A hypothesis for the role of substance P that would account for the temporal onset with stress, the clinical symmetry of lesions, and the histopathologic features of psoriasis is presented.
Overexpression of several genes, such as phospholipase A2 IVD, substance P, voltage-gated sodium channel 1.7, and transient receptor potential (TRP) vanilloid 1, in itchy skin was positively correlated with itch intensity ratings in both atopic dermatitis and psoriasis.
Several neuropeptides, including substance P (SP), nerve growth factor, calcitonin gene-related peptide, and vasoactive intestinal peptide have been hypothesized to play a part in the development of psoriasis and its symptoms.