Determination of the serum metallothionein (MT)1/2 concentration in patients with Wilson's disease and Menkes disease

Evolution of Status of Trace Elements and Metallothioneins in Patients with COVID-19: Relationship with Clinical, Biochemical, and Inflammatory Parameters

The inflammatory reaction and pathogenesis of COVID-19 may be modulated by circulating trace elements (Iron (Fe), Zinc (Zn), Copper (Cu), Manganese (Mn)) and Metallothioneins (MTs). Thus, the present study aimed to investigate their relationship with clinical, biochemical, and inflammatory parameters in patients with COVID-19 at the early Intensive Care Unit (ICU) phase. Critically ill patients (n = 86) were monitored from the first day of ICU admission until the third day of stay. Serum samples were used to assess mineral levels via Inductively Coupled Plasma Mass Spectrometry (ICP-MS) and MT levels via differential pulse voltammetry. Levels of Cu and MTs were significantly decreased after 3 days (p < 0.05), increasing the prevalence of Cu-deficient values from 50% to 65.3% (p = 0.015). Fe and Zn were shown to have a predictive value for mortality and severity. The present study suggests trace element deficiency may be a risk factor during early ICU treatment of COVID-19, as it is related to different biochemical and clinical parameters, indicating a possible beneficial effect of restoring proper levels of these micronutrients.

Therapeutic role of nitroglycerin against copper-nitrilotriacetate induced hepatic and renal damage

Earlier we have shown that exposure to copper-nitrilotriacetate (Cu-NTA) manifests toxicity by generating oxidative stress and potent induction of proliferative reaction in the liver and kidney. In the study, we look at the impact of nitroglycerin (GTN) administration on Cu-NTA-induced oxidative stress and hyperproliferative response in the liver and kidney. GTN administration intraperitoneally to male Wistar rats after Cu-NTA administration intraperitoneally caused substantial protection against Cu-NTA-induced tissue injury, oxidative stress and hyperproliferative response. Cu-NTA administration at a dose of 4.5 mg/kg body weight produces significant ( p < .001) elevation in biochemical parameters including aspartate aminotransferase (AST), alanine aminotransferase (ALT), blood urea nitrogen (BUN) and creatinine (CREA) with a concomitant increase in microsomal lipid peroxidation. Along with these alterations, we discovered a substantial increment in [3H]thymidine incorporation into hepatic and renal DNA synthesis ( p < .001). Cu-NTA-induced tissue damage and lipid peroxidation in hepatic and renal tissues were inhibited by GTN treatment in a dose-dependent manner ( p < .05–0.001). Furthermore, GTN can suppress the hyperproliferative response elicited by Cu-NTA by down-regulating the rate of [3H]thymidine incorporation into hepatic and renal DNA ( p < .01–0.001). Protective effect of GTN against Cu-NTA was also confirmed by histopathological changes in liver and kidney. This result suggests that GTN may serve as a scavenger for reactive oxygen species (ROS) and reduces toxic metabolites of Cu-NTA, thereby avoiding tissue injury and oxidative stress. Further, administration of NO inhibitor, NG-Nitroarginine methyl ester (L-NAME), exacerbated Cu-NTA induced oxidative tissue damage and cell proliferation. Overall, GTN reduces Cu-NTA-induced tissue damage, oxidative stress, and proliferative response in the rat liver and kidney, according to these findings. On the basis of the above results, present study suggests that GTN may be a potential therapeutic agent for restoration of oxidative damage and proliferation to liver and kidney.

Synthetic fish metallothionein design as a potential tool for monitoring toxic metals in water

The diversity of aquatic ecosystems impacted by toxic metals is widely distributed throughout the world. The application of metallothionein (MT) as an early warning sign of metal exposure in freshwater fish is important in biomonitoring, but a more accessible, sensitive, safe, and efficient new methodological strategy is necessary. On this way, a fish MT synthetic gene from Oreochromis aureos was expressed in Escherichia coli to produce polyclonal antibodies against the protein. In the validation assays, these antibodies were able to detect hepatic MT from freshwater fishes Oreochromis niloticus, Pimelodus maculatus, Prochilodus lineatus, and Salminus brasiliensis showing a potential tool for toxic metals biomarker in biomonitoring of aquatic ecosystems. The current results showed the applicability of this molecule in quantitative immunoassays as a sensor for monitoring aquatic environments impacted by toxic metals. Due to the lack of methods focusing on metal pollution diagnostics in aquatic ecosystems, the current proposal revealed a promising tool to applications in biomonitoring programs of water resources, mainly in Brazil where the mining activity is very developed.

Serum copper, zinc and metallothionein serve as potential biomarkers for hepatocellular carcinoma

BACKGROUND

Copper (Cu) and zinc (Zn) are essential nutrients and cofactors of enzymatic reactions with their binding partner. Metallothionein (MT) plays an important role in protecting against heavy metals and oxidative injury, however it may also portend drug resistance and a worse prognosis for hepatocellular carcinoma (HCC) patients. The aim of this study was to determine the amount of Cu, Zn, Cu/Zn and MT in evaluating a group of patients with HCC, including those treated with lenvatinib.

METHODS

We enrolled 175 patients with HCC (139 men, 36 women; mean age 71.1 years; hepatitis C virus n = 85, hepatitis B virus n = 19, hepatitis C virus and hepatitis B virus n = 2, non-alcoholic steatohepatitis n = 39, alcohol n = 25, others n = 5; Child-Pugh A n = 141, Child-Pugh B n = 30, Child-Pugh C n = 4; Barcelona clinic liver cancer (BCLC) stage 0 n = 38, stage A n = 56, stage B n = 39, stage C n = 38, stage D n = 4). We evaluated the associations between Cu, Zn and MT. The study outcome was liver cancer-specific survival. Moreover, we treated 12 HCC patients with lenvatinib and investigated the changes in MT during lenvatinib therapy.

RESULTS

The serum level of Cu was positively correlated with alanine aminotransferase and the BCLC stage. The serum level of Zn decreased concordant with liver disease progression. Patients with a Cu/Zn ratio≥0.999 had significantly improved rates of survival when compared to patients with a Cu/Zn ratio<0.999 (45.3 vs. 30.1 months, p<0.001). MT was significantly correlated with the Cu/Zn ratio and increased after the administration of lenvatinib. Using multivariate Cox regression analyses, it was determined that the Cu/Zn ratio (hazard ratio [HR]: 1.442, p = 0.008), alpha-fetoprotein (HR: 1.000, p<0.001) and BCLC stage (HR: 2.087, p<0.001) were independent predictors of survival.

CONCLUSIONS

The Cu/Zn ratio could serve as a useful predictive marker for survival in cases of HCC. MT levels increased in HCC patients receiving lenvatinib therapy, and maybe a predictor of reduced survival.

Microalgal Metallothioneins and Phytochelatins and Their Potential Use in Bioremediation

The persistence of heavy metals (HMs) in the environment causes adverse effects to all living organisms; HMs accumulate along the food chain affecting different levels of biological organizations, from cells to tissues. HMs enter cells through transporter proteins and can bind to enzymes and nucleic acids interfering with their functioning. Strategies used by microalgae to minimize HM toxicity include the biosynthesis of metal-binding peptides that chelate metal cations inhibiting their activity. Metal-binding peptides include genetically encoded metallothioneins (MTs) and enzymatically produced phytochelatins (PCs). A number of techniques, including genetic engineering, focus on increasing the biosynthesis of MTs and PCs in microalgae. The present review reports the current knowledge on microalgal MTs and PCs and describes the state of art of their use for HM bioremediation and other putative biotechnological applications, also emphasizing on techniques aimed at increasing the cellular concentrations of MTs and PCs. In spite of the broad metabolic and chemical diversity of microalgae that are currently receiving increasing attention by biotechnological research, knowledge on MTs and PCs from these organisms is still limited to date.

Animal models of Wilson disease

Wilson disease (WD) is an autosomal recessive disorder of copper metabolism manifesting with hepatic, neurological and psychiatric symptoms. The limitations of the currently available therapy for WD (particularly in the management of neuropsychiatric disease), together with our limited understanding of key aspects of this illness (e.g. neurological vs. hepatic presentation) justify the ongoing need to study WD in suitable animal models. Four animal models of WD have been established: the Long-Evans Cinnamon rat, the toxic-milk mouse, the Atp7b knockout mouse and the Labrador retriever. The existing models of WD all show good similarity to human hepatic WD and have been helpful in developing an improved understanding of the human disease. As mammals, the mouse, rat and canine models also benefit from high homology to the human genome. However, important differences exist between these mammalian models and human disease, particularly the absence of a convincing neurological phenotype. This review will first provide an overview of our current knowledge of the orthologous genes encoding ATP7B and the closely related ATP7A protein in C. elegans, Drosophila and zebrafish (Danio rerio) and then summarise key characteristics of rodent and larger mammalian models of ATP7B-deficiency.

Metallothionein is elevated in liver and duodenum of Atp7b(-/-) mice

Different mutations in the copper transporter gene Atp7b are identified as the primary cause of Wilson's disease. These changes result in high copper concentrations especially in the liver and brain, and consequently lead to a dysfunction of these organs. The Atp7^(-/-) mouse is an established animal model for Wilson's disease and characterized by an abnormal copper accumulation, a low serum oxidase activity and an increased copper excretion in urine. Metallothionein (MT) proteins are low molecular weight metal-binding proteins and essential for the zinc homeostasis but also play a role for the regulation of other metals, e.g. copper. However the molecular mechanisms of MT in regard to Atp7b remain still elusive. In this study we investigate the expression of MT in the liver and duodenum of Atp7b^(-/-) mice and wildtype mice. Hepatic and duodenal expression of MT was measured by real-time reverse transcription-polymerase chain reaction and post-translational expression was analyzed by immunoblot and immunofluorescence. Expression of MT in liver und duodenum was significantly higher in Atp7b^(-/-) mice than in controls. Hepatic and duodenal copper, iron and zinc content were also studied. Compared to control hepatic copper and iron content was significantly higher while hepatic zinc content was significantly lower in Atp7b^(-/-) mice. In the duodenum copper and zinc content of Atp7b^(-/-) mice was significantly lower than in controls. Duodenal iron content was also lower in Atp7b^(-/-) mice, but did not reach statistical significance. The results of our study suggest that metallothionein is elevated in the liver and duodenum of Atp7b^(-/-) mice.

Metallothionein: a Potential Link in the Regulation of Zinc in Nutritional Immunity

Nutritional immunity describes mechanisms for withholding essential transition metals as well as directing the toxicity of these metals against infectious agents. Zinc is one of these transition elements that are essential for both humans and microbial pathogens. At the same time, Zn can be toxic both for man and microbes if its concentration is higher than the tolerance limit. Therefore a "delicate" balance of Zn must be maintained to keep the immune cells surveilling while making the level of Zn either to starve or to intoxicate the pathogens. On the other hand, the invading pathogens will exploit the host Zn pool for its survival and replication. Apparently, different sets of protein in human and bacteria are involved to maintain their Zn need. Metallothionein (MT)-a group of low molecular weight proteins, is well known for its Zn-binding ability and is expected to play an important role in that Zn balance at the time of active infection. However, the differences in structural, functional, and molecular control of biosynthesis between human and bacterial MT might play an important role to determine the proper use of Zn and the winning side. The current review explains the possible involvement of human and bacterial MT at the time of infection to control and exploit Zn for their need.

Origin, Function, and Fate of Metallothionein in Human Blood

Toxic heavy metals, toxic organic compounds, reactive oxygen species (ROS), infections, and temperature are well-known metallothionein (MT) inducers in human blood. The current review aims to summarize synthesis, function, and fate of human blood MT in response to the known MT inducers. Part of the MTs that are synthesized in different organs such as the liver, kidney, and spleen is transported and stored in different blood cells and in plasma. Cells of the circulatory system also synthesize MT. From the circulation, MT returns to the kidney where the metal-bound MTs are degraded to release the metal ion that in turn induces MT expression therein. The blood MTs play important roles in metal detoxification, transportation, and storage. By neutralizing ROS, MTs protect blood cells from oxidative stress-induced cytotoxicity and genotoxicity. Arguably, MTs are also involved in immune suppression. Given the permeating distribution of blood MT throughout the body as well as its diverse role in the protection against harmful environmental factors and in metal homeostasis, MT could be better recognized as a major public health protein.

Mammalian Metallothionein-2A and Oxidative Stress

Mammalian metallothionein-2A (MT2A) has received considerable attention in recent years due to its crucial pathophysiological role in anti-oxidant, anti-apoptosis, detoxification and anti-inflammation. For many years, most studies evaluating the effects of MT2A have focused on reactive oxygen species (ROS), as second messengers that lead to oxidative stress injury of cells and tissues. Recent studies have highlighted that oxidative stress could activate mitogen-activated protein kinases (MAPKs), and MT2A, as a mediator of MAPKs, to regulate the pathogenesis of various diseases. However, the molecule mechanism of MT2A remains elusive. A deeper understanding of the functional, biochemical and molecular characteristics of MT2A would be identified, in order to bring new opportunities for oxidative stress therapy.

Cardiovascular effects of copper deficiency on activity of superoxide dismutase in diabetic nephropathy

BACKGROUND

Copper (Cu) is essential both for its role in antioxidant enzymes, like Cu/zinc (Zn) superoxide dismutase (SOD) and ceruloplasmin, as well as its role in lysyl oxidase, essential for the strength and integrity of the heart and blood vessels. With such a central role in cardiovascular health, Cu has been generally overlooked in the debate over improving our cardiovascular health. Cu deficiency has produced many of the same abnormalities present in cardiovascular disease. It seems almost certain that Cu plays a large role in the development of this killer disease, not because of its excess in the diet, but rather its deficiency.

AIM

This study was undertaken to investigate the cardiovascular effects of Cu deficiency on the activity of SOD in patients with type 2 diabetes mellitus (T2DM) with and without diabetic nephropathy.

MATERIALS AND METHODS

Fifty-five patients with T2DM were recruited in this study which were divided into two subgroups based on the presence of microalbuminuria, the first group (microal buminuric group, n = 31) had a microalbuminuria between 30 and 299 μg/mg. The second group (normoal buminuric group, n = 29) had an albumin level less than 30 μg/mg. The two diabetic groups were compared to the control group (n = 37).

RESULTS

The results of our study showed a significant reduction in the levels of SOD enzyme associated with an increased urinary Cu excretion in microalbuminuric group compared to the control group at P < 0.05.

CONCLUSIONS

The current study illustrates that the regulation of the blood concentrations of Cu may be a potential therapeutic target for prevention and treatment of diabetic nephropathy.