Modulation by aspirin of nuclear phospho-signal transducer and activator of transcription 6 expression: Possible role in therapeutic benefit associated with aspirin desensitization.
BACKGROUND
Aspirin-exacerbated respiratory disease is characterized by asthma, nasal polyps, and intolerance to aspirin with overexpression of leukotriene (LT) C(4) synthase and cysteinyl leukotriene receptors. Through an unknown mechanism, aspirin desensitization is an effective treatment.


OBJECTIVE
We hypothesized that aspirin desensitization blocks IL-4-induced expression of these LT activities through inhibition of signal transducer and activator of transcription 6 (STAT6)-mediated transcription.


METHODS
Nuclear extracts were derived from THP-1 and normal human monocytes resting and cocultured with aspirin before IL-4 stimulation. Quantitative PCRs were conducted. Electrophoretic mobility shift assays were performed by using oligomers for STAT6 sites within the LT receptor and synthase promoters. Western blots of nuclear extracts were probed by using anti-phospho-STAT6 antibodies.


RESULTS
Upregulation of LT receptor mRNA by IL-4 was negated by aspirin and ketorolac but not by sodium salicylate. The STAT6 site in the LT receptor and synthase promoters was confirmed by using mobility shift assays by competing with unlabeled STAT6 consensus probes and supershifts with anti-STAT6 antibodies. Aspirin and ketorolac decreased the IL-4-inducible expression of nuclear STAT6 observed in mobility shift assays and Western hybridization.


CONCLUSIONS
The LT receptor and synthase promoters have STAT6-binding sites that are engaged by IL-4-induced nuclear extracts and inhibited by aspirin. Assuming that normal monocytes behave like monocytes from patients with aspirin-exacerbated respiratory disease, inhibition of IL-4-STAT6 might explain a mechanism in aspirin desensitization daily treatment, resulting in downregulation of production and responsiveness to cysteinyl leukotrienes. This biologic activity of aspirin likely reflects COX inhibition because it was shared with ketorolac but not sodium salicylate.
Steinke
John W
JW
Carter Immunology Center, Asthma and Allergic Disease Center, University of Virginia Health System, Charlottesville, Va., USA.
Culp
Jeffrey A
JA
Kropf
Elizabeth
E
Borish
Larry
L
D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000009:adverse effects / Q000494:pharmacology*; D001241:Aspirin / Q000009:adverse effects / Q000494:pharmacology*; D001249:Asthma / Q000276:immunology*; D002460:Cell Line; D051546:Cyclooxygenase 2 / Q000187:drug effects / Q000378:metabolism; D003888:Desensitization, Immunologic; D004342:Drug Hypersensitivity / Q000276:immunology*; D015870:Gene Expression / Q000187:drug effects / Q000502:physiology; D005982:Glutathione Transferase; D006801:Humans; D015847:Interleukin-4 / Q000494:pharmacology; D019746:Intramolecular Oxidoreductases / Q000037:antagonists & inhibitors / Q000378:metabolism; D020910:Ketorolac / Q000494:pharmacology; D009000:Monocytes / Q000187:drug effects / Q000276:immunology / Q000378:metabolism; D000071876:Prostaglandin-E Synthases; D018077:Receptors, Leukotriene / Q000187:drug effects / Q000378:metabolism; D050800:STAT6 Transcription Factor / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology; D012980:Sodium Salicylate / Q000494:pharmacology; D015854:Up-Regulation / Q000187:drug effects / Q000502:physiology
D000894:Anti-Inflammatory Agents, Non-Steroidal; C508598:IL4 protein, human; D018077:Receptors, Leukotriene; D050800:STAT6 Transcription Factor; C494101:STAT6 protein, human; D015847:Interleukin-4; D051546:Cyclooxygenase 2; C496540:PTGS2 protein, human; D005982:Glutathione Transferase; C041116:leukotriene-C4 synthase; D019746:Intramolecular Oxidoreductases; D000071876:Prostaglandin-E Synthases; C083169:leukotriene D4 receptor; D001241:Aspirin; D012980:Sodium Salicylate; D020910:Ketorolac