Polymorphisms in eicosanoid-related biosynthesis enzymes associated with acute urticaria/angioedema induced by nonsteroidal anti-inflammatory drug hypersensitivity

BACKGROUND

Nonsteroidal anti-inflammatory drugs (NSAIDs) are the main triggers of drug hypersensitivity, with NSAID-induced acute urticaria/angioedema (NIUA) the most frequent phenotype. NSAID hypersensitivity is caused by cyclooxygenase 1 inhibition, which leads to an imbalance in prostaglandin (PG) and cysteinyl leukotriene (CysLT) synthesis. As only susceptible individuals develop NSAID hypersensitivity, genetic factors are believed to be involved; however, no study has assessed the overall genetic variability of key enzymes in PG and CysLT synthesis in NSAID hypersensitivity.

OBJECTIVES

To evaluate simultaneously variants in the main genes involved in PG and CysLT biosynthesis in NIUA.

METHODS

Two independent cohorts of patients were recruited in Spain, alongside NSAID-tolerant controls. The discovery cohort included only patients with NIUA; the replication cohort included patients with NSAID-exacerbated respiratory disease (NERD). A set of tagging single-nucleotide polymorphisms (tagSNPs) in PTGS1, PTGS2, ALOX5 and LTC4S was genotyped using mass spectrometry coupled with endpoint polymerase chain reaction.

RESULTS

The study included 1272 individuals. Thirty-five tagSNPs were successfully genotyped in the discovery cohort, with three being significantly associated after Bonferroni correction (rs10306194 and rs1330344 in PTGS1; rs28395868 in ALOX5). These polymorphisms were genotyped in the replication cohort: rs10306194 and rs28395868 remained associated with NIUA, and rs28395868 was marginally associated with NERD. Odds ratios (ORs) in the combined analysis (discovery and replication NIUA populations) were 1·7 for rs10306194 [95% confidence interval (CI) 1·34-2·14; P_corrected = 2·83 × 10^-4 ) and 2·19 for rs28395868 (95% CI 1·43-3·36; P_corrected = 0·002).

CONCLUSIONS

Variants of PTGS1 and ALOX5 may play a role in NIUA and NERD, supporting the proposed mechanisms of NSAID-hypersensitivity and shedding light on their genetic basis.

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.

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.

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.

A compendium answering 150 questions on COVID-19 and SARS-CoV-2

In December 2019, China reported the first cases of the coronavirus disease 2019 (COVID‐19). This disease, caused by the severe acute respiratory syndrome–related coronavirus 2 (SARS‐CoV‐2), has developed into a pandemic. To date, it has resulted in ~9 million confirmed cases and caused almost 500 000 related deaths worldwide. Unequivocally, the COVID‐19 pandemic is the gravest health and socioeconomic crisis of our time. In this context, numerous questions have emerged in demand of basic scientific information and evidence‐based medical advice on SARS‐CoV‐2 and COVID‐19. Although the majority of the patients show a very mild, self‐limiting viral respiratory disease, many clinical manifestations in severe patients are unique to COVID‐19, such as severe lymphopenia and eosinopenia, extensive pneumonia, a “cytokine storm” leading to acute respiratory distress syndrome, endothelitis, thromboembolic complications, and multiorgan failure. The epidemiologic features of COVID‐19 are distinctive and have changed throughout the pandemic. Vaccine and drug development studies and clinical trials are rapidly growing at an unprecedented speed. However, basic and clinical research on COVID‐19–related topics should be based on more coordinated high‐quality studies. This paper answers pressing questions, formulated by young clinicians and scientists, on SARS‐CoV‐2, COVID‐19, and allergy, focusing on the following topics: virology, immunology, diagnosis, management of patients with allergic disease and asthma, treatment, clinical trials, drug discovery, vaccine development, and epidemiology. A total of 150 questions were answered by experts in the field providing a comprehensive and practical overview of COVID‐19 and allergic disease.

ARADyAL: The Spanish Multidisciplinary Research Network for Allergic Diseases

Thematic cooperative health research networks (RETICS) are organizational structures promoted by the Instituto de Salud Carlos III of the Spanish Ministry of Science with the objective of carrying out cooperative research projects addressing challenges of general interest for society as a whole in the field of health care. The RETICS of Asthma, Adverse Drug Reactions, and Allergy (ARADyAL) received funding in 2016 for a 5-year program (2017-2021). ARADyAL integrates basic and clinical research in the areas of allergy, immunology, genetics, nanomedicine, pharmacology, and chemistry, with special interest in research on new biomarkers and the design and evaluation of new interventions for allergic patients with severe phenotypes. The consortium comprises 28 groups across Spain, including 171 clinical and basic researchers, 17 clinical groups that cover more than 10 000 000 patients of all ages from urban and rural areas and 11 basic groups active mostly at universities and research institutes. ARADyAL has proposed a research program organized into 3 different areas focusing on precision medicine, as follows: Program 1, Mechanisms and prediction of adverse drug reactions and allergic diseases; Program 2, Toward a precise diagnosis of allergic diseases; and Program 3, Predicting interventions in allergic diseases. There is also 1 common program dedicated to training. The network has a Steering Committee and an External Advisory Scientific Committee, which advise the global network coordinator, who has recognized expertise in the field. ARADyAL is a unique meeting point for clinicians and basic scientists who are already working in allergy.

PPARβ/δ-dependent MSC metabolism determines their immunoregulatory properties

Mesenchymal stem cell (MSC)-based therapy is being increasingly considered a powerful opportunity for several disorders based on MSC immunoregulatory properties. Nonetheless, MSC are versatile and plastic cells that require an efficient control of their features and functions for their optimal use in clinic. Recently, we have shown that PPARβ/δ is pivotal for MSC immunoregulatory and therapeutic functions. However, the role of PPARβ/δ on MSC metabolic activity and the relevance of PPARβ/δ metabolic control on MSC immunosuppressive properties have never been addressed. Here, we demonstrate that PPARβ/δ deficiency forces MSC metabolic adaptation increasing their glycolytic activity required for their immunoregulatory functions on Th1 and Th17 cells. Additionally, we show that the inhibition of the mitochondrial production of ATP in MSC expressing PPARβ/δ, promotes their metabolic switch towards aerobic glycolysis to stably enhance their immunosuppressive capacities significantly. Altogether, these data demonstrate that PPARβ/δ governs the immunoregulatory potential of MSC by dictating their metabolic reprogramming and pave the way for enhancing MSC immunoregulatory properties and counteracting their versatility.

Evaluation of Subjects Experiencing Allergic Reactions to Non-Steroidal Anti-Inflammatory Drugs: Clinical Characteristics and Drugs Involved

Non-steroidal anti-inflammatory drugs (NSAIDs), the most commonly prescribed and consumed medicines worldwide, are the main triggers of drug hypersensitivity reactions (DHRs). The underlying mechanisms of NSAID-DHRs may be related to COX-1 inhibition (cross-hypersensitivity reactions, CRs) or to immunological recognition (selective reactions, SRs), being the latter remarkably less studied. SRs include those usually appearing within the first hour after drug intake (single-NSAID-induced urticaria/angioedema or anaphylaxis, SNIUAA), and those usually occurring more than 24 h after (single-NSAID-induced delayed reactions, SNIDR). We have evaluated the largest series of patients with SRs, analyzing the number of episodes and drugs involved, the latency for reaction onset, the clinical entities, among other variables, as well as the value of available diagnostic methods. Globally, pyrazolones and arylpropionics were the most frequent culprits (39.3% and 37.3%, respectively). Pyrazolones were the most frequent triggers in SNIUAA and arylpropionics in SNIDR. Urticaria was the most common clinical entity in SNIUAA (42.4%) followed by anaphylaxis (33.3%); whereas SNIDR induced mostly fixed drug eruption (41.1%) and maculopapular exanthema (32.6%). The percentage of patients diagnosed by clinical history was higher in SNIUAA compared with SNIDR (62.7% versus 35.3%, p = 0.00015), whereas the percentage of those diagnosed by skin tests was higher in SNIDR than in SNIUAA (47.1% versus 22.8%, p = 0.00015). Drug provocation test with the culprit was performed in 67 SNIUAA (14.5%) and in 9 SNIDR (17.6%) patients. Our results may be of interest not only for allergologists but also for other clinicians dealing with these drugs, and can be useful for the correct identification of subjects experiencing DHRs to NSAIDs, and for avoiding mislabeling. Moreover, as NSAIDs are highly consumed worldwide, our results may be of interest for evaluating other populations exposed to these drugs.

Amoxicillin Inactivation by Thiol-Catalyzed Cyclization Reduces Protein Haptenation and Antibacterial Potency

Serum and cellular proteins are targets for the formation of adducts with the β-lactam antibiotic amoxicillin. This process could be important for the development of adverse, and in particular, allergic reactions to this antibiotic. In studies exploring protein haptenation by amoxicillin, we observed that reducing agents influenced the extent of amoxicillin-protein adducts formation. Consequently, we show that several thiol-containing compounds, including dithiothreitol, N-acetyl-L-cysteine, and glutathione, perform a nucleophilic attack on the amoxicillin molecule that is followed by an internal rearrangement leading to amoxicillin diketopiperazine, a known amoxicillin metabolite with residual activity. Increased diketopiperazine conversion is also observed with human serum albumin but not with L-cysteine, which mainly forms the amoxicilloyl amide. The effect of thiols is catalytic and can render complete amoxicillin conversion. Interestingly, this process is dependent on the presence of an amino group in the antibiotic lateral chain, as in amoxicillin and ampicillin. Furthermore, it does not occur for other β-lactam antibiotics, including cefaclor or benzylpenicillin. Biological consequences of thiol-mediated amoxicillin transformation are exemplified by a reduced bacteriostatic action and a lower capacity of thiol-treated amoxicillin to form protein adducts. Finally, modulation of the intracellular redox status through inhibition of glutathione synthesis influenced the extent of amoxicillin adduct formation with cellular proteins. These results open novel perspectives for the understanding of amoxicillin metabolism and actions, including the formation of adducts involved in allergic reactions.

Targeting Wistar rat as a model for studying benign, premalignant and malignant lesions of the prostate

AIMS

The purpose of this study was to describe a suitable experimental model for studying aging-related prostate disorders including cancer.

MATERIALS AND METHODS

12-month old Wistar rats were kept in control conditions (n = 12) or treated (n = 16) for 6 months with Silastic implants filled with testosterone (T) and estradiol (E₂). After the experiment period (at 18 months of age), animals were euthanized and the prostate and other organs were harvested, dissected, weighed, and processed for morphological, ultrastructural and molecular analyses.

KEY FINDINGS

We demonstrated that male rats of Wistar strain nicely recapitulate the carcinogenesis process taking place in the aging prostate through the arising of benign, precancerous and malignant lesions, and above all yields a modest incidence of spontaneous PCa (~36%). Moreover, our results highlight that 100% incidence of PCa and precancerous lesions such as prostatic intraepithelial neoplasia and proliferative inflammatory atrophy were achieved in this rat strain after T + E₂ treatment, without changing the broad spectrum of changes that naturally emerge in the prostate at advanced ages. Such enhancement of precancerous lesions and tumors was linked to a decreased expression of E-cadherin and β-catenin in parallel with an increase in Vimentin and N-cadherin, hallmark modifications of epithelial-mesenchymal transition.

SIGNIFICANCE

Our findings provide solid evidence that aged Wistar rats may be an excellent model for studies regarding human prostate biology and related disorders including cancer.

Statement of the Spanish Society of Allergology and Clinical Immunology on Provocation Tests With Aspirin/Nonsteroidal Anti-inflammatory Drugs

Nonsteroidal anti-inflammatory drugs (NSAIDs) are widely used throughout the world. They are frequently involved in hypersensitivity reactions, which range from local or mild reactions to systemic and severe reactions. Consequently, it is necessary to perform an exhaustive study of patients in order to make an accurate diagnosis, search for safe procedures in the case of severe reactions, and identify alternative treatment options. Various guidelines and protocols address the management of hypersensitivity to NSAIDs, although these vary widely from country to country. The Committees of Asthma, Rhinoconjunctivitis, and Drug Allergy of the Spanish Society of Allergy and Clinical Immunology (SEAIC) propose the present position statement on available options for provocation testing with aspirin/NSAIDs. This document is the fruit of an exhaustive review of current evidence and is based on recent publications addressing the diagnosis of patients with hypersensitivity to NSAIDs and on a consensus-oriented discussion among a group of experts from the SEAIC. The main objective was to draft an easy-toread, practical guideline for health care professionals in specialist areas who assess and manage patients with suspected hypersensitivity to NSAIDs. Furthermore, indications, contraindications, and procedures for oral, bronchial, and nasal provocation tests with aspirin/NSAIDs have been updated.

Expanding the Regulon of the Bradyrhizobium diazoefficiens NnrR Transcription Factor: New Insights Into the Denitrification Pathway

Denitrification in the soybean endosymbiont Bradyrhizobium diazoefficiens is controlled by a complex regulatory network composed of two hierarchical cascades, FixLJ-FixK₂-NnrR and RegSR-NifA. In the former cascade, the CRP/FNR-type transcription factors FixK₂ and NnrR exert disparate control on expression of core denitrifying systems encoded by napEDABC, nirK, norCBQD, and nosRZDFYLX genes in response to microoxia and nitrogen oxides, respectively. To identify additional genes controlled by NnrR and involved in the denitrification process in B. diazoefficiens, we compared the transcriptional profile of an nnrR mutant with that of the wild type, both grown under anoxic denitrifying conditions. This approach revealed more than 170 genes were simultaneously induced in the wild type and under the positive control of NnrR. Among them, we found the cycA gene which codes for the c₅₅₀ soluble cytochrome (CycA), previously identified as an intermediate electron donor between the bc₁ complex and the denitrifying nitrite reductase NirK. Here, we demonstrated that CycA is also required for nitrous oxide reductase activity. However, mutation in cycA neither affected nosZ gene expression nor NosZ protein steady-state levels. Furthermore, cycA, nnrR and its proximal divergently oriented nnrS gene, are direct targets for FixK₂ as determined by in vitro transcription activation assays. The dependence of cycA expression on FixK₂ and NnrR in anoxic denitrifying conditions was validated at transcriptional level, determined by quantitative reverse transcription PCR, and at the level of protein by performing heme c-staining of soluble cytochromes. Thus, this study expands the regulon of NnrR and demonstrates the role of CycA in the activity of the nitrous oxide reductase, the key enzyme for nitrous oxide mitigation.

Identification of an antigenic determinant of clavulanic acid responsible for IgE-mediated reactions

BACKGROUND

Selective reactions to clavulanic acid (CLV) account for around 30% of immediate reactions after administration of amoxicillin-CLV. Currently, no immunoassay is available for detecting specific IgE to CLV, and its specific recognition in patients with immediate reactions has only been demonstrated by basophil activation testing, however with suboptimal sensitivity. The lack of knowledge regarding the structure of the drug that remains bound to proteins (antigenic determinant) is hampering the development of in vitro diagnostics. We aimed to identify the antigenic determinants of CLV as well as to evaluate their specific IgE recognition and potential role for diagnosis.

METHODS

Based on complex CLV degradation mechanisms, we hypothesized the formation of two antigenic determinants for CLV, AD-I (N-protein, 3-oxopropanamide) and AD-II (N-protein, 3-aminopropanamide), and designed different synthetic analogs to each one. IgE recognition of these structures was evaluated in basophils from patients with selective reactions to CLV and tolerant subjects. In parallel, the CLV fragments bound to proteins were identified by proteomic approaches.

RESULTS

Two synthetic analogs of AD-I were found to activate basophils from allergic patients. This determinant was also detected bound to lysines 195 and 475 of CLV-treated human serum albumin. One of these analogs was able to activate basophils in 59% of patients whereas CLV only in 41%. Combining both results led to an increase in basophil activation in 69% of patients, and only in 12% of controls.

CONCLUSION

We have identified AD-I as one CLV antigenic determinant, which is the drug fragment that remains protein-bound.

Update on the Genetic Basis of Drug Hypersensitivity Reactions

Drug hypersensitivity reactions (DHRs) are unpredictable, complex responses to medicines in predisposed individuals. They represent a major health problem owing to the number of patients affected and the severity of the clinical conditions they can induce. In addition to environmental factors, the underlying mechanisms of DHRs are also influenced by genetic factors, although considerable gaps remain in our knowledge. Therefore, further study of the genetics of DHRs is necessary to shed light on their underlying mechanisms. In this manuscript, we provide an update on the genetic basis of the most frequent types of DHRs, including those mediated by immunological and nonimmunological mechanisms. For the first group, we will focus on immediate reactions to β-lactam antibiotics, which are associated mainly with the IgE pathway (IL13, IL4R, LGALS3, and NOD2) and antigen presentation (HLA-DRA), and nonimmediate reactions to allopurinol, anticonvulsants, antibiotics, and antiretrovirals, which are often associated with polymorphisms in the HLA system. For the second group, we will focus on nonsteroidal anti-inflammatory drugs, which are mostly associated with genetic variants in enzymes and receptors from the arachidonic acid pathway (eg, ALOX5, ALOX5AP, PTGDR, and CYSLTR1). The information provided here will be of interest for medical practitioners from a range of disciplines who come across these reactions in their clinical practice, as well as for allergologists.

Rhizobium etli Produces Nitrous Oxide by Coupling the Assimilatory and Denitrification Pathways

More than two-thirds of the powerful greenhouse gas nitrous oxide (N₂O) emissions from soils can be attributed to microbial denitrification and nitrification processes. Bacterial denitrification reactions are catalyzed by the periplasmic (Nap) or membrane-bound (Nar) nitrate reductases, nitrite reductases (NirK/cd ₁Nir), nitric oxide reductases (cNor, qNor/ Cu_ANor), and nitrous oxide reductase (Nos) encoded by nap/nar, nir, nor and nos genes, respectively. Rhizobium etli CFN42, the microsymbiont of common bean, is unable to respire nitrate under anoxic conditions and to perform a complete denitrification pathway. This bacterium lacks the nap, nar and nos genes but contains genes encoding NirK and cNor. In this work, we demonstrated that R. etli is able to grow with nitrate as the sole nitrogen source under aerobic and microoxic conditions. Genetic and functional characterization of a gene located in the R. etli chromosome and annotated as narB demonstrated that growth under aerobic or microoxic conditions with nitrate as nitrogen source as well as nitrate reductase activity requires NarB. In addition to be involved in nitrate assimilation, NarB is also required for NO and N₂O production by NirK and cNor, respectively, in cells grown microoxically with nitrate as the only N source. Furthermore, β-glucuronidase activity from nirK::uidA and norC::uidA fusions, as well as NorC expression and Nir and Nor activities revealed that expression of nor genes under microoxic conditions also depends on nitrate reduction by NarB. Our results suggest that nitrite produced by NarB from assimilatory nitrate reduction is detoxified by NirK and cNor denitrifying enzymes that convert nitrite into NO which in turn is reduced to N₂O, respectively.

Silencing of the transcriptional factor ZEB1 alters the steroidogenic pathway, and increases the concentration of testosterone and DHT in DU145 cells

Prostate cancer (PCa) is the second most common type of male malignancy worldwide. The transcription factor zinc finger E‑box binding homeobox 1 (ZEB1) is associated with epithelial‑mesenchymal transition and is also involved in regulation of androgen receptor (AR) expression, the main ligands of which are testosterone and dihydrotestosterone (DHT). These androgens are synthesized through the steroidogenic pathway within the prostate, and their synthesis is altered in PCa. The present study aimed to determine the ZEB1‑induced alterations in androgen synthesis and AR expression in the DU145 PCa cell line. Reverse transcription‑quantitative polymerase chain reaction, western blotting and immunocytochemistry were used to determine the mRNA and protein expression levels, and cellular localization of steroidogenic pathway enzymes in the DU145 cell line in response to ZEB1 silencing. Furthermore, the concentrations of testosterone and DHT were detected in cell culture medium using ELISA. ZEB1‑silenced cells exhibited an increase in testosterone and DHT production, an increase in AR expression and an alteration in the steroidogenic pathway. In particular, steroidogenic acute regulatory protein and 5α‑reductase 2 expression levels were decreased, whereas cytochrome P450 family 17 subfamily A member 1, 5α‑reductase 1, aldo‑keto reductase family 1 member D1 and aldo‑keto reductase family 1 member C2 expression levels were increased. In conclusion, the present study provided novel information regarding the regulation of intratumoral androgen production in PCa, which is relevant for the progression of the disease to a castration‑resistant form.

Accuracy of the Diagnosis of Allergic Reactions in the Emergency Department

BACKGROUND AND OBJECTIVE

Suspicion of an acute allergic reaction is a common reason for attending the emergency department (ED). However, there are few comparisons between the initial diagnosis of suspected allergic reaction made in the ED with the definitive diagnosis made subsequently in the allergy department (AD). Objective: To compare details of the initial diagnosis made in the ED relating to allergy with the final diagnosis made in the AD.

METHODS

Patients attending the ED of 2 hospitals with suspected allergic reactions were prospectively enrolled based on key words. A certified allergy specialist reviewed the ED records of these patients and, if these were suggestive of an allergic reaction, the patients were scheduled for further evaluation at the allergy clinic.

RESULTS

In total, 2000 patients were enrolled between April 2013 and October 2015. Of these, 1333 passed the initial assessment and underwent further evaluation. Of the 1333 patients, 528 underwent an allergological study, and 206 were confirmed as being allergic. With respect to drug allergy, nonsteroidal anti-inflammatory drugs were the most common triggers, followed by β-lactams; in food allergy, plant-based foods were the most common. Only 16.4% of patients confirmed as having anaphylaxis in the AD were initially diagnosed with the condition in the ED.

CONCLUSION

Of the 528 patients who finally underwent the full allergological study, fewer than half were confirmed as allergic. Moreover, anaphylaxis appears to be underdiagnosed in the ED. Better communication between the ED and the AD is necessary to improve the diagnosis and management of these patients.

Local allergic rhinitis: Implications for management

A significant proportion of rhinitis patients without systemic IgE-sensitisation tested by skin prick test and serum allergen-specific IgE (sIgE) display nasal reactivity upon nasal allergen provocation test (NAPT). This disease phenotype has been termed local allergic rhinitis (LAR). LAR is an underdiagnosed entity affecting children and adults from different parts of the world, with moderate-to-severe symptoms, impairment of quality of life and rapid progression to symptom worsening. LAR is a stable phenotype and not merely an initial state of AR. Allergic rhinitis and LAR share many clinical features including a positive NAPT response, markers of type 2 nasal inflammation including sIgE in nasal secretions and a significant rate of asthma development. LAR should be considered as a differential diagnosis in those subjects of any age with symptoms suggestive of AR but no evidence of systemic atopy. Although LAR pathophysiology is partially unknown, in some patients sIgE can be demonstrated directly in the nasal secretions and/or indirectly via positive responses in basophil activation test (BAT). LAR can coexist with other rhinitis phenotypes, especially AR. The diagnosis currently relies on the positivity of NAPT to a single or multiple allergens. NAPT has high sensitivity, specificity and reproducibility, and it is considered the gold standard. BAT and the measurement of nasal sIgE can also contribute to LAR diagnosis. LAR patients benefit from the same therapeutic strategies than AR individuals, including the avoidance of allergen exposure and the pharmacotherapy. Moreover, several recent studies support the effectiveness and safety of allergen immunotherapy for LAR, which opens a window of treatment opportunity in these patients.

Dendrimeric Antigens for Drug Allergy Diagnosis: A New Approach for Basophil Activation Tests

Dendrimeric Antigens (DeAns) consist of dendrimers decorated with multiple units of drug antigenic determinants. These conjugates have been shown to be a powerful tool for diagnosing penicillin allergy using in vitro immunoassays, in which they are recognized by specific IgE from allergic patients. Here we propose a new diagnostic approach using DeAns in cellular tests, in which recognition occurs through IgE bound to the basophil surface. Both IgE molecular recognition and subsequent cell activation may be influenced by the tridimensional architecture and size of the immunogens. Structural features of benzylpenicilloyl-DeAn and amoxicilloyl-DeAn (G2 and G4 PAMAM) were studied by diffusion Nuclear Magnetic Resonance (NMR) experiments and are discussed in relation to molecular dynamics simulation (MDS) observations. IgE recognition was clinically evaluated using the basophil activation test (BAT) for allergic patients and tolerant subjects. Diffusion NMR experiments, MDS and cellular studies provide evidence that the size of the DeAn, its antigen composition and tridimensional distribution play key roles in IgE-antigen recognition at the effector cell surface. These results indicate that the fourth generation DeAns induce a higher level of basophil activation in allergic patients. This approach can be considered as a potential complementary diagnostic method for evaluating penicillin allergy.

Immunological Changes Induced in Peach Allergy Patients with Systemic Reactions by Pru p 3 Sublingual Immunotherapy

SCOPE

Sublingual immunotherapy using peach extract enriched in Pru p 3 (Pru p 3-enriched-SLIT) brings a new perspective to treating patients with allergy to lipid transfer proteins. We evaluate the immunological changes induced by Pru p 3-enriched-SLIT during one year.

METHODS AND RESULTS

Three groups are included: peach allergic patients who receive Pru p 3-enriched-SLIT, peach allergic untreated patients, and controls. Peripheral blood mononuclear cells are obtained before treatment and at different time-points. Monocyte-derived dendritic cells (moDCs) maturation and lymphocyte proliferation are assessed by flow cytometry. Data showed a significant reduction of moDCs maturation status during one year of treatment and an increase in PD-L1. Moreover, we observed a significant decrease of the Pru p 3-specific proliferation of effector cells and an increase in regulatory T (Treg) cells with higher PD-L1 expression and IL-10 production. These are observed in patients treated only.

CONCLUSION

Successful Pru p 3-enriched-SLIT is linked to an important immunosuppression of allergen-specific effector T cells, potentially due to an increase of allergen-specific Treg cells. These cellular changes are orchestrated by the activity of moDCs promoting the expression of PD-L1 that will participate in the regulatory response. These changes may serve as biomarkers during SLIT alongside other features such as IgE/IgG₄ ratio.

The clinical and immunological effects of Pru p 3 sublingual immunotherapy on peach and peanut allergy in patients with systemic reactions

BACKGROUND

The peach non-specific lipid transfer protein, Pru p 3, is the primary sensitizer in fruits and responsible for severe reactions in the Mediterranean area. Peach allergy is frequently associated with other allergies such as peanut. Therefore, it is important to assess how specific immunotherapy to Pru p 3 could affect both peach and peanut tolerance.

OBJECTIVES

To evaluate peach and peanut desensitization and immunological changes after 1 year of Pru p 3 sublingual immunotherapy (SLIT) in patients with systemic allergic reactions to peach and/or peanut.

METHODS

Forty-eight peach allergic patients, 36 treated with SLIT and 12 non-treated, were monitored for 12 months. Treated patients were subclassified as peanut allergic (Group A), sensitized (Group B) or tolerant (Group C). SLIT effect was evaluated by skin prick test (SPT) reactivity and food challenge. Immunological changes were evaluated by monitoring sIgE and sIgG4 levels and basophil reactivity.

RESULTS

After 1 year of SLIT, the weal area in SPT significantly decreased and a significant increase in peach threshold in treated patients was observed (P < 0.001). Patients in Group A showed a significant decrease in peanut SPT weal area and an increase in peanut threshold (P < 0.001). Immunological changes were observed in treated patients only, with a significant decrease in sIgE and a parallel increase in sIgG4, sIgG4/sIgE and basophil reactivity for both Pru p 3 and Ara h 9.

CONCLUSIONS AND CLINICAL RELEVANCE

After 1 year, Pru p 3 SLIT induces both desensitization and immunological changes not only for peach but also for other food allergens relevant in the induction of severe reactions such as peanut.

Dermatophagoides pteronyssinus immunotherapy changes the T-regulatory cell activity

Subcutaneous specific immunotherapy (SCIT) has been shown to modify the Dermatophagoides pteronissinus (DP) allergic response, characterized by generation of Treg cells. However, studies have reported no changes in the proportion of Treg cells after immunotherapy, indicating that the effects may be due to modifications in their regulatory activities. We aimed to determine whether Tregs generated by DP-SCIT can switch the allergic response to tolerant and study the involvement of suppressive cytokines on it. Twenty-four DP-allergic rhinitis patients were recruited, 16 treated with DP-SCIT and 8 untreated. Treg and T effector cells were isolated before and after DP-SCIT, and cocultured in different combinations with α-IL-10, α-TGF-β blocking antibodies and nDer p 1. Treg cells after DP-SCIT increased Th1 and decreased Th2 and Th9 proliferation. Similarly, they increased IL-10 and decreased IL-4 and IL-9-producing cells. α-IL-10 affected the activity of Treg cells obtained after DP-SCIT only. Finally, DP-specific IgG4 levels, Treg percentage and IL-10 production were correlated after DP-SCIT. These results demonstrate that DP-SCIT induces Treg cells with different suppressive activities. These changes could be mediated by IL-10 production and appear to play an important role in the induction of the tolerance response leading to a clinical improvement of symptoms.