CLDN1 and Alzheimer disease: CLDN1 regulates the pathogenesis, severity and natural course of human AD, and reduced levels of CLDN1 in AD skin have been inversely correlated with expression of Th2 markers and a propensity to infection.21, 22, 23 It is noteworthy that restoring the expression of CLDN1 alleviates atopic dermatitis.24 So regulating tight junctions might involve in the mechanism of attenuation of AD.