CCL27 and Alzheimer disease: Among these, the most critical are cytokines associated with the Th2 and Th22 immune pathways, such as IL-13 and IL-22, as well as key chemokines, including thymus and activation-regulated chemokine/C-C motif ligand 17 (TARC/CCL17), eotaxin-3/CCL26, cutaneous T-cell-attracting chemokine (CTACK/CCL27), pulmonary and activation-regulated chemokine (PARC/CCL18), and macrophage-derived chemokine (MDC/CCL22), which highlight the immune dysregulation central to AD pathogenesis [2,55].