Cadmium exposure induces apoptosis, inflammation and immunosuppression through CYPs activation and antioxidant dysfunction in common carp neutrophils

Removal and assessment of cadmium contamination based on the toxic responds of a soil ciliate Colpoda sp

Bioremediation of cadmium (Cd) pollution, a recognized low-carbon green environmental protection technology, is significantly enhanced by the discovery of Cd-tolerant microorganisms and their underlying tolerance mechanisms. This study presents Colpoda sp., a soil ciliate with widespread distribution, as a novel bioindicator and bioremediator for Cd contamination. With a 24 h-LC50 of 5.39 mg l-1 and an IC50 of 24.85 μg l-1 in Cd-contaminated water, Colpoda sp. achieves a maximum bioaccumulation factor (BAF) of 3.58 and a Cd removal rate of 32.98 ± 0.74 % within 96 h. The toxic responses of Colpoda sp. to Cd stress were assessed through cytological observation with transmission electron microscopy (TEM), oxidative stress kinase activity, and analysis of Cd-metallothionein (Cd-MTs) and the cd-mt gene via qRT-PCR. The integrated biomarker response index version 2 (IBRv2) and structural equation models (SEM) were utilized to analyze key factors and mechanisms, revealing that the up-regulation of Cd-MTs and cd-mt expression, rather than the oxidative stress system, is the primary determinant of Cd accumulation and tolerance in Colpoda sp. The ciliate's ability to maintain growth under 24.85 μg l-1 Cd stress and its capacity to absorb and accumulate Cd particles from water into cells are pivotal for bioremediation. A new mathematical formula and regression equations based on Colpoda sp.'s response parameters have been established to evaluate environmental Cd removal levels and design remediation schemes for contaminated sites. These findings provide a novel bioremediation and monitoring pathway for Cd remobilization and accumulation in soil and water, potentially revolutionizing the governance of Cd pollution.

Effects of 2,4-dichlorophenol on non-specific immunity, histopathological lesions, and redox balance in African Catfish, clarias gariepinus (Burchell, 1822)

The toxic effects of 2, 4-dichlorophenol (2, 4-DCP) on aquatic organisms are well-established; however, the details regarding the mechanisms underlying the toxicity, especially immunotoxicity are poorly understood. Consequently, the aim of this study was to investigate the histopathologic, oxidative stress and immunotoxic effects attributed to exposure to sublethal concentrations of 2,4-DCP in the African catfish, Clarias gariepinus. Juvenile C. gariepinus were exposed to 0.4, 0.8, or 1.6 mg/L 2, 4-DCP for 28 days after which blood and head kidney were extracted for the determination of various nonspecific innate immune parameters while the liver was excised for histopathology examination and measurement of oxidative stress biomarkers. Control fish were maintained in water spiked 10 µL/L ethanol, representing the solvent control. A significant increase was noted in the activities of lactate dehydrogenase and superoxide dismutase as well as in levels of lipid peroxidation and DNA fragmentation in a dose-dependent manner, with higher adverse effects observed at the highest concentration tested (1.6 mg/L). The total white blood cells (WBC) count was significantly elevated in fish exposed to 2,4-DCP compared to control. Myeloperoxidase content was decreased significantly in fish exposed to 2,4-DCP especially at the highest concentration (1.6 mg/L) compared to controls. The respiratory burst activity did not differ markedly amongst groups. Histopathological lesions noted included edema, leucocyte infiltration, and depletion of hemopoietic tissue in the head kidney of exposed fish. There was significant upregulation in the mRNA expression of tumor necrosis factor (TNF-α) and heat shock protein 70 (HSP 70) but downregulation of major histocompatibility complex 2 (MHC 2) in exposed fish. Data demonstrated that exposure to 2,4-DCP resulted in histopathological lesions, oxidative stress, and compromised immune system in C. gariepinus.

The antagonism mechanism of astilbin against cadmium-induced injury in chicken lungs via Treg/Th1 balance signaling pathway

The purpose of this study was to investigate the effect of Treg/Th1 imbalance in cadmium-induced lung injury and the potential protective effect of astilbin against cadmium-induced lung injury in chicken. Cadmium exposure significantly decreased T-AOC and GSH-Px levels and SOD activity in the chicken lung tissues. In contrast, it significantly increased the MDA and NO levels. These results indicate that cadmium triggers oxidative stress in lungs. Histopathological analysis revealed that cadmium exposure further induced infiltration of lymphocytes in the chicken lungs, indicating that cadmium causes pulmonary damage. Further analysis revealed that cadmium decreased the expression of IL-4 and IL-10 but increased those of IL-17, Foxp3, TNF-α, and TGF-β, indicating that the exposure of cadmium induced the imbalance of Treg/Th1. Moreover, cadmium adversely affected chicken lung function by activating the NF-kB pathway and inducing expression of genes downstream to these pathways (COX-2, iNOS), associated with inflammatory injury in the lung tissue. Astilbin reduced cadmium-induced oxidative stress and inflammation in the lungs by increasing antioxidant enzyme activities and restoring Treg/Th1 balance. In conclusion, our results suggest that astilbin treatment alleviated the effects of cadmium-mediated lung injury in chickens by restoring the Treg/Th1 balance.

Unveiling the underwater threat: Exploring cadmium's adverse effects on tilapia

Prolonged exposure to environmentally relevant amounts of cadmium (Cd) in aquatic environments, even at small doses (0.1 and 1 μg/L), might endanger the health of underwater creatures. This research delved into the impacts of a four-month cadmium exposure on Mozambique tilapia (Oreochromis mossambicus), aiming to uncover the mechanisms behind it. Through close examination, we found that the 4-momth cadmium exposure led to harmful effects on the fish's gills, muscles, brain, and intestines. This exposure also triggered changes in gene expressions in the brain and liver, affected the respiratory system and weakened liver's ability to detoxify and defend against potential infections. Looking deeper into the fish's gut, we noticed alterations in energy-related genes and disruptions in immune pathways, making it more susceptible to illnesses. The exposure to cadmium also had an impact on the fish's gut and water-dwelling microorganisms, reducing diversity and encouraging harmful microbial communities. Interestingly, some gut microbes seemed to assist in breaking down and detoxifying cadmium, which could potentially protect the fish. Taken together, prolonged low-level cadmium exposure impaired gill, muscle, and brain function, suppressed immunity, disrupted intestines, and altered microbial balance, leading to hindered growth. These insights illuminate cadmium's impact on fish, addressing vital environmental concerns.

Influence of titanium dioxide nanoparticles and/or cadmium chloride oral exposure on testicular morphology, oxidative stress, and apoptosis in rats: Ameliorative role of co-enzyme Q10

Background and objectives

Little is known about the implications of titanium dioxide nanoparticles (TiO2NPs) and cadmium chloride (Cd) co-exposure on the male reproductive system in mammals. As a result, this study researched the effects of oral TiO2NPs and/or Cd exposure on male reproduction and testicular functions. Additionally, a mitigation trial with co-enzyme Q10 (CoQ10) has also been conducted.

Methods

In a 60-day experiment, seven experimental groups, each containing 10 male Sprague Dawley rats, were orally given distilled water (control), corn oil (vehicle control), CoQ10 (10 mg/kg b.wt), TiO2NPs (50 mg/kg b.wt), Cd (5 mg/kg b.wt), TiO2NPs + Cd, and TiO2NPs + Cd + CoQ10. Then, sperm quality, male sex hormones, oxidative stress indications, Ti and Cd testicular residues, testes and accessory gland architecture, and apoptotic and inflammatory markers in rat testes were assessed.

Results

TiO2NPs and/or Cd exposure negatively impacted body weight, weight gain, testicular weights, semen quality, serum reproductive hormones, oxidative stress parameters, and Caspase-3 and tumor necrosis factor (TNF-α) immunoreactions. Histopathological changes were recorded in testicular, seminal vesicle, and prostatic tissues. Yet, co-administration of CoQ10 with TiO2NPs and Cd substantially mitigated these adverse consequences. The most notable aspect is that it effectively lowered testicular tissue Ti and Cd levels. It also improved oxidant status, hormonal profile, and sperm picture. CoQ10 minimized the testicular damage implied by histological examination. Furthermore, CoQ10 significantly diminished TiO2NPs and Cd-induced Caspase-3 and TNF-α immunoexpression in testicular tissue.

Conclusion

As a result, CoQ10 could be utilized as a safe remedy to protect male reproductive physiology from TiO2NPs and Cd damage.

Effect of dietary koumine on the immune and antioxidant status of carp (Cyprinus carpio) after Aeromonas hydrophila infection

Koumine (KM) has anxiolytic, anti-inflammatory and growth-promoting effects in pigs and sheep. Based on the growth-promoting and immunological effects of koumine, the present study was conducted on Cyprinus carpio (C. carpio) with four KM concentrations: 0 mg/kg, 0.2 mg/kg, 2 mg/kg, and 20 mg/kg for 10 weeks, followed by a 1-week Aeromonas hydrophila (A. hydrophila) infection experiment. The effect of KM on the immunity of A. hydrophila infected carp was analyzed by histopathology, biochemical assay, and qRT-PCR to assess the feasibility of KM in aquaculture. The results showed that the presence of KM alleviated pathogen damage to carp tissues. At 2 mg/kg and 20 mg/kg concentrations of KM successively and significantly elevated (p < 0.05) the SOD activities in the intestinal tract, hepatopancreas and kidney of carp. The expression levels of hepatopancreatic antioxidant genes Nrf2 and IGF-1 were significantly up-regulated in the same group (p < 0.05), while the expression levels of immune genes IL-8 and IL-10 were down-regulated. In summary, KM at concentrations of 2 mg/kg and 20 mg/kg could regulate the expression of antioxidant and immune genes in various tissues in an orderly and rapid manner, and significantly improve the antioxidant and immune abilities of carp, which is conducive to the improvement of the resilience of carp.

A Review of in vivo Toxicity of Quantum Dots in Animal Models

Tremendous research efforts have been devoted to nanoparticles for applications in optoelectronics and biomedicine. Over the past decade, quantum dots (QDs) have become one of the fastest growing areas of research in nanotechnology because of outstanding photophysical properties, including narrow and symmetrical emission spectrum, broad fluorescence excitation spectrum, the tenability of the emission wavelength with the particle size and composition, anti-photobleaching ability and stable fluorescence. These characteristics are suitable for optical imaging, drug delivery and other biomedical applications. Research on QDs toxicology has demonstrated QDs affect or damage the biological system to some extent, and this situation is generally caused by the metal ions and some special properties in QDs, which hinders the further application of QDs in the biomedical field. The toxicological mechanism mainly stems from the release of heavy metal ions and generation of reactive oxygen species (ROS). At the same time, the contact reaction with QDs also cause disorders in organelles and changes in gene expression profiles. In this review, we try to present an overview of the toxicity and related toxicity mechanisms of QDs in different target organs. It is believed that the evaluation of toxicity and the synthesis of environmentally friendly QDs are the primary issues to be addressed for future widespread applications. However, considering the many different types and potential modifications, this review on the potential toxicity of QDs is still not clearly elucidated, and further research is needed on this meaningful topic.

A preliminary study on the pathology and molecular mechanism of fumonisin B1 nephrotoxicity in young quails

Fumonisin B1 (FB1) is a widely present mycotoxin that accumulates in biological systems and poses a health risk to animals. However, few studies have reported the molecular mechanism by which FB1 induces nephrotoxicity. The aim of this study was to assess the extent of nephrotoxicity during FB1 exposure and the possible molecular mechanisms behind it. Therefore, 180 young quails were equally divided into two groups. The control group was fed typical quail food, while the experimental group was fed quail food containing 30 mg·kg-1 FB1. Various parameters were assessed, which included histopathological, ultrastructural changes, levels of biochemical parameters, oxidative indicators, inflammatory factors, possible target organelles mitochondrial and endoplasmic reticulum (ER)-related factors, nuclear xenobiotic receptors (NXR) response, and cytochrome P450 system (CYP450s)-related factors in the kidneys on days 14, 28, and 42. The results showed that FB1 can induce oxidative stress through NXR response and disorder of the CYP450s system, leading to mitochondrial dysfunction and ER stress, promoting the expression of inflammatory factors (including IL-1β, IL-6, and IL-8) and causing kidney damage. This study elucidated the possible molecular mechanism by which FB1 induces nephrotoxicity in young quails.

Review of cadmium toxicity effects on fish: Oxidative stress and immune responses

Cadmium (Cd) in aquatic environments can cause environmental toxicity to fish and induce oxidative stress owing to an excessive production of reactive oxygen species in fish bodies. Fish have developed various antioxidant systems to protect themselves from reactive oxygen species; thus, a change in antioxidant responses in fish can be a criterion for evaluating oxidative stress resulting from Cd exposure. Because Cd exposure may be recognized as an exogenous substance by a fish body, it may lead to the stimulation or suppression of its immune system. Various immune responses can be assessed to evaluate Cd toxicity in fish. This review aimed to identify the impacts of Cd exposure on oxidative stress and immunotoxicity in fish as well as identify accurate indicators of Cd toxicity in aquatic ecosystems.

Toxic effects of cadmium exposure on intestinal histology, oxidative stress, microbial community, and transcriptome change in the mud crab (Scylla paramamosain)

Cadmium is one of hazardous pollutants that has a great threat to aquatic organisms and ecosystems. The intestine plays important roles in barrier function and immunity to defend against environmental stress. However, whether cadmium exposure caused the intestine injury is not well studied. Thus, the aim of this study was to explore the potential mechanisms of cadmium toxicity in the intestine of mud crab (Scylla paramamosain) via physiological, histological, microbial community, and transcriptional analyses. Mud crabs were exposed to 0, 0.01, and 0.125 mg/L cadmium. After a 21-day of cadmium exposure, 0.125 mg/L cadmium caused intestine damaged by decreasing superoxide dismutase and catalase activities, and increasing hydrogen peroxide and malondialdehyde levels. Integrated biological index analysis confirmed that the toxicity of cadmium exhibited a concentration-dependent manner. Comparative transcriptional analyses showed that the up-regulations of several genes associated with heat shock proteins, detoxification and anti-oxidant defense, and two key signaling pathways (PI3k-Akt and apoptosis) revealed an adaptive response mechanism against cadmium exposure. Transcriptomic analysis also suggested that cadmium exposure disturbed the expression of ion transport and immune-related genes, indicating that it has negative effects on the immune functions of the mud crab. Furthermore, the intestinal microbial diversity and composition were significantly influenced by cadmium exposure. The abundance of the dominant phyla Fusobacteria and Bacteroidetes significantly changed after cadmium exposure. KEGG pathway analysis demonstrated that cadmium exposure could change energy metabolism and environmental information processing. Overall, we concluded that excessive cadmium exposure could be potentially exerted adverse effects to the mud crab health by inducing oxidative damage, decreasing immune system, disrupting metabolic function, and altering intestinal microbial composition. These results provided a novel insight into the mechanism of cadmium toxicity on crustaceans.

Effects of Zinc Supplementation in Mitigating the Harmful Effects of Chronic Cadmium Exposure in a Zebrafish Model

Cadmium (Cd) is a heavy metal that is highly toxic to living organisms, including humans. But the dietary zinc (Zn) supplements play critical role in minimizing or preventing Cd poisoning, without any side effects. The underlying mechanisms, however, have not been thoroughly investigated. Therefore, in this study, we investigated the use of Zn as a protection against Cd toxicity in zebrafish models. The obtained results confirmed the levels of antioxidant enzymes and supported the synergistic effects of Zn in reducing Cd toxicity. The lipid, carbohydrate, and protein concentrations in the liver tissue have also been negatively impacted by Cd; however, treatment with Zn has lessened these adverse effects. Furthermore, the level of 8-hydroxy-2' -deoxyguanosine (8-OHdG), caspase-3 also confirms the protective effects of Zn in reducing DNA damage caused by Cd. The results of this study demonstrate that a Zn supplement can lessen the harmful effects of Cd in zebrafish model.

Adaptive plastic responses to metal contamination in a multistress context: a field experiment in fish

Wild populations often differ in their tolerance to environmental stressors, but intraspecific variability is rarely taken into account in ecotoxicology. In addition, plastic responses to multiple stressors have rarely been investigated in realistic field conditions. In this study, we compared the responses to metal contamination of gudgeon populations (Gobio occitaniae) differing in their past chronic exposure to metal contamination, using a reciprocal transplant experiment and an immune challenge mimicking a parasite attack to test for potential effects of multiple stressors across biological levels. We measured fish survival and traits involved in metal bioaccumulation, oxidative stress, immunity, cell apoptosis, and energy management to decipher underpinning physiological mechanisms across biological levels (i.e., gene expression, cell, organism). Fish from the two replicate High Contamination sites had higher survival when transferred into contaminated sites, suggesting a local adaptation to the contaminated site, possibly explained by higher levels of detoxification and antioxidant capacity but with potential higher apoptosis costs compared to their naïve counterparts. We found no evidence of co- or maladaptation to the immune stressor, suggesting no specific costs to face pathogens. In the emerging field of evolutionary ecotoxicology, this study underlines the need to consider intraspecific variability to better understand the effects of pollution in heterogeneous populations.

A novel cadmium detoxification pathway in Tri-spine horseshoe crab (Tachypleus tridentatus): A 430-million-years-ago organism

Marine and intertidal heavy metal pollution has been a major concern in recent years. Tachypleus tridentatus has existed on earth for more than 430 million years. It has suffered a sharp decline in population numbers caused by environmental pollution and anthropogenic disturbance for almost 40 years. However, the effects of heavy metal pollution on juvenile T. tridentatus have not been reported. Here we show the mechanism of cadmium (Cd) detoxification in juvenile T. tridentatus using integrated antioxidant indexes and transcriptomic and metabolomic analysis. High Cd²⁺ concentration caused oxidative stress in juvenile T. tridentatus. The hazards increase with increasing Cd²⁺ concentration in juvenile T. tridentatus. Transcriptomics and metabolomics analyses concluded that high Cd²⁺ concentration resulted in the imbalance of glycerophospholipid metabolism in juvenile T. tridentatus to detoxify Cd. Our results offer a rationale for protective measures and further studies of heavy metal stress in T. tridentatus.

Mechanism of evodiamine blocking Nrf2/MAPK pathway to inhibit apoptosis of grass carp hepatocytes induced by DEHP

Di (2-ethylhexyl) phthalate (DEHP) is often used as a plasticizer for plastic products, and its excessive use can cause irreversible damage to aquatic animals and humans. Evodiamine (EVO) is an alkaloid component in the fruit of Evodia rutaecarpa, which has antioxidant and detoxification functions. To investigate the toxic mechanism of DEHP on grass carp (Ctenopharyngodon idellus) hepatocyte cell line (L8824) and the therapeutic effect of evodiamine, an experimental model of L8824 cells exposed to 800 μM DEHP and/or 10 μM EVO for 24 h was established. Flow cytometry, AO/EB fluorescence staining, real-time quantitative PCR, and western blot were used to detect the degree of cell injury, oxidative stress level, MAPK signaling pathway relative genes, and the expression of apoptosis-related molecules. The results showed that DEHP exposure could significantly increase the level of reactive oxygen species (ROS), inhibit the activities of antioxidant enzymes (CAT, SOD, GSH-Px), and cause the accumulation of MDA. DEHP also activated MAPK signaling pathway-related molecules (JNK, ERK, P38 MAPK), and then up-regulated the expression of pro-apoptotic factors Bcl-2-Associated X (Bax) and caspase 3, while inhibiting the anti-apoptotic factor B-cell lymphoma-2 (Bcl-2). In addition, EVO can also promote the dissociation of nuclear factor-E2-related factor 2 (Nrf2) into the nucleus, reduce the level of ROS and the occurrence of oxidative stress in grass carp hepatocytes, down-regulate the MAPK pathway, alleviate DEHP-induced apoptosis, and restore the expression of antioxidant genes. These results indicated that evodiamine could block Nrf2/MAPK pathway to inhibit DEHP-induced apoptosis of grass carp hepatocytes.

Associations of long-term cadmium exposure with peripheral white blood cell subtype counts and indices in residents of cadmium-polluted areas

BACKGROUND

Experimental evidence suggests that exposure to cadmium (Cd) could affect immune cells in vivo and in vitro. However, the associations of long-term Cd exposure with white blood cell (WBC) subtype counts and hemogram-derived indices have been rarely investigated. Therefore, we evaluated these relationships in residents of cadmium-polluted areas.

METHODS

This cross-sectional study included 431 participants aged 45-75 years without occupational exposure histories from Cd-contaminated areas of southern China. We detected WBC, neutrophil, lymphocyte, and monocyte counts using routine blood tests and calculated neutrophil-lymphocyte ratio (NLR), systemic inflammation response index (SIRI), and lymphocyte-monocyte ratio (LMR). Urinary Cd (U-Cd) was measured with inductively coupled plasma mass spectrometry and adjusted for creatinine. To evaluate the associations of U-Cd with peripheral WBC subtype counts and indices, we performed multivariate linear regression, logistic regression and subgroup analyses using U-Cd categorized into quartiles.

RESULTS

In models adjusted for all potential confounders, U-Cd was negatively associated with WBC, neutrophil, and monocyte counts in Q2, compared with Q1 of U-Cd (p < 0.05). A similar relationship was observed between U-Cd and NLR and SIRI, whereas the corresponding association for LMR was positive (p < 0.05). In subgroup analyses, U-Cd was negatively associated with neutrophil count, except for never smokers, after full adjustment.

CONCLUSIONS

U-Cd was negatively associated with WBC count, neutrophil count, monocyte count, NLR, and SIRI, and positively associated with LMR. Therefore, neutrophil count could be a potential indicator of long-term Cd exposure-associated immunosuppressive effect.

Combined exposure to di(2-ethylhexyl) phthalate and polystyrene microplastics induced renal autophagy through the ROS/AMPK/ULK1 pathway

Di(2-ethylhexyl) phthalate (DEHP) and polystyrene microplastics (PS-MPs) are new environmental pollutants that attracted increased attention. At present, the effects and underlying mechanisms of action of combined exposure of DEHP and PS-MPs on the kidney have not been elucidated. To investigate the renal toxicity of DEHP and PS-MPs exposure, we established single and combined DEHP and PS-MPs exposure models in mice and HEK293 cells, respectively. Hematoxylin and eosin staining, transmission electron microscopy, monodansylcadaverine staining, immunofluorescence, real-time quantitative PCR, Western blot analysis and other methods were used to detect relevant indicators. The results showed that the expression levels of ROS/AMPK/ULK1 and Ppargc1α/Mfn2 signaling pathway-related genes were significantly increased in the DEHP and PS-MPs exposure models. The mRNA and protein expression levels of autophagy markers were also upregulated. In addition, we found that the expression levels of mRNAs and proteins in the combined exposure group were more significantly increased than those in the single exposure group. In conclusion, combined exposure to DEHP and PS-MPs caused oxidative stress and activated the AMPK/ULK1 pathway, thereby inducing renal autophagy. Our results enhance the field of nephrotoxicity studies of plasticizers and microplastics and provide new light on combined toxicity studies of DEHP and PS-MPs.

Parental cadmium exposure during the spawning period reduces cadmium sensitivity through the antioxidant system in rare minnow (Gobiocypris rarus) larvae

Cadmium (Cd) is a noxious heavy metal widely dispersed in aquatic systems. Parental Cd exposure of fish species at environmental concentrations has been shown to cause deformities and stunted growth in their offspring. However, the long-term effects and the mechanisms underlying parental Cd exposure in fish species on Cd sensitivity in their offspring remain unclear. To explore the impacts of parental Cd exposures on Cd sensitivity, rare minnow (Gobiocypris rarus) larvae whose parents were exposed to Cd at 0, 5 or 10 μg/L for 28 days were established. Results showed that parental Cd exposure in rare minnow increased the Cd content of its larvae. In terms of malformation rate, mortality rate and total length at 7 days of rare minnow larvae, parental Cd exposure at 5 or 10 μg/L reduced Cd sensitivity. Further mechanistic investigation demonstrated that parental Cd exposure significantly upregulated the expression of antioxidant gene regulated by nuclear factor erythroid 2-related factor 2 (Nrf2) and nuclear factor-kappa B (NF-кB) in rare minnow larvae. In addition, parental Cd exposure significantly elevated the level of reactive oxygen species (ROS) and malondialdehyde (MDA), but markedly decreased catalase (CAT), superoxide dismutase (SOD) and oxidized glutathione (GST) activity. The impact of parental Cd exposure to metallothionein (MT) content and the expression of MT mRNA, a detoxifying metallothionein, showed that parental Cd exposure of rare minnow induced oxidative stress in the larvae. Meanwhile, these results indicated that parental Cd exposure in rare minnow reduced the Cd sensitivity of the larvae via activating the Nrf2-mediated antioxidant system. This project helps us to further understand the toxicological mechanism of Cd in fish species and properly assess its potential ecological risk.

Toxic Effects of Cadmium on Fish

Large amounts of enriched cadmium (Cd) in the environment seriously threatens the healthy and sustainable development of the aquaculture industry and greatly restricts the development of the food processing industry. Studying the distribution and toxic effects of Cd in fish, as well as the possible toxic effects of Cd on the human body, is very significant. A large number of studies have shown that the accumulation and distribution of Cd in fish are biologically specific, cause tissue differences, and seriously damage the integrity of tissue structure and function, the antioxidant defense system, the reproductive regulation system, and the immune system. The physiological, biochemical, enzyme, molecular, and gene expression levels change with different concentrations and times of Cd exposure, and these changes are closely related to the target sites of Cd action and tissues in fish. Therefore, the toxic effects of Cd on fish occur with multiple tissues, systems, and levels.

Mechanisms of Cd-induced Cytotoxicity in Normal Human Skin Keratinocytes: Implication for Human Health

Cadmium (Cd) is one of the toxic heavy metals found widely in the environment. Skin is an important target organ of Cd exposure. However, the adverse effects of Cd on human skin are still not well known. In this study, normal human skin keratinocytes (HaCaT cells) were studied for changes in cell viability, morphology, DNA damage, cycle, apoptosis, and the expression of endoplasmic reticulum (ER) stress-related genes (XBP-1, BiP, ATF-4, and CHOP) after exposure to Cd for 24 h. We found that Cd decreased cell viability in a concentration-dependent manner, with a median lethal concentration (LC₅₀) of 11 µM. DNA damage induction was evidenced by upregulation of the level of γ-H2AX. Furthermore, Cd induced G0/G1 phase cell cycle arrest and apoptosis in a dose-dependent manner and upregulated the mRNA levels of ER stress biomarker genes (XBP-1, BiP, ATF4, and CHOP). Taken together, our results showed that Cd induced cytotoxicity and DNA damage in HaCaT cells, eventually resulting in cell cycle arrest in the G0/G1 phase and apoptosis. In addition, ER stress may be involved in Cd-induced HaCaT apoptosis. Our data imply the importance of reducing Cd pollution in the environment to reduce its adverse impacts on human skin.

Cyt-C Mediated Mitochondrial Pathway Plays an Important Role in Oocyte Apoptosis in Ricefield Eel (Monopterus albus)

Apoptosis plays a key role in the effective removal of excessive and defective germ cells, which is essential for sequential hermaphroditism and sex change in vertebrates. The ricefield eel, Monopterus albus is a protogynous hermaphroditic fish that undergoes a sequential sex change from female to male. Previous studies have demonstrated that apoptosis is involved in sex change in M. albus. However, the apoptotic signaling pathway is unclear. In the current study, we explored the underlying mechanism of apoptosis during gonadal development and focused on the role of the mitochondrial apoptosis signaling pathway in sex change in M. albus. Flow cytometry was performed to detect apoptosis in gonads at five sexual stages and ovary tissues exposed to hydrogen peroxide (H2O2) in vitro. Then the expression patterns of key genes and proteins in the mitochondrial pathway, death receptor pathway and endoplasmic reticulum (ER) pathway were examined. The results showed that the apoptosis rate was significantly increased in the early intersexual stage and then decreased with the natural sex change from female to male. Quantitative real-time PCR revealed that bax, tnfr1, and calpain were mainly expressed in the five stages. ELISA demonstrated that the relative content of cytochrome-c (cyt-c) in the mitochondrial pathway was significantly higher than that of caspase8 and caspase12, with a peak in the early intersexual stage, while the levels of caspase8 and caspase12 peaked in the late intersexual stage. Interestingly, the Pearson’s coefficient between cyt-c and the apoptosis rate was 0.705, which suggests that these factors are closely related during the gonadal development of M. albus. Furthermore, the cyt-c signal was found to be increased in the intersexual stage by immunohistochemistry. After incubation with H2O2, the mRNA expression of mitochondrial pathway molecules such as bax, apaf-1, and caspase3 increased in ovary tissues. In conclusion, the present results suggest that the mitochondrial apoptotic pathway may play a more important role than the other apoptotic pathways in sex change in M. albus.

Role of miR-451 in mediating cadmium induced head kidney injury in common carp via targeting cacna1ab through autophagy pathways

Cadmium (Cd) is a common environmental pollutant, which leads to Cd residue in aquatic animals. The Cd in aquatic animals will be enriched into the human body through the food chain and seriously harm human health. The research aims to investigate the molecular mechanism of Cd poisoning in common carps. Our previous studies have confirmed that 23 differentially expressed miRNAs were potential biomarkers for Cd exposure in common carp head kidney lymphocytes. Herein, based on the prediction of the website and previous studies, miR-451 and cacna1ab were selected and their targeting relationship was verified again by dual-luciferase. Subsequently, we established the miR-451 overexpression/knockdown models and miR-451 inhibitor, cacna1ab co-knockdown models in common carp head kidney lymphocytes respectively. Immunofluorescence staining, MDC staining, calcium staining, qRT-PCR (Quantitative Real-time PCR) and western blot were used to detect the levels of autophagy. Our results demonstrated that Cd significantly decreased the expression of miR-451, miR-451 suppression thereby induced increased cacna1ab and the expression of ATG5, LC3-I, LC3-II and Beclin 1, while significantly inhibiting the expression of mTOR, P62 and Bcl-2, which indicated that autophagy was triggered. Moreover, the miR-451 knockdown group activated the expression of autophagy related factors as well as the Cd group. However, cacna1ab knockdown can reduce autophagy activation induced by miR-451 knockdown. Our results indicated that Cd induced autophagy in head kidney lymphocytes through the inhibition of miR-451 and the excitation of cacna1ab.

Dataset-based assessment of heavy metal contamination in freshwater fishes and their health risks

The ecological risks and health hazards of heavy metals pollution in Taihu Lake have received widespread concern. This study has developed a species-pollution dataset which includes a large amount of data on heavy metal pollution in Taihu fish. The heavy metal contamination poses a significant threat to human consumption, but no studies have been conducted to assess the risk of exposure to consumption of these fish and to make recommendations for their consumption. In this study, we systematically integrated the relevant data in the dataset, analyzed its contamination level using PI (single pollution index) and MPI (metal pollution index) models, and assessed health hazards of fish consumption using THQ (target hazard quotient) and ILCR (incremental lifetime cancer risk) models. Results showed that the contamination levels of heavy metals in fish varied in a feeding habit and living habit dependent manner. The risk of non-cancer health is the highest from consuming omnivorous fish, then from carnivorous and herbivorous fish. The ILCR model predicted that the long-term Taihu consumption of omnivorous fish may pose a potential carcinogenic risk, especially for children. In all, our study provided a comprehensive understanding on the risk of heavy metals in Taihu. Accordingly, it is recommended that children should try to choose herbivorous fish when consuming fish from Taihu Lake while avoiding long-term consumption of omnivorous fish.

Registered human trials addressing environmental and occupational toxicant exposures: Scoping review of immunological markers and protective strategies

Exposure to pollution is a worldwide societal challenge participating in the etiology and progression of different diseases. However, the scarce information hinders our understanding of the actual level of human exposure and its specific effects. Inadequate and excessive immune responses underlie diverse chronic diseases. Yet, it is unclear which and how toxicant exposures affect the immune system functions. There is a multiplicity of immunological outcomes and biomarkers being studied in human trials related to exposure to different toxicants but still without clear evidence of their value as biomarkers of exposure or effect. The main aim of this study was to collect scientific evidence and identify relevant immunological biomarkers used at the clinical level for toxicant exposures. We used the platform clinical trials.gov as a database tool. First, we performed a search combining research items related to toxicants and immunological parameters. The resulting117 clinical trials were examined for immune-related outcomes and specific biomarkers evaluated in subjects exposed to occupational and environmental toxicants. After categorization, relevant immunological outcomes and biomarkers were identified related to systemic and airway inflammation, modulation of immune cells, allergy and autoimmunity. In general, the immune markers related to inflammation are more frequently investigated for exposure to pollutants, namely IL-6, C-reactive protein (CRP) and nitric oxide (NO). Nevertheless, the data also indicated that prospective biomarkers of effect are gaining ground and a guiding representation of the established and novel biomarkers is suggested for upcoming trials. Finally, potential protective strategies to mitigate the adverse effects of specific toxicants are underlined for future studies.

Mechanism of Cadmium Exposure Induced Hepatotoxicity in the Mud Crab (Scylla paramamosain): Activation of Oxidative Stress and Nrf2 Signaling Pathway

Cadmium, one of the most toxic heavy metals, can cause severe oxidative damage to aquatic animals. However, the mechanism whereby the mud crabs respond to cadmium exposure remains unclear. This study investigated the effects of cadmium exposure on oxidative stress and histopathology changes and evaluated the role of the Nrf2 signaling pathway in regulating responses to cadmium-induced hepatotoxicity were investigated in mud crabs. Mud crabs were exposed to 0, 0.01, 0.05, and 0.125 mg/L cadmium for 21 d. The present results indicated that cadmium exposure increased hydrogen peroxide (H₂O₂) production, lipid peroxidation and tissue damage, but decreased the activity of superoxide dismutase (SOD) and catalase (CAT), and caused lipid peroxidation and tissue damage. The results of an integrated biomarker index analysis suggested that the toxicity of cadmium was positively related to cadmium concentration. The expression levels of the Nrf2 signaling pathway (Nrf2, metallothionein, and cytochrome P450 enzymes) were up-regulated after cadmium exposure. Silencing of Nrf2 in vivo decreased antioxidant gene (SOD, CAT, and glutathione S-transferase) expression, suggesting that Nrf2 can regulate antioxidant genes. Knocking down Nrf2 in vivo also significantly decreased the activity of SOD and CAT after cadmium exposure. Moreover, silencing of Nrf2 in vivo enhanced H₂O₂ production and the mortality rates of mud crabs after cadmium exposure. The present study indicated that cadmium exposure induced hepatotoxicity in the mud crab by increasing H₂O₂ content, which decreased the antioxidant capacity, leading to cell injury. In addition, the Nrf2 is activated to bound with antioxidant response element, initiating the expression of antioxidant enzyme genes during cadmium induced hepatotoxicity in the mud crabs.

Characterization, expression, and function analysis of AKR1A1 gene from yellow catfish (Tachysurus fulvidraco)

Aldehyde reductase (AKR1A1) is a carbonyl detoxification protein in toxic aldehyde removal. In the present study, the full-length cDNA of yellow catfish AKR1A1 (TfAKR1A1) was cloned. As expected, yellow catfish AKR1A1 showed similarities with that of other species. Subsequently, prokaryotic expression vector was constructed and recombinant TfAKR1A1 (rTfAKR1A1) was successfully induced and purified. rTfAKR1A1 exhibited reductive activity to many aldehydes and ketones. To determine whether TfAKR1A1 could confer stress tolerance in vitro, the viability of control and TfAKR1A1 expression E. coli under abiotic stress was compared by spot assay. Results showed that the recombinant strain had better stress resistance under cadmium, hydrogen peroxide, and DL-glyceraldehyde stress. Then, effects of an intraperitoneal injection of rTfAKR1A1 protein on cadmium-induced oxidative stress were evaluated. Results displayed that TfAKR1A1 and Nrf2 expression levels were significantly decreased, CAT and SOD expression levels were significantly increased, BCL-2 and IL-10 expression levels were significantly increased, and caspase3a, NF-κB, and IL-1β expression levels were significantly decreased in protein-injection group. Furthermore, oxidative stress indexes in livers under different protein injection doses were examined by ELISA. Results showed that CAT, SOD, and GSH-Px activities were upregulated, ROS and T-AOC contents were also improved, while MDA content was significantly decreased both in lower and middle dose injection groups. Finally, liver pathological section analysis was performed. Results displayed that liver injury degree in protein-injected groups was lower than that of PBS group under cadmium stress. These results suggested that TfAKR1A1 played important roles in response to cadmium stress in yellow catfish.

Etanercept Mitigates Cadmium Chloride-induced Testicular Damage in Rats "An Insight into Autophagy, Apoptosis, Oxidative Stress and Inflammation"

RATIONALE

Cadmium (Cd) is an environmental and occupational toxin that represents a serious health hazard to humans and other animals. One of the negative consequences of cadmium exposure is testicular injury.

OBJECTIVE

This study aimed to investigate the therapeutic effect of etanercept against cadmium chloride-induced testicular damage and the probable underlying mechanisms of its action.

METHODS

A total of sixty rats were divided into six groups: control, cadmium chloride (CdCl₂) (7 mg/ kg i.p.), and CdCl₂ treated with etanercept (5,10 and 15 mg/kg s.c.) and etanercept only (15 mg/kg s.c.). CdCl₂ was administrated as a single dose, while etanercept was administered every 3 days for 3 weeks.

RESULTS

CdCl₂ reduced serum testosterone, testicular glutathione (GSH), catalase (CAT), and superoxide dismutase (SOD). However, it elevated the levels of malondialdehyde (MDA) and microtubule-associated protein light chain 3B (LC3B) in the testes. Cadmium caused pathogenic alterations as well as increased levels of inflammatory biomarkers such as tumor necrosis factor-alpha (TNF-α) and nuclear factor-kappa B (NF-κB). Besides, the gene expressions of caspase-3 and inducible nitric oxide synthase (i-NOS) and Beclin-1 protein increased with CdCl₂ exposure. Interestingly, etanercept relieved the previous toxic effects induced by CdCl₂ in a dose-dependent manner as evidenced by inhibition of oxidative stress, inflammatory markers, Beclin-1, LC3B, and caspase-3 accompanied by improvement in histopathological changes.

CONCLUSION

Etanercept provides a potential therapeutic approach to treat testicular tissue against the damaging effects of Cd by reducing oxidative stress, inflammation, apoptosis, and autophagy.

Carnosic Acid Suppresses the Development of Oral Squamous Cell Carcinoma via Mitochondrial-Mediated Apoptosis

Oral squamous cell carcinoma (OSCC) predominantly consists of squamous cells and is the tumor with the highest incidence of the head and neck. Carnosic acid (CA), a natural monomer drug obtained from rosemary and salvia, shows various pharmacological effects, including of tumor development. This study aimed to assess for an effect of CA on the development of OSCC and the underlying mechanisms. In CAL27 and SCC9 cells, CA inhibited cell proliferation and migration, increased intracellular levels of reactive oxygen species (ROS) and Ca²⁺, decreased the mitochondrial membrane potential (MMP), and promoted apoptosis. In CAL27- and SCC9-xenotransplanted BALB/c nude mice, CA inhibited the tumor growth without affecting the body weight and tissue morphology. CA upregulated Bax, Bad, cleaved Caspase-3 and -9 levels, and the cleaved PARP1/PARP1 ratio but downregulated Bcl-2 in CA-treated OSCC cells and OSCC cells-xenotransplanted BALB/c nude mice. These results indicate that CA suppresses OSCC at least via the mitochondrial apoptotic pathway and offers this natural compound as a potential therapeutic against OSCC.

Cadmium induced Fak -mediated anoikis activation in kidney via nuclear receptors (AHR/CAR/PXR)-mediated xenobiotic detoxification pathway

Cadmium (Cd) is a toxic heavy metal of considerable toxicity, possessing a serious environmental problem that threatening food safety and human health. However, the underlying mechanisms of Cd-induced nephrotoxicity and detoxification response remain largely unclear. Cd was administered at doses of 35, 70, and 140 mg/kg diet with feed for 90 days and produced potential damage to chickens' kidneys. The results showed that Cd exposure induced renal anatomical and histopathological injuries. Cd exposure up-regulated cytochrome P450 enzymes (CYP450s), activated nuclear xenobiotic receptors (NXRs) response, including aryl hydro-carbon receptor (AHR), constitutive androstane receptor (CAR), and pregnane X receptor (PXR) by low and moderate doses of Cd, and induced an increase in CYP isoforms expression. Cd exposure down-regulated phase II detoxification enzymes (glutathione-S-transferase (GST), glutathione peroxidase (GSH-PX) activities, and glutathione (GSH) content), and GST isoforms transcription . Furthermore, ATP-binding cassette (ABC) transporters, multidrug resistance protein (MRP1), and P-glycoprotein (P-GP) levels were elevated by low dose, but high dose inhibited the P-GP expression. Activation of detoxification enzymes lost their ability of resistance as increasing dose of Cd, afterwards brought into severe renal injury. Additionally, Cd suppressed focal adhesion kinase (Fak) and integrins protein expression as well as activated extrinsic pathway and intrinsic pathways, thereby producing anoikis. In conclusion, these results indicated that Cd induced Fak-mediated anoikis activation in the kidney via nuclear receptors (AHR/CAR/PXR)-mediated xenobiotic detoxification pathway.

Quercetin antagonizes imidacloprid-induced mitochondrial apoptosis through PTEN/PI3K/AKT in grass carp hepatocytes

Imidacloprid (IMI) is widely used in agriculture, and is toxic to non-target aquatic species. Quercetin (Que) is a flavonoid abundant in fruits and vegetables that exhibits anti-oxidant activity. In the present study, we treated grass carp hepatocytes (L8824) with 0.1 μM Que and/or 1 mM IMI for 24 h to explore the effect of Que on IMI-induced mitochondrial apoptosis. We found that IMI exposure enhanced reactive oxygen species (ROS) generation, inhibiting the activities of SOD, CAT and T-AOC, exacerbating the accumulation of MDA, aggravating the expression of mitochondrial apoptosis pathway (Cyt-C, BAX, Caspase9 and Caspase3) related genes and decreased the expression of anti-apoptosis gene B-cell lymphoma-2 (Bcl-2). In addition, Que and IMI co-treatment significantly restored the activity of anti-oxidant enzymes, downregulated ROS level and apoptosis rate, thereby alleviating the depletion of mitochondrial membrane potential (ΔΨm) and the expression of cytochrome c (Cyt-C), Bcl-2-associated X (BAX), and cysteinyl aspartate specific proteinases (Caspase9 and 3), increasing the Bcl-2 level. Furthermore, we elucidated that Que could inhibit the expression of phosphatase and tensin homolog deleted on chromosome 10 (PTEN), thus activating phosphatidylinositol 3-kinase/protein kinase B (PI3K/AKT) pathway to attenuate IMI-induced apoptosis. Molecular docking provides assertive evidence for the interaction between Que ligand and PTEN receptor. Consequently, these results indicate that Que effectively antagonizes IMI-induced mitochondrial apoptosis in grass carp hepatocytes via regulating the PTEN/PI3K/AKT pathway.

Chlorpyrifos caused necroptosis via MAPK/NF-κB/TNF-α pathway in common carp (Cyprinus carpio L.) gills

Chlorpyrifos (CPF) is an organophosphate insecticide and can cause cell death of animals. In the study, the common carp were exposed to CPF at 0 μg/L (the control group), 1.16 μg/L (the low dose group), 11.6 μg/L (the medium dose group), and 116 μg/L (the high dose group), respectively. The carp were euthanized at the 30th day and gills were collected immediately. The ultrastructural and histopathological observations showed obvious necrosis characteristics and inflammatory injury in the CPF-treated groups. CPF exposure activated the MAPK pathway, in which the mRNA and protein expressions of extracellular signal-regulated (ERK), p38 MAP kinase (p38), and c-Jun N-terminal kinase (JNK) were increased; the mRNAs and proteins of NF-κB and TNF-α were activated; and the mRNAs and proteins of necroptosis related genes were changed (the mRNA and protein expression of RIPK1, RIPK3, MLKL, and FADD were increased and caspase-8 was decreased) with concentration dependency. Taken together, we concluded that CPF exposure activated the MAPK/NF-κB/TNF-α pathway, promoted inflammatory injure and evoked necroptosis in common carp gills. In addition, CPF-induced inflammation and necroptosis was concentration dependency. The toxic effects of CPF on gills provided data for both aquaculture and toxicological studies.

Subacute cadmium exposure promotes M1 macrophage polarization through oxidative stress-evoked inflammatory response and induces porcine adrenal fibrosis

Cadmium (Cd) is a widely distributed environmental pollutant with immunotoxicity and endocrine toxicity. M1/M2 macrophages participate in the immune response and exert an essential influence on fibrosis. Nevertheless, whether Cd can induce porcineadrenal fibrosis by affecting the polarization of M1/M2 macrophages and its potential regulatory mechanism have not been explored. We added 20 mg/kg CdCl₂ to the pig diet for 40 days to investigate the fibrogenic effect of subacute Cd exposure on the adrenal gland. The results indicated that the ACTH and CORT in serum were decreased by 15.26 % and 21.99 %, respectively. The contents of adrenal mineral elements Cd, Cr, Mn were increased up to 34, 1.93, 1.42 folds and Co, Zn, Sn were reduced by 21.57 %, 20.52 %, 15.75 %. Concurrently, the pro-oxidative indicators (LPO, MDA and H₂O₂) were increased by 1.85, 2.20, 2.77 folds and 3.60, 11.15, 4.11 folds upregulated mRNA levels of TLR4, NF-κB, NLRP3 were observed. Subsequently, the expression of M1 macrophages polarization markers (IL-6, iNOS, TNF-α, CCL2 and CXCL9) were raised by 2.03, 2.30, 2.35, 1.58, 1.56 folds, while M2 macrophages (IL-4, CCL24, Arg1, IL-10, MRC1) showed a 62.34 %, 31.88 %, 50.26 %, 74.00 %, 69.34 % downregulation. The expression levels of AMPK subunits and genes related to glycolysis, oxidative phosphorylation (OXPHOS) and fatty acid oxidation (FAO) were also markedly increased. Additionally, the expression level of TGF-β1, Smad2/3 and downstream pro-fibrotic markers was obviously upregulated. Taken together, we conclude that Cd activates the oxidative stress-mediated TLR4/NF-κB/NLRP3 inflammatory signal transduction, leading to porcine adrenal fibrosis by promoting macrophage polarization toward M1.

Selenium-deficient diet induces necroptosis in the pig brain by activating TNFR1 via mir-29a-3p

Selenium (Se) deficiency is one of the crucial factors related to nervous system disease and necroptosis. MicroRNAs (miRNAs) play vital roles in regulating necroptosis. However, the mechanism of Se deficiency-induced necroptosis in the pig brain tissue and the role that miRNAs play in this process are unclear. Therefore, in this study, in vitro and pig models of Se deficiency were replicated, and electron microscopy, quantitative real-time polymerase chain reaction (qRT-PCR) and western blot assays were performed. The results showed that brain cells typically undergo necrotic changes, and that Se deficiency suppresses mir-29a-3p, which increases the levels of TNFRSF1A (TNFR1). Subsequently, a distinct increase in the necroptosis markers (RIPK1, RIPK3, and MLKL) and an evident decrease in caspase 8 was observed. And the expression of 10 selenoproteins was decreased. Moreover, the in vitro experiments showed that the expression of mir-29a-3p decreased as the Se content in the medium decreased and the application of an mir-29a-3p inhibitor increased the number of necrotic cells and the accumulation of ROS, and these effects were inhibited by necrostatin-1 (Nec-1) and N-acetyl-cysteine (NAC), respectively. Taken together, we proved that Se deficiency induced necroptosis both in vitro and in vivo through the targeted regulation of TNFR1 by mir-29a-3p in the pig brain.

Th1/Th2 imbalance and heat shock protein mediated inflammatory damage triggered by manganese via activating NF-κB pathway in chicken nervous system in vivo and in vitro

Manganese (Mn) is a ubiquitous heavy metal pollutant in environment, and excess Mn can damage nervous system of humans and animals. However, molecular mechanism of Mn-induced poultry neurotoxicity on inflammatory injury is still not fully clear. Thus, the purpose of the conducted research was to explore molecular mechanism of inflammatory injury caused by Mn in chicken nervous system. Two Mn poisoning models were established in vivo and in vitro. One hundred and eighty chickens were randomly separated into four groups. One control group was raised drinking water and standard diet. Three Mn groups were raised drinking water, and the standard diet supplemented with three different concentrations of MnCl2 ∙ 4H2O. There were 45 birds and 3 replicates in each group. Neurocytes from chicken embryos were cultured in mediums without and with six different concentrations of MnCl2 ∙ 4H2O in vitro. Our experiments showed that excess Mn caused cerebral histomorphological structure alternations and damage, and increased the expressions (P < 0.05) of inflammation-related factor NF-κB, TNF-α, iNOS, COX-2, and PTGEs in vivo and in vitro, meaning that excess Mn caused inflammatory damage and inflammatory response in chicken nervous system. Moreover, there were an upregulated IFN-γ mRNA expression and a downregulated IL-4 mRNA expression (P < 0.05) in bird cerebra and embryonic neurocytes after exposure to Mn, indicating that Mn exposure caused Th1/Th2 imbalance and immunosuppression. Additionally, in our research, the elevation (P < 0.05) of five HSPs (HSP27, HSP40, HSP60, HSP70, and HSP90) was found, suggesting that HSPs participated molecular mechanism of Mn stress. In addition, the inflammatory toxicity of Mn to chicken nervous system was time- and dose-dependent. Taken all together, our findings indicated that Th1/Th2 imbalance and HSPs mediated Mn-caused inflammatory injury via NF-κB pathway in chicken nervous system in vivo and in vitro.

Effects of Cadmium Exposure on the Immune System and Immunoregulation

Cadmium (Cd), a biologically non-essential heavy metal, is widespread in the environment, including the air, water, and soil, and is widely present in foods and quantum dot preparations. Cd enters the body primarily through inhalation and ingestion. Its biological half-life in humans is 10-35 years; therefore, Cd poses long-term health risks. While most studies on Cd toxicity have focused on organ and tissue damage, the immunotoxicity of Cd has drawn increasing attention recently. Cd accumulates in immune cells, modulates the function of the immune system, triggers immunological responses, and leads to diverse health problems. Cd acts as an immunotoxic agent by regulating the activity and apoptosis of immune cells, altering the secretion of immune cytokines, inducing reactive oxygen species (ROS) production and oxidative stress, changing the frequency of T lymphocyte subsets, and altering the production of selective antibodies in immune cells. This review summarizes the immunological toxicity of Cd, elucidates the mechanisms underlying Cd toxicity in terms of innate immunity and adaptive immunity, and discusses potential strategies to alleviate the adverse effects of Cd on the immune system.

Cadmium exposure induces inflammation and necroptosis in porcine adrenal gland via activating NF-κB/MAPK pathway

Cadmium (Cd) is a heavy metal harmful to animals and humans. Cd exposure causes inflammation or necroptosis in many tissues, including adrenal tissue. However, the current researches on the effects of Cd²⁺ in adrenal tissues are not enough. Therefore, in our experiment Cd chloride (CdCl₂) was added to the piglet's diet at a concentration of 20 mg/kg to study the effects of Cd²⁺ exposure on the porcine adrenal tissue. Our results showed that Cd²⁺ exposure could cause inflammation by activating the nuclear factor kappa-B (NF-κB) pathway, which in turn induced necroptosis in adrenal tissue with the activated mitogen-activated protein kinase (MAPK) pathway. The expression increase of inflammatory factors and necroptosis downstream genes, and the downregualtion of cysteinyl aspartate specific proteinase 8 (Caspase 8) proved that Cd²⁺ exposure caused inflammation and necroptosis in adrenal tissue. We conclude that this report provides more basic theoretical data for exploring the mechanism of adrenal injury.

Sequencing and Comparative Genomic Analysis of a Highly Metal-Tolerant Penicillium janthinellum P1 Provide Insights Into Its Metal Tolerance

Heavy metal pollution is a global knotty problem and fungi hold promising potential for the remediation of wastewater containing heavy metals. Here, a new highly chromium-tolerance species, Penicillium janthinellum P1, is investigated. The genome of P1 was sequenced and assembled into 30 Mb genome size containing 10,955 predicted protein-coding genes with a GC content of 46.16% through an integrated method of Illumina short-read sequencing and single-molecule real-time Pacific Biosciences sequencing platforms. Through a phylogenetic analysis with model species of fungi, the evolutionary divergence time of Penicillium janthinellum P1 and Penicillium oxalicum 114-2 was estimated to be 74 MYA. 33 secondary metabolism gene clusters were identified via antiSMASH software, mainly including non-ribosomal peptide synthase genes and T1 polyketide synthase genes. 525 genes were annotated to encode enzymes that act on carbohydrates, involving 101 glucose-degrading enzymes and 24 polysaccharide synthase. By whole-genome sequence analysis, large numbers of metal resistance genes were found in strain P1. Especially ABC transporter and Superoxide dismutase ensure that the P1 fungus can survive in a chromium-polluted environment. ChrA and ChrR were also identified as key genes for chromium resistance. Analysis of their genetic loci revealed that the specific coding-gene arrangement may account for the fungus’s chromium resistance. Genetic information and comparative analysis of Penicillium janthinellum are valuable for further understanding the mechanism of high resistance to heavy metal chromium, and gene loci analysis provides a new perspective for identifying chromium-resistant strains.

Protective Effects of α-Lipoic Acid and Chlorogenic Acid on Cadmium-Induced Liver Injury in Three-Yellow Chickens

Simple Summary

Cadmium (Cd) exerts pernicious influences on global health. We evaluated the protective effects of α-lipoic acid (α-LA) or chlorogenic acid (CGA) and their combination on counteracting Cd toxicity in vivo in three-yellow chickens. Administration of Cd (50 mg/L) alone lowered the production performance and resulted in biochemical, histologic and enzyme changes within the liver consistent with hepatic injury induced by oxidative stress and apoptosis of hepatocytes. However, the above variations of the Cd group were partially or fully reversed by administration of either α-LA or CGA; their combination showed an even better effect in attenuating Cd-induced hepatotoxicity. This study provided a practical and feasible approach to rescuing Cd intoxication in animal production.

Abstract

Cadmium (Cd) is a type of noxious heavy metal that is distributed widely. It can severely injure the hepatocytes and cause liver dysfunction by inducing oxidative stress and mitochondrial damage. We evaluated the protective effects of α-lipoic acid (α-LA) or chlorogenic acid (CGA) and their combination on counteracting cadmium toxicity in vivo in three-yellow chickens. For three months, CdCl₂ (50 mg/L) was administrated through their drinking water, α-LA (400 mg/kg) was added to feed and CGA (45 mg/kg) was employed by gavage. The administration of Cd led to variations in growth performance, biochemical markers (of the liver, kidney and heart), hematological parameters, liver histopathology (which suggested hepatic injury) and ultrastructure of hepatocytes. Some antioxidant enzymes and oxidative stress parameters showed significant differences in the Cd-exposure group when compared with the control group. The groups treated with Cd and administrated α-LA or CGA showed significant amelioration with inhibited mitochondrial pathway-induced apoptosis. Combining both drugs was the most effective in reducing Cd toxicity in the liver. In summary, the results demonstrated that α-LA and CGA may be beneficial in alleviating oxidative stress induced by oxygen free radicals and tissue injury resulting from Cd-triggered hepatotoxicity.

Lycopene alleviates sulfamethoxazole-induced hepatotoxicity in grass carp (Ctenopharyngodon idellus) via suppression of oxidative stress, inflammation and apoptosis

Antibiotics are used worldwide to treat diseases in humans and other animals; most of them and their secondary metabolites are discharged into the aquatic environment, posing a serious threat to human health. However, the toxicity of antibiotics on aquatic organisms, especially the effects on the detoxification system and immune system, has not been thoroughly studied. Lycopene (LYC) is a naturally occurring hydrocarbon carotenoid, which has received extensive attention as a potential antioxidant. The aim of this study was to investigate whether LYC alleviates exogenous toxicity in carp induced by sulfamethoxazole (SMZ) and the underlying molecular mechanisms. The grass carp were treated with SMZ (0.3 μg L-1) and/or LYC (10 mg per kg body weight) for 30 days. Indexes, such as hepatic function-related including histopathological changes and biochemical parameters, detoxification system-related including the cytochrome P450 enzyme system and antioxidant system, and immune system-related including inflammatory and apoptosis processes were detected. The results showed that SMZ stress leads to significant pathological damage of the liver and induction of oxidative stress. LYC coadministration recovered the cytochrome p450-1A1 homeostasis and decreased SMZ-induced accumulation of intracellular reactive oxygen species (ROS). Mechanistically, indicators in the innate immune system (such as toll like receptors (TLRs), tumor necrosis factor-α (TNF-α), interleukin (IL)-1β, IL-6 and IL-8) and the apoptosis pathway (p53, PUMA, B-cell lymphoma-2 (Bcl-2), BCL2-associated X (Bax), and Caspase-9/3) disclosed adaptive activation under SMZ exposure; these anomalies returned to normal or close-to-normal levels after LYC coadministration. Therefore, LYC dietary supplement possesses liver protective function against exogenous toxic compounds like SMZ, making LYC a functional aquatic feed ingredient for aquiculture.

The global research trend on cadmium in freshwater: a bibliometric review

Cadmium pollution turns out to be a global environmental problem. This study conducted a quantitative and qualitative bibliometric analysis based on 9188 research items from the Web of Science Core Collection published in the last 20 years (2000-2020), presenting an in-depth statistical investigation of global freshwater cadmium research progress and developing trend. Our results demonstrated that the researchers from China, the USA, and India contribute the most to this field. The primary sources of cadmium are mining, industry, wastewater, sedimentation, and agricultural activities. In developing countries, cadmium exposure occurs mainly through the air, freshwater, and food. Fish and vegetables are the main food sources of cadmium for humans because of their high accumulation capability. Source evaluation, detection, and remediation represent the main technologies used to clean up cadmium-contaminated sites. To mitigate the risk of cadmium contamination in freshwater, biomarker-based cadmium monitoring methods and integrated policies/strategies to reduce cadmium exposure merit further concern.

Dibutyl phthalate-induced oxidative stress, inflammation and apoptosis in grass carp hepatocytes and the therapeutic use of taxifolin

The widespread use of plastic products has led to the widespread presence of plasticizers in the environment. As a common environmental pollutant, research on plasticizer toxicity is insufficient in fish cells. In particular, research on the toxicity of dibutyl phthalate (DBP) in grass carp hepatocyte lines is insufficient. To further explore these mechanisms, we treated grass carp hepatocytes with 300 μM DBP, a common plasticizer, for 24 h, and hepatocytes were also treated with 1 μM taxifolin (TAX), an antioxidant, for 24 h to study its antagonistic effect on DBP. After DBP exposure, oxidative stress levels and inflammation in hepatocytes increased, and the mRNA and protein expression of apoptosis-related markers increased significantly, leading to hepatocyte apoptosis. Moreover, AO/EB staining, Hoechst staining and flow cytometry also showed that the level of apoptotic cells increased after DBP exposure. Notably, both TAX pretreatment and TAX simultaneous treatment alleviated oxidative stress, increased inflammatory factor levels and apoptosis induced by DBP. In comparison, the effect of simultaneous TAX treatment was better than that of TAX pretreatment. Our results showed that TAX alleviates DBP-induced apoptosis in grass carp hepatocytes through oxidative stress and inflammation, and TAX pretreatment and simultaneous treatment exhibited specific effects. Specifically, simultaneous treatment had a better effect. Our study assessed the toxicity of DBP in grass carp hepatocytes and provided a theoretical and research basis for the in vivo study of animal models in the future. The innovation of this study involves the exploration of the interaction between DBP and TAX for the first time. This study may enrich knowledge regarding the theoretical mechanism of DBP toxicity in fish hepatocytes and propose methods address DBP toxicity.

Cadmium-induced Oxidative Stress and Immunosuppression Mediated Mitochondrial Apoptosis via JNK-FoxO3a-PUMA pathway in Common Carp (Cyprinus carpio L.) Gills

Cadmium (Cd)-caused water environment pollution has become a matter of concern. Gill is an organ with respiratory and mucosal immune functions, and is also one of the organs directly attacked by pollutants. It was found that excess Cd could cause Cd accumulation and gill injury in carp. However, the mechanism of Cd-caused damage in common carp gills is still unclear. Oxidative stress, immunosuppression, and apoptosis took part in the mechanism of poisoning caused by some harmful substances. The aim of the study was to investigate complex molecular mechanism of apoptotic injury caused by Cd in common carp gills. Hence, in this study, we established a Cd poisoning model to explore whether excess Cd can induce apoptosis through observing histomorphology and apoptotic cells; and determining mineral elements, oxidative stress-related factors, immune-related, and apoptosis-related genes in common carp gills. Fifty-four fish were randomly separated into the control group and the Cd group and were cultured for 45 days. The water of the control group was drinking water and the water of the Cd group was CdCl₂-added drinking water (0.26 mg/L Cd). In our results, we found that excess Cd increased Cd level, decreased the levels of essential mineral elements (Cu, Fe, Zn, and Mn), damaged mitochondria, and increased apoptotic cells in common carp gills, meaning that excess Cd caused Cd accumulation and apoptotic injury via mitochondrion in common carp gills. Furthermore, we found that Cd inhibited anti-apoptosis-related gene Bcl-2 and stimulated pro-apoptosis-related genes (JNK, FoxO3a, PUMA, Bax, Apaf-1, Caspase-9, and Caspase-3) on 15th, 30th, and 45th days. Above data meant that Cd exposure caused apoptosis via mitochondrion and JNK-FoxO3a-PUMA pathway in common carp gills. In addition, in our experiment, Cd treatment increased oxidants (H₂O₂ and MDA) and decreased antioxidants (CAT, GPx, GST, SOD, T-AOC, and GSH), indicating that Cd caused oxidative stress via oxidation/antioxidation imbalance. Meanwhile, compared to the control group, T-help 17 (Th17) cell-related factors (IL-17, TNF-α, and RORγ) were up-regulated, regulatory T (Treg) cell-related factors (IL-10 and Foxp3) were down-regulated, and IL-17/IL-10, TNF-α/IL-10, and RORγ/Foxp3 were increased in Cd-exposed group; meaning that excess Cd induced immunosuppression via the imbalance of Th17/Treg cells. Taken together, our findings indicated that JNK-FoxO3a-PUMA pathway and mitochondrion participated in oxidative stress and immunosuppression-mediated apoptosis caused by Cd in common carp (Cyprinus carpio L.) gills. Our data provided new perspectives on the negative effects of heavy metal pollutants on fish.

Novel insights into cytochrome P450 enzyme and solute carrier families in cadmium-induced liver injury of pigs

Cadmium (Cd) is a typical pollutant and carcinogen in environment. Exposure assessment of contaminants is an important component of occupational and environmental epidemiological studies. Early studies of Cd have focused on aquatic animals, chickens and rats. However, toxicological evaluation of Cd in pigs has not been reported. Therefore, twelve pigs were randomly divided into two groups (n = 6): the control group and the Cd group (Cd content: 15 ± 0.242 mg/kg feed) in this study, the experimental period was 30 d, and the toxic effects of Cd on the liver of weanling piglets were examined by antioxidant function, liver function, Cd content, histological examination and transcriptomics. The results showed that the changes of antioxidant function, liver function and Cd content were significant in the liver. Transcriptional profiling results showed that 399 differentially expressed genes (DEGs) were significantly up-regulated while 369 DEGs were remarkably down-regulated in Cd group, and which were concentrated in three ontologies: molecular function, cellular component and biological processes. Interestingly, significant changes in some genes of the cytochrome P450 enzyme (CYP450) and solute carrier (SLC) families have been observed and were consistent with qRT-PCR results. In conclusion, Cd could cause liver injury in weanling piglets and change the transcriptomic characteristics of liver. CYP450 and SLC families play an indispensable role in Cd-mediated hepatotoxicity. Importantly, changes in mRNA levels of CYP2B22, CYP7A1, CYP8B1, SLC26A8, SLC11A1, SLC27A2 and SLC22A7 induced by Cd have been reported for the first time. Our findings will provide a new insight for better assessing the mechanism of Cd toxicity to the liver.

Cadmium exposure induces inflammation through the canonical NF-κΒ pathway in monocytes/macrophages of Channa punctatus Bloch

A vast range of research related to the toxicity of the heavy metal cadmium (Cd) has been carried out in a wide variety of fish species. However, Cd induced immunomodulation in monocytes/macrophages of Channa punctatus Bloch. has rarely been explored. The present study was designed to determine Cd induced immune response, role of NF-κB (nuclear factor kappa B) pathway and the subsequent downstream molecular responses in monocytes/macrophages of C. punctatus. Fish were sampled and acclimatized, with one group treated with cadmium chloride (CdCl₂) (1.96 mg/L) and another kept as untreated control group, both under observation for 7 days. Exposure to CdCl₂ was found to alter hematological profile of C. punctatus in addition to incurring histo-architectural damages in the HK (head kidney) and ultrastructural changes in the monocytes/macrophages. The innate immune potential was found to be significantly compromised as evident from decreased phagocytosis, intracellular killing, cell adhesion and reduced release of nitric oxide (NO) and myeloperoxidase (MPO) in Cd intoxicated group. Also Cd triggered ROS generation, reduced cellular NO levels by forming peroxynitrite along with the upregulated expression of the inflammatory marker iNOS (inducible nitric oxide synthase) in monocytes/macrophages, both at mRNA and protein levels, indicating inflammation. Inflammation is further verified from the upregulated expression of proinflammatory cytokines viz. TNF-α, IL-1β, IL-6, IL-12 along with a central inflammatory mediator NF-κΒ and downregulation of the anti-inflammatory cytokine IL-10, both at mRNA and protein levels. It can be concluded that, a sub-lethal exposure of Cd in C. punctatus for 7 days caused significant alterations in the hematological, histological and ultrastructural profile in monocytes/macrophages; impaired innate immune parameters, triggers ROS generation and inflammation as validated from the upregulated expression of NF-κΒ, iNOS, TNF-α, IL-1β, IL-6, IL-12 and IL-10 downregulation.

NLRP3 inflammasome mediated pyroptosis is involved in cadmium exposure-induced neuroinflammation through the IL-1β/IkB-α-NF-κB-NLRP3 feedback loop in swine

Cadmium (Cd) chloride, as widely distributed toxic environmental pollutants by using in industry, severely imperils animal and human health. Pyroptosis is a Cas1-dependent pro-inflammatory programmed cell death and involves in various types of diseases. Nevertheless, the mechanism of pyroptosis and Cd-induced neurotoxicity remains obscure. To investigate the specific molecular mechanisms of Cd-induced neurotoxicity, 10 weaned piglets were randomly divided into 2 groups treated with 0 and 20 mg/kg CdCl₂ in the diet for 40 days. The levels of pyroptosis, mitochondrial and inflammation-related genes were validated by qRT-PCR and WB in vivo. Our results revealed that Cd caused cerebral histopathology lesions, inducing cerebral pyroptosis and the mass generation of inflammatory cytokines, as indicated by the increased NLRP3 inflammasome activation (NLRP3, Cas1 and ASC) and the upregulation of inflammation factors IL-2, IL-6, IL-7 and inhibition of IL-10. Subsequently, further research indicated that Cd triggered pyroptosis via activating the TRAF6-IkB-α-NF-κB pathway, which interfered with the phosphorylation and ubiquitination of IkB-α. Furthermore, Cd caused mitochondrial dysfunction and fragmentation by inhibiting the AMPK-PGC-1α-NRF1/2 signaling pathway and reduced the expression of mitochondrial-related regulatory factors OPA1, TFAM and mtDNA, resulting in the increase of NLRP3 inflammasome. Besides, we found eight hub genes (IKK, IKB-α, NLRP3, TRAF6, NF-κB, AMPK, TNFα and PGC-1α), mainly related to the interaction between the NF-κB pathway and NLRP3 inflammasome. Overall, these results demonstrated that Cd could promote the IL-1β/IkB-α-NF-κB-NLRP3 inflammasome activation positive feedback loop to result in neuroinflammation in swine, which provided new insights in understanding Cd-induced toxicity.

Cadmium exposure induces mitochondrial pathway apoptosis in swine myocardium through xenobiotic receptors-mediated CYP450s activation

Cadmium (Cd) pollution has become an important public and environmental health issue. Xenobiotic receptors (XRs, aryl hydrocarbon receptor, AHR; constitutive androstane receptor, CAR; pregnane X receptor, PXR) modulate downstream cytochrome P450 enzymes (CYP450s) expression to metabolize xenobiotics and environmental contaminants. However, the underlying mechanisms of cardiotoxicity induced by Cd(II) in swine and the roles of XRs and CYP450s remain poorly understood. In this study, the cardiotoxicity of Cd(II) was investigated by establishing a Cd(II)-exposed swine model (CdCl₂, 20 mg Cd/Kg diet). Terminal-deoxynucleotidyl transferase mediated nick end labeling (TUNEL) assay and transmission electron microscope were used to observe the apoptosis. Antioxidant capacity was evaluated by free radicals contents and antioxidant enzymes activities. RT-PCR and western blot were used to measure the expression of XRs, CYP450s and apoptosis-related genes. Our results revealed that Cd(II) exposure activated the XRs and increased the CYP450s expression, contributing to the production of reactive oxygen species (ROS). Cd(II) exposure restrained the antioxidant capacity, causing oxidative stress. Moreover, mitogen-activated protein kinase (MAPK) pathway including c-Jun N-terminal kinase (JNK), extracellular signal-regulated kinase (ERK) and P38 mitogen-activated protein kinase (P38) was activated, triggering the mitochondrial apoptotic pathway. In brief, we concluded that Cd(II) caused mitochondrial pathway apoptosis in swine myocardium via the oxidative stress-MAPK pathway, and XRs-mediated CYP450s expression might participate in this process through promoting the ROS.

Antagonistic effect of VDR/CREB1 pathway on cadmium-induced apoptosis in porcine spleen

Cadmium (Cd) is a toxic trace element that can enter the environment with industrial waste and accumulate in the body but the health effects of Cd on ternary pigs are still lacking in research. In order to explore the effect of Cd on the apoptosis of pig spleen and its mechanism, this study chose ternary pig as the research object to detect relevant indicators in pig spleen under Cd exposure. The results of this study showed that Cd exposure can induce apoptosis by promoting the absorption of various toxic trace elements in the spleen and inducing oxidative stress. We also found that the mechanism of Cd-induced apoptosis is closely related to the VDR/CREB1 pathway. On the one hand, Cd exposure can activate VDR, and indirectly regulate the CYP family, affecting the normal function of the spleen. On the other hand, VDR and its downstream genes antagonize the toxicity of Cd by maintaining the stability of the mitochondrial-related endoplasmic reticulum membrane structure. Our research will help researchers to further understand the physiological toxicity of Cd.

Cadmium induces apoptosis of pig lymph nodes by regulating the PI3K/AKT/HIF-1α pathway

OBJECTIVE

This study was aimed to explore the possible mechanism of environmental metal cadmium (Cd) inducing apoptosis of pig lymph nodes.

METHOD

10 healthy 6-week-old weaned piglets were randomly divided into two groups (n = 5 pigs/group). The control group was fed with a basic diet, and the test group was fed with a basic diet of 20 mg/kg CdCl₂.

RESULTS

The Cd deposition in mesenteric lymph nodes (MLN), inguinal lymph nodes (ILN) and submaxillary lymph nodes (SLN) after Cd exposure was 2.37 folds, 1.4 folds and 1.8 folds of the control group, respectively. And the rate of MLN and ILN apoptotic cells in the Cd group was 4.11 folds and 9.18 folds of the control group, respectively. The mRNA levels of SOD1, SOD2, CAT, GPX1 and GSH in the Cd group were reduced. Similarly, the two-phase detoxification enzymes had a significant downward trend. Cd exposure decreased the activities of GSH, GSH-Px, SOD, CAT, and increased H₂O₂ and MDA levels. The mRNA and protein levels of Drp1 and Mff in the Cd group were higher than the corresponding control group, and the mRNA and protein levels of Mfn1 and Mfn2 were lower than those in the control group. In addition, the mRNA and protein levels of pro-apoptotic genes in the Cd group were lower than those in the control group. Cd can significantly reduce the expression of PI3K, AKT and HIF-1α in the three lymph nodes. In summary, Cd induces oxidative stress and regulates the PI3K/AKT/HIF-1α signal transduction pathway to cause mitochondrial dynamics disorder, which leads to the apoptosis of pig lymph nodes, suggesting that Cd-induced mitochondrial pathway apoptosis is related to Cd pig lymph nodes play an important role in the toxicity mechanism.

Zinc offers splenic protection through suppressing PERK/IRE1-driven apoptosis pathway in common carp (Cyprinus carpio) under arsenic stress

Arsenic (As) occurs naturally and concentrations in water bodies can reach high levels, leading to accumulation in vital organs like the spleen. Being an important organ in immune response and blood development processes, toxic effects of As on the spleen could compromise immunity and cause associated disorders in affected individuals. Splenic detoxification is key to improving the chances of survival but relatively little is known about the mechanisms involved. Essential trace elements like zinc have shown immune-modulatory effects humans and livestock. This study aimed to investigate the mechanisms involved in As-induced splenic toxicity in the common carp (Cyprinus carpio), and the protective effects of zinc (Zn). Our findings suggest that environmental exposure to As caused severe histological injuries and Ca²⁺ accumulation in the spleen of common carp. Additionally, transcriptional and translational profiles of endoplasmic reticulum stress, apoptosis and autophagy-related genes of the spleen showed upward trends under As toxicity. Treatment with Zn appears to offer protection against As-induced splenic injury in common carp and the pathologic changes above were alleviated. Our results provide additional insight into the mechanism of As toxicity in common carp while elucidating the role of Zn, a natural immune-modulator, as a potential antidote against As poisoning.