AKR1C3 and Alzheimer disease: On the other hand, patients’ cells showed increased expression of AKR1C3 and AQP9: AKR1C3 encodes an enzyme of aldo-keto reductase family that promotes inflammation in skin lesions of AD patients [51], while AQP9 codes for a member of the aquaporins that enhances skin barrier function and antimicrobial defenses [52].