Good news! This could be a breakthrough!
"... researchers have identified a rogue population of immune cells that quietly accumulates in aging tissues and in the livers of people with fatty liver disease.
Clearing these cells, they found, dramatically reduced inflammation and reversed liver damage in mice—even while the animals remained on an unhealthy diet. ..."
"Key takeaways
- UCLA researchers have identified a population of dysfunctional immune cells — dubbed “zombie macrophages” — that accumulates in the liver during aging and fatty liver disease, driving the chronic inflammation behind both conditions.
- The study found that excess dietary cholesterol, not just aging alone, can push these immune cells into a permanently inflamed state, suggesting that high-cholesterol diets may accelerate biological aging at the cellular level.
- Treating mice with a drug that selectively clears these cells reversed fatty liver disease and reduced inflammation — even without any change in diet — pointing to a potential new therapeutic strategy for a condition affecting an estimated 30-40% of Los Angeles residents.
...
For years, scientists debated whether macrophages — the large immune cells that patrol every tissue in the body, engulfing debris, pathogens and dying cells — could truly become senescent. The prevailing view was that they could not. Part of the confusion stemmed from biology: macrophages naturally display some molecular markers of senescence even when healthy, making it hard to tell a genuinely dysfunctional cell from one simply doing its job.
The UCLA team resolved this by identifying a molecular signature — two proteins, p21 and TREM2, whose combination reliably flags macrophages that are genuinely senescent: no longer functional, but persistently inflaming their surrounding tissue.
Using this signature, the researchers found that the proportion of senescent macrophages in the liver surges from roughly 5% in young mice to nearly 60-80% in old ones, closely tracking with the rise of chronic liver inflammation during normal aging. But aging, it turns out, isn’t the only trigger. ...
"
From the abstract:
"Cellular senescence drives chronic sterile inflammation during aging via the senescence-associated secretory phenotype, yet the senescent cell types responsible are poorly defined.
Macrophages share multiple features of senescence, including inflammatory secretion, yet whether macrophages can adopt a senescent state remains unclear. Here we identify p21⁺Trem2⁺ senescent macrophages as a major source of inflammaging, using primary mouse and human macrophage models of DNA damage and cholesterol-induced senescence characterized by multi-omic profiling. We found that senescent macrophages exhibit a distinctive p21-TREM2 expression profile and senescence-associated secretory phenotype, driven in part by type I interferon signaling via cytosolic mitochondrial DNA.
We also found that senescent macrophage accumulation occurs in aging, metabolic dysfunction-associated steatotic liver disease mouse livers, and is enriched in human cirrhotic liver tissue.
Finally, senolytic treatment targeting senescent macrophages reduced liver inflammation and steatosis in both aged mice and mice with metabolic dysfunction-associated steatotic liver disease.
These findings establish macrophage senescence as a central driver of chronic inflammation in aging and metabolic liver disease, and a tractable therapeutic target."
UCLA scientists identify zombie immune cells as a driver of fatty liver disease, inflammation and aging (original news release)
Microscopy image showing senescent macrophages in red and cholesterol-laden lipid droplets – a key driver of senescence – in green.
Fig. 3: Senescent p21+ macrophages accumulate in aged metabolic tissues.
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