Autophagy in cardiovascular biology

The role of glucagon-like peptide-1/GLP-1R and autophagy in diabetic cardiovascular disease

Diabetes leads to a significantly accelerated incidence of various related macrovascular complications, including peripheral vascular disease and cardiovascular disease (the most common cause of mortality in diabetes), as well as microvascular complications such as kidney disease and retinopathy. Endothelial dysfunction is the main pathogenic event of diabetes-related vascular disease at the earliest stage of vascular injury. Understanding the molecular processes involved in the development of diabetes and its debilitating vascular complications might bring up more effective and specific clinical therapies. Long-acting glucagon-like peptide (GLP)-1 analogs are currently available in treating diabetes with widely established safety and extensively evaluated efficacy. In recent years, autophagy, as a critical lysosome-dependent self-degradative process to maintain homeostasis, has been shown to be involved in the vascular endothelium damage in diabetes. In this review, the GLP-1/GLP-1R system implicated in diabetic endothelial dysfunction and related autophagy mechanism underlying the pathogenesis of diabetic vascular complications are briefly presented. This review also highlights a possible crosstalk between autophagy and the GLP-1/GLP-1R axis in the treatment of diabetic angiopathy.

6PPD induced cardiac dysfunction in zebrafish associated with mitochondrial damage and inhibition of autophagy processes

The compound 6PPD is widely acknowledged for its antioxidative properties; however, concerns regarding its impact on aquatic organisms have spurred comprehensive investigations. In our study, we advanced our comprehension by revealing that exposure to 6PPD could induce cardiac dysfunction, myocardial injury and DNA damage in adult zebrafish. Furthermore, our exploration unveiled that the exposure of cardiomyocytes to 6PPD resulted in apoptosis and mitochondrial injury, as corroborated by analyses using transmission electron microscopy and flow cytometry. Significantly, our study demonstrated the activation of the autophagy pathway in both the heart of zebrafish and cardiomyocytes, as substantiated by transmission electron microscopy and immunofluorescent techniques. Importantly, the increased the expression of P62 in the heart and cardiomyocytes suggested an inhibition of the autophagic process. The reduction in autophagy flux was also verified through in vivo experiments involving the infection of mCherry-GFP-LC3. We further identified that the fusion of autophagosomes and lysosomes was impaired in the 6PPD treatment group. In summary, our findings indicated that the impaired fusion of autophagosomes and lysosomes hampered the autophagic degradation process, leading to apoptosis and ultimately resulting in cardiac dysfunction and myocardial injury. This study discovered the crucial role of the autophagy pathway in regulating 6PPD-induced cardiotoxicity. SYNOPSIS: 6PPD exposure inhibited the autophagic degradation process and induced mitochondrial injury and apoptosis in the heart of adult zebrafish.

Inhibition of autophagy prevents cardiac dysfunction at early stages of cardiomyopathy in Bag3-deficient hearts

The HSP70 co-chaperone BAG3 targets unfolded proteins to degradation via chaperone assisted selective autophagy (CASA), thereby playing pivotal roles in the proteostasis of adult cardiomyocytes (CMs). However, the complex functions of BAG3 for regulating autophagy in cardiac disease are not completely understood. Here, we demonstrate that conditional inactivation of Bag3 in murine CMs leads to age-dependent dysregulation of autophagy, associated with progressive cardiomyopathy. Surprisingly, Bag3-deficient CMs show increased canonical and non-canonical autophagic flux in the juvenile period when first signs of cardiac dysfunction appear, but reduced autophagy during later stages of the disease. Juvenile Bag3-deficient CMs are characterized by decreased levels of soluble proteins involved in synchronous contraction of the heart, including the gap junction protein Connexin 43 (CX43). Reiterative administration of chloroquine (CQ), an inhibitor of canonical and non-canonical autophagy, but not inactivation of Atg5, restores normal concentrations of soluble cardiac proteins in juvenile Bag3-deficient CMs without an increase of detergent-insoluble proteins, leading to complete recovery of early-stage cardiac dysfunction in Bag3-deficient mice. We conclude that loss of Bag3 in CMs leads to age-dependent differences in autophagy and cardiac dysfunction. Increased non-canonical autophagic flux in the juvenile period removes soluble proteins involved in cardiac contraction, leading to early-stage cardiomyopathy, which is prevented by reiterative CQ treatment.

Targeting autophagy in diabetic cardiomyopathy: From molecular mechanisms to pharmacotherapy

Diabetic cardiomyopathy (DCM) is a cardiac microvascular complication caused by metabolic disorders. It is characterized by myocardial remodeling and dysfunction. The pathogenesis of DCM is associated with abnormal cellular metabolism and organelle accumulation. Autophagy is thought to play a key role in the diabetic heart, and a growing body of research suggests that modulating autophagy may be a potential therapeutic strategy for DCM. Here, we have summarized the major signaling pathways involved in the regulation of autophagy in DCM, including Adenosine 5'-monophosphate-activated protein kinase (AMPK), mechanistic target of rapamycin (mTOR), Forkhead box subfamily O proteins (FOXOs), Sirtuins (SIRTs), and PTEN-inducible kinase 1 (PINK1)/Parkin. Given the significant role of autophagy in DCM, we further identified natural products and chemical drugs as regulators of autophagy in the treatment of DCM. This review may help to better understand the autophagy mechanism of drugs for DCM and promote their clinical application.

Maternal dietary copper deficiency induces cardiomyopathy and liver injury in mice by activating autophagy

Maternal nutritional deficiencies during pregnancy result in birth defects and elevate the risk of cardiovascular diseases and metabolic diseases. Accumulating evidence suggests that deficiency of copper, a fundamental trace element involved in several pivotal physiological processes, promotes the onset of multiple diseases, notably heart and liver diseases. Yet, exploration into the effects of maternal copper deficiency (CuD) on offspring is still limited. In this study, we hypothesized that maternal CuD induced cardiomyopathy and liver injury in offspring through the activation of autophagy. We established a maternal CuD mouse model by feeding pregnant C57BL/6 mice with a CuD diet until the end of the experiment. Echocardiography, histological analysis, western blotting, and quantitative polymerase chain reaction were performed on offspring at postnatal day 14. We found that maternal CuD caused growth retardation and early postnatal death in the offspring. Furthermore, our results revealed that CuD induced cardiac systolic dysfunction, cardiac hypertrophy, hepatic steatosis, and liver injury. Moreover, higher expression of LC3 and lower expression of p62 were observed in the heart tissues and liver tissues of CuD mice compared with the control group, indicating that CuD induced autophagy activation. In conclusion, maternal CuD caused severely deleterious effects on the heart and liver of the offspring via activating autophagy.

PCSK9 induces endothelial cell autophagy by regulating the PI3K/ATK pathway in atherosclerotic coronary heart disease

OBJECTIVE

Atherosclerosis is a chronic inflammatory disease of the arteries, and its pathogenesis is related to endothelial dysfunction. It has been found that the protein convertase subtilin/kexin9 type (PCSK9) plays an important role in AS, but its specific mechanism is still unclear.

METHODS

In this study, we first cultured human umbilical vein endothelial cells (HUVECs) with 50 or 100μg/ml oxidized low-density lipoprotein (ox-LDL) for 24 hours to establish a coronary atherosclerosis cell model.

RESULTS

The results showed that ox-LDL induced HUVEC injury and autophagy and upregulated PCSK9 protein expression in HUVECs in a concentration-dependent manner. Silencing PCSK9 expression with siRNA inhibited ox-LDL-induced HUVEC endothelial dysfunction, inhibited the release of inflammatory factors, promoted HUVEC proliferation and inhibited apoptosis. In addition, ox-LDL increased the expression of LC3B-I and LC3B-II and decreased the expression of p62. However, these processes are reversed by sh-PCSK9. In addition, sh-PCSK9 can inhibit PI3K, AKT and mTOR phosphorylation and promote autophagy.

CONCLUSION

Taken together, our research shows that silencing PCSK9 inhibits the PI3K/ATK/mTOR pathway to activate ox-LDL-induced autophagy in vascular endothelial cells, alleviating endothelial cell injury and inflammation.

Stem cell models of TAFAZZIN deficiency reveal novel tissue-specific pathologies in Barth Syndrome

Barth syndrome (BTHS) is a rare mitochondrial disease caused by pathogenic variants in the gene TAFAZZIN, which leads to abnormal cardiolipin (CL) metabolism on the inner mitochondrial membrane. Although TAFAZZIN is ubiquitously expressed, BTHS involves a complex combination of tissue specific phenotypes including cardiomyopathy, neutropenia, skeletal myopathy, and growth delays, with a relatively minimal neurological burden. To understand both the developmental and functional effects of TAZ-deficiency in different tissues, we generated isogenic TAZ knockout (TAZ- KO) and WT cardiomyocytes (CMs) and neural progenitor cells (NPCs) from CRISPR-edited induced pluripotent stem cells (iPSCs). In TAZ-KO CMs we discovered evidence of dysregulated mitophagy including dysmorphic mitochondria and mitochondrial cristae, differential expression of key autophagy-associated genes, and an inability of TAZ-deficient CMs to properly initiate stress-induced mitophagy. In TAZ-deficient NPCs we identified novel phenotypes including a reduction in CIV abundance and CIV activity in the CIII2&CIV2 intermediate complex. Interestingly, while CL acyl chain manipulation was unable to alter mitophagy defects in TAZ-KO CMs, we found that linoleic acid or oleic acid supplementation was able to partially restore CIV abundance in TAZ-deficient NPCs. Taken together, our results have implications for understanding the tissue-specific pathology of BTHS and potential for tissue-specific therapeutic targeting. Moreover, our results highlight an emerging role for mitophagy in the cardiac pathophysiology of BTHS and reveal a potential neuron-specific bioenergetic phenotype.

MLKL Protects Pulmonary Endothelial Cells in Acute Lung Injury

The role of autophagy in pulmonary microvascular endothelial cells (PMVECs) is controversial in LPS-induced acute lung injury (ALI). Mixed lineage kinase domain-like pseudokinase (MLKL) has recently been reported to maintain cell survival by facilitating autophagic flux in response to starvation rather than its well-recognized role in necroptosis. Using a mouse PMVEC and LPS-induced ALI model, we showed that in PMVECs, MLKL was phosphorylated (p-MLKL) and autophagic flux was accelerated at the early stage of LPS stimulation (1-3 h), manifested by increases in concentrations of lipidated MAP1LC3B/LC3B (microtubule-associated protein 1 light chain 3 β; LC3-II), decreases in concentrations of SQSTM1/p62 (sequestosome 1), and fusion of the autophagosome and lysosome by pHluorin-mKate2-human LC3 assay, which were all reversed by either MLKL inhibitor or siRNA MLKL. In mice, the inhibition of MLKL increased vascular permeability and aggravated mouse ALI upon 3-hour LPS stimulation. The p-MLKL induced by short-term LPS formed multimers to facilitate the closure of the phagophore by HaloTag-LC3 autophagosome completion assay. The charged multivesicular body protein 2A (CHMP2A) is essential in the process of phagophore closure into the nascent autophagosome. In agreement with the p-MLKL change, CHMP2A concentrations markedly increased during 1-3-hour LPS stimulation. CHMP2A knockdown blocked autophagic flux upon LPS stimulation, whereas CHMP2A overexpression boosted autophagic flux and attenuated mouse ALI even in the presence of MLKL inhibitor. We propose that the activated MLKL induced by short-term LPS facilitates autophagic flux by accelerating the closure of the phagophore via CHMP2A, thus protecting PMVECs and alleviating LPS-induced ALI.

NADPH oxidase 2 mediates cardiac sympathetic denervation and myocyte autophagy, resulting in cardiac atrophy and dysfunction in doxorubicin-induced cardiomyopathy

Doxorubicin has been used extensively as a potent anticancer agent, but its clinical use is limited by its cardiotoxicity. However, the underlying mechanisms remain to be fully elucidated. In this study, we tested whether NADPH oxidase 2 (Nox2) mediates cardiac sympathetic nerve terminal abnormalities and myocyte autophagy, resulting in cardiac atrophy and dysfunction in doxorubicin-induced heart failure. Nox2 knockout (KO) and wild-type (WT) mice were randomly assigned to receive a single injection of doxorubicin (15 mg/kg, i.p.) or saline. WT doxorubicin mice exhibited the decreases in survival rate, left ventricular (LV) wall thickness and LV fractional shortening and the increase in the lung wet-to-dry weight ratio 1 week after the injections. These alterations were attenuated in Nox2 KO doxorubicin mice. In WT doxorubicin mice, myocardial oxidative stress was increased, myocardial noradrenergic nerve fibers were reduced, myocardial expression of PGP9.5, GAP43, tyrosine hydroxylase and norepinephrine transporter was decreased, and these changes were prevented in Nox2 KO doxorubicin mice. Myocyte autophagy was increased and myocyte size was decreased in WT doxorubicin mice, but not in Nox2 KO doxorubicin mice. Nox2 mediates cardiac sympathetic nerve terminal abnormalities and myocyte autophagy-both of which contribute to cardiac atrophy and failure after doxorubicin treatment.

NADPH oxidase 2 inhibitor GSK2795039 prevents doxorubicin-induced cardiac atrophy by attenuating cardiac sympathetic nerve terminal abnormalities and myocyte autophagy

Doxorubicin is widely used for the treatment of human cancer, but its clinical use is limited by a cumulative dose-dependent cardiotoxicity. However, the mechanism of doxorubicin-induced cardiac atrophy and failure remains to be fully understood. In this study, we tested whether the specific NADPH oxidase 2 (Nox2) inhibitor GSK2795039 attenuates cardiac sympathetic nerve terminal abnormalities and myocyte autophagy, leading to the amelioration of cardiac atrophy and dysfunction in chronic doxorubicin-induced cardiomyopathy. Mice were randomized to receive saline, doxorubicin (2.5 mg/kg, every other day, 6 times) or doxorubicin plus GSK2795039 (2.5 mg/kg, twice a day, 9 weeks). Left ventricular (LV) total wall thickness and LV ejection fraction were decreased in doxorubicin-treated mice compared with saline-treated mice and the decreases were prevented by the treatment of the specific Nox2 inhibitor GSK2795039. The ratio of total heart weight to tibia length and myocyte cross-sectional area were decreased in doxorubicin-treated mice, and the decreases were attenuated by the GSK2795039 treatment. In doxorubicin-treated mice, myocardial Nox2 and 4-hydroxynonenal levels were increased, myocardial expression of GAP43, tyrosine hydroxylase and norepinephrine transporter, markers of sympathetic nerve terminals, was decreased, and these changes were prevented by the GSK2795039 treatment. The ratio of LC3 II/I, a marker of autophagy, and Atg5, Atg12 and Atg12-Atg5 conjugate proteins were increased in doxorubicin-treated mice, and the increases were attenuated by the GSK2795039 treatment. These findings suggest that inhibition of Nox2 by GSK2795039 attenuates cardiac sympathetic nerve terminal abnormalities and myocyte autophagy, thereby ameliorating cardiac atrophy and dysfunction after chronic doxorubicin treatment.

Association of Circulating Autophagy Proteins ATG5 and Beclin 1 with Acute Myocardial Infarction in a Case-Control Study

INTRODUCTION

Acute myocardial infarction (AMI) is a main contributor of sudden cardiac death worldwide. The discovery of new biomarkers that can improve AMI risk prediction meets a major clinical need for the identification of high-risk patients and the tailoring of medical treatment. Previously, we reported that autophagy a highly conserved catabolic mechanism for intracellular degradation of cellular components is involved in atherosclerotic plaque phenotype and cardiac pathological remodeling. The crucial role of autophagy in the normal and diseased heart has been well described, and its activation functions as a pro-survival process in response to myocardial ischemia. However, autophagy is dysregulated in ischemia/reperfusion injury, thus promoting necrotic or apoptotic cardiac cell death. Very few studies have focused on the plasma levels of autophagy markers in cardiovascular disease patients, even though they could be companion biomarkers of AMI injury. The aims of the present study were to evaluate (1) whether variations in plasma levels of two key autophagy regulators autophagy-related gene 5 (ATG5) and Beclin 1 (the mammalian yeast ortholog Atg6/Vps30) are associated with AMI and (2) their potential for predicting AMI risk.

METHODS

The case-control study population included AMI patients (n = 100) and control subjects (n = 99) at high cardiovascular risk but without known coronary disease. Plasma levels of ATG5 and Beclin 1 were measured in the whole population study by enzyme-linked immunosorbent assay.

RESULTS

Multivariate analyses adjusted on common cardiovascular factors and medical treatments, and receiver operating characteristic curves demonstrated that ATG5 and Beclin 1 levels were inversely associated with AMI and provided original biomarkers for AMI risk prediction.

CONCLUSION

Plasma levels of autophagy regulators ATG5 and Beclin 1 represent relevant candidate biomarkers associated with AMI.

Suxiao Jiuxin Pill alleviates myocardial ischemia/reperfusion-induced autophagy via miR-193a-3p/ALKBH5 pathway

BACKGROUND

Myocardial ischemia/reperfusion injury (MIRI) poses a formidable challenge to cardiac reperfusion therapy due to the absence of effective clinical interventions. Methylation of N6-methyladenosine (m6A), which is the most common post-transcriptional modifications occurring within mammalian mRNA, is believed to be involved in MIRI by modulating autophagy. MicroRNAs (miRNAs) play a crucial role in regulating gene expression at the post-transcriptional level and have been implicated in the regulation of m6A methylation. Suxiao Jiuxin Pill (SJP) is extensively used in China for the clinical treatment of angina pectoris and confers benefits to patients with acute coronary syndrome who have received percutaneous coronary intervention. However, the precise mechanisms underlying SJP intervention in MIRI remain unclear.

PURPOSE

This study aimed to demonstrate, both in vivo and in vitro, that SJP could alleviate autophagy in MIRI by regulating miR-193a-3p to target and upregulate the demethylase ALKBH5.

METHODS

An in vitro hypoxia/reoxygenation model was established using H9c2 cells, while an in vivo MIRI model was established using Wistar rats. A lentivirus harboring the precursor sequence of miR-193a-3p was employed for its overexpression. Adeno-associated viruses were used to silence both miR-193a-3p and ALKBH5 expressions. Cardiac function, infarct size, and tissue structure in rats were assessed using echocardiography, triphenyl tetrazolium chloride (TTC) staining, and HE staining, respectively. Terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL) was employed to detect the levels of apoptosis in rat cardiac tissue. m6A methylation levels were assessed using colorimetry. GFP-RFP-LC3B was used to monitor autophagic flux and transmission electron microscopy was used to evaluate the development of autophagosomes. Western Blot and qRT-PCR were respectively employed to assess the levels of autophagy-related proteins and miR-193a-3p.

RESULTS

SJP alleviated autophagy, preserved cardiac function, and minimized myocardial damage in the hearts of MIRI rats. SJP attenuated autophagy in H/R H9C2 cells. Elevated levels of miR-193a-3p were observed in the cardiac tissues of MIRI rats and H/R H9C2 cells, whereas SJP downregulated miR-193a-3p levels in these models. ALKBH5, a target gene of miR-193, is negatively regulated by miR-193a-3p. Upon overexpression of miR-193a-3p or silencing of ALKBH5, m6A methylation decreased, and the autophagy-attenuating effects of SJP and its components, senkyunolide A and l-borneol, were lost in H/R H9C2 cells, whereas in MIRI rats, these effects were not abolished but merely weakened. Further investigation indicated that the METTL3 inhibitor STM2475, combined with the silencing of miR-193a-3p, similarly attenuated autophagy in the hearts of MIRI rats. This suggests that a reduction in m6A methylation is involved in autophagy alleviation.

CONCLUSION

We demonstrated that SJP mitigates autophagy in MIRI by downregulating miR-193a-3p, enhancing ALKBH5 expression, and reducing m6A methylation, a mechanism potentially attributed to its constituents, senkyunolide A and l-borneol.

NPC1 promotes autophagy with tumor promotion and acts as a prognostic model for hepatocellular carcinoma

BACKGROUND

more and more studies have indicated that autophagy plays a crucial role in hepatocellular carcinoma (HCC) in recent years. Hence, our study aimed to establish a prognostic signature for HCC based on autophagy-related genes (ARGs) in order to predict the prognosis of HCC.

METHODS

All original gene-expression data and clinical information were downloaded from The Cancer Genome Atlas (TCGA), International Cancer Genome Consortium (ICGC) and Gene Expression Omnibus (GEO). ARGs were obtained from the Human Autophagy Database (HADb). Univariate Cox regression analysis, Least absolute shrinkage and selection operator (LASSO) and Principal Component Analysis (PCA) analysis were performed to identify and validate the validity and reliability of our eight-gene signature, Gene Set Enrichment Analysis (GSEA) was used to perform enrichment analysis by comparing high-risk and low-risk groups in KEGG (Kyoto Encyclopedia of Genes and Genomes) and GO (Gene Ontology) gene sets. Finally, we verified the gene (NPC1) by functional experiments in vitro and in vivo.

RESULTS

8 ARGs were identified for establishing an eight-gene signature. Then, we validated our eight-gene signature in training, internal, external, and entire testing cohorts. Besides, we also explored the relationships between the eight-gene signature and immune infiltration or immune checkpoints. We also identified NPC1 was closely related to Activated CD4 T cell and Type I IFN Response, and higher expressed level of HCC patients was more sensitive to CTLA4 and TNFRSF9 immune checkpoint inhibitors. NPC1 is highly expressed in HCC cells and tumor tissues, which promotes the proliferation, migration, and invasion of tumor cells by activating autophagy..

CONCLUSION

8 ARGs were used to establish a gene signature to predict the prognosis of HCC. we inferred that NPC1 can promote late autophagy, it could be a future novel therapeutic target of HCC.

Regulation and Functions of Autophagy During Animal Development

Autophagy is used to degrade cytoplasmic materials, and is critical to maintain cell and organismal health in diverse animals. Here we discuss the regulation, utilization and impact of autophagy on development, including roles in oogenesis, spermatogenesis and embryogenesis in animals. We also describe how autophagy influences postembryonic development in the context of neuronal and cardiac development, wound healing, and tissue regeneration. We describe recent studies of selective autophagy during development, including mitochondria-selective autophagy and endoplasmic reticulum (ER)-selective autophagy. Studies of developing model systems have also been used to discover novel regulators of autophagy, and we explain how studies of autophagy in these physiologically relevant systems are advancing our understanding of this important catabolic process.

Inhibition of PRKAA/AMPK (Ser485/491) phosphorylation by crizotinib induces cardiotoxicity via perturbing autophagosome-lysosome fusion

Crizotinib, a small-molecule tyrosine kinase inhibitor targeting ALK, MET and ROS1, is the first-line drug for ALK-positive metastatic non-small cell lung cancer and is associated with severe, sometimes fatal, cases of cardiac failure, which increases the risk of mortality. However, the underlying mechanism remains unclear, which causes the lack of therapeutic strategy. We established in vitro and in vivo models for crizotinib-induced cardiotoxicity and found that crizotinib caused left ventricular dysfunction, myocardial injury and pathological remodeling in mice and induced cardiomyocyte apoptosis and mitochondrial injury. In addition, we found that crizotinib prevented the degradation of MET protein by interrupting autophagosome-lysosome fusion and silence of MET or re-activating macroautophagy/autophagy flux rescued the cardiomyocytes death and mitochondrial injury caused by crizotinib, suggesting that impaired autophagy activity is the key reason for crizotinib-induced cardiotoxicity. We further confirmed that recovering the phosphorylation of PRKAA/AMPK (Ser485/491) by metformin re-activated autophagy flux in cardiomyocytes and metformin rescued crizotinib-induced cardiomyocyte injury and cardiac complications. In summary, we revealed a novel mechanism for crizotinib-induced cardiotoxicity, wherein the crizotinib-impaired autophagy process causes cardiomyocyte death and cardiac injury by inhibiting the degradation of MET protein, demonstrated a new function of impeded autophagosome-lysosome fusion in drugs-induced cardiotoxicity, pointed out the essential role of the phosphorylation of PRKAA (Ser485/491) in autophagosome-lysosome fusion and confirmed metformin as a potential therapeutic strategy for crizotinib-induced cardiotoxicity.Abbreviations and Acronyms: AAV: adeno-associated virus; ACAC/ACC: acetyl-Co A carboxylase; AMP: adenosine monophosphate; AMPK: AMP-activated protein kinase; ATG5: autophagy related 5; ATG7: autophagy related 7; CHX: cycloheximide; CKMB: creatine kinase myocardial band; CQ: chloroquine; c-PARP: cleaved poly (ADP-ribose) polymerase; DAPI: 4'6-diamidino-2-phenylindole; EF: ejection fraction; FOXO: forkhead box O; FS: fractional shortening; GSEA: gene set enrichment analysis; H&E: hematoxylin and eosin; HF: heart failure; HW: TL: ratio of heart weight to tibia length; IR: ischemia-reperfusion; KEGG: Kyoto encyclopedia of genes and genomes; LAMP2: lysosomal-associated membrane protein 2; LDH: lactate dehydrogenase; MCMs: mouse cardiomyocytes; MMP: mitochondrial membrane potential; mtDNA: mitochondrial DNA; MYH6: myosin, heavy peptide 6, cardiac muscle, alpha; MYH7: myosin, heavy peptide 7, cardiac muscle, beta; NPPA: natriuretic peptide type A; NPPB: natriuretic peptide type B; PI: propidium iodide; PI3K: phosphoinositide 3-kinase; PRKAA/AMPKα: protein kinase AMP-activated catalytic subunit alpha; qPCR: quantitative real-time PCR; SD: standard deviation; SRB: sulforhodamine B; TKI: tyrosine kinase inhibitor; WGA: wheat germ agglutinin.

Control of NAD+ homeostasis by autophagic flux modulates mitochondrial and cardiac function

Impaired autophagy is known to cause mitochondrial dysfunction and heart failure, in part due to altered mitophagy and protein quality control. However, whether additional mechanisms are involved in the development of mitochondrial dysfunction and heart failure in the setting of deficient autophagic flux remains poorly explored. Here, we show that impaired autophagic flux reduces nicotinamide adenine dinucleotide (NAD+) availability in cardiomyocytes. NAD+ deficiency upon autophagic impairment is attributable to the induction of nicotinamide N-methyltransferase (NNMT), which methylates the NAD+ precursor nicotinamide (NAM) to generate N-methyl-nicotinamide (MeNAM). The administration of nicotinamide mononucleotide (NMN) or inhibition of NNMT activity in autophagy-deficient hearts and cardiomyocytes restores NAD+ levels and ameliorates cardiac and mitochondrial dysfunction. Mechanistically, autophagic inhibition causes the accumulation of SQSTM1, which activates NF-κB signaling and promotes NNMT transcription. In summary, we describe a novel mechanism illustrating how autophagic flux maintains mitochondrial and cardiac function by mediating SQSTM1-NF-κB-NNMT signaling and controlling the cellular levels of NAD+.

Ginsenoside Rb2 improves heart failure by down-regulating miR-216a-5p to promote autophagy and inhibit apoptosis and oxidative stress

BACKGROUND

Ginsenoside Rb2 is beneficial in cardiovascular disease treatment, yet its role in heart failure (HF) is obscure. This study aimed to investigate the effect and mechanism of ginsenoside Rb2 on HF.

METHODS

The left anterior descending branch-ligated HF rat model and oxygen-glucose deprivation/reoxygenation (OGD/R) H9c2 cell model were constructed. Ginsenoside Rb2 were applied for intervention. Heart function indexes, miR-216a-5p expression, autophagy, oxidative stress, apoptosis, cell morphology, and proliferation were detected to explore the effect of ginsenoside Rb2 on HF. Overexpression of miR-216a-5p was employed to explore the specific mechanism of ginsenoside Rb2 on HF.

RESULTS

Ginsenoside Rb2 improved the heart function of HF rats, including the reduction of heart rate, LVEDP, and heart weight/body weight ratio, and the increase of LVSP, +dP/dtmax, -dP/dtmax, LVEF, and LVFS. It also down-regulated miR-216a-5p expression and enhanced OGD/R-induced cardiomyocyte viability. Ginsenoside Rb2 up-regulated Bcl2, LC3B II/I, and Beclin1, and down-regulated Bax, Caspase-3, and p62 in the myocardium of HF rats and OGD/R-induced H9c2 cells. Moreover, ginsenoside Rb2 increased the levels of SOD and CAT, but decreased the levels of MDA and ROS in the myocardium of HF rats and OGD/R-induced H9c2 cells. However, overexpression of miR-216a-5p promoted the apoptosis and oxidative stress of cardiomyocytes and inhibited autophagy, thus reversing the therapeutic effect of ginsenoside Rb2 on HF in vivo and in vitro.

CONCLUSION

Ginsenoside Rb2 demonstrated potential as a therapeutic intervention for HF by enhancing autophagy and reducing apoptosis and oxidative stress through miR-216a-5p downregulation. Further research could explore its application in clinical trials and investigate the complex mechanism networks underlying its effects.

Chemical Biology Perspectives on STING Agonists as Tumor Immunotherapy

Stimulator of interferon genes (STING) is a crucial adaptor protein in the innate immune response. STING activation triggers cytokine secretion, including type I interferon and initiates T cell-mediated adaptive immunity. The activated immune system converts "cold tumors" into "hot tumors" that are highly responsive to T cells by recruiting them to the tumor microenvironment, ultimately leading to potent and long-lasting antitumor effects. Unlike most immune checkpoint inhibitors, STING agonists represent a groundbreaking class of innate immune agonists that hold great potential for effectively targeting various cancer populations and are poised to become a blockbuster in tumor immunotherapy. This review will focus on the correlation between the STING signaling pathway and tumor immunity, as well as explore the impact of STING activation on other biological processes. Ultimately, we will summarize the development and optimization of STING agonists from a medicinal chemistry perspective, evaluate their potential in cancer therapy, and identify possible challenges for future advancement.

Pulmonary tuberculosis biomarker miR-215-5p inhibits autophagosome-lysosome fusion in macrophages

The normal autophagy flux is beneficial for the rapid elimination of phagocytic pathogens by macrophages. However, Mycobacterium tuberculosis interferes with the autophagy flux of macrophages to weaken their immune function and evade immune surveillance. In this study, we found that miRNA-215-5p was downregulated in tuberculosis patients. A potential diagnostic model for tuberculosis was established by combining miRNA-215-5p with three others differentially expressed microRNAs (miRNA-145-5p, miRNA-486-5p and miRNA-628-3p). Furthermore, we discovered that the up-regulated miRNA-215-5p could inhibit the maturation of autophagy by preventing the fusion of autophagosomes with lysosomes in macrophages. The role of TB-specific miRNA-215-5p in inhibiting auto-lysosome formation provides evidence of its potential role in Host-directed therapy for tuberculosis.

The role of heat shock proteins in the pathogenesis of heart failure (Review)

The influence of heat shock proteins (HSPs) on protein quality control systems in cardiomyocytes is currently under investigation. The effect of HSPs on the regulated cell death of cardiomyocytes (CMCs) is of great importance, since they play a major role in the implementation of compensatory and adaptive mechanisms in the event of cardiac damage. HSPs mediate a number of mechanisms that activate the apoptotic cascade, playing both pro‑ and anti‑apoptotic roles depending on their location in the cell. Another type of cell death, autophagy, can in some cases lead to cell death, while in other situations it acts as a cell survival mechanism. The present review considered the characteristics of the expression of HSPs of different molecular weights in CMCs in myocardial damage caused by heart failure, as well as their role in the realization of certain types of regulated cell death.

Nuciferine induces autophagy to relieve vascular cell adhesion molecule 1 activation via repressing the Akt/mTOR/AP1 signal pathway in the vascular endothelium

Pro-inflammatory factor-associated vascular cell adhesion molecule 1 (VCAM1) activation initiates cardiovascular events. This study aimed to explore the protective role of nuciferine on TNFα-induced VCAM1 activation. Nuciferine was administrated to both high-fat diet (HFD)-fed mice and the TNFα-exposed human vascular endothelial cell line. VCAM1 expression and further potential mechanism(s) were explored. Our data revealed that nuciferine intervention alleviated VCAM1 activation in response to both high-fat diet and TNFα exposure, and this protective effect was closely associated with autophagy activation since inhibiting autophagy by either genetic or pharmaceutical approaches blocked the beneficial role of nuciferine. Mechanistical studies revealed that Akt/mTOR inhibition, rather than AMPK, SIRT1, and p38 signal pathways, contributed to nuciferine-activated autophagy, which further ameliorated TNFα-induced VCAM1 via repressing AP1 activation, independent of transcriptional regulation by IRF1, p65, SP1, and GATA6. Collectively, our data uncovered a novel biological function for nuciferine in protecting VCAM1 activation, implying its potential application in improving cardiovascular events.

Activation of AMPK promotes cardiac differentiation by stimulating the autophagy pathway

Autophagy, a critical catabolic process for cell survival against different types of stress, has a role in the differentiation of various cells, such as cardiomyocytes. Adenosine 5'-monophosphate (AMP)-activated protein kinase (AMPK) is an energy-sensing protein kinase involved in the regulation of autophagy. In addition to its direct role in regulating autophagy, AMPK can also influence other cellular processes by regulating mitochondrial function, posttranslational acetylation, cardiomyocyte metabolism, mitochondrial autophagy, endoplasmic reticulum stress, and apoptosis. As AMPK is involved in the control of various cellular processes, it can influence the health and survival of cardiomyocytes. This study investigated the effects of an AMPK inducer (Metformin) and an autophagy inhibitor (Hydroxychloroquine) on the differentiation of human pluripotent stem cell-derived cardiomyocytes (hPSC-CMs). The results showed that autophagy was upregulated during cardiac differentiation. Furthermore, AMPK activation increased the expression of CM-specific markers in hPSC-CMs. Additionally, autophagy inhibition impaired cardiomyocyte differentiation by targeting autophagosome-lysosome fusion. These results indicate the significance of autophagy in cardiomyocyte differentiation. In conclusion, AMPK might be a promising target for the regulation of cardiomyocyte generation by in vitro differentiation of pluripotent stem cells.

Effective Attenuation of Arteriosclerosis Following Lymphatic-Targeted Delivery of Hyaluronic Acid-Decorated Rapamycin Liposomes

Background

The activation of lymphatic vessel function is the crux to resolving atherosclerosis (AS), a chronic inflammatory disease. Rapamycin (RAPA) recently has attracted considerable attention as a potent drug to induce atherosclerotic plaque attenuation. The objective of this work was to develop a ligand-decorated, RAPA-loaded liposome for lymphatic-targeted delivery of drugs to improve abnormal lymphatic structure and function, resulting in highly effective regression of atherosclerotic plaques.

Methods

Hyaluronic acid-decorated, RAPA-loaded liposomes (HA-RL) were fabricated by emulsion-solvent evaporation. The average size, zeta potential, entrapment efficiency were characterized, and the stability and drug release in vitro were investigated. Furthermore, the in vitro and in vivo lymphatic targeting ability were evaluated on lymphatic endothelial cells and LDLR-/- mice, and the efficiency of this nano-system in inducing the attenuation of atherosclerotic plaques was confirmed.

Results

HA-RL had a size of 100 nm, over 90% drug encapsulation efficiency, the storage stability was distinguished, demonstrating a slow release from the lipid nano-carriers. The mean retention time (MRT) and elimination half-life (t1/2β) achieved from HA-RL were 100.27±73.08 h and 70.74±50.80 h, respectively. HA-RL acquired the most prominent efficacy of lymphatic-targeted delivery and atherosclerotic plaques attenuation, implying the successful implementation of this novel drug delivery system in vivo.

Conclusion

HA-RL exhibited the most appreciable lymphatic targeting ability and best atherosclerotic plaques attenuation efficiency, opening a new paradigm and promising perspective for the treatment of arteriosclerosis.

Cellular reprogramming of fibroblasts in heart regeneration

Myocardial infarction causes the loss of cardiomyocytes and the formation of cardiac fibrosis due to the activation of cardiac fibroblasts, leading to cardiac dysfunction and heart failure. Unfortunately, current therapeutic interventions can only slow the disease progression. Furthermore, they cannot fully restore cardiac function, likely because the adult human heart lacks sufficient capacity to regenerate cardiomyocytes. Therefore, intensive efforts have focused on developing therapeutics to regenerate the damaged heart. Several strategies have been intensively investigated, including stimulation of cardiomyocyte proliferation, transplantation of stem cell-derived cardiomyocytes, and conversion of fibroblasts into cardiac cells. Resident cardiac fibroblasts are critical in the maintenance of the structure and contractility of the heart. Fibroblast plasticity makes this type of cells be reprogrammed into many cell types, including but not limited to induced pluripotent stem cells, induced cardiac progenitor cells, and induced cardiomyocytes. Fibroblasts have become a therapeutic target due to their critical roles in cardiac pathogenesis. This review summarizes the reprogramming of fibroblasts into induced pluripotent stem cell-derived cardiomyocytes, induced cardiac progenitor cells, and induced cardiomyocytes to repair a damaged heart, outlines recent findings in utilizing fibroblast-derived cells for heart regeneration, and discusses the limitations and challenges.

Functional defects in hiPSCs-derived cardiomyocytes from patients with a PLEKHM2-mutation associated with dilated cardiomyopathy and left ventricular non-compaction

Dilated cardiomyopathy (DCM) is a primary myocardial disease, leading to heart failure and excessive risk of sudden cardiac death with rather poorly understood pathophysiology. In 2015, Parvari's group identified a recessive mutation in the autophagy regulator, PLEKHM2 gene, in a family with severe recessive DCM and left ventricular non-compaction (LVNC). Fibroblasts isolated from these patients exhibited abnormal subcellular distribution of endosomes, Golgi apparatus, lysosomes and had impaired autophagy flux. To better understand the effect of mutated PLEKHM2 on cardiac tissue, we generated and characterized induced pluripotent stem cells-derived cardiomyocytes (iPSC-CMs) from two patients and a healthy control from the same family. The patient iPSC-CMs showed low expression levels of genes encoding for contractile functional proteins (α and β-myosin heavy chains and 2v and 2a-myosin light chains), structural proteins integral to heart contraction (Troponin C, T and I) and proteins participating in Ca2+ pumping action (SERCA2 and Calsequestrin 2) compared to their levels in control iPSC-derived CMs. Furthermore, the sarcomeres of the patient iPSC-CMs were less oriented and aligned compared to control cells and generated slowly beating foci with lower intracellular calcium amplitude and abnormal calcium transient kinetics, measured by IonOptix system and MuscleMotion software. Autophagy in patient's iPSC-CMs was impaired as determined from a decrease in the accumulation of autophagosomes in response to chloroquine and rapamycin treatment, compared to control iPSC-CMs. Impairment in autophagy together with the deficiency in the expression of NKX2.5, MHC, MLC, Troponins and CASQ2 genes, which are related to contraction-relaxation coupling and intracellular Ca2+ signaling, may contribute to the defective function of the patient CMs and possibly affect cell maturation and cardiac failure with time.

Restored autophagy is protective against PAK3-induced cardiac dysfunction

Despite the development of clinical treatments, heart failure remains the leading cause of mortality. We observed that p21-activated kinase 3 (PAK3) was augmented in failing human and mouse hearts. Furthermore, mice with cardiac-specific PAK3 overexpression exhibited exacerbated pathological remodeling and deteriorated cardiac function. Myocardium with PAK3 overexpression displayed hypertrophic growth, excessive fibrosis, and aggravated apoptosis following isoprenaline stimulation as early as two days. Mechanistically, using cultured cardiomyocytes and human-relevant samples under distinct stimulations, we, for the first time, demonstrated that PAK3 acts as a suppressor of autophagy through hyper-activation of the mechanistic target of rapamycin complex 1 (mTORC1). Defective autophagy in the myocardium contributes to the progression of heart failure. More importantly, PAK3-provoked cardiac dysfunction was mitigated by administering an autophagic inducer. Our study illustrates a unique role of PAK3 in autophagy regulation and the therapeutic potential of targeting this axis for heart failure.

Chlorin e6 (Ce6)-loaded plaque-specific liposome with enhanced photodynamic therapy effect for atherosclerosis treatment

Recently, photodynamic therapy (PDT) has been considered as a new strategy for atherosclerosis treatment. Targeted delivery of photosensitizer could significantly reduce its toxicity and enhance its phototherapeutic efficiency. CD68 is an antibody that can be conjugated to nano-drug delivery systems to actively target plaque sites, owing to its specific binding to CD68 receptors that are highly expressed on the surfaces of macrophage-derived foam cells. Liposomes are very popular nanocarriers due to their ability to encapsulate a wide range of therapeutic compounds including drugs, microRNAs and photosensitizers, and their ability to be surface-modified with targeting moieties leading to the development of nanocarriers with an improved targeted ability. Hence, we designed a Ce6-loaded liposomes using the film dispersion method, followed by the conjugation of CD68 antibody on the liposomal surface through a covalent crosslinking reaction, forming CD68-modified Ce6-loaded liposomes (CD68-Ce6-mediated liposomes). Flow cytometry results indicated that Ce6-containing liposomes were more effective in promoting intracellular uptake after laser irradiation. Furthermore, CD68-modified liposomes significantly strengthened the cellular recognization and thus internalization. Different cell lines have been incubated with the liposomes, and the results showed that CD68-Ce6-mediated liposomes had no significant cytotoxicity to coronary artery endothelial cells (HCAEC) under selected conditions. Interestingly, they promoted autophagy in foam cells through the increase in LC3-Ⅰ, LC3-Ⅱ expression and the decrease in p62 expression, and restrained the migration of mouse aortic vascular smooth muscle cells (MOVAS) in vitro. Moreover, the enhancement of atherosclerotic plaque stability and the reduction in the cholesterol content by CD68-Ce6-mediated liposomes were dependent on transient reactive oxygen species (ROS) generated under laser irradiation. In summary, we demonstrated that CD68-Ce6-mediated liposomes, as a photosensitizer nano-drug delivery system, have an inhibitory effect on MOVAS migration and a promotion of cholesterol efflux in foam cells, and thereby, represent promising nanocarriers for atherosclerosis photodynamic therapy.

MicroRNA-216a is essential for cardiac angiogenesis

While it is experimentally supported that impaired myocardial vascularization contributes to a mismatch between myocardial oxygen demand and supply, a mechanistic basis for disruption of coordinated tissue growth and angiogenesis in heart failure remains poorly understood. Silencing strategies that impair microRNA biogenesis have firmly implicated microRNAs in the regulation of angiogenesis, and individual microRNAs prove to be crucial in developmental or tumor angiogenesis. A high-throughput functional screening for the analysis of a whole-genome microRNA silencing library with regard to their phenotypic effect on endothelial cell proliferation as a key parameter, revealed several anti- and pro-proliferative microRNAs. Among those was miR-216a, a pro-angiogenic microRNA which is enriched in cardiac microvascular endothelial cells and reduced in expression under cardiac stress conditions. miR-216a null mice display dramatic cardiac phenotypes related to impaired myocardial vascularization and unbalanced autophagy and inflammation, supporting a model where microRNA regulation of microvascularization impacts the cardiac response to stress.

Cardiomyocyte ZKSCAN3 regulates remodeling following pressure-overload

Autophagy is important for protein and organelle quality control. Growing evidence demonstrates that autophagy is tightly controlled by transcriptional mechanisms, including repression by zinc finger containing KRAB and SCAN domains 3 (ZKSCAN3). We hypothesize that cardiomyocyte-specific ZKSCAN3 knockout (Z3K) disrupts autophagy activation and repression balance and exacerbates cardiac pressure-overload-induced remodeling following transverse aortic constriction (TAC). Indeed, Z3K mice had an enhanced mortality compared to control (Con) mice following TAC. Z3K-TAC mice that survived exhibited a lower body weight compared to Z3K-Sham. Although both Con and Z3K mice exhibited cardiac hypertrophy after TAC, Z3K mice exhibited TAC-induced increase of left ventricular posterior wall thickness at end diastole (LVPWd). Conversely, Con-TAC mice exhibited decreases in PWT%, fractional shortening (FS%), and ejection fraction (EF%). Autophagy genes (Tfeb, Lc3b, and Ctsd) were decreased by the loss of ZKSCAN3. TAC suppressed Zkscan3, Tfeb, Lc3b, and Ctsd in Con mice, but not in Z3K. The Myh6/Myh7 ratio, which is related to cardiac remodeling, was decreased by the loss of ZKSCAN3. Although Ppargc1a mRNA and citrate synthase activities were decreased by TAC in both genotypes, mitochondrial electron transport chain activity did not change. Bi-variant analyses show that while in Con-Sham, the levels of autophagy and cardiac remodeling mRNAs form a strong correlation network, such was disrupted in Con-TAC, Z3K-Sham, and Z3K-TAC. Ppargc1a also forms different links in Con-sham, Con-TAC, Z3K-Sham, and Z3K-TAC. We conclude that ZKSCAN3 in cardiomyocytes reprograms autophagy and cardiac remodeling gene transcription, and their relationships with mitochondrial activities in response to TAC-induced pressure overload.

STIM1 ablation impairs exercise-induced physiological cardiac hypertrophy and dysregulates autophagy in mouse hearts

Cardiac stromal interaction molecule 1 (STIM1), a key mediator of store-operated Ca2+ entry (SOCE), is a known determinant of cardiomyocyte pathological growth in hypertrophic cardiomyopathy. We examined the role of STIM1 and SOCE in response to exercise-dependent physiological hypertrophy. Wild-type (WT) mice subjected to exercise training (WT-Ex) showed a significant increase in exercise capacity and heart weight compared with sedentary (WT-Sed) mice. Moreover, myocytes from WT-Ex hearts displayed an increase in length, but not width, compared with WT-Sed myocytes. Conversely, exercised cardiac-specific STIM1 knock-out mice (cSTIM1KO-Ex), although displaying significant increase in heart weight and cardiac dilation, evidenced no changes in myocyte size and displayed a decreased exercise capacity, impaired cardiac function, and premature death compared with sedentary cardiac-specific STIM1 knock-out mice (cSTIM1KO-Sed). Confocal Ca2+ imaging demonstrated enhanced SOCE in WT-Ex myocytes compared with WT-Sed myocytes with no measurable SOCE detected in cSTIM1KO myocytes. Exercise training induced a significant increase in cardiac phospho-Akt Ser473 in WT mice but not in cSTIM1KO mice. No differences were observed in phosphorylation of mammalian target of rapamycin (mTOR) and glycogen synthase kinase (GSK) in exercised versus sedentary cSTIM1KO mice hearts. cSTIM1KO-Sed mice showed increased basal MAPK phosphorylation compared with WT-Sed that was not altered by exercise training. Finally, histological analysis revealed exercise resulted in increased autophagy in cSTIM1KO but not in WT myocytes. Taken together, our results suggest that adaptive cardiac hypertrophy in response to exercise training involves STIM1-mediated SOCE. Our results demonstrate that STIM1 is involved in and essential for the myocyte longitudinal growth and mTOR activation in response to endurance exercise training.NEW & NOTEWORTHY Store-operated Ca2+ entry (SOCE) has been implicated in pathological cardiac hypertrophy; however, its role in physiological hypertrophy is unknown. Here we report that SOCE is also essential for physiological cardiac hypertrophy and functional adaptations in response to endurance exercise. These adaptations were associated with activation of AKT/mTOR pathway and curtailed cardiac autophagy and degeneration. Thus, SOCE is a common mechanism and an important bifurcation point for signaling paths involved in physiological and pathological hypertrophy.

Activating P2Y1 receptors improves function in arteries with repressed autophagy

AIM

The importance of endothelial cell (EC) autophagy to vascular homeostasis in the context of health and disease is evolving. Earlier, we reported that intact EC autophagy is requisite to maintain shear-stress-induced nitric oxide (NO) generation via glycolysis-dependent purinergic signalling to endothelial NO synthase (eNOS). Here, we illustrate the translational and functional significance of these findings.

METHODS AND RESULTS

First, we assessed translational relevance using older male humans and mice that exhibit blunted EC autophagy and impaired arterial function vs. adult controls. Active hyperaemia evoked by rhythmic handgrip exercise-elevated radial artery shear-rate similarly from baseline in adult and older subjects for 60 min. Compared with baseline, indexes of autophagy initiation, p-eNOSS1177 activation, and NO generation, occurred in radial artery ECs obtained from adult but not older volunteers. Regarding mice, indexes of autophagy and p-eNOSS1177 activation were robust in ECs from adult but not older animals that completed 60-min treadmill-running. Furthermore, 20 dyne • cm2 laminar shear stress × 45-min increased autophagic flux, glycolysis, ATP production, and p-eNOSS1177 in primary arterial ECs obtained from adult but not older mice. Concerning functional relevance, we next questioned whether the inability to initiate EC autophagy, glycolysis, and p-eNOSS1177in vitro precipitates arterial dysfunction ex vivo. Compromised intraluminal flow-mediated vasodilation displayed by arteries from older vs. adult mice was recapitulated in vessels from adult mice by (i) NO synthase inhibition; (ii) acute autophagy impairment using 3-methyladenine (3-MA); (iii) EC Atg3 depletion (iecAtg3KO mice); (iv) purinergic 2Y1-receptor (P2Y1-R) blockade; and (v) germline depletion of P2Y1-Rs. Importantly, P2Y1-R activation using 2-methylthio-ADP (2-Me-ADP) improved vasodilatory capacity in arteries from (i) adult mice treated with 3-MA; (ii) adult iecAtg3KO mice; and (iii) older animals with repressed EC autophagy.

CONCLUSIONS

Arterial dysfunction concurrent with pharmacological, genetic, and age-associated EC autophagy compromise is improved by activating P2Y1-Rs.

Biochemical Mechanisms beyond Glycosphingolipid Accumulation in Fabry Disease: Might They Provide Additional Therapeutic Treatments?

Fabry disease is a rare X-linked disease characterized by deficient expression and activity of alpha-galactosidase A (α-GalA) with consequent lysosomal accumulation of glycosphingolipid in various organs. Currently, enzyme replacement therapy is the cornerstone of the treatment of all Fabry patients, although in the long-term it fails to completely halt the disease's progression. This suggests on one hand that the adverse outcomes cannot be justified only by the lysosomal accumulation of glycosphingolipids and on the other that additional therapies targeted at specific secondary mechanisms might contribute to halt the progression of cardiac, cerebrovascular, and renal disease that occur in Fabry patients. Several studies reported how secondary biochemical processes beyond Gb3 and lyso-Gb3 accumulation-such as oxidative stress, compromised energy metabolism, altered membrane lipid, disturbed cellular trafficking, and impaired autophagy-might exacerbate Fabry disease adverse outcomes. This review aims to summarize the current knowledge of these pathogenetic intracellular mechanisms in Fabry disease, which might suggest novel additional strategies for its treatment.

Chronic intermittent hypoxia-induced BNIP3 expression mitigates contractile dysfunction and myocardial injury in animal and cell model via modulating autophagy

Obstructive sleep apnea syndrome is generally associated with multiple cardiovascular disorders, such as myocardial hypertrophy. Autophagy is strictly modulated to maintain cardiac homeostasis. Post-injury autophagy is closely associated with pathological cardiac hypertrophy. BCL2 interacting protein 3 (BNIP3) and BNIP3-like protein (BNIP3L) can cause cell death and are important for hypoxia-elicited autophagy. Here, we evaluated whether BNIP3 could mitigate functional remodeling and cardiac hypertrophy through regulation of autophagy. Male WT rats or rats with BNIP3 knockout were subjected to chronic intermittent hypoxia (CIH) for 8 h/day over 5 weeks. Echocardiography and morphology were employed to assess the cardioprotective effects. Autophagy was assessed via transmission electron microscopy and detection of LC3, p62, and Beclin-1. Terminal deoxynucleotidyl transferase dUTP nick end labeling and the Bax/Bcl2 ratio were used to monitor apoptosis. Biochemical evaluations were performed to assess oxidative stress. Additionally, BNIP3-knockdown H9c2 cells that were subjected to CIH were used to examine autophagy and apoptosis to confirm the findings of the animal study. The CIH group showed elevated heart weight/body weight and left ventricle weight/body weight proportions, along with left ventricular remodeling. CIH-exposed rats exhibited dramatically higher fractional shortening and ejection fractions than the controls. In addition, the levels of autophagy markers Beclin-1 and LC3-II/I were increased, whereas the level of p62 was reduced by CIH treatment. The oxidative marker levels and the apoptosis index in the CIH group were markedly increased. Knockout of BNIP3 significantly aggravated the impairment in cardiac function, apoptosis, oxidative stress, and hypertrophy of CIH rats, while significantly reducing autophagy. The autophagy-associated PI3K/Akt/mTOR pathway was also deactivated by BNIP3 knockout. At the cellular level, CIH treatment significantly upregulated autophagy and apoptosis; however, BNIP3 silencing reduced autophagy and promoted apoptosis. CIH treatment-mediated upregulation of BNIP3 expression plays a crucial role in autophagy by targeting the PI3K/Akt/mTOR pathway, alleviating cardiac hypertrophy.

Madder (Rubia cordifolia L.) Alleviates Myocardial Ischemia-Reperfusion Injury by Protecting Endothelial Cells from Apoptosis and Inflammation

Objective

Ischemia-reperfusion injury often occurs in organ transplantation, coronary heart disease, ischemic heart disease, and other diseases, which greatly reduces clinical efficacy. This study examined the effectiveness of madder as a medicine to treat ischemia-reperfusion injury.

Methods

The efficacy of madder was evaluated by measuring myocardial infarction size, coronary outflow volume, myocardial contraction rate, activation of inflammatory factors, autophagy factors, apoptosis factors, and related pathway genes in mice.

Results

The results indicated that treatment with madder can effectively reduce the area of myocardial infarction and restore arterial blood flow velocity and myocardial contractility in mice. Additionally, madder treatment inhibited the expression of inflammatory factors, autophagy factors, and apoptosis factors in mice and reduced the degree of myocardial cell injury. Studies have also shown that madder treatment can alleviate myocardial ischemia-reperfusion injury in mice and inhibit the occurrence of inflammatory response by inhibiting the activity of the NF-κB pathway.

Conclusion

The results showed that madder was effective against ischemia-reperfusion injury, thus showing potential as a clinical drug for treating ischemia-reperfusion injury.

The pathophysiological and molecular mechanisms of atmospheric PM2.5 affecting cardiovascular health: A review

BACKGROUND

Exposure to ambient fine particulate matter (PM2.5, with aerodynamic diameter less than 2.5 µm) is a leading environmental risk factor for global cardiovascular health concern.

OBJECTIVE

To provide a roadmap for those new to this field, we reviewed the new insights into the pathophysiological and cellular/molecular mechanisms of PM2.5 responsible for cardiovascular health.

MAIN FINDINGS

PM2.5 is able to disrupt multiple physiological barriers integrity and translocate into the systemic circulation and get access to a range of secondary target organs. An ever-growing body of epidemiological and controlled exposure studies has evidenced a causal relationship between PM2.5 exposure and cardiovascular morbidity and mortality. A variety of cellular and molecular biology mechanisms responsible for the detrimental cardiovascular outcomes attributable to PM2.5 exposure have been described, including metabolic activation, oxidative stress, genotoxicity, inflammation, dysregulation of Ca2+ signaling, disturbance of autophagy, and induction of apoptosis, by which PM2.5 exposure impacts the functions and fates of multiple target cells in cardiovascular system or related organs and further alters a series of pathophysiological processes, such as cardiac autonomic nervous system imbalance, increasing blood pressure, metabolic disorder, accelerated atherosclerosis and plaque vulnerability, platelet aggregation and thrombosis, and disruption in cardiac structure and function, ultimately leading to cardiovascular events and death. Therein, oxidative stress and inflammation were suggested to play pivotal roles in those pathophysiological processes.

CONCLUSION

Those biology mechanisms have deepen insights into the etiology, course, prevention and treatment of this public health concern, although the underlying mechanisms have not yet been entirely clarified.

Titin-truncating variants in hiPSC cardiomyocytes induce pathogenic proteinopathy and sarcomere defects with preserved core contractile machinery

Titin-truncating variants (TTNtv) are the single largest genetic cause of dilated cardiomyopathy (DCM). In this study we modeled disease phenotypes of A-band TTNtv-induced DCM in human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) using genome editing and tissue engineering technologies. Transcriptomic, cellular, and micro-tissue studies revealed that A-band TTNtv hiPSC-CMs exhibit pathogenic proteinopathy, sarcomere defects, aberrant Na⁺ channel activities, and contractile dysfunction. These phenotypes establish a dual mechanism of poison peptide effect and haploinsufficiency that collectively contribute to DCM pathogenesis. However, TTNtv cellular defects did not interfere with the function of the core contractile machinery, the actin-myosin-troponin-Ca²⁺ complex, and preserved the therapeutic mechanism of sarcomere modulators. Treatment of TTNtv cardiac micro-tissues with investigational sarcomere modulators augmented contractility and resulted in sustained transcriptomic changes that promote reversal of DCM disease signatures. Together, our findings elucidate the underlying pathogenic mechanisms of A-band TTNtv-induced DCM and demonstrate the validity of sarcomere modulators as potential therapeutics.

Autophagy and pressure overload-induced cardiac hypertrophy

Autophagy plays an important role in the pathogenesis of cardiovascular diseases. Dysregulation of autophagy may have a huge effect on cardiac hypertrophy induced by overload pressure although reports on autophagy and cardiac hypertrophy have been contradictory. Some studies showed that autophagy activation attenuated cardiac hypertrophy. However, others suggested that inhibition of autophagy would be protective. Different research models or different pathways involved could be responsible for it. Cardiac hypertrophy may be alleviated through regulation of autophagy. This review aims to highlight the pathways and therapeutic targets identified in the prevention and treatment of cardiac hypertrophy by regulating autophagy.

Β-blockers activate autophagy on infantile hemangioma-derived endothelial cells in vitro

The mechanisms underlying the success of propranolol in the treatment of infantile hemangioma (IH) remain elusive and do not fully explain the rapid regression of hemangiomatous lesions following drug administration. As autophagy is critically implicated in vascular homeostasis, we determined whether β-blockers trigger the autophagic flux on infantile hemangioma-derived endothelial cells (Hem-ECs) in vitro.

MATERIAL AND METHODS

Fresh tissue specimens, surgically removed for therapeutic purpose to seven children affected by proliferative IH, were subjected to enzymatic digestion. Cells were sorted with anti-human CD31 immunolabeled magnetic microbeads. Following phenotypic characterization, expanded Hem-ECs, at P2 to P6, were exposed to different concentrations (50 μM to 150 μM) of propranolol, atenolol or metoprolol alone and in combination with the autophagy inhibitor Bafilomycin A1. Rapamycin, a potent inducer of autophagy, was also used as control. Autophagy was assessed by Lysotracker Red staining, western blot analysis of LC3BII/LC3BI and p62, and morphologically by transmission electron microscopy.

RESULTS

Hem-ECs treated with either propranolol, atenolol or metoprolol displayed positive LysoTracker Red staining. Increased LC3BII/LC3BI ratio, as well as p62 modulation, were documented in β-blockers treated Hem-ECs. Abundant autophagic vacuoles and multilamellar bodies characterized the cytoplasmic ultrastructural features of autophagy in cultured Hem-ECs exposed in vitro to β-blocking agents. Importantly, similar biochemical and morphologic evidence of autophagy were observed following rapamycin while Bafilomycin A1 significantly prevented the autophagic flux promoted by β-blockers in Hem-ECs.

CONCLUSION

Our data suggest that autophagy may be ascribed among the mechanisms of action of β-blockers suggesting new mechanistic insights on the potential therapeutic application of this class of drugs in pathologic conditions involving uncontrolled angiogenesis.

Autophagy in health and disease: From molecular mechanisms to therapeutic target

Macroautophagy/autophagy is an evolutionally conserved catabolic process in which cytosolic contents, such as aggregated proteins, dysfunctional organelle, or invading pathogens, are sequestered by the double‐membrane structure termed autophagosome and delivered to lysosome for degradation. Over the past two decades, autophagy has been extensively studied, from the molecular mechanisms, biological functions, implications in various human diseases, to development of autophagy‐related therapeutics. This review will focus on the latest development of autophagy research, covering molecular mechanisms in control of autophagosome biogenesis and autophagosome–lysosome fusion, and the upstream regulatory pathways including the AMPK and MTORC1 pathways. We will also provide a systematic discussion on the implication of autophagy in various human diseases, including cancer, neurodegenerative disorders (Alzheimer disease, Parkinson disease, Huntington's disease, and Amyotrophic lateral sclerosis), metabolic diseases (obesity and diabetes), viral infection especially SARS‐Cov‐2 and COVID‐19, cardiovascular diseases (cardiac ischemia/reperfusion and cardiomyopathy), and aging. Finally, we will also summarize the development of pharmacological agents that have therapeutic potential for clinical applications via targeting the autophagy pathway. It is believed that decades of hard work on autophagy research is eventually to bring real and tangible benefits for improvement of human health and control of human diseases.

Gut microbiota: A new therapeutic target for diabetic cardiomyopathy

Diabetic cardiomyopathy seriously affects quality of life and even threatens life safety of patients. The pathogenesis of diabetic cardiomyopathy is complex and multifactorial, and it is widely accepted that its mechanisms include oxidative stress, inflammation, insulin resistance, apoptosis, and autophagy. Some studies have shown that gut microbiota plays an important role in cardiovascular diseases. Gut microbiota and its metabolites can affect the development of diabetic cardiomyopathy by regulating oxidative stress, inflammation, insulin resistance, apoptosis, and autophagy. Here, the mechanisms of gut microbiota and its metabolites resulting in diabetic cardiomyopathy are reviewed. Gut microbiota may be a new therapeutic target for diabetic cardiomyopathy.

Autophagy-nutrient sensing pathways in diabetic complications

The incidence of diabetes has been increasing in recent decades which is affecting the population of both, developed and developing countries. Diabetes is associated with micro and macrovascular complications which predominantly result from hyperglycemia and disrupted metabolic pathways. Persistent hyperglycemia leads to increased reactive oxygen species (ROS) generation, formation of misfolded and abnormal proteins, and disruption of normal cellular functioning. The inability to maintain metabolic homeostasis under excessive energy and nutrient input, which induces insulin resistance, is a crucial feature during the transition from obesity to diabetes. According to various study reports, redox alterations, intracellular stress and chronic inflammation responses have all been linked to dysregulated energy metabolism and insulin resistance. Autophagy has been considered a cleansing mechanism to prevent these anomalies and restore cellular homeostasis. However, disrupted autophagy has been linked to the pathogenesis of metabolic disorders such as obesity and diabetes. Recent studies have reported that the regulation of autophagy has a beneficial role against these conditions. When there is plenty of food, nutrient-sensing pathways activate anabolism and storage, but the shortage of food activates homeostatic mechanisms like autophagy, which mobilises internal stockpiles. These nutrient-sensing pathways are well conserved in eukaryotes and are involved in the regulation of autophagy which includes SIRT1, mTOR and AMPK. The current review focuses on the role of SIRT1, mTOR and AMPK in regulating autophagy and suggests autophagy along with these nutrient-sensing pathways as potential therapeutic targets in reducing the progression of various diabetic complications.

Pharmacological Targets in Chronic Heart Failure with Reduced Ejection Fraction

Heart failure management has been repeatedly reviewed over time. This strategy has resulted in improved quality of life, especially in patients with heart failure with reduced ejection fraction (HFrEF). It is for this reason that new mechanisms involved in the development and progression of heart failure, along with specific therapies, have been identified. This review focuses on the most recent guidelines of therapeutic interventions, trials that explore novel therapies, and also new molecules that could improve prognosis of different HFrEF phenotypes.

Sodium butyrate attenuates bovine mammary epithelial cell injury by inhibiting the formation of neutrophil extracellular traps

Neutrophil extracellular traps (NETs) are an important means by which the body fights against exogenous bacteria. However, studies have shown that excessive NETs release can damage other cells. Accumulating evidence has shown that butyric acid can alleviate the inflammatory response of cells. However, the effect of butyric acid on Staphylococcus aureus-induced NETs formation and its underlying mechanism are still unclear. In this study, western blotting, immunofluorescence and CCK-8 assays were used to examine the effect of NETs formation by sodium butyrate (NaB). The results showed that NaB suppressed the release of S. aureus-induced NETs formation, as indicated by decreases in the levels of DNA, histones, myeloperoxidase, and neutrophil elastase. S. aureus can induce autophagy, and autophagy plays a key role in the formation of NETs. Our data showed that NaB activated mammalian target of rapamycin (mTOR) and the kinases protein kinase B (AKT) and unc-51 like kinase 1 (ULK1) at Ser757 and inhibited AMP-activated protein kinase (AMPK). To explore whether NaB inhibited the formation of NETs by inhibiting autophagy, we added 3-methyladenine (autophagy inhibitor) (3-MA, 5 mM) to bovine neutrophils, and the results showed that 3-MA significantly inhibited NETs release. Furthermore, we found that NETs and their component histones exhibited significantly increased the cytotoxic effects on bovine mammary epithelial cells (BMECs), indicating that NETs and their component histones play a key role in BMEC damage. In conclusion, NaB can reduce the excessive formation of NETs by inhibiting autophagy, thus reducing the damaging effect of NETs on BMECs.

Aldehyde Dehydrogenase 2 (ALDH2) Elicits Protection against Pulmonary Hypertension via Inhibition of ERK1/2-Mediated Autophagy

Pulmonary hypertension (PH) is caused by chronic hypoxia that induces the migration and proliferation of pulmonary arterial smooth muscle cells (PASMCs), eventually resulting in right heart failure. PH has been related to aberrant autophagy; however, the hidden mechanisms are still unclear. Approximately 40% East Asians, equivalent to 8% of the universal population, carry a mutation in Aldehyde dehydrogenase 2 (ALDH2), which leads to the aggregation of noxious reactive aldehydes and increases the propensity of several diseases. Therefore, we explored the potential aspect of ALDH2 in autophagy associated with PH. In vitro mechanistic studies were conducted in human PASMCs (HPASMCs) after lentiviral ALDH2 knockdown and treatment with platelet-derived growth factor-BB (PDGF-BB). PH was induced in wild-type (WT) and ALDH2-knockout (ALDH2^−/−) mice using vascular endothelial growth factor receptor inhibitor SU5416 under hypoxic conditions (HySU). Right ventricular function was assessed using echocardiography and invasive hemodynamic monitoring. Histological and immunohistochemical analyses were performed to evaluate pulmonary vascular remodeling. EdU, transwell, and wound healing assays were used to evaluate HPASMC migration and proliferation, and electron microscopy and immunohistochemical and immunoblot assays were performed to assess autophagy. The findings demonstrated that ALDH2 deficiency exacerbated right ventricular pressure, hypertrophy, fibrosis, and right heart failure resulting from HySU-induced PH. ALDH2^−/− mice exhibited increased pulmonary artery muscularization and 4-hydroxynonenal (4-HNE) levels in lung tissues. ALDH2 knockdown increased PDGF-BB-induced PASMC migration and proliferation and 4-HNE accumulation in vitro. Additionally, ALDH2 deficiency increased the number of autophagosomes and autophagic lysosomes together with autophagic flux and ERK1/2-Beclin-1 activity in lung tissues and PASMCs, indicating enhanced autophagy. In conclusion, the study shows that ALDH2 has a protective role against the migration and proliferation of PASMCs and PH, possibly by regulating autophagy through the ERK1/2-Beclin-1 pathway.

Endothelial Autophagy in Coronary Microvascular Dysfunction and Cardiovascular Disease

Coronary microvascular dysfunction (CMD) refers to a subset of structural and/or functional disorders of coronary microcirculation that lead to impaired coronary blood flow and eventually myocardial ischemia. Amid the growing knowledge of the pathophysiological mechanisms and the development of advanced tools for assessment, CMD has emerged as a prevalent cause of a broad spectrum of cardiovascular diseases (CVDs), including obstructive and nonobstructive coronary artery disease, diabetic cardiomyopathy, and heart failure with preserved ejection fraction. Of note, the endothelium exerts vital functions in regulating coronary microvascular and cardiac function. Importantly, insufficient or uncontrolled activation of endothelial autophagy facilitates the pathogenesis of CMD in diverse CVDs. Here, we review the progress in understanding the pathophysiological mechanisms of autophagy in coronary endothelial cells and discuss their potential role in CMD and CVDs.

Mitochondrial Dynamics and Mitophagy in Cardiometabolic Disease

Mitochondria play a key role in cellular metabolism. Mitochondrial dynamics (fusion and fission) and mitophagy, are critical to mitochondrial function. Fusion allows organelles to share metabolites, proteins, and mitochondrial DNA, promoting complementarity between damaged mitochondria. Fission increases the number of mitochondria to ensure that they are passed on to their offspring during mitosis. Mitophagy is a process of selective removal of excess or damaged mitochondria that helps improve energy metabolism. Cardiometabolic disease is characterized by mitochondrial dysfunction, high production of reactive oxygen species, increased inflammatory response, and low levels of ATP. Cardiometabolic disease is closely related to mitochondrial dynamics and mitophagy. This paper reviewed the mechanisms of mitochondrial dynamics and mitophagy (focus on MFN1, MFN2, OPA1, DRP1, and PINK1 proteins) and their roles in diabetic cardiomyopathy, myocardial infarction, cardiac hypertrophy, heart failure, atherosclerosis, and obesity.

SUMOylation in peripheral tissues under low perfusion-related pathological states

SUMOylation is described as a posttranslational protein modification (PTM) that is involved in the pathophysiological processes underlying several conditions related to ischemia- and reperfusion-induced damage. Increasing evidence suggests that, under low oxygen levels, SUMOylation might be part of an endogenous mechanism, which is triggered by injury to protect cells within the central nervous system. However, the role of ischemia-induced SUMOylation in the periphery is still unclear. This article summarizes the results of recent studies regarding SUMOylation profiles in several diseases characterized by impaired blood flow to the cardiorenal, gastrointestinal, and respiratory systems. Our review shows that although ischemic injury per se does not always increase SUMOylation levels, as seen in strokes, it seems that in most cases the positive modulation of protein SUMOylation after peripheral ischemia might be a protective mechanism. This complex relationship warrants further investigation, as the role of SUMOylation during hypoxic conditions differs from organ to organ and is still not fully elucidated.