Increase of cystathionine-γ-lyase (CSE) during late wound repair: Hydrogen sulfide triggers cytokeratin 10 expression in keratinocytes

Gas Therapy: Generating, Delivery, and Biomedical Applications

Oxygen (O2), nitric oxide (NO), carbon monoxide (CO), hydrogen sulfide (H2S), and hydrogen (H2) with direct effects, and carbon dioxide (CO2) with complementary effects on the condition of various diseases are known as therapeutic gases. The targeted delivery and in situ generation of these therapeutic gases with controllable release at the site of disease has attracted attention to avoid the risk of gas poisoning and improve their performance in treating various diseases such as cancer therapy, cardiovascular therapy, bone tissue engineering, and wound healing. Stimuli-responsive gas-generating sources and delivery systems based on biomaterials that enable on-demand and controllable release are promising approaches for precise gas therapy. This work highlights current advances in the design and development of new approaches and systems to generate and deliver therapeutic gases at the site of disease with on-demand release behavior. The performance of the delivered gases in various biomedical applications is then discussed.

Inhibition of endogenous hydrogen sulfide production reduces activation of hepatic stellate cells via the induction of cellular senescence

In chronic liver injury, quiescent hepatic stellate cells (HSCs) transdifferentiate into activated myofibroblast-like cells and produce large amounts of extracellular matrix components, e.g. collagen type 1. Cellular senescence is characterized by irreversible cell-cycle arrest, arrested cell proliferation and the acquisition of the senescence-associated secretory phenotype (SASP) and reversal of HSCs activation. Previous studies reported that H2S prevents induction of senescence via its antioxidant activity. We hypothesized that inhibition of endogenous H2S production induces cellular senescence and reduces activation of HSCs. Rat HSCs were isolated and culture-activated for 7 days. After activation, HSCs treated with H2S slow-releasing donor GYY4137 and/or DL-propargylglycine (DL-PAG), an inhibitor of the H2S-producing enzyme cystathionine γ-lyase (CTH), as well as the PI3K inhibitor LY294002. In our result, CTH expression was significantly increased in fully activated HSCs compared to quiescent HSCs and was also observed in activated stellate cells in a in vivo model of cirrhosis. Inhibition of CTH reduced proliferation and expression of fibrotic markers Col1a1 and Acta2 in HSCs. Concomitantly, DL-PAG increased the cell-cycle arrest markers Cdkn1a (p21), p53 and the SASP marker Il6. Additionally, the number of β-galactosidase positive senescent HSCs was increased. GYY4137 partially restored the proliferation of senescent HSCs and attenuated the DL-PAG-induced senescent phenotype. Inhibition of PI3K partially reversed the senescence phenotype of HSCs induced by DL-PAG. Inhibition of endogenous H2S production reduces HSCs activation via induction of cellular senescence in a PI3K-Akt dependent manner. Our results show that cell-specific inhibition of H2S could be a novel target for anti-fibrotic therapy via induced cell senescence.

Sustained delivery of rhMG53 promotes diabetic wound healing and hair follicle development

MG53 is an essential component of the cell membrane repair machinery, participating in the healing of dermal wounds. Here we develop a novel delivery system using recombinant human MG53 (rhMG53) protein and a reactive oxygen species (ROS)-scavenging gel to treat diabetic wounds. Mice with ablation of MG53 display defective hair follicle structure, and topical application of rhMG53 can promote hair growth in the mg53 ^-/- mice. Cell lineage tracing studies reveal a physiological function of MG53 in modulating the proliferation of hair follicle stem cells (HFSCs). We find that rhMG53 protects HFSCs from oxidative stress-induced apoptosis and stimulates differentiation of HSFCs into keratinocytes. The cytoprotective function of MG53 is mediated by STATs and MAPK signaling in HFSCs. The thermosensitive ROS-scavenging gel encapsulated with rhMG53 allows for sustained release of rhMG53 and promotes healing of chronic cutaneous wounds and hair follicle development in the db/db mice. These findings support the potential therapeutic value of using rhMG53 in combination with ROS-scavenging gel to treat diabetic wounds.

On-demand therapeutic delivery of hydrogen sulfide aided by biomolecules

Hydrogen sulfide (H₂S), known as the third gasotransmitter, exerts various physiological functions including cardiac protection, angiogenesis, anti-inflammatory, and anti-cancer capability. Given its promising therapeutic potential as well as severe perniciousness if improper use, the sustained and tunable H₂S delivery systems are highly required for H₂S-based gas therapy with enhanced bioactivity and reduced side effects. To this end, a series of stimuli-responsive compounds capable of releasing H₂S (termed H₂S donors) have been designed over the past two decades to mimic the endogenous generation of H₂S and elucidate the biological functions. Further to improve the stability of H₂S donors and achieve the targeted delivery, various delivery systems have been constructed. In this review, we focus on the recent advances of an emerging subset, biomolecular-based H₂S delivery systems, which combine H₂S donors with biomolecular vectors including polysaccharide, peptide, and protein. We demonstrated their basic structures, building strategies, and therapeutic applications respectively to unfold their inherent merits endued by biomolecules including biocompatibility, biodegradability as well as expansibility. The varied development potentials of biomolecular-based H₂S delivery systems based on their specific properties are also discussed. At the end, brief future outlooks and upcoming challenges are presented as well.

Walnut ointment promotes full-thickness burning wound healing: role of linoleic acid

PURPOSE

To investigate the active ingredients of walnut ointment (WO) and its mechanism in repairing wounds.

METHODS

The ingredients of WO were detected by gas chromatography-mass spectrometry. The effect of linoleic acid (LA) was tested by in vitro Alamar Blue (AB) reagent. Image J software, histological and immunohistochemical analysis were used to confirm the healing effect of LA in the porcine skin model. The animals were euthanized after the experiment by injection of pentobarbital sodium.

RESULTS

LA, 24% in WO, promotes keratinocytes and fibroblasts proliferation, which were 50.09% and 15.07% respectively higher than control (p < 0.05). The healing rate of the LA group (96.02% ± 2%, 98.58% ± 0.78%) was higher than the saline group (82.11% ± 3.37%, 88.72% ± 1.73%) at week 3 and week 4 (p < 0.05). The epidermal thickness of the LA was 0.16 ± 0.04 mm greater and the expression of the P63 and CK10 proteins was stronger in the LA group than the control (p < 0.05).

CONCLUSIONS

LA, which is the main components in WO can promote full-thickness burning wounds (FBWs) by stimulating cell proliferation and differentiation.

Signaling pathways in cutaneous wound healing

Wound healing is a very complex process, where variety of different pathways is activated, depending on the phase of healing. Improper or interrupted healing might result in development of chronic wounds. Therefore, novel approaches based on detailed knowledge of signalling pathways that are activated during acute or chronic cutaneous wound healing enables quicker and more effective healing. This review outlined new possibilities of cutaneous wound healing by modulation of some signalling molecules, e.g., gasotransmitters, or calcium. Special focus is given to gasotransmitters, since these bioactive signalling molecules that can freely diffuse into the cell and exert antioxidative effects. Calcium is an important booster of immune system and it can significantly contribute to healing process. Special interest is given to chronic wounds caused by diabetes mellitus and overcoming problems with the inflammation.

Emerging ROS-Modulating Technologies for Augmentation of the Wound Healing Process

Reactive oxygen species (ROS) is considered a double-edged sword. The slightly elevated level of ROS helps in wound healing by inhibiting microbial infection. In contrast, excessive ROS levels in the wound site show deleterious effects on wound healing by extending the inflammation phase. Understanding the ROS-mediated molecular and biomolecular mechanisms and their effect on cellular homeostasis and inflammation thus substantially improves the possibility of exogenously augmenting and manipulating wound healing with the emerging antioxidant therapeutics. This review comprehensively delves into the relationship between ROS and critical phases of wound healing and the processes underpinning antioxidant therapies. The manuscript also discusses cutting-edge antioxidant therapeutics that act via ROS scavenging to enhance chronic wound healing.

Mitochondria-Targeted Hydrogen Sulfide Delivery Molecules Protect Against UVA-Induced Photoaging in Human Dermal Fibroblasts, and in Mouse Skin In Vivo

Aims: Oxidative stress and mitochondrial dysfunction play a role in the process of skin photoaging via activation of matrix metalloproteases (MMPs) and the subsequent degradation of collagen. The activation of nuclear factor E2-related factor 2 (Nrf2), a transcription factor controlling antioxidant and cytoprotective defense systems, might offer a pharmacological approach to prevent skin photoaging. We therefore investigated a pharmacological approach to prevent skin photoaging, and also investigated a protective effect of the novel mitochondria-targeted hydrogen sulfide (H₂S) delivery molecules AP39 and AP123, and nontargeted control molecules, on ultraviolet A light (UVA)-induced photoaging in normal human dermal fibroblasts (NHDFs) in vitro and the skin of BALB/c mice in vivo. Results: In NHDFs, AP39 and AP123 (50-200 nM) but not nontargeted controls suppressed UVA (8 J/cm²)-mediated cytotoxicity and induction of MMP-1 activity, preserved cellular bioenergetics, and increased the expression of collagen and nuclear levels of Nrf2. In in vivo experiments, topical application of AP39 or AP123 (0.3-1 μM/cm²; but not nontargeted control molecules) to mouse skin before UVA (60 J/cm²) irradiation prevented skin thickening, MMP induction, collagen loss of oxidative stress markers 8-hydroxy-2'-deoxyguanosine (8-OHdG), increased Nrf2-dependent signaling, as well as increased manganese superoxide dismutase levels and levels of the mitochondrial biogenesis marker peroxisome proliferator-activated receptor-gamma coactivator (PGC-1α). Innovation and Conclusion: Targeting H₂S delivery to mitochondria may represent a novel approach for the prevention and treatment of skin photoaging, as well as being useful tools for determining the role of mitochondrial H₂S in skin disorders and aging. Antioxid. Redox Signal. 36, 1268-1288.

Rutin Inhibits the Progression of Osteoarthritis Through CBS-Mediated RhoA/ROCK Signaling

Osteoarthritis (OA) is a chronic joint disease characterized by the deterioration of cartilage and subchondral bone in the joints. Currently, there is no complete cure for OA, only treatments designed to temporarily relieve pain and improve function. Compared with the high cost of surgical treatment, medical treatment of OA is more acceptable and cost-effective. Rutin, as a flavonoid, has been shown to have anti-OA properties. We evaluated the effects of rutin on chondrocytes in lipopolysaccharide (LPS)-induced OA and on OA in rats induced by anterior cruciate ligament transection. We found that rutin effectively reduced the expression levels of inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2), tumor necrosis factor-α (TNF-α), and matrix metalloproteinase 13 (MMP-13) and increased the expression of Col II and aggrecan (p < 0.001). In addition, we also found that rutin increased the expression of cystathionine-β-synthase (CBS) and inhibited the expression of Rho-related coiled-coil protein kinase (ROCK) in chondrocytes (p < 0.05), thereby effectively inhibiting the inflammatory progression of OA. We concluded that rutin inhibits the inflammatory progression of OA through the CBS-mediated RhoA/ROCK signaling pathway.

Medical Gas Therapy for Tissue, Organ, and CNS Protection: A Systematic Review of Effects, Mechanisms, and Challenges

Gaseous molecules have been increasingly explored for therapeutic development. Here, following an analytical background introduction, a systematic review of medical gas research is presented, focusing on tissue protections, mechanisms, data tangibility, and translational challenges. The pharmacological efficacies of carbon monoxide (CO) and xenon (Xe) are further examined with emphasis on intracellular messengers associated with cytoprotection and functional improvement for the CNS, heart, retina, liver, kidneys, lungs, etc. Overall, the outcome supports the hypothesis that readily deliverable "biological gas" (CO, H2 , H2 S, NO, O2 , O3 , and N2 O) or "noble gas" (He, Ar, and Xe) treatment may preserve cells against common pathologies by regulating oxidative, inflammatory, apoptotic, survival, and/or repair processes. Specifically, CO, in safe dosages, elicits neurorestoration via igniting sGC/cGMP/MAPK signaling and crosstalk between HO-CO, HIF-1α/VEGF, and NOS pathways. Xe rescues neurons through NMDA antagonism and PI3K/Akt/HIF-1α/ERK activation. Primary findings also reveal that the need to utilize cutting-edge molecular and genetic tactics to validate mechanistic targets and optimize outcome consistency remains urgent; the number of neurotherapeutic investigations is limited, without published results from large in vivo models. Lastly, the broad-spectrum, concurrent multimodal homeostatic actions of medical gases may represent a novel pharmaceutical approach to treating critical organ failure and neurotrauma.

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 Stress and Gut Microbiome in Inflammatory Skin Diseases

Oxidative stress plays a dominant role in inflammatory skin diseases. Emerging evidence has shown that the close interaction occurred between oxidative stress and the gut microbiome. Overall, in this review, we have summarized the impact of oxidative stress and gut microbiome during the progression and treatment for inflammatory skin diseases, the interactions between gut dysbiosis and redox imbalance, and discussed the potential possible role of oxidative stress in the gut-skin axis. In addition, we have also elucidated the promising gut microbiome/redox-targeted therapeutic strategies for inflammatory skin diseases.

Hydrogen Sulfide and the Immune System

Hydrogen sulfide (H₂S) is the "third gasotransmitter" recognized alongside nitric oxide (NO) and carbon monoxide (CO). H₂S exhibits an array of biological effects in mammalian cells as revealed by studies showing important roles in the cardiovascular system, in cell signalling processes, post-translational modifications and in the immune system. Regarding the latter, using pharmacological and genetic approaches scientists have shown this molecule to have both pro- and anti-inflammatory effects in mammalian systems. The anti-inflammatory effects of H₂S appeared to be due to its inhibitory action on the nuclear factor kappa beta signalling pathway; NF-kB representing a transcription factor involved in the regulation pro-inflammatory mediators like nitric oxide, prostaglandins, and cytokines. In contrast, results from several animal model describe a more complicated picture and report on pro-inflammatory effects linked to exposure to this molecule; linked to dosage used and point of administration of this molecule. Overall, roles for H₂S in several inflammatory diseases spanning arthritis, atherosclerosis, sepsis, and asthma have been described by researchers. In light this work fascinating research, this chapter will cover H₂S biology and its many roles in the immune system.

Regulatory Role of Nrf2 Signaling Pathway in Wound Healing Process

Wound healing involves a series of cellular events in damaged cells and tissues initiated with hemostasis and finally culminating with the formation of a fibrin clot. However, delay in the normal wound healing process during pathological conditions due to reactive oxygen species, inflammation and immune suppression at the wound site represents a medical challenge. So far, many therapeutic strategies have been developed to improve cellular homeostasis and chronic wounds in order to accelerate wound repair. In this context, the role of Nuclear factor erythroid 2-related factor 2 (Nrf2) during the wound healing process has been a stimulating research topic for therapeutic perspectives. Nrf2 is the main regulator of intracellular redox homeostasis. It increases cytoprotective gene expression and the antioxidant capacity of mammalian cells. It has been reported that some bioactive compounds attenuate cellular stress and thus accelerate cell proliferation, neovascularization and repair of damaged tissues by promoting Nrf2 activation. This review highlights the importance of the Nrf2 signaling pathway in wound healing strategies and the role of bioactive compounds that support wound repair through the modulation of this crucial transcription factor.

Hydrogen sulfide: Recent progress and perspectives for the treatment of dermatological diseases

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Three hydrogen sulfide (H₂S) production enzymes including CSE, CBS and 3-MST exist in the skin.

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H₂S regulates burn, diabetic skin wound, psoriasis, systemic sclerosis, melanoma, and pruritus.

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H₂S regulates oxidative stress, inflammation, angiogenesis and apoptosis in skin diseases.

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Some ideal characteristics of H₂S-based therapeutics for topical delivery are preferred.

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Therapeutic potential of H₂S for skin disorders will be further proposed in clinical trials.

Background

Hydrogen sulfide (H₂S) is now recognized as a vital endogenous gasotransmitter with a variety of biological functions in different systems. Recently, studies have increasingly focused on the role of H₂S in the skin.

Aim of Review

This review summarizes recent progress and provides perspectives on H₂S in the treatment of dermatological diseases.

Key Scientific Concepts of Review

Three H₂S production enzymes, cystathionine-γ-lyase (CSE), cystathionine-β-synthase (CBS) and 3-mercaptopyruvate sulfur transferase (3-MST), are all present in the skin, and it is likely that different cell types in the skin express them differently. Previous studies have demonstrated that H₂S protects against several dermatological diseases, such as burns, diabetic skin wounds, psoriasis, skin flap transplantation, systemic sclerosis, melanoma, and pruritus. The mechanism might be related to the regulation of oxidative stress, inflammation, angiogenesis, apoptosis, and allergic reactions. H₂S-based therapeutics require certain characteristics for topical delivery, for example, controlled release, appropriate physicochemical properties, good storage stability, acceptable odor, and advanced delivery systems. H₂S-induced S-sulfhydration on proteins are potential novel targets for therapeutic intervention and drug design for the skin, which may lead to the development and application of H₂S-related drugs for dermatological diseases.

Hydrogen Sulfide in Bone Tissue Regeneration and Repair: State of the Art and New Perspectives

The importance of hydrogen sulfide (H₂S) in the regulation of multiple physiological functions has been clearly recognized in the over 20 years since it was first identified as a novel gasotransmitter. In bone tissue H₂S exerts a cytoprotective effect and promotes bone formation. Just recently, the scientific community has begun to appreciate its role as a therapeutic agent in bone pathologies. Pharmacological administration of H₂S achieved encouraging results in preclinical studies in the treatment of systemic bone diseases, such as osteoporosis; however, a local delivery of H₂S at sites of bone damage may provide additional opportunities of treatment. Here, we highlight how H₂S stimulates multiple signaling pathways involved in various stages of the processes of bone repair. Moreover, we discuss how material science and chemistry have recently developed biomaterials and H₂S-donors with improved features, laying the ground for the development of H₂S-releasing devices for bone regenerative medicine. This review is intended to give a state-of-the-art description of the pro-regenerative properties of H₂S, with a focus on bone tissue, and to discuss the potential of H₂S-releasing scaffolds as a support for bone repair.