Continuous Stimulation of Subcutaneously Implanted Xenogeneic Protein Thread Recruited Treg Cells and M2 Macrophages to Induce Inguinal White Adipose Tissue Browning

Brown adipose tissue and beige adipose tissue have emerged as potential targets for obesity intervention, but the present strategies targeting at inducing the browning of white adipose tissue are not satisfactory. Xenogeneic protein thread implantation is an attempt of complementary and alternative medicine in the field of obesity treatment, but the specific effect or mechanism has not been well validated. This study examined the corrective effect of subcutaneous catgut or absorbable polymer thread embedding on obesity and metabolic syndrome, and aimed to explore the mechanism of subcutaneous white adipose tissue browning after catgut embedding. Embedding of catgut reduced weight gain and improved metabolic status in ob/ob mice. Browning of bilateral inguinal WAT was induced after catgut embedding, with massive infiltration of Treg cells and M2 macrophages in the tissue slices of fat pads. IL-10 and TGF-β released by Treg cells targeted the macrophages and the induced M2 macrophages promoted the secretion of norepinephrine in sympathetic nervous system, leading to the activation of β3-AR related pathways in adipocytes. This study demonstrates abdominal subcutaneous catgut embedding has the potential to combat obesity through inducing the browning of WAT mediated by the infiltrated Treg cells and macrophages.