Arsenic (III) induces oxidative stress and inflammation in the gills of common carp, which is ameliorated by zinc (II)

New insights into zinc alleviating renal toxicity of arsenic-exposed carp (Cyprinus carpio) through YAP-TFR/ROS signaling pathway

Environmental pollution caused by arsenic or its compounds is called arsenic pollution. Arsenic pollution mainly comes from people mining and smelting arsenic compounds. In addition, arsenic compounds' widespread use and production of arsenic-containing pesticides, arsenic-rich water used to irrigate farms, or high arsenic levels in foods caused by coal burning are all sources of arsenic contamination. Arsenic contamination poses a significant threat to global public health. It is reported that exposure to arsenic can induce severe renal injury. However, the underlying mechanism needs to be clarified. In this study, the arsenic exposure model in vivo and in vitro was used to explore the mechanism of arsenic-induced renal injury, especially the role of ferroptosis and its regulatory mechanism, and then to evaluate its anti-pollution effect by supplementing zinc. The results showed that arsenic significantly induced ferroptosis, characterized by up-regulating the expression of YAP and TFR in kidney and CIK cells and then increasing the levels of Fe2+ and ROS, lipid peroxidation, and iron metabolism. Microscopic observation revealed the shrinkage of mitochondria and the increase in membrane density. In addition, molecular docking and inhibitor experiments further confirmed that arsenic is involved in the process of ferroptosis by activating YAP and TFR. These results clarify the harmful effects of arsenic on carp kidneys and its mechanism and highlight the critical interactions between the YAP-TFR pathway, ROS, and ferroptosis. Importantly, this study found that zinc can reduce ferroptosis caused by the arsenic-activated YAP-TFR pathway by inhibiting YAP activation and lipid peroxidation.

Poison in the water: Arsenic's silent assault on fish health

Arsenic occurs across the world in freshwater and marine environments, menacing the survival of aquatic organisms. Organic and inorganic forms of this substance can be found, in which the inorganic form is more hazardous than the organic form. Most aquatic bodies contain inorganic arsenic species, but organic species are believed to be the dominant form of arsenic in the majority of fish. Natural and anthropogenic both are the sources of water contamination with arsenic. Its bioaccumulation and transfer from one trophic level to another in the aquatic food chain make arsenic a vital environmental issue. Continuous exposure to low concentrations of arsenic in aquatic organisms including fish leads to its bioaccumulation, which may affect organisms of higher trophic levels including large fishes or humans. Humans can be exposed to arsenic through the consumption of fish contaminated with arsenic. Hence, the present review facilitates our understanding about sources of arsenic, its bioaccumulation, food chain transfer, and its effect on the fish health. Also, "Poison in the Water: Arsenic's Silent Assault on Fish Health" serves as a wake-up call to recognize the pressing need to address arsenic contamination in water bodies. By understanding its devastating impact on fish health, we can strive to implement sustainable practices and policies that safeguard our precious aquatic environments and ensure the well-being of both wildlife and human communities that depend on them.

Toxicity and speciation of inorganic arsenics and their adverse effects on in vivo endpoints and oxidative stress in the marine medaka Oryzias melastigma

Here, we investigate the effects of acute and chronic exposure to arsenate (AsV) and arsenite (AsIII) in the marine medaka Oryzias melastigma. In vivo effects, biotransformation, and oxidative stress were studied in marine medaka exposed to the two inorganic arsenics for 4 or 28 days. An investigation of embryonic development revealed no effect on in vivo parameters, but the hatching rate increased in the group exposed to AsIII. Exposure to AsIII also caused the greatest accumulation of arsenic in medaka. For acute exposure, the ratio of AsV to AsIII was higher than that of chronic exposure, indicating that bioaccumulation of inorganic arsenic can induce oxidative stress. The largest increase in oxidative stress was observed following acute exposure to AsIII, but no significant degree of oxidative stress was induced by chronic exposure. During acute exposure to AsV, the increase in the enzymatic activity of glutathione-S-transferase (GST) was twice as high compared with exposure to AsIII, suggesting that GST plays an important role in the initial detoxification process. In addition, an RNA-seq-based ingenuity pathway analysis revealed that acute exposure to AsIII may be related to cell-cycle progression. A network analysis using differentially expressed genes also revealed a potential link between the generation of inflammatory cytokines and oxidative stress due to arsenic exposure.

Metallothionein: A Comprehensive Review of Its Classification, Structure, Biological Functions, and Applications

Metallothionein is a cysteine-rich protein with a high metal content that is widely found in nature. In addition to heavy metal detoxification, metallothionein is well known as a potent antioxidant. The high sulfhydryl content of metallothionein confers excellent antioxidant activity, enabling it to effectively scavenge free radicals and mitigate oxidative stress damage. In addition, metallothionein can play a neuroprotective role by alleviating oxidative damage in nerve cells, have an anticancer effect by enhancing the ability of normal cells to resist unfavorable conditions through its antioxidant function, and reduce inflammation by scavenging reactive oxygen species. Due to its diverse biological functions, metallothionein has a broad potential for application in alleviating environmental heavy metal pollution, predicting and diagnosing diseases, and developing skin care products and health foods. This review summarizes the recent advances in the classification, structure, biological functions, and applications of metallothionein, focusing on its powerful antioxidant effects and related functions.

Fe-Zn alloy, a new biodegradable material capable of reducing ROS and inhibiting oxidative stress

Fe-based biodegradable materials have attracted significant attention due to their exceptional mechanical properties and favorable biocompatibility. Currently, research on Fe-based materials mainly focuses on regulating the degradation rate. However, excessive release of Fe ions during material degradation will induce the generation of reactive oxygen species (ROS), leading to oxidative stress and ferroptosis. Therefore, the control of ROS release and the improvement of biocompatibility for Fe-based materials are very important. In this study, new Fe-Zn alloys were prepared by electrodeposition with the intention of using Zn as an antioxidant to reduce oxidative damage during alloy degradation. Initially, the impact of three potential degradation ions (Fe2+, Fe3+, Zn2+) from the Fe-Zn alloy on human endothelial cell (EC) activity and migration ability was investigated. Subsequently, cell adhesion, cell activity, ROS production and DNA damage were assessed at various locations surrounding the alloy. Finally, the influence of different concentrations of Zn2+ in the medium on cell viability and ROS production was evaluated. High levels of ROS exhibited evident toxic effects on ECs and promoted DNA damage. As an antioxidant, Zn2+ effectively reduced ROS production around Fe and improved the cell viability on its surface at a concentration of 0.04 mmol/l. These findings demonstrate that Fe-Zn alloy can attenuate the ROS generated from Fe degradation thereby enhancing cytocompatibility.

Zinc homeostasis may reverse the synergistic neurotoxicity of heavy metal mixtures in Caenorhabditis elegans

Heavy metal mixtures can cause nerve damage. However, the combined effects of metal mixtures are extremely complex and rarely studied. Zinc (Zn) homeostasis plays an integral role in neural function, but the role of Zn homeostasis in the toxicity of metal mixtures is not well understood. Here, we investigated the combined effects of manganese (Mn), lead (Pb) and arsenic (As) on nerves and the effect of Zn homeostasis on metal toxicity. Caenorhabditis elegans (Maupas, 1900) were exposed to single and multiple metals for 8 days, their movement, behavior, neurons and metal concentration were detected to evaluate the combined effect of metal mixtures. After nematodes were co-treated with metal mixtures and Zn, the nerve function, Zn concentration and redox balance were detected to evaluate the effect of Zn homeostasis on metal toxicity. The results showed that Mn + Pb and Pb + As mixtures induced synergistic toxicity for nematode nerves, which damaged movement, behavior and neurons, and decreased Zn concentration. While Zn supplementation recovered Zn homeostasis and promoted redox balance on nematodes, and then improved the nerve function. Our study demonstrated the combined effects of metal mixtures and the neuroprotective effect of Zn homeostasis. Therefore, assessment of metal mixtures toxicity should consider their interaction and the impacts of essential metals homeostasis.

Polystyrene microplastics induce apoptosis in chicken testis via crosstalk between NF-κB and Nrf2 pathways

Microplastics (MPs) are a new type of pollutants that are widespread in nature, and their toxic effects on humans or animals are receiving attention. Birds are in a higher ecological niche in nature, and MPs may have potential bioaccumulation and biomagnification risks to birds. The mechanisms underlying the reproductive toxicity of MPs to birds are mainly unknown. To study the reproductive toxicity of MPs to birds, we randomly divided chickens into six groups and exposed polystyrene microplastics (PS-MPs) through drinking water (0, 1, and 100 mg/L) for 28 and 42 days. We found that PS-MPs caused testicular inflammatory infiltration and interstitial hemorrhage, resulting in testicular tissue damage; the expression of Claudin3 and Occludin in the blood-testis barrier (BTB) decreased and may damage the integrity of the BTB. PS-MPs exposure inhibited the expression of the Nrf2-Keap1 pathway, which in turn reduced HO-1 and NQO1, simultaneous GSH and T-AOC were also reduced, resulting in an imbalance of the redox system; in addition, the NF-κB signaling pathway was activated, increasing the expression of TNF-α, COX-2 and iNOS. Under redox system imbalance and inflammatory stress, exposure to PS-MPs led to decreased expression of Bcl-2 and increased Bax, cytc, caspase-8, and caspase-3, etc., activating apoptosis, and ultimately causing testicular damage. These results suggested that PS-MPs exposure led to an imbalance of the redox system and an inflammatory response, inducing both endogenous and exogenous apoptosis, resulting in testicular tissue damage. Our study provides a theoretical basis for reproductive injury mechanisms in chicken.

Tollip suppresses MyD88-mediated NF-κB activation by enhancing MyD88 ubiquitination levels in large yellow croaker (Larimichthys crocea)

Toll-interacting protein (Tollip) plays an important role in the innate immune response by negative regulation of the TLR-IL-1R signaling pathway. MyD88 serves as a universal adaptor in TLR-mediated NF-κB activation. However, the regulation mechanisms of Tollip in piscine MyD88-mediated NF-κB activation is largely unknown. In the present study, the cDNA sequence of LcTollip was identified from the large yellow croaker (Larimichthys crocea). The putative LcTollip protein encoded 275 amino acid residues, containing a N-terminal TBD domain, a central C2 domain, and a C-terminal CUE domain. Quantitative PCR showed that the most predominant constitutive expression of LcTollip was detected in spleen. In addition, LcTollip transcripts enhanced significantly after LPS and poly I:C challenge (P < 0.05). Cellular localization revealed that LcTollip existed in the cytoplasm and nucleus. Furthermore, the overexpression plasmids of wild type LcTollip as well as its six domain truncated mutants of LcTollip were constructed by overlap PCR. Dual luciferase analysis showed that NF-κB activation could not be induced by overexpression of LcTollip or its domain truncated mutants alone. However, the LcMyD88-induced-NF-κB activation was significantly suppressed by overexpression with LcTollip, and the truncated mutants LcTollip-ΔTBD, LcTollip-ΔC2, LcTollip-ΔCUE and LcTollip-ΔTBDΔCUE while not by LcTollip-ΔLR and LcTollip-ΔTBDΔC2. Moreover, co-immunoprecipitation (Co-IP) assay revealed that the interaction between LcTollip and LcMyD88 was through CUE domain. More interesting, IP and immunoblotting examination of HEK293T cells co-transfected with LcMyD88, LcTollip and HA-ubiquitin showed that LcMyD88 induced a dose-dependent de-ubiquitination of LcTollip while LcTollip enhanced a dose-dependent ubiquitination of LcMyD88. However, protein degradation investigation displayed that the proteolysis and ubiquitination of LcMyD88 were not connected. Our findings suggested that the LcTollip might involve in negative regulation TLR pathway by suppressing LcMyD88-mediated immune activation and improving the ubiquitination level of LcMyD88.

Selenium-Enriched Yeast Relieves Hexavalent Chromium Toxicity by Inhibiting NF-κB Signaling Pathway in Broiler Spleens

Simple Summary

Hexavalent chromium is a common environmental pollution. It has been reported that hexavalent chromium threatens the health of humans and animals, so it is necessary to develop new, effective mitigation methods. Selenium is an indispensable micronutrient recently shown to be able to resist the toxicity of heavy metals. Selenium-enriched yeast has a high content of total selenium, which has the advantages of a high absorption rate and safety. Potassium dichromate and selenium-enriched yeast were used to construct single hexavalent chromium and combined selenium/hexavalent-chromium-exposed broiler models. Additionally, the ability to relieve the hexavalent chromium toxicity of selenium along with the molecular mechanisms focusing on inflammation induced by the NF-κB signaling pathway was investigated in this study. Histopathological assessment, serum biochemical tests, oxidative stress kits, enzyme-linked immunosorbent assay, quantitative real-time PCR, and Western blotting were used to detect indicators. We found that the oxidative stress induced by hexavalent chromium triggers NF-κB pathway-driven inflammatory responses in the broiler spleen and further reduces the immune function of broilers. Selenium-enriched yeast protects the spleen from the toxicity of hexavalent chromium exposure through inhibiting the NF-κB signaling pathway.

Abstract

This study was conducted to investigate the molecular mechanisms of selenium (Se) antagonism of hexavalent chromium (Cr⁶⁺)-induced toxicity. Potassium dichromate (K₂Cr₂O₇) and selenium-enriched yeast (SeY) were used to construct the single Cr⁶⁺ and combined Se/Cr⁶⁺ exposure broiler models, and then the broilers were randomly divided into four groups (C group, Se group, Se/Cr⁶⁺ group, and Cr⁶⁺ group). After a 42-day experiment, the spleen tissues of broilers were excised and weighted. The antagonistic mechanisms of Se and Cr⁶⁺ were evaluated using histopathological assessment, serum biochemical tests, oxidative stress kits, ELISA, qPCR, and Western blotting. On the whole, there were no significant changes between the C and Se groups. The spleen organ index in the Cr⁶⁺ group was significantly decreased, but SeY increased spleen organ index to a certain extent. The levels of SOD and GSH were reduced, and the MDA content was elevated by Cr⁶⁺; however, these changes were mitigated by Se/Cr⁶⁺ exposure. Importantly, Cr⁶⁺ exposure induced a series of histopathological injuries in broiler spleen tissues, while these symptoms were significantly relieved in the Se/Cr⁶⁺group. Furthermore, Cr⁶⁺ significantly decreased the levels of T-globulin, IgA, IgM, and IgG in serum. Contrarily, dramatically more T-globulin IgA, IgM, and IgG were found in the Se/Cr⁶⁺group than in the Cr⁶⁺ group. Revealed by the results of qPCR and WB, the expressions of NF-κB, IκBα, and p-IκBα were upregulated in Cr⁶⁺ groups, while they were downregulated in Se/Cr⁶⁺ group compared to that in Cr⁶⁺ group. Besides IFN-γ and IL-2, the expressions of pro-inflammatory cytokines were significantly increased by Cr⁶⁺ exposure, but the SeY supplement relived the expression levels mediated by Cr⁶⁺ exposure. In conclusion, our findings suggest SeY has biological activity that can protect broiler spleens from immunosuppression and inflammation induced by Cr⁶⁺, and we speculate that the NF-κB signaling pathway is one of its mechanisms.