Mechanisms of Action of Photo(Chemo)Therapy in Skin Diseases

The molecular mechanisms of action of photo(chemo)therapy in skin diseases are investigated in this study. The phototherapeutic modalities employed include UVB (ultraviolet B), UVA (ultraviolet A), PUVA (psoralen+UVA) and/or extracorporeal photochemotherapy (photopheresis). The study will address whether and how photo(chemo)therapy affects specific biologic pathways in different skin disorders and search for predictive biomarkers.

This study is performed in order to investigate the molecular mechanisms of action of photo(chemo)therapy in skin diseases, including psoriasis, cutaneous T-cell lymphoma, other lymphoproliferative disorders of the skin, eczema, lichen planus, prurigo/pruritus, polymorphic light eruption, mastocytosis, graft-versus-host disease, vitiligo and other photo(chemo)therapy-responsive diseases. Twenty patients will be enrolled per diagnosis group. The phototherapeutic modalities administered will be UVB, UVA, PUVA and/or extracorporeal photochemotherapy (photopheresis). The severity of disease and clinical response to treatment will be assessed with scores including dermatological quality of life (DLQI) and disease-specific scores such as PASI (psoriasis area and severity index), mSWAT (modified severity-weighted assessment tool), SCORAD (scoring atopic dermatitis), scleroderma score and/or different visual analog scale (VAS) scores for pruritus. The effect of treatment on a variety of laboratory endpoints will be investigated in blood samples and optionally also skin samples. Those endpoints include among others the regulation of cytokines/chemokines, immune function, clonality of immune cells, vitamin D, and serum lipids. The study will address whether and how photo(chemo)therapy affects specific biologic pathways in the different disorders and determine whether predictive biomarkers for therapeutic response exist.