Different Effect of Glutamine on Macrophage Tumor Necrosis Factor-alpha Release and Heat Shock Protein 72 Expression in Vitro and in Vivo

Macrophage plays a vital role in sepsis. However, the modulatory effect of glutamine (Gln) on macrophage/ monocyte-mediate cytokines release is still controversial. Thus, we investigated the effect of Gln on macrophage tumor necrosis factor (TNF)-alpha release and heat shock protein (HSP) 72 expression in vivo and in vitro. Data from our study indicated that the increase of HSP72 expression was significant at 8 mM of Gln 4 h after lipopolysaccharide (LPS) stimulation and became independent of Gln concentrations at 24 h, whereas TNF-alpha release was dose- and time-dependent on Gln. Heat stress (HS) induced more HSP72 and less TNF-alpha production compared with the non-HS group. However, the production of TNF-alpha in cells pretreated with HS was increased with increasing concentrations of Gln. Treatment with various concentrations of Gln for 1 h and then 0.5 mM Gln for 4 h led to an increase in HSP72 expression, but not in TNF-alpha production. In sepsis model mice, Gln treatment led to a significantly lower intracellular TNF-alphalevel and an increase in HSP72 expression in mouse peritoneal macrophages. Our results demonstrate that Gln directly increases TNF-alpha release of LPS-stimulated RAW264.7 macrophages in a dose-dependent manner, and also decreases mouse peritoneal macrophages TNF-a release in the sepsis model. Taken together, our data suggest that there may be more additional pathways by which Gln modulates cytokine production besides HSP72 expression in macrophage during sepsis.