Adipose Tissue Macrophages of the Human Fetus
Ádám Radványi1, Katalin Gyurina1, Emese Rácz2
1Department of Pediatrics, Faculty of Medicine, University of Debrecen, 4032 Debrecen, Hungary.
Insights
Adipose tissue macrophages (ATMs) are present in fetal fat tissue starting at 17 weeks gestation. These early ATMs may influence prenatal development of fat depots and childhood adiposity.
Area of Science:
- Developmental biology
- Immunology
- Metabolic research
Background:
- Prenatal adipose tissue development is crucial for infant growth and childhood adiposity.
- Adipose tissue macrophages (ATMs) are vital for fat metabolism postnatally, but their prenatal presence and role are unknown.
Purpose of the Study:
- To investigate the presence and distribution of ATMs in human fetal adipose tissue.
- To determine if ATMs are present and functional during prenatal development.
Main Methods:
- Analysis of human fetal adipose tissue samples from 17 to 38 weeks gestation.
- Identification and characterization of ATMs using specific cell markers (CD45, CD14, CD68).
- Assessment of ATM phagocytic activity and gene expression (interleukin-6) in neonates.
Main Results:
- ATMs were found in fetal adipose tissue from 17 weeks gestation, persisting through the second and third trimesters.
- Neonatal ATMs demonstrated phagocytic capabilities and expressed pro-inflammatory markers like interleukin-6.
- These findings confirm early colonization of adipose tissue by ATMs.
Conclusions:
- ATMs colonize human adipose tissue early in gestation.
- The presence of ATMs suggests potential intrauterine communication influencing prenatal adipose tissue development.
- This early ATM activity may impact long-term adiposity and metabolic health.
Abstract:
Prenatal adipose tissue development affects body composition and growth trajectory in early infancy, therefore it is a key determinant of adiposity in childhood. Childhood overweight and obesity increase the probability of being obese as an adult. After birth and in adulthood, adipose tissue macrophages (ATMs) are relevant constituents of the fat depots, and they are necessary for physiological adipose tissue development and fat metabolism. In obesity, however, ATMs may induce chronic inflammation leading to insulin resistance, pancreatic beta cell damage and self-immunity. Despite being relevant regulators of adipose tissue development and functioning, it is unknown whether ATMs are present in the fetal adipose tissue, therefore it is elusive whether they may affect the prenatal establishment of fat depots. Here we studied the distribution of ATMs in the human fetus between gestational weeks 17 and 38 and labeled ATMs in the early postnatal life. We found that CD45+/CD14+/CD68+ ATMs infiltrated the fetal adipose tissue from the 17th week of gestation and remained persistent throughout the second and third trimesters. ATMs were phagocytic in the neonate and expressed interleukin-6, along with other pro-inflammatory gene products. These findings show that ATMs colonize the adipose tissue early in gestation, raising the possibility that intrauterine ATM-adipocyte communication may exist, eventually allowing ATMs to affect prenatal adipose tissue development.
