Excessive Cu2+ deteriorates arsenite-induced apoptosis in chicken brain and resulting in immunosuppression, not in homeostasis

miRNA-21, which disrupts metabolic reprogramming to facilitate CD4+ T cell polarization toward the Th2 phenotype, accelerates arsenite-induced hepatic fibrosis

Elevated levels of arsenic may be present in groundwater, and long-term exposure to arsenic increases hepatic fibrosis. T helper 2 (Th2) cells are involved in the fibrotic cascade, and cell metabolism is a regulatory factor participating in CD4⁺ T cell differentiation and function. However, the mechanism for Th2 cell regulation of arsenite-induced hepatic fibrosis is not fully understood. In present study, for arsenite-fed mice, activated hepatic stellate cells may be involved in the infiltration of CD4⁺ T cells, accompanied by up-regulation of GATA3, a transcription factor, and IL-13, the major Th2 cytokine. Exposed to arsenite, Jurkat cells had increased aerobic glycolysis to promote the cell cycle and cell proliferation. Further, this process elevated levels of marker molecules, including those of the Th2 paradigm characterized by GATA3, IL-4, and IL-13. LX-2 cells were activated when treated with culture medium from Jurkat cells exposed to arsenite. miR-21 may be a therapeutic target for arsenite-induced hepatic fibrosis. In vitro, miR-21 knock-down caused inhibition of the PTEN/PI3K/AKT pathway induced by arsenite. It also reversed the elevated glycolysis and the accelerated cell cycle and cell proliferation. Indeed, this alteration led to diminished expression of GATA3, IL-4, and IL-13 in T cells differentiated under Th2 conditions, which inhibits activation of LX-2 cells. Consistent with the results in vitro, miR-21 knock-out in mice reversed hepatic fibrosis and attenuated the levels of GATA3 and IL-13 induced by arsenite. These findings indicate that miR-21 regulates the glycolysis of CD4⁺ T cells through the PTEN/PI3K/AKT pathway to accelerate the cell cycle, thereby facilitating CD4⁺ T cell polarization toward Th2 and releasing the fibrogenic factor IL-13, which participates in arsenite-associated hepatic fibrosis. Inhibition of Th2 polarization of CD4⁺T cells or miR-21 could be a therapeutic strategy to combat hepatic fibrosis caused by exposure to arsenic.

Melatonin ameliorates trimethyltin chloride-induced cardiotoxicity: The role of nuclear xenobiotic metabolism and Keap1-Nrf2/ARE axis-mediated pyroptosis

Trimethyltin chloride (TMT) is a stabilizer for polyvinyl chloride plastics that causes serious health hazards in nontarget organisms. Melatonin (MT) exhibits powerful protective effects in cardiac diseases. As a new environmental pollutant, TMT-induced cardiotoxicity and the protective effects of MT remain unclear. To explore this, the mice were treated with TMT (2.8 mg/kg) and/or MT (10 mg/kg) for 7 days. Firstly, the histopathological and ultrastructural evaluation showed that TMT induced cardiac damage, tumescent rupture and nuclear pyknosis. Moreover, TMT elevated the expressions of pyroptosis genes NLRP3, ASC and Cas1 and inflammation factors IL-6, IL-17 and TNFα. Secondly, TMT reduced antioxidant enzymes (GSH, CAT and T-AOC) via decreasing the expression of genes associated with the Keap1-Nrf2/ARE pathway to increase oxidative stress. Thirdly, TMT decreased the expression of genes associated with the ARE-driven drug metabolizing enzymes (DMEs), including Akr7a3, Akr1b8, and Akr1b10. Besides, TMT upregulated the mRNA expression of nuclear Xenobiotic metabolism on cytochrome P450s enzymes via increasing the expression of CAR, PXP, and AHR genes. Furthermore, MT treatment mitigated the aforementioned adverse changes induced by TMT. Overall, these results demonstrated that TMT caused pyroptosis and inflammation to aggravate cardiac damage via inducing excessive oxidative stress, imbalance of DMEs homeostasis, and nuclear Xenobiotic metabolism disorder, which could be alleviated by MT.

MicroRNA-294 Regulates Apoptosis of the Porcine Cerebellum Caused by Selenium Deficiency via Targeting iNOS

Deficiency of the essential trace element selenium (Se) can lead to cell apoptosis, and various microRNAs (miRNAs) are known to participate in the regulation of apoptosis by regulating their target genes. In this study, we explore the effect of Se deficiency on porcine cerebellar cell apoptosis and the role of miRNA in this process. After constructing a low-Se pig model, we observed the porcine cerebellum through an electron microscope and observed obvious characteristics of apoptosis. Moreover, it was found that the expression of miR-294 in Se-deficient pigs was significantly lower than that in the control group. Through bioinformatics, qRT-PCR, western blot analysis, and other experimental techniques, we further confirmed that inducible nitric oxide synthase (iNOS) is one of the target genes of miR-294. Our experimental results show that Se deficiency can reduce the expression of miR-294 and increase both the expression of iNOS and the nitric oxide (NO) content (P < 0.01). The expression of heat shock proteins (HSPs, such as HSP70, HSP90, HSP60, HSP40, and HSP27) and mitochondrial pathway-related indicators, such as Bcl2-associated X protein (Bax), cytochrome C (Cyt-C), and cysteinyl aspartate-specific proteinases (caspase 3, caspase 7, and caspase 8), was upregulated (P < 0.05), and the expression of B cell lymphoma-2 (Bcl-2) was downregulated (P < 0.05). In summary, we believe that Se deficiency can lead to abnormal expression of miR-294 and HSPs; moreover, the mitochondrial apoptosis pathway is activated, which significantly enhances apoptosis of cerebellar cells in Se-deficient pigs. These results enrich the biological effects of Se deficiency.

Metabolomics analysis reveals the effects of copper on mitochondria-mediated apoptosis in kidney of broiler chicken (Gallus gallus)

Copper (Cu) is one of the ubiquitous environmental pollutants which have raised wide concerns about the potential toxic effects and public health threat. For deeply investigating the nephrotoxicity induced by Cu, the effects of Cu on mitochondria-mediated apoptosis in kidney were first to analyze by combining metabolomics and molecular biology techniques. In this study, broiler chicks were fed with different contents of Cu (11, 110, 220, and 330 mg/kg Cu) for 49 d. The results of terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling (TUNEL) staining and transmission electron microscope showed that Cu could induce apoptosis in kidney, characterized by the increasing of TUNEL-positive cells and mitochondrial vacuolation. Additionally, a total of 62 differential metabolites were detected by liquid chromatography-mass spectrometry (LC-MS), and mainly enriched in the metabolic pathways including riboflavin metabolism, glutathione metabolism, sphingolipid metabolism, and glycerophospholipid metabolism, which were closely to mitochondrial metabolism. Meanwhile, the decreased mitochondrial membrane potential (MMP), increased mitochondrial membrane permeability and the change of mRNA and protein expression levels associated with mitochondria-mediated apoptosis and mitochondrial dynamics confirmed that Cu could induce mitochondria-mediated apoptosis. Therefore, our results demonstrated that Cu induced mitochondria-mediated apoptosis in kidney. Moreover, this study highlighted the metabolic characteristics of Cu to kidney, which suggested that mitochondrial metabolism could be considered as an important factor influencing toxicity.

In situ triggering antitumor efficacy of alcohol-abuse drug disulfiram through Cu-based metal-organic framework nanoparticles

Although approved as an alcohol-abuse drug, disulfiram (DSF) exhibited potential anticancer activity when chelated with copper (Cu). However, the low level of intrinsic Cu, toxicity originated from exogenous Cu supplementation, and poor stability of DSF in vivo severely limited its application in cancer treatment. Herein, we proposed an in situ DSF antitumor efficacy triggered system, taking advantages of Cu-based metal-organic framework (MOF). In detail, DSF was encapsulated into Cu-MOF nanoparticles (NPs) during its formation, and the obtained NPs were coated with hyaluronic acid to enhance the tumor targetability and biocompatibility. Notably, DSF loaded Cu-MOF NPs maintained stability and integrity without Cu2+ leakage in blood circulation, thus showing excellent biosafety. Once accumulating at tumor site, NPs were internalized into tumor cells via receptor-mediated endocytosis and released DSF and Cu2+ simultaneously in the hyaluronidase-enriched and acidic intracellular tumor microenvironment. This profile lead to in situ chelation reaction between DSF and Cu2+, generating toxic DSF/Cu complex against tumor cells. Both in vitro and in vivo results demonstrated the programmed degradation and recombination property of Cu-based MOF NPs, which facilitated the tumor-specific chemotherapeutic effects of DSF. This system provided a promising strategy for the application of DSF in tumor therapy.

Arsenite induce neurotoxicity of common carp: Involvement of blood brain barrier, apoptosis and autophagy, and subsequently relieved by zinc (Ⅱ) supplementation

Arsenic pollution is a common threat to aquatic ecosystems. The effects of chronic exposure to arsenite on the brains of aquatic organisms are unknown. This study was designed to evaluate arsenic-induced brain damage in common carp (Cyprinus carpio) and the ameliorating effects of divalent zinc ion (Zn2+) supplementation from the aspects of oxidative stress (OxS), tight junction (TJ), apoptosis and autophagy. After arsenite exposure (2.83 mg/L) for 30 days, oxidative damage to the brain was determined, as indicated by inhibited antioxidants system (catalase-superoxide dismutase system, and glutathione system) and elevated levels of biomacromolecule peroxidation (malondialdehyde and 8-hydroxydeoxyguanosine). Moreover, we also found functional damage to the brain as suggested by injuries to the blood-brain barrier (decreases in tight junction) and nerve conduction (depletion of AChE). Mechanisticly, apoptotic and autophagic cell death were indicated by typical morphologies including karyopyknosis and autophagosome, accompanying by key bio-indicators (Bcl-2, caspase and autophagy related gene family proteins). In contrast, the coadministration of Zn2+ (1 mg/L) with arsenite effectively alleviated this damage as suggested by the recovery of the aforementioned bioindicators. This study provides new insight into the brain toxicity caused by arsenite and suggests the application of zinc preparations in the aquatic pollution of arsenic.

Inflammation accelerates copper-mediated cytotoxicity through induction of six-transmembrane epithelial antigens of prostate 4 expression

Copper is an essential trace metal, but imbalance in copper homeostasis can induce oxidative damage. Inflammation is a fundamental element of various pulmonary diseases. Although a positive relationship between copper and chronic pulmonary diseases has been reported, the underlying reasons are still not clear. The copper level in the sputum of patients with various pulmonary diseases was measured. An inflammatory model was established to evaluate the impact of inflammation on copper uptake in the lung. We found that the level of sputum copper was increased in patients with various pulmonary diseases, especially chronic obstructive pulmonary disease and asthma. Then, we confirmed that mice with pulmonary inflammation were susceptible to copper-mediated oxidative damage because of copper overload in lung tissue. Further investigation demonstrated that interleukin (IL)-17 and tumor necrosis factor (TNF)-α exerted synergistic effects in airway epithelial cells by upregulating the expression of six-transmembrane epithelial antigens of prostate 4 (STEAP4), a metalloreductase that reduces extracellular copper ions from the cupric state to the cuprous state and facilitates copper uptake. Inhibition of STEAP4 decreased the copper uptake of cells and inhibited copper-mediated oxidative damage. Moreover, we demonstrated that the upregulation of STEAP4 by IL-17 and TNF-α was largely dependent on TNF receptor-associated factor 4 (TRAF4). Traf4^-/- mice were resistant to copper-mediated oxidative damage. Our data suggest a novel IL-17/TNF-α-TRAF4-STEAP4 axis that regulates copper homeostasis.

Selenoprotein Gpx3 knockdown induces myocardial damage through Ca2+ leaks in chickens

Glutathione peroxidase 3 (Gpx3) is a pivotal selenoprotein that acts as an antioxidant. However, the role of Gpx3 in maintaining the normal metabolism of cardiomyocytes remains to be elucidated in more detail. Herein, we employed a model of Gpx3 interference in chicken embryos in vivo and Gpx3 knockdown chicken cardiomyocytes in vitro. Real-time PCR, western blotting and fluorescent staining were performed to detect reactive oxygen species (ROS), the calcium (Ca²⁺) concentration, endoplasmic reticulum (ER) stress, myocardial contraction, inflammation and heat shock proteins (HSPs). Our results revealed that Gpx3 suppression increased the level of ROS, which induced Ca²⁺ leakage in the cytoplasm by blocking the expression of Ca²⁺ channels. The imbalance of Ca²⁺ homeostasis triggered ER stress and blocked myocardial contraction. Furthermore, we found that Ca²⁺ imbalance in the cytoplasm induced severe inflammation, and HSPs might play a protective role throughout these processes. In conclusion, Gpx3 suppression induces myocardial damage through the activation of Ca²⁺-dependent ER stress.

Arsenic (III) and/or copper (II) induces oxidative stress in chicken brain and subsequent effects on mitochondrial homeostasis and autophagy

As two quite complicated substances, arsenic (As) and copper (Cu) have polluted to the environment. As is highly toxic and could cause nerve damage. Cu is involved in the occurrence of oxidative stress. The brain is one of the main target organs of heavy metal toxicity, but the damage mechanism activated by As and/or Cu in the chicken brain has not been precisely researched. This study is designed to analyze the nervous system damage induced by As and/or Cu exposure from both structural and molecular levels. Under the As and/or Cu stress, local hemorrhage, inflammatory infiltration and mitochondrial damage were observed. Enzymes and non-enzyme antioxidants clearly show that the redox balance is deviated gradually. The results of real-time quantitative PCR and Western blotting revealed that there may be a cascading effect between oxidative stress and disruption of mitochondrial dynamics, the key protein of mitochondrial fusion has decreased and the fission protein has increased. The superposition of these two types of damage may activate the celluar autophagy pathway, the up-regulation of autophagy related genes (ATGs) levels could be observed. All data indicated that excessive As and/or Cu in the environment may pose a threat to the nervous system of poultry. These findings have neurophysiological meaning for exploring cross-contamination of As and Cu in the environment, and offering precautions to economic losses and negative effects on the health of animals and humans. In addition, it provides a reference for feed preparation and environmental protection in agricultural production.