The mechanisms underlying metabolic decline during ageing are not well understood. A new study in Cell Metabolism identifies IgG antibodies as factors that accumulate in white adipose tissue (WAT) during ageing, driving tissue fibrosis and impaired metabolic health in mice.

“Leveraging our understanding of ageing research, we naturally sought to investigate whether interventions targeting ageing could influence IgG accumulation in adipose tissue,” says corresponding author Liheng Wang. Considering previous work showing the anti-ageing effects of caloric restriction, they investigated IgG accumulation in calorie-restricted mice (CR-mice). Interestingly, age-linked IgG accumulation was decreased in CR-mice and administering IgG to CR-mice counteracted the beneficial effects of caloric restriction on glucose metabolism. Delving into the mechanisms, the researchers found that IgG was activating adipose tissue-resident macrophages. The activated macrophages induced fibrosis in WAT, which is detrimental for systemic metabolic health.