UCLA scientists discovered that dysfunctional "zombie" immune cells called senescent macrophages accumulate in aging livers and drive inflammation. These cells make up only 5% of liver immune cells in young mice but 60-80% in older mice. When researchers removed them using a specific protein marker (p21-TREM2), liver damage was dramatically reversed even without changing unhealthy diets. The study found that excess LDL cholesterol can trigger these cells to become senescent, suggesting high-fat diets may accelerate biological aging throughout the body.
