Middle-aged humans and mice showed reduced natural killer cell numbers, maturation, and cytotoxic capacity, with lower degranulation and interferon-gamma output, most pronounced in males. The deficit tracked with expanding white adipose tissue and a falling basal metabolic rate, and was reproduced in young mice made obese by diet. Impaired immune surveillance in midlife offers a mechanistic link between adiposity and elevated all-cause mortality.
Key Points
- Midlife NK cells show reduced degranulation and interferon-gamma production
- Adipose expansion coincides with fewer, less mature NK cells
- Diet-induced obesity reproduced the same deficit in young mice
Longevity Analysis
Adipose tissue behaves as an active signaling environment that constrains the cells responsible for clearing infected and transformed cells, meaning body composition in the fourth and fifth decades carries consequences well beyond metabolic markers. Reducing the adipose burden that drives this suppression matters more than layering immune-supportive interventions on top of it, and the male-skewed effect argues for sex-specific interpretation of midlife immune data. Functional immune measures, not cell counts alone, are the signal worth tracking as metabolic rate declines.
Original published by Wiley Aging Cell, by Ruojia Biao, Xudong Wang, Jiantao Fu, Yifan Guo, Junming He, Juan Du .