CD55 and Alzheimer disease: Since S. aureus PI-PLC was observed to cleave CD55 and CD59 from the surface of human umbilical vein endothelial cells and mouse pneumocytes25, the PI-PLC-mediated shedding of CD55 and CD59 from keratinocytes might enhance epidermal penetration by S. aureus, epidermal hyperplasia, and immune cell infiltration in S. aureus-infected skin in AD model mice.