The crucial relationship between miRNA-27 and CSE/H2S, and the mechanism of action of GLP-1 in myocardial hypertrophy

Cardiac hypertrophy is the most prevalent compensatory heart disease that ultimately leads to spontaneous heart failure. Mounting evidence suggests that microRNAs (miRs) and endogenous hydrogen sulfide (H2S) play a crucial role in the regulation of cardiac hypertrophy. In this study, we aimed to investigate whether inhibition of miR-27a could protect against cardiac hypertrophy by modulating H2S signaling. We established a model of cardiac hypertrophy by obtaining hypertrophic tissue from mice subjected to transverse aortic constriction (TAC) and from cells treated with angiotensin-II. Molecular alterations in the myocardium were quantified using quantitative real time PCR (qRT-PCR), Western blotting, and ELISA. Morphological changes were characterized by hematoxylin and eosin (HE) staining and Masson's trichrome staining. Functional myocardial changes were assessed using echocardiography. Our results demonstrated that miR-27a levels were elevated, while H2S levels were reduced in TAC mice and myocardial hypertrophy. Further luciferase and target scan assays confirmed that cystathionine-γ-lyase (CSE) was a direct target of miR-27a and was negatively regulated by it. Notably, enhancement of H2S expression in the heart was observed in mice injected with recombinant adeno-associated virus vector 9 (rAAV9)-anti-miR-27a and in cells transfected with a miR-27a inhibitor during cardiac hypertrophy. However, this effect was abolished by co-transfection with CSE siRNA and the miR-27a inhibitor. Conversely, injecting rAAV9-miR-27a yielded opposite results. Interestingly, our findings demonstrated that glucagon-like peptide-1 (GLP-1) agonists could mitigate myocardial damage by down-regulating miR-27a and up-regulating CSE. In summary, our study suggests that inhibition of miR-27a holds therapeutic promise for the treatment of cardiac hypertrophy by increasing H2S levels. Furthermore, our findings unveil a novel mechanism of GLP-1 agonists involving the miR-27a/H2S pathway in the management of cardiac hypertrophy.

Weakening of M1 macrophage and bone resorption in periodontitis cystathionine γ-lyase-deficient mice

OBJECTIVES

Cystathionine-γ-lyase (CTH) has been proved to involve in inflammation and bone remolding, implying its potential role in the progression of periodontitis. This study was aimed to investigate the function of CTH and its relation to the macrophage polarization in periodontitis.

MATERIALS AND METHODS

Bone marrow-derived macrophages (BMDMs) from wild-type (WT) and Cth knockout (Cth-/- ) mice were stimulated with lipopolysaccharide (LPS) in vitro and pro-inflammatory cytokines were analyzed by qRT-PCR. Ligature-induced periodontitis was established on WT and Cth-/- mice. Histological analysis, tartrate-resistant acid phosphatase staining, immunostaining, and Western blot were performed to analyze the periodontium destruction and M1 macrophage polarization.

RESULTS

Cth expression in BMDMs was upregulated upon increasing LPS stimulation. Deletion of Cth suppressed BMDMs inflammatory response with decreased Il1b, Il6, and Tnf mRNA. Cth-/- mice with periodontitis showed attenuated bone loss and impaired osteoclast differentiation compared with WT. Moreover, Cth knockout hindered M1 macrophage polarization, reduced the expression of IL-1β, IL-6, and TNF-α in periodontally diseased tissue.

CONCLUSION

This study demonstrated that CTH played an important role in regulating the inflammatory responses and periodontitis tissue destruction. Importantly, Cth knockout suppressed M1 macrophages polarization in periodontitis.

Cystathionine Gamma Lyase Is Regulated by Flow and Controls Smooth Muscle Migration in Human Saphenous Vein

The saphenous vein is the conduit of choice for bypass grafting. Unfortunately, the hemodynamic stress associated with the arterial environment of the bypass vein graft leads to the development of intimal hyperplasia (IH), an excessive cellular growth and collagen deposition that results in restenosis and secondary graft occlusion. Hydrogen sulfide (H2S) is a ubiquitous redox-modifying gasotransmitter that inhibits IH. H2S is produced via the reverse trans-sulfuration pathway by three enzymes: cystathionine γ-lyase (CSE), cystathionine β-synthase (CBS) and 3-mercaptopyruvate sulfurtransferase (3-MST). However, the expression and regulation of these enzymes in the human vasculature remains unclear. Here, we investigated the expression of CSE, CBS and 3-MST in segments of native human saphenous vein and large arteries. Furthermore, we evaluated the regulation of these enzymes in vein segments cultured under static, venous (7 mmHg pressure) or arterial (100 mmHg pressure) pressure. CSE was expressed in the media, neointima and intima of the vessels and was negatively regulated by arterial shear stress. Adenoviral-mediated CSE overexpression or RNA interference-mediated CSE knock-down revealed that CSE inhibited primary human VSMC migration but not proliferation. We propose that high shear stress in arteriovenous bypass grafts inhibits CSE expression in both the media and endothelium, which may contribute to increased VSMC migration in the context of IH.

Beneficial Effect of H2S-Releasing Molecules in an In Vitro Model of Sarcopenia: Relevance of Glucoraphanin

Sarcopenia is a gradual and generalized skeletal muscle (SKM) syndrome, characterized by the impairment of muscle components and functionality. Hydrogen sulfide (H₂S), endogenously formed within the body from the activity of cystathionine-γ-lyase (CSE), cystathionine- β-synthase (CBS), and mercaptopyruvate sulfurtransferase, is involved in SKM function. Here, in an in vitro model of sarcopenia based on damage induced by dexamethasone (DEX, 1 μM, 48 h treatment) in C2C12-derived myotubes, we investigated the protective potential of exogenous and endogenous sources of H₂S, i.e., glucoraphanin (30 μM), L-cysteine (150 μM), and 3-mercaptopyruvate (150 μM). DEX impaired the H₂S signalling in terms of a reduction in CBS and CSE expression and H₂S biosynthesis. Glucoraphanin and 3-mercaptopyruvate but not L-cysteine prevented the apoptotic process induced by DEX. In parallel, the H₂S-releasing molecules reduced the oxidative unbalance evoked by DEX, reducing catalase activity, O₂⁻ levels, and protein carbonylation. Glucoraphanin, 3-mercaptopyruvate, and L-cysteine avoided the changes in myotubes morphology and morphometrics after DEX treatment. In conclusion, in an in vitro model of sarcopenia, an impairment in CBS/CSE/H₂S signalling occurs, whereas glucoraphanin, a natural H₂S-releasing molecule, appears more effective for preventing the SKM damage. Therefore, glucoraphanin supplementation could be an innovative therapeutic approach in the management of sarcopenia.

Methods for Suppressing Hydrogen Sulfide in Biological Systems

Significance: Hydrogen sulfide (H₂S) plays critical roles in redox biology, and its regulatory effects are tightly controlled by its cellular location and concentration. The imbalance of H₂S is believed to contribute to some pathological processes. Recent Advances: Downregulation of H₂S requires chemical tools such as inhibitors of H₂S-producing enzymes and H₂S scavengers. Recent efforts have discovered some promising inhibitors and scavengers. These advances pave the road toward better understanding of the functions of H₂S. Critical Issues: Precise H₂S downregulation is challenging. The potency and specificity of current inhibitors are still far from ideal. H₂S-producing enzymes are involved in complex sulfur metabolic pathways and ubiquitously present in biological matrices. The inhibition of these enzymes can cause unwanted side effects. H₂S scavengers allow targeted H₂S clearance, but their options are still limited. In addition, the scavenging process often results in biologically active by-products. Future Directions: Further development of potent and specific inhibitors for H₂S-producing enzymes is needed. Scavengers that can rapidly and selectively remove H₂S while generating biocompatible by-products are needed. Potential therapeutic applications of scavengers and inhibitors are worth exploring. Antioxid. Redox Signal. 36, 294-308.

Localization of the hydrogen sulfide and oxytocin systems at the depth of the sulci in a porcine model of acute subdural hematoma

In the porcine model discussed in this review, the acute subdural hematoma was induced by subdural injection of autologous blood over the left parietal cortex, which led to a transient elevation of the intracerebral pressure, measured by bilateral neuromonitoring. The hematoma-induced brain injury was associated with albumin extravasation, oxidative stress, reactive astrogliosis and microglial activation in the ipsilateral hemisphere. Further proteins and injury markers were validated to be used for immunohistochemistry of porcine brain tissue. The cerebral expression patterns of oxytocin, oxytocin receptor, cystathionine-γ-lyase and cystathionine-β-synthase were particularly interesting: these four proteins all co-localized at the base of the sulci, where pressure-induced brain injury elicits maximum stress. In this context, the pig is a very relevant translational model in contrast to the rodent brain. The structure of the porcine brain is very similar to the human: the presence of gyri and sulci (gyrencephalic brain), white matter to grey matter proportion and tentorium cerebelli. Thus, pressure-induced injury in the porcine brain, unlike in the rodent brain, is reflective of the human pathophysiology.

Lenthionine, a Key Flavor Substance in Lentinula edodes, Is Regulated by Cysteine under Drought Stress

Due to its unique flavor profile, Lentinula edodes has become one of the most popular edible mushrooms in the world, but the regulatory mechanism of its flavor substances has not been revealed. To study the mechanism that regulates the anabolic metabolism of the important flavor substance lenthionine (LT), the effect of cysteine (Cys) synthesized by the cystathionine-γ-lyase (CSE-1) gene participating in the regulation of LT metabolism under drought stress was analyzed. Our results showed that drought stress promoted the accumulation of LT, and the key genes GTT and LECSL were activated. Furthermore, drought stress promoted the accumulation of intracellular Cys and activated the key gene for Cys synthesis, CSE-1. Both inhibition of the CSE enzyme activity by inhibitors and silencing of the CSE-1 gene under drought stress significantly reduced the intracellular contents of Cys and LT, but the inhibition of LT synthesis disappeared after the exogenous addition of Cys. These results indicate that LT synthesis in L. edodes under drought stress is dependent on Cys. In summary, the mechanism of the regulation of flavor substances in edible mushrooms by the environment was revealed for the first time.

Corrigendum: Mechanism of Growth Regulation of Yeast Involving Hydrogen Sulfide From S-Propargyl-Cysteine Catalyzed by Cystathionine-γ-Lyase

[This corrects the article DOI: 10.3389/fmicb.2021.679563.].

Biological Connection of Psychological Stress and Polytrauma under Intensive Care: The Role of Oxytocin and Hydrogen Sulfide

This paper explored the potential mediating role of hydrogen sulfide (H2S) and the oxytocin (OT) systems in hemorrhagic shock (HS) and/or traumatic brain injury (TBI). Morbidity and mortality after trauma mainly depend on the presence of HS and/or TBI. Rapid "repayment of the O2 debt" and prevention of brain tissue hypoxia are cornerstones of the management of both HS and TBI. Restoring tissue perfusion, however, generates an ischemia/reperfusion (I/R) injury due to the formation of reactive oxygen (ROS) and nitrogen (RNS) species. Moreover, pre-existing-medical-conditions (PEMC's) can aggravate the occurrence and severity of complications after trauma. In addition to the "classic" chronic diseases (of cardiovascular or metabolic origin), there is growing awareness of psychological PEMC's, e.g., early life stress (ELS) increases the predisposition to develop post-traumatic-stress-disorder (PTSD) and trauma patients with TBI show a significantly higher incidence of PTSD than patients without TBI. In fact, ELS is known to contribute to the developmental origins of cardiovascular disease. The neurotransmitter H2S is not only essential for the neuroendocrine stress response, but is also a promising therapeutic target in the prevention of chronic diseases induced by ELS. The neuroendocrine hormone OT has fundamental importance for brain development and social behavior, and, thus, is implicated in resilience or vulnerability to traumatic events. OT and H2S have been shown to interact in physical and psychological trauma and could, thus, be therapeutic targets to mitigate the acute post-traumatic effects of chronic PEMC's. OT and H2S both share anti-inflammatory, anti-oxidant, and vasoactive properties; through the reperfusion injury salvage kinase (RISK) pathway, where their signaling mechanisms converge, they act via the regulation of nitric oxide (NO).

H2S and Oxytocin Systems in Early Life Stress and Cardiovascular Disease

Today it is well established that early life stress leads to cardiovascular programming that manifests in cardiovascular disease, but the mechanisms by which this occurs, are not fully understood. This perspective review examines the relevant literature that implicates the dysregulation of the gasomediator hydrogen sulfide and the neuroendocrine oxytocin systems in heart disease and their putative mechanistic role in the early life stress developmental origins of cardiovascular disease. Furthermore, interesting hints towards the mutual interaction of the hydrogen sulfide and OT systems are identified, especially with regards to the connection between the central nervous and the cardiovascular system, which support the role of the vagus nerve as a communication link between the brain and the heart in stress-mediated cardiovascular disease.

Mechanism of Growth Regulation of Yeast Involving Hydrogen Sulfide From S-Propargyl-Cysteine Catalyzed by Cystathionine-γ-Lyase

Pathogenic fungi are recognized as a progressive threat to humans, particularly those with the immunocompromised condition. The growth of fungi is controlled by several factors, one of which is signaling molecules, such as hydrogen sulfide (H₂S), which was traditionally regarded as a toxic gas without physiological function. However, recent studies have revealed that H₂S is produced enzymatically and endogenously in several species, where it serves as a gaseous signaling molecule performing a variety of critical biological functions. However, the influence of this endogenous H₂S on the biological activities occurring within the pathogenic fungi, such as transcriptomic and phenotypic alternations, has not been elucidated so far. Therefore, the present study was aimed to decipher this concern by utilizing S-propargyl-cysteine (SPRC) as a novel and stable donor of H₂S and Saccharomyces cerevisiae as a fungal model. The results revealed that the yeast could produce H₂S by catabolizing SPRC, which facilitated the growth of the yeast cells. This implies that the additional intracellularly generated H₂S is generated primarily from the enhanced sulfur-amino-acid-biosynthesis pathways and serves to increase the growth rate of the yeast, and presumably the growth of the other fungi as well. In addition, by deciphering the implicated pathways and analyzing the in vitro enzymatic activities, cystathionine-γ-lyase (CYS3) was identified as the enzyme responsible for catabolizing SPRC into H₂S in the yeast, which suggested that cystathionine-γ-lyase might play a significant role in the regulation of H₂S-related transcriptomic and phenotypic alterations occurring in yeast. These findings provide important information regarding the mechanism underlying the influence of the gaseous signaling molecules such as H₂S on fungal growth. In addition, the findings provide a better insight to the in vivo metabolism of H₂S-related drugs, which would be useful for the future development of anti-fungal drugs.

Synergisms, Discrepancies and Interactions between Hydrogen Sulfide and Carbon Monoxide in the Gastrointestinal and Digestive System Physiology, Pathophysiology and Pharmacology

Endogenous gas transmitters, hydrogen sulfide (H₂S), carbon monoxide (CO) and nitric oxide (NO) are important signaling molecules known to exert multiple biological functions. In recent years, the role of H₂S, CO and NO in regulation of cardiovascular, neuronal and digestive systems physiology and pathophysiology has been emphasized. Possible link between these gaseous mediators and multiple diseases as well as potential therapeutic applications has attracted great attention from biomedical scientists working in many fields of biomedicine. Thus, various pharmacological tools with ability to release CO or H₂S were developed and implemented in experimental animal in vivo and in vitro models of many disorders and preliminary human studies. This review was designed to review signaling functions, similarities, dissimilarities and a possible cross-talk between H₂S and CO produced endogenously or released from chemical donors, with special emphasis on gastrointestinal digestive system pathologies prevention and treatment.

The Role of Glucocorticoid Receptor and Oxytocin Receptor in the Septic Heart in a Clinically Relevant, Resuscitated Porcine Model With Underlying Atherosclerosis

The pathophysiology of sepsis-induced myocardial dysfunction is not resolved to date and comprises inflammation, barrier dysfunction and oxidative stress. Disease-associated reduction of tissue cystathionine-γ-lyase (CSE) expression, an endogenous H₂S-producing enzyme, is associated with oxidative stress, barrier dysfunction and organ injury. CSE-mediated cardio-protection has been suggested to be related the upregulation of oxytocin receptor (OTR). CSE can also mediate glucocorticoid receptor (GR) signaling, which is important for normal heart function. A sepsis-related loss of cardiac CSE expression associated with impaired organ function has been reported previously. The aim of this current post hoc study was to investigate the role of cardiac GR and OTR after polymicrobial sepsis in a clinically relevant, resuscitated, atherosclerotic porcine model. Anesthetized and instrumented FBM (Familial Hypercholesterolemia Bretoncelles Meishan) pigs with high fat diet-induced atherosclerosis underwent poly-microbial septic shock (n = 8) or sham procedure (n = 5), and subsequently received intensive care therapy with fluid and noradrenaline administration for 24 h. Cardiac protein expression and mRNA levels were analyzed. Systemic troponin, a marker of cardiac injury, was significantly increased in septic animals in contrast to sham, whereas OTR and GR expression in septic hearts were reduced, along with a down-regulation of anti-inflammatory GR target genes and the antioxidant transcription factor NRF2. These results suggest a potential interplay between GR, CSE, and OTR in sepsis-mediated oxidative stress, inflammation and cardiac dysfunction.

Increased susceptibility of mice obtained from in vitro fertilization to global cerebral ischemia-reperfusion injury: possible role of hydrogen sulphide and its biosynthetic enzymes

Aim of the Study: This study was designed to explore the relative susceptibility of in vitro fertilization (IVF)-conceived mice to global cerebral ischemic injury with the possible role of hydrogen sulphide and enzymes responsible for its production.Materials and Methods: IVF was carried to obtain pups, which were allowed to grow to the age of eight weeks. Thereafter, male mice were subjected to 20 min of global ischemia and 24 h of reperfusion. The mice obtained from other groups including normal mating, superovulation but normal mating and normal mating but embryo implantation were also subjected to global ischemia-reperfusion (I/R) injury.Results: IVF-derived mice exhibited significant more injury in response to I/R injury in comparison to other groups assessed in terms of impairment in locomotor activity, development of motor in coordination, neurological severity score, cerebral infarction and apoptosis markers (caspase-3 activity and Bcl-2 expression). Moreover, there was a relative decrease in the brain levels of hydrogen sulphide (H₂S) and its biosynthetic enzymes viz. cystathionine-β-synthase and cystathionine-γ-lyase. Interestingly, the levels of H₂S and cystathionine-γ-lyase were significantly low in IVF-derived mice in basal conditions also, i.e. before subjecting to I/R injury and these biochemical alterations were associated with the behavioural deficits in mice, even before subjecting to I/R injury.Conclusion: It is concluded that in vitro fertilization-derived mice are more susceptible to global cerebral I/R injury, which may be possibly due to decreased levels of hydrogen sulphide and its biosynthetic enzymes viz., cystathionine-β-synthase and cystathionine-γ-lyase.

Altered gene expression of hydrogen sulfide-producing enzymes in the liver and muscles tissues of hyperthyroid rats

Thyroid hormones have a role in the regulation of hydrogen sulfide (H₂ S) biosynthesis. In this study, we determined the effects of hyperthyroidism on H₂ S levels in various tissues and messenger RNA (mRNA) expression of cystathionine-β-synthase (CBS), cystathionine-γ-lyase (CSE), and 3-mercaptopyruvate sulfurtransferase (3-MST) in the liver and muscles of the rat. Sixteen male Wistar rats were divided into the hyperthyroid and the control groups. Hyperthyroidism was induced by adding l-thyroxine (12 mg/L) to drinking water for a period of 21 days. H₂ S concentrations in serum, liver, aorta, heart, and soleus muscles, as well as mRNA expressions of CBS, CSE, and 3-MST in these tissues were measured at Day 21. Hyperthyroid rats had lower H₂ S levels in the serum compared with controls (14.7 ± 1.4 vs. 25.7 ± 1.6 µmol/L, p < 0.001). Compared with controls, hyperthyroid rats had lower levels of H₂ S in the aorta (89%), heart (80%), and soleus (103%) muscles, but higher levels in the liver (35%). Hyperthyroidism decreased the ratio of CBS/CSE mRNA expression in the liver and the CSE/CBS mRNA expression in the muscles by decreasing CBS levels in liver (34% cf. controls) and CSE levels in the aorta, heart, and soleus muscles (respectively, 51%, 7%, and 52% cf.). In addition, hyperthyroidism decreased the mRNA expression of 3-MST in the liver (51%) and aorta (33%), and increased it in the heart (300%) and soleus muscle (182%). In conclusion, hyperthyroidism increased H₂ S levels in the liver and decreased it in muscles; these effects are at least in part due to increases and decreases in expression of CSE in the liver and muscles, respectively. These data indicate an association between thyroid hormone status and gene expression of the H₂ S-producing enzymes in the rat.

Cystathionine-γ-lyase ameliorates the histone demethylase JMJD3-mediated autoimmune response in rheumatoid arthritis

Cystathionine-γ-lyase (CSE), an enzyme associated with hydrogen sulfide (H₂S) production, is an important endogenous regulator of inflammation. Jumonji domain-containing protein 3 (JMJD3) is implicated in the immune response and inflammation. Here, we investigated the potential contribution of JMJD3 to endogenous CSE-mediated inflammation in rheumatoid arthritis (RA). Upregulated CSE and JMJD3 were identified in synovial fibroblasts (SFs) from RA patients as well as in the joints of arthritic mice. Knocking down CSE augmented inflammation in IL-1β-induced SFs by increasing JMJD3 expression. In addition, CSE^-/- mice with collagen-induced arthritis (CIA) developed severe joint inflammation and bone erosion. Conversely, overexpressing CSE inhibited JMJD3 expression by the transcription factor Sp-1 and was accompanied by reduced inflammation in IL-1β-treated SFs. Furthermore, JMJD3 silencing or the administration of the JMJD3 inhibitor GSK-J4 significantly decreased the inflammatory response in IL-1β-treated SFs, mainly by controlling the methylation status of H3K27me3 at the promoter of its target genes. GSK-J4 markedly attenuated the severity of arthritis in CIA mice. In conclusion, suppressing JMJD3 expression by the transcription factor Sp-1 is likely responsible for the ability of CSE to negatively modulate the inflammatory response and reduce the progression of RA.

Involvement of NF-κB in the upregulation of cystathionine-γ-lyase, a hydrogen sulfide-forming enzyme, and bladder pain accompanying cystitis in mice

Hydrogen sulfide (H₂ S) is generated from l-cysteine by multiple enzymes including cystathionine-γ-lyase (CSE), and promotes nociception by targeting multiple molecules such as Ca_v 3.2 T-type Ca²⁺ channels. Bladder pain accompanying cyclophosphamide (CPA)-induced cystitis in mice has been shown to involve the functional upregulation of the CSE/H₂ S/Ca_v 3.2 pathway. Therefore, we investigated whether NF-κB, as an upstream signal of the CSE/H₂ S system, contributes to bladder pain in mice with CPA-induced cystitis. Bladder pain-like nociceptive behaviour was observed in CPA-treated mice, and referred hyperalgesia was evaluated by the von Frey test. Isolated bladder weights were assessed to estimate bladder swelling, and protein levels were measured by Western blotting. CPA, administered intraperitoneally, induced nociceptive behaviour, referred hyperalgesia and increased bladder weights in mice. β-Cyano-l-alanine, a reversible selective CSE inhibitor, prevented CPA-induced nociceptive behaviour, referred hyperalgesia, and, in part, increases in bladder weight. CPA markedly increased phosphorylated NF-κB p65 levels in the bladder, an effect that was prevented by pyrrolidine dithiocarbamate (PDTC), an NF-κB inhibitor. PDTC and curcumin, which inhibits NF-κB signals, abolished CPA-induced nociceptive behaviour, referred hyperalgesia and, in part, increases in bladder weight. CPA caused the overexpression of CSE in the bladder, and this was prevented by PDTC or curcumin. The CPA-induced activation of NF-κB signals appeared to cause CSE overexpression in the bladder, contributing to bladder pain and in part swelling, possibly through H₂ S/Ca_v 3.2 signaling. Therefore, NF-κB-inhibiting compounds including curcumin may be useful for the treatment of cystitis-related bladder pain.

Cystathionine- γ-lyase promotes process of breast cancer in association with STAT3 signaling pathway

Here we provide evidences to link cystathionine-γ-lyase (CSE) to the development of breast cancer. CSE expression is up-regulated in both breast cancers and breast cancer cell lines and results in proliferation and migration of breast cancer cells. CSE Function in breast cancer depends on the STAT3 signaling pathway, a regulator of critical cell functions including cell growth in a wide variety of human cancer cells via activating the expression of relative genes. STAT3 positively relates to CSE expression. It activates the CSE promoter via a direct binding to the promoter. Moreover, CSE could reversely regulate STAT3 expression and consequently enhance the effect of STAT3 on CSE. Taken together, these data demonstrate for the first time the roles of CSE in breast cancer leading to breast cancer development in association with STAT3 signaling pathway.

Hydrogen sulfide synthesis enzymes reduced in lower esophageal sphincter of patients with achalasia

The etiology of achalasia remains largely unknown. Considerable evidence reveals that the lower esophageal sphincter dysfunction is due to the lack of inhibitory neurotransmitter, secondary to esophageal neuronal inflammation or loss. Recent studies suggest hydrogen sulfide may act as an inhibitory transmitter in gastrointestinal tract, but study about hydrogen sulfide in human esophagus still lack. The aim of the study was to investigate if hydrogen sulfide synthesis enzymes could be detected in human esophagus and if the synthesis of the endogenous hydrogen sulfide could be affected in achalasia patients. Tissue samples in cardia, lower esophageal sphincter, 2 cm and 4 cm above lower esophageal sphincter were obtained from achalasia patients undergoing peroral endoscopic myotomy. Control tissues in lower esophageal sphincter were obtained from esophageal carcinoma patients. Expression of cystathionine-β-synthase and cystathionine-γ-lyase in lower esophageal sphincter of achalasia patients and control were detected by immunohistochemical staining. In addition, expression of cystathionine-β-synthase and cystathionine-γ-lyase were compared among different parts of esophagus in achalasia patients. Compared with control, the expression of cystathionine-β-synthase and cystathionine-γ-lyase in lower esophageal sphincter of achalasia patients was significantly reduced (χ² = 11.429, P = 0.010). The expression of cystathionine-β-synthase and cystathionine-γ-lyase were lower in lower esophageal sphincter than that in 2 cm and 4 cm above lower esophageal sphincter, respectively (all P < 0.05). In conclusion, the expression of hydrogen sulfide synthesis enzymes, cystathionine-β-synthase and cystathionine-γ-lyase, can be detected in human esophagus and is reduced in patients with achalasia, which implicates the involvement of the two hydrogen sulfide synthesis enzymes in the pathophysiology of achalasia.

The CBS/CSE system: a potential therapeutic target in NAFLD?

Non-alcoholic fatty liver disease (NAFLD) is a broad spectrum liver disorder diagnosed in patients without a history of alcohol abuse. NAFLD is growing at alarming rates worldwide. Its pathogenesis is complex and incompletely understood. The cystathionine-β-synthase (CBS) and cystathionine-γ-lyase (CSE) system regulates homocysteine and cysteine metabolism and contributes to endogenous hydrogen sulfide (H2S) biosynthesis. This review summarizes our current understanding of the hepatic CBS/CSE system, and for the first time, positions this system as a potential therapeutic target in NAFLD. As will be discussed, the CBS/CSE system is highly expressed and active in the liver. Its dysregulation, presenting as alterations in circulating homocysteine and (or) H2S levels, has been reported in NAFLD patients and in NAFLD-associated co-morbidities such as obesity and type 2 diabetes. Intricate links between the CBS/CSE system and a number of metabolic and stress related molecular mediators have also emerged. Various dysfunctions in the hepatic CBS/CSE system have been reported in animal models representative of each NAFLD spectrum. It is anticipated that a newfound appreciation for the hepatic CBS/CSE system will emerge that will improve our understanding of NAFLD pathogenesis, and give rise to new prospective targets for management of this disorder.

MPST but not CSE is the primary regulator of hydrogen sulfide production and function in the coronary artery

Hydrogen sulfide (H2S) has emerged as an important gasotransmitter in the vasculature. In this study, we tested the hypothesis that H2S contributes to coronary vasoregulation and evaluated the physiological relevance of two sources of H2S, namely, cystathionine-γ-lyase (CSE) and 3-mercaptypyruvate sulfertransferase (MPST). MPST was detected in human coronary artery endothelial cells as well as rat and mouse coronary artery; CSE was not detected in the coronary vasculature. Rat coronary artery homogenates produced H2S through the MPST pathway but not the CSE pathway in vitro. In vivo coronary vasorelaxation response was similar in CSE knockout mice, wild-type mice (WT), and WT mice treated with the CSE inhibitor propargylglycine, suggesting that CSE-produced H2S does not have a significant role in coronary vasoregulation in vivo. Ex vivo, the MPST substrate 3-mercaptopyruvate (3-MP) and H2S donor sodium hydrosulfide (NaHS) elicited similar coronary vasoreactivity responses. Pyruvate did not have any effects on vasoreactivity. The vasoactive effect of H2S appeared to be nitric oxide (NO) dependent: H2S induced coronary vasoconstriction in the presence of NO and vasorelaxation in its absence. Maximal endothelial-dependent relaxation was intact after 3-MP and NaHS induced an increase in preconstriction tone, suggesting that endothelial NO synthase activity was not significantly inhibited. In vitro, H2S reacted with NO, which may, in part explain the vasoconstrictive effects of 3-MP and NaHS. Taken together, these data show that MPST rather than CSE generates H2S in coronary artery, mediating its effects through direct modulation of NO. This has important implications for H2S-based therapy in healthy and diseased coronary arteries.

Endogenous carbon monoxide downregulates hepatic cystathionine-γ-lyase in rats with liver cirrhosis

The aim of the present study was to investigate the effect of endogenous carbon monoxide (CO) on the hydrogen sulfide/cystathionine-γ-lyase (H₂S/CSE) pathway in cirrhotic rat livers. The rats were allocated at random into four groups: Sham, cirrhosis, cobalt protoporphyrin (CoPP) and zinc protoporphyrin IX (ZnPP). The expression of hepatic CSE mRNA was evaluated using a quantitative polymerase chain reaction, while CSE protein expression was determined using immunohistochemical analysis. Hematoxylin and eosin staining was performed for the histological evaluation of liver fibrosis. The levels of H₂S, alanine aminotransferase (ALT), aspartate aminotransferase (AST), total bilirubin (TBIL) and carboxyhemoglobin (COHb) in the arterial blood were determined, in addition to the portal vein pressure. The mRNA and protein expression levels of hepatic CSE and the serum levels of H₂S were significantly decreased in the cirrhosis group compared with those in the sham group (P<0.05). Compared with the cirrhosis group, rats in the ZnPP group had significantly lower levels of serum ALT, AST and TBIL, arterial COHb and hepatic fibrosis, while hepatic CSE expression and the production of H₂S were significantly increased (P<0.05). The CoPP group exhibited decreased hepatic CSE expression and H₂S production, but aggravated hepatic function and fibrosis (P<0.05). In conclusion, the H₂S/CSE pathway is involved in the formation of liver cirrhosis and serves a crucial function in protecting liver cells against the progression of liver fibrosis. Endogenous CO downregulates hepatic CSE mRNA and protein expression and the production of H₂S in rats with liver cirrhosis.

Reduction of hydrogen sulfide synthesis enzymes in the esophagus of patients with achalasia: effect of hydrogen sulfide in achalasia

BACKGROUND

The aim of the present study was to investigate whether the synthesis of endogenous hydrogen sulfide (H2 S) was altered in achalasia patients and to determine the effects of H2 S on esophageal motility.

METHODS

(1) Tissue samples in lower esophageal sphincter (LES) were obtained from 22 achalasia patients during peroral endoscopic myotomy. LES muscle from eight esophageal carcinoma patients was obtained as control. The expression of cystathionine-β-synthase (CBS) and cystathionine-γ-lyase (CSE) was detected by immunohistochemical staining. (2) Rabbit esophageal smooth muscle strips were used to measure isometric contractions. The effects of sodium hydrosulfide (NaHS) and L-cysteine on contractile activity and bethanechol-stimulated contractile activity were evaluated. The contraction of esophageal muscle strips was also measured after the inhibition of CBS and CSE by aminooxyacetic acid (AOA) and propargylglycine (PAG).

KEY RESULTS

Both CBS and CSE could be detected in biopsies from achalasia patients and controls. Compared with controls, the expression of CBS and CSE in the LES of achalasia patients was significantly reduced (p < 0.001). Both NaHS and L-cysteine concentration-dependently inhibited esophageal contractile activity (both p < 0.05). After inhibition of CBS and CSE by PAG and AOA, esophageal contractile activity increased significantly, and this effect could be restored by NaHS but not L-cysteine (p < 0.05).

CONCLUSIONS & INFERENCES

H2 S synthesis enzymes are significantly reduced in patients with achalasia compared with the controls. H2 S inhibits esophageal contractile activity concentration-dependently, and the inhibition of H2 S synthesis enzymes increases esophageal contractile activity. H2 S might be involved in the development of achalasia.

Release of GLP-1 and PYY in response to the activation of G protein-coupled bile acid receptor TGR5 is mediated by Epac/PLC-ε pathway and modulated by endogenous H2S

Activation of plasma membrane TGR5 receptors in enteroendocrine cells by bile acids is known to regulate gastrointestinal secretion and motility and glucose homeostasis. The endocrine functions of the gut are modulated by microenvironment of the distal gut predominantly by sulfur-reducing bacteria of the microbiota that produce H₂S. However, the mechanisms involved in the release of peptide hormones, GLP-1 and PYY in response to TGR5 activation by bile acids and the effect of H₂S on bile acid-induced release of GLP-1 and PYY are unclear. In the present study, we have identified the signaling pathways activated by the bile acid receptor TGR5 to mediate GLP-1 and PYY release and the mechanism of inhibition of their release by H₂S in enteroendocrine cells. The TGR5 ligand oleanolic acid (OA) stimulated Gα_s and cAMP formation, and caused GLP-1 and PYY release. OA-induced cAMP formation and peptide release were blocked by TGR5 siRNA. OA also caused an increase in PI hydrolysis and intracellular Ca²⁺. Increase in PI hydrolysis was abolished in cells transfected with PLC-ε siRNA. 8-pCPT-2′-O-Me-cAMP, a selective activator of Epac, stimulated PI hydrolysis, and GLP-1 and PYY release. L-Cysteine, which activates endogenous H₂S producing enzymes cystathionine-γ-lyase and cystathionine-β-synthase, and NaHS and GYY4137, which generate H₂S, inhibited PI hydrolysis and GLP-1 and PYY release in response to OA or 8-pCPT-2′-O-Me-cAMP. Propargylglycine, an inhibitor of CSE, reversed the effect of L-cysteine on PI hydrolysis and GLP-1 and PYY release. We conclude: (i) activation of Gα_s-coupled TGR5 receptors causes stimulation of PI hydrolysis, and release of GLP-1 and PYY via a PKA-independent, cAMP-dependent mechanism involving Epac/PLC-ε/Ca²⁺ pathway, and (ii) H₂S has potent inhibitory effects on GLP-1 and PYY release in response to TGR5 activation, and the mechanism involves inhibition of PLC-ε/Ca²⁺ pathway.

Inherent variations in CO-H2S-mediated carotid body O2 sensing mediate hypertension and pulmonary edema

Oxygen (O2) sensing by the carotid body and its chemosensory reflex is critical for homeostatic regulation of breathing and blood pressure. Humans and animals exhibit substantial interindividual variation in this chemosensory reflex response, with profound effects on cardiorespiratory functions. However, the underlying mechanisms are not known. Here, we report that inherent variations in carotid body O2 sensing by carbon monoxide (CO)-sensitive hydrogen sulfide (H2S) signaling contribute to reflex variation in three genetically distinct rat strains. Compared with Sprague-Dawley (SD) rats, Brown-Norway (BN) rats exhibit impaired carotid body O2 sensing and develop pulmonary edema as a consequence of poor ventilatory adaptation to hypobaric hypoxia. Spontaneous Hypertensive (SH) rat carotid bodies display inherent hypersensitivity to hypoxia and develop hypertension. BN rat carotid bodies have naturally higher CO and lower H2S levels than SD rat, whereas SH carotid bodies have reduced CO and greater H2S generation. Higher CO levels in BN rats were associated with higher substrate affinity of the enzyme heme oxygenase 2, whereas SH rats present lower substrate affinity and, thus, reduced CO generation. Reducing CO levels in BN rat carotid bodies increased H2S generation, restoring O2 sensing and preventing hypoxia-induced pulmonary edema. Increasing CO levels in SH carotid bodies reduced H2S generation, preventing hypersensitivity to hypoxia and controlling hypertension in SH rats.

The effect of CSE gene deletion in caerulein-induced acute pancreatitis in the mouse

Hydrogen sulfide (H2S) has been reported to be involved in the signaling of the inflammatory response; however, there are differing views as to whether it is pro- or anti-inflammatory. In this study, we sought to determine whether endogenously synthesized H2S via cystathionine-γ-lyase (CSE) plays a pro- or anti-inflammatory role in caerulein-induced pancreatitis. To investigate this, we used mice genetically deficient in CSE to elucidate the function of CSE in caerulein-induced acute pancreatitis. We compared the inflammatory response and tissue damage of wild-type (WT) and CSE knockout (KO) mice following 10 hourly administrations of 50 μg/kg caerulein or saline control. From this, we found that the CSE KO mice showed significantly less local pancreatic damage as well as acute pancreatitis-associated lung injury compared with the WT mice. There were also lower levels of pancreatic eicosanoid and cytokines, as well as reduced acinar cell NF-κB activation in the CSE KO mice compared with WT mice. Additionally, in WT mice, there was a greater level of pancreatic CSE expression and sulfide-synthesizing activity in caerulein-induced pancreatitis compared with the saline control. When comparing the two saline-treated control groups, we noted that the CSE KO mice showed significantly less pancreatic H2S-synthesizing activity relative to the WT mice. These results indicate that endogenous H2S generated by CSE plays a key proinflammatory role via NF-κB activation in caerulein-induced pancreatitis, and its genetic deletion affords significant protection against acute pancreatitis and associated lung injury.

The anti-thrombotic effect of hydrogen sulfide is partly mediated by an upregulation of nitric oxide synthases

INTRODUCTION

Hydrogen sulfide (H2S) known as a gasotransmitter is increasingly recognized for its anti-adhesive, anti-inflammatory and vasoactive properties. Due to these properties, we analysed anti-thrombotic effects of H2S and the participation of the nitric oxide synthase (NOS)-pathway.

MATERIALS AND METHODS

In individual venules of the ear of hairless SKH1-hr mice, thrombus formation was induced using a phototoxic light/dye-injury model and intravital fluorescence microscopy. Animals were treated intravenously with the H2S donor Na2S or NaCl as control. In a second setting, the NOS inhibitor L-NAME was applied intraperitoneally as a bolus 12h prior to Na2S treatment and thrombus induction. Blood and ear tissue were sampled after microscopy for assessment of plasma concentrations of soluble (s)P-selectin, sE-selectin, sVCAM-1 and sICAM-1 and expression of endothelial (e)NOS and inducible (i)NOS, respectively.

RESULTS

When mice were treated with Na2S, venular thrombus formation was significantly delayed versus that in animals of the NaCl-treated control group. While plasma levels of pro-thrombotic adhesion molecules were not affected by Na2S, immunohistochemistry of the vessel walls showed a significant up-regulation of eNOS and iNOS expression within the Na2S-treated group. The delay of thrombus formation in the Na2S-group was partly but significantly reverted by application of L-NAME.

CONCLUSIONS

The anti-thrombotic efficacy of H2S involves the NOS-pathway and may be of preventive and therapeutic value for clinical disorders with increased risk of thrombotic events.

H(2)S inhibits oscillatory shear stress-induced monocyte binding to endothelial cells via nitric oxide production

H(2)S is a signaling molecule associated with protection against vascular diseases, including atherosclerosis. This protection involves the stimulation of vasorelaxation, but other possible contributing mechanisms have not been extensively explored. In this study, we found that the vascular H(2)S-producing enzyme, cystathionine-γ-lyase (CSE), was down-regulated by oscillatory shear stress (OSS) among various vaso-regulators. Consistently, NaHS, an H(2)S donor, appeared to inhibit OSS-induced THP-1 cell adhesion. We also found that NaHS activated the nitric oxide (NO)-producing Akt/endothelial nitric oxide synthase (eNOS) signaling pathway in response to OSS, whereas NaHS had no effect on IκB, a well-known molecule regulating pro-inflammatory signaling pathways. Moreover, NaHS increased OSS-dependent eNOS expression and decreased expression of intercellular adhesion molecule-1 (ICAM-1). NG-nitro-L-arginine methyl ester (L-NAME), an eNOS inhibitor, abrogated the inhibitory effects of NaHS on OSSinduced endothelial ICAM-1 expression and monocyte adhesion to endothelial cells. These data suggest that down-regulation of CSE resulting in decreased levels of H(2)S is a key factor for OSS-associated atherogenesis and further suggest that regulation of H(2)S production can be a potential target for preventing cardiovascular diseases.