Metabolic surgery improves the unbalanced proportion of peripheral blood myeloid dendritic cells and T lymphocytes in obese patients

Background Obesity is associated with impaired immune function and chronic low-grade inflammation. Metabolic surgery is one of the most effective therapies for treating obesity and related metabolic disorders. We aimed to explore the pathophysiological roles of peripheral dendritic cells (DCs) and T lymphocytes in metabolic surgery. Method In this observational cohort study, a total of 106 individuals, including obese participants with or without T2DM, overweight subjects and normal controls, were recruited. All obese participants underwent laparoscopic sleeve gastrectomy surgery and returned for the evaluation of the clinical indicators after surgery. We evaluated the frequencies of circulating DCs subsets (myeloid (mDCs) and plasmacytoid (pDCs)), the pro-inflammatory (Th1 and Th17) and anti-inflammatory (Th2 and Treg) T cell subsets by flow cytometry. Results Compared with normal controls, the frequencies of mDCs, Th1 and Th17 cells increased, while Treg and Th2 cells decreased in the obese participants. The frequency of mDCs and Th1 cells consistently declined after surgery compared with baseline in the obese patients and were restored to the levels observed in the normal controls after surgery. Moreover, the frequency of Treg cells was increased at 6 months after surgery in the obese patients with T2DM, and Th17 cells declined at 6 months after surgery in the severely obese patients without T2DM. Conclusion This study indicates that metabolic surgery can effectively improve imbalanced immune cells in peripheral blood and restore the proportion of immune cells to a normal range during a 12-month follow-up.