Considering that keratinocyte-derived cytokines are involved in the pathogenesis of AD [34,36], the next step was to evaluate the exogenous effect of Gal-9 in the human keratinocytes under a mimetic AD microenvironment (TNF-α/IFN-γ, IL-4, or IL-17 stimulation). This evidence concerns the gene IL4 and Alzheimer disease.