Is copper hepatotoxic in primary biliary cirrhosis?

Copper concentrations are prevalently associated with antithrombin III, but also with prothrombin time and fibrinogen in patients with liver cirrhosis: A cross-sectional retrospective study

BACKGROUND

Concerning the link between copper excess and the pathogenesis of chronic liver diseases, its retention is reckoned to develop as a complication of cholestasis. Recently, it has been found that cholestatic liver injury involves largely inflammatory cell-mediated liver cell necrosis, with consequent reduced hepatic mass, more than occurring through direct bile acid-induced apoptosis. On the other hand, interference with protein synthesis could be expected to result, ending in an altered ability of the liver to retain copper. Little is known about the association between serum copper and clotting factors in cirrhotics. We aimed at studying a possible relationship between increased levels of copper and an aspect of the haemostatic process in liver cirrhosis patients, assessing an index of protein synthesis (albumin) and parameters of protein synthesis/coagulation/fibrinolysis, such as prothrombin time (PT), antithrombin (AT) III and fibrinogen.

METHODS

Records from 85 patients suffering from liver cirrhosis of various aetiology and different severity were retrospectively examined. Serum concentrations of copper were determined by atomic absorption spectrophotometer. An index of protein synthesis, such as albumin and parameters of both synthesis and coagulation/hypercoagulation such as PT %, AT III%, levels of fibrinogen were taken into account to study possible correlations to serum copper. The severity of cirrhosis was evaluated by the Child-Pugh (C-P) classification. The relationship among variables were studied by linear regression.

RESULTS

Copper levels of patients suffering from liver cirrhosis were increased respect to those of controls, 102.7+/-28.7 versus 80.4+/-19.5 mcg/dL, (P = .0009), independently from disease severity, and were positively predicted by PT% (P = 0. 017), fibrinogen (P = 0.007) and AT III% (P = 0.000), at linear regression. Among the previous parameters, to which serum albumin was added, the unique predictor of copper levels was AT III%, at multiple regression (P = 0. 010); AT III% was negatively predicted by the C-P classification (P = 0.000); copper levels, adjusted for C-P classification, were predicted by AT III% (P = 0.020) and fibrinogen concentrations, but not by PT% (P = 0.09).

CONCLUSION

The copper concentration is reckoned as responsible for production of the hydroxyl radicals. On the basis that oxidants may enhance the activity of the extrinsic coagulation cascade, ultimately leading to thrombin formation, via their combined effects on stimulation of tissue factor activity and inhibition of fibrinolytic pathways, the positive relationship of copper to coagulation/hypercoagulation parameters (mainly AT III) in our research could find a plausible interpretation.

Primary biliary cirrhosis: Clinical and laboratory criteria for its diagnosis

Primary biliary cirrhosis (PBC) is a chronic progressive cholestatic granulomatous, and destructive inflammatory lesion of small intralobular and septal bile ducts, which is likely to be caused by an autoimmune mechanism with a the presence of serum antimitochondrial antibodies and a potential tendency to progress to cirrhosis. Despite the fact that the etiology of this disease has been unknown so far, there has been a considerable body of scientific evidence that can reveal the clinical and laboratory signs of PBC and the individual components of its pathogenesis and elaborate diagnostic criteria for the disease and its symptomatic therapy. Deficiencies in autoimmune tolerance are critical factors for the initiation and perpetuation of the disease. The purpose of this review is to summarize the data available in the literature and the author’s findings on clinical and laboratory criteria for the diagnosis of PBC. This review describes the major clinical manifestations of the disease and the mechanisms of its development. It presents the immunological, biochemical, and morphological signs of PBC and their significance for its diagnosis. A great deal of novel scientific evidence for the problem of PBC has been accumulated. However, the inadequate efficiency of therapy for the disease lends impetus to the quest for its etiological factors and to further investigations of its pathogenetic mechanisms and, on this basis, to searches for new methods for its early diagnosis.

Primary biliary cirrhosis: specific treatment

No single agent or combination of agents has been shown to unequivocally delay the need for liver transplantation or reduce mortality in patients with PBC. Given this uncertainty, what, if any, specific therapy should be recommended? The agents with the strongest scientific proof of efficacy in well-designed clinical trials are ursodiol, azathioprine, and cyclosporine. Ursodiol is clearly the least toxic of these three. Other agents, such as methotrexate, have shown impressive results in anecdotal studies but have never been adequately tested in randomized clinical trials. Thus, based on the current evidence, imperfect as it is, ursodiol appears to be the safest and potentiaily the most effective specific therapy for patients with PBC. Azathioprine and methotrexate may be the best alternatives for patients who cannot tolerate or do not respond to ursodiol therapy, primarily because their safety has been established in large and lengthy clinical trials. Cylosporine could be considered in patients who fail other treatments (Table 3). We can hope that a safe, highly-effective treatment for patients with PBC will ultimately be discovered. Trials to unequivocally demonstrate the efficacy of new agents will have to be extremely well designed, however, and will require large numbers of patients followed for an extended period of time.

Aberrant expression of cytokeratin 7 as a histological marker of progression in primary biliary cirrhosis

AIM

We evaluated the aberrant expression of cytokeratin 7 (CK-7) in hepatocytes as a marker of cholestasis and progression in primary biliary cirrhosis (PBC).

PATIENTS AND METHODS

The expression of CK-7 was studied by immunohistochemistry in 83 cases of PBC. This expression was compared with biochemical data, the deposition of copper-associated protein, and previous histological classifications.

RESULTS

In normal liver, CK-7 was expressed exclusively in bile duct epithelial cells (BDE). In PBC, the expression was also observed in hepatocytes. The expression pattern was classified as follows: Grade 0, BDE as in normal; Grade 1, proliferated bile ductules; Grade 2, periportal hepatocytes in addition to proliferated bile ductules; Grade 3, intralobular hepatocytes; Grade 4, the majority of hepatocytes. The grades correlated with serum bilirubin levels but not with serum levels of biliary enzymes. A discrepancy between the CK-7 grading and Ludwig's classification was noted in cases with Stage 1 of the CK-7 grading who were considered Stage 2 or 3 in Ludwig's classification, suggesting that cholestasis and inflammatory activity might be independent events.

CONCLUSIONS

These results suggest that the aberrant expression of CK-7 in hepatocytes may be a marker of chronic cholestasis and progression in PBC.

Liver fibrosis in guinea pigs experimentally induced by combined copper and aflatoxin application

Aflatoxin B1 alone (0.05 mg resp. 0.037 mg/kg/d), copper alone (6.6 mg/kg/d or 200 mg/l drinking water) or a combination of both was administrated orally for 6 months to young guinea pigs from the first/second day of life. In the copper group there were no pathomorphological changes. For the aflatoxin B1 group liver damage was established. In the combined group liver injury was more frequent and more severe compared to the aflatoxin B1 group. Compared with the copper group biliary copper excretion was diminished and the kidney copper content was elevated in the Afl. B1 + Cu group. While copper concentrations in bile and kidney correlated with other parameters, notably the pathological lesions of the liver, no such correlation was found for liver copper. Therefore in this experiment the degree of Cu accumulation was not decisive for the liver lesions. The livers' capacity for excreting Cu by bile seems to be a much more important factor. Histologically only the livers of the combined group exhibited degeneration, atrophy and steatosis of liver cells, and a fibrosis more or less pronounced. For childhood cirrhosis (ICC and ICT), a combined etiology--a liver damaging agent plus elevated alimentary copper--is a plausible hypothesis.

Experimental induction of liver fibrosis in young guinea pigs by combined application of copper sulphate and aflatoxin B1

Aflatoxin B1 alone (0.05 mg resp. 0.037 mg/kg/d), copper alone (6.6 mg/kg/d or 200 mg/l drinking water) or a combination of both was administered orally for 6 months to young guinea pigs from the first/second day of life. In the copper group there were no pathomorphological changes. For the aflatoxin B1 group, liver damage was established. In the combined group, liver injury was more frequent and more severe compared to the aflatoxin B1 group and biliary copper excretion was diminished compared with the copper group. Histologically, only the livers of this group exhibited degeneration, atrophy and steatosis of liver cells, inflammatory processes and a more or less prominent fibrosis. For childhood cirrhosis (ICC and ICT) a combined etiology--a liver damaging agent plus elevated alimentary copper--is a plausible hypothesis.

Synergistic liver toxicity of copper and retrorsine in the rat

To investigate the possible synergy between copper and retrorsine (a pyrrolizidine alkaloid) as a cause of Indian Childhood Cirrhosis, four groups of male Wistar rats were fed the following diets from weaning: A. Normal diet; B. Copper loaded (2 g CuSO4/kg diet); C. Retrorsine supplemented (Expt 1:25 mg/kg body weight/week by gavage, Expt 2:25 mg/kg food initially then 15 mg/kg food after 4 weeks); and D. Copper and retrorsine as above. Serial plasma samples were assayed for aminotransferases, albumin and bilirubin. Liver samples at biopsy and sacrifice provided samples for copper analysis and histology. Results showed that copper and retrorsine together significantly increased liver damage compared with feeding either alone as assessed by: 1. Increased mortality rate; 2. Decreased plasma albumin and increased plasma bilirubin (mainly conjugated) indicative of hepatocyte dysfunction; 3. Massive liver copper accumulation, and 4. Increased liver damage histologically. Thus retrorsine caused liver copper accumulation, and together copper and retrorsine led to severe hepatic dysfunction, characterised by hypoalbuminaemia and conjugated hyperbilirubinaemia. Plant alkaloids secreted in milk by grazing animals and copper from brass vessels may together produce Indian Childhood Cirrhosis.

Alpha-tocopherol deficiency fails to aggravate toxic liver injury but liver injury causes alpha-tocopherol retention

The possible aggravation of liver injury by impaired cellular antioxidant function was investigated. A vitamin E-deficient diet (0.5 mg/kg alpha-tocopherol; control 100 mg/kg) significantly reduced rat liver alpha-tocopherol concentrations after 4 weeks (1.8 +/- 1.7 micrograms/g; control 34.4 +/- 2.4 micrograms/g, p < 0.001). The effects of copper loading (Cu, 3 g/kg diet); galactosamine (GalN, 0.85 g/kg i.p.); or carbon tetrachloride (CCl4, 10 mmol/kg i.p.) were examined. Serum aspartate transaminase activity was elevated slightly by vitamin E deficiency but not by hepatic copper accumulation. In vitamin E-replete (E+) and vitamin E-deficient (E-) rats, GalN or CCl4 caused a large and comparable elevation in serum AST and OCT activity. This effect on AST was markedly reduced by copper loading in vitamin E replete (E+) rats, but in E(-) rats copper had significantly less protective effect. Copper also diminished the OCT response to GalN in E+, though not E-, rats. A significant rise in total hepatic alpha-tocopherol content followed administration of GalN or CCl4 in both normocupric and copper-laden E(-) rats. Thus alpha-tocopherol deficiency (a) was not hepatotoxic per se; (b) failed to potentiate the toxicity of copper, GalN or CCL4; but (c) partially abolished the protection by copper against toxin-induced liver injury. Retention of hepatic alpha-tocopherol after liver damage may partly explain low serum vitamin E levels seen in clinical liver disease.

Three stages of copper accumulation in hepatocellular lysosomes: X-ray microanalysis of copper-loaded golden hamsters

Male golden hamsters were loaded with copper by supplying them for up to 12 weeks with drinking water containing 0.5% cupric acetate. The copper feeding increased hepatic copper to widely varying levels. Energy dispersive X-ray microanalysis could always identify a copper-sulphur complex in the hepatocyte lysosomes of copper-loaded hamsters and the X-ray intensity of copper was found to be a reliable parameter to measure in-situ copper accumulation. Combining this parameter with the copper binding ratio expressed by delta Cu/delta S enabled us to discern two stages of sub-histochemical copper accumulation. The first stage was marked by low levels of both lysosomal copper and binding ratio, which suggested that this initial copper transfer was mediated by unsaturated cuproproteins. The second stage was characterized by median amounts of lysosomal copper and a binding ratio of more than 0.50. At the third stage, histochemically detectable copper appeared in animals whose lysosomal copper was extraordinarily high in later experimental periods. With the copper binding ratio being in the same range of 0.50-0.83, it seemed that saturated cuproproteins were the main mediator of copper transport in the later two stages.

Liver cell carcinoma with orcein-positive granules and no identifiable copper

A liver cell carcinoma removed surgically by partial hepatectomy from a 79-year-old woman contained abundant orcein-positive granules in many tumour cells. The granules were similar to those usually identified as representing copper-associated protein, yet they lacked copper, as demonstrated by negative rhodanine and rubeanic acid stains and energy dispersive X-ray microanalysis.

Review: the treatment of primary biliary cirrhosis

Considerable improvement in quality of life can be achieved by treating the complications of primary biliary cirrhosis. However, once fibrosis, cirrhosis, portal hypertension and hyperbilirubinaemia occur, it is unlikely that 'medical' treatment will cure the disorder. Trials of medical therapy should aim to delay or halt the progression of the early phase of the disease and clinicians should refer patients to centres conducting clinical trials. If the disease progresses, and the quality of life is seriously impaired, liver transplantation offers the realistic chance of a new life.

Hypothesis: plant and fungal biocides, copper and Indian childhood liver disease

Hepatic copper accumulation is characteristic of Indian childhood cirrhosis (ICC) but in experimental animals causes only modest liver damage. Plant and fungal biocidal agents may be hepatotoxic, may increase hepatic copper concentration, and may be secreted in milk of lactating animals. Crotalaria species, Parthenium hysterophorus and Aspergillus flavus are possible contaminants of animal feeds in rural India, and we hypothesise that their products may be synergistic with copper in causing ICC.

Some medical applications of the oxford scanning proton microprobe

Results from several medical investigations carried out using the Oxford scanning proton microprobe are presented, including maps of the hepatic copper-distribution in primary biliary cirrhosis and maps of the iron distribution in primary hemochromatosis. Preliminary studies of human nervous tissue reveal that morphologically recognizable structures can be differentiated using precision elemental mapping, and this may lead to a powerful new way of distinguishing subtle perturbations of structure and function. In further prelimianry studies, localized aluminum structures have been observed in Alzheimer's disease tissue at bulk levels of less than parts per million.

The ontogeny of liver copper metabolism in the guinea pig: clues to the etiology of Wilson's disease

The normal human neonate has a copper profile indistinguishable from Wilson's disease, and we have previously postulated that this disease is caused by genetic failure to switch from the fetal to adult mode of copper metabolism. This study validates the developing guinea pig as a suitable animal in which to study copper ontogeny. At birth, liver copper concentrations are 7 times higher than in adults and serum copper and ceruloplasmin are 27 and 21% of adult values, respectively. A 53% fall in liver copper occurs in the 4 days after birth. This is associated with a marked increase in bile copper output, which does not parallel increasing bile flow. Liver copper falls, and serum copper and ceruloplasmin increase to near adult levels in the 30 days after birth. Until the sixtieth day of gestation, liver copper was significantly increased in copper-stressed littermates, although paradoxically at birth, concentrations were significantly lower. In copper-stressed fetal animals, bile copper output increased markedly before birth. Metallothionein was the dominant copper-binding protein in the fetal liver but a minor component in the adult. Superoxide dismutase activity only developed after birth. We conclude that the postnatal switch from the fetal to adult mode of copper metabolism involves activation of biliary excretion and ceruloplasmin export as well as changes in the association of copper with hepatic copper proteins. Similarities between the fetus and Wilson's disease suggest that this disease is caused by failure of this postnatal adaptation process.

Hepatic copper distribution in primary biliary cirrhosis shown by the scanning proton microprobe

A number of conditions are associated with abnormalities of trace metal handling by the liver. We report the application of the Oxford scanning proton microprobe to the analysis of hepatic copper in one such condition, primary biliary cirrhosis. The scanning proton microprobe analyses conventional tissue sections (5-10 micron thickness) and produces simultaneous elemental distribution maps of biologically relevant elements with a spatial resolution of 1 micron and a detection limit better than 1 ppm. We have confirmed the localisation of excess copper to periportal areas and suggest that such accumulation is confined to a proportion of periportal hepatocytes. We have also shown a close spatial correlation between regions of copper accumulation and areas of high sulphur concentration. The copper to sulphur ratio in these areas is consistent with their identity as aggregates of copper loaded metallothionein, and the scanning proton microprobe was further able to show that the aggregates contain less than 30 ppm zinc.

Diagnostic and prognostic value of serum copper and plasma fibrinogen in hepatic carcinoma

To investigate the diagnostic and prognostic value of several biochemical tests in primary liver tumors, the authors studied 36 cases (4 cholangiocarcinomas and 32 hepatocellular carcinomas, 10 of which were associated with cirrhosis) and 47 cases of liver cirrhosis, all with morphologically proven diagnosis. Serum copper (SCu) and plasma fibrinogen (PF) appeared the most useful tests in differential diagnosis between tumors and cirrhosis. In liver tumors, mean SCu level was 200.50, standard deviation (SD) 47.17 micrograms/dl (121.40, SD 25.90 micrograms/dl in cirrhosis; P less than 0.001). PF level was 461.78, SD 151.25 mg/dl in tumors (275.30 SD, 124.40 mg/dl in cirrhosis; P less than 0.001). SCu had a good sensitivity (0.80) and a high specificity (0.92) at a cutoff value of 160 micrograms/dl; when the cutoff level was raised to 170 micrograms/dl, the specificity increased to 1, with a sensitivity of 0.77. The combination of SCu and PF improved the diagnostic value slightly. Moreover, with an estimated frequency of tumor in cirrhosis of 10%, SCu had a positive predictive value of 1 (cutoff, 170 micrograms/dl) and a negative predictive value of 0.97. In nine patients SCu levels decreased after surgical removal of tumor; five other patients, sequentially studied, showed an increase of SCu level that correlated with the progression of the disease. Finally, patients with longer survival had a lower SCu level. These findings suggest that SCu level may be used as a screening test for early detection of neoplastic degeneration, and it is correlated with the extension of tumor mass.

Double blind controlled trial of d-penicillamine in patients with primary biliary cirrhosis

One hundred and eighty nine patients with primary biliary cirrhosis were entered into a double blind, placebo controlled randomised trial starting in January 1978 to assess the therapeutic value of d-penicillamine 1200 mg daily. Eighteen of the 98 patients receiving d-penicillamine and 22 of the 91 placebo treated patients died during the study. Thirty six per cent of those on d-penicillamine and 8% of those on placebo were withdrawn from the study. No difference in overall survival was noted between the two groups of patients whether the results were analysed for the entire period of observation or only during the period in which the patients were receiving therapy. The mortality rate of those receiving d-penicillamine in histological stage I to II, however, was one third of that of the placebo group although this difference did not reach statistical significance. Using the occurrence rate ratio as the statistical method of analysis, no effect of d-penicillamine was noted on any clinical, biochemical or histological features examined, except the serum alanine aminotransferase activity which was greater in those on active treatment. In this trial we have been unable to establish any therapeutic benefit from the drug.

Trace elements in human body fluids and tissues

Published figures for trace element concentrations in body fluids and tissues of apparently healthy subjects are widely divergent. For a considerable time, the apparent disparities were readily ascribed to biological sources of variation such as age, sex, dietary habits, physiological conditions, environmental exposure, geographical circumstances, or similar influences. Growing evidence, however, suggests that this interpretation may be seriously questioned in numerous instances. First, values obtained in reference materials leave no doubt that some previous studies must have been subject to gross analytical inaccuracies. Second, it has now been thoroughly documented that inadequate sample collection and manipulation may drastically distort the intrinsic trace element content of biological matrices. This review scrutinizes data reported by a number of investigators. In an effort to settle the currently flourishing confusion, critically selected reference values are set forth for trace element levels in human blood plasma or serum, packed blood cells, urine, lung, liver, kidney, and skeletal muscle tissue.

The lysosomal copper concentration in the liver in primary biliary cirrhosis

The copper concentration in the lysosomes of periportal hepatocytes of nine patients with primary biliary cirrhosis was determined by X-ray microanalysis in ultrathin sections, the chlorine concentration of the embedding medium being taken as internal standard. A positive correlation was found between the lysosomal and the total liver copper concentration. No correlation was found between the lysosomal copper concentration and the grade of orcein staining for lysosomal copper-associated protein in paraffin sections. It is concluded that in contrast to the grade of orcein staining, the lysosomal copper concentration is a reliable measure of the total liver copper concentration in primary biliary cirrhosis.

Species differences in the occurrence of copper-metallothionein in the particulate fractions of the liver of copper-loaded animals

Large amounts of Cu-metallothionein were obtained by 2-mercaptoethanol and sodium dodecyl sulphate extractions of the particulate fractions of the liver of pigs given high-Cu2+ diets or rats injected with Cu2+. Three isoproteins were purified from pig liver and characterized on the basis of their physicochemical properties, metal content and amino acid composition. No such pool of Cu-metallothionein was present in the liver of Cu2+-loaded sheep or of rats given Cu2+-supplemented diets.

Immunohistochemical demonstration of the cytoplasmic copper-associated protein in the liver in primary biliary cirrhosis: its identification as metallothionein

Metallothionein was isolated from the liver of rats pretreated with cadmium. Monospecific anti-metallothionein antibodies were produced in rabbits. Twenty-six primary biliary cirrhosis (PBC) liver samples and three control liver samples were stained for metallothionein by an indirect immunoperoxidase technique. Nineteen of the PBC samples and the control samples were also stained for copper by Timm's silver sulphide method. In all PBC samples the copper concentration was determined. In addition, the zinc, cadmium, and mercury concentrations were measured in some samples. Eighteen of the PBC samples stained for metallothionein showed marked diffuse cytoplasmic and nuclear staining of a varying number of periportal hepatocytes. In none of them was granular staining detected. None of the control samples showed staining. Fourteen of the PBC samples stained for copper showed diffuse cytoplasmic and granular staining of the periportal hepatocytes. In none of them was nuclear staining detected. None of the control samples showed staining. No elevated zinc, cadmium, or mercury concentrations were found but the copper concentration was increased in 21 of the 26 PBC samples. The number of cells staining for copper and metallothionein was assessed semiquantitatively. Significant correlations were found between the grade of metallothionein staining and the liver copper concentration; the grade of Timm's staining and the liver copper concentration; and the grades of metallothionein staining and Timm's staining. The data suggest that the accumulation of copper induces synthesis of cytoplasmic and nuclear metallothionein, and that the increased amount of cytoplasmic copper is bound to a similarly increased amount of metallothionein.

Patterns of hepatocyte injury in man

Three patterns of hepatocyte injury in man, direct, immunological, and cholestatic, are described. The characteristics of the direct pattern are predominantly mitochondrial damage, central (zone 3) necrosis, and, usually, fatty change. It can be subdivided into the alcohol type (also seen with obesity, in diabetes, as a reaction to perhexiline, in Wilson's disease, and in Indian childhood cirrhosis) and the Reye's syndrome type (also seen with tetracycline toxicity, fatty liver of pregnancy, and cytotoxic drugs). Reactive drug metabolites, metal poisoning, and anoxia are also associated with the direct pattern of hepatocyte injury. The immunological pattern is characterised by damage to cell membranes with piecemeal necrosis of periportal (zone 1) hepatocytes and mononuclear-cell infiltration. Examples include chronic active hepatitis, primary biliary cirrhosis, and drug reactions such as those to halothane. In the cholestatic pattern there is disturbance of the bile-secretory mechanism with retention of bile within the hepatocytes. Cholestatic liver injury may be intrahepatic, as in sex-hormone cholestasis, or extrahepatic, as in choledocholithiasis or carcinoma of the bile ducts. Identification of the type of hepatocyte injury is valuable in diagnosis, in assessing prognosis, and in selecting treatment.