In addition, a recent study revealed that IL‐33 regulates AD by modulating the expression of sebum and its microbial metabolite propionate on the surface of AD skin in MC903‐induced AD‐like mice; however, knockdown of IL‐33 or the IL‐33 receptor ST2 did not prevent the development of AD‐like skin inflammation.277, 278. This evidence concerns the gene IL1RL1 and Alzheimer disease.