Porphyria cutanea tarda

Cutaneous deposits

: The cutaneous deposition disorders are a group of unrelated conditions characterized by the accumulation of either endogenous or exogenous substances within the skin. These cutaneous deposits are substances that are not normal constituents of the skin and are laid down usually in the dermis, but also in the subcutis, in a variety of different circumstances. There are 5 broad categories of cutaneous deposits. The first group includes calcium salts, bone, and cartilage. The second category includes the hyaline deposits that may be seen in the dermis in several metabolic disorders, such as amyloidosis, gout, porphyria, and lipoid proteinosis. The third category includes various pigments, heavy metals, and complex drug pigments. The fourth category, cutaneous implants, includes substances that are inserted into the skin for cosmetic purposes. The fifth category includes miscellaneous substances, such as oxalate crystals and fiberglass. In this article, the authors review the clinicopathologic characteristics of cutaneous deposition diseases, classify the different types of cutaneous deposits, and identify all the histopathologic features that may assist in diagnosing the origin of a cutaneous deposit.

Erythrocyte uroporphyrinogen decarboxylase activity and therapeutic phlebotomy in porphyria cutanea tarda

On the basis of the uroporphyrinogen decarboxylase ( UD ) activity in the erythrocytes, and the family history of the disease, different types of porphyria cutanea tarda ( PCT ) can be distinguished. In some cases, however, the distinction may involve some uncertainty (overlapping of subgroups). The question arises of whether the current erythrocyte UD activities in the different types of PCT are determined merely genetically. The erythrocyte UD activities in 72 unrelated patients with different forms of PCT (62 with type I PCT and 10 with type II PCT ), in different stages of the disease, were measured in order to test whether the activity exhibits any change during the long period of recovery. In both types the activities were faintly but significantly increased, from 94.9% (in PCT I) or 54.3% (in PCT II) up to 98.4% or 56.1% respectively. In both types the lower activity in the untreated condition can be attributed to a combination of several factors, including oxidative damage to UD , which results in a minor additional inhibition of the genetically determined enzyme activities.

Iron overload states

Hereditary hemochromatosis is a common disorder of iron metabolism that increasingly is diagnosed and treated prior to the development of cirrhosis or diabetes. The discovery of a candidate gene for hereditary hemochromatosis undoubtedly will result in improved diagnosis of hereditary hemochromatosis and to a better understanding of certain aspects of iron absorption, hepatic iron uptake and release, and whole body iron metabolism. In turn, this enhanced understanding of iron biology can be applied to the observations seen in patients with other hepatic diseases such as chronic viral hepatitis.

Porphyria in childhood

Porphyria in childhood is an uncommon problem but the recognition of these disorders is vitally important for affected children. Of the cutaneous porphyrias, erythropoietic protoporphyria, congenital erythropoietic porphyria, hepatoerythropoietic porphyria, and the hereditary form of porphyria cutanea tarda (PCT) can present in infancy or childhood. This article focuses on the porphyrias that present in infants and children along with a brief discussion of pathogenesis, cutaneous histopathology, and genetics of these metabolic disorders.

Treatment of the porphyrias

There are seven porphyrias which are caused by defective functions of the enzymes in the haem biosynthesis. Pathogenic mechanisms and symptoms differ greatly in individual porphyrias and, consequently, most of them require a specific therapy. Clinically, the three most important entities are acute porphyric attack, porphyria cutanea tarda and protoporphyria. For an acute porphyric attack the treatment of choice is administration of haem; the other measures are elimination of precipitating factors and symptomatic therapy for many associated symptoms. Porphyria cutanea tarda is controlled by removal of iron by phlebotomies or with low-dose chloroquine. Skin symptoms in protoporphyria can be alleviated with betacaroten but there is no effective procedure to normalize disturbed porphyrin metabolism; hepatic failure seen in some patients may need a liver transplantation. The only effective treatment in congenital erythropoietic porphyria is probably a bone marrow transplantation. No satisfactory treatment is available for very rare delta-aminolevulinic acid dehydrase deficiency porphyria.

Allosteric inhibition of human lymphoblast and purified porphobilinogen deaminase by protoporphyrinogen and coproporphyrinogen. A possible mechanism for the acute attack of variegate porphyria

Variegate porphyria (VP) is characterized by photocutaneous lesions and acute neuropsychiatric attacks. Decreased protoporphyrinogen oxidase activity results in accumulation of protoporphyrin (ogen) IX and coproporphyrin (ogen) III. During acute attacks delta-aminolevulinic acid and porphobilinogen also increase, suggesting that porphobilinogen deaminase (PBG-D) may be rate limiting. We have examined the effects of porphyrinogens accumulating in VP on PBG-D activity in Epstein-Barr virus-transformed lymphoblast sonicates from 12 VP and 12 control subjects. Protoporphyrinogen oxidase activity was decreased and protoporphyrin increased in VP lymphoblasts. PBG-D in control lymphoblasts obeyed Michaelis-Menten kinetics (Vmax 28.7 +/- 1.8 pmol/mg per h, Hill coefficient 0.83 +/- 0.07). VP sonicates yielded sigmoidal substrate-velocity curves that did not obey Michaelis-Menten kinetics. Vmax was decreased (21.2 +/- 2.0 pmol/mg per h) and the Hill coefficient was 1.78 +/- 0.17. Addition of protoporphyrinogen IX and coproporphyrinogen III to control sonicates yielded sigmoidal PBG-D substrate-velocity curves and decreased PBG-D Vmax. Addition of porphyrins or uroporphyrinogen III did not affect PBG-D activity. Removal of endogenous porphyrin (ogens) from VP sonicates restored normal PBG-D kinetics. Purified human erythrocyte PBG-D obeyed Michaelis-Menten kinetics (Vmax 249 +/- 36 nmol/mg per h, Km 8.9 +/- 1.5 microM, Hill coefficient 0.93 +/- 0.14). Addition of protoporphyrinogen yielded a sigmoidal curve with decreased Vmax. The Hill coefficient approached 4. These findings provide a rational explanation for the increased delta-aminolevulinic acid and porphobilinogen during acute attacks of VP.

Erythrocyte uroporphyrinogen decarboxylase activity in 80 unrelated patients with porphyria cutanea tarda

To estimate the prevalence of the subgroups of porphyria cutanea tarda (PCT), erythrocyte uroporphyrinogen decarboxylase (UD) activity was measured in 80 unrelated patients with PCT, and in 45 of their relatives by using pentacarboxyl-porphyrinogen III as substrate. The subgroups were differentiated by analysis of the urinary porphyrins of the patients and 119 of their relatives. Of the patients, 77.5% were found to be suffering from the sporadic form of PCT (type I PCT), and 22.5% from the familial form (type II PCT). Every patient with PCT had previously been affected by alcohol, oestrogen or some other liver-damaging factor. The relative frequency of familial PCT was higher in females (nine of 15) than in males (nine of 65), which suggests that inheritance of the gene for type II PCT may predispose to oestrogen-precipitated PCT. The onset of type II PCT occurred at a lower age than that of type I (42.6 vs. 47.0 years). The findings suggest an increased risk of precipitating factors in carriers of an inherited UD deficiency.

A case of cutaneous squamous cell carcinoma associated with sporadic porphyria cutanea tarda due to liver disorder after Schistosoma japonicum infection

A 56-year-old man suffered from cutaneous squamous cell carcinoma (cutaneous SCC) which occurred on a cutaneous lesion of sporadic porphyria cutanea tarda (sporadic PCT). His liver function decreased from the time he was infected with Schistosoma japonicum at the age of 10. He drank a little alcohol. Erythematous maculae with blisters or erosions occurred on sun-exposed areas of his skin when he was 52. His urine continued to be red. After detailed examinations including liver biopsy, he was diagnosed as having sporadic PCT due to liver disorder after infection with Schistosoma japonicum. At the age of 56, a small red papule arose on his right earlobe at the site of a sporadic PCT lesion. The papule rapidly enlarged with ulceration; this completely destroyed his right earlobe, which was covered with odoriferous yellow-white necrotic tissue. The tumor then extended to his right preauricular area with ulceration. A skin biopsy confirmed well-differentiated cutaneous SCC. The association of cutaneous SCC with sporadic PCT has not been previously reported; we think that the association is significant. Such an occurrence may have been induced by either direct or indirect effects of ultraviolet light or a scar formed by the sporadic PCT.

Mechanism of synergistic induction of hepatic heme oxygenase by glutethimide and iron: studies in cultured chick embryo liver cells

Heme oxygenase, the rate controlling enzyme for heme catabolism, is inducible by a variety of treatments, some of which induce by a heme-dependent mechanism and others by a heme-independent mechanism. This work shows that, in cultured chick embryo liver cells, synergistic induction of heme oxygenase by iron, added with the phenobarbital-like drug, glutethimide was heme-dependent. Addition of an inhibitor of heme biosynthesis abolished the synergistic induction of heme oxygenase providing evidence for the heme-dependent mechanism of induction. Glutethimide and iron appeared to induce at the transcriptional level since both heme oxygenase mRNA and protein levels correlate with changes in heme oxygenase activity.

Mechanism of iron potentiation of hepatic uroporphyria: studies in cultured chick embryo liver cells

Effects of iron were studied in cultured chick embryo liver cells to help elucidate the effect of hepatic iron in the human disease porphyria cutanea tarda and in toxic porphyria caused by chemicals. These cultures have proven useful because (a) phenobarbital and phenobarbital-like drugs induce a common form(s) of cytochrome P-450 (P-450-phenobarbital) in these cultures; (b) 20-methylcholanthrene and certain other polycyclic hydrocarbons induce a different form(s) (P-450-methylchol-anthrene), and (c) uroporphyria can be produced rapidly by exposure to suitable chemicals. In these cultures, treatment with iron alone did not produce porphyrin accumulation, and treatment with iron + 5-aminolevulinate caused accumulation of protoporphyrin, as did treatment with 5-aminolevulinate alone. However, treatment with phenobarbital-like drugs and iron, the latter at a concentration as low as 0.2 microM, led to accumulation of uro- and heptacarboxylporphyrins. Potentiation of uroporphyrin accumulation by iron began before there was a detectable synergistic increase in activity of 5-aminolevulinate synthase, the rate-controlling enzyme of heme synthesis. In contrast, treatment of cultures with 20-methylcholanthrene, in the presence or absence of iron, did not result in uroporphyrin accumulation or an increase in the activity of 5-aminolevulinate synthase. Uroporphyrinogen decarboxylase activity was unchanged by drug and iron treatments. Inhibitors of P-450-phenobarbital, SKF525A and piperonyl butoxide, as well as cadmium and cycloheximide prevented the porphyrin accumulation produced by glutethimide + iron, even though, except with cycloheximide, these substances further increased 5-aminolevulinate synthase activity. In vitro, uroporphyrin was oxidized autocatalytically by iron. In intact hepatocytes, even low concentrations of iron (0.2 to 20 microM), in the presence of a form of cytochrome P-450 induced by phenobarbital-like chemicals, produces uroporphyria primarily by enhancing uroporphyrinogen oxidation, not by inhibition of the decarboxylase. Induction of 5-aminolevulinate synthase amplifies the porphyrin overproduction.

Manifestation of familial porphyria cutanea tarda after childbirth

We report the case of a woman with hereditary porphyria cutanea tarda which manifested 3 weeks after she gave birth to her second child. The mother of the patient had also been diagnosed and treated for porphyria cutanea tarda. Reduced red cell uroporphyrinogen decarboxylase activity was found in the patient, the new-born child and the patient's mother. Normal enzyme activity was found in the patient's first child.

Hepatic heme synthesis in a new model of experimental hemochromatosis: studies in rats fed finely divided elemental iron

Rats fed chow containing finely divided elemental iron (from carbonyl-iron) develop hepatic iron overload resembling human hereditary hemochromatosis in that deposition of iron is primarily in periportal hepatocytes and with hepatic iron concentrations sufficiently high to be associated in the human disease with hepatic fibrosis or cirrhosis. In recent studies using this model, we reported changes in hepatic hemoproteins and heme oxygenase, the rate-controlling enzyme of heme breakdown. We now report effects of iron-loading on three enzymes of heme synthesis: 5-aminolevulinate synthase; the first and rate-controlling enzyme of the pathway, 5-aminolevulinate dehydrase (or porphobilinogen synthase), and uroporphyrinogen decarboxylase, the activity of which is decreased in porphyria cutanea tarda, a liver disease in which iron is known to play an important but still poorly understood role. Of the three enzymes, only activity of the dehydrase was altered by iron-loading: it was decreased significantly as early as 1 week after starting iron feeding, and with marked iron overload was 30 to 32% of control values. The degree of decrease was inversely related (r = -0.77 to -0.88) to the degree of iron overload and was partially reversed within 1 to 3 days when feeding of the iron-supplemented diet was stopped. The decrease in dehydrase activity was not attributable to lack of reduced glutathione or other disulfide-reducing agents or to zinc deficiency; nor was evidence found for inhibition by iron compounds or other possible inhibitors present in iron-loaded livers.(ABSTRACT TRUNCATED AT 250 WORDS)

Uroporphyrin accumulation produced by halogenated biphenyls in chick-embryo hepatocytes. Reversal of the accumulation by piperonyl butoxide

Cultures of chick-embryo hepatocytes were used to study the mechanism by which 3,4,3',4'-tetrachlorobiphenyl and 2,4,5,3',4'-pentabromobiphenyl cause accumulation of uroporphyrin. In a previous paper, an isoenzyme of cytochrome P-450 induced by 3-methylcholanthrene had been implicated in this process [Sinclair, Bement, Bonkovsky & Sinclair (1984) Biochem. J. 222, 737-748]. Cells treated with 3,4,3',4'-tetrachlorobiphenyl and 5-aminolaevulinate accumulated uroporphyrin and heptacarboxyporphyrin, whereas similarly treated cells accumulated protoporphyrin immediately after piperonyl butoxide was added. Piperonyl butoxide also restored haem synthesis as detected by incorporation of radioactive 5-aminolaevulinate into haem, and decrease in drug-induced 5-aminolaevulinate synthase activity. The restoration of synthesis of protoporphyrin and haem by piperonyl butoxide was not affected by addition of cycloheximide, indicating recovery was probably not due to protein synthesis de novo. Piperonyl butoxide also reversed uroporphyrin accumulation caused by 3,4,5,3',4',5'-hexachlorobiphenyl, mixtures of other halogenated biphenyls, lindane, parathion, nifedipine and verapamil. The effect of piperonyl butoxide was probably not due to inhibition of metabolism of these compounds, since the hexachlorobiphenyl was scarcely metabolized. Other methylenedioxyphenyl compounds, as well as ellipticine and acetylaminofluorene, also reversed the uroporphyrin accumulation caused by 3,4,3',4'-tetrachlorobiphenyl. SKF-525A (2-dimethylaminoethyl-2,2-diphenyl valerate) did not reverse the uroporphyrin accumulation caused by the halogenated biphenyls, but did reverse that caused by phenobarbital and propylisopropylacetamide. We conclude that the mechanism of the uroporphyrin accumulation cannot be due to covalent binding of activated metabolites of halogenated compounds to uroporphyrinogen decarboxylase.

Hereditary uroporphyrinogen-decarboxylase deficiency predisposing porphyria cutanea tarda (chronic hepatic porphyria) in females after oral contraceptive medication

Porphyria cutanea tarda (PCT) was diagnosed in 27 women aged 23-48 years (mean, 35 years) who had been under oral-hormonal-contraceptive medication for 1-18 years, in 3 women under substitutional estrogen treatment in the menopause, and in 2 men aged 65 and 76 years after estrogen treatment of prostatic carcinoma. In all patients, total urinary porphyrin excretion was elevated, with an average uro- and heptacarboxyporphyrin predominance of 88%, thus proving PCT. Of the patients, 84% showed a significant decrease of erythrocyte uroporphyrinogen-decarboxylase (UD; EC 4.1.1.37) activity to approximately 50% of control levels suggesting a hereditary predisposition for the development of a chronic hepatic porphyria. Estrogens and alcohol are capable of reducing hepatic UD activity. Women with hereditary red cell UD deficiency may be regarded as predisposed to PCT when under estrogen intake, especially in combination with the potentiating influence of alcohol and chronic liver disease. Normal erythrocyte UD values in patients with additive alcohol consumption may implicate a stronger inhibitory effect for alcohol on UD, suggesting a merely toxic form of chronic hepatic porphyria.

Immunoreactive uroporphyrinogen decarboxylase in the liver in porphyria cutanea tarda

Immunoreactive and catalytic uroporphyrinogen decarboxylase were measured in liver from 15 patients with sporadic porphyria cutanea tarda (PCT) and 4 patients with familial PCT at different stages of the disorder. In sporadic PCT, catalytic activity was lowest and immunoreactive enzyme concentration was highest when active skin lesions were present; this pattern was also seen in the one familial PCT patient who had skin lesions. During remission, the ratio of catalytic activity to immunoreactive enzyme concentration returned towards normal. Immunoreactive enzyme was increased by comparison with controls in sporadic patients with skin lesions; in familial PCT mean concentration was 59% of the overall sporadic value. In 4 sporadic patients in prolonged (4-8 years) remission (following venesection) enzyme activity and immunoreactive enzyme concentrations were normal. It is suggested that clinically overt PCT is precipitated by an iron-dependent process which inactivates the active centres of uroporphyrinogen decarboxylase molecules in the liver. Treatment by venesection eventually leads to complete reversal of this biochemical defect in at least some patients with sporadic PCT. The findings are consistent with the view that sporadic PCT is an acquired disorder.

Inhibition of uroporphyrinogen decarboxylase by halogenated biphenyls in chick hepatocyte cultures. Essential role for induction of cytochrome P-448

Uroporphyrinogen decarboxylase (EC 4.1.1.37) activity was assayed in cultures of chick-embryo hepatocytes by the changes in composition of porphyrins accumulated after addition of excess 5-aminolaevulinate. Control cells accumulated mainly protoporphyrin, whereas cells treated with 3,4,3',4'-tetrachlorobiphenyl or 2,4,5,3',4'-pentabromobiphenyl accumulated mainly uroporphyrin, indicating decreased activity of the decarboxylase. 3-Methylcholanthrene and other polycyclic-hydrocarbon inducers of the P-448 isoenzyme of cytochrome P-450, did not affect the decarboxylase in the absence of the biphenyls. Induction of P-448 was detected as an increase in ethoxyresorufin de-ethylase activity. Pretreatment of cells with methylcholanthrene decreased the time required for the halogenated biphenyls to inhibit the decarboxylase. The dose response of methylcholanthrene showed that less than 40% of the maximal induction of cytochrome P-448 was needed to produce the maximum biphenyl-mediated inhibition of the decarboxylase. In contrast, induction of the cytochrome P-450 isoenzyme by propylisopropylacetamide had no effect on the biphenyl-mediated decrease in decarboxylase activity. Use of inhibitors of the P-450 and P-448 isoenzymes (SKF-525A, piperonyl butoxide and ellipticine) supported the concept that only the P-448 isoenzyme is involved in the inhibition of the decarboxylase by the halogenated biphenyls. The effect of preinduction with methylcholanthrene to enhance inhibition of the decarboxylase was also shown by the increased rate at which porphyrin accumulated from endogenously synthesized 5-aminolaevulinate after treatment of cells with the combination of propylisopropylacetamide and the biphenyls. Antioxidants, chelators of iron, and chromate affected the decrease in decarboxylase activity only if they prevented the induced increase in cytochrome P-448. We conclude that the P-448 and not the P-450 isoenzyme of cytochrome P-450 plays an obligatory role in the inhibition of uroporphyrinogen decarboxylase caused by halogenated biphenyls.

Alcoholic liver disease

Aggressive management to prevent alcoholic cirrhosis should include the use of biopsy results to diagnose and to monitor alcoholic liver disease. Guidelines for the interpretation of the liver biopsy are highlighted. The diagnosis, course, and treatment of alcoholic hepatitis and cirrhosis are presented in detail.

Decreased activity of uroporphyrinogen decarboxylase caused by 2,4,5,3',4'-pentabromobiphenyl in chick embryo hepatocyte cultures. Difference in activity in intact or homogenized cells

Uroporphyrinogen decarboxylase activity was investigated in cultures of chick embryo liver by two different methods: (1) analysis of porphyrin composition following incubation of intact cells with delta-aminolevulinic acid; and (2) a more conventional direct enzymic assay of cell homogenates. Activity was detectibly decreased following exposure of cells to 100 ng/ml 2,4,5,3',4'-pentabromobiphenyl using the first method, but not the second. This decrease in activity was reversed by homogenizing the cells treated with 100 ng/ml pentabromobiphenyl. It is concluded that the direct homogenate assay of the enzyme may miss or underestimate decreases in its in vivo activity.