Determination of ultrafiltrable and exchangeable copper in plasma: stability and reference values in healthy subjects

Relative Exchangeable Copper, Exchangeable Copper and Total Copper in the Diagnosis of Wilson Disease

BACKGROUND AND AIMS

Diagnosing Wilson disease (WD) remains challenging. The exchangeable copper (CuEXC) methodology measures the non-ceruloplasmin-bound copper fraction in serum. Relative exchangeable copper (REC), the ratio of CuEXC to total serum copper (Total Cu), has been proposed as a potential diagnostic biomarker. This study aimed to evaluate the diagnostic performance of these three copper biomarkers in WD.

METHODS

CuEXC and Total Cu levels were measured in newly diagnosed treatment-naïve patients with WD (n = 13), treated WD (n = 91), non-Wilsonian hepatic disease (n = 206) and non-Wilsonian acute liver failure (n = 22). REC, CuEXC and Total Cu were compared among groups. Receiver-operating characteristic analyses were performed.

RESULTS

Median REC was significantly elevated among patients with WD compared to all other groups combined (23.6% vs. 4.9%, p < 0.001). The opposite was found for Total Cu (3.5 μmol/L vs. 17.2 μmol/L, p < 0.001). In newly diagnosed patients with WD, median REC was significantly higher than in treated patients (29.1% vs. 21.6%, p = 0.008). The optimal diagnostic cut-off value for REC was ≥ 13.8% (sensitivity 100% and specificity 99.6%) for newly diagnosed patients versus those with non-Wilsonian hepatic disease. For Total Cu, the optimal cut-off was ≤ 7.1 μmol/L (sensitivity 61.5% and specificity 99.1%) for newly diagnosed patients with WD versus those with non-Wilsonian hepatic disease.

CONCLUSION

Our data support the diagnostic value of REC in WD. The more broadly available Total Cu also demonstrates a strong diagnostic performance and may be useful in initial work-up. We suggest including REC and/or Total Cu in a future revision of the Leipzig score.

Copper in human health: From COVID 19 to neurodegenerative diseases

Copper (Cu) exists in two oxidation states Cu+I and Cu+II yielding formation of enzymes involved in biological processes. In higher concentrations, by oxidative process and ROS production, Cu is toxic towards plants, humans and animals livers as observed in Wilson disease or sheep scrapie. Fighting according to the Fenton reaction against bacteria and viruses, has been proposed as a mean of combatting nosocomial diseases and complementary to COVID19 vaccination. In humans, Cu is stocked in liver, muscle or bound to brain protein as ß-APP, tau-protein, α-synuclein, ubiquitin or prion which present antioxidant properties when Cu-bonded. In abnormal ß-sheet conformation, they can trigger neurodegenerative diseases such as Alzheimer(AD), Parkinson(PD) and ALS. In these diseases, blood copper increase correlated with brain copper decrease has been described. In AD, abnormal D-serine has been detected in blood and cerebrospinal fluid. D-glutamate and D-alanine blood levels have been found in AD and could also be controlled with Cu and ceruloplasmin in a possible disease screening test. This abnormal D-conformation might result from epimerization of physiologically L-conformation brain peptides into protease-resistant D-enantiomers. This has previously been experimentally demonstrated for Bovine Spongiform Encephalopathy in a free Cu reductive medium with UV-induced free radicals. The Cu brain protective effect against free radicals was restored with cupric addition in oxidizing medium. Cupric supplementation in the brain, might restore Cu protection and slow down neurodegenerative processes. To lower side effects, Cu amino-acid complexes able to cross the blood brain barrier might be suggested for a Cu transfer to the brain.

EASL-ERN Clinical Practice Guidelines on Wilson's disease

Wilson's disease is an autosomal recessive disorder of copper metabolism which affects the liver, brain and other organs. Diagnosis is based on: clinical features; biochemical tests, including plasma ceruloplasmin concentration, 24-h urinary copper excretion, copper content in the liver; and molecular analysis. Leipzig score and additionally relative exchangeable copper determination are recommended for diagnosis. Pharmacological therapy comprises chelating agents (penicillamine, trientine) and zinc salts, while only chelators are recommended for significant liver disease. Monitoring is based on clinical symptoms, liver tests and copper metabolism (urinary copper excretion, exchangeable copper) to detect poor compliance and over/under-treatment. Acute liver failure is challenging as making a diagnosis is difficult and pharmacological therapy may not be sufficient to save life. Liver transplantation has a well-defined role in Wilsonian acute hepatic failure but may also be considered in neurological disease.

A comparative analysis in monitoring 24-hour urinary copper in wilson disease: sampling on or off treatment?

BACKGROUND & AIM

Twenty-four-hour urinary copper excretion (24 h-UCE) is the standard diagnostic tool for dose adjustments in maintenance therapy in Wilson disease (WD) patients. Guidelines lack data if both variants of 24 h-UCE measurement (with or without 48 h of treatment interruption) are equally interpretable.

METHODS

Eighty-four patients with a confirmed diagnosis of WD treated with chelators (50% of patients with D-Penicillamine and 50% with trientine) and with pairwise 24-h-UCE values on-therapy and off-therapy were included in the analysis. Pairwise urinary sampling between October 2022 (T0) and a 12-month FU (T2) was compared, and exchangeable copper (CuEXC) was additionally measured at T0.

RESULTS

Among the 84 patients, 65% had predominant hepatic symptoms, the median age was 42 years, and 58% were female. At T0, patients were in the stable maintenance phase, with a median treatment duration of 21.9 years. The levels of the biochemical markers liver and copper metabolism remained stable over the 12-month observation period for all patients. 24 h-UCE off-therapy significantly decreased from T0 to T2 (p = 0.03), whereas no statistically significant differences were detected for 24 h-UCE after therapy. Both sampling methods did not correlate. CuEXC was significantly correlated with 24 h-UCE after 48 h of dose interruption (p = 0.018) but not with 24 h-UCE after therapy. A total of 46% of the 24 h-UCE value pairs were discordant, laying out the aimed therapeutic ranges given in current international guidelines.

CONCLUSION

Off-therapy 24 h-UCE reflects the "free" copper pool more accurately than does urinary sampling. The study shows discordant results for both sampling methods in approximately half of the patients, revealing that interpretation of 24 h-UCE with respect to chelator-dosing decisions should be performed with caution.

Exchangeable serum copper: Adult and pediatric reference intervals and in vitro stability in a nordic cohort

Wilson disease (WD) is a rare genetic disorder characterized by copper overload, primarily affecting the liver and brain, and the organ damage is believed to be caused by non-ceruloplasmin-bound copper (NCC). Accurate and early diagnosis is important for prognosis. Recently, a method for the measurement of NCC, exchangeable serum copper (CuEXC), was developed and shown to be a promising marker of WD, especially as the fraction of total copper, relative exchangeable copper (REC). This study aimed to validate the CuEXC extraction method and establish reference intervals for CuEXC and REC, as well as to examine short- and long-term stability of CuEXC in serum samples. The adult reference interval for CuEXC was 0.61-1.62 µmol/L and for REC 3.0-9.7 % based on 120 blood donors. Based on 88 children, the reference intervals for CuEXC was 0.45-1.16 µmol/L. The intervals for REC were 1.8-5.8 % for children <10 years and 2.3-8.5 % for children ≥10 years. Regarding stability, CuEXC increased following a logarithmic scale in uncentrifuged serum and exceeded the permissible difference of 10 % after 4 h. With long-term freezing at -20 °C, CuEXC was stable for 1.7 months. In conclusion, reference intervals for CuEXC and REC were established and confirmed to be substantially lower in children. Accurate reference intervals are important to ensure timely diagnosis of WD. Finally, our findings on stability have important implications and highlight the need for standardization of the pre-analytical handling of CuEXC samples in order to obtain comparable results within and between laboratories both for clinical and research use.

Wilson Disease: Novel Diagnostic and Therapeutic Approaches

The Wilson disease (WD) research field is rapidly evolving, and new diagnostic and therapeutical approaches are expected to be change-gamers in the disease for the incoming years, after decades of slow changing options. Non-ceruloplasmin-bound copper assays for circulating bioavailable copper are being tested for use in monitoring therapy and may also help in the diagnosis of new cases of WD. Other diagnostic advances include the use of quantitative detection of ATP7B peptides in dried blood spots, a method that is being tested for use in the newborn screening for WD, and the use of metallothionein immunostaining of liver biopsy specimens to differentiate WD from other liver diseases. Ongoing and future trials of gene therapy and use of methanobactin are expected to restore biliary copper excretion from the liver, thus making a cure for WD a plausible therapeutic objective. With the aim of helping updating physicians, this review summarizes the novel methods for WD diagnosis and future therapies. Advancing understanding of the scientific advances that can be applied to WD will be critical for ensuring that our patients will receive the best current and future care.

Exchangeable Copper Excess and Zinc Deficiency in the Serum of Patients with Colorectal Cancer

Copper (Cu) and Zinc (Zn) are altered in colorectal cancer (CRC) but their association with the clinical classification of the tumor has not been fully explored. To examine the association of Cu and Zn homeostasis in the onset and severity of CRC, we performed an exploratory case-control study comparing the serum levels for Cu, the exchangeable component of Cu in serum (CuExc), Zn, the ratio between them (CuExc:Zn), ceruloplasmin [Cp, concentration (iCp) and its activity (eCp), Cp specific activity (eCp:iCp)], and the Cu:Cp, assessed in 31 consecutive CRC patients before surgical resection to those obtained from 37 healthy controls (CTRL). Additionally, we correlated the analyte levels with the indices of the pathological tumor, node, and metastasis (TNM) staging, namely tumor (T), node (N), and metastasis (M), evaluated at the histopathological examination. We found that Cu, CuExc, CuExc:Zn, iCp, eCp, eCp:iCp, and Cu:Cp ratios increased while Zn decreased in CRC patients. In addition, correlation analyses showed that CuExc and Zn levels confirmed the CRC diagnosis. Specifically, CuExc:Zn further increased the discrimination between the individuals of the two groups, providing an area under the curve (ROC AUC) = 0.94. Elevated CuExc was the strongest factor associated with CRC resulting in 15-fold increased odds. These data were confirmed through a multivariable regression model revealing an effect of Zn and CuExc on the CRC risk, with the CuExc resulting in 11-fold increased odds of having the disease. We also found that most of the Cu biological variables analyzed were associated with T, while the CuExc was associated with M. The current pilot study demonstrates that excess labile Cu pool, Zn deficiency, and even further their combination in the CuExc:Zn provide information about CRC in terms of diagnosis, risk of having CRC, and CRC disease stage.

Total Copper and Labile Bound Copper Fraction as a Selective and Sensitive Tool in the Evaluation of Wilson Disease

BACKGROUND

A dual filtration-based method for determination of serum labile bound copper (LBC) and LBC fraction (LBC/total copper) was developed. Reduced total copper, elevated LBC, and elevated LBC fraction have been reported in Wilson disease (WD).

METHODS

To evaluate the diagnostic performance of these markers, samples were obtained from 21 WD treatment-naïve (WD-TN, no WD treatment or <28 days of treatment) patients, 46 WD standard-of-care-treated (WD-SOC) patients, along with 246 patients representing other potential disorders of copper status. These were then compared to 213 reference interval population patients.

RESULTS

Receiver operating characteristic curves for the reference population vs WD-TN yielded areas under the curve for total copper, LBC, and LBC fraction, of 0.99, 0.81, and 0.98, respectively. Using Youden cutoffs, sensitivity/specificity for WD-TN was 95%/97% for total copper, 71%/85% for LBC, and 95%/94% for LBC fraction. LBC values, but not total copper and LBC fraction, differed substantially between WD-TN and WD-SOC cohorts.We propose a dual model wherein total copper and LBC fraction results must agree to be classified as a "positive" or "negative" result for WD. This correctly classified 19/21 WD-TN patients as positive, and 194/213 reference interval patients as negative. The remaining "indeterminate" patients (representing approximately 9% of the reference and the WD-TN populations) exhibited conflicting total copper and LBC fraction results. When indeterminate results are excluded, this model exhibited apparent 100% sensitivity/specificity.

CONCLUSIONS

Agreement of total serum copper and LBC fraction classification may constitute an effective "rule-in" and "rule-out" assessment for WD-TN patients.

Exchangeable copper for patients with Wilson disease at follow-up: Rethinking normal ranges or changing methodology

BACKGROUND AND AIM

Determining suitable copper parameters for monitoring Wilson disease remains a topic of ongoing discussion. International recommendations currently rely on the combination of urinary copper excretion and nonspecific liver markers when considering therapy and time elapsed since diagnosis. The emergence of exchangeable copper (CuEX) as a novel measurement reflecting the "free copper pool" held promise as a valuable target to ensure metabolic stability during follow-up, although the validation of target ranges remains unknown. We aimed to evaluate CuEX quantification in repeated samples from 92 real-world patients with Wilson disease during a 2-year period.

APPROACH

Patients were classified as "stable" if a diagnosis had been made more than 1 year before and were compliant with stable anti-copper drug and dose. Otherwise, patients were classified as "nonstable."

RESULTS

Two hundred and thirteen CuEX samples were obtained per clinical practice. Overall, 57% of CuEX measurements fell below the reference "range of normality," whereas only 34% were within and 9% were above normal levels. There was no association of CuEX levels with therapy, elapsed time from diagnosis, or clinical stability, although most of the samples above normality corresponded to nonstable patients. Only 23.4% of the CuEX samples were aligned with data obtained from concomitant urinary copper excretion.

CONCLUSIONS

Our findings suggest that CuEX is a suboptimal tool for assessing copper homeostasis when used alone and should be used with caution if no additional information is available. Normal reference intervals for Wilson disease-treated patients should be redefined, as most CuEX quantifications fell in the lower range, with no sign of overtreatment in these patients.

Non-ceruloplasmin copper and urinary copper in clinically stable Wilson disease: Alignment with recommended targets

Background & Aims

Wilson disease (WD) is caused by accumulation of copper primarily in the liver and brain. During maintenance therapy of WD with D-penicillamine, current guidelines recommend on-treatment ranges of urinary copper excretion (UCE) of 200-500 μg/24 h and serum non-ceruloplasmin-bound copper (NCC) of 50-150 μg/L. We compared NCC (measured by two novel assays) and UCE from patients with clinically stable WD on D-penicillamine therapy with these recommendations.

Methods

This is a secondary analysis of data from the Chelate trial (NCT03539952) that enrolled physician-selected patients with clinically stable WD on D-penicillamine maintenance therapy (at an unaltered dose for at least 4 months). We analyzed laboratory samples from the first screening visit, prior to interventions. NCC was measured by either protein speciation (NCC-Sp) using anion exchange high-performance liquid chromatography protein speciation followed by copper determination with inductively coupled plasma mass spectroscopy or as exchangeable copper (NCC-Ex). NCC-Sp was also analyzed in healthy controls (n = 75).

Results

In 76 patients with WD with 21.3±14.3 average treatment-years, NCC-Sp (mean±SD: 56.6±26.2 μg/L) and NCC-Ex (mean±SD: 57.9±24.7 μg/L) were within the 50-150 μg/L target in 61% and 54% of patients, respectively. In addition, 36% and 31%, respectively, were even below the normal ranges (NCC-Sp: 46-213 μg/L, NCC-Ex: 41-71 μg/L). NCC-Ex positively correlated with NCC-Sp (r2 = 0.66, p <0.001) but with systematic deviation. UCE was outside the 200-500 μg/24 h target range in 58%. Only 14/69 (20%) fulfilled both the NCC-Sp and UCE targets. Clinical or biochemical signs of copper deficiency were not detected.

Conclusion

Clinically stable patients with WD on maintenance D-penicillamine therapy frequently have lower NCC-Sp or higher UCE than current recommendations without signs of overtreatment. Further studies are warranted to identify appropriate target ranges of NCC-Sp, NCC-Ex and UCE in treated WD.

Impact and implications

Chelator treatment of patients with Wilson disease (WD) is currently guided by measurements of non-ceruloplasmin-bound copper (NCC) and 24 h urinary copper excretion (UCE) but validation is limited. In 76 adults with ≈21 years history of treated WD and clinically stable disease on D-penicillamine therapy, NCC was commonly found to be below normal values and recommended target ranges whether measured by protein speciation (NCC-Sp) or as exchangeable copper (NCC-Ex), while UCE values were above the recommended target range in 49%. Common wisdom would suggest overtreatment in these cases, but no clinical or biochemical signs of copper deficiency were observed. Exploratory analysis of liver enzymes suggested that NCC below levels seen in controls may be beneficial, while the relation to UCE was less clear. The data calls for critical re-evaluation of target ranges for treatment of WD, specific for drug and laboratory methodology.

Clinical trial number

(NCT03539952).

Accurate non-ceruloplasmin bound copper: a new biomarker for the assessment and monitoring of Wilson disease patients using HPLC coupled to ICP-MS/MS

OBJECTIVES

Assessment of Wilson disease is complicated, with neither ceruloplasmin, nor serum or urine copper, being reliable. Two new indices, accurate non-ceruloplasmin copper (ANCC) and relative ANCC were developed and applied to a cohort of 71 patients, as part of a Wilson Disease Registry Study.

METHODS

Elemental copper-protein speciation was developed for holo-ceruloplasmin quantitation using strong anion exchange chromatography coupled to triple quadrupole inductively coupled plasma mass spectrometry. The serum proteins were separated using gradient elution and measured at m/z 63 (63Cu+) and 48 (32S16O+) using oxygen reaction mode and Cu-EDTA as calibration standard. The ANCC was calculated by subtraction of the ceruloplasmin bound copper from the total serum copper and the RelANCC was the percentage of total copper present as the ANCC.

RESULTS

The accuracy of the holo-ceruloplasmin measurement was established using two certified reference materials, giving a mean recovery of 94.2 %. Regression analysis between the sum of the copper containing species and total copper concentration in the patient samples was acceptable (slope=0.964, intercept=0, r=0.987) and a difference plot, gave a mean difference for copper of 0.38 μmol/L. Intra-day precision for holo-ceruloplasmin at serum copper concentrations of 0.48 and 3.20 μmol/L were 5.2 and 5.6 % CV and the intermediate precision at concentrations of 0.80 and 5.99 μmol/L were 6.4 and 6.4 % CV, respectively. The limit of detection (LOD) and lower limit of quantification (LLOQ) for holo-ceruloplasmin were 0.08 and 0.27 μmol/L as copper, respectively.

CONCLUSIONS

ANCC and Relative ANCC are important new diagnostic and monitoring biomarker indices for Wilson disease (WD).

Establishment of a Labile Bound Copper Reference Interval in a Healthy Population via an Inductively Coupled Plasma Mass Spectrometry Dual Filtration-Based Assay

CONTEXT.—

Clinical testing for Wilson disease (WD) is potentially challenging. Measuring the fraction of labile bound copper (LBC) to total copper may be a promising alternative diagnostic tool with better sensitivity and specificity than some current biomarker approaches. A dual filtration-based inductively coupled mass spectrometry (ICP-MS) assay to measure LBC in serum was developed.

OBJECTIVE.—

To establish a reference interval for LBC and LBC to total copper (LBC fraction) in a healthy adult population, and to examine associations between total copper, LBC, and LBC fraction with age, sex, menopausal status, hormone replacement therapy, and supplement use.

DESIGN.—

Serum samples were collected from healthy male (n = 110) and female (n = 104) patients between the ages of 19 and 80 years. Total copper and LBC were analyzed using ICP-MS. Results were used to calculate the LBC fraction. Reference intervals were calculated for the 2.5th and 97.5th percentiles for both LBC and LBC fraction.

RESULTS.—

The reference intervals for LBC were determined to be 13 to 105 ng/mL and 12 to 107 ng/mL for female and male patients, respectively. The reference intervals for the LBC fraction were 1.0% to 8.1% and 1.2% to 10.5% for female and male patients, respectively. No significant associations were found regarding age, menopausal status, hormone replacement therapy, or vitamin and supplement use.

CONCLUSIONS.—

Sex-specific reference intervals have now been established for LBC and LBC fraction. These data in conjunction with further testing of WD populations can be used to assess the sensitivity and specificity of LBC fraction in screening, monitoring, and diagnosis.

Benefits of using exchangeable copper and the ratio of exchangeable copper in a real-world cohort of patients with Wilson disease

Wilson disease (WD) is a complex disease in which diagnosis and long-term metabolic copper control remains challenging. The absence of accurate biomarkers requires the combination of different parameters to ensure copper homeostasis. Exchangeable copper and its ratio (REC) have been suggested to be useful biomarkers in this setting. We aimed at introducing these measurements and evaluate their performance and accuracy in our real-world cohort of WD patients. Exchangeable copper and REC were measured in 48 WD patients and 56 control individuals by inductively coupled plasma-mass-spectrometry. Demographic and clinical characteristics were collected. REC was shown to be significantly higher among WD patients compared to controls and useful for WD identification by using the previously established cutoffs: 71.4% of WD patients with a recent diagnosis had REC ≥18.5% and 95.1% of long-term treated WD had REC ≥14%; only four patients of the cohort presented discordant levels. Moreover, REC values were below 15% in all the control individuals. Exchangeable copper was significantly higher in WD patients compared to controls and tended to be reduced among WD patients who were compliant to medication. This real-life study confirmed that exchangeable copper and REC are useful serum biomarkers that can be used as complementary tests to ensure WD diagnosis (REC) and copper homeostasis whithin time (exchangeable copper). The desirable target levels for this last objective still needs to be validated in prospective cohorts.

Decoding Neurodegeneration: A Comprehensive Review of Molecular Mechanisms, Genetic Influences, and Therapeutic Innovations

Neurodegenerative disorders often acquire due to genetic predispositions and genomic alterations after exposure to multiple risk factors. The most commonly found pathologies are variations of dementia, such as frontotemporal dementia and Lewy body dementia, as well as rare subtypes of cerebral and cerebellar atrophy-based syndromes. In an emerging era of biomedical advances, molecular-cellular studies offer an essential avenue for a thorough recognition of the underlying mechanisms and their possible implications in the patient's symptomatology. This comprehensive review is focused on deciphering molecular mechanisms and the implications regarding those pathologies' clinical advancement and provides an analytical overview of genetic mutations in the case of neurodegenerative disorders. With the help of well-developed modern genetic investigations, these clinically complex disturbances are highly understood nowadays, being an important step in establishing molecularly targeted therapies and implementing those approaches in the physician's practice.

A fluorometric assay to determine labile copper(II) ions in serum

Labile copper(II) ions (Cu2+) in serum are considered to be readily available for cellular uptake and to constitute the biologically active Cu2+ species in the blood. It might also be suitable to reflect copper dyshomeostasis during diseases such as Wilson's disease (WD) or neurological disorders. So far, no direct quantification method has been described to determine this small Cu2+ subset. This study introduces a fluorometric high throughput assay using the novel Cu2+ binding fluoresceine-peptide sensor FP4 (Kd of the Cu2+-FP4-complex 0.38 pM) to determine labile Cu2+ in human and rat serum. Using 96 human serum samples, labile Cu2+was measured to be 0.14 ± 0.05 pM, showing no correlation with age or other serum trace elements. No sex-specific differences in labile Cu2+ concentrations were noted, in contrast to the total copper levels in serum. Analysis of the effect of drug therapy on labile Cu2+ in the sera of 19 patients with WD showed a significant decrease in labile Cu2+ following copper chelation therapy, suggesting that labile Cu2+ may be a specific marker of disease status and that the assay could be suitable for monitoring treatment progress.

Medical care of patients with Wilson disease in Germany: a multidisciplinary survey among university centers

BACKGROUND

Wilson disease (WD) is a rare, hereditary disorder of copper metabolism. Due to its variable symptoms and manifestations, diagnosis remains challenging. Affected patients must obtain lifelong medical treatment, as the disease is fatal if untreated. Patients require continuous monitoring, but little is known about the care of these patients in Germany. Therefore, we analyzed the medical care of WD patients at German university centers. We sent a questionnaire containing 20 questions to a total of 108 departments of pediatrics, neurology and gastroenterology in 36 university hospitals. Our questions referred to the characteristics of WD patients at the different sites and internal procedures regarding diagnosis, therapy and follow-up. A descriptive statistical analysis was performed.

RESULTS

Sixty-three departments (58%) returned our questionnaire. In total, approximately one-third of the estimated WD patients in Germany are seen annually in the outpatient clinics of these departments (approx. 950 patients). There are only a few departments which treat patients in a multidisciplinary setting (12%). Our survey revealed that for diagnosis, 51% of all departments used an algorithm based on the Leipzig score as recommended by international guidelines. Most departments apply essential parameters recommended by WD guidelines. Routine monitoring is performed at least biannually by 84% of the departments, and standard investigations for monitoring are regularly applied. A routine family screening is performed by 84% of all departments. A reduction in medical therapy during pregnancy is recommended by 46% of the departments. Only 14% suggested that WD patients should not breastfeed. Liver transplantation (LT) due to WD is a rare but repeatedly occurring event. Most departments of gastroenterology (72%) reported at least one patient with LT within the last decade.

CONCLUSIONS

Medical care of WD patients at German university centers follows the recommendations set forth by international guidelines, but only a few centers treat significant numbers of patients. The surveillance of patients does not follow specified standards, but most departments adhere to the accepted guidelines. The formation of central units and networks in a multidisciplinary setting should be evaluated to improve the care of WD patients.

Monitoring of Copper in Wilson Disease

(1) Introduction: Wilson's disease (WND) is an autosomal recessive disorder of copper (Cu) metabolism. Many tools are available to diagnose and monitor the clinical course of WND. Laboratory tests to determine disorders of Cu metabolism are of significant diagnostic importance. (2) Methods: A systematic review of the literature in the PubMed, Science Direct, and Wiley Online Library databases was conducted. (Results): For many years, Cu metabolism in WND was assessed with serum ceruloplasmin (CP) concentration, radioactive Cu test, total serum Cu concentration, urinary copper excretion, and Cu content in the liver. The results of these studies are not always unambiguous and easy to interpret. New methods have been developed to calculate non-CP Cu (NCC) directly. New parameters, such as relative Cu exchange (REC), reflecting the ratio of CuEXC to total serum Cu, as well as relative Cu exchange (REC), reflecting the ratio of CuEXC to total serum Cu, have been shown to be an accurate tool for the diagnosis of WND. Recently, a direct and fast LC-ICP-MS method for the study of CuEXC was presented. A new method to assess Cu metabolism during treatment with ALXN1840 (bis-choline tetrathiomolybdate [TTM]) has been developed. The assay enables the bioanalysis of CP and different types of Cu, including CP-Cu, direct NCC (dNCC), and labile bound copper (LBC) in human plasma. Conclusions: A few diagnostic and monitoring tools are available for patients with WND. While many patients are diagnosed and adequately assessed with currently available methods, diagnosis and monitoring is a real challenge in a group of patients who are stuck with borderline results, ambiguous genetic findings, and unclear clinical phenotypes. Technological progress and the characterization of new diagnostic parameters, including those related to Cu metabolism, may provide confidence in the more accurate diagnosis of WND in the future.

[Wilson's disease: overview]

Wilson's disease (WD) is an uncommon hereditary disorder caused by a deficiency in the ATP7B transporter. The protein codified by this gene facilitates the incorporation of the copper into ceruloplasmin. Therefore, WD accumulates copper primary in the liver and secondary in other organs, such as the central nervous system. It represents a wide spectrum of disease, ranging from being asymptomatic in some patients to promote an acute liver failure in others. The diagnosis requires a combination of clinical signs and symptoms, as well as some diagnostic tests such as the measurement of serum ceruloplasmin, the urinary excretion of copper, the liver biopsy or the genetic testing. The treatment must be maintained lifelong and includes some drugs such as chelating agents (penicillamine and trientine) and inhibitors of the copper absorption (zinc salts). Lastly, the liver transplant should be an option for patients with end-stage liver disease.

Thermodynamics-based rules of thumb to evaluate the interaction of chelators and kinetically-labile metal ions in blood serum and plasma

Metal ions play a very important role in nature and their homeostasis is crucial. A lot of metal-related chemical research activities are ongoing that concern metal-based drugs or tools, such as chelation therapy, metal- and metabolite sensors, metallo-drugs and prodrugs, PET and MRI imaging agents, etc. In most of these cases, the applied chelator/ligand (L) or metal-ligand complex (M-L) has at least to pass the blood plasma to reach the target. Hence it is exposed to several metal-binding proteins (mainly serum albumin and transferrin) and to all essential metal ions (zinc, copper, iron, etc.). This holds also for studies in cultured cells when fetal calf serum is used in the medium. There is a risk that the applied compound (L or M-L) in the serum is transformed into a different entity, due to trans-metallation and/or ligand exchange reactions. This depends on the thermodynamics and kinetics. For kinetically-labile complexes, the complex stability with all the ligands and all metal ions present in serum is decisive in evaluating the thermodynamic driving force towards a certain fate of the chelator or metal-ligand complex. To consider that, an integrative view is needed on the stability constants, by taking into account all the metal ions present and all the main proteins to which they are bound, as well as the non-occupied metal binding site in proteins. Only then, a realistic estimation of the complex stability, and hence its potential fate, can be done. This perspective aims to provide a simple approach to estimate the thermodynamic stability of labile metal-ligand complexes in a blood plasma/serum environment. It gives a guideline to obtain an estimation of the plasma and serum complex stability and metal selectivity starting from the chemical stability constants of metal-ligand complexes. Although of high importance, it does not focus on the more complex kinetic aspects of metal-transfer reactions. The perspective should help for a better design of such compounds, to perform test tube assays which are relevant to the conditions in the plasma/serum and to be aware of the importance of ternary complexes, kinetics and competition experiments.

Pitfalls in the interpretation of blood tests used to assess and monitor micronutrient nutrition status

Assessment of micronutrient (MN) status is of particular importance in patients who require medical nutrition therapy, especially those requiring parenteral nutrition. Blood testing is generally the only tool available in clinical settings to assess MN status. However, using plasma or serum concentration faces pitfalls mainly because of the impact of inflammation that diverts the MNs from the circulating compartment. This review aims to review the blood tests that are useful and provide information about how to integrate functional markers of status to reach a clinically relevant diagnosis. Most impacted, with a significant and proportional decrease in plasma concentrations, are iron, selenium, zinc, thiamin, folic acid, cobalamin, and vitamins A, C, and D; copper is the only MN for which the plasma concentration increases. Therefore, a surrogate marker of inflammation, C-reactive protein, must always be determined simultaneously. Validated intracellular and functional tests are proposed to improve status assessment. A protocol is suggested for tests required both on commencing and during nutrition support. A timely turnaround of analysis is essential for results to be clinically useful. In some cases, the appropriate provision of MNs should be commenced before results have been obtained to confirm the clinical assessment. Laboratory tests of MN status are an area prone to misuse and misinterpretation. The appropriate use and interpretation of such tests are essential to ensure the correct management of nutrition problems.

Trientine tetrahydrochloride versus penicillamine for maintenance therapy in Wilson disease (CHELATE): a randomised, open-label, non-inferiority, phase 3 trial

BACKGROUND

Wilson disease is an inherited disorder of copper transport. Whereas penicillamine is used therapeutically to re-establish copper balance, trientine is indicated for patients with penicillamine intolerance. We aimed to compare penicillamine with trientine tetrahydrochloride (TETA4) for maintenance therapy in patients with Wilson disease.

METHODS

We conducted a randomised, open-label, non-inferiority, phase 3 trial at 15 health-care centres across nine countries (patients were recruited from 13 of these health-care centres across Brazil, Europe, and the USA). We enrolled patients aged 18-75 years with stable Wilson disease who were treated for at least 1 year with penicillamine. Patients entered a 12-week period to determine stability through clinical assessment by site investigators and predefined thresholds for serum non-caeruloplasmin-bound copper (NCC; by an exchangeable copper assay; 25-150 μg/L), 24 h urinary copper excretion (100-900 μg/24 h), and alanine aminotransferase (ALT; <2 × upper limit of normal). Stable patients were randomly assigned (1:1) to continue receiving the maintenance twice daily dose of oral penicillamine or switched mg-for-mg to oral TETA4 centrally with a web-based system using minimisation. The primary endpoint, assessed 24 weeks after randomisation, was NCC by speciation assay. The non-inferiority margin of mean difference in NCC by speciation assay was -50 μg/L, as estimated by a general linear model for repeated visits, adjusted for baseline values. Further data on safety and efficacy were collected during a 24-week extension period. Data were analysed using an intention-to-treat approach. Safety was assessed in all patients who received at least one dose of study treatment. This study is registered with ClinicalTrials.gov, NCT03539952 (active, not recruiting).

FINDINGS

Between June 4, 2018, and March 10, 2020, 77 patients were screened. 53 patients were randomly assigned (27 to the penicillamine group and 26 to the TETA4 group). After 24 weeks, the mean difference in serum NCC by speciation assay between the penicillamine group and TETA4 group was -9·1 μg/L (95% CI -24·2 to 6·1), with the lower limit of the 95% CI within the defined non-inferiority margin. At 24 weeks, urinary copper excretion was lower with TETA4 than with penicillamine (mean difference 237·5 μg/24 h (99% CI 115·6 to 359·4). At 48 weeks, TETA4 remained non-inferior to penicillamine in terms of NCC by speciation assay (mean difference NCC -15·5 μg/L [95% CI -34·5 to 3·6]). Urinary copper excretion at 48 weeks remained in the expected range for well treated patients in both study groups, and the mean difference (124·8 μg/24 h [99% CI -37·6 to 287·1]) was not significantly different. At 24 weeks and 48 weeks, masked clinical adjudication of stability assessed by three independent clinicians confirmed clinical stability (100%) of all participants, in agreement with the stability seen with the NCC by speciation assay. There were no notable changes in either the Clinical Global Impression of Change or Unified Wilson Disease Rating Scale (neurological assessment) from baseline (pre-randomisation) at weeks 24 and 48. The mean change in serum total copper from baseline to 24 weeks was 17·6 μg/L (99% CI -9·5 to 44·7) with penicillamine and -6·3 μg/L (-34·7 to 22·1) with TETA4, and the mean change in serum total caeruloplasmin from baseline to 24 weeks was 1·8 mg/L (-19·2 to 22·8) with penicillamine and -2·2 mg/L (-6·1 to 1·7) with TETA4. All liver enzymes were similar at 24 weeks and 48 weeks, with the exception of elevated ALT concentration at 48 weeks for patients in the TETA4 group. Penicillamine was associated with three post-randomisation serious adverse events (leukopenia, cholangiocarcinoma, and hepatocellular cancer); none were reported for TETA4. The most common treatment-emergent adverse events were headache for penicillamine (five [19%] of 27 patients vs two [8%] of 26) and abdominal pain for TETA4 (one [4%] vs four [15%]); all treatment-emergent adverse events resolved and were mild to moderate. One patient developed a rash with TETA4 that resolved on discontinuation of therapy.

INTERPRETATION

The efficacy of TETA4 as oral maintenance therapy was non-inferior to penicillamine and well tolerated in adults with Wilson disease.

FUNDING

Orphalan.

Pseudocholinesterase as a Biomarker for Untreated Wilson's Disease

The aim of this study was to demonstrate that pseudocholinesterase (CHE) serum level is a useful diagnostic biomarker for untreated Wilson's disease (WD). Between 2013 and 2019, about 75 patients were referred to the outpatient department of the University of Düsseldorf with suspected Wilson's disease. In 31 patients with suspected Wilson's disease (WD-SUS-group), WD was excluded by means of investigations other than analysis of blood and urine. A total of 27 parameters of blood and urine in these 31 patients were compared to those of 20 de novo patients with manifest WD (WD-DEF-group), which parameter showed the highest significance level of difference between the WD-DEF-group and the WD-SUS-group. Thereafter, receiver operating characteristics (ROC-curves) were analyzed to evaluate which parameter showed the largest area under the curve (AUC) to detect WD. Finally, a logistic regression analysis was performed to analyze which combination of parameters allowed the best classification of the 51 patients either into the WD-DEF-group or into the WD-SUS-group. CHE showed the highest significance level for a difference between the WD-DEF- and WD-SUS-group, had the highest AUC, and, in combination with ceruloplasmin, allowed 100% correct classification. Without CHE, no other combination of parameters reached this level of correct classification. After the initiation of treatment, which regularly results in an improvement in CHE, the high diagnostic accuracy of this biomarker was lost. Cholinesterase turns out to be an excellent biomarker for differentiation between untreated de novo patients with manifest WD and heterozygotic gene carriers.

Long-Term Urinary Copper Excretion and Exchangeable Copper in Children With Wilson Disease Under Chelation Therapy

OBJECTIVES

Determining 24-hour urinary copper excretion (UCE) levels is useful for diagnosing Wilson's disease (WD) and for treatment monitoring. Exchangeable copper (ExC) is a novel potential marker, but its long-term changes have never been described in patients under chelation therapy. Our aim was to describe the long-term changes in ExC levels compared to UCE levels in symptomatic WD pediatric patients under chelation therapy.

METHODS

A retrospective, descriptive, and analytical study including all patients under 18 years of age, diagnosed between 2006 and 2020, and treated with chelation therapy was conducted at the National Reference Center for WD in Lyon. Ceruloplasmin levels, serum copper, 24 h-UCE, ExC, and liver enzymes at diagnosis and during follow-up were analyzed.

RESULTS

Our study included 36 patients, predominantly with hepatic form of WD (n = 31). The median [interquartile range (IQR)] age at diagnosis was 10.5 (8.4-13.1) years, and the median (IQR) follow-up duration was 6.3 (3.3-8.8) years. At diagnosis, the median (IQR) ExC value was 1.01 (0.60-1.52) µmol/L. There was a significant decrease during the first year of chelation treatment ( P = 0.0008), then a stabilization. The median (IQR) ExC values was 0.38 (0.22-0.63) µmol/L at 12-18 months and 0.43 (0.31-0.54) µmol/L at 5 years of chelation treatment ( P = 0.4057). Similarly, there was a significant decrease in 24-hour UCE ( P &lt; 0.001) during the first year of chelation treatment, then a stabilization.

CONCLUSIONS

Our study showed a significant decrease in ExC and 24-hour UCE levels during the first year of follow-up; The dynamics of both biomarkers were similar along the follow-up, demonstrating their usefulness in clinical practice for monitoring WD.

The Role of Zinc in the Treatment of Wilson’s Disease

Wilson’s disease (WD) is a hereditary disorder of copper metabolism, producing abnormally high levels of non-ceruloplasmin-bound copper, the determinant of the pathogenic process causing brain and hepatic damage and dysfunction. Although the disease is invariably fatal without medication, it is treatable and many of its adverse effects are reversible. Diagnosis is difficult due to the large range and severity of symptoms. A high index of suspicion is required as patients may have only a few of the many possible biomarkers. The genetic prevalence of ATP7B variants indicates higher rates in the population than are currently diagnosed. Treatments have evolved from chelators that reduce stored copper to zinc, which reduces the toxic levels of circulating non-ceruloplasmin-bound copper. Zinc induces intestinal metallothionein, which blocks copper absorption and increases excretion in the stools, resulting in an improvement in symptoms. Two meta-analyses and several large retrospective studies indicate that zinc is equally effective as chelators for the treatment of WD, with the advantages of a very low level of toxicity and only the minor side effect of gastric disturbance. Zinc is recommended as a first-line treatment for neurological presentations and is gaining acceptance for hepatic presentations. It is universally recommended for lifelong maintenance therapy and for presymptomatic WD.

Biochemical diagnosis of Wilson's disease: an update

Wilson's disease (WD) is an inherited disorder of copper metabolism caused by mutations in the ATP7B gene. This condition is characterized by the accumulation of copper in the liver and other organs and tissues causing hepatic and neuropsychiatric manifestations. This paper reviews the diagnostic performance and limitations of the biochemical tests commonly used to detect this underdiagnosed disease. It also provides some recommendations and suggests a set of standardized laboratory comments. At present, a rapid, simple, reliable biochemical test that confirms diagnosis of WD is not available. However, diagnosis can be established based on serum ceruloplasmin and urinary copper excretion. Total serum copper should be employed with caution, since it has a low negative predictive value. The use of estimated non-ceruloplasmin-bound copper is not recommended. Nevertheless, measured relative exchangeable copper has very high sensitivity and specificity and emerges as a potential gold standard for the biochemical diagnosis of WD. The development of novel assays for WD detection makes this disorder a potential candidate to be included in newborn screening programs.

Review about Powerful Combinations of Advanced and Hyphenated Sample Introduction Techniques with Inductively Coupled Plasma-Mass Spectrometry (ICP-MS) for Elucidating Trace Element Species in Pathologic Conditions on a Molecular Level

Element analysis in clinical or biological samples is important due to the essential role in clinical diagnostics, drug development, and drug-effect monitoring. Particularly, the specific forms of element binding, actual redox state, or their spatial distribution in tissue or in single cells are of interest in medical research. This review summarized exciting combinations of sophisticated sample delivery systems hyphenated to inductively coupled plasma-mass spectrometry (ICP-MS), enabling a broadening of information beyond the well-established outstanding detection capability. Deeper insights into pathological disease processes or intracellular distribution of active substances were provided, enabling a better understanding of biological processes and their dynamics. Examples were presented from spatial elemental mapping in tissue, cells, or spheroids, also considering elemental tagging. The use of natural or artificial tags for drug monitoring was shown. In the context of oxidative stress and ferroptosis iron, redox speciation gained importance. Quantification methods for Fe2+, Fe3+, and ferritin-bound iron were introduced. In Wilson’s disease, free and exchangeable copper play decisive roles; the respective paragraph provided information about hyphenated Cu speciation techniques, which provide their fast and reliable quantification. Finally, single cell ICP-MS provides highly valuable information on cell-to-cell variance, insights into uptake of metal-containing drugs, and their accumulation and release on the single-cell level.

Practical insights into chronic management of hepatic Wilson’s disease

Wilson’s disease (WD) is a rare inherited disorder of human copper metabolism, with an estimated prevalence of 1:30000-1:50000 and a broad spectrum of hepatic and neuropsychiatric manifestations. In healthy individuals, the bile is the main route of elimination of copper. In WD patients, copper accumulates in the liver, it is released into the bloodstream, and is excreted in urine. Copper can also be accumulated in the brain, kidneys, heart, and osseous matter and causes damage due to direct toxicity or oxidative stress. Hepatic WD is commonly but not exclusively diagnosed in childhood or young adulthood. Adherent, non-cirrhotic WD patients seem to have a normal life expectancy. Nevertheless, chronic management of patients with Wilson’s disease is challenging, as available biochemical tests have many limitations and do not allow a clear identification of non-compliance, overtreatment, or treatment goals. To provide optimal care, clinicians should have a complete understanding of these limitations and counterbalance them with a thorough clinical assessment. The aim of this review is to provide clinicians with practical tools and suggestions which may answer doubts that can arise during chronic management of patients with hepatic WD. In particular, it summarises current knowledge on Wilson’s disease clinical and biochemical monitoring and treatment. It also analyses available evidence on pregnancy and the role of low-copper diet in WD. Future research should focus on trying to provide new copper metabolism tests which could help to guide treatment adjustments.

Study of impacts of brickkiln emanations on soil quality of agriculture lands in selected areas of District Bhimber, Azad Jammu and Kashmir, Pakistan

The pollution is hot issue of current era in world and the current study was carried to explore impacts of brickkilns' emanations on physiochemical properties of agricultural lands from District Bhimber of Azad Jammu and Kashmir (AJK) Pakistan. In this research, various edaphic characteristics: pH, soil organic matter, organic carbon, water holding capacity, cation exchange capacity and heavy metal contamination in soils nearby of brickkilns were determined. The pH of soil ranged from 5.55 to 7.50, soil organic matter was 0.35-0.90% and organic carbon content was 0.65-1.40%. The water holding capacity ranged from 2.10 to 3.20 mgL-1 and carbon exchange capacity was 1250 to 4202 meq/100g. The contamination profile of heavy metal depicted that Pb showed highest conc. 0.065 mg/g followed by Co (0.053 mg/g) and Ni with 0.52 mg/g in the soil. Pb and Cr had high conc. in soil samples around brickkilns due to burning of coal and rubber tyres as fuel. The conc. of sulphate and nitrate ranged from 0.90±0.50 mol L-1 to 4.25±0.65 mol L-1 and 2.30±0.50 mol L-1 to 6.55±0.25 mol L-1, respectively. The fertility of agriculture lands was depicted that edaphic properties were directly related while nutritive features were inversely commensurate to distance from brickkilns. The research proved that emanations of brickkilns causes severe impact on quality of agriculture land, plant growth and its yield. Hence, reclamation measures should be taken to mitigate and/or eradicate nuisance of brickkilns emanations by using environmental friendly strategies.

Melatonin: Regulation of Prion Protein Phase Separation in Cancer Multidrug Resistance

The unique ability to adapt and thrive in inhospitable, stressful tumor microenvironments (TME) also renders cancer cells resistant to traditional chemotherapeutic treatments and/or novel pharmaceuticals. Cancer cells exhibit extensive metabolic alterations involving hypoxia, accelerated glycolysis, oxidative stress, and increased extracellular ATP that may activate ancient, conserved prion adaptive response strategies that exacerbate multidrug resistance (MDR) by exploiting cellular stress to increase cancer metastatic potential and stemness, balance proliferation and differentiation, and amplify resistance to apoptosis. The regulation of prions in MDR is further complicated by important, putative physiological functions of ligand-binding and signal transduction. Melatonin is capable of both enhancing physiological functions and inhibiting oncogenic properties of prion proteins. Through regulation of phase separation of the prion N-terminal domain which targets and interacts with lipid rafts, melatonin may prevent conformational changes that can result in aggregation and/or conversion to pathological, infectious isoforms. As a cancer therapy adjuvant, melatonin could modulate TME oxidative stress levels and hypoxia, reverse pH gradient changes, reduce lipid peroxidation, and protect lipid raft compositions to suppress prion-mediated, non-Mendelian, heritable, but often reversible epigenetic adaptations that facilitate cancer heterogeneity, stemness, metastasis, and drug resistance. This review examines some of the mechanisms that may balance physiological and pathological effects of prions and prion-like proteins achieved through the synergistic use of melatonin to ameliorate MDR, which remains a challenge in cancer treatment.

Non-invasive diagnosis and follow-up of rare genetic liver diseases

Rare genetic liver diseases can result in multi-systemic damage, which may compromise the patient's prognosis. Wilson's disease and alpha-1 antitrypsin deficiency must be investigated in any patient with unexplained liver disease. Cystic fibrosis screening of new-borns is now implemented in most high-prevalence countries. The diagnosis of these diseases can be strongly suggested with specific non-invasive tests. Molecular analysis gene for these diseases is long and tedious but is recommended to confirm the diagnosis and help for the family screening. Liver biopsy is not systematic and is discussed when it helps diagnosis. Currently, for these three diseases, non-invasive fibrosis markers could identify patients with risk of cirrhosis and complications. Rare genetic liver diseases can result in multi-systemic damage, which may compromise the patient's prognosis. Wilson's disease, must be investigated in any patient with unexplained liver disease and/or unexplained neurological or neuropsychiatric disorders. The diagnosis is based on a combination of clinical, biological features, including copper balance. The exchangeable copper/total copper ratio is a new sensible and specific biological marker, useful for the diagnosis of the disease. Timely diagnosis and treatment will prevent serious complications from the disease. Neurological evaluation and familial screening are essential in patients with Wilson's disease.

Wilson's Disease: An Update on the Diagnostic Workup and Management

Wilson's disease (WD) is a rare autosomal recessive disorder of hepatocellular copper deposition. The diagnostic approach to patients with WD may be challenging and is based on a complex set of clinical findings that derive from patient history, physical examination, as well as laboratory and imaging testing. No single examination can unequivocally confirm or exclude the disease. Timely identification of signs and symptoms using novel biomarkers and modern diagnostic tools may help to reduce treatment delays and improve patient prognosis. The proper way of approaching WD management includes, firstly, early diagnosis and prompt treatment introduction; secondly, careful and lifelong monitoring of patient compliance and strict adherence to the treatment; and, last but not least, screening for adverse effects and evaluation of treatment efficacy. Liver transplantation is performed in about 5% of WD patients who present with acute liver failure at first disease presentation or with signs of decompensation in the course of liver cirrhosis. Increasing awareness of this rare inherited disease among health professionals, emphasizing their training to consider early signs and symptoms of the illness, and strict monitoring are vital strategies for the patient safety and efficacy of WD therapy.

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.

A fit-for-purpose copper speciation method for the determination of exchangeable copper relevant to Wilson's disease

Exchangeable copper (CuEXC), mainly comprised copper (Cu) bound to albumin, has been proposed as a specific marker of Cu overload in Wilson's disease (WD). To the author's knowledge, there are no methods capable of determining reliably CuEXC to meet the requirements and challenges faced by a clinical trial. The present work describes a novel speciation strategy for the determination of the main Cu-species in human serum by anion-exchange high-performance liquid chromatography coupled to inductively coupled plasma mass spectrometry (HPLC-ICP-MS). A label-free protein quantification approach was conducted where the concentration of Cu associated to the protein fraction was based on its relative peak area distribution and the total Cu concentration in the sample. Such a methodology was characterized in terms of selectivity, sensitivity, precision, and robustness. Due to the lack of speciated Cu-reference materials, protein recovery was assessed by comparison with that of species-specific (SS) isotope dilution (ID). For this, a double SS HPLC-ICP-IDMS method for Cu-albumin was developed and presented here for the first time. Three human sera (two frozen LGC8211 and ERM®-DA250a, and the lyophilised Seronorm™ Human) were analyzed using both the relative and ID quantification methods. The validated relative approach, with relative expanded uncertainties (k = 2) between 5.7 and 10.1% for Cu-albumin concentrations ranging from 112 to 455 μg kg^-1 Cu, was found to be able to discriminate between healthy and WD populations in terms of Cu-albumin content. Also, using such methodology, underestimation of CuEXC by the classical EDTA/ultrafiltration method was demonstrated. The methodology developed in this work will be invaluable for quality control assessment and WD drug monitoring. This work describes a Cu-protein quantification approach for the determination of exchangeable Cu relevant to Wilson's Disease.

Total and Exchangeable Copper Assay Using Inductively Coupled Plasma Mass Spectrometry and Establishment of a Pediatric Reference Interval

CONTEXT.—

Recently, an exchangeable copper (CuEXC) assay has been suggested as a robust and feasible diagnostic tool for Wilson disease (WD). Although WD is a disorder that requires lifelong treatment and monitoring, few data are currently available regarding the status of copper levels in children.

OBJECTIVE.—

To evaluate the performance of copper assays and establish a reference interval for total copper and CuEXC in the pediatric population.

DESIGN.—

Serum samples from children aged 1-5 (n = 122), 6-12 (n = 125), and 13-18 years (n = 120) were analyzed. Total copper and CuEXC concentrations were directly measured using inductively coupled plasma mass spectrometry, and relative CuEXC levels were calculated. Total copper reference intervals, CuEXC levels, and relative CuEXC levels were determined based on the 2.5th and 97.5th percentiles of the data with 90% confidence intervals.

RESULTS.—

There were significant differences in the median concentrations of total copper and relative CuEXC among the age groups. Reference intervals determined for total copper were 82 to 167, 75 to 139, and 64 to 133 μg/dL for children aged 1 to 5, 6 to 12, and 13 to 18 years, respectively. The reference intervals for CuEXC were 4.29 to 9.79, 4.02 to 9.09, and 3.55 to 8.25 μg/dL for children aged 1 to 5, 6 to 12, and 13 to 18 years, respectively. Among 11 patients with suspected WD, relative CuEXC values were elevated in all 3 diagnosed with WD.

CONCLUSIONS.—

The pediatric reference intervals derived in this study are expected to be useful for the diagnosis, differential diagnosis, treatment, and monitoring of pediatric patients with WD.

Considerations for optimizing Wilson's disease patients' long-term follow-up

Wilson's disease is a sistemic genetic disease caused by the excessive accumulation of copper. The first and main involvement is in the liver, which can range from mild and transient elevation of transaminases to the onset of an overt cirrhosis or acute liver failure. It is known that up to 20-30% of these patients may evolve to liver cirrhosis during follow-up. In clinical practice, liver fibrosis is assessed mainly by using indirect and non-invasive tools (laboratory tests, liver elastography, ultrasound), similar to other prevalent chronic liver diseases. However, despite the fact that liver elastography is a valuable tool in general hepatology, the evidence of its usefulness and accuracy in Wilsońs disease is scarce. This review summarizes the available scientific data and their limitations in Wilson's disease.

Management Perspective of Wilson's Disease: Early Diagnosis and Individualized Therapy

Wilson's disease (WD) is an inherited disease caused by mutations in ATP7B and is characterized by the pathological accumulation of copper in the liver and brain. Common clinical manifestations of WD include a wide range of liver disease and neurological symptoms. In some patients, psychiatric symptoms may be the only manifestation at the time of diagnosis. The clinical features of WD are highly variable and can mimic any disease of internal medicine. Therefore, for unexplained medical diseases, the possibility of WD should not be ignored. Early diagnosis and treatment can improve the prognosis of WD patients and reduce disability and early death. Gene sequencing is becoming a valuable method to diagnose WD, and if possible, all WD patients and their siblings should be genetically sequenced. Copper chelators including D-penicillamine, trientine, and dimercaptosuccinic acid can significantly improve the liver injury and symptoms of WD patients but may have a limited effect on neurological symptoms. Zinc salts may be more appropriate for the treatment of asymptomatic patients or for the maintenance treatment of symptomatic patients. High-quality clinical trials for the drug treatment of WD are still lacking, therefore, individualized treatment options for patients are recommended. Individualized treatment can be determined based on the clinical features of the WD patients, efficacy and adverse effects of the drugs, and the experience of the physician. Liver transplantation is the only effective method to save patients with acute liver failure or with severe liver disease who fail drug treatment.

Assay in serum of exchangeable copper and total copper using inductively coupled plasma mass spectrometry (ICP-MS): development, optimisation and evaluation of a routine procedure

The assay in serum of non-caeruloplasmin copper, as exchangeable copper after complexation with EDTA (ExCu) and total copper has been evaluated and compared in patients with varying c-reactive protein(CRP). Measurement of ExCu and total copper, range 0.2-47.2 µmol/L, was developed using ICP-MS. The chelating agents EDTA and TEPA were compared over 0.0-10 g/L after incubation with serum for 60 mins followed by ultrafiltration with Amicon 10 kDa filter. The assay for ExCu was optimised with EDTA 3 g/L (8.1 mmol/L) maintained at pH 7.0-8.0 before ultrafiltration. TEPA was not as selective in chelation of copper. Patients n = 82 were studied in relation to changes in inflammatory marker CRP and a group of patients n = 37 with normal CRP. The ExCu assay gave excellent recoveries (94-102 % but poor recovery for free uncomplexed copper), good repeatability, limit of quantitation 0.19 µmol/l with a provisional reference range 0.48 to 1.63 µmol/L (n = 37 patients). The range for relative exchangeable copper (exchangeable copper divided by total serum copper) was 2.49 to 9.96 %. ExCu was elevated in conditions with increased CRP greater than 100 mg/L suggesting an effect of inflammation on the free copper fraction. A reliable and reproducible assay for ExCu and total copper has been developed. The upregulated inflammatory state increases the ExCu suggesting excess free copper.

A terbium(iii) luminescent ATCUN-based peptide sensor for selective and reversible detection of copper(ii) in biological media

Detection of copper(ii) in biological media via time-delayed luminescence by a selective and reversible terbium(iii)-luminescent peptide sensor with pM affinity.

Serum copper profile in patients with type 1 diabetes in comparison to other metals

BACKGROUND

Type 1 diabetes (T1D) is a chronic condition in which the pancreas loses the ability to produce insulin due to an autoimmune destruction of the insulin producing beta cells in the pancreatic islets of Langerhans. Pathophysiological complications related to diabetes include micro and macrovascular disease, nephropathy, and neuropathy that can also be affected by environmental factors such as lifestyle and diet.

OBJECTIVES

The current study aimed to evaluate the serum levels of total copper, the copper-carrying protein, ceruloplasmin and nonceruloplasmin bound copper (nonceruloplasmin-Cu) and other essential and environmental metals and metalloids in subjects with T1D compared with healthy controls.

METHODS

A cohort of 63 subjects with T1D attending Diabetes Clinics at the University of Miami and 65 healthy control subjects was studied. Metals and metalloids were measured by inductively coupled plasma mass spectrometry.

RESULTS

A main finding of this study was that total copper and ceruloplasmin levels were higher in persons with T1D compared to healthy controls. In comparison to other metals and clinical variables, elevated copper was the strongest factor associated with T1D resulting in a15-fold increased odds of having the disease per standard deviation increase.

CONCLUSION

Our results suggest a metal and metalloid perturbation in T1D with a significant involvement of Copper dysfunction in the disease pathology, possibly linked to inflammatory processes.

Innovative Biomarkers for Alzheimer's Disease: Focus on the Hidden Disease Biomarkers

The criteria for the clinical diagnosis of AD include the analysis of biomarkers of the underlying brain disease pathology; a set of cerebrospinal fluid (CSF) tests, amyloid-β1-42 (Aβ42), total-tau (t-tau), and phosphorylated tau (p-tau), are available and their performance in a clinical setting has been assessed in several studies. Thus, in dementia research, great advances have been made in the discovery of putative biomarkers; however, disappointingly, few of them have been translated into clinically applicable assays. To find biomarkers able to reliably detect AD pathology already at prodromal stages and in blood is even more important. Recent technical breakthroughs have provided ultrasensitive methods that allow the detection of brain-specific proteins in blood. In the present review, we will focus on the usefulness of ultrasensitive technologies for biomarker discovery and trace elements detection; moreover, we will review studies on circulating nano-compartments, a promising novel source of material for molecular diagnostics.

Challenges in the diagnosis of Wilson disease

The understanding and management of Wilson disease (WD) have dramatically improved since the first description of the disease by K. Wilson more than a century ago. However, the persistent long delay between the first symptoms and diagnosis emphasizes challenges in diagnosing earlier this copper overload disorder. As a treatable disease, WD should be detected early in the course of the disease by any health professionals at any care level, but the rare prevalence of the disease explains the lack of awareness of referring physicians. The most important challenge is to train physicians to recognize atypical or rare symptoms of WD that will lead to discuss the diagnosis more systematically. Atypia can come from the age of onset, the liver [non-alcoholic steatohepatitis (NASH) presentation], the central or peripheral nervous system (neuropathy, epilepsy, sleep disorders…) or may be due to lesions of other organs (renal manifestations, osteo-articular disorders or endocrine disturbances). Isolated biological anomalies, rare radiological findings or inadequate interpretation of copper test may also lead to misdiagnosis. The second challenge is to confirm the diagnosis faster and more effectively so as not to delay the initiation of treatment, and expand family screening as the genetic prevalence is higher than previously expected. Generalization of the exchangeable copper assay and the next generation sequencing (NGS) are two promising ways to overcome this ultimate challenge. By drawing attention to the earliest and rare symptoms and to new biomarkers and diagnostic tools, we hope that this article will increase diagnostic awareness and reduce delays so that patients can start their treatment earlier in the course of the illness and thus have a better disease prognosis.

New tools for Wilson's disease diagnosis: exchangeable copper fraction

Wilson's disease (WD) biochemical markers continue to evolve. Classical tests [serum copper, serum ceruloplasmin (Cp), urinary copper] have their own limits, and they are often insufficient to diagnose or exclude WD. So, calculated estimation of copper that is not bound to Cp has been proposed, but it is flawed. Therefore, we focused our research on a direct measurement of serum copper labile fraction. Exchangeable copper (CuEXC) offers a correct view of the free copper overload. It provides information on the spread and severity of WD. Relative exchangeable copper (REC) (percentage of exchangeable to total serum copper) that appreciates the toxic fraction of copper in blood is an excellent biomarker for WD diagnosis. These two tests are reliable and non-invasive. They give rapid answers for an appropriate diagnosis and make possible to start the treatment quickly without waiting for the result of the genetic tests. As early diagnosis and treatment are the keystones of successful management of patients with WD, different teams have already applied these tests in a routine framework to a large number of patients.

Biochemical Markers for the Diagnosis and Monitoring of Wilson Disease

Wilson disease (WD) is an autosomal recessively-inherited disorder of copper metabolism and characterised by a pathological accumulation of copper. The ATP7B gene encodes for a transmembrane copper transporter essential for biliary copper excretion. Depending on time of diagnosis, severity of disease can vary widely. Almost all patients show evidence of progressive liver disease. Neurological impairments or psychiatric symptoms are common in WD patients not diagnosed during adolescence. WD is a treatable disorder, and early treatment can prevent the development of symptoms in patients diagnosed while still asymptomatic. This is why the early diagnosis of WD is crucial. The diagnosis is based on clinical symptoms, abnormal measures of copper metabolism and DNA analysis. Available treatment includes chelators and zinc salts which increase copper excretion and reduce copper uptake. In severe cases, liver transplantation is indicated and accomplishes a phenotypic correction of the hepatic gene defect. Recently, clinical development of the new copper modulating agent tetrathiomolybdate has started and direct genetic therapies are being tested in animal models. The following review focuses especially on biochemical markers and how they can be utilised in diagnosis and drug monitoring.

Evaluation of the accuracy of exchangeable copper and relative exchangeable copper (REC) in a mouse model of Wilson's disease

Wilson's disease (WD) is caused by mutations in the ATP7B gene responsible for a toxic copper overload mainly in the liver and the central nervous system. Phenotypic heterogeneity may challenge the diagnostic confirmation. Exchangeable copper (CuEXC) has recently been proposed as a new marker of WD, and its ratio to the total serum copper (Cus), Relative Exchangeable Copper (REC = CuEXC/Cus), as a diagnostic marker. This study aimed to investigate whether this could be confirmed in Atp7b^-/- mice, an engineered WD animal model. Atp7b^-/- (n = 137) and wild type (WT; n = 101) mice were investigated under the same conditions at 6-8, 20, 39, or 50 weeks of age. Twenty-four Atp7b^-/- mice received D-penicillamine treatment from 39 to 50 weeks of age. Serum and liver [histology and intrahepatic copper (IHCu)] data were evaluated. In the WT group, all serum and liver data were normal. Atp7b^-/- livers developed a chronic injury from isolated moderate inflammation (6-8 weeks: 16/33 = 48%) to inflammatory fibrosis with cirrhosis (50 weeks: 25/25 = 100% and 16/25 = 64% respectively). Cus and CuEXC increased until week 39, whereas IHCu and REC were stable with increasing age and much higher than in WT mice (mean ± SD: 669 ± 269 vs. 13 ± 3 μg/g dry liver and 39 ± 12 vs. 11 ± 3%, respectively). A threshold value of 20% for REC provided a diagnostic sensitivity and specificity of 100%, regardless of sex, age, or the use of D-penicillamine. Eleven weeks of 100 mg/kg D-penicillamine reduced liver fibrosis (p = 0.001), IHCu (p = 0.026) and CuEXC (p = 0.175). In conclusion, this study confirms REC as a WD diagnostic marker in a mouse model of chronic liver disease caused by copper overload. Further studies are needed to assess the usefulness of CuEXC to monitor the evolution of WD, particularly during treatment.