Hydrogen sulfide suppresses angiotensin II-stimulated endothelin-1 generation and subsequent cytotoxicity-induced endoplasmic reticulum stress in endothelial cells via NF-κB

Recent progress of endoplasmic reticulum stress in the mechanism of atherosclerosis

The research progress of endoplasmic reticulum (ER) stress in atherosclerosis (AS) is of great concern. The ER, a critical cellular organelle, plays a role in important biological processes including protein synthesis, folding, and modification. Various pathological factors may cause ER stress, and sustained or excessive ER stress triggers the unfolded protein response, ultimately resulting in apoptosis and disease. Recently, researchers have discovered the importance of ER stress in the onset and advancement of AS. ER stress contributes to the occurrence of AS through different pathways such as apoptosis, inflammatory response, oxidative stress, and autophagy. Therefore, this review focuses on the mechanisms of ER stress in the development of AS and related therapeutic targets, which will contribute to a deeper understanding of the disease's pathogenesis and provide novel strategies for preventing and treating AS.

Sex Influence on Autophagy Markers and miRNAs in Basal and Angiotensin II-Treated Human Umbilical Vein Endothelial Cells

Cardiovascular diseases (CVD) display many sex and gender differences, and endothelial dysfunction, angiotensin II (Ang II), and autophagy represent key factors in the autophagic process Therefore, we studied whether Ang II modulates the mentioned processes in a sex-specific way in HUVECs obtained from healthy male and female newborns. In basal HUVECs, the Parkin gene and protein were higher in FHUVECs than in MHUVECs, while the Beclin-1 protein was more expressed in MHUVECs, and no other significant differences were detected. Ang II significantly increases LAMP-1 and p62 protein expression and decreases the expression of Parkin protein in comparison to basal in MHUVECs. In FHUVECs, Ang II significantly increases the expression of Beclin-1 gene and protein, and Parkin gene. The LC3 II/I ratio and LAMP-1 protein were significantly higher in MHUVECs than in FHUVECs, while Parkin protein was significantly more expressed in Ang II-treated FHUVECs than in male cells. Ang II affects the single miRNA levels: miR-126-3p and miR-133a-3p are downregulated and upregulated in MHUVECs and FHUVECs, respectively. MiR-223 is downregulated in MHUVEC and FHUVECs. Finally, miR-29b-3p and miR-133b are not affected by Ang II. Ang II effects and the relationship between miRNAs and organelles-specific autophagy is sex-dependent in HUVECs. This could lead to a better understanding of the mechanisms underlying sex differences in endothelial dysfunction, providing useful indications for innovative biomarkers and personalized therapeutic approaches.

Inflammatory Mediators of Endothelial Dysfunction

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

Physiological roles of hydrogen sulfide in mammalian cells, tissues and organs

H2S belongs to the class of molecules known as gasotransmitters, which also includes nitric oxide (NO) and carbon monoxide (CO). Three enzymes are recognized as endogenous sources of H2S in various cells and tissues: cystathionine g-lyase (CSE), cystathionine β-synthase (CBS) and 3-mercaptopyruvate sulfurtransferase (3-MST). The current article reviews the regulation of these enzymes as well as the pathways of their enzymatic and non-enzymatic degradation and elimination. The multiple interactions of H2S with other labile endogenous molecules (e.g. NO) and reactive oxygen species are also outlined. The various biological targets and signaling pathways are discussed, with special reference to H2S and oxidative posttranscriptional modification of proteins, the effect of H2S on channels and intracellular second messenger pathways, the regulation of gene transcription and translation and the regulation of cellular bioenergetics and metabolism. The pharmacological and molecular tools currently available to study H2S physiology are also reviewed, including their utility and limitations. In subsequent sections, the role of H2S in the regulation of various physiological and cellular functions is reviewed. The physiological role of H2S in various cell types and organ systems are overviewed. Finally, the role of H2S in the regulation of various organ functions is discussed as well as the characteristic bell-shaped biphasic effects of H2S. In addition, key pathophysiological aspects, debated areas, and future research and translational areas are identified A wide array of significant roles of H2S in the physiological regulation of all organ functions emerges from this review.

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

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

Crosstalk between the renin-angiotensin system and the endoplasmic reticulum stress in the cardiovascular system: Lessons learned so far

The renin-angiotensin (Ang) system (RAS) is a complex hormonal system present locally in several tissues such as cardiovascular organs. RAS deregulation through overactivation of the classical arm [Ang-converting enzyme (ACE)/Ang-II/Ang type 1 receptor (AT1R)] has been linked to the development of cardiovascular diseases and activation of endoplasmic reticulum (ER) stress pathways. The ER stress is a condition that, if unresolved, might lead to heart failure, atherosclerosis, hypertension, and endothelial dysfunction. Accumulated evidence has shown that the RAS modulates the UPR activation. Several studies reported increased ER stress markers in response to Ang-II treatment, in both in vivo and in vitro models. Evidence has also pointed that targeting the RAS classical arm through RAS blockers, gene silencing or genetic models leads to lower levels of ER stress markers. Few studies demonstrated protective effects of the counter-regulatory arm (ACE-2/Ang-(1-7)/Mas receptor) over ER stress. However, the crosstalk mechanisms between the arms of the RAS and ER stress remain unclear. In this review, we sought to explore the classical arm of the RAS as a key mechanism in UPR activation and to suggest a possible protective role of the counter-regulatory arm in mitigating ER stress.

TNFα regulates the expression of the CSE gene in HUVEC

The hydrogen sulfide (H₂S)/cystathionine γ-lyase (CSE) signaling pathway is involved in several inflammatory conditions, where tumor necrosis factor-α (TNFα) is one of the inflammatory cytokines activated during sepsis. Therefore, the present study investigated the role of the NF-κB transcription factor binding site in the transcriptional regulation of the CSE gene in 293T cells following treatment with TNFα using luciferase assays, as well as using western blotting and reverse transcription-quantitative PCR to examine the effect of TNFα on CSE expression in HUVECs. After transfected 293T cells were incubated with various concentrations of TNFα for 1, 3, and 6 h, the wild-type promoter of the CSE gene increased significantly at 1 h compared to 0 h. By contrast, after the transfected 293T cells were incubated with various concentrations of TNFα for 1 h, the mutant-type promoter activity of the CSE gene decreased significantly compared to the wild-type. These results revealed that the DNA sequence GGGACATTCC on the CSE gene promoter was directly associated with the transcriptional regulation of the CSE gene in Human cells (293T cells) that's were treated with TNFα. This suggests that TNFα affects CSE gene expression, such that vascular endothelial cells respond to TNFα in the blood by regulating CSE expression. The regulatory mechanisms associated with the effects of TNFα on the transcriptional regulation of the CSE gene in HUVECs and the NF-κB pathway warrant further investigation.

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

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

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

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

Knockdown of Long Noncoding RNA (lncRNA) AK094457 Relieved Angiotensin II Induced Vascular Endothelial Cell Injury

Background

Hypertension could induce many serious diseases, including damage to vascular endothelial cells. As a non-coding RNA, long noncoding RNA (lncRNA) has received much attention in scientific research and has a regulating efficacy on many critical life activities in human body. The level of lncRNA AK094457 is thought to be elevated in hypertensive rats. However, there is no research indicating the relationship between the level of lncRNA AK094457 and vascular endothelial injury.

Material/Methods

In our study, we used lentiviral to knockdown lncRNA AK094457, and the human umbilical vein endothelial cells (HUVECs) were stimulated by the Ang II to imitate the vascular endothelial cell damage caused by hypertension. The Cell Counting Kit-8 assays were used to detect the cells viability. Western blotting was performed to detect the endothelial nitric oxide synthase (eNOS), p-eNOS and endothelin-1 (ET-1). After that the production of the NO was monitored. At last, the reactive oxygen species (ROS) levels and apoptosis rates were detected in this study.

Results

According to the results, we found that knockdown lncRNA AK094457 could alleviate the decrease of vascular endothelial cell viability induced by angiotensin II (Ang II). The knockdown of lncRNA AK094457 also relieved the downregulation of eNOS and p-eNOS, and the decreasing of NO release. At the same time, the knockdown of lncRNA inhibited the levels of Ang II-induced proinflammatory cytokines (tumor necrosis factor [TNF]-α, interleukin [IL]-1, and IL-6) and cell adhesion molecules (vascular cell adhesion molecule 1 [VCAM-1], intercellular adhesion molecule 1 [ICAM-1], and monocyte chemoattractant protein-1 [MCP-1]). The levels of ROS and apoptosis rates also decreased after the knockdown of lncRNA AK094457.

Conclusions

All these results indicated that lncRNA AK094457 could promote Ang II-induced vascular endothelial cell injury. On the contrary, knockdown of lncRNA AK094457 could alleviate this damage.

Role of Endothelial Dysfunction in Cardiovascular Diseases: The Link Between Inflammation and Hydrogen Sulfide

Endothelial cells are important constituents of blood vessels that play critical roles in cardiovascular homeostasis by regulating blood fluidity and fibrinolysis, vascular tone, angiogenesis, monocyte/leukocyte adhesion, and platelet aggregation. The normal vascular endothelium is taken as a gatekeeper of cardiovascular health, whereas abnormality of vascular endothelium is a major contributor to a plethora of cardiovascular ailments, such as atherosclerosis, aging, hypertension, obesity, and diabetes. Endothelial dysfunction is characterized by imbalanced vasodilation and vasoconstriction, elevated reactive oxygen species (ROS), and proinflammatory factors, as well as deficiency of nitric oxide (NO) bioavailability. The occurrence of endothelial dysfunction disrupts the endothelial barrier permeability that is a part of inflammatory response in the development of cardiovascular diseases. As such, abrogation of endothelial cell activation/inflammation is of clinical relevance. Recently, hydrogen sulfide (H₂S), an entry as a gasotransmitter, exerts diverse biological effects through acting on various targeted signaling pathways. Within the cardiovascular system, the formation of H₂S is detected in smooth muscle cells, vascular endothelial cells, and cardiomyocytes. Disrupted H₂S bioavailability is postulated to be a new indicator for endothelial cell inflammation and its associated endothelial dysfunction. In this review, we will summarize recent advances about the roles of H₂S in endothelial cell homeostasis, especially under pathological conditions, and discuss its putative therapeutic applications in endothelial inflammation-associated cardiovascular disorders.

Hydrogen Sulfide Plays an Important Protective Role through Influencing Endoplasmic Reticulum Stress in Diseases

The endoplasmic reticulum is an important organelle responsible for protein synthesis, modification, folding, assembly and transport of new peptide chains. When the endoplasmic reticulum protein folding ability is impaired, the unfolded or misfolded proteins accumulate to lead to endoplasmic reticulum stress. Hydrogen sulfide is an important signaling molecule that regulates many physiological and pathological processes. Recent studies indicate that H₂S plays an important protective role in many diseases through influencing endoplasmic reticulum stress, but its mechanism is not fully understood. This article reviewed the progress about the effect of H₂S on endoplasmic reticulum stress and its mechanisms involved in diseases in recent years to provide theoretical basis for in-depth study.

Dihydromyricetin Attenuates TNF-α-Induced Endothelial Dysfunction through miR-21-Mediated DDAH1/ADMA/NO Signal Pathway

Accumulating studies demonstrate that dihydromyricetin (DMY), a compound extracted from Chinese traditional herb, Ampelopsis grossedentata, attenuates atherosclerotic process by improvement of endothelial dysfunction. However, the underlying mechanism remains poorly understood. Thus, the aim of this study is to investigate the potential mechanism behind the attenuating effects of DMY on tumor necrosis factor alpha- (TNF-α-) induced endothelial dysfunction. In response to TNF-α, microRNA-21 (miR-21) expression was significantly increased in human umbilical vein endothelial cells (HUVECs), in line with impaired endothelial dysfunction as evidenced by decreased tube formation and migration, endothelial nitric oxide synthase (eNOS) (ser1177) phosphorylation, dimethylarginine dimethylaminohydrolases 1 (DDAH1) expression and metabolic activity, and nitric oxide (NO) concentration as well as increased asymmetric dimethylarginine (ADMA) levels. In contrast, DMY or blockade of miR-21 expression ameliorated endothelial dysfunction in HUVECs treated with TNF-α through downregulation of miR-21 expression, whereas these effects were abolished by overexpression of miR-21. In addition, using a nonspecific NOS inhibitor, L-NAME, also abrogated the attenuating effects of DMY on endothelial dysfunction. Taken together, these data demonstrated that miR-21-mediated DDAH1/ADMA/NO signal pathway plays an important role in TNF-α-induced endothelial dysfunction, and DMY attenuated endothelial dysfunction induced by TNF-α in a miR-21-dependent manner.