Early Neurotoxic Effects of Inorganic Arsenic Modulate Cortical GSH Levels Associated With the Activation of the Nrf2 and NFκB Pathways, Expression of Amino Acid Transporters and NMDA Receptors and the Production of Hydrogen Sulfide

Fluoride Exposure Increases the Activity of the Cystine/Glutamate Exchanger in Glia Cells

Fluoride exposure in drinking water has been widely related to impairment of cognitive function. Even though this ion has been described as neurotoxic for more than two decades, the molecular mechanisms of fluoride neurotoxicity are not fully understood, however, increasing evidence suggests that glial cells are the site of early injury in fluoride neurotoxicity. Nevertheless, a convergence point of many studies is the effect on glutamatergic neurotransmission and the generation of reactive oxygen species. In this context, we evaluated here the expression and regulation of the cystine/glutamate exchanger upon fluoride exposure since this transporter is in the interface between excitotoxicity and the antioxidant response. We demonstrate here the functional expression of the cystine /glutamate exchanger in both the U373 human glioblastoma cells and chick cerebellar Bergmann glia cells. Using a [3H]-L-Glutamate uptake assay, we demonstrate that fluoride increases the activity of the exchanger in a time and dose-dependent manner. This augmentation is mitigated by the antioxidant Trolox. To gain insight into fluoride neurotoxicity mechanisms, we evaluated its effect on human antigen R, a RNA binding protein, that binds to the 3'-UTR region of exchanger mRNA increasing its half time life. An increase in human antigen R protein was recorded after a 6 h fluoride exposure, suggesting that this ion regulates the exchanger through this RNA-binding protein. Furthermore, we show that fluoride exposure increases both the exchanger and human antigen R mRNAs half-life. These results provide insights into fluoride neurotoxicity mechanisms and support the notion of a central role of glial cells in neuronal glutamatergic transmission disruption that leads to neuronal cell death.

Chronic Exposure to Arsenic and Fluoride Starting at Gestation Alters Liver Mitochondrial Protein Expression and Induces Early Onset of Liver Fibrosis in Male Mouse Offspring

The presence of arsenic (As) and fluoride (F-) in drinking water is of concern due to the enormous number of individuals exposed to this condition worldwide. Studies in cultured cells and animal models have shown that As- or F-induced hepatotoxicity is primarily associated with redox disturbance and altered mitochondrial homeostasis. To explore the hepatotoxic effects of chronic combined exposure to As and F- in drinking water, pregnant CD-1 mice were exposed to 2 mg/L As (sodium arsenite) and/or 25 mg/L F- (sodium fluoride). The male offspring continued the exposure treatment up to 30 (P30) or 90 (P90) postnatal days. GSH levels, cysteine synthesis enzyme activities, and cysteine transporter levels were investigated in liver homogenates, as well as the expression of biomarkers of ferroptosis and mitochondrial biogenesis-related proteins. Serum transaminase levels and Hematoxylin-Eosin and Masson trichrome-stained liver tissue slices were examined. Combined exposure at P30 significantly reduced GSH levels and the mitochondrial transcription factor A (TFAM) expression while increasing lipid peroxidation, free Fe 2+, p53 expression, and serum ALT activity. At P90, the upregulation of cysteine uptake and synthesis was associated with a recovery of GSH levels. Nevertheless, the downregulation of TFAM continued and was now associated with a downstream inhibition of the expression of MT-CO2 and reduced levels of mtDNA and fibrotic liver damage. Our experimental approach using human-relevant doses gives evidence of the increased risk for early liver damage associated with elevated levels of As and F- in the diet during intrauterine and postnatal period.

Acute anticonvulsant effects of dapsone on PTZ- and MES-induced seizures in mice: NLRP3 inflammasome inhibition and Nrf2/HO-1 pathway preservation

BACKGROUND

Epilepsy, a neurological disorder characterized by recurrent seizures, presents considerable difficulties in treatment, particularly when dealing with drug-resistant cases. Dapsone, recognized for its anti-inflammatory properties, holds promise as a potential therapeutic option. However, its effectiveness in epilepsy requires further investigation. The aim of this study is to explore the effects of dapsone on seizure activity and neuroinflammation, particularly through the nuclear factor erythroid-2-related factor (Nrf2)/ Heme Oxygenase 1 (HO-1) and NOD-like receptor family pyrin domain-containing 3 (NLRP3) pathways, to better understand its therapeutic potential.

METHODS

To evaluate the effects of dapsone, two seizure models were utilized in mice: pentylenetetrazole (PTZ)-induced clonic seizures and maximal electroshock (MES)-induced generalized tonic-clonic seizures (GTCS) in mice. The impact of dapsone on neuroinflammatory markers and oxidative stress pathways, specifically Nrf2/HO-1 and NLRP3, as well as interleukin-1β (IL-1β), IL-8, and IL-18, was assessed using Western blotting and ELISA techniques.

RESULTS

In this study, dapsone (2, 5, 10, and 20 mg/kg, ip) showcased a significant increase in clonic seizure threshold following intravenous infusion of PTZ. Notably, doses of 5, 10, and 20 mg/kg exhibited increased latency and decreased the number of seizures. Additionally, dapsone at 10 and 20 mg/kg prevented the incidence of GTCS and subsequent mortality in the MES model. Furthermore, Dapsone demonstrated modulation of Nrf2/ HO-1 and NLRP3 IL-1 β/IL-18 pathways.

CONCLUSION

This study highlights the therapeutic potential of dapsone in epilepsy, emphasizing the involvement of Nrf2/HO-1 and NLRP3 pathways. These findings provide a foundation for future clinical research aimed at developing dapsone-based therapies for drug-resistant epilepsy.

LINC00942 Alleviates NaAsO2-induced Apoptosis by Promoting GSH Synthesis Through Targeting miR-214-5p

The mechanism of arsenic-induced liver toxicity is not fully understood. This study aimed to investigate the role of LINC00942 in arsenic-induced hepatotoxicity by regulating miR-214-5p. As the exposure dose of NaAsO2 gradually increases, cell viability, intracellular GSH content, ΔΨm, and the protein levels of GCLC and GCLM were reduced significantly. Apoptosis rate, ROS, and expression of apoptosis-related and NF-κB pathway proteins increased. The expression of LINC00942 was increased, while the expression of miR-214-5p was decreased. After suppressing LINC00942 levels, NaAsO2 exposure further decreased cell viability, intracellular GSH content, ΔΨm, GCLC protein, and miR-214-5p expression. The apoptosis rate, ROS, and apoptosis-related and NF-κB pathway proteins further increased. miR-214-5p is targeted and negatively regulated by LINC00942. After miR-214-5p was overexpressed, NaAsO2 further decreased cell viability, intracellular GSH content, ΔΨm, and GCLC protein expression compared to NaAsO2 exposure. The apoptosis rate, ROS, apoptosis-related and NF-κB pathway proteins p65, and IKKβ were higher than those exposed to NaAsO2. LINC00942 inhibitor along with miR-214-5p inhibitor combined with NaAsO2 treatment resulted in increased cell viability, GSH, Bcl-2, and GCLC protein expression and decreased apoptosis rate, apoptosis related, p65, IKKβ protein, and ΔΨm, as compared to the combined NaAsO2 and si LINC00942 group. NaAsO2 exposure induces oxidative damage and apoptosis in LX-2 cells by activating NF-κB and inhibiting GSH synthesis. During this process, the expression level of LINC00942 increases, targeting to reduce the level of miR-214-5p, then weakening the effect of NaAsO2 on NF-κB, thereby alleviating cellular oxidative damage and playing a protective role.

Association of Prenatal Dietary Toxicants and Inorganic Arsenic Exposure with Children's Emotional and Behavioral Problems: ECLIPSES Study

Prenatal exposure to dietary toxicants is linked to neurocognitive issues, but its effect on early emotional and behavioral development in children is less clear. To explore the relationship between prenatal intake of As, iAs, Cd, MeHg, Pb, PCDD/Fs, DL-PCBs, and NDL-PCBs and emotional and behavioral issues in four-year-old children. This study included 192 mother-child pairs from the ECLIPSES study, assessing prenatal dietary toxicant exposure through a food-frequency questionnaire and Catalan Food Safety Agency data. Children's emotional and behavioral scores were evaluated using the Child Behavior Checklist for ages 1.5-5 years. Multivariable regression and logistic models were used, focusing on iAs after finding significant preliminary associations. Increased prenatal dietary intake of iAs was associated with internalizing, externalizing, and attention-deficit/hyperactivity problems. Higher iAs levels (>4.16 μg/day) significantly increased the risk of total problems (OR = 2.94) and specific issues like anxious/depressed (OR = 4.88), anxiety (OR = 3.27), and oppositional defiant problems (OR = 4.30). High iAs consumption correlated with the intake of meat, eggs, cereals, tubers, fruits, and pulses Prenatal dietary iAs exposure is associated with various emotional and behavioral problems in children. Monitoring and reducing iAs levels in food are crucial for public health.

The role of thioredoxin and glutathione systems in arsenic-induced liver injury in rats under glutathione depletion

Antioxidant systems like thioredoxin (Trx) and glutaredoxin (Grx) maintain oxidative stress balance. These systems have cross-talk supported by some in vitro studies. We investigated the underlying mechanisms of arsenic-induced liver injury in glutathione-deficient rats and whether there was any cross-talk between the Trx and Grx systems. The rats in arsenic-treated groups were administered with sodium arsenite (10, 20 mg/kg b w/d) for four weeks. In buthionine sulfoximine (BSO, an inhibitor of GSH) and 20 mg/kg arsenic combined groups, rats were injected with 2 mmol/kg BSO intraperitoneally twice per week. BSO exacerbated arsenic-induced liver injury by increasing arsenic accumulation in urine, serum, and liver while decreasing glutathione activity and resulting in upregulated mRNA expression of the Trx system and downregulation of Grx mRNA expression. The impact of Trx lasted longer than that of the Grx. The Trx system remained highly expressed, while GSH, Grx1, and Grx2 levels were decreased. The inhibitory effect of only BSO treatment on Grx1 and Grx2 was not pronounced. However, the combined impact of arsenic and BSO upregulated Trx expression, primarily related to further reduction of GSH. As a result, the suppressed Grxs were protected by the upregulated Trxs, which serve as a backup antioxidant defense system in the liver.

Evaluation of arsenic metabolism and tight junction injury after exposure to arsenite and monomethylarsonous acid using a rat in vitro blood-Brain barrier model

Experimental verification of impairment to cognitive abilities and cognitive dysfunction resulting from inorganic arsenic (iAs) exposure in children and adults is challenging. This study aimed to elucidate the effects of arsenite (iAsIII; 1, 10 and 20 μM) or monomethylarsonous acid (MMAIII; 0.1, 1 and 2 μM) exposure on arsenic metabolism and tight junction (TJ) function in the blood-brain barrier (BBB) using a rat in vitro-BBB model. The results showed that a small percentage (~15%) of iAsIII was oxidized or methylated within the BBB, suggesting the persistence of toxicity as iAsIII. Approximately 65% of MMAIII was converted to low-toxicity monomethylarsonic acid and dimethylarsenic acid via oxidation and methylation. Therefore, it is estimated that MMAIII causes TJ injury to the BBB at approximately 35% of the unconverted level. TJ injury of BBB after iAsIII or MMAIII exposure could be significantly assessed from decreased expression of claudin-5 and decreased transepithelial electrical resistance values. TJ injury in BBB was found to be significantly affected by MMAIII than iAsIII. Relatedly, the penetration rate in the BBB by 24 h of exposure was higher for MMAIII (53.1% ± 2.72%) than for iAsIII (43.3% ± 0.71%) (p < 0.01). Exposure to iAsIII or MMAIII induced an antioxidant stress response, with concentration-dependent increases in the expression of nuclear factor-erythroid 2-related factor 2 in astrocytes and heme oxygenase-1 in a group of vascular endothelial cells and pericytes, respectively. This study found that TJ injury at the BBB is closely related to the chemical form and species of arsenic; we believe that elucidation of methylation in the brain is essential to verify the impairment of cognitive abilities and cognitive dysfunction caused by iAs exposure.

Chronic exposure to inorganic arsenic and fluoride induces redox imbalance, inhibits the transsulfuration pathway, and alters glutamate receptor expression in the brain, resulting in memory impairment in adult male mouse offspring

Exposure to toxic elements in drinking water, such as arsenic (As) and fluoride (F), starts at gestation and has been associated with memory and learning deficits in children. Studies in which rodents underwent mechanistic single exposure to As or F showed that the neurotoxic effects are associated with their capacity to disrupt redox balance, mainly by diminishing glutathione (GSH) levels, altering glutamate disposal, and altering glutamate receptor expression, which disrupts synaptic transmission. Elevated levels of As and F are common in groundwater worldwide. To explore the neurotoxicity of chronic exposure to As and F in drinking water, pregnant CD-1 mice were exposed to 2 mg/L As (sodium arsenite) and 25 mg/L F (sodium fluoride) alone or in combination. The male litter continued to receive exposure up to 30 or 90 days after birth. The effects of chronic exposure on GSH levels, transsulfuration pathway enzymatic activity, expression of cysteine/cystine transporters, glutamate transporters, and ionotropic glutamate receptor subunits as well as behavioral performance in the object recognition memory task were assessed. Combined exposure resulted in a significant reduction in GSH levels in the cortex and hippocampus at different times, decreased transsulfuration pathway enzyme activity, as well as diminished xCT protein expression. Altered glutamate receptor expression in the cortex and hippocampus and decreased transaminase enzyme activity were observed. These molecular alterations were associated with memory impairment in the object recognition task, which relies on these brain regions.

Arsenic induced autophagy-dependent apoptosis in hippocampal neurons via AMPK/mTOR signaling pathway

Arsenic contamination of groundwater remains a serious public health problem worldwide. Arsenic-induced neurotoxicity receives increasing attention, however, the mechanism remains unclear. Hippocampal neuronal death is regarded as the main event of arsenic-induced cognitive dysfunction. Mitochondria lesion is closely related to cell death, however, the effects of arsenic on PGAM5-regulated mitochondrial dynamics has not been documented. Crosstalk between autophagy and apoptosis is complicated and autophagy has a dual role in the apoptosis pathways in neuronal cells. In this study, arsenic exposure resulted in mitochondrial PGAM5 activation and subsequent activation of apoptosis and AMPK-mTOR dependent autophagy. Intervention by autophagy activator Rapamycin or inhibitor 3-MA, both targeting at mTOR, accordingly induced activation or inhibition of apoptosis. Intervention by MK-3903 or dorsomorphin, activator or inhibitor of AMPK, received similar results. Our findings suggested that arsenic-induced PGAM5 activation played a role in AMPK-mTOR dependent autophagy and arsenic induced autophagy-dependent apoptosis in hippocampal neurons via AMPK/mTOR signaling pathway.

Hydrogen Sulfide (H2S) Signaling as a Protective Mechanism against Endogenous and Exogenous Neurotoxicants

In view of the significant role of H₂S in brain functioning, it is proposed that H₂S may also possess protective effects against adverse effects of neurotoxicants. Therefore, the objective of the present review is to discuss the neuroprotective effects of H₂S against toxicity of a wide spectrum of endogenous and exogenous agents involved in the pathogenesis of neurological diseases as etiological factors or key players in disease pathogenesis. Generally, the existing data demonstrate that H₂S possesses neuroprotective effects upon exposure to endogenous (amyloid β, glucose, and advanced-glycation end-products, homocysteine, lipopolysaccharide, and ammonia) and exogenous (alcohol, formaldehyde, acrylonitrile, metals, 6-hydroxydopamine, as well as 1-methyl-4-phenyl- 1,2,3,6- tetrahydropyridine (MPTP) and its metabolite 1-methyl-4-phenyl pyridine ion (MPP)) neurotoxicants. On the one hand, neuroprotective effects are mediated by S-sulfhydration of key regulators of antioxidant (Sirt1, Nrf2) and inflammatory response (NF-κB), resulting in the modulation of the downstream signaling, such as SIRT1/TORC1/CREB/BDNF-TrkB, Nrf2/ARE/HO-1, or other pathways. On the other hand, H₂S appears to possess a direct detoxicative effect by binding endogenous (ROS, AGEs, Aβ) and exogenous (MeHg) neurotoxicants, thus reducing their toxicity. Moreover, the alteration of H₂S metabolism through the inhibition of H₂S-synthetizing enzymes in the brain (CBS, 3-MST) may be considered a significant mechanism of neurotoxicity. Taken together, the existing data indicate that the modulation of cerebral H₂S metabolism may be used as a neuroprotective strategy to counteract neurotoxicity of a wide spectrum of endogenous and exogenous neurotoxicants associated with neurodegeneration (Alzheimer's and Parkinson's disease), fetal alcohol syndrome, hepatic encephalopathy, environmental neurotoxicant exposure, etc. In this particular case, modulation of H₂S-synthetizing enzymes or the use of H₂S-releasing drugs should be considered as the potential tools, although the particular efficiency and safety of such interventions are to be addressed in further studies.

NO, CO and H2S: A Trinacrium of Bioactive Gases in the Brain

Oxygen and carbon dioxide are time honored gases that have direct bearing on almost all life forms, but over the past thirty years, and in large part due to the Nobel Prize Award in Medicine for the elucidation of nitric oxide (NO) as a bioactive gas, the research and medical communities now recognize other gases as critical for survival. In addition to NO, hydrogen sulfide (H₂S) and carbon monoxide (CO) have emerged as a triumvirate or Trinacrium of gases with analogous importance and that serve important homeostatic functions. Perhaps, one of the most intriguing aspects of these gases is the functional interaction between them, which is intimately linked by the enzyme systems that produce them. Despite the need to better understand NO, H₂S and CO biology, the notion that these are environmental pollutants remains ever present. For this reason, incorporating the concept of hormesis becomes imperative and must be included in discussions when considering developing new therapeutics that involve these gases. While there is now an enormous literature base for each of these gasotransmitters, we provide here an overview of their respective physiologic roles in the brain.

Cortex metabolome and proteome analysis reveals chronic arsenic exposure via drinking water induces developmental neurotoxicity through hnRNP L mediated mitochondrial dysfunction in male rats

Lots of people are at the risk of arsenic-contaminated drinking water. Arsenic exposure was confirmed to be closely linked to neurocognitive deficits, particularly during childhood. The multi-omics approaches are known be well suitable for toxicological research. Thus, this study aimed to explore the molecular mechanisms of arsenic-induced learning and memory function impairments through the integrative proteome and metabolome analysis of cortex in rats. The weaned rats were exposed to arsenic-contaminated drinking water for six months to mimic the developmental exposure. 220 differential proteins and 19 differential metabolites were identified in the cortex, and nine potential biomarkers were found to be related to impaired Morris water maze (MWM) indicators. Chronic arsenic exposure affected the cognitive function by inducing the overproduction of amyloid-β (Aβ) peptides and the redox imbalance in the mitochondria. Glycolysis and tricarboxylic acid (TCA) cycle enhancement driven by the increased heterogeneous nuclear ribonucleoprotein L (hnRNP L) is a low-dose protective mechanism against arsenic-induced ATP deficiency and oxidative stress. Moreover, apoptosis is another important pathway of arsenic-induced neurotoxicity. This study provides new evidence about the alterations of proteins and metabolites in the cortex of the exposed rats under arsenic toxicity. These findings suggest hnRNP L could be a potential target for the treatment of arsenic-induced neurotoxicity.

Differential effects of subchronic acrylonitrile exposure on hydrogen sulfide levels in rat blood, brain, and liver

Background

Hydrogen sulfide (H2S), as the third gasotransmitter participates in both cellular physiological and pathological processes, including chemical-induced injuries. We recently reported acute acrylonitrile (AN) treatment inhibited endogenous H2S biosynthesis pathway in rat and astrocyte models. However, there is still no evidence to address the correlation between endogenous H2S and sub-chronic AN exposure.

Objectives

This study aims to explore the modulatory effects of prolonged AN exposure on endogenous H2S levels and its biosynthetic enzymes in rat blood, brain and liver.

Methods

A total of 50 male Sprague-Dawley rats were randomly divided into 5 groups, including the control group and AN-treated groups at dosages of 6.25, 12.5, 25 or 50 mg/kg. Rats received one exposure/day, 5 days/week, for 4 consecutive weeks. The rat bodyweight and brain/liver organ coefficient were detected, along with liver cytochrome P450 2E1(CYP2E1) expression. In addition, the H2S contents in rat serum and plasma, and in cerebral cortex and liver tissues were measured by methylene blue method. The expression of H2S-generating enzymes, including cystathionine β-synthase (CBS), cystathionine γ-lyase (CSE) and 3-mercaptopyruvate sulfurtransferase (3-MPST) was also measured with Western blot both in rat cerebral cortex and liver.

Results

Subchronic exposure to AN significantly inhibited bodyweight-gain and increased the liver CYP2E1 expression compared with the control. In addition, AN significantly increased H2S levels in rat plasma and serum, but not in liver. The endogenous H2S level in rat cerebral cortex was also significantly increased upon AN treatment, when expression of the major H2S-generating enzymes, CBS and 3-MPST were significantly enhanced. However, hepatic protein levels of CBS and CSE were significantly increased, whereas hepatic levels of 3-MPST were significantly decreased.

Conclusion

This study showed that sub-chronic AN exposure increased endogenous H2S contents in rat blood and brain tissues, but not liver, which may be resulted from the distinct expression profile of H2S-producing enzymes in response to AN. The blood H2S contents may be applied as a potential novel biomarker for surveillance of chronically AN-exposed populations.

Highlights

Subchronic intraperitoneal exposure to acrylonitrile increased H2S content in rat blood and cerebral cortex, but not in liver.Distinct tissue expression profiles of H2S-producing enzymes contribute to the acrylonitrile-induced differential effects on the H2S level.Blood H2S level may be a biomarker for subchronic exposure to acrylonitrile.

Resveratrol protects against inorganic arsenic-induced oxidative damage and cytoarchitectural alterations in female mouse hippocampus

Prolonged inorganic arsenic (iAs) exposure is widely associated with brain damage particularly in the hippocampus via oxidative and apoptotic pathways. Resveratrol (RES) has gained considerable attention because of its benefits to human health. However, its neuroprotective potential against iAs-induced toxicity in CA1 region of hippocampus remains unexplored. Therefore, we investigated the neuroprotective efficacy of RES against arsenic trioxide (As₂O₃)-induced adverse effects on neuronal morphology, apoptotic markers and oxidative stress parameters in mouse CA1 region (hippocampus). Adult female Swiss albino mice of reproductive maturity were orally exposed to either As₂O₃ (2 and 4 mg/kg bw) alone or in combination with RES (40 mg/kg bw) for a period of 45 days. After animal sacrifice on day 46, the perfusion fixed brain samples were used for the observation of neuronal morphology and studying the morphometric features. While the freshly dissected hippocampi were processed for biochemical estimation of oxidative stress markers and western blotting of apoptosis-associated proteins. Chronic iAs exposure led to significant decrease in Stratum Pyramidale layer thickness along with reduction in cell density and area of Pyramidal neurons in contrast to the controls. Biochemical analysis showed reduced hippocampal GSH content but no change in total nitrite (NO) levels following iAs exposure. Western blotting showed apparent changes in the expression levels of Bax and Bcl-2 proteins following iAs exposure, however the change was statistically insignificant. Contrastingly, iAs +RES co-treatment exhibited substantial reversal in morphological and biochemical observations. Together, these findings provide preliminary evidence of neuroprotective role of RES on structural and biochemical alterations pertaining to mouse hippocampus following chronic iAs exposure.

Molecular Mechanisms of Environmental Metal Neurotoxicity: A Focus on the Interactions of Metals with Synapse Structure and Function

Environmental exposure to neurotoxic metals and metalloids such as arsenic, cadmium, lead, mercury, or manganese is a global health concern affecting millions of people worldwide. Depending on the period of exposure over a lifetime, environmental metals can alter neurodevelopment, neurobehavior, and cognition and cause neurodegeneration. There is increasing evidence linking environmental exposure to metal contaminants to the etiology of neurological diseases in early life (e.g., autism spectrum disorder) or late life (e.g., Alzheimer’s disease). The known main molecular mechanisms of metal-induced toxicity in cells are the generation of reactive oxygen species, the interaction with sulfhydryl chemical groups in proteins (e.g., cysteine), and the competition of toxic metals with binding sites of essential metals (e.g., Fe, Cu, Zn). In neurons, these molecular interactions can alter the functions of neurotransmitter receptors, the cytoskeleton and scaffolding synaptic proteins, thereby disrupting synaptic structure and function. Loss of synaptic connectivity may precede more drastic alterations such as neurodegeneration. In this article, we will review the molecular mechanisms of metal-induced synaptic neurotoxicity.

SLC7A11 regulated by NRF2 modulates esophageal squamous cell carcinoma radiosensitivity by inhibiting ferroptosis

BACKGROUND

Solute carrier family 7 member 11(SLC7A11) is a component of cysteine/glutamate transporter, which plays a key role in tumor growth; however, its underlying effect on radiosensitivity in esophageal squamous cell carcinoma (ESCC) remains unclear. This study aimed to clarify SLC7A11's expression and correlation with nuclear expression of nuclear factor erythroid-2 (NRF2)-associated radioresistance in ESCC.

METHODS

We included 127 ESCC patients who received radical chemoradiotherapy. Immunohistochemical staining was used to detect SLC7A11 and NRF2 nuclear expression, and the relationship between clinicopathological characteristics and survival rates or therapy response were evaluated. Western blot, dual-reporter assays and Chromatin immunoprecipitation (ChIP)-sequencing were used to analyze their relationship in vitro. Their roles in radioresistance were then investigated through multiple validation steps.

RESULTS

NRF2 nuclear expression and SLC7A11 expression were overexpressed in ESCC tissues and were positively correlated with one another. NRF2 nuclear expression was significantly associated with tumor length, lymph node metastasis, and TNM stage, while SLC7A11 expression was associated with lymph node metastasis. Patients with high NRF2 nuclear expression and SLC7A11 expression had significantly shorter overall and progression-free survival, and poor treatment response. The multivariate model showed that NRF2 nuclear expression and SLC7A11 expression, sex and tumor location are independent prognostic factors. In vitro analysis confirmed that hyperactivation of NRF2 induced SLC7A11 expression by directly binding to its promoter region, promoting radioresistance, reducing radiotherapy-induced lipid peroxidation levels, PTGS2 expression, and radiotherapy-related ferroptosis morphologic features.

CONCLUSION

Our study reveals a connection between high SLC7A11 expression and NRF2 nuclear expression in patients with ESCC that was related to worse survival and poorer therapy outcomes. SLC7A11-mediated ferroptosis inhibition induced NRF2-associated radioresistance, highlighting potential of NRF2/SLC7A11/ferroptosis axis as future therapeutic targets against therapy resistance biomarker.

Ceftriaxone Reduces Waterpipe Tobacco Smoke Withdrawal-induced Anxiety in rats via Modulating the Expression of TNF-α/NFĸB, Nrf2, and GLT-1

Tobacco exposure has been linked to neuroinflammation and adaptive/maladaptive changes in neurotransmitter systems, including in glutamatergic systems. We examined the effects of waterpipe tobacco smoke (WTS) on inflammatory mediators and astroglial glutamate transporters in mesocorticolimbic brain regions including the prefrontal cortex (PFC), nucleus accumbens (NAc) and ventral tegmental area (VTA). The behavioral consequences of WTS exposure on withdrawal-induced anxiety-like behavior were assessed using elevated plus maze (EPM) and open field (OF) tests. Male Sprague-Dawley rats were randomly assigned to 3 experimental groups: a control group exposed only to standard room air, a WTS exposed group treated with saline vehicle, and a WTS exposed group treated with ceftriaxone. WTS exposure was performed for 2 h/day, 5 days/week, for 4 weeks. Behavioral tests (EPM and OF) were conducted weekly 24 h after WTS exposure, during acute withdrawal. During week 4, rats were given either saline or ceftriaxone (200 mg/kg i.p.) 30 min before WTS exposure. WTS increased withdrawal-induced anxiety, and ceftriaxone attenuated this effect. WTS exposure increased the relative mRNA levels for nuclear factor ĸB (NFĸB), tumor necrosis factor-α (TNF-α), and brain-derived neurotrophic factor (BDNF) in the PFC, NAc and VTA, and ceftriaxone treatment reversed these effects. In addition, WTS decreased the relative mRNA of nuclear factor erythroid 2 related factor 2 (Nrf2), glutamate transporter 1 (GLT-1) and cystine-glutamate transporter (xCT) in PFC, NAc and VTA, and ceftriaxone treatment normalized their expression. WTS caused neuroinflammation, alteration in relative mRNA glutamate transport expression, and increased anxiety-like behavior, and these effects were attenuated by ceftriaxone treatment.

Ursodeoxycholic Acid Protects Against Arsenic Induced Hepatotoxicity by the Nrf2 Signaling Pathway

Arsenic is ubiquitous toxic metalloid responsible for many human diseases all over the world. Contrastingly, Ursodeoxycholic acid (UDCA) has been suggested as efficient antioxidant in various liver diseases. However, there are no reports of the effects of UDCA on arsenious acid [As(III)]-induced hepatotoxicity. The objective of this study is to elucidate the protective actions of UDCA on As(III)-induced hepatotoxicity and explore its controlling role in biomolecular mechanisms in vivo and in vitro. The remarkable liver damage induced by As(III) was ameliorated by treatment with UDCA, as reflected by reduced histopathological changes of liver and elevation of serum AST, ALT levels. UDCA play a critical role in stabilization of cellular membrane potential, inhibition of apoptosis and LDH leakage in LO2 cells. Meanwhile, the activities of SOD, CAT and GSH-Px and the level of TSH, GSH were enhanced with UDCA administration, while the accumulations of intracellular ROS, MDA and rate of GSSG/GSH were decreased in vivo and in vitro. Further study disclosed that UDCA significantly inhibited As(III)-induced apoptosis through increasing the expression of Bcl-2 and decreasing the expression of Bax, p53, Cyt C, Cleaved caspase-3 and 9. Moreover, UDCA promoted the expression of nuclear Nrf2, HO-1, and NQO1, although arsenic regulated nuclear translocation of Nrf2 positively. When Nrf2 was silenced, the protective effect of UDCA was abolished. Collectively, the results of this study showed that UDCA protects hepatocytes antagonize As(III)-induced cytotoxicity, and its mechanism may be related to activation of Nrf2 signaling.