We may age at different rates, but none of us escapes aging. A study in mice and human cells by Stanford Medicine researchers pins much of the blame on a particular type of immune cell’s increasing inability, with advancing age, to gobble up another immune cell type.

So-called tissue-resident macrophages appear to be central coordinators of age-related organ decline. Blocking a single receptor on these cells preserved the youthfulness of multiple organs in mice, including the brain, heart, skeletal and heart muscle, liver, spleen, bone marrow, kidney and colon. The receptor binds specifically to a hormone known to cause inflammation and pain in humans as well as mice.

In mice, selectively disabling this receptor exclusively on tissue-resident macrophages prevented chronic inflammation-driven disorders of aging, including frailty, excessive fat accumulation and heart trouble. It also substantially slowed cognitive decline, said Katrin Andreasson, MD, the Edward F. and Irene Thiel Pimley professor of neurology and neurological sciences.

A newly identified protein pathway may link blood-brain barrier deterioration to age-related cognitive decline.

Cognitive frailty, characterized by the coexistence of physical frailty and cognitive impairment, has emerged as a major challenge in aging populations and is closely linked to sarcopenia, neurodegeneration, and chronic inflammation. Increasing evidence suggests that the gut microbiota acts as a central regulator of neuromuscular and neurocognitive aging through the integrated gut–brain–muscle axis. This review highlights how microbial dysbiosis, reduced short-chain fatty acid (SCFA) production, systemic endotoxemia, and altered microbial metabolites contribute to mitochondrial dysfunction, neuroinflammation, anabolic resistance, and impaired neuroplasticity.

Why does the immune system become less effective as we age? A new USC study published in BMC Biology offers fresh insights by examining a key immune cell type across tissues: macrophages.

Macrophages act as the body’s cleanup and maintenance crew. Found in nearly every tissue, they help fight infections, remove damaged cells, repair tissues and keep inflammation under control, acting as a first line of defense for the immune system. But like many cells in the body, macrophages change as we get older.

In this new study, researchers analyzed data from macrophages collected from different mouse tissues, including the brain, lungs, liver and other organs. By comparing younger and older animals, they uncovered common patterns of aging shared across many macrophage populations, as well as important differences depending on where the cells come from.