How genetic defects are identified

The use of i.v. IG therapy in dermatology

The intravenous administration of exogenous pooled human immunoglobulin (i.v. IG) was originally licensed as antibody replacement therapy in patients with primary immunodeficiencies and there are currently six FDA-approved uses for this agent. Despite a current lack of FDA approval, off-label treatment of a multitude of dermatologic disorders with i.v. IG has shown exciting potential for this unique treatment modality. The diseases successfully treated with i.v. IG include autoimmune bullous diseases, connective tissue diseases, vasculitides, toxic epidermal necrolysis, and infectious disorders (such as streptococcal toxic shock syndrome). Currently the biggest drawback in the consideration of i.v. IG therapy in dermatologic disorders is the lack of randomized controlled trials. Nevertheless, there is a significant body of evidence demonstrating the efficacy of i.v. IG in patients with dermatologic disorders that are resistant to treatment with standard agents. In summary, i.v. IG constitutes a valuable and potentially life-saving agent in managing patients with a variety of dermatologic disorders under the appropriate circumstances.

Methotrexate vs. ciclosporin in psoriasis: effectiveness, quality of life and safety. A randomized controlled trial

BACKGROUND

When this study was initiated, no previous studies comparing methotrexate and ciclosporin for moderate to severe plaque psoriasis had been performed.

OBJECTIVES

To compare the effectiveness, quality of life and side-effects of methotrexate and ciclosporin treatments in a context reflecting normal clinical practice.

METHODS

Eighty-four patients with moderate to severe plaque psoriasis were randomized to treatment with methotrexate or ciclosporin for 12 weeks. The primary outcome was the Psoriasis Area and Severity Index (PASI). The secondary outcome was quality of life, measured by the Dermatology Life Quality Index (DLQI) and the 36-item Short Form Health Survey (SF-36). A visual analogue scale (VAS) was used for patients' assessment.

RESULTS

Sixty-eight patients started treatment and were included in the analysis. Dropout before initiation of treatment was higher in the ciclosporin group. Mean PASI change from baseline at 12 weeks was 58% in the methotrexate group and 72% in the ciclosporin group, showing ciclosporin to be more effective than methotrexate. Improvement of the VAS score was higher in the ciclosporin group. The methotrexate group showed a greater improvement in the subscale Physical Functioning of the SF-36. No significant difference between the groups was found for DLQI.

CONCLUSIONS

Treatment with methotrexate or ciclosporin for chronic plaque psoriasis brings satisfactory disease control, improved quality of life and tolerable side-effects. A statistically significant difference in effectiveness between treatment groups was recorded, showing ciclosporin to be more effective than methotrexate in a short-term perspective.

Blistering disorders: diagnosis and treatment

Blistering diseases are a heterogeneous group of disorders that can affect either skin and mucous membrane, or both, varying in presentation, clinical course, pathohistology, immunopathology and treatment. Not infrequently the diagnosis is delayed. This can result in severe, and sometimes fatal consequences. Although these diseases are rare, it is very important to make an accurate diagnosis based on a combination of clinical profile and laboratory observations. A brief review is presented of the following bullous diseases: pemphigus, paraneoplastic pemphigus, bullous pemphigoid, cicatricial pemphigoid, epidermolysis bullosa acquisita, dermatitis herpetiformis, linear IgA bullous disease, porphyria cutanea tarda, and subcorneal pustular dermatitis. Their clinical, pathohistologic and immunopathologic features and recommendations for therapy are discussed.

Diagnosis and treatment of the hepatic porphyrias

Porphyrias are a peculiar group of diseases resulting from hereditary or acquired partial deficiencies in seven of the eight enzymes in the biosynthetic pathway of heme. Biosynthesis of heme takes place in the erythropoietic system or in the hepatic tissue. Depending on the main location of the enzyme defect, porphyrias can be classified as erythropoietic or hepatic. There are seven basic clinical forms of porphyria related to a deficiency of each of the involved enzymes. Clinical manifestations in porphyria may be neurovisceral or cutaneous. Patients may present with acute attacks (acute porphyrias), cutaneous lesions (cutaneous porphyrias), or both (mixed porphyrias). Study of patients supected of having porphyria should include several steps: 1) clinical evaluation, 2) biochemical study, which enables us to classify the patient to a specific form of porphyria, followed if possible by 3) enzymatic assay(s), and 4) genetic studies to confirm an enzyme deficiency and its level and the causal genetic mutation. Unfortunately no curative treatment is available for any of the porphyrias. However, symptomatic treatments are available and are discussed in this article.

Cyclosporin: applications in small animal dermatology

Cyclosporin has been increasingly used for the treatment of skin diseases in small animals. Reported uses include the treatment of atopy, cutaneous lupus erythematosus, feline acquired alopecia resembling pseudopelade of humans, pemphigus erythematosus, pemphigus foliaceus, perianal fistulae and sebaceous adenitis. In addition, cyclosporin has been used anecdotally for several other skin diseases. Few side effects have been noted at doses therapeutic for dermatologic diseases. Current suggestions for monitoring, and the value of trough cyclosporin serum concentrations for prediction of toxicity and efficacy are discussed.

Porphyrins, porphyrin metabolism and porphyrias. I. Update

The biosynthesis of porphyrins is one of the most conserved parthways known, about the same sequence of reactions taking place in all species. By associating different metals, porphyrins give rise to the "pigments of life": chlorophyll, haem and cobalamin. The unique tetrapyrrolic structure enables it to function in an array of reactions as a single electron carrier and as a catalyst for redox reactions. In this capacity, it constitutes the prosthetic group of enzymes participating in cellular respiration, in conversion reactions involving steroids and lipophilic xenobiotics, in protective mechanisms directed against oxidative stress and in pathways providing central messenger molecules. The formation of haem is accomplished by a sequence of eight dedicated enzymes encoded by different genes, some being active in ubiquitous as well as in erythroid isoforms. Large differences between the participating enzymes with regard to catalytic power, with low capacity steps positioned early in the catalytic chain, constitute a bar against substrate overloading of enzymes processing porphyrins, thus preventing accumulation in the body of these phototoxic compounds under physiological conditions. Most of the haem in the body is produced by the liver and bone marrow, but the mechanisms applied for the control of the synthesis differ between the two organs. The extremely potent hemeprotein enzymes formed in the liver are rapidly turned over in response to current metabolic needs. They have half-lives in the order of minutes or hours and are restored by fast-acting mechanisms for the de novo synthesis, when needed. Uninterrupted and instant availability of the compound is secured by acute deinhibition of the initial enzyme of the synthetic chain, ubiquitous 5-aminolevulinate synthase (ALAS-1), in response to drain of the free cellular haem pool caused by prevailing demands for hemeproteins or by increased catabolism of the compound. In contrast, in the erythroid progenitor cell the haem synthetic machinery is designed for uninterrupted production of huge amounts of haem for combination with globin chains to form hemoglobin at a steady rate. In the erythron the synthesis of the enzymes participating in the formation of haem is under control of erythropoietin, formed under hypoxic conditions. In the absence of iron, to be incorporated in the porphyrin formed in the last step of the synthesis, the mRNA of erythroid 5-aminolevulinate synthase (ALAS-2) is blocked by attachment of an iron-responsive element (IRE) binding cytosolic protein, and transcription of this key enzyme is inhibited. In humans, the genes for each of the haem synthetic enzymes may become the target of mutations that give rise to impaired cellular enzyme activity. Seven of the enzyme deficiencies are associated with accumulation of toxic intermediaries and with disease entities termed porphyrias. The acute porphyrias are characterized by attacks of neuropsychiatric symptoms, which may be due to a toxic surplus of the porphyrin presursor 5-aminolevulinic acid, or a consequence of a deficit of vital hemeproteins resulting from impaired synthesis of haem. In the cutaneous porphyrias, impairment of enzymatic steps where porphyrins are processed gives rise to solar hypersensitivity due to accumulation of phototoxic porphyrins in the skin. Early diagnosis, information to the patient regarding the nature of the illness and counselling aimed at avoidance of triggering factors are cornerstones in the handling of the porphyric diseases. Gene analysis is of incomparable diagnostic reliability in carrier detection, but biochemical methods must be applied in the important task of monitoring porphyric disease activity. In most forms of porphyria the gene carriers run the risk of development of associated diseases in liver or kidneys, a circumstance that prompts application of well-structured surveillance programs.