GGT5: a potential immunotherapy response inhibitor in gastric cancer by modulating GSH metabolism and sustaining memory CD8+ T cell infiltration.

PURPOSE: The variable responses to immunotherapy observed in gastric cancer (GC) patients can be attributed to the intricate nature of the tumor microenvironment. Glutathione (GSH) metabolism significantly influences the initiation and progression of gastric cancer. Consequently, targeting GSH metabolism holds promise for improving the effectiveness of Immune checkpoints inhibitors (ICIs). METHODS: We investigated 16 genes related to GSH metabolism, sourced from the MSigDB database, using pan-cancer datasets from TCGA. The most representative prognosis-related gene was identified for further analysis. ScRNA-sequencing analysis was used to explore the tumor heterogeneity of GC, and the results were confirmed by  Multiplex immunohistochemistry (mIHC). RESULTS: Through DEGs, LASSO, univariate and multivariate Cox regression analyses, and survival analysis, we identified GGT5 as the hub gene in GSH metabolism with the potential to promote GC. Combining CIBERSORT, ssGSEA, and scRNA analysis, we constructed the immune architecture of GC. The subpopulations of T cells were isolated, revealing a strong association between GGT5 and memory CD8+ T cells. Furthermore, specimens from 10 GC patients receiving immunotherapy were collected. mIHC was used to assess the expression levels of GGT5 and memory CD8+ T cell markers. Our results established a positive correlation between GGT5 expression, the enrichment of memory CD8+ T cells, and a suboptimal response to immunotherapy. CONCLUSIONS: Our study identifies GGT5, a hub gene in GSH metabolism, as a potential therapeutic target for inhibiting the response to immunotherapy in GC patients. These findings offer new insights into strategies for optimizing immunotherapy of GC.

Requirements for the biogenesis of [2Fe-2S] proteins in the human and yeast cytosol.

The biogenesis of iron-sulfur (Fe/S) proteins entails the synthesis and trafficking of Fe/S clusters, followed by their insertion into target apoproteins. In eukaryotes, the multiple steps of biogenesis are accomplished by complex protein machineries in both mitochondria and cytosol. The underlying biochemical pathways have been elucidated over the past decades, yet the mechanisms of cytosolic [2Fe-2S] protein assembly have remained ill-defined. Similarly, the precise site of glutathione (GSH) requirement in cytosolic and nuclear Fe/S protein biogenesis is unclear, as is the molecular role of the GSH-dependent cytosolic monothiol glutaredoxins (cGrxs). Here, we investigated these questions in human and yeast cells by various in vivo approaches. [2Fe-2S] cluster assembly of cytosolic target apoproteins required the mitochondrial ISC machinery, the mitochondrial transporter Atm1/ABCB7 and GSH, yet occurred independently of both the CIA system and cGrxs. This mechanism was strikingly different from the ISC-, Atm1/ABCB7-, GSH-, and CIA-dependent assembly of cytosolic-nuclear [4Fe-4S] proteins. One notable exception to this cytosolic [2Fe-2S] protein maturation pathway defined here was yeast Apd1 which used the CIA system via binding to the CIA targeting complex through its C-terminal tryptophan. cGrxs, although attributed as [2Fe-2S] cluster chaperones or trafficking proteins, were not essential in vivo for delivering [2Fe-2S] clusters to either CIA components or target apoproteins. Finally, the most critical GSH requirement was assigned to Atm1-dependent export, i.e. a step before GSH-dependent cGrxs function. Our findings extend the general model of eukaryotic Fe/S protein biogenesis by adding the molecular requirements for cytosolic [2Fe-2S] protein maturation.

Lipid-derived electrophiles inhibit the function of membrane channels during ferroptosis.

The therapeutic targeting of ferroptosis requires full understanding of the molecular mechanism of this regulated cell death pathway. While lipid-derived electrophiles (LDEs), including 4-hydroxy-2-nonenal (4-HNE), are important biomarkers of ferroptosis, a functional role for these highly reactive species in ferroptotic cell death execution has not been established. Here, through mechanistic characterization of LDE-detoxification impairment, we demonstrate that LDEs mediate altered protein function during ferroptosis. Applying live cell fluorescence imaging, we first identified that export of glutathione-LDE-adducts through multidrug resistance-associated protein (MRP) channels is inhibited following exposure to a panel of ferroptosis inducers (FINs) with different modes of action (type I-IV FINs erastin, RSL3, FIN56, and FINO2). This channel inhibition was recreated by both initiation of lipid peroxidation and treatment with 4-HNE. Importantly, treatment with radical-trapping antioxidants prevented impaired LDE-adduct export when working with both FINs and lipid peroxidation initiators but not 4-HNE, pinpointing LDEs as the cause of this inhibited MRP activity observed during ferroptosis. Our findings, when combined with reports of widespread LDE alkylation of key proteins following ferroptosis induction, including MRP1, set a precedent for LDEs as critical mediators of ferroptotic cell damage. Lipid hydroperoxide breakdown to form truncated phospholipids and LDEs may fully explain membrane permeabilization and modified protein function downstream of lipid peroxidation, offering a unified explanation of the molecular cell death mechanism of ferroptosis.

Metabolic Activation and Cytotoxicity of Gramine Mediated by CYP3A in Rats.

Gramine (GRM), which occurs in Gramineae plants, has been developed to be a biological insecticide. Exposure to GRM was reported to induce elevations of serum ALT and AST in rats, but the mechanisms of the observed hepatotoxicity have not been elucidated. The present study aimed to identify reactive metabolites that potentially participate in the toxicity. In rat liver microsomal incubations fortified with glutathione or N-acetylcysteine, one oxidative metabolite (M1), one glutathione conjugate (M2), and one N-acetylcysteine conjugate (M3) were detected after exposure to GRM. The corresponding conjugates were detected in the bile and urine of rats after GRM administration. CYP3A was the main enzyme mediating the metabolic activation of GRM. The detected GSH and NAC conjugates suggest that GRM was metabolized to a quinone imine intermediate. Both GRM and M1 showed significant toxicity to rat primary hepatocytes.

Intake of oligoelements with cytarabine or etoposide alters dopamine levels and oxidative damage in rat brain.

Research on the relationships between oligoelements (OE) and the development of cancer or its prevention is a field that is gaining increasing relevance. The aim was to evaluate OE and their interactions with oncology treatments (cytarabine or etoposide) to determine the effects of this combination on biogenic amines and oxidative stress biomarkers in the brain regions of young Wistar rats. Dopamine (DA), 5-Hydroxyindoleacetic acid (5-Hiaa), Glutathione (Gsh), Tiobarbituric acid reactive substances (TBARS) and Ca+2, Mg+2 ATPase enzyme activity were measured in brain regions tissues using spectrophometric and fluorometric methods previously validated. The combination of oligoelements and cytarabine increased dopamine in the striatum but decreased it in cerebellum/medulla-oblongata, whereas the combination of oligoelements and etoposide reduced lipid peroxidation. These results suggest that supplementation with oligoelements modifies the effects of cytarabine and etoposide by redox pathways, and may become promising therapeutic targets in patients with cancer.

A dual model of normal vs isogenic Nrf2-depleted murine epithelial cells to explore oxidative stress involvement.

Cancer-derived cell lines are useful tools for studying cellular metabolism and xenobiotic toxicity, but they are not suitable for modeling the biological effects of food contaminants or natural biomolecules on healthy colonic epithelial cells in a normal genetic context. The toxicological properties of such compounds may rely on their oxidative properties. Therefore, it appears to be necessary to develop a dual-cell model in a normal genetic context that allows to define the importance of oxidative stress in the observed toxicity. Given that the transcription factor nuclear factor erythroid 2-related factor 2 (Nrf2) is considered to be the master regulator of antioxidant defenses, our aim was to develop a cellular model comparing normal and Nrf2-depleted isogenic cells to qualify oxidative stress-related toxicity. We generated these cells by using the CRISPR/Cas9 technique. Whole-genome sequencing enabled us to confirm that our cell lines were free of cancer-related mutations. We used 4-hydroxy-2-nonenal (HNE), a lipid peroxidation product closely related to oxidative stress, as a model molecule. Here we report significant differences between the two cell lines in glutathione levels, gene regulation, and cell viability after HNE treatment. The results support the ability of our dual-cell model to study the role of oxidative stress in xenobiotic toxicity.

A new method based on melatonin-mediated seed germination to quickly remove pesticide residues and improve the nutritional quality of contaminated grains.

In the present study, we attempted to use melatonin combined with germination treatment to remove pesticide residues from contaminated grains. High levels of pesticide residues were detected in soybean seeds after soaking with chlorothalonil (10 mM) and malathion (1 mM) for 2 hours. Treatment with 50 µM melatonin for 5 days completely removed the pesticide residues, while in the control group, only 61-71% of pesticide residues were removed from soybean sprouts. Compared with the control, melatonin treatment for 7 days further increased the content of ascorbic acid (by 48-66%), total phenolics (by 52-68%), isoflavones (by 22-34%), the total antioxidant capacity (by 37-40%), and the accumulated levels of unsaturated fatty acids (C18:1, C18:2, and C18:3) (by 17-30%) in soybean sprouts. Moreover, melatonin treatment further increased the accumulation of ten components of phenols and isoflavones in soybean sprouts relative to those in the control. The ability of melatonin to accelerate the degradation of pesticide residues and promote the accumulation of antioxidant metabolites might be related to its ability to trigger the glutathione detoxification system in soybean sprouts. Melatonin promoted glutathione synthesis (by 49-139%) and elevated the activities of glutathione-S-transferase (by 24-78%) and glutathione reductase (by 38-61%). In summary, we report a new method in which combined treatment by melatonin and germination rapidly degrades pesticide residues in contaminated grains and improves the nutritional quality of food.

Dynamics of the content of reactive oxygen species and the state of the glutathione system in the oral cavity during subchronic intoxication wuth the fungicide thiram and its antioxidant correction.

Thiram is a dithiocarbamate derivative, which is used as a fungicide for seed dressing and spraying during the vegetation period of plants, and also as an active vulcanization accelerator in the production of rubber-based rubber products. In this study the content of reactive oxygen species (ROS) and the state of the glutathione system have been investigated in the oral fluid and gum tissues of adult male Wistar rats treated with thiram for 28 days during its administration with food at a dose of 1/50 LD50. Thiram induced formation of ROS in the oral cavity; this was accompanied by an imbalance in the ratio of reduced and oxidized forms of glutathione due to a decrease in glutathione and an increase in its oxidized form as compared to the control. Thiram administration caused an increase in the activity of glutathione-dependent enzymes (glutathione peroxidase, glutathione transferase, and glutathione reductase). However, the time-course of enzyme activation in the gum tissues and oral fluid varied in dependence on the time of exposure to thiram. In the oral fluid of thiram-treated rats changes in the antioxidant glutathione system appeared earlier. The standard diet did not allow the glutathione pool to be fully restored to physiological levels after cessation of thiram intake. The use of exogenous antioxidants resviratrol and an Echinacea purpurea extract led to the restoration of redox homeostasis in the oral cavity.

Development of Aptamer-DNAzyme based metal-nucleic acid frameworks for gastric cancer therapy.

The metal-nucleic acid nanocomposites, first termed metal-nucleic acid frameworks (MNFs) in this work, show extraordinary potential as functional nanomaterials. However, thus far, realized MNFs face limitations including harsh synthesis conditions, instability, and non-targeting. Herein, we discover that longer oligonucleotides can enhance the synthesis efficiency and stability of MNFs by increasing oligonucleotide folding and entanglement probabilities during the reaction. Besides, longer oligonucleotides provide upgraded metal ions binding conditions, facilitating MNFs to load macromolecular protein drugs at room temperature. Furthermore, longer oligonucleotides facilitate functional expansion of nucleotide sequences, enabling disease-targeted MNFs. As a proof-of-concept, we build an interferon regulatory factor-1(IRF-1) loaded Ca2+/(aptamer-deoxyribozyme) MNF to target regulate glucose transporter (GLUT-1) expression in human epidermal growth factor receptor-2 (HER-2) positive gastric cancer cells. This MNF nanodevice disrupts GSH/ROS homeostasis, suppresses DNA repair, and augments ROS-mediated DNA damage therapy, with tumor inhibition rate up to 90%. Our work signifies a significant advancement towards an era of universal MNF application.

Gamma-aminobutyric acid (GABA) improves salinity stress tolerance in soybean seedlings by modulating their mineral nutrition, osmolyte contents, and ascorbate-glutathione cycle.

BACKGROUND: In plants, GABA plays a critical role in regulating salinity stress tolerance. However, the response of soybean seedlings (Glycine max L.) to exogenous gamma-aminobutyric acid (GABA) under saline stress conditions has not been fully elucidated. RESULTS: This study investigated the effects of exogenous GABA (2 mM) on plant biomass and the physiological mechanism through which soybean plants are affected by saline stress conditions (0, 40, and 80 mM of NaCl and Na2SO4 at a 1:1 molar ratio). We noticed that increased salinity stress negatively impacted the growth and metabolism of soybean seedlings, compared to control. The root-stem-leaf biomass (27- and 33%, 20- and 58%, and 25- and 59% under 40- and 80 mM stress, respectively]) and the concentration of chlorophyll a and chlorophyll b significantly decreased. Moreover, the carotenoid content increased significantly (by 35%) following treatment with 40 mM stress. The results exhibited significant increase in the concentration of hydrogen peroxide (H2O2), malondialdehyde (MDA), dehydroascorbic acid (DHA) oxidized glutathione (GSSG), Na+, and Cl- under 40- and 80 mM stress levels, respectively. However, the concentration of mineral nutrients, soluble proteins, and soluble sugars reduced significantly under both salinity stress levels. In contrast, the proline and glycine betaine concentrations increased compared with those in the control group. Moreover, the enzymatic activities of ascorbate peroxidase, monodehydroascorbate reductase, glutathione reductase, and glutathione peroxidase decreased significantly, while those of superoxide dismutase, catalase, peroxidase, and dehydroascorbate reductase increased following saline stress, indicating the overall sensitivity of the ascorbate-glutathione cycle (AsA-GSH). However, exogenous GABA decreased Na+, Cl-, H2O2, and MDA concentration but enhanced photosynthetic pigments, mineral nutrients (K+, K+/Na+ ratio, Zn2+, Fe2+, Mg2+, and Ca2+); osmolytes (proline, glycine betaine, soluble sugar, and soluble protein); enzymatic antioxidant activities; and AsA-GSH pools, thus reducing salinity-associated stress damage and resulting in improved growth and biomass. The positive impact of exogenously applied GABA on soybean plants could be attributed to its ability to improve their physiological stress response mechanisms and reduce harmful substances. CONCLUSION: Applying GABA to soybean plants could be an effective strategy for mitigating salinity stress. In the future, molecular studies may contribute to a better understanding of the mechanisms by which GABA regulates salt tolerance in soybeans.

Protective effect of astaxanthin on testis torsion/detorsion injury through modulation of autophagy.

A significant clinical condition known as testicular torsion leads to permanent ischemic damage to the testicular tissue and consequent loss of function in the testicles. In this study, it was aimed to evaluate the protective effects of Astaxanthin (ASTX) on testicular damage in rats with testicular torsion/detorsion in the light of biochemical and histopathological data. Spraque Dawley rats of 21 were randomly divided into three groups; sham, testicular torsion/detorsion (TTD) and astaxanthin + testicular torsion/detorsion (ASTX + TTD). TTD and ASTX + TTD groups underwent testicular torsion for 2 hours and then detorsion for 4 hours. Rats in the ASTX + TTD group were given 1 mg/kg/day astaxanthin by oral gavage for 7 days before torsion. Following the detorsion process, oxidative stress parameters and histopathological changes in testicular tissue were evaluated. Malondialdehyde (MDA) and total oxidant status (TOS) levels were significantly decreased in the ASTX group compared to the TTD group, while superoxide dismutase (SOD), glutathione (GSH) and total antioxidant status (TAS) levels were increased (p < 0.05). Moreover, histopathological changes were significantly reduced in the group given ASTX (p < 0.0001). It was determined that ASTX administration increased Beclin-1 immunoreactivity in ischemic testicular tissue, while decreasing caspase-3 immunoreactivity (p < 0.0001). Our study is the first to investigate the antiautophagic and antiapoptotic properties of astaxanthin after testicular torsion/detorsion based on the close relationship of Beclin-1 and caspase-3 in ischemic tissues. Our results clearly demonstrate the protective effects of ASTX against ischemic damage in testicular tissue. In ischemic testicular tissue, ASTX contributes to the survival of cells by inducing autophagy and inhibiting the apoptosis.

Plasma Redox Balance in Advanced-Maternal-Age Pregnant Women and Effects of Plasma on Umbilical Cord Mesenchymal Stem Cells.

Pregnancy at advanced maternal age (AMA) is a condition of potential risk for the development of maternal-fetal complications with possible repercussions even in the long term. Here, we analyzed the changes in plasma redox balance and the effects of plasma on human umbilical cord mesenchymal cells (hUMSCs) in AMA pregnant women (patients) at various timings of pregnancy. One hundred patients and twenty pregnant women younger than 40 years (controls) were recruited and evaluated at various timings during pregnancy until after delivery. Plasma samples were used to measure the thiobarbituric acid reactive substances (TBARS), glutathione and nitric oxide (NO). In addition, plasma was used to stimulate the hUMSCs, which were tested for cell viability, reactive oxygen species (ROS) and NO release. The obtained results showed that, throughout pregnancy until after delivery in patients, the levels of plasma glutathione and NO were lower than those of controls, while those of TBARS were higher. Moreover, plasma of patients reduced cell viability and NO release, and increased ROS release in hUMSCs. Our results highlighted alterations in the redox balance and the presence of potentially harmful circulating factors in plasma of patients. They could have clinical relevance for the prevention of complications related to AMA pregnancy.

Deciphering proteomic mechanisms explaining the role of glutathione as an aid in improving plant fitness and tolerance against cadmium-toxicity in Brassica napus L.

Cadmium (Cd) hazard is a serious limitation to plants, soils and environments. Cd-toxicity causes stunted growth, chlorosis, necrosis, and plant yield loss. Thus, ecofriendly strategies with understanding of molecular mechanisms of Cd-tolerance in plants is highly demandable. The Cd-toxicity caused plant growth retardation, leaf chlorosis and cellular damages, where the glutathione (GSH) enhanced plant fitness and Cd-toxicity in Brassica through Cd accumulation and antioxidant defense. A high-throughput proteome approach screened 4947 proteins, wherein 370 were differently abundant, 164 were upregulated and 206 were downregulated. These proteins involved in energy and carbohydrate metabolism, CO2 assimilation and photosynthesis, signal transduction and protein metabolism, antioxidant defense response, heavy metal detoxification, cytoskeleton and cell wall structure, and plant development in Brassica. Interestingly, several key proteins including glutathione S-transferase F9 (A0A078GBY1), ATP sulfurylase 2 (A0A078GW82), cystine lyase CORI3 (A0A078FC13), ferredoxin-dependent glutamate synthase 1 (A0A078HXC0), glutaredoxin-C5 (A0A078ILU9), glutaredoxin-C2 (A0A078HHH4) actively involved in antioxidant defense and sulfur assimilation-mediated Cd detoxification process confirmed by their interactome analyses. These candidate proteins shared common gene networks associated with plant fitness, Cd-detoxification and tolerance in Brassica. The proteome insights may encourage breeders for enhancing multi-omics assisted Cd-tolerance in Brassica, and GSH-mediated hazard free oil seed crop production for global food security.

Exposure to 6-PPD quinone causes ferroptosis activation associated with induction of reproductive toxicity in Caenorhabditis elegans.

Exposure to N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine quinone (6-PPDQ) caused toxicity on Caenorhabditis elegans, including reproductive toxicity. However, the underlying mechanisms for this induced reproductive toxicity by 6-PPDQ remain largely unclear. We examined possible association of ferroptosis activation with reproductive toxicity of 6-PPDQ. In 1-100 µg/L 6-PPDQ exposed nematodes, Fe2+ content was increased, which was accompanied with enhanced lipid peroxidation, increased malonydialdehyde (MDA) content, and decreased L-glutathione (GSH) content. Exposure to 1-100 µg/L 6-PPDQ decreased expressions of ftn-1 encoding ferritin, ads-1 encoding AGPS, and gpx-6 encoding GPX4 and increased expression of bli-3 encoding dual oxidase. After 6-PPDQ exposure, RNAi of ftn-1 decreased ads-1 and gpx-6 expressions and increased bli-3 expression. RNAi of ftn-1, ads-1, and gpx-6 strengthened alterations in ferroptosis related indicators, and RNAi of bli-3 suppressed changes of ferroptosis related indicators in 6-PPDQ exposed nematodes. Meanwhile, RNAi of ftn-1, ads-1, and gpx-6 induced susceptibility, and RNAi of bli-3 caused resistance to 6-PPDQ reproductive toxicity. Moreover, expressions of DNA damage checkpoint genes (clk-2, mrt-2, and hus-1) could be increased by RNAi of ftn-1, ads-1, and gpx-6 in 6-PPDQ exposed nematodes. Therefore, our results demonstrated activation of ferroptosis in nematodes exposed to 6-PPDQ at environmentally relevant concentrations, and this ferroptosis activation was related to reproductive toxicity of 6-PPDQ.

Inhibition of Golgi stress alleviates sepsis-induced cardiomyopathy by reducing inflammation and apoptosis.

BACKGROUND: Sepsis is often accompanied by multiple organ dysfunction, in which the incidence of cardiac injury is about 60%, and is closely related to high mortality. Recent studies have shown that Golgi stress is involved in liver injury, kidney injury, and lung injury in sepsis. However, whether it is one of the key mechanisms of sepsis-induced cardiomyopathy (SIC) is still unclear. The aim of this study is to investigate whether Golgi stress mediates SIC and the specific mechanism. METHODS: Sepsis model of male C57BL/6J mice was established by cecal ligation and puncture. To observe the effect of Golgi stress on SIC, mice were injected with Golgi stimulant (Brefeldin A) or Golgi inhibitor (Glutathione), respectively. The 7-day survival rate of mice were recorded, and myocardial injury indicators including cardiac function, myocardial enzymes, myocardial pathological tissue score, myocardial inflammatory factors, and apoptosis were detected. The morphology of Golgi was observed by immunofluorescence, and the Golgi stress indices including GM-130, GOLPH3 and Goligin97 were detected by WB and qPCR. RESULTS: After CLP, the cardiac function of mice was impaired and the levels of myocardial enzymes were significantly increased. Golgi stress was accompanied by increased myocardial inflammation and apoptosis. Moreover, the expressions of morphological proteins GM-130 and Golgin97 were decreased, and the expression of stress protein GOLPH3 was increased. In addition, Brefeldin A increased 7-day mortality and the above indicators in mice. The use of glutathione improves all of the above indicators. CONCLUSION: Golgi stress mediates SIC, and the inhibition of Golgi stress can improve SIC by inhibiting apoptosis and inflammation.

Congener-specific fate and impact of microcystins in the soil-earthworm system.

Microcystins (MCs) have a significant influence on aquatic ecosystems, but little is known about their terrestrial fate and impact. Here, we investigated the fate of two MCs (MC-LR and MC-RR) in the soil-earthworm system, with consideration of their congener-specific impact on earthworm health, soil bacteria, and soil metabolome. Although MCs had little acute lethal effect on earthworms, they caused obvious growth inhibition and setae rupture. Relative to MC-RR, MC-LR exhibited higher bioaccumulation and the resulting dermal lesions and deformation of longitudinal muscles. While the incorporation of both MCs into soils stimulated pathogenic bacteria and depressed oxidative stress tolerant bacteria, the response among soil nitrification and glutathione metabolism differed between the two congeners. The dissipation kinetics of MCs obeyed the first-order model. Earthworms stimulated soil N-cycling enzyme activities, increased the abundance of MC-degrading bacteria, and promoted bacterial metabolic functions related to glutathione metabolism, xenobiotics biodegradation, and metabolism of amino acids that comprise MCs, which accelerated the dissipation of MC-LR and MC-RR by 227% and 82%, respectively. These results provide evidence of significant congener differences in the terrestrial fate and impact of MCs, which will enable a better understanding of their role in mediating soil functions and ecosystem services.

Mucoadhesive phenylboronic acid-grafted carboxymethyl cellulose hydrogels containing glutathione for treatment of corneal epithelial cells exposed to benzalkonium chloride.

Benzalkonium chloride (BAK) is the most commonly-used preservative in topical ophthalmic medications that may cause ocular surface inflammation associated with oxidative stress and dry eye syndrome. Glutathione (GSH) is an antioxidant in human tears and able to decrease the proinflammatory cytokine release from cells and reactive oxygen species (ROS) formation. Carboxymethyl cellulose (CMC), a hydrophilic polymer, is one of most commonly used artificial tears and can promote the corneal epithelial cell adhesion, migration and re-epithelialization. However, most of commercial artificial tears provide only temporary relief of irritation symptoms and show the short-term treatment effects. In the study, 3-aminophenylboronic acid was grafted to CMC for increase of mucoadhesive properties that might increase the precorneal retention time and maintain the effective therapeutic concentration on the ocular surface. CMC was modified with different degree of substitution (DS) and characterized by Fourier transform infrared spectroscopy and nuclear magnetic resonance spectroscopy. Phenylboronic acid (PBA)-grafted CMC hydrogels have interconnected porous structure and shear thinning behavior. Modification of CMC with high DS (H-PBA-CMC) shows the strong bioadhesive force. The optimal concentration of GSH to treat corneal epithelial cells (CECs) was evaluated by cell viability assay. H-PBA-CMC hydrogels could sustained release GSH and decrease the ROS level. H-PBA-CMC hydrogels containing GSH shows the therapeutic effects in BAK-damaged CECs via improvement of inflammation, apoptosis and cell viability. After topical administration of developed hydrogels, there was no ocular irritation in rabbits. These results suggested that PBA-grafted CMC hydrogels containing GSH might have potential applications for treatment of dry eye disease.

Pinobanksin ameliorated DSS-induced acute colitis mainly through modulation of SLC7A11/glutathione-mediated intestinal epithelial ferroptosis.

Inhibition of ferroptosis in intestinal epithelial cells serves as an attractive target for the development of therapeutic strategies for colitis. Pinobanksin, one of the main flavonoids derived from propolis, possesses significant anti-inflammatory effects and inhibits the cell death of several cell lines. Here, we evaluated whether pinobanksin influenced colitis by modulation of epithelial ferroptosis. Mice treated with 2.5% DSS dissolved in sterile distilled water were established for an acute colitis model. The mitochondrial morphology, colonic iron level, lipid peroxidation products MDA/4-HNE, and lipid reactive oxygen species levels were measured to assess ferroptosis in epithelial cells. RNA-seq and functional analyses were performed to reveal key genes mediating pinobanksin-exerted modulation of ferroptosis. We found that pinobanksin, at different doses, induced significant anti-colitis effects and inhibited the elevated ferroptosis in colonic epithelial cells isolated from DSS-treated mice largely by activating GPX4 (negative regulator of ferroptosis). Furthermore, RNA-seq assays indicated that pinobanksin significantly increased the cystine transporter SLC7A11 in colonic tissues from mice with colitis. Depletion of SLC7A11 largely blocked pinobanksin-induced promotion of cystine uptake/glutathione biosynthesis and suppression of ferroptosis in epithelial cells from mice with colitis or IEC-6 cells pretreated with RSL3. Altogether, pinobanksin alleviated DSS-induced colitis largely by inhibition of ferroptosis in epithelial cells. Activation of SLC7A11 by pinobanksin resulted in the promotion of cystine uptake and enhancement of glutathione biosynthesis. This work will provide novel guidance for the clinical use of pinobanksin to treat colitis through inhibition of epithelial ferroptosis.

Supreme glutathione-dependent ketosteroid isomerase in the yellow-fever transmitting mosquito Aedes aegypti.

The steroid hormone ecdysone is essential for the reproduction and survival of insects. The hormone is synthesized from dietary sterols such as cholesterol, yielding ecdysone in a series of consecutive enzymatic reactions. In the insect orders Lepidoptera and Diptera a glutathione transferase called Noppera-bo (Nobo) plays an essential, but biochemically uncharacterized, role in ecdysteroid biosynthesis. The Nobo enzyme is consequently a possible target in harmful dipterans, such as disease-carrying mosquitoes. Flavonoid compounds inhibit Nobo and have larvicidal effects in the yellow-fever transmitting mosquito Aedes aegypti, but the enzyme is functionally incompletely characterized. We here report that within a set of glutathione transferase substrates the double-bond isomerase activity with 5-androsten-3,17-dione stands out with an extraordinary specific activity of 4000 µmol min-1 mg-1. We suggest that the authentic function of Nobo is catalysis of a chemically analogous ketosteroid isomerization in ecdysone biosynthesis.

Regulation of Cysteine Homeostasis and Its Effect on Escherichia coli Sensitivity to Ciprofloxacin in LB Medium.

Cysteine and its derivatives, including H2S, can influence bacterial virulence and sensitivity to antibiotics. In minimal sulfate media, H2S is generated under stress to prevent excess cysteine and, together with incorporation into glutathione and export into the medium, is a mechanism of cysteine homeostasis. Here, we studied the features of cysteine homeostasis in LB medium, where the main source of sulfur is cystine, whose import can create excess cysteine inside cells. We used mutants in the mechanisms of cysteine homeostasis and a set of microbiological and biochemical methods, including the real-time monitoring of sulfide and oxygen, the determination of cysteine and glutathione (GSH), and the expression of the Fur, OxyR, and SOS regulons genes. During normal growth, the parental strain generated H2S when switching respiration to another substrate. The mutations affected the onset time, the intensity and duration of H2S production, cysteine and glutathione levels, bacterial growth and respiration rates, and the induction of defense systems. Exposure to chloramphenicol and high doses of ciprofloxacin increased cysteine content and GSH synthesis. A high inverse relationship between log CFU/mL and bacterial growth rate before ciprofloxacin addition was revealed. The study points to the important role of maintaining cysteine homeostasis during normal growth and antibiotic exposure in LB medium.