Sirtuins: To Be or Not To Be in Diabetic Cardiomyopathy

Role of the Histone Deacetylase Family in Lipid Metabolism: Structural Specificity and Functional Diversity

Lipids play crucial roles in signal transduction. Lipid metabolism is associated with several transcriptional regulators, including peroxisome proliferator activated receptor γ, sterol regulatory element-binding protein 1, and acetyl-CoA carboxylase. In recent years, increasing evidence has suggested that members of the histone deacetylase (HDAC) family play key roles in lipid metabolism. However, the mechanisms by which each member of this family regulates lipid metabolism remain unclear. This review discusses the latest research on the roles played by HDACs in fat metabolism. The role of HDACs in obesity, diabetes, and atherosclerosis has also been discussed. In addition, the interaction of HDACs with the gut microbiome and circadian rhythm has been reviewed, and the future development trend in HDACs has been predicted, which may potentiate therapeutic application of targeted HDACs in related metabolic diseases.

Mitochondrial glycerol 3-phosphate dehydrogenase deficiency exacerbates lipotoxic cardiomyopathy

Metabolic diseases such as obesity and diabetes induce lipotoxic cardiomyopathy, which is characterized by myocardial lipid accumulation, dysfunction, hypertrophy, fibrosis and mitochondrial dysfunction. Here, we identify that mitochondrial glycerol 3-phosphate dehydrogenase (mGPDH) is a pivotal regulator of cardiac fatty acid metabolism and function in the setting of lipotoxic cardiomyopathy. Cardiomyocyte-specific deletion of mGPDH promotes high-fat diet induced cardiac dysfunction, pathological hypertrophy, myocardial fibrosis, and lipid accumulation. Mechanically, mGPDH deficiency inhibits the expression of desuccinylase SIRT5, and in turn, the hypersuccinylates majority of enzymes in the fatty acid oxidation (FAO) cycle and promotes the degradation of these enzymes. Moreover, manipulating SIRT5 abolishes the effects of mGPDH ablation or overexpression on cardiac function. Finally, restoration of mGPDH improves lipid accumulation and cardiomyopathy in both diet-induced and genetic obese mouse models. Thus, our study indicates that targeting mGPDH could be a promising strategy for lipotoxic cardiomyopathy in the context of obesity and diabetes.

Maladaptive response following glucose overload in GLUT4-overexpressing H9C2 cardiomyoblasts

BACKGROUND

Glucose overload drives diabetic cardiomyopathy by affecting the tricarboxylic acid pathway. However, it is still unknown how cells could overcome massive chronic glucose influx on cellular and structural level.

METHODS/MATERIALS

Expression profiles of hyperglycemic, glucose transporter-4 (GLUT4) overexpressing H9C2 (KE2) cardiomyoblasts loaded with 30 mM glucose (KE230L) and wild type (WT) cardiomyoblasts loaded with 30 mM glucose (WT30L) were compared using proteomics, real-time polymerase quantitative chain reaction analysis, or Western blotting, and immunocytochemistry.

RESULTS

The findings suggest that hyperglycemic insulin-sensitive cells at the onset of diabetic cardiomyopathy present complex changes in levels of structural cell-related proteins like tissue inhibitor of metalloproteases-1 (1.3 fold), intercellular adhesion molecule 1 (1.8 fold), type-IV-collagen (3.2 fold), chaperones (Glucose-Regulated Protein 78: 1.8 fold), autophagy (Autophagosome Proteins LC3A, LC3B: 1.3 fold), and in unfolded protein response (UPR; activating transcription factor 6α expression: 2.3 fold and processing: 2.4 fold). Increased f-actin levels were detectable with glucose overload by immnocytochemistry. Effects on energy balance (1.6 fold), sirtuin expression profile (Sirtuin 1: 0.7 fold, sirtuin 3: 1.9 fold, and sirtuin 6: 4.2 fold), and antioxidant enzymes (Catalase: 0.8 fold and Superoxide dismutase 2: 1.5 fold) were detected.

CONCLUSION

In conclusion, these findings implicate induction of chronic cell distress by sustained glucose accumulation with a non-compensatory repair reaction not preventing final cell death. This might explain the chronic long lasting pathogenesis observed in developing heart failure in diabetes mellitus.

Epigenetics in diabetic cardiomyopathy

Diabetic cardiomyopathy (DCM) is a critical complication that poses a significant threat to the health of patients with diabetes. The intricate pathological mechanisms of DCM cause diastolic dysfunction, followed by impaired systolic function in the late stages. Accumulating researches have revealed the association between DCM and various epigenetic regulatory mechanisms, including DNA methylation, histone modifications, non-coding RNAs, and other epigenetic molecules. Recently, a profound understanding of epigenetics in the pathophysiology of DCM has been broadened owing to advanced high-throughput technologies, which assist in developing potential therapeutic strategies. In this review, we briefly introduce the epigenetics regulation and update the relevant progress in DCM. We propose the role of epigenetic factors and non-coding RNAs (ncRNAs) as potential biomarkers and drugs in DCM diagnosis and treatment, providing a new perspective and understanding of epigenomics in DCM.

Noncoding RNAs as therapeutic targets in autophagy-related diabetic cardiomyopathy

Diabetic cardiomyopathy, a multifaceted complication of diabetes mellitus, remains a major challenge in clinical management due to its intricate pathophysiology. Emerging evidence underscores the pivotal role of autophagy dysregulation in the progression of diabetic cardiomyopathy, providing a novel avenue for therapeutic intervention. Noncoding RNAs (ncRNAs), a diverse class of regulatory molecules, have recently emerged as promising candidates for targeted therapeutic strategies. The exploration of various classes of ncRNAs, including microRNAs (miRNAs), long noncoding RNAs (lncRNAs), and circular RNAs (circRNAs) reveal their intricate regulatory networks in modulating autophagy and influencing the pathophysiological processes associated with diabetic cardiomyopathy. The nuanced understanding of the molecular mechanisms underlying ncRNA-mediated autophagic regulation offers a rationale for the development of precise and effective therapeutic interventions. Harnessing the regulatory potential of ncRNAs presents a promising frontier for the development of targeted and personalized therapeutic strategies, aiming to ameliorate the burden of diabetic cardiomyopathy in affected individuals. As research in this field advances, the identification and validation of specific ncRNA targets hold immense potential for the translation of these findings into clinically viable interventions, ultimately improving outcomes for patients with diabetic cardiomyopathy. This review encapsulates the current understanding of the intricate interplay between autophagy and diabetic cardiomyopathy, with a focus on the potential of ncRNAs as therapeutic targets.

Molecular mechanisms of metabolic dysregulation in diabetic cardiomyopathy

Diabetic cardiomyopathy (DCM), one of the most serious complications of diabetes mellitus, has become recognized as a cardiometabolic disease. In normoxic conditions, the majority of the ATP production (>95%) required for heart beating comes from mitochondrial oxidative phosphorylation of fatty acids (FAs) and glucose, with the remaining portion coming from a variety of sources, including fructose, lactate, ketone bodies (KB) and branched chain amino acids (BCAA). Increased FA intake and decreased utilization of glucose and lactic acid were observed in the diabetic hearts of animal models and diabetic patients. Moreover, the polyol pathway is activated, and fructose metabolism is enhanced. The use of ketones as energy sources in human diabetic hearts also increases significantly. Furthermore, elevated BCAA levels and impaired BCAA metabolism were observed in the hearts of diabetic mice and patients. The shift in energy substrate preference in diabetic hearts results in increased oxygen consumption and impaired oxidative phosphorylation, leading to diabetic cardiomyopathy. However, the precise mechanisms by which impaired myocardial metabolic alterations result in diabetes mellitus cardiac disease are not fully understood. Therefore, this review focuses on the molecular mechanisms involved in alterations of myocardial energy metabolism. It not only adds more molecular targets for the diagnosis and treatment, but also provides an experimental foundation for screening novel therapeutic agents for diabetic cardiomyopathy.

Pyroptosis: Mechanisms and links with diabetic cardiomyopathy

Diabetes mellitus (DM) is a chronic metabolic disease characterized by hyperglycaemia that seriously affects human health. Diabetic cardiomyopathy (DCM) is a major cardiovascular complication and one of the main causes of death in patients with DM. Although DCM attracts great attention, and new therapeutic methods are continuously developed, there is a lack of effective treatment strategies. Therefore, exploring and targeting new signalling pathways related to the evolution of DCM becomes a hotspot and difficulty in the prevention and treatment of DCM. Pyroptosis is a newly discovered regulated cell death that is heavily dependent on the formation of plasma membrane pores by members of the gasdermin protein family and is reported to be involved in the occurrence, development, and pathogenesis of DCM. In this review, we focus on the molecular mechanisms of pyroptosis, its involvement in the relevant signalling pathways of DCM, and potential pyroptosis-targeting therapeutic strategies for the treatment of DCM. Our review provides new insights into the use of pyroptosis as a useful tool for the prevention and treatment of DCM and clarifies future research directions.

Anemarrhena asphodeloides Bunge total saponins ameliorate diabetic cardiomyopathy by modifying the PI3K/AKT/HIF-1α pathway to restore glycolytic metabolism

ETHNOPHARMACOLOGICAL RELEVANCE

Based on the theory of traditional Chinese medicine (TCM), diabetic cardiomyopathy (DCM) belongs to the category of "Xiaoke disease" according to the symptoms, and "stasis-heat" is the main pathogenesis of DCM. The Chinese medicine Anemarrhena asphodeloides Bunge (AAB), as a representative of heat-clearing and engendering fluid, is often used clinically in the treatment of DCM. Anemarrhena asphodeloides Bunge total saponins (RATS) are the main bioactive components of AAB, the modern pharmacologic effects of RATS are anti-inflammatory, hypoglycemic, and cardioprotective. However, the potential protective mechanisms of RATS against DCM remain largely undiscovered.

AIM OF THE STUDY

The primary goal of this study was to explore the effect of RATS on DCM and its mechanism of action.

MATERIALS AND METHODS

Streptozotocin and a high-fat diet were used to induce DCM in rats. UHPLC/Q-TOF-MS was used to determine the chemical components of RATS. The degenerative alterations and apoptotic cells in the heart were assessed by HE staining and TUNEL. Network pharmacology was used to anticipate the probable targets and important pathways of RATS. The alterations in metabolites and main metabolic pathways in heart tissue were discovered using 1 H-NMR metabolomics. Ultimately, immunohistochemistry was used to find critical pathway protein expression.

RESULTS

First of all, UHPLC/Q-TOF-MS analysis showed that RATS contained 11 active ingredients. In animal experiments, we found that RATS lowered blood glucose and lipid levels in DCM rats, and alleviated cardiac pathological damage, and decreased cardiomyocyte apoptosis. Furthermore, the study found that RATS effectively reduced inflammatory factor release and the level of oxidative stress. Mechanistically, RATS downregulated the expression levels of PI3K, AKT, HIF-1α, LDHA, and GLUT4 proteins. Additionally, glycolysis was discovered to be a crucial pathway for RATS in the therapy of DCM.

CONCLUSIONS

Our findings suggest that the protective effect of RATS on DCM may be attributed to the inhibition of the PI3K/AKT/HIF-1α pathway and the correction of glycolytic metabolism.

CD38 Deficiency Alleviates Diabetic Cardiomyopathy by Coordinately Inhibiting Pyroptosis and Apoptosis

Diabetic cardiomyopathy is one of the diabetes mellitus-induced cardiovascular complications that can result in heart failure in severe cases, which is characterized by cardiomyocyte apoptosis, local inflammation, oxidative stress, and myocardial fibrosis. CD38, a main hydrolase of NAD+ in mammals, plays an important role in various cardiovascular diseases, according to our previous studies. However, the role of CD38 in diabetes-induced cardiomyopathy is still unknown. Here, we report that global deletion of the CD38 gene significantly prevented diabetic cardiomyopathy induced by high-fat diet plus streptozotocin (STZ) injection in CD38 knockout (CD38-KO) mice. We observed that CD38 expression was up-regulated, whereas the expression of Sirt3 was down-regulated in the hearts of diabetic mice. CD38 deficiency significantly promoted glucose metabolism and improved cardiac functions, exemplified by increased left ventricular ejection fraction and fractional shortening. In addition, we observed that CD38 deficiency markedly decreased diabetes or high glucose and palmitic acid (HG + PA)-induced pyroptosis and apoptosis in CD38 knockout hearts or cardiomyocytes, respectively. Furthermore, we found that the expression levels of Sirt3, mainly located in mitochondria, and its target gene FOXO3a were increased in CD38-deficient hearts and cardiomyocytes with CD38 knockdown under diabetic induction conditions. In conclusion, we demonstrated that CD38 deficiency protected mice from diabetes-induced diabetic cardiomyopathy by reducing pyroptosis and apoptosis via activating NAD+/Sirt3/FOXO3a signaling pathways.

The role of mitochondria in myocardial damage caused by energy metabolism disorders: From mechanisms to therapeutics

Myocardial damage is the most serious pathological consequence of cardiovascular diseases and an important reason for their high mortality. In recent years, because of the high prevalence of systemic energy metabolism disorders (e.g., obesity, diabetes mellitus, and metabolic syndrome), complications of myocardial damage caused by these disorders have attracted widespread attention. Energy metabolism disorders are independent of traditional injury-related risk factors, such as ischemia, hypoxia, trauma, and infection. An imbalance of myocardial metabolic flexibility and myocardial energy depletion are usually the initial changes of myocardial injury caused by energy metabolism disorders, and abnormal morphology and functional destruction of the mitochondria are their important features. Specifically, mitochondria are the centers of energy metabolism, and recent evidence has shown that decreased mitochondrial function, caused by an imbalance in mitochondrial quality control, may play a key role in myocardial injury caused by energy metabolism disorders. Under chronic energy stress, mitochondria undergo pathological fission, while mitophagy, mitochondrial fusion, and biogenesis are inhibited, and mitochondrial protein balance and transfer are disturbed, resulting in the accumulation of nonfunctional and damaged mitochondria. Consequently, damaged mitochondria lead to myocardial energy depletion and the accumulation of large amounts of reactive oxygen species, further aggravating the imbalance in mitochondrial quality control and forming a vicious cycle. In addition, impaired mitochondria coordinate calcium homeostasis imbalance, and epigenetic alterations participate in the pathogenesis of myocardial damage. These pathological changes induce rapid progression of myocardial damage, eventually leading to heart failure or sudden cardiac death. To intervene more specifically in the myocardial damage caused by metabolic disorders, we need to understand the specific role of mitochondria in this context in detail. Accordingly, promising therapeutic strategies have been proposed. We also summarize the existing therapeutic strategies to provide a reference for clinical treatment and developing new therapies.

Fatty acid metabolism disorders and potential therapeutic traditional Chinese medicines in cardiovascular diseases

Cardiovascular diseases are currently the primary cause of mortality in the whole world. Growing evidence indicated that the disturbances in cardiac fatty acid metabolism are crucial contributors in the development of cardiovascular diseases. The abnormal cardiac fatty acid metabolism usually leads to energy deficit, oxidative stress, excessive apoptosis, and inflammation. Targeting fatty acid metabolism has been regarded as a novel approach to the treatment of cardiovascular diseases. However, there are currently no specific drugs that regulate fatty acid metabolism to treat cardiovascular diseases. Many traditional Chinese medicines have been widely used to treat cardiovascular diseases in clinics. And modern studies have shown that they exert a cardioprotective effect by regulating the expression of key proteins involved in fatty acid metabolism, such as peroxisome proliferator-activated receptor α and carnitine palmitoyl transferase 1. Hence, we systematically reviewed the relationship between fatty acid metabolism disorders and four types of cardiovascular diseases including heart failure, coronary artery disease, cardiac hypertrophy, and diabetic cardiomyopathy. In addition, 18 extracts and eight monomer components from traditional Chinese medicines showed cardioprotective effects by restoring cardiac fatty acid metabolism. This work aims to provide a reference for the finding of novel cardioprotective agents targeting fatty acid metabolism.

Polystyrene microplastics disrupt female reproductive health and fertility via sirt1 modulation in zebrafish (Danio rerio)

Microplastics (MPs) pollution poses an emerging threat to aquatic biota, which could hinder their physiological processes. Recently various evidence has demonstrated the toxic impacts of MPs on cellular and organismal levels, but still, the underlying molecular mechanism behind their toxicity remains ambiguous. The hypothalamic-pituitary-gonadal (HPG) axis regulates the synthesis and release of sex steroid hormones, and SIRT1 plays a vital role in this process. The current study aimed to elucidate the harmful effects of MPs on female reproduction via SIRT1 modulation. Healthy female zebrafish were exposed to different concentrations (50 and 500 µg/L) of polystyrene microplastics (PS-MPs). The results revealed a significant change in the gonadosomatic index (GSI) after exposure to PS-MPs. In addition, the decreased fecundity rate displayed an evident dosage effect, indicating that exposure to PS-MPs causes deleterious effects on fertilization. Furthermore, significantly enhanced levels of reactive oxygen species (ROS) and apoptotic signals through the TUNEL assay were evaluated in different treated groups. Moreover, morphological alterations in the gonads of zebrafish exposed to MPs were also observed through H&E staining. The subsequent change in plasma steroid hormone levels (E2/T ratio) showed an imbalance in hormonal homeostasis. Meanwhile, to follow PS-MPs' effects on the HPG axis via SIRT1 modulation and gene expression related to steroidogenesis, SIRT1/p53 pathway was evaluated through qPCR. The altered transcription levels of genes indicated the plausible interference of PS-MPs on the HPG axis function. Our in-silico molecular docking study proves that PS-MPs efficiently bind and inhibit endocrine receptors and SIRT1. Thus, these findings add to our understanding of the probable molecular mechanisms of reproductive impairment caused by PS-MPs in zebrafish.

The lncRNA HOTAIR attenuates pyroptosis of diabetic cardiomyocytes by recruiting FUS to regulate SIRT3 expression

Diabetic cardiomyopathy (DCM) is a serious cardiovascular complication of diabetes that severely affects the quality of life of diabetic patients. Long noncoding RNAs (lncRNAs) play important roles in the pathogenesis of DCM. However, the role of the lncRNA homeobox transcript antisense RNA (HOTAIR) in the progression of DCM remains unclear. The present study aimed to investigate the role of HOTAIR in high glucose (HG)-induced pyroptosis in cardiomyocytes. The expression of the lncRNA HOTAIR, FUS, and SIRT3 in H9C2 cardiomyocytes was detected by RT-qPCR. Western blotting was used to evaluate the expression of FUS and SIRT3 as well as that of pyroptosis- and inflammation-related proteins. RT-qPCR and ELISA were used to determine the expression and secretion of IL-1β and IL-18. RNA pulldown and RIP experiments were used to validate the binding relationship among HOTAIR, FUS, and SIRT3. Flow cytometry was performed to detect pyroptosis. HG induced pyroptosis and elevated the expression of proteins associated with pyroptosis and inflammation (NLRP3, GSDMD-N, cleaved caspase-1, IL-1β, and IL-18) in cardiomyocytes. HOTAIR and SIRT3 levels were decreased in HG-exposed H9C2 cells. Additionally, overexpression of HOTAIR inhibited the HG-induced pyroptosis and inflammatory response in cardiomyocytes. HOTAIR upregulated SIRT3 expression in H9C2 cells by targeting FUS. Moreover, SIRT3 upregulation suppressed HG-mediated pyroptosis of cardiomyocytes. Notably, SIRT3 depletion reversed the inhibitory effect of HOTAIR on HG-triggered pyroptosis in cardiomyocytes. Our research indicates that HOTAIR alleviates pyroptosis in diabetic cardiomyocytes through the FUS/SIRT3 axis, providing a potential marker for the diagnosis and treatment of DCM.

S-Doped carbonized polymer dots inhibit early myocardial fibrosis by regulating mitochondrial function

Myocardial fibrosis (MF) is a critical pathological lesion in the progression of various acute and chronic cardiovascular diseases. However, there is still a lack of clinically effective drugs and treatments for MF therapies. Herein, for the first time, we developed fluorescent sulfur-doped carbonized polymer dots (S-CPDs) as new nano-antioxidants to reduce the cardiomyocyte damage caused by reactive oxygen species (ROS) in the early stage of fibrotic lesions. In vitro results suggested that the pre-protection of S-CPDs significantly increased the survival rate of H9c2 cells under severe oxidative stress, inhibited the isoproterenol (ISO)-induced hypertrophy of myocardial cells through improving the content of mitochondria related proteins and adenosine triphosphate (ATP) in cells. Moreover, S-CPD administration could effectively decrease cardiac hypertrophy and promote heart function in MF rat models. The rapid internalization, high biocompatibility and fluorescence imaging potential of S-CPDs revealed their promising application prospects in the diagnoses and treatments of cardiovascular diseases.

Central role of cardiac fibroblasts in myocardial fibrosis of diabetic cardiomyopathy

Diabetic cardiomyopathy (DCM), a main cardiovascular complication of diabetes, can eventually develop into heart failure and affect the prognosis of patients. Myocardial fibrosis is the main factor causing ventricular wall stiffness and heart failure in DCM. Early control of myocardial fibrosis in DCM is of great significance to prevent or postpone the progression of DCM to heart failure. A growing body of evidence suggests that cardiomyocytes, immunocytes, and endothelial cells involve fibrogenic actions, however, cardiac fibroblasts, the main participants in collagen production, are situated in the most central position in cardiac fibrosis. In this review, we systematically elaborate the source and physiological role of myocardial fibroblasts in the context of DCM, and we also discuss the potential action and mechanism of cardiac fibroblasts in promoting fibrosis, so as to provide guidance for formulating strategies for prevention and treatment of cardiac fibrosis in DCM.

Why Is Longevity Still a Scientific Mystery? Sirtuins-Past, Present and Future

The sirtuin system consists of seven highly conserved regulatory enzymes responsible for metabolism, antioxidant protection, and cell cycle regulation. The great interest in sirtuins is associated with the potential impact on life extension. This article summarizes the latest research on the activity of sirtuins and their role in the aging process. The effects of compounds that modulate the activity of sirtuins were discussed, and in numerous studies, their effectiveness was demonstrated. Attention was paid to the role of a caloric restriction and the risks associated with the influence of careless sirtuin modulation on the organism. It has been shown that low modulators' bioavailability/retention time is a crucial problem for optimal regulation of the studied pathways. Therefore, a detailed understanding of the modulator structure and potential reactivity with sirtuins in silico studies should precede in vitro and in vivo experiments. The latest achievements in nanobiotechnology make it possible to create promising molecules, but many of them remain in the sphere of plans and concepts. It seems that solving the mystery of longevity will have to wait for new scientific discoveries.

Oxidative stress and inflammation regulation of sirtuins: New insights into common oral diseases

Sirtuins are a family of nicotinamide adenine dinucleotide (NAD)⁺-dependent histone deacetylases, comprising seven members SIRT1-SIRT7. Sirtuins have been extensively studied in regulating ageing and age-related diseases. Sirtuins are also pivotal modulators in oxidative stress and inflammation, as they can regulate the expression and activation of downstream transcriptional factors (such as Forkhead box protein O3 (FOXO3a), nuclear factor erythroid 2-related factor 2 (Nrf2) and nuclear factor-kappa B (NF-κB)) as well as antioxidant enzymes, through epigenetic modification and post-translational modification. Most importantly, studies have shown that aberrant sirtuins are involved in the pathogenesis of infectious and inflammatory oral diseases, and oral cancer. In this review, we provide a comprehensive overview of the regulatory patterns of sirtuins at multiple levels, and the essential roles of sirtuins in regulating inflammation, oxidative stress, and bone metabolism. We summarize the involvement of sirtuins in several oral diseases such as periodontitis, apical periodontitis, pulpitis, oral candidiasis, oral herpesvirus infections, dental fluorosis, and oral cancer. At last, we discuss the potential utilization of sirtuins as therapeutic targets in oral diseases.

Hydrogen Sulfide Plays an Important Role by Regulating Endoplasmic Reticulum Stress in Diabetes-Related Diseases

Endoplasmic reticulum (ER) plays important roles in protein synthesis, protein folding and modification, lipid biosynthesis, calcium storage, and detoxification. ER homeostasis is destroyed by physiological and pharmacological stressors, resulting in the accumulation of misfolded proteins, which causes ER stress. More and more studies have shown that ER stress contributes to the pathogenesis of many diseases, such as diabetes, inflammation, neurodegenerative diseases, cancer, and autoimmune diseases. As a toxic gas, H₂S has, in recent years, been considered the third most important gas signal molecule after NO and CO. H₂S has been found to have many important physiological functions and to play an important role in many pathological and physiological processes. Recent evidence shows that H₂S improves the body’s defenses to many diseases, including diabetes, by regulating ER stress, but its mechanism has not yet been fully understood. We therefore reviewed recent studies of the role of H₂S in improving diabetes-related diseases by regulating ER stress and carefully analyzed its mechanism in order to provide a theoretical reference for future research.

The Role of H2S Regulating NLRP3 Inflammasome in Diabetes

Nucleotide-binding oligomeric domain (NOD)-like receptor protein 3 (NLRP3) is a recently discovered cytoplasmic multiprotein complex involved in inflammation. The NLRP3 inflammasome contains NLRP3, apoptosis-related specific protein (ASC) and precursor caspase-1. The NLRP3 inflammasome is involved in many diseases, including diabetes. H₂S is a harmful gas with a rotten egg smell. Recently, it has been identified as the third gas signal molecule after nitric oxide and carbon monoxide. It has many biological functions and plays an important role in many diseases, including diabetes. In recent years, it has been reported that H₂S regulation of the NLRP3 inflammasome contributes to a variety of diseases. However, the mechanism has not been fully understood. In this review, we summarized the recent role and mechanism of H₂S in regulating the NLRP3 inflammasome in diabetes, in order to provide a theoretical basis for future research.

Combination of resolvin E1 and lipoxin A4 promotes the resolution of pulpitis by inhibiting NF-κB activation through upregulating sirtuin 7 in dental pulp fibroblasts

Objectives

To determine whether the combination of resolvin E1 (RvE1) and lipoxin A4 (LXA4) could promote resolution of pulpitis and to investigate the mechanism.

Materials and Methods

Preliminary screening was first conducted in four specialized pro‐resolving mediators (SPMs). Real‐time quantitative polymerase chain reaction, western blotting, enzyme‐linked immunosorbent assay and double‐immunofluorescence labelling were employed to assess the expression of RelA, SIRT1, SIRT6, SIRT7 and pro‐inflammatory factors. Dental pulp fibroblasts (DPFs) were transfected with siRNA to assess the biological role of SIRT7. A pulpitis model was utilized to evaluate the in vivo curative effect.

Results

Preliminary results showed that RvE1 and LXA4 reduced the expression of RelA more markedly than other two SPMs. Both RvE1 and LXA4 treatment downregulated nuclear factor kappa B (NF‐κB) activation and increased the expression of SIRT1, SIRT6 and SIRT7, more so in combination than alone. Double‐immunofluorescence labelling showed that SIRT7 co‐localized with p‐p65 and Ac‐p65 in the nucleus. Inhibiting ChemR23 and ALX reversed the expression of RelA mRNA, p‐p65 and Ac‐p65 proteins, pro‐inflammatory factors, SIRT1, SIRT6 and SIRT7. Silencing SIRT7 significantly increased p‐p65 and Ac‐p65 protein levels and decreased SIRT1 and SIRT6 expression. In vivo experiments showed that combined administration of RvE1 and LXA4 promoted pulpitis markedly to resolution.

Conclusions

Combination of RvE1 and LXA4 effectively inhibited NF‐κB activation by upregulating SIRT7 expression in DPFs, leading to reduced production of pro‐inflammatory factors and promotion of pulpitis resolution.

Targeting Gut Microbiota With Natural Polysaccharides: Effective Interventions Against High-Fat Diet-Induced Metabolic Diseases

Unhealthy diet, in particular high-fat diet (HFD) intake, can cause the development of several metabolic disorders, including obesity, hyperlipidemia, type 2 diabetes mellitus (T2DM), non-alcoholic fatty liver disease (NAFLD), and metabolic syndrome (MetS). These popular metabolic diseases reduce the quality of life, and induce premature death worldwide. Evidence is accumulating that the gut microbiota is inextricably associated with HFD-induced metabolic disorders, and dietary intervention of gut microbiota is an effective therapeutic strategy for these metabolic dysfunctions. Polysaccharides are polymeric carbohydrate macromolecules and sources of fermentable dietary fiber that exhibit biological activities in the prevention and treatment of HFD-induced metabolic diseases. Of note, natural polysaccharides are among the most potent modulators of the gut microbiota composition. However, the prebiotics-like effects of polysaccharides in treating HFD-induced metabolic diseases remain elusive. In this review, we introduce the critical role of gut microbiota human health and HFD-induced metabolic disorders. Importantly, we review current knowledge about the role of natural polysaccharides in improving HFD-induced metabolic diseases by regulating gut microbiota.

Protective role of hydrogen sulfide against diabetic cardiomyopathy via alleviating necroptosis

Diabetic cardiomyopathy lacks effective and novel methods. Hydrogen sulfide (H₂S) as the third gasotransmitter plays an important role in the cardiovascular system. Our study was to elucidate the protective effect and possible mechanism of H₂S on diabetic cardiomyopathy from the perspective of necroptosis. Leptin receptor deficiency (db/db) mice and streptozotocin (STZ)-induced diabetic cystathionine-γ-lyase (CSE) knockout (KO) mice were investigated. In addition, cardiomyocytes were stimulated with high glucose. We found that plasma H₂S level, myocardial H₂S production and CSE mRNA expression was impaired in the diabetic mice. CSE deficiency exacerbated diabetic cardiomyopathy, and promoted myocardial oxidative stress, necroptosis and inflammasome in STZ-induced mice. CSE inhibitor dl-propargylglycine (PAG) aggravated cell damage and oxidative stress, deteriorated necroptosis and inflammasome in cardiomyocytes with high glucose stimulation. H₂S donor sodium hydrosulfide (NaHS) improved diabetic cardiomyopathy, attenuated myocardial oxidative stress, necroptosis and the NLR family pyrin domain-containing protein 3 (NLRP3) in db/db mice. NaHS also alleviated cell damage, oxidative stress, necroptosis and inflammasome in cardiomyocytes with high glucose stimulation. In Conclusion, H₂S deficiency aggravated mitochondrial damage, increased reactive oxygen species accumulation, promoted necroptosis, activated NLRP3 inflammasome, and finally exacerbated diabetic cardiomyopathy. Exogenous H₂S supplementation alleviated necroptosis to suppress NLRP3 inflammasome activation and attenuate diabetic cardiomyopathy via mitochondrial dysfunction improvement and oxidative stress inhibition. Our study provides the first evidence and a new mechanism that necroptosis inhibition by a pharmacological manner of H₂S administration protected against diabetic cardiomyopathy. It is beneficial to provide a novel strategy for the prevention and treatment of diabetic cardiomyopathy.