Hydrogen Sulfide Inhibits High-Salt Diet-Induced Myocardial Oxidative Stress and Myocardial Hypertrophy in Dahl Rats

Common salt aggravated pathology of testosterone-induced benign prostatic hyperplasia in adult male Wistar rat

BACKGROUND

Benign prostatic hyperplasia (BPH) is a major health concern associated with lower urinary tract symptoms and sexual dysfunction in men. Recurrent inflammation, decreased apoptotic rate and oxidative stress are some of the theories that explain the pathophysiology of BPH. Common salt, a food additive, is known to cause systemic inflammation and redox imbalance, and may serve as a potential risk factor for BPH development or progression. This study examined the effect of common salt intake on the pathology of testosterone-induced BPH.

METHODS

Forty male Wistar rats were randomly divided into four equal groups of 10: a control and three salt diet groups-low-salt diet (LSD), standard-salt diet (SSD) and high-salt diet (HSD). The rats were castrated, allowed to recuperate and placed on salt-free diet (control), 0.25% salt diet (LSD), 0.5% salt diet (SSD) and 1.25% salt diet (HSD) for 60 days ad libitum. On day 33, BPH was induced in all the rats with daily injections of testosterone propionate-Testost® (3 mg/kg body weight) for 28 days. The rats had overnight fast (12 h) on day 60 and were euthanized the following day in order to collect blood and prostate samples for biochemical, molecular and immunohistochemistry (IHC) analyses. Mean ± SD values were calculated for each group and compared for significant difference with ANOVA followed by post hoc test (Tukey HSD) at p < 0.05.

RESULTS

This study recorded a substantially higher level of IL-6, IL-8 and COX-2 in salt diet groups and moderate IHC staining of COX-2 in HSD group. The prostatic level of IL-17, IL-1β, PGE2, relative prostate weight and serum PSA levels were not statistically different. The concentrations of IGF-1, TGF-β were similar in all the groups but there were multiple fold increase in Bcl-2 expression in salt diet groups-LSD (13.2), SSD (9.5) and HSD (7.9) and multiple fold decrease in VEGF expression in LSD (-6.3), SSD (-5.1) and HSD (-14.1) compared to control. Activity of superoxide dismutase (SOD) and concentration of nitric oxide rose in LSD and SSD groups, and SSD and HSD groups respectively. Activities of glutathione peroxidase and catalase, and concentration of NADPH and hydrogen peroxide were not significantly different. IHC showed positive immunostaining for iNOS expression in all the groups while histopathology revealed moderate to severe prostatic hyperplasia in salt diet groups.

CONCLUSIONS

These findings suggest that low, standard and high salt diets aggravated the pathology of testosterone-induced BPH in Wistar rats by promoting inflammation, oxidative stress, while suppressing apoptosis and angiogenesis.

Chronic high‑salt intake induces cardiomyocyte autophagic vacuolization during left ventricular maladaptive remodeling in spontaneously hypertensive rats

The role of autophagy in high-salt (HS) intake associated hypertensive left ventricular (LV) remodeling remains unclear. The present study investigated the LV autophagic change and its association with the hypertensive LV remodeling induced by chronic HS intake in spontaneously hypertensive rats (SHR). Wistar Kyoto (WKY) rats and SHR were fed low-salt (LS; 0.5% NaCl) and HS (8.0% NaCl) diets and were subjected to invasive LV hemodynamic analysis after 8, 12 and 16 weeks of dietary intervention. Reverse transcription-quantitative PCR and western blot analysis were performed to investigate the expression of autophagy-associated key components. The LV morphologic staining was performed at the end of the study. The rat H9c2 ventricular myoblast cell-associated experiments were performed to explore the mechanism of HS induced autophagic change. A global autophagy-associated key component, as well as increased cardiomyocyte autophagic vacuolization, was observed after 12 weeks of HS intake. During this period, the heart from HS-diet-fed SHR exhibited a transition from compensated LV hypertrophy to decompensation, as shown by progressive impairment of LV function and interstitial fibrosis. Myocardial extracellular [Na⁺] and the expression of tonicity-responsive enhancer binding protein (TonEBP) was significantly increased in HS-fed rats, indicating myocardial interstitial hypertonicity by chronic HS intake. The global autophagic change and overt deterioration of LV function were not observed in LS-fed SHR and HS-fed WKY rats. The study of rat H9c2 cardiomyocytes demonstrated a cytosolic [Na⁺] elevation-mediated, reactive oxygen species-dependent the autophagic change occurred when exposed to an increased extracellular [Na⁺]. The present findings demonstrated that a myocardial autophagic change participates in the maladaptive LV remodeling induced by chronic HS intake in SHR, which provides a possible target for future intervention studies on HS-induced hypertensive LV remodeling.

Hydrogen Sulfide Regulates Macrophage Function in Cardiovascular Diseases

Significance: Hydrogen sulfide (H₂S) is an endogenous gasotransmitter that plays a vital role in immune system regulation. Recently, the regulation of macrophage function by H₂S has been extensively and actively recognized. Recent Advances: The mechanisms by which endogenous H₂S controls macrophage function have attracted increasing attention. The generation of endogenous H₂S from macrophages is mainly catalyzed by cystathionine-γ-lyase. H₂S is involved in the macrophage activation and inflammasome formation, which contributes to macrophage apoptosis, adhesion, chemotaxis, and polarization. In addition, H₂S has redox ability and interacts with reactive oxygen species to prevent oxidative stress. Moreover, H₂S epigenetically regulates gene expression. Critical Issues: In this article, the generation of endogenous H₂S in macrophages and its regulatory effect on macrophage function are reviewed. In addition, the signal transduction targeting macrophages by H₂S is also addressed. Finally, the potential therapeutic effect of H₂S on macrophages is discussed. Future Directions: Further experiments are required to explore the involvement of endogenous H₂S in the regulation of macrophage function in various physiological and pathophysiological processes and elucidate the mechanisms involved. Regarding the clinical translation of H₂S, further exploration of the application of H₂S in inflammation-related diseases is needed. Antioxid. Redox Signal. 38, 45-56.

Tissue Sodium Accumulation: Pathophysiology and Clinical Implications

Excessive sodium intake has been well established as a risk factor for the development and progression of cardiovascular and renal diseases. Its adverse effects are achieved by renal sodium retention and related volume expansion and by inducing low-grade inflammation and oxidative stress (OS) in the target tissues. This review presents the recent concept of nonosmotic sodium storage in the skin interstitium, the subsequent dissociation of sodium and volume homeostasis, and the cellular response to the increased tissue sodium concentration. Furthermore, data are shown on the sodium barrier and buffering potential of the endothelial glycocalyx that may protect the functional integrity of the endothelium when it is challenged by an increased sodium load. Finally, examples will be given of the involvement of oxygen free radicals (OFR) in sodium-induced tissue damage, and some clinical entities will be mentioned that are causally associated with sodium/volume retention and OS.

Exogenous H2S Ameliorates High Salt-Induced Hypertension by Alleviating Oxidative Stress and Inflammation in the Paraventricular Nucleus in Dahl S Rats

Hydrogen sulfide (H₂S) is an important gaseous signaling molecule that regulates cardiovascular activity in animals. The hypothalamic paraventricular nucleus (PVN) is a major integrative region involved in blood pressure (BP) regulation. We explored whether exogenous H₂S application by intraperitoneal injection of sodium hydrosulfide (NaHS) alleviates BP increase induced by a high salt diet (HSD) and the role of PVN in Dahl salt-sensitive (Dahl S) rats. Dahl S rats were divided into four groups according to diet regime (normal salt diet [NSD] and HSD) and treatment method (daily intraperitoneal NaHS or saline injection). We monitored BP, food and water intake, and body weight for 8 weeks. Plasma, kidney, and brain tissues were collected at the end of the experiment. We found that exogenous H₂S not only delayed BP elevation but also attenuated the increase in the levels of norepinephrine, cystatin C, and blood urea nitrogen in the plasma of Dahl S rats with an HSD. Furthermore, H₂S enhanced the total antioxidant capacity, superoxide dismutase, and glutathione peroxidase in the PVN. Exogenous H₂S attenuated the protein expression of the nuclear factor-κB pathway and proinflammatory cytokines, which were significantly higher in the PVN in rats with an HSD than in rats with an NSD. Additionally, exogenous H₂S relieved PVN neuronal apoptosis induced by an HSD. These findings suggest that exogenous H₂S attenuates hypertension caused by an HSD by ameliorating oxidative stress, inflammation, and apoptosis in the PVN. This study provides evidence of the benefits of peripheral H₂S therapy for hypertension.

High-Salt Diet in the Pre- and Postweaning Periods Leads to Amygdala Oxidative Stress and Changes in Locomotion and Anxiety-Like Behaviors of Male Wistar Rats

High-salt (HS) diets have recently been linked to oxidative stress in the brain, a fact that may be a precursor to behavioral changes, such as those involving anxiety-like behavior. However, to the best of our knowledge, no study has evaluated the amygdala redox status after consuming a HS diet in the pre- or postweaning periods. This study aimed to evaluate the amygdala redox status and anxiety-like behaviors in adulthood, after inclusion of HS diet in two periods: preconception, gestation, and lactation (preweaning); and only after weaning (postweaning). Initially, 18 females and 9 male Wistar rats received a standard (n = 9 females and 4 males) or a HS diet (n = 9 females and 5 males) for 120 days. After mating, females continued to receive the aforementioned diets during gestation and lactation. Weaning occurred at 21-day-old Wistar rats and the male offspring were subdivided: control-control (C-C)—offspring of standard diet fed dams who received a standard diet after weaning (n = 9–11), control-HS (C-HS)—offspring of standard diet fed dams who received a HS diet after weaning (n = 9–11), HS-C—offspring of HS diet fed dams who received a standard diet after weaning (n = 9–11), and HS-HS—offspring of HS diet fed dams who received a HS diet after weaning (n = 9–11). At adulthood, the male offspring performed the elevated plus maze and open field tests. At 152-day-old Wistar rats, the offspring were euthanized and the amygdala was removed for redox state analysis. The HS-HS group showed higher locomotion and rearing frequency in the open field test. These results indicate that this group developed hyperactivity. The C-HS group had a higher ratio of entries and time spent in the open arms of the elevated plus maze test in addition to a higher head-dipping frequency. These results suggest less anxiety-like behaviors. In the analysis of the redox state, less activity of antioxidant enzymes and higher levels of the thiobarbituric acid reactive substances (TBARS) in the amygdala were shown in the amygdala of animals that received a high-salt diet regardless of the period (pre- or postweaning). In conclusion, the high-salt diet promoted hyperactivity when administered in the pre- and postweaning periods. In animals that received only in the postweaning period, the addition of salt induced a reduction in anxiety-like behaviors. Also, regardless of the period, salt provided amygdala oxidative stress, which may be linked to the observed behaviors.

Physical exercise prevents age-related heart dysfunction induced by high-salt intake and heart salt-specific overexpression in Drosophila

A long-term high-salt intake (HSI) seems to accelerate cardiac aging and age-related diseases, but the molecular mechanism is still not entirely clear. Exercise is an effective way to delay cardiac aging. However, it remains unclear whether long-term exercise (LTE) can protect heart from aging induced by high-salt stress. In this study, heart CG2196(salt) specific overexpression (HSSO) and RNAi (HSSR) was constructed by using the UAS/hand-Gal4 system in Drosophila. Flies were given exercise and a high-salt diet intervention from 1 to 5 weeks of age. Results showed that HSSR and LTE remarkably prevented heart from accelerated age-related defects caused by HSI and HSSO, and these defects included a marked increase in heart period, arrhythmia index, malondialdehyde (MDA) level, salt expression, and dTOR expression, and a marked decrease in fractional shortening, SOD activity level, dFOXO expression, PGC-1α expression, and the number of mitochondria and myofibrils. The combination of HSSR and LTE could better protect the aging heart from the damage of HSI. Therefore, current evidences suggested that LTE resisted HSI-induced heart presenility via blocking CG2196(salt)/TOR/oxidative stress and activating dFOXO/PGC-1α. LTE also reversed heart presenility induced by cardiac-salt overexpression via activating dFOXO/PGC-1α and blocking TOR/oxidative stress.

Diet and Hydrogen Sulfide Production in Mammals

Significance: In recent times, it has emerged that some dietary sulfur compounds can act on mammalian cell signaling systems via their propensity to release hydrogen sulfide (H₂S). H₂S plays important biochemical and physiological roles in the heart, gastrointestinal tract, brain, kidney, and immune systems of mammals. Reduced levels of H₂S in cells and tissues correlate with a spectrum of pathophysiological conditions, including heart disease, diabetes, obesity, and altered immune function. Recent Advances: In the last decade, researchers have now begun to explore the mechanisms by which dietary-derived sulfur compounds, in addition to cysteine, can act as sources of H₂S. This research has led to the identified several compounds, organic sulfides, isothiocyanates, and inorganic sulfur species including sulfate that can act as potential sources of H₂S in mammalian cells and tissues. Critical Issues: We have summarised progress made in the identification of dietary factors that can impact on endogenous H₂S levels in mammals. We also describe current research focused on how some sulfur molecules present in dietary plants, and associated chemical analogues, act as sources of H₂S, and discuss the biological properties of these molecules as studied in a range of in vitro and in vivo systems. Future Directions: The identification of sulfur compounds in edible plants that can act as novel H₂S releasing molecules is intriguing. Research in this area could inform future studies exploring the impact of diet on H₂S levels in mammalian systems. Despite recent progress, additional work is needed to determine the mechanisms by which H₂S is released from these molecules following ingestions of dietary plants in humans, whether the amounts of H₂S produced is of physiological significance following the metabolism of these compounds in vivo, and if diet could be used to manipulated H₂S levels in humans. Importantly, this will lead to a better understanding of the biological significance of H₂S generated from dietary sources, and this information could be used in the development of plant breeding initiatives to increase the levels of H₂S releasing sulfur compounds in crops, or inform dietary intervention strategies that could be used to alter the levels of H₂S in humans.

Oxidative stress in cardiac hypertrophy: From molecular mechanisms to novel therapeutic targets

When faced with increased workload the heart undergoes remodelling, where it increases its muscle mass in an attempt to preserve normal function. This is referred to as cardiac hypertrophy and if sustained, can lead to impaired contractile function. Experimental evidence supports oxidative stress as a critical inducer of both genetic and acquired forms of cardiac hypertrophy, a finding which is reinforced by elevated levels of circulating oxidative stress markers in patients with cardiac hypertrophy. These observations formed the basis for using antioxidants as a therapeutic means to attenuate cardiac hypertrophy and improve clinical outcomes. However, the use of antioxidant therapies in the clinical setting has been associated with inconsistent results, despite antioxidants having been shown to exert protection in several animal models of cardiac hypertrophy. This has forced us to revaluate the mechanisms, both upstream and downstream of oxidative stress, where recent studies demonstrate that apart from conventional mediators of oxidative stress, metabolic disturbances, mitochondrial dysfunction and inflammation as well as dysregulated autophagy and protein homeostasis contribute to disease pathophysiology through mechanisms involving oxidative stress. Importantly, novel therapeutic targets have been identified to counteract oxidative stress and attenuate cardiac hypertrophy but more interestingly, the repurposing of drugs commonly used to treat metabolic disorders, hypertension, peripheral vascular disease, sleep disorders and arthritis have also been shown to improve cardiac function through suppression of oxidative stress. Here, we review the latest literature on these novel mechanisms and intervention strategies with the aim of better understanding the complexities of oxidative stress for more precise targeted therapeutic approaches to prevent cardiac hypertrophy.

Non-invasive vagus nerve stimulation attenuates proinflammatory cytokines and augments antioxidant levels in the brainstem and forebrain regions of Dahl salt sensitive rats

The anti-inflammatory effects of vagus nerve stimulation are well known. It has recently been shown that low-level, transcutaneous stimulation of vagus nerve at the tragus (LLTS) reduces cardiac inflammation in a rat model of heart failure with preserved ejection fraction (HFpEF). The mechanisms by which LLTS affect the central neural circuits within the brain regions that are important for the regulation of cardiac vagal tone are not clear. Female Dahl salt-sensitive rats were initially fed with either low salt (LS) or high salt (HS) diet for a period of 6 weeks, followed by sham or active stimulation (LLTS) for 30 min daily for 4 weeks. To study the central effects of LLTS, four brainstem (SP5, NAb, NTS, and RVLM) and two forebrain sites (PVN and SFO) were examined. HS diet significantly increased the gene expression of proinflammatory cytokines in the SP5 and SFO. LLTS reversed HS diet-induced changes at both these sites. Furthermore, LLTS augmented the levels of antioxidant Nrf2 in the SP5 and SFO. Taken together, these findings suggest that LLTS has central anti-inflammatory and antioxidant properties that could mediate the neuromodulation of cardiac vagal tone in the rat model of HFpEF.

Effects of PM2.5 exposure in utero on heart injury, histone acetylation and GATA4 expression in offspring mice

Atmospheric fine particulate matter exposure (PM_2.5) can increase the incidence and mortality of heart disease, and raise the risk of fetal congenital heart defect, which have recently drawn much attention. In this study, C57BL/6 mice were exposed to PM_2.5 (approximately equivalent to 174 μg/m³) by intratracheal instillation during the gestation. After birth, 10 weeks old offspring mice were divided into four groups: male exposed group (ME), female exposed group (FE), male control group (MC), female control group (FC). The pathological injury, pro-inflammatory cytokines, histone acetylation levels, and expressions of GATA-binding protein 4 (GATA4) and downstream genes were investigated. The results showed that exposure to PM_2.5 in utero increased pathological damage and TNF-α and IL-6 levels in hearts of offspring mice, and effects in ME were more serious than FE. Notably, GATA4 protein levels in hearts in ME were significantly lower than that of MC, accompanied by down-regulation of histone acetyltransferase (HAT)-p300 and up-regulation of histone deacetylase-SIRT3. As GATA4 downstream genes, ratios of β-MHC gene expression to α-MHC significantly raised in ME relative to the MC. Results of chromatin immunoprecipitation (ChIP)-qPCR assay found that binding levels of acetylated histone 3 lysine 9 (H3K9ac) in GATA4 promoter region in the hearts of ME or FE were markedly decreased compared with their corresponding control groups. It suggested that maternal exposure to PM_2.5 may cause cardiac injury in the offspring, heart damage of male mice was worse than female mice, in which process HAT-p300, H3K9ac, transcription factor GATA4 may play an important regulation role.

Hydrogen sulfide signaling in regulation of cell behaviors

Recent advances in the biomedical importance of H₂S have help us understand various cellular functions and pathophysiological processes from a new aspect. Specially, H₂S has been demonstrated to play multiple roles in regulating cell behaviors, including cell survival, cell differentiation, cell senescence, cell hypertrophy, cell atrophy, cell metaplasia, and cell death, etc. H₂S contributes to cell behavior changes via various mechanisms, such as histone modification, DNA methylation, non-coding RNA changes, DNA damage repair, transcription factor activity, and post-translational modification of proteins by S-sulfhydration, etc. In this review, we summarized the recent research progress on H₂S signaling in control of cell behaviors and discussed the ways of H₂S regulation of gene expressions. Given the key roles of H₂S in both health and diseases, a better understanding of the regulation of H₂S on cell behavior change and the underlying molecular mechanisms will help us to develop novel and more effective strategies for clinical therapy.

Hydrogen sulfide stabilizes atherosclerotic plaques in apolipoprotein E knockout mice

Hydrogen sulfide gas (H₂S) has protective effects in the cardiovascular system that includes preventing the development of atherosclerosis when tested in several in vivo models. Plaque instability is a major risk factor for thromboembolism, myocardial infarction, and stroke, so we examined if H₂S can promote plaque stability and the potential underlying mechanisms. Apolipoprotein E knockout mice fed an atherogenic diet were administered the exogenous H₂S donor sodium hydrosulfide (NaHS) or pravastatin as a positive control daily for 14 weeks. NaHS significantly enhanced plaque stability by increasing fibrous cap thickness and collagen content compared to vehicle-treated controls. NaHS treatment also reduced blood lipid levels and plaque formation. Preservation of plaque stability by NaHS was associated with reductions in vascular smooth muscle cells (VSMCs) apoptosis and expression of the collagen-degrading enzyme matrix metallopeptidase-9 (MMP-9) in plaque. While pravastatin also increased fibrous cap thickness and reduced VSMC apoptosis, but did not enhance plaque collagen or reduce MMP-9 significantly, suggesting distinct mechanisms of plaque stabilization. in vitro, NaHS also decreased MMP-9 expression in macrophages stimulated with tumor necrosis factor-α by inhibiting ERK/JNK phosphorylation and activator protein 1 nuclear translocation. Moreover, H₂S reduced caspase-3/9 activity, Bax/Bcl-2 ratio, and LOX-1 mRNA expression in VSMCs stimulated with oxidized low-density lipoprotein. These results suggest that H₂S enhances plaque stability and protects against atherogenesis by increasing plaque collagen content and VSMC count. In conclusion, H₂S exerts protective effects against atherogenesis at least partly by stabilizing atherosclerotic plaque.

Exogenous Hydrogen Sulfide Supplement Attenuates Isoproterenol-Induced Myocardial Hypertrophy in a Sirtuin 3-Dependent Manner

Hydrogen sulfide (H₂S) is a gasotransmitter with a variety of cardiovascular protective effects. Sirtuin 3 (SIRT3) is closely related to mitochondrial function and oxidative stress. We found that NaHS increased SIRT3 expression in the preventive effect on isoproterenol- (ISO-) induced myocardial hypertrophy. We further investigated whether exogenous H₂S supplement improved ISO-induced myocardial hypertrophy in a SIRT3-dependent manner. 10-week-old male 129S1/SvImJ (WT) mice and SIRT3 knockout (KO) mice were intraperitoneally injected with NaHS (50 μmol/kg/d) for two weeks and then intraperitoneally injected with ISO (60 mg/kg/d) for another two weeks. In WT mice, NaHS significantly reduced the cardiac index of ISO-induced mice, decreased the cross-sectional area of cardiomyocytes, and inhibited the expressions of atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP) mRNA. The activity of total antioxidant capacity (T-AOC) and superoxide dismutase (SOD) in the myocardium was increased, but the level of malondialdehyde (MDA) was decreased. The fluorescence intensity of dihydroethidium staining for superoxide anion was attenuated. Optic atrophy 1 (OPA1) expression was upregulated, while dynamin-related protein 1 (DRP1) expression was downregulated. ERK, but not P38 and JNK, phosphorylation was downregulated. However, all above protective effects were unavailable in ISO-induced SIRT3 KO mice. Our present study suggested that exogenous H₂S supplement inhibited ISO-induced cardiac hypertrophy depending on SIRT3, which might be associated with antioxidant stress.

Protective Mechanism of Hydrogen Sulfide against Chemotherapy-Induced Cardiotoxicity

Over the past few decades, the number of long term survivors of childhood cancers has been increased exponentially. However, among these survivors, treatment-related toxicity, especially cardiotoxicity, is becoming the essential cause of morbidity and mortality. Thus, preventing the treatment-related adverse effects is important to increase the event free survival during the treatment of cancer in children and adolescents. Accumulating evidence has demonstrated that hydrogen sulfide (H₂S) exerts a protective role on cardiomyocytes through a variety of mechanisms. Here, we mainly reviewed the cardioprotective role of H₂S in the chemotherapy, and emphatically discussed the possible mechanisms.

Cooperative Oxygen Sensing by the Kidney and Carotid Body in Blood Pressure Control

Oxygen sensing mechanisms are vital for homeostasis and survival. When oxygen levels are too low (hypoxia), blood flow has to be increased, metabolism reduced, or a combination of both, to counteract tissue damage. These adjustments are regulated by local, humoral, or neural reflex mechanisms. The kidney and the carotid body are both directly sensitive to falls in the partial pressure of oxygen and trigger reflex adjustments and thus act as oxygen sensors. We hypothesize a cooperative oxygen sensing function by both the kidney and carotid body to ensure maintenance of whole body blood flow and tissue oxygen homeostasis. Under pathological conditions of severe or prolonged tissue hypoxia, these sensors may become continuously excessively activated and increase perfusion pressure chronically. Consequently, persistence of their activity could become a driver for the development of hypertension and cardiovascular disease. Hypoxia-mediated renal and carotid body afferent signaling triggers unrestrained activation of the renin angiotensin-aldosterone system (RAAS). Renal and carotid body mediated responses in arterial pressure appear to be synergistic as interruption of either afferent source has a summative effect of reducing blood pressure in renovascular hypertension. We discuss that this cooperative oxygen sensing system can activate/sensitize their own afferent transduction mechanisms via interactions between the RAAS, hypoxia inducible factor and erythropoiesis pathways. This joint mechanism supports our view point that the development of cardiovascular disease involves afferent nerve activation.

The Role of Hydrogen Sulfide on Cardiovascular Homeostasis: An Overview with Update on Immunomodulation

Hydrogen sulfide (H₂S), the third endogenous gaseous signaling molecule alongside nitric oxide (NO) and carbon monoxide, is synthesized by multiple enzymes in cardiovascular system. Similar to other gaseous mediators, H₂S has demonstrated a variety of biological activities, including anti-oxidative, anti-apoptotic, pro-angiogenic, vasodilating capacities and endothelial NO synthase modulating activity, and regulates a wide range of pathophysiological processes in cardiovascular disorders. However, the underlying mechanisms by which H₂S mediates cardiovascular homeostasis are not fully understood. This review focuses on the recent progress on functional and mechanistic aspects of H₂S in the inflammatory and immunoregulatory processes of cardiovascular disorders, importantly myocardial ischemia, heart failure, and atherosclerosis. Moreover, we highlight the challenges for developing H₂S-based therapy to modulate the pathological processes in cardiovascular diseases. A better understanding of the immunomodulatory and biochemical functions of H₂S might provide new therapeutic strategies for these cardiovascular diseases.