Induction of hepatic portal fibrosis, mitochondria damage, and extracellular vesicle formation in Sprague-Dawley rats exposed to copper, manganese, and mercury, alone and in combination

Investigating the relationship among zinc status, blood manganese levels, and enzymatic markers of tissue damage: an epidemiological study using NHANES 2013-2016 data

Manganese is an essential trace element required for various physiological processes. However, excessive exposure to this metal can lead to health issues. This study aims to evaluate whether adequate zinc intake can influence the relationship between blood manganese levels and markers indicating damage to the liver and other organs in populations using epidemiological data. We conducted a comprehensive analysis utilizing 2013-2016 data from the National Health and Nutrition Examination Survey (NHANES). The findings indicated that blood manganese exhibits a significant positive association with the serum levels of enzymatic markers of liver damage alkaline phosphatase and aspartate aminotransferase. However, when investigating the interaction between blood manganese and zinc intake at the second quartile, a significant negative association was found with alkaline phosphatase in three different linear regression models. A similar association was found between the fourth quartile of zinc intake and lactate dehydrogenase activity in all three models of the study. The findings suggest that unhealthy high levels of manganese in populations may lead to tissue injury and disease. Nevertheless, having an adequate zinc intake could help mitigate manganese toxicity.

Copper and liver fibrosis in MASLD: the two-edged sword of copper deficiency and toxicity

Copper is a trace metal whose absence or deficiency can cause structural and functional alterations that can be corrected by copper administration. Copper excess is associated with significant liver toxicity, such as that seen in Wilson’s disease, which often exhibits liver steatosis and can be managed by copper sequestrants. Copper, due to its ability to either accept or donate electrons, is a cofactor in many physiological redox reactions, playing an essential role in cell energy homeostasis, detoxification of reactive oxygen species, and hepatic immunometabolism. Given these facts, it is reasonable to speculate that copper might be involved in the pathogenesis of liver fibrosis in the setting of metabolic dysfunction-associated fatty liver disease (MASLD). To address this research question, a narrative review of published studies was conducted, spanning from the needs, sources, and toxicity of copper to Menkes and Wilson’s disease. Most epidemiological studies have demonstrated that MASLD is associated with copper deficiency. However, several studies show that MASLD is associated with copper excess and very few conclude that copper is not associated with MASLD. Therefore, the putative pathomechanisms associating both copper excess and deficiency with MASLD development and progression are reviewed. In conclusion, epidemiological and pathogenic data support the notion that well-balanced copper homeostasis is a prerequisite for liver health. Accordingly, both copper excess and deficiency may potentially predispose to liver fibrosis via the development of MASLD. Therefore, studies aimed at restoring normal bodily stores of copper should be tailored according to precision medicine approaches based on the specific features of copper metabolism in individual MASLD patients.

Acute manganese toxicosis related to joint health supplement ingestion in two dogs

Two unrelated dogs residing in the same house including an 11-year-old, female spayed, mixed breed dog and a 7-year-old, female spayed, mixed breed dog ingested approximately 75 capsules of a human joint health supplement (Ligaplex I; Standard Process, WI, USA). A total of 2,062 mg of manganese was ingested between both dogs. Dog 1 developed acute fulminant liver failure and a severe coagulopathy that led to hepatic fractures and exsanguination from hemoabdomen. The estimated maximum time from ingestion of the joint health supplement to death was 36 to 48 h. Histologic examination revealed severe periportal hepatic necrosis with mild evidence of preexisiting liver disease and renal tubular epithelial necrosis. Manganese concentrations in liver and kidney tissue were severely increased. Dog 2 developed a severe acute liver injury and was hospitalized for 6 days. Therapies provided during hospitalization included intravenous fluids, maropitant, pantoprazole, N-acetylcysteine, vitamin C, S-adenosylmethionine, and silybin. The dog was treated long-term with S-adenosylmethionine, silybin, ursodiol, and vitamin C. Clinical and biochemical resolution occurred on the recheck examination that took place on day 44. The veterinary literature is comprised of only 2 reports containing 3 dogs that describe acute manganese intoxication. Here, we provide a detailed description of 2 dogs that developed manganese-induced toxicosis after ingestion of a human joint health supplement.

Arrestin domain-containing protein 1-mediated microvesicles (ARMMs) protect against cadmium-induced neurotoxicity

Exposure to environmental heavy metals such as cadmium (Cd) is often linked to neurotoxicity but the underlying mechanisms remain poorly understood. Here we show that Arrestin domain-containing protein 1 (ARRDC1)-mediated microvesicles (ARMMs)--an important class of extracellular vesicles (EVs) whose biogenesis occurs at the plasma membrane--protect against Cd-induced neurotoxicity. Cd increased the production of EVs, including ARMMs, in a human neural progenitor cell line, ReNcell CX (ReN) cells. ReN cells that lack ARMMs production as a result of CRISPR-mediated ARRDC1 knockout were more susceptible to Cd toxicity as evidenced by increased LDH production as well as elevated level of oxidative stress markers. Importantly, adding ARMMs back to the ARRDC1-knockout ReN cells significantly reduced Cd-induced toxicity. Consistent with this finding, proteomics data showed that anti-oxidative stress proteins are enriched in ARMMs secreted from ReN cells. Together our study reveals a novel protective role of ARMMs in Cd neurotoxicity and suggests that ARMMs may be used therapeutically to reduce neurotoxicity caused by exposure to Cd and potentially other metal toxicants.

Effects of Long-Term Exposure to Copper on Mitochondria-Mediated Apoptosis in Pig Liver

Copper (Cu) is listed as one of the main heavy metal pollutants, which poses potential health risks to humans. Excessive intake of Cu has shown toxic effects on the organs of many animals, and the liver is one of the most important organs to metabolize it. In this study, pigs, the mammal with similar metabolic characteristics to humans, were selected to assess the effects of long-term exposure to Cu on mitochondria-mediated apoptosis, which are of great significance for studying the toxicity of Cu to humans. Pigs were fed a diet with different contents of Cu (10, 125, and 250 mg/kg) for 80 days. Samples of blood and liver tissue were collected on days 40 and 80. Experimental results demonstrated that the accumulation of Cu in the liver was increased in a dose-dependent and time-dependent manner. Meanwhile, the curve of pig's body weight showed that a 125 mg/kg Cu diet promoted the growth of pigs during the first 40 days and then inhibited it from 40 to 80 days, while the 250 mg/kg Cu diet inhibited the growth of pigs during 80 days of feeding. Additionally, the genes and protein expression levels of Caspase-3, p53, Bax, Bak1, Bid, Bad, CytC, and Drp1 in the treatment group were higher than that in the control group, while Bcl-2, Bcl-xL, Opa1, Mfn1, and Mfn2 were decreased. In conclusion, these results indicated that long-term excessive intake of Cu could inhibit the growth of pigs and induced mitochondria-mediated apoptosis by breaking the mitochondrial dynamic balance. Synopsis: Long-term exposure to high doses of Cu could lead to mitochondrial dysfunction by breaking the mitochondrial dynamic balance, which ultimately induced mitochondria-mediated apoptosis in the liver of pigs. This might be closely related to the growth inhibition and liver damage in pigs.

Blood and urine manganese exposure in non-alcoholic fatty liver disease and advanced liver fibrosis: an observational study

Manganese was the key activator of biological enzymes-mediated metabolic diseases (Mets)-associated pathophysiological process. Non-alcoholic fatty liver disease (NAFLD), which was the hepatic manifestation of Mets, development remained a mystery. We aimed to explore the association between blood/urine manganese exposure and NAFLD and liver fibrosis diagnosed by vibration-controlled transient elastography (VCTE). All data were extracted from National Health and Nutrition Examination Survey database (2017-2018). A total of 3580 participants with blood manganese data were enrolled and divided into four groups according to the quartile of blood manganese exposure level. In multiple logistic regression models, the higher blood manganese exposure level (groups 2, 3, and 4) had a significant positive association with NAFLD (β = 1.58, 1.30, and 1.69). In subgroup analysis, the main inversely correlation between blood manganese and NAFLD was found in participants with normal/high body mass index and high blood manganese exposure level. Moreover, in 1179 participants with urine manganese data, urine manganese exposure level presented as significantly associated with advanced liver fibrosis in models 1 and 2 (β = 2.00 and 2.02). This study showed that manganese exposure level was positively associated with NAFLD and advanced liver fibrosis among the US population. We suggested that manganese exposure level was a biomarker of the development of NAFLD.

Association between Blood Manganese Levels and Visceral Adipose Tissue in the United States: A Population-Based Study

Background: Manganese (Mn) is an essential trace element with a narrow toxic margin for human health. The association between Mn exposure and adverse visceral adipose tissue (VAT) accumulation is unclear. Objective: This study aimed to estimate the associations of blood Mn levels with VAT mass or visceral obesity in the general population in the United States. Method: This cross-sectional study included data of 7297 individuals released by National Health and Nutrition Examination Survey (NHANES). VAT was quantified with dual-energy X-ray absorptiometry, and blood Mn was measured using inductively coupled plasma mass spectrometry. The generalized linear model and generalized additive model (GAM) were applied to estimate the linear and non-linear associations between Mn levels and VAT mass, respectively. Logistic regression was used to estimate the associations between blood Mn levels and the risk of visceral obesity. Results: Fully adjusted generalized linear regression revealed that individuals in the higher quantile of Mn had increased VAT mass compared with those in the lower quantile (β per quantile change = 0.025; 95% CI of 0.017, 0.033; p < 0.001). Positive associations were also observed in males and females (males: β per quantile change = 0.012, 95% CI of 0.002, 0.022 (p = 0.020); female: β per quantile change = 0.036; 95% CI of 0.023, 0.048 (p < 0.001)). The GAM illustrated that the non-linear associations between blood Mn levels and VAT mass were in U-shape patterns (effective degree of freedom >1 in total participants, males, and females). A stratified analysis found significant interactions between Mn and the family income-to-poverty ratio (PIR) in males, with stronger associations in males with a PIR < 1.3 (β = 0.109; 95% CI of 0.048, 0.170). Additional analyses revealed that individuals in the highest quantile of Mn had a 39% higher risk of visceral obesity (OR = 1.39; 95% CI of 1.15−1.69; p < 0.001). Conclusions: Higher blood Mn levels were positively associated with increased VAT mass and visceral obesity risk. The adverse VAT phenotype associated with excessive blood Mn levels should be further investigated.

Oral Administration of Copper Chloride Damages DNA, Lowers Antioxidant Defense, Alters Metabolic Status, and Inhibits Membrane Bound Enzymes in Rat Kidney

Copper (Cu) is a heavy metal that is widely used in industries and is also an essential micronutrient for living beings. However, excess Cu is toxic and human exposure to high levels of this metal results in numerous adverse health effects. We have investigated the effect of oral administration of copper chloride (CuCl₂), a Cu(II) compound, on various parameters of oxidative stress, cellular metabolism, and DNA integrity in the rat kidney. This was done to delineate the molecular mechanism of Cu(II) toxicity. Adult male rats were randomly divided into five groups. Animals in four CuCl₂-treated groups were separately administered single acute oral dose of CuCl₂ at 5, 15, 30, and 40 mg/kg body weight. Animals in the fifth group were not given CuCl₂ and served as the control. All rats were sacrificed 24 h after the dose of CuCl₂ and their kidneys removed. CuCl₂ administration led to significant alterations in enzymatic and non-enzymatic parameters of oxidative stress. It changed the activities of metabolic and membrane bound enzymes and also decreased the activities of brush border membrane enzymes. CuCl₂ treatment dose-dependently enhanced DNA damage and DNA-protein crosslinking in renal cells, when compared to the control group. The administration of CuCl₂ also resulted in marked morphological changes in the kidney, with more prominent alterations at higher doses of CuCl₂. These results clearly show that CuCl₂ impairs the antioxidant defense system resulting in oxidative damage to the kidney.

Copper chloride inhibits brush border membrane enzymes, alters antioxidant and metabolic status and damages DNA in rat intestine: a dose-dependent study

Copper (Cu) is an extensively used heavy metal and an indispensible micronutrient for living beings. However, Cu is also toxic and exerts multiple adverse health effects when humans are exposed to high levels of this metal. We have examined the effect of single acute oral dose of copper chloride (CuCl₂) on parameters of oxidative stress, cellular metabolism, membrane and DNA damage in rat intestine. Adult male Wistar rats were divided into four groups and separately administered a single oral dose of 5, 15, 30 and 40 mg CuCl₂/kg body weight. Rats not administered CuCl₂ served as the control. Oral administration of CuCl₂ led to significant alterations in the activities of metabolic and membrane-bound enzymes; brush border enzymes were inhibited by 45-75% relative to the control set. Inhibition of antioxidant enzymes diminished the metal-reducing and free radical quenching ability of the cells. Oxidative damage caused cellular oxidation of thiols, proteins and lipids. Diphenylamine and comet assays showed that CuCl₂ treatment enhanced DNA damage while DNA-protein crosslinking was also increased in the intestinal cells. Examination of stained sections showed that CuCl₂ treatment led to marked histological changes in the intestine. All the changes seen were in a CuCl₂ dose-dependent manner with more prominent alterations at higher doses of CuCl₂. These results clearly show that oral administration of CuCl₂ results in oxidative damage to the intestine which can impair its digestive and absorptive functions.

The impact of environmental and occupational exposures of manganese on pulmonary, hepatic, and renal functions

Manganese (Mn) is an essential trace element for humans, but long-term environmental or occupational exposures can lead to numerous health problems. Although many studies have identified an association between Mn exposures and neurological abnormalities, emerging data suggest that occupationally and environmentally relevant levels of Mn may also be linked to multiple organ dysfunction in the general population. In this regard, many experimental and clinical studies provide support for a causal link between Mn exposure and structural and functional changes that are responsible for organ dysfunction in major organs like lung, liver, and kidney. The underlying mechanisms suggested to Mn toxicity include altered activities of the components of intracellular signaling cascades, oxidative stress, apoptosis, affected cell cycle regulation, autophagy, angiogenesis, and an inflammatory response. We further discussed the sources and possible mechanisms of Mn absorption and distribution in different organs. Finally, treatment strategies available for treating Mn toxicity as well as directions for future studies were discussed.

Extracellular Vesicles in Organ Fibrosis: Mechanisms, Therapies, and Diagnostics

Fibrosis is the unrelenting deposition of excessively large amounts of insoluble interstitial collagen due to profound matrigenic activities of wound-associated myofibroblasts during chronic injury in diverse tissues and organs. It is a highly debilitating pathology that affects millions of people globally and leads to decreased function of vital organs and increased risk of cancer and end-stage organ disease. Extracellular vesicles (EVs) produced within the chronic wound environment have emerged as important vehicles for conveying pro-fibrotic signals between many of the cell types involved in driving the fibrotic response. On the other hand, EVs from sources such as stem cells, uninjured parenchymal cells, and circulation have in vitro and in vivo anti-fibrotic activities that have provided novel and much-needed therapeutic options. Finally, EVs in body fluids of fibrotic individuals contain cargo components that may have utility as fibrosis biomarkers, which could circumvent current obstacles to fibrosis measurement in the clinic, allowing fibrosis stage, progression, or regression to be determined in a manner that is accurate, safe, minimally-invasive, and conducive to repetitive testing. This review highlights the rapid and recent progress in our understanding of EV-mediated fibrotic pathogenesis, anti-fibrotic therapy, and fibrosis staging in the lung, kidney, heart, liver, pancreas, and skin.

Exposure to copper induces mitochondria-mediated apoptosis by inhibiting mitophagy and the PINK1/parkin pathway in chicken (Gallus gallus) livers

Copper (Cu), a transition metal with essential cellular functions, exerts toxic effects when present in excess by inducing oxidative stress. However, the Cu-induced crosstalk between mitophagy and apoptosis and the underlying mechanisms are unknown. Here, the mechanism of Cu-induced hepatotoxicity mediated by mitophagy and apoptosis was explored in vivo and in vitro. In in vivo experiments, chickens were fed a diet with various levels of Cu (11, 110, 220, and 330 mg/kg) for 7 weeks, which led to ultrastructural damage, mitophagy, and apoptosis in liver tissue. In vitro experiments on primary chicken hepatocytes showed that Cu treatment for 24 h increased the numbers of mitophagosomes and upregulated PINK1, parkin, and p62 mRNA levels and parkin and p62 protein levels, inducing mitophagy. Moreover, treatment with 3- methyladenine (3-MA) aggravated Cu-induced S-phase arrest in cell cycle; increased the apoptotic rate; increased p53, Bak1, Bax, Cyt C, and Caspase3/cleaved-caspase3 mRNA and protein levels; and decreased Bcl2 mRNA and protein levels. However, rapamycin (Rapa) had the opposite effects on the above factors. In general, the results reveal that Cu exposure can cause mitophagy through the PINK1/Parkin pathway in chicken livers, and that mitophagy might attenuate Cu-induced mitochondrial apoptosis.

Biochemical and histological effects of five weeks ingestion of Zamzam water on the liver and kidneys of Wistar rats

Zamzam water is a natural alkaline water which has become alkaline as a result of the natural environment. It comes from what is considered as one of the oldest springs in the world. The water contains high concentrations of alkaline minerals as well as trace and heavy metals. The aim of the current study is to evaluate the effects of five weeks ingestion of Zamzam water on the liver and kidney functions of rats. Adult female Wistar rats weighing 150-200 g were divided into two groups, with 15 rats in each. The control group was supplied daily by bottled water and the Zamzam water group was supplied daily by 500 ml of Zamzam water for five weeks. The rats were weighed weekly and, at the end of the experiment, blood samples were collected from all rats for the biochemical determination of serum levels of aspartate transaminase (AST), alanine aminotransferase (ALT), alkaline phosphatase (ALP), urea, creatinine, albumin, and uric acid, using calorimetric methods. Liver and kidney tissues were fixed in 10% neutral buffered-formalin solution and further embedded in wax blocks for routine hematoxylin and eosin (H&E) staining and were examined for histopathological changes using a light microscope. The results of the current study showed that there was a significant increase (P < 0.05) in the weight of the Zamzam group when compared to the control group after five weeks of ingestion. Liver and kidney function tests did not show any significant difference when compared with the controls (P > 0.05). In addition, histological examination of the liver and kidney tissues did not show any toxicological changes. In conclusion, the results showed that the ingestion of Zamzam water did not alter serum levels of kidney function tests and liver enzymes; and did not result in a noticeable change in the liver and kidney histology. Thus, the high concentrations of elements in Zamzam water do not induce hepatotoxicity or nephrotoxicity and the water is considered safe for long-term consumption.