The induction of pruritus is due to the SP-induced production of pro-inflammatory cytokines and release of pruritogenic mediators from mast cells such as histamine, tumor necrosis factor (TNF)-α, prostaglandin D2, and leukotriene B4 via binding of SP to NKR1 on keratinocytes and mast cells [13], [19], [20]. This evidence concerns the gene TNF and Pruritus.