Uroporphyrin I stimulation of collagen biosynthesis in human skin fibroblasts. A unique dark effect of porphyrin

Forearm porphyrin levels evaluated by digital imaging system are increased in patients with systemic sclerosis compared with patients in pre-clinical stage

We hypothesized that changes in skin characteristics on the forearm could be useful for early diagnosis of systemic sclerosis (SSc). We used VISIA digital imaging system to investigate this possibility for the first time. Twenty-eight Japanese patients who were diagnosed with typical or very early diagnosis of SSc (VEDOSS) were enrolled in this study, and ten age- and gender-matched patients with other disorders were included as a control group. Eight skin characteristics were analyzed. Our method of evaluating forearm skin characteristics was shown to be reproducible. The scores of WRINKLES, TEXTURE, PORES, and PORPHYRINS were higher in SSc subjects with sclerotic forearm skin (SSc forearm+; 11.004, 5.116, 3.230, and 0.084, respectively) and those without (SSc forearm-: 11.915, 4.898, 2.624, 0.0616, respectively) than in the non-SSc control subjects (10.075, 4.496, 2.459, 0.0223, respectively). Also, the scores of SPOTS, TEXTURE, PORES, UV SPOTS, BROWN SPOTS, and PORPHYRINS were elevated in SSc forearm+ (3.182, 5.116, 3.230, 5.761, 6.704, 0.084, respectively) and SSc forearm- patients (2.391, 4.898, 2.624, 9.835, 5.798, 0.0616, respectively) compared with those with VEDOSS (2.362, 4.738, 2.234, 5.999, 4.898, 0.0169, respectively). We found statistical significance in the difference in score of PORPHYRINS between SSc forearm- and VEDOSS groups (p = 0.044), and between SSc forearm+ and VEDOSS groups (p = 0.012). Therefore, they can be used to differentiate VEDOSS from early or mild SSc cases, which is sometimes clinically problematic. Our study also suggests that the porphyrin research will lead to a better understanding of SSc pathogenesis.

Clinical and Histopathological Features of Scleroderma-like Disorders: An Update

Scleroderma-like disorders include a set of entities involving cutis, subcutis and, sometimes, even muscular tissue, caused by several pathogenetic mechanisms responsible for different clinical–pathological pictures. The absence of antinuclear antibodies (ANA), Raynaud’s phenomenon and capillaroscopic anomalies constitutes an important element of differential diagnosis with systemic sclerosis. When scleroderma can be excluded, on the basis of the main body sites, clinical evolution, any associated pathological conditions and specific histological features, it is possible to make a correct diagnosis.

Acitretin mitigates uroporphyrin-induced bone defects in congenital erythropoietic porphyria models

Congenital erythropoietic porphyria (CEP) is a rare genetic disorder leading to accumulation of uro/coproporphyrin-I in tissues due to inhibition of uroporphyrinogen-III synthase. Clinical manifestations of CEP include bone fragility, severe photosensitivity and photomutilation. Currently there is no specific treatment for CEP, except bone marrow transplantation, and there is an unmet need for treating this orphan disease. Fluorescent porphyrins cause protein aggregation, which led us to hypothesize that uroporphyrin-I accumulation leads to protein aggregation and CEP-related bone phenotype. We developed a zebrafish model that phenocopies features of CEP. As in human patients, uroporphyrin-I accumulated in the bones of zebrafish, leading to impaired bone development. Furthermore, in an osteoblast-like cell line, uroporphyrin-I decreased mineralization, aggregated bone matrix proteins, activated endoplasmic reticulum stress and disrupted autophagy. Using high-throughput drug screening, we identified acitretin, a second-generation retinoid, and showed that it reduced uroporphyrin-I accumulation and its deleterious effects on bones. Our findings provide a new CEP experimental model and a potential repurposed therapeutic.

Porphyria cutanea tarda: Recent update

Porphyria cutanea tarda (PCT) is the most common human porphyria, due to hepatic deficiency of uroporphyrinogen decarboxylase (UROD), which is acquired in the presence of iron overload and various susceptibility factors, such as alcohol abuse, smoking, hepatitis C virus (HCV) infection, HIV infection, iron overload with HFE gene mutations, use of estrogens, and UROD mutation. Patients with familial or type II PCT due to autosomal dominant UROD mutation also require other susceptibility factors, as the disease phenotype requires hepatic UROD deficiency to below 20% of normal. PCT clinically manifests with increased skin fragility and blistering skin lesions on sun exposed areas. The common age of presentation is 5th to 6th decade and occurs slightly more commonly in males. Although mild liver biochemical profile are common, advanced fibrosis and cirrhosis with hepatocellular carcinoma (HCC) can occasionally develop. Screening for HCC using ultrasound examination is recommended in PCT patients, especially with cirrhosis and advanced fibrosis. PCT is effectively and readily treatable with the use of either repeated phlebotomy or use of 100 mg hydroxychloroquine orally twice a week, and both the treatments are equally effective and safe. With the advent of new or direct antiviral agents for HCV infection, treatment of concomitant HCV has become safer and effective. Data are emerging on the benefit of these drugs as monotherapy for both PCT and HCV. After the achievement of remission of PCT, there remains a potential for relapse, especially when the susceptibility factors are not adequately controlled. Scanty data from retrospective and observational studies shows the relapse rate to be somewhat higher after remission with low-dose hydroxychloroquine as compared to phlebotomy induced remission. Future studies are needed on exploring mechanism of action of 4-aminoquinolines, understanding interaction of HCV and PCT, and relapse of PCT on long-term follow-up.

[Sclerodermatous changes revealing porphyria cutanea tarda]

BACKGROUND

Porphyria cutanea tarda (PCT) is associated with cutaneous accumulation of porphyrins. This accumulation results from a deficiency of uroporphyrinogen decarboxylase occurring only in the liver. The classical presentation is blistering on sun-exposed areas.

PATIENTS AND METHODS

A 59-year-old woman presented at the dermatology consultation for sclerotic lesions that had been present for one year. The remainder of the clinical examination and further investigations did not indicate systemic scleroderma. The sun-exposed nature of the lesions led us to perform an assay of urinary porphyrin, which was found to be elevated. Uroporphyrinogen decarboxylase levels were normal, confirming the diagnosis of type 1 PCT. Screening for a hepatic etiology revealed a heterozygous mutation H63D/C282Y of the hemochromatosis gene responsible for this clinical picture. The patient underwent regular bleeding, which led to complete disappearance of cutaneous sclerosis.

DISCUSSION

Sclerodermatous lesions are an unusual presentation of PCT and cause delays in diagnosis. The accumulation of uroporphyrins in the dermis stimulates fibroblasts, which then synthesize collagen, resulting in cutaneous sclerosis.

[Porphyria cutanea tara]

Porphyria cutanea tara (PCT) has a prevelance of about 40 new diagnoses per 1 million people per year and is the most frequently occurring type of porphyria worldwide. Inhibition of the uroporphyrinogen decarboxylase (UROD) is the main cause of the disease, which can be the result of a heterozygous or homozygous mutation of the UROD gene; however, xenobiotics or other diseases may play an important role for the precipitation of the disease. Risk factors include alcohol, estrogen, iron overload, and hemochromatosis, hepatitis C or poisoning, e.g., with polyhalogenated aromatic compounds such as hexachlorobenzene. Signs and symptoms are blisters, skin fragility, erosions hyperpigmentation, sclerodermoid plaques. Therapy includes sun protection, prevention of risk factors, phlebotomy, and chloroquine.

[Porphyria cutanea tarda in a child undergoing bone marrow grafting]

BACKGROUND

Porphyria cutanea tarda (PCT) is rare in childhood and association with bone marrow transplant has occasionally been reported.

PATIENTS AND METHODS

A 13-year-old boy was referred to our department for bullous lesions on sun-exposed areas. His past medical history revealed acute biphenotypic leukaemia with complete remission after allogeneic hematopoietic stem cell transplantation (unrelated donor). Complications of bone marrow transplant comprised anaemia (treated by blood transfusions), primary cytomegalovirus (CMV) infection, pulmonary aspergillosis and acute digestive graft-versus-host disease. The diagnosis of type I sporadic PCT was based on high levels of porphyria and normal erythrocytic uroporphyrinogen decarboxylase activity. The bullous lesions disappeared on bleeding, but the patient subsequently developed sclerodermiform lesions.

DISCUSSION

An association between PCT and bone marrow transplant has been reported previously in two independent cases, of which one involved a child. The causative role of bone marrow transplantation in the development of PCT could be related to several triggering factors: primary CMV infection, hepatotoxic drugs, blood transfusion and possible chronic hepatic graft-versus-host disease.

CONCLUSION

We report the second case in a child of type I PCT associated with bone marrow transplantation. This new case reinforces the hypothesis of a non-random relationship between the two conditions.

Severe radiation therapy-related soft tissue toxicity in a patient with porphyria cutanea tarda: a literature review

BACKGROUND

Some porphyrias are associated with cutaneous phototoxicity due to photoactivation of porphyrins, but whether ionizing radiation can have an additive effect is not clear. We report a case of severe radiation therapy-related toxicity in a patient with porphyria cutanea tarda and review the literature.

METHODS

A 50-year-old man with porphyria cutanea was treated for lower lip squamous cell carcinoma with definitive radiation therapy. During radiation therapy, acute toxicity was of an expected onset and severity. Six months after treatment completion, he developed skin hypopigmentation, soft tissue fibrosis, and areas of painful denuded skin and crusting within the previous treatment field.

RESULTS

Reports of 7 patients with porphyria receiving radiation therapy to at least 9 separate sites were reviewed, with only 1 previous report suggestive of increased radiation therapy-related toxicity.

CONCLUSION

Based on this and 1 other report, caution is warranted when considering radiation therapy in patients with active porphyria.

Mast cells and transforming growth factor-beta expression: a possible relationship in the development of porphyria cutanea tarda skin lesions

BACKGROUND

Porphyria cutanea tarda (PCT) is a metabolic disease characterized by vesicles and blisters in sun-exposed areas and scleroderma-like lesions in sun-exposed and non-sun-exposed areas. Mast cells participate in the pathogenesis of bullous diseases and diseases that show sclerosis, including PCT. Moreover, transforming growth factor-beta (TGF-beta) is the main cytokine in the development of tissue sclerosis. The correlation of mast cells and TGF-beta with the lesions of PCT has not been examined, however. The possible role of mast cells and TGF-beta (and the relationship between them) in the development of PCT lesions is discussed.

METHODS

To quantify mast cells and cells expressing TGF-beta in skin samples from patients with PCT and controls, immunohistochemical studies were performed in tissue sections allied to morphometric analyses.

RESULTS

The numbers of mast cells and cells expressing TGF-beta per square millimeter were increased in the PCT group relative to controls, and there was a direct and significant correlation between the mast cell number and cells expressing TGF-beta in PCT.

CONCLUSIONS

The results suggest that the increased number of mast cells and of cells expressing TGF-beta, as well as their direct correlation, may contribute to the pathogenesis of the skin lesions in PCT.

Porfiria cutânea tardia

Trata-se de revisão sobre a porfiria cutânea tardia em que são abordados a fisiopatogenia, as características clínicas, as doenças associadas, os fatores desencadeantes, a bioquímica, a histopatologia, a microscopia eletrônica, a microscopia de imunofluorescência e o tratamento da doença.

Hochdosierte Vitamingabe zur Verhinderung einer Porphyria cutanea urämica?

50 Patients with chronic renal failure undergoing hemodialysis with or without porphyria cutanea tarda (PCT)-like skin changes were investigated. The total porphyrin amount in erythrocytes, plasma and dialysate and the distribution of porphyrin metabolites in plasma and dialysate were measured. In plasma, the group of patients with skin changes (referred as PCU = porphyria cutanea uremica) showed significantly increased uroporphyrin levels as compared to the non-symptomatic group. In addition, significant differences concerning the ratio uro-/coproporphyrin in plasma were shown: non-symptomatic patients with 0.87, as opposed to the PCU group with 3.7. Considerable differences between the level of vitamin ingestion were identified between the groups. Patients with PCU took distinctly less vitamins C, E and B than patients without symptoms.

[Pansclerotic porphyria cutanea tarda after chronic exposure to organic solvents]

A 63 year old man developed generalized scleroderma with massive sclerotic areas, particularly in the abdominal region, four years after being diagnosed with porphyria cutanea tarda (PCT). He had almost daily exposure to organic solvents (benzene, trichlorethylene) for many years. The cutaneous fibrosis progressed dramatically leading to a pansclerosis, even though the uroporphyrin levels were borderline and the liver enzyme values were normal. Organic solvents are among those substances which can cause a cutaneous fibrosis. The unusually complicated clinical development in our patient was a combination of the two initial factors, the PCT and the long term exposure to organic solvents. The pansclerotic PCT was differentiated from a systemic sclerosis, a disabling pansclerotic morphea and a generalized morphea by means of histological examinations, the absence of a Raynaud phenomenon and the non-involvement of additional organs. Auto-antibodies typical for systemic sclerosis were negative. Using a medium dosage of UVA1 phototherapy and intensive physiotherapy, the progression of the skin disease was stopped and the sclerosis improved.

The photodynamic and non-photodynamic actions of porphyrins

Porphyrias are a family of inherited diseases, each associated with a partial defect in one of the enzymes of the heme biosynthetic pathway. In six of the eight porphyrias described, the main clinical manifestation is skin photosensitivity brought about by the action of light on porphyrins, which are deposited in the upper epidermal layer of the skin. Porphyrins absorb light energy intensively in the UV region, and to a lesser extent in the long visible bands, resulting in transitions to excited electronic states. The excited porphyrin may react directly with biological structures (type I reactions) or with molecular oxygen, generating excited singlet oxygen (type II reactions). Besides this well-known photodynamic action of porphyrins, a novel light-independent effect of porphyrins has been described. Irradiation of enzymes in the presence of porphyrins mainly induces type I reactions, although type II reactions could also occur, further increasing the direct non-photodynamic effect of porphyrins on proteins and macro-molecules. Conformational changes of protein structure are induced by porphyrins in the dark or under UV light, resulting in reduced enzyme activity and increased proteolytic susceptibility. The effect of porphyrins depends not only on their physico-chemical properties but also on the specific site on the protein on which they act. Porphyrin action alters the functionality of the enzymes of the heme biosynthetic pathway exacerbating the metabolic deficiencies in porphyrias. Light energy absorption by porphyrins results in the generation of oxygen reactive species, overcoming the protective cellular mechanisms and leading to molecular, cell and tissue damage, thus amplifying the porphyric picture.

Scarring alopecia and sclerodermatous changes of the scalp in a patient with hepatitis C infection

Hepatitis C virus (HCV) is a common cause of chronic hepatitis and is frequently associated with extrahepatic disease. Recently, cutaneous disorders have been a presenting manifestation of HCV infection. Porphyria cutanea tarda (PCT) is one of the cutaneous diseases associated with hepatitis C. PCT manifests in an acute form with tense bullae and erosions and in a chronic form with milia, scarring, and sclerodermatous changes. HCV has also been implicated as a cause of vasculitis through immune complex deposition. We report a patient in whom HCV was associated with sclerodermoid PCT and a medium vessel vasculitis. This case underscores the importance of HCV and its potential cutaneous manifestations, as well as the importance of recognizing cutaneous manifestations of internal disease that may be the first clue to diagnosis of HCV.

Erythropoietic protoporphyria treated with narrow-band (TL-01) UVB phototherapy

Erythropoietic protoporphyria is a rare photodermatosis for which treatment options are limited. The present report describes the clinical features of a patient with erythropoietic protoporphyria and liver function test abnormalities associated with treatment with beta-carotene. Subsequent treatment with narrow-band UVB phototherapy resulted in marked subjective improvement in photosensitivity, which was confirmed by abolition of demonstrated abnormalities on monochromator phototesting. The therapeutic options for photosensitivity in erythropoietic protoporphyria are reviewed and discussed.

Coexistence of lupus erythematosus and porphyria cutanea tarda in fifteen patients

BACKGROUND

Lupus erythematosus (LE) and porphyria cutanea tarda (PCT) may have similar clinical presentations, and their coexistence presents special problems in diagnosis and management.

OBJECTIVE

The purposes of this study were to describe a patient with discoid LE and PCT and to present a review of 15 patients with coexistent LE (all variants) and PCT.

METHODS

The medical records of all patients with coexistent LE and PCT seen between 1976 and 1995 were retrospectively reviewed.

RESULTS

Of 6179 cases of LE and 676 cases of porphyria (all variants), there were 15 patients, 6 men and 9 women, with coexistent LE and PCT. The mean age at diagnosis of LE was 42.8 years and of PCT was 48 years. Nine patients had discoid LE; five patients had systemic LE, and one patient had subacute cutaneous LE. The initial diagnosis was LE in eight patients, PCT in five patients, and simultaneous LE and PCT in two patients. Precipitating factors for PCT included alcohol in seven patients, iron overload in one patient, and estrogen in one patient. Treatment of LE with hydroxychloroquine 200 mg daily precipitated PCT in two patients. Patients were treated with phlebotomy or low-dose antimalarials for PCT. Patients with systemic LE received systemic glucocorticoid therapy. Patients with discoid LE and subacute cutaneous LE were treated with topical glucocorticoids.

CONCLUSION

The association of LE and PCT poses therapeutic challenges. The preferred treatment for one may exacerbate the other. Use of standard dose antimalarials for LE is inadvisable, and phlebotomy or low-dose antimalarials should be used cautiously in patients with coexistent disease.

Porphyrin-induced protein structural alterations of heme enzymes

Some alterations in the protein structure of delta-aminolevulinic acid dehydratase (ALA-D) and porphobilinogen deaminase (PBG-D) induced by uroporphyrin (URO) and prototoporphyrin (PROTO) have been observed previously. To obtain further evidence of these phenomena, the absorption and fluorescence spectra of ALA-D and PBG-D and the total protein content of sulfhydryl and free amino groups were analyzed after exposure of the enzymes to URO I and PROTO IX, ALA-D and PBG-D were partially purified from bovine liver and exposed to URO I or PROTO IX, both in the dark and under UV light. All experiments were performed in the enzyme solutions after removing the porphyrins. Absorbance spectra changes in the region of 220-300 nm were registered, indicating the interaction of the porphyrins with the molecular structure of the enzymes. The main changes in the fluorescence spectra were observed in the spectral region of 555 nm, and only slight modifications in the spectral region of 340-360 nm; moreover, alterations were stronger upon UV irradiation and in the presence of URO I when compared with darkness and PROTO IX. Variations in total SH groups would suggest the formation of disulfur bridges induced by URO I and the rupture of some S-S groups induced by PROTO IX. The effect of porphyrins on free amino groups would reflect a combination of cross-linking and fragmentation of proteins. Structural changes were observed when the enzymes were exposed to the porphyrin both in the dark or under UV light; however, they were stronger in the latter condition. These results suggest that porphyrins per se could act directly on the protein structure and that this action would be enhanced upon UV irradiation.

Folding and unfolding of delta-aminolevulinic acid dehydratase and porphobilinogen deaminase induced by uro- and protoporphyrin

In all the cutaneous porphyrias, alterations in the heme pathway lead to an excessive production and accumulation of porphyrins. Absorption of light energy by circulating porphyrins induces reactive oxygen species generation, which provoke enzyme inactivation and protein structure changes. Protein structure alterations induced by porphyrins with different physico-chemical properties on delta-aminolevulinic acid dehydratase (ALA-D) and porphobilinogen deaminase (PBG-D) were examined. The action of uroporphyrin (URO), a highly hydrophilic porphyrin, and protoporphyrin (PROTO), most hydrophobic, was tested. ALA-D and PBG-D were partially purified from bovine liver and exposed to URO or PROTO, both in the dark and under UV light. All experiments were performed in solution after removing the porphyrins. Treatment with 10 microM URO I or 10 microM PROTO IX reduced the activity of ALA-D and PBG-D. This effect increased with increasing time of exposure to porphyrins. Solubility of the enzymes in buffer containing 3 M KCl decreased with increasing time of porphyrin treatment; this may be because of exposure of hydrophobic residues that are normally shielded in the native protein structure. Tryptic digestion of ALA-D and PBG-D exposed to URO I or PROTO IX resulted in an increase of protein degradation products, indicating an enhanced susceptibility to proteolysis. Fluorescence emission of several enzymes aminoacids was greatly modified. The structural changes described were observed when the enzymes were exposed to porphyrins both in the dark or under UV light. However, they were more noticeable with UV light. These results suggest that porphyrins per se can act directly on protein structure and that this action may be enhanced by UV irradiation.

Photosensitization of uroporphyrin augments the ultraviolet A-induced synthesis of matrix metalloproteinases in human dermal fibroblasts

Porphyria cutanea tarda is characterized by severe connective tissue damage in sun-exposed skin. The regulated synthesis and degradation of the extracellular matrix by various matrix metalloproteinases (MMPs) determine its amount and composition within the skin. In this study, we therefore asked whether long-wave ultraviolet irradiation (340-450 nm) in conjunction with uroporphyrin I could modulate the synthesis of MMPs with substrate specificities for dermal (collagens I, III, V; proteoglycans) and basement membrane components (collagens IV, VII; fibronectin; laminin) and whether synthesis of the counteracting tissue inhibitor of metalloproteinases is also affected. After irradiation of uroporphyrin-pretreated fibroblasts, specific mRNAs of MMP-1 and MMP-3 increased concomitantly up to 2.7-fold compared with ultraviolet-irradiated cells and up to 10-fold compared with mock-irradiated or uroporphyrin I-treated controls. In contrast, mRNA levels of tissue inhibitor of metalloproteinases remained unaltered. Similar results were obtained by immunoprecipitation. Gelatin and casein zymography revealed increased proteolytic activity of MMP-2 and MMP-3 in blister fluids of patients with porphyria cutanea tarda, indicating that similar events may occur in vivo. Using deuterium oxide as enhancer and sodium azide as quencher of singlet oxygen, we could increase or reduce MMP synthesis, suggesting that singlet oxygen is the major intermediate in the upregulation of MMPs after irradiation of uroporphyrin-pretreated fibroblasts. Taken together, our results show that ultraviolet irradiation alone, and to a greater extent in conjunction with uroporphyrin I, results in an unbalanced synthesis of MMPs that may contribute to the destruction of the dermis and basement membrane, leading to blistering and accelerated photoaging in porphyria cutanea tarda patients.

Homozygous variegate porphyria: an evolving clinical syndrome

Variegate porphyria is one of the most frequently encountered genetic conditions in South Africa. It is inherited as an autosomal dominant disease and in excess of 300 heterozygous cases have been studied by the Cape Town unit. Despite this, the homozygous condition has not previously been encountered in South Africa. We report two cases of homozygous variegate porphyria, one of whom represents the first South African case. We delineate a syndrome principally characterized by growth retardation, developmental delay, epileptic seizures, photosensitivity and an abnormal porphyrin excretion pattern. In addition we describe, in one case, two features not previously reported: skin disease in areas unexposed to light and a severe sensory neuropathy which may account at least in part for the hand deformities of this disorder.

Generalized morphoea secondary to porphyria cutanea tarda

We report a patient with generalized morphoea secondary to porphyria cutanea tarda, who responded to treatment with cyclosporin. The differences between the sclerodermatous skin changes seen in porphyria cutanea tarda and generalized morphoea are discussed.

Mechanisms of photosensitivity in porphyric patients with special emphasis on erythropoietic protoporphyria

In erythropoietic protoporphyria, protoporphyrin overproduction occurs mainly in erythroid tissue. Protoporphyrin can be released from erythrocytes in the dark, but the release is greatly increased if the erythrocytes are exposed to small amounts of light. Protoporphyrin can be bound in plasma either to albumin or to low density or high density lipoprotein. The cutaneous symptoms in erythropoietic protoporphyria are primarily elicited by protoporphyrin-sensitized photodamage of endothelial cells due to the presence of protoporphyrin in lipid structures. Which structures are damaged first in endothelial cells is unknown. Endothelial cells probably accumulate protoporphyrin from albumin or lipoproteins present in the plasma. A direct transfer from the erythrocyte membrane to the endothelial cell membrane can also occur. The transfer processes are probably facilitated by light exposure. Degranulation of mast cells, invasion of neutrophils into interstitial tissue and complement activation seem to be of less importance than endothelial cell injury in the pathogenesis of erythropoietic protoporphyria. These processes may, however, participate in the final expression of the cutaneous symptoms. Uroporphyrin and coproporphyrin are hydrophilic and are probably unbound in plasma, although weak binding to plasma proteins cannot be excluded. In the hepatic porphyrias and in erythropoietic porphyria, the clinical symptoms are probably evoked by uroporphyrin and coproporphyrin present in the interstitial tissue. Very little is known about the primary targets of uroporphyrin and coproporphyrin photodamage in these disorders, but photodamage to intercellular structures probably represents the initial event. Activation of complement may contribute to the final expression of the cutaneous symptoms.

Further evidence on the photodynamic and the novel non-photodynamic inactivation of uroporphyrinogen decarboxylase by uroporphyrin I

The action of uroporphyrin I (URO I) on the activity of red cell uroporphyrinogen decarboxylase (URO-D) in the dark and under UV light was studied. Light-dependent-and light-independent inactivation was observed. Both effects increased at increasing concentrations of URO I, the former reached its maximum at 150 microM of sensitizer. At 100 microM of URO I, both light and dark inactivation were temperature dependent amounting to about 50% at 30-37 degrees C. The velocity of dark inactivation increased with increasing temperature in the range of 0 to 45 degrees C. Photoinactivation can be ascribed to primary oxidation of essential amino acids, very likely histidyl residues, followed by secondary inter or intrapeptide cross-linking. Dark inactivation could be the result of both oxidation and cross-linking (although to a less degree than that produced by light) and also direct inhibition of the enzyme by induced conformational changes at its active site through binding of the porphyrin to the protein. When the action of URO I was tested on partially purified URO-D, the enzyme appeared to be more susceptible to the dark than to the light effect.

Photodynamic and non-photodynamic action of several porphyrins on the activity of some heme-enzymes

The action of porphyrins, uroporphyrin I and III (URO I and URO III), pentacarboxylic porphyrin I (PENTA I), coproporphyrin I and III (COPRO I and COPRO III), protoporphyrin IX (PROTO IX) and mesoporphyrin (MESO), on the activity of human erythrocytes delta-aminolevulinic acid dehydratase, porphobilinogenase, deaminase and uroporphyrinogen decarboxylase in the dark and under UV light was investigated. Both photoinactivation and light-independent inactivation was found in all four enzymes using URO I as sensitizer. URO III had a similar action as URO I on porphobilinogenase and deaminase and PROTO IX exerted equal effect as URO I on delta-aminolevulinic acid dehydratase and uroporphyrinogen decarboxylase. Photodynamic efficiency of the porphyrins was dependent on their molecular structure. Selective photodecomposition of enzymes by URO I, greater specificity of tumor uptake by URO I and enhanced porphyrin synthesis by tumors from delta-aminolevulic acid, with predominant formation of URO I, underline the possibility of using URO I in detection of malignant cells and photodynamic therapy.

Porphyria cutanea tarda with cutaneous "scleroderma" and calcification

An unusual case of porphria cutanea tarda (PCT) with sclerodermoid changes is reported. This case is remarkable for the extent of sclerodermoid changes and the presence of gross dystrophic calcification and ulceration in the sclerotic areas. The pathogenesis of this condition is discussed.

Radiological features in congenital erythropoietic porphyria (Gunther's disease). Report of 3 cases

Gunther's disease or congenital erythropoietic porphyria is a rare and severe disorder comprising cutaneous and haemolytic symptoms. Photocutaneous lesions are responsible for scleroderma-like calcifications and deformities of the extremities visible on X-rays. Hemolytic manifestations lead to diffuse major osteopenia. Soft tissue calcifications of the fingers can be seen even in young patients. One case reported here is the first illustration of intracranial calcifications located on dura-mater and calvarium.

Differential effects of protoporphyrin and uroporphyrin on murine mast cells

To investigate the mechanisms responsible for the distinct cutaneous manifestations of erythropoietic protoporphyria and porphyria cutanea tarda, the effects of protoporphyrin (PP) and uroporphyrin (URO), the predominant porphyrins in the respective disease, on mast cells were examined. Release of preformed and generated mediators was assessed by the release of radioactivity from cells labeled with [3H]serotonin and [14C]arachidonic acid, respectively. Clinically relevant doses of PP (25-500 ng/ml) and 396-407 nm irradiation (3-16 X 10(2)J/m2) induced maximal net release of preformed mediators of 44.52 +/- 6.6 to 58.01 +/- 4.0% (mean +/- SE). In contrast, irradiation in the presence of URO (50-5000 ng/ml) resulted in less than 5% net release. [3H]Serotonin release induced by PP and irradiation was calcium-independent, and was not enhanced by phorbol 12-myristate 13-acetate, a known activator of protein kinase C. This release was suppressed by catalase, a scavenger of hydrogen peroxide. Furthermore, irradiation in the presence of PP, but not in the presence of URO, resulted in perturbation of cell membrane. Irradiation in the presence of PP also resulted in a maximal net release of generated mediators of 9.98 +/- 3.5% (mean +/- SE), whereas similar treatment in the presence of URO induced less than 0.5% net release. These results suggested that the burning, stinging, erythema, and edema experienced by patients with erythropoietic protoporphyria following sun exposure, and the lack of such findings in patients with porphyria cutanea tarda, may be explained, at least in part, by the differential effects of PP and URO on mast cells.

Retinoic acid induces cyclic changes in epidermal thickness and dermal collagen and glycosaminoglycan biosynthesis rates

The effects of daily topical application onto guinea pig ears of a therapeutic concentration of all trans-retinoic acid (RA) on epidermal thickness and dermal collagen and glycosaminoglycan (GAG) biosynthesis rates were studied during a 40-day period. Clinically, the RA-treated skin became erythematous and scaly beginning at 5-6 days, conditions which persisted throughout the experiment. The epidermis became thickened and hyperplastic with marked psoriasi-form histologic features, and the phenomenon was dependent on RA concentration. The initial hyperplasia resulted from a transient 4-fold increase in epidermal basal cell replication during the first 3-4 days, as shown by the rise and fall of [3H]thymidine labeling index which preceded the hyperplasia. The extent of epidermal hyperplasia as measured by epidermal thickness was not constant throughout the 40-day treatment period, but exhibited maxima on days 11, 25, and 36. These maxima were followed by periods of decreased thickness, although the minima were always greater than the untreated controls. Retinoic acid induced similar temporal cycles in GAG and collagen biosynthesis rates, but the collagen cycles occurred at different times with maxima on days 6, 20, and 34. After 8 weeks' treatment, the blood flow rates in the ear microcirculation (laser Doppler photometry) were increased 81% above that of the water-treated controls. The demonstration of these RA-induced cyclic changes in epidermal hyperplasia and dermal fibroblast biosynthetic activities have revealed the presence of control mechanisms in these tissues which normally operate to maintain tissue homeostasis.

Sclerodermoid changes of porphyria cutanea tarda: possible relationship to urinary uroporphyrin levels

From 1950 to 1982, fifteen patients were seen at the Mayo Clinic with a diagnosis of sclerodermoid changes of porphyria cutanea tarda. Fourteen patients had changes similar to scleroderma limited to the skin, and one patient had scleroderma-like skin changes accompanied by visceral abnormalities. Both light-exposed and unexposed areas of the body were affected. Areas of involvement included the chest, the V-shaped area of the neck, and the back, face, and shoulders. In six patients, morpheaform changes represented the presenting cutaneous sign of porphyria cutanea tarda. Follow-up examination, after treatment that included abstinence from alcohol and phlebotomy, revealed that the sclerodermoid skin changes had disappeared in six patients and improved in four. Generally, the degree of improvement of the sclerodermoid changes was proportional to the reduction of the urinary uroporphyrin levels toward normal (p = 0.02).