Fig. 1: Definition and classification of trained immunity.
From: Trained immunity induced by DAMPs and LAMPs in chronic inflammatory diseases
a, Trained immunity is defined as innate immune memory, characterized by an enhanced production of proinflammatory cytokines or chemokines upon secondary stimulation that is distinct from the initial stimulus. Trained immunity can persist for days to weeks in innate immune cells (for example, monocytes, NK cells and tissue-resident macrophages) and non-immune cells (for example, ECs and SMCs) following exposure to inducers such as PAMPs or DAMPs, a phenomenon referred to as peripheral trained immunity. b, Trained immunity can also persist for months or even years through the reprogramming of HSPCs in the bone marrow, which is referred to as central trained immunity. The figure was created using BioRender.com. CMP, common myeloid progenitor; MPP, multipotent progenitor; Mo, monocytes; Mφ, macrophages.
