Interleukin-38 inhibits adipogenesis and inflammatory cytokine production in 3T3-L1 preadipocytes

Interleukin-38 (IL-38) is a novel member of the IL-1 cytokine family with anti-inflammatory activity. However, its effect on adipogenesis and inflammatory cytokines secretion of adipocytes in vitro has not been reported. To address whether IL-38 inhibits adipogenesis and inflammation in vitro, adipose precursor 3T3-L1 cells were cultured with or without IL-38. The morphology and size of lipid droplets in 3T3-L1 cells were measured by Oil red O staining. The mRNA expression levels of GATA-binding protein-3 (GATA-3), glucose transporter type 4 (GLUT4), peroxisome proliferator-associated receptor gamma 2, IL-1 beta, IL-6, and monocyte chemoattractant protein-1 (MCP-1) in 3T3-L1 cells were detected by real-time PCR, The contents of IL-6, IL-1 beta, and MCP-1 in 3T3-L1 cell medium supernatants were determined by enzyme-linked immunosorbent assay. IL-38 significantly decreased the number of lipid droplets in 3T3-L1 cells. IL-38 also increased GATA-3 and GLUT4 mRNA expression and inhibited IL-1 beta, IL-6, and MCP-1 secretion by 3T3-L1 cells. It is concluded that IL-38 can inhibit the differentiation of human adipocytes and inflammatory cytokine production by 3T3-L1 cells.