Activator protein-1 and caspase 8 mediate p38α MAPK-dependent cardiomyocyte apoptosis induced by palmitic acid

Apolipoprotein J protects cardiomyocytes from lipid-mediated inflammation and cytotoxicity induced by the epicardial adipose tissue of diabetic patients

Diabetic patients present increased volume and functional alterations in epicardial adipose tissue (EAT). We aimed to analyze EAT from type 2 diabetic patients and the inflammatory and cytotoxic effects induced on cardiomyocytes. Furthermore, we analyzed the cardioprotective role of apolipoprotein J (apoJ). EAT explants were obtained from nondiabetic patients (ND), diabetic patients without coronary disease (DM), and DM patients with coronary disease (DM-C) after heart surgery. Morphological characteristics and gene expression were evaluated. Explants were cultured for 24 h and the content of nonesterified fatty acids (NEFA) and sphingolipid species in secretomes was evaluated by lipidomic analysis. Afterwards, secretomes were added to AC16 human cardiomyocytes for 24 h in the presence or absence of cardioprotective molecules (apoJ and HDL). Cytokine release and apoptosis/necrosis were assessed by ELISA and flow cytometry. The EAT from the diabetic samples showed altered expression of genes related to lipid accumulation, insulin resistance, and inflammation. The secretomes from the DM samples presented an increased ratio of pro/antiatherogenic ceramide (Cer) species, while those from DM-C contained the highest concentration of saturated NEFA. DM and DM-C secretomes promoted inflammation and cytotoxicity on AC16 cardiomyocytes. Exogenous Cer16:0, Cer24:1, and palmitic acid reproduced deleterious effects in AC16 cells. These effects were attenuated by exogenous apoJ. Diabetic secretomes promoted inflammation and cytotoxicity in cardiomyocytes. This effect was exacerbated in the secretomes of the DM-C samples. The increased content of specific NEFA and ceramide species seems to play a key role in inducing such deleterious effects, which are attenuated by apoJ.

Alendronate augments lipid A‑induced IL‑1β release by ASC‑deficient RAW264 cells via AP‑1 activation

Alendronate (ALN) is an anti-bone-resorptive drug with inflammatory side effects. ALN upregulates lipid A-induced interleukin (IL)-1α and IL-1β release by J774.1 cells via apoptosis-associated speck-like protein containing a caspase recruitment domain (ASC) activation. The present study examined whether ALN augmented lipid A-induced proinflammatory cytokine production using ASC-deficient mouse macrophage-like RAW264 cells. Pretreatment of RAW264 cells with ALN significantly augmented lipid A-induced IL-1β release, although ALN did not upregulate the expression of Toll-like receptor 4, myeloid differentiation factor 88 (MyD88) and caspase-11. Moreover, pretreatment of caspase-11-deficient RAW264.7 cells with ALN significantly augmented lipid A-induced IL-1β release. Notably, ALN upregulated the activation of FosB, c-Jun or JunD, but not c-Fos or NF-κB in RAW264 cells. Furthermore, pretreatment with the activator protein 1 (AP-1) inhibitor SR11302, but not the c-Fos inhibitor T-5224, before addition of ALN inhibited ALN-augmented IL-1β release by lipid A-treated RAW264 cells. SR11302 also reduced ALN-augmented lactate dehydrogenase release by the cells. These findings collectively suggested that ALN augmented lipid A-induced IL-1β release and cell membrane damage in ASC-deficient RAW264 cells via activation of AP-1, but not NF-κB.

Effects of Dapagliflozin on Myocardial Gene Expression in BTBR Mice with Type 2 Diabetes

BACKGROUND

Dapagliflozin, a sodium-glucose cotransporter 2 (SGLT2) inhibitor, is approved for the treatment of type 2 diabetes, heart failure, and chronic kidney disease. DAPA-HF and DELIVER trial results demonstrate that the cardiovascular protective effect of dapagliflozin extends to non-diabetic patients. Hence, the mechanism-of-action may extend beyond glucose-lowering and is not completely elucidated. We have previously shown that dapagliflozin reduces cardiac hypertrophy, inflammation, fibrosis, and apoptosis and increases ejection fraction in BTBR mice with type 2 diabetes.

METHODS

We conducted a follow-up RNA-sequencing study on the heart tissue of these animals and performed differential expression and Ingenuity Pathway analysis. Selected markers were confirmed by RT-PCR and Western blot.

RESULTS

SGLT2 had negligible expression in heart tissue. Dapagliflozin improved cardiac metabolism by decreasing glycolysis and pyruvate utilization enzymes, induced antioxidant enzymes, and decreased expression of hypoxia markers. Expression of inflammation, apoptosis, and hypertrophy pathways was decreased. These observations corresponded to the effects of dapagliflozin in the clinical trials.

Thyroid hormone increases fatty acid use in fetal ovine cardiac myocytes

Cardiac metabolic substrate preference shifts at parturition from carbohydrates to fatty acids. We hypothesized that thyroid hormone (T3 ) and palmitic acid (PA) stimulate fetal cardiomyocyte oxidative metabolism capacity. T3 was infused into fetal sheep to a target of 1.5 nM. Dispersed cardiomyocytes were assessed for lipid uptake and droplet formation with BODIPY-labeled fatty acids. Myocardial expression levels were assessed PCR. Cardiomyocytes from naïve fetuses were exposed to T3 and PA, and oxygen consumption was measured with the Seahorse Bioanalyzer. Cardiomyocytes (130-day gestational age) exposed to elevated T3 in utero accumulated 42% more long-chain fatty acid droplets than did cells from vehicle-infused fetuses. In utero T3 increased myocardial mRNA levels of CD36, CPT1A, CPT1B, LCAD, VLCAD, HADH, IDH, PDK4, and caspase 9. In vitro exposure to T3 increased maximal oxygen consumption rate in cultured cardiomyocytes in the absence of fatty acids, and when PA was provided as an acute (30 min) supply of cellular energy. Longer-term exposure (24 and 48 h) to PA abrogated increased oxygen consumption rates stimulated by elevated levels of T3 in cultured cardiomyocytes. T3 contributes to metabolic maturation of fetal cardiomyocytes. Prolonged exposure of fetal cardiomyocytes to PA, however, may impair oxidative capacity.

Exposure to fluoride induces apoptosis in the liver, kidney, and heart of Xenopus laevis by regulating the Caspase-8/3 signaling pathway

Fluoride compounds are abundant and widely distributed in the environment at various concentrations, which can seriously injure the human body. In this study, we aim to evaluate the effects of excessive fluoride exposure on the liver, kidney, and heart tissues of healthy female Xenopus laevis by administering NaF (0, 100, and 200 mg/L) in drinking water for 90 days. The expression level of procaspase-8, cleaved-caspase-8, and procaspase-3 proteins were determined by Western blot. Compared with the control group, the group exposed to NaF exhibited expression levels of procaspase-8, cleaved-caspase-8, and procaspase-3 proteins that were considerably upregulated at a concentration of 200 mg/L in the liver and kidney. The cleaved-caspase-8 protein expression in the group exposed to a high concentration of NaF was lower than that in the control group in heart. Histopathological results by hematoxylin and eosin staining showed that excessive NaF exposure caused necrosis of hepatocytes and vacuolization degeneration. Granular degeneration and necrosis in renal tubular epithelial cells were also observed. Moreover, hypertrophy of myocardial cells, atrophy of myocardial fibers and disorder of myocardial fibers were detected. These results demonstrated that NaF-induced apoptosis and the mediated death receptor pathway activation ultimately damaged the liver and kidney tissues. This finding offers a fresh perspective on the effects of F-induced apoptosis in X. laevis.

Modelling Diabetic Cardiomyopathy: Using Human Stem Cell-Derived Cardiomyocytes to Complement Animal Models

Diabetes is a global epidemic, with cardiovascular disease being the leading cause of death in diabetic patients. There is a pressing need for an in vitro model to aid understanding of the mechanisms driving diabetic heart disease, and to provide an accurate, reliable tool for drug testing. Human induced-pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) have potential as a disease modelling tool. There are several factors that drive molecular changes inside cardiomyocytes contributing to diabetic cardiomyopathy, including hyperglycaemia, lipotoxicity and hyperinsulinemia. Here we discuss these factors and how they can be seen in animal models and utilised in cell culture to mimic the diabetic heart. The use of human iPSC-CMs will allow for a greater understanding of disease pathogenesis and open up new avenues for drug testing.

The Signaling Pathways and Targets of Natural Compounds from Traditional Chinese Medicine in Treating Ischemic Stroke

Ischemic stroke (IS) is a common neurological disorder associated with high disability rates and mortality rates. At present, recombinant tissue plasminogen activator (r-tPA) is the only US(FDA)-approved drug for IS. However, due to the narrow therapeutic window and risk of intracerebral hemorrhage, r-tPA is currently used in less than 5% of stroke patients. Natural compounds have been widely used in the treatment of IS in China and have a wide range of therapeutic effects on IS by regulating multiple targets and signaling pathways. The keywords "ischemia stroke, traditional Chinese Medicine, Chinese herbal medicine, natural compounds" were used to search the relevant literature in PubMed and other databases over the past five years. The results showed that JAK/STAT, NF-κB, MAPK, Notch, Nrf2, and PI3K/Akt are the key pathways, and SIRT1, MMP9, TLR4, HIF-α are the key targets for the natural compounds from traditional Chinese medicine in treating IS. This study aims to update and summarize the signaling pathways and targets of natural compounds in the treatment of IS, and provide a base of information for the future development of effective treatments for IS.

Network pharmacology and RNA-sequencing reveal the molecular mechanism of Xuebijing injection on COVID-19-induced cardiac dysfunction

BACKGROUND

Coronavirus disease 2019 (COVID-19) is an emerging infectious disease caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Up to 20%-30% of patients hospitalized with COVID-19 have evidence of cardiac dysfunction. Xuebijing injection is a compound injection containing five traditional Chinese medicine ingredients, which can protect cells from SARS-CoV-2-induced cell death and improve cardiac function. However, the specific protective mechanism of Xuebijing injection on COVID-19-induced cardiac dysfunction remains unclear.

METHODS

The therapeutic effect of Xuebijing injection on COVID-19 was validated by the TCM Anti COVID-19 (TCMATCOV) platform. RNA-sequencing (RNA-seq) data from GSE150392 was used to find differentially expressed genes (DEGs) from human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) infected with SARS-CoV-2. Data from GSE151879 was used to verify the expression of Angiotensin I Converting Enzyme 2 (ACE2) and central hub genes in both human embryonic-stem-cell-derived cardiomyocytes (hESC-CMs) and adult human CMs with SARS-CoV-2 infection.

RESULTS

A total of 97 proteins were identified as the therapeutic targets of Xuebijing injection for COVID-19. There were 22 DEGs in SARS-CoV-2 infected hiPSC-CMs overlapped with the 97 therapeutic targets, which might be the therapeutic targets of Xuebijing injection on COVID-19-induced cardiac dysfunction. Based on the bioinformatics analysis, 7 genes (CCL2, CXCL8, FOS, IFNB1, IL-1A, IL-1B, SERPINE1) were identified as central hub genes and enriched in pathways including cytokines, inflammation, cell senescence and oxidative stress. ACE2, the receptor of SARS-CoV-2, and the 7 central hub genes were differentially expressed in at least two kinds of SARS-CoV-2 infected CMs. Besides, FOS and quercetin exhibited the tightest binding by molecular docking analysis.

CONCLUSION

Our study indicated the underlying protective effect of Xuebijing injection on COVID-19, especially on COVID19-induced cardiac dysfunction, which provided the theoretical basis for exploring the potential protective mechanism of Xuebijing injection on COVID19-induced cardiac dysfunction.

KIF15 promotes the evolution of gastric cancer cells through inhibition of reactive oxygen species-mediated apoptosis

Kinesin family member 15 (KIF15) is a member of the kinesin superfamily of proteins, which promotes cell mitosis, participates in the transport of intracellular materials, and helps structural assembly and cell signaling pathways transduction. However, its biological role and molecular mechanisms of action in the development of gastric cancer (GC) remain unclear. In the present study, an integrated analysis of The Cancer Genome Atlas (TCGA), Gene Expression Omnibus database, and Kaplan-Meier plotter database was performed to predict the expression and prognostic value of KIF15 in GC patients. Detection of KIF15 expression in GC cells and tissues was performed by a quantitative polymerase chain reaction. In vitro cell proliferation, viability, colony formation ability and flow cytometry assays, and in vivo tumorigenicity assay, were performed to evaluate the effects of KIF15 knockdown on GC cell phenotype. It was demonstrated that the expression of KIF15 messenger RNA in GC tissues was significantly higher compared with that in adjacent tissues, and was closely associated with larger tumor size and poor patient prognosis. In addition, functional studies demonstrated that, due to the increase in reactive oxygen species (ROS) generation, the interference with the expression of KIF15 not only decreased cell proliferation but also increased cell apoptosis and induced cell cycle arrest. ROS-mediated activation of c-Jun N-terminal kinase/c-Jun signaling reduced cell proliferation by regulating the GC cell cycle and increasing apoptosis. Taken together, the results of the present study indicate that KIF15 is an oncoprotein contributing to GC progression, and is expected to help identify novel biomarkers and treatment targets in GC.

Globular CTRP9 protects cardiomyocytes from palmitic acid-induced oxidative stress by enhancing autophagic flux

BACKGROUND

Oxidative stress in cardiac myocytes is an important pathogenesis of cardiac lipotoxicity. Autophagy is a cellular self-digestion process that can selectively remove damaged organelles under oxidative stress, and thus presents a potential therapeutic target against cardiac lipotoxicity. Globular CTRP9 (gCTRP9) is a newly identified adiponectin paralog with established metabolic regulatory properties. The aim of this work is to investigate whether autophagy participates the protection effects of gCTRP9 in neonatal rat cardiac myocytes (NRCMs) under oxidative stress and the underlying mechanism.

RESULTS

NRCMs were treated with PA of various concentrations for indicated time period. Our results showed that PA enhanced intracellular ROS accumulation, decreased mitochondrial membrane potential (Δψm) and increased activation of caspases 3. These changes suggested lipotoxicity due to excessive PA. In addition, PA was observed to impair autophagic flux in NRCMs and impaired autophagosome clearance induced by PA contributes to cardiomyocyte death. Besides, we found that gCTRP9 increased the ratio of LC3II/I and the expression of ATG5 which was vital to the formation of autophagosomes and decreased the level of P62, suggesting enhanced autophagic flux in the absence or presence of PA. The result was further confirmed by the methods of infection with LC3-mRFP-GFP lentivirus and blockage of autophagosome-lysosome fusion by BafA1. Moreover, gCTRP9 reestablished the loss of mitochondrial membrane potential, suppressed ROS generation, and reduced PA -induced myocyte death. However, the protective effect of gCTRP9 on the cardiac lipotoxicity was partly abolished by blockade of autophagy by autophagy-related 5 (ATG5) siRNA, indicating that the effect of gCTRP9 on cell survival is critically mediated through regulation of autophagy.

CONCLUSION

Autophagy induction by gCTRP9 could be utilized as a potential therapeutic strategy against oxidative stress-mediated damage in cardiomyocytes.