Effects of disulfiram treatment in patients with Menkes disease and occipital horn syndrome

Mitochondrial copper in human genetic disorders

Copper is an essential micronutrient that serves as a cofactor for enzymes involved in diverse physiological processes, including mitochondrial energy generation. Copper enters cells through a dedicated copper transporter and is distributed to intracellular cuproenzymes by copper chaperones. Mitochondria are critical copper-utilizing organelles that harbor an essential cuproenzyme cytochrome c oxidase, which powers energy production. Mutations in copper transporters and chaperones that perturb mitochondrial copper homeostasis result in fatal genetic disorders. Recent studies have uncovered the therapeutic potential of elesclomol, a copper ionophore, for the treatment of copper deficiency disorders such as Menkes disease. Here we review the role of copper in mitochondrial energy metabolism in the context of human diseases and highlight the recent developments in copper therapeutics.

Early clinical signs and treatment of Menkes disease

Menkes disease (MD) is an X-linked recessive disorder caused by mutations in ATP7A. Patients with MD exhibit severe neurological and connective tissue disorders due to copper deficiency and typically die before 3 years of age. Early treatment with copper injections during the neonatal period, before the occurrence of neurological symptoms, can alleviate neurological disturbances to some degree. We investigated whether early symptoms can help in the early diagnosis of MD. Abnormal hair growth, prolonged jaundice, and feeding difficulties were observed during the neonatal period in 20 of 69, 16 of 67, and 3 of 18 patients, respectively. Only three patients visited a physician during the neonatal period; MD diagnosis was not made at that point. The mean age at diagnosis was 8.7 months. Seven patients, who were diagnosed in the prenatal stage or soon after birth, as they had a family history of MD, received early treatment. No diagnosis was made based on early symptoms, highlighting the difficulty in diagnosing MD based on symptoms observed during the neonatal period. Patients who received early treatment lived longer than their elderly relatives with MD. Three patients could walk and did not have seizures. Therefore, effective newborn screening for MD should be prioritized.

Metals and Metal-Nanoparticles in Human Pathologies: From Exposure to Therapy

An increasing number of pathologies correlates with both toxic and essential metal ions dyshomeostasis. Next to known genetic disorders (e.g., Wilson's Disease and β-Thalassemia) other pathological states such as neurodegeneration and diabetes are characterized by an imbalance of essential metal ions. Metal ions can enter the human body from the surrounding environment in the form of free metal ions or metal-nanoparticles, and successively translocate to different tissues, where they are accumulated and develop distinct pathologies. There are no characteristic symptoms of metal intoxication, and the exact diagnosis is still difficult. In this review, we present metal-related pathologies with the most common onsets, biomarkers of metal intoxication, and proper techniques of metal qualitative and quantitative analysis. We discuss the possible role of drugs with metal-chelating ability in metal dyshomeostasis, and present recent advances in therapies of metal-related diseases.

Pharmacokinetics of CuGTSM, a Novel Drug Candidate, in a Mouse Model of Menkes Disease

PURPOSE

Menkes disease is a rare hereditary disease in which systemic deficiency of copper due to mutation of the ATP7A gene causes severe neurodegenerative disorders. The present parenteral drugs have limited efficacy, so there is a need for an efficacious drug that can be administered orally. This study focused on glyoxal-bis (N(4)-methylthiosemicarbazonato)-copper(II (CuGTSM), which has shown efficacy in macular mice, a murine model of Menkes disease, and examined its pharmacokinetics. In addition, nanosized CuGTSM (nCuGTSM) was prepared, and the effects of nanosizing on CuGTSM pharmacokinetics were investigated.

METHODS

CuGTSM or nCuGTSM (10 mg/kg) was administered orally to male macular mice or C3H/HeNCrl mice (control), and plasma was obtained by serial blood sampling. Plasma concentrations of CuGTSM and GTSM were measured by LC-MS/MS and pharmacokinetic parameters were calculated.

RESULTS

When CuGTSM was administered orally, CuGTSM and GTSM were both detected in the plasma of both mouse strains. When nCuGTSM was administered, the C_max was markedly higher, and the mean residence time was longer than when CuGTSM was administered for both CuGTSM and GTSM in both mouse strains. With macular mice, the AUC ratio (GTSM/CuGTSM) was markedly higher and the plasma CuGTSM concentration was lower than with C3H/HeNCrl mice when either CuGTSM or nCuGTSM was administered.

CONCLUSION

Absorption of orally administered CuGTSM was confirmed in macular mice, and the nano-formulation improved the absorption and retention of CuGTSM in the body. However, the plasma concentration of CuGTSM was lower in macular mice than in control mice, suggesting easier dissociation of CuGTSM.

Defining the Clinical, Molecular and Ultrastructural Characteristics in Occipital Horn Syndrome: Two New Cases and Review of the Literature

Occipital horn syndrome (OHS) is a rare connective tissue disorder caused by pathogenic variants in ATP7A, encoding a copper transporter. The main clinical features, including cutis laxa, bony exostoses, and bladder diverticula are attributed to a decreased activity of lysyl oxidase (LOX), a cupro-enzyme involved in collagen crosslinking. The absence of large case series and natural history studies precludes efficient diagnosis and management of OHS patients. This study describes the clinical and molecular characteristics of two new patients and 32 patients previously reported in the literature. We report on the need for long-term specialized care and follow-up, in which MR angiography, echocardiography and spirometry should be incorporated into standard follow-up guidelines for OHS patients, next to neurodevelopmental, orthopedic and urological follow-up. Furthermore, we report on ultrastructural abnormalities including increased collagen diameter, mild elastic fiber abnormalities and multiple autophagolysosomes reflecting the role of lysyl oxidase and defective ATP7A trafficking as pathomechanisms of OHS.

Chelating principles in Menkes and Wilson diseases: Choosing the right compounds in the right combinations at the right time

Dysregulation of copper homeostasis in humans is primarily found in two genetic diseases of copper transport, Menkes and Wilson diseases, which show symptoms of copper deficiency or overload, respectively. However, both diseases are copper storage disorders despite completely opposite clinical pictures. Clinically, Menkes disease is characterized by copper deficiency secondary to poor loading of copper-requiring enzymes although sufficient body copper. Copper accumulates in non-hepatic tissues, but is deficient in blood, liver, and brain. In contrast, Wilson disease is characterized by symptoms of copper toxicity secondary to accumulation of copper in several organs most notably brain and liver, and a saturated blood copper pool. It is a challenge to correct copper dyshomeostasis in either disease though copper depletion in Menkes disease is most challenging. Both diseases are caused by defective copper export from distinct cells, and we seek to give new angles and guidelines to improve treatment of these two complementary diseases. Therapy of Menkes disease with copper-histidine, thiocarbamate, nitrilotriacetate or lipoic acid is discussed. In Wilson disease combination of a hydrophilic chelator e.g. trientine or dimercaptosuccinate with a brain shuttle e.g. thiomolybdate or lipoate, is discussed. New chelating principles for copper removal or delivery are outlined.

[Recent Trends of Trace Element Studies in Clinical Medicine in Japan]

The deficiency or excess intake of trace elements, including zinc, copper, selenium and iodine, has often been reported. Zinc deficiency is often observed in infants fed breast milk with low zinc concentration, individuals administered chelating medicines, athletes and patients with diabetes mellitus, hepatic cirrhosis or nephrosis syndrome. Menkes disease is associated with severe copper deficiency, and there is no effective treatment. Deficiencies of selenium and iodine are observed in patients who receive special formulas of milk and enteral formula with low selenium and iodine concentrations, respectively. In contrast, neonatal transient hypothyroidism due to excess intake of iodine in pregnant women has also reported in Japan. It is expected that collaborative studies by researchers and clinicians will contribute to clarify the detail mechanism, diagnosis and treatment of these abnormalities.

Menkes disease and response to copper histidine: An Indian case series

Background:

Menkes disease (MD) is an X-linked recessive neurodegenerative disorder caused by mutations in ATP7A gene. Depending on the residual ATP7A activity, manifestation may be classical MD, occipital horn syndrome, or distal motor neuropathy. Neurological sparing is expected in female carriers. However, on rare occasions, females may manifest with classical clinical phenotype due to skewed X-chromosome inactivation, X-autosome translocation, and XO genotype. Here, we describe a small series of probands with MD and their response to copper histidine therapy. This series also includes a female with X-13 translocation manifesting neurological symptoms.

Methods:

The clinical profile, laboratory and radiological data, and follow-up of four children with MD were collected from the hospital database and are being presented.

Results:

All the four children in our series had developmental delay, recurrent respiratory tract infections, hair and skeletal changes, axial hypotonia, tortuous vessels on imaging, low serum copper, ceruloplasmin, and elevated lactate. Fetal hypokinesia and fetal growth retardation were present in two cases. Failure to thrive was present in three children and only one child had epilepsy. Subcutaneous copper histidine was administered to all children. The average time lapse in the initiation of treatment was 20.3 months, and average duration of follow-up was 14.3 months.

Conclusion:

We conclude that copper histidine therapy is beneficial in reversing the skin and hair changes, improving appendicular tone, socio-cognitive milestones, and improving weight gain, and immunity. Early diagnosis and management of MD are essential to have a better clinical outcome. More research is needed to explore and devise new strategies in the management of patients with MD.

Disulfiram and Copper Ions Kill Mycobacterium tuberculosis in a Synergistic Manner

Tuberculosis is a severe disease affecting millions worldwide. Unfortunately, treatment strategies are hampered both by the prohibitively long treatment regimen and the rise of drug-resistant strains. Significant effort has been expended in the search for new treatments, but few options have successfully emerged, and new treatment modalities are desperately needed. Recently, there has been growing interest in the synergistic antibacterial effects of copper ions (Cu(II/I)) in combination with certain small molecular compounds, and we have previously reported development of a drug screening strategy to harness the intrinsic bactericidal properties of Cu(II/I). Here, we describe the copper-dependent antimycobacterial properties of disulfiram, an FDA-approved and well-tolerated sobriety aid. Disulfiram was inhibitory to mycobacteria only in the presence of Cu(II/I) and exerted its bactericidal activity well below the active concentration of Cu(II/I) or disulfiram alone. No other physiologically relevant bivalent transition metals (e.g., Fe(II), Ni(II), Mn(II), and Co(II)) exhibited this effect. We demonstrate that the movement of the disulfiram-copper complex across the cell envelope is porin independent and can inhibit intracellular protein functions. Additionally, the complex is able to synergistically induce intracellular copper stress responses significantly more than Cu(II/I) alone. Our data suggest that by complexing with disulfiram, Cu(II/I) is likely allowed unfettered access to vulnerable intracellular components, bypassing the normally sufficient copper homeostatic machinery. Overall, the synergistic antibacterial activity of Cu(II/I) and disulfiram reveals the susceptibility of the copper homeostasis system of Mycobacterium tuberculosis to chemical attacks and establishes compounds that act in concert with copper as a new class of bacterial inhibitors.

Disulfiram and Copper Ions Kill Mycobacterium tuberculosis in a Synergistic Manner

Tuberculosis is a severe disease affecting millions worldwide. Unfortunately, treatment strategies are hampered both by the prohibitively long treatment regimen and the rise of drug-resistant strains. Significant effort has been expended in the search for new treatments, but few options have successfully emerged, and new treatment modalities are desperately needed. Recently, there has been growing interest in the synergistic antibacterial effects of copper ions (Cu(II/I)) in combination with certain small molecular compounds, and we have previously reported development of a drug screening strategy to harness the intrinsic bactericidal properties of Cu(II/I). Here, we describe the copper-dependent antimycobacterial properties of disulfiram, an FDA-approved and well-tolerated sobriety aid. Disulfiram was inhibitory to mycobacteria only in the presence of Cu(II/I) and exerted its bactericidal activity well below the active concentration of Cu(II/I) or disulfiram alone. No other physiologically relevant bivalent transition metals (e.g., Fe(II), Ni(II), Mn(II), and Co(II)) exhibited this effect. We demonstrate that the movement of the disulfiram-copper complex across the cell envelope is porin independent and can inhibit intracellular protein functions. Additionally, the complex is able to synergistically induce intracellular copper stress responses significantly more than Cu(II/I) alone. Our data suggest that by complexing with disulfiram, Cu(II/I) is likely allowed unfettered access to vulnerable intracellular components, bypassing the normally sufficient copper homeostatic machinery. Overall, the synergistic antibacterial activity of Cu(II/I) and disulfiram reveals the susceptibility of the copper homeostasis system of Mycobacterium tuberculosis to chemical attacks and establishes compounds that act in concert with copper as a new class of bacterial inhibitors.

A novel two-nucleotide deletion in the ATP7A gene associated with delayed infantile onset of Menkes disease

BACKGROUND

Determining the relationship between clinical phenotype and genotype in genetic diseases is important in clinical practice. In general, frameshift mutations are expected to produce premature termination codons, leading to production of mutant transcripts destined for degradation by nonsense-mediated decay. In X-linked recessive diseases, male patients with frameshift mutations typically have a severe or even lethal phenotype.

PATIENT

We report a case of a 17-month-old boy with Menkes disease (NIM #309400), an X-linked recessive copper metabolism disorder caused by mutations in the ATP7A copper transporter gene. He exhibited an unexpectedly late onset and experienced milder symptoms.

STUDY AND RESULT

His genomic DNA showed a de novo two-nucleotide deletion in exon 4 of ATP7A, predicting a translational frameshift and premature stop codon, and a classic severe phenotype. Characterization of his ATP7A mRNA showed no abnormal splicing.

CONCLUSION

We speculate that translation reinitiation could occur downstream to the premature termination codon and produce a partially functional ATP7A protein. Study of the child's fibroblasts found no evidence of translation reinitiation; however, the possibility remains that this phenomenon occurred in neural tissues and influenced the clinical phenotype.