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

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 percentages 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 percentages 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.