The role of AKT1 and autophagy in the protective effect of hydrogen sulphide against hepatic ischemia/reperfusion injury in mice

Identification and validation of ferroptosis-related hub genes and immune infiltration in liver ischemia-reperfusion injury

Ischemia-reperfusion injury (IRI) is a cumulation of pathophysiological processes that involves cell and organelle damage upon blood flow constraint and subsequent restoration. However, studies on overall immune infiltration and ferroptosis in liver ischemia-reperfusion injury (LIRI) are limited. This study explored immune cell infiltration and ferroptosis in LIRI using bioinformatics and experimental validation. The GSE151648 dataset, including 40 matched pairs of pre- and post- transplant liver samples was downloaded for bioinformatic analysis. Eleven hub genes were identified by overlapping differentially expressed genes (DEGs), iron genes, and genes identified through weighted gene co-expression network analysis (WGCNA). Subsequently, the pathway enrichment, transcription factor-target, microRNA-mRNA and protein-protein interaction networks were investigated. The diagnostic model was established by logistic regression, which was validated in the GSE23649 and GSE100155 datasets and verified using cytological experiments. Moreover, several drugs targeting these genes were found in DrugBank, providing a more effective treatment for LIRI. In addition, the expression of 11 hub genes was validated using quantitative real-time polymerase chain reaction (qRT-PCR) in liver transplantation samples and animal models. The expression of the 11 hub genes increased in LIRI compared with the control. Five genes were significantly enriched in six biological process terms, six genes showed high enrichment for LIRI-related signaling pathways. There were 56 relevant transcriptional factors and two central modules in the protein-protein interaction network. Further immune infiltration analysis indicated that immune cells including neutrophils and natural killer cells were differentially accumulated in the pre- and post-transplant groups, and this was accompanied by changes in immune-related factors. Finally, 10 targeted drugs were screened. Through bioinformatics and further experimental verification, we identified hub genes related to ferroptosis that could be used as potential targets to alleviate LIRI.

Hydrogen sulphide reduces renal ischemia-reperfusion injury by enhancing autophagy and reducing oxidative stress

AIM

Renal ischemia-reperfusion injury (IRI) is a major cause of acute kidney injury. Hydrogen sulphide (H2S) exerts a protective effect in renal IRI. The present study was carried out to investigate the effects of exogenous H2S on renal IRI by regulating autophagy in mice.

METHODS

Mice were randomly assigned to control, IRI and NaHS (an H2S donor, 28, 56 and 100 μmol/kg) groups. Renal IRI was induced by clamping the bilateral renal pedicles with non-traumatic arterial clamp for 45 min and then reperfused for 24 h. Mice were administered intraperitoneally with NaHS 20 min prior to renal ischemia. Sham group mice underwent the same procedures without clamping. Serum and kidney tissues were harvested 24 h after reperfusion for functional, histological, oxidative stress, and autophagic determination.

RESULTS

Compared with the control group, the concentrations of serum creatinine (Scr), blood urea nitrogen (BUN), and malondialdehyde (MDA), the protein levels of LC3II/I, Beclin-1 and P62, as well as the number of autophagosomes were significantly increased, but the activity of superoxide dismutase (SOD) was decreased after renal IRI. NaHS pre-treatment dramatically attenuated renal IRI-induced renal dysfunction, histological changes, MDA concentration and p62 expression in a dose-dependent manner. However, NaHS increased the SOD activity and the protein levels of LC3II/I and Beclin-1.

CONCLUSION

These results indicate that exogenous H2S protects the kidney from IRI through enhancement of autophagy and reduction of oxidative stress. Novel H2S donors could be developed in the treatment of renal IRI.

FGF21 protects against ischaemia reperfusion injury in normal and fatty livers

BACKGROUND

Liver ischaemia/reperfusion (I/R) injury, which is an inevitable clinical problem of liver resection, liver transplantation and haemorrhagic shock. Fibroblast growth factor 21 (FGF21) was intimately coupled with multiple metabolic processes and proved to protect against apoptosis and inflammatory response in hepatocytes during hepatic I/R injury. However, the regulatory mechanisms of FGF21 in hepatic I/R injury remains unknown. Therefore, we hypothesize that FGF21 protects hepatic tissues from I/R injury.

METHODS

Blood samples were available from haemangiomas patients undergoing hepatectomy and murine liver I/R model and used to further evaluate the serum levels of FGF21 both in humans and mice. We further explored the regulatory mechanisms of FGF21 in murine liver I/R model by using FGF21-knockout mice (FGF21-KO mice) and FGF21-overexpression transgenic mice (FGF21-OE mice) fed a high-fat or ketogenic diet.

RESULTS

Our results show that the circulating levels of FGF21 were robustly decreased after liver I/R in both humans and mice. Silencing FGF21 expression with FGF21-KO mice aggravates liver injury at 6 h after 75 min of partial liver ischaemia, while FGF21-OE mice display alleviated hepatic I/R injury and inflammatory response. Compared with chow diet mice, exogenous FGF21 decreases the levels of aminotransferase, histological changes, apoptosis and inflammatory response in hepatic I/R injury treatment mice with a high-fat diet. Meanwhile, ketogenic diet mice are not sensitive to hepatic I/R injury.

CONCLUSIONS

The circulating contents of FGF21 are decreased during liver warm I/R injury and exogenous FGF21 exerts hepatoprotective effects on hepatic I/R injury. Thus, FGF21 regulates hepatic I/R injury and may be a key therapeutic target.

Therapeutic Potential of Hydrogen Sulfide in Ischemia and Reperfusion Injury

Ischemia-reperfusion (I/R) injury, a prevalent pathological condition in medical practice, presents significant treatment challenges. Hydrogen sulfide (H2S), acknowledged as the third gas signaling molecule, profoundly impacts various physiological and pathophysiological processes. Extensive research has demonstrated that H2S can mitigate I/R damage across multiple organs and tissues. This review investigates the protective effects of H2S in preventing I/R damage in the heart, brain, liver, kidney, intestines, lungs, stomach, spinal cord, testes, eyes, and other tissues. H2S provides protection against I/R damage by alleviating inflammation and endoplasmic reticulum stress; inhibiting apoptosis, oxidative stress, and mitochondrial autophagy and dysfunction; and regulating microRNAs. Significant advancements in understanding the mechanisms by which H2S reduces I/R damage have led to the development and synthesis of H2S-releasing agents such as diallyl trisulfide-loaded mesoporous silica nanoparticles (DATS-MSN), AP39, zofenopril, and ATB-344, offering a new therapeutic avenue for I/R injury.

Coated sodium butyrate ameliorates high-energy and low-protein diet induced hepatic dysfunction via modulating mitochondrial dynamics, autophagy and apoptosis in laying hens

BACKGROUND

Fatty liver hemorrhagic syndrome (FLHS), a fatty liver disease in laying hens, poses a grave threat to the layer industry, stemming from its ability to trigger an alarming plummet in egg production and usher in acute mortality among laying hens. Increasing evidence suggests that the onset and progression of fatty liver was closely related to mitochondria dysfunction. Sodium butyrate was demonstrated to modulate hepatic lipid metabolism, alleviate oxidative stress and improve mitochondrial dysfunction in vitro and mice models. Nevertheless, there is limited existing research on coated sodium butyrate (CSB) to prevent FLHS in laying hens, and whether and how CSB exerts the anti-FLHS effect still needs to be explored. In this experiment, the FLHS model was induced by administering a high-energy low-protein (HELP) diet in laying hens. The objective was to investigate the effects of CSB on alleviating FLHS with a focus on the role of CSB in modulating mitochondrial function.

METHODS

A total of 288 healthy 28-week-old Huafeng laying hens were arbitrarily allocated into 4 groups with 6 replicates each, namely, the CON group (normal diet), HELP group (HELP diet), CH500 group (500 mg/kg CSB added to HELP diet) and CH750 group (750 mg/kg CSB added to HELP diet). The duration of the trial encompassed a period of 10 weeks.

RESULTS

The result revealed that CSB ameliorated the HELP-induced FLHS by improving hepatic steatosis and pathological damage, reducing the gene levels of fatty acid synthesis, and promoting the mRNA levels of key enzymes of fatty acid catabolism. CSB reduced oxidative stress induced by the HELP diet, upregulated the activity of GSH-Px and SOD, and decreased the content of MDA and ROS. CSB also mitigated the HELP diet-induced inflammatory response by blocking TNF-α, IL-1β, and F4/80. In addition, dietary CSB supplementation attenuated HELP-induced activation of the mitochondrial unfolded protein response (UPRmt), mitochondrial damage, and decline of ATPase activity. HELP diet decreased the autophagosome formation, and downregulated LC3B but upregulated p62 protein expression, which CSB administration reversed. CSB reduced HELP-induced apoptosis, as indicated by decreases in the Bax/Bcl-2, Caspase-9, Caspase-3, and Cyt C expression levels.

CONCLUSIONS

Dietary CSB could ameliorate HELP diet-induced hepatic dysfunction via modulating mitochondrial dynamics, autophagy, and apoptosis in laying hens. Consequently, CSB, as a feed additive, exhibited the capacity to prevent FLHS by modulating autophagy and lipid metabolism.

Hydrogen Sulfide and Liver Health: Insights into Liver Diseases

Significance: Hydrogen sulfide (H2S) is a recently recognized gasotransmitter involved in physiological and pathological conditions in mammals. It protects organs from oxidative stress, inflammation, hypertension, and cell death. With abundant expression of H2S-production enzymes, the liver is closely linked to H2S signaling. Recent Advances: Hepatic H2S comes from various sources, including gut microbiota, exogenous sulfur salts, and endogenous production. Recent studies highlight the importance of hepatic H2S in liver diseases such as nonalcoholic fatty liver disease (NAFLD), liver injury, and cancer, particularly at advanced stages. Endogenous H2S production deficiency is associated with severe liver disease, while exogenous H2S donors protect against liver dysfunction. Critical Issues: However, the roles of H2S in NAFLD, liver injury, and liver cancer are still debated, and its effects depend on donor type, dosage, treatment duration, and cell type, suggesting a multifaceted role. This review aimed to critically evaluate H2S production, metabolism, mode of action, and roles in liver function and disease. Future Direction: Understanding H2S's precise roles and mechanisms in liver health will advance potential therapeutic applications in preclinical and clinical research. Targeting H2S-producing enzymes and exogenous H2S sources, alone or in combination with other drugs, could be explored. Quantifying endogenous H2S levels may aid in diagnosing and managing liver diseases. Antioxid. Redox Signal. 40, 122-144.

PPARβ/δ activation protects against hepatic ischaemia-reperfusion injury

BACKGROUND AND AIMS

Hepatic ischaemia/reperfusion injury (HIRI) is a pathophysiological process that occurs during the liver resection and transplantation. Reportedly, peroxisome proliferator-activated receptor β/δ (PPARβ/δ) can ameliorate kidney and myocardial ischaemia/reperfusion injury. However, the effect of PPARβ/δ in HIRI remains unclear.

METHODS

Mouse hepatic ischaemia/reperfusion (I/R) models were constructed for in vivo study. Primary hepatocytes and Kupffer cells (KCs) isolated from mice and cell anoxia/reoxygenation (A/R) injury model were constructed for in vitro study. Liver injury and inflammation were investigated. Small molecular compounds (GW0742 and GSK0660) and adenoviruses were used to interfere with PPARβ/δ.

RESULTS

We found that PPARβ/δ expression was increased in the I/R and A/R models. Overexpression of PPARβ/δ in hepatocytes alleviated A/R-induced cell apoptosis, while knockdown of PPARβ/δ in hepatocytes aggravated A/R injury. Activation of PPARβ/δ by GW0742 protected against I/R-induced liver damage, inflammation and cell death, whereas inhibition of PPARβ/δ by GSK0660 had the opposite effects. Consistent results were obtained in mouse I/R models through the tail vein injection of adenovirus-mediated PPARβ/δ overexpression or knockdown vectors. Furthermore, knockdown and overexpression of PPARβ/δ in KCs aggravated and ameliorated A/R-induced hepatocyte injury, respectively. Gene ontology and gene set enrichment analysis showed that PPARβ/δ deletion was significantly enriched in the NF-κB pathway. PPARβ/δ inhibited the expression of p-IKBα and p-P65 and decreased NF-κB activity.

CONCLUSIONS

PPARβ/δ exerts anti-inflammatory and anti-apoptotic effects on HIRI by inhibiting the NF-κB pathway, and hepatocytes and KCs may play a synergistic role in this phenomenon. Thus, PPARβ/δ is a potential therapeutic target for HIRI.

LncRNA Hnf4αos exacerbates liver ischemia/reperfusion injury in mice via Hnf4αos/Hnf4α duplex-mediated PGC1α suppression

LncRNAs are involved in the pathophysiologic processes of multiple diseases, but little is known about their functions in hepatic ischemia/reperfusion injury (HIRI). As a novel lncRNA, the pathogenetic significance of hepatic nuclear factor 4 alpha, opposite strand (Hnf4αos) in hepatic I/R injury remains unclear. Here, differentially expressed Hnf4αos and Hnf4α antisense RNA 1 (Hnf4α-as1) were identified in liver tissues from mouse ischemia/reperfusion models and patients who underwent liver resection surgery. Hnf4αos deficiency in Hnf4αos-KO mice led to improved liver function, alleviated the inflammatory response and reduced cell death. Mechanistically, we found a regulatory role of Hnf4αos-KO in ROS metabolism through PGC1α upregulation. Hnf4αos also promoted the stability of Hnf4α mRNA through an RNA/RNA duplex, leading to the transcriptional activation of miR-23a and miR-23a depletion was required for PGC1α function in hepatoprotective effects on HIRI. Together, our findings reveal that Hnf4αos elevation in HIRI leads to severe liver damage via Hnf4αos/Hnf4α/miR-23a axis-mediated PGC1α inhibition.

Integrative analysis of the roles of lncRNAs and mRNAs in ischaemic preconditioning to alleviate liver ischaemia-reperfusion injury in mice

The objective of our study was to elucidate the possible underlying mechanism for the protective effect of ischaemic preconditioning (IPC) against ischaemia-reperfusion (I/R) injury and to provide new research perspectives of long non-coding RNAs (lncRNAs). In this study, serum and liver tissue samples were collected to measure indexes of liver injury from a mouse liver model in sham, I/R injury and I/R + IPC groups. Furthermore, liver samples from 5 randomly selected mice per group were extracted and subjected to the microarray and subsequent bioinformatics analysis. IPC ameliorated liver damage by lowered liver transaminase levels and pro-inflammatory cytokines. A total of 167 lncRNAs and 108 messenger RNAs (mRNAs) were significantly differentially expressed genes (DEGs) between the I/R + IPC and I/R groups. Gene Ontology (GO) analysis revealed that these genes were mainly related to unfolded proteins, responses to topologically incorrect proteins, responses to temperature stimuli, protein folding and protein refolding. Kyoto Encyclopaedia of Genes and Genomes (KEGG) pathway analysis indicated that the DEGs were enriched in the following pathways: protein processing in the endoplasmic reticulum; antigen processing and presentation; and fructose and mannose metabolism. Additionally, the 7 selected DEGs (Hspa1ab, Chka, Clec2h, Mvd, Adra1a, AK085737 and AK088966) were validated in modules of the lncRNA-mRNA weighted coexpression network, which agreed with the qRT-PCR and chip data. And the identified differentially expressed lncRNAs and mRNAs may provide new clues to understand the pivotal pathophysiological mechanism by which IPC alleviates I/R-caused liver damage.

Receptor for Advanced Glycation End Products (RAGE): A Pivotal Hub in Immune Diseases

As a critical molecule in the onset and sustainment of inflammatory response, the receptor for advanced glycation end products (RAGE) has a variety of ligands, such as advanced glycation end products (AGEs), S100/calcium granule protein, and high-mobility group protein 1 (HMGB1). Recently, an increasing number studies have shown that RAGE ligand binding can initiate the intracellular signal cascade, affect intracellular signal transduction, stimulate the release of cytokines, and play a vital role in the occurrence and development of immune-related diseases, such as systemic lupus erythematosus, rheumatoid arthritis, and Alzheimer’s disease. In addition, other RAGE signaling pathways can play crucial roles in life activities, such as inflammation, apoptosis, autophagy, and endoplasmic reticulum stress. Therefore, the strategy of targeted intervention in the RAGE signaling pathway may have significant therapeutic potential, attracting increasing attention. In this paper, through the systematic induction and analysis of RAGE-related signaling pathways and their regulatory mechanisms in immune-related diseases, we provide theoretical clues for the follow-up targeted intervention of RAGE-mediated diseases.

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.

Identifying the Mechanism of Polygoni Cuspidati Rhizoma et Radix in Treating Acute Liver Failure Based on Network Pharmacology and Molecular Docking

Materials and Methods

The potential bioactive compounds of PCRR and their targets were collected from TCMSP, TCMID, and BATMAN-TCM databases with absorption, distribution, metabolism, and excretion protocols (oral bioavailability ≥30% and drug-likeness ≥0.18). The ALF-related target genes were identified using the GeneCards and OMIM databases. A protein-protein interaction (PPI) network among these targets was constructed using the Cytoscape software to obtain the core targets. The genes associated with ALF were analyzed via Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses to identify the signaling pathways related to the therapeutic effect of PCRR in ALF.

Results

In total, 10 bioactive compounds of PCRR and 200 targets related to them were obtained, and 2913 ALF-related target genes were identified. PPI network analysis pinpointed 15 core targets, namely, TP53, AKT1, JUN, HSP90AA1, MAPK1, RELA, TNF, ESR1, IL6, MYC, MAPK14, FOS, RB1, CDKN1A, and EGFR. GO enrichment and KEGG pathway analyses revealed that the therapeutic mechanisms of PCRR in ALF are related to cell metabolism, oxidative stress, inflammation, and hepatocyte apoptosis.

Conclusion

This is the first study to explore the therapeutic mechanisms of PCRR in ALF via network pharmacology and molecular docking. This study provides a research platform with candidate ALF-related targets of PRCC for the development of therapeutics against ALF.

Stellate Ganglion Block Improves the Proliferation and Function of Splenic CD4 + T Cells Through Inhibition of Posthemorrhagic Shock Mesenteric Lymph-Mediated Autophagy

Severe hemorrhagic shock leads to excessive inflammation and immune dysfunction, which results in high mortality related to mesenteric lymph return. A recent study showed that stellate ganglion block (SGB) increased the survival rate in rats suffering hemorrhagic shock. However, whether SGB ameliorates immune dysfunction induced by hemorrhagic shock remains unknown. The aim of the present study was to verify the favorable effects of SGB on the proliferation and function of splenic CD4 + T cells isolated from rats that underwent hemorrhagic shock and to investigate the mechanism related to the SGB interaction with autophagy and posthemorrhagic shock mesenteric lymph (PHSML). Male rats underwent SGB or sham SGB and conscious acute hemorrhage followed by resuscitation and multiple treatments. After 3 h of resuscitation, splenic CD4 + T cells were isolated to measure proliferation and cytokine production following stimulation with ConA in vitro. CD4 + T cells isolated from normal rats were treated with PHSML drained from SBG-treated rats, and proliferation, cytokine production, and autophagy biomarkers were detected. Hemorrhagic shock reduced CD4 + T cell proliferation and production of interleukin (IL)-2, IL-4, and tumor necrosis factor-α-induced protein 8-like 2 (TIPE2). SGB or administration of the autophagy inhibitor 3-methyladenine (3-MA) normalized these indicators. In contrast, administration of rapamycin (RAPA) autophagy agonist or intravenous injection of PHSML inhibited the beneficial effects of SGB on CD4 + T cells from hemorrhagic shocked rats. Furthermore, PHSML incubation decreased proliferation and cytokine production, increased LC3 II/I and Beclin-1 expression, and reduced p-PI3K and p-Akt expression in normal CD4 + T cells. These adverse effects of PHSML were also abolished by 3-MA administration, as well as incubation with PHSML obtained from SGB-treated rats. SGB improves splenic CD4 + T cell function following hemorrhagic shock, which is related to the inhibition of PHSML-mediated autophagy.

Integrative Analysis of the Roles of lncRNAs and mRNAs in Itaconate-Mediated Protection Against Liver Ischemia-Reperfusion Injury in Mice

Purpose

Itaconate is well known for its strong anti-inflammatory and antioxidant effect, but little is known about the potential role of long non-coding RNAs (lncRNAs) in the underlying mechanisms of hepatic ischemia-reperfusion (IR) injury. The aim of our study is to identify lncRNAs related to IR injury and itaconate-mediated protection and to demonstrate the mechanism by which itaconate acts in liver IR injury from the new perspective of lncRNAs.

Methods

4-Octyl itaconate (OI), a membrane-permeable derivative of itaconate, was used as a substitute for itaconate in our study. By using a mouse model of hepatic IR injury, serum and liver samples were collected to measure indexes of liver injury. Then, the liver samples of the mice were subjected to RNA sequencing (RNA-seq) and subsequent bioinformatics analysis.

Results

Itaconate attenuated liver IR injury. A total of 138 lncRNAs and 156 messenger RNAs (mRNAs) were markedly differentially expressed in the IR-damaged liver tissues pretreated with OI compared with the matched liver tissues treated with vehicle. Functional analysis indicated that lncRNAs may indirectly participate in the effects of itaconate. Furthermore, 41 mRNAs were examined for the protein-protein interaction (PPI) network analysis, and a key gene cluster was defined. Then, combined the coexpression analysis and the cis and trans regulatory function prediction of lncRNAs, some "candidate" lncRNA-mRNA pairs which might relate to itaconate-mediated liver protection were identified, while the relationship requires future validation.

Conclusion

Our study revealed that itaconate could protect the liver against IR injury and that lncRNAs might play a role in this process. Our study provides a novel way to investigate the mechanism by which itaconate affects hepatic IR injury and exerts its anti-inflammatory and antioxidative stress effects.

An evolutionary perspective on the interplays between hydrogen sulfide and oxygen in cellular functions

The physiological effects of the endogenously generated hydrogen sulfide (H2S) have been extensively studied in recent years. This review summarized the role of H2S in the origin of life and H2S metabolism in organisms from bacteria to vertebrates, examined the relationship between H2S and oxygen from an evolutionary perspective and emphasized the oxygen-dependent manner of H2S signaling in various physiological and pathological processes. H2S and oxygen are inextricably linked in various cellular functions. H2S is involved in aerobic respiration and stimulates oxidative phosphorylation and ATP production within the cell. Besides, H2S has protective effects on ischemia and reperfusion injury in several organs by acting as an oxygen sensor. Also, emerging evidence suggests the role of H2S is in an oxygen-dependent manner. All these findings indicate the subtle relationship between H2S and oxygen and further explain why H2S, a toxic molecule thriving in an anoxia environment several billion years ago, still affects homeostasis today despite the very low content in the body.

Autophagy inhibitors 3-MA and LY294002 repress osteoclastogenesis and titanium particle-stimulated osteolysis

Aseptic loosening caused by peri-implant osteolysis (PIO) is a common complication after joint replacement, and there is still no better treatment than revision surgery. The wear particle-induced inflammation response, especially subsequent osteoclastic bone resorption, is responsible for PIO. As the importance of wear particles in inducing autophagy in cells around the prosthesis in PIO has been discovered, this might be a central process underlying aseptic loosening. However, the role of autophagy induced by wear particles in osteoclastogenesis during PIO remains unclear. In this study, we investigated the role of autophagy in osteoclastogenesis and verified it in a mouse calvarial osteolysis model. We found that osteoclasts were increased in the interface membranes of patients with aseptic loosening. In vitro, knocking down the Atg5 gene or using autophagy inhibitors (3-MA, LY294002) to inhibit autophagy was found to repress osteoclastogenesis and decrease expression of the osteoclast-related genes TRAP, cathepsin K, and matrix metalloprotein 9 (MMP-9) with or without titanium (Ti) particles. In vivo, 3-MA and LY294002 repressed Ti particle-stimulated osteolysis and osteoclastogenesis and reduced expression of the pro-inflammatory factors TNF-α, IL-1β, and IL-6. Our results suggest that 3-MA and LY294002 might be the potential medicines to prevent and treat PIO and aseptic loosening.

PGC-1α Protects against Hepatic Ischemia Reperfusion Injury by Activating PPARα and PPARγ and Regulating ROS Production

Peroxisome proliferator-activated receptors (PPARs) α and γ have been shown to be protective in hepatic ischemia/reperfusion (I/R) injury. However, the precise role of PPARγ coactivator-1α (PGC-1α), which can coactivate both of these receptors, in hepatic I/R injury, remains largely unknown. This study was designed to test our hypothesis that PGC-1α is protective during hepatic I/R injury in vitro and in vivo. Our results show that endogenous PGC-1α is basally expressed in normal livers and is moderately increased by I/R. Ectopic PGC-1α protects against hepatic I/R and hepatocyte anoxia/reoxygenation (A/R) injuries, whereas knockdown of endogenous PGC-1α aggravates such injuries, as evidenced by assessment of the levels of serum aminotransferases and inflammatory cytokines, necrosis, apoptosis, cell viability, and histological examination. The EMSA assay shows that the activation of PPARα and PPARγ is increased or decreased by the overexpression or knockdown of PGC-1α, respectively, during hepatic I/R and hepatocyte A/R injuries. In addition, the administration of specific antagonists of either PPARα (MK886) or PPARγ (GW9662) can effectively decrease the protective effect of PGC-1α against hepatic I/R and hepatocyte A/R injuries. We also demonstrate an important regulatory role of PGC-1α in reactive oxygen species (ROS) metabolism during hepatic I/R, which is correlated with the induction of ROS-detoxifying enzymes and is also dependent on the activations of PPARα and PPARγ. These data demonstrate that PGC-1α protects against hepatic I/R injury, mainly by regulating the activation of PPARα and PPARγ. Thus, PGC-1α may be a promising therapeutic target for the protection of the liver against I/R injury.

Exogenous Hydrogen Sulfide Plays an Important Role Through Regulating Autophagy in Ischemia/Reperfusion Injury

Ischemia/reperfusion (I/R) injury is characterized by limiting blood supply to organs, then restoring blood flow and reoxygenation. It leads to many diseases, including acute kidney injury, myocardial infarction, circulatory arrest, ischemic stroke, trauma, and sickle cell disease. Autophagy is an important and conserved cellular pathway, in which cells transfer the cytoplasmic contents to lysosomes for degradation. It plays an important role in maintaining the balance of cell synthesis, decomposition and reuse, and participates in a variety of physiological and pathological processes. Hydrogen sulfide (H₂S), along with carbon monoxide (CO) and nitric oxide (NO), is an important gas signal molecule and regulates various physiological and pathological processes. In recent years, there are many studies on the improvement of I/R injury by H₂S through regulating autophagy, but the related mechanisms are not completely clear. Therefore, we summarize the related research in the above aspects to provide theoretical reference for future in-depth research.

Sodium orthovanadate inhibits growth of acute leukemia HL60 cells and HL60/A cells in vitro

Vanadium is an ultratrace element. The transition metal vanadium, widely exists in the environment and exhibits various biological and physiological effects in the human body, yet with no presently known specific physiological function in mammals. Sodium orthovanadate (SOV) is a kind of vanadium compound. SOV has shown promising antineoplastic activity in several human cancers. But the effects of SOV on acute promyelocytic leukemia (APL) are still unknown. In the present study, for the first time, we found that SOV could inhibit proliferation, induce G2/M cell cycle arrest and apoptosis, and could inhibit autophagy of acute leukemia cell lines in vitro. Thus, our findings suggest that SOV could effectively suppress the growth of acute leukemia HL60 cells and HL60/A cells through the regulations of proliferation, cell cycle, apoptosis and autophagy, and thus may act as a potential therapeutic agent in APL treatment.

Hydrogen sulfide-loaded microbubbles combined with ultrasound mediate thrombolysis and simultaneously mitigate ischemia-reperfusion injury in a rat hindlimb model

BACKGROUND

Thromboembolism and subsequent ischemia/reperfusion injury (IRI) remain major clinical challenges.

OBJECTIVES

To investigate whether hydrogen sulfide (H2 S)-loaded microbubbles (hs-Mbs) combined with ultrasound (US) radiation (hs-Mbs+US) dissolve thrombi and simultaneously alleviate tissue IRI through local H2 S release.

METHODS

hs-Mbs were manufactured and US-triggered H2 S release was recorded. White and red thromboembolisms were established ex vivo and in rats left iliac artery. All subjects randomly received control, US, Mbs+US, or hs-Mbs+US treatment for 30 minutes.

RESULTS

H2 S was released from hs-Mbs+US both ex vivo and in vivo. Compared with control and US, hs-Mbs+US and Mbs+US showed comparable substantial decreases in thrombotic area, clot mass, and flow velocity increases for both ex vivo macrothrombi. In vivo, hs-Mbs+US and Mbs+US caused similarly increased recanalization rates, blood flow velocities, and hindlimb perfusion for both thrombi compared with the other treatments, with no obvious influence on hemodynamics, respiration, and macrophage vitality. More importantly, hs-Mbs+US substantially alleviated skeletal muscle IRI by reducing reactive oxygen species, cellular apoptosis, and proapoptotic Bax, caspase-3, and caspase-9 and increasing antiapoptotic Bcl-2 compared with other treatments. In vitro, hypoxia/reoxygenation-predisposed skeletal muscle cells and endothelial cells treated with normal saline solution exhibited similar trends, which were largely reversed by an H2 S scavenger or an inhibitor of Akt phosphorylation.

CONCLUSION

hs-Mbs+US effectively dissolved both white and red macrothrombi and simultaneously alleviated skeletal muscle IRI through the US-triggered, organ-specific release of H2 S. This integrated therapeutic strategy holds promise for treating thromboembolic diseases and subsequent IRI.

Hydrogen sulfide-induced GAPDH sulfhydration disrupts the CCAR2-SIRT1 interaction to initiate autophagy

The deacetylase SIRT1 (sirtuin 1) has emerged as a major regulator of nucleocytoplasmic distribution of macroautophagy/autophagy marker MAP1LC3/LC3 (microtubule-associated protein 1 light chain 3). Activation of SIRT1 leads to the deacetylation of LC3 and its translocation from the nucleus into the cytoplasm leading to an increase in the autophagy flux. Notably, hydrogen sulfide (H₂S) is a cytoprotective gasotransmitter known to activate SIRT1 and autophagy; however, the underlying mechanism for both remains unknown. Herein, we demonstrate that H₂S sulfhydrates the active site cysteine of the glycolytic enzyme GAPDH (glyceraldehyde-3-phosphate dehydrogenase). Sulfhydration of GAPDH leads to its redistribution into the nucleus. Importantly, nuclear localization of GAPDH is critical for H₂S-mediated activation of autophagy as H₂S does not induce autophagy in cells with GAPDH ablation or cells overexpressing a GAPDH mutant lacking the active site cysteine. Importantly, we observed that nuclear GAPDH interacts with CCAR2/DBC1 (cell cycle activator a nd apoptosis regulator 2) inside the nucleus. CCAR2 interacts with the deacetylase SIRT1 to inhibit its activity. Interaction of GAPDH with CCAR2 disrupts the inhibitory effect of CCAR2 on SIRT1. Activated SIRT1 then deacetylates MAP1LC3B/LC3B (microtubule-associated protein 1 light chain 3 beta) to induce its translocation into the cytoplasm and activate autophagy. Additionally, we demonstrate this pathway's physiological role in autophagy-mediated trafficking of Mycobacterium tuberculosis into lysosomes to restrict intracellular mycobacteria growth. We think that the pathway described here could be involved in H₂S-mediated clearance of intracellular pathogens and other health benefits.Abbreviations: ATG5: autophagy related 5; ATG7: autophagy related 7; BECN1: beclin 1, autophagy related; CCAR2/DBC1: cell cycle activator and apoptosis regulator 2; CFU: colony-forming units; DLG4/PSD95: discs large MAGUK scaffold protein 4; EX-527: 6-chloro-2,3,4,9-tetrahydro-1H-carbazole-1-carboxamide; GAPDH: glyceraldehyde-3-phosphate dehydrogenase; H₂S: hydrogen sulfide; HEK: human embryonic kidney cells; MAP1LC3B/LC3B: microtubule-associated protein 1 light chain 3 beta; MEF: mouse embryonic fibroblast; Mtb: Mycobacterium tuberculosis; MTOR: mechanistic target of rapamycin kinase; MOI: multiplicity of infection; NO: nitric oxide; PI3K: phosphatidylinositol-4,5-bisphosphate 3-kinase; PLA: proximity ligation assay; PRKAA: protein kinase, AMP-activated, alpha catalytic subunit; SIAH1: siah E3 ubiquitin protein ligase 1A; SIRT1: sirtuin 1; TB: tuberculosis; TP53INP2/DOR: transformation related protein 53 inducible nuclear protein 2; TRP53/TP53: transformation related protein 53.

Hydrogen Sulfide Alleviates Liver Injury Through the S-Sulfhydrated-Kelch-Like ECH-Associated Protein 1/Nuclear Erythroid 2-Related Factor 2/Low-Density Lipoprotein Receptor-Related Protein 1 Pathway

BACKGROUND AND AIMS

Protein S-sulfhydration mediated by H₂ S has been shown to play important roles in several diseases. However, its precise role in liver disease and the related mechanism remain unclear.

APPROACH AND RESULTS

We showed that in streptozotocin (STZ)-treated and high-fat diet (HFD)-treated low-density lipoprotein receptor-negative (LDLr^-/- ) mice, the H₂ S donor GYY4137 ameliorated liver injury, decreased serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels, mitigated lipid deposition, and reduced hepatocyte death. Strikingly, S-sulfhydration of Kelch-like ECH-associated protein 1 (Keap1) was decreased in the livers of patients with fatty liver under diabetic conditions. In STZ+HFD-treated LDLr^-/- mice and in high glucose-treated and oxidized low-density lipoprotein (ox-LDL)-treated primary mouse hepatocytes, the GYY4137-mediated increase in Keap1 S-sulfhydration induced nuclear erythroid 2-related factor 2 (Nrf2) dissociation from Keap1, which enhanced the nuclear translocation of Nrf2 itself and the consequent expression of antioxidant proteins. Keap1 Cys151 mutation significantly reduced Keap1 S-sulfhydration and abolished the hepatoprotective effects of H₂ S both in vivo and in vitro. Nrf2 deficiency inhibited the H₂ S-induced beneficial impacts in Nrf2^-/- mice. Similarly, in CCl₄ -stimulated mice, GYY4137 increased Keap1 S-sulfhydration, improved liver function, alleviated liver fibrosis, decreased hepatic oxidative stress, and activated the Nrf2 signaling pathway; and these effects were abrogated after Keap1 Cys151 mutation. Moreover, H₂ S increased the binding of Nrf2 to the promoter region of LDLr-related protein 1 (Lrp1) and consequently up-regulated LRP1 expression, but these effects were disrupted by Keap1 Cys151 mutation.

CONCLUSIONS

H₂ S-mediated Keap1 S-sulfhydration alleviates liver damage through activation of Nrf2. Hence, administration of exogenous H₂ S in the form of the H₂ S donor GYY4137 may be of therapeutic benefit in the context of concurrent hyperlipidemia and hyperglycemia-induced or CCl₄ -stimulated liver dysfunction.

Systemic pharmacology understanding of the key mechanism of Sedum sarmentosum Bunge in treating hepatitis

Sedum sarmentosum Bunge is a Traditional Chinese Medicine that is widely used in treating hepatitis, whereas the detailed mechanisms have not been fully interpreted. A systemic pharmacology method including absorption, distribution, metabolism and elimination screening, drug targeting, interaction network plotting, and enrichment analysis was applied for exploring the underlying mechanisms of Sedum sarmentosum Bunge in the treatment of hepatitis. A total of 47 ingredients were identified in Sedum sarmentosum Bunge, and 5 active ingredients (DFV, isorhamnetin, beta-sitosterol, luteolin and quercetin) were screened out with the criteria of oral bioavailability (OB) ≥ 30% and drug-likeness (DL) ≥ 0.18. Those 5 ingredients interacted with 170 targets, 163 of which were hepatitis-related. By compound-target-disease network plotting, protein-protein interaction network plotting and enrichment analysis, the pathways that the 5 ingredients engaged in during hepatitis development and progression were investigated, such as threonine-protein kinase signaling. The integrated systemic pharmacology analysis facilitates the in-depth understanding of Sedum sarmentosum Bunge in the hepatitis treatment, which also paves the way for further knowledge of the molecular mechanism of Sedum sarmentosum Bunge in treating hepatitis.

Titanium particles induce apoptosis by promoting autophagy in macrophages via the PI3K/Akt signaling pathway

Chronic inflammation and infection in the tissue surrounding implants after total joint replacement is closely associated with the innate immune response to surgical implants. Wear particles are known to increase apoptosis and impair the innate immunity in macrophages, which can cause immunosuppression around the implants. Excessive autophagy can induce apoptosis. However, the link between autophagy and apoptosis in macrophages during chronic inflammation and infection remains unknown. In this study, we investigated the autophagy and apoptosis induced by titanium particles in RAW264.7 macrophages, and in the interface membrane of patients with late-onset periprosthetic joint infection (PJI). We found that titanium particles stimulated autophagy and apoptosis in macrophages. Inhibition of autophagy significantly reduced titanium particle-induced apoptosis in macrophages, which may be related to the PI3K/Akt signaling pathway. The secretion of inflammatory factors, such as IL-1β, IL-6, and TNF-α, decreased after inhibition of autophagy in titanium particle-stimulated macrophages, which may be caused by immune dysfunction due to titanium particle-induced autophagy and apoptosis in macrophages. Furthermore, our in vivo mouse calvarial model also showed that autophagy inhibitors lowered the rate of cell apoptosis. Our findings indicate that wear particle-induced apoptosis may be caused by enhanced autophagy in macrophages, which could potentially impair the local innate immunity in periprosthetic tissues and could be a risk factor for PJI. Based on these results, autophagy modulators may act as a new therapeutic option for PJI.

Implications of hydrogen sulfide in liver pathophysiology: Mechanistic insights and therapeutic potential

Background

Over the last several decades, hydrogen sulfide (H₂S) has been found to exert multiple physiological functions in mammal systems. The endogenous production of H₂S is primarily mediated by cystathione β-synthase (CBS), cystathione γ-lyase (CSE), and 3-mercaptopyruvate sulfurtransferase (3-MST). These enzymes are widely expressed in the liver tissues and regulate hepatic functions by acting on various molecular targets.

Aim of Review

In the present review, we will highlight the recent advancements in the cellular events triggered by H₂S under liver diseases. The therapeutic effects of H₂S donors on hepatic diseases will also be discussed.

Key Scientific Concepts of Review

As a critical regulator of liver functions, H₂S is critically involved in the etiology of various liver disorders, such as nonalcoholic steatohepatitis (NASH), hepatic fibrosis, hepatic ischemia/reperfusion (IR) injury, and liver cancer. Targeting H₂S-producing enzymes may be a promising strategy for managing hepatic disorders.

Prevention of renal ischemia and reperfusion injury by penehyclidine hydrochloride through autophagy activation

Penehyclidine hydrochloride (PHC) suppresses renal ischemia and reperfusion (I/R) injury (IRI); however, the underlying mechanism of action that achieves this function remains largely unknown. The present study aimed to investigate the potential role of autophagy in PHC‑induced suppression of renal IRI, as well as the involvement of cell proliferation and apoptosis. A rat IRI model and a cellular hypoxia/oxygenation (H/R) model were established; PHC, 3‑methyladenine (3‑MA) and rapamycin (Rapa) were administered to the IRI model rats prior to I/R induction and to H/R cells following reperfusion. Serum creatinine was measured using a biochemistry analyzer, whereas aspartate aminotransferase (ASAT) and alanine aminotransferase (ALAT) expression levels were detected using ELISA kits. Renal tissue injury was evaluated by histological examination. In addition, microtubule‑associated protein light chain 3B (LC3B) expression, autophagosome formation, cell proliferation and apoptosis were detected in the cellular H/R model. The results demonstrated that I/R induced renal injury in IRI model rats, upregulated serum creatinine, ALAT and ASAT expression levels, and increased autophagic processes. In contrast, pretreatment with PHC or Rapa significantly prevented these I/R‑induced changes, whereas the administration of 3‑MA enhanced I/R‑induced injuries through suppressing autophagy. PHC and Rapa increased LC3B and Beclin‑1 expression levels, but decreased sequestome 1 (p62) expression in the cellular H/R model, whereas 3‑MA prevented these PHC‑induced changes. PHC and Rapa promoted proliferation and autophagy in the cellular H/R model; these effects were accompanied by increased expression levels of LC3B and Beclin‑1, and reduced p62 expression levels, whereas these levels were inhibited by 3‑MA. Furthermore, PHC and Rapa inhibited apoptosis in the cellular H/R model through increasing Bcl‑2 expression levels, and suppressing Bax and caspase‑3 expression levels; the opposite effect was induced by 3‑MA. In conclusion, PHC suppressed renal IRI through the induction of autophagy, which in turn promoted proliferation and suppressed apoptosis in renal cells.

Protective Role of mTOR in Liver Ischemia/Reperfusion Injury: Involvement of Inflammation and Autophagy

Liver ischemia/reperfusion (IR) injury is a common phenomenon after liver resection and transplantation, which often results in liver graft dysfunction such as delayed graft function and primary nonfunction. The mammalian target of rapamycin (mTOR) is an evolutionarily highly conserved serine/threonine protein kinase, which coordinates cell growth and metabolism through sensing environmental inputs under physiological or pathological conditions, involved in the pathophysiological process of IR injury. In this review, we mainly present current evidence of the beneficial role of mTOR in modulating inflammation and autophagy under liver IR to provide some evidence for the potential therapies for liver IR injury.

Mangiferin Prevents TBHP-Induced Apoptosis and ECM Degradation in Mouse Osteoarthritic Chondrocytes via Restoring Autophagy and Ameliorates Murine Osteoarthritis

Osteoarthritis (OA) is an age-related degenerative disease with complicated pathology involving chondrocyte apoptosis and extracellular matrix (ECM) degradation. Previous studies have shown that moderate autophagy has a protective effect against apoptosis in chondrocyte. Mangiferin is a natural polyphenol and exerts multiple pharmacological effects on different diseases in various preclinical studies. In this study, we investigated the effects of mangiferin on OA and delineated a potential molecular mechanism. In vitro, mangiferin treatment inhibited the expression of proapoptotic proteins induced by tert-butyl hydroperoxide (TBHP), increased the expression of antiapoptotic Bcl-2, and prevented ECM degradation by inhibiting the production of matrix-degrading enzyme. Mechanistically, mangiferin enhanced autophagy by activating the AMP-activated protein kinase (AMPK) signaling pathway. On the contrary, inhibition of autophagy partly abolished the protective effects of mangiferin on antiapoptosis and ECM synthesis in TBHP-treated chondrocyte. Correspondingly, the protective effect of mangiferin was also found in a mouse OA model. In conclusion, our results suggested that mangiferin serves as a potentially applicable candidate for treating OA.

Alleviation of Hepatic Ischemia Reperfusion Injury by Oleanolic Acid Pretreating via Reducing HMGB1 Release and Inhibiting Apoptosis and Autophagy

Hepatic ischemia reperfusion (IR) injury (IRI) occurs during liver transplantation, hepatectomy, and hemorrhagic shock. Oleanolic acid (OA) is a natural compound with antioxidant and anti-inflammatory activity that has been used to treat liver disorders in clinical practice for several years. Here, we investigated the effects and underlying mechanisms of OA in hepatic IRI. A 60-minute partial (70%) hepatic, warm, ischemic reperfusion model was established in BALB/c mice, and two doses (30 and 60 mg/kg) of OA were administered intragastrically for 7 consecutive days prior to hepatic IR. Orbital blood and liver specimens were collected at 2, 8, and 24 h after IR. The results showed that OA preconditioning significantly alleviated hepatic injury, as evidenced by decreased alanine aminotransferase and aspartate aminotransferase levels; improved histology, inhibition of JNK phosphorylation, and high mobility group box 1 (HMGB1); and tumor necrosis factor-α downregulation in hepatic IR mice. OA upregulated Bcl-2 and downregulated caspase-3, caspase-9, Bax, Beclin 1, and LC3, which play crucial roles in the regulation of apoptosis and autophagy. These findings highlighted the protective effects of OA against hepatic IRI mediated by the inhibition of apoptosis and autophagy and the release of HMGB1, which acted as a late inflammatory mediator in hepatic IRI.

Ischaemia reperfusion injury in liver transplantation: Cellular and molecular mechanisms

Liver disease causing end organ failure is a growing cause of mortality. In most cases, the only therapy is liver transplantation. However, liver transplantation is a complex undertaking and its success is dependent on a number of factors. In particular, liver transplantation is subject to the risks of ischaemia-reperfusion injury (IRI). Liver IRI has significant effects on the function of a liver after transplantation. The cellular and molecular mechanisms governing IRI in liver transplantation are numerous. They involve multiple cells types such as liver sinusoidal endothelial cells, hepatocytes, Kupffer cells, neutrophils and platelets acting via an interconnected network of molecular pathways such as activation of toll-like receptor signalling, alterations in micro-RNA expression, production of ROS, regulation of autophagy and activation of hypoxia-inducible factors. Interestingly, the cellular and molecular events in liver IRI can be correlated with clinical risk factors for IRI in liver transplantation such as donor organ steatosis, ischaemic times, donor age, and donor and recipient coagulopathy. Thus, understanding the relationship of the clinical risk factors for liver IRI to the cellular and molecular mechanisms that govern it is critical to higher levels of success after liver transplantation. This in turn will help in the discovery of therapeutics for IRI in liver transplantation - a process that will lead to improved outcomes for patients suffering from end-stage liver disease.

GSK-3β mediates ischemia-reperfusion injury by regulating autophagy in DCD liver allografts

To elucidate the role of autophagy in ischemia-reperfusion injury (IRI) and determine whether glycogen synthase kinase-3β (GSK-3β) plays an important role in autophagy, a donors of cardiac death (DCD) liver transplantation model was established to observe the expression of GSK-3β and autophagy in hepatocytes during liver IRI. Immunohistochemical staining and western blotting were used to detect expression of the autophagy markers, LC3 and p62, as well as study the expression of GSK-3β and AMPK. Serum enzymology changes were analyzed at different times after liver transplantation. Hypoxia-reoxygenation methods were used to mimic the process of ischemia-reperfusion injury in cultured hepatocytes. In DCD liver transplantation with a prolonged reperfusion time, LC3 expression increased, whereas p62 decreased. GSK-3β and AMPK expression in the transplanted liver tissue were consistent with changes in autophagy, ALT, and AST. In summary, inactive GSK-3β reduced liver IRI, promoted hepatocyte autophagy, and improved hepatocyte activity. Therefore, GSK-3β may regulate autophagy through the AMPK-mTOR pathway.

Mechanisms by which hydrogen sulfide attenuates muscle function following ischemia-reperfusion injury: effects on Akt signaling, mitochondrial function, and apoptosis

Ischemia–reperfusion injury is caused by a period of ischemia followed by massive blood flow into a tissue that had experienced restricted blood flow. The severity of the injury is dependent on the time the tissue was restricted from blood flow, becoming more severe after longer ischemia times. This can lead to many complications such as tissue necrosis, cellular apoptosis, inflammation, metabolic and mitochondrial dysfunction, and even organ failure. One of the emerging therapies to combat ischemic reperfusion injury complications is hydrogen sulfide, which is a gasotransmitter that diffuses across cell membranes to exert effects on various signaling pathways regulating cell survival such as Akt, mitochondrial activity, and apoptosis. Although commonly thought of as a toxic gas, low concentrations of hydrogen sulfide have been shown to be beneficial in promoting tissue survival post-ischemia, and modulate a wide variety of cellular responses. This review will detail the mechanisms of hydrogen sulfide in affecting the Akt signaling pathway, mitochondrial function, and apoptosis, particularly in regards to ischemic reperfusion injury in muscle tissue. It will conclude with potential clinical applications of hydrogen sulfide, combinations with other therapies, and perspectives for future studies.

Hydrogen Sulfide as a Novel Regulatory Factor in Liver Health and Disease

Hydrogen sulfide (H₂S), a colorless gas smelling of rotten egg, has long been recognized as a toxic gas and environment pollutant. However, increasing evidence suggests that H₂S acts as a novel gasotransmitter and plays important roles in a variety of physiological and pathological processes in mammals. H₂S is involved in many hepatic functions, including the regulation of oxidative stress, glucose and lipid metabolism, vasculature, mitochondrial function, differentiation, and circadian rhythm. In addition, H₂S contributes to the pathogenesis and treatment of a number of liver diseases, such as hepatic fibrosis, liver cirrhosis, liver cancer, hepatic ischemia/reperfusion injury, nonalcoholic fatty liver disease/nonalcoholic steatohepatitis, hepatotoxicity, and acute liver failure. In this review, the biosynthesis and metabolism of H₂S in the liver are summarized and the role and mechanism of H₂S in liver health and disease are further discussed.

Autophagy and Akt in the protective effect of erythropoietin helix B surface peptide against hepatic ischaemia/reperfusion injury in mice

Helix B surface peptide (HBSP) is an erythropoietin (EPO)-derived peptide that protects tissue from the risks of elevated blood pressure and thrombosis. This study focused on the protection of HBSP in hepatic ischaemia/reperfusion (I/R) by enhancing the level of autophagy. In detail, we randomly divided C57BL/6 mice into sham-operated, hepatic ischaemia/reperfusion (I/R), I/R + HBSP, I/R + HBSP + 3-methyladenine (autophagy inhibitor), I/R + HBSP + rapamycin (mTOR inhibitor), and I/R + HBSP + Ly294002 (Akt inhibitor) groups. We assessed alanine aminotransferase (ALT), aspartate aminotransferase (AST) and lactate dehydrogenase (LDH) levels in mouse sera, and performed haematoxylin/eosin (HE) staining, immunohistochemistry, electron microscopy, immunofluorescence microscopy, and western blotting on liver tissue to detect the degree of liver injury, liver apoptosis, autophagy, and the expression of microtubule associated protein 1 light chain 3 alpha (Map1lc3, or LC3), Beclin 1, phospho-mTOR, mTOR, phospho-Akt (P-Akt), and Akt. HBSP relieved hepatic I/R injury in a concentration-independent manner. The expression of LC3II, LC3I, and Beclin 1, and the formation of autophagosomes, in the I/R + HBSP group were higher than those in the I/R group. The protective effects of HBSP were abolished by 3-methyladenine and, to a lesser extent, Ly294002, but enhanced by rapamycin. Furthermore, In vivo, HBSP also protected against hypoxia injury induced by cobalt chloride (CoCl₂) through improving the level of autophagy. Therefore, HBSP protected against hepatic I/R injury, mainly via regulating autophagy by targeting mTOR.

Hydrogen Sulfide: A Potent Tool in Postharvest Fruit Biology and Possible Mechanism of Action

Hydrogen sulfide (H2S), an endogenous gaseous molecule, is considered as a signaling agent, in parallel with other low molecular weight reactive substances, mainly hydrogen peroxide (H2O2) and nitric oxide (NO), in various plant systems. New studies are now revealing that the postharvest application of H2S, through H2S donors such as sodium hydrosulfide (NaSH) or sodium sulfide (Na2S), can inhibit fruit ripening and senescence programs in numerous fruits. We discuss here current knowledge on the impact of H2S in postharvest physiology of several climacteric and non-climacteric fruits such as banana, apple, pear, kiwifruit, strawberry, mulberry fruit, and grape. Although there is still a considerable lack of studies establishing the mechanisms by which H2S signaling is linked to fruit metabolism, we highlight several candidate mechanisms, including a putative cross-talk between H2S and ethylene, reactive oxygen and nitrogen species, oxidative/nitrosative stress signaling, sulfate metabolism, and post-translational modification of protein cysteine residues (S-sulfhydration) as being functional in this H2S postharvest action. Understanding H2S metabolism and signaling during postharvest storage and the interplay with other key player molecules would therefore provide new, improved strategies for better fruit postharvest storage. To achieve this understanding, postharvest fruit physiology research will need to focus increasingly on the spatial interaction between H2S and ethylene perception as well as on the interplay between S-sulfhydration/desulfhydration and S-nitrosylation/denitrosylation under several postharvest conditions.

Reactive Persulfides from Salmonella Typhimurium Downregulate Autophagy-Mediated Innate Immunity in Macrophages by Inhibiting Electrophilic Signaling

Reactive persulfides such as cysteine persulfide and glutathione persulfide are produced by bacteria including Salmonella during sulfur metabolism. The biological significance of bacterial reactive persulfides in host-pathogen interactions still warrants investigation. We found that reactive persulfides produced by Salmonella Typhimurium LT2 regulate macrophage autophagy via metabolizing 8-nitroguanosine 3',5'-cyclic monophosphate (8-nitro-cGMP), an electrophilic product of reactive oxygen species and nitric oxide signaling. 8-Nitro-cGMP signaling was required for efficient autophagy-mediated clearance of Salmonella from infected macrophages. In the infected cells, 8-nitro-cGMP caused cGMP adduct formation (S-guanylation) of bacterial surface proteins, which triggered recruitment of autophagy-related proteins p62 and LC3-II to the intracellular bacteria. We also found that Salmonella-produced reactive persulfides downregulated this autophagy by decreasing cellular 8-nitro-cGMP content, thereby inhibiting electrophilic signaling. These data reveal a pathogenic role of bacteria-derived reactive persulfides via suppression of anti-bacterial autophagy.

Hydrogen Sulfide Regulating Myocardial Structure and Function by Targeting Cardiomyocyte Autophagy

Objective:

Hydrogen sulfide (H₂S), a gaseous signal molecule, plays a crucial role in many pathophysiologic processes in the cardiovascular system. Autophagy has been shown to participate in the occurrence of many cardiac diseases. Increasing evidences indicated that H₂S regulates myocardial structure and function in association with the altered autophagy and plays a “switcher” role in the autophagy of myocardial diseases. The aim of this review was to summarize these insights and provide the experimental evidence that H₂S targets cardiomyocyte autophagy to regulate cardiovascular function.

Data Sources:

This review was based on data in articles published in the PubMed databases up to October 30, 2017, with the following keywords: “hydrogen sulfide,” “autophagy,” and “cardiovascular diseases.”

Study Selection:

Original articles and critical reviews on H₂S and autophagy were selected for this review.

Results:

When autophagy plays an adaptive role in the pathogenesis of diseases, H₂S restores autophagy; otherwise, when autophagy plays a detrimental role, H₂S downregulates autophagy to exert a cardioprotective function. For example, H₂S has beneficial effects by regulating autophagy in myocardial ischemia/reperfusion and plays a protective role by inhibiting autophagy during the operation of cardioplegia and cardiopulmonary bypass. H₂S postpones cardiac aging associated with the upregulation of autophagy but improves the left ventricular function of smoking rats by lowering autophagy.

Conclusions:

H₂S exerts cardiovascular protection by regulating autophagy. Cardiovascular autophagy would likely become a potential target of H₂S therapy for cardiovascular diseases.

DHA attenuates hepatic ischemia reperfusion injury by inhibiting pyroptosis and activating PI3K/Akt pathway

Hepatic ischemia reperfusion (I/R) injury is very common in liver transplantation and major liver surgeries and may cause liver failure or even death. Docosahexaenoic acid (DHA) has displayed activities in reducing oxidative stress and inflammatory reaction in many disorders. In the present study, we investigated the protective effects of DHA against I/R-induced injury and the underlying mechanisms. Here, we show that DHA protected hepatic I/R injury by reducing aspartate aminotransferase (AST) and alanine aminotransferase (ALT) levels and decreasing the oxidative stress in liver tissues. The viability of Buffalo rat liver (BRL) cells was reduced by hypoxia/restoration (H/R) but restored by DHA. DHA significantly downregulated the expression of pyroptosis-related proteins including NLR pyrin domain containing 3 (NLRP3), apoptotic speck-like protein containing CARD (ASC) and cleaved caspase-1 and reduced the secretion of pro-inflammatory cytokines. The above results were supported by terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) staining. However, incubation with LY294002, a specific inhibitor of phosphatidylinositol-3-kinase (PI3K), abolished the effects of DHA, since it increased the expression of cleaved caspase-1 and the production of inflammatory cytokines. The present results have demonstrated that DHA ameliorated I/R-induced injury by inhibiting pyroptosis of hepatocytes induced in liver I/R injury in vivo and in vitro through the PI3K/Akt pathway, providing a potential therapeutic option to prevent liver injury by I/R.

BM‑MSCs protect against liver ischemia/reperfusion injury via HO‑1 mediated autophagy

Ischemia/reperfusion (I/R) injury is considered to be a contributing factor in liver injury following major hepatic resection or liver transplantation. Bone marrow mesenchymal stem cells (BM‑MSCs) have the potential to protect against liver I/R injury; however, the precise mechanisms have not been completely elucidated. Autophagy serves an important role in protecting against various injuries, including I/R injury. The present study aimed to determine the role of autophagy and its potential regulatory mechanism in BM‑MSC‑mediated protection against liver I/R injury in rats. The results demonstrated that BM‑MSCs mitigated I/R injury and enhanced autophagy in vivo. In addition, inhibition of autophagy by 3‑methyladenine reversed the positive effects of BM‑MSCs. Furthermore, heme oxygenase‑1 (HO‑1) expression was promoted by BM‑MSCs. Using zinc protoporphyrin IX to inhibit HO‑1 demonstrated that HO‑1 was important for the promotion of autophagy. In conclusion, the present study revealed that BM‑MSCs protected against liver I/R injury via the promotion of HO‑1‑mediated autophagy.

Negative feedback loop of autophagy and endoplasmic reticulum stress in rapamycin protection against renal ischemia-reperfusion injury during initial reperfusion phase

Rapamycin, an immunosuppressant, is widely used in patients with kidney transplant. However, the therapeutic effects of rapamycin remain controversial. Additionally, previous studies have revealed deleterious effects of rapamycin predominantly when administered for ≥24 h. Few studies, however, have focused on the short-term effects of rapamycin administered only during the initial reperfusion phase. As such, we designed this study to explore the potential effects and mechanisms of rapamycin under a specific therapeutic regimen in which rapamycin is mixed in the perfusate during the initial reperfusion phase (within 24 h). Interestingly, we found that rapamycin maintained renal function and attenuated ischemia-reperfusion (I/R)-induced apoptosis in vivo and in vitro during the initial reperfusion phase, especially at 8 h after reperfusion. Simultaneously, rapamycin activated autophagy and inhibited endoplasmic reticulum (ER) stress and 3 pathways of unfolding protein response: ATF6, PERK, and IRE1α. Interestingly, we further found that the protective effects of rapamycin were suppressed when autophagy was inhibited by chloroquine and 3-methyladenine or when ER stress was induced by thapsigargin. Moreover, in terms of the regulatory effects of rapamycin, a negative-feedback loop between autophagy and ER stress occurred, with autophagy inhibiting ER stress and increased ER stress promoting autophagy during the initial reperfusion phase of renal I/R injury. Our study provides evidence that immediate reperfusion with rapamycin during the initial reperfusion phase repairs renal function and reduces apoptosis via activating autophagy, which could further inhibit ER stress. These results suggest a novel treatment modality for application during the initial reperfusion phase of renal I/R injury caused by kidney transplantation.-Li, X., Zhu, G., Gou, X., He, W., Yin, H., Yang, X., Li, J. Negative feedback loop of autophagy and endoplasmic reticulum stress in rapamycin protection against renal ischemia-reperfusion injury during initial reperfusion phase.

Role of autophagy in hepatic ischemia-reperfusion injury

Hepatic ischemia-reperfusion injury is a common complication of liver surgery and an important cause of liver dysfunction after operation. The pathogenesis of liver ischemia-reperfusion injury is very complex, involving many factors. Autophagy is a lysosomal degradation pathway on which eukaryotic cells rely to maintain the cell homeostasis. Autophagy plays an important role in the process of liver ischemia-reperfusion injury. However, the specific role and mechanism of autophagy in liver ischemia-reperfusion injury are still controversial. In this paper, we reivew the role and mechanism of autophagy in hepatic ischemia-reperfusion injury.

Rage induces hepatocellular carcinoma proliferation and sorafenib resistance by modulating autophagy

The receptor for advanced glycation end products (Rage) is involved in the development of various tumors and acts as an oncogenic protein. Rage is overexpressed in tumors including hepatocellular carcinoma (HCC). However, the molecular mechanism of Rage in HCC progression and sorafenib resistance remains unclear. In this study, enhanced Rage expression is highly associated proliferation and contributes to sorafenib resistance. Rage deficiency contributed to autophagy induction through activating AMPK/mTOR signaling pathway, which is important for sorafenib response. Moreover, the interactions between Rage and Rage ligands such as high mobility group box 1 (HMGB1) and s100a4 positively increased Rage expression. Our data indicate that Rage may be a potential target for therapeutic intervention in HCC and biomarker for sorafenib resistance.

Stat3-Atg5 signal axis inducing autophagy to alleviate hepatic ischemia-reperfusion injury

In performing our experiment, impaired autophagy increased hepatocellular damage during the reperfusion period. It was demonstrated by the effect of blocking autophagy using bafilomycin A1 or knocking Atg5 gene out reduces the anti-apoptotic effect of Stat3. Here we focus on the role of signal transducer and activator of transcription 3 (Stat3) in regulating autophagy to alleviate hepatic IRI. We found that Stat3 was up-regulated during hepatic IRI and was associated with an activation of the autophagic signaling pathway. This increased Stat3 expression, which was allied with high autophagic activity, alleviated liver damage to IR, an effect which was abrogated by Stat3 epletion as demonstrated in both in vivo and in vitro methods. The levels of Atg5 protein were decreased when Stat3 was inhibited by HO 3867 or siStat3. We conclude that Stat3 appeared to exert a pivotal role in hepatic IRI, by activating autophagy to alleviate hepatic IRI, and Atg5 was required for this process. The identification of this novel pathway, that links expression levels of Stat3 with Atg5-mediated autophagy, may provide new insights for the generation of novel protective therapies directed against hepatic IRI.

Increased autophagic degradation contributes to the neuroprotection of hydrogen sulfide against cerebral ischemia/reperfusion injury

Hydrogen sulfide (H₂S), an endogenous gaseous signal molecule, exhibits protective effect against ischemic injury. However, its underlying mechanism is not fully understood. We have recently reported that exogenous H₂S decreases the accumulation of autophagic vacuoles in mouse brain with ischemia/reperfusion (I/R) injury. To further investigate whether this H₂S-induced reduction of autophagic vacuoles is caused by the decreased autophagosome synthesis and/or the increased autophagic degradation inautophagic flux, we performed in vitro and in vivo studies using SH-SY5Y cells for the oxygen and glucose deprivation/reoxygenation (OGD/R) and mice for the cerebral I/R, respectively. NaHS (a donor of H₂S) treatment significantly increased cell viability and reduced cerebral infarct volume. NaHS treatment reduced the OGD/R-induced elevation in LC3-II (an autophagic marker), which was completely reversed by co-treatment with an autophagic flux inhibitor bafilomycin A₁ (BafA1). However, H₂S did not affect the OGD/R-induced increase of the ULK1 self-association and decrease of the ATG13 phosphorylation, which are the critical steps for the initiation of autophagosome formation. Cerebral I/R injury caused an increase in LC3-II, a decrease in p62 and the accumulation of autophagosomes in the cortex and the hippocampus, which were inhibited by NaHS treatment. This H₂S-induced decline of LC3-II in ischemic brain was reversed by BafA1. Moreover, BafA1 treatment abolished the protection of H₂S on the cerebral infarction. Collectively, the neuroprotection of exogenous H₂S against ischemia/hypoxia and reperfusion/reoxygenation injury is mediated by the enhancement of autophagic degradation.

Hydrogen Sulfide Inhibits Autophagic Neuronal Cell Death by Reducing Oxidative Stress in Spinal Cord Ischemia Reperfusion Injury

Autophagy is upregulated in spinal cord ischemia reperfusion (SCIR) injury; however, its expression mechanism is largely unknown; moreover, whether autophagy plays a neuroprotective or neurodegenerative role in SCIR injury remains controversial. To explore these issues, we created an SCIR injury rat model via aortic arch occlusion. Compared with normal controls, autophagic cell death was upregulated in neurons after SCIR injury. We found that autophagy promoted neuronal cell death during SCIR, shown by a significant number of terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling- (TUNEL-) positive cells colabeled with the autophagy marker microtubule-associated protein 1 light chain 3, while the autophagy inhibitor 3-methyladenine reduced the number of TUNEL-positive cells and restored neurological and motor function. Additionally, we showed that oxidative stress was the main trigger of autophagic neuronal cell death after SCIR injury and N-acetylcysteine inhibited autophagic cell death and restored neurological and motor function in SCIR injury. Finally, we found that hydrogen sulfide (H₂S) inhibited autophagic cell death significantly by reducing oxidative stress in SCIR injury via the AKT-the mammalian target of rapamycin (mTOR) pathway. These findings reveal that oxidative stress induces autophagic cell death and that H₂S plays a neuroprotective role by reducing oxidative stress in SCIR.

Role of Hydrogen Sulfide on Autophagy in Liver Injuries Induced by Selenium Deficiency in Chickens

Selenium (Se) is an indispensable trace mineral that was associated with liver injuries in animal models. Hydrogen sulfide (H₂S) is involved in many liver diseases, and autophagy can maintain liver homeostasis with a stress stimulation. However, little is known about the correlation between H₂S and autophagy in the liver injury chicken models induced by Se deficiency. In this study, we aimed to investigate the correlation between H₂S and autophagy in the liver injury chicken models. We randomly divided 120 1-day-old chickens into two equal groups. The control group was fed with complete food with a Se content of 0.15 mg/kg, and the Se-deficiency group (lab group) was fed with a Se-deficient diet with a Se content of 0.033 mg/kg. When the time comes to 15, 25, and 35 days, the chickens were sacrificed (20 each). The liver tissues were gathered and examined for pathological observations, the mRNA and protein levels of H₂S synthases (CSE, CBS, and 3-MST) and the mRNA and protein levels of autophagy-related genes. The results showed that the expression of CSE, CBS, and 3-MST and H₂S production were higher in the lab group than in the control group. Swellings, fractures, and vacuolizations were visible in the mitochondria cristae in the livers of the lab group and autophagosomes were found as well. In addition, the expression of autophagy-related genes (ATG5, LC3-I, LC3-II, Beclin1, and Dynein) was higher in the lab group than in the control group (p < 0.05) while TOR decreased significantly in the lab group (p < 0.05). The results showed that H₂S and autophagy were involved in the liver injury chicken models, and H₂S was correlated with autophagy.