Neuroimmune Mediators of Pruritus in Hispanic Scalp Psoriatic Itch

Scalp psoriatic itch is a common, bothersome, yet understudied, condition with numerous associated treatment challenges. The aim of this study was to enhance our understanding of the pathophysiology of scalp psoriatic itch. Immunohistochemical analysis of known neuroimmune mediators of pruritus was conducted using scalp biopsies from 27 Hispanic psoriatic patients. Patients were categorized into mild/moderate or severe itch groups according to their itch intensity rating of scalp itch. Protease activated receptor (PAR2), substance P, transient receptor potential (TRP)V3, TRPM8 and interleukin-23 expression all correlated significantly with itch intensity. The pathophysiology of scalp psoriasis is largely non-histaminergic, mediated by PAR2, interleukin-23, transient receptor potential channels, and substance P. SIGNIFICANCE The body region most predominantly impacted by psoriatic itch is the scalp. This study correlated the presence of neuroimmune mediators with severity of itch in patients with scalp psoriasis. The results show that there may be a larger neural component to scalp psoriatic itch than previously thought. Neurotropic agents, rather than anti-histaminergic or cooling agents, may warrant greater consideration for the management of scalp psoriatic itch.