HIF1A and Alzheimer disease: AD is characterized by an increase in the release of local inflammatory factors, such as IL‐1β, TNF‐α and Th2 cytokines.25, 26 Many studies have shown that inflammatory cytokines play a vital role in the dysregulation of the epithelial barrier function.27, 28 HIF‐1α can be activated by these inflammatory mediators and can activate inflammation‐modulating proteins itself.29 Therefore, HIF‐1α may relate to the regulation of the epithelial barrier function.