Circulating exosome-like vesicles of humans with nondiabetic obesity impaired islet β-cell proliferation, which was associated with decreased Omentin-1 protein cargo

The regulation of beta-cell mass in the status of nondiabetic obesity remains not well understood. We aimed to investigate the role of circulating exosome-like vesicles (ELVs) isolated from humans with simple obesity in the regulation of islet beta-cell mass. Between June 2017 and July 2019, 81 subjects with simple obesity and 102 healthy volunteers with normal weight were recruited. ELVs were isolated by ultra-centrifugation. The proliferations of beta-cells and islets were measured by 5-ethynl-20-deoxyuridine (EdU). Protein components in ELVs were identified by Quantitative Proteomic Analysis and verified by Western blot and ELISA. The role of specific exosomal protein was analyzed by gain-of-function approach in ELVs released by 3T3-L1 preadipocytes. Circulating ELVs from subjects with simple obesity inhibited beta-cell proliferation in vitro without affecting its apoptosis, secretion, and inflammation. The protein levels of Rictor and Omentin-1 were downregulated in circulating ELVs from subjects with simple obesity and associated with the obesity-linked pathologic conditions. The ELV-carried Omentin-1 and Omentin-1 protein per se were validated to increase beta-cell proliferation and activate Akt signaling pathway. Moreover, Omentin-1 in ELVs was downregulated by insulin. The circulating ELVs may act as a negative regulator for beta-cell mass in nondiabetic obesity through inhibiting beta-cell proliferation. This effect was associated with downregulated Omentin-1 protein in ELVs. This newly identified ELV-carried protein could be a mediator linking insulin resistance to impaired beta-cell proliferation and a new potential target for increasing beta-cell mass in obesity and T2DM. Copyright (C) 2021, Chongqing Medical University. Production and hosting by Elsevier B.V.

Automated summary

This study aimed to investigate the role of circulating exosome-like vesicles (ELVs) isolated from individuals with simple obesity in the regulation of beta-cell mass. The results showed that circulating ELVs can act as negative regulators for beta-cell mass in nondiabetic obesity by inhibiting beta-cell proliferation. This effect is associated with downregulated Omentin-1 protein in ELVs.