Elevated Glutathione Concentration Research Articles

Transformable binary-prodrug nanoparticles harness heterogeneity of neutrophils to overcome multidrug resistance and promote pyroptosis in cancer

Neutrophils, the most abundant myeloid cells, exhibit diverse phenotypic and functional variants in both homeostatic and disease conditions. The inherent heterogeneity of neutrophils positions them as promising candidates for drug carriers, facilitating precise drug delivery to tumor tissues and enhancing treatment accuracy and effectiveness. However, challenges arise from drug toxicity hindering neutrophil migration and the imperative need for efficient drug release at tumor sites. In response to these challenges, we have developed transformable binary-prodrug nanoparticles known as DSST@PSA. These nanoparticles manifest in two distinct forms: U-shaped and I-shaped. The U-shaped DSST@PSA variant demonstrates reduced toxicity and can be effectively transported to tumor sites through a neutrophil-mediated drug delivery system. Within the tumor microenvironment, the elevated glutathione concentration triggers a transformation of DSST@PSA into I-shaped structures. The I-shaped DSST@PSA variant exhibits the capability to overcome doxorubicin-induced multidrug resistance and promote pyroptosis in tumor cells. Our innovative DSST@PSA treatment strategy has demonstrated remarkable therapeutic effects in both in situ breast and metastatic mouse models. This breakthrough in neutrophil-mediated drug delivery systems significantly enhances treatment precision and efficacy.

Photoacoustic imaging of elevated glutathione in models of lung cancer for companion diagnostic applications.

Companion diagnostics (CDx) are powerful tests that can provide physicians with crucial biomarker information that can improve treatment outcomes by matching therapies to patients. Here, we report a photoacoustic imaging-based CDx (PACDx) for the selective detection of elevated glutathione (GSH) in a lung cancer model. GSH is abundant in most cells, so we adopted a physical organic chemistry approach to precisely tune the reactivity to distinguish between normal and pathological states. To evaluate the efficacy of PACDx in vivo, we designed a blind study where photoacoustic imaging was used to identify mice bearing lung xenografts. We also employed PACDx in orthotopic lung cancer and liver metastasis models to image GSH. In addition, we designed a matching prodrug, PARx, that uses the same SNAr chemistry to release a chemotherapeutic with an integrated PA readout. Studies demonstrate that PARx can inhibit tumour growth without off-target toxicity in a lung cancer xenograft model.

Chemopreventive effect of hesperidin, a citrus bioflavonoid in two stage skin carcinogenesis in Swiss albino mice

The cancer-protective ability of hesperidin was investigated on 7, 12-dimethylbenz[a]anthracene (DMBA) and 12-O-tetradecanoyl phorbol-13-acetate (TPA)-induced skin carcinogenesis in Swiss albino mice. Topical application of DMBA+TPA on mice skin led to 100% tumour incidence and rise in average number of tumours. Administration of different doses of hesperidin (HPD) before (pre) or after (post) and continuous (pre and post) DMBA application significantly reduced tumour incidence and average number of tumours in comparison to DMBA+TPA treatment alone. Topical application of DMBA+TPA increased oxidative stress as shown by significantly increased TBARS values and reduced glutathione contents, and glutathione-S-transferase, superoxide dismutase and catalase activities. Hesperidin treatment significantly reduced TBARS values and elevated glutathione concentration and glutathione-S-transferase, superoxide dismutase and catalase activities in the skin/tumors of mice treated with HPD+DMBA+TPA, HPD+DMBA+TPA+HPD or DMBA+TPA+HPD when compared to DMBA+TPA application alone. The study of molecular mechanisms showed that hesperidin suppressed expression of Rassf7, Nrf2, PARP and NF-κB in a dose dependent manner with a maximum inhibition at the level of 300 mg/kg body weight hesperidin. In conclusion, oral administration of hesperidin protected mice against chemical carcinogenesis by increasing antioxidant status, reducing DMBA+TPA induced lipid peroxidation and inflammatory response, and repressing of Rassf7, Nrf2, PARP and NF-κB levels.

Impact of glutathione metabolism on zinc homeostasis in Saccharomyces cerevisiae.

Zinc is a crucial mineral for all organisms as it is an essential cofactor for the proper function of a plethora of proteins and depletion of zinc causes oxidative stress. Glutathione is the major redox buffering agent in the cell and therefore important for mitigation of the adverse effects of oxidative stress. In mammalian cells, zinc deficiency is accompanied by a glutathione depletion. In the yeast Saccharomyces cerevisiae, the opposite effect is observed: under low zinc conditions, an elevated glutathione concentration is found. The main regulator to overcome zinc deficiency is Zap1p. However, we show that Zap1p is not involved in this glutathione accumulation phenotype. Furthermore, we found that in glutathione-accumulating strains also the metal ion-binding phytochelatin-2, which is an oligomer of glutathione, is accumulated. This increased phytochelatin concentration correlates with a lower free zinc level in the vacuole. These results suggest that phytochelatin is important for zinc buffering in S. cerevisiae and thus explains how zinc homeostasis is connected with glutathione metabolism.

Selenite activates the alternative oxidase pathway and alters primary metabolism in Brassica napus roots: evidence of a mitochondrial stress response

BackgroundHuman requirements for dietary selenium are met mainly by crops. However, excessive uptake of selenium in plants can restrict growth, and its toxicity has been postulated to target roots. Selenite toxicity can be attributed to its assimilation into selenocysteine, which can replace cysteine to yield malformed selenoproteins. Additionally, selenite has pro-oxidant properties. In this study, the effects of selenite on root tissue in Brassica napus (canola) were investigated to better understand its mode of toxicity and the metabolic adjustments needed to mediate a selenite-response.ResultsSelenite induced the rapid formation of mitochondrial superoxide, which led to decreased aconitase activity and involvement of the alternative oxidase pathway. Although selenite altered primary metabolism, as observed by the increased amino acids and decreased TCA cycle metabolites, increased glucose presumably supported higher respiratory rates and ATP levels reported in this study. Additionally, evidence is presented indicating that selenite suppressed the ubiquitin-proteasome pathway, and induced the pentose phosphate pathway needed to maintain antioxidant metabolism. Selenite treatment also elevated glutathione concentration and coincided with increased levels of γ-glutamyl cyclotransferase, which may possibly degrade selenium metabolites conjugated to glutathione.ConclusionCollectively, the data indicate that selenite necessitates the reconfiguration of metabolic pathways to overcome the consequences of mitochondrial oxidative stress in root tissue. Efforts to mitigate the detrimental effects of selenite-induced oxidative stress may ultimately improve selenium tolerance and accumulation in crops.Electronic supplementary materialThe online version of this article (doi:10.1186/s12870-014-0259-6) contains supplementary material, which is available to authorized users.

Aberrations of methyl group and homocysteine metabolism during the progression of diabetes in the ZDF rat

Altered methyl group and homocysteine (Hcy) metabolism was tissue‐specific, non‐transient, and preceded hepatic DNA hypomethylation in STZ‐induced type 1 diabetes. Similar perturbations occur in the Zucker (type 2) diabetic fatty (ZDF) rat, but the tissue specificity and effect of disease progression are unknown. ZDF and lean rats were killed at 12 and 21 wk of age. At 12 wk, hepatic glycine N‐methyltransferase (GNMT), methionine synthase, and cystathionine β‐synthase (CBS) activity/abundance were increased, whereas plasma Hcy was decreased in ZDF rats. At 21 wk, GNMT was induced in liver and kidney. In liver only, there was a trend toward increased CBS protein abundance (78%, p = 0.080) and betaine‐Hcy methyltransferase mRNA expression (~100%, p = 0.098). Phosphatidylethanolamine methyltransferase activity tended to be lower in ZDF liver (p =0.071) despite an increase (p < 0.05) in mRNA expression. Hcy levels were decreased in plasma and kidney, but not in liver, at 12 and 21 wk. Elevated glutathione concentrations in liver and kidney at 12 wk, and in kidney at 21 wk, suggests altered regulation of redox homeostasis. Hepatic genomic DNA was hypermethylated at 12 and 21 wk, with a trend toward increased DNMT1 mRNA expression (p = 0.08) at 21 wk. In summary, alterations of methyl group and Hcy metabolism, redox status, and epigenetic regulation result during the progression of type 2 diabetes. Support: Am. Heart Assn.

Vitamin B-6 restriction tends to reduce the red blood cell glutathione synthesis rate without affecting red blood cell or plasma glutathione concentrations in healthy men and women

Background:Glutathione plays various protective roles in the human body. Vitamin B-6 as pyridoxal-5′-phosphate (PLP) is required as the coenzyme in the formation of glutathione precursors. Despite this obligatory role of PLP, previous studies from this laboratory showed that vitamin B-6 deficiency caused elevated glutathione concentrations in rat liver and human plasma. Objective:Our aim was to determine the effect of marginal vitamin B-6 deficiency (plasma PLP 20–30 nmol/L) on the rate of red blood cell (RBC) glutathione synthesis. Design:We measured plasma and RBC glutathione concentrations and the fractional and absolute synthesis rates of RBC glutathione using the stable-isotope-labeled glutathione precursor [1,2-13C2]glycine in 13 healthy volunteers aged 21–39 y. Results:Dietary vitamin B-6 restriction did not significantly affect the glutathione concentration in plasma (6.9 ± 1.9 compared with 6.7 ± 1.1μmol/L) or RBCs (2068 ± 50 compared with 2117 ± 48μmol/L). For RBC glutathione, the mean fractional synthesis rates were 54 ± 5%/d and 43 ± 4%/d (P = 0.10), and the absolute synthesis rates were 1116 ± 100 and 916 ± 92μmol · L−1 · d−1 (P = 0.14) before and after vitamin B-6 restriction, respectively. Conclusions:Marginal vitamin B-6 deficiency tended to decrease mean RBC glutathione synthesis with no effect on RBC glutathione concentration, but the responses varied widely among individuals. Because the cysteine concentration in plasma and RBC did not change during vitamin B-6 restriction, we conclude that the effects of marginal vitamin B-6 deficiency on glutathione synthesis are not caused by altered precursor concentrations.

Effects of zucchini yellow mosaic virus infection on the subcellular distribution of glutathione and its precursors in a highly tolerantCucurbita pepocultivar

Glutathione (γ-glutamyl-cysteinyl-glycine) is an antioxidant that plays important protective roles during pathogen attack. Glutathione synthesis is a highly compartment-specific pathway and relies on the supply of its precursors cysteine, glutamate, and glycine. To study the importance of glutathione in the development of tolerance and resistance, glutathione and its precursors were quantified with cytohistochemical methods in a highly tolerant cultivar (‘Quine’) of Cucurbita pepo L. during zucchini yellow mosaic virus (ZYMV) infection. Glutathione concentrations were strongly increased in almost all cell compartments of younger leaves (up to 247% in peroxisomes), older leaves (up to 73% in the cytosol), and roots (up to 104% in nuclei) during ZYMV infection. In addition, glutathione precursor concentrations were generally unchanged or increased in all cell compartments of younger leaves and roots, indicating that glutathione synthesis in these organs was not limited by low levels of glutathione precursors. The lower increase of glutathione in older leaves could be caused by strongly decreased levels of glycine in plastids (42%) and the cytosol (53%) during ZYMV infection, as they are the main centers for glutathione synthesis. Nevertheless, as the increase in glutathione was in general much higher than that observed in a highly susceptible cultivar in previous studies, we can conclude that elevated glutathione concentrations can be strongly correlated with the development of tolerance during ZYMV infection.

Systemic, pulmonary, and hepatosplanchnic effects of N-acetylcysteine during long-term porcine endotoxemia.

Controversial data have been reported on the effects of N-acetylcysteine in patients with septic shock. We therefore investigated the systemic, pulmonary, and hepatosplanchnic hemodynamic, gas exchange, and metabolic effects of N-acetylcysteine during long-term, volume-resuscitated, hyperdynamic porcine endotoxemia, which mimics the features of hyperdynamic human sepsis. Prospective, randomized, controlled experimental study. Investigational animal laboratory. Eighteen pigs were randomized to receive endotoxin alone (controls, n = 9) or endotoxin plus N-acetylcysteine (n = 9). Anesthetized, mechanically ventilated, and instrumented animals received continuous intravenous endotoxin and were resuscitated with hydroxyethylstarch to keep mean arterial pressure >60 mm Hg. After 12 hrs of endotoxemia, they were randomized to receive either placebo or N-acetylcysteine (150 mg/kg loading dose over 1 hr followed by 20 mg.kg-1.hr-1 for 11 hrs). Before as well as 12, 18, and 24 hrs after starting the endotoxin infusion, systemic, pulmonary, and hepatosplanchnic hemodynamics, oxygen exchange, and metabolism as well as nitric oxide, glutathione, and 8-isoprostane concentrations were assessed. N-acetylcysteine failed to improve any of the variables of the systemic, pulmonary, or hepatosplanchnic hemodynamics, gas exchange, and metabolism. Although N-acetylcysteine significantly elevated glutathione concentration, it did not influence the 8-isoprostane concentrations and even further reduced hepatic venous pH. Despite the increased glutathione concentration, N-acetylcysteine did not improve systemic, pulmonary, and hepatosplanchnic hemodynamics, oxygen exchange, and metabolism. When compared with previous reports in the literature, a different timing of N-acetylcysteine administration and/or an ongoing or even N-acetylcysteine-induced aggravation of oxidative stress may account for this result.

Protection from Paraquat‐Mediated Photo‐Oxidative Stress by Glutathione in Poplar (Populus tremula×P. alba) Plants

Abstract: The sensitivity of hybrid poplar (Populus tremula×P. alba) to oxidative stress mediated by paraquat exposure was analysed with leaf discs from wild‐type plants and plants expressing the bacterial cDNA of the enzymes of glutathione synthesis, namely gshI, encoding γ‐glutamylcysteine synthetase (ECS), or gshII, encoding glutathione synthetase (GS), both in the cytosol. It was expected that leaf discs containing more than 2‐fold elevated glutathione concentrations due to over‐expression of ECS are less susceptible to paraquat exposure than wild‐type plants and transformants over‐expressing GS. However, neither over‐expression of GS nor of ECS improved paraquat tolerance of the leaves. This result was surprising, because in wild‐type plants reduced paraquat sensitivity of young compared with mature leaves coincided with ca. 30 % higher glutathione contents of the young leaves. Apparently, developmental changes in paraquat sensitivity of poplar leaves are controlled by factors different from glutathione contents. Feeding experiments with glutathione and its metabolic precursor γ‐glutamylcysteine (EC) plus gly showed that glutathione can provide protection from paraquat‐mediated photo‐oxidative stress; but at least ca. 5‐fold elevated glutathione levels are required for this effect in poplar leaves. Currently, such high glutathione levels have not been achieved by the application of plant molecular biology techniques. The significance of glutathione for the compensation of photo‐oxidative stress is discussed.