1 Department of Health, Kinesiology, and Applied Physiology, Concordia University, Montreal, Quebec, Canada.
2 Metabolism, Obesity, and Nutrition Laboratory, PERFORM Centre, Concordia University, Montreal, Quebec, Canada.
3 Centre de recherche - Axe maladies chroniques, Centre intégré universitaire de santé et de services sociaux du Nord-de-l'Ile-de-Montréal, Hôpital du Sacré-Coeur de Montréal, Montreal, Quebec, Canada.
4 Division of Endocrinology, Department of Medicine, McGill University, Royal Victoria Hospital, MUHC Glen site, Montreal, Quebec, Canada.
5 Division of Geriatric Medicine, Department of Medicine, McGill University, MUHC-Montreal General Hospital, Montreal, Quebec, Canada.

Objective: The inflammatory environment in lower-body subcutaneous adipose tissue (SAT) has been largely unexplored. This study aimed to examine the effects of region (upper body vs. lower body) and sex on SAT immune cell profiles in young adults with obesity.

Methods: Abdominal (AB) and femoral (FEM) SAT was collected from 12 males (mean [SEM] age = 30.8 [1.4] years; mean [SEM] BMI = 34.1 [1.1] kg/m² ) and 22 females (mean [SEM] age = 30.6 [0.6] years; mean [SEM] BMI = 34.0 [0.7] kg/m² ) with obesity via needle aspiration. Flow cytometry was used to quantify macrophage (CD68+) and T-cell (CD3+) subpopulations in the stromovascular fraction of each SAT region.

Results: Females had a greater proportion of most T-cell types (CD3+CD4+CD45RA+, CD3+CD4+CD45RA-, and CD3+CD8+CD45RA+) in FEM compared with AB SAT, while males had similar proportions in both regions. Regardless of sex, the M1-like macrophage population (CD68+CD206-) was proportionally higher in AB SAT than in FEM SAT.

Conclusions: Results showed that T-cell populations vary by SAT region in females but not males. Both sexes, however, have proportionately more proinflammatory macrophages in upper-body than in lower-body SAT. It remains to be seen how these unique immune cell profiles in males and females with obesity contribute to adipose tissue inflammation and metabolic disease risk.