The age of obesity onset affects changes in subcutaneous adipose tissue macrophages and T cells after weight loss

Jessica Murphy¹José A. Morais²Michael A. Tsoukas²Alexandra B. Cooke²Stella S Daskalopoulou²Sylvia Santosa^1*

• ¹Concordia University, Montreal, Canada
• ²McGill University, Montreal, Quebec, Canada

Introduction: Adipose tissue inflammation, driven in part by immune cells, may contribute to the elevated type 2 diabetes risk in adults with childhood-onset obesity (CO) compared to those with adult-onset obesity (AO). Weight loss can modify adipose tissue immune cell composition, but whether these changes differ by obesity onset remains unknown. Methods: We compared abdominal and femoral subcutaneous adipose tissue (SAT) immune cell proportions between people with CO and AO before and after moderate (~10%) weight loss. We collected abdominal and femoral SAT from females with CO or AO before (CO: n=14; AO: n=13) and after (CO: n=8; AO: n=6) diet- and exercise-induced weight loss. We used flow cytometry to quantify the proportions of macrophages and T cells in the stromovascular fraction of both SAT regions. Results: Abdominal CD68+CD206- ‘pro-inflammatory’ macrophages were slightly higher in AO than CO at baseline but declined in AO only, equalizing between groups after weight loss. Femoral CD68+CD206- macrophages, as well as abdominal and femoral CD68+CD206+ ‘anti-inflammatory’ macrophages and CD3+CD8+ T cells, did not differ between groups at baseline or change after weight loss. Abdominal and femoral CD3+CD4+ T cells—potentially pro- or anti-inflammatory—increased after weight loss in AO but remained unchanged in CO. Discussion: Our findings, though preliminary, do not support the hypothesis that SAT immune cell profiles account for the elevated type 2 diabetes risk in CO. Weight loss appears to alter some immune cell populations in AO but not in CO. The long-term metabolic consequences of these changes—or lack thereof—remain to be determined.