsequent proteasomal degradation. Our results reveal that a novel exercise-induced peptide, TAG-23, can inhibit PKG degradation by serving as a competitive binding peptide to attenuate the formation of the PKG–cCbl complex. Treatment with TAG-23 may be a new therapeutic approach for reperfusion injury.

The Jumonji Domain-Containing Histone Demethylase Homolog 1D/lysine Demethylase 7A (JHDM1D/KDM7A) Is an Epigenetic Activator of RHOJ Transcription in Breast Cancer Cells

The small GTPase RHOJ is a key regulator of breast cancer metastasis by promoting cell migration and invasion. The prometastatic stimulus TGF-β activates RHOJ transcription via megakaryocytic leukemia 1 (MKL1). The underlying epigenetic mechanism is not clear. Here, we report that MKL1 deficiency led to disrupted assembly of the RNA polymerase II preinitiation complex on the RHOJ promoter in breast cancer cells. This could be partially explained by histone H3K9/H3K27 methylation status. Further analysis confirmed that the H3K9/H3K27 dual demethylase JHDM1D/KDM7A was essential for TGF-β-induced RHOJ transcription in breast cancer cells. MKL1 interacted with and recruited KDM7A to the RHOJ promoter to cooperatively activate RHOJ transcription. KDM7A knockdown attenuated migration and invasion of breast cancer cells in vitro and mitigated the growth and metastasis of breast cancer cells in nude mice. KDM7A expression level, either singularly or in combination with that of RHOJ, could be used to predict prognosis in breast cancer patients. Of interest, KDM7A appeared to be a direct transcriptional target of TGF-β signaling. A SMAD2/SMAD4 complex bound to the KDM7A promoter and mediated TGF-β-induced KDM7A transcription. In conclusion, our data unveil a novel epigenetic mechanism whereby TGF-β regulates the transcription of the prometastatic small GTPase RHOJ. Screening for small-molecule inhibitors of KDM7A may yield effective therapeutic solutions to treat malignant breast cancers.

A small molecule inhibitor of Nox2 and Nox4 improves contractile function after ischemia-reperfusion in the mouse heart

The NADPH oxidase enzymes Nox2 and 4, are important generators of Reactive oxygen species (ROS). These enzymes are abundantly expressed in cardiomyocytes and have been implicated in ischemia-reperfusion injury. Previous attempts with full inhibition of their activity using genetically modified animals have shown variable results, suggesting that a selective and graded inhibition could be a more relevant approach. We have, using chemical library screening, identified a new compound (GLX481304) which inhibits Nox 2 and 4 (with IC50 values of 1.25 µM) without general antioxidant effects or inhibitory effects on Nox 1. The compound inhibits ROS production in isolated mouse cardiomyocytes and improves cardiomyocyte contractility and contraction of whole retrogradely (Langendorff) perfused hearts after a global ischemia period. We conclude that a pharmacological and partial inhibition of ROS production by inhibition of Nox 2 and 4 is beneficial for recovery after ischemia reperfusion and might be a promising venue for treatment of ischemic injury to the heart.

MRTF: Basic Biology and Role in Kidney Disease

A lesser known but crucially important downstream effect of Rho family GTPases is the regulation of gene expression. This major role is mediated via the cytoskeleton, the organization of which dictates the nucleocytoplasmic shuttling of a set of transcription factors. Central among these is myocardin-related transcription factor (MRTF), which upon actin polymerization translocates to the nucleus and binds to its cognate partner, serum response factor (SRF). The MRTF/SRF complex then drives a large cohort of genes involved in cytoskeleton remodeling, contractility, extracellular matrix organization and many other processes. Accordingly, MRTF, activated by a variety of mechanical and chemical stimuli, affects a plethora of functions with physiological and pathological relevance. These include cell motility, development, metabolism and thus metastasis formation, inflammatory responses and—predominantly-organ fibrosis. The aim of this review is twofold: to provide an up-to-date summary about the basic biology and regulation of this versatile transcriptional coactivator; and to highlight its principal involvement in the pathobiology of kidney disease. Acting through both direct transcriptional and epigenetic mechanisms, MRTF plays a key (yet not fully appreciated) role in the induction of a profibrotic epithelial phenotype (PEP) as well as in fibroblast-myofibroblast transition, prime pathomechanisms in chronic kidney disease and renal fibrosis.

HDAC9 exacerbates myocardial infarction via inactivating Nrf2 pathways

OBJECTIVES

Myocardial infarction (MI) is the leading cause of death worldwide. Histone deacetylases (HDACs) collectively participate in the initiation and progression of heart diseases, including MI. This study aimed to investigate the roles of histone deacetylase 9 (HDAC9) in the development of MI.

METHODS

In vivo and in vitro assays were conducted to determine the effects of HDAC9 on heart function and MI. qRT-PCR was applied to determine the mRNA level. Western blot was performed for protein expression. Immunofluorescence was applied to detect the fluorescence tensity of Myog and Myod. CCK-8, flow cytometry and transwell assays were carried out for function analysis.

KEY FINDINGS

HDAC9 was upregulated in MI models in vivo and in vitro. Downregulated HDAC9 modulated the changes in left ventricle ejection fraction (LVEF), left ventricle fractional shortening (LVFS) and left ventricular end-diastolic diameter (LVEDD) and left ventricular end-systolic diameter (LVESD). Moreover, HDAC9 knockdown activated NFE2-related factor 2 (Nrf2)/Keap1/HO-1 pathways. Additionally, HDAC9/Nrf2 axis modulated the proliferation, apoptosis and myogenesis of cardiomyocytes.

CONCLUSIONS

Taken together, HDAC9 knockout induced the activation of Nrf2 and protected heart from MI injury. Thus, the HDAC9/Nrf2 axis can be a novel marker for the treatment of MI.

Protective effect of selenomethionine on T-2 toxin-induced liver injury in New Zealand rabbits

Background

T-2 toxin is a mycotoxin produced by Fusarium species that is highly toxic to animals. Recent studies have indicated that Selenomethionine (SeMet) have protective effect against mycotoxins-induced toxicity. The aim of the present study was to investigate the protective effect of SeMet on T-2-toxin-induced liver injury in rabbit and explore its molecular mechanism. Fifty rabbits (30 d, 0.5 ± 0.1 kg) were randomly divided into 5 groups: control group, T-2 toxin group, low, medium and high dose SeMet treatment group. The SeMet-treated group was orally pretreated with SeMet (containing selenium 0.2 mg/kg, 0.4 mg/kg and 0.6 mg/kg) for 21 days. On the 17th day, T-2 toxin group and SeMet-treated group were orally administered with T-2 toxin (0.4 mg/kg body weight) for 5 consecutive days.

Results

The results showed that low-dose SeMet significantly improved T-2 toxin-induced liver injury. We found that low-dose SeMet can reduce the level of oxidative stress and the number of hepatocyte apoptosis. Moreover, the levels of Bax, caspase-3 and caspase-9 were significantly reduced and the levels of Bcl-2 were increased.

Conclusions

Therefore, we confirmed that low-dose SeMet may protect rabbit hepatocytes from T-2 toxin by inhibiting the mitochondrial-caspase apoptosis pathway.

Myeloid MKL1 Disseminates Cues to Promote Cardiac Hypertrophy in Mice

Cardiac hypertrophy is a key pathophysiological process in the heart in response to stress cues. Although taking place in cardiomyocytes, the hypertrophic response is influenced by other cell types, both within the heart and derived from circulation. In the present study we investigated the myeloid-specific role of megakaryocytic leukemia 1 (MKL1) in cardiac hypertrophy. Following transverse aortic constriction (TAC), myeloid MKL1 conditional knockout (MFCKO) mice exhibit an attenuated phenotype of cardiac hypertrophy compared to the WT mice. In accordance, the MFCKO mice were protected from excessive cardiac inflammation and fibrosis as opposed to the WT mice. Conditioned media collected from macrophages enhanced the pro-hypertrophic response in cardiomyocytes exposed to endothelin in an MKL1-dependent manner. Of interest, expression levels of macrophage derived miR-155, known to promote cardiac hypertrophy, were down-regulated in the MFCKO mice compared to the WT mice. MKL1 depletion or inhibition repressed miR-155 expression in macrophages. Mechanistically, MKL1 interacted with NF-κB to activate miR-155 transcription in macrophages. In conclusion, our data suggest that MKL1 may contribute to pathological hypertrophy via regulating macrophage-derived miR-155 transcription.

Myocardin-related transcription factor A (MRTF-A) regulates integrin beta 2 transcription to promote macrophage infiltration and cardiac hypertrophy in mice

AIMS

Macrophage-mediated inflammatory response represents a key pathophysiological process in a host of cardiovascular diseases including heart failure. Regardless of etiology, heart failure is invariably preceded by cardiac hypertrophy. In the present study we investigated the effect of macrophage-specific deletion of myocardin-related transcription factor A (MRTF-A) on cardiac hypertrophy and the underlying mechanism.

METHODS AND RESULTS

We report that when subjected to transverse aortic constriction (TAC), macrophage MRTF-A conditional knockout (CKO) mice developed a less severe phenotype of cardiac hypertrophy compared to wild type (WT) littermates and were partially protected from the loss of heart function. In addition, there was less extensive cardiac fibrosis in the CKO mice than WT mice following the TAC procedure. Further analysis revealed that cardiac inflammation, as assessed by levels of pro-inflammatory cytokines and chemokines, was dampened in CKO mice paralleling reduced infiltration of macrophages in the heart. Mechanistically, MRTF-A deficiency attenuated the expression of integrin beta 2 (ITGB2/CD18) in macrophage thereby disrupting adhesion of macrophages to vascular endothelial cells. MRTF-A was recruited by Sp1 to the ITGB2 promoter and cooperated with Sp1 to activate ITGB2 transcription in macrophages. Administration of a CD18 blocking antibody attenuated TAC induced cardiac hypertrophy in mice. Interaction between MRTF-A and the histone demethylase KDM3A likely contributed to IGTB2 transcription and consequently adhesion of macrophages to endothelial cells.

CONCLUSIONS

Our data suggest that MRTF-A may regulate macrophage trafficking and contribute to the pathogenesis of cardiac hypertrophy by activating ITGB2 transcription.

MKL1 cooperates with p38MAPK to promote vascular senescence, inflammation, and abdominal aortic aneurysm

Abdominal aortic aneurysm (AAA) is a catastrophic disease with little effective therapy. Myocardin related transcription factor A (MRTFA, MKL1) is a multifaceted transcription factor, regulating diverse biological processes. However, a detailed understanding of the mechanistic role of MKL1 in AAA has yet to be elucidated. In this study, we showed induced MKL1 expression in thoracic and abdominal aneurysmal tissues, respectively in both mice and humans. MKL1 global knockout mice displayed reduced AAA formation and aortic rupture compared with wild-type mice. Both gene deletion and pharmacological inhibition of MKL1 markedly protected mice from aortic dissection, an early event in Angiotensin II (Ang II)-induced AAA formation. Loss of MKL1 was accompanied by reduced senescence/proinflammation in the vessel wall and cultured vascular smooth muscle cells (VSMCs). Mechanistically, a deficiency in MKL1 abolished AAA-induced p38 mitogen activated protein kinase (p38MAPK) activity. Similar to MKL1, loss of MAPK14 (p38α), the dominant isoform of p38MAPK family in VSMCs suppressed Ang II-induced AAA formation, vascular inflammation, and senescence marker expression. These results reveal a molecular pathway of AAA formation involving MKL1/p38MAPK stimulation and a VSMC senescent/proinflammatory phenotype. These data support targeting MKL1/p38MAPK pathway as a potential effective treatment for AAA.

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MKL1 expression is induced in both thoracic and abdominal aneurysmal tissues.

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Genetic ablation and pharmacological inhibition of MKL1 protect mice from aortic dissection and AAA induced by Ang II.

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Depletion of MKL1 in mice suppresses Ang II-induced vascular inflammation and senescence.

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Depletion of MKL1 blunts the activation of p38MAPK and STAT3 pathways.

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Loss of MAPK14 in VSMCs suppresses Ang II-induced AAA formation, vascular inflammation, and senescence marker expression.

Uric acid aggravates myocardial ischemia-reperfusion injury via ROS/NLRP3 pyroptosis pathway

BACKGROUND

The NOD-like receptor pyrin domain-containing protein 3 (NLRP3) inflammasome activation-mediated pyroptosis pathway has been linked to myocardial ischemia-reperfusion (MI/R) injury. This study explored whether uric acid (UA) aggravates MI/R injury through NLRP3 inflammasome-mediated pyroptosis.

METHODS

In vivo, a mouse MI/R model was established by ligating the left coronary artery, and a mouse hyperuricemia model was created by intraperitoneal injection of potassium oxonate (PO). Then, the myocardial infarction (MI) size; terminal deoxynucleotidyl transferase dUTP nick end-labeling (TUNEL) immunofluorescence; and serum levels of lactate dehydrogenase (LDH), creatine kinase isoenzyme (CK-MB), and UA, as well as the expression level of pyroptosis-related protein and caspase-3 in heart tissues, were measured. Separately, primary mouse cardiomyocytes were cultured in vitro to create a hypoxia/reoxygenation (H/R) model. We then compared cardiomyocytes viability, TUNEL immunofluorescence, and the levels of LDH, reactive oxygen species (ROS), and pyroptosis-related protein and caspase-3 in cardiomyocytes.

RESULTS

In vivo, the MI area, levels of CK-MB and LDH, rate of cell death, and pyroptosis-related protein and the expression of caspase-3 were significantly higher in the MI/R group than in the sham group, and high UA levels worsened these changes. In vitro, cardiomyocytes viability was significantly downregulated, and the levels of ROS, LDH, pyroptosis-related protein, caspase-3, and the rate of cardiomyocyte death were significantly higher in the H/R + UA group compared with the HR group. Administration of an NLRP3 inflammasome inhibitor and ROS scavenger reversed these effects.

CONCLUSION

UA aggravates MI/R-induced activation of the NLRP3 inflammatory cascade and pyroptosis by promoting ROS generation, while inflammasome inhibitors and ROS scavengers partly reverse the injury.