Advances in Treatment of Wilson Disease

Background: Wilson disease (WD) is an inherited neurometabolic disorder that results in excessive copper deposition in the liver and the brain, affecting children and young adults. Without treatment the disease is invariably fatal. Though treatments for WD have been available since the 1950s, the disease continues to be associated with considerable morbidity and mortality because of missed diagnosis, and delayed or inadequate treatment. In this paper we survey WD-related literature in order to review recent advances in WD treatment. Methods: We performed a literature search using the PubMed database for articles relating to WD and its medical treatment. We reviewed the articles, and cross-references of relevant articles, to summarize the current practices for treatment of WD. Results: The survey shows that if WD is properly treated, in most patients the liver can be stabilized, even severe neurological disability reversed, and patients can resume normal lives. Discussion: Medical treatment for WD includes use of copper chelators (penicillamine, trientine, dimercaprol, dimercaptopropane sulfonate, and ammonium tetrathiomolybdate) and drugs that decrease gastrointestinal copper absorption. Our knowledge of the treatment approaches has benefited from the large systematic clinical studies that have been conducted over the last decade. For each drug used to treat WD, we surveyed its development, indication for use, dosing, efficacy, and adverse effects

Eye sign in an 18 year old man with psychosis

Annu Aggarwal and Mohit Bhat

Drug induced tolerance of copper treated KO cells.

<p>Cells were treated with Zn, DPA and Zn+DPA and viability was determined by MTT assay. Zn pretreatment was for 2 h. DPA and Cu exposure was for 48 h. The gain of viability following treatment (black) is given relative to the viability of untreated KO (open) and HepG2 cells (shadow). Significance (p<0.05) is indicated: *treated vs untreated; ^†gain by treatment in KO vs. gain in HepG2 cells; ^aZn+DPA treatment vs. Zn; ^bZn+DPA treatment vs. DPA.</p

Cellular copper in KO cells after drug treatment.

<p>Cells were treated with drugs essentially as described for <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0098809#pone-0098809-g005" target="_blank">Figure 5</a>. 0.1 mM Cu was used. Cells were subjected to Cu determination by AAS. Total cellular Cu of KO (black) and HepG2 cells (open) is given relative to the absolute number of the Cu concentration as shown in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0098809#pone-0098809-g004" target="_blank">Figure 4A</a> (100%). Data is represented as mean±SE of three independent experiments. Asterisks indicate significance (p<0.05).</p

The Effect of Zinc and D-Penicillamine in a Stable Human Hepatoma <i>ATP7B</i> Knockout Cell Line

<div><p>Mutations in the copper (Cu) transporter gene <i>ATP7B</i>, the primary cause of Wilson disease (WD), result in high liver Cu and death of hepatocytes. Cu chelators and zinc salts are the two most important drugs used in the treatment of WD patients; however, the molecular mechanisms of the drugs with regard to <i>ATP7B</i> expression have not been determined. A targeted knockout of <i>ATP7B</i> (KO) was established in the most widely used human hepatoma cell line, HepG2 for molecular studies of the pathogenesis and treatment of the disease. KO cells showed similar growth, Cu uptake, release, and gene expression as compared to parental cells. However, in the presence of Cu, morphological changes, oxidative stress, apoptosis, and loss of viability were observed. Induction of metallothionein (<i>MT1X</i>) after Cu exposure was significantly reduced in KO cells. Following zinc treatment, <i>MT1X</i> expression was strongly induced and a high percentage of KO cells could be rescued from Cu induced toxicity. D-penicillamine treatment had a minor effect on the viability of KO cells whereas the parental cell line showed a pronounced improvement. Combined treatment displayed a highly synergistic effect in KO cells. The data suggest that zinc has a previously unrecognized effect on the viability of hepatocytes that lack <i>ATP7B</i> due to a high induction of <i>MT1X</i> expression that compensates low gene expression after Cu exposure. A combination therapy that simultaneously targets at <i>MT1X</i> induction and Cu chelation improves the overall survival of hepatocytes for most efficient therapy of patients having WD.</p></div

Oxidative stress and viability of KO cell line.

<p>(A) Oxidative stress following Cu exposure at 0.1 mM Cu for 1 h. The four histograms represent fluorescence of viable cells as obtained by flow cytometry after staining with H₂DCFDA dye. A shift of the two histograms appears in KO cells after Cu exposure (shaded) relative to untreated control (open) indicating induction of OS. (B) Viability of KO (circles) and HepG2 cells (triangle) relative to untreated control was determined by MTT assay after 48 h of Cu exposure. (C) Induction of apoptosis was determined after 24 h of 0.1 mM Cu exposure using Annexin-V staining followed by flow cytometry analysis. (D) Cell viability of knockin versus KO cell is shown. Viability was determined at 0.5 mM Cu by MTT assay after 48 h. Data is represented as mean±SE of three independent experiments. Asterisks indicate significance (p<0.05).</p