Psoriasis: New insight about pathogenesis, role of barrier organ integrity, NLR/CATERPILLER family genes and microbial flora

Psoriasis is a common, inflammatory, chronic, relapsing skin disease. New insight about the etiology of this disease shows the important role played by the epidermal barrier function, its integrity and pathogen responses in combination with microbial environmental factors. A pivotal role in the management of this balance is played by NLR genes, also known as NBD-LRR or CATERPILLER, that encode important mediators of innate immunity and provide the first line of defense against pathogens. The polymorphism of these genes is implicated in the pathogenesis of several immunological diseases and might be of importance in the pathogenesis of barrier organ disorders. Crohn's disease is considered archetypal of these kinds of disorders; similarities between Crohn's disease and psoriasis and their similar pathogenetic mechanisms may support the concept of psoriasis as a barrier organ disorder and common genetic ground lying behind these illnesses. Considering psoriasis as a "barrier organ disease" is not only a mere mental exercise; this consideration may, in fact, open new prospects in the treatment of these disorders just by preventing alterations of microbial flora or regulating the response of the host to infective diseases. © 2012 Japanese Dermatological Association.