FLG and Alzheimer disease: Importantly, upregulation of IL-1β in the nonlesional skin of both Flgft/ft and Rag1−/−Flgft/ft mice is consistent with our previous work in which epidermal IL-1β levels were increased in Flgft/ft mice and also in patients with AD with filaggrin mutations,48 indicating a key role for IL-1β in the dysregulated cutaneous environment arising from filaggrin deficiency.