TAC1 and psoriasis: Psoriasis may be triggered by environmental exposures, especially infectious agents or by unmasked autoantigens, such as keratins 17 and 13 or neuropeptides like substance P, heterogenous nuclear ribonucleoproteins, cathelicidin, LL-37, A disintegrin and metalloprotease domain containing thrombospondin type 1 motif-like 5 (ADAMTSL5), phospholipase A2 group IVD, and pso p27 [10,11].