Human neutrophil-derived histamine-releasing activity (HRA-N) causes the release of serotonin but not arachidonic acid metabolites from rat basophilic leukemia cells

Inflammatory patterns of allergic and nonallergic rhinitis

Rhinitis is a chronic condition of the nasal mucosa that affects a large segment of the population. The symptoms of rhinitis occur in a variety of sinonasal conditions, which may be broadly classified as allergic (seasonal or perennial) or nonallergic (infectious or a number of noninfectious etiologies) based on the presence or absence of atopy. The cytokine profile and inflammatory patterns underlying these two conditions vary because of certain differences in their pathophysiology as discussed in this review.

Direct evidence for a role of the mast cell in the nasal response to aspirin in aspirin-sensitive asthma

BACKGROUND

A subset of patients with asthma experience adverse nasoocular reactions after ingestion of aspirin or agents that inhibit cyclooxygenase. Recent evidence has implicated the leukotrienes in the nasoocular reaction, but the cellular sources and mechanism of activation are unknown. We used nasal lavage with and without a 5-lipoxygenase inhibitor, zileuton, to define the role of leukotrienes and to profile nasal cellular activation during this reaction.

METHODS

A group of eight patients with asthma shown to have adverse reactions to aspirin documented by a 15% or greater decrease in forced expiratory volume in 1 second, accompanied by an elevation in urinary leukotriene E4 after ingestion of aspirin, received aspirin or placebo in a study with a crossover design. Nasal symptoms and nasal tryptase, histamine, leukotriene, and eosinophil cationic protein levels were evaluated. Serum tryptase and urinary histamine levels were also assessed. Subjects were then randomized to receive a week of treatment with zileuton or placebo, according to a double-blind, crossover design followed by aspirin challenge and measurement of the same mediators.

RESULTS

Aspirin ingestion produced a marked increase in nasal symptoms from a baseline symptom score of 2.1 +/- 0.7 to a maximum of 8.4 +/- 1.2 (p < 0.0007). Aspirin ingestion produced a mean maximal increase in nasal tryptase of 3.5 +/- 2.6 ng/ml, whereas placebo ingestion produced a mean maximal increase of 0.1 +/- 0.2 ng/ml (p < 0.05, aspirin vs placebo). Mean maximal nasal histamine increased 1.73 +/- 1.16 ng/ml versus 0.08 +/- 0.08 ng/ml from baseline (p < 0.05, aspirin vs placebo). Aspirin produced a mean maximal increase in nasal leukotriene value of 152 pg/ml versus a 16 pg/ml decrease after placebo ingestion (p < 0.05). Zileuton treatment blocked the increase in nasal symptoms after aspirin ingestion (maximum nasal symptom score of 1.6 +/- 0.6 with zileuton vs 5.5 +/- 0.9 with placebo [p < 0.0053]). It also blocked the rise in nasal tryptase (p = 0.011) and nasal leukotriene (p < 0.05) levels after aspirin ingestion. Zileuton treatment had no significant effect on the recovery of nasal histamine.

CONCLUSION

The increase in nasal symptoms in aspirin-sensitive patients with asthma after aspirin ingestion is associated with increases in nasal tryptase, histamine, and cysteinyl leukotriene levels. This mediator profile is consistent with mast cell activation during the nasal response to aspirin and suggests that 5-lipoxygenase products are essential for the nasal response to aspirin.

Effects of inhibitors of arachidonic acid metabolism on serotonin release from rat basophilic leukemia cells

Mast cells can release arachidonic acid (AA) metabolites as well as preformed mediators with IgE mediated stimulation, and these mediators are considered to play an important role in allergic reactions. The coincident release of preformed mediators and AA metabolites suggests that AA metabolism is related to mast cell degranulation. To clarify the relationship between mast cell degranulation and AA metabolism, the effects of various A cascade inhibitors on rat basophilic leukemia cell (RBL) mediator release induced by either anti-IgE or A23187 were examined. 5,8,11,14-eicosatetraynoic acid (ETYA) inhibited both PGD2 and LTC4/D4 generation, and partially inhibited serotonin release. Nordihydroguaiaretic acid (NDGA) caused complete inhibition of LTC4/D4 generation, and partial inhibition of PGD2 generation and serotonin release. The cyclooxygenase inhibitor, indomethacin, and the specific 5-lipoxygenase inhibitor, L-651,392 completely inhibited PGD2 and LTC4/D4 generation, respectively, without affecting release of other mediators. Both PGD2 and LTC4/D4 generation were abolished by the combination of indomethacin and L-651,392, however, serotonin release remained intact. HPLC analysis showed that no shift to other AA metabolites occurred after the treatment with these inhibitors. Mepacrine, a phospholipase A2 inhibitor, completely inhibited PGD2 and LTC4/D4 generation, as well as AA release itself, without affecting serotonin release. Therefore, neither AA metabolism nor AA release is necessary for RBL degranulation.

Platelet-activating factor stimulates eicosanoid production in cultured feline tracheal explants

Eicosanoids have been shown to be major mediators of airway inflammation. Platelet-activating factor (PAF), a potent bronchoconstrictor and stimulator of respiratory mucous secretion, may mediate some of its effects via eicosanoid production. To explore eicosanoid generation by cultured feline tracheal explants, eicosanoids were measured following PAF stimulation. After labeling the explants with [3H]arachidonic acid, supernatant from control and PAF treated explants was fractionated by reverse phase high-performance liquid chromatography (HPLC). The resulting elution pattern suggested the release of arachidonic acid (AA), 15-hydroxyeicosatetraenoic acid (HETE), leukotriene (LT)B4, C4, prostaglandin (PG) D2/E2/F2 alpha, and 6-keto-PGF1 alpha. Radioimmunoassay (RIA) following HPLC resolution confirmed that PAF induced a significantly increased release of peptido-leukotrienes, PGD2, PGE2, PGF2 alpha, LTB4, and 5-HETE, as well as thromboxane (TX) B2. The most remarkable increase was LTC4/D4/E4 (15 x control) and PGD2 (4 x control). The PAF antagonist Ro 19-3704 had an inhibitory effect on the PAF-stimulated release of peptido-leukotrienes. We conclude that PAF stimulates the production of a variety of lipoxygenase and cyclooxygenase pathway metabolites in feline airways.