Lack of Major Involvement of Common CYP2C Gene Polymorphisms in the Risk of Developing Cross-Hypersensitivity to NSAIDs.

Cross-hypersensitivity to non-steroidal anti-inflammatory drugs (NSAIDs) is a relatively common, non-allergic, adverse drug event triggered by two or more chemically unrelated NSAIDs. Current evidence point to COX-1 inhibition as one of the main factors in its etiopathogenesis. Evidence also suggests that the risk is dose-dependent. Therefore it could be speculated that individuals with impaired NSAID biodisposition might be at increased risk of developing cross-hypersensitivity to NSAIDs. We analyzed common functional gene variants for CYP2C8, CYP2C9, and CYP2C19 in a large cohort composed of 499 patients with cross-hypersensitivity to NSAIDs and 624 healthy individuals who tolerated NSAIDs. Patients were analyzed as a whole group and subdivided in three groups according to the main enzymes involved in the metabolism of the culprit drugs as follows: CYP2C9, aceclofenac, indomethacin, naproxen, piroxicam, meloxicam, lornoxicam, and celecoxib; CYP2C8 plus CYP2C9, ibuprofen and diclofenac; CYP2C19 plus CYP2C9, metamizole. Genotype calls ranged from 94 to 99%. No statistically significant differences between patients and controls were identified in this study, either for allele frequencies, diplotypes, or inferred phenotypes. After patient stratification according to the enzymes involved in the metabolism of the culprit drugs, or according to the clinical presentation of the hypersensitivity reaction, we identified weak significant associations of a lower frequency (as compared to that of control subjects) of CYP2C8*3/*3 genotypes in patients receiving NSAIDs that are predominantly CYP2C9 substrates, and in patients with NSAIDs-exacerbated cutaneous disease. However, these associations lost significance after False Discovery Rate correction for multiple comparisons. Taking together these findings and the statistical power of this cohort, we conclude that there is no evidence of a major implication of the major functional CYP2C polymorphisms analyzed in this study and the risk of developing cross-hypersensitivity to NSAIDs. This argues against the hypothesis of a dose-dependent COX-1 inhibition as the main underlying mechanism for this adverse drug event and suggests that pre-emptive genotyping aiming at drug selection should have a low practical utility for cross-hypersensitivity to NSAIDs.

Diagnostic Approach of Hypersensitivity Reactions to Cefazolin in a Large Prospective Cohort.

BACKGROUND: Cefazolin is a common trigger of perioperative anaphylaxis. The diagnostic approach is controversial because the optimal concentration for skin testing is uncertain, drug provocation tests (DPTs) are contraindicated in severe reactions, and in vitro tests are not thoroughly validated. OBJECTIVE: We aimed to characterize a large number of patients reporting cefazolin allergic reactions and to analyze the diagnostic role of in vivo and in vitro tests. METHODS: We prospectively evaluated patients with suspicion for allergic reactions to cefazolin by clinical history, skin tests (STs), and, if negative, DPT. In a subgroup of patients, basophil activation test (BAT) and radioallergosorbent test were done before allergologic workup was performed and the final diagnosis was achieved. RESULTS: We evaluated 184 patients, 76 of whom were confirmed as allergic (41.3%), 90 were nonallergic (48.9%), and 18 were nonconfirmed (9.8%). All patients reporting anaphylactic shock and most reporting anaphylaxis were confirmed to be allergic (P < .001). Forty allergic patients (52.6%) were confirmed by STs, 22 by DPT (28.9%), and 14 by clinical history (18.4%). All subjects manifesting exanthemas and pruritus were nonallergic. The BAT sensitivity was 66.7% when CD63 and CD203c were combined as activation markers. Six of 8 patients with negative STs and positive DPT had a positive BAT. CONCLUSIONS: Patients allergic to cefazolin often reported severe immediate-type reactions. Skin tests enabled a diagnosis in half of patients when using cefazolin at 20 mg/mL. Unfortunately, DPT could not be performed in all patients owing to reaction severity, which makes BAT a promising diagnostic tool. Further research is needed to clarify the underlying mechanisms, especially in severe reactions.

Genetic Variants in Cytosolic Phospholipase A2 Associated With Nonsteroidal Anti-Inflammatory Drug-Induced Acute Urticaria/Angioedema.

Nonsteroidal anti-inflammatory drugs (NSAIDs) are among the main triggers of drug hypersensitivity reactions, probably due to their high consumption worldwide. The most frequent type of NSAID hypersensitivity is NSAID cross-hypersensitivity, in which patients react to NSAIDs from different chemical groups in the absence of a specific immunological response. The underlying mechanism of NSAID cross-hypersensitivity has been linked to cyclooxygenase (COX)-1 inhibition causing an imbalance in the arachidonic acid pathway. Despite NSAID-induced acute urticaria/angioedema (NIUA) being the most frequent clinical phenotype, most studies have focused on NSAID-exacerbated respiratory disease. As NSAID cross-hypersensitivity reactions are idiosyncratic, only appearing in some subjects, it is believed that individual susceptibility is under the influence of genetic factors. Although associations with polymorphisms in genes from the AA pathway have been described, no previous study has evaluated the potential role of cytosolic phospholipase A2 (cPLA2) variants. This enzyme catalyzes the initial hydrolysis of membrane phospholipids to release AA, which can be subsequently metabolized into eicosanoids. Here, we analyzed for the first time the overall genetic variation in the cPLA2 gene (PLA2G4A) in NIUA patients. For this purpose, a set of tagging single nucleotide polymorphisms (tagSNPs) in PLA2G4A were selected using data from Europeans subjects in the 1,000 Genomes Project, and genotyped with the iPlex Sequenom MassArray technology. Two independent populations, each comprising NIUA patients and NSAID-tolerant controls, were recruited in Spain, for the purposes of discovery and replication, comprising a total of 1,128 individuals. Fifty-eight tagSNPs were successfully genotyped in the discovery cohort, of which four were significantly associated with NIUA after Bonferroni correction (rs2049963, rs2064471, rs12088010, and rs12746200). These polymorphisms were then genotyped in the replication cohort: rs2049963 was associated with increased risk for NIUA after Bonferroni correction under the dominant and additive models, whereas rs12088010 and rs12746200 were protective under these two inheritance models. Our results suggest a role for PLA2G4A polymorphisms in NIUA. However, further studies are required to replicate our findings, elucidate the mechanistic role, and evaluate the participation of PLA2G4A variants in other phenotypes induced by NSAID cross-hypersensitivity.

Deep sequencing of prostaglandin-endoperoxide synthase (PTGE) genes reveals genetic susceptibility for cross-reactive hypersensitivity to NSAID.

BACKGROUND AND PURPOSE: Cross-reactive hypersensitivity to nonsteroidal anti-inflammatory drugs (NSAIDs) is a relatively common adverse drug event caused by two or more chemically unrelated drugs and that is attributed to inhibition of the COX activity, particularly COX-1. Several studies investigated variations in the genes coding for COX enzymes as potential risk factors. However, these studies only interrogated a few single nucleotide variations (SNVs), leaving untested most of the gene sequence. EXPERIMENTAL APPROACH: In this study, we analysed the whole sequence of the prostaglandin-endoperoxide synthase genes, PTGS1 and PTGS2, including all exons, exon-intron boundaries and both the 5' and 3' flanking regions in patients with cross-reactive hypersensitivity to NSAIDs and healthy controls. After sequencing analysis in 100 case-control pairs, we replicated the findings in 540 case-control pairs. Also, we analysed copy number variations for both PTGS genes. KEY RESULTS: The most salient finding was the presence of two PTGS1 single nucleotide variations, which are significantly more frequent in patients than in control subjects. Patients carrying these single nucleotide variations displayed a significantly and markedly lower COX-1 activity as compared to non-carriers for both heterozygous and homozygous patients. CONCLUSION AND IMPLICATIONS: Although the risk single nucleotide variations are present in a small proportion of patients, the strong association observed and the functional effect of these single nucleotide variations raise the hypothesis of genetic susceptibility to develop cross-reactive NSAID hypersensitivity in individuals with an impairment in COX-1 enzyme activity.

Platelet-Adherent Leukocytes Associated With Cutaneous Cross-Reactive Hypersensitivity to Nonsteroidal Anti-Inflammatory Drugs.

Nonsteroidal anti-inflammatory drugs (NSAIDs) are among the most highly consumed drugs worldwide and the main triggers of drug hypersensitivity reactions. The most frequent reaction, named cross-reactive NSAID-hypersensitivity, is due to the pharmacological activity of these drugs by blocking the cyclooxygenase-1 enzyme. Such inhibition leads to cysteinyl-leukotriene synthesis, mainly LTE4, which are responsible for the reaction. Although the complete molecular picture of the underlying mechanisms remains elusive, the participation of platelet-adherent leukocytes (CD61+) and integrins have been described for NSAID-exacerbated respiratory disease (NERD). However, there is a lack of information concerning NSAID-induced urticaria/angioedema (NIUA), by far the most frequent clinical phenotype. Here we have evaluated the potential role of CD61+ leukocytes and integrins (CD18, CD11a, CD11b, and CD11c) in patients with NIUA, and included the other two phenotypes with cutaneous involvement, NSAID-exacerbated cutaneous disease (NECD) and blended reactions (simultaneous skin and airways involvement). A group NSAID-tolerant individuals was also included. During the acute phase of the reaction, the three clinical phenotypes showed increased frequencies of CD61+ neutrophils, eosinophils, and monocytes compared to controls, which correlated with urinary LTE4 levels. However, no correlation was found between these variables at basal state. Furthermore, increased expressions of CD18 and CD11a were found in the three CD61+ leukocytes subsets in NIUA, NECD and blended reactions during the acute phase when compared with CD61-leukocyte subpopulations. During the acute phase, CD61+ neutrophils, eosinophils and monocytes showed increased CD18 and CD11a expression when compared with CD61+ leukocytes at basal state. No differences were found when comparing controls and CD61+ leukocytes at basal state. Our results support the participation of platelet-adherent leukocytes and integrins in cutaneous cross-hypersensitivity to NSAIDs and provide a link between these cells and arachidonic acid metabolism. Our findings also suggest that these reactions do not involve a systemic imbalance in the frequency of CD61+ cells/integrin expression or levels of LTE4, which represents a substantial difference to NERD. Although further studies are needed, our results shed light on the molecular basis of cutaneous cross-reactive NSAID-hypersensitivity, providing potential targets for therapy through the inhibition of platelet-leukocyte interactions.

The use of drug provocation testing in the investigation of suspected immediate perioperative allergic reactions: current status.

Suspected perioperative allergic reactions are often severe. To avoid potentially life-threatening re-exposure to the culprit drug, establishing a firm diagnosis and identifying the culprit is crucial. Drug provocation tests are considered the gold standard in drug allergy investigation but have not been recommended in the investigation of perioperative allergy, mainly because of the pharmacological effects of drugs such as induction agents and neuromuscular blocking agents. Some specialised centres have reported benefits of provocation testing in perioperative allergy investigation, but the literature on the subject is limited. Here we provide a status update on the use of drug provocation testing in perioperative allergy, including its use in specific drug groups. This review is based on a literature search and experiences of the authors comprising anaesthesiologists and allergists with experience in perioperative allergy investigation. In addition, 19 participating centres in the International Suspected Perioperative Allergic Reaction Group were surveyed on the use of provocation testing in perioperative allergy investigation. A response was received from 13 centres in eight European countries, New Zealand, and the USA. Also, 21 centres from the Australian and New Zealand Anaesthetic Allergy Group were surveyed. Two centres performed provocation routinely and seven centres performed no provocations at all. Nearly half of the centres reported performing provocations with induction agents and neuromuscular blocking agents. Drug provocation testing is being used in perioperative allergy investigation in specialised centres, but collaborations between relevant specialties and multicentre studies are necessary to determine indications and establish common testing protocols.

Comparative epidemiology of suspected perioperative hypersensitivity reactions.

Suspected perioperative hypersensitivity reactions are rare but contribute significantly to the morbidity and mortality of surgical procedures. Recent publications have highlighted the differences between countries concerning the respective risk of different drugs, and changes in patterns of causal agents and the emergence of new allergens. This review summarises recent information on the epidemiology of perioperative hypersensitivity reactions, with specific consideration of differences between geographic areas for the most frequently involved offending agents.

The Basophil Activation Test Can Be of Value for Diagnosing Immediate Allergic Reactions to Omeprazole.

BACKGROUND: Proton pump inhibitors (PPIs) are commonly used to treat gastrointestinal diseases. Incidence of hypersensitivity reactions to PPIs has risen, likely because of increased consumption. Their diagnosis is difficult, with skin tests (STs) presenting low sensitivity, making it necessary to perform drug provocation tests (DPTs). The value of in vitro tests for the diagnosis of immediate reaction to PPI is unclear. OBJECTIVE: To analyze the diagnostic value of the basophil activation test (BAT) in a group of patients diagnosed with immediate allergy to omeprazole. METHODS: The study included 42 patients with confirmed immediate allergic reactions to omeprazole confirmed by positive ST results or DPT results and 22 age- and sex-matched subjects tolerant to PPIs. BAT was performed with omeprazole, pantoprazole, and lansoprazole using CD63 and CD203c as activation markers. RESULTS: ST sensitivity was 66.7% with a specificity of 100%. BAT using CD63 with a stimulation index of more than 2 as positive revealed a sensitivity of 73.8%, a specificity of 100%, a positive predictive value of 100%, and a negative predictive value of 66.7%. BAT was positive in 57.1% of patients with negative ST result, and thus by combining ST and BAT we can correctly diagnose 85.7% of patients with immediate allergy to omeprazole. CONCLUSION: BAT represents a complementary tool for inclusion in the allergological workup for patients allergic to omeprazole. When combined with ST, it can be of value to guide the clinician as to whether to perform a DPT.

Evolution of diagnostic approaches in betalactam hypersensitivity.

INTRODUCTION: Betalactams are the most widely used drugs against infections and the primary cause of antibiotic hypersensitivity reactions. Reaction patterns for different betalactams have been changing in accordance with consumption trends, and vary among countries. As a consequence, in vivo and in vitro tests have had to change with to keep up with new tendencies. Areas covered: This review is focused on advances in betalactam hypersensitivity diagnosis. Changes in in vivo methods have been limited to the inclusion of new haptens. In contrast, major progress has been achieved for in vitro tests since the 1960s, from the first description of immunoassays, the basophil activation test and the lymphocyte transformation test, to the more sophisticated assays developed in last years. Expert commentary: Issues with diagnosis are related to test sensitivity. In vivo tests show higher sensitivity, however they can be risky, especially in severe and life-threatening reactions. Therefore, we believe that in vitro tests should be the preferred method. Current efforts are under way to enhance their sensitivity. Only multidisciplinary approaches involving immunology, proteomics, nanotechnology and chemistry can help us to fully understand conjugate structures and mechanisms involved in hypersensitivity reactions to betalactams, and consequently lead to advances in in vitro methods.

Variants of CEP68 gene are associated with acute urticaria/angioedema induced by multiple non-steroidal anti-inflammatory drugs.

Non-steroidal anti-inflammatory drugs (NSAIDs) are the most consumed drugs worldwide because of their efficacy and utility in the treatment of pain and inflammatory diseases. However, they are also responsible for an important number of adverse effects including hypersensitivity reactions. The most important group of these reactions is triggered by non-immunological, pharmacological mechanisms catalogued under the denomination of cross-intolerance (CRI), with acute urticaria/angioedema induced by multiple NSAIDs (MNSAID-UA) the most frequently associated clinical entity. A recent genome-wide association study identified the gene encoding the centrosomal protein of 68 KDa (CEP68) as the major locus associated with aspirin intolerance susceptibility in asthmatics. In this study, we aimed to assess the role of this locus in susceptibility to CRI to NSAIDs by examining 53 common gene variants in a total of 635 patients that were classified as MNSAID-UA (n = 399), airway exacerbations (n = 110) or blended pattern (n = 126), and 425 controls. We found in the MNSAID-UA group a number of variants (17) associated (lowest p-value = 1.13 × 10(-6)), including the non-synonymous Gly74Ser variant (rs7572857) previously associated with aspirin intolerance susceptibility in asthmatics. Although not being significant in the context of multiple testing, eight of these variants were also associated with exacerbated respiratory disease or blended reactions. Our results suggest that CEP68 gene variants may play an important role in MNSAID-UA susceptibility and, despite the different regulatory mechanisms involved depending on the specific affected organ, in the development of hypersensitivity reactions to NSAIDs.

Variability in histamine receptor genes HRH1, HRH2 and HRH4 in patients with hypersensitivity to NSAIDs.

AIM: Histamine plays an important role in the pathogenesis of allergic diseases. Genetic variations in histamine receptors (HRH) may influence the expression of allergic diseases. This study analyzes the association between HRH variants and NSAID hypersensitivity reactions. PATIENTS & METHODS: The authors analyzed copy number variations (CNVs) and common functional SNPs in genes HRH1, HRH2 and HRH4 in 442 unrelated patients with hypersensitivity to NSAIDs and in 414 healthy unrelated controls. RESULTS: The authors identified, both in patients and control subjects, individuals carrying CNVs in HRH genes. The most common genotype corresponded to two copies of each gene, but carriers of one or three copies of HRH1 (5% of individuals), HRH2 (1.1%) and HRH4 genes (0.9%) were also identified. CONCLUSION: For the first time, we describe CNVs in human HRH genes. Neither common functional SNPs in HRH genes nor CNVs influenced the risk of developing hypersensitivity to NSAIDs.

The diamine oxidase gene is associated with hypersensitivity response to non-steroidal anti-inflammatory drugs.

UNLABELLED: Non-steroidal anti-inflammatory drugs (NSAIDs) are the drugs most frequently involved in hypersensitivity drug reactions. Histamine is released in the allergic response to NSAIDs and is responsible for some of the clinical symptoms. The aim of this study is to analyze clinical association of functional polymorphisms in the genes coding for enzymes involved in histamine homeostasis with hypersensitivity response to NSAIDs. We studied a cohort of 442 unrelated Caucasian patients with hypersensitivity to NSAIDs. Patients who experienced three or more episodes with two or more different NSAIDs were included. If this requirement was not met diagnosis was established by challenge. A total of 414 healthy unrelated controls ethnically matched with patients and from the same geographic area were recruited. Analyses of the SNPs rs17740607, rs2073440, rs1801105, rs2052129, rs10156191, rs1049742 and rs1049793 in the HDC, HNMT and DAO genes were carried out by means of TaqMan assays. The detrimental DAO 16 Met allele (rs10156191), which causes decreased metabolic capacity, is overrepresented among patients with crossed-hypersensitivity to NSAIDs with an OR  = 1.7 (95% CI  = 1.3-2.1; Pc  = 0.0003) with a gene-dose effect (P = 0.0001). The association was replicated in two populations from different geographic areas (Pc  = 0.008 and Pc  = 0.004, respectively). CONCLUSIONS AND IMPLICATIONS: The DAO polymorphism rs10156191 which causes impaired metabolism of circulating histamine is associated with the clinical response in crossed-hypersensitivity to NSAIDs and could be used as a biomarker of response.