HRH4 and Pruritus: Some of the in vivo data also yield insight as to the role of functional selectivity at the H4R. In the models of pruritus, asthma, and dermatitis the phenotype is the same between JNJ 7777120-treated and H4R-deficient mice (Dunford et al., 2006, 2007; Cowden et al., 2010b).