The mode of action of aspirin-like drugs: effect on inducible nitric oxide synthase.
Nitric oxide synthesized by inducible nitric oxide synthase (iNOS) has been implicated as a mediator of inflammation in rheumatic and autoimmune diseases. We report that exposure of lipopolysaccharide-stimulated murine macrophages to therapeutic concentrations of aspirin (IC50 = 3 mM) and hydrocortisone (IC50 = 5 microM) inhibited the expression of iNOS and production of nitrite. In contrast, sodium salicylate (1-3 mM), indomethacin (5-20 microM), and acetaminophen (60-120 microM) had no significant effect on the production of nitrite at pharmacological concentrations. At suprapharmacological concentrations, sodium salicylate (IC50 = 20 mM) significantly inhibited nitrite production. Immunoblot analysis of iNOS expression in the presence of aspirin showed inhibition of iNOS expression (IC50 = 3 mM). Sodium salicylate variably inhibited iNOS expression (0-35%), whereas indomethacin had no effect. Furthermore, there was no significant effect of these nonsteroidal anti-inflammatory drugs on iNOS mRNA expression at pharmacological concentrations. The effect of aspirin was not due to inhibition of cyclooxygenase 2 because both aspirin and indomethacin inhibited prostaglandin E2 synthesis by > 75%. Aspirin and N-acetylimidazole (an effective acetylating agent), but not sodium salicylate or indomethacin, also directly interfered with the catalytic activity of iNOS in cell-free extracts. These studies indicate that the inhibition of iNOS expression and function represents another mechanism of action for aspirin, if not for all aspirin-like drugs. The effects are exerted at the level of translational/posttranslational modification and directly on the catalytic activity of iNOS.
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Department of Rheumatology, Hospital for Joint Diseases, New York, NY 10003, USA.
Vyas
P
P
Attur
M
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Leszczynska-Piziak
J
J
Patel
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IR
Weissmann
G
G
Abramson
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SB
D000082:Acetaminophen / Q000494:pharmacology; D000594:Amino Acid Oxidoreductases / Q000037:antagonists & inhibitors / Q000096:biosynthesis* / Q000378:metabolism; D000818:Animals; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000494:pharmacology*; D001241:Aspirin / Q000494:pharmacology*; D002460:Cell Line; D002474:Cell-Free System; D015232:Dinoprostone / Q000096:biosynthesis; D004305:Dose-Response Relationship, Drug; D003576:Electron Transport Complex IV / Q000096:biosynthesis / Q000378:metabolism; D004790:Enzyme Induction; D015870:Gene Expression / Q000187:drug effects*; D006854:Hydrocortisone / Q000494:pharmacology; D007213:Indomethacin / Q000494:pharmacology*; D007700:Kinetics; D008070:Lipopolysaccharides / Q000494:pharmacology; D008264:Macrophages; D051379:Mice; D019001:Nitric Oxide Synthase; D012980:Sodium Salicylate / Q000494:pharmacology*
D000894:Anti-Inflammatory Agents, Non-Steroidal; D008070:Lipopolysaccharides; D000082:Acetaminophen; D019001:Nitric Oxide Synthase; D000594:Amino Acid Oxidoreductases; D003576:Electron Transport Complex IV; D015232:Dinoprostone; D001241:Aspirin; D006854:Hydrocortisone; D012980:Sodium Salicylate; D007213:Indomethacin