Blocking Immune Receptor in Aging Mice Restores Cold Tolerance and Fat Burning
Scientists found that deleting a specific receptor in immune cells prevents age-related decline in brown fat function and cold tolerance.
Summary
Researchers discovered that blocking a specific receptor called GHSR in immune cells can prevent age-related decline in thermogenesis - the body's ability to generate heat and burn calories. In aging mice, this receptor causes harmful inflammation in brown adipose tissue, the metabolically active fat that burns calories for heat. When scientists deleted GHSR from immune cells, older mice maintained better cold tolerance, preserved brown fat mass, and showed improved metabolic function. The treated mice had fewer inflammatory immune cells and more anti-inflammatory ones in their brown fat, along with higher expression of genes that promote fat burning. This suggests that targeting this immune pathway could help maintain metabolic health during aging.
Detailed Summary
As we age, our ability to regulate body temperature and burn calories for heat significantly declines, contributing to metabolic dysfunction in older adults. This study reveals a promising new target for maintaining these critical functions during aging.
Researchers at Texas A&M University investigated how a receptor called GHSR (growth hormone secretagogue receptor) in immune cells affects brown adipose tissue function. Brown fat is metabolically active tissue that burns calories to generate heat, but its function deteriorates with age due to chronic inflammation.
The team studied mice with GHSR deleted specifically from myeloid immune cells, comparing their responses to cold stress at young and old ages. They measured core body temperature, glucose levels, brown fat mass, and analyzed the types of immune cells present in the tissue.
Older control mice showed the expected age-related decline: impaired cold tolerance, reduced brown fat mass, and increased pro-inflammatory immune cells. However, mice lacking GHSR in immune cells maintained superior cold tolerance at both young and old ages. Crucially, aged mice without GHSR preserved their brown fat mass and showed a dramatic shift toward anti-inflammatory immune cells. They also had reduced inflammatory markers and increased expression of thermogenic genes that promote fat burning.
These findings suggest that GHSR in immune cells drives age-related inflammation that impairs metabolic function. Targeting this pathway could potentially help maintain thermogenesis, metabolic flexibility, and thermal resilience during aging - all important factors for healthy longevity and quality of life in older adults.
Key Findings
- Deleting GHSR from immune cells preserved brown fat mass and cold tolerance in aging mice
- Treatment shifted immune cells from pro-inflammatory to anti-inflammatory states in brown fat
- Aged treated mice maintained higher expression of fat-burning genes during cold exposure
- Immune cell GHSR appears to drive age-related metabolic dysfunction through inflammation
Methodology
Study used myeloid-specific GHSR knockout mice compared to controls at young and old ages. Researchers measured thermogenic responses to 4°C cold exposure, analyzed brown adipose tissue composition, and assessed immune cell populations and gene expression patterns.
Study Limitations
Study was conducted only in male mice, limiting generalizability to females and humans. The specific mechanisms by which GHSR deletion improves immune cell function require further investigation. Long-term safety and efficacy of targeting this pathway in humans remains unknown.
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