Correlation of Lower Concentrations of Hydrogen Sulfide with Activation of Protein Kinase CβII in Uremic Accelerated Atherosclerosis Patients

Circulating Levels of Hydrogen Sulfide (H2S) in Patients with Age-Related Diseases: A Systematic Review and Meta-Analysis

Hydrogen sulfide (H₂S) is an endogenous gasotransmitter that promotes multiple biological effects in many organs and tissues. An imbalanced biosynthesis of H₂S has been observed in animal models of age-related pathological conditions. However, the results from human studies are inconsistent. We performed a systematic review with meta-analysis of studies searched in Medline, Embase, Scopus, and CENTRAL databases. We included observational studies on patients with age-related diseases showing levels of H₂S in blood, plasma, or serum. All the analyses were carried out with R software. 31 studies were included in the systematic review and 21 in the meta-analysis. The circulating levels of H₂S were significantly reduced in patients with progressive, chronic, and degenerative diseases compared with healthy people (standardized mean difference, SMD: -1.25; 95% confidence interval, CI: -1.98; -0.52). When we stratified results by type of disorder, we observed a significant reduction in circulating levels of H₂S in patients with vascular disease (e.g., hypertension) (SMD: -1.32; 95% CI: -2.43; -0.22) or kidney disease (SMD: -2.24; 95% CI: -4.40; -0.08) compared with the control group. These results could support the potential use of compounds targeting the "H₂S system" to slow down the progression of many diseases in the elderly.

A novel, microvascular evaluation method and device for early diagnosis of peripheral artery disease and chronic limb-threatening ischemia in individuals with diabetes

Objective

A novel transdermal arterial gasotransmitter sensor (TAGS) has been tested as a diagnostic tool for lower limb microvascular disease in individuals with and without diabetes mellitus (DM).

Methods

The TAGS system noninvasively measures hydrogen sulfide (H₂S) emitted from the skin. Measurements were made on the forearm and lower limbs of individuals from three cohorts, including subjects with DM and chronic limb-threatening ischemia, to evaluate skin microvascular integrity. These measurements were compared with diagnosis of peripheral artery disease (PAD) using the standard approach of the toe brachial index. Other measures of vascular health were made in some subjects including fasting blood glucose, hemoglobin A1c, plasma lipids, blood pressure, estimated glomerular filtration, and body mass index.

Results

The leg:arm ratio of H₂S emissions correlated with risk factors for microvascular disease (ie, high-density lipoprotein levels, estimated glomerular filtration rate, systolic blood pressure, and hemoglobin A1c). The ratios were significantly lower in symptomatic DM subjects being treated for chronic limb-threatening ischemia (n = 8, 0.48 ± 0.21) compared with healthy controls (n = 5, 1.08 ± 0.30; P = .0001) and with asymptomatic DM subjects (n = 4, 0.79 ± 0.08; P = .0086). The asymptomatic DM group ratios were also significantly lower than the healthy controls (P = .0194). Using ratios of leg:arm transdermal H₂S measurement (17 subjects, 34 ratios), the overall accuracy to identify limbs with severe PAD had an area under the curve of the receiver operating curve of 0.93.

Conclusions

Ratios of transdermal H₂S measurements are lower in legs with impaired microvascular function, and the decrease in ratio precedes clinically apparent severe microvascular disease and diabetic ulcers. The TAGS instrument is a novel, sensitive tool that may aid in the early detection and monitoring of PAD complications and efforts for limb salvage.

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

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

Molecular mechanisms of hydrogen sulfide against uremic accelerated atherosclerosis through cPKCβII/Akt signal pathway

Background

Cardiovascular disease is the most common complication and leading cause of death in maintenance hemodialysis patients. The protection mechanism of hydrogen sulfide (H₂S) and the specific role of conventional protein kinase C βII (cPKCβII)/Akt signaling pathway in the formation of atherosclerosis is still controversial.

Methods

8-week-old male ApoE^−/− mice were treated with 5/6 nephrectomy and high-fat diet to make uremia accelerated atherosclerosis (UAAS) model. Mice were divided into normal control group (control group), sham operation group (sham group), UAAS group, L-cysteine group (UAAS+L-cys group), sodium hydrosulfide group (UAAS+NaHS group), and propargylglycine group (UAAS+PPG group). Western blot was used to detect cPKCβII activation, Akt phosphorylation and endothelial nitric oxide synthase (eNOS) expression in mice aorta.

Results

The membrane translocation of cPKCβII in UAAS group was higher than sham group, and L-cys or NaHS injection could suppress the membrane translocation, but PPG treatment resulted in more membrane translocation of cPKCβII (P < 0.05, n = 6 per group). Akt phosphorylation and the eNOS expression in UAAS group was lower than sham group, and L-cys or NaHS injection could suppress the degradation of Akt phosphorylation and the eNOS expression, but PPG treatment resulted in more decrease in the Akt phosphorylation and the eNOS expression (P < 0.05, n = 6 per group).

Conclusion

Endogenous cystathionine-γ-lyase (CSE)/H₂S system protected against the formation of UAAS via cPKCβII/Akt signal pathway. The imbalance of CSE/H₂S system may participate in the formation of UAAS by affecting the expression of downstream molecule eNOS, which may be mediated by cPKCβII/Akt signaling pathway.

Trimethyl Lock: A Multifunctional Molecular Tool for Drug Delivery, Cellular Imaging, and Stimuli-Responsive Materials

Trimethyl lock (TML) systems are based on ortho-hydroxydihydrocinnamic acid derivatives displaying increased lactonization reactivity owing to unfavorable steric interactions of three pendant methyl groups, and this leads to the formation of hydrocoumarins. Protection of the phenolic hydroxy function or masking of the reactivity as benzoquinone derivatives prevents lactonization and provides a trigger for controlled release of molecules attached to the carboxylic acid function through amides, esters, or thioesters. Their easy synthesis and possible chemical adaption to several different triggers make TML a highly versatile module for the development of drug-delivery systems, prodrug approaches, cell-imaging tools, molecular tools for supramolecular chemistry, as well as smart stimuliresponsive materials.

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.

Vascular biology of hydrogen sulfide

Hydrogen sulfide (H₂S) is a ubiquitous signaling molecule with important functions in many mammalian organs and systems. Observations in the 1990s ascribed physiological actions to H₂S in the nervous system, proposing that this gasotransmitter acts as a neuromodulator. Soon after that, the vasodilating properties of H₂S were demonstrated. In the past decade, H₂S was shown to exert a multitude of physiological effects in the vessel wall. H₂S is produced by vascular cells and exhibits antioxidant, antiapoptotic, anti-inflammatory, and vasoactive properties. In this concise review, we have focused on the impact of H₂S on vascular structure and function with an emphasis on angiogenesis, vascular tone, vascular permeability and atherosclerosis. H₂S reduces arterial blood pressure, limits atheromatous plaque formation, and promotes vascularization of ischemic tissues. Although the beneficial properties of H₂S are well established, mechanistic insights into the molecular pathways implicated in disease prevention and treatment remain largely unexplored. Unraveling the targets and downstream effectors of H₂S in the vessel wall in the context of disease will aid in translation of preclinical observations. In addition, acute regulation of H₂S production is still poorly understood and additional work delineating the pathways regulating the enzymes that produce H₂S will allow pharmacological manipulation of this pathway. As the field continues to grow, we expect that H₂S-related compounds will find their way into clinical trials for diseases affecting the blood vessels.

H2S biosynthesis and catabolism: new insights from molecular studies

Hydrogen sulfide (H₂S) has profound biological effects within living organisms and is now increasingly being considered alongside other gaseous signalling molecules, such as nitric oxide (NO) and carbon monoxide (CO). Conventional use of pharmacological and molecular approaches has spawned a rapidly growing research field that has identified H₂S as playing a functional role in cell-signalling and post-translational modifications. Recently, a number of laboratories have reported the use of siRNA methodologies and genetic mouse models to mimic the loss of function of genes involved in the biosynthesis and degradation of H₂S within tissues. Studies utilising these systems are revealing new insights into the biology of H₂S within the cardiovascular system, inflammatory disease, and in cell signalling. In light of this work, the current review will describe recent advances in H₂S research made possible by the use of molecular approaches and genetic mouse models with perturbed capacities to generate or detoxify physiological levels of H₂S gas within tissues.