Hydrogen sulfide-mediated regulation of cell death signaling ameliorates adverse cardiac remodeling and diabetic cardiomyopathy

Types of cell death in diabetic cardiomyopathy: insights from animal models

Approximately one-tenth of the global population is affected by diabetes mellitus, and its incidence continues to rise each year. In China, 1.4 million patients die from diabetes-related complications every year. Additionally, approximately 26% of patients with diabetes develop diabetic cardiomyopathy, with heart failure being one of the main causes of death in these patients. However, early detection of diabetic cardiomyopathy has proven to be difficult in a clinical setting; furthermore, there are limited guidelines and targeted means of prevention and treatment for this disease. In recent years, several studies have provided evidence for the occurrence of various forms of regulated cell death in diabetic myocardial cells, including apoptosis, necroptosis, ferroptosis, and cuproptosis, which are closely linked to the pathological progression of diabetic cardiomyopathy. Although most research on diabetic cardiomyopathy is currently in the animal trial phase, the inhibition of these regulatory cell death processes can limit or slow down the progression of diabetic cardiomyopathy. Therefore, this review discusses the appropriate animal experimental models currently available for diabetic cardiomyopathy and evaluates the roles of apoptosis, necroptosis, ferroptosis, and cuproptosis in diabetic cardiomyopathy. We hope to provide new methods and ideas for future research in diabetic cardiomyopathy.

Thrombosis and Aging: Fibrin Clot Properties and Oxidative Stress

Significance: Aging is a complex process associated with an increased risk of many diseases, including thrombosis. This review summarizes age-related prothrombotic mechanisms in clinical settings of thromboembolism, focusing on the role of fibrin structure and function modified by oxidative stress. Recent Advances: Aging affects blood coagulation and fibrinolysis via multiple mechanisms, including enhanced oxidative stress, with an imbalance in the oxidant/antioxidant mechanisms, leading to loss of function and accumulation of oxidized proteins, including fibrinogen. Age-related prothrombotic alterations are multifactorial involving enhanced platelet activation, endothelial dysfunction, and changes in coagulation factors and inhibitors. Formation of more compact fibrin clot networks displaying impaired susceptibility to fibrinolysis represents a novel mechanism, which might contribute to atherothrombosis and venous thrombosis. Alterations to fibrin clot structure/function are at least in part modulated by post-translational modifications of fibrinogen and other proteins involved in thrombus formation, with a major impact of carbonylation. Fibrin clot properties are also involved in the efficacy and safety of therapy with oral anticoagulants, statins, and/or aspirin. Critical Issues: Since a prothrombotic state is observed in very elderly individuals free of diseases associated with thromboembolism, the actual role of activated blood coagulation in health remains elusive. It is unclear to what extent oxidative modifications of coagulation and fibrinolytic proteins, in particular fibrinogen, contribute to a prothrombotic state in healthy aging. Future Directions: Ongoing studies will show whether novel therapies that may alter oxidative stress and fibrin characteristics are beneficial to prevent atherosclerosis and thromboembolic events associated with aging.

Tailoring transfection for cardiomyocyte cell lines: balancing efficiency and toxicity in lipid versus polymer-based transfection methods in H9c2 and HL-1 cells

Cardiovascular research relies heavily on the veracity of in vitro cardiomyocyte models, with H9c2 and HL-1 cell lines at the forefront due to their cardiomyocyte-like properties. However, the variability stemming from nonstandardized culturing and transfection methods poses a significant challenge to data uniformity and reliability. In this study, we introduce meticulously crafted protocols to enhance the culture and transfection of H9c2 and HL-1 cells, emphasizing the reduction of cytotoxic effects while improving transfection efficiency. Through the examination of polymer-based and lipid-based transfection methods, we offer a comparative analysis that underscores the heightened efficiency and reduced toxicity of these approaches. Our research provides an extensive array of step-by-step procedures designed to foster robust cell cultures and outlines troubleshooting practices to rectify issues of low transfection rates. We discuss the merits and drawbacks of both transfection techniques, equipping researchers with the knowledge to choose the most fitting method for their experimental goals. By offering a definitive guide to these cell lines' culturing and transfection, our work seeks to set a new standard in procedural consistency, ensuring that the cardiovascular research community can achieve more dependable and reproducible results, thereby pushing the boundaries of current methodologies toward impactful clinical applications.NEW & NOTEWORTHY We have developed standardized protocols that significantly reduce cytotoxicity and enhance transfection efficiency in H9c2 and HL-1 cardiomyocyte cell lines. Our detailed comparative analysis of polymer-based and lipid-based transfection methods has identified optimized approaches with superior performance. Accompanying these protocols are comprehensive troubleshooting strategies to address common issues related to low transfection rates. Implementing these protocols is expected to yield more consistent and reproducible results, driving the field of cardiovascular research toward impactful clinical breakthroughs.

Regulation of cardiac ferroptosis in diabetic human heart failure: uncovering molecular pathways and key targets

Diabetes significantly increases the risk of heart failure by inducing myocardial cell death, potentially through ferroptosis-an iron-dependent, non-apoptotic cell death pathway characterized by lipid peroxidation. The role of cardiac ferroptosis in human heart failure, however, remains poorly understood. In this study, we compared cardiac ferroptosis in humans with diabetic heart failure to that in healthy controls. Our findings reveal that diabetes not only intensifies myocardial cell death but also upregulates markers of ferroptosis in human hearts. This is linked to decreased transcription and activity of glutathione peroxidase-4 (GPX4), influenced by reduced levels of activating transcription factor-4 (ATF4) and nuclear factor erythroid-2-related factor-2 (NRF2), and downregulation of glutathione reductase (GSR). Additionally, diabetic hearts showed an increased labile iron pool due to enhanced heme metabolism by heme oxygenase-1 (HMOX1), elevated iron import via divalent metal transporter-1 (DMT1), reduced iron storage through ferritin light chain (FLC), and decreased iron export via ferroportin-1 (FPN1). The reduction in FPN1 levels likely results from decreased stabilization by amyloid precursor protein (APP) and diminished NRF2-mediated transcription. Furthermore, diabetes upregulates lysophosphatidylcholine acyltransferase-3 (LPCAT3), facilitating the integration of polyunsaturated fatty acids (PUFA) into phospholipid membranes, and downregulates acyl-CoA thioesterase-1 (ACOT1), which further promotes ferroptosis. LC-MS/MS analysis identified several novel proteins implicated in diabetes-induced cardiac ferroptosis, including upregulated ceruloplasmin, which enhances iron metabolism, and cytochrome b-245 heavy chain (CYBB), a key component of NADPH oxidase that aids in the production of reactive oxygen species (ROS), along with downregulated voltage-dependent anion-selective channel protein-2 (VDAC2), essential for maintaining mitochondrial membrane potential. In conclusion, our study not only confirms the presence and potentially predominant role of cardiac ferroptosis in humans with diabetic heart failure but also elucidates its molecular mechanisms, offering potential therapeutic targets to mitigate heart failure complications in diabetic patients.

Exogenous Hydrogen Sulfide Prevents Necroptosis by Inhibiting p38MAPK Pathway Activation in JEG-3 Trophoblast Cells: A Role in Preeclampsia

OBJECTIVES

Necroptosis, a form of programmed cell death, can occur in the placenta of patients with preeclampsia (PE). Hydrogen sulfide (H2S) can inhibit necroptosis of human umbilical vein endothelial cells under the high glucose-induced injury. Whether H2S can protect trophoblasts against necroptosis underlying PE has not been elucidated. This study aimed to explore the protective role of H2S in trophoblast cells against necroptosis underlying PE.

DESIGN

This is an in vitro experimental study.

PARTICIPANTS

A total of 10 pregnant women with severe PE and 10 matched control normotensive pregnant women were included. The placenta tissues were extracted from participators. The human JEG-3 trophoblasts were commercially available.

METHODS

The expression and localization of necrotic proteins were assayed in human placenta samples, and the effect of necrotic cell death on the proliferation and apoptosis of human JEG-3 trophoblasts was evaluated. The component expressions of inflammatory cytokine and p38MAPK signaling pathway were measured in samples pretreated with or without NaHS (H2S donor) and SB203580 (p38 inhibitor).

RESULTS

RIPA1, RIPA3, and p-p38 levels were significantly higher in PE placental tissue, whereas cystathionine β-synthase expression was decreased. In JEG-3 trophoblasts, necroptosis increased apoptotic cell numbers, suppressed cell proliferation, increased inflammatory cytokine expression, and increased p38MAPK activation, which can be prevented by NaHS.

LIMITATIONS

In the present study, we did not provide sufficient evidence that necroptosis was a part of the pathogenesis of PE.

CONCLUSIONS

We proposed the putative role of necroptosis in early-onset PE, reflected by the blockage of caspase-8/3 and increased expression of RIPA1 and RIPA3 in PE placenta tissues. Furthermore, we demonstrated that exogenous H2S protected cytotrophoblasts against ceramide-induced necroptosis via the p38MAPK pathway.

N-acetylcysteine combined with insulin attenuates myocardial injury in canines with type 1 diabetes mellitus by modulating TNF-α-mediated apoptotic pathways and affecting linear ubiquitination

The exact pathogenesis of type 1 diabetes mellitus (DM) is still unclear. Numerous organs, including the heart, will suffer damage and malfunction as a result of long-term hyperglycemia. Currently, insulin therapy alone is still not the best treatment for type 1 DM. In order to properly treat and manage patients with type 1 DM, it is vital to seek a combination that includes both insulin and additional medications. This study aims to explore the therapeutic effect and mechanism of N-acetylcysteine (NAC) combined with insulin on type 1 DM. By giving beagle canines injections of streptozotocin (STZ) and alloxan (ALX) (20 mg/kg each), a model of type 1 DM was created. The results showed that this combination could effectively control blood sugar level, improve heart function, avoid the damage of mitochondria and myocardial cells, and prevent the excessive apoptosis of myocardial cells. Importantly, the combination can activate nuclear factor kappa-B (NF-κB) by promoting linear ubiquitination of receptor-interacting protein kinase 1 (RIPK1) and NF-κB-essential modulator (NEMO) and inhibitor of NF-κB (IκB) phosphorylation. The combination can increase the transcription and linear ubiquitination of Cellular FLICE (FADD-like IL-1β-converting enzyme) -inhibitory protein (c-FLIP), diminish the production of cleaved-caspase-8 p18 and cleaved-caspase-3 to reduce apoptosis. This study confirmed that NAC combined with insulin can promote the linear ubiquitination of RIPK1, NEMO and c-FLIP and regulate the apoptosis pathway mediated by TNF-α to attenuate the myocardial injury caused by type 1 DM. Meanwhile, the research served as a resource when choosing a clinical strategy for DM cardiac complications.

Ironing out the details: ferroptosis and its relevance to diabetic cardiomyopathy

Ferroptosis is a newly identified myocardial cell death mechanism driven by iron-dependent lipid peroxidation. The presence of elevated intramyocardial lipid levels and excessive iron in patients with diabetes suggest a predominant role of ferroptosis in diabetic cardiomyopathy. As myocardial cell death is a precursor of heart failure, and intensive glycemic control cannot abate the increased risk of heart failure in patients with diabetes, targeting myocardial cell death via ferroptosis is a promising therapeutic avenue to prevent and/or treat diabetic cardiomyopathy. This review provides updated and comprehensive molecular mechanisms underpinning ferroptosis, clarifies several misconceptions about ferroptosis, emphasizes the importance of ferroptosis in diabetes-induced myocardial cell death, and offers valuable approaches to evaluate and target ferroptosis in the diabetic heart. Furthermore, basic concepts and ideas presented in this review, including glutathione peroxidase-4-independent and mitochondrial mechanisms of ferroptosis, are also important for investigating ferroptosis in other diabetic organs, as well as nondiabetic and metabolically compromised hearts.

Protective effect of canagliflozin on post-resuscitation myocardial function in a rat model of cardiac arrest

BACKGROUND

Currently, most patients with cardiac arrest (CA) show reversible myocardial dysfunction, hemodynamic instability, systemic inflammation and other pathophysiological state in early stage of resuscitation, some patients may eventually progress to multiple organ failure. There is evidence that heart failure is the terminal stage in the development of various cardiovascular diseases. Although the cardio-protective effect of canagliflozin (CANA) has been confirmed in large clinical studies and recommended in domestic and international heart failure-related guidelines, the effectiveness of CANA after resuscitation remains unclear. In this study, we constructed a modified CA/CPR rat model to investigate whether CANA administered on post-resuscitation improves myocardial function.

METHODS

Twenty-fourth healthy male Sprague-Dawley rats were randomized into four groups: (1) Sham + placebo group, (2) Sham + CANA group, (3) CPR + placebo group, and (4) CPR + CANA group. Ventricular fibrillation was induced by transcutaneous electrical stimulation on epicardium. After 6 min untreated ventricular fibrillation, chest compressions was initiated. The rats were received an injection of placebo or canagliflozin (3 ug/kg) randomly 15 min after restore of spontaneous circulation (ROSC). Electrocardiogram (ECG) and blood pressure were continuously detected in each group throughout the experiment. The rats were killed 6 h after ROSC to collected the arterial serum and myocardial tissue. Myocardial injury was estimated with concentrations of inflammatory factors, oxidative stress indexes and, apoptosis index, myocardial injury markers, echocardiography and myocardial pathological slices.

RESULTS

After resuscitation, mean arterial pressure (MAP) were significantly increased after cardiopulmonary resuscitation in CANA group rats when compared with placebo group. Heart rate, body lactate returned and left ventricular ejection fraction (LVEF) to normal levels in a shorter time and the myocardial injury was obviously attenuated in CPR + CANA group. Inflammatory factors (IL-6, TNF-α) and oxidative stress indexes (MAD, SOD, CAT) were dramatically decreased with the administration of CANA. The expression of apoptosis index (BAX, caspase-3) were higher in CPR + placebo group and the expression of anti-apoptosis index (Bcl-2) was lower (P < 0.05).

CONCLUSIONS

The administration of CANA effectively reduces myocardial ischaemia/reperfusion (I/R) injury after cardiac arrest and cardiopulmonary resuscitation (CPR), and the underlying mechanism may be related to anti-inflammation, oxidative stress and apoptosis.

Health position paper and redox perspectives on reactive oxygen species as signals and targets of cardioprotection

The present review summarizes the beneficial and detrimental roles of reactive oxygen species in myocardial ischemia/reperfusion injury and cardioprotection. In the first part, the continued need for cardioprotection beyond that by rapid reperfusion of acute myocardial infarction is emphasized. Then, pathomechanisms of myocardial ischemia/reperfusion to the myocardium and the coronary circulation and the different modes of cell death in myocardial infarction are characterized. Different mechanical and pharmacological interventions to protect the ischemic/reperfused myocardium in elective percutaneous coronary interventions and coronary artery bypass grafting, in acute myocardial infarction and in cardiotoxicity from cancer therapy are detailed. The second part keeps the focus on ROS providing a comprehensive overview of molecular and cellular mechanisms involved in ischemia/reperfusion injury. Starting from mitochondria as the main sources and targets of ROS in ischemic/reperfused myocardium, a complex network of cellular and extracellular processes is discussed, including relationships with Ca2+ homeostasis, thiol group redox balance, hydrogen sulfide modulation, cross-talk with NAPDH oxidases, exosomes, cytokines and growth factors. While mechanistic insights are needed to improve our current therapeutic approaches, advancements in knowledge of ROS-mediated processes indicate that detrimental facets of oxidative stress are opposed by ROS requirement for physiological and protective reactions. This inevitable contrast is likely to underlie unsuccessful clinical trials and limits the development of novel cardioprotective interventions simply based upon ROS removal.

Role of RIPK3‑CaMKII‑mPTP signaling pathway‑mediated necroptosis in cardiovascular diseases (Review)

Necroptosis, which is distinct from apoptosis and necrosis, serves a crucial role in ontogeny and the maintenance of homeostasis. In the last decade, it has been demonstrated that the pathogenesis of cardiovascular diseases is also linked to necroptosis. Receptor interaction protein kinase (RIPK) 1, RIPK3 and mixed lineage kinase domain‑like protein serve vital roles in necroptosis. In addition to the aforementioned necroptosis‑related components, calcium/calmodulin‑dependent protein kinase II (CaMKII) has been identified as a novel substrate for RIPK3 that promotes the opening of the mitochondrial permeability transition pore (mPTP), and thus, mediates necroptosis of myocardial cells through the RIPK3‑CaMKII‑mPTP signaling pathway. The present review provides an overview of the current knowledge of the RIPK3‑CaMKII‑mPTP‑mediated necroptosis signaling pathway in cardiovascular diseases, focusing on the role of the RIPK3‑CaMKII‑mPTP signaling pathway in acute myocardial infarction, ischemia‑reperfusion injury, heart failure, abdominal aortic aneurysm, atherosclerosis, diabetic cardiomyopathy, hypertrophic cardiomyopathy, atrial fibrillation, and the cardiotoxicity associated with antitumor drugs and other chemicals. Finally, the present review discusses the research status of drugs targeting the RIPK3‑CaMKII‑mPTP signaling pathway.

Recent advances in the role of endogenous hydrogen sulphide in cancer cells

Hydrogen sulphide (H2 S) is a gaseous neurotransmitter that can be self-synthesized by living organisms. With the deepening of research, the pathophysiological mechanisms of endogenous H2 S in cancer have been increasingly elucidated: (1) promote angiogenesis, (2) stimulate cell bioenergetics, (3) promote migration and proliferation thereby invasion, (4) inhibit apoptosis and (5) activate abnormal cell cycle. However, the increasing H2 S levels via exogenous sources show the opposite trend. This phenomenon can be explained by the bell-shaped pharmacological model of H2 S, that is, the production of endogenous (low concentration) H2 S promotes tumour growth while the exogenous (high concentration) H2 S inhibits tumour growth. Here, we review the impact of endogenous H2 S synthesis and metabolism on tumour progression, summarize the mechanism of action of H2 S in tumour growth, and discuss the possibility of H2 S as a potential target for tumour treatment.

Therapeutic Potential of Hibiscus sabdariffa Linn. in Attenuating Cardiovascular Risk Factors

Cardiovascular diseases (CVDs) represent a broad spectrum of diseases afflicting the heart and blood vessels and remain a major cause of death and disability worldwide. CVD progression is strongly associated with risk factors, including hypertension, hyperglycemia, dyslipidemia, oxidative stress, inflammation, fibrosis, and apoptosis. These risk factors lead to oxidative damage that results in various cardiovascular complications including endothelial dysfunctions, alterations in vascular integrity, the formation of atherosclerosis, as well as incorrigible cardiac remodeling. The use of conventional pharmacological therapy is one of the current preventive measures to control the development of CVDs. However, as undesirable side effects from drug use have become a recent issue, alternative treatment from natural products is being sought in medicinal plants and is gaining interest. Roselle (Hibiscus sabdariffa Linn.) has been reported to contain various bioactive compounds that exert anti-hyperlipidemia, anti-hyperglycemia, anti-hypertension, antioxidative, anti-inflammation, and anti-fibrosis effects. These properties of roselle, especially from its calyx, have relevance to its therapeutic and cardiovascular protection effects in humans. This review summarizes the findings of recent preclinical and clinical studies on roselle as a prophylactic and therapeutic agent in attenuating cardiovascular risk factors and associated mechanisms.

Hydrogen sulfide attenuates uranium-induced kidney cells pyroptosis via upregulation of PI3K/AKT/mTOR signaling

We have identified that hydrogen sulfide (H₂ S), a gaseous mediator, plays a crucial role in antioxidative, anti-inflammatory, and cytoprotective effects on uranium (U)-triggered rat nephrotoxicity. Pyroptosis is a special mode of inflammation and programmed cell death involved in the activation of inflammasome and Caspase-1 and the release of inflammatory cytokines. This study aims to confirm whether H₂ S can alleviate U-induced rat NRK-52^E cell pyroptosis and to investigate the H₂ S underlying regulatory mechanism. Our results indicate that pretreatment with NaHS (an H₂ S donor) significantly inhibited U-increased reactive oxygen species level, NLRP3, apoptosis-related speck-like protein consisting of a caspase recruitment domain (ASC), and cleaved Caspase-1 proteins expression, gasdermin D messenger RNA (GSDMD mRNA) expression, interleukin (IL)-1β and IL-18 contents, lactate dehydrogenase leakage, and numbers of double-positive dying kidney cells. NaHS application evidently augmented phosphorylated PI3K, AKT, and mTOR expression as well as ratios of their respective phosphorylation to the corresponding total proteins which were downregulated by U treatment. But, LY294002 (a PI3K inhibitor) administration effectively abrogated the consequences of NaHS on the levels of p-PI3K, cleaved Caspase-1, ASC and NLRP3 proteins, GSDMD mRNA expression, and (IL)-1β and IL-18 contents. Simultaneously, LY294002 significantly reversed the effects of NaHS on U-induced pyroptosis rate and cytotoxicity. Taken together, these results indicate that H₂ S ameliorated U-triggered NRK-52^E cells pyroptosis via upregulation of PI3K/AKT/mTOR pathway, suggesting a novel role for H₂ S in the management of nephrotoxicity caused by U exposure.

Hydrogen sulfide protects against ischemic heart failure by inhibiting RIP1/RIP3/MLKL-mediated necroptosis

The aim of the present study was to explore whether hydrogen sulfide (H2S) protects against ischemic heart failure (HF) by inhibiting the necroptosis pathway. Mice were randomized into Sham, myocardial infarction (MI), MI + propargylglycine (PAG) and MI + sodium hydrosulfide (NaHS) group, respectively. The MI model was induced by ligating the left anterior descending coronary artery. PAG was intraperitoneally administered at a dose of 50 mg/kg/day for 4 weeks, and NaHS at a dose of 4mg/kg/day for the same period. At 4 weeks after MI, the following were observed: A significant decrease in the cardiac function, as evidenced by a decline in ejection fraction (EF) and fractional shortening (FS); an increase in plasma myocardial injury markers, such as creatine kinase-MB (CK-MB) and cardiac troponin I (cTNI); an increase in myocardial collagen content in the heart tissues; and a decrease of H2S level in plasma and heart tissues. Furthermore, the expression levels of necroptosis-related markers such as receptor interacting protein kinase 1 (RIP1), RIP3 and mixed lineage kinase domain-like protein (MLKL) were upregulated after MI. NaHS treatment increased H2S levels in plasma and heart tissues, preserving the cardiac function by increasing EF and FS, decreasing plasma CK-MB and cTNI and reducing collagen content. Additionally, NaHS treatment significantly downregulated the RIP1/RIP3/MLKL pathway. While, PAG treatment aggravated cardiac function by activated the RIP1/RIP3/MLKL pathway. Overall, the present study concluded that H2S protected against ischemic HF by inhibiting RIP1/RIP3/MLKL-mediated necroptosis which could be a potential target treatment for ischemic HF.

Independent and combined effects of liraglutide and aerobic interval training on glycemic control and cardiac protection in diabetic cardiomyopathy rats

OBJECTIVE

This study intended to explore the hypoglycemic and cardioprotective effects of 8-week aerobic interval training combined with liraglutide and elucidate the underlying mechanisms.

METHOD

Male Wistar rats were randomly divided into 5 groups - normal control group (CON), diabetic cardiomyopathy group (DCM), high-dose liraglutide group (DH), low-dose liraglutide group (DL), and aerobic interval training combined with liraglutide group (DLE). High-fat diet and streptozotocin (STZ) were used to induce the DCM model, and both the liraglutide administration group and combination therapy group allocated to 8 weeks of either liraglutide or liraglutide and exercise intervention. Cardiac functions were analyzed by electrocardiography. Blood biochemical parameters were measured to judge glycemic control conditions. Hematoxylin and eosin (HE) staining and Sirus red staining was used to identify cardiac morphology and collagen accumulation, respectively. Advanced glycation end products (AGEs) were determined by enzymatic methods. The mRNA expression of myocardial remodeling genes (BNP, GSK3β, α-MHC, β-MHC and PPARα) and the protein expression of GLP-1, GLP-1R were analyzed.

RESULTS

DCM rats developed hyperglycemia, impaired cardiac function with accumulation of AGEs and collagen (P < 0.05). The development of hyperglycemia and cardiac dysfunction was significantly attenuated with all interventions, as reduced cardiac fibrosis and improved cardiac function (P < 0.05). Cardiac remodeling genes were normalized after all interventions, these positive modifications were due to increased GLP-1 and GLP-1R expression in DCM heart (P < 0.05). Liraglutide combined with AIT significantly increased the diameters of cardiomyocytes, increased the α-MHC expressionx, reduced PPARαexpression and reduced the fluctuation of blood glucose level, which showed the safety and effective of medicine combined with exercise.

CONCLUSION

Liraglutide combined with AIT intervention normalized blood glucose alleviates myocardial fibrosis and improves cardiac contractile function in DCM rats, supporting the efficacy and safety of the combination therapy.

Hydrogen Sulfide: A Gaseous Mediator and Its Key Role in Programmed Cell Death, Oxidative Stress, Inflammation and Pulmonary Disease

Hydrogen sulfide (H2S) has been acknowledged as a novel gaseous mediator. The metabolism of H2S in mammals is tightly controlled and is mainly achieved by many physiological reactions catalyzed by a suite of enzymes. Although the precise actions of H2S in regulating programmed cell death, oxidative stress and inflammation are yet to be fully understood, it is becoming increasingly clear that H2S is extensively involved in these crucial processes. Since programmed cell death, oxidative stress and inflammation have been demonstrated as three important mechanisms participating in the pathogenesis of various pulmonary diseases, it can be inferred that aberrant H2S metabolism also functions as a critical contributor to pulmonary diseases, which has also been extensively investigated. In the meantime, substantial attention has been paid to developing therapeutic approaches targeting H2S for pulmonary diseases. In this review, we summarize the cutting-edge knowledge on the metabolism of H2S and the relevance of H2S to programmed cell death, oxidative stress and inflammation. We also provide an update on the crucial roles played by H2S in the pathogenesis of several pulmonary diseases. Finally, we discuss the perspective on targeting H2S metabolism in the treatment of pulmonary diseases.

Hydrogen sulfide protects against ischemic heart failure by inhibiting RIP1/RIP3/MLKL-mediated necroptosis

The aim of the present study was to explore whether hydrogen sulfide (H2S) protects against ischemic heart failure (HF) by inhibiting the necroptosis pathway. Mice were randomized into Sham, myocardial infarction (MI), MI + propargylglycine (PAG) and MI + sodium hydrosulfide (NaHS) group, respectively. The MI model was induced by ligating the left anterior descending coronary artery. PAG was intraperitoneally administered at a dose of 50 mg/kg/day for 4 weeks, and NaHS at a dose of 4 mg/kg/day for the same period. At 4 weeks after MI, the following were observed: A significant decrease in the cardiac function, as evidenced by a decline in ejection fraction (EF) and fractional shortening (FS); an increase in plasma myocardial injury markers, such as creatine kinase-MB (CK-MB) and cardiac troponin I (cTNI); an increase in myocardial collagen content in the heart tissues; and a decrease of H2S level in plasma and heart tissues. Furthermore, the expression levels of necroptosis-related markers such as receptor interacting protein kinase 1 (RIP1), RIP3 and mixed lineage kinase domain-like protein (MLKL) were upregulated after MI. NaHS treatment increased H2S levels in plasma and heart tissues, preserving the cardiac function by increasing EF and FS, decreasing plasma CK-MB and cTNI and reducing collagen content. Additionally, NaHS treatment significantly downregulated the RIP1/RIP3/MLKL pathway. While, PAG treatment aggravated cardiac function by activated the RIP1/RIP3/MLKL pathway. Overall, the present study concluded that H2S protected against ischemic HF by inhibiting RIP1/RIP3/MLKL-mediated necroptosis which could be a potential target treatment for ischemic HF.

Hydrogen sulfide poisoning in forensic pathology and toxicology: mechanism and metabolites quantification analysis

Historically, hydrogen sulfide (H₂S) poisoning has extremely high and irreparable mortality. Currently, the identification of H₂S poisoning needs to combine with the case scene analysis in forensic medicine. The anatomy of the deceased seldom had obvious features. There are also a few reports about H₂S poisoning in detail. As a result, we give a comprehensive analysis of the related knowledge on the forensic aspect of H₂S poisoning. Furthermore, we provide the analytical methods of H₂S and its metabolite-which may assist in H₂S poisoning identification.

Spotlight on pyroptosis: role in pathogenesis and therapeutic potential of ocular diseases

Pyroptosis is a programmed cell death characterized by swift plasma membrane disruption and subsequent release of cellular contents and pro-inflammatory mediators (cytokines), including IL‐1β and IL‐18. It differs from other types of programmed cell death such as apoptosis, autophagy, necroptosis, ferroptosis, and NETosis in terms of its morphology and mechanism. As a recently discovered form of cell death, pyroptosis has been demonstrated to be involved in the progression of multiple diseases. Recent studies have also suggested that pyroptosis is linked to various ocular diseases. In this review, we systematically summarized and discussed recent scientific discoveries of the involvement of pyroptosis in common ocular diseases, including diabetic retinopathy, age-related macular degeneration, AIDS-related human cytomegalovirus retinitis, glaucoma, dry eye disease, keratitis, uveitis, and cataract. We also organized new and emerging evidence suggesting that pyroptosis signaling pathways may be potential therapeutic targets in ocular diseases, hoping to provide a summary of overall intervention strategies and relevant multi-dimensional evaluations for various ocular diseases, as well as offer valuable ideas for further research and development from the perspective of pyroptosis.

Recent Advances in Molecular Research on Hydrogen Sulfide (H2S) Role in Diabetes Mellitus (DM)-A Systematic Review

Abundant experimental data suggest that hydrogen sulfide (H₂S) is related to the pathophysiology of Diabetes Mellitus (DM). Multiple molecular mechanisms, including receptors, membrane ion channels, signalingmolecules, enzymes, and transcription factors, are known to be responsible for the H₂S biological actions; however, H₂S is not fully documented as a gaseous signaling molecule interfering with DM and vascular-linked pathology. In recent decades, multiple approaches regarding therapeutic exploitation of H₂S have been identified, either based on H₂S exogenous apport or on its modulated endogenous biosynthesis. This paper aims to synthesize and systematize, as comprehensively as possible, the recent literature-related data regarding the therapeutic/rehabilitative role of H₂S in DM. This review was conducted following the “Preferred reporting items for systematic reviews and meta-analyses” (PRISMA) methodology, interrogating five international medically renowned databases by specific keyword combinations/“syntaxes” used contextually, over the last five years (2017–2021). The respective search/filtered and selection methodology we applied has identified, in the first step, 212 articles. After deploying the next specific quest steps, 51 unique published papers qualified for minute analysis resulted. To these bibliographic resources obtained through the PRISMA methodology, in order to have the best available information coverage, we added 86 papers that were freely found by a direct internet search. Finally, we selected for a connected meta-analysis eight relevant reports that included 1237 human subjects elicited from clinical trial registration platforms. Numerous H₂S releasing/stimulating compounds have been produced, some being used in experimental models. However, very few of them were further advanced in clinical studies, indicating that the development of H₂S as a therapeutic agent is still at the beginning.

RIPK1-RIPK3 mediates myocardial fibrosis in type 2 diabetes mellitus by impairing autophagic flux of cardiac fibroblasts

Receptor-interacting protein kinase 1 (RIPK1) and 3 (RIPK3) are critical regulators of programmed necrosis or necroptosis. However, the role of the RIPK1/RIPK3 signaling pathway in myocardial fibrosis and related diabetic cardiomyopathy is still unclear. We hypothesized that RIPK1/RIPK3 activation mediated myocardial fibrosis by impairing the autophagic flux. To this end, we established in vitro and in vivo models of type 2 diabetes mellitus with high glucose fat (HGF) medium and diet respectively. HGF induced myocardial fibrosis, and impaired cardiac diastolic and systolic function by activating the RIPK1/RIPK3 pathway, which increased the expression of autophagic related proteins such as LC3-II, P62 and active-cathepsin D. Inhibition of RIPK1 or RIPK3 alleviated HGF-induced death and fibrosis of cardiac fibroblasts by restoring the impaired autophagic flux. The autophagy blocker neutralized the effects of the RIPK1 inhibitor necrostatin-1 (Nec-1) and RIPK3 inhibitor GSK872 (GSK). RIPK1/RIPK3 inhibition respectively decreased the levels of RIPK3/p-RIPK3 and RIPK1/p-RIPK1. P62 forms a complex with RIPK1-RIPK3 and promotes the binding of RIPK1 and RIPK3, silencing of RIPK1 decreased the association of RIPK1 with P62 and the binding of P62 to LC3. Furthermore, inhibition of both kinases in combination with a low dose of Nec-1 and GSK in the HGF-treated fibroblasts significantly decreased cell death and fibrosis, and restored the autophagic flux. In the diabetic rat model, Nec-1 (1.65 mg/kg) treatment for 4 months markedly alleviated myocardial fibrosis, downregulated autophagic related proteins, and improved cardiac systolic and diastolic function. In conclusion, HGF induces myocardial fibrosis and cardiac dysfunction by activating the RIPK1-RIPK3 pathway and by impairing the autophagic flux, which is obviated by the pharmacological and genetic inhibition of RIPK1/RIPK3.

Preliminary evidence for the presence of multiple forms of cell death in diabetes cardiomyopathy

Diabetic mellitus (DM) is a common degenerative chronic metabolic disease often accompanied by severe cardiovascular complications (DCCs) as major causes of death in diabetic patients with diabetic cardiomyopathy (DCM) as the most common DCC. The metabolic disturbance in DCM generates the conditions/substrates and inducers/triggers and activates the signaling molecules and death executioners leading to cardiomyocyte death which accelerates the development of DCM and the degeneration of DCM to heart failure. Various forms of programmed active cell death including apoptosis, pyroptosis, autophagic cell death, autosis, necroptosis, ferroptosis and entosis have been identified and characterized in many types of cardiac disease. Evidence has also been obtained for the presence of multiple forms of cell death in DCM. Most importantly, published animal experiments have demonstrated that suppression of cardiomyocyte death of any forms yields tremendous protective effects on DCM. Herein, we provide the most updated data on the subject of cell death in DCM, critical analysis of published results focusing on the pathophysiological roles of cell death, and pertinent perspectives of future studies.

Development of an Electrochemical Dual H2S/Ca2+ Microsensor and Its In Vivo Application to a Rat Seizure Model

A dual electrochemical microsensor was fabricated for concurrent monitoring of hydrogen sulfide (H₂S) and calcium ions (Ca²⁺), which are closely linked important signaling species involved in various physiological processes. The dual sensor was prepared using a dual recessed electrode consisting of two platinum (Pt) microdisks (50 μm in diameter). Each electrode was individually optimized for the best sensing ability toward a target analyte. One electrode (WE1, amperometric H₂S sensor) was modified with electrodeposition of Au and electropolymerized polyaniline coating. The other electrode (WE2, all-solid-state Ca²⁺-selective electrode) was composed of Ag/AgCl onto the recessed Pt disk formed via electrodeposition/chloridation, followed by silanization and Ca²⁺-selective membrane loading. The current of WE1 and the potential of WE2 in a dual sensor responded linearly to H₂S concentration and logarithm of Ca²⁺ concentration, respectively, without a crosstalk between the sensing signals. Both WE1 and WE2 presented excellent sensitivity, selectivity (log⁡KH2S,iAmp≤-3.5, i = CO, NO, O₂, NO₂^-, AP, AA, DA, and GABA; and log⁡KCa2+,jPot≤-3.2, j = Na⁺, K⁺, and Mg²⁺), and fast response time with reasonable stability (during ca. 6 h in vivo experiment). Particularly, WE2 prepared using a mixture of two ionophores (ETH1001 and ETH129) and two plasticizers (2-nitrophenyl octyl ether and bis(2-ethylhexyl) sebacate) showed a very shortened response time (t_R to attain the ΔE/Δt slope of 0.6 mV/min = 3.0 ± 0.2 s, n ≥ 10), a critically required factor for real-time analysis. The developed sensor was utilized for simultaneous real-time monitoring of H₂S and Ca²⁺ changes at the brain cortex surface of a living rat during spontaneous epileptic seizures induced by a cortical 4-aminopyridine injection. The dynamic changes of H₂S and Ca²⁺ were clearly observed in an intimate correlation with the electrophysiological recording of seizures, demonstrating the sensor feasibility of in vivo and real-time simultaneous measurements of H₂S and Ca²⁺.

An Updated Insight Into Molecular Mechanism of Hydrogen Sulfide in Cardiomyopathy and Myocardial Ischemia/Reperfusion Injury Under Diabetes

Cardiovascular diseases are the most common complications of diabetes, and diabetic cardiomyopathy is a major cause of people death in diabetes. Molecular, transcriptional, animal, and clinical studies have discovered numerous therapeutic targets or drugs for diabetic cardiomyopathy. Within this, hydrogen sulfide (H₂S), an endogenous gasotransmitter alongside with nitric oxide (NO) and carbon monoxide (CO), is found to play a critical role in diabetic cardiomyopathy. Recently, the protective roles of H₂S in diabetic cardiomyopathy have attracted enormous attention. In addition, H₂S donors confer favorable effects in myocardial infarction, ischaemia-reperfusion injury, and heart failure under diabetic conditions. Further studies have disclosed that multiplex molecular mechanisms are responsible for the protective effects of H₂S against diabetes-elicited cardiac injury, such as anti-oxidative, anti-apoptotic, anti-inflammatory, and anti-necrotic properties. In this review, we will summarize the current findings on H₂S biology and pharmacology, especially focusing on the novel mechanisms of H₂S-based protection against diabetic cardiomyopathy. Also, the potential roles of H₂S in diabetes-aggravated ischaemia-reperfusion injury are discussed.

Pyroptosis: A possible link between obesity-related inflammation and inflammatory diseases

The main manifestation of obesity is persistent low-level inflammation and insulin resistance, which is an important factor inducing or promoting other obesity-related diseases. As a proinflammatory programmed cell death, pyroptosis plays an important role, especially in the activation and regulation of the NLRP3 inflammasome pathway. Pyroptosis is associated with the pathogenesis of many chronic inflammatory diseases and is characterized by the formation of micropores in the plasma membrane and the release of a large number of proinflammatory cytokines. This article mainly introduces the main pathways and key molecules of pyroptosis and focuses on the phenomenon of pyroptosis in obesity. It is suggested that the regulation of pyroptosis-related targets may become a new potential therapy for the prevention and treatment of systemic inflammatory response caused by obesity, and we summarize the potential molecular substances that may be beneficial to obesity-related inflammatory diseases through target pyroptosis.

H2S signaling and extracellular matrix remodeling in cardiovascular diseases: A tale of tense relationship

Extracellular matrix (ECM) is a non-cellular three-dimensional macromolecular network that not only provides mechanical support but also transduces essential molecular signals in organ functions. ECM is constantly remodeled to control tissue homeostasis, responsible for cell adhesion, cell migration, cell-to-cell communication, and cell differentiation, etc. The dysregulation of ECM components contributes to various diseases, including cardiovascular diseases, fibrosis, cancer, and neurodegenerative diseases, etc. Aberrant ECM remodeling is initiated by various stress, such as oxidative stress, inflammation, ischemia, and mechanical stress, etc. Hydrogen sulfide (H₂S) is a gasotransmitter that exhibits a wide variety of cytoprotective and physiological functions through its anti-oxidative and anti-inflammatory actions. Amounting research shows that H₂S can attenuate aberrant ECM remodeling. In this review, we discussed the implications and mechanisms of H₂S in the regulation of ECM remodeling in cardiovascular diseases, and highlighted the potential of H₂S in the prevention and treatment of cardiovascular diseases through attenuating adverse ECM remodeling.

Hydrogen sulfide plays a potential alternative for the treatment of metabolic disorders of diabetic cardiomyopathy

Diabetic cardiomyopathy (DCM) is a cardiovascular complication that tends to occur in patients with diabetes, obesity, or insulin resistance, with a higher late mortality rate. Sustained hyperglycemia, increased free fatty acids, or insulin resistance induces metabolic disorders in cardiac tissues and cells, leading to myocardial fibrosis, left ventricular hypertrophy, diastolic and/or systolic dysfunction, and finally develop into congestive heart failure. The close connection between all signaling pathways and the complex pathogenesis of DCM cause difficulties in finding effective targets for the treatment of DCM. It reported that hydrogen sulfide (H₂S) could regulate cell energy substrate metabolism, reduce insulin resistance, protect cardiomyocytes, and improve myocardial function by acting on related key proteins such as differentiation cluster 36 (CD36) and glucose transporter 4 (GLUT4). In this article, the relative mechanisms of H₂S in alleviating metabolic disorders of DCM were reviewed, and how H₂S can better prevent and treat DCM in clinical practice will be discussed.

The role of regulated necrosis in endocrine diseases

The death of endocrine cells is involved in type 1 diabetes mellitus, autoimmunity, adrenopause and hypogonadotropism. Insights from research on basic cell death have revealed that most pathophysiologically important cell death is necrotic in nature, whereas regular metabolism is maintained by apoptosis programmes. Necrosis is defined as cell death by plasma membrane rupture, which allows the release of damage-associated molecular patterns that trigger an immune response referred to as necroinflammation. Regulated necrosis comes in different forms, such as necroptosis, pyroptosis and ferroptosis. In this Perspective, with a focus on the endocrine environment, we introduce these cell death pathways and discuss the specific consequences of regulated necrosis. Given that clinical trials of necrostatins for the treatment of autoimmune conditions have already been initiated, we highlight the therapeutic potential of such novel therapeutic approaches that, in our opinion, should be tested in endocrine disorders in the future.

Xinyang Tablet inhibits MLK3-mediated pyroptosis to attenuate inflammation and cardiac dysfunction in pressure overload

ETHNOPHARMACOLOGICAL RELEVANCE

Xinyang tablet (XYT) has been traditionally used in the treatment of cardiovascular diseases (CVDs). Our previous study indicated that XYT exhibited protective effects in heart failure (HF).

AIM OF THE STUDY

The aim of the present study was to determine the protective effects of XYT in pressure overload induced HF and to elucidate its underlying mechanisms of action.

MATERIALS AND METHODS

We analyzed XYT content using high-performance liquid chromatography (HPLC.). Mice were subjected to transverse aortic constriction (TAC) to generate pressure overload-induced cardiac remodeling and were then orally administered XYT or URMC-099 for 1 week after the operation. HL1 mouse cardiomyoblasts were induced by lipopolysaccharides (LPS) to trigger pyroptosis and were then treated with XYT or URMC-099. We used echocardiography (ECG), hematoxylin and eosin (H&E) staining, Masson's trichrome staining and a terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling (TUNEL) assay to evaluate the effects of XYT. Messenger ribonucleic acid (mRNA) levels of collagen metabolism biomarkers and inflammation-related factors were detected. We determined protein levels of inflammation- and pyroptosis-related signaling pathway members via Western blot (WB). Caspase-1 activity was measured in cell lysate using a Caspase-1 Activity Assay Kit. Subsequently, to define the candidate ingredients in XYT that regulate mixed-lineage kinase-3 (MLK3), we used molecular docking (MD) to predict and evaluate binding affinity with MLK3. Finally, we screened 24 active potential compounds that regulate MLK3 via MD.

RESULTS

ECG, H&E staining, Masson's trichrome staining and TUNEL assay results showed that XYT remarkably improved heart function, amelorated myocardial fibrosis and inhibited apoptosis in vivo. Moreover, it reduced expression of proteins or mRNAs related to collagen metabolism, including collagen type 1 (COL1), fibronectin (FN), alpha smooth-muscle actin (α-SMA), and matrix metalloproteinases-2 and -9 (MMP-2, MMP-9). XYT also inhibited inflammation and the induction of pyroptosis at an early stage, as well as attenuated inflammation and pyroptosis levels in vitro.

CONCLUSION

Our data indicated that XYT exerted protective effects against pressure overload induced myocardial fibrosis (MF), which might be associated with the induction of pyroptosis-mediated MLK3 signaling.

The Hidden Role of Hydrogen Sulfide Metabolism in Cancer

Hydrogen Sulfide (H₂S), an endogenously produced gasotransmitter, is involved in various important physiological and disease conditions, including vasodilation, stimulation of cellular bioenergetics, anti-inflammation, and pro-angiogenesis. In cancer, aberrant up-regulation of H₂S-producing enzymes is frequently observed in different cancer types. The recognition that tumor-derived H₂S plays various roles during cancer development reveals opportunities to target H₂S-mediated signaling pathways in cancer therapy. In this review, we will focus on the mechanism of H₂S-mediated protein persulfidation and the detailed information about the dysregulation of H₂S-producing enzymes and metabolism in different cancer types. We will also provide an update on mechanisms of H₂S-mediated cancer progression and summarize current options to modulate H₂S production for cancer therapy.

Hydrogen Sulfide Plays an Important Role in Diabetic Cardiomyopathy

Diabetic cardiomyopathy is an important complication of diabetes mellitus and the main cause of diabetes death. Diabetic cardiomyopathy is related with many factors, such as hyperglycemia, lipid accumulation, oxidative stress, myocarditis, and apoptosis. Hydrogen sulfide (H₂S) is a newly discovered signal molecule, which plays an important role in many physiological and pathological processes. Recent studies have shown that H₂S is involved in improving diabetic cardiomyopathy, but its mechanism has not been fully elucidated. This review summarizes the research on the roles and mechanisms of H₂S in diabetic cardiomyopathy in recent years to provide the basis for in-depth research in the future.

MiR-21-3p triggers cardiac fibroblasts pyroptosis in diabetic cardiac fibrosis via inhibiting androgen receptor

AIMS/HYPOTHESIS

MicroRNA-21 has been implicated in diabetic complication, including diabetic cardiomyopathy. However, there is limited information regarding the biological role of the miR-21 passenger strand (miR-21-3p) in diabetic cardiac fibrosis. The aim of this study was to investigate the role of miR-21-3p and its target androgen receptor in STZ-induced diabetic cardiac fibrosis.

METHODS

The pathological changes and collagen depositions was analyzed by HE, Sirius Red staining and Masson's Trichrome Staining. MiR-21-3p, AR, NLRP3, caspase1 and collagen I expression were analyzed by western blotting, immunohistochemistry, immunofluorescence, qRT-PCR, miR one step qRT-PCR, respectively. A luciferase reporter assay was used to verify the interaction between miR-21 and the 3' untranslated region (3'UTR) of AR.

RESULTS

Our results indicated that miR-21-3p level was up-regulated, while AR was decreased in STZ-induced diabetic cardiac fibrosis tissues and cardiac fibroblast. High glucose triggers cardiac fibroblasts pyroptosis and collagen deposition. Gain-of-function and loss-of-function assays demonstrated that miR-21-3p mediated the crucial role in diabetic cardiac fibrosis. Our results show that miR-21-3p bound to the 3'UTR of AR post-transcriptionally repressed its expression. We also found AR, which regulates cardiac fibroblasts pyroptosis and collagen deposition through caspase1 signaling.

CONCLUSIONS

/interpretation: Taken together, our study showed that miR-21-3p aggravates STZ-induced diabetic cardiac fibrosis through the caspase1 pathways by suppressing AR expression.

Oxymatrine Ameliorates Memory Impairment in Diabetic Rats by Regulating Oxidative Stress and Apoptosis: Involvement of NOX2/NOX4

Oxymatrine (OMT) is the major quinolizidine alkaloid extracted from the root of Sophora flavescens Ait and has been shown to exhibit a diverse range of pharmacological properties. The aim of the present study was to investigate the role of OMT in diabetic brain injury in vivo and in vitro. Diabetic rats were induced by intraperitoneal injection of a single dose of 65 mg/kg streptozotocin (STZ) and fed a high-fat and high-cholesterol diet. Memory function was assessed using a Morris water maze test. A SH-SY5Y cell injury model was induced by incubation with glucose (30 mM/l) to simulate damage in vitro. The serum fasting blood glucose, insulin, serum S100B, malondialdehyde (MDA), and superoxide dismutase (SOD) levels were analyzed using commercial kits. Morphological changes were observed using Nissl staining and electron microscopy. Cell apoptosis was assessed using Hoechst staining and TUNEL staining. NADPH oxidase (NOX) and caspase-3 activities were determined. The effects of NOX2 and NOX4 knockdown were assessed using small interfering RNA. The expression levels of NOX1, NOX2, and NOX4 were detected using reverse transcription-quantitative PCR and western blotting, and the levels of caspase-3 were detected using western blotting. The diabetic rats exhibited significantly increased plasma glucose, insulin, reactive oxygen species (ROS), S-100B, and MDA levels and decreased SOD levels. Memory function was determined by assessing the percentage of time spent in the target quadrant, the number of times the platform was crossed, escape latency, and mean path length and was found to be significantly reduced in the diabetic rats. Hyperglycemia resulted in notable brain injury, including histological changes and apoptosis in the cortex and hippocampus. The expression levels of NOX2 and NOX4 were significantly upregulated at the protein and mRNA levels, and NOX1 expression was not altered in the diabetic rats. NOX and caspase-3 activities were increased, and caspase-3 expression was upregulated in the brain tissue of diabetic rats. OMT treatment dose-dependently reversed behavioral, biochemical, and molecular changes in the diabetic rats. In vitro, high glucose resulted in increases in reactive oxygen species (ROS), MDA levels, apoptosis, and the expressions of NOX2, NOX4, and caspase-3. siRNA-mediated knockdown of NOX2 and NOX4 decreased NOX2 and NOX4 expression levels, respectively, and reduced ROS levels and apoptosis. The results of the present study suggest that OMT alleviates diabetes-associated cognitive decline, oxidative stress, and apoptosis via NOX2 and NOX4 inhibition.

ROS-associated immune response and metabolism: a mechanistic approach with implication of various diseases

The immune system plays a pivotal role in maintaining the defense mechanism against external agents and also internal danger signals. Metabolic programming of immune cells is required for functioning of different subsets of immune cells under different physiological conditions. The field of immunometabolism has gained ground because of its immense importance in coordination and balance of immune responses. Metabolism is very much related with production of energy and certain by-products. Reactive oxygen species (ROS) are generated as one of the by-products of various metabolic pathways. The amount, localization of ROS and redox status determine transcription of genes, and also influences the metabolism of immune cells. This review discusses ROS, metabolism of immune cells at different cellular conditions and sheds some light on how ROS might regulate immunometabolism.

Exercise Training Promotes Cardiac Hydrogen Sulfide Biosynthesis and Mitigates Pyroptosis to Prevent High-Fat Diet-Induced Diabetic Cardiomyopathy

Obesity increases the risk of developing diabetes and subsequently, diabetic cardiomyopathy (DMCM). Reduced cardioprotective antioxidant hydrogen sulfide (H₂S) and increased inflammatory cell death via pyroptosis contribute to adverse cardiac remodeling and DMCM. Although exercise training (EX) has cardioprotective effects, it is unclear whether EX mitigates obesity-induced DMCM by increasing H₂S biosynthesis and mitigating pyroptosis in the heart. C57BL6 mice were fed a high-fat diet (HFD) while undergoing treadmill EX for 20 weeks. HFD mice developed obesity, hyperglycemia, and insulin resistance, which were reduced by EX. Left ventricle pressure-volume measurement revealed that obese mice developed reduced diastolic function with preserved ejection fraction, which was improved by EX. Cardiac dysfunction was accompanied by increased cardiac pyroptosis signaling, structural remodeling, and metabolic remodeling, indicated by accumulation of lipid droplets in the heart. Notably, EX increased cardiac H₂S concentration and expression of H₂S biosynthesis enzymes. HFD-induced obesity led to features of type 2 diabetes (T2DM), and subsequently DMCM. EX during the HFD regimen prevented the development of DMCM, possibly by promoting H₂S-mediated cardioprotection and alleviating pyroptosis. This is the first report of EX modulating H₂S and pyroptotic signaling in the heart.

Hydrogen Sulfide Ameliorates Homocysteine-Induced Cardiac Remodeling and Dysfunction

Patients with diabetes, a methionine-rich meat diet, or certain genetic polymorphisms show elevated levels of homocysteine (Hcy), which is strongly associated with the development of cardiovascular disease including diabetic cardiomyopathy. However, reducing Hcy levels with folate shows no beneficial cardiac effects. We have previously shown that a hydrogen sulfide (H₂S), a by-product of Hcy through transsulfuration by cystathionine beta synthase (CBS), donor mitigates Hcy-induced hypertrophy in cardiomyocytes. However, the in vivo cardiac effects of H₂S in the context of hyperhomocysteinemia (HHcy) have not been studied. We tested the hypothesis that HHcy causes cardiac remodeling and dysfunction in vivo, which is ameliorated by H₂S. Twelve-week-old male CBS^+/− (a model of HHcy) and sibling CBS^+/+ (WT) mice were treated with SG1002 (a slow release H₂S donor) diet for 4 months. The left ventricle of CBS^+/− mice showed increased expression of early remodeling signals c-Jun and c-Fos, increased interstitial collagen deposition, and increased cellular hypertrophy. Notably, SG1002 treatment slightly reduced c-Jun and c-Fos expression, decreased interstitial fibrosis, and reduced cellular hypertrophy. Pressure volume loop analyses in CBS^+/− mice revealed increased end systolic pressure with no change in stroke volume (SV) suggesting increased afterload, which was abolished by SG1002 treatment. Additionally, SG1002 treatment increased end-diastolic volume and SV in CBS^+/− mice, suggesting increased ventricular filling. These results demonstrate SG1002 treatment alleviates cardiac remodeling and afterload in HHcy mice. H₂S may be cardioprotective in conditions where H₂S is reduced and Hcy is elevated.