Skip to main content
. Author manuscript; available in PMC: 2022 Mar 4.
Published in final edited form as: Trends Immunol. 2018 Nov 21;39(12):980–991. doi: 10.1016/j.it.2018.10.001

Figure 1. Key Figure. The Itch–Scratch Cycle.

Figure 1. Key Figure

(A) Chronic itch sensations and associated scratching behaviors are components of a dynamic pathological process known as the itch–scratch cycle. Scratching behaviors exacerbate itch sensation through damage to skin epithelial cells. (B) The epithelial stress response releases cytokines, proteases, and AMPs that can activate immune cells to promote inflammation. (C) Keratinocytes may also activate itch-sensory neurons directly through soluble mediators such as cytokines and proteases. (D) Release of neuropeptides from neurons can also cause neurogenic inflammation. In contrast, cytokines and proteases produced by immune cells interface with the sensory nervous system to mediate itch. Abbreviations: AMP, antimicrobial peptide; DRG, dorsal root ganglion.