Past, present and future of in vitro 3D reconstructed inflammatory skin models to study psoriasis.

Psoriasis is a common chronic inflammatory skin disease with a significant socio-economic impact that can greatly affect the patients' quality of life. The prevailing dogma in the aetiology and pathophysiology of this complex disease is that skin cells, immune cells and environmental factors contribute to psoriatic skin inflammation. For a better understanding of the disease pathogenesis, models are required that mimic the disease and which can be used to develop therapeutics. Over the last decades, in vitro human reconstructed skin models have been widely used in dermatological research and have also been developed to mimic psoriatic skin. This viewpoint summarizes the most commonly used in vitro models and the latest accomplishments for the combination of the dermal and epidermal compartments with other cell types and factors that are important players in the psoriatic skin environment. We aim to critically list the most complete and best-validated models that include major psoriasis hallmarks with regard to gene and protein expression profile and epidermal morphology, but also discuss the shortcoming of the current models. This viewpoint intends to guide the development of in vitro 3D skin models that faithfully mimic all features of psoriatic skin. Such model will enable fundamental biological studies for a better understanding of the aetiology and pathophysiology of psoriasis and aid in novel therapeutic target identification and drug development studies.