Role of hydrogen sulfide in endothelial dysfunction: Pathophysiology and therapeutic approaches

H2S prevents the disruption of the blood-brain barrier in rats with prenatal hyperhomocysteinemia

Elevation of the homocysteine concentration in the plasma called hyperhomocysteinemia (hHCY) during pregnancy causes a number of pre- and postnatal developmental disorders. The aim of our study was to analyze the effects of H2S donors -NaHS and N-acetylcysteine (NAC) on blood-brain barrier (BBB) permeability in rats with prenatal hHCY. In rats with mild hHCY BBB permeability assessed by Evans Blue extravasation in brain increased markedly throughout life. Administration of NaHS or NAC during pregnancy attenuated hHCY-associated damage and increased endogenous concentrations of sulfides in brain tissues. Acute application of dl-homocysteine thiolactone induced BBB leakage, which was prevented by the NMDA receptor antagonist MK-801 or H2S donors. Rats with hHCY demonstrated high levels of NO metabolite - nitrites and proinflammatory cytokines (IL-1β, TNF-α, IL-6) in brain. Lactate dehydrogenase (LDH) activity in the serum was higher in rats with hHCY. Mitochondrial complex-I activity was lower in brain of hHCY rats. NaHS treatment during pregnancy restored levels of proinflammatory cytokines, nitrites and activity of the respiratory chain complex in brain as well as the LDH activity in serum. Our data suggest that H2S has neuroprotective effects against prenatal hHCY-associated BBB disturbance providing a potential strategy for the prevention of developmental impairments in newborns.

Natural H2S-donors: A new pharmacological opportunity for the management of overweight and obesity

The prevalence of overweight and obesity has progressively increased in the last few years, becoming a real threat to healthcare systems. To date, the clinical management of body weight gain is an unmet medical need, as there are few approved anti-obesity drugs and most require an extensive monitoring and vigilance due to risk of adverse effects and poor patient adherence/persistence. Growing evidence has shown that the gasotransmitter hydrogen sulfide (H2S) and, therefore, H2S-donors could have a central role in the prevention and treatment of overweight/obesity. The main natural sources of H2S-donors are plants from the Alliaceae (garlic and onion), Brassicaceae (e.g., broccoli, cabbage, and wasabi), and Moringaceae botanical families. In particular, polysulfides and isothiocyanates, which slowly release H2S, derive from the hydrolysis of alliin from Alliaceae and glucosinolates from Brassicaceae/Moringaceae, respectively. In this review, we describe the emerging role of endogenous H2S in regulating adipose tissue function and the potential efficacy of natural H2S-donors in animal models of overweight/obesity, with a final focus on the preliminary results from clinical trials. We conclude that organosulfur-containing plants and their extracts could be used before or in combination with conventional anti-obesity agents to improve treatment efficacy and reduce inflammation in obesogenic conditions. However, further high-quality studies are needed to firmly establish their clinical efficacy.

Hydrogen sulfide protects the endometrium in a rat model of type 1 diabetes via modulation of PPARγ/mTOR and Nrf-2/NF-κb pathways

Diabetes is one of the leading causes of endometrial diseases in women. No study has addressed the influence of hydrogen sulphide (H2S) donors on endometrial injury on top of type 1 diabetes. This research was conducted to study either the effect of sodium hydrosulphide (NaHS), the H2S donor, or DL-propargylglycine (PAG), the inhibitor of endogenous H2S production, on the endometrium of diabetic rats. A total of 40 female Wistar rats were separated into control group, diabetic group, diabetic group treated with NaHS and diabetic group treated with PAG. Serum levels of insulin, glucose, total cholesterol (TC) and triglycerides (TG) were assessed. Uterine tissue markers of oxidative stress, inflammation, apoptosis and cell proliferation were analysed. Diabetes-induced endometrial overgrowth associated with oxidative stress, inflammation and inhibition of apoptosis. NaHS administration reversed the previous conditions while PAG administration got them worse. We concluded that H2S prevented endometrial overgrowth in a rat model of type 1 diabetes through modulation of PPARγ/mTOR and Nrf-2/NF-κB pathways.

Hydrogen Sulfide and Irisin, Potential Allies in Ensuring Cardiovascular Health

Irisin is a myokine secreted under the influence of physical activity and exposure to low temperatures and through different exogenous stimuli by the cleavage of its precursor, fibronectin type III domain-containing protein 5 (FNDC5). It is mainly known for maintaining of metabolic homeostasis, promoting the browning of white adipose tissue, the thermogenesis process, and glucose homeostasis. Growing experimental evidence suggests the possible central role of irisin in the regulation of cardiometabolic pathophysiological processes. On the other side, hydrogen sulfide (H2S) is well recognized as a pleiotropic gasotransmitter that regulates several homeostatic balances and physiological functions and takes part in the pathogenesis of cardiometabolic diseases. Through the S-persulfidation of cysteine protein residues, H2S is capable of interacting with crucial signaling pathways, exerting beneficial effects in regulating glucose and lipid homeostasis as well. H2S and irisin seem to be intertwined; indeed, recently, H2S was found to regulate irisin secretion by activating the peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α)/FNDC5/irisin signaling pathway, and they share several mechanisms of action. Their involvement in metabolic diseases is confirmed by the detection of their lower circulating levels in obese and diabetic subjects. Along with the importance of metabolic disorders, these modulators exert favorable effects against cardiovascular diseases, preventing incidents of hypertension, atherosclerosis, heart failure, myocardial infarction, and ischemia-reperfusion injury. This review, for the first time, aims to explore the role of H2S and irisin and their possible crosstalk in cardiovascular diseases, pointing out the main effects exerted through the common molecular pathways involved.

Investigating the impact of protein S-sulfhydration modification on vascular diseases: A comprehensive review

The post-translational modification of cysteine through redox reactions, especially S-sulfhydration, plays a critical role in regulating protein activity, interactions, and spatial arrangement. This review focuses on the impact of protein S-sulfhydration on vascular function and its implications in vascular diseases. Dysregulated S-sulfhydration has been linked to the development of vascular pathologies, including aortic aneurysms and dissections, atherosclerosis, and thrombotic diseases. The H2S signaling pathway and the enzyme cystathionine γ-lyase (CSE), which is responsible for H2S generation, are identified as key regulators of vascular function. Additionally, potential therapeutic targets for the treatment of vascular diseases, such as the H2S donor GYY4137 and the HDAC inhibitor entinostat, are discussed. The review also emphasizes the antithrombotic effects of H2S in regulating platelet aggregation and thrombosis. The aim of this review is to enhance our understanding of the function and mechanism of protein S-sulfhydration modification in vascular diseases, and to provide new insights into the clinical application of this modification.

Fetoplacental endothelial dysfunction in gestational diabetes mellitus and maternal obesity: A potential threat for programming cardiovascular disease

Gestational diabetes mellitus (GDM) and maternal obesity (MO) increase the risk of adverse fetal outcomes, and the incidence of cardiovascular disease later in life. Extensive research has been conducted to elucidate the underlying mechanisms by which GDM and MO program the offspring to disease. This review focuses on the role of fetoplacental endothelial dysfunction in programming the offspring for cardiovascular disease in GDM and MO pregnancies. We discuss how pre-existing maternal health conditions can lead to vascular dysfunction in the fetoplacental unit and the fetus. We also examine the role of fetoplacental endothelial dysfunction in impairing fetal cardiovascular system development and the involvement of nitric oxide and hydrogen sulfide in mediating fetoplacental vascular dysfunction. Furthermore, we suggest that the L-Arginine-Nitric Oxide and the Adenosine-L-Arginine-Nitric Oxide (ALANO) signaling pathways are pertinent targets for research. Despite significant progress in this area, there are still knowledge gaps that need to be addressed in future research.

Noncoding RNAs: Versatile regulators of endothelial dysfunction

Noncoding RNAs have recently emerged as versatile regulators of endothelial dysfunction in atherosclerosis, a chronic inflammatory disease characterized by the formation of plaques within the arterial walls. Through their ability to modulate gene expression, noncoding RNAs, including microRNAs, long noncoding RNAs, and circular RNAs, play crucial roles in various cellular processes involved in endothelial dysfunction (ECD), such as inflammation, pyroptosis, migration, proliferation, apoptosis, oxidative stress, and angiogenesis. This review provides an overview of the current understanding of the regulatory roles of noncoding RNAs in endothelial dysfunction during atherosclerosis. It highlights the specific noncoding RNAs that have been implicated in the pathogenesis of ECD, their target genes, and the mechanisms by which they contribute to ECD. Furthermore, we have reviewed the current therapeutics in atherosclerosis and explore their interaction with noncoding RNAs. Understanding the intricate regulatory network of noncoding RNAs in ECD may open up new opportunities for the development of novel therapeutic strategies to combat ECD.

Chemistry of Hydrogen Sulfide-Pathological and Physiological Functions in Mammalian Cells

Hydrogen sulfide (H2S) was recognized as a gaseous signaling molecule, similar to nitric oxide (-NO) and carbon monoxide (CO). The aim of this review is to provide an overview of the formation of hydrogen sulfide (H2S) in the human body. H2S is synthesized by enzymatic processes involving cysteine and several enzymes, including cystathionine-β-synthase (CBS), cystathionine-γ-lyase (CSE), cysteine aminotransferase (CAT), 3-mercaptopyruvate sulfurtransferase (3MST) and D-amino acid oxidase (DAO). The physiological and pathological effects of hydrogen sulfide (H2S) on various systems in the human body have led to extensive research efforts to develop appropriate methods to deliver H2S under conditions that mimic physiological settings and respond to various stimuli. These functions span a wide spectrum, ranging from effects on the endocrine system and cellular lifespan to protection of liver and kidney function. The exact physiological and hazardous thresholds of hydrogen sulfide (H2S) in the human body are currently not well understood and need to be researched in depth. This article provides an overview of the physiological significance of H2S in the human body. It highlights the various sources of H2S production in different situations and examines existing techniques for detecting this gas.

Molecular Linkage between Immune System Disorders and Atherosclerosis

A strong relationship exists between immune dysfunction and cardiovascular disease. Immune dysregulation can promote the development of cardiovascular diseases as well as exacerbate their course. The disorders may occur due to the presence of primary immune defects (currently known as inborn errors of immunity) and the more common secondary immune deficiencies. Secondary immune deficiencies can be caused by certain chronic conditions (such as diabetes, chronic kidney disease, obesity, autoimmune diseases, or cancer), nutritional deficiencies (including both lack of nutrients and bioactive non-nutrient compounds), and medical treatments and addictive substances. This article unravels the molecular linkage between the aforementioned immune system disorders and atherosclerosis.

Mechanistic Intimate Insights into the Role of Hydrogen Sulfide in Alzheimer's Disease: A Recent Systematic Review

In the rapidly evolving field of Alzheimer's Disease (AD) research, the intricate role of Hydrogen Sulfide (H2S) has garnered critical attention for its diverse involvement in both pathological substrates and prospective therapeutic paradigms. While conventional pathophysiological models of AD have primarily emphasized the significance of amyloid-beta (Aβ) deposition and tau protein hyperphosphorylation, this targeted systematic review meticulously aggregates and rigorously appraises seminal contributions from the past year elucidating the complex mechanisms of H2S in AD pathogenesis. Current scholarly literature accentuates H2S's dual role, delineating its regulatory functions in critical cellular processes-such as neurotransmission, inflammation, and oxidative stress homeostasis-while concurrently highlighting its disruptive impact on quintessential AD biomarkers. Moreover, this review illuminates the nuanced mechanistic intimate interactions of H2S in cerebrovascular and cardiovascular pathology associated with AD, thereby exploring avant-garde therapeutic modalities, including sulfurous mineral water inhalations and mud therapy. By emphasizing the potential for therapeutic modulation of H2S via both donors and inhibitors, this review accentuates the imperative for future research endeavors to deepen our understanding, thereby potentially advancing novel diagnostic and therapeutic strategies in AD.

Persulfidation of mitoKv7.4 channels contributes to the cardioprotective effects of the H2S-donor Erucin against ischemia/reperfusion injury

BACKGROUND

Hydrogen sulfide (H2S) is a gasotransmitter deeply involved in cardiovascular homeostasis and implicated in the myocardial protection against ischemia/reperfusion. The post-translational persulfidation of cysteine residues has been identified as the mechanism through which H2S regulates a plethora of biological targets. Erucin (ERU) is an isothiocyanate produced upon hydrolysis of the glucosinolate glucoerucin, presents in edible plants of Brassicaceae family, such as Eruca sativa Mill., and it has emerged as a slow and long-lasting H2S-donor.

AIM

In this study the cardioprotective profile of ERU has been investigated and the action mechanism explored, focusing on the possible role of the recently identified mitochondrial Kv7.4 (mitoKv7.4) potassium channels.

RESULTS

Interestingly, ERU showed to release H2S and concentration-dependently protected H9c2 cells against H2O2-induced oxidative damage. Moreover, in in vivo model of myocardial infarct ERU showed protective effects, reducing the extension of ischemic area, the levels of troponin I and increasing the amount of total AnxA1, as well as co-related inflammatory outcomes. Conversely, the pre-treatment with XE991, a blocker of Kv7.4 channels, abolished them. In isolated cardiac mitochondria ERU exhibited the typical profile of a mitochondrial potassium channels opener, in particular, this isothiocyanate produced a mild depolarization of mitochondrial membrane potential, a reduction of calcium accumulation into the matrix and finally a flow of potassium ions. Finally, mitoKv7.4 channels were persulfidated in ERU-treated mitochondria.

CONCLUSIONS

ERU modulates the cardiac mitoKv7.4 channels and this mechanism may be relevant for cardioprotective effects.

Hydrogen sulfide ameliorates senescence in vascular endothelial cells through ameliorating inflammation and activating PPARδ/SGLT2/STAT3 signaling pathway

Mounting evidence demonstrates that hydrogen sulfide (H 2S) promotes anti-inflammatory molecules and inhibits pro-inflammatory cytokines in endothelial cells (ECs). This study aims to investigate the favorable action of H 2S on endothelial function in senescence by inhibiting the production of inflammatory molecules. Senescent ECs exhibit a reduction in H 2S, endothelial nitric oxide synthase (eNOS) and peroxisome proliferator-activated receptor δ (PPARδ), coupled with increased inflammatory molecules, sodium glucose transporter type 2 (SGLT2) and phosphorylation of STAT3, which could be reversed by the administration of a slow but sustained release agent of H 2S, GYY4137. Decreased production of eNOS and upregulated p-STAT3 and SGLT2 levels in senescent ECs are reversed by replenishment of the SGLT2 inhibitor EMPA and the PPARδ agonist GW501516. The PPARδ antagonist GSK0660 attenuates eNOS expression and increases the production of p-STAT3 and SGLT2. However, supplementation with GYY4137 has no beneficial effect on GSK0660-treated ECs. GYY4137, GW501516 and EMPA preserve endothelial-dependent relaxation (EDR) in D-gal-treated aortae, while GSK0660 destroys aortic relaxation even with GYY4137 supplementation. In summary, senescent ECs manifest aggravated the expressions of the inflammatory molecules SGLT2 and p-STAT3 and decreased the productions of PPARδ, eNOS and CSE. H 2S ameliorates endothelial dysfunction through the anti-inflammatory effect of the PPARδ/SGLT2/p-STAT3 signaling pathway in senescent ECs and may be a potential therapeutic target for anti-ageing treatment.

The Role of Hydrogen Sulfide (H2S) in Epigenetic Regulation of Neurodegenerative Diseases: A Systematic Review

This review explores the emerging role of hydrogen sulfide (H2S) in modulating epigenetic mechanisms involved in neurodegenerative diseases. Accumulating evidence has begun to elucidate the multifaceted ways in which H2S influences the epigenetic landscape and, subsequently, the progression of various neurodegenerative disorders, including Alzheimer's, Parkinson's, and Huntington's disease. H2S can modulate key components of the epigenetic machinery, such as DNA methylation, histone modifications, and non-coding RNAs, impacting gene expression and cellular functions relevant to neuronal survival, inflammation, and synaptic plasticity. We synthesize recent research that positions H2S as an essential player within this intricate network, with the potential to open new therapeutic avenues for these currently incurable conditions. Despite significant progress, there remains a considerable gap in our understanding of the precise molecular mechanisms and the potential therapeutic implications of modulating H2S levels or its downstream targets. We conclude by identifying future directions for research aimed at exploiting the therapeutic potential of H2S in neurodegenerative diseases.

Plants and Mushrooms as Possible New Sources of H2S Releasing Sulfur Compounds

Hydrogen sulfide (H2S), known for many decades exclusively for its toxicity and the smell of rotten eggs, has been re-discovered for its pleiotropic effects at the cardiovascular and non-cardiovascular level. Therefore, great attention is being paid to the discovery of molecules able to release H2S in a smart manner, i.e., slowly and for a long time, thus ensuring the maintenance of its physiological levels and preventing "H2S-poor" diseases. Despite the development of numerous synthetically derived molecules, the observation that plants containing sulfur compounds share the same pharmacological properties as H2S led to the characterization of naturally derived compounds as H2S donors. In this regard, polysulfuric compounds occurring in plants belonging to the Alliaceae family were the first characterized as H2S donors, followed by isothiocyanates derived from vegetables belonging to the Brassicaceae family, and this led us to consider these plants as nutraceutical tools and their daily consumption has been demonstrated to prevent the onset of several diseases. Interestingly, sulfur compounds are also contained in many fungi. In this review, we speculate about the possibility that they may be novel sources of H2S-donors, furnishing new data on the release of H2S from several selected extracts from fungi.

Hydrogen sulfide and epigenetics: Novel insights into the cardiovascular effects of this gasotransmitter

Epigenetics studies the heritable modifications of genome expression that do not affect the nucleotide sequence. Epigenetic modifications can be divided into: DNA methylation, histone modifications, and modulation of genome expression by non-coding RNAs. Alteration of these mechanisms can alter the phenotype, and can lead to disease onset. The endogenous gasotransmitter hydrogen sulfide (H2 S) plays pleiotropic roles in many systems, including the cardiovascular (CV) system, and its mechanism of action mainly includes S-persulfidation of cysteine residues. Recent evidence suggests that many H2 S-mediated biological activities are based on the epigenetic regulation of cellular function, with effects ranging from DNA methylation to modification of histones and regulation of non-coding RNAs. This review describes the role of H2 S-regulating epigenetic mechanisms, providing a panorama of the current literature, and offers a novel scenario for the development of H2 S-releasing 'epidrugs' with a potential clinical use in the prevention and treatment of many CV and non-CV disorders.

Inflammatory Mediators of Endothelial Dysfunction

Endothelial dysfunction (ED) is characterized by imbalanced vasodilation and vasoconstriction, elevated reactive oxygen species (ROS), and inflammatory factors, as well as deficiency of nitric oxide (NO) bioavailability. It has been reported that the maintenance of endothelial cell integrity serves a significant role in human health and disease due to the involvement of the endothelium in several processes, such as regulation of vascular tone, regulation of hemostasis and thrombosis, cell adhesion, smooth muscle cell proliferation, and vascular inflammation. Inflammatory modulators/biomarkers, such as IL-1α, IL-1β, IL-6, IL-12, IL-15, IL-18, and tumor necrosis factor α, or alternative anti-inflammatory cytokine IL-10, and adhesion molecules (ICAM-1, VCAM-1), involved in atherosclerosis progression have been shown to predict cardiovascular diseases. Furthermore, several signaling pathways, such as NLRP3 inflammasome, that are associated with the inflammatory response and the disrupted H2S bioavailability are postulated to be new indicators for endothelial cell inflammation and its associated endothelial dysfunction. In this review, we summarize the knowledge of a plethora of reviews, research articles, and clinical trials concerning the key inflammatory modulators and signaling pathways in atherosclerosis due to endothelial dysfunction.

Hydrogen Sulfide and Oxygen Homeostasis in Atherosclerosis: A Systematic Review from Molecular Biology to Therapeutic Perspectives

Atherosclerosis is a complex pathological condition marked by the accumulation of lipids in the arterial wall, leading to the development of plaques that can eventually rupture and cause thrombotic events. In recent years, hydrogen sulfide (H₂S) has emerged as a key mediator of cardiovascular homeostasis, with potential therapeutic applications in atherosclerosis. This systematic review highlights the importance of understanding the complex interplay between H₂S, oxygen homeostasis, and atherosclerosis and suggests that targeting H₂S signaling pathways may offer new avenues for treating and preventing this condition. Oxygen homeostasis is a critical aspect of cardiovascular health, and disruption of this balance can contribute to the development and progression of atherosclerosis. Recent studies have demonstrated that H₂S plays an important role in maintaining oxygen homeostasis by regulating the function of oxygen-sensing enzymes and transcription factors in vascular cells. H₂S has been shown to modulate endothelial nitric oxide synthase (eNOS) activity, which plays a key role in regulating vascular tone and oxygen delivery to tissues. The comprehensive analysis of the current understanding of H₂S in atherosclerosis can pave the way for future research and the development of new therapeutic strategies for this debilitating condition. PROSPERO ID: 417150.

Antioxidant-rich Terminalia catappa fruit exerts antihypertensive effect via modulation of angiotensin-1-converting enzyme activity and H2S/NO/cGMP signaling pathway in Wistar rats

INTRODUCTION

The present study aimed at investigating the effect of Terminalia catappa fruits on blood pressure, NO/cGMP signalling pathway, angiotensin-1-converting enzyme and arginase activity, and oxidative stress biomarkers in L-NAME-induced hypertensive rats.

MATERIALS AND METHODS

Forty-two Wistar rats were divided into seven groups. Hypertension was induced via oral administration of 40 mg/kg of L-NAME for 21 days. Thereafter, the hypertensive rats were treated with Terminalia catappa fruit-supplemented diet and sildenafil citrate for 21 days. The blood pressure was measured and cardiac homogenate was prepared for biochemical analyses.

RESULTS

The results showed that L-NAME caused a significant (p < 0.05) increase in systolic and diastolic blood pressure, and heart rate as well as ACE, arginase and PDE-5 activity, with a simultaneous decrease in NO and H₂S levels as well as increased oxidative stress biomarkers. However, treatment with Terminalia catappa fruits-supplemented diets and sildenafil citrate lowered blood pressure and modulated ACE, arginase, and PDE-5 activity, improved NO and H₂S levels, as well as antioxidant status.

CONCLUSION

Findings presented in this study provide useful information on the antihypertensive property of Terminalia catappa fruits, alongside some possible mechanisms. Hence, Terminalia catappa fruits could be considered a dietary regimen and functional food in alleviating hypertension.

A Pharmacological Review of Tanshinones, Naturally Occurring Monomers from Salvia miltiorrhiza for the Treatment of Cardiovascular Diseases

Cardiovascular diseases (CVDs) are a set of heart and blood vessel disorders that include coronary heart disease (CHD), rheumatic heart disease, and other conditions. Traditional Chinese Medicine (TCM) has definite effects on CVDs due to its multitarget and multicomponent properties, which are gradually gaining national attention. Tanshinones, the major active chemical compounds extracted from Salvia miltiorrhiza, exhibit beneficial improvement on multiple diseases, especially CVDs. At the level of biological activities, they play significant roles, including anti-inflammation, anti-oxidation, anti-apoptosis and anti-necroptosis, anti-hypertrophy, vasodilation, angiogenesis, combat against proliferation and migration of smooth muscle cells (SMCs), as well as anti-myocardial fibrosis and ventricular remodeling, which are all effective strategies in preventing and treating CVDs. Additionally, at the cellular level, Tanshinones produce marked effects on cardiomyocytes, macrophages, endothelia, SMCs, and fibroblasts in myocardia. In this review, we have summarized a brief overview of the chemical structures and pharmacological effects of Tanshinones as a CVD treatment to expound on different pharmacological properties in various cell types in myocardia.

Sulfide regulation of cardiovascular function in health and disease

Hydrogen sulfide (H2S) has emerged as a gaseous signalling molecule with crucial implications for cardiovascular health. H2S is involved in many biological functions, including interactions with nitric oxide, activation of molecular signalling cascades, post-translational modifications and redox regulation. Various preclinical and clinical studies have shown that H2S and its synthesizing enzymes - cystathionine γ-lyase, cystathionine β-synthase and 3-mercaptosulfotransferase - can protect against cardiovascular pathologies, including arrhythmias, atherosclerosis, heart failure, myocardial infarction and ischaemia-reperfusion injury. The bioavailability of H2S and its metabolites, such as hydropersulfides and polysulfides, is substantially reduced in cardiovascular disease and has been associated with single-nucleotide polymorphisms in H2S synthesis enzymes. In this Review, we highlight the role of H2S, its synthesizing enzymes and metabolites, their roles in the cardiovascular system, and their involvement in cardiovascular disease and associated pathologies. We also discuss the latest clinical findings from the field and outline areas for future study.

Mechanism of homocysteine-mediated endothelial injury and its consequences for atherosclerosis

Homocysteine (Hcy) is an intermediate amino acid formed during the conversion from methionine to cysteine. When the fasting plasma Hcy level is higher than 15 μmol/L, it is considered as hyperhomocysteinemia (HHcy). The vascular endothelium is an important barrier to vascular homeostasis, and its impairment is the initiation of atherosclerosis (AS). HHcy is an important risk factor for AS, which can promote the development of AS and the occurrence of cardiovascular events, and Hcy damage to the endothelium is considered to play a very important role. However, the mechanism by which Hcy damages the endothelium is still not fully understood. This review summarizes the mechanism of Hcy-induced endothelial injury and the treatment methods to alleviate the Hcy induced endothelial dysfunction, in order to provide new thoughts for the diagnosis and treatment of Hcy-induced endothelial injury and subsequent AS-related diseases.

Hydrogen Sulfide in Diabetic Complications Revisited: The State of the Art, Challenges, and Future Directions

Significance: Diabetes and its related complications are becoming an increasing public health problem that affects hundreds of millions of people globally. Increased disability and mortality rate of diabetic individuals are closely associated with various life-threatening complications, such as atherosclerosis, nephropathy, retinopathy, and cardiomyopathy. Recent Advances: Conventional treatments for diabetes are still limited because of undesirable side effects, including obesity, hypoglycemia, and hepatic and renal toxicity. Studies have shown that hydrogen sulfide (H₂S) plays a critical role in the modulation of glycolipid metabolism, pancreatic β cell functions, and diabetic complications. Critical Issues: Preservation of endogenous H₂S systems and supplementation of H₂S donors are effective in attenuating diabetes-induced complications, thus representing a new avenue to treat diabetes and its associated complications. Future Directions: This review systematically recapitulates and discusses the most recent updates regarding the therapeutic effects of H₂S on diabetes and its various complications, with an emphasis on the molecular mechanisms that underlie H₂S-mediated protection against diabetic complications. Furthermore, current clinical trials of H₂S in diabetic populations are highlighted, and the challenges and solutions to the clinical transformation of H₂S-derived therapies in diabetes are proposed. Finally, future research directions of the pharmacological actions of H₂S in diabetes and its related complications are summarized. Antioxid. Redox Signal. 38, 18-44.

Lipid Nanoparticles for Nucleic Acid Delivery to Endothelial Cells

Endothelial cells play critical roles in circulatory homeostasis and are also the gateway to the major organs of the body. Dysfunction, injury, and gene expression profiles of these cells can cause, or are caused by, prevalent chronic diseases such as diabetes, cardiovascular disease, and cancer. Modulation of gene expression within endothelial cells could therefore be therapeutically strategic in treating longstanding disease challenges. Lipid nanoparticles (LNP) have emerged as potent, scalable, and tunable carrier systems for delivering nucleic acids, making them attractive vehicles for gene delivery to endothelial cells. Here, we discuss the functions of endothelial cells and highlight some receptors that are upregulated during health and disease. Examples and applications of DNA, mRNA, circRNA, saRNA, siRNA, shRNA, miRNA, and ASO delivery to endothelial cells and their targets are reviewed, as well as LNP composition and morphology, formulation strategies, target proteins, and biomechanical factors that modulate endothelial cell targeting. Finally, we discuss FDA-approved LNPs as well as LNPs that have been tested in clinical trials and their challenges, and provide some perspectives as to how to surmount those challenges.

Anti-Inflammatory Effect of the Natural H2S-Donor Erucin in Vascular Endothelium

Vascular inflammation (VI) represents a pathological condition that progressively affects the integrity and functionality of the vascular wall, thus leading to endothelial dysfunction and the onset of several cardiovascular diseases. Therefore, the research of novel compounds able to prevent VI represents a compelling need. In this study, we tested erucin, the natural isothiocyanate H₂S-donor derived from Eruca sativa Mill. (Brassicaceae), in an in vivo mouse model of lipopolysaccharide (LPS)-induced peritonitis, where it significantly reduced the amount of emigrated CD11b positive neutrophils. We then evaluated the anti-inflammatory effects of erucin in LPS-challenged human umbilical vein endothelial cells (HUVECs). The pre-incubation of erucin, before LPS treatment (1, 6, 24 h), significantly preserved cell viability and prevented the increase of reactive oxygen species (ROS) and tumor necrosis factor alpha (TNF-α) levels. Moreover, erucin downregulated endothelial hyperpermeability and reduced the loss of vascular endothelial (VE)-Cadherin levels. In addition, erucin decreased vascular cell adhesion molecule 1 (VCAM-1), cyclooxygenase-2 (COX-2) and microsomal prostaglandin E-synthase 1 (mPGES-1) expression. Of note, erucin induced eNOS phosphorylation and counteracted LPS-mediated NF-κB nuclear translocation, an effect that was partially abolished in the presence of the eNOS inhibitor L-NAME. Therefore, erucin can control endothelial function through biochemical and genomic positive effects against VI.

Regulation of blood pressure by natural sulfur compounds: Focus on their mechanisms of action

Natural sulfur compounds are emerging as therapeutic options for the management of hypertension and prehypertension. They are mainly represented by polysulfides from Alliaceae (i.e., garlic) and isothiocyanates from Brassicaceae (or crucifers). The beneficial cardiovascular effects of these compounds, especially garlic polysulfides, are well known and widely reported both in preclinical and clinical studies. However, only a few authors have linked the ability of natural sulfur compounds to induce vasorelaxation and subsequent antihypertensive effects with their ability to release hydrogen sulfide (H₂S) in biological tissue. H₂S is an endogenous gasotransmitter involved in vascular tone regulation. Some cardiovascular diseases, such as hypertension, are associated with lower plasma H₂S levels. Consequently, exogenous sources of H₂S (H₂S donors) have been designed and synthesized or identified among secondary plant metabolites as potential therapeutic options. In addition to antioxidant effects due to its chemical properties as a reducing agent, H₂S induces vasorelaxation by interacting with a range of molecular targets. The mechanisms of action accounting for H₂S-induced vasodilation include opening of vascular potassium channels (such as ATP-sensitive (K_ATP) and voltage-operated (Kv7) channels), inhibition of 5-phosphodiesterase (5-PDE), and activation of vascular endothelial growth factor receptor-2 (VEGFR-2). These effects may be attributed to H₂S-induced S-persulfidation (or S-sulfhydration), which is a posttranslational modification of cysteine residues of many types of proteins resulting in structural and functional alterations (activation/inhibition). Thus, H₂S donors, such as natural sulfur compounds, are promising antihypertensive agents with novel mechanisms of action.

Epigenetic Regulation by microRNAs in Hyperhomocysteinemia-Accelerated Atherosclerosis

Increased serum levels of homocysteine (Hcy) is a risk factor for cardiovascular disease and is specifically linked to various diseases of the vasculature such as atherosclerosis. However, the precise mechanisms by which Hcy contributes to this condition remain elusive. During the development of atherosclerosis, epigenetic modifications influence gene expression. As such, epigenetic modifications are an adaptive response to endogenous and exogenous factors that lead to altered gene expression by methylation and acetylation reactions of different substrates and the action of noncoding RNA including microRNAs (miRNAs). Epigenetic remodeling modulates cell biology in both physiological and physiopathological conditions. DNA and histone modification have been identified to have a crucial role in the progression of atherosclerosis. However, the potential role of miRNAs in hyperHcy (HHcy)-related atherosclerosis disease remains poorly explored and might be essential as well. There is no review available yet summarizing the contribution of miRNAs to hyperhomocystein-mediated atherogenicity or their potential as therapeutic targets even though their important role has been described in numerous studies. Specifically, downregulation of miR-143 or miR-125b has been shown to regulate VSCMs proliferation in vitro. In preclinical studies, downregulation of miR-92 or miR195-3p has been shown to increase the accumulation of cholesterol in foam cells and increase macrophage inflammation and atherosclerotic plaque formation, respectively. Another preclinical study found that there is a reciprocal regulation between miR-148a/152 and DNMT1 in Hcy-accelerated atherosclerosis. Interestingly, a couple of studies have shown that miR-143 or miR-217 may be used as potential biomarkers in patients with HHcy that may develop atherosclerosis. Moreover, the current review will also update current knowledge on miRNA-based therapies, their challenges, and approaches to deal with Hcy-induced atherosclerosis.

Recent advances in molecular biology of metabolic syndrome pathophysiology: endothelial dysfunction as a potential therapeutic target

Current advances in molecular pathobiology of endotheliocytes dysfunctions are promising in finding the pathogenetic links to the emergence of insulin resistance syndrome. Physiologically, human organism homeostasis is strictly controlled to maintain metabolic processes at the acquainted level. Many factors are involved in maintaining these physiological processes in the organism and any deviation is undoubtedly accompanied by specific pathologies related to the affected process. Fortunately, the body’s defense system can solve and compensate for the impaired function through its multi-level defense mechanisms. The endothelium is essential in maintaining this homeostasis through its ability to modulate the metabolic processes of the organism. Pathological activity or impairment of physiological endothelium function seems directly correlated to the emergence of metabolic syndrome. The most accepted hypothesis is that endothelium distribution is due to endoplasmic reticulum stress and unfolded protein response development, which includes inhibition of long non-coding RNAs expression, cytokines disbalance, Apelin dysregulation, glycocalyx degradation, and specific microparticles. Clinically, the enhancement or restoration of normal endothelial cells can be a target for novel therapeutic strategies since the distribution of its physiological activity impairs homeostasis and results in the progression of metabolic syndrome, and induction of its physiological activity can ameliorate insulin resistance syndrome. Novel insights on the molecular mechanisms of endothelial cell dysfunction are concisely represented in this paper to enhance the present therapeutic tactics and advance the research forward to find new therapeutic targets.

Topical Reappraisal of Molecular Pharmacological Approaches to Endothelial Dysfunction in Diabetes Mellitus Angiopathy

Diabetes mellitus (DM) is a frequent medical problem, affecting more than 4% of the population in most countries. In the context of diabetes, the vascular endothelium can play a crucial pathophysiological role. If a healthy endothelium—which is a dynamic endocrine organ with autocrine and paracrine activity—regulates vascular tone and permeability and assures a proper balance between coagulation and fibrinolysis, and vasodilation and vasoconstriction, then, in contrast, a dysfunctional endothelium has received increasing attention as a potential contributor to the pathogenesis of vascular disease in diabetes. Hyperglycemia is indicated to be the major causative factor in the development of endothelial dysfunction. Furthermore, many shreds of evidence suggest that the progression of insulin resistance in type 2 diabetes is parallel to the advancement of endothelial dysfunction in atherosclerosis. To present the state-of-the-art data regarding endothelial dysfunction in diabetic micro- and macroangiopathy, we constructed this literature review based on the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA). We interrogated five medical databases: Elsevier, PubMed, PMC, PEDro, and ISI Web of Science.

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.

Aphrodisiac Performance of Bioactive Compounds from Mimosa pudica Linn.: In Silico Molecular Docking and Dynamics Simulation Approach

Plants and their derived molecules have been traditionally used to manage numerous pathological complications, including male erectile dysfunction (ED). Mimosa pudica Linn. commonly referred to as the touch-me-not plant, and its extract are important sources of new lead molecules in drug discovery research. The main goal of this study was to predict highly effective molecules from M. pudica Linn. for reaching and maintaining penile erection before and during sexual intercourse through in silico molecular docking and dynamics simulation tools. A total of 28 bioactive molecules were identified from this target plant through public repositories, and their chemical structures were drawn using Chemsketch software. Graph theoretical network principles were applied to identify the ideal target (phosphodiesterase type 5) and rebuild the network to visualize the responsible signaling genes, proteins, and enzymes. The 28 identified bioactive molecules were docked against the phosphodiesterase type 5 (PDE5) enzyme and compared with the standard PDE5 inhibitor (sildenafil). Pharmacokinetics (ADME), toxicity, and several physicochemical properties of bioactive molecules were assessed to confirm their drug-likeness property. Molecular dynamics (MD) simulation modeling was performed to investigate the stability of PDE5–ligand complexes. Four bioactive molecules (Bufadienolide (−12.30 kcal mol⁻¹), Stigmasterol (−11.40 kcal mol⁻¹), Isovitexin (−11.20 kcal mol⁻¹), and Apigetrin (−11.20 kcal mol⁻¹)) showed the top binding affinities with the PDE5 enzyme, much more powerful than the standard PDE5 inhibitor (−9.80 kcal mol⁻¹). The four top binding bioactive molecules were further validated for a stable binding affinity with the PDE5 enzyme and conformation during the MD simulation period as compared to the apoprotein and standard PDE5 inhibitor complexes. Further, the four top binding bioactive molecules demonstrated significant drug-likeness characteristics with lower toxicity profiles. According to the findings, the four top binding molecules may be used as potent and safe PDE5 inhibitors and could potentially be used in the treatment of ED.

Progress and perspective on hydrogen sulfide donors and their biomedical applications

Following the discovery of nitric oxide (NO) and carbon monoxide (CO), hydrogen sulfide (H₂ S) has been identified as the third gasotransmitter in humans. Increasing evidence have shown that H₂ S is of preventive or therapeutic effects on diverse pathological complications. As a consequence, it is of great significance to develop suitable approaches of H₂ S-based therapeutics for biomedical applications. H₂ S-releasing agents (H₂ S donors) play important roles in exploring and understanding the physiological functions of H₂ S. More importantly, accumulating studies have validated the theranostic potential of H₂ S donors in extensive repertoires of in vitro and in vivo disease models. Thus, it is imperative to summarize and update the literatures in this field. In this review, first, the background of H₂ S on its chemical and biological aspects is concisely introduced. Second, the studies regarding the H₂ S-releasing compounds are categorized and described, and accordingly, their H₂ S-donating mechanisms, biological applications, and therapeutic values are also comprehensively delineated and discussed. Necessary comparisons between related H₂ S donors are presented, and the drawbacks of many typical H₂ S donors are analyzed and revealed. Finally, several critical challenges encountered in the development of multifunctional H₂ S donors are discussed, and the direction of their future development as well as their biomedical applications is proposed. We expect that this review will reach extensive audiences across multiple disciplines and promote the innovation of H₂ S biomedicine.

Potential Effects of Natural H2S-Donors in Hypertension Management

After the discovery of hydrogen sulfide (H₂S) in the central nervous system by Abe and Kimura in 1996, the physiopathological role of H₂S has been widely investigated in several systems such as the cardiovascular. In particular, H₂S plays a pivotal role in the control of vascular tone, exhibiting mechanisms of action able to induce vasodilation: for instance, activation of potassium channels (KATP and Kv7) and inhibition of 5-phosphodiesterase (5-PDE). These findings paved the way for the research of natural and synthetic exogenous H₂S-donors (i.e., molecules able to release H₂S) in order to have new tools for the management of hypertension. In this scenario, some natural molecules derived from Alliaceae (i.e., garlic) and Brassicaceae (i.e., rocket or broccoli) botanical families show the profile of slow H₂S-donors able to mimic the endogenous production of this gasotransmitter and therefore can be viewed as interesting potential tools for management of hypertension or pre-hypertension. In this article, the preclinical and clinical impacts of these natural H₂S-donors on hypertension and vascular integrity have been reviewed in order to give a complete panorama of their potential use for the management of hypertension and related vascular diseases.

Protein S-sulfhydration: Unraveling the prospective of hydrogen sulfide in the brain, vasculature and neurological manifestations

Hydrogen sulfide (H₂S) and hydrogen polysulfides (H₂S_n) are essential regulatory signaling molecules generated by the entire body, including the central nervous system. Researchers have focused on the classical H₂S signaling from the past several decades, whereas the last decade has shown the emergence of H₂S-induced protein S-sulfhydration signaling as a potential therapeutic approach. Cysteine S-persulfidation is a critical paradigm of post-translational modification in the process of H₂S signaling. Additionally, studies have shown the cross-relationship between S-sulfhydration and other cysteine-induced post-translational modifications, namely nitrosylation and carbonylation. In the central nervous system, S-sulfhydration is involved in the cytoprotection through various signaling pathways, viz. inflammatory response, oxidative stress, endoplasmic reticulum stress, atherosclerosis, thrombosis, and angiogenesis. Further, studies have demonstrated H₂S-induced S-sulfhydration in regulating different biological processes, such as mitochondrial integrity, calcium homeostasis, blood-brain permeability, cerebral blood flow, and long-term potentiation. Thus, protein S-sulfhydration becomes a crucial regulatory molecule in cerebrovascular and neurodegenerative diseases. Herein, we first described the generation of intracellular H₂S followed by the application of H₂S in the regulation of cerebral blood flow and blood-brain permeability. Further, we described the involvement of S-sulfhydration in different biological and cellular functions, such as inflammatory response, mitochondrial integrity, calcium imbalance, and oxidative stress. Moreover, we highlighted the importance of S-sulfhydration in cerebrovascular and neurodegenerative diseases.

Homocysteine, Vitamins B6 and Folic Acid in Experimental Models of Myocardial Infarction and Heart Failure—How Strong Is That Link?

Cardiovascular diseases are the leading cause of death and the main cause of disability. In the last decade, homocysteine has been found to be a risk factor or a marker for cardiovascular diseases, including myocardial infarction (MI) and heart failure (HF). There are indications that vitamin B6 plays a significant role in the process of transsulfuration in homocysteine metabolism, specifically, in a part of the reaction in which homocysteine transfers a sulfhydryl group to serine to form α-ketobutyrate and cysteine. Therefore, an elevated homocysteine concentration (hyperhomocysteinemia) could be a consequence of vitamin B6 and/or folate deficiency. Hyperhomocysteinemia in turn could damage the endothelium and the blood vessel wall and induce worsening of atherosclerotic process, having a negative impact on the mechanisms underlying MI and HF, such as oxidative stress, inflammation, and altered function of gasotransmitters. Given the importance of the vitamin B6 in homocysteine metabolism, in this paper, we review its role in reducing oxidative stress and inflammation, influencing the functions of gasotransmitters, and improving vasodilatation and coronary flow in animal models of MI and HF.

Dopamine 1 receptors inhibit apoptosis via activating CSE/H2 S pathway in high glucose-induced vascular endothelial cells

High glucose (HG) induced dysfunction of vascular endothelial cells plays a crucial role in the development of diabetic vascular complications. Inhibition of cystathionine γ-synthase/hydrogen sulfide (CSE/H₂ S) pathway is one of the causes of vascular endothelial cells injury induced by HG. Dopamine D1 receptors (DR1) are widely expressed and regulate important physiological functions in the vascular system. However, the effect of DR1 inhibition on HG-induced vascular endothelial apoptosis by regulating CSE/H₂ S pathway is unclear. Therefore, we aimed to determine if DR1 can regulate the CSE/H₂ S pathway and the effect of DR1 on HG-induced apoptosis in human umbilical vein endothelial cells (HUVECs). In this study, we found that HG treatment significantly decreased the expression of DR1 and CSE and the endogenous content of H₂ S, DR1 agonist SKF 38393 reversed these effect, while NaHS only increased CSE expression and the endogenous H₂ S production and had no effect on DR1 expression. Meanwhile, HG significantly raised intracellular calcium concentration ([Ca²⁺ ]_i ), SKF 38393 further increased HG-induced [Ca²⁺ ]_i . In addition, HG increased LDH activity, MDA and ROS contents, apoptotic rate, the expression of cleaved caspase-3, -9 and Cytochrome C and the activity of phosphorylated-IκBα (p-IκBα) and phosphorylated-NF-κB (p-NF-κB), reduced cell viability, SOD activity and Bcl-2 expressions. SKF 38393 and NaHS markedly reversed the effect of HG. The effect of SKF 38393 was similar to NAC (an inhibitor of oxidative stress) or PDTC (a NF-kB inhibitor). Taken together, DR1 up-regulate CSE/H₂ S pathway by increasing [Ca²⁺ ]_i , which inhibits HG-induced apoptosis via down-regulating NF-κB/IκBα pathway in vascular endothelial cells. This article is protected by copyright. All rights reserved.

Modulation of Human Hydrogen Sulfide Metabolism by Micronutrients, Preliminary Data

Background:

Hydrogen sulfide (H₂S) is a pivotal gasotransmitter networking with nitric oxide (NO) and carbon monoxide (CO) to regulate basic homeostatic functions. It is released by the alternative pathways of transulfuration by the enzymes Cystathionine Beta Synthase (CBS) and Cystathionine Gamma Lyase (CSE), and by Cysteine AminoTransferase (CAT)/ 3-Mercaptopyruvate Sulfur Transferase (3MPST). A non-enzymatic, intravascular release is also in place. We retrospectively investigated the possibility to modulate the endogenous H₂S release and signaling in humans by a dietary manipulation with supplemented micronutrients (L-cystine, Taurine and pyridoxal 5-phopsphate/P5P).

Methods:

Patients referring for antiaging purposes underwent a 10-day supplementation. Blood was collected at baseline and after treatment and the metabolome was investigated by mass spectrometry to monitor the changes in the metabolites reporting on H₂S metabolism and related pathways.

Results:

Data were available from 6 middle aged subjects (2 women). Micronutrients increased 3-mercaptopyruvate (P = .03), reporting on the activity of CAT that provides the substrate for H₂S release within mitochondria by 3MPST, decreased lanthionine (P = .024), reporting the release of H₂S from CBS, and had no significant effect of H₂S release from CSE. This is compatible with a homeostatic balancing. We also recorded a strong increase of reporters of H₂S-induced pathways including 5-MethylTHF (P = .001) and SAME (P = .022), reporting on methylation capacity, and of BH4 (P = .021) and BH2 (P = .028) reporting on nitric oxide metabolism. These activations may be explained by the concomitant induction of non-enzymatic release of H₂S.

Conclusions:

Although the current evidences are weak and will need to be confirmed, the effect of micronutrients was compatible with an increase of the H₂S endogenous release and signaling within the control of homeostatic mechanisms, further endorsing the role of feeding in health and disease. These effects might result in a H₂S boosting effect in case of defective activity of pathologic origin, which should be checked in duly designed clinical trials.

Renal consequences of the novel coronavirus disease 2019 (COVID-19) and hydrogen sulfide as a potential therapy

The novel coronavirus disease 2019 (COVID-19), caused by SARS-CoV-2, is a global pandemic which is primarily considered a respiratory illness. However, emerging reports show that the virus exhibits both pulmonary and extra-pulmonary manifestations in humans, with the kidney as a major extra-pulmonary target due to its abundant expression of angiotensin-converting enzyme 2 and transmembrane protease serine 2, which facilitate entry of the virus into cells. Acute kidney injury has become prevalent in COVID-19 patients without prior any history of kidney dysfunction. In addition, the virus also worsens kidney conditions and increases mortality of COVID-19 patients with pre-existing chronic kidney disease, renal cancer, diabetic nephropathy, end-stage kidney disease as well as dialysis and kidney transplant patients. In the search for antiviral agents for the treatment of COVID-19, hydrogen sulfide (H₂S), the third established member of gasotransmitter family, is emerging as a potential candidate, possessing important therapeutic properties including antiviral, anti-inflammatory, anti-thrombotic and antioxidant properties. A recent clinical study revealed higher serum H₂S levels in survivors of COVID-19 pneumonia with reduced interleukin-6 levels compared to fatal cases. In this review, we summarize the global impact of COVID-19 on kidney conditions and discuss the emerging role of H₂S as a potential COVID-19 therapy.

Effect of hydrogen sulphide containing mineral water on experimental osteoporosis in rats

Background/Aim: Sulphur mineral water is widely used in the treatment of musculoskeletal diseases. Hydrogen sulphide is an important regulator of bone metabolism and its application in the treatment of osteoporosis is intensively researched. The aim of this study was to analyse biochemical and histological effects of H2S containing mineral water of "Mlječanica" spring on ovariectomy-induced experimental osteoporosis in rats. Methods: In this experiment a 14-week-old Wistar female rats were used. The animals undergone bilateral ovariectomy (OVX groups) as an experimental model for oestrogen-deficient osteoporosis. After six weeks, animals were divided into control and the experimental group. Rats from the experimental group treated with H2S (SW group) containing mineral water ad libitum during five weeks. Biochemical parameters for monitoring sulphur water effects were concentration in serum of osteocalcin, alkaline phosphatase, calcium and phosphorus. Histological analyses of the left tibia coloured with haematoxylin-eosin were carried out. Results: Regarding the biochemical parameters, a statistically significant increase was observed in the OVX group for osteocalcin, alkaline phosphatase calcium and phosphorus compared to the sham-operated (CNT) group (p < 0.01). In SW + OVX, alkaline phosphatase was statistically significantly decreased (p < 0.01) and serum osteocalcin and phosphorus increased (p < 0.01). Calcium values were increased without significance. In the OVX + SW group, histological analyses showed numerous osteoblasts along the trabecular endosteum and the growth of young chondrocytes in the central bone zone and their migration to the peripheral parts. Conclusion: Drinking the H2S containing "Mlječanica" mineral water has led to decreased alkaline phosphatase, increased osteocalcin and phosphorus concentration in serum and stimulated the bone reparation in osteoporotic rats.

The effect of sulphate-sulphide mineral baths on blood glucose level in patients with knee osteoarthritis

Background/Aim: Type 2 diabetes is a common comorbidity in patients with knee osteoarthritis. Bearing in mind that obesity and insulin resistance are risk factors for the development of knee osteoarthritis, physical therapy and balneotherapy containing hydrogen sulphide (H2S) has a positive effect on the functional and metabolic status of these patients. This work was aimed to investigate the effect of sulphate-sulphide-rich mineral baths containing H2S on the level of serum glucose in patients with knee osteoarthritis. Methods: An open prospective randomised clinical trial included patients suffering from stage I and II of the knee osteoarthritis. Patients were divided into two groups of 40 subjects each: control group and experimental group. All subjects underwent inpatient physical treatment consisting of kinesitherapy and transcutaneous electrical nerve stimulation (TENS) 6 days a week. Patients from experimental group, in addition to all the mentioned treatments, also took sulphate-sulphide mineral water baths once a day for 30 minutes for 7 days, unlike the patients from control group who took tap water baths, according to the same schedule. The level of serum glucose was monitored in all patients on admission, after discharge and 6 months after the treatment. The Student t-test was used for statistical data processing and p < 0.05 was considered as statistically significant. Results: Study included 80 patients of both sexes, with an average age of 67.00 ± 5.75 years. All patients had elevated serum glucose values on admission. The initial levels of glycaemia in the control and experimental groups were not significantly different (6.99 ± 1.95 and 7.88 ± 1.90 mmol/L, respectively). At discharge, patients who performed balneotherapy had a statistically significant decrease in serum glucose values compared to patients from the control group (by 1.84 vs 0.26 mmol/L, p < 0.001). This effect did not persist six months after the end of the treatment (p > 0.05). Conclusion: The application of balneotherapy with sulphate-sulphide mineral baths containing H2S as a potent gas transmitter significantly reduces serum glucose levels in patients with knee osteoarthritis.

Dysfunctional Vascular Endothelium as a Driver of Atherosclerosis: Emerging Insights Into Pathogenesis and Treatment

Atherosclerosis, the chronic accumulation of cholesterol-rich plaque within arteries, is associated with a broad spectrum of cardiovascular diseases including myocardial infarction, aortic aneurysm, peripheral vascular disease, and stroke. Atherosclerotic cardiovascular disease remains a leading cause of mortality in high-income countries and recent years have witnessed a notable increase in prevalence within low- and middle-income regions of the world. Considering this prominent and evolving global burden, there is a need to identify the cellular mechanisms that underlie the pathogenesis of atherosclerosis to discover novel therapeutic targets for preventing or mitigating its clinical sequelae. Despite decades of research, we still do not fully understand the complex cell-cell interactions that drive atherosclerosis, but new investigative approaches are rapidly shedding light on these essential mechanisms. The vascular endothelium resides at the interface of systemic circulation and the underlying vessel wall and plays an essential role in governing pathophysiological processes during atherogenesis. In this review, we present emerging evidence that implicates the activated endothelium as a driver of atherosclerosis by directing site-specificity of plaque formation and by promoting plaque development through intracellular processes, which regulate endothelial cell proliferation and turnover, metabolism, permeability, and plasticity. Moreover, we highlight novel mechanisms of intercellular communication by which endothelial cells modulate the activity of key vascular cell populations involved in atherogenesis, and discuss how endothelial cells contribute to resolution biology - a process that is dysregulated in advanced plaques. Finally, we describe important future directions for preclinical atherosclerosis research, including epigenetic and targeted therapies, to limit the progression of atherosclerosis in at-risk or affected patients.

Oxidative Post-Translational Modifications: A Focus on Cysteine S-Sulfhydration and the Regulation of Endothelial Fitness

Significance: Changes in the oxidative balance can affect cellular physiology and adaptation through redox signaling. The endothelial cells that line blood vessels are particularly sensitive to reactive oxygen species, which can alter cell function by a number of mechanisms, including the oxidative post-translational modification (oxPTM) of proteins on critical cysteine thiols. Such modifications can act as redox-switches to alter the function of targeted proteins. Recent Advances: Mapping the cysteine oxPTM proteome and characterizing the effects of individual oxPTMs to gain insight into consequences for cellular responses has proven challenging. A recent addition to the list of reversible oxPTMs that contributes to cellular redox homeostasis is persulfidation or S-sulfhydration. Critical Issues: It has been estimated that up to 25% of proteins are S-sulfhydrated, making this modification almost as abundant as phosphorylation. In the endothelium, persulfides are generated by the trans-sulfuration pathway that catabolizes cysteine and cystathionine to generate hydrogen sulfide (H₂S) and H₂S-related sulfane sulfur compounds (H₂S_n). This pathway is of particular importance for the vascular system, as the enzyme cystathionine γ lyase (CSE) in endothelial cells accounts for a significant portion of total vascular H₂S/H₂S_n production. Future Directions: Impaired CSE activity in endothelial dysfunction has been linked with marked changes in the endothelial cell S-sulfhydrome and can contribute to the development of atherosclerosis and hypertension. It will be interesting to determine how changes in the S-sulfhydration of specific networks of proteins contribute to endothelial cell physiology and pathophysiology. Antioxid. Redox Signal. 35, 1494-1514.

H2S Donors and Their Use in Medicinal Chemistry

Hydrogen sulfide (H2S) is a ubiquitous gaseous signaling molecule that has an important role in many physiological and pathological processes in mammalian tissues, with the same importance as two others endogenous gasotransmitters such as NO (nitric oxide) and CO (carbon monoxide). Endogenous H2S is involved in a broad gamut of processes in mammalian tissues including inflammation, vascular tone, hypertension, gastric mucosal integrity, neuromodulation, and defense mechanisms against viral infections as well as SARS-CoV-2 infection. These results suggest that the modulation of H2S levels has a potential therapeutic value. Consequently, synthetic H2S-releasing agents represent not only important research tools, but also potent therapeutic agents. This review has been designed in order to summarize the currently available H2S donors; furthermore, herein we discuss their preparation, the H2S-releasing mechanisms, and their -biological applications.

Metformin in cardiovascular diabetology: a focused review of its impact on endothelial function

As a first-line treatment for diabetes, the insulin-sensitizing biguanide, metformin, regulates glucose levels and positively affects cardiovascular function in patients with diabetes and cardiovascular complications. Endothelial dysfunction (ED) represents the primary pathological change of multiple vascular diseases, because it causes decreased arterial plasticity, increased vascular resistance, reduced tissue perfusion and atherosclerosis. Caused by “biochemical injury”, ED is also an independent predictor of cardiovascular events. Accumulating evidence shows that metformin improves ED through liver kinase B1 (LKB1)/5'-adenosine monophosphat-activated protein kinase (AMPK) and AMPK-independent targets, including nuclear factor-kappa B (NF-κB), phosphatidylinositol 3 kinase-protein kinase B (PI3K-Akt), endothelial nitric oxide synthase (eNOS), sirtuin 1 (SIRT1), forkhead box O1 (FOXO1), krüppel-like factor 4 (KLF4) and krüppel-like factor 2 (KLF2). Evaluating the effects of metformin on endothelial cell functions would facilitate our understanding of the therapeutic potential of metformin in cardiovascular diabetology (including diabetes and its cardiovascular complications). This article reviews the physiological and pathological functions of endothelial cells and the intact endothelium, reviews the latest research of metformin in the treatment of diabetes and related cardiovascular complications, and focuses on the mechanism of action of metformin in regulating endothelial cell functions.

Role of H2S in Regulation of Vascular Tone in Metabolic Disorders

We studied the effect of the H₂S donor (NaHS, 1-500 μM) on the contractile responses of isolated aortic smooth muscle segments from rats with metabolic syndrome induced by high-fat, high-carbohydrate diet. It was found that the vasorelaxing effect of NaHS (5-100 μM) decreased in under conditions of MS. The endothelial NO synthase inhibitor L-NAME (100 μM) suppressed the effect of NaHS, while cystathionine-gamma-lyase inhibitor PAG (100 μM) decreased the vasodilating effects of acetylcholine (0.1-100 μM). Application of endogenous NO precursor L-arginine (1 mM) potentiated in the effects of H₂S donor NaHS. Thus, the contractile activity of vascular smooth muscles in metabolic syndrome is determined by not only the effect of H₂S, but also the influence of NO.

The Antiviral Roles of Hydrogen Sulfide by Blocking the Interaction between SARS-CoV-2 and Its Potential Cell Surface Receptors

The ongoing coronavirus disease 2019 (COVID-19) pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is posing a great threat to the global economy and public health security. Together with the acknowledged angiotensin-converting enzyme 2, glucose-regulated protein 78, transferrin receptor, AXL, kidney injury molecule-1, and neuropilin 1 are also identified as potential receptors to mediate SARS-CoV-2 infection. Therefore, how to inhibit or delay the binding of SARS-CoV-2 with the abovementioned receptors is a key step for the prevention and treatment of COVID-19. As the third gasotransmitter, hydrogen sulfide (H2S) plays an important role in many physiological and pathophysiological processes. Recently, survivors were reported to have significantly higher H2S levels in COVID-19 patients, and mortality was significantly greater among patients with decreased H2S levels. Considering that the beneficial role of H2S against COVID-19 and COVID-19-induced comorbidities and multiorgan damage has been well-examined and reported in some excellent reviews, this review will discuss the recent findings on the potential receptors of SARS-CoV-2 and how H2S modulates the above receptors, in turn blocking SARS-CoV-2 entry into host cells.

H2S as a Bridge Linking Inflammation, Oxidative Stress and Endothelial Biology: A Possible Defense in the Fight against SARS-CoV-2 Infection?

The endothelium controls vascular homeostasis through a delicate balance between secretion of vasodilators and vasoconstrictors. The loss of physiological homeostasis leads to endothelial dysfunction, for which inflammatory events represent critical determinants. In this context, therapeutic approaches targeting inflammation-related vascular injury may help for the treatment of cardiovascular disease and a multitude of other conditions related to endothelium dysfunction, including COVID-19. In recent years, within the complexity of the inflammatory scenario related to loss of vessel integrity, hydrogen sulfide (H₂S) has aroused great interest due to its importance in different signaling pathways at the endothelial level. In this review, we discuss the effects of H₂S, a molecule which has been reported to demonstrate anti-inflammatory activity, in addition to many other biological functions related to endothelium and sulfur-drugs as new possible therapeutic options in diseases involving vascular pathobiology, such as in SARS-CoV-2 infection.

Tanshinone IIA Stimulates Cystathionine γ-Lyase Expression and Protects Endothelial Cells from Oxidative Injury

Tanshinone IIA (Tan IIA), an active ingredient of Danshen, is a well-used drug to treat cardiovascular diseases. Currently, the mechanisms involved remain poorly understood. Given that many actions of Tan IIA could be similarly achieved by hydrogen sulfide (H2S), we speculated that Tan IIA might work through the induction of endogenous H2S. This study was to test this hypothesis. Exposure to endothelial cells to Tan IIA elevated H2S-synthesizing enzyme cystathionine γ-Lyase (CSE), associated with an increased level of endogenous H2S and free thiol activity. Further analysis revealed that this effect of Tan IIA was mediated by an estrogen receptor (ER) and cAMP signaling pathway. It stimulated VASP and CREB phosphorylation. Inhibition of ER or PKA abolished the CSE-elevating effect, whereas activation of ER or PKA mimicked the effect of Tan IIA. In an oxidative endothelial cell injury model, Tan IIA potently attenuated oxidative stress and inhibited cell death. In support of a role of endogenous H2S, inhibition of CSE aggerated oxidative cell injury. On the contrary, supplement of H2S attenuated cell injury. Collectively, our study characterized endogenous H2S as a novel mediator underlying the pharmacological actions of Tan IIA. Given the multifaceted functions of H2S, the H2S-stimulating property of Tan IIA could be exploited for treating many diseases.

Endothelial Progenitor Cells Dysfunctions and Cardiometabolic Disorders: From Mechanisms to Therapeutic Approaches

Metabolic syndrome (MetS) is a cluster of several disorders, such as hypertension, central obesity, dyslipidemia, hyperglycemia, insulin resistance and non-alcoholic fatty liver disease. Despite health policies based on the promotion of physical exercise, the reduction of calorie intake and the consumption of healthy food, there is still a global rise in the incidence and prevalence of MetS in the world. This phenomenon can partly be explained by the fact that adverse events in the perinatal period can increase the susceptibility to develop cardiometabolic diseases in adulthood. Individuals born after intrauterine growth restriction (IUGR) are particularly at risk of developing cardiovascular diseases (CVD) and metabolic disorders later in life. It has been shown that alterations in the structural and functional integrity of the endothelium can lead to the development of cardiometabolic diseases. The endothelial progenitor cells (EPCs) are circulating components of the endothelium playing a major role in vascular homeostasis. An association has been found between the maintenance of endothelial structure and function by EPCs and their ability to differentiate and repair damaged endothelial tissue. In this narrative review, we explore the alterations of EPCs observed in individuals with cardiometabolic disorders, describe some mechanisms related to such dysfunction and propose some therapeutical approaches to reverse the EPCs dysfunction.

The H2S-Donor Erucin Exhibits Protective Effects against Vascular Inflammation in Human Endothelial and Smooth Muscle Cells

Preservation of vascular wall integrity against degenerative processes associated with ageing, fat-rich diet and metabolic diseases is a timely therapeutical challenge. The loss of endothelial function and integrity leads to cardiovascular diseases and multiorgan inflammation. The protective effects of the H₂S-donor erucin, an isothiocyanate purified by Eruca sativa Mill. seeds, were evaluated on human endothelial and vascular smooth muscle cells. In particular, erucin actions were evaluated on cell viability, ROS, caspase 3/7, inflammatory markers levels and the endothelial hyperpermeability in an inflammatory model associated with high glucose concentrations (25 mM, HG). Erucin significantly prevented the HG-induced decrease in cell viability as well as the increase in ROS, caspase 3/7 activation, and TNF-α and IL-6 levels. Similarly, erucin suppressed COX-2 and NF-κB upregulation associated with HG exposure. Erucin also caused a significant inhibition of p22phox subunit expression in endothelial cells. In addition, erucin significantly prevented the HG-induced increase in endothelial permeability as also confirmed by the quantification of the specific markers VE-Cadherin and ZO-1. In conclusion, our results assess anti-inflammatory and antioxidant effects by erucin in vascular cells undergoing HG-induced inflammation and this protection parallels the preservation of endothelial barrier properties.