Yale Scientists Discover Novel Immune Cells Driving Age-Related Inflammation

Scientists have identified a previously unknown type of immune cell in mouse fat tissue that appears to play a central role in chronic inflammation associated with aging. Unlike other immune cells in the same tissue that suppress inflammation, this newly discovered macrophage subgroup was found exclusively in older mice and showed elevated expression of pro-inflammatory factors and aging-related signaling molecules. The findings, published in Nature Aging, shed new light on how the immune system changes with age.

Using high-resolution imaging and single-cell RNA sequencing, a Yale University research team systematically analyzed visceral fat macrophages in both young and aged mice. They identified 13 distinct macrophage populations whose abundance and distribution varied significantly with age and sex. Notably, the newly discovered subgroup may directly drive “inflammaging”—the chronic, low-grade inflammation linked to aging.

The study also revealed that nerve-associated macrophages extend fine synapse-like projections to connect structurally with surrounding nerves, suggesting a role in maintaining neural homeostasis and regulating fat metabolism. Removing these cells in young mice triggered heightened inflammation and impaired lipid breakdown.

Experts say the discovery highlights the complex regulatory roles of macrophages in aging and may provide promising therapeutic targets for age-related inflammation and metabolic diseases. The Yale team plans to further investigate the developmental origins and mechanisms of this pro-inflammatory macrophage population to advance translational medicine.