Clinical Potential of Hydrogen Sulfide in Peripheral Arterial Disease

Signaling Paradigms of H2S-Induced Vasodilation: A Comprehensive Review

Hydrogen sulfide (H2S), a gas traditionally considered toxic, is now recognized as a vital endogenous signaling molecule with a complex physiology. This comprehensive study encompasses a systematic literature review that explores the intricate mechanisms underlying H2S-induced vasodilation. The vasodilatory effects of H2S are primarily mediated by activating ATP-sensitive potassium (K_ATP) channels, leading to membrane hyperpolarization and subsequent relaxation of vascular smooth muscle cells (VSMCs). Additionally, H2S inhibits L-type calcium channels, reducing calcium influx and diminishing VSMC contraction. Beyond ion channel modulation, H2S profoundly impacts cyclic nucleotide signaling pathways. It stimulates soluble guanylyl cyclase (sGC), increasing the production of cyclic guanosine monophosphate (cGMP). Elevated cGMP levels activate protein kinase G (PKG), which phosphorylates downstream targets like vasodilator-stimulated phosphoprotein (VASP) and promotes smooth muscle relaxation. The synergy between H2S and nitric oxide (NO) signaling further amplifies vasodilation. H2S enhances NO bioavailability by inhibiting its degradation and stimulating endothelial nitric oxide synthase (eNOS) activity, increasing cGMP levels and potent vasodilatory responses. Protein sulfhydration, a post-translational modification, plays a crucial role in cell signaling. H2S S-sulfurates oxidized cysteine residues, while polysulfides (H2Sn) are responsible for S-sulfurating reduced cysteine residues. Sulfhydration of key proteins like K_ATP channels and sGC enhances their activity, contributing to the overall vasodilatory effect. Furthermore, H2S interaction with endothelium-derived hyperpolarizing factor (EDHF) pathways adds another layer to its vasodilatory mechanism. By enhancing EDHF activity, H2S facilitates the hyperpolarization and relaxation of VSMCs through gap junctions between endothelial cells and VSMCs. Recent findings suggest that H2S can also modulate transient receptor potential (TRP) channels, particularly TRPV4 channels, in endothelial cells. Activating these channels by H2S promotes calcium entry, stimulating the production of vasodilatory agents like NO and prostacyclin, thereby regulating vascular tone. The comprehensive understanding of H2S-induced vasodilation mechanisms highlights its therapeutic potential. The multifaceted approach of H2S in modulating vascular tone presents a promising strategy for developing novel treatments for hypertension, ischemic conditions, and other vascular disorders. The interaction of H2S with ion channels, cyclic nucleotide signaling, NO pathways, ROS (Reactive Oxygen Species) scavenging, protein sulfhydration, and EDHF underscores its complexity and therapeutic relevance. In conclusion, the intricate signaling paradigms of H2S-induced vasodilation offer valuable insights into its physiological role and therapeutic potential, promising innovative approaches for managing various vascular diseases through the modulation of vascular tone.

The Influence of Balneotherapy Using Salty Sulfide-Hydrogen Sulfide Water on Selected Markers of the Cardiovascular System: A Prospective Study

Background: The sulfide-hydrogen sulfide brine balneotherapy (HSBB), including a combination of dissolved hydrogen sulfide (H2S) gas, inorganic sulfur ions (S2-), and hydrosulfide ions (HS-), is one of the most important and most effective forms of spa treatment in patients with osteoarticular disorders (OADs). Some cardiovascular diseases (CVDs) are often considered to be contraindications to HSBB since the presence of thiol groups may lead to an increased quantity of reactive oxygen species (ROS), which damage the vascular endothelium, and endothelial dysfunction is considered to be the main cause of atherosclerosis. However, there are a number of literature reports suggesting this theory to be false. H2S is a member of the endogenous gaseous transmitter family and, since it is a relatively recent addition, it has the least well-known biological properties. H2S-NO interactions play an important role in oxidative stress in CVDs. The general objective of this study was to assess the cardiovascular safety of HSBB and analyze the effect of HSBB on selected cardiovascular risk markers. Methods: A total of 100 patients at the age of 76.3 (±7.5) years from the Włókniarz Sanatorium in Busko-Zdrój were initially included in the study. The following parameters were assessed: age, sex, height, body weight, body surface area (BSA), body mass index (BMI), systolic (SBP) and diastolic blood pressure (DBP), heart rate, the diagnosis of OAD that was the indication for balneotherapy, creatinine (CREAT), glomerular filtration rate (GFR), lipid panel, C-reactive protein (CRP), uric acid (UA), and fibrinogen (FIBR) and cardiovascular markers: (cardiac troponin T (cTnT), N-terminal pro-B-type natriuretic peptide (NT-proBNP). Results: A significant decrease in DBP and a trend towards SBP reduction were observed over the course of the study. A significant decrease was observed in CRP levels decreasing from 2.7 (±3.6) mg/L to 2.06 (±1.91) mg/L, whereas FIBR rose significantly from 2.95 (±0.59) g/L to 3.23 (±1.23) g/L. LDL-C levels decreased slightly, statistically significant, from 129.36 (±40.67) mg/dL to 123.74 (±36.14) mg/dL. HSBB did not affect the levels of evaluated cardiovascular biomarkers, namely NT-proBNP (137.41 (±176.52) pg/mL vs. 142.89 (±182.82) pg/mL; p = 0.477) and cTnT (9.64 (±4.13) vs. 9.65 (±3.91) ng/L; p = 0.948). A multiple regression analysis of pre-balneotherapy and post-balneotherapy values showed cTnT levels to be independently correlated only with CREAT levels and GFR values. None of the assessed parameters independently correlated with the NT-proBNP level. Conclusions: HSBB resulted in a statistically significant improvement in a subclinical pro-inflammatory state. HSBB has a beneficial effect in modifying key cardiovascular risk factors by reducing LDL-C levels and DBP values. HSBB has a neutral effect on cardiovascular ischemia/injury. Despite slightly elevated baseline levels of the biochemical marker of HF (NT-proBNP), HSBB causes no further increase in this marker. The use of HSBB in patients with OAD has either a neutral effect or a potentially beneficial effect on the cardiovascular system, which may constitute grounds for further studies to verify the current cardiovascular contraindications for this form of therapy.

The Antioxidant Properties of Glucosinolates in Cardiac Cells Are Independent of H2S Signaling

The organic sulfur-containing compounds glucosinolates (GSLs) and the novel gasotransmitter H2S are known to have cardioprotective effects. This study investigated the antioxidant effects and H2S-releasing potential of three GSLs ((3E)-4-(methylsulfanyl)but-3-enyl GSL or glucoraphasatin, 4-hydroxybenzyl GSL or glucosinalbin, and (RS)-6-(methylsulfinyl)hexyl GSL or glucohesperin) in rat cardiac cells. It was found that all three GSLs had no effect on cardiac cell viability but were able to protect against H2O2-induced oxidative stress and cell death. NaHS, a H2S donor, also protected the cells from H2O2-stimulated oxidative stress and cell death. The GSLs alone or mixed with cysteine, N-acetylcysteine, glutathione, H2O2, iron and pyridoxal-5'-phosphate, or mouse liver lysates did not induce H2S release. The addition of GSLs also did not alter endogenous H2S levels in cardiac cells. H2O2 significantly induced cysteine oxidation in the cystathionine gamma-lyase (CSE) protein and inhibited the H2S production rate. In conclusion, this study found that the three tested GSLs protect cardiomyocytes from oxidative stress and cell death but independently of H2S signaling.

Potentially active compounds that improve PAD through angiogenesis: A review

Peripheral arterial disease (PAD) has been historically neglected, which has resulted in a lack of effective drugs in clinical practice. However, with the increasing prevalence of diseases like atherosclerosis and diabetes, the incidence of PAD is rising and cannot be ignored. Researchers are exploring the potential of promoting angiogenesis through exogenous compounds to improve PAD. This paper focuses on the therapeutic effect of natural products (Salidroside, Astragaloside IV, etc.) and synthetic compounds (Cilostazol, Dapagliflozin, etc.). Specifically, it examines how they can promote autocrine secretion of vascular endothelial cells, enhance cell paracrine interactions, and regulate endothelial progenitor cell function. The activation of these effects may be closely related to PI3K, AMPK, and other pathways. Overall, these exogenous compounds have promising therapeutic potential for PAD. This study aims to summarize the potential active compounds, provide a variety of options for the search for drugs for the treatment of PAD, and bring light to the treatment of patients.