Weight loss independent changes in adipose tissue macrophage and T cell populations after sleeve gastrectomy in mice

OBJECTIVE: In addition to adipocytes, adipose tissue contains large numbers of immune cells. A wide range of evidence links the activity of these cells to regulation of adipocyte and systemic metabolic function. Bariatric surgery improves several aspects of metabolic derangements and at least some of these effects occur in a weight-loss independent manner. We sought to investigate the impact of vertical sleeve gastrectomy (VSG) on adipose immune cell frequencies. METHODS: We analyzed the frequencies of immune cells within distinct adipose tissue depots in obese mice that had VSG or sham surgery with a portion of the latter group pair-fed such that their body mass was matched to the VSG animals. RESULTS: We demonstrate that VSG induced a shift in the epididymal adipose tissue leukocyte profile including increased frequencies of CD11c(−) macrophages, increased frequencies of T cells (CD4(+), CD8(+), and CD4(−)/CD8(−) T cells all increased), but a significantly decreased frequency of adipose tissue dendritic cells (ATDC) that, despite the continued high fat feeding of the VSG group, dropped below control diet levels. CONCLUSIONS: These results indicate that VSG induces substantial changes in the immune populations residing in the adipose depots independent of weight loss.