摘要
Vitamin D_3 has been found to produce therapeutic effects on obesity-associated insulin resistance and dyslipidemia through its potent anti-inflammatory activity, but the precise immunomodulatory mechanism remains poorly understood. In the present study we found that 1,25-dihydroxyvitamin D_3[1,25(OH)_2D_3], the biologically active form of vitamin D_3, significantly attenuated monosodium glutamate(MSG)-induced obesity and insulin resistance as indicated by body weight reduction, oral glucose tolerance improvement, and a glucose infusion rate increase as detected with hyperinsulinemiceuglycemic clamp. Moreover, 1,25(OH)_2D_3 not only restored pancreatic islet functions but also improved lipid metabolism in insulin-targeted tissues. The protective effects of 1,25(OH)_2D_3 on glycolipid metabolism were attributed to its ability to inhibit an obesity-activated inflammatory response in insulin secretory and targeted tissues, as indicated by reduced infiltration of macrophages in pancreas islets and adipose tissue while enhancing the expression of Tgf-β1 in liver tissue, which was accompanied byincreased infiltration of Treg cells in immune organs such as spleen and lymph node as well as in insulintargeted tissues such as liver, adipose, and muscle. Together, our findings suggest that 1,25(OH)_2D_3 serves as a beneficial immunomodulator for the prevention and treatment of obesity or metabolic syndrome through its anti-inflammatory effects.
Vitamin D_3 has been found to produce therapeutic effects on obesity-associated insulin resistance and dyslipidemia through its potent anti-inflammatory activity, but the precise immunomodulatory mechanism remains poorly understood. In the present study we found that 1,25-dihydroxyvitamin D_3[1,25(OH)_2D_3], the biologically active form of vitamin D_3, significantly attenuated monosodium glutamate(MSG)-induced obesity and insulin resistance as indicated by body weight reduction, oral glucose tolerance improvement, and a glucose infusion rate increase as detected with hyperinsulinemiceuglycemic clamp. Moreover, 1,25(OH)_2D_3 not only restored pancreatic islet functions but also improved lipid metabolism in insulin-targeted tissues. The protective effects of 1,25(OH)_2D_3 on glycolipid metabolism were attributed to its ability to inhibit an obesity-activated inflammatory response in insulin secretory and targeted tissues, as indicated by reduced infiltration of macrophages in pancreas islets and adipose tissue while enhancing the expression of Tgf-β1 in liver tissue, which was accompanied byincreased infiltration of Treg cells in immune organs such as spleen and lymph node as well as in insulintargeted tissues such as liver, adipose, and muscle. Together, our findings suggest that 1,25(OH)_2D_3 serves as a beneficial immunomodulator for the prevention and treatment of obesity or metabolic syndrome through its anti-inflammatory effects.
基金
supported by grants from the National Natural Science Foundation of China (81773800 and 81471070)
the CAMS Innovation Fund for Medical Sciences (CIFMS, 2016I2M-1-010 to Xiao-wei Zhang and 2016-I2M-1-012 to Wen Jin)
