IgE profiles of Bermuda grass pollen sensitised patients evaluated by Phleum pratense allergens Phl P 1, 2, 4, 5, 6 , 7, 11, 12

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.

Green Roof Gardens - Selecting Allergy-Friendly Vegetation: A Global Allergy and Asthma Excellence Network (GA²LEN) Position Paper

Green roof gardens are important for planetary health by mitigating the effects of urbanization. Because of the nature of green roof gardens, only particular plants can be used. The allergologic impact of these plants remains ill-characterized and guidance on building allergy-friendly green roof gardens is missing. To address this gap, we investigated the plant spectrum of several German green roof companies and categorized plants based on their primary pollination mechanism. Except for grasses, most plants were insect-pollinated and of low allergenicity. In addition, we conducted a review on the allergologic impact of plants used for green roof gardens. Our aim was to provide landscape architects with guidance on how to develop allergy-friendly green roof gardens. We highlight the need for universally accepted standards for assessing the allergenicity of roof top plants. Also, we recommend the joint development, by green roof producers and allergists, of criteria for allergy-friendly roof gardens. Their implementation may help to reduce the risk of allergen sensitization and allergy exacerbation, such as by avoiding the use of wind-pollinated plants of proven allergenicity including grasses. Green infrastructure, such as green roofs, should benefit planetary health without increasing the prevalence and burden of allergies.

Three patterns of sensitization to mugwort, timothy, birch and their major allergen components revealed by Latent class analysis

BACKGROUND

Mugwort, timothy, and birch are commonly spread pollen allergens across China. Although several studies have described the rates of sensitization to mugwort, timothy, and birch in China, most of them just on specific whole-allergen extracts but little was known about the co-sensitization characteristics of its allergen components. This study aimed to explore the patterns of sensitization to mugwort, timothy, birch, and their major allergen components.

METHOD

Serum specific IgE (sIgE) levels of allergen components of mugwort, timothy, birch, and cross-reactive carbohydrate determinants (CCD) were detected in 160 patients whose serum showed positive results to at least one of mugwort, timothy, and birch allergens via EUROBlotMaster system. Skin prick testing was utilized to assess the allergic reaction of grass, weed, and tree allergens. Latent class analysis was used to identify underlying patterns of sensitization to a series of allergen components and their corresponding extracts.

RESULTS

88.8% of patients with allergic rhinitis and/or asthma were positive for mugwort-sIgE, 30% for timothy-sIgE, and 32.5% for birch-sIgE. By using the LCA model, three sensitization patterns as "Mugwort, Art v 4, Bet v 2 and Phl p 12 co-sensitized", "Timothy, mugwort, and CCD co-sensitized", "Mugwort and Art v 1 co-sensitized" were revealed based on optimal statistical fit in this study. Compared with other clusters, participants in "Mugwort, Art v 4, Bet v 2 and Phl p 12 co-sensitized" pattern were associated with higher sensitization rates of common grass and tree pollens allergen. The spearman's coefficient between CCD and timothy was larger than the corresponding values of CCD with mugwort or birch.

CONCLUSION

CCD and profilin, as minor allergens in pollens, were associated with other pollen sIgE false positives presumably due to cross-reactivity. Patients sensitized with profilin had a significantly higher risk of sensitization to other pollens.

Clinical symptoms and biomarkers of Bermuda grass-induced allergic rhinitis using the nasal allergen challenge model

BACKGROUND

Bermuda grass is a prevalent allergen that flourishes in tropical climates. Its exposure is traditionally believed to be low in Ontario due to the colder environment. However, high sensitization rates have been observed in Kingston, Ontario.

OBJECTIVE

We sought to investigate whether its allergens can provoke allergic rhinitis (AR) symptoms in sensitized participants from south-eastern Ontario and determine if nasal allergen challenge (NAC) model is appropriate to study Bermuda grass-induced AR.

METHODS

Twenty-one participants sensitized to Bermuda grass and 12 nonallergic participants completed a titrated NAC with increasing allergen concentrations at a screening visit. Total nasal symptom score (TNSS) and peak nasal inspiratory flow were collected before allergen exposure and 10 minutes after delivery of each concentration. Twelve participants with a Bermuda grass allergy who met the qualifying criteria (TNSS ≥ 8 and peak nasal inspiratory flow fall ≥ 50%) and 11 nonallergic controls returned for single-dose NAC visit.

RESULTS

At titrated NAC, 19 of 21 sensitized participants met the criteria of positive allergic response when challenged. During single-dose NAC, participants with allergy had significantly greater TNSS between 15 minutes and 3 hours after NAC than controls. Likewise, allergic participants had a significantly increased number of nasal lavage eosinophils at both 1 and 6 hours after NAC. Bermuda grass-specific immunoglobulin E was significantly increased in Bermuda grass allergic participants at NAC than screening visit.

CONCLUSION

Although Bermuda grass is a non-native allergen in Ontario, it can induce AR symptoms in sensitized participants, and the NAC model is appropriate to study Bermuda grass-induced AR.

Diagnostic relevance of IgE sensitization profiles to eight recombinant Phleum pratense molecules

BACKGROUND

Grass pollen-related seasonal allergic rhinoconjunctivitis (SARg) is clinically heterogeneous in severity, comorbidities, and response to treatment. The component-resolved diagnostics disclosed also a high heterogeneity at molecular level. Our study aimed at analyzing the characteristics of the IgE sensitization to Phleum pratense molecules and investigating the diagnostic relevance of such molecules in childhood.

METHODS

We examined 1120 children (age 4-18 years) with SARg. Standardized questionnaires on atopy were acquired through informatics platform (AllergyCARD™). Skin prick tests were performed with pollen extracts. Serum IgE to airborne allergens and eight P. pratense molecules (rPhl p 1, rPhl p 2, rPhl p 4, rPhl p 5b, rPhl p 6, rPhl p 7, rPhl p 11, rPhl p 12) were tested by ImmunoCAP FEIA.

RESULTS

The analysis of IgE responses against eight P. pratense molecules showed 87 profiles. According to the number of molecules recognized by IgE, the more complex profiles were characterized by higher serum total IgE, higher grass-specific serum IgE, and higher number and degree of sensitization to pollens. The most frequent IgE sensitization profile was the monomolecular Phl p 1. Sensitization to Phl p 7 was a reliable biomarker of asthma, whereas Phl p 12 of oral allergy syndrome. Sensitization to Phl p 7 was associated with a higher severity of SARg, and complex profiles were associated with longer disease duration.

CONCLUSIONS

In a large pediatric population, the complexity of IgE sensitization profiles against P. pratense molecules is related to high atopic features although useless for predicting the clinical severity. The detection of serum IgE to Phl p 1, Phl p 7, and Phl p 12 can be used as clinical biomarkers of SARg and comorbidities. Further studies in different areas are required to test the impact of different IgE molecular profiles on AIT response.

Grass pollen allergens globally: the contribution of subtropical grasses to burden of allergic respiratory diseases

Grass pollens of the temperate (Pooideae) subfamily and subtropical subfamilies of grasses are major aeroallergen sources worldwide. The subtropical Chloridoideae (e.g. Cynodon dactylon; Bermuda grass) and Panicoideae (e.g. Paspalum notatum; Bahia grass) species are abundant in parts of Africa, India, Asia, Australia and the Americas, where a large and increasing proportion of the world's population abide. These grasses are phylogenetically and ecologically distinct from temperate grasses. With the advent of global warming, it is conceivable that the geographic distribution of subtropical grasses and the contribution of their pollen to the burden of allergic rhinitis and asthma will increase. This review aims to provide a comprehensive synthesis of the current global knowledge of (i) regional variation in allergic sensitivity to subtropical grass pollens, (ii) molecular allergenic components of subtropical grass pollens and (iii) allergic responses to subtropical grass pollen allergens in relevant populations. Patients from subtropical regions of the world show higher allergic sensitivity to grass pollens of Chloridoideae and Panicoideae grasses, than to temperate grass pollens. The group 1 allergens are amongst the allergen components of subtropical grass pollens, but the group 5 allergens, by which temperate grass pollen extracts are standardized for allergen content, appear to be absent from both subfamilies of subtropical grasses. Whilst there are shared allergenic components and antigenic determinants, there are additional clinically relevant subfamily-specific differences, at T- and B-cell levels, between pollen allergens of subtropical and temperate grasses. Differential immune recognition of subtropical grass pollens is likely to impact upon the efficacy of allergen immunotherapy of patients who are primarily sensitized to subtropical grass pollens. The literature reviewed herein highlights the clinical need to standardize allergen preparations for both types of subtropical grass pollens to achieve optimal diagnosis and treatment of patients with allergic respiratory disease in subtropical regions of the world.

Recombinant marker allergens in diagnosis of patients with allergic rhinoconjunctivitis to tree and grass pollens

BACKGROUND

The aim of this study was to investigate recombinant marker allergens in patients with allergic rhinoconjunctivitis to tree and grass pollens.

METHODS

Sera of 260 tree pollen- and 282 grass pollen-allergic patients were analyzed. Bet v 1 and Phl p 1/p 5 were used as marker allergens for allergies to pollen from birch and grasses. Profilin (Bet v 2 and Phl p 12) and calcium-binding protein (Bet v 4 and Phl p 7) were used as markers for polysensitization.

RESULTS

Two hundred thirty-nine (92%) patients tested positive for IgE anti-Bet v 1. All of them were positive for IgE antibodies against natural birch extract (t3), hazel (t4), and alder (t2). Bet v 1 in combination with t3 identified allergies from related trees with a sensitivity of 99.2%. Two hundred fifty-six patients (91%) tested positive for IgE anti-Phl p 1 and/or anti-Phl p 5. All of them were positive for IgE antibodies against natural timothy (g6) and rye (g12) extract. Phl p 1/p 5 and natural timothy extract identified allergies from grasses and rye with a sensitivity of 99.3%. All Patients reacting to the cross-reactive allergens Bet v 2, Phl p 12, Bet v 4, and Phl p 7 were polysensitized.

CONCLUSION

Bet v 1 in combination with natural birch pollen extract identifies allergies from related trees with a sensitivity of 99.2%. Phl p 1, Phl p 5, and natural timothy extract identifies allergies from grasses and rye in 99.3%. Reactivity to the allergens Bet v 2, Phl p 12, Bet v 4, and Phl p 7 identifies polysensitization and cross-reactivity.

Skin prick test reactivity to common aeroallergens and ARIA classification of allergic rhinitis in patients of Central Greece

Allergic rhinitis (AR) is prevalent in Mediterranean countries, but there are no epidemiological studies in the Hellenic milieu in accordance with the recent ARIA guidelines. We investigated aetiological aeroallergens in AR patients of Central Greece using the ARIA classification. Between 2002 and 2006, 911 patients with rhinitis symptomatology were interviewed and underwent Skin prick testing and 623 completed the study. Seasonal rhinitis (SAR) represented 37.6%, Perennial rhinitis (PAR) 46.4% and SAR + PAR 16%. Intermittent mild and moderate/severe AR was evident in 9.3 and 24.5%, persistent mild and moderate/severe in 23.2 and 43.0%. Persistent AR appeared in overall 66.2% of patients and was prevalent in PAR and SAR + PAR (p < 0.0001). Severity of AR symptoms did not correlate more with ARIA than with the traditional subgroups. Marked statistical (p < 0.05) differences were evident for seven aeroallergens between the four geographic areas of the study. Pollen allergy was found in 77.8% but all pollens were significantly lower in coastal areas (p < 0.001), besides Parietaria (p < 0.003). Mite sensitivity manifested in 43.2%. Alternaria affected mostly the paediatric population (p < 0.0001). 12.4% (N = 77) was monosensitive, 58.7% (N = 366) oligosensitive, and 28.9% (N = 180) polysensitive. Rhinitis and asthma comorbidity was high (45.3%) and occurrence of asthma was related with PAR (p < 0.007) and SAR + PAR (p < 0.023) but not with the ARIA classification subgroups. This study provides compelling evidence of a typical Mediterranean allergic profile of patients of Central Greece with significant regional variability. Both classifications had approximately equal diagnostic value in our study besides the fact that ARIA subdivision is considered superior in determining treatment.

Evaluation of molecular basis of cross reactivity between rye and Bermuda grass pollen allergens

BACKGROUND

Allergenic cross reactivity between the members of the Pooids (Lolium perenne, Phleum pratense, and Poa pratensis) and Chloridoids (Cynodon dactylon and Paspalum notatum) is well established. Studies using crude extracts in the past have demonstrated limited cross reactivity between the Pooids and the Chloridoids suggesting separate diagnosis and therapy. However, little is known regarding the molecular basis for the limited cross reactivity observed between the 2 groups of grasses. The present study was undertaken to gain insights into the molecular basis of cross allergenicity between the major allergens from rye and Bermuda grass pollens.

METHODS

Immunoblot inhibition tests were carried out to determine the specificity of the proteins involved in cross reactivity. Crude pollen extract and bacterially expressed and purified recombinant Lol p 1and Lol p 5 from rye grass were subjected to cross inhibition experiments with crude and purified recombinant Cyn d 1 from Bermuda grass using sera from patients allergic to rye grass pollen.

RESULTS

The immunoblot inhibition studies revealed a high degree of cross inhibition between the group 1 allergens. In contrast, a complete lack of inhibition was observed between Bermuda grass group 1 allergen rCyn d 1, and rye grass group 5 allergen rLol p 5. Crude rye grass extract strongly inhibited IgE reactivity to Bermuda grass, whereas crude Bermuda grass pollen extract showed a weaker inhibition.

CONCLUSIONS

Our data suggests that a possible explanation for the limited cross reactivity between the Pooids and Chloridoids may, in part, be due to the absence of group 5 allergen from Chloridoid grasses. This approach of using purified proteins may be applied to better characterize the cross allergenicity patterns between different grass pollen allergens.