CCL17 and Alzheimer disease: Since Th2 and Th22 immune pathways predominate in AD inflammatory response, these potential biomarkers include Th2- and Th22-related cytokines and chemokines identified both in skin and serum, namely, interleukin (IL)-13, IL-22, thymus and activation-regulated chemokine/C-C motif ligand 17 (TARC/CCL17), pulmonary and activation-regulated chemokine (PARC/CCL18), macrophage-derived chemokine (MDC/CCL22), cutaneous T-cell-attracting chemokine (CTACK/CCL27) and eosinophil-attracting chemokine (eotaxin-3/CCL26) [18,25].