GLP1 protects cardiomyocytes from palmitate-induced apoptosis via Akt/GSK3b/b-catenin pathway

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.

Endothelial NOX5 overexpression induces changes in the cardiac gene profile: potential impact in myocardial infarction?

Cardiovascular diseases and the ischemic heart disease specifically constitute the main cause of death worldwide. The ischemic heart disease may lead to myocardial infarction, which in turn triggers numerous mechanisms and pathways involved in cardiac repair and remodeling. Our goal in the present study was to characterize the effect of the NADPH oxidase 5 (NOX5) endothelial expression in healthy and infarcted knock-in mice on diverse signaling pathways. The mechanisms studied in the heart of mice were the redox pathway, metalloproteinases and collagen pathway, signaling factors such as NFκB, AKT or Bcl-2, and adhesion molecules among others. Recent studies support that NOX5 expression in animal models can modify the environment and predisposes organ response to harmful stimuli prior to pathological processes. We found many alterations in the mRNA expression of components involved in cardiac fibrosis as collagen type I or TGF-β and in key players of cardiac apoptosis such as AKT, Bcl-2, or p53. In the heart of NOX5-expressing mice after chronic myocardial infarction, gene alterations were predominant in the redox pathway (NOX2, NOX4, p22phox, or SOD1), but we also found alterations in VCAM-1 and β-MHC expression. Our results suggest that NOX5 endothelial expression in mice preconditions the heart, and we propose that NOX5 has a cardioprotective role. The correlation studies performed between echocardiographic parameters and cardiac mRNA expression supported NOX5 protective action.

Multifaceted Roles of GLP-1 and Its Analogs: A Review on Molecular Mechanisms with a Cardiotherapeutic Perspective

Diabetes is one of the chronic metabolic disorders which poses a multitude of life-debilitating challenges, including cardiac muscle impairment, which eventually results in heart failure. The incretin hormone glucagon-like peptide-1 (GLP-1) has gained distinct recognition in reinstating glucose homeostasis in diabetes, while it is now largely accepted that it has an array of biological effects in the body. Several lines of evidence have revealed that GLP-1 and its analogs possess cardioprotective effects by various mechanisms related to cardiac contractility, myocardial glucose uptake, cardiac oxidative stress and ischemia/reperfusion injury, and mitochondrial homeostasis. Upon binding to GLP-1 receptor (GLP-1R), GLP-1 and its analogs exert their effects via adenylyl cyclase-mediated cAMP elevation and subsequent activation of cAMP-dependent protein kinase(s) which stimulates the insulin release in conjunction with enhanced Ca²⁺ and ATP levels. Recent findings have suggested additional downstream molecular pathways stirred by long-term exposure of GLP-1 analogs, which pave the way for the development of potential therapeutic molecules with longer lasting beneficial effects against diabetic cardiomyopathies. This review provides a comprehensive overview of the recent advances in the understanding of the GLP-1R-dependent and -independent actions of GLP-1 and its analogs in the protection against cardiomyopathies.

WNT/β-catenin pathway is a key regulator of cardiac function and energetic metabolism

The WNT/β-catenin pathway is a master regulator of cardiac development and growth, and its activity is low in healthy adult hearts. However, even this low activity is essential for maintaining normal heart function. Acute activation of the WNT/β-catenin signaling cascade is considered to be cardioprotective after infarction through the upregulation of prosurvival genes and reprogramming of metabolism. Chronically high WNT/β-catenin pathway activity causes profibrotic and hypertrophic effects in the adult heart. New data suggest more complex functions of β-catenin in metabolic maturation of the perinatal heart, establishing an adult pattern of glucose and fatty acid utilization. Additionally, low basal activity of the WNT/β-catenin cascade maintains oxidative metabolism in the adult heart, and this pathway is reactivated by physiological or pathological stimuli to meet the higher energy needs of the heart. This review summarizes the current state of knowledge of the organization of canonical WNT signaling and its function in cardiogenesis, heart maturation, adult heart function, and remodeling. We also discuss the role of the WNT/β-catenin pathway in cardiac glucose, lipid metabolism, and mitochondrial physiology.

Diabetic cardiomyopathy: a brief summary on lipid toxicity

Diabetes mellitus (DM) is a serious epidemic around the globe, and cardiovascular diseases account for the majority of deaths in patients with DM. Diabetic cardiomyopathy (DCM) is defined as a cardiac dysfunction derived from DM without the presence of coronary artery diseases and hypertension. Patients with either type 1 or type 2 DM are at high risk of developing DCM and even heart failure. Metabolic disorders of obesity and insulin resistance in type 2 diabetic environments result in dyslipidaemia and subsequent lipid-induced toxicity (lipotoxicity) in organs including the heart. Although various mechanisms have been proposed underlying DCM, it remains incompletely understood how lipotoxicity alters cardiac function and how DM induces clinical heart syndrome. With recent progress, we here summarize the latest discoveries on lipid-induced cardiac toxicity in diabetic hearts and discuss the underlying therapies and controversies in clinical DCM.

LncRNA FGD5-AS1 reduces cardiomyocyte apoptosis and inflammation by modulating Akt and miR-223-3p expression

OBJECTIVES

Long non-coding RNAs (lncRNAs) are known to be involved in heart development and function. In this study, we aimed to explore the effect of the lncRNA FGD5 antisense RNA 1 (FGD5-AS1) on acute myocardial infarction (AMI) by targeting miR-223-3p.

METHODS

An AMI model was established both in vivo and in vitro. The levels of FGD5-AS1, miR-223-3p and inflammatory factors were detected by real-time quantitative reverse transcription PCR. Cardiomyocyte apoptosis was assessed using TdT-mediated dUTP nick-end labeling assay. The protein levels of cleaved caspase-3, Bcl-2 and Bax were examined using Western blot. Cardiac function was evaluated using hemodynamic analysis and hematoxylin-eosin and Masson's trichrome staining. In addition, an underlying competitive endogenous RNA mechanism was revealed by bioinformatics analysis, dual-luciferase reporter assay and rescue experiments.

RESULTS

We found decreased expression of FGD5-AS1 in AMI. Furthermore, FGD5-AS1 expression significantly decreased the infarct size, improved cardiac performance and attenuated cardiac fibrosis by reducing myocardial apoptosis and inflammation. miR-223-3p was a direct target of FGD5-AS1. Moreover, miRNA-223-3p directly downregulated the expression of phosphorylated Akt in primary neonatal rat cardiomyocytes. Further experiments demonstrated that FGD5-AS1 modulated Akt activity to reduce myocardial injury through miR-223-3p.

CONCLUSION

The FGD5-AS1/miR-223-3p/Akt pathway is involved in AMI, suggesting that FGD5-AS1 may act as a potential biomarker and therapeutic target for AMI.

Glycaemic Control in Patients Undergoing Percutaneous Coronary Intervention: What Is the Role for the Novel Antidiabetic Agents? A Comprehensive Review of Basic Science and Clinical Data

Coronary artery disease (CAD) remains one of the most important causes of morbidity and mortality worldwide, and revascularization through percutaneous coronary interventions (PCI) significantly improves survival. In this setting, poor glycaemic control, regardless of diabetes, has been associated with increased incidence of peri-procedural and long-term complications and worse prognosis. Novel antidiabetic agents have represented a paradigm shift in managing patients with diabetes and cardiovascular diseases. However, limited data are reported so far in patients undergoing coronary stenting. This review intends to provide an overview of the biological mechanisms underlying hyperglycaemia-induced vascular damage and the contrasting actions of new antidiabetic drugs. We summarize existing evidence on the effects of these drugs in the setting of PCI, addressing pre-clinical and clinical studies and drug-drug interactions with antiplatelet agents, thus highlighting new opportunities for optimal long-term management of these patients.

Meta-analysis of cardiovascular outcome trials assessing the impact of glucagon-like peptide-1 receptor agonists on major cardiac arrhythmias

OBJECTIVE

Glucagon-like peptide-1 receptor agonists (GLP-1RAs), a group of novel antidiabetic agents, demonstrated beneficial cardiovascular effects in recent large, placebo-controlled randomised clinical trials (RCTs); their clear antiarrhythmic benefit has not been yet underlined. The purpose of the present meta-analysis is to clarify the impact of GLP-1RAs on different types of cardiac arrhythmias.

METHODS

We searched PubMed from its inception up to 8 October 2020 for all available cardiovascular and renal outcome, placebo-controlled RCTs utilising GLP-1RAs versus placebo. The present meta-analysis is reported according to the Preferred Reporting Items for Systematic reviews and Meta-analyses (PRISMA) statement.

RESULTS

We included data from 7 RCTs with GLP-1RAs in a total of 55,943 participants. Treatment with GLP-1RAs did not provide significant benefit in the risk for atrial fibrillation (RR = 0.81, 95%CI; 0.78-1.15, I² = 51%), atrial flutter (RR = 0.79, 95%CI; 0.53-1.16, I² = 0%), ventricular fibrillation (RR = 0.99, 95%CI; 0.48-2.04, I² = 0%), ventricular tachycardia (RR = 1.41, 95%CI; 0.87-2.28, I² = 10%), atrial tachycardia (RR = 0.63, 95%CI; 0.10-3.90, I² = 24%), sinus node dysfunction (RR = 0.70, 95%CI; 0.40-1.23, I² = 0%), ventricular extrasystoles (RR = 1.37, 95%CI; 0.56-3.30, I² = 0%), second-degree atrioventricular block (RR = 0.96, 95%CI; 0.52-1.74, I² = 0%) or complete atrioventricular block (RR = 0.78, 95%CI; 0.39-1.54, I² = 38%).

CONCLUSIONS

In patients with type 2 diabetes mellitus, treatment with GLP-1RAs does not significantly affect the risk for major cardiac arrhythmias.

miR-141-3p regulates saturated fatty acid-induced cardiomyocyte apoptosis through Notch1/PTEN/AKT pathway via targeting PSEN1

It has been reported that miR-141-3p levels are markedly upregulated in the cardiomyocytes of obese rats induced by a high-fat diet. However, the role of miR-141-3p in myocardial lipotoxicity remains elusive. In the present study, the role of miR-141-3p in lipotoxic injury of H9c2 cells induced by palmitic acid (PA) and its possible mechanisms were assessed. The results indicated that miR-141-3p was significantly upregulated in PA-induced cardiomyocytes. miR-141-3p inhibitor enhanced the cell viability, reduced the release of lactate dehydrogenase (LDH), creatine kinase-MB (CK-MB), and troponin I (CTN-I), decreased cell apoptosis rate, and repressed the activation of mitochondrial apoptosis pathway in PA-treated H9c2, whereas treatment with miR-141-3p mimics resulted in the opposite effects. Mechanistically, it was further revealed that miR-141-3p could specifically bind to presenilin 1 (PSEN1) 3'UTR, and upregulating miR-141-3p levels reduced the expression of PSEN1, thereby inhibiting the activation of the Notch1/PTEN/AKT pathway. Additionally, inhibition of Notch1/AKT signaling pathway by its inhibitor could abrogate the effect of miR-141-3p on mitochondrial-mediated apoptosis induced by PA. In conclusion, the present study demonstrates that miR-141-3p regulates saturated fatty acid-induced cardiomyocyte apoptosis through Notch1/PTEN/AKT pathway via targeting PSEN1, which gains a new insight into the mechanisms of myocardial lipotoxic injury.

A Glucagon-like Peptide 1 Analog Protects Mitochondria and Attenuates Hypoxia-Reoxygenation Injury in Cultured Cardiomyocytes

ABSTRACT

Glucagon-like peptide 1 (GLP-1) analogs improve glycemic control in diabetes and protect the heart against ischemia-reperfusion injury. However, the mechanisms underlying this protection remain unclear. Mitochondria are essential for myocyte homeostasis. Therefore, we herein examined the effects of a GLP-1 analog on mitochondria after the hypoxia-reoxygenation of rat neonatal cultured cardiomyocytes. Cardiomyocytes were subjected to hypoxia for 5 hours followed by reoxygenation for 30 minutes in the presence or absence of exendin-4 (50 nmol/L), a GLP-1 analog. Hypoxia-reoxygenation increased lactate dehydrogenase and caspase-3 activities, indicators of lethal myocyte injury and apoptosis, respectively, and exendin-4 attenuated these increases. The content of ATP in myocytes decreased after hypoxia-reoxygenation but was preserved by exendin-4. The membrane potential and shape of mitochondria were assessed using a fluorescent probe. Exendin-4 attenuated the hypoxia-reoxygenation-induced disruption of the mitochondrial membrane potential and shortening. Mitochondrial quality control-related factors, such as optic atrophy protein 1, mitofusin 2, dynamin-related protein 1, and parkin, were examined by Western blotting. Exendin-4 significantly increased the expression of the fusion proteins, optic atrophy protein 1 and mitofusin 2, and decreased that of the mitophagy-related protein, parkin, without altering dynamin-related protein 1 expression levels. Exendin-4 also preserved Akt phosphorylation levels after hypoxia-reoxygenation, whereas wortmannin, an inhibitor of the phosphoinositide 3-kinase-Akt pathway, blunted exendin-4-induced myocyte protection and its effects on mitochondrial quality control factors. In conclusion, exendin-4 protected mitochondria by preserving the phosphorylation of Akt and fusion proteins, leading to the attenuation of hypoxia-reoxygenation-induced injury in cultured myocytes.

Protocatechuic aldehyde protects cardiomycoytes against ischemic injury via regulation of nuclear pyruvate kinase M2

Rescuing cells from stress damage emerges a potential therapeutic strategy to combat myocardial infarction. Protocatechuic aldehyde (PCA) is a major phenolic acid in Chinese herb Danshen (Salvia miltiorrhiza root). This study investigated whether PCA regulated nuclear pyruvate kinase isoform M2 (PKM2) function to protect cardiomyocytes. In rats subjected to isoprenaline, PCA attenuated heart injury and protected cardiomyocytes from apoptosis. Through DARTS and CETSA assays, we identified that PCA bound and promoted PKM2 nuclear translocation in cardiomyocytes exposed to oxygen/glucose deprivation (OGD). In the nucleus, PCA increased the binding of PKM2 to β-catenin via preserving PKM2 acetylation, and the complex, in cooperation with T-cell factor 4 (TCF4), was required for transcriptional induction of genes encoding anti-apoptotic proteins, contributing to rescuing cardiomyocyte survival. In addition, PCA ameliorated mitochondrial dysfunction and prevented mitochondrial apoptosis dependent on PKM2. Consistently, PCA increased the binding of PKM2 to β-catenin, improved heart contractive function, normalized heart structure and attenuated oxidative damage in mice subjected to artery ligation, but the protective effects were lost in Pkm2-deficient heart. Together, we showed that PCA regulated nuclear PKM2 function to rescue cardiomyocyte survival via β-catenin/TCF4 signaling cascade, suggesting the potential of pharmacological intervention of PKM2 shuttle to protect the heart.

CD36 Signaling in Diabetic Cardiomyopathy

Cluster of differentiation 36 (CD36), also referred to as scavenger receptor B2, has been shown to serve multiple functions in lipid metabolism, inflammatory signaling, oxidative stress, and energy reprogramming. As a scavenger receptor, CD36 interacts with various ligands, such as oxidized low-density lipoprotein (oxLDL), thrombospondin 1 (TSP-1), and fatty acid (FA), thereby activating specific downstream signaling pathways. Cardiac CD36 is mostly expressed on the surface of cardiomyocytes and endothelial cells. The pathophysiological process of diabetic cardiomyopathy (DCM) encompasses diverse metabolic abnormalities, such as enhanced transfer of cardiac myocyte sarcolemmal FA, increased levels of advanced glycation end-products, elevation in oxidative stress, impaired insulin signaling cascade, disturbance in calcium handling, and microvascular rarefaction which are closely related to CD36 signaling. This review presents a summary of the CD36 signaling pathway that acts mainly as a long-chain FA transporter in cardiac myocytes and functions as a receptor to bind to numerous ligands in endothelial cells. Finally, we summarize the recent basic research and clinical findings regarding CD36 signaling in DCM, suggesting a promising strategy to treat this condition.

Liraglutide improves lipid and carbohydrate metabolism of ovariectomized rats

Considering that post-menopausal women and ovariectomized rodents develop obesity associated with increased visceral fat, this study was developed to investigate if liraglutide, a glucagon-like peptide 1 (GLP1) analogue, could improve the metabolism of estrogen (E2) deficient females. Wistar rats were ovariectomized (OVX), and subdivided in four groups: sham saline, sham liraglutide, OVX saline, and OVX liraglutide. After sixty days, metabolic parameters of blood, heart, liver, brown (BAT) and white adipose tissue (WAT) visceral depots, and, heart oxidative homeostasis, were evaluated. Castration increased the animals' body weight, the relative weight of the WAT depots, hepatic triglycerides and cardiac glycogen content. Liraglutide treatment reversed these effects, decreased WAT depots weight and increased glucose oxidation and lipogenesis in BAT and WAT. In addition, liraglutide enhanced adrenalin (A) lipolytic effect. These results indicate that liraglutide may be a promising treatment to restore lipid homeostasis and prevent weight gain associated with E2 deficiency.

Liraglutide Protects Nucleus Pulposus Cells Against High-Glucose Induced Apoptosis by Activating PI3K/Akt/ mTOR/Caspase-3 and PI3K/Akt/GSK3β/Caspase-3 Signaling Pathways

Background and Objective: Diabetes mellitus (DM) is reportedly a significant risk factor for intervertebral disc degeneration (IDD). Incretin system and particularly glucagon-like peptide 1 (GLP-1) because of its glucose-lowering effects has become an important target in therapeutic strategies of type 2 diabetes (T2D). Liraglutide is a GLP-1 receptor (GLP-1R) agonist with glucoregulatory and insulinotropic functions as well as regulatory functions on cell proliferation, differentiation, and apoptosis. However, little is known on the roles and signaling pathways of apoptosis protecting effects of liraglutide in IDD. This study aimed to investigate the potential protective effects of liraglutide against high glucose-induced apoptosis of nucleus pulposus cells (NPCs) and the possible involved signaling pathways.

Methods: The human NPCs were incubated with 100 nM liraglutide alone or in combination with LY294002 (PI3K inhibitor), rapamycin (mTOR inhibitor), and SB216763 (GSK3β inhibitor) in a high glucose culture for 48 h. The four groups were assessed further for apoptosis and genes expressions. The apoptotic effect was evaluated by flow cytometry and further confirmed by cell death detection enzyme-linked immunoassay plus (ELISAPLUS). The gene and protein expression levels were assessed by quantitative real-time polymerase chain reaction (qRT-PCR) and Western blotting techniques. The results were comparatively assessed between the four groups.

Results: The results confirmed the presence of GLP-1R in the NPCs indicating that liraglutide inhibited the high glucose-induced apoptosis, which was blocked by silencing GLP-1R with siRNA. Moreover, liraglutide stimulated the phosphorylation of Akt, mTOR and GSK3β. Treatment with LY294002 significantly increased the apoptosis of NPCs and reduced the levels of their downstream substrates (p-AKT, p-mTOR, and p-GSK3β). Further assessments revealed that activation of mTOR and GSK3β was almost completely inhibited by rapamycin and SB216763, respectively, which significantly increased the caspase-3 levels.

Conclusion: Liraglutide could protect NPCs against high glucose-induced apoptosis by activating the PI3K/AKT/mTOR/caspase-3 and PI3K/AKT/GSK3β/caspase-3 signaling pathways.

Irisin and Incretin Hormones: Similarities, Differences, and Implications in Type 2 Diabetes and Obesity

Incretins are gut hormones that potentiate glucose-stimulated insulin secretion (GSIS) after meals. Glucagon-like peptide-1 (GLP-1) is the most investigated incretin hormone, synthesized mainly by L cells in the lower gut tract. GLP-1 promotes β-cell function and survival and exerts beneficial effects in different organs and tissues. Irisin, a myokine released in response to a high-fat diet and exercise, enhances GSIS. Similar to GLP-1, irisin augments insulin biosynthesis and promotes accrual of β-cell functional mass. In addition, irisin and GLP-1 share comparable pleiotropic effects and activate similar intracellular pathways. The insulinotropic and extra-pancreatic effects of GLP-1 are reduced in type 2 diabetes (T2D) patients but preserved at pharmacological doses. GLP-1 receptor agonists (GLP-1RAs) are therefore among the most widely used antidiabetes drugs, also considered for their cardiovascular benefits and ability to promote weight loss. Irisin levels are lower in T2D patients, and in diabetic and/or obese animal models irisin administration improves glycemic control and promotes weight loss. Interestingly, recent evidence suggests that both GLP-1 and irisin are also synthesized within the pancreatic islets, in α- and β-cells, respectively. This review aims to describe the similarities between GLP-1 and irisin and to propose a new potential axis-involving the gut, muscle, and endocrine pancreas that controls energy homeostasis.

Downregulation of microRNA-15b-5p Targeting the Akt3-Mediated GSK-3β/β-Catenin Signaling Pathway Inhibits Cell Apoptosis in Parkinson's Disease

Parkinson's disease (PD) is an incurable progressive disorder resulting from neurodegeneration, and apoptosis is considered a dominant mechanism underlying the process of neurodegeneration. MicroRNAs (miRNAs), which are small and noncoding RNAs involved in many a biological process like apoptosis and regulation of gene expressions, have been found in postmortem brain samples of patients with PD, as well as in vitro and in vivo models of PD. To explore the impact of miR-15b-5p and Akt3 on apoptosis in the progression of PD, the method of quantitative reverse transcription polymerase chain reaction (qRT-PCR) was employed, and the analysis result showed upregulated expression of miR-15b-5p and downregulated expression of Akt3 in the serum of PD patients, MPP+-induced SH-SY5Y cells, and the brain tissues of MPTP-induced mice. Meanwhile, the dual-luciferase reporter assay was used to demonstrate the regulator-target interaction between miR-15b-5p and Akt3; flow cytometry and spectrophotometry revealed that transfection of miR-15b-5p mimic and si-Akt3 increased the rate of apoptosis and caspase-3 activity, whereas transfecting the miR-15b-5p inhibitor and Akt3-overexpression plasmid repressed the rate of apoptosis and caspase-3 activity in the MPP+-induced SH-SY5Y cell model and the MPTP-induced mouse model. Additionally, analysis of western blotting (WB) assays in vivo and in vitro revealed that proapoptosis proteins (Bax, caspase-3, GSK-3β, and β-catenin) showed markedly upregulated expression in the miR-15b-5p inhibitor and si-Akt3-overexpression groups, while the expression of an antiapoptosis gene (i.e., Bcl2) was downregulated. These analysis results indicate that downregulation of miR-15b-5p by targeting the Akt3-mediated GSK-3β/β-catenin signaling pathway would repress cell apoptosis in PD in vivo and in vitro. It is expected that the research findings would help find new therapeutic targets for treatment of PD.

SGLT2i and GLP-1RA in Cardiometabolic and Renal Diseases: From Glycemic Control to Adipose Tissue Inflammation and Senescence

Background. Over the last few years, the use of sodium-glucose cotransporter 2 inhibitors (SGLT2i) and glucagon-like peptide 1 receptor agonists (GLP-1RA) has increased substantially in medical practice due to their documented benefits in cardiorenal and metabolic health. In this sense, and in addition to being used for glycemic control in diabetic patients, these drugs also have other favorable effects such as weight loss and lowering blood pressure, and more recently, they have been shown to have cardio and renoprotective effects with anti-inflammatory properties. Concerning the latter, the individual or associated use of these antihyperglycemic agents has been linked with a decrease in proinflammatory cytokines and with an improvement in the inflammatory profile in chronic endocrine-metabolic diseases. Hence, these drugs have been positioned as first-line therapy in the management of diabetes and its multiple comorbidities, such as obesity, which has been associated with persistent inflammatory states that induce dysfunction of the adipose tissue. Moreover, other frequent comorbidities in long-standing diabetic patients are chronic complications such as diabetic kidney disease, whose progression can be slowed by SGLT2i and/or GLP-1RA. The neuroendocrine and immunometabolism mechanisms underlying adipose tissue inflammation in individuals with diabetes and cardiometabolic and renal diseases are complex and not fully understood. Summary. This review intends to expose the probable molecular mechanisms and compile evidence of the synergistic or additive anti-inflammatory effects of SGLT2i and GLP-1RA and their potential impact on the management of patients with obesity and cardiorenal compromise.

Environmentally Self-Adaptative Nanocarriers Suppress Glioma Proliferation and Stemness via Codelivery of shCD163 and Doxorubicin

Gliomas-devastating intracranial tumors with a dismal outcome-are in dire need of innovative treatment. Although nanodrugs have been utilized as a target therapy for certain types of solid tumors, their therapeutic effects in gliomas are limited due to the complications of the systemic circulation, blood-brain barrier (BBB), and specific glioma environment. Thus, we aimed to establish a nanoliposome adaptable to different environments by codelivery of shCD163 and doxorubicin (DOX) to treat gliomas. In this study, we first synthesized pH-sensitive DSPE-cRGD-Hz-PEG₂₀₀₀ to form an environmentally self-adaptative nanoliposome (cRGD-DDD Lip) via a thin film method. We used in vitro BBB models, in vitro cell uptake experiments, and in vivo biodistribution assays to confirm the long circulation time and low cell uptake of the cRGD-DDD Lip as a result of the poly(ethylene glycol) (PEG) shell of cRGD-DDD Lip in the neutral pH systemic circulation. Moreover, the cRGD-DDD Lip bypassed the BBB and attached to the intracranial glioma following the removal of the PEG shell and the exposure of cRGD to the weakly acidic tumor microenvironment. We further assembled the shCD163/DOX@cRGD-DDD Lip through cRGD-DDD Lip loading of shCD163 and DOX. In vitro, cell proliferation and self-renewal of glioma cells were inhibited by the shCD163/DOX@cRGD-DDD Lip due to the toxicity of DOX and the suppression of shCD163 via the CD163 pathway. In vivo, the shCD163/DOX@cRGD-DDD Lip disturbed the progression of in situ gliomas by inhibiting the growth and stemness of glioma cells and prevented the recurrence of gliomas after resection. In conclusion, the cRGD-DDD Lip may be a promising nanodrug-loading platform to cope with different environments and the shCD163/DOX@cRGD-DDD Lip may potentially be a novel nanodrug for glioma therapy.

Repurposing Antidiabetic Drugs for Cardiovascular Disease

Metabolic diseases and diabetes represent an increasing global challenge for human health care. As associated with a strongly elevated risk of developing atherosclerosis, kidney failure and death from myocardial infarction or stroke, the treatment of diabetes requires a more effective approach than lowering blood glucose levels. This review summarizes the evidence for the cardioprotective benefits induced by antidiabetic agents, including sodium-glucose cotransporter 2 inhibitor (SGLT2i) and glucagon-like peptide-1 receptor agonist (GLP1-RA), along with sometimes conversely discussed effects of dipeptidyl peptidase-4 inhibitor (DPP4i) and metformin in patients with high cardiovascular risk with or without type 2 diabetes. Moreover, the proposed mechanisms of the different drugs are described based on the results of preclinical studies. Recent cardiovascular outcome trials unexpectedly confirmed a beneficial effect of GLP-1RA and SGLT2i in type 2 diabetes patients with high cardiovascular risk and with standard care, which was independent of glycaemic control. These results triggered a plethora of studies to clarify the underlying mechanisms and the relevance of these effects. Taken together, the available data strongly highlight the potential of repurposing the original antidiabetics GLP1-RA and SGLT2i to improve cardiovascular outcome even in non-diabetic patients with cardiovascular diseases.

The Multifunctionality of CD36 in Diabetes Mellitus and Its Complications-Update in Pathogenesis, Treatment and Monitoring

CD36 is a multiligand receptor contributing to glucose and lipid metabolism, immune response, inflammation, thrombosis, and fibrosis. A wide range of tissue expression includes cells sensitive to metabolic abnormalities associated with metabolic syndrome and diabetes mellitus (DM), such as monocytes and macrophages, epithelial cells, adipocytes, hepatocytes, skeletal and cardiac myocytes, pancreatic β-cells, kidney glomeruli and tubules cells, pericytes and pigment epithelium cells of the retina, and Schwann cells. These features make CD36 an important component of the pathogenesis of DM and its complications, but also a promising target in the treatment of these disorders. The detrimental effects of CD36 signaling are mediated by the uptake of fatty acids and modified lipoproteins, deposition of lipids and their lipotoxicity, alterations in insulin response and the utilization of energy substrates, oxidative stress, inflammation, apoptosis, and fibrosis leading to the progressive, often irreversible organ dysfunction. This review summarizes the extensive knowledge of the contribution of CD36 to DM and its complications, including nephropathy, retinopathy, peripheral neuropathy, and cardiomyopathy.

Taurine with combined aerobic and resistance exercise training alleviates myocardium apoptosis in STZ-induced diabetes rats via Akt signaling pathway

AIM

The aim of this study was considering the effects of taurine supplementation with combined aerobic and resistance training (CARE) on myocardial apoptosis and Protein Kinase B (akt) level changes in diabetic rat.

MAIN METHODS

Forty male Wistar rats were randomly divided in to 5 groups of 8 animals in each: 1) control, 2) Diabetes Mellitus (DM), 3) DM with taurine supplementation (DM/T), 4) DM with CARE (DM/CARE), and 5) DM with combination of taurine and CARE (DM/T/CARE). DM was induced by injection of streptozotocin (STZ) and nicotine amid (NA) for 2, 3, 4 and 5 groups. Supplement groups received taurine in gavage, 100 mg/kg of body weight, 6 day per weeks, 8 weeks. CARE was performed at maximal speed and 1RM (40-60% of maximum for both).

KEY FINDINGS

The results of this study showed that DM significantly increased blood glucose and caspase 3, caspase 9 expressions and apoptosis cells in heart tissue and reduced Akt expression (p < 0.001). However, taurine and CARE interventions significantly decreased apoptosis markers (caspase 3 and caspase 9) and significantly increased Akt in heart of diabetic rats compare to DM groups (p < 0.05). The highest improvement observed in DM/T/CARE group (p < 0.05).

SIGNIFICANCE

Based on these results, it seems that the use of taurine with combined aerobic and exercise training minimize the cardiac damage caused by diabetes (especially apoptosis) trough increasing protein kinase Akt expression. This could improve cardiac remodeling after diabetes. However, more research is needed, especially on the human samples.

Metabolic and cardiovascular benefits of GLP-1 agonists, besides the hypoglycemic effect (Review)

Patients with type 2 diabetes exhibit higher cardiovascular risk than normal individuals. Optimal blood glucose levels are rarely achieved in diabetic patients. Glucagon-like peptide-1 receptor agonists (GLP-1 RAs) have emerged as a new antidiabetic drug class with multiple metabolic effects. Some trials have evaluated their safety, but it has been recently demonstrated that this new class has cardiovascular benefits, through other mechanisms than glycemic control. The use of GLP-1RAs was associated with a significant reduction of cardiovascular and all-cause mortality, with a safe profile related to pancreatitis or thyroid cancer, as compared with placebo. This review presents the cardiovascular and metabolic benefits of GLP-1 RAs versus placebo, in patients with type 2 diabetes. Semaglutide and liraglutide demonstrated a reduction in cardiovascular events, with similar rates on cardiovascular mortality. Ongoing trials assess the cardiovascular benefits and side effects of dulaglutide treatment. Exenatide and liraglutide demonstrated the decrease of blood pressure values, weight reduction and improvement of dyslipidemia. Liraglutide induced, both in vivo and in vitro, an improvement of blood circulation, increasing the nitric oxide level and inhibiting the adhesion and procoagulant factors. Also, liraglutide demonstrated beneficial effects on cardiac remodeling after myocardial infarction, but more large trials are required. However, the international guidelines recommend using GLP-1 RAs as first-line therapy in type 2 diabetes patients with high cardiovascular risk or as first-line agents in patients intolerant to metformin.

Human-induced pluripotent stem cells for modelling metabolic perturbations and impaired bioenergetics underlying cardiomyopathies

Normal cardiac contractile and relaxation functions are critically dependent on a continuous energy supply. Accordingly, metabolic perturbations and impaired mitochondrial bioenergetics with subsequent disruption of ATP production underpin a wide variety of cardiac diseases, including diabetic cardiomyopathy, dilated cardiomyopathy, hypertrophic cardiomyopathy, anthracycline cardiomyopathy, peripartum cardiomyopathy, and mitochondrial cardiomyopathies. Crucially, there are no specific treatments for preventing the onset or progression of these cardiomyopathies to heart failure, one of the leading causes of death and disability worldwide. Therefore, new treatments are needed to target the metabolic disturbances and impaired mitochondrial bioenergetics underlying these cardiomyopathies in order to improve health outcomes in these patients. However, investigation of the underlying mechanisms and the identification of novel therapeutic targets have been hampered by the lack of appropriate animal disease models. Furthermore, interspecies variation precludes the use of animal models for studying certain disorders, whereas patient-derived primary cell lines have limited lifespan and availability. Fortunately, the discovery of human-induced pluripotent stem cells has provided a promising tool for modelling cardiomyopathies via human heart tissue in a dish. In this review article, we highlight the use of patient-derived iPSCs for studying the pathogenesis underlying cardiomyopathies associated with metabolic perturbations and impaired mitochondrial bioenergetics, as the ability of iPSCs for self-renewal and differentiation makes them an ideal platform for investigating disease pathogenesis in a controlled in vitro environment. Continuing progress will help elucidate novel mechanistic pathways, and discover novel therapies for preventing the onset and progression of heart failure, thereby advancing a new era of personalized therapeutics for improving health outcomes in patients with cardiomyopathy.

Preventive Effects of Dulaglutide on Disuse Muscle Atrophy Through Inhibition of Inflammation and Apoptosis by Induction of Hsp72 Expression

Pathological conditions such as joint immobilization, long-time bed rest, or inactivity may result in disuse-induced muscle wasting and dysfunction. To investigate the effect of dulaglutide, a long-acting glucagon-like peptide-1 receptor agonist, on disuse muscle atrophy, disuse condition was induced by spiral wire immobilization in C57BL/6 mice and the mice were treated with dulaglutide. Dulaglutide treatment effectively improved muscle function and increased muscle mass compared with vehicle treatment. Dulaglutide inhibited the decrease of muscle fiber size and the expression of atrophic factors such as myostatin, atrogin-1/MAFbx, and muscle RING-finger protein-1 in immobilized mice. In addition, dulaglutide inhibited nuclear factor kappa B activation, leading to a decrease in the mRNA levels of proinflammatory cytokines, including tumor necrosis factor-α, interleukin (IL)-1β, and IL-6 in muscle of immobilized mice. Dulaglutide suppressed the expression of apoptotic markers such as caspase-3, cleaved poly-ADP ribose polymerase, and Bax under immobilization condition and increased the expression of heat shock protein 72 (Hsp72), which is related to the amelioration of inflammation and apoptosis during disuse time. Further study showed that dulaglutide could induce Hsp72 expression via the regulation of 5′-AMP-activated protein kinase signaling. Our data suggest that dulaglutide could exert beneficial effects against disuse-induced muscle atrophy.

Application quantitative proteomics approach to identify differentially expressed proteins associated with cardiac protection mediated by cycloastragenol in acute myocardial infarction rats

Acute myocardial infarction (AMI) is an acute heart disease. Cycloastragenol, as a natural product, inhibits inflammation and protects cardiomyocytes. Cycloastragenol (Y006) modulates inflammation in AMI is not known. To explore the function of Cycloastragenol in AMI, this study investigated the effect of Y006 and its mechanisms both in vitro and in vivo. Y006 influences the concentration of 11 proteins, as shown by a proteomics analysis, immunohistochemistry and western blotting. Among these 11 proteins, Erk1/2, PLCG1, IKBKG, and ZEB1 are related to inflammatory regulation. BAX, COX2, and GSK3β are involved in modulating cardiomyocyte apoptosis, and RhoA and DSC2 are directly associated with myocardial function. However, the functions of ARHGAP17 and Rit2 in heart are less well established. Additionally, Y006 suppressed TNF-α, IFN-γ and IL-17 production in PBMCs (peripheral blood monocytes) from patients with acute myocardial infarction and enhanced IL-10 and IL-4 expression. Similar results were obtained in a rat model of AMI by flow cytometry detection and ELISA. Our findings indicate that Y006 protects rats from AMI through direct or indirect inhibition of inflammation and cardiomyocyte apoptosis. However, the specific mechanism of Y006's protective function requires further study. Nonetheless, this research revealed a novel aspect for the treatment of myocardial infarction. SIGNIFICANCE: In the present study, we undertook the first proteomic evaluation of Cycloastragenol (Y006) function in acute myocardial infarction (AMI). Y006 significantly improved myocardial function in vivo by regulating multiple molecular expressions. Hypoxia is a direct reason for AMI. And our data support a role of Y006 in gene expression, cell apoptosis under hypoxia. The conclusions of this research assist to explain the potential molecular mechanism in Cycloastragenol treating AMI and supply a new method for ameliorating AMI.

AQP1 suppression by ATF4 triggers trabecular meshwork tissue remodelling in ET-1-induced POAG

Primary open‐angle glaucoma (POAG) is the second leading cause of irreversible blindness worldwide. Increased endothelin‐1 (ET‐1) has been observed in aqueous humour (AH) of POAG patients, resulting in an increase in the out‐flow resistance of the AH. However, the underlining mechanisms remain elusive. Using established in vivo and in vitro POAG models, we demonstrated that water channel Aquaporin 1 (AQP1) is down‐regulated in trabecular meshwork (TM) cells upon ET‐1 exposure, which causes a series of glaucomatous changes, including actin fibre reorganization, collagen production, extracellular matrix deposition and contractility alteration of TM cells. Ectopic expression of AQP1 can reverse ET‐1‐induced TM tissue remodelling, which requires the presence of β‐catenin. More importantly, we found that ET‐1‐induced AQP1 suppression is mediated by ATF4, a transcription factor of the unfolded protein response, which binds to the promoter of AQP1 and negatively regulates AQP1 transcription. Thus, we discovered a novel function of ATF4 in controlling the process of TM remodelling in ET‐1‐induced POAG through transcription suppression of AQP1. Our findings also detail a novel pathological mechanism and a potential therapeutic target for POAG.

PBX homeobox 1 enhances hair follicle mesenchymal stem cell proliferation and reprogramming through activation of the AKT/glycogen synthase kinase signaling pathway and suppression of apoptosis

BACKGROUND

PBX homeobox 1 (PBX1) is involved in the maintenance of the pluripotency of human embryonic and hematopoietic stem cells; however, the effects of PBX1 in the self-renewal and reprogramming of hair follicle mesenchymal stem cells (HF-MSCs) are unclear. The AKT/glycogen synthase kinase (GSK) 3β pathway regulates cell metabolism, proliferation, apoptosis, and reprogramming, and p16 and p21, which act downstream of this pathway, regulate cell proliferation, cell cycle, and apoptosis induced by reprogramming. Here, we aimed to elucidate the roles of PBX1 in regulating the proliferation and reprogramming of HF-MSCs.

METHODS

A lentiviral vector designed to carry the PBX1 sequence or PBX1 short hairpin RNA sequence was used to overexpress or knock down PBX1. The roles of PBX1 in proliferation and apoptosis were investigated by flow cytometry. Real-time polymerase chain reaction was performed to evaluate pluripotent gene expression. Dual-luciferase reporter assays were performed to examine the transcriptional activity of the NANOG promoter. Western blotting was performed to identify the molecules downstream of PBX1 involved in proliferation and reprogramming. Caspase3 activity was detected to assess HF-MSC reprogramming. The phosphatidylinositol 3-kinase/AKT inhibitor LY294002 was used to inhibit the phosphorylation and activity of AKT.

RESULTS

Overexpression of PBX1 in HF-MSCs increased the phosphorylation of AKT and nuclear translocation of β-catenin, resulting in the progression of the cell cycle from G0/G1 to S phase. Moreover, transfection with a combination of five transcription factors (SOMKP) in HF-MSCs enhanced the formation of alkaline phosphatase-stained colonies compared with that in HF-MSCs transfected with a combination of four transcription factors (SOMK). PBX1 upregulated Nanog transcription by activating the promoter and promoted the expression of endogenous SOX2 and OCT4. Furthermore, PBX1 expression activated the AKT/glycogen synthase kinase (GSK) 3β pathway and reduced apoptosis during the early stages of reprogramming. Inhibition of phospho-AKT or knockdown of PBX1 promoted mitochondrion-mediated apoptosis and reduced reprogramming efficiency.

CONCLUSIONS

PBX1 enhanced HF-MSC proliferation, and HF-MSCs induced pluripotent stem cells (iPSC) generation by activating the AKT/GSK3β signaling pathway. During the reprogramming of HF-MSCs into HF-iPSCs, PBX1 activated the NANOG promoter, upregulated NANOG, and inhibited mitochondrion-mediated apoptosis via the AKT/GSK3β pathway during the early stages of reprogramming.

Liraglutide inhibits the apoptosis of human nucleus pulposus cells induced by high glucose through PI3K/Akt/caspase-3 signaling pathway

Diabetes mellitus (DM) is a potential etiology of disc degeneration. Glucagon-like peptide-1 (GLP-1) is currently regarded as a powerful treatment option for type 2 diabetes. Apart from the beneficial effects on glycaemic control, GLP-1 has been reported to exert functions in a variety of tissues on modulation of cell proliferation, differentiation, and apoptosis. However, little is known regarding the effects of GLP-1 on nucleus pulposus cells (NPCs). In the present study, we investigated the effects of liraglutide (LIR), a long-lasting GLP-1 analogue, on apoptosis of human NPCs and the underlying mechanisms involved. We confirmed the presence of GLP-1 receptor (GLP-1R) in NPCs. Our data demonstrated that liraglutide inhibited the apoptosis of NPCs induced by high glucose (HG), as detected by Annexin V/Propidium Iodide (PI) and ELISA assays. Moreover, liraglutide down-regulated caspase-3 activity at intermediate concentration (100 nM) for maximum effect. Further analysis suggested that liraglutide suppressed reactive oxygen species (ROS) generation and stimulated the phosphorylation of Akt under HG condition. Pretreatment of cells with the Phosphoinositide 3-kinase (PI3K) inhibitor LY294002 (LY) and small interfering RNAs (siRNAs) GLP-1R abrogated the liraglutide-induced activation of Akt and the protective effects on NPCs' apoptosis. In conclusion, liraglutide could directly protect NPCs against HG-induced apoptosis by inhibiting oxidative stress and activate the PI3K/Akt/caspase-3 signaling pathway via GLP-1R.

Fighting Type-2 Diabetes: Present and Future Perspectives

BACKGROUND

Type-2 diabetes mellitus accounts for 80-90% of diabetic patients. So far, the treatment of diabetes mainly aims at elevating insulin level and lowering glucose level in the peripheral blood and mitigating insulin resistance. Physiologically, insulin secretion from pancreatic β cells is delicately regulated. Thus, how insulin-related therapies could titrate blood glucose appropriately and avoid the occurrence of hypoglycemia remains an important issue for decades. Similar question is addressed on how to attenuate vascular complication in diabetic subjects.

METHODS

We overviewed the evolution of each class of anti-diabetic drugs that have been used in clinical practice, focusing on their mechanisms, clinical results and cautions.

RESULTS

Glucagon-like peptide-1 receptor agonists stimulate β cells for insulin secretion in response to diet but not in fasting stage, which make them superior than conventional insulinsecretion stimulators. DPP-4 inhibitors suppress glucagon-like peptide-1 degradation. Sodium/ glucose co-transporter 2 inhibitors enhance glucose clearance through urine excretion. The appearance of these new drugs provides new information about glycemic control. We update the clinical findings of Glucagon-like peptide-1 receptor agonists, DPP-4 inhibitors and Sodium/glucose cotransporter 2 inhibitors in glycemic control and the risk or progression of cardiovascular disease in diabetic patients. Stem cell therapy might be an alternative tool for diabetic patients to improve β cell regeneration and peripheral ischemia. We summarize the clinical results of mesenchymal stem cells transplanted into patients with diabetic limb and foot.

CONCLUSION

A stepwise intensification of dual and triple therapy for individual diabetic patient is required to achieve therapeutic target.

Sporamin suppresses growth of xenografted colorectal carcinoma in athymic BALB/c mice by inhibiting liver β-catenin and vascular endothelial growth factor expression

BACKGROUND

Colorectal cancer (CRC) is the third most common malignancy of the digestive tract and the fifth leading cause of cancer-related mortality in China. Sporamin, a Kunitz-type trypsin inhibitor isolated from sweet potato, is a potential anti-cancer agent with activities against a number of malignant tumor cells in vitro. The liver secretes a myriad of endocrine factors that may facilitate the growth and transformation of tumors in the development of CRC.

AIM

To investigate the effects of sporamin on liver morphology and biomarkers of xenografted CRC in the liver of athymic BALB/c mice.

METHODS

Twenty-seven male BALB/c nude mice were randomly divided into control, vehicle, and sporamin groups. Mice in the latter two groups were intraperitoneally xenografted with LoVo colorectal carcinoma cells and intragastrically infused with saline or sporamin (0.5 g/kg body weight/d), respectively, for 3 wk. Hematoxylin and eosin (HE) staining of the sections was performed to observe morphological changes in hepatic tissue and real-time fluorescent quantitative PCR (qPCR) and enzyme-linked immunosorbent assay (ELISA) were used to measure the expression of β-catenin and vascular endothelial growth factor (VEGF) in the liver.

RESULTS

Sporamin significantly reduced the number and weight of tumor nodules formed in the abdominal cavity. Compared with the vehicle group, the mean tumor weight (± SD) in the sporamin group was significantly reduced (0.44 ± 0.10 g vs 0.26 ± 0.15 g) and the total number of tumors decreased from 93 to 55. HE staining showed that enlargement of the nucleus and synthesis of proteins within hepatocytes, as well as infiltration of inflammatory cells into the liver, were attenuated by sporamin. Immunohistochemical staining and ELISA showed that the concentrations of β-catenin and VEGF in the liver were significantly reduced by sporamin. Compared with the vehicle group, the expression of β-catenin measured in integrated optical density units per area was reduced in the sporamin group (47.29 ± 9.10 vs 26.14 ± 1.72; P = 0.003). Expression of VEGF was also reduced after sporamin intervention from 20.78 ± 2.06 in the vehicle group to 15.80 ± 1.09 in the sporamin group (P = 0.021). Compared with the vehicle group, the concentration of β-catenin decreased from 134.42 ± 22.04 pg/mL to 109.07 ± 9.65 pg/mL after sporamin intervention (P = 0.00002). qPCR indicated that compared to the vehicle group, relative mRNA expression of β-catenin and VEGF in the liver of mice in the sporamin-treated group was significantly reduced to 71% ± 1% (P = 0.000001) and 23% ± 7% (P = 0.00002), respectively, of the vehicle group levels.

CONCLUSION

Sporamin down-regulates the expression and secretion of β-catenin and VEGF in the liver, which subsequently inhibits the transcription of downstream genes involved in cancer progression and angiogenesis.

Long Noncoding Competing Endogenous RNA Networks in Age-Associated Cardiovascular Diseases

Cardiovascular diseases (CVDs) are the most serious health problem in the world, displaying high rates of morbidity and mortality. One of the main risk factors for CVDs is age. Indeed, several mechanisms are at play during aging, determining the functional decline of the cardiovascular system. Aging cells and tissues are characterized by diminished autophagy, causing the accumulation of damaged proteins and mitochondria, as well as by increased levels of oxidative stress, apoptosis, senescence and inflammation. These processes can induce a rapid deterioration of cellular quality-control systems. However, the molecular mechanisms of age-associated CVDs are only partially known, hampering the development of novel therapeutic strategies. Evidence has emerged indicating that noncoding RNAs (ncRNAs), such as long ncRNAs (lncRNAs) and micro RNAs (miRNAs), are implicated in most patho-physiological mechanisms. Specifically, lncRNAs can bind miRNAs and act as competing endogenous-RNAs (ceRNAs), therefore modulating the levels of the mRNAs targeted by the sponged miRNA. These complex lncRNA/miRNA/mRNA networks, by regulating autophagy, apoptosis, necrosis, senescence and inflammation, play a crucial role in the development of age-dependent CVDs. In this review, the emerging knowledge on lncRNA/miRNA/mRNA networks will be summarized and the way in which they influence age-related CVDs development will be discussed.

MicroRNA-21 abrogates palmitate-induced cardiomyocyte apoptosis through caspase-3/NF-κB signal pathways

Objective:

The aim of the study was to investigate the role of microRNA-21 (miR-21) in cardiomyocyte apoptosis and to determine a possible mechanism.

Methods:

H9c2 embryonic rat heart-derived cells were used in the study. Cell viability was determined using the 3-(4.5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide (MTT) assay, and flow cytometry was used to evaluate cell apoptosis. Reverse transcription-polymerase chain reaction and western blot assays were used to detect mRNA and protein expression of the apoptosis-related proteins and miR-21. ELISA was used to detect reactive oxygen species (ROS).

Results:

Palmitate exposure greatly reduced miR-21 expression in cardiomyocytes. Apoptosis increased when miR-21 was inhibited with or without palmitate exposure. Consistently, reduced apoptosis was observed when miR-21 was overexpressed in cardiomyocytes. Caspase-3 activity was reduced after palmitate exposure. Bcl-2 protein expression was increased in H9c2 cells when transfected with the miR-21 mimic. MiR-21 overexpression alone did not induce ROS or DNA fragmentation; however, in conjunction with palmitate exposure, miR-21 mimic reduced ROS and DNA fragmentation. Moreover, palmitate administration overcame the antioxidant effect of 3 mM N-acetylcysteine to significantly inhibit apoptosis, DNA fragmentation, and caspase-3 activity. The exposure to palmitate greatly reduced p65 and p-p38 expression in the nucleus. A p38 inhibitor had no effect on the expression of Bcl-2 and cleaved caspase-3 in H9c2 cells alone; however, when combined with exposure to palmitate the p38 inhibitor induced Bcl-2 expression and inhibited caspase-3 activity. The p38 inhibitor by itself did not induce apoptosis, ROS production, or DNA fragmentation in H9c2 cells, but when palmitate was included with the p38 inhibitor, apoptosis, ROS production, and DNA fragmentation were reduced.

Conclusion:

miR-21 protects cardiomyocytes from apoptosis that is induced by palmitate through the caspase-3/NF-κB signal pathways.

Selective deletion of endothelial cell calpain in mice reduces diabetic cardiomyopathy by improving angiogenesis

AIMS/HYPOTHESIS

The role of non-cardiomyocytes in diabetic cardiomyopathy has not been fully addressed. This study investigated whether endothelial cell calpain plays a role in myocardial endothelial injury and microvascular rarefaction in diabetes, thereby contributing to diabetic cardiomyopathy.

METHODS

Endothelial cell-specific Capns1-knockout (KO) mice were generated. Conditions mimicking prediabetes and type 1 and type 2 diabetes were induced in these KO mice and their wild-type littermates. Myocardial function and coronary flow reserve were assessed by echocardiography. Histological analyses were performed to determine capillary density, cardiomyocyte size and fibrosis in the heart. Isolated aortas were assayed for neovascularisation. Cultured cardiac microvascular endothelial cells were stimulated with high palmitate. Angiogenesis and apoptosis were analysed.

RESULTS

Endothelial cell-specific deletion of Capns1 disrupted calpain 1 and calpain 2 in endothelial cells, reduced cardiac fibrosis and hypertrophy, and alleviated myocardial dysfunction in mouse models of diabetes without significantly affecting systemic metabolic variables. These protective effects of calpain disruption in endothelial cells were associated with an increase in myocardial capillary density (wild-type vs Capns1-KO 3646.14 ± 423.51 vs 4708.7 ± 417.93 capillary number/high-power field in prediabetes, 2999.36 ± 854.77 vs 4579.22 ± 672.56 capillary number/high-power field in type 2 diabetes and 2364.87 ± 249.57 vs 3014.63 ± 215.46 capillary number/high-power field in type 1 diabetes) and coronary flow reserve. Ex vivo analysis of neovascularisation revealed more endothelial cell sprouts from aortic rings of prediabetic and diabetic Capns1-KO mice compared with their wild-type littermates. In cultured cardiac microvascular endothelial cells, inhibition of calpain improved angiogenesis and prevented apoptosis under metabolic stress. Mechanistically, deletion of Capns1 elevated the protein levels of β-catenin in endothelial cells of Capns1-KO mice and constitutive activity of calpain 2 suppressed β-catenin protein expression in cultured endothelial cells. Upregulation of β-catenin promoted angiogenesis and inhibited apoptosis whereas knockdown of β-catenin offset the protective effects of calpain inhibition in endothelial cells under metabolic stress.

CONCLUSIONS/INTERPRETATION

These results delineate a primary role of calpain in inducing cardiac endothelial cell injury and impairing neovascularisation via suppression of β-catenin, thereby promoting diabetic cardiomyopathy, and indicate that calpain is a promising therapeutic target to prevent diabetic cardiac complications.

Identification of Specific Lysines and Arginines That Mediate Angiomotin Membrane Association

The family of Angiomotin (Amot) proteins regulate several biological pathways associated with cellular differentiation, proliferation, and migration. These adaptor proteins target proteins to the apical membrane, actin fibers, or the nucleus. A major function of the Amot coiled-coil homology (ACCH) domain is to initiate protein interactions with the cellular membrane, particularly those containing phosphatidylinositol lipids. The work presented in this article uses several ACCH domain lysine/arginine mutants to probe the relative importance of individual residues for lipid binding. This identified four lysine and three arginine residues that mediate full lipid binding. Based on these findings, three of these residues were mutated to glutamates in the Angiomotin 80 kDa splice form and were incorporated into human mammary cell lines. Results show that mutating three of these residues in the context of full-length Angiomotin reduced the residence of the protein at the apical membrane. These findings provide new insight into how the ACCH domain mediates lipid binding to enable Amot proteins to control epithelial cell growth.

New Insights into the Mechanisms of Action of Topical Administration of GLP-1 in an Experimental Model of Diabetic Retinopathy

The main goals of this work were to assess whether the topical administration of glucagon-like peptide-1 (GLP-1) could revert the impairment of the neurovascular unit induced by long-term diabetes (24 weeks) in diabetic mice and to look into the underlying mechanisms. For that reason, db/db mice were treated with eye drops of GLP-1 or vehicle for 3 weeks. Moreover, db/+ mice were used as control. Studies performed in vivo included electroretinogramand the assessment of vascular leakage by using Evans Blue. NF-κB, GFAP and Ki67 proteins were analyzed by immunofluorescence (IF). Additionally, caspase 9, AMPK, IKBα, NF-κB, AKT, GSK3, β-catenin, Bcl-xl, and VEGF were analyzed by WB. Finally, VEGF, IL-1β, IL-6, TNF-α, IL-18, and NLRP3 were studied by reverse transcription-polymerase chain reaction (RT-PCR) and immunofluorescence. We found that topical administration of GLP-1 reverted reactive gliosis and albumin extravasation, and protected against apoptosis and retinal dysfunction. Regarding the involved mechanisms, GLP-1 exerted an anti-inflammatory action by decreasing NF-κB, inflammosome, and pro-inflammatory factors. In addition, it also decreased VEGF expression. Furthermore, GLP-1 promoted cell survival by increasing the anti-apoptotic protein Bcl-xl and the signaling pathway Akt/GSK3b/β-catenin. Finally, Ki67 results revealed that GLP-1 treatment could induce neurogenesis. In conclusion, the topical administration of GLP-1 reverts the impairment of the neurovascular unit by modulating essential pathways involved in the development of diabetic retinopathy (DR). These beneficial effects on the neurovascular unit could pave the way for clinical trials addressed to confirm the effectiveness of GLP-1 in early stages of DR.

Tetrahydroxy stilbene glucoside alleviates palmitic acid-induced inflammation and apoptosis in cardiomyocytes by regulating miR-129-3p/Smad3 signaling

Objective

Tetrahydroxy stilbene glucoside (TSG) has been reported to exert a cytoprotective effect against various toxicants. However, the function and mechanism of TSG in palmitic acid (PA)-induced inflammation and apoptosis in cardiomyocytes are still unknown. The present study was designed to investigate the post-transcriptional mechanism in TSG-treated cardiomyocytes’ inflammation and apoptosis induced by PA.

Methods

The mRNA and protein levels were assayed by reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and western blotting, respectively. The targeted genes were predicted by a bioinformatics algorithm and confirmed by a dual luciferase reporter assay. Cell proliferation was analyzed by CCK-8 assay. Annexin V-fluorescein isothiocyanate/polyimide (annexin V-FITC/PI) staining was used to evaluate apoptosis using flow cytometry.

Results

TSG restricted the detrimental effects, including the activated inflammatory response and apoptosis, of PA in cardiomyocytes, as well as the up-regulation of miR-129-3p and down-regulation of p-Smad3 expression. In addition, bioinformatics and experimental analysis suggested that Smad3 was a direct target of miR-129-3p, which could inhibit or enhance the expression of p-Smad by transfection with miR-129-3p mimics or inhibitors, respectively. Furthermore, our results demonstrated that overexpression of Smad3 reversed the inhibition of inflammation and apoptosis by overexpression of miR-129-3p in PA-stimulated cardiomyocytes.

Conclusion

TSG targeted to miR-129-3p/Smad3 signaling inhibited PA-induced inflammation and apoptosis in cardiomyocytes.

A New Way for Beta Cell Neogenesis: Transdifferentiation from Alpha Cells Induced by Glucagon-Like Peptide 1

Recent studies showed that alpha cells, especially immature cells and proalpha cells, might be the precursors of beta cells. Exposure to glucagon-like peptide 1 (GLP1) can ameliorate hyperglycemia in diabetic mice and restore the beta cell mass. In the present study, we adopted single high-dose (60 mg/kg, i.p.) streptozotocin (STZ) to model diabetes mellitus (DM) and randomly assigned short-tail (SD) rats to a normal group, a diabetic group, GLP1 groups (50 μg/kg, 100 μg/kg, and 200 μg/kg), a GLP1 (200 μg/kg) with exendin (9-39) group, and a GLP1 with LY294002 group. We found that the pancreatic insulin-glucagon-positive cell populations increased according to the increase in GLP1 exposure. By contrast, no insulin-amylase-positive cell populations or insulin/pan-cytokeratin cells were observed in the pancreatic sections. The GLP1 receptor antagonist exendin (9-39) and the phosphatidylinositol-4,5-bisphosphate 3-kinase (PI3K) family inhibitor LY294002 not only suppressed protein kinase B (Akt), pancreatic and duodenal homeobox 1 (Pdx1), forkhead box O 1 (FoxO1), and mast cell function-associated antigen A (MafA) mRNA expression but also increased MAFB expression. We concluded that treatment with GLP1 might result in beta cell neogenesis by promoting the transdifferentiation of alpha cells but not by pancreatic acinar cells, ductal cells, or the self-replication of beta cells. The regulation on the GLP1 receptor and its downstream transcription factor PI3K/AKT/FOXO1 pathway, which causes increased pancreatic and duodenal homeobox 1 (Pdx1) and MafA mRNA expression but causes decreased MAFB expression, may be the mechanism involved in this process.

GSK-3 inhibition through GLP-1R allosteric activation mediates the neurogenesis promoting effect of P7C3 after cerebral ischemic/reperfusional injury in mice

An aminopropyl carbazole compound, P7C3, has been shown to be a potent neurogenesis promoting agent; however, its fundamental signaling action has yet to be elucidated. A cerebral ischemic/reperfusional (CI/R) injury model in mice was implemented to elucidate the neuronal protective mechanism(s) of P7C3. Treating CI/R mice using P7C3 (50-100 μg/kg, i.v.) significantly improved tracking distance and walking behavior, and reduced brain damage. Specifically, P7C3 promoted the expression of neurogenesis-associated proteins, including doublecortin, beta tubulin III (β-tub3), adam11 and adamts20, near the peri-infarct cortex, accompanied by glycogen synthase kinase 3 (GSK-3) inhibition and β-catenin upregulation. The application of a specific inhibitor against glucagon-like peptide 1 receptor (GLP-1R), exendin(9-39), revealed that the beneficial effects of P7C3 involved triggering the activation of GLP-1R-associated PKA/Akt signaling. P7C3 elicited the GLP-1R-dependent intracellular cAMP increment and the insulin secretion in cellular models. Surface plasmon resonance assay of P7C3 showed a Kd value of 0.53 μM for GLP-1R binding, and the docking of P7C3 to the putative active site on GLP-1R was successfully predicted by molecular modeling. Our findings indicate that P7C3 promotes the expression of neurogenesis proteins by activation of the cAMP/PKA-dependent and Akt/GSK3-associated β-catenin through positive allosteric stimulation of GLP-1R. Within the P7C3 class of neuroprotective molecules, this mechanism appears to be unique to the prototypical P7C3 molecule, as other active derivatives such as P7C2-A20 and P7C3-S243 they do not engage this same pathway and have been shown to work by nicotinamide phosphoribosyltransferase (NAMPT) stimulation.

Sitagliptin attenuates myocardial apoptosis via activating LKB-1/AMPK/Akt pathway and suppressing the activity of GSK-3β and p38α/MAPK in a rat model of diabetic cardiomyopathy

The present study aimed to investigate the protective effect of sitagliptin, a dipeptidyl peptidase-4 inhibitor, on diabetic cardiomyopathy (DCM)-associated apoptosis and if this effect is mediated via modulating the activity of the survival kinases; AMP-activated protein kinase (AMPK) and Akt & the apoptotic kinases; glycogen synthase kinase-3 β (GSK-3β) and p38 mitogen-activated protein kinase (p38MAPK). Diabetes was induced by a single intraperitoneal injection of streptozotocin (55 mg/kg). Diabetic rats were treated with sitagliptin (10 mg/kg/day, p.o.) and metformin (200 mg/kg/day, p.o. as positive control) for six weeks. Chronic hyperglycemia resulted in elevation of serum cardiac biomarkers reflecting cardiac damage which was supported by H&E stain. The mRNA levels of collagen types I and III were augmented reflecting cardiac fibrosis and hypertrophy which was supported by Masson trichome stain and enhanced phosphorylation of p38MAPK. Cardiac protein levels of cleaved casapse-3, BAX were elevated, whereas, the levels of Bcl-2 and p-BAD were reduced indicating cardiac apoptosis which could be attributed to the diabetes-induced reduced phosphorylation of Akt and AMPK with concomitant augmented activation of GSK-3β and p38MAPK. Protein levels of liver kinase B-1, the upstream kinase of AMPK were also supressed. Sitagliptin administration alleviated the decreased phosphorylation of AMPK and Akt, inactivated the GSK-3β and p38 AMPK, therefore, attenuating the apoptosis and hypertrophy induced by hyperglycemia in the diabetic heart. In conclusion, sitagliptin exhibits valuable therapeutic potential in the management of DCM by attenuating apoptosis. The underlying mechanism may involve the modulating activity of AMPK, Akt, GSK-3β and p38MAPK.

Liraglutide Inhibits the Apoptosis of MC3T3-E1 Cells Induced by Serum Deprivation through cAMP/PKA/β-Catenin and PI3K/AKT/GSK3β Signaling Pathways

In recent years, the interest towards the relationship between incretins and bone has been increasing. Previous studies have suggested that glucagon-like peptide-1 (GLP-1) and its receptor agonists exert beneficial anabolic influence on skeletal metabolism, such as promoting proliferation and differentiation of osteoblasts via entero-osseous-axis. However, little is known regarding the effects of GLP-1 on osteoblast apoptosis and the underlying mechanisms involved. Thus, in the present study, we investigated the effects of liraglutide, a glucagon-like peptide-1 receptor agonist, on apoptosis of murine MC3T3-E1 osteoblastic cells. We confirmed the presence of GLP-1 receptor (GLP-1R) in MC3T3-E1 cells. Our data demonstrated that liraglutide inhibited the apoptosis of osteoblastic MC3T3-E1 cells induced by serum deprivation, as detected by Annexin V/PI and Hoechst 33258 staining and ELISA assays. Moreover, liraglutide upregulated Bcl-2 expression and downregulated Bax expression and caspase-3 activity at intermediate concentration (100 nM) for maximum effect. Further study suggested that liraglutide stimulated the phosphorylation of AKT and enhanced cAMP level, along with decreased phosphorylation of GSK3β, increased β-catenin phosphorylation at Ser675 site and upregulated nuclear β-catenin content and transcriptional activity. Pretreatment of cells with the PI3K inhibitor LY294002, PKA inhibitor H89, and siRNAs GLP-1R, β-catenin abrogated the liraglutide-induced activation of cAMP, AKT, β-catenin, respectively. In conclusion, these findings illustrate that activation of GLP-1 receptor by liraglutide inhibits the apoptosis of osteoblastic MC3T3-E1 cells induced by serum deprivation through cAMP/PKA/β-catenin and PI3K/Akt/GSK3β signaling pathways.

Overexpression of adrenomedullin protects mesenchymal stem cells against hypoxia and serum deprivation‑induced apoptosis via the Akt/GSK3β and Bcl‑2 signaling pathways

The poor survival rate of transplanted mesenchymal stem cells (MSCs) within the ischemic heart limits their therapeutic potential for cardiac repair. Adrenomedullin (ADM) has been identified as a potent apoptotic inhibitor. The present study aimed to investigate the protective effects of ADM on MSCs against hypoxia and serum deprivation (H/SD)‑induced apoptosis, and to determine the potential underlying mechanisms. In the present study, a recombinant adenovirus expressing the ADM gene was established and was infected into MSCs. The infection rate was determined via microscopic detection of green fluorescence and flow cytometric analysis. The mRNA expression levels of ADM were detected by reverse transcription‑polymerase chain reaction. In addition, a model of H/SD was generated. The MSCs were randomly separated into six groups: Control, enhanced green fluorescent protein (EGFP)‑Adv, EGFP‑ADM, H/SD, EGFP‑Adv + H/SD and EGFP‑ADM + H/SD. Cell viability and proliferation were determined using the Cell Counting kit‑8 assay. Apoptosis was assessed by terminal deoxynucleotidyl transferase‑mediated‑dUTP nick‑end labeling assay and flow cytometric analysis using Annexin V‑phycoerythrin/7‑aminoactinomycin D staining. The protein expression levels of total protein kinase B (Akt), phosphorylated (p)‑Akt, total glycogen synthase kinase (GSK)3β, p‑GSK3β, B‑cell lymphoma 2 (Bcl‑2), Bcl‑2‑associated X protein (Bax), caspase‑3 and cleaved caspase‑3 were detected by western blot analysis. The results indicated that ADM overexpression could improve MSC proliferation and viability, and protect MSCs against H/SD‑induced apoptosis. In addition, ADM overexpression increased Akt and GSK3β phosphorylation, and Bcl‑2/Bax ratio, and decreased the activation of caspase‑3. These results suggested that ADM protects MSCs against H/SD‑induced apoptosis, which may be mediated via the Akt/GSK3β and Bcl‑2 signaling pathways.

Myricetin against ischemic cerebral injury in rat middle cerebral artery occlusion model

The purpose of the present study was to examine the effects of myricetin on reducing cerebral ischemia injury in a rat model. A rat model of permanent middle cerebral artery occlusion (pMCAO) was used in the present study. Rats were randomized into the following five groups: Sham, model, low‑myricetin (1 mg/kg), medium‑myricetin (5 mg/kg) and high‑myricetin (25 mg/kg) groups. Neurological deficit scores were evaluated by an examiner blinded to the experimental groups. Brain infarct size was estimated macroscopically using 2,3,5‑triphenyltetrazolium chloride staining. The levels of inflammatory factors tumor necrosis factor (TNF)‑α, interleukin (IL)‑6 and IL‑1β, and oxidative stress index superoxide dismutase (SOD), malondiadehyde (MDA), and the glutathione/glutathione disulfide (GSH/GSSG) ratio were measured by ELISA. The degree of brain cell apoptosis was determined using a terminal deoxynucleotidyl transferase dUTP nick‑end labeling assay. Protein expression levels of total or phosphorylated p38 mitogen activated protein kinase (MAPK), nuclear factor (NF)‑κB/p65 and protein kinase B (AKT) were determined using a western blotting assay. The neurological deficit score and infarct area induced by pMCAO decreased in a dose‑dependent manner following myricetin treatment. Furthermore, myricetin reduced the expression levels of IL‑1β, IL‑6, TNF‑α, and MDA, and increased GSH/GSSG ratio and SOD activity. A significant decrease in cell apoptosis was observed in response to myricetin. In addition, myricetin significantly increased the level of phosphorylated AKT protein, and decreased the phosphorylation of p38 MAPK and the level of NF‑κB/p65. Overall, the results of the present study suggested that myricetin exhibits a therapeutic effect by reducing ischemic cerebral injury, and the protective effect of myricetin may be associated with the p38 MAPK, NF‑κB/p65 and AKT signaling pathways.

Long-Acting GLP-1 Receptor Agonist Exenatide Influence on the Autonomic Cardiac Sympatho-Vagal Balance

Long-acting glucagon-like peptide 1 receptor agonists are increasingly used to treat type 2 diabetes. An increase of heart rate (HR) has been observed with their use. To elucidate the role of the cardiac sympatho-vagal balance as a possible mediator of the reported increase in HR, we performed power spectral analysis of HR variability (HRV) in patients receiving exenatide extended-release (ER). Twenty-eight ambulatory patients with type 2 diabetes underwent evaluation at initiation of exenatide-ER and thereafter at 3 and at 6 months. To obtain spectral analyses of HRV, a computerized acquisition of 10 minutes of RR electrocardiogram intervals (mean values of ~700 RR intervals) were recorded both in lying and in standing positions. All patients showed a substantial increase of HR both in lying and in standing positions. Systolic blood pressure, body weight, and glycated hemoglobin A1c significantly decreased both at 3 and 6 months compared with basal levels. The low-frequency/high-frequency ratio varied from 3.05 ± 0.4 to 1.64 ± 0.2 (P < 0.001) after 3 months and to 1.57 ± 0.3 (P < 0.001) after 6 months in a lying position and from 4.56 ± 0.8 to 2.24 ± 0.3 (P < 0.001) after 3 months and to 2.38 ± 0.4 (P < 0.001) after 6 months in a standing position compared with basal values, respectively. HR variations, induced by exenatide-ER treatment, do not appear to be related to sympathetic autonomic tone. Of note, we observed a relative increase of vagal influence on the heart.

High density lipoprotein (HDL) reverses palmitic acid induced energy metabolism imbalance by switching CD36 and GLUT4 signaling pathways in cardiomyocyte

In our previous study palmitic acid (PA) induced lipotoxicity and switches energy metabolism from CD36 to GLUT4 in H9c2 cells. Low level of high density lipoprotein (HDL) is an independent risk factor for cardiac hypertrophy. Therefore, we in the present study investigated whether HDL can reverse PA induced lipotoxicity in H9c2 cardiomyoblast cells. In this study, we treated H9c2 cells with PA to create a hyperlipidemia model in vitro and analyzed for CD36 and GLUT4 metabolic pathway proteins. CD36 metabolic pathway proteins (phospho-AMPK, SIRT1, PGC1α, PPARα, CPT1β, and CD36) were decreased by high PA (150 and 200 μg/μl) concentration. Interestingly, expression of GLUT4 metabolic pathway proteins (p-PI3K and pAKT) were increased at low concentration (50 μg/μl) and decreased at high PA concentration. Whereas, phospho-PKCζ, GLUT4 and PDH proteins expression was increased in a dose dependent manner. PA treated H9c2 cells were treated with HDL and analyzed for cell viability. Results showed that HDL treatment induced cell proliferation efficiency in PA treated cells. In addition, HDL reversed the metabolic effects of PA: CD36 translocation was increased and reduced GLUT4 translocation, but HDL treatment significantly increased CD36 metabolic pathway proteins and reduced GLUT4 pathway proteins. Rat neonatal cardiomyocytes showed similar results. In conclusion, HDL reversed palmatic acid-induced lipotoxicity and energy metabolism imbalance in H9c2 cardiomyoblast cells and in neonatal rat cardiomyocyte cells.

Berberis vulgaris and its constituent berberine as antidotes and protective agents against natural or chemical toxicities

Berberis vulgaris L (B. vulgaris) and its main constituent berberine have been used in traditional medicine for a long time. This medicinal plant and berberine have many properties that have attracted the attention of researchers over the time. According to several studies, B. vulgaris and berberine exhibited anti-inflammatory, antioxidant, anticonvulsant, antidepressant, anti-Alzheimer, anti-cancer, anti-arrhythmic, antiviral, antibacterial and anti-diabetic effects in both in vitro and invivo experiments. In regard to many reports on protective effects of B. vulgaris and berberine on natural and chemical toxins, in the current review article, the inhibitory effects of these compounds against natural, industrial, environmental and chemical toxicities with focus on cellular mechanism have been categorized. It has been mentioned that berberine could ameliorate toxicity of chemical toxins in brain, heart, kidney, liver and lung in part through antioxidant, anti-inflammatory, anti-apoptotic, modulation of mitogen-activated protein kinase (MAPK) and nuclear factor-κB (NF-κB) signaling pathways.

Saturated palmitic acid induces myocardial inflammatory injuries through direct binding to TLR4 accessory protein MD2

Obesity increases the risk for a number of diseases including cardiovascular diseases and type 2 diabetes. Excess saturated fatty acids (SFAs) in obesity play a significant role in cardiovascular diseases by activating innate immunity responses. However, the mechanisms by which SFAs activate the innate immune system are not fully known. Here we report that palmitic acid (PA), the most abundant circulating SFA, induces myocardial inflammatory injury through the Toll-like receptor 4 (TLR4) accessory protein MD2 in mouse and cell culture experimental models. Md2 knockout mice are protected against PA- and high-fat diet-induced myocardial injury. Studies of cell surface binding, cell-free protein–protein interactions and molecular docking simulations indicate that PA directly binds to MD2, supporting a mechanism by which PA activates TLR4 and downstream inflammatory responses. We conclude that PA is a crucial contributor to obesity-associated myocardial injury, which is likely regulated via its direct binding to MD2.

The free fatty acid-mediated inflammatory activities are regulated through TLR4. Here the authors show that palmitic acid binds to MD2, initiating complex formation with TLR4, recruitment of MyD88, and subsequent activation of pro-inflammatory molecules, and that MD2 blockade protects against diet-induced cardiac dysfunction.