ABSTRACT
PURPOSE: Glutamine and arginine modulate inflammatory responses of epithelial cells and monocytes. Here, we studied the response of human mast cells to pharmacological doses of arginine and glutamine. METHODS: Mast cells isolated from intestinal tissue were incubated with physiological doses of arginine (0.1 mmol/L) and glutamine (0.6 mmol/L) or with pharmacological doses of arginine (2 mmol/L) and glutamine (10 mmol/L) for 18 h. Following stimulation by IgE receptor crosslinking mast cell mediators were measured by enzymatic assay, ELISA, multiplex bead immunoassay, or real-time RT-PCR, and activation of intracellular signaling molecules was determined using proteome profiler array or immunoblotting. RESULTS: We found that the combined challenge of mast cells with pharmacological doses of arginine and glutamine caused a decrease in induced release of de novo synthesized leukotriene C(4) but not of pre-stored ß-hexosaminidase. Moreover, we found reduced expression of chemokines monocyte chemoattractant protein-1 (CCL2), macrophage inflammatory protein-1ß (CCL4), IL-8 (CXCL8), and TNF in response to high doses of both amino acids. The anti-inflammatory effects of arginine and glutamine were associated with decreased activation levels of signaling molecules known to be involved in mast cell cytokine expression such as MAPK family members extracellular signal-regulated kinase, c-Jun N-terminal kinase, and p38, and the protein kinase B (Akt). CONCLUSION: Arginine and glutamine attenuate IgE-dependent human mast cell activation by decreasing lipid mediator release and expression of proinflammatory cytokines.
