title: Macrophage inflammatory protein-1 alpha production in lipopolysaccharide-stimulated human adherent blood mononuclear cells is inhibited by the nitric oxide synthase inhibitor N(G)-monomethyl-L-arginine.
abstract: The release of chemokines such as macrophage-inflammatory protein-1 alpha (MIP-1 alpha) from activated macrophages is a crucial step in cell recruitment necessary for establishing local inflammatory responses. To ascertain the importance of the L-arginine/nitric oxide (NO) pathway in LPS-induced MIP-1 alpha release, we stimulated human adherent PBMC with LPS in the presence of the NO synthase inhibitor N(G)-monomethyl-L-arginine (L-NMMA). L-NMMA decreased LPS-induced MIP-1 alpha protein release (45.5% inhibition) and steady state levels of mRNA (48% inhibition) in adherent PBMC. The concentration of L-NMMA for inhibition of MIP-1 alpha release was dependent on the concentration of L-arginine in the cell culture medium, emphasizing the L-arginine-related action of the drug. Most of the MIP-1 alpha release was attributed to the activity of IL-1 and TNF, since coincubation of LPS-stimulated PBMC with IL-1R antagonist and TNF-binding protein abrogated LPS-induced MIP-1 alpha release (by 76.8%). Analysis of cytokine secretion revealed that, in addition to MIP-1 alpha, L-NMMA inhibited the release of mature IL-1 beta (by 70%) and TNF-alpha (by 53%). In contrast, release of macrophage chemoattractant protein-1 was unaffected; IL-10 was augmented (123.4%) by L-NMMA. In the presence of exogenous NO provided by NO donors, LPS-induced MIP-1 alpha release was enhanced. We concluded that endogenous NO acts as a mediator of inflammation. Since IL-10 is a potent anti-inflammatory cytokine, these data also suggest that L-NMMA acts as an anti-inflammatory agent by specifically altering the balance of pro- and anti-inflammatory cytokines released from LPS-stimulated human PBMC.
authors.affiliation: Division of Infectious Diseases, University of Colorado Health Sciences Center, Denver 80262, USA.
authors.forename: H
authors.initials: H
authors.lastname: Mühl
authors.forename: C A
authors.initials: CA
authors.lastname: Dinarello
mesh_terms: D000818:Animals; D001120:Arginine / Q000378:metabolism; D002448:Cell Adhesion / Q000276:immunology; D002460:Cell Line; D018932:Chemokine CCL2 / Q000096:biosynthesis; D054407:Chemokine CCL4; D018946:Chemokine CCL5 / Q000096:biosynthesis; D005786:Gene Expression Regulation / Q000187:drug effects / Q000276:immunology; D006801:Humans; D007375:Interleukin-1 / Q000378:metabolism / Q000502:physiology; D016753:Interleukin-10 / Q000378:metabolism / Q000494:pharmacology; D016209:Interleukin-8 / Q000096:biosynthesis; D007963:Leukocytes, Mononuclear / Q000201:enzymology / Q000378:metabolism*; D008070:Lipopolysaccharides / Q000494:pharmacology*; D019402:Macrophage Inflammatory Proteins / Q000096:biosynthesis* / Q000235:genetics / Q000378:metabolism; D051379:Mice; D009569:Nitric Oxide / Q000502:physiology; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors* / Q000378:metabolism; D013379:Substrate Specificity; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism / Q000502:physiology; D019323:omega-N-Methylarginine / Q000494:pharmacology*
chemical_list: D018932:Chemokine CCL2; D054407:Chemokine CCL4; D018946:Chemokine CCL5; D007375:Interleukin-1; D016209:Interleukin-8; D008070:Lipopolysaccharides; D019402:Macrophage Inflammatory Proteins; D014409:Tumor Necrosis Factor-alpha; D016753:Interleukin-10; D019323:omega-N-Methylarginine; D009569:Nitric Oxide; D001120:Arginine; D019001:Nitric Oxide Synthase