Figure 1.

Functional and molecular alterations in senescent macrophages. Senescent macrophages are characterized by upregulated p16^INK4a and accumulation of SA-β-gal, SASP, MMP-9, and PGE2. These abnormal accumulation and expression levels finally undermine macrophage functions like compromised migration through barriers, poor phagocytosis level to defend against bacteria and other infections, less effective antigen presentation towards T cells, low metabolism with deficient glucose and other metabolism productions contributing to other dysfunctions, imbalanced polarization which lead to the diseases and degenerations.