[Psoriasis and inflammatory bowel diseases]

Psoriasis and inflammatory bowel diseases (Crohn's disease and ulcerative colitis) are among the immune-mediated inflammatory diseases. This group includes approximately 80 disorders, some of which can at times be associated in a single patient. In psoriasis, Crohn's disease may be observed slightly more frequently, but ulcerative colitis and celiac disease are also an issue. The underlying relations between these disorders comprise: i) genetic data obtained by genome-wide association studies that show the involvement of shared predisposing loci and/or genes, for example, in innate immunity; ii) immunological data: these disorders share inflammation effector mechanisms, particularly the activation pathway of Th17 lymphocytes, which explains the efficacy of anti-TNF antibodies and anti-IL-12/23; and iii) environmental co-factors such as smoking, possibly certain food proteins (gliadin, etc.), and bacterial infections that are probably decisive elements in the genesis of these diseases.