l-Arginine Availability Modulates Local Nitric Oxide Production and Parasite Killing in Experimental Trypanosomiasis
AUTOR(ES)
Gobert, Alain P.
FONTE
American Society for Microbiology
RESUMO
Nitric oxide (NO) is an important effector molecule of the immune system in eliminating numerous pathogens. Peritoneal macrophages from Trypanosoma brucei brucei-infected mice express type II NO synthase (NOS-II), produce NO, and kill parasites in the presence of l-arginine in vitro. Nevertheless, parasites proliferate in the vicinity of these macrophages in vivo. The present study shows that l-arginine availability modulates NO production. Trypanosomes use l-arginine for polyamine synthesis, required for DNA and trypanothione synthesis. Moreover, arginase activity is up-regulated in macrophages from infected mice from the first days of infection. Arginase competes with NOS-II for their common substrate, l-arginine. In vitro, arginase inhibitors decreased urea production, increased macrophage nitrite production, and restored trypanosome killing. In vivo, a dramatic decrease in l-arginine concentration was observed in plasma from infected mice. In situ restoration of NO production and trypanosome killing were observed when excess l-arginine, but not d-arginine or l-arginine plus Nω-nitro-l-arginine (a NOS inhibitor), was injected into the peritoneum of infected mice. These data indicate the role of l-arginine depletion, induced by arginase and parasites, in modulating the l-arginine–NO pathway under pathophysiological conditions.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=98402Documentos Relacionados
- Regulation of L-arginine transport and nitric oxide release in superfused porcine aortic endothelial cells.
- Formation of free nitric oxide from l-arginine by nitric oxide synthase: direct enhancement of generation by superoxide dismutase.
- Evidence for cytokine-inducible nitric oxide synthesis from L-arginine in patients receiving interleukin-2 therapy.
- Evidence for cytokine-inducible nitric oxide synthesis from L-arginine in patients receiving interleukin-2 therapy
- Diabetes and insulin-induced stimulation of L-arginine transport and nitric oxide synthesis in rabbit isolated gastric glands.