Role And Mechanism Of IL-38 In High Fat Diet-induce Obese In Mice

Objective Obesity is a chronic disease that easily lead to type 2 diabetes,hypertension,fatty liver,and is often accompanied with the development of inflammatory response.Interleukin(IL)-38 is one of the members of IL-1 family.Current studies found that IL-38 can inhibit the expression of inflammatory cytokines in psoriasis arthritis and systemic lupus erythematosus.This study is to clone mouse IL-38 gene and construct the eukaryotic expression vector pcDNA3.1-mIL-38.The role and mechanism of IL-38 in obesity were explored at the cellular and animal levels through 3T3-L1 cell and a high fat-diet-induced mouse obese model.Methods 1.We extracted total RNA from mouse spleen,the gene fragment encoding IL-38 gene was amplified by RT-PCR and connected with pcDNA3.1 vector,both were digested by Kpn?enzyme and Xba?enzyme,then reconnected by T4 DNA ligase and transformed into competent DH5? cells.Recombinant eukaryotic expression vector pcDNA3.1-mIL-38 was thus constructed.2.A high-fat diet-induced mouse obese model was established with ICR mice fed with high faty feed;pcDNA3.1-mIL-38 plasmid was injected into mice by hydrodynamics-based gene delivery.After 16 weeks,mice were executed in order to collect sample.HE staining and oil red O staining were used to detected the size and number of lipid droplets in adipose tissue and liver;intraperitoneal glucose tolerance test and insulin tolerance test were used to detect blood glucose tolerance chances and insulin tolerance of mice;qRT-PCR was applied to detect the expression of tumor necrosis factor(TNF)-?,IL-6,IL-1?,CD68,F4/80 and monocyte chemotactic protein(MCP)-1 in adipose tissues;the serum levels of IL-6,IL-1? and MCP-1 were detected by ELISA.3.3T3-L1 cells were differentiated with or without IL-38.The morphology and size of lipid droplets in3T3-L1 were measured by oil red O staining;the expression levels of GATA-3,GLUT4,PPAR?2,IL-6,IL-1?,and MCP-1 were detected by qRT-PCR;The contents of IL-6,IL-1? and MCP-1 in the cells medium were tested by ELISA.Results1.Eukaryotic expression vector pcDNA3.1-mIL-38 was constructed after mouse IL-38 cDNA was successfully cloned by RT-PCR.2.An obese mice model was constructed as expected.The weight of obese mice was higher than the weight of control group significantly.There was no significantly visible in body weight difference between IL-38-treated group and control group.The obese mice had glucose intolerance and insulin resistance,and the IL-38-treated mice raise the level of glucose tolerance as well as insulin sensitivity;the expression of TNF-?,IL-6,IL-1?,CD68,F4/80,MCP-1 were decreased after IL-38 treatment.3.IL-38 decreased significantly the lipid droplets of 3T3-L1 cell increased the expression of GATA-3 and GLUT4,and inhibited the expression of IL-6,IL-1? and MCP-1 in 3T3-L1 cells.Conclusion In this study,the mouse IL-38 eukaryotic expression vector was successfully constructed and IL-38 was overexpressed in mice by hydrodynamic injection.We found that IL-38 can effectively reduce high-fat diet-induced obesity and inhibit the expression of inflammatory cytokines in obese mice and increase the glucose tolerance and insulin sensitivity.Moreover,IL-38 can inhibit the differentiation of 3T3-L1 cells and the expression of inflammatory cytokines in 3T3-L1 cells.