title: Inosine inhibits inflammatory cytokine production by a posttranscriptional mechanism and protects against endotoxin-induced shock.
abstract: Extracellular purines, including adenosine and ATP, are potent endogenous immunomodulatory molecules. Inosine, a degradation product of these purines, can reach high concentrations in the extracellular space under conditions associated with cellular metabolic stress such as inflammation or ischemia. In the present study, we investigated whether extracellular inosine can affect inflammatory/immune processes. In immunostimulated macrophages and spleen cells, inosine potently inhibited the production of the proinflammatory cytokines TNF-alpha, IL-1, IL-12, macrophage-inflammatory protein-1alpha, and IFN-gamma, but failed to alter the production of the anti-inflammatory cytokine IL-10. The effect of inosine did not require cellular uptake by nucleoside transporters and was partially reversed by blockade of adenosine A1 and A2 receptors. Inosine inhibited cytokine production by a posttranscriptional mechanism. The activity of inosine was independent of activation of the p38 and p42/p44 mitogen-activated protein kinases, the phosphorylation of the c-Jun terminal kinase, the degradation of inhibitory factor kappaB, and elevation of intracellular cAMP. Inosine suppressed proinflammatory cytokine production and mortality in a mouse endotoxemic model. Taken together, inosine has multiple anti-inflammatory effects. These findings, coupled with the fact that inosine has very low toxicity, suggest that this agent may be useful in the treatment of inflammatory/ischemic diseases.
authors.affiliation: Inotek Corp., Beverly, MA 01915, USA. ghasko@inotekcorp.com
authors.forename: G
authors.initials: G
authors.lastname: Haskó
authors.forename: D G
authors.initials: DG
authors.lastname: Kuhel
authors.forename: Z H
authors.initials: ZH
authors.lastname: Németh
authors.forename: J G
authors.initials: JG
authors.lastname: Mabley
authors.forename: R F
authors.initials: RF
authors.lastname: Stachlewitz
authors.forename: L
authors.initials: L
authors.lastname: Virág
authors.forename: Z
authors.initials: Z
authors.lastname: Lohinai
authors.forename: G J
authors.initials: GJ
authors.lastname: Southan
authors.forename: A L
authors.initials: AL
authors.lastname: Salzman
authors.forename: C
authors.initials: C
authors.lastname: Szabó
mesh_terms: D000818:Animals; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000008:administration & dosage / Q000494:pharmacology; D018925:Chemokines / Q000037:antagonists & inhibitors / Q000096:biosynthesis; D016207:Cytokines / Q000037:antagonists & inhibitors* / Q000096:biosynthesis; D004789:Enzyme Activation / Q000187:drug effects / Q000276:immunology; D020672:I-kappa B Proteins / Q000378:metabolism; D007166:Immunosuppressive Agents / Q000494:pharmacology*; D018836:Inflammation Mediators / Q000037:antagonists & inhibitors* / Q000378:metabolism; D007274:Injections, Intraperitoneal; D007288:Inosine / Q000008:administration & dosage / Q000494:pharmacology*; D007371:Interferon-gamma / Q000037:antagonists & inhibitors / Q000096:biosynthesis; D048031:JNK Mitogen-Activated Protein Kinases; D008070:Lipopolysaccharides / Q000633:toxicity*; D008262:Macrophage Activation / Q000187:drug effects; D017737:Macrophages, Peritoneal / Q000187:drug effects / Q000201:enzymology / Q000276:immunology / Q000378:metabolism; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D011499:Protein Processing, Post-Translational / Q000187:drug effects* / Q000276:immunology; D058906:Purinergic P1 Receptor Agonists; D018047:Receptors, Purinergic P1 / Q000502:physiology; D012772:Shock, Septic / Q000209:etiology / Q000276:immunology* / Q000473:pathology / Q000517:prevention & control*; D018417:Th1 Cells / Q000187:drug effects / Q000378:metabolism
chemical_list: D000894:Anti-Inflammatory Agents, Non-Steroidal; D018925:Chemokines; D016207:Cytokines; D020672:I-kappa B Proteins; D007166:Immunosuppressive Agents; D018836:Inflammation Mediators; D008070:Lipopolysaccharides; D058906:Purinergic P1 Receptor Agonists; D018047:Receptors, Purinergic P1; D007288:Inosine; D007371:Interferon-gamma; D048031:JNK Mitogen-Activated Protein Kinases; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases