FLG and Alzheimer disease: On the other hand, recent studies using human keratinocytes have identified a number of T-cell derived cytokines found in AD skin (e.g., IL-4, IL-13, TNF-α, IL-25, IL-22, or IL-17A) can inhibit the expression of key epidermal barrier proteins (e.g., filaggrin, loricrin, S100A11, and involucrin).