Treatment of chronic actinic dermatitis with azathioprine

NRF2 in dermatological disorders: Pharmacological activation for protection against cutaneous photodamage and photodermatosis

The skin barrier and its endogenous protective mechanisms cope daily with exogenous stressors, of which ultraviolet radiation (UVR) poses an imminent danger. Although the skin is able to reduce the potential damage, there is a need for comprehensive strategies for protection. This is particularly important when developing pharmacological approaches to protect against photocarcinogenesis. Activation of NRF2 has the potential to provide comprehensive and long-lasting protection due to the upregulation of numerous cytoprotective downstream effector proteins that can counteract the damaging effects of UVR. This is also applicable to photodermatosis conditions that exacerbate the damage caused by UVR. This review describes the alterations caused by UVR in normal skin and photosensitive disorders, and provides evidence to support the development of NRF2 activators as pharmacological treatments. Key natural and synthetic activators with photoprotective properties are summarized. Lastly, the gap in knowledge in research associated with photodermatosis conditions is highlighted.

Recent Developments in the Diagnosis and Management of Photosensitive Disorders

Photodermatoses occur in males and females of all races and ages. Onset can be variable in timing and influenced by genetic and environmental factors. Photodermatoses are broadly classified as immunologically mediated, chemical- and drug-induced, photoaggravated, and genetic (defective DNA repair or chromosomal instability) diseases. Advances in the field have led to improved recognition and treatment of many photodermatoses. The purpose of this focused review is to provide an update on the diagnosis and management of a variety of photodermatoses, both common and less common, with review of recent updates in the literature pertaining to their diagnosis and management.

Chronic actinic dermatitis

Chronic actinic dermatitis (CAD) is an immunologically mediated photodermatosis characterized by pruritic eczematous and lichenified plaques located predominantly on sun-exposed areas with notable sparing of eyelids, skin folds, and postauricular skin. CAD is thought to be due to secondary photosensitization of an endogenous antigen in the skin. Management of CAD should include strict photoprotection and topical agents, including corticosteroids and calcineurin inhibitors. Other treatments with noted efficacy include oral prednisone, cyclosporine, azathioprine, and mycophenolate mofetil. Photoprotection and avoidance of allergens, if identified, may lead to spontaneous resolution of CAD in 50% of patients over 15 years.

Diagnosis and pharmacological treatment of chronic actinic dermatitis in the elderly: an update

Chronic actinic dermatitis (CAD) describes a condition resulting from abnormal photosensitivity; the dermatitis is clinically similar to contact allergic dermatitis. Sun-exposed skin is more commonly affected but the condition can extend to and encompass unexposed skin. CAD is relatively rare but becomes more prevalent in the elderly population. Phototesting, patch testing and laboratory results should be used to help guide diagnosis. In the elderly, it is important to distinguish CAD from drug-induced photosensitivity. Management of the condition requires sunlight avoidance and use of sunscreens, topical emollients and topical corticosteroids. Oral corticosteroids and immunosuppressive therapy such as azathioprine may be indicated but should be used with caution in the elderly.

[Chronic actinic dermatitis: treatment with topical tacrolimus (two cases)]

BACKGROUND

Chronic actinic dermatitis is usually controlled under systemic immunosuppressive drugs. We report herein two patients successfully treated with topical tacrolimus.

CASE REPORTS

Two men aged 60 and 70 years were treated for chronic actinic dermatitis for two years using systemic immunosuppressive drugs. Due to drug intolerance and treatment resistance, systemic treatment was substituted by topical tacrolimus. Cutaneous lesions improved dramatically within two months but withdrawal of daily application was immediately followed by recurrence of the lesions.

DISCUSSION

Our cases, together with the 10 others reported in the literature, confirm the efficacy of topical tacrolimus in the treatment of chronic actinic dermatitis. Since tacrolimus chiefly targets activated T lymphocytes, it has been successfully deployed in various inflammatory dermatoses and its use is logical in the treatment of chronic actinic dermatitis. While dramatic improvement is achieved within a few weeks in this indication with twice-daily applications of tacrolimus ointment 0.1%, symptoms recur rapidly on dosage reduction, and extremely long-term, or even lifelong, treatment is thus probably needed. Topical tacrolimus application has been shown to be safe for periods of three years. However, the peculiar mechanism of chronic actinic dermatitis with a pronounced imbalance in T-cell subsets raises the question of theoretical risk of carcinogenicity of tacrolimus applications, and this, together with the prolonged duration of treatment, calls for long-term follow-up of chronic actinic dermatitis patients.

Azathioprine in dermatology: The past, the present, and the future

For several decades, dermatologists have utilized azathioprine to treat numerous debilitating skin diseases. This synthetic purine analog is derived from 6-mercaptopurine. It is thought to act by disrupting nucleic acid synthesis and has recently been found to interfere with T-cell activation. The most recognized uses of azathioprine in dermatology are for immunobullous diseases, generalized eczematous disorders, and photodermatoses. In this comprehensive review, the authors present recent advancements in the understanding of azathioprine and address aspects not covered in prior reviews. They (1) summarize the history of azathioprine; (2) discuss metabolism, integrating information from recent publications; (3) review the mechanism of action with attention paid to the activities of azathioprine not mediated by its 6-mercaptopurine metabolites and review new data about inhibition by azathioprine of the CD28 signal transduction pathway; (4) thoroughly examine thiopurine s-methyltransferase genetics, its clinical relevance, and interethnic variations; (5) review prior uses of azathioprine in the field of dermatology and grade the level of evidence; (6) discuss the use of azathioprine in pregnancy and pediatrics; review (7) key drug interactions and (8) adverse effects; (9) suggest a dosing and monitoring approach different from prior recommendations; and (10) explore the future of azathioprine, focusing on laboratory considerations and therapeutic application.

A case of chronic actinic dermatitis treated with topical tacrolimus

INTRODUCTION

The treatment of chronic actinic dermatitis (CAD), a sun-induced disorder characterized by a persistent eczematous eruption, involves photoprotective measures, topical corticosteroid therapy and, in more severe cases, systemic immunosuppression. The potential side effects of systemic immunosuppressant drugs prompted us to evaluate the efficacy of topical tacrolimus for treatment of CAD. PATIENT AND TREATMENT: A 58-year-old man with CAD, resistant to previous treatment with topical and systemic corticosteroids, oral cyclosporine and PUVA-photochemotherapy, was treated with tacrolimus ointment 0.1% once a day.

RESULTS

Tacrolimus ointment led to significant improvement of pruritus and severe eczematous skin lesions after 20 days of treatment.

CONCLUSIONS

Tacrolimus shows a beneficial effect on CAD; this could be attributed to the fact that CAD is characterized by a lymphohistiocytic infiltrate producing a chronic eczema and that tacrolimus blocks the activation of lymphocytes and other immune system cells, also inhibiting the release of mediators from cutaneous mast cells and basophils.

Chronic actinic dermatitis in the elderly: recognition and treatment

Chronic actinic dermatitis is a condition involving abnormal cutaneous photosensitivity to UV and, often, visible wavelengths. It is rare, but more common in the elderly than in younger populations, with an estimated prevalence of one in 2000 in the > or = 75-year-old population in Tayside, Dundee, Scotland. It usually presents as a dermatitis that maximally, but not exclusively, affects photo-exposed skin. Investigation to confirm the diagnosis and guide management includes phototesting and patch testing. The mainstay of treatment is education about the condition and advice on sunlight and allergen avoidance. Topical corticosteroids and emollients are always required, at least intermittently, and it is sometimes necessary to resort to systemic immunosuppression, usually with corticosteroids or azathioprine.

Diagnosis and treatment of chronic actinic dermatitis

Chronic actinic dermatitis, synonymous with the photosensitivity dermatitis and actinic reticuloid syndrome, presents as a dermatitis and/or a pseudolymphomatous eruption. Abnormal photosensitivity to ultraviolet (UV) and often visible radiation is a feature. Many patients also have multiple contact allergens. Histopathologic features vary, with a spectrum from mild dermatitis to pseudolymphomatous (reticuloid) features. The essential tests to make the diagnosis and to guide advice on avoidance of the responsible wavelengths and any contact allergens are phototesting and patch testing. Chronic actinic dermatitis can be regarded as a disorder of increased susceptibility, for reasons that remain uncertain, to develop delayed-type allergic responses to both endogenous photoallergens and exogenous allergens. Treatment consists of detailed advice on sunlight and allergen avoidance (guided by the results of investigations), topical corticosteroids, and emollients. When these measures are insufficient alone, systemic immunosuppressives may be considered: systemic prednisolone for acute exacerbations or azathioprine if systemic treatment is required for more than a few weeks.

Traditional therapies: glucocorticoids, azathioprine, methotrexate, hydroxyurea

The 'old favourites' used for treatment of inflammatory diseases, and hence, the original immunomodulators, include the glucocorticoids, azathioprine, methotrexate and hydroxyurea. Glucocorticoids are still one of the most effective anti-inflammatory agents because they work on several different intracellular processes and hence, block many components that contribute to inflammatory and immune responses. They bind to intracellular glucocorticoid receptors which transport them into the nucleus. Here the receptor/steroid complex may bind to many genes that interact with transcription factors including NFkappaB and AP-1, to inhibit their activation, thereby preventing activation of many genes encoding immune effector and pro-inflammatory cytokines. Also, protein kinases involved in intracellular signalling, are directly activated resulting in phosphorylation of various targets of which Annexin (AXA)-1 is critical in inhibiting biosynthesis of both purines and DNA. This results in reduced proliferation of B and T lymphocytes, reduced immune effector mechanisms and reduced recruitment of mononuclear cells including monocytes into sites of immune inflammation. Methotrexate also blocks DNA synthesis and hence cellular proliferation but also induces release of adenosine. This inhibits chemotaxis of polymorph neutrophils and release of critical cytokines such as TNF-alpha and Interleukins 6 and 8. Hydroxyurea also inhibits DNA synthesis with inhibitory effects on proliferation of lymphocytes and possibly kerationcytes. Even though many new agents with much greater selectivity are coming through into clinical use, this group of old agents still have an absolutely central position in the therapeutic armamentarium. Their value lies in the fact that they are not 'clean' drugs with narrow effects but they inhibit a wide range of mechanisms involved in immune and inflammatory processes.

Drug photosensitivity, idiopathic photodermatoses, and sunscreens

Photosensitization may be defined as a process in which a reaction to normally innocuous radiation is induced by the introduction of a specific radiation-absorbing substance (the photosensitizer) that causes another component (the substrate) to be changed by the radiation. This review focuses on photosensitization produced by exogenous chemicals. Idiopathic photodermatoses, including polymorphous light eruption and its variants, solar urticaria and chronic actinic dermatitis, are also discussed. Clinical recognition patterns of the photodermatoses are stressed as well as several diagnostic procedures available for confirmation of the condition. Finally, descriptions, therapeutic uses, and adverse reactions of sunscreens are provided.

Photochemotherapy beyond psoriasis

Photochemotherapy involves the therapeutic use of nonionizing radiation in combination with a photosensitizing chemical to trigger a photochemical reaction that mediates a beneficial effect. The successful introduction and widespread use of psoralen photochemotherapy (PUVA) in the management of psoriasis was the chief stimulus for recent interest in the therapeutic use of nonionizing radiation in various other dermatoses. This article discusses the expanding spectrum of diseases responding to PUVA therapy. More than 30 conditions such as atopic dermatitis, mycosis fungoides, vitiligo, the photodermatoses, chronic graft-versus-host disease, and granuloma annulare have been successfully treated with oral psoralen photochemotherapy. Various mechanisms of response to treatment are discussed including photoimmunologic effects, selective cytotoxicity, alterations of cell function, and stimulation of melanocytes. Finally, the limitations to the use of PUVA therapy are identified and its future use in other cutaneous and systemic diseases are discussed.

Chronic actinic dermatitis

Chronic actinic dermatitis (CAD) is one of the most frequently encountered photodermatoses in patients older than 50 years of age. It is characterized by persistent redness of the face and other exposed areas. CAD can become so severe that even nonexposed parts of the body develop eczematous lesions and the disease persists during winter. The diagnosis must be confirmed by phototests that show a broad action spectrum with low threshold doses. CAD must be differentiated from photocontact allergy and airborne dermatitis. The histopathologic features in the early stages are comparable to contact dermatitis, whereas in the later stages they may be those of pseudolymphoma. The most popular treatments are azathioprine and PUVA.

Successful treatment of musk ketone-induced chronic actinic dermatitis with cyclosporine and PUVA

We describe a patient with chronic actinic dermatitis whose photopatch tests revealed reactions to musk ketone and musk ambrette, both of which were found in his aftershave lotion. Minimal erythema doses of UVA and UVB were decreased. After initial unsuccessful treatment with PUVA therapy the patient was successfully treated with a combination of cyclosporine and PUVA.

Chronic actinic dermatitis with vitiligo-like depigmentation

This report describes two patients suffering from severe chronic actinic dermatitis. Unusual widespread vitiligo-like depigmentation occurred during the course of the disease. The progression of these lesions was triggered by the chronic actinic dermatitis. Loss of pigment and complete absence of tyrosinase positive melanocytes were found in depigmented skin of both cases. Immunohistological investigation of the inflammatory infiltrate in case 2 revealed a predominance of CD-8 positive cytotoxic/-suppressor lymphocytes. Analysing the adjacent pigmented epidermis of progressive depigmenting lesions a dense exocytosis of CD-8 T-cells was notable. This distribution suggests cytotoxic destruction of melanocytes as the cause for the vitiligo-like depigmentation.

Azathioprine in dermatology

Azathioprine has been available for 30 years and is used in a variety of dermatologic conditions. In common with other systemic immunosuppressant drugs, it has potentially serious side effects in both the short and the long term. It has a favorable therapeutic ratio, however, and most side effects can be avoided by administering low doses for short periods. This review describes azathioprine's chemistry, drug interactions, adverse effects, and oncogenicity and then deals with its clinical applications. The well-established uses are discussed first, followed by less conventional ones. In severe, potentially fatal blistering diseases, azathioprine has an undisputed place in management. For intractable, disabling actinic reticuloid and atopic eczema, it has a smaller part to play, and its role is less clear.

Recent advances in phototherapy and photochemotherapy of skin disease

The therapeutic spectrum for ultraviolet radiation treatment of skin disease has continued to be broadened. Psoralen photochemotherapy is beneficial in chronic lichenoid graft-versus-host disease and disseminated granuloma annulare. This treatment is now being found more useful in atopic eczema and chronic photosensitivity with some modifications of the therapy. UV phototherapy has also been found useful in mild to moderate atopic eczema. The nature of these treatments is also changing with greater use of selective UV phototherapy and definition of the required schedule for maintenance treatment with UVB phototherapy. The mechanism of therapeutic benefit remains unknown although one possibility is selective phototoxicity for inflammatory cells in the dermis. Nonmelanoma skin cancer, premature aging of the skin and freckling are the main long-term adverse effects of these treatments.

Photosensitivity in the elderly

Photosensitivity to drugs and chemicals in the elderly is more prevalent due to more frequent use of medications. Phototoxic reactions to common, orally administered drugs such as diuretics, cardiac agents and antidiabetics may occur and the reactions may be remedied by discontinuing drug therapy. Photocontact dermatitis due to the ingredients in sunscreens or other agents, such as perfumes, may also arise. Diagnosis is often confirmed by photopatch testing and subsequent avoidance of these agents leads to gradual resolution. Idiopathic photodermatoses, such as sunlight-induced polymorphic light eruption or solar urticaria, may occur and persist from an early age and, in elderly subjects, they can cause mild to marked disability. The most disturbing disorder of this type is the severe, widespread eczematous chronic actinic dermatitis, which can be difficult to diagnose. Porphyrias, such as variegate porphyria or erythropoietic protoporphyria, may persist from an early age, whereas porphyria cutanea tarda generally begins in later life. Porphyrias all have specific clinical and biochemical features and, apart from variegate porphyria, usually respond well to treatment following diagnosis. Exposure of elderly skin to sunlight may also cause deterioration of many ordinary dermatoses, particularly seborrhoeic eczema, which generally respond to protection from UV exposure and to treatment of the underlying abnormality. Progress in identifying the underlying causes, the availability of increasingly sophisticated diagnostic techniques, and improvements in sunscreen preparations and therapeutic medications will probably significantly reduce abnormal photosensitivity in the elderly in the near future.

Azathioprine treatment in chronic actinic dermatitis: a double-blind controlled trial with monitoring of exposure to ultraviolet radiation

Oral azathioprine was compared with placebo in a double-blind controlled trial of therapy in chronic actinic dermatitis (CAD), a rare eczematous photodermatosis. Eighteen severely affected patients were randomly allocated to azathioprine 50 mg t.d.s. or placebo over a 2-year period. Severity of itch and rash were assessed weekly by each patient on a visual analogue scale and overall clinical status monthly by a medical observer. Monitoring of patient ultraviolet radiation (UVR) exposure was undertaken throughout treatment by polysulphone film lapel-badge dosimetry. Five of 8 patients treated with azathioprine but none of 10 placebo patients achieved remission within 6 months. One patient could not tolerate treatment because of gastrointestinal effects. No haematological or hepatic abnormality was noted. The marked improvement in clinical status of actively treated patients (P less than 0.02, Fisher's exact test), led to early termination of the trial. Oral azathioprine therapy is an effective and usually well tolerated treatment in chronic actinic dermatitis.

Dermatopharmacology: drugs around the corner

This article describes impending advances in drug treatment of skin diseases. We have included the following categories: (1) interesting new drugs for which there are reasonable prospects of eventual licensing for skin indications, (2) important novel compounds whose progress through licensing procedures, although incomplete at the time of writing, is advanced, and (3) new indications or improved regimens that have recently emerged for established drugs.

Actinic reticuloid in a black man: successful therapy with azathioprine

A 61-year-old black man suffering from actinic reticuloid with contact allergy to four substances, extreme sensitivity to both ultraviolet A and ultraviolet B, normal visible light sensitivity, and negative results on photopatch tests was placed on a regimen of azathioprine, 50 mg twice a day. At 3 months, clinical appearance was unchanged, as was his strong contact allergy; however, tolerance to natural sunlight was markedly improved. At 6 months the clinical appearance and ultraviolet responses were normal; however, strong contact allergy persisted. To our knowledge, this is the first report of actinic reticuloid in a black person. Azathioprine, after giving an excellent clinical response without leukopenia, was discontinued. A further 9-month follow-up showed continued remission. The persistence of contact allergy, despite profound improvement in photosensitivity and the skin's appearance, suggests that the role of contact allergy in the cause of actinic reticuloid is unclear, and the existence and identity of the hypothesized photosensitizer(s) in actinic reticuloid remain unproved.

PUVA therapy of chronic actinic dermatitis

Four men with long-standing chronic actinic dermatitis were treated with a modified PUVA regime which initially included generalized applications of topical steroids given immediately after PUVA exposure. All patients are now free of rash, no longer need protection from UV radiation, and are being maintained on twice monthly PUVA therapy (IO J/cm2).