Asthma improved by aspirin-like drugs

Interleukin-4 in the Generation of the AERD Phenotype: Implications for Molecular Mechanisms Driving Therapeutic Benefit of Aspirin Desensitization

Aspirin-exacerbated respiratory disease (AERD) is explained in part by over-expression of 5-lipoxygenase, leukotriene C4 synthase (LTC₄S) and the cysteinyl leukotriene (CysLT) receptors (CysLT1 and 2), resulting in constitutive over-production of CysLTs and the hyperresponsiveness to CysLTs that occurs with aspirin ingestion. Increased levels of IL-4 have been found in the sinus mucosa and nasal polyps of AERD subjects. Previous studies demonstrated that IL-4 is primarily responsible for the upregulation of LTC4S by mast cells and the upregulation of CysLT1 and 2 receptors on many immune cell types. Prostaglandin E₂ (PGE₂) acts to prevent CysLT secretion by inhibiting mast cell and eosinophil activation. PGE₂ concentrations are reduced in AERD reflecting diminished expression of cyclooxygenase (COX)-2. IL-4 can inhibit basal and stimulated expression of COX-2 and microsomal PGE synthase 1 leading to decreased capacity for PGE₂ secretion. Thus, IL-4 plays an important pathogenic role in generating the phenotype of AERD. This review will examine the evidence supporting this hypothesis and describe a model of how aspirin desensitization provides therapeutic benefit for AERD patients.

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.

CONCLUSION

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.

Summing up 100 years of asthma

In this review, we aim to lead the readers through the historical highlights of pathophysiological concepts and treatment of asthma. Understanding the nature and links of asthma has modeled our diagnostic, pathophysiological and therapeutic thinking and acting. The recognition of its heterogeneous nature in combination with several refined and sophisticated technologies will mark a new era of phenotype-specific approach and treatment of asthma.

Aspirin and salicylates inhibit the IL-4- and IL-13-induced activation of STAT6

Allergic diseases, including asthma, represent a major threat to human health. Over the three last decades, their incidence has risen in western countries. Aspirin treatment has been shown to improve allergic diseases, especially asthma, and the decreased use of aspirin has been hypothesized to contribute to the increase in childhood asthma. Because salicylate compounds suppress a number of enzymatic activities, and signaling through IL-4R participates in the development of allergic responses, we tested the effect of salicylates on IL-4 signal transduction. We found that treatment of cell lines and primary cells with aspirin and salicylates, but not acetaminophen, inhibited the activation of STAT6 by IL-4 and IL-13. This effect correlated with the inhibition of IL-4-induced CD23 expression. Although salicylates inhibited the in vivo activation of Janus kinases, their kinase activity was not affected in vitro by salicylates, suggesting that other kinases were involved in IL-4-induced STAT6 activation. Furthermore, we found that an Src kinase was involved in STAT6 activation because 1) Src kinase activity was induced by IL-4, 2) Src kinase activity, but not Janus kinase, was inhibited by salicylates in vitro, 3) cells expressing viral Src had constitutive STAT6 phosphorylation, and 4) cells lacking Src showed low STAT6 phosphorylation in response to IL-4. Because STAT6 activation by IL-4 and IL-13 participates in the development of allergic diseases, our results provide a mechanism to explain the beneficial effects of aspirin and salicylate treatment of these diseases.

Selective inhibition of interleukin-4 gene expression in human T cells by aspirin

Previous studies indicated that aspirin (acetylsalicylic acid [ASA]) can have profound immunomodulatory effects by regulating cytokine gene expression in several types of cells. This study is the first in which concentrations of ASA in the therapeutic range were found to significantly reduce interleukin (IL)-4 secretion and RNA expression in freshly isolated and mitogen-primed human CD4+ T cells. In contrast, ASA did not affect IL-13, interferon-gamma, and IL-2 expression. ASA inhibited IL-4, but not IL-2, promoter-driven chloramphenicol acetyltransferase expression in transiently transfected Jurkat T cells. The structurally unrelated nonsteroidal anti-inflammatory drugs indomethacin and flurbiprofen did not affect cytokine gene expression in T cells, whereas the weak cyclo-oxygenase inhibitor salicylic acid was at least as effective as ASA in inhibiting IL-4 expression and promoter activity. The inhibitory effect of ASA on IL-4 transcription was not mediated by decreased nuclear expression of the known salicylate target nuclear factor (NF)-kappaB and was accompanied by reduced binding of an inducible factor to an IL-4 promoter region upstream of, but not overlapping, the NF of activated T cells- and NF-kappaB-binding P1 element. It is concluded that anti-inflammatory salicylates, by means of a previously unrecognized mechanism of action, can influence the nature of adaptive immune responses by selectively inhibiting the expression of IL-4, a critical effector of these responses, in CD4+ T cells.

Analgesics, allergy and asthma

Intolerance to analgesics is common in patients with bronchial asthma, nasal polyps and urticaria. Symptoms of intolerance resemble those of allergy, but the events precipitating them can rarely be traced to reactions between the drug and a specific antibody or sensitised T-lymphocytes. In 8 to 20% of adult asthmatics, aspirin and several other analgesics provoke asthmatic attacks, probably through inhibition of cyclo-oxygenase. This is a distinct and important clinical syndrome with a specific history, course and clinical presentation and a number of unique peculiarities which still require elucidation at the biochemical level. Up to 40% of patients with chronic urticaria develop an obvious increase in weals and swelling after taking aspirin. These reactions occur only when urticaria is active, and though the reason for them is not known, it appears that different mechanisms may be responsible in different patients. Skin reactions other than exacerbation of chronic urticaria are less common, but may create serious clinical problems. The clinical background of a patient often determines the type of adverse response to an analgesic. Thus, in certain individuals, analgesics can produce anaphylactic reactions and/or urticaria, probably through an immunological mechanism, while in some asthmatics they precipitate bronchoconstriction, probably through inhibition of bronchial cyclooxygenase. Study of untoward reactions to analgesics not only leads to safer pharmacotherapy, but it also offers a fascinating model for better understanding of some diseases.

Serum 13-14-diOH-15-keto-prostaglandin F2 alpha and airway response to meclofenamate and metaproterenol in relation to the menstrual cycle

In order to evaluate whether adverse reactions to a nonsteroidal antiinflammatory agent (NSAIA) were related to variations in prostaglandin levels during the menstrual cycle, we measured 13-14-diOH-15-keto-prostaglandin F2 alpha in serum and the effect on airways of a single dose of 100 mg oral meclofenamate and 1.5 mg inhaled metaproterenol during the early (follicular phase) and late (luteal phase) menstrual cycle. Among 24 women with premenstrual asthma (PMA), four women with regular asthma (REA), and four healthy women, the 13-14-diOH-15-keto-PGF2 alpha averaged 140.9 +/- 68.4 pg/0.1 ml during the follicular phase but only 14.4 +/- 2.2 pg/0.1 ml during the luteal phase (p less than 0.0001). Acute asthma reactions to the meclofenamate occurred during the follicular phase in six women with PMA but were never observed during the luteal phase (p = 0.016). These reactions occurred preferentially in patients on corticosteroids (p = 0.004). Conversely, one patient with PMA had 18% improvement in FEV1 with meclofenamate during the luteal phase. A placebo-controlled, double-blind evaluation of the healthy women and the women with REA revealed a trend toward improvement in FEV1 during the luteal phase (0.15 less than p less than 0.10) but no change during the follicular phase. The effect of metaproterenol did not vary with the menstrual cycle, and there was no interaction between the effects of meclofenamate and those of metaproterenol. It appears that meclofenamate causes adverse effects on pulmonary function in asthmatic women primarily during the follicular phase of the menstrual cycle. This effect is associated with corticosteroid treatment and may be related to monthly variation in serum 13-14-diOH-15-keto-PGF2 alpha.

Effect of aspirin in "aspirin sensitive" patients

Eighteen patients with a history of urticaria or asthma, or both, induced by aspirin were studied before and after provocation of symptoms with aspirin. The plasma prostaglandin F2 alpha concentration, which was characteristically raised before challenge, fell significantly at the time of adverse reactions. Repeated administration of aspirin up to a dose of 650 mg daily induced tolerance in most of the patients, and several developed bronchodilator responses to aspirin. Although median total IgE concentrations may be raised in patients with aspirin sensitivity, it appears likely that pharmacological rather than immunological mechanisms are chiefly responsible for the phenomena of aspirin sensitivity and desensitisation.

Antipyretic analgesics and the allergic patient

Recent studies of idiosyncratic reactions to analgesics have revealed several clinical patterns with different pathogeneses. In the common type of asthma precipitated by aspirin, inhibition of cyclooxygenase leads to disturbances in the metabolism of arachidonic acid. Drugs that precipitate possibly life-threatening bronchoconstriction and are absolutely contraindicated in patients with aspirin-induced asthma include indomethacin, mefenamic acid, flufenamic and meclofenamic acids, ibuprofen, fenoprofen, ketoprofen, naproxen, diclofenac, amidopyrine, noramidopyrine, phenylbutazone, flumizole, and ditazol. If necessary, patients with aspirin-induced asthma can safely take, even on a long-term basis, salicylamide, dextropropoxyphene, benzydamine, guaiacolic ester of salicylic acid, and chloroquine. In some patients with urticaria/angioedema, symptoms are due to inhibition of cyclooxygenase by analgesics; in others, the cause may be impurities in commercial preparations of aspirin; and in still others, the mechanisms remain unknown.