IL4 and Alzheimer disease: Mast cells, eosinophils and basophils interact with peripheral nerves to mediate skin inflammation, pain and itch in patients with AD via IL‐4, IL‐13, IL‐31, OSM, neuropeptides and substance P.25, 38Thus, the bidirectional communication between the nervous system and immune system can work to amplify the pathologic state in patients with AD (Figure 1).