Glutathione and Glutathione Transferase Omega 1 as Key Posttranslational Regulators in Macrophages

Plasma levels of CD36 and glutathione as biomarkers for ruptured intracranial aneurysm

Evidence has proved that intracranial aneurysm (IA) formation and rupture might be closely related to inflammatory response and oxidative stress. Our objective was to evaluate the potential of CD36 and glutathione (GSH) as biomarkers for IA. In this study, the enzyme-linked immunosorbent assay was used to measure the plasma levels of CD36 and GSH in 30 IA patients and 30 healthy controls. Then, correlation analysis, receiver operating characteristic (ROC) curve, and logistic regression analysis were performed. The results showed that the plasma level of CD36 in IA patients was significantly higher than that in the control group (P < 0.0001), and plasma GSH was significantly lower compared with that in the control group (P < 0.0001). ROC analysis showed that CD36 and GSH had high sensitivity (90.0 and 96.6%) and specificity (96.6 and 86.6%) for IA diagnosis. The combined sensitivity and specificity achieved were 100 and 100%, respectively. The plasma levels of CD36 and GSH did not show a significant correlation with age, the Glasgow Coma Scale, Hunter-Hess score, aneurysm size, aneurysm height, aneurysm neck, and aspect ratio. The AUC of the logistic regression model based on CD36 and GSH was 0.505. Our results suggested that the combination of plasma CD36 and GSH could serve as potential biomarkers for IA rupture.

Nuclear factor kappa B expression in non-small cell lung cancer

In this mini-review, we discuss the role of NF-κB, a proinflammatory transcription factor, in the expression of genes involved in inflammation, proliferation, and apoptosis pathways, and link it with prognosis of various human cancers, particularly non-small cell lung cancer (NSCLC). We and others have shown that NF-κB activity can be impacted by post-translational S-glutathionylation through reversible formation of a mixed disulfide bond between its cysteine residues and glutathione (GSH). Clinical data analysis showed that high expression of NF-κB correlated with shorter overall survival (OS) in NSCLC patients, suggesting a tumor promotion function for NF-κB. Moreover, NF-κB expression was associated with tumor stage, lymph node metastasis, and 5-year OS in these patients. NF-κB was over-expressed in the cytoplasm of tumor tissue compared to adjacent normal tissues. S-glutathionylation of NF-κB caused negative regulation by interfering with DNA binding activities of NF-κB subunits. In response to oxidants, S-glutathionylation of NF-κB also correlated with enhanced lung inflammation. Thus, S-glutathionylation is an important contributor to NF-κB regulation and clinical results highlight the importance of NF-κB in NSCLC, where NF-κB levels are associated with unfavorable prognosis.

Salivary Chemical Barrier Proteins in Oral Squamous Cell Carcinoma-Alterations in the Defense Mechanism of the Oral Cavity

Oral squamous cell carcinoma (OSCC) is one of the most frequent types of head and neck cancer. Despite the genetic and environmental risk factors, OSCC is also associated with microbial infections and/or dysbiosis. The secreted saliva serves as the chemical barrier of the oral cavity and, since OSCC can alter the protein composition of saliva, our aim was to analyze the effect of OSCC on the salivary chemical barrier proteins. Publicly available datasets regarding the analysis of salivary proteins from patients with OSCC and controls were collected and examined in order to identify differentially expressed chemical barrier proteins. Network analysis and gene ontology (GO) classification of the differentially expressed chemical barrier proteins were performed as well. One hundred and twenty-seven proteins showing different expression pattern between the OSCC and control groups were found. Protein-protein interaction networks of up- and down-regulated proteins were constructed and analyzed. The main hub proteins (IL-6, IL-1B, IL-8, TNF, APOA1, APOA2, APOB, APOC3, APOE, and HP) were identified and the enriched GO terms were examined. Our study highlighted the importance of the chemical barrier of saliva in the development of OSCC.

N-acetylcysteine modulates rotenone-induced mitochondrial Complex I dysfunction in THP-1 cells

Mitochondrial Complex I dysfunction and oxidative stress have been part of the pathophysiology of several diseases ranging from mitochondrial disease to chronic diseases such as diabetes, mood disorders and Parkinson's Disease. Nonetheless, to investigate the potential of mitochondria-targeted therapeutic strategies for these conditions, there is a need further our understanding on how cells respond and adapt in the presence of Complex I dysfunction. In this study, we used low doses of rotenone, a classical inhibitor of mitochondrial complex I, to mimic peripheral mitochondrial dysfunction in THP-1 cells, a human monocytic cell line, and explored the effects of N-acetylcysteine on preventing this rotenone-induced mitochondrial dysfunction. Our results show that in THP-1 cells, rotenone exposure led to increases in mitochondrial superoxide, levels of cell-free mitochondrial DNA, and protein levels of the NDUFS7 subunit. N-acetylcysteine (NAC) pre-treatment ameliorated the rotenone-induced increase of cell-free mitochondrial DNA and NDUFS7 protein levels, but not mitochondrial superoxide. Furthermore, rotenone exposure did not affect protein levels of the NDUFV1 subunit but induced NDUFV1 glutathionylation. In summary, NAC may help to mitigate the effects of rotenone on Complex I and preserve the normal function of mitochondria in THP-1 cells.

Chemistry and biology of enzymes in protein glutathionylation

Protein S-glutathionylation is emerging as a central oxidation that regulates redox signaling and biological processes linked to diseases. In recent years, the field of protein S-glutathionylation has expanded by developing biochemical tools for the identification and functional analyses of S-glutathionylation, investigating knockout mouse models, and developing and evaluating chemical inhibitors for enzymes involved in glutathionylation. This review will highlight recent studies of two enzymes, glutathione transferase omega 1 (GSTO1) and glutaredoxin 1 (Grx1), especially introducing their glutathionylation substrates associated with inflammation, cancer, and neurodegeneration and showcasing the advancement of their chemical inhibitors. Lastly, we will feature protein substrates and chemical inducers of LanC-like protein (LanCL), the first enzyme in protein C-glutathionylation.

Galectin-3 S-glutathionylation regulates its effect on adipocyte insulin signaling

Protein-S-glutathionylation promotes redox signaling in physiological and oxidative distress conditions. Galectin-3 (Gal-3) promotes insulin resistance by down-regulating adipocyte insulin signaling, however, its S-glutathionylation and significance is not known. In this context, we report reversible S-glutathionylation of Gal-3. Site-directed mutagenesis established Gal-3 Cys187 as the putative S-glutathionylation site. Glutathionylated Gal-3 prevents Gal-3(WT)-Insulin Receptor interaction and facilitates insulin-induced murine adipocyte p-IRS1(tyr895) and p-AKT(ser473) signaling and glucose uptake in a Gal-3 Cys187 glutathionylation dependent manner in murine adipocytes, as assessed by Western blotting and 2-NBDG uptake assay respectively. Pre-glutathionylated Gal-3 at Cys187 resisted irreversible oxidation by H₂O₂. M2 macrophages showed enhanced Gal-3 S-glutathionylation when compared to M1 phenotype. Serum and stromal vascular fraction (SVF) isolated from control mice showed increased Gal-3 S-glutathionylation as compared to db/db mice. A significant increase in Gal-3 S-glutathionylation was observed in metformin-treated db/db mice when compared to db/db mice alone. Similar to murine, enhanced Gal-3 S-glutathionylation is observed in primary human monocyte derived M2 macrophages when compared to the M1 macrophage phenotype and Gal-3 regulates primary human adipocyte insulin signaling in a glutathionylation dependent manner. Collectively, we identified Gal-3 S-glutathionylation as a protective phenomenon, which relieves its inhibitory effect on adipocyte insulin signaling.

Association of Low Molecular Weight Plasma Aminothiols with the Severity of Coronavirus Disease 2019

Objective

Aminothiols (glutathione (GSH), cysteinylglycine (CG)) may play an important role in the pathogenesis of coronavirus disease 2019 (COVID-19), but the possible association of these indicators with the severity of COVID-19 has not yet been investigated.

Methods

The total content (t) and reduced forms (r) of aminothiols were determined in patients with COVID-19 (n = 59) on admission. Lung injury was characterized by computed tomography (CT) findings in accordance with the CT0-4 classification.

Results

Low tGSH level was associated with the risk of severe COVID-19 (tGSH ≤ 1.5 μM, mild vs. moderate/severe: risk ratio (RR) = 3.09, p = 0.007) and degree of lung damage (tGSH ≤ 1.8 μM, CT < 2 vs. CT ≥ 2: RR = 2.14, p = 0.0094). The rGSH level showed a negative association with D-dimer levels (ρ = -0.599, p = 0.014). Low rCG level was also associated with the risk of lung damage (rCG ≤ 1.3 μM, CT < 2 vs. CT ≥ 2: RR = 2.28, p = 0.001). Levels of rCG (ρ = -0.339, p = 0.012) and especially tCG (ρ = -0.551, p = 0.004) were negatively associated with platelet count. In addition, a significant relationship was found between the advanced oxidation protein product level and tGSH in patients with moderate or severe but not in patients with mild COVID-19.

Conclusion

Thus, tGSH and rCG can be seen as potential markers for the risk of severe COVID-19. GSH appears to be an important factor to oxidative damage prevention as infection progresses. This suggests the potential clinical efficacy of correcting glutathione metabolism as an adjunct therapy for COVID-19.

New roles for glutathione: Modulators of bacterial virulence and pathogenesis

Low molecular weight (LMW) thiols contain reducing sulfhydryl groups that are important for maintaining antioxidant defense in the cell. Aside from the traditional roles of LMW thiols as redox regulators in bacteria, glutathione (GSH) has been reported to affect virulence and bacterial pathogenesis. The role of GSH in virulence is diverse, including the activation of virulence gene expression and contributing to optimal biofilm formation. GSH can also be converted to hydrogen sulfide (H₂S) which is important for the pathogenesis of certain bacteria. Besides GSH, some bacteria produce other LMW thiols such as mycothiol and bacillithiol that affect bacterial virulence. We discuss these newer reported functions of LMW thiols modulating bacterial pathogenesis either directly or indirectly and via modulation of the host immune system.

Glutathione transferase Omega 1 confers protection against azoxymethane-induced colorectal tumour formation

Inflammatory bowel disease (IBD) is characterized by multiple alterations in cytokine expression and is a risk factor for colon cancer. The Omega class glutathione transferase GSTO1-1 regulates the release of the pro-inflammatory cytokines interleukin 1β (IL-1β) and interleukin 18 (IL-18) by deglutathionylating NEK7 in the NLRP3 inflammasome. When treated with azoxymethane and dextran sodium sulphate (AOM/DSS) as a model of IBD, Gsto1-/- mice were highly sensitive to colitis and showed a significant increase in the size and number of colon tumours compared with wild-type (WT) mice. Gsto1-/- mice treated with AOM/DSS had significantly lower serum IL-1β and IL-18 levels as well as significantly decreased interferon (IFN)-γ, decreased pSTAT1 and increased pSTAT3 levels in the distal colon compared with similarly treated WT mice. Histologically, AOM/DSS treated Gsto1-/- mice showed increased active chronic inflammation with macrophage infiltration, epithelial dysplasia and invasive adenocarcinoma compared with AOM/DSS treated WT mice. Thus, this study shows that GSTO1-1 regulates IL-1β and IL-18 activation and protects against colorectal cancer formation in the AOM/DSS model of IBD. The data suggest that while GSTO1-1 is a new target for the regulation of the NLRP3 inflammasome-associated cytokines IL-1β and IL-18 by small molecule inhibitors, there is a possibility that anti-inflammatory drugs targeting these cytokines may potentiate colon cancer in some situations.

Triptolide delivery: Nanotechnology-based carrier systems to enhance efficacy and limit toxicity

Triptolide (TP) possesses a wide range of biological and pharmacological activities involved in the treatment of various diseases. However, widespread usages of TP raise the urgent issues of the severe toxicity, which hugely limits its further clinical application. The novel functional nanostructured delivery system, which is of great significance in enhancing the efficacy, reducing side effects and improving bioavailability, could improve the enrichment, penetration and controlled release of drugs in the lesion location. Over the past decades, considerable efforts have been dedicated to designing and developing a variety of TP delivery systems with the intention of alleviating the adverse toxicity effects and enhancing the bioavailability. In this review, we briefly summarized and discussed the recent functionalized nano-TP delivery systems for the momentous purpose of guiding further development of novel TP delivery systems and providing perspectives for future clinical applications.

Serum Selenium Status and Its Interrelationship with Serum Biomarkers of Thyroid Function and Antioxidant Defense in Hashimoto's Thyroiditis

Selenium (Se) deficiency has been implicated in the pathogenesis of Hashimoto’s thyroiditis (HT), although the available evidence is limited. The present study aimed to explore the interrelationships between serum Se status with measures of thyroid function and antioxidant defense in new cases of HT patients with hypoechogenic thyroid. HT patients (n = 49) and matched controls (n = 50) were recruited. Selenium, thyroid hormone panel, thyroid volume (TVol), glutathione (GSH), glutathione peroxidase3 (GPx3) activity, urinary iodine concentration (UIC), and urinary creatinine (Cr) were assessed. HT patients exhibited lower Se levels compared to controls (p < 0.001) with the rates of Se-deficient (<0.85 µmol/L) participants being 58.8% and 34%, respectively. Se-deficient patients exhibited higher thyroid stimulating hormone (TSH), Thyroid volume (TVol), thyroglobulin, antibody-titers, GPx3 activity and UIC/Cr compared to Se-sufficient patients (all p < 0.001). In the Se-deficient patients, inverse correlations were seen between Se-levels with TSH, TVol, and Thyroid peroxidase antibody (TPO-Ab) (all p < 0.001). This study is the first to uncover that coexisting Se-deficiency and elevated iodine in HT may enhance autoimmune reactions and accelerate the deterioration of thyroid function through oxidative stress. Our study also highlights the importance of optimal Se status in this disease, thus providing a rationale for the execution of intervention trials for the evaluation of the clinical benefits of antioxidant-status improvement in HT.

Deletion of Glutathione S-Transferase Omega 1 Activates Type I Interferon Genes and Downregulates Tissue Factor

GST omega 1 (GSTO1) is an atypical GST isoform that is overexpressed in several cancers and has been implicated in drug resistance. Currently, no small-molecule drug targeting GSTO1 is under clinical development. Here we have validated GSTO1 as an impactful target in oncology. Transcriptional profiling coupled with proteomics uncovered novel pharmacodynamic markers and cellular pathways regulated by GSTO1. CRISPR/Cas9 GSTO1 knockout (KO) cell lines failed to form tumors or displayed growth delay in vivo; they also formed smaller 3D spheroids in vitro. Multiomics analysis in GSTO1 KO cells found a strong positive correlation with cell adhesion molecules and IFN response pathways and a strong negative correlation with Myc transcriptional signature. In addition, several clinically used drugs showed significant synthetic lethality with loss or inhibition of GSTO1. Transcription and protein expression of tissue factor (gene name, F3) were downregulated in response to GSTO1 KO. F3 is associated with poor patient survival and promotion of tumor progression in multiple cancers and is a known risk factor for metastasis. Transcription of F3 was regulated by IL1β, whose secretion decreased upon inhibition of GSTO1, suggesting that IL1β links GSTO1 expression and F3 transcription. In summary, our results implicate GSTO1 as a potential therapeutic target in cancer and offer new mechanistic insights into its significant role in cancer progression. SIGNIFICANCE: These findings validate GSTO1 as a therapeutic target in cancer and implicate GSTO1 in the modulation of tumor growth, immune responses, and expression of F3.

Effects of dietary methionine plus cysteine levels on growth performance and intestinal antibody production in broilers during Eimeria challenge

Research has shown that methionine+ cysteine (M+C) requirements may be higher when chickens are infected with Eimeria app. In a 4 × 2 factorial design, broilers (11 to 21 D) were fed one of 4 corn–soybean meal-based diets containing either 0.6, 0.8, 0.9, or 1.0% standardized ileal digestible (SID) M+C; on day 14, broilers from each diet were gavaged with either phosphate-buffered saline (PBS) or a commercial coccidiosis vaccine (at 100 × vaccine dose) which provide a mixture of live Eimeria acervulina, Eimeria maxima, and Eimeria tenella oocysts. Growth performance was recorded from day 11 to 21. Plasma and intestinal luminal samples were collected on days 14 and 21. Intestine lesion scores and fecal oocyst counts were conducted on day 21. Regardless of dietary SID M+C levels, compared to PBS gavaged broilers, the Eimeria-challenged broilers had (1) decreased (P < 0.05) body weight gain (BWG), feed intake (FI), and gain-to-feed ratio (G:F); (2) increased (P < 0.05) intestinal lesion scores and fecal oocyst counts; (3) increased (P < 0.05) plasma anti-Eimeria IgG, and intestinal luminal total IgA and anti-Eimeria IgA concentrations; and (4) increased (P < 0.05) levels of duodenum luminal gamma interferon (IFN-γ) and interleukin-10 (IL-10), as well as jejunum and cecum luminal IFN-γ concentrations. Regardless of Eimeria challenge, when compared to 0.6% SID M+C, broilers fed ≥0.8% SID M+C had (1) increased (P < 0.05) BWG, FI, and G:F and (2) increased (P < 0.05) levels of jejunum luminal total IgA. After Eimeria challenge, broilers fed 0.8% SID M+C had increased (P < 0.05) levels of jejunum luminal anti-Eimeria IgA compared to broilers fed diets containing 0.6 and 1.0% SID M+C. Collectively, in 11- to 21-D broilers, the growth suppression caused by Eimeria infection could not be mitigated by further increasing dietary M+C alone ≥0.8%. Further research should investigate interactions between dietary M+C and other nutrients for support of immune function and growth in pathogen-challenged broilers.

Metabolic regulation of inflammasomes in inflammation

Inflammasome activation and subsequent inflammatory cytokine secretion are essential for innate immune defence against multiple stimuli and are regarded as a link to adaptive immune responses. Dysfunction of inflammasome activation has been discovered at the onset or progression of infectious diseases, autoimmune diseases and cancer, all of which are also associated with metabolic factors. Furthermore, many studies concerning the metabolic regulation of inflammasome activation have emerged in recent years, especially regarding the activity of the NLRP3 inflammasome under metabolic reprogramming. In this review, we discuss the molecular mechanisms of the interactions between metabolic pathways and inflammasome activation, which exerts further important effects on various diseases.

Redox-responsive self-assembly PEG nanoparticle enhanced triptolide for efficient antitumor treatment

Chemotherapy induces tumor cell death by directly damaging DNA or hindering cell mitosis. Some of the drawbacks of most chemotherapy are lack of target selectivity to tumor cells, and adverse drug reaction, which limit the treatment intensity and frequency. Herein, we synthesized the prodrug of triptolide (TP) coupled to vitamin E (VE) using dithiodiglycolic acid and co-dissolved with PEG2000- linoleic acid (MPEG200-LD) in ethanol. The PEGylated TP prodrug self-assembly nanoparticles (PTPPSN) were prepared via nanoprecipitation method. Besides, characterization, stability and in vitro release of the PEGylated nanometer prodrug were investigated. Furthermore, in vitro and in vivo antitumor efficacy of PTPPSN explored showed that the cytotoxicity of triptolide was significantly reduced in vitro preparation. However, in vitro and in vivo antitumor effect of PTPPSN was significantly improved compared to the original triptolide. In summary, the PEGylated nanoparticle successfully encapsulated triptolide yielded suitable cell microenvironment, and nanotechnology-related achievements. This study, therefore, provides a new method for antitumor research as well as an innovative technology for clinical treatment of malignant tumor.

Glutathionylation: a regulatory role of glutathione in physiological processes

Glutathione (γ-glutamyl-cysteinyl-glycine) is an intracellular thiol molecule and a potent antioxidant that participates in the toxic metabolism phase II biotransformation of xenobiotics. It can bind to a variety of proteins in a process known as glutathionylation. Protein glutathionylation is now recognised as one of important posttranslational regulatory mechanisms in cell and tissue physiology. Direct and indirect regulatory roles in physiological processes include glutathionylation of major transcriptional factors, eicosanoids, cytokines, and nitric oxide (NO). This review looks into these regulatory mechanisms through examples of glutathione regulation in apoptosis, vascularisation, metabolic processes, mitochondrial integrity, immune system, and neural physiology. The focus is on the physiological roles of glutathione beyond biotransformational metabolism.

GSTO1-1 plays a pro-inflammatory role in models of inflammation, colitis and obesity

Glutathione transferase Omega 1 (GSTO1-1) is an atypical GST reported to play a pro-inflammatory role in response to LPS. Here we show that genetic knockout of Gsto1 alters the response of mice to three distinct inflammatory disease models. GSTO1-1 deficiency ameliorates the inflammatory response stimulated by LPS and attenuates the inflammatory impact of a high fat diet on glucose tolerance and insulin resistance. In contrast, GSTO1-1 deficient mice show a more severe inflammatory response and increased escape of bacteria from the colon into the lymphatic system in a dextran sodium sulfate mediated model of inflammatory bowel disease. These responses are similar to those of TLR4 and MyD88 deficient mice in these models and confirm that GSTO1-1 is critical for a TLR4-like pro-inflammatory response in vivo. In wild-type mice, we show that a small molecule inhibitor that covalently binds in the active site of GSTO1-1 can be used to ameliorate the inflammatory response to LPS. Our findings demonstrate the potential therapeutic utility of GSTO1-1 inhibitors in the modulation of inflammation and suggest their possible application in the treatment of a range of inflammatory conditions.