Publication details
The unique role of dietary L-arginine in the acceleration of peritoneal macrophage sensitivity to bacterial endotoxin.
| Authors | |
|---|---|
| Year of publication | 2013 |
| Type | Article in Periodical |
| Magazine / Source | Immunologic Research |
| MU Faculty or unit | |
| Citation | |
| Doi | http://dx.doi.org/10.1007/s12026-012-8379-2 |
| Field | Immunology |
| Keywords | Macrophages; L-arginine; Lipopolysaccharide; Mitogen-activated protein kinases; Phospholipase C; G-protein-coupled receptor |
| Description | It is known that cells and organisms can indirectly "sense" changes in l-arginine availability via changes in the activity of various metabolic pathways. However, the mechanism(s) by which genes can be directly regulated by l-arginine in mammalian cells have not yet been elucidated. We investigated the effect of l-arginine in the in vivo model of peritoneal inflammation in mice and in vitro in RAW 264.7 macrophages. A detailed analysis of basic physiological functions and selected intracellular signaling cascades revealed that l-arginine is crucial for the acceleration of macrophage activation by bacterial lipopolysaccharide. l-arginine increased the production of reactive oxygen species, nitric oxide, release of Ca2+, as well as inducible nitric oxide synthase expression. Interestingly, the effect of l-arginine on macrophage activation was dependent on the phosphorylation of mitogen-activated protein kinases and activity of phospholipase C. In RAW 264.7 cells, l-arginine was shown to modulate the response of macrophages toward lipopolysaccharide via the activation of G-protein-coupled receptors. According to our data, we concluded that l-arginine availability plays a key role in the initiation of intracellular signaling pathways that trigger the lipopolysaccharide-induced inflammatory responses in murine macrophages. Although macrophages are partially stimulated in the absence of extracellular l-arginine, the presence of this amino acid significantly accelerates the sensitivity of macrophages to bacterial endotoxin. |