Erythropoietin signaling in peripheral macrophages is required for systemic β‐amyloid clearance.

Impaired clearance of beta‐amyloid (Aβ) is a primary cause of sporadic Alzheimer's disease (AD). Aβ clearance in the periphery contributes to reducing brain Aβ levels and preventing Alzheimer's disease pathogenesis. We show here that erythropoietin (EPO) increases phagocytic activity, levels of Aβ‐degrading enzymes, and Aβ clearance in peripheral macrophages via PPARγ. Erythropoietin is also shown to suppress Aβ‐induced inflammatory responses. Deletion of EPO receptor in peripheral macrophages leads to increased peripheral and brain Aβ levels and exacerbates Alzheimer's‐associated brain pathologies and behavioral deficits in AD‐model mice. Moreover, erythropoietin signaling is impaired in peripheral macrophages of old AD‐model mice. Exogenous erythropoietin normalizes impaired EPO signaling and dysregulated functions of peripheral macrophages in old AD‐model mice, promotes systemic Aβ clearance, and alleviates disease progression. Erythropoietin treatment may represent a potential therapeutic approach for Alzheimer's disease. Synopsis: How peripheral amyloid‐beta (Aβ) clearance affects Aβ levels in the brain is not clear. Here, it is shown to be promoted by erythropoietin (EPO) signaling in peripheral macrophages and to alleviate disease progression in mouse models of Alzheimer's disease (AD). EPO receptor deletion in peripheral macrophages decreases Aβ clearance, leading to increased peripheral and brain Aβ levels and enhanced AD progression.EPO signaling is impaired in peripheral macrophages of old AD‐model mice.EPO increases peripheral macrophage phagocytic activity and levels of Aβ‐degrading enzymes, and suppresses Aβ‐induced inflammatory response.Exogenous EPO treatment normalizes dysregulated functions of peripheral macrophages to promote systemic Aβ clearance and to alleviate AD progression. [ABSTRACT FROM AUTHOR]