CCR5 and Alzheimer disease: As for the mechanism of CCR5 overexpression in AD, it was found that Aβ promoted CCR5 expression by enhancing the binding of transcription factor early growth response protein 1 (Egr-1) to the CCR5 promoter; Egr-1 gene silencing inhibited CCR5 expression and abolished chemotaxis mediated by CCR5 (47).