Cellular Cleanup Decline with Age Weakens Removal of Senescent Cells
Senescent cells stop dividing, enlarge, and release inflammatory and growth-promoting signals after stress, injury, or reaching their replication limit. Young immune systems remove these cells efficiently, but they accumulate with age and disrupt tissue function. A new paper links age-related loss of chaperone-mediated autophagy in senescent cells and innate immune cells to poorer macrophage clearance of senescent cells.
Senescent cells arise after stress, injury, or upon hitting their replication limit. They stop dividing, enlarge, and release inflammatory and growth-promoting signals. In youth, immune cells clear them efficiently, and senescence can support regeneration and flag potentially cancerous cells. With age, clearance falters and these cells linger.
Chaperone-mediated autophagy relies on HSC70 to recognize proteins carrying a KFERQ-like motif and deliver them to LAMP2A on lysosomes. This pathway declines with age and is linked to neurodegeneration, metabolic syndrome, and atherosclerosis. The new work connects that decline, in senescent and innate immune cells, to weaker macrophage engulfment.
Because senescent cell buildup is tied to tissue dysfunction, older adults and people with fibrotic disease could be most affected by any future therapy that boosts chaperone-mediated autophagy. If such approaches prove safe, they may complement existing senolytic strategies. Still, mouse findings often fail to translate, and interventions would need to avoid disrupting autophagy's normal roles. Near-term impact is likely to be scientific rather than clinical.