Did the prolonged residual efficacy of clothianidin products lead to a greater reduction in vector populations and subsequent malaria transmission compared to the shorter residual efficacy of pirimiphos-methyl?

BACKGROUND: The residual activity of a clothianidin + deltamethrin mixture and clothianidin alone in IRS covered more than the period of malaria transmission in northern Benin. The aim of this study was to show whether the prolonged residual efficacy of clothianidin-based products resulted in a greater reduction in vector populations and subsequent malaria transmission compared with the shorter residual efficacy of pirimiphos-methyl. METHODS: Human bait mosquito collections by local volunteers and pyrethrum spray collections were used in 6 communes under IRS monitoring and evaluation from 2019 to 2021. ELISA/CSP and species PCR tests were performed on Anopheles gambiae sensu lato (s.l.) to determine the infectivity rate and subspecies by commune and year. The decrease in biting rate, entomological inoculation rate, incidence, inhibition of blood feeding, resting density of An. gambiae s.l. were studied and compared between insecticides per commune. RESULTS: The An. gambiae complex was the major vector throughout the study area, acounting for 98.71% (19,660/19,917) of all Anopheles mosquitoes collected. Anopheles gambiae s.l. collected was lower inside treated houses (45.19%: 4,630/10,245) than outside (54.73%: 5,607/10,245) after IRS (p < 0.001). A significant decrease (p < 0.001) in the biting rate was observed after IRS in all departments except Donga in 2021 after IRS with clothianidin 50 WG. The impact of insecticides on EIR reduction was most noticeable with pirimiphos-methyl 300 CS, followed by the clothianidin + deltamethrin mixture and finally clothianidin 50 WG. A reduction in new cases of malaria was observed in 2020, the year of mass distribution of LLINs and IRS, as well as individual and collective protection measures linked to COVID-19. Anopheles gambiae s.l. blood-feeding rates and parous were high and similar for all insecticides in treated houses. CONCLUSION: To achieve the goal of zero malaria, the optimal choice of vector control tools plays an important role. Compared with pirimiphos-methyl, clothianidin-based insecticides induced a lower reductions in entomological indicators of malaria transmission.

Ageing-Related Alterations in Renal Epithelial Glucose Transport.

The kidney plays a crucial role in glucose homeostasis by regulating glucose transport. We aimed to investigate the impact of alterations in glucose transport on glucose metabolism during ageing. Adult male Sprague Dawley rats were divided into five groups: 3-month, 6-month, and 12-month control groups, and 6- and 12-month groups receiving the hydrogen sulfide donor molecule GYY4137. The study found that, as age increased, daily urinary uric acid and protein levels increased in the 12-month group. Blood sugar level and HOMA-IR index increased in the 12-month group, and were partially improved by GYY4137. The kidney tissue showed mild glomerulosclerosis in the 12-month group, which was diminished by GYY4137. Gene expression analysis showed decreased sirtuin and increased p21 expression in the aging groups. Increased SGLT1 and SGLT2 expression was observed in the 12-month group, which was reversed by GYY4137. Both GLUT1 and GLUT2 expression was increased in the 6- and 12-month groups, and reversed by GYY4137 in the 12-month group. The study concluded that aging was associated with increased blood sugar levels and the HOMA-IR index, and the abundance of renal glucose transporters increased as aging progressed. GYY4137 effectively reversed aging-related alterations in glucose homeostasis and renal epithelial transporters.

Hydrogen sulfide attenuates ferroptosis and stimulates autophagy by blocking mTOR signaling in sepsis-induced acute lung injury.

Sepsis often leads to multiple organ failure or even death and is a significant health problem that contributes to a heavy economic burden. The lung is the first organ to be affected by sepsis. Presently, there is no specific drug or method to treat sepsis and sepsis-induced acute lung injury (ALI). H2S, along with CO and NO, is a physiological gas that acts as a signaling molecule and plays an active role in fighting various lung infections. GYY4137 is a novel H2S donor that is stable in vivo and in vitro. However, particularly in the context of ferroptosis, GYY4137 affects cecal ligation and puncture (CLP)-induced ALI by a mechanism that is not understood. Ferroptosis is a new form of cell necrosis. The primary mechanism is the accumulation of cellular lipid ROS in an iron-dependent manner. The principal objective of this project was to investigate the effects of GYY4137 on ferroptosis and autophagy in a mouse model of sepsis-induced ALI. We divided the experimental mice randomly into 5 groups: (1) sham group; (2) CLP group; (3) CLP + DMSO group: (4) CLP + GYY4137 (25 mg/kg) group; and (5) CLP + GYY4137 (50 mg/kg) group. (6) CLP + Rapamycin (2.0 mg/Kg) group. (7) CLP + Chloroquine (80 mg/Kg) group. (8) the Chloroquine (80 mg/Kg) + GYY (50 mg/Kg) group. The findings showed that GYY4137 significantly protected against CLP-induced ALI by improving sepsis-induced lung histopathological changes, diminishing lung tissue damage, ameliorating oxidative stress, and attenuating the severity of lung injury in mice. In this study, we found that GYY4137 could alleviate septicemia-induced ferroptosis in ALI by increasing the expression of GPx4 and SLC7A11 in lung tissue after CLP. One unexpected finding was the extent to which the levels of ferritin and ferritin light chain increased after CLP, which may be a compensatory mechanism for storing abnormally increased iron. We also found that the expression of p-mTOR, P62, and Beclin1 was significantly increased and that LC3II/LC3I declined after LPS stimulation, but the effect was inhibited by treatment with GYY4137, indicating that GYY4137 could inhibit the activation of autophagy in sepsis-induced ALI by blocking mTOR signaling.

H2S Donors and Their Use in Medicinal Chemistry.

Hydrogen sulfide (H2S) is a ubiquitous gaseous signaling molecule that has an important role in many physiological and pathological processes in mammalian tissues, with the same importance as two others endogenous gasotransmitters such as NO (nitric oxide) and CO (carbon monoxide). Endogenous H2S is involved in a broad gamut of processes in mammalian tissues including inflammation, vascular tone, hypertension, gastric mucosal integrity, neuromodulation, and defense mechanisms against viral infections as well as SARS-CoV-2 infection. These results suggest that the modulation of H2S levels has a potential therapeutic value. Consequently, synthetic H2S-releasing agents represent not only important research tools, but also potent therapeutic agents. This review has been designed in order to summarize the currently available H2S donors; furthermore, herein we discuss their preparation, the H2S-releasing mechanisms, and their -biological applications.

Hydrogen sulfide blocks HIV rebound by maintaining mitochondrial bioenergetics and redox homeostasis.

A fundamental challenge in human immunodeficiency virus (HIV) eradication is to understand how the virus establishes latency, maintains stable cellular reservoirs, and promotes rebound upon interruption of antiretroviral therapy (ART). Here, we discovered an unexpected role of the ubiquitous gasotransmitter hydrogen sulfide (H2S) in HIV latency and reactivation. We show that reactivation of HIV is associated with downregulation of the key H2S producing enzyme cystathionine-γ-lyase (CTH) and reduction in endogenous H2S. Genetic silencing of CTH disrupts redox homeostasis, impairs mitochondrial function, and remodels the transcriptome of latent cells to trigger HIV reactivation. Chemical complementation of CTH activity using a slow-releasing H2S donor, GYY4137, suppressed HIV reactivation and diminished virus replication. Mechanistically, GYY4137 blocked HIV reactivation by inducing the Keap1-Nrf2 pathway, inhibiting NF-κB, and recruiting the epigenetic silencer, YY1, to the HIV promoter. In latently infected CD4+ T cells from ART-suppressed human subjects, GYY4137 in combination with ART prevented viral rebound and improved mitochondrial bioenergetics. Moreover, prolonged exposure to GYY4137 exhibited no adverse influence on proviral content or CD4+ T cell subsets, indicating that diminished viral rebound is due to a loss of transcription rather than a selective loss of infected cells. In summary, this work provides mechanistic insight into H2S-mediated suppression of viral rebound and suggests exploration of H2S donors to maintain HIV in a latent form.

Hydrogen sulfide suppresses the proliferation of intestinal epithelial cells through cell cycle arrest.

The pathogenesis of chronic kidney disease (CKD) is closely related to the changes in the intestinal microbiota and integrity. Our previous studies have shown the accumulation of hydrogen sulfide (H2S)-producing bacterial family, Desulfovibrionacea, in the colon of a murine model of CKD, suggesting that the increased H2S contributes to the impaired intestinal integrity in CKD. Here, we investigated the anti-proliferative effect of H2S in the intestinal epithelial cells. A slow- H2S releasing molecule GYY4137 ((p-methoxyphenyl)morpholino-phosphinodithioic acid) reduced the proliferation of Caco-2 and IEC-6 cells. Flow cytometric analysis demonstrated that GYY4137 accumulated Caco-2 cells in the S phase fraction, suggesting that H2S arrested the cell cycle at G2 and/or M phases. The RNA sequencing analysis demonstrated that GYY4137 modulated the mRNA expression of the genes involved in the G2/M and the spindle assembly checkpoints; increased mRNA levels of Cdkn1a, Gadd45a, and Sfn and decreased mRNA levels of Cdc20, Pttg1, and Ccnb1 were observed. These alterations were confirmed by quantitative reverse transcription-polymerase chain reaction and Western blot analyses. Besides, studies exploring the MEK inhibitor indicated that MEK activation is involved in the GYY4137-mediated increase in the Sfn expression. Altogether, our data showed that H2S reduced the proliferation of intestinal epithelial cells through transcriptional regulation in G2/M and the spindle assembly checkpoints. This may be one of the underlying mechanisms for the observed impaired intestinal integrity in CKD.

GYY4137 Regulates Extracellular Matrix Turnover in the Diabetic Kidney by Modulating Retinoid X Receptor Signaling.

Diabetic kidney is associated with an accumulation of extracellular matrix (ECM) leading to renal fibrosis. Dysregulation of retinoic acid metabolism involving retinoic acid receptors (RARs) and retinoid X receptors (RXRs) has been shown to play a crucial role in diabetic nephropathy (DN). Furthermore, RARs and peroxisome proliferator-activated receptor γ (PPARγ) are known to control the RXR-mediated transcriptional regulation of several target genes involved in DN. Recently, RAR and RXR have been shown to upregulate plasminogen activator inhibitor-1 (PAI-1), a major player involved in ECM accumulation and renal fibrosis during DN. Interestingly, hydrogen sulfide (H2S) has been shown to ameliorate adverse renal remodeling in DN. We investigated the role of RXR signaling in the ECM turnover in diabetic kidney, and whether H2S can mitigate ECM accumulation by modulating PPAR/RAR-mediated RXR signaling. We used wild-type (C57BL/6J), diabetic (C57BL/6-Ins2Akita/J) mice and mouse mesangial cells (MCs) as experimental models. GYY4137 was used as a H2S donor. Results showed that in diabetic kidney, the expression of PPARγ was decreased, whereas upregulations of RXRα, RXRß, and RARγ1 expression were observed. The changes were associated with elevated PAI-1, MMP-9 and MMP-13. In addition, the expressions of collagen IV, fibronectin and laminin were increased, whereas elastin expression was decreased in the diabetic kidney. Excessive collagen deposition was observed predominantly in the peri-glomerular and glomerular regions of the diabetic kidney. Immunohistochemical localization revealed elevated expression of fibronectin and laminin in the glomeruli of the diabetic kidney. GYY4137 reversed the pathological changes. Similar results were observed in in vitro experiments. In conclusion, our data suggest that RXR signaling plays a significant role in ECM turnover, and GYY4137 modulates PPAR/RAR-mediated RXR signaling to ameliorate PAI-1-dependent adverse ECM turnover in DN.

A role of peptidoglycan recognition protein in mediating insecticide detoxification in Glyphodes pyloalis.

Glyphodes pyloalis Walker has become one of the most significant mulberry pests, and it has caused serious economic losses in major mulberry growing regions in China. Peptidoglycan recognition proteins (PGRPs) are responsible for initiating and regulating immune signalling pathways in insects. However, their roles responding to chemical pesticides is still less known. This study aimed to investigate the possible detoxication function of GpPGRP-S2 and GpPGRP-S3 in G. pyloalis in response to chlorfenapyr and phoxim. The chlorfenapyr and phoxim treatment significantly induced the expression level of GpPGRP-S3 at 48 h. In addition, the expression levels of GpPGRP-S2 and GpPGRP-S3 in the chlorfenapyr/phoxim treatment group were significantly higher in midgut than those in the control group at 48 h. The results of the survival experiment showed that silencing either GpPGRP-S2 or GpPGRP-S3 would not influence the survival rate of G. pyloalis which treated with phoxim, however, silencing GpPGRP-S2 or GpPGRP-S3 would cause G. pyloalis to be more easily killed by chlorfenapyr. The expression of carboxylesterase GpCXE1 was significantly induced by chlorfenapyr/phoxim treatment, while it was suppressed once silenced GpPGRP-S2 followed with chlorfenapyr treatment or silenced GpPGRP-S3 followed with phoxim treatment. These results might suggest that under the chlorfenapyr/phoxim treatment condition, the connection between GpPGRPs and detoxification genes in insect was induced to maintain physiological homeostasis; and these results may further enrich the mechanisms of insects challenged by insecticides.

AMPK S-sulfuration contributes to H2S donors-induced AMPK phosphorylation and autophagy activation in dopaminergic cells.

Hydrogen sulfide (H2S) serves as a neuromodulator and regulator of neuroinflammation. It is reported to be therapeutic for Parkinson's disease (PD) animal and cellular models. However, whether it affects α-synuclein accumulation in dopaminergic cells, the key pathological feature in PD, is poorly understood. In this study we reported that exogenous H2S donors NaHS and GYY4137 (GYY) enhanced the autophagy activity, as indicated by the increases of autophagy marker LC3-II expression and LC3 dots formation even during lysosome inhibition in dopaminergic cell lines and HEK293 cells. The enhancement of H2S donors on autophagic flux was mediated by adenosine 5'-monophosphate-activated protein kinase (AMPK)-dependent mammalian target of rapamycin (mTOR) inhibition, as H2S donors activated AMPK but reduced the mTOR activity and H2S donors-induced LC3-II increase was diminished by mTOR activator. Moreover, point mutation of Cys302 into alanine (C302A) in AMPKα2 subunit abolished the AMPK activation and mTOR inhibition, as well as autophagic flux increase elicited by NaHS. Interestingly, NaHS triggered AMPK S-sulfuration, which was not observed in AMPK C302A-transfected cells. Further, NaHS was able to attenuate α-synuclein accumulation in a cellular model induced by dopamine oxidized metabolite 3, 4-dihydroxyphenylacetaldehyde (DOPAL), and this effect was interfered by autophagy inhibitor wortmannin and also eliminated in AMPK Cys302A-transfected cells. In sum, the findings identified a role of Cys302 S-sulfuration in AMPK activation induced by exogenous H2S and demonstrated that H2S donors could enhance the autophagic flux via AMPK-mTOR signaling and thus reduce α-synuclein accumulation in vitro.

Mechanism of preservation of the intestinal mucosa architecture and NF-κB/PGE2 reduction by hydrogen sulfide on cholera toxin-induced diarrhea in mice.

AIMS: Investigate the involvement of Hydrogen sulfide (H2S) in inflammatory parameters and intestinal morphology caused by cholera toxin (CT) in mice. MAIN METHODS: Mice were subjected to the procedure of inducing diarrhea by CT in the isolated intestinal loop model. The intestinal loops were inoculated with H2S donor molecules (NaHS and GYY 4137) or saline and CT. To study the role of EP2 and EP4 prostaglandin E2 (PGE2) receptors in the H2S antisecretory effect, PAG (DL-propargylglycine - inhibitor of cystathionine-γ-lyase (CSE)), PF-04418948 (EP2 antagonist) and ONO-AE3-208 (EP4 antagonist) were used. The intestinal loops were evaluated for intestinal secretion, relation of the depth of villi and intestinal crypts, and real-time PCR for the mRNA of the CXCL2, IL-6, NOS-2, IL-17, NF-κB1, NF-κBIA, SLC6A4 and IFN-γ genes. KEY FINDINGS: H2S restored the villus/crypt depth ratio caused by CT. NaHS and GYY 4137 increased the expression of NF-κB1 and for the NF-κBIA gene, only GYY 4137 increased the expression of this gene. The increased expression of NF-κB inhibitors, NF-κB1 and NF-κBIA by H2S indicates a possible decrease in NF-κB activity. The pretreatment with PAG reversed the protective effect of PF-04418948 and ONO-AE3-208, indicating that H2S probably decreases PGE2 because in the presence of antagonists of this pathway, PAG promotes intestinal secretion. SIGNIFICANCE: Our results point to a protective activity of H2S against CT for promoting a protection of villus and crypt intestine morphology and also that its mechanism occurs at least in part due to decreasing the activity of NF-κB and PGE2.

Quantum Calculations of VX Ammonolysis and Hydrolysis Pathways via Hydrated Lithium Nitride.

Recently, lithium nitride (Li3N) has been proposed as a chemical warfare agent (CWA) neutralization reagent for its ability to produce nucleophilic ammonia molecules and hydroxide ions in aqueous solution. Quantum chemical calculations can provide insight into the Li3N neutralization process that has been studied experimentally. Here, we calculate reaction-free energies associated with the Li3N-based neutralization of the CWA VX using quantum chemical density functional theory and ab initio methods. We find that alkaline hydrolysis is more favorable to either ammonolysis or neutral hydrolysis for initial P-S and P-O bond cleavages. Reaction-free energies of subsequent reactions are calculated to determine the full reaction pathway. Notably, products predicted from favorable reactions have been identified in previous experiments.

GYY4137 attenuates functional impairment of corpus cavernosum and reduces fibrosis in rats with STZ-induced diabetes by inhibiting the TGF-ß1/Smad/CTGF pathway.

Erectile dysfunction (ED) is a common diabetic complication. Recent evidence has illuminated the role of hydrogen sulfide (H2S) as a dynamic mediator of the erection process. H2S is a potent endogenous relaxant gas. It has been shown to relax human and animal penile tissue in vitro and induce erection in animals in vivo. The reported penile expression of H2S-synthesizing enzymes also supports the potential role of the endogenous L-cysteine/H2S pathway in penile homeostasis. Several pathological changes take place in the diabetic penile tissue, including inflammation, oxidative stress, neuropathy and fibrosis of the corpus cavernosum (CC), the major erectile structure of the penis. The present study is experimental and has been performed in the diabetic rat model. The study will investigate the role of H2S as a potential protective mediator against diabetes-induced structural and functional alterations in the CC by examining if it: (1) reduces corporal contraction and/or enhances corporal relaxation following pharmacological stimulation, (2) attenuates fibromuscular changes in diabetic CC, and (3) whether there is a link with H2S plasma/urine level and CC tissue generation, as well as studying the expression of some proteins in the transforming growth factor (TGF)-ß1-associated pathway. The major findings of the study reveal that- compared to the nondiabetic controls - the diabetic animals CC showed: (1) augmented contraction and attenuated relaxation in response to phenylephrine and carbachol, respectively, (2) marked fibromuscular degeneration with a significantly lower smooth muscle/collagen ratio and upregulation of TGF-ß-1/Smad/CTGF fibrosis signaling pathway, (3) reduced H2S plasma and urinary levels and cavernosal tissue generation. Chronic GYY4137 treatment prevented most of these pathological changes in diabetic CC, thus may be considered a potential new strategy for the prevention and/or treatment of diabetes-induced ED.

GYY4137 protected the integrity of the blood-brain barrier via activation of the Nrf2/ARE pathway in mice with sepsis.

Injury to the blood-brain barrier (BBB) plays a vital role in sepsis-associated encephalopathy (SAE), which is one of the most common complications of sepsis. GYY4137, a new synthetic compound of hydrogen sulfide (H2 S), has extensive biological benefits. In this study, we focused on the protective effects of GYY4137 on the BBB in septic mice and the underlying mechanisms. The results suggested that whether administrated at the same time or 3 hours after LPS injection, GYY4137 both significantly alleviated the clinical symptoms and the long-term prognosis. Besides, GYY4137 improved the pathological abnormalities of septic mice. Moreover, the degradation of tight junctions in the BBB was considerably inhibited by GYY4137. In addition, GYY4137 significantly attenuated inflammation and apoptosis in the brain. Furthermore, GYY4137 activated the Nrf2/ARE pathway through the sulfhydrylation of Keap1 and inhibited oxidative stress. ML385, the specific inhibitor of Nrf2, significantly reversed the protective effects of GYY4137 in sepsis mice. In conclusion, this study indicated that through the sulfhydrylation of Keap1, GYY4137 activated the Nrf2/ARE pathway and exerted anti-inflammatory, anti-apoptotic and antioxidant effects in septic mice that consequently protected the integrity of the BBB and improved the clinical outcome of sepsis. Our findings suggest that GYY4137 might be a promising agent for the treatment of SAE.

Mesorhizobium ciceri as biological tool for improving physiological, biochemical and antioxidant state of Cicer aritienum (L.) under fungicide stress.

Fungicides among agrochemicals are consistently used in high throughput agricultural practices to protect plants from damaging impact of phytopathogens and hence to optimize crop production. However, the negative impact of fungicides on composition and functions of soil microbiota, plants and via food chain, on human health is a matter of grave concern. Considering such agrochemical threats, the present study was undertaken to know that how fungicide-tolerant symbiotic bacterium, Mesorhizobium ciceri affects the Cicer arietinum crop while growing in kitazin (KITZ) stressed soils under greenhouse conditions. Both in vitro and soil systems, KITZ imparted deleterious impacts on C. arietinum as a function of dose. The three-time more of normal rate of KITZ dose detrimentally but maximally reduced the germination efficiency, vigor index, dry matter production, symbiotic features, leaf pigments and seed attributes of C. arietinum. KITZ-induced morphological alterations in root tips, oxidative damage and cell death in root cells of C. arietinum were visible under scanning electron microscope (SEM). M. ciceri tolerated up to 2400 µg mL-1 of KITZ, synthesized considerable amounts of bioactive molecules including indole-3-acetic-acid (IAA), 1-aminocyclopropane 1-carboxylate (ACC) deaminase, siderophores, exopolysaccharides (EPS), hydrogen cyanide, ammonia, and solubilised inorganic phosphate even in fungicide-stressed media. Following application to soil, M. ciceri improved performance of C. arietinum and enhanced dry biomass production, yield, symbiosis and leaf pigments even in a fungicide-polluted environment. At 96 µg KITZ kg-1 soil, M. ciceri maximally and significantly (p ≤ 0.05) augmented the length of plants by 41%, total dry matter by 18%, carotenoid content by 9%, LHb content by 21%, root N by 9%, shoot P by 11% and pod yield by 15% over control plants. Additionally, the nodule bacterium M. ciceri efficiently colonized the plant rhizosphere/rhizoplane and considerably decreased the levels of stressor molecules (proline and malondialdehyde) and antioxidant defence enzymes viz. ascorbate peroxidise (APX), guaiacol peroxidise (GPX), catalase (CAT) and peroxidises (POD) of C. arietinum plants when inoculated in soil. The symbiotic strain effectively colonized the plant rhizosphere/rhizoplane. Conclusively, the ability to endure higher fungicide concentrations, capacity to secrete plant growth modulators even under fungicide pressure, and inherent features to lower the level of proline and plant defence enzymes makes this M. ciceri as a superb choice for augmenting the safe production of C. arietinum even under fungicide-contaminated soils.

Hydrogen sulfide regulates hippocampal neuron excitability via S-sulfhydration of Kv2.1.

Hydrogen sulfide (H2S) is gaining interest as a mammalian signalling molecule with wide ranging effects. S-sulfhydration is one mechanism that is emerging as a key post translational modification through which H2S acts. Ion channels and neuronal receptors are key target proteins for S-sulfhydration and this can influence a range of neuronal functions. Voltage-gated K+ channels, including Kv2.1, are fundamental components of neuronal excitability. Here, we show that both recombinant and native rat Kv2.1 channels are inhibited by the H2S donors, NaHS and GYY4137. Biochemical investigations revealed that NaHS treatment leads to S-sulfhydration of the full length wild type Kv2.1 protein which was absent (as was functional regulation by H2S) in the C73A mutant form of the channel. Functional experiments utilising primary rat hippocampal neurons indicated that NaHS augments action potential firing and thereby increases neuronal excitability. These studies highlight an important role for H2S in shaping cellular excitability through S-sulfhydration of Kv2.1 at C73 within the central nervous system.

Hydrogen sulfide inhibits calcium and phosphorus loss after fracture by negatively regulating glucocorticoid/glucocorticoid receptor α.

AIMS: Post-fracture calcium and phosphorus excretion is greater than influx, which might be caused by stress. Glucocorticoid is known to enhance calcium and phosphorous excretion, and hydrogen sulfide (H2S) has been shown to exert inhibitory effects on glucocorticoid. Therefore, this study explored whether H2S could inhibit calcium and phosphorus loss after fracture by regulating glucocorticoid and/or its receptor. MAIN METHODS: The following properties were analyzed in rats with femur fractures: serum and urinary calcium and phosphorus (by colorimetry); bone turnover markers alkaline phosphatase, serum type 1 collagen amino terminal peptide, type 1 procollagen carboxy terminal peptide, and anti-tartaric acid phosphatase (by ELISA); factors related to calcium-phosphorus metabolism including glucocorticoid, parathyroid hormone, calcitonin, fibroblast growth factor 23, and 1,25(OH)2D3 (by ELISA); and sulfhydration of glucocorticoid receptor α in the kidney (by immunoprecipitation linked biotin-switch assay), after supplementing with mifepristone, the H2S donor GYY4137 or H2S generating enzyme inhibitors aminooxyacetic acid and propargylglycine. KEY FINDINGS: Serum H2S decreased and glucocorticoid secretion increased in rats post-fracture. The glucocorticoid receptor inhibitor mifepristone partly blunted calcium and phosphorus loss. Furthermore, supplementation with GYY4137 reduced glucocorticoid secretion; inhibited glucocorticoid receptor α activity by sulfhydration; downregulated vitamin D 1α-hydroxylase expression; and upregulated 24-hydroxylase, calbindin-D28k, and sodium phosphate cotransporter 2a expression in the kidney; thereby inhibiting calcium and phosphorus loss induced by fracture. Moreover, inhibiting endogenous H2S generation showed opposite effects. SIGNIFICANCE: Our findings suggest that H2S antagonized calcium and phosphorus loss after fracture by reducing glucocorticoid secretion and inhibiting glucocorticoid receptor α activity by sulfhydration.

Mitochondrial hydrogen sulfide supplementation improves health in the C. elegans Duchenne muscular dystrophy model.

Duchenne muscular dystrophy (DMD) is an X-linked recessive disorder characterized by progressive muscle degeneration and weakness due to mutations in the dystrophin gene. The symptoms of DMD share similarities with those of accelerated aging. Recently, hydrogen sulfide (H2S) supplementation has been suggested to modulate the effects of age-related decline in muscle function, and metabolic H2S deficiencies have been implicated in affecting muscle mass in conditions such as phenylketonuria. We therefore evaluated the use of sodium GYY4137 (NaGYY), a H2S-releasing molecule, as a possible approach for DMD treatment. Using the dys-1(eg33) Caenorhabditis elegans DMD model, we found that NaGYY treatment (100 µM) improved movement, strength, gait, and muscle mitochondrial structure, similar to the gold-standard therapeutic treatment, prednisone (370 µM). The health improvements of either treatment required the action of the kinase JNK-1, the transcription factor SKN-1, and the NAD-dependent deacetylase SIR-2.1. The transcription factor DAF-16 was required for the health benefits of NaGYY treatment, but not prednisone treatment. AP39 (100 pM), a mitochondria-targeted H2S compound, also improved movement and strength in the dys-1(eg33) model, further implying that these improvements are mitochondria-based. Additionally, we found a decline in total sulfide and H2S-producing enzymes in dystrophin/utrophin knockout mice. Overall, our results suggest that H2S deficit may contribute to DMD pathology, and rectifying/overcoming the deficit with H2S delivery compounds has potential as a therapeutic approach to DMD treatment.

GYY4137 alleviates sepsis-induced acute lung injury in mice by inhibiting the PDGFRß/Akt/NF-κB/NLRP3 pathway.

AIMS: GYY4137 [GYY, morpholin-4-ium-4-methoxyphenyl (morpholino) phosphinodithioate] is a novel and perfect hydrogen sulfide (H2S) donor that is stable in vivo and in vitro. H2S, along with CO and NO, has been recognized as the third physiological gas signaling molecule that plays an active role in fighting various lung infections. However, the mechanism by which GYY4137 affects cecal ligation and puncture (CLP)-induced acute lung injury (ALI) is not understood. This study aimed to investigate whether GYY4137 inhibits the activation of the pyrin domain-containing protein 3 (NLRP3) inflammasome by inhibiting the PDGFRß/Akt/NF-κB pathway. MAIN METHODS: The model of CLP-induced ALI was established in vivo. The mice were subsequently treated with GYY4137 (25 µg/g and 50 µg/g) to simulate the realistic conditions of pathogenesis. Western blotting and immunohistochemical staining were used to examine protein expression, hematoxylin and eosin staining was used for the histopathological analysis, and the levels of inflammatory factors were determined using enzyme-linked immunosorbent assays (ELISAs). KEY FINDINGS: GYY4137 significantly increased the 7-day survival of mice with septic peritonitis and protected against CLP-induced ALI, including decreasing neutrophil infiltration, improving sepsis-induced lung histopathological changes, diminishing lung tissue damage, and attenuating the severity of lung injury in mice. The protective effect of GYY4137 was undoubtedly dose-dependent. We discovered that GYY4137 reduced the levels of the p-PDGFRß, p-NF-κB, ASC, NLRP3, caspase-1, and p-Akt proteins in septic mouse lung tissue. Akt regulates the generation of proinflammatory cytokines in endotoxemia-associated ALI by enhancing the nuclear translocation of NF-κB. SIGNIFICANCE: These results indicate a new molecular mechanism explaining the effect of GYY4137 on the treatment of CLP-induced ALI in mice.

Hydrogen sulfide inhibits endoplasmic reticulum stress through the GRP78/mTOR pathway in rat chondrocytes subjected to oxidative stress.

The activation of oxidative stress is a primary cause of chondrocyte apoptosis in osteoarthritis (OA). The 78­kDa glucose­regulated protein (GRP78)/mammalian target of rapamycin (mTOR) signaling pathway has been demonstrated to be linked with the endoplasmic reticulum (ER) and autophagy. Hydrogen sulfide (H2S) has been reported to exert antioxidant effects. The present study investigated oxidative stress levels via 2',7'­dichlorofluorescin diacetate and MitoSOX staining, apoptosis rates via flow cytometry and the expression levels of ER stress­related proteins in GYY4137 (donor of H2S)­treated chondrocytes (CHs). CHs were isolated from the bilateral hip joints of male rats to examine mitochondrial permeability transition pore opening­ and mTOR signaling pathway­related proteins. The results demonstrated that tert­Butyl hydroperoxide (TBHP) increased CH apoptosis, and treatment with GYY4137 ameliorated TBHP­mediated the generation of ROS and CH apoptosis. Moreover, TBHP­treated CHs displayed elevated ER stress sensor expression levels and apoptotic rates; however, the TBHP­induced protein expression levels were decreased following GYY4137 treatment. In the present study, treatment with either GYY4137 or transfection with GRP78 siRNA both suppressed the activation of p­P70S6k and p­mTOR. H2S played an important role in regulating ER stress in TBHP­stimulated CHs. GYY4137 promoted autophagy, which was accompanied by the inhibition of ER stress. On the whole, the present study demonstrates that TBHP­induced oxidative stress stimulates ER interactions and CH apoptosis, which are suppressed by exogenous H2S via modulating the GRP78/mTOR signaling pathway.

Hydrogen sulfide is neuroprotective in Alzheimer's disease by sulfhydrating GSK3ß and inhibiting Tau hyperphosphorylation.

Alzheimer's disease (AD), the most common cause of dementia and neurodegeneration in the elderly, is characterized by deterioration of memory and executive and motor functions. Neuropathologic hallmarks of AD include neurofibrillary tangles (NFTs), paired helical filaments, and amyloid plaques. Mutations in the microtubule-associated protein Tau, a major component of the NFTs, cause its hyperphosphorylation in AD. We have shown that signaling by the gaseous molecule hydrogen sulfide (H2S) is dysregulated during aging. H2S signals via a posttranslational modification termed sulfhydration/persulfidation, which participates in diverse cellular processes. Here we show that cystathionine γ-lyase (CSE), the biosynthetic enzyme for H2S, binds wild type Tau, which enhances its catalytic activity. By contrast, CSE fails to bind Tau P301L, a mutant that is present in the 3xTg-AD mouse model of AD. We further show that CSE is depleted in 3xTg-AD mice as well as in human AD brains, and that H2S prevents hyperphosphorylation of Tau by sulfhydrating its kinase, glycogen synthase kinase 3ß (GSK3ß). Finally, we demonstrate that sulfhydration is diminished in AD, while administering the H2S donor sodium GYY4137 (NaGYY) to 3xTg-AD mice ameliorates motor and cognitive deficits in AD.