FLG and Alzheimer disease: An argument for the acquired pathway is the fact that a number of T-cell-derived cytokines (e.g., IL-4, IL-13, IL-25, IL-22, or IL-17A) found in AD skin can inhibit the epidermal expression of key barrier proteins such as filaggrin, loricrin, and involucrin, which are also markers of terminal differentiation [88,89,90,91].