Fig. 1.

Contribution of immunosenescence to the pathogenesis of AD. Under physiological conditions, around 40%–60% brain-born Aβ exits the brain and is cleared by peripheral tissues (i.e. kidney, liver and blood monocytes). In the circumstance of immunosenescence, immune system dysfunctions can lead to widespread premature aging of peripheral tissues. The Aβ clearance ability of aged tissues decreases, which might accelerate Aβ deposition in the brain. Besides, the secretion level of SASP factors of aged tissues is significantly increased, which might accelerate brain aging and neurodegeneration. SASP, senescence-associated secretory phenotype.