[Bullous pemphigoid: diagnosis and therapy]

[Management of bullous pemphigoid]

BACKGROUND

Bullous pemphigoid, the most common autoimmune blistering disease of the skin in adults, is caused by autoantibodies against hemidesmosomal adhesion proteins (BP180/type XVII collagen and BP230), leading into subepidermal blistering. Therefore patients, mostly older than 70 years, show tight bullae and erosions of the skin and rarely at mucous membranes.

PROBLEM

Usually the disease shows a chronically relapsing course. Thus there is a need for long-term topical corticosteroids and if necessary systemic immunosuppressives. Still there is no curative treatment available. In the context of a long-term treatment, drug-specific side effects and also a patient's comorbidities have to be taken into account.

CONCLUSION

The choice of treatment should be based on disease activity and the extent of the muco-cutaneous manifestations. Dependent on this, high-potent topical class IV corticosteroids are used because of fewer side effects compared to systemic steroids. In case of an intense disease extent or in refractory courses treatment with systemic corticosteroids is usually combined with potentially corticosteroid-sparing immunomodulants such as dapsone or doxycycline or adjuvant immunosuppressives such as azathioprine, mycophenoles or methotrexate. Medium- to long-term an attendant immunosuppressant should be applied to reduce the use of corticosteroids. The CD20-antibody rituximab and high-dose intravenous immunoglobulins are also supplemental off-label options in refractory cases.

Targeted Therapies for Autoimmune Bullous Diseases: Current Status

Autoimmune bullous skin disorders are rare but meaningful chronic inflammatory diseases, many of which had a poor or devastating prognosis prior to the advent of immunosuppressive drugs such as systemic corticosteroids, which down-regulate the immune pathogenesis in these disorders. Glucocorticoids and adjuvant immunosuppressive drugs have been of major benefit for the fast control of most of these disorders, but their long-term use is limited by major side effects such as blood cytopenia, osteoporosis, diabetes mellitus, hypertension, and gastrointestinal ulcers. In recent years, major efforts were made to identify key elements in the pathogenesis of autoimmune bullous disorders, leading to the identification of their autoantigens, which are mainly located in desmosomes (pemphigus) and the basement membrane zone (pemphigoids). In the majority of cases, immunoglobulin G, and to a lesser extent, immunoglobulin A autoantibodies directed against distinct cutaneous adhesion molecules are directly responsible for the loss of cell-cell and cell-basement membrane adhesion, which is clinically related to the formation of blisters and/or erosions of the skin and mucous membranes. We describe and discuss novel therapeutic strategies that directly interfere with the production and regulation of pathogenic autoantibodies (rituximab), their catabolism (intravenous immunoglobulins), and their presence in the circulation and extravascular tissues such as the skin (immunoadsorption), leading to a significant amelioration of disease. Moreover, we show that these novel therapies have pleiotropic effects on various proinflammatory cells and cytokines. Recent studies in bullous pemphigoid suggest that targeting of immunoglobulin E autoantibodies (omalizumab) may be also beneficial. In summary, the introduction of targeted therapies in pemphigus and pemphigoid holds major promise because of the high efficacy and fewer side effects compared with conventional global immunosuppressive therapy.