Mechanism of glutamine downregulates the cytokine expression in lipopolysaccharide-stimulated human peripheral blood mononuclear cells

Abstract

To investigate the mechanism that glutamine (Gln) downregulates the cytokine expression in lipopolysaccharide (LPS)-stimulated human peripheral blood mononuclear cells (PMBCs). PMBCs were extracted from healthy volunteer by density gradient centrifugation, the cells were divided into two parts. The first part of PMBCs was pretreated with Gln of the concentration of 0, 8, 15 mmol/L for 0.5 h and 2.0 h respectively, then stimulated by LPS for 4.0 h. Cells and supernatants were collected. The second part of PBMCs was divided into group A, B and C. Group A and B were pretreated with HSP70 blocker (Quercetin) for 1.0 h, then were stimulated by LPS for 4.0 h. Cells and supernatants were also collected. The release of TNF-alpha and IL-10 was analyzed via enzyme-linked immunosorbent assay (ELISA) and HSP70 via Western Blot. In this experiment, the effect of Quercetin on TNF-alpha, IL-10 and HSP70 expression in human PBMCs was assessed. Gln led to an increase in HSP70 expression, and decreased TNF-alpha, IL-10 release at 4.0 h after LPS stimulation when 8 mmol/L glutamine pretreated for 0.5 h and 2.0 h, 15 mmol/L glutamine pretreated for 0.5 h (P < 0.05). The expression level of HSP70 was significantly decreased, however, the expression of TNF-alpha and IL-10 was enhanced in Quercetin group (P < 0.05). The effect of glutamine attenuating cytokine release in PBMCs is related to the enhancement of HSP70 expression.