Genetic variants of the arachidonic acid pathway in non-steroidal anti-inflammatory drug-induced acute urticaria.

BACKGROUND: To date, genetic studies of hypersensitivity reactions to non-steroidal anti-inflammatory drugs (NSAIDs) have been carried out mainly in aspirin-induced asthma and to a lesser extent in chronic urticaria, with no studies in patients with acute urticaria (AU), the most common entity induced by these drugs. OBJECTIVE: In this work, we analysed the association of common variants of 15 relevant genes encoding both enzymes and receptors from the arachidonic acid (AA) pathway with NSAID-induced AU. METHODS: Patients were recruited in several Allergy Services that are integrated into the Spanish network RIRAAF, and diagnosed of AU induced by cross-intolerance (CRI) to NSAIDs. Genotyping was carried out by TaqMan allelic discrimination assays. RESULTS: A total of 486 patients with AU induced by CRI to NSAIDs and 536 unrelated controls were included in this large Spanish case-control study. Seven variants from 31 tested in six genes were associated in a discovery study population from Malaga (0.0003 ≤ p-value ≤ 0.041). A follow-up analysis in an independent sample from Madrid replicated three of the SNPs from the ALOX15 (rs7220870), PTGDR (rs8004654) and CYSLTR1 (rs320095) genes (1.055x10(-6) ≤meta-analysis p-value ≤ 0.003). CONCLUSIONS AND CLINICAL RELEVANCE: Genetic variants of the AA pathway may play an important role in NSAID-induced AU. These data may help understand the mechanism underlying this disease.

Response to a selective COX-2 inhibitor in patients with urticaria/angioedema induced by nonsteroidal anti-inflammatory drugs.

BACKGROUND: In subjects with hypersensitivity reactions with cross-intolerance to nonsteroidal anti-inflammatory drugs (NSAIDs), tolerance to selective COX-2 inhibitors has not been evaluated in large series of well-phenotyped cases. METHODS: We evaluated 252 patients with urticaria and/or angioedema caused by hypersensitivity owing to cross-intolerance to NSAIDs. In addition to the clinical history, diagnosis was confirmed by provocation to an alternative NSAID. Two groups were considered: (A) patients with cross-intolerance to NSAIDs and intolerance to paracetamol and (B) patients with cross-intolerance to NSAIDs and good tolerance to paracetamol. Etoricoxib was administered to Group A patients and to a representative sample of Group B patients. In the event of a positive response, serum tryptase levels were determined and skin biopsy was performed in five patients in each group. RESULTS: Ibuprofen was the most commonly implicated drug, followed by acetylsalicylic acid (ASA). Urticaria was the most common manifestation, followed by angioedema. Most of the patients developed symptoms within 1 h. Twenty-five percent in Group A (n = 47) and 6% in Group B (n = 50) were intolerant to etoricoxib. Skin biopsy showed mast cell activation with the release of tryptase to the extracellular space but without the increase in serum tryptase levels. CONCLUSION: Selective COX-2 inhibitors may be unsafe in subjects with urticaria and/or angioedema caused by hypersensitivity reactions to NSAIDs with cross-intolerance if they are intolerant to paracetamol. A quarter of patients who were intolerant to this drug were also intolerant to etoricoxib. In subjects with hypersensitivity to NSAIDs and intolerance to paracetamol, selective COX-2 inhibitors should be administered as a controlled, incremental dose provocation test to assess tolerance.