Diagnostic Accuracy of Specific IgE Against Wheat and Rye in Flour-Induced Occupational Asthma.

BACKGROUND: Assessment of IgE-mediated sensitization to flour allergens is widely used to investigate flour-induced occupational asthma. The diagnostic efficiency of detecting specific IgE antibodies (sIgEs) against wheat and rye flour, however, has not been thoroughly compared with other diagnostic procedures. OBJECTIVE: We sought to evaluate the diagnostic accuracy of sIgE against wheat and rye compared with specific inhalation challenge (SIC) with flour as the reference standard. METHODS: This retrospective multicenter study included 264 subjects who completed an SIC with flour in eight tertiary centers, of whom 205 subjects showed a positive SIC result. RESULTS: Compared with SIC, sIgE levels of 0.35 kUA/L or greater against wheat and rye provided similar sensitivities (84% to 85%, respectively), specificities (71% to 78%), positive predictive values (91% to 93%), and negative predictive values (56% to 61%). Increasing the threshold sIgE value to 5.10 kUA/L for wheat and to 6.20 kUA/L for rye provided a specificity of 95% or greater and further enhanced the positive predictive value to 98%. Among subjects with a positive SIC, those who failed to demonstrate sIgE against wheat and rye (n = 26) had significantly lower total serum IgE level and blood and sputum eosinophil counts and a lesser increase in postchallenge FeNO compared with subjects with a detectable sIgE. CONCLUSION: High levels of sIgE against wheat and/or rye flour strongly support a diagnosis of flour-induced occupational asthma without the need to perform an SIC. The absence of detectable sIgE against wheat and rye in subjects with a positive SIC seems to be associated with lower levels of TH2 biomarkers.

Comparison of high- and low-molecular-weight sensitizing agents causing occupational asthma: an evidence-based insight.

INTRODUCTION: The many substances used at the workplace that can cause sensitizer-induced occupational asthma are conventionally categorized into high-molecular-weight (HMW) agents and low-molecular-weight (LMW) agents, implying implicitly that these two categories of agents are associated with distinct phenotypic profiles and pathophysiological mechanisms. AREAS COVERED: The authors conducted an evidence-based review of available data in order to identify the similarities and differences between HMW and LMW sensitizing agents. EXPERT OPINION: Compared with LMW agents, HMW agents are associated with a few distinct clinical features (i.e. concomitant work-related rhinitis, incidence of immediate asthmatic reactions and increase in fractional exhaled nitric oxide upon exposure) and risk factors (i.e. atopy and smoking). However, some LMW agents may exhibit 'HMW-like' phenotypic characteristics, indicating that LMW agents are a heterogeneous group of agents and that pooling them into a single group may be misleading. Regardless of the presence of detectable specific IgE antibodies, both HMW and LMW agents are associated with a mixed Th1/Th2 immune response and a predominantly eosinophilic pattern of airway inflammation. Large-scale multicenter studies are needed that use objective diagnostic criteria and assessment of airway inflammatory biomarkers to identify the pathobiological pathways involved in OA caused by the various non-protein agents.

Endotyping asthma related to 3 different work exposures.

BACKGROUND: Work exposures play a significant role in adult-onset asthma, but the mechanisms of work-related asthma are not fully elucidated. OBJECTIVE: We aimed to reveal the molecular mechanisms of work-related asthma associated with exposure to flour (flour asthma), isocyanate (isocyanate asthma), or welding fumes (welding asthma) and identify potential biomarkers that distinguish these groups from each other. METHODS: We used a combination of clinical tests, transcriptomic analysis, and associated pathway analyses to investigate the underlying disease mechanisms of the blood immune cells and the airway epithelium of 61 men. RESULTS: Compared with the healthy controls, the welding asthma patients had more differentially expressed genes than the flour asthma and isocyanate asthma patients, both in the airway epithelia and in the blood immune cells. In the airway epithelia, active inflammation was detected only in welding asthma patients. In contrast, many differentially expressed genes were detected in blood cells in all 3 asthma groups. Disease-related immune functions in blood cells, including leukocyte migration and inflammatory responses, and decreased expression of upstream cytokines such as TNF and IFN-γ were suppressed in all the asthma groups. In transcriptome-phenotype correlations, hyperresponsiveness (R ∼ |0.6|) had the highest clinical relevance and was associated with a set of exposure group-specific genes. Finally, biomarker subsets of only 5 genes specifically distinguished each of the asthma exposure groups. CONCLUSIONS: This study provides novel data on the molecular mechanisms underlying work-related asthma. We identified a set of 5 promising biomarkers in asthma related to flour, isocyanate, and welding fume exposure to be tested and clinically validated in future studies.

Baker's asthma in bread factory workers.

Background: Baker's asthma (BA) is one of the most common causes of occupational asthma. Prevalence of BA varies from 3 to 24% in various studies; however, in our country, there are not enough data on its prevalence. Objective: The aim of this study was to evaluate wheat flour sensitivity and to determine the rate of BA in workers at a large bread factory in Ankara. Methods: All steps of the study were carried out in the workplace by the research team who made regular visits to the bread factory. A questionnaire was used to determine the presence of respiratory symptoms and its relation with the occupation. Skin-prick tests and specific immunoglobulin E measurements were performed. Pulmonary function tests and specific inhalation challenges (SIC) were performed to confirm the BA diagnosis. Results: A total of 162 workers (women/men, 3/159; mean ±standard error age, 38.25 ± 7.8 years) were included in the study. Of the 99 workers who described symptoms, 88 (88.8%) had nasal and 57 (57.5%) had lower respiratory symptoms. Sensitivity to wheat flour was present in 23 of the workers (14.2%) among all the workers. Among all the workers, seven (4.32%) were diagnosed with BA and SICs were positive in four (2.46%). Conclusion: Wheat sensitivity was high among the bakers who were exposed to wheat flour; however, the prevalence of BA was quite lower than the previous data in the literature.

Exposure to additives or multigrain flour is associated with high risk of work-related allergic symptoms among bakers.

OBJECTIVES: Wheat flour exposure in bakers can elicit respiratory and skin symptoms. Scarce data are available on the prevalence of such conditions in bakers. We investigated the prevalence of work-related rhinitis, asthma-like symptoms and dermatitis in bakers according to job task and type of allergens involved. METHODS: Of the 229 traditional bakeries in Verona area who were invited to participate in a cross-sectional survey, 211 (92%) accepted; 727 employees in these bakeries answered a modified version of a questionnaire on job tasks; allergen exposure within the bakery; and work-related nasal, asthma-like and skin symptoms during 2010-2014. Determinants of work-related nasal, asthma-like or skin disorders were separately evaluated using different logistic models. RESULTS: The prevalence of work-related nasal and asthma-like symptoms was, respectively, 15.1% and 4.2% in bakery shop assistants, increasing to 25.7% and 9.5% in bakers using only wheat flour, and further to 31.8% and 13.6% in bakers using flour and additives, and then to 34.1% and 18.2% in bakers using flour with additives and multigrain (p<0.001). The risk of work-related asthma-like symptoms was more than doubled in bakers using additives without or with multigrain than in shop assistants (OR 2.3, 95% CI 1.0 to 5.5 and OR 3.4, 95% CI 1.1 to 10.8, respectively). Making bread with additives alone or with multigrain significantly increased the risk of work-related nasal symptoms in shop assistants, while the risk of skin symptoms was not significantly affected. CONCLUSIONS: Bakers using additives alone or with multigrain are at a high risk of experiencing nasal and asthma-like symptoms.

Prunus persica 9, a new occupational allergen from peach tree pollen involved in rhinitis and asthma.

OBJECTIVES: Several studies have described peach tree (PT) as an occupational allergen. The aim of this work was to assess the effect of Prunus persica 9 (Pru p 9), a recently identified allergen from PT pollen, in exposed workers. METHODS: The study included people who reported respiratory symptoms after handling PT in orchards during the flowering period (Blanca village, Murcia region, south-east Spain). After completing a detailed questionnaire, participants underwent skin prick test (SPT) and nasal provocation test (NPT). The IgE response was analysed by SDS-PAGE and immunoblotting assays. RESULTS: A total of 21 cases were included (mean age 45 years; 57% women). Most were polysensitised to common pollens, although one person was sensitised only to PT pollen. All cases had a positive SPT to this pollen, and 43% also to Pru p 9. All participants reported having rhinitis, and six participants reported having also asthma. Immunoblotting showed a heterogeneous IgE pattern for several proteins, with Pru p 9 recognised in nine cases. Most participants sensitised to PT pollen and Pru p 9 had positive NPTs, while those who were not sensitised to Pru p 9 tested negative. CONCLUSIONS: We demonstrate for the first time that Pru p 9, an allergen from PT pollen, can induce respiratory symptoms following occupational exposure. This must be considered a relevant allergen when people working with PT cultivars develop respiratory symptoms.

Potential classification of chemical immunologic response based on gene expression profiles.

Occupational immune diseases are a serious public health burden and are often a result of exposure to low molecular weight (LMW) chemicals. The complete immunological mechanisms driving these responses are not fully understood which has made the classification of chemical allergens difficult. Antimicrobials are a large group of immunologically-diverse LMW agents. In these studies, mice were dermally exposed to representative antimicrobial chemicals (sensitizers: didecyldimethylammonium chloride (DDAC), ortho-phthalaldehyde (OPA), irritants: benzal-konium chloride (BAC), and adjuvant: triclosan (TCS)) and the mRNA expression of cytokines and cellular mediators was evaluated using real-time qPCR in various tissues over a 7-days period. All antimicrobials caused increases in the mRNA expression of the danger signals Tslp (skin), and S100a8 (skin, blood, lung). Expression of the TH2 cytokine Il4 peaked at different timepoints for the chemicals based on exposure duration. Unique expression profiles were identified for OPA (Il10 in lymph node, Il4 and Il13 in lung) and TCS (Tlr4 in skin). Additionally, all chemicals except OPA induced decreased expression of the cellular adhesion molecule Ecad. Overall, the results from these studies suggest that unique gene expression profiles are implicated following dermal exposure to various antimicrobial agents, warranting the need for additional studies. In order to advance the development of preventative and therapeutic strategies to combat immunological disease, underlying mechanisms of antimicrobial-induced immunomodulation must be fully understood. This understanding will aid in the development of more effective methods to screen for chemical toxicity, and may potentially lead to more effective treatment strategies for those suffering from immune diseases.

Assessing the health impact of interventions for baker's allergy and asthma in supermarket bakeries: a group randomised trial.

PURPOSE: To assess the impact of an intervention for baker's allergy and asthma in supermarket bakeries. METHODS: A group randomised trial conducted in 31 bakeries (n = 337 bakers) that were randomly assigned to one of two intervention groups (n = 244 bakers) and a control group (n = 93 bakers). Health data collected prior to and 1-year after the intervention included information obtained from an ECRHS questionnaire; tests for atopy and serum-specific IgE to cereal flours; fractional exhaled nitric oxide (FeNO). Data from the two intervention groups were combined to form one intervention group for purposes of the statistical analysis. RESULTS: At 1 year of follow-up, the incidence and level of decline of work-related ocular-nasal and chest symptoms, sensitisation status and elevated FeNO (FeNO > 25 ppb) was similar in both intervention and control groups. The mean FeNO difference was also similar across both groups (2.2 ppb vs 1.7 ppb, p = 0.86). In those with FeNO > 25 ppb at baseline, the decline was greater in the intervention compared to control group (16.9 ppb vs 7.7 ppb, p = 0.24). Multivariate logistic regression models (adjusting for smoking, baseline sensitisation to cereal flour, baseline FeNO > 25 ppb) did not demonstrate an appreciable FeNO decline (≥ 10%) in the intervention compared to control group. However, stratification by the presence of work-related ocular-nasal symptoms in bakers at baseline demonstrated a significant FeNO decline (≥ 10%) in the intervention compared to the control group (OR 3.73, CI 1.22-11.42). CONCLUSION: This study demonstrates some evidence of an intervention effect on FeNO 1 year after an intervention, particularly in bakers with work-related ocular-nasal symptoms.

Prevention of baker's asthma.

PURPOSE OF REVIEW: Baker's allergy and asthma continue to represent an important contributor of occupational asthma globally. This review identified recent studies related to the prevention of baker's allergy and asthma. RECENT FINDINGS: Studies with respect to regulatory exposure standards, workplace control measures aimed at reduction of flour dust exposures, surveillance programmes (exposure monitoring, medical surveillance) and workplace information, education and training programmes were identified. SUMMARY: Detailed knowledge on risk factors and detection methods to assess exposure and early identification of high-risk workers exist, but workplace control measures remain sub-optimal because they are rarely multifaceted. This is compounded by the lack of health-based exposure standards globally. Exposure level monitoring and medical surveillance are integral to assessing effectiveness of preventive strategies. Triage systems for optimizing the efficiency of medical surveillance programmes show promise, but need replication in different contexts. Future studies need to focus on evaluating the relevance and quantification of peak exposures in increasing risk; developing standardized respiratory questionnaires for medical surveillance; and further exploration of serial fractional exhaled nitric oxide (FeNO) measurements as an adjunct to allergic sensitization for the early identification of baker's asthma and assessing the long-term impact of interventions.

Neutrophil activation in occupational asthma.

PURPOSE OF REVIEW: The aim of this review is to emphasize the role of neutrophils in patients with occupational asthma. This review facilitates a better understanding, accurate diagnosis, and proper management of asthmatic reactions provoked at the workplace. RECENT FINDINGS: Increased recruitment and infiltration of neutrophils are found in patients with occupational asthma. Activated neutrophils release several mediators including pro-inflammatory cytokines and extracellular traps, leading to stimulation of airway epithelium and other inflammatory cells. SUMMARY: New insights into neutrophils in the pathogenesis of occupational asthma may provide a novel approach to the individual patient with occupational asthma.

[Comparative characteristics of cytokine and IgE levels in patients with bronchial asthma of professional and non-professional genesis]. / Sravnitel'naia kharakteristika tsitokinov i IgE u patsientov s bronkhial'noi astmoi professional'nogo i neprofessional'nogo geneza.

A comparative evaluation of serum concentrations of cytokines and IgE production in patients with occupational bronchial asthma (BA) caused by exposure to the toxic-dust factor of the aluminum industry and patients with asthma of unprofessional genesis was carried out. A more pronounced pro-inflammatory response has been found in patients with occupational BA characterized by hyperproduction of IL-1b, IL-8. While for persons with non-professional asthma, a decrease in IL-1b, IL-5, IL-10 is characteristic. The common pattern of the detected changes in the patients of both groups consists in an increase in the production of IgE (6 times in patients with occupational BA and 8.9 times with non-occupational asthma) and a decrease in serum concentrations of TNF-a. Various cytokine manifestations in occupational and unprofessional BA may be associated with different etiopathogenetic mechanisms of disturbance of intra-immune regulation, and also confirms the professional conditionality of the revealed changes in patients with BA who work in the aluminum industry.

Allergen component analysis as a tool in the diagnosis and management of occupational allergy.

We are now in the epoch of "molecular allergology" and numerous clinically relevant allergenic molecules are available improving the performance of in vitro allergen tests and allergen detection methods. This review is focusing on characterized occupational allergens and their implementation into the in vitro diagnosis for occupational allergy and in allergen detection methods. More than 400 occupational agents are identified and documented as being 'respiratory sensitizers', but currently only a limited number of them are characterized on the molecular level and available for routine diagnosis as native or recombinant allergens. One exception, however, is natural rubber latex (NRL) from Hevea brasiliensis still remaining an important occupational allergen source. Characterization of 15 NRL allergens led to the development of assays for the determination of allergen content of NRL materials and the implementation of component-resolved diagnosis (CRD) for specific IgE antibody measurement. Microarray or singleplex using recombinant or native allergens are reliable tools for NRL allergy diagnosis. In addition, NRL allergy is an excellent model for improving extract-based specific IgE measurement by amplification of NRL extract preparation with stable recombinant major allergen rHev b 5. Despite the many efforts to characterize the occupationally relevant wheat allergens for baker's asthma, the most frequently occurring forms of occupational asthma, the results are highly diverse. Wheat sensitization profiles of bakers showed great interindividual variability and no wheat allergen could be classified as the major allergen. For diagnosis of baker's asthma, a whole wheat extract is still the best option for specific IgE determination. But single wheat allergens might help to discriminate between wheat-induced food allergy, grass pollen allergy and baker's asthma. For workplace-related allergens like coffee, wood, soybean, seafood and moulds allergens are characterized and few of them are available, but their relevance for occupational sensitization routes should be verified in the further studies.

Baker's Asthma: Is the Ratio of Rye Flour-Specific IgE to Total IgE More Suitable to Predict the Outcome of Challenge Test Than Specific IgE Alone.

Usually the diagnosis of baker's asthma is based on specific inhalation challenge with flours. To a certain extent the concentration of specific IgE to flour predicts the outcome of challenge test in bakers. The aim of this study was to evaluate whether the ratio of specific IgE (sIgE) to total IgE (tIgE) improves challenge test prediction in comparison to sIgE alone. Ninety-five bakers with work-related respiratory symptoms were challenged with rye flour. Total IgE, sIgE, and the sIgE/tIgE ratio were determined. Receiver operator characteristic (ROC) plots including the area under the curve (AUC) were calculated using the challenge test as gold-standard. Total IgE and sIgE concentrations, and their ratio were significantly higher in bakers with a positive challenge test than in those with a negative one (p < 0.0001, p < 0.0001, and p = 0.023, respectively). In ROC analysis, AUC was 0.83 for sIgE alone, 0.79 for tIgE, and 0.64 for the ratio. At optimal cut-offs, tIgE, sIgE, and the ratio reached a positive predicted value (PPV) of 95%, 84% and 77%, respectively. In conclusion, calculating the ratio of rye flour-sIgE to tIgE failed to improve the challenge test prediction in our study group.

Health surveillance for occupational asthma.

PURPOSE OF REVIEW: The outcome for workers with occupational asthma is improved for those with an earlier diagnosis. Health surveillance at work is in principle designed to identify such cases, so that the risks to the individual worker, and coworkers, can be reduced. There is recent evidence to suggest that the uptake and quality of such surveillance could be improved. This review has assessed current approaches to health surveillance for occupational asthma. RECENT FINDINGS: The article covers a review of the utility of questionnaires, lung function testing, immunological investigations, and other tests, including exhaled nitric oxide, sputum eosinophilia, and exhaled breath condensate specifically in the context of workplace-based health surveillance. SUMMARY: Questionnaires remain a key component of respiratory health surveillance, although maybe limited by both sensitivity and specificity for early occupational asthma. The role of lung function testing is debated, although is recommended for higher level health surveillance. Various examples of immunological testing in health surveillance are discussed, but more evidence is needed in many specific areas before more general recommendations can be made. Evidence is discussed in relation to the utility of newer approaches such as exhaled nitric oxide, sputum eosinophilia, and exhaled breath condensate.

Assessment of eosinophilic airway inflammation as a contribution to the diagnosis of occupational asthma.

BACKGROUND: Ascertaining the presence of asthma through the assessment of nonspecific bronchial hyperresponsiveness (NSBH) is a key step in the diagnosis of occupational asthma (OA). We aimed at investigating whether indices of airway inflammation including fractional exhaled nitric oxide (FeNO) and sputum eosinophils would be useful adjuncts to the measurement of NSBH in diagnosing OA defined as a positive specific inhalation challenge (SIC). METHODS: The study included 240 consecutive subjects with a suspicion of OA who completed a SIC, of whom 133 showed a positive response. The sensitivity, specificity, and predictive values of NSBH, and FeNO, as well as sputum eosinophil counts assessed at baseline of the SIC were determined. RESULTS: A concentration of histamine inducing a 20% decline in FEV1 (PC20 ) ≤16 mg/mL showed a sensitivity of 87% and a specificity of 36%. A FeNO level ≥25 ppb and a sputum eosinophil count ≥2% provided lower sensitivity rates (47% and 39%, respectively) than the PC20 value. Eight of the 17 subjects without baseline NSBH despite a positive SIC showed a sputum eosinophil count ≥2%, a FeNO level ≥25 ppb, or both outcomes. Combining either a PC20 value ≤16 mg/mL or a FeNO ≥25 ppb increased the sensitivity to 91%. Using either a PC20 ≤16 mg/mL or a sputum eosinophil count ≥1% increased the sensitivity to 94%. CONCLUSION: Adding the assessment of FeNO level and sputum eosinophils to NSBH improves the identification of subjects who may have OA and require further objective testing before excluding the possibility of OA.

Nasal protein profiles in work-related asthma caused by different exposures.

BACKGROUND: The mechanisms of work-related asthma (WRA) are incompletely delineated. Nasal cell samples may be informative about processes in the lower airways. Our aim was to determine the nasal protein expression profiles of WRA caused by different kind of exposures. METHODS: We collected nasal brush samples from 82 nonsmoking participants, including healthy controls and WRA patients exposed to (i) protein allergens, (ii) isocyanates and (iii) welding fumes the day after relevant exposure. The proteome changes in samples were analysed by two-dimensional difference gel electrophoresis, and the differentially regulated proteins found were identified by mass spectrometry. Immunological comparison was carried out using Western blot. RESULTS: We detected an average of 2500 spots per protein gel. Altogether, 228 protein spots were chosen for identification, yielding 77 different proteins. Compared to the controls, exposure to protein allergens had the largest effects on the proteome. Hierarchical clustering revealed that protein allergen- and isocyanate-related asthma had similar profiles, whereas asthma related to welding fumes differed. The highly overrepresented functional categories in the asthma groups were defence response, protease inhibitor activity, inflammatory and calcium signalling, complement activation and cellular response to oxidative stress. Immunological analysis confirmed the found abundance differences in galectin 10 and protein S100-A9 between the groups. CONCLUSIONS: Work-related asthma patients exposed to protein allergens and isocyanates elicit similar nasal proteome responses and the profiles of welders and healthy controls were alike. Revealed biological activities of the protein expression changes are associated with allergic inflammation and asthma.