Microarray-based evaluation of selected recombinant timothy grass allergens expressed in E. Coli and N. Benthamiana.

BACKGROUND: Timothy grass (Phleum pratense) is a significant source of allergens, and recombinant allergens are increasingly used for diagnostic purposes. However, the performance of different recombinant allergen production systems in diagnostic assays needs further investigation to optimize their use in clinical settings. OBJECTIVE: The main objective of this study was to analyze and compare the diagnostic performance of recombinant timothy grass allergens produced in E. coli and N. benthamiana using a custom-made microarray chip. METHODS: Recombinant timothy grass allergens Phl p 1, Phl p 2, Phl p 5, Phl p 6, Phl p 11, and Phl p 12 were produced in E. coli and/or N. benthamiana. A total of 113 patient serum samples were tested to evaluate the diagnostic sensitivity, specificity, inter-assay variability, and correlation of allergen-specific IgE detection compared to commercial multiplex tests (ALEX and ISAC). Additionally, the prevalence of sIgE to these allergens was assessed. RESULTS: Phl p 1, Phl p 2, Phl p 5, Phl p 6 and Phl p 11 showed high or very high positive correlation in immunoreactivity with other commercial multiplex tests. Notably, Phl p 11 fused with maltose-binding protein (MBP) demonstrated high diagnostic specificity and sensitivity, with a 0.3 arbitrary cut-off value. However, a high intra-assay variation was observed. The study also assessed specific IgE prevalence to timothy grass allergens within the tested patient cohort. CONCLUSIONS: Recombinant allergens from both E. coli and N. benthamiana demonstrated strong diagnostic potential on the microarray platform, with Phl p 11 (MBP-fused) showing particularly high performance. High intra-assay variation highlights the need for further optimization in allergen formulation and microarray storage conditions. These results highlight the potential of recombinant allergens for diagnostic applications, despite challenges with allergen stability in microarray formats. Specific IgE prevalence to timothy allergens revealed a sensitization profile consistent with findings from multiple studies.

Clinical validation of grass pollen exposure chamber in patients with allergic rhinitis triggered by timothy grass.

BACKGROUND: The fluctuation in concentrations of airborne allergens frequently presents a challenge to assessing the efficacy of allergen immunotherapy (AIT) in 'field' studies. Allergen exposure chambers (AECs) are specialized medical installations developed to expose individuals to allergens at defined and consistent concentrations under a controlled environment. The aim of the study was to validate the provocation test with timothy grass pollen as well as to assess its safety in the AEC in patients with allergic rhinitis. METHODS: In the ALLEC® AEC, varying concentrations of timothy grass pollen were dispersed. Allergic symptoms were measured by total nasal symptom score (TNSS), acoustic rhinometry, peak nasal inspiratory flow (PNIF) and nasal discharge volume. Lung function, assessed through peak expiratory flow rate (PEFR) and forced expiratory volume in the first second (FEV1), was used to evaluate safety. RESULTS: The consistency of the test was proved by the stability of environmental conditions, including temperature, humidity and CO2 levels, as well as constant concentrations of grass pollen at predetermined levels ranging from 1000 to 10,000 particles per cubic meter (p/m3). Allergic individuals developed symptoms at concentrations of 3000 p/m3 and above, across all measured endpoints. Lung function was not affected throughout all the challenges. The reproducibility of symptoms was confirmed throughout the tests. The concentration of 8000 p/m3 together with a challenge duration of 120 min was found to be optimal. CONCLUSION: The study demonstrates that the ALLEC® grass pollen exposure chamber provides a reliable and safe method for inducing repeatable symptoms in patients with allergic rhinitis. This approach can be effectively applied for allergy diagnostics and clinical endpoint determination during AIT.

IgE to cross-reactive carbohydrate determinants (CCD) in childhood: Prevalence, risk factors, putative origins.

BACKGROUND: IgE antibodies to cross-reactive carbohydrate determinants (CCD) are usually clinically irrelevant but they can be a cause of false positive outcomes of allergen-specific IgE tests in vitro. Their prevalence and levels have been so far cross-sectionally examined among adult allergic patients and much less is known about their origins and relevance in childhood. METHODS: We examined CCD with a cross-sectional approach in 1263 Italian pollen allergic children (Panallergen in Paediatrics, PAN-PED), as well as with a longitudinal approach in 612 German children (Multicenter Allergy Study, MAS), whose cutaneous and IgE sensitization profile to a broad panel of allergen extracts and molecules was already known. The presence and levels of IgE to CCD were examined in the sera of both cohorts using bromelain (MUXF3) as reagent and a novel chemiluminescence detection system, operating in a solid phase of fluorescently labelled and streptavidin-coated paramagnetic microparticles (NOVEOS, HYCOR, USA). RESULTS: IgE to CCD was found in 22% of the Italian pollen allergic children, mainly in association with an IgE response to grass pollen. Children with IgE to CCD had higher total IgE levels and were sensitized to more allergenic molecules of Phleum pratense than those with no IgE to CCD. Among participants of the German MAS birth cohort study, IgE to CCD emerged early in life (even at pre-school age), with IgE sensitization to group 1 and 4 allergen molecules of grasses, and almost invariably persisted over the full observation period. CONCLUSIONS: Our results contribute to dissect the immunological origins, onset, evolution and risk factors of CCD-sIgE response in childhood, and raise the hypothesis that group 1 and/or 4 allergen molecules of grass pollen are major inducers of these antibodies through an antigen-specific, T-B cell cognate interaction.

The effectiveness of pollen allergen immunotherapy on allergic rhinitis over 18 years: A national cohort study in Denmark.

BACKGROUND: Because long-term effectiveness of pollen allergen immune therapy (AIT) for allergic rhinitis (AR) is not well-described, we studied effectiveness over 18 years in Denmark. METHODS: A register-based cohort study using data on filled prescriptions, 1995-2016, Denmark. In a cohort of 1.1 million intranasal corticosteroid inhaler users (proxy for AR), we matched users treated with grass, birch or mugwort AIT 1:2 with non-treated users on baseline year and 24 characteristics in the 3 years prior to baseline. The primary outcome was the odds ratio (OR) of using anti-allergic nasal inhaler during the pollen season in the treated versus non-treated group by years since baseline. RESULTS: Among 7760 AR patients treated with pollen AIT, the OR of using nasal inhaler 0-5 years after baseline was reduced when compared with 15,520 non-treated AR individuals (0-2 years, OR 0.84 (0.81-0.88); 3-5 years, OR 0.88 (0.84-0.92)), but was close to unity or higher thereafter (6-9 years, OR 1.03 (0.97-1.08); 10-18 years, OR 1.18 (1.11-1.26)). In post hoc analyses, results were more consistent for those who already had 3 of 3 baseline years of use, and in patients using nasal inhaler in the latest pollen season (0-2 years, OR 0.76 (0.72-0.79); 3-5 years OR 0.86 (0.81-0.93); 6-9 years, OR 0.94 (0.87-1.02); 10-18 years, OR 0.94 (0.86-1.04)) as opposed to no such use. CONCLUSIONS: Patients treated with pollen AIT in routine care to a higher degree stopped using anti-allergic nasal inhaler 0-5 years after starting the standard 3 years of therapy, and not beyond 5 years. Post hoc analyses suggested effectiveness was more consistent among patients with persistent AR.

Environmental DNA analysis of airborne poaceae (grass) pollen reveals taxonomic diversity across seasons and climate zones.

BACKGROUND: Grasses populate most biogeographical zones, and their diversity influences allergic sensitisation to pollen. Previously, the contribution of different Poaceae subfamilies to airborne pollen has mostly been inferred from historical herbarium records. We recently applied environmental (e)DNA metabarcoding at one subtropical site revealing that successive airborne grass pollen peaks were derived from repeated flowering of Chloridoid and Panicoid grasses over a season. This study aimed to compare spatiotemporal patterns in grass pollen exposure across seasons and climate zones. METHODS: Airborne pollen concentrations across two austral pollen seasons spanning 2017-2019 at subtropical (Mutdapilly and Rocklea, Queensland) and temperate (Macquarie Park and Richmond, New South Wales) sites, were determined with a routine volumetric impaction sampler and counting by light microscopy. Poaceae rbcL metabarcode sequences amplified from daily pollen samples collected once per week were assigned to subfamily and genus using a ribosomal classifier and compared with Atlas of Living Australia sighting records. RESULTS: eDNA analysis revealed distinct dominance patterns of grass pollen at various sites: Panicoid grasses prevailed in both subtropical Mutdapilly and temperate Macquarie Park, whilst Chloridoid grasses dominated the subtropical Rocklea site. Overall, subtropical sites showed significantly higher proportion of pollen from Chloridoid grasses than temperate sites, whereas the temperate sites showed a significantly higher proportion of pollen from Pooideae grasses than subtropical sites. Timing of airborne Pooid (spring), Panicoid and Chloridoid (late spring to autumn), and Arundinoid (autumn) pollen were significantly related to number of days from mid-winter. Proportions of eDNA for subfamilies correlated with distributions grass sighting records between climate zones. CONCLUSIONS: eDNA analysis enabled finer taxonomic discernment of Poaceae pollen records across seasons and climate zones with implications for understanding adaptation of grasslands to climate change, and the complexity of pollen exposure for patients with allergic respiratory diseases.

Short-course subcutaneous treatment with PQ Grass strongly improves symptom and medication scores in grass allergy.

BACKGROUND: A modified grass allergen subcutaneous immunotherapy (SCIT) product with MicroCrystalline Tyrosine and monophosphoryl lipid-A as an adjuvant system (Grass MATA MPL [PQ Grass]) is being developed as short-course treatment of grass-pollen allergic rhinitis (SAR) and/or rhinoconjunctivitis. We sought to evaluate the combined symptom and medication score (CSMS) of the optimized cumulative dose of 27,600 standardized units (SU) PQ Grass in a field setting prior to embarking on a pivotal Phase III trial. METHODS: In this exploratory, randomized, double-blind, placebo-controlled trial subjects were enrolled across 14 sites (Germany and the United States of America). Six pre-seasonal subcutaneous injections of PQ Grass (using conventional or extended regimens) or placebo were administered to 119 subjects (aged 18-65 years) with moderate-to-severe SAR with or without asthma that was well-controlled. The primary efficacy endpoint was CSMS during peak grass pollen season (GPS). Secondary endpoints included Rhinoconjunctivitis Quality of Life Questionnaire standardized (RQLQ-S) and allergen-specific IgG4 response. RESULTS: The mean CSMS compared to placebo was 33.1% (p = .0325) and 39.5% (p = .0112) for the conventional and extended regimens, respectively. An increase in IgG4 was shown for both regimens (p < .01) as well as an improvement in total RQLQ-S for the extended regimen (mean change -0.72, p = .02). Both regimens were well-tolerated. CONCLUSIONS: This trial demonstrated a clinically relevant and statistically significant efficacy response to PQ Grass. Unprecedented effect sizes were reached for grass allergy of up to ≈40% compared to placebo for CSMS after only six PQ Grass injections. Both PQ Grass regimens were considered equally safe and well-tolerated. Based on enhanced efficacy profile extended regime will be progressed to the pivotal Phase III trial.

RNA sequencing of single allergen-specific memory B cells after grass pollen immunotherapy: Two unique cell fates and CD29 as a biomarker for treatment effect.

BACKGROUND: Sublingual immunotherapy (SLIT) for grass pollen allergy can modify the natural history of allergic rhinitis and is associated with increased allergen-specific IgG4 . IgG4 competitively inhibits functional IgE on the surface of effector cells, such as mast cells and basophils, from binding to allergens. To further understand the important role memory B-cell (Bmem) responses play in mediating the beneficial effects of SLIT, we assessed changes in allergen-specific Bmem subsets induced by SLIT for grass pollen allergy. METHODS: Blood samples were collected twice outside the pollen season from twenty-seven patients with sensitization to ryegrass pollen (RGP; Lolium perenne) and seasonal rhinoconjunctivitis. Thirteen received 4-month pre-seasonal SLIT for grass pollen allergy, and 14 received standard pharmacotherapy only. Single-cell RNA sequencing was performed on FACS-purified Lol p 1-specific Bmem before and after SLIT from four patients, and significant genes were validated by flow cytometry on the total cohort. RESULTS: Four months of SLIT increased RGP-specific IgE and IgG4 in serum and induced two Lol p 1-specific Bmem subsets with unique transcriptional profiles. Both subsets had upregulated expression of beta 1 integrin ITGB1 (CD29), whereas IGHE (IgE), IGHG4 (IgG4 ), FCER2 (CD23), and IL13RA1 were upregulated in one subset. There was an increase in the proportion of Lol p 1+ Bmem expressing surface IgG4 , CD23, and CD29 after SLIT. CONCLUSIONS: A clinically successful 4 months course of SLIT for grass pollen allergy induces two transcriptionally unique Bmem fates. Associated changes in surface-expressed proteins on these Bmem subsets can be used as early biomarkers for treatment effects.

A Pilot Study to Identify Grass Species That Mediate Pollen Allergy in Thailand.

INTRODUCTION: Some grass species that are either common or widely spread in Thailand have not been used for pollen allergy diagnosis. In order to improve diagnostic accuracy, the aim of this pilot study was to identify the grass species responsible for pollen allergy in Thailand. METHODS: The skin sensitization of pollen extracts from six different grass species, including rice (Oryza sativa), corn (Zea mays), sorghum (Sorghum bicolor), para grass (Urochloa mutica), ruzi grass (Urochloa eminii), and green panic grass (Megathyrsus maximus), was evaluated by skin prick test (SPT). Serum's IgE specific to each pollen extract was analyzed by Western blot (WB). The ImmunoCAPTM test for Johnson grass was also evaluated. RESULTS: Of the thirty-six volunteers who participated in this study, eighteen tested positive for at least one of the diagnostic tests, namely SPT, WB analysis, or ImmunoCAPTM. Notably, skin reactivity to para grass, corn, sorghum, and rice was more commonly observed compared to ruzi grass and green panic grass. However, in the WB analysis, individuals with pollen-specific IgE were more frequently detected in sorghum, green panic grass, corn, rice, and ruzi grass than para grass. CONCLUSION: In this pilot investigation, our findings indicate that the pollen extracts of rice, corn, sorghum, and para grass are associated with pollen allergy in Thailand. These results contribute to the current knowledge on the identification of grass species that are associated with pollen allergy in Thailand and Southeast Asia.

Increased Focus on Internal Body Sensations Is Associated with Higher Patient-Perceived Severity of Allergic Rhinitis.

BACKGROUND: Monitoring allergic rhinitis (AR) severity with objective biomarkers is important for the clinical management of patients as well as for research purposes. The most commonly used tool for the assessment of AR severity is the Total Nasal Symptom Score (TNSS). Objective biomarkers like skin prick test size or specific IgE levels do not correlate with TNSS. OBJECTIVE: We hypothesize that the psychological factors are the missing link between patient-perceived severity of AR and objective biomarkers. METHOD: Thirty-nine patients (median age: 34 years; 21 [54%] female) with grass pollen-related AR were enrolled in our study. Patients allergic for perennial allergens and allergens with potentially overlapping seasons including cypress, ash/olive, plane, and nettle families were excluded. Patient-reported outcomes included symptom score, medication scores, combined score, and Juniper Mini Rhinitis Quality of Life Questionnaire (minRQLQ). Psychometric evaluation was performed using 5 different psychological questionnaires that measure 13 different psychological factors. RESULTS: There was a significant correlation between the symptom score and private body consciousness (r = 0.50, p = 0.001) and neuroticism (R = 0.41 and p = 0.01). There was also a statistically significant correlation between the combined score and private body consciousness (r = 0.49 and p = 0.001) and with perceiving and understanding emotions (r = 0.34 and p = 0.04). The miniRQLQ score had a positive correlation with private body consciousness (r = 0.55 and p = 0.002) and observing (r = 0.42 and p = 0.02). CONCLUSIONS: Our data suggest that patients who are more aware of internal stimuli, as well as those who are highly self-conscious and somatically concerned tend to experience more severe AR symptoms.

Airborne grass pollen and thunderstorms influence emergency department asthma presentations in a subtropical climate.

BACKGROUND: Grass pollen is considered a major outdoor aeroallergen source worldwide. It is proposed as a mechanism for thunderstorm asthma that lightning during thunderstorms promotes electrical rupture of pollen grains that leads to allergic airway inflammation. However, most evidence of associations between grass pollen and asthma comes from temperate regions. The objective of this study was to investigate short-term associations between airborne grass pollen exposure and asthma emergency department presentations in a subtropical population. METHODS: Episode level public hospital presentations for asthma (2016-2020) were extracted for greater Brisbane, Australia, from Queensland Health's Emergency Data Collection. Concentrations of airborne pollen were determined prospectively using a continuous flow volumetric impaction sampler. Daily time series analysis using a generalised additive mixed model were applied to determine associations between airborne grass pollen concentrations, and lightning count data, with asthma presentations. RESULTS: Airborne grass pollen showed an association with asthma presentations in Brisbane; a significant association was detected from same day exposure to three days lag. Grass pollen exposure increased daily asthma presentations up to 48.5% (95% CI: 12%, 85.9%) in female children. Lightning did not modify the effect of grass pollen on asthma presentations, however a positive association was detected between cloud-to-cloud lightning strikes and asthma presentations (P = 0.048). CONCLUSION: Airborne grass pollen exposure may exacerbate symptoms of asthma requiring urgent medical care of children and adults in a subtropical climate. This knowledge indicates an opportunity for targeted management of respiratory allergic disease to reduce patient and health system burden. For the first time, an influence of lightning on asthma was detected in this context. The outcomes support a need for continued pollen monitoring and surveillance of thunderstorm asthma risk in subtropical regions.

Skin Physiology, Mucosal Functions, and Symptoms Are Modulated by Grass Pollen and Ozone Double Exposure in Allergic Patients.

INTRODUCTION: Along with climate changes, we see an increase in allergic symptoms and the number of pollen-allergic patients in many countries. Increased allergic symptoms are associated with an elevated ozone exposure which may be linked by impaired epithelial barrier function. This study aimed to quantify the clinical effect of ozone and pollen double exposure (DE). We tested whether ozone impairs barrier-related skin physiology and mucosal functions under DE with pollen in grass pollen-allergic patients versus healthy controls. METHODS: This case-control study included 8 grass pollen-allergic patients and 8 non-allergic healthy subjects exposed to grass pollen and ozone in the GA2LEN pollen chamber, comparing shorter and longer DE duration. Non-invasive skin physiological parameters were assessed, including stratum corneum hydration, skin redness, surface pH, and basal transepidermal water loss as a parameter for epidermal barrier function. The subjects' general well-being, bronchial, nasal, and ocular symptoms were documented. RESULTS: Skin physiology tests revealed that DE in allergic patients deteriorates the epidermal barrier function and increases the surface pH and skin redness. DE significantly induced nasal secretion in pollen-allergic versus healthy subjects, which was more pronounced with longer DE. The general well-being was significantly impaired under DE versus pollen or ozone alone, with a negative influence of DE duration. No relevant bronchial symptoms were recorded. CONCLUSION: Skin physiology and nasal mucosal symptoms are negatively affected by ozone and grass pollen DE in allergic patients. The negative effects showed, in some parameters, a dose (time)-response relationship. The pH can be regarded as a possible modulatory mechanism.

IL-31 transgenic mice show reduced allergen-induced lung inflammation.

Interleukin-31 (IL-31) is a Th2 cell-derived cytokine that has been closely linked to pruritic skin inflammation. More recently, enhanced IL-31 serum levels have also been observed in patients with allergic rhinitis and allergic asthma. Therefore, the main aim of this study was to unravel the contribution of IL-31 to allergen-induced lung inflammation. We analyzed lung inflammation in response to the timothy grass (Phleum pratense) pollen allergen Phl p 5 in C57BL/6 wild-type (wt) mice, IL-31 transgenic (IL-31tg) mice, and IL-31 receptor alpha-deficient animals (IL-31RA-/- ). IL-31 and IL-31RA levels were monitored by qRT-PCR. Cellular infiltrate in bronchoalveolar lavage fluid (BALF) and lung tissue inflammation, mucus production as well as epithelial thickness were measured by flow cytometry and histomorphology. While allergen challenge induced IL-31RA expression in lung tissue of wt and IL-31tg mice, high IL-31 expression was exclusively observed in lung tissue of IL-31tg mice. Upon Phl p 5 challenge, IL-31tg mice showed reduced numbers of leukocytes and eosinophils in BALF and lung tissue as well as diminished mucin expression and less pronounced epithelial thickening compared to IL-31RA-/- or wt animals. These findings suggest that the IL-31/IL-31RA axis may regulate local, allergen-induced inflammation in the lungs.

Clinical impact and immunological alterations in asthmatic patients allergic to grass pollen subjected to high urban pollution in Madrid.

BACKGROUND: The prevalence of asthma has increased in recent decades. Among the reasons for this increase is environmental pollution. Pollutants cause bronchial inflammation and introduce modifications in the pollen, making it more allergenic. OBJECTIVE: Assess symptoms and medication requirements of asthmatic patients with grass allergies in Madrid (high urban pollution) and Ciudad Real (low pollution), and simultaneously evaluate the in vitro effects that pollen collected in both areas has on the immune cells of patients. METHODS: During two pollen seasons, patients from both cities were included. The patients recorded their symptoms and the asthma medication they took daily. In both cities, pollen data, pollutants and meteorological variables were evaluated. The response to different cell populations from patients in both areas were analysed after "in vitro" stimulation with pollen from both cities. RESULTS: The symptoms and medication use of the patients in Madrid was 29.94% higher. The NO2 concentration in Madrid was triple that of Ciudad Real (33.4 vs. 9.1 µg/m3 of air). All other pollutants had very similar concentrations during the study period. Pollen from the high pollution area caused a significant enhancement of T-CD8+ and NK cells proliferation compared with pollen of low pollution area, independently of the patient's origin. CONCLUSION: Asthmatic patients from Madrid have a worse clinical evolution than those from Ciudad Real because of higher levels of urban pollution, and this could be driven by the higher capacity of pollen of Madrid to activate T-CD8+ and NK cells.

The AusPollen partnership project: Allergenic airborne grass pollen seasonality and magnitude across temperate and subtropical eastern Australia, 2016-2020.

BACKGROUND: Allergic rhinitis affects half a billion people globally, including a fifth of the Australian population. As the foremost outdoor allergen source, ambient grass pollen exposure is likely to be altered by climate change. The AusPollen Partnership aimed to standardize pollen monitoring and examine broad-scale biogeographical and meteorological factors influencing interannual variation in seasonality of grass pollen aerobiology in Australia. METHODS: Daily airborne grass and other pollen concentrations in four eastern Australian cities separated by over 1700 km, were simultaneously monitored using Hirst-style samplers following the Australian Interim Pollen and Spore Monitoring Standard and Protocols over four seasons from 2016 to 2020. The grass seasonal pollen integral was determined. Gridded rainfall, temperature, and satellite-derived grassland sources up to 100 km from the monitoring site were analysed. RESULTS: The complexity of grass pollen seasons was related to latitude with multiple major summer-autumn peaks in Brisbane, major spring and minor summer peaks in Sydney and Canberra, and single major spring peaks occurring in Melbourne. The subtropical site of Brisbane showed a higher proportion of grass out of total pollen than more temperate sites. The magnitude of the grass seasonal pollen integral was correlated with pasture greenness, rainfall and number of days over 30 °C, preceding and within the season, up to 100 km radii from monitoring sites. CONCLUSIONS: Interannual fluctuations in Australian grass pollen season magnitude are strongly influenced by regional biogeography and both pre- and in-season weather. This first continental scale, Southern Hemisphere standardized aerobiology dataset forms the basis to track shifts in pollen seasonality, biodiversity and impacts on allergic respiratory diseases.

Sensitization to genuine markers of timothy grass pollen (Phleum pratense) in the North-Central region of Portugal.

Summary: Pollens are the main cause of respiratory allergies which prevalence is increasing. The most important cause of pollinosis in Europe and especially in the Mediterranean countries as Portugal is Poaceae family pollen. Timothy grass (Phleum pratense) is one of the most common pollen sources, and one of the best characterized allergenic grasses. The major allergens Phl p1 and Phl p5 are considered markers of genuine grass pollen sensitization. A characterization of Phl p1 and Phl p5 sensitization in the North-Central region of Portugal was made in children and adults. Phl p1 sensitization was the most frequent.

Associations between grass pollen exposures in utero and in early life with food allergy in 12-month-old infants.

Birth during pollen seasons may influence food allergy risk but no study has assessed pollen exposure. Using the HealthNuts population-based cohort of 5276 infants, we assessed grass pollen exposures, in utero and up to the first 6 months of life, on hen's egg, sesame and peanut allergy outcomes at 12 months. Cumulative pollen exposure in the first 7 days of life increased risk of peanut sensitization aMOR (adjusted multinomial odds ratio) = 1.21 (95% CI: 1.01-1.44). Exposure between first 4-6 months of life increased risk of hen's egg aMOR = 1.02 (95% CI: 1.004-1.04) and sensitization to all foods aMOR = 1.02 (95% CI: 1.003-1.04). Grass pollen exposure was associated with food challenge diagnosed food allergy, but only among infants with a maternal history of food allergy. Exposure to grass pollen in the intrauterine period and infancy may be important but more studies are needed to replicate these findings.

Interference of Dermatophagoides pteronyssinus sensitization in grass pollen allergy.

Summary: Background. Climate conditions in the northwest of Spain are from the rest of the country, and the pollen sensitisation rates and allergens involved are different. The present study aimed to investigate the sensitisation profile of patients with grass pollen allergy and the interference of other sensitisations in respiratory symptoms. Methods. A total of 959 Spanish patients with seasonal respiratory symptoms and a positive skin prick test (SPT) to Phleum pratense pollen were studied. Patients were classified as having rhinitis and/or bronchial asthma. A battery of SPTs, including common weeds and tree pollens, profilin, polcalcin, moulds, Dermatophagoides pteronyssinus, Lepidoglyphus destructor, and cat and dog dander were performed. Serum specific IgE (sIgE) to Phl p 1 and Phl p 5, adding sIgE to Phl p 7, Phl p 12 and house dust mites (HDMs) or other pollens in selected cases were measured. Results.The majority (89.8%) of the patients were polysensitised according to SPT. HDM co-sensitisation was the most prevalent (62.3%). Profilin and polcalcin rendered a positive result in 25.9% and 18.7% of the patients, respectively. A higher proportion of patients recognized sIgE to Phl p 1 (88.7%) with respect to Phl p 5 (59%). Phl p 1-sIgE levels were higher than Phl p 5-sIgE levels, and no differences were found in patients with rhinitis and/or asthma. However, total serum IgE was higher in patients with asthma. Multivariate regression analyses revealed that only sIgE to Dermatophagoides pteronyssinus (after adjusting by sIgE to Phl p 1, Phl p 5 and Lepidoglyphus destructor) was associated with a greater risk of asthma. Conclusions. Phl p 1 is the most relevant allergen in patients with grass pollen allergy in the northwest of Spain. Sensitisation rates against panallergens are low. Even in patients with grass pollen allergy, HDM sensitisation plays a relevant role in asthma.

Allergen-specific IgG+ memory B cells are temporally linked to IgE memory responses.

BACKGROUND: IgE is the least abundant immunoglobulin and tightly regulated, and IgE-producing B cells are rare. The cellular origin and evolution of IgE responses are poorly understood. OBJECTIVE: The cellular and clonal origin of IgE memory responses following mucosal allergen exposure by sublingual immunotherapy (SLIT) were investigated. METHODS: In a randomized double-blind, placebo-controlled, time course SLIT study, PBMCs and nasal biopsy samples were collected from 40 adults with seasonal allergic rhinitis at baseline and at 4, 8, 16, 28, and 52 weeks. RNA was extracted from PBMCs, sorted B cells, and nasal biopsy samples for heavy chain variable gene repertoire sequencing. Moreover, mAbs were derived from single B-cell transcriptomes. RESULTS: Combining heavy chain variable gene repertoire sequencing and single-cell transcriptomics yielded direct evidence of a parallel boost of 2 clonally and functionally related B-cell subsets of short-lived IgE+ plasmablasts and IgG+ memory B cells. Mucosal grass pollen allergen exposure by SLIT resulted in highly diverse IgE and IgGE repertoires. These were extensively mutated and appeared relatively stable as per heavy chain isotype, somatic hypermutations, and clonal composition. Single IgGE+ memory B-cell and IgE+ preplasmablast transcriptomes encoded antibodies that were specific for major grass pollen allergens and able to elicit basophil activation at very low allergen concentrations. CONCLUSION: For the first time, we have shown that on mucosal allergen exposure, human IgE memory resides in allergen-specific IgG+ memory B cells. These cells rapidly switch isotype, expand into short-lived IgE+ plasmablasts, and serve as a potential target for therapeutic intervention.

Sensitization to grass pollen allergen molecules in a birth cohort-natural Phl p 4 as an early indicator of grass pollen allergy.

BACKGROUND: Grass pollen allergy is one of the most common allergies worldwide. OBJECTIVE: The aim of this study was to evaluate the usefulness of grass pollen allergen molecules for prediction of grass pollen allergy during childhood and up to adolescence. METHOD: Questionnaire data and sera obtained from the study subjects at the ages of 4, 8, and 16 years from the population-based Barn/Children Allergy Milieu Stockholm Epidemiology birth cohort were used. Sera from 763 representative subjects with serum samples available at all 3 ages were analyzed for IgE reactivity to 8 Phleum pratense (Phl p) allergens (MeDALL [Mechanisms for the Development of Allergies] chip) and to timothy grass extract (ImmunoCAP). Allergic rhinitis to grass pollen (ARg) was defined as upper airway symptoms during grass pollen exposure. RESULTS: The prevalence of sensitization to any Phl p molecule was higher compared with that to timothy extract at all 3 ages: at the age of 4 years, 9.7% versus 6.8%; at the age of 8 years, 28.4% versus 15.3%; and at the age of 16 years, 37.1% versus 27.1%. General estimating equations analyses revealed that among children sensitized at the age of 4 years, the overall odds ratio (OR) of later ARg (up to 16 years) was increased only for IgE reactivity to Phl p 1 (OR = 4.9) and natural Phl p 4 (OR = 6.9). The likelihood of later symptoms increased with the number of allergen molecules; at the age of 4 years, 2 or more molecules predicted ARg to 78% and 3 or more molecules predicted ARg to 95%. A positive test result for timothy extract predicted ARg to 70%. CONCLUSIONS: Natural Phl p 4 is a hitherto unrecognized early indicator of grass pollen allergy, in addition to Phl p 1. To identify grass pollen sensitization and predict later ARg, allergen molecules are of added value to timothy extract alone and may help clinicians improve prediction of grass pollen allergy.

TGFß1 mimetic peptide modulates immune response to grass pollen allergens in mice.

BACKGROUND: Transforming growth factor ß1 (TGFß1) is a cytokine that exerts immunosuppressive functions, as reflected by its ability to induce regulatory T (Treg) cell differentiation and inhibit Th1 and Th2 responses. Hence, peptides that mimic the active core domain of TGFß1 may be promising candidates for modulation of the allergic response. This study aimed to investigate a synthetic TGFß1 mimetic peptide (TGFß1-mim) for its ability to modulate the immune response during allergic sensitization to grass pollen allergens. METHODS: The in vitro action of TGFß1-mim was evaluated in human lung epithelial cells, Jurkat cells, and rat basophilic leukemia cells. The in vivo action was evaluated in a murine model of Phl p 5 allergic sensitization. Additionally, the Th2 modulatory response was evaluated in IL-4 reporter mice. RESULTS: In vitro, TGFß1-mim downregulated TNF-α production, IL-8 gene expression, and cytokine secretion, upregulated IL-10 secretion, and inhibited Phl p 5-induced basophil degranulation. During Phl p 5 sensitization in mice, TGFß1-mim downregulated IL-2, IL-4, IL-5, IL-13, and IFN-γ, upregulated IL-10, and induced Treg cell production. Furthermore, mice treated with TGFß1-mim had lower levels of IgE, IgG1, IgG2a and higher levels of IgA antibodies than control mice. In a reporter mouse, the mimetic inhibited Th2 polarization. CONCLUSION: The TGFß1-mim efficiently modulated various important events that exacerbate the allergic microenvironment, including the production of main cytokines that promote Th1 and Th2 differentiation, and the induction of allergen-specific regulatory T cells, highlighting its potential use in therapeutic approaches to modulate the immune response toward environmental allergens.