GCLC Research Articles

Complementarity of two-dimensional gas chromatography and two-dimensional liquid chromatography for the analysis of depolymerised lignin

Two-dimensional gas chromatography (GC × GC) and two-dimensional liquid chromatography (LC × LC) are nowadays widely used in academia and industry due to their high separation power. However, as far as we know, the complementarity of these two techniques has not yet been thoroughly studied based on the analysis of the same sample. Therefore, this was undertaken here by analysing the liquid fraction obtained after depolymerising a natural waste – lignin – with GC × GC and off-line comprehensive LC × SFC (SFC: supercritical fluid chromatography). Using complementary techniques is also important for lignin valorisation, as thorough structural characterisation of the depolymerised product can aid with developing and improving valorisation processes. For the tentative identification, NIST library was used for GC × GC–MS results and MS-DIAL together with SIRIUS for LC × SFC-MS/MS data. This allowed to study which compounds are detectable with the different 2D methods but also to discuss the limitations of the data analysis processes. The previous knowledge that LC techniques are more suitable than GC × GC for the analysis of larger oligomers and other low volatility compounds was confirmed; however, it was seen that GC × GC enabled the analysis of smaller compounds, such as aliphatic alcohols and saturated compounds. Overall, the study demonstrates the complementarity of the two techniques but also draws attention to the different detectable compound groups and classifications that the two techniques can provide.

Effect of goose-derived adiponectin peptide gADP3 on LPS-induced inflammatory injury in goose liver

ABSTRACT 1. This study evaluated the effects and mechanisms of action of the peptide gADP3 on hepatic inflammatory injury induced by lipopolysaccharide (LPS). 2. Hepatic inflammatory injury was induced in geese by intraperitoneal injection of LPS and gADP3, and the adiponectin receptor agonist AdipoRon (positive control) was used for potential amelioration. Serum inflammatory factor levels, liver function-related biochemical indicators and oxidative stress-related biochemical parameters in the liver tissues were determined. The expression levels of adiponectin and its receptors, inflammation and oxidative stress-related genes and key signalling molecules involved in adiponectin, inflammation and oxidative stress signalling pathways in liver tissues were detected. 3. The peptide gADP3 alleviated inflammatory cell infiltration and hepatic inflammatory changes, reversed the decrease in serum albumin (ALB), total protein (TP), alanine aminotransferase (ALT) and aspartate aminotransferase (AST) content or activity induced by LPS and increased the activity of the antioxidant enzymes CAT (catalase), SOD (superoxide dismutase) and GSH-Px (glutathione peroxidase). 4. The peptide gADP3 upregulated the expression of antioxidant enzyme-related genes GCLC, HO-1 and NQO1 in liver tissues, decreased the levels of inflammatory factors like TNF-α, IL-1β, IL-6, IFN-γ and TGF-β and reduced mRNA expression levels of inflammatory-related genes TNF-α, IL-1β, iNOS and TGF-β. Additionally, it increased the mRNA and protein expression levels of adiponectin and its receptors, as well as key molecules in the adiponectin signalling pathway like AMPK and PPARα. In addition, gADP3 reversed the changes in mRNA or protein expression of inflammatory and oxidative stress signalling pathway-related genes P38MAPK, NF-κBP65, TLR4 and Nrf2 in liver tissues caused by LPS treatment. 5. In conclusion, goose-derived adiponectin peptide gADP3, similar to the adiponectin receptor agonist AdipoRon, attenuated LPS-induced hepatic inflammatory injury in geese.

Natural modulation of redox status throughout the ontogeny of Amazon frog Physalaemus ephippifer (Anura, Leptodactylidae)

During their development, amphibians undergo various physiological processes that may affect their susceptibility to environmental pollutants. Naturally occurring fluctuations caused by developmental events are often overlooked in ecotoxicological studies. Our aim is to investigate how biomarkers of oxidative stress are modulated at different stages of larval development in the Amazonian amphibian species, Physalaemus ephippifer. The premetamorphosis, prometamorphosis and metamorphic climax stages were used to analyze total antioxidant capacity (ACAP), glutathione S-transferase (GST) activity, lipid peroxidation (LPO) levels and the expression of genes nrf2, gst, gsr (glutathione reductase) and gclc (glycine-cysteine ligase, catalytic subunit). Although there was no difference in ACAP and the genes expression among the studied stages, individuals from the premetamorphosis and prometamorphosis showed higher GST activity than ones under the climax. LPO levels were highest in individuals from the metamorphic climax. The present study suggests that the oxidative status changes during ontogeny of P. ephippifer tadpoles, especially during the metamorphic climax, the most demanding developmental phase. Variations in the redox balance at different developmental stages may lead to a divergent response to pollution. Therefore, we recommend that studies using anuran larvae as biomonitors consider possible physiological differences during ontogeny in their respective analyses.

Polymorphism of antioxidant defense genes as a predictor of unfavorable neurological outcomes in preterm children

Currently, oxidative stress is considered as one of the most important factors in the pathogenesis of many pathological processes occurring in the newborn baby. Purpose. To establish the relationship of the polymorphism of genes, encoding antioxidant enzymes (glutamyl cysteine ligase, manganine superoxide dismutase) with unfavorable neurological outcomes in preterm children at various age periods. Material and methods. A prospective cohort continuous study included 151 preterm children, with a gestational age of 26–32 weeks and body weight of 590–1990 grams. Cord blood was sampled in children to determine allelic polymorphisms of 4 genetic markers: the SOD2 gene rs4880 (с.47C>Т, р.Ala16Val), the SOD2 gene rs1141718 (с.58T>C, р.Thr58Ile), the SOD2 gene rs11575993 (с.60С>Т, р.Leu58Phe), GCLC gene rs17883901 (с.–129 С>Т). The division of children into groups was carried out based on the assessment of neurological outcomes at the following control points: 1 control point — at the time of discharge from hospital, 2 control point — corrected age of 1 year of life, 3 control point — 4 years of life. Results. The cohort of children with unfavorable neurological outcomes was found to increase from 36.4 % at the time of hospital discharge to 70 % by the age of 4 years. Children who joined the cohort of children with unfavorable neurological outcomes at corrected age of 1 year of life were carriers of 47 CT of the gene of the mitochondrial superoxide dismutase (SOD2) rs4880, and those, attached by 4 years of age, were carriers of heterozygous 129 CT genotype of the gene of the catalytic subunit of glutamate cysteine ligase (GCLC) rs17883901 and 47 CT mitochondrial superoxide dismutase (SOD2) rs4880. Children with a favorable neurological outcome at corrected age of 1 year of life were more often diagnosed with homozygous 47 CC genotype of SOD2 rs4880 and 60 CC SOD2 rs11575993, and at the age of 4 years of life — with homozygous 129 CC genotype of GCLC rs17883901 gene and 47 TTSOD2 rs4880. Conclusion. The study of single nucleotide exchange in the antioxidant enzyme genes will establish the risk group of children exposed to free-radical injuries of CNS and begin neuroprotective therapy with the inclusion of antioxidant treatment.

Sulodexide protects endothelial cells against 4-hydroxynonenal-induced oxidative stress and glutathione-dependent redox imbalance by modulation of sestrin2/nuclear factor erythroid 2-related factor 2 pathway.

The lipid peroxidation product 4-hydroxynonenal (HNE) may be involved in vascular endothelial cell damage by induction of oxidative stress, apoptosis, and loss of redox homeostasis. There is evidence that stimulation of endothelial cells with 4-HNE induces the activation of the nuclear factor erythroid 2-related factor 2/Kelch-like ECH-associated protein 1 (Nrf2/Keap-1) pathway. Sestrin2 protein (SESN2) is one of the key regulators of Nrf2 and is involved in the cellular response to oxidative stress. However, the function of SESN2 in HNE-induced endothelial injury is not yet understood. Sulodexide (SDX) is a mixture of glycosaminoglycans used in clinical practice in the treatment of chronic venous and arterial diseases. While SDX has well-documented endothelial protective properties, little is known about its antioxidant effects. The aim of this study was to elucidate the molecular mechanisms activated by SDX in human umbilical endothelial cells (HUVECs) under HNE-induced oxidative stress. In this experimental model, we decided to evaluate the anti-apoptotic and antioxidant potential of SDX and its effect on the SESN2/Nrf2/GSH pathway. HUVECs were treated with 25 _M HNE or HNE combined with 0.5 LRU/mL SDX for 4 hours. Cell viability, apoptosis and intracellular reactive oxygen species (ROS) production were assessed by MTT assay and fluorescence microscopy. The expressions of Bax, cleaved caspase-3, Keap-1 and Nrf2 were determined by Western blot analysis. The intracellular concentrations of reduced glutathione (GSH) and oxidized glutathione (GSSG) were measured by colorimetric assay. SESN2, glutamate-cysteine ligase catalytic subunit (GCLc) and glutathione synthase (GSS) were assessed using ELISA. RT-qPCR was performed to detect Nrf2, GCLc and GSS mRNA levels. Transient Nrf2 silencing was obtained by short interfering RNA (siRNA). We have demonstrated that SDX can reduce the negative impact of HNE on HUVECs. SDX significantly protected HNE-treated HUVECs from apoptosis (p<0.001) and oxidative stress (p<0.001). SDX treatment significantly reduced Bax (p<0.05) and cleaved caspase-3 (p<0.01) expression. Co-administration of HNE and SDX increased GSH content (p<0.001) and GSH:GSSG ratio (p<0.001) as well as decreased SESN2 concentration (p<0.001) and Nrf2 (p<0.01), GCLc (p<0.05) and GSS (p<0.01) gene expression compared with the HNE group. Moreover, we revealed a negative correlation between SESN2 levels and GSH concentrations (p<0.001). Nrf2 silencing significantly decreased the effect of HNE and SDX on the induction of GCLc and GSS genes. SDX also significantly ameliorated the increase of nuclear Nrf2 in response to HNE (p<0.05). The results confirmed that SDX may protect against HNE-induced endothelial damage through its antioxidant effect and modulation of the SESN2/Nrf2/GSH signaling pathway.

Ganoderma lucidum Polysaccharides Ameliorate Acetaminophen-Induced Acute Liver Injury by Inhibiting Oxidative Stress and Apoptosis along the Nrf2 Pathway.

The excessive employment of acetaminophen (APAP) is capable of generating oxidative stress and apoptosis, which ultimately result in acute liver injury (ALI). Ganoderma lucidum polysaccharides (GLPs) exhibit hepatoprotective activity, yet the protective impact and potential mechanism of GLPs in relation to APAP-induced ALI remain ambiguous. The intention of this research was to scrutinize the effect of GLPs on APAP-induced ALI and to shed light on their potential mechanism. The results demonstrated that GLPs were capable of notably alleviating the oxidative stress triggered by APAP, as shown through a significant drop in the liver index, the activities of serum ALT and AST, and the amounts of ROS and MDA in liver tissue, along with an increase in the levels of SOD, GSH, and GSH-Px. Within these, the hepatoprotective activity at the high dose was the most conspicuous, and its therapeutic efficacy surpassed that of the positive drug (bifendate). The results of histopathological staining (HE) and apoptosis staining (TUNEL) indicated that GLPs could remarkably inhibit the necrosis of hepatocytes, the permeation of inflammatory cells, and the occurrence of apoptosis induced by APAP. Moreover, Western blot analysis manifested that GLPs enhanced the manifestation of Nrf2 and its subsequent HO-1, GCLC, and NQO1 proteins within the Nrf2 pathway. The results of qPCR also indicated that GLPs augmented the expression of antioxidant genes Nrf2, HO-1, GCLC, and NQO1. The results reveal that GLPs are able to set off the Nrf2 signaling path and attenuate ALI-related oxidative stress and apoptosis, which is a potential natural medicine for the therapy of APAP-induced liver injury.

Implications of GCLC in prognosis and immunity of lung adenocarcinoma and multi-omics regulation mechanisms

BackgroundFerroptosis is an iron-dependent type of regulated cell death, and has been implicated in lung adenocarcinoma (LUAD). Evidence has proved the key role of glutamate-cysteine ligase catalytic subunit (GCLC) in ferroptosis, but its role in LUAD remains unclear. Herein, we explored the implications of GCLC and relevant genes in LUAD prognosis and immunity as well as underlying molecular mechanisms.MethodsThis work gathered mRNA, miRNA, DNA methylation, somatic mutation and copy-number variation data from TCGA-LUAD. WGCNA was utilized for selecting GCLC-relevant genes, and a GCLC-relevant prognostic signature was built by uni- and multivariate-cox regression analyses. Immune compositions were estimated via CIBERSORT, and two immunotherapy cohorts of solid tumors were analyzed. Multi-omics regulatory mechanisms were finally assessed.ResultsOur results showed that GCLC was overexpressed in LUAD, and potentially resulted in undesirable survival. A prognostic model was generated, which owned accurate and independent performance in prognostication. GCLC, and relevant genes were notably connected with immune compositions and immune checkpoints. High GCLC expression was linked with better responses to anti-PD-L1 and anti-CTLA-4 treatment. Their possible DNA methylation sites were inferred, e.g., hypomethylation in cg19740353 might contribute to GCLC up-regulation. Frequent genetic mutations also affected their expression. Upstream transcription factors (E2F1/3/4, etc.), post-transcriptional regulation of miRNAs (hsa-mir-30c-1, etc.), lncRNAs (C8orf34-AS1, etc.), and IGF2BP1-mediated m6A modification were identified. It was also found NOP58-mediated SUMOylation post-translational modification.ConclusionsTogether, we show that GCLC and relevant genes exert crucial roles in LUAD prognosis and immunity, and their expression can be controlled by complex multi-omics mechanisms.

Hydrogen Sulfide Regulates Erectile Function through Stimulation of Antioxidant Defense in the Corpus Cavernosum

Hydrogen sulfide (H2S) is a gaseous cell signaling molecule with vasodilatory properties. Diminished H2S production has been implicated in the pathology of several cardiovascular diseases. H2S may protect against oxidative stress through scavenging of reactive oxygen species (ROS) or through stimulation of the Nrf2-mediated cellular antioxidant defense systems. We have previously demonstrated that mice fed a western diet for 12 weeks develop elevated penile ROS levels and impaired erectile function, which coincides with diminished corpus cavernosal expression of cystathionine γ-lyase (CSE), a major H2S producing enzyme. The objective of this study was to investigate the role of H2S in the regulation of erectile function and penile redox balance. We hypothesized that H2S levels will be positively associated with cellular antioxidant defense and erectile function. Young male C57Bl/6J mice (n = 120) were fed a control diet (CD) or western diet (WD) ad libitum for 18 weeks. For the final six weeks of the dietary intervention, half of the mice were switched to an equivalent diet containing the H2S pro-drug SG1002 at approximately 20 mg/kg/day. Separately, male CSE knockout mice (n = 26) and wild type (WT) littermate controls (n = 26) were fed a standard diet and studied at 6 months. Following the interventions, erectile function was assessed by measuring intracavernosal pressure (ICP) and mean arterial pressure (MAP) during cavernous nerve stimulation (1, 2, 4 V). In separate mice, penile in vivo ROS production was measured via microdialysis. Relative expression of 18 genes related to cellular antioxidant defense were assessed from naïve corpus cavernosum tissue by qRT-PCR. Group differences were determined by two-way ANOVA, with an α-level of 0.05. Erectile function was impaired in CSE KO mice (2V ICP/MAP - WT: 0.70±0.039 vs. KO: 0.55±0.043; p&lt;0.05). Erectile function was similarly impaired in the untreated WD-fed mice (CD: 0.68±0.035 vs. WD: 0.49±0.012; p&lt;0.05), while SG1002 induced a 54% functional restoration in WD mice (WD+SG1002: 0.59±0.019; p&lt;0.05). Penile production of the ROS hydrogen peroxide and superoxide were elevated in CSE KO mice (WT: 0.73±0.04 vs. KO: 1.19±0.13; p&lt;0.01). Penile ROS were also elevated in the WD mice (CD: 0.71±0.07 vs. WD: 1.09±0.15; p&lt;0.01), which were normalized by SG1002 treatment (WD+SG1002: 0.83±0.07; p&lt;0.01 vs. WD). Five antioxidant genes (Gclc, Gpx1, Gpx4, Prdx3, and Hmox1) that were stimulated by SG1002 treatment were also downregulated in CSE KO cavernosal tissues. Conversely, Txnip, a negative regulator of the thioredoxin antioxidant system was suppressed by SG1002 treatment and increased in CSE KO tissues. These results indicate that H2S is a key regulator of the cellular antioxidant systems and ROS balance in the penis, which may also regulate erectile function. Grant number K01DK115540 from the National Institutes of Health. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Vinpocetine attenuates methotrexate-induced hippocampal intoxication via Keap-1/Nrf2, NF-κB/AP-1, and apoptotic pathways in rats

Methotrexate (MTX) is an anti-folate chemotherapeutic commonly used to treat cancer and autoimmune diseases. Despite its widespread clinical use, MTX has been linked to serious neurotoxicity side effects. Vinpocetine (VNP) has been widely used clinically to treat many neurological conditions. This study was conducted to study the potential neuroprotective effects of VNP against MTX hippocampal intoxication in rats. Thirty-two rats were randomly allocated into 4 groups: (I) control (Vehicle); (II) VNP-treated group (20 mg/kg/day, p.o); (III) MTX-control (20 mg/kg/once, i.p.) group; and (IV) the VNP + MTX group. VNP was administered orally for 10 days, during which MTX was given intraperitoneally once at the end of day 5. Our data indicated that VNP administration significantly improved MTX-induced neuronal cell death, odema, vacuolation and degeneration. VNP attenuated oxidative injury mediated by significant upregulation of the Nrf2, HO-1, and GCLC genes, while the Keap-1 mRNA expression downregulated. Moreover, VNP suppressed cytokines release mediated by increasing IκB expression level while it caused a marked downregulation in NF-κB and AP-1 (C-FOS and C-JUN) levels. Additionally, VNP attenuated apoptosis by reducing hippocampal Bax levels while increasing Bcl2 levels in MTX-intoxicated rats. In conclusion, our results suggested that VNP significantly attenuated MTX hippocampal intoxication by regulating Keap-1/Nrf2, NF-κB/AP-1, and apoptosis signaling in these effects.

Glutathione Supplementation Prevents Neonatal Parenteral Nutrition-Induced Short- and Long-Term Epigenetic and Transcriptional Disruptions of Hepatic H2O2 Metabolism in Guinea Pigs.

The parenteral nutrition (PN) received by premature newborns is contaminated with peroxides that induce global DNA hypermethylation via oxidative stress. Exposure to peroxides could be an important factor in the induction of chronic diseases such as those observed in adults who were born preterm. As endogenous H2O2 is a major regulator of glucose-lipid metabolism, our hypothesis was that early exposure to PN induces permanent epigenetic changes in H2O2 metabolism. Three-day-old guinea pigs were fed orally (ON), PN or glutathione-enriched PN (PN+GSSG). GSSG promotes endogenous peroxide detoxification. After 4 days, half the animals were sacrificed, and the other half were fed ON until 16 weeks of age. The liver was harvested. DNA methylation and mRNA levels were determined for the SOD2, GPx1, GCLC, GSase, Nrf2 and Keap1 genes. PN induced GPx1 hypermethylation and decreased GPx1, GCLC and GSase mRNA. These findings were not observed in PN+GSSG. PN+GSSG induced Nrf2 hypomethylation and increased Nrf2 and SOD2 mRNA. These observations were independent of age. In conclusion, in neonatal guinea pigs, PN induces epigenetic changes, affecting the expression of H2O2 metabolism genes. These changes persist for at least 15 weeks after PN. This disruption may signify a permanent reduction in the capacity to detoxify peroxides.

Studying the role of GCLC gene polymorphisms in predicting the clinical course of acute alcoholic pancreatitis

Studying the role of GCLC gene polymorphisms in predicting the clinical course of acute alcoholic pancreatitis

Diet Supplementation with Prinsepiae Nux Extract in Broiler Chickens: Its Effect on Growth Performance and Expression of Antioxidant, Pro-Inflammatory, and Heat Shock Protein Genes.

Heat stress significantly undermines the poultry industry by escalating rates of morbidity and mortality and impairing growth performance. Our recent findings indicate that Prinsepiae Nux extract (PNE) effectively stimulates the Nrf2 signaling pathway, a vital element in cellular antioxidant stress responses. This study further explores the prospective benefits of supplementing PNE into poultry feed to enhance broiler growth in heat-stressed conditions. An Nrf2-luciferase reporter assay was developed in a chicken fibroblast cell line, demonstrating that PNE induces Nrf2 activity in a concentration-dependent manner. Real-time RT-PCR results showed that PNE intensifies the expression of Nrf2-responsive targets such as Ho1 and Nqo1 in chicken fibroblasts. A total of 160 one-day-old Arbor Acres broiler chicks were randomly assigned into four groups, each receiving a basal diet supplemented with either 0% (control), 0.1% PNE, 1% PNE, or commercial electrolyte for 35 days. Broilers were raised in an environment where the ambient temperature exceeded 30 °C for approximately seven hours each day, fluctuating between 26 and 34 °C, which is known to induce mild heat stress. The findings reveal that a 1% PNE supplement led to a significant decrease in the feed conversion ratio (FCR) compared to the control group. Moreover, chickens supplemented with 1% PNE exhibited a substantial increase in hepatic mRNA expression of antioxidant genes, such as Nqo1, Gclc, Sod2, Cat, and heat shock protein-related genes including Hsp90 and Hsf1, and a decrease in pro-inflammatory cytokine genes Il-6 and Il-1β. Consequently, PNE holds potential as a feed supplement to strengthen the antioxidant defenses of broilers and build heat stress resilience in the poultry industry.

Involvement of reactive oxygen species (ROS) in the hepatopancreatic cytotoxicity, oxidative stress, and apoptosis induced by microcystin-LR in Eriocheir sinensis

There is limited knowledge about the toxicity of Microcystin-LR (MC-LR) in crustaceans, despite its high toxicity to aquatic organisms. This research aimed to explore the effects of MC-LR on cytotoxicity, oxidative stress, and apoptosis in the hepatopancreas of Eriocheir sinensis, as well as elucidate the involvement of reactive oxygen species (ROS) and potential mechanisms of toxicity. In vivo and in vitro exposures of crabs to MC-LR and N-acetylcysteine (NAC) were performed, followed by assessments of cell morphology, viability, tissue pathology, biochemical indicators, gene expression, and hepatopancreatic transcriptome. Results revealed that MC-LR facilitated the entry of the MC-LR transporter oatp3a into hepatopancreatic cells, leading to upregulated expression of phase I detoxification enzyme genes (cyp4c, cyp2e1, and cyp3) and downregulated the phase II enzyme genes (gst1, gpx, gsr2, gclc, and nqo1), resulting in increased ROS levels and cytotoxic effects. MC-LR exhibited cytotoxicity, reducing cell viability and inducing abnormal nuclear morphology with a 48 h-IC50 value of approximately 120 μm. MC-LR exposure caused biochemical changes indicative of oxidative stress damage and evident hepatopancreatic lesions. Additionally, MC-LR exposure regulated the levels of bax and bcl-2 expression, activating caspase 3 and 6 to induce cell apoptosis. Intervention with NAC attenuated MC-LR-induced ROS production and associated toxic effects. Transcriptome analysis revealed enrichment of differentially expressed genes in pathways related to cytochrome P450-mediated xenobiotic metabolism and the FoxO signaling pathway. These findings shed light on the potential mechanisms underlying MC-LR toxicity and provide valuable references for further research and conservation efforts regarding the health of aquatic animals.

Assessment of oxidative stress biomarkers in the threatened annual killifish Austrolebias charrua exposed to Roundup

This study aimed to analyze the toxic effects of Roundup Transorb® on the endangered Neotropical annual killifish Austrolebias charrua through the assessment of molecular and biochemical biomarkers. The fish were collected in temporary ponds and exposed to environmentally realistic concentrations of the herbicide (5 mg.L‐1 for 96 h). The production of ROS, lipid peroxidation, DNA damage, and membrane fluidity were evaluated in the blood cells by flow cytometry. The mRNA expression of the antioxidant-related genes sod2, cat, gstα, atp1a1, gclc, and ucp1 across the brain, liver, and gills was quantified. The acute exposure of annual killifish to Roundup significantly increased ROS production, lipid peroxidation, and DNA damage in their erythrocytes. Likewise, Roundup Transorb® decreased membrane fluidity in the blood cells of the exposed fish. Gene expression analysis revealed that Roundup exposure alters the relative expression of genes associated with oxidative stress and antioxidant defense. Our results give rise to new insights into adaptive mechanisms of A. charrua in response to Roundup. Since Brazilian annual killifishes strongly risk extinction, this study paves the way for developing novel biotechnologies applied to environmental monitoring and aquatic toxicology assessment.

Changes in the expression of oxidative stress genes in toxic hepatitis of different etiologies and their correction

The study aims to study of changes in transcriptional activity of oxidative stress genes in acute toxic hepatitis. Materials and methods. The study material was white mongrel male rats weighing 180-200 grams. The studied toxicants were: carbon tetrachloride, ethanol, acetaminophen. As hepatoprotectors were introduced: oxymethyluracil, ademethionine and ethylmethylhydroxypyridine succinate. RNA was isolated, which was subjected to reverse transcription. RT-PCR was performed using a real-time PCR system in the presence of SYBR Green. GAPDH was used as a normalized control. The expression of the studied genes was evaluated by PCR analysis using pre-selected primers. Statistical significance was checked using IBM SPSS Statistics software. Results. In comparison of experimental groups, statistically significant differences were found in the level of expression of the CASP7 gene. Transcriptional activity of the CHEK gene (k=11.25; p=0.024). The GCLC gene (k=21.70; p=0.001) reached its minimum value of -3.6 [-3.72; -3.32] in the Mexidol group. The multiplicity of expression of the GSTM1 gene (k=15.54; p=0.004) had the highest value -0.14 [-1.11; 1] in the group that did not receive TCM. The NQO1 gene achieved its statistical significance in a 72-hour experiment (p=0.005). Statistical analysis of the RIPK gene showed significant differences. The expression level of the GSTP1 gene (k=10.39; p=0.034) reached its maximum value in the untreated group of 0.03 [-0.74; 0.48]. Expression of the NFE2L2 gene with acetaminophen administration showed the following results (k=13.64; p=0.009). Glutathione activity (k=10.29; p=0.036) reached its minimum value in the group receiving Mexidol -1.6 [-1.7; -1.29]. The multiplicity of superoxide dismutase expression showed statistical significance (p=0.003). Conclusions. Markers of the clinical course, prognosis and outcomes of toxic hepatitis were found. These data make it possible to determine the severity of the disease at the stage of early molecular response, when active clinical symptoms have not yet developed, which makes it possible to prescribe targeted therapy and adjust treatment tactics.

Применение молекулярно-генетических предикторов и машинного обучения в оценке токсичности химических веществ

Toxic hepatites is an important public health issue in Russia. They have diverse etiologies, including industrial toxins, drugs, and ethanol, leading to significant differences in pathogenesis at the molecular and genetic level. This study aimed to analyze genes involved in the response to toxic liver injury of different origins and to establish a model to predict the etiology of toxic hepatitis. To model acute toxic hepatitis, outbred white male rats weighing 180–200 g were used. They were divided into four groups: control group, tetrachloromethane group, paracetamol group, and ethanol group. 24 h and 72 h after toxicant administration rats were anesthetized and mRNA levels of Chek1, Gclc, Gstm1, Gstp1, Gstt1, Nfe2l2, Nqo1, and Ripk1 genes in liver homogenate were studied. Analysis of the expression of these genes showed that the expression profile varies depending on the etiology of toxic hepatitis. In tetrachloromethane poisoning, there was a marked increase in gene expression of Nqo1 (p?=?0.001), Gstm1 (p?=?0.037), and a decrease in gene expression of Nfe2l2 (p?=?0.004), Ripk1 (p?=?0.004). However, liver exposure to paracetamol and its metabolites resulted in decreased Gstm1 gene expression (p?=?0.001) and increased Nfe2l2 (p?=?0.009), Gclc (p?=?0.001), and Chek1 (p?=?0.011) gene expression. No significant changes in the expression of these genes are found in alcohol intoxication. A model was constructed to predict the etiology of toxic hepatitis on the basis of gene expression indices. Keywords: acute toxic hepatitis, paracetamol, tetrachloromethane, ethanol, gene expression.

In Vitro Comparison of Shear Bond Strength (SBS) of Orthodontic Brackets Bonded with 4 Adhesive Materials and Debonded at Different Time Intervals

Aim: This study compared the SBS of orthodontic brackets that were bonded on buccal enamel of premolars either with composite resins or with RMGI after 2 and 24 hours and after 4 weeks. Methods: 220 premolars extracted due to orthodontic reasons were divided in four groups: In 2 groups brackets were bonded with composite resins: GC connect and Transbond XT-3M, and in 2 groups with RMGI: GC FUJI LC Capsule and GC Automix. Each group was divided to 3 different time intervals: 2H, 24H and 4 weeks. At each time interval the brackets were tested using a constant load of 2.5 N and the shear bond strength recorded as stress at maximal load was recorded in MPa. Results: Our study shows that the RMGI glue GC LC Capsule had the highest shear bond strength after 2H (11.6 MPa) and after 24H (8.5 MPa) with significance of P&lt;0.001 Conclusions: As shown also in previous studies GC Fuji LC Capsule should be considered as a safe material for bracket bonding and caries protection during orthodontic treatment, due to fluoride release around the bracket.

AMPK-Mediated Phosphorylation of Nrf2 at S374/S408/S433 Favors Its βTrCP2-Mediated Degradation in KEAP1-Deficient Cells.

Nrf2 is a transcription factor facilitating cells' resilience against redox and various other forms of stress. In the absence of stressors, KEAP1 and/or βTrCP mediate the ubiquitination of Nrf2 and prevent Nrf2-dependent gene expression and detoxification. AMPK regulates cellular energy homeostasis and redox balance. Previous studies indicated a potential Nrf2-AMPK cooperativity. In line with this, our lab had previously identified three AMPK-dependent phosphorylation sites (S374/408/433) in Nrf2. Given their localization in or near the Neh6 domain, known to regulate βTrCP-mediated degradation, we examined whether they may influence the βTrCP-driven degradation of Nrf2. By employing expression plasmids for WT and triple mutant (TM)-Nrf2 (Nrf2S374/408/433→A), (co)immunoprecipitation, proximity ligation, protein half-life, knockdown, ubiquitination experiments, and qPCR in Keap1-null mouse embryonic fibroblasts, we show that TM-Nrf2S→A374/408/433 had enhanced stability due to impeded interaction with βTrCP2 and reduced ubiquitination in comparison to WT-Nrf2. In addition, TM-Nrf2 elicited higher expression of the Nrf2 target gene Gclc, potentiated in the presence of a pharmacological AMPK activator. Overall, we propose that AMPK-dependent phospho-sites of Nrf2 can favor its βTrCP2-mediated degradation and dampen the extent of Nrf2 target gene expression. Therefore, targeting AMPK might be able to diminish Nrf2-mediated responses in cells with overactive Nrf2 due to KEAP1 deficiency.

Molecular mechanisms of hepatoprotective effect of tectorigenin against ANIT-induced cholestatic liver injury: Role of FXR and Nrf2 pathways.

Cholestatic liver injury is caused by toxic action or allergic reaction, resulting in abnormality of bile formation and excretion. Few effective therapies have become available for the treatment of cholestasis. Herein, we found that tectorigenin (TG), a natural isoflavone, showed definite protective effects on alpha-naphthylisothiocyanate (ANIT)-induced cholestatic liver injury, significantly reversing the abnormality of plasma alanine/aspartate aminotransferase, total/direct bilirubin and alkaline phosphatase, as well as hepatic reactive oxygen species, catalase and superoxide dismutase. Importantly, the targeted metabolomic determination found that BA homeostasis could be well maintained in TG-treated cholestatic mice, especially the levels of glycocholic acid, tauromuricholic acid, taurocholic acid, taurolithocholic acid, tauroursodeoxycholic acid and taurodeoxycholic acid. Overall, primary/secondary and amidated/unamidated bile acid (BA) levels were significantly altered upon ANIT stimulation but could be restored by TG intervention to certain extents. In addition, TG boosted the expression of farnesoid x receptor (FXR), which in turn upregulated multidrug resistance protein 2 (MRP2) and bile salt export pump (BSEP) to accelerate the excretion of BA. Meanwhile, TG enhanced the expression of Nrf2 and its upstream genes PI3K/Akt and downstream target genes HO-1, NQO1, GCLC and GCLM to strengthen the antioxidant capacity. Taken together, TG plays a vital role in maintaining BA homeostasis and ameliorating cholestatic liver injury through regulating FXR-mediated BA efflux and Nrf2-mediated antioxidative pathways.

Differentially Expressed Genes Regulating Glutathione Metabolism, Protein-Folding, and Unfolded Protein Response in Pancreatic β-Cells in Type 2 Diabetes Mellitus.

Impaired redox homeostasis in the endoplasmic reticulum (ER) may contribute to proinsulin misfolding and thus to activate the unfolded protein response (UPR) and apoptotic pathways, culminating in pancreatic β-cell loss and type 2 diabetes (T2D). The present study was designed to identify differentially expressed genes (DEGs) encoding enzymes for glutathione metabolism and their impact on the expression levels of genes regulating protein folding and UPR in β-cells of T2D patients. The GEO transcriptome datasets of β-cells of diabetics and non-diabetics, GSE20966 and GSE81608, were analyzed for 142 genes of interest using limma and GREIN software, respectively. Diabetic β-cells showed dataset-specific patterns of DEGs (FDR ≤ 0.05) implicated in the regulation of glutathione metabolism (ANPEP, PGD, IDH2, and CTH), protein-folding (HSP90AB1, HSP90AA1, HSPA1B, HSPA8, BAG3, NDC1, NUP160, RLN1, and RPS19BP1), and unfolded protein response (CREB3L4, ERP27, and BID). The GCLC gene, encoding the catalytic subunit of glutamate-cysteine ligase, the first rate-limiting enzyme of glutathione biosynthesis, was moderately down-regulated in diabetic β-cells from both datasets (p ≤ 0.05). Regression analysis established that genes involved in the de novo synthesis of glutathione, GCLC, GCLM, and GSS affect the expression levels of genes encoding molecular chaperones and those involved in the UPR pathway. This study showed for the first time that diabetic β-cells exhibit alterations in the expression of genes regulating glutathione metabolism, protein-folding, and UPR and provided evidence for the molecular crosstalk between impaired redox homeostasis and abnormal protein folding, underlying ER stress in type 2 diabetes.