Animal models of Wilson disease

Role of copper in central nervous system physiology and pathology

Copper is a transition metal and an essential element for the organism, as alterations in its homeostasis leading to metal accumulation or deficiency have pathological effects in several organs, including the central nervous system. Central copper dysregulations have been evidenced in two genetic disorders characterized by mutations in the copper-ATPases ATP7A and ATP7B, Menkes disease and Wilson's disease, respectively, and also in multifactorial neurological disorders such as Alzheimer's disease, Parkinson's disease, amyotrophic lateral sclerosis, and multiple sclerosis. This review summarizes current knowledge about the role of copper in central nervous system physiology and pathology, reports about unbalances in copper levels and/or distribution under disease, describes relevant animal models for human disorders where copper metabolism genes are dysregulated, and discusses relevant therapeutic approaches modulating copper availability. Overall, alterations in copper metabolism may contribute to the etiology of central nervous system disorders and represent relevant therapeutic targets to restore tissue homeostasis.

Effect of primary copper metabolism disturbance on elemental, protein, and lipid composition of the organs in Jackson toxic milk mouse

Toxic milk (txJ) is an autosomal recessive mutation in the Atp7b gene in the C3H/HeJ strain, observed at The Jackson Laboratory in Maine, USA. TxJ mice exhibit symptoms similar to those of human Wilson's disease (WD). The study aimed to verify organ involvement in a mouse model of WD. TxJ mice and control animals were sacrificed at 2, 4, 8, and 14 months of age. Total X-ray Fluorescence Spectroscopy (TXRF) was used to determine the elemental concentration in organs. Tissue chemical composition was measured by Fourier Transform Infrared Spectroscopy (FTIR). Additionally, hybrid mapping of FTIR and microXRF was performed. Elevated concentrations of Cu were observed in the liver, striatum, eye, heart, and duodenum of txJ mice across age groups. In the striatum of the oldest txJ mice, there was lower lipid content and a higher fraction of saturated fats. The secondary structure of striatum proteins was disturbed in txJ mice. In the livers of txJ mice, higher concentrations of saturated fats and disturbances in the secondary structure of proteins were observed. The concentration of neurofilaments was significantly higher in txJ serum. The distribution of Cu deposits in brains was uniform with no prevalence in any anatomic structure in either group, but significant protein structure changes were observed exclusively in the striatum of txJ. In this txJ animal model of WD, pathologic copper accumulation occurs in the duodenum, heart, and eye tissues. Increased copper concentration in the liver and brain results in increased saturated fat content and disturbances in secondary protein structure, leading to hepatic injury and neurodegeneration.

Aberrant copper metabolism and hepatic inflammation cause neurological manifestations in a mouse model of Wilson's disease

Pathogenic germline mutations in the P-type copper-transporting ATPase (ATP7B) gene cause Wilson's disease (WD), a hereditary disorder characterized by disrupted copper metabolism. The Arg778Leu (R778L) mutation in exon 8 is prevalent among individuals with WD in East Asia and is associated with more severe phenotypes. In this study, we generated a WD mouse model harboring R778L mutation (R778L mice) using CRISPR/Cas9. R778L mice exhibit a range of pathological characteristics resembling those of patients with WD and the same point mutations, including aberrant copper metabolism, pathological cellular injury, inflammation, and severe hepatic fibrosis. At 3-5 months of age, these mice started to display neurological deficits in motor coordination and cognitive dysfunction, accompanied by increased expression of inflammatory cytokines in the central nervous system. Microglia in the striatum and cortex exhibit significant activation, shorter processes, and decreased branch points. However, the Cu2+ levels in the brain tissue of R778L mice did not differ significantly from those of wild-type mice. Notably, inhibition of hepatic inflammation with PJ34 or siNfkb markedly alleviated the deficiencies in cognitive performance and improved locomotor activity in R778L mice. Thus, this study establishes a novel murine model to investigate the pathophysiology of WD, highlights the liver-brain crosstalk responsible for neurological manifestations in individuals with WD caused by the R778L point mutation, and demonstrates the potential of modulating liver inflammation as a therapeutic strategy for alleviating the neurological manifestations of WD.

Gandouling ameliorates liver injury in Wilson's disease through the inhibition of ferroptosis by regulating the HSF1/HSPB1 pathway

Ferroptosis, an iron-dependent form of cell death, plays a crucial role in the progression of liver injury in Wilson's disease (WD). Gandouling (GDL) has emerged as a potential therapeutic agent for preventing and treating liver injury in WD. However, the precise mechanisms by which GDL mitigates ferroptosis in WD liver injury remain unclear. In this study, we discovered that treating Toxic Milk (TX) mice with GDL effectively decreased liver copper content, corrected iron homeostasis imbalances, and lowered lipid peroxidation levels, thereby preventing ferroptosis and improving liver injury. Bioinformatics analysis and machine learning algorithms identified Hspb1 as a pivotal regulator of ferroptosis. GDL treatment significantly upregulated the expression of HSPB1 and its upstream regulatory factor HSF1, thereby activating the HSF1/HSPB1 pathway. Importantly, inhibition of this pathway by NXP800 reversed the protective effects of GDL on ferroptosis in the liver of TX mice. In conclusion, GDL shows promise in alleviating liver injury in WD by inhibiting ferroptosis through modulation of the HSF1/HSPB1 pathway, suggesting its potential as a novel therapeutic agent for treating liver ferroptosis in WD.

The physiological and pathophysiological roles of copper in the nervous system

Copper is a critical trace element in biological systems due the vast number of essential enzymes that require the metal as a cofactor, including cytochrome c oxidase, superoxide dismutase and dopamine-β-hydroxylase. Due its key role in oxidative metabolism, antioxidant defence and neurotransmitter synthesis, copper is particularly important for neuronal development and proper neuronal function. Moreover, increasing evidence suggests that copper also serves important functions in synaptic and network activity, the regulation of circadian rhythms, and arousal. However, it is important to note that because of copper's ability to redox cycle and generate reactive species, cellular levels of the metal must be tightly regulated to meet cellular needs while avoiding copper-induced oxidative stress. Therefore, it is essential that the intricate system of copper transporters, exporters, copper chaperones and copper trafficking proteins function properly and in coordinate fashion. Indeed, disorders of copper metabolism such as Menkes disease and Wilson disease, as well as diseases linked to dysfunction of copper-requiring enzymes, such as SOD1-linked amyotrophic lateral sclerosis, demonstrate the dramatic neurological consequences of altered copper homeostasis. In this review, we explore the physiological importance of copper in the nervous system as well as pathologies related to improper copper handling.

Iron, Copper, and Selenium: Cancer's Thing for Redox Bling

Cells require micronutrients for numerous basic functions. Among these, iron, copper, and selenium are particularly critical for redox metabolism, and their importance is heightened during oncogene-driven perturbations in cancer. In this review, which particularly focuses on iron, we describe how these micronutrients are carefully chaperoned about the body and made available to tissues, a process that is designed to limit the toxicity of free iron and copper or by-products of selenium metabolism. We delineate perturbations in iron metabolism and iron-dependent proteins that are observed in cancer, and describe the current approaches being used to target iron metabolism and iron-dependent processes.

A new Caenorhabditis elegans model to study copper toxicity in Wilson disease

Wilson disease (WD) is caused by mutations in the ATP7B gene that encodes a copper (Cu) transporting ATPase whose trafficking from the Golgi to endo-lysosomal compartments drives sequestration of excess Cu and its further excretion from hepatocytes into the bile. Loss of ATP7B function leads to toxic Cu overload in the liver and subsequently in the brain, causing fatal hepatic and neurological abnormalities. The limitations of existing WD therapies call for the development of new therapeutic approaches, which require an amenable animal model system for screening and validation of drugs and molecular targets. To achieve this objective, we generated a mutant Caenorhabditis elegans strain with a substitution of a conserved histidine (H828Q) in the ATP7B ortholog cua-1 corresponding to the most common ATP7B variant (H1069Q) that causes WD. cua-1 mutant animals exhibited very poor resistance to Cu compared to the wild-type strain. This manifested in a strong delay in larval development, a shorter lifespan, impaired motility, oxidative stress pathway activation, and mitochondrial damage. In addition, morphological analysis revealed several neuronal abnormalities in cua-1 mutant animals exposed to Cu. Further investigation suggested that mutant CUA-1 is retained and degraded in the endoplasmic reticulum, similarly to human ATP7B-H1069Q. As a consequence, the mutant protein does not allow animals to counteract Cu toxicity. Notably, pharmacological correctors of ATP7B-H1069Q reduced Cu toxicity in cua-1 mutants indicating that similar pathogenic molecular pathways might be activated by the H/Q substitution and, therefore, targeted for rescue of ATP7B/CUA-1 function. Taken together, our findings suggest that the newly generated cua-1 mutant strain represents an excellent model for Cu toxicity studies in WD.

The Specific Copper(II) Chelator TDMQ20 Is Efficient for the Treatment of Wilson's Disease in Mice

(1) Background: In patients with Wilson's disease, the deficiency of the copper carrier ATP7B causes the accumulation of copper in the liver, brain and various other organs. Lifelong treatment is therefore mandatory, using copper chelators to increase the excretion of copper and to avoid life-threatening damage. The clinically used reference drug, D-penicillamine, exhibit numerous adverse effects, especially a frequent severe and irreversible neurological worsening, mainly due to its lack of metal selectivity; (2) Methods: A new tetradentate ligand based on an 8-aminoquinoline entity, named TDMQ20, which is highly selective for copper compared with other metal ions, is evaluated in "toxic milk" TX mice as an oral treatment of this Wilson's disease murine model; (3) Results: The concentration of copper in the liver of "toxic milk" TX mice decreased and the fecal excretion of copper increased upon oral treatment with TDMQ20. Both effects are dose-dependent, and more pronounced than those of D-penicillamine; (4) Conclusions: The TDMQ20 copper chelator is more efficient than the reference drug D-penicillamine for the treatment of a Wilson's disease murine model. Pharmacological data obtained with TDMQ20 on the TX mouse model strongly support the selection of this ligand as a drug candidate for this genetic disease.

Copper-transporting ATPases throughout the animal evolution - From clinics to basal neuron-less animals

Copper-transporting ATPases are a group of heavy metal-transporting proteins and which can be found in all living organisms. In animals, they are generally referred to as ATP7 proteins and are involved in many different physiological processes including the maintaining of copper homeostasis and the supply of copper to cuproenzymes. A single ATP7 gene is present in non-chordate animals while it is divided into ATP7A and ATP7B in chordates. In humans, dysfunction of ATP7 proteins can lead to severe genetic disorders, such as, Menkes disease and Wilson's disease, which are characterized by abnormal copper transport and accumulation, causing significant health complications. Therefore, there is a substantial amount of research on ATP7 genes and ATP7 proteins in humans and mice to understand pathophysiological conditions and find potential therapeutic interventions. Copper-transporting ATPases have also been investigated in some non-mammalian vertebrates, protostomes, single-cellular eukaryotes, prokaryotes, and archaea to gain useful evolutionary insights. However, ATP7 function in many animals has been somewhat neglected, particularly in non-bilaterians. Previous reviews on this topic only broadly summarized the available information on the function and evolution of ATP7 genes and ATP7 proteins and included only the classic vertebrate and invertebrate models. Given this, and the fact that a considerable amount of new information on this topic has been published in recent years, the present study was undertaken to provide an up-to-date, comprehensive summary of ATP7s/ATP7s and give new insights into their evolutionary relationships. Additionally, this work provides a framework for studying these genes and proteins in non-bilaterians. As early branching animals, they are important to understand the evolution of function of these proteins and their important role in copper homeostasis and neurotransmission.

Stimulation of Liver Fibrosis by N2 Neutrophils in Wilson's Disease

BACKGROUND & AIMS

Wilson's disease is an inherited hepatoneurologic disorder caused by mutations in the copper transporter ATP7B. Liver disease from Wilson's disease is one leading cause of cirrhosis in adolescents. Current copper chelators and zinc salt treatments improve hepatic presentations but frequently worsen neurologic symptoms. In this study, we showed the function and machinery of neutrophil heterogeneity using a zebrafish/murine/cellular model of Wilson's disease.

METHODS

We investigated the neutrophil response in atp7b-/- zebrafish by live imaging, movement tracking, and transcriptional analysis in sorted cells. Experiments were conducted to validate liver neutrophil heterogeneity in Atp7b-/- mice. In vitro experiments were performed in ATP7B-knockout human hepatocellular carcinomas G2 cells and isolated bone marrow neutrophils to reveal the mechanism of neutrophil heterogeneity.

RESULTS

Recruitment of neutrophils into the liver is observed in atp7b-/- zebrafish. Pharmacologic stimulation of neutrophils aggravates liver and behavior defects in atp7b-/- zebrafish. Transcriptional analysis in sorted liver neutrophils from atp7b-/- zebrafish reveals a distinct transcriptional profile characteristic of N2 neutrophils. Furthermore, liver N2 neutrophils also were observed in ATP7B-knockout mice, and pharmacologically targeted transforming growth factor β1, DNA methyltransferase, or signal transducer and activator of transcription 3 reduces liver N2 neutrophils and improves liver function and alleviates liver inflammation and fibrosis in ATP7B-knockout mice. Epigenetic silencing of Socs3 expression by transforming growth factor β1 contributes to N2-neutrophil polarization in isolated bone marrow neutrophils.

CONCLUSIONS

Our findings provide a novel prospect that pharmacologic modulation of N2-neutrophil activity should be explored as an alternative therapeutic to improve liver function in Wilson's disease.

Cyclodextrin Polymers Functionalized with Histidine and Carcinine as Chelating Therapeutics for Copper Dyshomeostasis

In recent years, cyclodextrin polymeric nanoparticles have been designed to introduce new properties and extend their medical applications. Based on the features of cyclodextrins, we derivatized cross-linked cyclodextrin polymers with histidine or carcinine moieties. We found that amylases do not hydrolyze cyclodextrin polymers. The new polymers can form copper(II) complexes and may act as nanochelators to counteract copper(II) dyshomeostasis-related diseases. Furthermore, the copper(II) complexes show superoxide dismutase activity, similar to free carcinine and histidine complexes. The antioxidant biological activity of the copper(II) complex formed in situ may protect cells from oxidative damage related to copper dyshomeostasis.

Protective effect of curcumin on hepatolenticular degeneration through copper excretion and inhibition of ferroptosis

BACKGROUND

Hepatolenticular degeneration (HLD) is an autosomal recessive disorder concerning copper metabolism. Copper overload is also accompanied by iron overload in HLD patients, which can lead to ferroptosis. Curcumin, the active component in turmeric, has the potential to inhibit ferroptosis.

PURPOSE

The current study proposed a systematic investigation of the protective effects of curcumin against HLD and the underlying mechanisms.

METHODS

The protective effect of curcumin on toxic milk (TX) mice was studied. Liver tissue was observed via hematoxylin-eosin (H&E) staining and the ultrastructure of the liver tissue was observed through transmission electron microscopy. Copper levels in the tissues, serum, and metabolites were measured by atomic absorption spectrometry (AAS). In addition, serum and liver indicators were evaluated. In cellular experiments, the effect of curcumin on the viability of rat normal liver cells (BRL-3A) was determined via the 3-[4,5-dimethylthiazol-2-yl)]-2,5-diphenyltetrazolium bromide (MTT) assay. Cell and mitochondrial morphology were observed in curcumin-mediated HLD model cells. The intracellular copper ion fluorescence intensity was observed via fluorescence microscopy, and intracellular copper iron content was detected using AAS. Further, oxidative stress indicators were evaluated. Cellular reactive oxygen species (ROS) and cellular mitochondrial membrane potential were examined via flow cytometry. Furthermore, the expression levels of nuclear factor erythroid-2-related factor 2 (Nrf2), heme oxygenase-1 (HO-1), and glutathione peroxidase 4 (GPX4) were determined via western blotting (WB).

RESULTS

The histopathology of the liver confirmed the hepatoprotective effects of curcumin. Curcumin improved copper metabolism in TX mice. Both serum liver enzyme markers and antioxidant enzyme levels indicated the protective effect of curcumin against HLD-related liver injury. The MTT assay results showed that curcumin was protective against excess copper-induced injury. Curcumin improved the morphology of HLD model cells and their mitochondrial morphology. The Cu²⁺ fluorescent probe and the AAS results indicated that curcumin reduced Cu²⁺ content in HLD hepatocytes. In addition, curcumin improved oxidative stress levels and prevented the decline of mitochondrial membrane potential in HLD model cells. The ferroptosis inducer Erastin reversed these effects of curcumin. WB revealed that curcumin promoted Nrf2, HO-1, and GPX4 protein expression in HLD model cells, and the Nrf2 inhibitor ML385 reversed the effects of curcumin.

CONCLUSION

Curcumin demonstrates a protective role by expelling copper and inhibiting ferroptosis, activating the Nrf2/HO-1/GPX4 signaling pathway in HLD.

A Century of Progress on Wilson Disease and the Enduring Challenges of Genetics, Diagnosis, and Treatment

Wilson disease (WD) is a rare, inherited metabolic disorder manifested with varying clinical presentations including hepatic, neurological, psychiatric, and ophthalmological features, often in combination. Causative mutations in the ATP7B gene result in copper accumulation in hepatocytes and/or neurons, but clinical diagnosis remains challenging. Diagnosis is complicated by mild, non-specific presentations, mutations exerting no clear effect on protein function, and inconclusive laboratory tests, particularly regarding serum ceruloplasmin levels. As early diagnosis and effective treatment are crucial to prevent progressive damage, we report here on the establishment of a global collaboration of researchers, clinicians, and patient advocacy groups to identify and address the outstanding challenges posed by WD.

Interactive Effects of Copper-Doped Urological Implants with Tissue in the Urinary Tract for the Inhibition of Cell Adhesion and Encrustation in the Animal Model Rat

The insertion of a ureteral stent provides acute care by restoring urine flow and alleviating urinary retention or dysfunction. The problems of encrustation, bacterial colonization and biofilm formation become increasingly important when ureteral stents are left in place for a longer period of time. One way to reduce encrustation and bacterial adherence is to modify the stent surface with a diamond-like carbon coating, in combination with copper doping. The biocompatibilities of the Elastollan^® base material and the a-C:H/Cu-mulitilayer coating were tested in synthetic urine. The copper content in bladder tissue was determined by atomic absorption spectroscopy and in blood and in urine by inductively coupled plasma mass spectrometry. Encrustations on the materials were analyzed by scanning electron microscopy, energy dispersive X-ray spectroscopy and Fourier transform infrared spectroscopy. A therapeutic window for copper ions of 0.5–1.0 mM was determined to kill bacteria without affecting human urothelial cells. In the rat animal model, it was found that copper release did not reach toxic concentrations in the affecting tissue of the urinary tract or in the blood. The encrustation behavior of the surfaces showed that the roughness of the amorphous carbon layer with the copper doping is probably the causal factor for the higher encrustation.

Wilson Disease: Update on Pathophysiology and Treatment

Wilson disease (WD) is a potentially fatal genetic disorder with a broad spectrum of phenotypic presentations. Inactivation of the copper (Cu) transporter ATP7B and Cu overload in tissues, especially in the liver, are established causes of WD. However, neither specific ATP7B mutations nor hepatic Cu levels, alone, explain the diverse clinical presentations of WD. Recently, the new molecular details of WD progression and metabolic signatures of WD phenotypes began to emerge. Studies in WD patients and animal models revealed the contributions of non-parenchymal liver cells and extrahepatic tissues to the liver phenotype, and pointed to dysregulation of nuclear receptors (NR), epigenetic modifications, and mitochondria dysfunction as important hallmarks of WD pathogenesis. This review summarizes recent advances in the characterization of WD pathophysiology and discusses emerging targets for improving WD diagnosis and treatment.

Inborn errors of metabolism: Lessons from iPSC models

The possibility of reprogramming human somatic cells to pluripotency has opened unprecedented opportunities for creating genuinely human experimental models of disease. Inborn errors of metabolism (IEMs) constitute a greatly heterogeneous class of diseases that appear, in principle, especially suited to be modeled by iPSC-based technology. Indeed, dozens of IEMs have already been modeled to some extent using patient-specific iPSCs. Here, we review the advantages and disadvantages of iPSC-based disease modeling in the context of IEMs, as well as particular challenges associated to this approach, together with solutions researchers have proposed to tackle them. We have structured this review around six lessons that we have learnt from those previous modeling efforts, and that we believe should be carefully considered by researchers wishing to embark in future iPSC-based models of IEMs.

The Rat Genome Database (RGD) facilitates genomic and phenotypic data integration across multiple species for biomedical research

Model organism research is essential for discovering the mechanisms of human diseases by defining biologically meaningful gene to disease relationships. The Rat Genome Database (RGD, ( https://rgd.mcw.edu )) is a cross-species knowledgebase and the premier online resource for rat genetic and physiologic data. This rich resource is enhanced by the inclusion and integration of comparative data for human and mouse, as well as other human disease models including chinchilla, dog, bonobo, pig, 13-lined ground squirrel, green monkey, and naked mole-rat. Functional information has been added to records via the assignment of annotations based on sequence similarity to human, rat, and mouse genes. RGD has also imported well-supported cross-species data from external resources. To enable use of these data, RGD has developed a robust infrastructure of standardized ontologies, data formats, and disease- and species-centric portals, complemented with a suite of innovative tools for discovery and analysis. Using examples of single-gene and polygenic human diseases, we illustrate how data from multiple species can help to identify or confirm a gene as involved in a disease and to identify model organisms that can be studied to understand the pathophysiology of a gene or pathway. The ultimate aim of this report is to demonstrate the utility of RGD not only as the core resource for the rat research community but also as a source of bioinformatic tools to support a wider audience, empowering the search for appropriate models for human afflictions.

Non-Ceruloplasmin Copper as a Stratification Biomarker of Alzheimer's Disease Patients: How to Measure and Use It

Alzheimer's disease (AD) is a type of dementia very common in the elderly. A growing body of recent evidence has linked AD pathogenesis to copper (Cu) dysmetabolism in the body. In fact, a subset of patients affected either by AD or by its prodromal form known as Mild Cognitive Impairment (MCI) have been observed to be unable to maintain a proper balance of Cu metabolism and distribution and are characterized by the presence in their serum of increased levels of Cu not bound to ceruloplasmin (non-ceruloplasmin Cu). Since serum non-ceruloplasmin Cu is a biomark- er of Wilson's disease (WD), a well-known condition of Cu-driven toxicosis, in this review, we pro- pose that in close analogy with WD, the assessment of non-ceruloplasmin Cu levels can be exploit- ed as a cost-effective stratification and susceptibility/risk biomarker for the identification of some AD/MCI individuals. The approach can also be used as an eligibility criterion for clinical trials aim- ing at investigating Cu-related interventions against AD/MCI.

Wilson's disease: update on pathogenesis, biomarkers and treatments

Wilson's disease is an autosomal-recessive disorder of copper metabolism caused by mutations in ATP7B and associated with neurological, psychiatric, ophthalmological and hepatic manifestations. Decoppering treatments are used to prevent disease progression and reduce symptoms, but neurological outcomes remain mixed. In this article, we review the current understanding of pathogenesis, biomarkers and treatments for Wilson's disease from the neurological perspective, with a focus on recent advances. The genetic and molecular mechanisms associated with ATP7B dysfunction have been well characterised, but despite extensive efforts to identify genotype-phenotype correlations, the reason why only some patients develop neurological or psychiatric features remains unclear. We discuss pathological processes through which copper accumulation leads to neurodegeneration, such as mitochondrial dysfunction, the role of brain iron metabolism and the broader concept of selective neuronal vulnerability in Wilson's disease. Delayed diagnoses continue to be a major problem for patients with neurological presentations. We highlight limitations in our current approach to making a diagnosis and novel diagnostic biomarkers, including the potential for newborn screening programmes. We describe recent progress in developing imaging and wet (fluid) biomarkers for neurological involvement, including findings from quantitative MRI and other neuroimaging studies, and the development of a semiquantitative scoring system for assessing radiological severity. Finally, we cover the use of established and novel chelating agents, paradoxical neurological worsening, and progress developing targeted molecular and gene therapy for Wilson's disease, before discussing future directions for translational research.

Copper Imbalance in Alzheimer's Disease: Meta-Analysis of Serum, Plasma, and Brain Specimens, and Replication Study Evaluating ATP7B Gene Variants

Evidence indicates that patients with Alzheimer's dementia (AD) show signs of copper (Cu) dyshomeostasis. This study aimed at evaluating the potential of Cu dysregulation as an AD susceptibility factor. We performed a meta-analysis of 56 studies investigating Cu biomarkers in brain specimens (pooled total of 182 AD and 166 healthy controls, HC) and in serum/plasma (pooled total of 2929 AD and 3547 HC). We also completed a replication study of serum Cu biomarkers in 97 AD patients and 70 HC screened for rs732774 and rs1061472 ATP7B, the gene encoding for the Cu transporter ATPase7B. Our meta-analysis showed decreased Cu in AD brain specimens, increased Cu and nonbound ceruloplasmin (Non-Cp) Cu in serum/plasma samples, and unchanged ceruloplasmin. Serum/plasma Cu excess was associated with a three to fourfold increase in the risk of having AD. Our replication study confirmed meta-analysis results and showed that carriers of the ATP7B AG haplotype were significantly more frequent in the AD group. Overall, our study shows that AD patients fail to maintain a Cu metabolic balance and reveals the presence of a percentage of AD patients carrying ATP7B AG haplotype and presenting Non-Cp Cu excess, which suggest that a subset of AD subjects is prone to Cu imbalance. This AD subtype can be the target of precision medicine-based strategies tackling Cu dysregulation.

Comprehensive RNA-Seq Analysis of Potential Therapeutic Targets of Gan-Dou-Fu-Mu Decoction for Treatment of Wilson Disease Using a Toxic Milk Mouse Model

Background: Gan–Dou–Fu–Mu decoction (GDFMD) improves liver fibrosis in experimental and clinical studies including those on toxic mouse model of Wilson disease (Model). However, the mechanisms underlying the effect of GDFMD have not been characterized. Herein, we deciphered the potential therapeutic targets of GDFMD using transcriptome analysis.

Methods: We constructed a tx-j Wilson disease (WD) mouse model, and assessed the effect of GDFMD on the liver of model mice by hematoxylin and eosin, Masson, and immunohistochemical staining. Subsequently, we identified differentially expressed genes (DEGs) that were upregulated in the Model (Model vs. control) and those that were downregulated upon GDFMD treatment (compared to the Model) using RNA-sequencing (RNA-Seq). Biological functions and signaling pathways in which the DEGs were involved were determined by gene ontology (GO) and Kyoto encyclopedia of genes and genomes (KEGG) pathway analyses. A protein–protein interaction (PPI) network was constructed using the STRING database, and the modules were identified using MCODE plugin with the Cytoscape software. Several genes identified in the RNA-Seq analysis were validated by real-time quantitative PCR.

Results: Total of 2124 DEGs were screened through the Model vs. control and Model vs. GDFMD comparisons, and dozens of GO and KEGG pathway terms modulated by GDFMD were identified. Dozens of pathways involved in metabolism (including metabolic processes for organic acids, carboxylic acids, monocarboxylic acids, lipids, fatty acids, cellular lipids, steroids, alcohols, eicosanoids, long-chain fatty acids), immune and inflammatory response (such as complement and coagulation cascades, cytokine–cytokine receptor interaction, inflammatory mediator regulation of TRP channels, antigen processing and presentation, T-cell receptor signaling pathway), liver fibrosis (such as ECM-receptor interactions), and cell death (PI3K-Akt signaling pathway, apoptosis, TGF-beta signaling pathway, etc.) were identified as potential targets of GDFMD in the Model. Some hub genes and four modules were identified in the PPI network. The results of real-time quantitative PCR analysis were consistent with those of RNA-Seq analysis.

Conclusions: We performed gene expression profiling of GDFMD-treated WD model mice using RNA-Seq analysis and found the genes, pathways, and processes effected by the treatment. Our study provides a theoretical basis to prevent liver fibrosis resulting from WD using GDFMD.

COMMD1 Exemplifies the Power of Inbred Dogs to Dissect Genetic Causes of Rare Copper-Related Disorders

Wilson's Disease is a rare autosomal recessive disorder in humans, often presenting with hepatic copper overload. Finding the genetic cause of a rare disease, especially if it is related to food constituents like the trace element copper, is a Herculean task. This review describes examples of how the unique population structure of in-bred dog strains led to the discovery of a novel gene and two modifier genes involved in inherited copper toxicosis. COMMD1, after the discovery in 2002, was shown to be a highly promiscuous protein involved in copper transport, protein trafficking/degradation, regulation of virus replication, and inflammation. Mutations in the ATP7A and ATP7B proteins in Labrador retrievers and Dobermann dogs resulted in a wide variation in hepatic copper levels in these breeds. To our knowledge, numerous dog breeds with inherited copper toxicosis of unknown genetic origin exist. Therefore, the possibility that men's best friend will provide new leads in rare copper storage diseases seems realistic.

Copper and zinc concentrations in the breast milk of mothers undergoing treatment for Wilson's disease: a prospective study

OBJECTIVE

To evaluate the concentrations of copper and zinc in the breast milk of mothers undergoing treatment for Wilson's disease (WD) and clarify whether they can safely breast feed their infants.

DESIGN

This was an observational and prospective study in an individual-based case series.

SETTING

Breast milk samples were collected from participants across Japan from 2007 to 2018 at the Department of Pediatrics, Teikyo University in Tokyo. This was a primary-care level study. Clinical data were collected from the participants' physicians.

PATIENTS

Eighteen Japanese mothers with WD who were treated with trientine, penicillamine or zinc, and 25 healthy mothers as controls, were enrolled.

MAIN OUTCOME MEASURES

Whey exacted from the milk was used to evaluate the distribution of copper by high-performance liquid chromatography-inductively coupled plasma mass spectrometry. Copper and zinc concentrations in the breast milk samples were analysed by atomic absorption spectrometry.

RESULTS

Copper distribution was normal in the breast milk of mothers with WD treated with trientine, penicillamine or zinc. No peak was detected for trientine-bound or penicillamine-bound copper. The mean copper concentrations in the mature breast milk of patients treated with trientine, penicillamine and zinc were 29.6, 26 and 38 µg/dL, respectively, and were within the normal range compared with the value in healthy controls (33 µg/dL). Likewise, mean zinc concentrations were normal in the mature breast milk of patients treated with trientine and penicillamine (153 and 134 µg/dL, respectively vs 160 µg/dL in healthy controls). Zinc concentrations in the breast milk of mothers treated with zinc were significantly higher than those in control milk. All infants were born normally, breast fed by mothers undergoing treatment and exhibited normal development.

CONCLUSIONS

Our results suggest that mothers with WD can safely breast feed their infants, even if they are receiving treatment for WD.

MiADMSA abrogates chronic copper-induced hepatic and immunological changes in Sprague Dawley rats

Wilson disease (WD) is an autosomal-recessive disorder associated with the impaired copper metabolism, resulting in hepatic and neurologic manifestations. D-Pencillamine (DPA) is a first-line of treatment however, monoisoamyl 2, 3-dimercaptosuccinic acid (MiADMSA), is gaining recognition recently as a future chelating agent of choice. We evaluated the effects of MiADMSA against copper-induced (20 mg/kg, orally, once, daily for 16 weeks) hepatic and immunological changes in the male Sprague Dawley (SD) rats. Copper overload increased the levels of pro-oxidant and concurrently decreased the levels of antioxidant enzymes in the liver. Increased oxidative stress triggered the up-regulation of pro-inflammatory cytokines (TNF-α, IL-1β, IL-6) in the liver and down-regulated the anti-inflammatory cytokine IL-4. Altered liver function parameters as well as serum immunoglobulins' (IgG, IgA, IgE, and IgM) levels, were also noted. MiADMSA treatment restored most of copper altered biochemical and immunological changes. Further, the histopathological changes proved that MiADMSA treatment ameliorated copper induced hepatic injury. Infra red spectra of liver tissue indicated shift in the characteristic -OH peak during copper exposure while the shifting came to normal in MiADMSA administered rat liver. We conclude that MiADMSA could be a promising antidote for the chronic copper toxicity and possibly in the clinical management of WD.

Variations in ATP7B in cats with primary copper-associated hepatopathy

OBJECTIVES

Primary copper-associated hepatopathy (PCH) has been reported in young cats. Although our group recently reported a young cat with PCH harbouring single-nucleotide variations in ATP7B, limited information is available regarding its association with the pathogenesis of feline PCH. The objective of this study was to investigate the prevalence of ATP7B variations in cats with PCH.

METHODS

Rhodanine staining was performed to detect hepatic copper accumulation (HCA) in intraoperative liver tissue specimens from 54 cats. In cats with HCA, variations in ATP7B and COMMD1 and serum ceruloplasmin activity were analysed.

RESULTS

Based on age, liver histopathological findings and hepatic distribution of accumulated copper, PCH was suspected in 4/54 cats. Sequence analysis of ATP7B and COMMD1 revealed single-nucleotide variations in ATP7B in 3/4 cats with PCH. Among the cats with PCH, one showed remarkably low serum ceruloplasmin activity, while the other three did not.

CONCLUSIONS AND RELEVANCE

The results of this study suggest that some cats with PCH harbour single-nucleotide variations in ATP7B, suggesting that feline PCH is an equivalent disorder to human Wilson's disease. This study provides basic evidence facilitating further studies of the pathophysiology and treatment of feline PCH.

Activation of HIF-1 signaling ameliorates liver steatosis in zebrafish atp7b deficiency (Wilson's disease) models

Wilson's disease is an autosomal recessive disease characterized by excess copper accumulated in the liver and brain. It is caused by mutations in the copper transporter gene ATP7B. However, based on the poor understanding of the transcriptional program involved in the pathogenesis of Wilson's disease and the lack of more safe and efficient therapies, the identification of novel pathways and the establishment of complementary model systems of Wilson's disease are urgently needed. Herein, we generated two zebrafish atp7b-mutant lines using the CRISPR/Cas9 editing system, and the mutants developed hepatic and behavioral deficits similar to those observed in humans with Wilson's disease. Interestingly, we found that atp7b-deficient zebrafish embryos developed liver steatosis under low-dose Cu exposure, and behavioral deficits appeared under high-dose Cu exposure. Analyses of publicly available transcriptomic data from ATP7B-knockout HepG2 cells demonstrated that the HIF-1 signaling pathway is downregulated in ATP7B-knockout HepG2 cells compared with wildtype cells following Cu exposure. The HIF-1 signaling pathway was also downregulated in our atp7b-deficient zebrafish mutants following Cu exposure. Furthermore, we demonstrate that activation of the HIF-1 signaling pathway with the chemical compound FG-4592 or DMOG ameliorates liver steatosis and reduces accumulated Cu levels in zebrafish atp7b deficiency models. These findings introduce a novel prospect that modulation of the HIF-1 signaling pathway should be explored as a novel strategy to reduce copper toxicity in Wilson's disease patients.

Animal Models of Normal and Disturbed Iron and Copper Metabolism

Research on the interplay between iron and copper metabolism in humans began to flourish in the mid-20th century, and diseases associated with dysregulated homeostasis of these essential trace minerals are common even today. Iron deficiency is the most frequent cause of anemia worldwide, leading to significant morbidity, particularly in developing countries. Iron overload is also quite common, usually being the result of genetic mutations which lead to inappropriate expression of the iron-regulatory hormone hepcidin. Perturbations of copper homeostasis in humans have also been described, including rare genetic conditions which lead to severe copper deficiency (Menkes disease) or copper overload (Wilson disease). Historically, the common laboratory rat (Rattus norvegicus) was the most frequently utilized species to model human physiology and pathophysiology. Recently, however, the development of genetic-engineering technology combined with the worldwide availability of numerous genetically homogenous (i.e., inbred) mouse strains shifted most research on iron and copper metabolism to laboratory mice. This created new opportunities to understand the function of individual genes in the context of a living animal, but thoughtful consideration of whether mice are the most appropriate models of human pathophysiology was not necessarily involved. Given this background, this review is intended to provide a guide for future research on iron- and copper-related disorders in humans. Generation of complementary experimental models in rats, swine, and other mammals is now facile given the advent of newer genetic technologies, thus providing the opportunity to accelerate the identification of pathogenic mechanisms and expedite the development of new treatments to mitigate these important human disorders.

Towards Bioengineered Liver Stem Cell Transplantation Studies in a Preclinical Dog Model for Inherited Copper Toxicosis

Wilson Disease is a rare autosomal recessive liver disorder in humans. Although its clinical presentation and age of onset are highly variable, hallmarks include signs of liver disease, neurological features and so-called Kayser-Fleischer rings in the eyes of the patient. Hepatic copper accumulation leads to liver disease and eventually to liver cirrhosis. Treatment options include life-long copper chelation therapy and/or decrease in copper intake. Eventually liver transplantations are indicated. Although clinical outcome of liver transplantations is favorable, the lack of suitable donor livers hampers large numbers of transplantations. As an alternative, cell therapies with hepatocytes or liver stem cells are currently under investigation. Stem cell biology in relation to pets is in its infancy. Due to the specific population structure of dogs, canine copper toxicosis is frequently encountered in various dog breeds. Since the histology and clinical presentation resemble Wilson Disease, we combined genetics, gene-editing, and matrices-based stem cell cultures to develop a translational preclinical transplantation model for inherited copper toxicosis in dogs. Here we describe the roadmap followed, starting from the discovery of a causative copper toxicosis mutation in a specific dog breed and culminating in transplantation of genetically-engineered autologous liver stem cells.

Laser Ablation Inductively Coupled Plasma Spectrometry: Metal Imaging in Experimental and Clinical Wilson Disease

Wilson disease is an inherited disorder caused by mutations in the ATP7B gene resulting in copper metabolism disturbances. As a consequence, copper accumulates in different organs with most common presentation in liver and brain. Chelating agents that nonspecifically chelate copper, and promote its urinary excretion, or zinc salts interfering with the absorption of copper from the gastrointestinal tract, are current medications. Also gene therapy, restoring ATP7B gene function or trials with bis-choline tetrathiomolybdate (WTX101) removing excess copper from intracellular hepatic copper stores and increasing biliary copper excretion, is promising in reducing body’s copper content. Therapy efficacy is mostly evaluated by testing for evidence of liver disease and neurological symptoms, hepatic synthetic functions, indices of copper metabolisms, urinary copper excretions, or direct copper measurements. However, several studies conducted in patients or Wilson disease models have shown that not only the absolute concentration of copper, but also its spatial distribution within the diseased tissue is relevant for disease severity and outcome. Here we discuss laser ablation inductively coupled plasma spectrometry imaging as a novel method for accurate determination of trace element concentrations with high diagnostic sensitivity, spatial resolution, specificity, and quantification ability in experimental and clinical Wilson disease specimens.

Preclinical models of Wilson's disease, why dogs are catchy alternatives

Copper toxicosis is frequently encountered in various dog breeds. A number of differences and similarities occur between Wilson disease and copper toxicosis in Bedlington terriers, caused by a mutation in the COMMD1 gene, and copper toxicosis in Labrador retrievers, caused by mutations in both ATP7A and ATP7B gene. First the specific population structure of dog breeds is explained with reference to its applicability for genetic investigations. The relatively large body size (variable from less than 1 kg to over 50 kg) and life-span (over 10 years) of dogs facilitates preclinical studies on safety on long-term effects of novel procedures. Then copper toxicosis in the two dog breeds is described in detail with an emphasis on the functions of the causative proteins. Some of the advantages of this species for preclinical studies are described with an example of liver stem cell transplantations in COMMD1 deficient dogs. Since the genetic background of copper toxicosis in other dogs' breeds has not yet been elucidated, it is conceivable that novel copper-related gene products or modifier genes will be discovered. About a century after the Novel prize was awarded to the research on dogs (Pavlov), dogs are in spotlight again as important preclinical model animals.

Hepatic copper accumulation in a young cat with familial variations in the ATP7B gene

A 9‐month‐old intact crossbred female cat was presented with jaundice, intermittent anorexia and lethargy, increased hepatic enzyme activities, and hyperammonemia. Abdominal ultrasound and computed tomographic examinations determined that the liver had a rounded and irregular margin, and histopathological examination identified excessive accumulation of copper hepatocytes in the liver. Concentrations of both blood and urine copper were higher than in healthy cats. The patient responded well to treatment with penicillamine. Clinicopathological abnormalities and clinical signs improved within 2 months, and the patient was alive for >9 months after starting treatment. Genetic examination determined that the patient and its littermate had a single‐nucleotide variation (SNV, p. T1297R) that impaired the function of the ATP7B gene product; the gene that is mutated in patients with Wilson's disease (WD). Hepatic copper accumulation was believed to be associated with the SNV of the ATP7B gene, and the patient had a genetic disorder of copper metabolism equivalent to WD in humans.