Nickel chloride (NiCl2) in hepatic toxicity: apoptosis, G2/M cell cycle arrest and inflammatory response

E-Cigarette effects on oral health: A molecular perspective

Electronic cigarettes (e-cigarettes) have emerged as a potential alternative to traditional smoking and may aid in tobacco harm reduction and smoking cessation. E-cigarette use has notably increased, especially among young non-tobacco users, raising concerns due to the unknown long-term health effects. The oral cavity is the first and one of the most crucial anatomical sites for the deposition of e-cigarette aerosols. E-cigarette aerosols contain nicotine, flavors, volatile organic compounds, heavy metals, carcinogens, and other hazardous substances. These aerosols impact the oral cavity, disrupting host-microbial interactions and triggering gingivitis and systemic diseases. Furthermore, oral inflammation and periodontitis can be caused by proinflammatory cytokines induced by e-cigarette aerosols. The toxic components of e-cigarette aerosols increase the cellular reactive oxygen species (ROS) levels, reduce antioxidant capacity, increase DNA damage, and disrupt repair processes, which may further contribute to harmful effects on oral epithelum, leading to inflammatory and pre-malignant oral epithelial lesions. In this review, we analyze the toxicological properties of compounds in e-cigarette aerosols, exploring their cytotoxic, genotoxic, and inflammatory effects on oral health and delving into the underlying molecular mechanisms. Further research is essential to understand the impact of e-cigarettes on oral health and make informed regulatory decisions based on reliable scientific evidence.

Effects of hesperidin on the histological structure, oxidative stress, and apoptosis in the liver and kidney induced by NiCl2

The aim of this study was to investigate the effect of hesperidin on the liver and kidney dysfunctions induced by nickel. The mice were divided into six groups: nickel treatment with 80 mg/kg, 160 mg/kg, 320 mg/kg hesperidin groups, 0.5% CMC-Na group, nickel group, and blank control group. Histopathological techniques, biochemistry, immunohistochemistry, and the TUNEL method were used to study the changes in structure, functions, oxidative injuries, and apoptosis of the liver and kidney. The results showed that hesperidin could alleviate the weight loss and histological injuries of the liver and kidney induced by nickel, and increase the levels of lactate dehydrogenase (LDH), alanine aminotransferase (GPT), glutamic oxaloacetic transaminase (GOT) in liver and blood urea nitrogen (BUN), creatinine (Cr) and N-acetylglucosidase (NAG) in kidney. In addition, hesperidin could increase the activities of superoxide dismutase (SOD), catalase (CAT), glutathione (GSH), and glutathione peroxidase (GSH-Px) in the liver and kidney, decrease the content of malondialdehyde (MDA) and inhibit cell apoptosis. It is suggested that hesperidin could help inhibit the toxic effect of nickel on the liver and kidney.

Apoptosis and DNA damage mediated by ROS involved in male reproductive toxicity in mice induced by Nickel

Nickel (Ni) is the most important environmental pollution in the world. Ni has been confirmed to have multi-organ toxicology and carcinogenicity. Recently, Ni also can impair the male reproductive system, however, its precious mechanism still has not been clarified. The current work found that nickel chloride (NiCl2) induced histopathological lesions in testis. And, the Johnsen's score, seminiferous tubule diameter, and spermatogenic epithelium thickness were decreased in NiCl2-treated mice. The number of spermatogonium, primary spermatocyte, and round spermatid also were significantly reduced after Ni treatment. Next the potential molecular mechanism was measured. NiCl2 treatment elevated ROS production in the testis. Additionally, NiCl2 was found to induce apoptosis with features including up-regulation of Bax, cleaved-caspase-3, cleaved-caspase-8, caspase-9, and caspase-12, while down-regulation of Bcl-2 expression. In the meantime, the marker protein of DNA damage γ-H2AX was significantly increased in NiCl2-primed mice testis. To clarify effects of reactive oxygen species (ROS) in apoptosis and DNA damage induced by NiCl2, NiCl2 was used to co-treat antioxidant NAC (N-Acetyl-L-cysteine). NAC weakened ROS production induced by NiCl2, and played an inhibition role in apoptosis and DNA damage. Moreover, co-treatment using NiCl2 and NAC group also eliminated spermatogenesis disorders. In summary, research results reveal the relations of spermatogenesis disorder induced by NiCl2 with apoptosis and DNA damage mediated by ROS and apoptosis in the testis.

Nickel induces blood-testis barrier damage through ROS-mediated p38 MAPK pathways in mice

Nickel (Ni) is an essential common environmental contaminant, it is hazardous to male reproduction, but the precise mechanisms are still unknown. Blood-testis barrier (BTB), an important testicular structure consisting of connections between sertoli cells, is the target of reproductive toxicity caused by many environmental toxins. In this study, ultrastructure observation and BTB integrity assay results indicated that NiCl2 induced BTB damage. Meanwhile, BTB-related proteins including the tight junction (TJ), adhesion junction (AJ) and the gap junction (GJ) protein expression in mouse testes as well as in sertoli cells (TM4) were significantly decreased after NiCl2 treatment. Next, the antioxidant N-acetylcysteine (NAC) was co-treated with NiCl2 to study the function of oxidative stress in NiCl2-mediated BTB deterioration. The results showed that NAC attenuated testicular histopathological damage, and the expression of BTB-related proteins were markedly reversed by NAC co-treatment in vitro and vivo. Otherwise, NiCl2 activated the p38 MAPK signaling pathway. And, NAC co-treatment could significantly inhibit p38 activation induced by NiCl2 in TM4 cells. Furthermore, in order to confirm the role of the p38 MAPK signaling pathway in NiCl2-induced BTB impairment, a p38 inhibitor (SB203580) was co-treated with NiCl2 in TM4 cells, and p38 MAPK signaling inhibition significantly restored BTB damage induced by NiCl2 in TM4 cells. These results suggest that NiCl2 treatment destroys the BTB, in which the oxidative stress-mediated p38 MAPK signaling pathway plays a vital role.

Nickel induces hepatotoxicity by mitochondrial biogenesis, mitochondrial dynamics, and mitophagy dysfunction

Nickel (Ni) is an important and widely hazardous chemical industrial waste. Excessive Ni exposure could cause multi-organs toxicity in human and animals. Liver is the major target organ of Ni accumulation and toxicity, however, the precise mechanism is still unclear. In this study, nickel chloride (NiCl₂ )-treatment induced hepatic histopathological changes in the mice, and, transmission electron microscopy results showed mitochondrial swollen and deformed of hepatocyte. Next, the mitochondrial damages including mitochondrial biogenesis, mitochondrial dynamics, and mitophagy were measured after NiCl₂ administration. The results showed that NiCl₂ suppressed mitochondrial biogenesis by decreasing PGC-1α, TFAM, and NRF1 protein and mRNA expression levels. Meanwhile, the proteins involved in mitochondrial fusion were reduced by NiCl₂ , such as Mfn1 and Mfn2, however, mitochondrial fission proteins Drip1 and Fis1 were significantly increased. The up-regulation of mitochondrial p62 and LC3II expression indicated that NiCl₂ increased mitophagy in the liver. Moreover, the receptor-mediated mitophagy and ubiquitin (Ub)-dependent mitophagy were detected. NiCl₂ promoted PINK1 accumulation and Parkin recruitment on mitochondria. And, the receptor proteins of mitophagy Bnip3 and FUNDC1 were increased in the NiCl₂ -treated mice liver. Overall, these results show that NiCl₂ could induce mitochondria damage in the liver of mice, and, dysfunction of mitochondrial biogenesis, mitochondrial dynamics and mitophagy involved in the molecular mechanism of NiCl₂ -induced hepatotoxicity.

Endoplasmic reticulum stress mediates nickel chloride-induced epithelial‑mesenchymal transition and migration of human lung cancer A549 cells through Smad2/3 and p38 MAPK activation

BACKGROUND

The endoplasmic reticulum (ER) is a cellular membrane-bound organelle whereby proteins are synthesized, folded and glycosylated. Due to intrinsic (e.g., genetic) and extrinsic (e.g., environmental stressors) perturbations, ER proteostasis can be deregulated within cells which triggers unfolded protein response (UPR) as an adaptive stress response that may impact the migration and invasion properties of cancer cells. However, the mechanisms underlying the nickel compounds on lung cancer cell migration and invasion remain uncertain.

OBJECTIVE

We aimed to study whether Nickel chloride (NiCl₂) induces ER stress in lung cancer cells, and whether ER stress is involved in modulating epithelial-mesenchymal transition (EMT) and migration by Smads and MAPKs pathways activation following NiCl₂ treatment.

METHODS

A549 cells were treated with NiCl₂ to determine the cell viability using MTT assay. The wound healing assay was used to evaluate cell migration ability. ER ultrastructure was observed by transmission electron microscopy. Western blotting assay was performed to evaluate the protein levels of BIP, PERK, IRE-1α, XBP-1 s, and ATF6 for ER stress and UPR, E-cadherin and Vimentin for EMT, p-Smad2/3, p-ERK, p-JNK, and p-P38 for activation of Smads and MAPKs signaling pathways.

RESULTS

The expression levels of BIP, PERK, IRE-1α, XBP-1 s, and ATF6 were significantly increased following treatment with NiCl₂ in time- and dose-effect relationship. The ER stress inhibitor 4-PBA downregulated the expression levels of the above five proteins, and reversed the decrease in E-cadherin protein level and the increase in vimentin protein expression and cell migration abilities caused by NiCl₂. Furthermore, 4-PBA significantly reduced nickel chloride-induced Smad2/3 and p38 MAPK pathway activation, while not affected ERK and JNK MAPK pathways.

CONCLUSION

NiCl₂ triggers ER stress and UPR in A549 cells. Moreover, 4-PBA alleviates NiCl₂-induced EMT and migration ability of A549 cells possibly through the Smad2/3 and p38 MAPK pathways activation, rather than ERK and JNK MAPK pathways.

Mechanism of effects of nickel or nickel compounds on intestinal mucosal barrier

As an important metal in industry, national defense, and production, nickel widely exists in nature and is also a necessary trace element for human beings and animals. Nickel deficiency will affect the growth and development of animals, the contents of related active substances, enzymes and other essential elements in vivo. However, excessive nickel or longer nickel exposure can induce excessive free radicals (reactive oxygen species and reactive nitrogen) in the body, which can lead to a variety of cell damage, apoptosis and canceration, and ultimately pose negative effects on the health of the body. Among them, the intestinal tract, as the largest interface between the body and the external environment, greatly increases the contact probability between nickel or nickel compounds and the intestinal mucosal barrier, thus, the intestinal structure and function are also more vulnerable to nickel damage, leading to a series of related diseases such as enteritis. Therefore, this paper briefly analyzed the damage mechanism of nickel or its compounds to the intestinal tract from the perspective of four intestinal mucosal barriers: mechanical barrier, immune barrier, microbial barrier and chemical barrier, we hope to make a certain theoretical contribution to the further research and the prevention and treatment of nickel related diseases.

Investigation of nickel sulfate-induced cytotoxicity and underlying toxicological mechanisms in human umbilical vein endothelial cells through oxidative stress, inflammation, apoptosis, and MAPK signaling pathways

Growing evidence indicates that nickle and its compounds have adverse effects on the cardiovascular system. In this study, the cytotoxic insults caused by nickel sulfate (NiSO₄ ) in human umbilical vein endothelial cells (HUVECs) were explored by examining cell viability, oxidative stress, inflammation, apoptosis, and MAPK signaling pathway activity. Cultured HUVECs were treated with varying concentrations of NiSO₄ (0, 62.5, 250, and 1000 μM) for 24 h. Subsequently, markers of oxidative stress, inflammation, apoptosis, and MAPK signaling pathways were analyzed using biochemical assays, real-time quantitative polymerase chain reaction, and western blot. Rates of apoptosis were evaluated using flow cytometry. The results showed that NiSO₄ exerted dose- and time-dependent inhibitory effects on cell growth. It induced oxidative stress and lipid peroxidation by increasing the generation of reactive oxygen species, the oxidized glutathione to reduced glutathione ratio (GSSG/GSH ratio), and malondialdehyde levels. Further, it inhibited superoxide dismutase activity in HUVECs. Flow cytometry analysis results revealed that NiSO₄ (62.5-1000 μM) could induce apoptosis in HUVECs. The protein and gene expressions of cleaved Caspase 3 and Bax were elevated, and those of Bcl-2 and Bcl-XL were reduced after NiSO₄ treatment. Additionally, NiSO₄ triggered inflammation in HUVECs, increasing the protein and mRNA levels of IL-6 and TNF-α and reducing those of TGF-β. Furthermore, western blot findings revealed that NiSO₄ could activate MAPK signaling pathways, upregulating p38, JNK, and ERK1/2 in HUVECs by increasing the levels of p-P38，p-JNK, and p-ERK1/2 in a dose-dependent manner. MAPK pathway inhibitors (10 μM SB203580 and 10 μM SP600125) could attenuate the NiSO₄ -induced increase in apoptosis and inflammation in HUVECs. They could also attenuate the dysregulation of inflammatory factors and related proteins caused by high-dose NiSO₄ exposure. Interestingly, while the MEK inhibitor U0126 (10 μM) enhanced NiSO₄ -induced apoptosis in HUVECs, it reduced cell inflammation. Taken together, these experimental results suggest that NiSO₄ can inhibit cell growth, induce oxidative stress, and trigger subsequent inflammatory responses and apoptosis in HUVECs. These effects may be mediated by the P38 and JNK MAPK stress response pathways.

Chronic heat stress causes liver damage via endoplasmic reticulum stress-induced apoptosis in broilers

Liver is a central metabolic organ, which is sensitive to heat stress. Liver damage affects animals' health and endangers the livestock and poultry industry. This study aimed to investigate the mechanism of chronic heat stress-induced liver damage in broiler chickens. Broilers were divided into 3 treatments: normal control group (NOR, 22°C), heat stress group (HS, 32°C) and pair-feeding group (PF, 22°C) for a 7-d and 14-d trial. The results showed that 7 d heat exposure caused microvesicular steatosis and reduced glutamine synthetase activity in broiler liver (P < 0.05). After 14 d of heat exposure, heat stress caused vacuolar degeneration and apoptosis in the liver; elevated liver relative weight and liver glutaminase activity as well as plasma ammonia level (P < 0.05). Additionally, heat stress enhanced GRP78 protein expression and the mRNA expressions of endoplasmic reticulum (ER) stress responses genes and apoptosis-related genes in broiler liver after 14 d of heat exposure (P < 0.05). In conclusion, chronic heat stress triggered ER stress-induced apoptosis and caused liver damage, which may compromise ammonia detoxification in broiler liver.

Pathogenesis-Related Gene Expression in Response to Trachyspermum ammi Supplementation Along With Probiotics in Chicken Salmonellosis and Insights in Drug Therapeutics

Salmonella enterica serovar typhimurium (S. typhimurium) is the leading cause of foodborne illness. Since Salmonella continues to have a detrimental effect on public health, there is an ongoing need to develop more advanced methods for combating Salmonellosis in foods before they reach consumers. In addition, the quest for alternative natural products has recently intensified due to increasingly stringent regulations regarding the use of antibiotics as growth promoters and consumer demand for antibiotic-free poultry products. This study evaluated the effect of Ajwain extract (AJE) on immune response and antioxidant status in broiler chicks challenged with Salmonella typhimurium. The chicks were infected with S. typhimurium and were divided into the different groups, except for the control group (CON). The challenged chicks received different treatments with 3 × 109 colony-forming unit (CFU) AciproTM-WS probiotic (PRO), 200 mg/kg Ajwain extract (AJE), 200 mg/100 kg of enrofloxacin (ENR), and a combination of 3 × 109 CFU AciproTM-WS probiotic and 200 mg/kg Ajwain extract (COM). Five days posttreatment, the tissue samples (liver and spleen) were analyzed. The results showed that basal diet supplemented with Ajwain extract (AJE) and a combination of probiotic and Ajwain extract (COM) significantly (P &lt; 0.0.5) reduced the cytokine expression in broiler chicks challenged with S. typhimurium. Our findings suggest that AJE can clear the bacterial infection, improve antioxidant status, and suppress the inflammation response. Additionally, AJE supplementation significantly mitigated the S. typhimurium-induced increase in the interleukin-6 (IL-6) (liver and spleen), interleukin-8 (IL-8) (liver and spleen), interleukin-17A (IL-17A) (liver and spleen), and inducible nitric oxide (iNOS) (spleen and liver) levels (P &lt; 0.05). We conclude that Ajwain is an efficient feed additive with antioxidant and anti-inflammatory properties. The interaction networks developed in this study provide a novel lead that could be targeted for anti-inflammatory and antioxidant properties.

Nickel's Role in Pancreatic Ductal Adenocarcinoma: Potential Involvement of microRNAs

Pancreatic ductal adenocarcinoma (PDAC) is one of the most lethal cancer types with a limited overall survival rate due to the asymptomatic progression of symptoms in metastatic stages of the malignancy and the lack of an early reliable diagnostic biomarker. MicroRNAs (miRs/miRNAs) are small (~18–24 nucleotides), endogenous, non-coding RNAs, which are closely linked to the development of numerous malignancies comprising PDAC. Recent studies have described the role of environmental pollutants such as nickel (Ni) in PDAC, but the mechanisms of Ni-mediated toxicity in cancer are still not completely understood. Specifically, Ni has been found to alter the expression and function of miRs in several malignancies, leading to changes in target gene expression. In this study, we found that levels of Ni were significantly higher in cancerous tissue, thus implicating Ni in pancreatic carcinogenesis. Hence, in vitro studies followed by using both normal and pancreatic tumor cell lines and increasing Ni concentration increased lethality. Comparing LC50 values, Ni-acetate groups demonstrated lower values needed than in NiCl₂ groups, suggesting greater Ni-acetate. Panc-10.05 cell line appeared the most sensitive to Ni compounds. Exposure to Ni-acetate resulted in an increased phospho-AKT, and decreased FOXO1 expression in Panc-10.05 cells, while NiCl₂ also increased PTEN expression in Panc-10.05 cells. Specifically, following NiCl₂ exposure to PDAC cells, the expression levels of miR-221 and miR-155 were significantly upregulated, while the expression levels of miR-126 were significantly decreased. Hence, our study has suggested pilot insights to indicate that the environmental pollutant Ni plays an important role in the progression of PDAC by promoting an association between miRs and Ni exposure during PDAC pathogenesis.

Nano-selenium attenuates mitochondrial-associated apoptosis via the PI3K/AKT pathway in nickel-induced hepatotoxicity in vivo and in vitro

The aim of this study was to investigate the protective effects of Nano-Se against nickel (Ni)-induced hepatotoxicity and the potential mechanism. Hence, we constructed in vivo and in vitro models of Ni-induced hepatotoxicity. Sprague-Dawley (SD) rats were exposed to nickel sulfate (NiSO₄ , 5.0 mg/kg, i.p.) with or without Nano-Se (0.5, 1, and 2 mg/kg, oral gavage) co-administration for 14 days, and HepG2 cells were exposed to NiSO₄ (1500 μM) with or without Nano-Se (20 μM) for 24 h. Nano-Se obviously prevented Ni-induced hepatotoxicity indicated by ameliorating pathological change and decreasing Ni accumulation in rat livers. Ni induced a significant increase in hepatic activities of superoxide dismutase (SOD), catalase (CAT), glutathione reductase (GSH-Px), and malondialdehyde (MDA) level, decreased the glutathione (GSH) content while compared to those in the control group. Nano-Se administration improved the hepatic antioxidant capacity through increase hepatic GSH contents and GSH-Px activity, decrease the activities of SOD, CAT, and MDA level. Nano-Se improved the cell viability, decreased active oxygen (ROS) generation and ameliorated morphological changes of nuclear structures in Ni-treated HepG2 cells. In addition, Nano-Se inhibited the Ni-induced increases of cytochrome c, caspase-9, cleaved caspase-3, increased PI3K and AKT phosphorylation both in vivo and in vitro. Besides, the PI3K inhibitor Y294002 could inhibit the protective effects of Nano-Se on apoptosis. Thus, Nano-Se significantly activates PI3K/AKT signaling to ameliorate apoptosis in Ni-induced hepatotoxicity.

Mitochondria damage and ferroptosis involved in Ni-induced hepatotoxicity in mice

Nickel (Ni) is an environmental toxicant that can cause toxic damage to humans and animals. Although the hepatotoxicity of Ni has been confirmed, its precise mechanism is still unclear. In this study, the results showed that nickel chloride (NiCl₂)-treatment could induce mice hepatotoxicity including hepatic histopathological alterations and up-regulation of serum AST and ALT. According to the results, NiCl₂ increased malondialdehyde (MDA) production while reducing total antioxidant capacity (T-AOC) activity and glutathione (GSH) content. Additionally, NiCl₂ induced mitochondrial damage which was featured by increase in mitochondrial ROS (mt-ROS) and mitochondrial membrane potential (MMP) depolarization. The mitochondrial respiratory chain complexes I-IV and ATP content were decreased in the liver of NiCl₂-treated mice. Meanwhile, NiCl₂ caused hepatic ferroptosis accompanied by increased iron content in the liver and up-regulation of cyclooxygenase 2 (COX-2) protein and mRNA expression levels, down-regulation of glutathione eroxidase 4 (GPX4), ferritin heavy chain 1 (FTH1) and nuclear receptor coactivator 4 (NCOA4) protein and mRNA expression levels. Altogether, the above mentioned results indicate that NiCl₂ treatment may induce hepatic damage through mitochondrial damage and ferroptosis.

Nickel induces autophagy via PI3K/AKT/mTOR and AMPK pathways in mouse kidney

Nickel (Ni), a widely distributed metal, is an important pollutant in the environment. Although kidney is a crucial target of Ni toxicity, information on autophagy and the potential mechanisms of Ni-induced renal toxicity are still poorly described. As we discovered, NiCl₂ could induce renal damage including decrease in renal weight, renal histological alterations, and renal function injury. According to the obtained results, NiCl₂ could obviously increase autophagy, which was characterized by increase of LC3 expression and decrease of p62 expression. Meanwhile, the result of ultrastructure observation showed increased autolysosomes numbers in the kidney of NiCl₂-treated mice. In addition, NiCl₂ increased mRNA and protein levels of autophagy flux proteins including Beclin1, Atg5, Atg12, Atg16L1, Atg7, and Atg3. Furthermore, NiCl₂ induced autophagy through AMPK and PI3K/AKT/mTOR pathways which featured down-regulated expression levels of p-PI3K, p-AKT and p-mTOR and up-regulated expression levels of p-AMPK and p-ULK1. In summary, the above results indicate involvement of autophagy in renal injury induced by NiCl₂, and NiCl₂ induced autophagy via PI3K/AKT/mTOR and AMPK pathways in mouse kidney.

Impact of Dietary or Drinking Water Ruminococcus sp. Supplementation and/or Heat Stress on Growth, Histopathology, and Bursal Gene Expression of Broilers

This research was conducted to evaluate the impact of dietary or drinking water Ruminococcus sp. supplementation and/or heat stress (HS) on the growth, serum biochemistry, tissue antioxidant, phagocytic assay, histopathology, and bursa gene expression of broilers. Day-old broiler chicks were allotted into six groups according to HS and/or Ruminococcus with or without enzyme supplementation. The first group was the control one, with a formulated diet and normal environmental temperature but without any supplement. The second group fed on Ruminococcus-supplemented diet (1 kg/kg diet). The third group fed on a formulated diet without supplement, and Ruminococcus and digestive enzymes were given in drinking water (0.1 ml/L). The fourth one was the heat stress group, with a normal formulated diet. The fifth and the sixth groups served as second and third groups, respectively, but with heat stress. The results of this experiment indicated that thermal temperature negatively affected the parameters of growth performance, serum biochemical, tissue antioxidants, and phagocytic assay. Moreover, heat stress led to pathological lesions in the internal organs and affected the expression of some genes related to heat stress, including proapoptotic genes such as caspase8 and bax, inflammatory genes such as NF-κβ1, and heat shock protein such as HSP 70 in the bursal tissue. These bad effects and abnormalities were mitigated by Ruminococcus alone or with enzyme supplementation, which improved all the above-mentioned parameters.

The downregulation of NCXs is positively correlated with the prognosis of stage II-IV colon cancer

Purpose

Colon cancer (CC) is a very common gastrointestinal tumor that is prone to invasion and metastasis in the late stage. This study aims to observe the expression of Na⁺/Ca²⁺ exchangers (NCXs) and analyze the correlation between NCXs and the prognosis of CC.

Methods

Specimens of 111 stage II–IV CC patients were collected. We used western blotting, qPCR, and immunohistochemical staining to observe the distributions and expression levels of NCX isoforms (NCX1, NCX2, and NCX3) in CC and distal normal tissues. Cox proportional hazards models were used to assess prognostic factors for patients.

Results

The expression of NCXs in most tumor specimens was lower than that in normal tissues. The NCX expression levels in tumor tissues from the primary tumor, local lymph node metastasis sites, and distant liver metastasis sites were increasingly significantly lower than those in normal tissues. The results of the Kaplan-Meier survival curves showed that the downregulation of any NCX isoform was closely related to the worse prognosis of advanced CC.

Conclusion

NCXs can be used as independent prognostic factors for CC. Our research results are expected to provide new targets for the treatment of CC.

Molecular mechanism of heavy metals (Lead, Chromium, Arsenic, Mercury, Nickel and Cadmium) - induced hepatotoxicity - A review

Heavy metals pose a serious threat if they go beyond permissible limits in our bodies. Much heavy metal's viz. Lead, Chromium, Arsenic, Mercury, Nickel, and Cadmium pose a serious threat when they go beyond permissible limits and cause hepatotoxicity. They cause the generation of ROS which in turn causes numerous injuries and undesirable changes in the liver. Epidemiological studies have shown an increase in the levels of such heavy metals in the environment posing a serious threat to human health. Epigenetic alterations have been seen in the event of exposure to such heavy metals. Apoptosis, caspase activation as well as ultrastructural changes in the hepatocytes have also been seen due to heavy metals. Inflammation involving TNF-alpha, pro-inflammatory cytokines, MAPK, ERK pathways have been seen in the event of heavy metal hepatotoxicity. All these have shown that these heavy metals pose a serious threat to human health in particular and the environment as a whole.

Research progress on the effects of nickel on hormone secretion in the endocrine axis and on target organs

BACKGROUND

Nickel, as one of the most abundant elements in the earth's crust, plays many roles in human reproduction and life. It is an essential trace element for the human body, but can be harmful in excess amounts. Nickel has a significant impact on endocrine hormones in humans and animals, potentially causing abnormal secretions and changing the structure and function of endocrine organs. This article systematically reviews the effects of nickel on hormone secretion and target organs in the endocrine system and identifies areas of insufficient research.

METHODS

All data in this article were extracted from peer-reviewed articles. The PubMed, SciFinder, Google Scholar, Web of Science, and China National Knowledge Infrastructure databases were searched for relevant articles. Data on nickel's effect on endocrine system hormones and target organs were retrieved, and manually sorted prior to inclusion in this review.

RESULTS

Nickel acts on the endocrine system and affects the release and regulation of endocrine hormones. Disorders of endocrine hormones may lead to retardation of human growth and mental development, disturbance of water and salt regulation, and even a decline in reproductive ability. Nickel affects the hypothalamus and pituitary gland by regulating organs upstream of the endocrine axis; it can cause abnormal secretion of pituitary hormones, which affects target organs of the endocrine axis, resulting in dysfunction therein and abnormal secretion of related hormones. Nickel also damages target organs, mainly by inducing apoptosis, which triggers oxidative stress, cell autophagy, free radical release, and DNA damage. However, there are few studies on the endocrine axis, and some of the data are contradictory. Nevertheless, it is clear that nickel affects the endocrine system.

CONCLUSIONS

Nickel can damage organs in the endocrine system, such as the hypothalamus and pituitary. It also affects the secretion of hormones and damages the target organs of these hormones; this can result in endocrine system dysfunction. However, the results have been equivocal and further research is needed.

Nickel carcinogenesis mechanism: cell cycle dysregulation

Nickel (Ni) is a widely distributed metal in the environment and an important pollutant due to its widespread industrial applications. Ni has various toxicity in humans and experimental animals, including carcinogenicity. However, the carcinogenic effects of Ni remain troublesome. Cell cycle dysregulation may be an important carcinogenic mechanism and is also a potential molecular mechanism for Ni complexes anti-cancerous effects. Therefore, we conducted a literature review to summarize the effects of Ni on cell cycle. Up to now, there were three different reports on Ni-induced cell cycle arrest: (i) Ni can induce cell cycle arrest in G0/G1 phase, phosphorylation and degradation of IkappaB kinase-alpha (IKKα)-dependent cyclin D1 and phosphoinositide-3-kinase (PI3K)/serine-threonine kinase (Akt) pathway-mediated down-regulation of expressions of cyclin-dependent kinases 4 (CDK4) play important role in it; (ii) Ni can induce cell cycle arrest in S phase, but the molecular mechanism is not known; (iii) G2/M phase is the target of Ni toxicity, and Ni compounds cause G2/M cell cycle phase arrest by reducing cyclinB1/Cdc2 interaction through the activation of the ataxia telangiectasia mutated (ATM)-p53-p21 and ATM-checkpoint kinase inhibitor 1 (Chk1)/Chk2-cell division cycle 25 (Cdc25) pathways. Revealing the mechanisms of cell cycle dysregulation associated with Ni exposure may help in the prevention and treatment of Ni-related carcinogenicity and toxicology.

Intracellular nickel accumulation induces apoptosis and cell cycle arrest in human astrocytic cells

Nickel, a heavy metal found in electronic wastes and fume from electronic cigarettes, induces neuronal cell death and is associated with neurocognitive impairment. Astrocytes are the first line of defense against nickel after entering the brain; however, the effects of nickel on astrocytes remain unknown. Herein, we investigated the effect of nickel exposure on cell survival and proliferation and the underlying mechanisms in U-87 MG human astrocytoma cells and primary human astrocytes. Intracellular nickel levels were elevated in U-87 MG cells in a dose- and time-dependent manner after exposure to nickel chloride. The median toxic concentrations of nickel in astrocytoma cells and primary human astrocytes were 600.60 and >1000 µM at 48 h post-exposure, respectively. Nickel exposure triggered apoptosis in concomitant with the decreased expression of anti-apoptotic B-cell lymphoma protein (Bcl-2) and increased caspase-3/7 activity. Nickel induced reactive oxygen species formation. Additionally, nickel suppressed astrocyte proliferation in a dose- and time-dependent manner by delaying G2 to M phase transition through the upregulation of cyclin B1 and p27 protein expression. These results indicate that nickel-induced cytotoxicity of astrocytes is mediated by the activation of apoptotic pathway and disruption of cell cycle regulation.

Immunotoxicity of nickel: Pathological and toxicological effects

Nickel (Ni) is a widely distributed metal in the environment and an important pollutant because of its many industrial applications. With increasing incidences of Ni contamination, Ni toxicity has become a global public health concern and recent evidence suggests that Ni adversely affects the immune system. Hence, this paper reviews the literature on immune-related effects of Ni exposure, the immunotoxicological effects of Ni, and the underlying mechanism of Ni immunotoxicity. The main focus was on the effect of Ni on the development of organs of immune system, lymphocyte subpopulations, cytokines, immunoglobulins, natural killer (NK) cells, and macrophages. Moreover, Ni toxicity also induces inflammation and several studies demonstrated that Ni could induce immunotoxicity. Excessive Ni exposure can inhibit the development of immune organs by excessively inducing apoptosis and inhibiting proliferation. Furthermore, Ni can decrease T and B lymphocytes, the specific mechanism of which requires further research. The effects of Ni on immunoglobulin A (IgA), IgG, and IgM remain unknown and while Ni inhibited IgA, IgG, and IgM levels in an animal experiment, the opposite result was found in research on humans. Ni inhibits the production of cytokines in non-inflammatory responses. Cytokine levels increased in Ni-induced inflammation responses, and Ni activates inflammation through toll like (TL)4-mediated nuclear factor-κB (NF-κB) and signal transduction cascades mitogen-activated protein kinase (MAPK) pathways. Ni has been indicated to inactivate NK cells and macrophages both in vitro and in vivo. Identifying the mechanisms underlying the Ni-induced immunotoxicity may help to explain the growing risk of infections and cancers in human populations that have been exposed to Ni for a long time. Such knowledge may also help to prevent and treat Ni-related carcinogenicity and toxicology.

Heat stress decreases egg production of laying hens by inducing apoptosis of follicular cells via activating the FasL/Fas and TNF-α systems

Heat stress (HS) causes significant economic losses in the poultry industry every year. However, the mechanisms for the adverse effects of HS on avian follicular development are largely unknown. The aim of this study was to test whether HS induces apoptosis of follicular cells and impairs egg production by activating the FasL/Fas and tumor necrosis factor (TNF)-α systems. To this end, Hy-Line Brown laying hens, at 32 wk of age, were either exposed to HS of 35°C to 37°C or maintained at 24°C to 26°C (control) for 5 D. At the end of the HS period, follicle numbers, apoptosis, FasL/Fas and TNF-α activation, oxidative stress, and hormone secretion were examined in ovarian follicles. Egg production was observed daily during both the stressed (day S1–S5) and the poststress recovery (day R1–R15) periods. The results demonstrated that HS on hens significantly 1) decreased laying rates from day S3 to R6; 2) reduced numbers of large yellow and hierarchical follicles; 3) triggered apoptosis while increasing the expression of FasL, Fas, TNF-α, and TNF-receptor 1 in small and large yellow follicles; and 4) increased levels of oxidative stress, corticotrophin-releasing hormone, and corticosterone while decreasing the estradiol/progesterone ratio in follicular fluid in small and large yellow follicles. Taken together, the results suggested that hen HS impaired egg production by reducing the number of follicles through inducing apoptosis and that it triggered apoptosis in follicular cells by activating the FasL/Fas and TNF-α systems.

Removal of dental alloys and titanium attenuates trace metals and biological effects on liver and kidney

To determine whether the potential effects on liver and kidney caused by dental alloys could be reduced or terminated by the removal of nickel-chromium (Ni-Cr) alloy, cobalt-chromium (Co-Cr) alloy, and commercially pure titanium (CP-Ti), they were placed in the cheek pouches of Syrian hamsters according to ISO 10993-10. Then, the peak/plateau and end times of trace metals in the blood were determined with or without the removal of the dental alloys. Based on these time points, the trace metals and their effects on liver and kidney were examined. We found that trace metals released from these dental alloys and titanium were accumulated transiently in the blood, liver, and kidney but had no effect on the histopathology of the liver or kidney. Although the functions of the liver and kidney were compromised, the function of these tissues seemed to be clinically acceptable compared to those in control Syrian hamsters. In addition, the apoptotic effect on renal cells was terminated by removing the Ni-Cr and Co-Cr alloys, and that on hepatocytes was also eliminated by removing the Ni-Cr alloy. In contrast, the effect of the Co-Cr alloy on hepatocytes was temporary and recovered by itself. Taken together, Ni- and Co-based dental alloys and titanium have no effect on the histopathology or function of liver and kidney. Moreover, Ni-Cr and Co-Cr alloys induce transient trace metal accumulation and apoptotic effects in liver and kidney, which can be reduced or terminated by the removal of the alloys, while CP-Ti shows favorable biocompatibility.

Nickel induces inflammatory activation via NF-κB, MAPKs, IRF3 and NLRP3 inflammasome signaling pathways in macrophages

Nickel (Ni), an environmental hazard, widely causes allergic contact hypersensitivity worldwide. Despite that Ni-stimulated pro-inflammatory response is vital in allergy, the underlying molecular mechanisms remain largely unclear. Here, we demonstrated that NiCl₂ activated nuclear factor kappa B (NF-κB), mitogen-activated protein kinases (MAPKs) and interferon regulatory factor 3 (IRF3) signaling pathways in primary bone marrow-derived macrophages (BMDMs), leading to the altered transcription levels of interleukin-1β (IL-1β), -6, -8, -18, tumor necrosis factor-α (TNF-α) and interferon β (INF-β). We also found that nickel chloride (NiCl₂) activated Nod-like receptor 3 (NLRP3) inflammasome pathway, resulting in the proteolytic cleavage and release of IL-1β. NiCl₂ induced the accumulation of mitochondrial reactive oxygen species (mtROS) and the release of mitochondrial DNA (mtDNA), thus activating NLRP3 inflammasome pathway. Additionally, NiCl₂-induced apoptosis was dependent on the generation of mtROS, and caspase-1 activation might also partly contribute to the apoptotic process. Altogether, abovementioned results indicate that NiCl₂ induces inflammatory activation in BMDMs via NF-κB, MAPKs, IRF3 signaling pathways as well as NLRP3 inflammasome pathway, which provides a mechanism to improve the efficiency of treatment against Ni-induced allergic reactions.

Nickel Carcinogenesis Mechanism: DNA Damage

Nickel (Ni) is known to be a major carcinogenic heavy metal. Occupational and environmental exposure to Ni has been implicated in human lung and nasal cancers. Currently, the molecular mechanisms of Ni carcinogenicity remain unclear, but studies have shown that Ni-caused DNA damage is an important carcinogenic mechanism. Therefore, we conducted a literature search of DNA damage associated with Ni exposure and summarized known Ni-caused DNA damage effects. In vitro and vivo studies demonstrated that Ni can induce DNA damage through direct DNA binding and reactive oxygen species (ROS) stimulation. Ni can also repress the DNA damage repair systems, including direct reversal, nucleotide repair (NER), base excision repair (BER), mismatch repair (MMR), homologous-recombination repair (HR), and nonhomologous end-joining (NHEJ) repair pathways. The repression of DNA repair is through direct enzyme inhibition and the downregulation of DNA repair molecule expression. Up to now, the exact mechanisms of DNA damage caused by Ni and Ni compounds remain unclear. Revealing the mechanisms of DNA damage from Ni exposure may contribute to the development of preventive strategies in Ni carcinogenicity.

Redox interactions and genotoxicity of metal-based nanoparticles: A comprehensive review

Nanotechnology is a growing science that may provide several new applications for medicine, food preservation, diagnostic technologies, and sanitation. Despite its beneficial applications, there are several questions related to the safety of nanomaterials for human use. The development of nanotechnology is associated with some concerns because of the increased risk of carcinogenesis following exposure to nanomaterials. The increased levels of reactive oxygen species (ROS) that are due to exposure to nanoparticles (NPs) are primarily responsible for the genotoxicity of metal NPs. Not all, but most metal NPs are able to directly produce free radicals through the release of metal ions and through interactions with water molecules. Furthermore, the increased production of free radicals and the cell death caused by metal NPs can stimulate reduction/oxidation (redox) reactions, leading to the continuous endogenous production of ROS in a positive feedback loop. The overexpression of inflammatory mediators, such as NF-kB and STATs, the mitochondrial malfunction and the increased intracellular calcium levels mediate the chronic oxidative stress that occurs after exposure to metal NPs. In this paper, we review the genotoxicity of different types of metal NPs and the redox mechanisms that amplify the toxicity of these NPs.

Coherent apoptotic and autophagic activities involved in regression of chicken postovulatory follicles

After ovulation in mammals, rupture of mature follicles is reorganized into the corpus luteum that secrets progesterone (P₄) to stimulate endometrial development. The situation in birds differs considerably. Beyond ovulation the ruptured avian follicle forms a postovulatory follicle (POF) that is not considered analogous to mammalian corpus luteum. The function and regression mechanisms of avian POFs remain poorly understood. Here we investigated the changes in apoptotic and autophagic activities that were involved during POF degradation. Results showed that the structure and secretory function of POF3 manifested the most apparent deterioration during whole processes of regression. A TUENL assay revealed that the granulosa layer maintained longer viability than the theca layer. Importantly, mitochondrial apoptosis and endoplasmic reticulum (ER) stress-associated genes and proteins reached their highest levels in the granulosa cells of POF3. Beclin1 was distributed mainly in theca cells and coupled with LC3β-II accumulation, Sequestosome-1 (p62) degradation and Beclin1 elevation confirmed that autophagic activity had increased dramatically in the theca layer of POFs. These results indicate that the apoptosis of the granulosa cells from POFs occurs by mitochondrial apoptosis and ER stress and that a coherence of Beclin1-induced autophagy and caspase-induced apoptosis results in regression of theca layers of avian POFs.

High-throughput transcriptomics: Insights into the pathways involved in (nano) nickel toxicity in a key invertebrate test species

Nickel nanoparticles (NiNPs) have an estimated production of ca. 20 tons per year in the US. Nickel has been risk-assessed for long in Europe, but not NiNPs, hence the concern for the environment. In the present study, we focused on investigating the mechanisms of toxicity of NiNPs and the comparison to NiNO₃. The high-throughput microarray for the soil ecotox model Enchytraeus crypticus (Oligochaeta) was used. To anchor gene to phenotype effect level, organisms were exposed to reproduction effect concentrations EC20 and EC50, for 3 and 7 days. Results showed commonly affected pathways between NiNPs and NiNO₃, including increase in proteolysis, apoptosis and inflammatory response, and interference with the nervous system. Mechanisms unique to NiNO₃ were also observed (e.g. glutathione synthesis). No specific mechanisms for NiNPs were found, which could indicate that longer exposure period (>7 days) is required to capture the peak response to NiNPs. A mechanisms scheme is assembled, showing both common and unique mechanisms to NiNO₃ and NiNPs, providing an important framework for further, more targeted, studies.

Ameliorative effect of dietary supplementation of copper oxide nanoparticles on inflammatory and immune reponses in commercial broiler under normal and heat-stress housing conditions

Heat stress (HS) is one of the most serious adverse conditions that affect poultry causing immunosuppression and decreasing production. In a novel approach, we investigated effects of supplementing copper oxide nanoparticles (CuO-NPs) on the immune response in two commercial broiler strains (Ross 308 and Cobb 500). At one day old, birds were divided into 3 groups with 3 replicates for each. The first group received diet supplemented with 100% of their recommended copper requirements as CuO while, in the second and third groups, birds were given diets supplemented with 100% and 50% of the recommended Cu requirements in the form of CuO-NPs, respectively. At age of 21 day, each group was subdivided randomly into normal (24 ± 2 °C) and heat stressed (33 ± 2 °C for 5 h per day for two successive weeks) groups. Under normal housing temperature, CuO-NPs, significantly enhanced the immune response in these birds, compared to CuO shown by the increased levels of phagocytic activity (PA), lysozyme serum activity, and by upregulating immune-modulator genes including NF-κβ, PGES, IL-1β, TGF-1β, IFN-γ, BAX and CASP8. The responses were different between the two studied strains especially at the level of gene expression. In HS birds, supplementation of CuO-NPs reduced HS induced inflammatory conditions, as shown by lower gene expression levels, lower degenerative changes in the spleen, and altered heterophils/lymphocytes (H/L) ratio. We suggest CuO-NPs supplementation, especially in those chickens that received diet supplemented with 50% of their recommended Cu requirements, could be used under normal housing temperature to enhance the birds' immune response, and during HS to lower heat stress-induced degenerative changes depending on the magnitude of the HS.

Nickel toxicity in P. lividus embryos: Dose dependent effects and gene expression analysis

Many industrial activities release Nickel (Ni) in the environment with harmful effects for terrestrial and marine organisms. Despite many studies on the mechanisms of Ni toxicity are available, the understanding about its toxic effects on marine organisms is more limited. We used Paracentrotus lividus as a model to analyze the effects on the stress pathways in embryos continuously exposed to different Ni doses, ranging from 0.03 to 0.5 mM. We deeply examined the altered embryonic morphologies at 24 and 48 h after Ni exposure. Some different phenotypes have been classified, showing alterations at the expenses of the dorso-ventral axis as well as the skeleton and/or the pigment cells. At the lowest dose used, Ni mainly induced a multi-spicule phenotype observed at 24 h after treatment. On the contrary, at the highest dose of Ni (0.5 mM), 90% of embryos showed no skeleton and no pigment cells. Therefore, we focused on this dose to study protein and gene expression patterns at 24 and 48 h after exposure. Among the proteins analyzed, i.e. p38MAPK, Grp78 and Mn-SOD, only p38MAPK was induced by Ni treatment. Moreover, we analyzed the mRNA profiles of a pool of genes that are involved in stress response and in development mechanisms, i.e. the transcription factors Pl-NFkB and Pl-FOXO; a marker of DNA repair, Pl-XPB/ERCC3; a mitogen-activated protein kinase (MAPK), Pl-p38; an ER stress gene, Pl-grp78; an adapter protein, Pl-14-3-3ε; two markers of pigment cells, Pl-PKS1 and Pl-gcm. The spatial expression of mesenchymal marker genes has been evaluated in Ni-treated embryos at both 24 and 48 h after exposure. Our results indicated that Ni acts at several levels in P. lividus sea urchin, by affecting embryo development, influencing the embryonic immune response and activating stress response pathways to counteract the suffered injury and to promote embryos surviving.

Polyethylene imine modified hydrochar adsorption for chromium (VI) and nickel (II) removal from aqueous solution

An adsorbent hydrochar was synthesized from corn cobs and modified with polyethylene imine (PEI). The hydrochars before and after modification were characterized by scanning electron microscopy, Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and thermogravimetric analysis. FTIR and XPS revealed that the PEI was grafted onto the hydrochar via ether and imine bonds formed with glutaraldehyde. The maximum adsorption capacities for Cr(VI) (33.663mg/g) and Ni(II) (29.059mg/g) on the modified hydrochars were 365% and 43.7% higher, respectively, than those on the unmodified hydrochar. A pseudo-second-order model described the adsorption of Ni(II) and Cr(VI) on all the adsorbents. The adsorption of Cr(VI) was endothermic, spontaneous, increased disorder, and obeyed the Langmuir model. By contrast, the adsorption of Ni(II) was exothermic, spontaneous, decreased disorder, and obeyed the Freundlich model. XPS confirmed that the adsorption sites and mechanisms for Ni(II) and Cr(VI) on the modified hydrochars were different.