AUTHOR=Tang Chun-lian , Yu Xiao-hong , Li Yan , Zhang Rong-hui , Xie Jun , Liu Zhi-ming 

TITLE=Schistosoma japonicum Soluble Egg Antigen Protects Against Type 2 Diabetes in Leprdb/db Mice by Enhancing Regulatory T Cells and Th2 Cytokines

JOURNAL=Frontiers in Immunology

VOLUME=10

YEAR=2019

URL=https://www.frontiersin.org/journals/immunology/articles/10.3389/fimmu.2019.01471

DOI=10.3389/fimmu.2019.01471

ISSN=1664-3224

ABSTRACT=<p>Type 2 diabetes is a metabolic disorder characterized by persistently elevated glucose levels. There is no effective treatment strategy for this condition, and it poses a massive economic burden globally. <italic>Schistosoma</italic> soluble egg antigen (SEA)-induced immunomodulatory mechanisms have been reported in the treatment of autoimmune disease. This study aimed to determine the ability of <italic>Schistosoma japonicum</italic> SEA to protect against type 2 diabetes in <italic>Lep</italic>r<sup><italic>db</italic>/<italic>db</italic></sup> mice and understand the associated mechanisms. The mice were divided into four groups: C57BL/6 (the normal group), SEA (C57BL/6 mice treated with SEA), <italic>Lep</italic>r<sup><italic>db</italic>/<italic>db</italic></sup>, and SEA and <italic>Lep</italic>r<sup><italic>db</italic>/<italic>db</italic></sup> co-treatment groups. The mice in the SEA and co-treatment groups were injected with 50 μg of SEA (twice a week for 6 weeks), and the same volume of PBS was used as control. Blood glucose, insulin, and HOMA-IR levels were measured in all mice, which were sacrificed 6 weeks after the last SEA administration. Flow cytometry was used to detect the percentages of regulatory T cells in splenocytes. ELISA was used to detect the levels of IFN-γ, IL-2, IL-4, and IL-5 in cell culture supernatants. Compared with the mice in the <italic>Lep</italic>r<sup><italic>db</italic>/<italic>db</italic></sup> group, the mice in the SEA + <italic>Lep</italic>r<sup><italic>db</italic>/<italic>db</italic></sup> group exhibited significantly reduced insulin resistance, as evidenced by the enhancement of wound healing. The frequency of spleen regulatory T cells increased significantly after SEA administration; meanwhile, the secretion of IL-4 and IL-5 in spleen cells was elevated. These results indicate that SEA can reduce insulin resistance and provide new targets for the treatment of type 2 diabetes. The potential mechanisms might be associated with increases in regulatory T cells and Th2 cytokines in <italic>Lep</italic>r<sup><italic>db</italic>/<italic>db</italic></sup> mice, which warrants further investigation.</p>