[Study on allergen components of birch pollen in Beijing area].

Objective:To explore the allergen components of birch pollen in the Beijing area and interpret its clinical significance. Methods:A total of 58 patients with birch pollen allergy were included in the cross-sectional study and divided into allergic rhinitis（AR） and allergic asthma（AA） groups according to clinical manifestations. Concentration of birch pollen allergen sIgE, as well as Bet v 1, Bet v 2, Bet v 4 and Bet v 6 sIgE were detected by ImmunoCAP immunolinked immunoassay. Differences of sIgE concentration of birch pollen allergen component in AR and AA were analyzed. Results:There were 44（75.9%） cases of AR and 14（24.1%） cases of AA were enrolled. All the 18 patients with spring pollen allergy were AR patients without AA. There were 40 cases with both spring and autumn pollen allergy, of which 26 cases（65%） were AR and 14 cases（35%） were AA. The sIgE of birch pollen allergen was level 2 or above in all subjects. 94.8% were positive for any four allergen components. 77.6% were mono-sensitized to any allergen component while 17.2% were dual-sensitized. The positive rate of Bet v 1 and/or Bet v 2 was 93.1%. The positive rates of four protein components were: Bet v 1（82.8%）, Bet v 2（29.3%）, Bet v 6（1.7%）, Bet v 4（0%）. sIgE of birch pollen was positively correlated with sIgE level of Betv 1（r=0.898, P<0.001）. The sIgE concentration of Bet v2 in AA group was significantly higher than that in AR group（[4.34±14.35] kUA/L vs [1.56±3.26] kUA/L, P<0.05）. There was no significant difference in other components. Conclusion:Bet v 1 is the main allergen component of birch pollen in the Beijing area, and Bet v 1 plus Bet v 2 can diagnose more than 90% of birch pollen allergy.

Natural human Bet v 1-specific IgG antibodies recognize non-conformational epitopes whereas IgE reacts with conformational epitopes.

BACKGROUND: The nature of epitopes on Bet v 1 recognized by natural IgG antibodies of birch pollen allergic patients and birch pollen-exposed but non-sensitized subjects has not been studied in detail. OBJECTIVE: To investigate IgE and IgG recognition of Bet v 1 and to study the effects of natural Bet v 1-specific IgG antibodies on IgE recognition of Bet v 1 and Bet v 1-induced basophil activation. METHODS: Sera from birch pollen allergic patients (BPA, n = 76), allergic patients without birch pollen allergy (NBPA, n = 40) and non-allergic individuals (NA, n = 48) were tested for IgE, IgG as well as IgG1 and IgG4 reactivity to folded recombinant Bet v 1, two unfolded recombinant Bet v 1 fragments comprising the N-terminal (F1) and C-terminal half of Bet v 1 (F2) and unfolded peptides spanning the corresponding sequences of Bet v 1 and the apple allergen Mal d 1 by ELISA or micro-array analysis. The ability of Bet v 1-specific serum antibodies from non-allergic subjects to inhibit allergic patients IgE or IgG binding to rBet v 1 or to unfolded Bet v 1-derivatives was assessed by competition ELISAs. Furthermore, the ability of serum antibodies from allergic and non-allergic subjects to modulate Bet v 1-induced basophil activation was investigated using rat basophilic leukaemia cells expressing the human FcεRI which had been loaded with IgE from BPA patients. RESULTS: IgE antibodies from BPA patients react almost exclusively with conformational epitopes whereas IgG, IgG1 and IgG4 antibodies from BPA, NBPA and NA subjects recognize mainly unfolded and sequential epitopes. IgG competition studies show that IgG specific for unfolded/sequential Bet v 1 epitopes is not inhibited by folded Bet v 1 and hence the latter seem to represent cryptic epitopes. IgG reactivity to Bet v 1 peptides did not correlate with IgG reactivity to the corresponding Mal d 1 peptides and therefore does not seem to be a result of primary sensitization to PR10 allergen-containing food. Natural Bet v 1-specific IgG antibodies inhibited IgE binding to Bet v 1 only poorly and could even enhance Bet v 1-specific basophil activation. CONCLUSION: IgE and IgG antibodies from BPA patients and birch pollen-exposed non-sensitized subjects recognize different epitopes. These findings explain why natural allergen-specific IgG do not protect against allergic symptoms and suggest that allergen-specific IgE and IgG have different clonal origin.

Impact of meteorological parameters and air pollutants on airborne concentration of Betula pollen and Bet v 1 allergen.

The intensity of birch pollen season is expressed by seasonal pollen integral (SPIn, the sum of the mean daily pollen concentration during the birch pollination period) and the amount of Bet v 1 allergen released per birch pollen grain expressed by pollen allergen potency (PAP). Betula pollen and Bet v 1 allergen were simultaneously measured in the air of Bratislava from 2019 to 2022 by using two Burkard traps (Hirst-type and cyclone) in order to evaluate the causes of the seasonal variation in the SPIn and PAP levels. The highest SPIn (19,975 pollen/m3) was observed in 2022 and the lowest one (1484 pollen/m3) in 2021. The average daily PAP level (4.0 pg Bet v 1/pollen) was highest in 2019 and lowest (2.5 pg Bet v 1/pollen) in 2020. We found that seasonal variation in SPIn was associated mainly with the changes in environmental conditions during the pre-season period, whereas the year-to-year variation in PAP levels was attributed to environmental conditions during both pre- and in-season periods. Our results indicate that rainy weather in June 2020 and cold overcast weather in January‒February 2021 resulted in low SPIn in 2021. On the other hand, dry weather in June 2021 and warm weather in January‒February 2022 resulted in high SPIn in 2022. The low average daily PAP level in 2020 was associated with (1) low levels of gaseous air pollutants in March, when the ripening of pollen takes place; (2) an earlier start of the birch main pollen season (MPS); and (3) dry weather during the MPS. On the other hand, high PAP level in 2019 was associated with higher levels of air pollutants in March and during the MPS.

Nasal IL-13 production identifies patients with late-phase allergic responses.

BACKGROUND: There is limited knowledge on how local cytokine secretion patterns after nasal allergen challenge correlate with clinical symptoms especially with regard to the "late allergic response," which occurs in approximately 40% to 50% of patients with allergy. OBJECTIVE: We sought to characterize the immunologic and clinical nasal responses to birch pollen allergen challenge with a special focus on the late allergic response. METHODS: In this randomized, double-blind, placebo-controlled trial, birch pollen-allergic participants were challenged with birch pollen extract (n = 20) or placebo (n = 10) on 3 consecutive days. On days 1 and 3, nasal secretions were collected at selected time points over a 24-hour time course for the measurement of 33 inflammatory mediators. Clinical responses were determined through subjective symptom scores and objective nasal airflow measurements. RESULTS: Provoked participants had significantly greater clinical responses and showed significant increases in tryptase and the soluble IL-33 receptor serum stimulation 2 (sST2) in nasal secretions within minutes compared with the placebo group. Eight of 20 provoked participants displayed high IL-13 levels 2 to 8 hours after allergen provocation. This group also showed significant changes in clinical parameters, with a secondary drop in nasal airflow measured by peak nasal inspiratory flow and increased symptoms of nasal obstruction, which significantly differed from IL-13 nonresponders after 6 hours. CONCLUSIONS: IL-13 response status correlates with clinical responses and type 2 cytokine responses in the late phase after allergen provocation.

The History and Science of the Major Birch Pollen Allergen Bet v 1.

The term allergy was coined in 1906 by the Austrian scientist and pediatrician Clemens Freiherr von Pirquet. In 1976, Dietrich Kraft became the head of the Allergy and Immunology Research Group at the Department of General and Experimental Pathology of the University of Vienna. In 1983, Kraft proposed to replace natural extracts used in allergy diagnostic tests and vaccines with recombinant allergen molecules and persuaded Michael Breitenbach to contribute his expertise in molecular cloning as one of the mentors of this project. Thus, the foundation for the Vienna School of Molecular Allergology was laid. With the recruitment of Heimo Breiteneder as a young molecular biology researcher, the work began in earnest, resulting in the publication of the cloning of the first plant allergen Bet v 1 in 1989. Bet v 1 has become the subject of a very large number of basic scientific as well as clinical studies. Bet v 1 is also the founding member of the large Bet v 1-like superfamily of proteins with members-based on the ancient conserved Bet v 1 fold-being present in all three domains of life, i.e., archaea, bacteria and eukaryotes. This suggests that the Bet v 1 fold most likely already existed in the last universal common ancestor. The biological function of this protein was probably related to lipid binding. However, during evolution, a functional diversity within the Bet v 1-like superfamily was established. The superfamily comprises 25 families, one of which is the Bet v 1 family, which in turn is composed of 11 subfamilies. One of these, the PR-10-like subfamily of proteins, contains almost all of the Bet v 1 homologous allergens from pollen and plant foods. Structural and functional comparisons of Bet v 1 and its non-allergenic homologs of the superfamily will pave the way for a deeper understanding of the allergic sensitization process.

Pollen Sensitization Can Increase the Allergic Reaction to Non-Cross-Reactive Allergens in a Soy-Allergic Patient.

During and after the pollen season, an increase in food-triggered allergic symptoms has been observed in pollen-food syndrome patients, possibly due to seasonal boosting of pollen-IgE levels. It has been suggested that consumption of birch-pollen-related foods plays a role in seasonal allergenic inflammation. However, whether this increased pollen sensitization during the pollen season can also affect the allergenicity of allergens that are non-cross-reactive with birch pollen remains in question. This study presents the case of a patient with soy allergy and pollinosis, who experiences worsening of gastrointestinal (GI) symptoms during the birch pollen season even though the eliciting food factor does not cross-react with birch pollen allergens and their homologs (e.g., Bet v 1 and Gly m 4). The results showed a notable increase in sIgE for Gly m 4 (3.3 fold) and Bet v 1 (2.6 fold) during the birch pollen season compared to outside the birch pollen season, while Gly m 5 and Gly m 6 showed only a slight increase (1.5 fold). The basophil activation test (BAT) showed that in this patient Gly m 5 and Gly m 6 are clinically relevant soy allergens, which correlates with the reported clinical symptoms to processed soy. Moreover, the BAT against raw soy shows an increase in basophil activation during the birch pollen season and a negative basophil activation result outside the birch pollen season. Thus, the worsening of GI symptoms could possibly be due to an increase in IgE receptors, an over-reactive immune system, and/or significant intestinal allergic inflammation. This case highlights the importance of including allergens that do not cross-react with birch pollen and using a functional assay such as the BAT to evaluate clinical relevance when assessing birch pollen seasonal influence on soy allergenicity.

The role of IgG1 and IgG4 as dominant IgE-blocking antibodies shifts during allergen immunotherapy.

BACKGROUND: The induction of allergen-specific IgE-blocking antibodies is a hallmark of allergen immunotherapy (AIT). The inhibitory bioactivity has largely been attributed to IgG4; however, our recent studies indicated the dominance of IgG1 early in AIT. OBJECTIVES: Here, the IgE-blocking activity and avidity of allergen-specific IgG1 and IgG4 antibodies were monitored throughout 3 years of treatment. METHODS: Serum samples from 24 patients were collected before and regularly during AIT with birch pollen. Bet v 1-specific IgG1 and IgG4 levels were determined by ELISA and ImmunoCAP, respectively. Unmodified and IgG1- or IgG4-depleted samples were compared for their inhibition of Bet v 1-induced basophil activation. The stability of Bet v 1-antibody complexes was compared by ELISA and by surface plasmon resonance. RESULTS: Bet v 1-specific IgG1 and IgG4 levels peaked at 12 and 24 months of AIT, respectively. Serological IgE-blocking peaked at 6 months and remained high thereafter. In the first year of therapy, depletion of IgG1 clearly diminished the inhibition of basophil activation while the absence of IgG4 hardly reduced IgE-blocking. Then, IgG4 became the main inhibitory isotype in most individuals. Both isotypes displayed high avidity to Bet v 1 ab initio of AIT, which did not increase during treatment. Bet v 1-IgG1 complexes were enduringly more stable than Bet v 1-IgG4 complexes were. CONCLUSIONS: In spite of the constant avidity of AIT-induced allergen-specific IgG1 and IgG4 antibodies, their dominance in IgE-blocking shifted in the course of treatment. The blocking activity of allergen-specific IgG1 should not be underestimated, particularly early in AIT.

Combined Exposure to Birch Pollen and Thunderstorms Affects Respiratory Health in Stockholm, Sweden-A Time Series Analysis.

BACKGROUND: Thunderstorm asthma is a term used to describe surges in acute respiratory illnesses following a thunderstorm and is often attributed to an intense exposure to aeroallergens. Several episodes of thunderstorm asthma have been observed worldwide; however, no such cases have been described in Sweden. In Sweden, the most prominent exposure to air-borne pollen occurs during the blooming of the birch. We aimed to explore the associations between respiratory health and the combined exposure to thunderstorms and birch pollen. METHODS: We investigated the association between the daily numbers of outpatient visits due to respiratory cases and the combined exposure to thunderstorms and birch pollen during the period of 1 May-31 September in 2001-2017, in Stockholm County, Sweden, by using time series analysis with log linear models. RESULTS: We detected noticeable increases in the number of outpatient visits on both the same day (max 26%; 95% CI 1.16-1.37) and the day after (max 50%; 95% CI 1.32-1.70) the occurrence of a thunderstorm, when the concentrations of birch pollen and the number of lightning discharges were within the highest categories. CONCLUSIONS: It is possible that co-exposure to heavy thunderstorms and high concentrations of birch pollen affects the respiratory health of the Stockholm population. To the best of our knowledge, this is the first study addressing the thunderstorm-related respiratory illnesses in Sweden and the effects of birch pollen. Our study may be important for future public health advice related to thunderstorm asthma.

Fluorescence signal of proteins in birch pollen distorted within its native matrix: Identification of the fluorescence suppressor quercetin-3-O-sophoroside.

The properties of biogenic aerosol strongly depend on the particle's proteinaceous compounds. Proteins from primary biological aerosol particles (PBAPs) can cause allergic reactions in the human respiratory system or act as ice and condensation nuclei in clouds. Consequently, these particles have high impact on human health and climate. The detection of biogenic aerosol is commonly performed with fluorescence-based techniques. However, many PBAPs (i.e., pollen of birch, mugwort, or ragweed) show weak or rather low fluorescence signals in the particular protein region (λex ~ 255-280 nm, λem ~ 280-350 nm). We hypothesize that the fluorescence signal of proteins present in birch pollen is being distorted within its native matrix. In this study, we conducted in vitro quenching experiments and employed UV/Vis spectroscopy, capillary zone electrophoresis (CZE), liquid chromatography (LC), electrospray ionization mass spectrometry (ESI-MS), and multistage MS (MS2 and MS3) to target major components in birch pollen washing water (BPWW) possibly quenching the fluorescence activity of proteins and thus explaining the lack of corresponding protein fluorescent signals. We identified quercetin-3-O-sophoroside (Q3OS, MW 626 g mol-1) to be the main UV/Vis absorbing component in BPWW. Our results point out that Q3OS suppresses the fluorescence of proteins in our samples predominantly due to inner filter effects. In general, when applying fluorescence spectroscopy to analyze and detect PBAPs in the laboratory or the atmosphere, it is important to critically scrutinize the obtained spectra.

Microarray Analysis Confirms ImmunoCAP-Fluorescence Enzyme Immunoassay Results on Specific IgE in Patients with Atopic Dermatitis and Suspected Birch Pollen-Related Food Allergy.

BACKGROUND: Previous studies demonstrated that birch pollen-related foods can cause late eczematous responses in birch pollen-sensitized patients with atopic dermatitis (AD). However, suitable markers to predict birch pollen-related food allergy in patients with AD are still lacking. OBJECTIVE: We evaluated the correlation of the results from ImmunoCAP® fluorescence enzyme immunoassay (FEIA) singleplex and ImmunoCAP® immuno solid-phase allergen chip (ISAC) multiplex system in AD patients and investigated the diagnostic validity of allergen microarray analysis, measuring specific IgE (sIgE) with ImmunoCAP® ISAC to predict birch pollen-related food allergy in patients with AD. METHODS: A total of 19 children and adults with AD, existing IgE-mediated birch pollen sensitization, and suspected birch pollen-related food allergy underwent a double-blind placebo-controlled food challenge (DBPCFC) in the clinical routine. Total and sIgE levels to birch pollen, Bet v 1, Bet v 2, and birch pollen-related foods (apple, carrot, celery, and hazelnut) were determined prior to the DBPCFC by ImmunoCAP®-FEIA. Additionally, allergen microarray ImmunoCAP® ISAC analysis was performed. Data were analyzed retrospectively. RESULTS: Twelve out of 19 patients (63% responders) experienced an allergic reaction upon DBPCFC. Overall, 7 patients (37%) developed a significant deterioration of AD with a median increase of 12.4 points in the scoring of atopic dermatitis (SCORAD) index (range 10.0-15.7). Oral allergy syndrome was the predominant immediate-type symptom (n = 11/12 responders). There were no differences in sensitization frequencies regarding allergens of the pathogenesis-related protein family 10 between responders and non-responders. In all patients, correlation of IgE levels determined with ImmunoCAP® ISAC and ImmunoCAP®-FEIA, respectively, was significant with high correlation coefficients regarding birch pollen allergen extract, rBet v 1, and rBet v 2 (rs > 0.8, p < 0.001) and lower but also significant correlation coefficients regarding food allergens (rs < 0.8, p < 0.05-<0.001). CONCLUSION: ImmunoCAP® ISAC microarray allows displaying a differentiated sensitization profile in birch pollen-sensitized patients with AD. However, IgE-mediated sensitization against birch pollen-related allergens revealed by the allergen multiplex system does not predict late eczematous reactions upon DBPCFC with birch pollen-related foods.

Isotype-specific binding patterns of serum antibodies to multiple conformational epitopes of Bet v 1.

BACKGROUND: Birch pollen is an important elicitor of respiratory allergy. The major allergen, Bet v 1, binds IgE exclusively via conformational epitopes. OBJECTIVE: We identified Bet v 1-specific epitope repertoires of IgE and IgG from birch pollen-allergic and nonallergic subjects. METHODS: Chimeric proteins were created by grafting individual epitope-sized, contiguous surface patches of Bet v 1 onto a nonallergenic structural homolog and expressed in Escherichia coli. Binding of IgE, IgG1, and IgG4 from sera of 30 birch pollen-allergic and 11 nonallergic subjects to Bet v 1, 13 chimeric proteins, and 4 bacterial Bet v 1 homologs were measured by ELISA. The proportion of epitope-specific in-total Bet v 1-specific IgE and the cross-reactivity of Bet v 1-specific IgE with bacterial homologs were determined by competitive ELISA. RESULTS: Thirteen soluble, correctly folded chimeric proteins were produced. IgE from 27 of 30 birch pollen-allergic patients bound to 1 to 12 chimeric proteins (median, 4.0), with patient-specific patterns evident. Three chimeras binding IgE from the majority of sera were identified, the grafted patches of which overlapped with previously published epitopes. Patterns of IgG1 and IgG4 binding to the chimeric proteins did not correspond to the binding patterns of IgE. Sera of 19 of 30 birch pollen-allergic patients contained low amounts of IgE to bacterial homologs. Bacterial proteins were able to partially inhibit IgE binding to Bet v 1. CONCLUSION: Epitopes recognized by Bet v 1-specific antibodies from birch pollen-allergic patients are specific to each patient and differ between IgE, IgG1, and IgG4.

Very high concentrations of birch pollen in the air of selected Polish cities in 2022 - clinical implications.

INTRODUCTION: In the Polish population, the most common cause of allergic rhinitis (AR) in the spring is birch pollen. AIM: The aim of this study was to assess the basic characteristics of the birch pollen season in selected cities in central and northern Poland including Warsaw, Piotrkow Trybunalski, and Bydgoszcz in 2022, considering their clinical implications. MATERIAL AND METHOD: Pollen monitoring was conducted using the volumetric method with the Hirst-type continuous volumetric sampler. Measurements were taken in 7-day cycles, and the microscopic analysis was performed for each 24-hour period. Results During the studied period, birch pollen posed a threat in the 2nd and 3rd decades of April and the 1st and 2nd decades of May. The birch pollination intensity was reflected by the very high values of maximum average daily pollen concentration 4102 pollen/m3 in Warsaw, 4389 pollen/m3 in Piotrkow Trybunalski, 3832 pollen/m3 in Bydgoszcz and the sum of the average daily pollen concentrations (i.e. Annual Pollen Integral, APIn) from 32439 in Bydgoszcz to 37638 in Warsaw, and long periods of exposure to high concentrations (2930 days). CONCLUSIONS: The pollen season 2022 is part of an alternating 2-year cycle of the birch pollen season intensity. The variability of parameters describing the dynamics of pollen seasons over years makes it necessary to monitor information on the pollen concentration in the air during the pollen season, both by the patients with inhalant allergy and their physicians.

The impact of data assimilation into the meteorological WRF model on birch pollen modelling.

We analyse the impact of ground-based data assimilation to the Weather Research and Forecasting (WRF) meteorological model on parameters relevant for birch pollen emission calculations. Then, we use two different emission databases (BASE - no data assimilation, OBSNUD - data assimilation for the meteorological model) in the chemical transport model and evaluate birch pollen concentrations. Finally, we apply a scaling factor for the emissions (BASE and OBSNUD), based on the ratio between simulated and observed seasonal pollen integral (SPIn) to analyse its impact on birch concentrations over Central Europe. Assimilation of observational data significantly reduces model overestimation of air temperature, which is the main parameter responsible for the start of pollen emission and amount of released pollen. The results also show that a relatively small bias in air temperature from the model can lead to significant differences in heating degree days (HDD) value. This may cause the HDD threshold to be attained several days earlier/later than indicated from observational data which has further impact on the start of pollen emission. Even though the bias for air temperature was reduced for OBSNUD, the model indicates a start for the birch pollen season that is too early compared to observations. The start date of the season was improved at two of the 11 stations in Poland. Data assimilation does not have a significant impact on the season's end or SPIn value. The application of the SPIn factor for the emissions results in a much closer birch pollen concentration level to observations even though the factor does not improve the start or end of the pollen season. The post-processing of modelled meteorological fields, such as the application of bias correction, can be considered as a way to further improve the pollen emission modelling.

Prophylactic and Therapeutic Effects of Oral Immunotherapy on Birch Pollen-Induced Allergic Conjunctivitis in Mice with a Rice-Based Edible Vaccine Expressing a Hypoallergenic Birch Pollen Allergen.

We investigated the prophylactic and therapeutic effects of the oral administration of transgenic rice seeds expressing a hypoallergenic Bet v 1 derivative of allergic birch pollen conjunctivitis in mice. Transgenic rice seed depositing a chimeric molecule called TPC7 (tree pollen chimera 7) created by DNA shuffling of Bet v 1 family sequences from birch, alder and hazel in protein bodies of endosperm was generated. BALB/c mice were sensitized to birch pollen in alum and challenged with pollen in eyedrops. They were fed TPC7 transgenic or non-transgenic (control) rice seeds for 14 d before sensitization (prophylactic protocol) or 17 d after sensitization (therapeutic protocol). The clinical score and number of conjunctival eosinophils were significantly lower in TPC7-fed mice than in the control mice based on both the prophylactic and therapeutic protocols. Serum concentration of allergen-specific IgE did not differ between TPC7-fed and control groups in either protocol. Prophylactic administration of TPC7 downregulated the production of IL-4 and IFN-γ, whereas therapeutic administration of TPC7 upregulated the production of IFN-γ by allergen-stimulated splenocytes. Prophylactic or therapeutic oral administration of transgenic rice expressing TPC7 suppressed birch pollen-induced allergic conjunctivitis in mice. Feeding transgenic rice is a potentially effective approach as an allergen-specific immunotherapy for allergic conjunctivitis.

Silver birch pollen-derived microRNAs promote NF-κB-mediated inflammation in human lung cells.

The pollen of Betula pendula Roth (silver birch) is considered to be the main cause of allergy-related rhinitis in Europe and its protein-based allergens such as Bet v 1 are well characterized. However, little is known about non-protein components of birch pollen, e.g., small RNAs and their proinflammatory activity. In the present study, next-generation sequencing (NGS) and bioinformatic approaches were used for silver birch pollen (SBP)-derived microRNA profiling and evaluation of microRNA target genes and pathways in human. Human lung cells, namely WI-38 fibroblasts and A549 alveolar epithelial cells were then stimulated with SBP microRNA in vitro and imaging cytometry-based analysis of the levels of proinflammatory cytokines, autophagy parameters and small RNA processing regulators was conducted. Bioinformatic analysis revealed that SBP microRNA may interfere with autophagy, inflammation and allergy pathways in human. SBP and SBP-derived microRNA induced NF-κB-mediated proinflammatory response in human lung cells as judged by increased levels of NF-κB p65, IL-8 and TNFα. NSUN2 and NSUN5 were involved in pollen-derived microRNA processing. Pollen-derived microRNA also modulated autophagic pathway by changes in the pools of LC3B and p62 that may affect autophagy-based adaptive responses during allergic lung inflammation. We postulate that SBP-derived microRNAs can be considered as novel proinflammatory environmental agents.

Primary and pollen-associated hazelnut allergy in school-aged children in Germany: A birth cohort study.

BACKGROUND: Primary hazelnut allergy is a common cause of anaphylaxis in children, as compared to birch-pollen associated hazelnut allergy. Population-based data on hazelnut and concomitant birch-pollen allergy in children are lacking. We aimed to investigate the prevalence of primary and pollen-associated hazelnut allergy and sensitization profiles in school-aged children in Berlin, Germany. METHODS: 1570 newborn children were recruited in Berlin in 2005-2009. The school-age follow-up (2014-2017) was based on a standardized web-based parental questionnaire and clinical evaluation by a physician including skin prick tests, allergen specific immunoglobulin E serum tests and placebo-controlled double-blind oral food challenges, if indicated. RESULTS: 1004 children (63.9% response) participated in the school-age follow-up assessment (52.1% male). For 1.9% (n = 19, 95%-confidence interval 1.1%-2.9%) of children their parents reported hazelnut-allergic symptoms, for half of these to roasted hazelnut indicating primary hazelnut allergy. Symptoms of birch-pollen allergy were reported for 11.6% (n = 116 95%-CI 9.7%-13.7%) of the children. Both birch-pollen allergy and hazelnut allergy associated symptoms affected 0.6% (n = 6, 95%-CI 0.2%-1.3%) of children. Assessment of allergic sensitization was performed in 261 participants and showed that almost 20% of these children were sensitized to hazelnut, being the most frequent of all assessed food allergens, or birch-pollen, the majority to both. CONCLUSIONS: Based on parental reports hazelnut-allergic symptoms were far less common than sensitization to hazelnut. This needs to be considered by physicians to avoid unnecessary changes in diet due to sensitization profiles only, especially when there is a co-sensitization to hazelnut and birch-pollen.

Birch Pollen Related Pear Allergy: A Single-Blind Oral Challenge TRIAL with 2 Pear Cultivars.

Approximately 70% of birch pollen allergic patients in Europe experience hypersensitivity reactions to Immunoglobulin E (IgE) cross-reactive food sources. This so-called pollen-food syndrome (PFS) is defined by allergic symptoms elicited promptly by the ingestion of fruits, nuts, or vegetables in these patients. So far, in the literature, less attention has been given to Bet v 1 cross-reactive symptoms caused by pear (Pyrus communis). In the Netherlands, pears are widely consumed. The primary objective of this study was to measure the type and severity of allergic symptoms during pear challenges in birch pollen allergic patients, with a positive history of pear allergy, using two different pear varieties. Fifteen patients were included, skin prick test (SPT), prick-to-prick test (PTP), specific Immunoglobulin E (sIgE), and single-blind oral challenges were performed with two pear (Pyrus communis) varieties: the 'Cepuna' (brand name Migo®) and the 'Conference' pears. All patients were sensitized to one or both pear varieties. A total of 12 out of 15 participants developed symptoms during the 'Cepuna' food challenge and 14/15 reacted during the 'Conference' challenge. Challenges with the 'Cepuna' pears resulted in less objective symptoms (n = 2) in comparison with challenges with 'Conference' pears (n = 7). Although we did not find significance between both varieties in our study, we found a high likelihood of fewer and less severe symptoms during the 'Cepuna' challenges. Consequently selected pear sensitized patients can try to consume small doses of the 'Cepuna' pear outside the birch pollen season.