Ständer S, et al. - In the present study, the researchers sought to provide an overview of chronic pruritus pathogenesis, concentrating on the role of substance P (SP) and neurokinin 1 receptor (NK₁R) in itch signalling, and to analyze data supporting NK₁R antagonism as a potential strategy for chronic pruritus treatment. The authors discovered NK₁R expression in the central nervous system and on multiple cell types, involved in the initiation and transmission of itch. Studies showing that SP and NK₁R are over-expressed across multiple chronic itch-inducing conditions and that NK₁R antagonism disrupts itch-signaling and decreases itch provide a basis for targeting this pathway as a possible chronic pruritus treatment across multiple diseases. A large and growing body of evidence, including recent phase II clinical studies of NK₁R antagonists, indicates that SP and NK₁R play a significant role in the signing of itch.