Skin barrier: structure and immune changes in common skin diseases

Abstract

Skin barrier must be seen as a complex structure with complex functions involving hydrolipidic film, stratum corneum, the intercellular cement and also immunologic barrier as innate adaptive immune system (as Toll Like Receptors - TLR), complement, dendritic cells and antigen-related responses. Skin barrier changes are seen in different skin diseases as atopic dermatitis, rosacea , contact dermatitis and others. In the first part of this article we describe skin physical barrier and its key elements roles (ceramides, filaggrin, tight junctions and claudins), the clinical consequences of barrier damages in different common skin diseases (atopic dermatitis, xeroses of different origins). Immune skin barrier is complex and in this first part of the article we focus only on innate immune system skin represented by Toll Like Receptors and their role in the synthesis of antimicrobial peptides (AMP). In the second part we present ex vivo and in vivo studies on skin physical barrier repair and improvement of AMP expression in human skin by modulating TLR2. The management of human skin barrier damages and their repair by active topicals must by a holistic approach, taking in account the complexity of physical and of immune barriers of the skin.