Relationship of Chromosome Arm 10q Variants to Occurrence of Multiple Primary Melanoma in the Population-Based Genes, Environment, and Melanoma (GEM) Study

Abstract

previously reported that touch-evoked scratching was elicited only by stimulation at the skin adjacent to a site of acute itch or the border of the dry skintreated area on the rostral back (Akiyama et al., 2012; Iwanaga et al., 2018). Therefore, it appears that, although Ab-fibers innervating the chemical-injected site or the skin within the treatment area drive a circuit for antimechanical itch, a subset of LTMRs innervating the adjacent skin mediates touch-evoked itch. In summary, we show that alloknesis in an IMQ-induced psoriatic mouse model is associated with a loss of the epidermal nerve endings of Ab-fibers but not Merkel cells. By contrast, alloknesis in dry skin and aged skin is associated with a loss of Merkel cells (Feng et al., 2018). Considering that the Merkel cells are innervated by Ab-fibers, the loss of sustained discharge of Ab-fibers from Merkel cells is essential for alloknesis. Ab-fibers in hairy skin likely innervate neuropeptide Y-positive inhibitory interneurons in the spinal cord to gate mechanical itch in normal conditions (Bourane et al., 2015). Our findings suggest that reactivation of Ab-fibers can reduce alloknesis under chronic itch condition. High-frequency transcutaneous electrical nerve stimulation activates Ab-fibers and temporarily relives generalized itch (Wallengren, 2004). Additionally, massage therapy works for certain types of itch (Gü rol et al., 2010; Schachner et al., 1998). Although antipruritic effects of those therapies are expected to be temporary, the approach to regain Ab-fibers could be considered as a novel strategy for treating chronic itch.