Emerging pollen allergens

Pollen production in olive cultivars and its interannual variability

BACKGROUND AND AIMS

Olive (Olea europaea subsp. europaea var. europaea) is the most extensively cultivated fruit crop worldwide. It is considered a wind-pollinated and strictly outcrossing crop. Thus, elevated pollen production is crucial to guarantee optimum fruit set and yield. Despite these facts, the variability of pollen production within the cultivated olive has been scarcely studied. This study aimed to characterize this feature by analysing a representative set of worldwide olive cultivars.

METHODS

We evaluated the average number of pollen grains per anther in 57 principal cultivars over three consecutive years. We applied a standard generalized linear model (GLM) approach to study the influence of cultivar, year and the previous year's fruit load on the amount of pollen per anther. Additionally, the K-means method was used for cluster analysis to group cultivars based on their pollen production capacity.

KEY RESULTS

Pollen production per anther was highly variable among olive cultivars. The cultivar significantly accounted for 51.3 % of the variance in pollen production and the year for 0.3 %. The interaction between the two factors explained 8.4 % of the variance, indicating that not all cultivars were equally stable in producing pollen across the years. The previous year's fruit load and its interaction with the year were significant, but barely accounted for 1.5 % of the variance. Olive cultivars were classified into four clusters according to their capacity to produce pollen. Interestingly, the fourth cluster was composed of male-sterile cultivars, which presumably share this character by inheritance.

CONCLUSIONS

Pollen production per anther varied extensively within the cultivated olive. This variation was mainly driven by the cultivar and its interaction with the year. The differential capacity of olive cultivars to produce pollen should be considered not only for designing new orchards but also gardens where this species is used as an ornamental.

Airborne transmission of biological agents within the indoor built environment: a multidisciplinary review

The nature and airborne dispersion of the underestimated biological agents, monitoring, analysis and transmission among the human occupants into building environment is a major challenge of today. Those agents play a crucial role in ensuring comfortable, healthy and risk-free conditions into indoor working and leaving spaces. It is known that ventilation systems influence strongly the transmission of indoor air pollutants, with scarce information although to have been reported for biological agents until 2019. The biological agents' source release and the trajectory of airborne transmission are both important in terms of optimising the design of the heating, ventilation and air conditioning systems of the future. In addition, modelling via computational fluid dynamics (CFD) will become a more valuable tool in foreseeing risks and tackle hazards when pollutants and biological agents released into closed spaces. Promising results on the prediction of their dispersion routes and concentration levels, as well as the selection of the appropriate ventilation strategy, provide crucial information on risk minimisation of the airborne transmission among humans. Under this context, the present multidisciplinary review considers four interrelated aspects of the dispersion of biological agents in closed spaces, (a) the nature and airborne transmission route of the examined agents, (b) the biological origin and health effects of the major microbial pathogens on the human respiratory system, (c) the role of heating, ventilation and air-conditioning systems in the airborne transmission and (d) the associated computer modelling approaches. This adopted methodology allows the discussion of the existing findings, on-going research, identification of the main research gaps and future directions from a multidisciplinary point of view which will be helpful for substantial innovations in the field.

Poaceae pollen as the leading aeroallergen worldwide: A review

The Poaceae family comprises over 12 000 wind-pollinated species, which release large amounts of pollen into the atmosphere. Poaceae pollen is currently regarded as the leading airborne biological pollutant and the chief cause of pollen allergy worldwide. Sensitization rates vary by country, and those variations are reviewed here. Grass pollen allergens are grouped according to their protein structure and function. In Poaceae, although species belonging to different subfamilies are characterized by distinct allergen subsets, there is a considerable degree of cross-reactivity between many species. Cross-reactivity between grass pollen protein and fresh fruit pan-allergens is associated with the appearance of food allergies. The additional influence of urban pollution may prompt a more severe immunological response. The timing and the intensity of the pollen season are governed by species genetics, but plant phenology is also influenced by climate; as a result, climate changes may affect airborne pollen concentrations. This article reviews the findings of worldwide research which has highlighted the major impact of climate change on plant phenology and also on the prevalence and severity of allergic disease.

The spectrum of olive pollen allergens. From structures to diagnosis and treatment

Olive tree is one of the main allergy sources in Mediterranean countries. The identification of the allergenic repertoire from olive pollen has been essential for the development of rational strategies of standardization, diagnosis, and immunotherapy, all of them focused to increase the life quality of the patients. From its complex allergogram, twelve allergens - Ole e 1 to Ole e 12 - have been identified and characterized to date. Most of them have been cloned and produced as recombinant forms, whose availability have allowed analyzing their three-dimensional structures, mapping their T-cell and B-cell epitopes, and determining the precise allergenic profile of patients for a subsequent patient-tailored immunotherapy. Protein mutant, hypoallergenic derivatives, or recombinant fragments have been also useful experimental tools to analyze the immune recognition of allergens. To test these molecules before using them for clinic purposes, a mouse model of allergic sensitizations has been used. This model has been helpful for assaying different prophylactic approaches based on tolerance induction by intranasal administration of allergens or hypoallergens, used as free or integrated in different delivery systems, and their findings suggest a promising utilization as nasal vaccines. Exosomes - nanovesicles isolated from bronchoalveolar lavage fluid of tolerogenic mice - have shown immunomodulatory properties, being able to protect mice against sensitization to Ole e 1.

Immune responses to inhalant allergens

This overview describes the nature of the immune responses induced by the inhalation of allergens. There is a dichotomy in that B cells have multiple mechanisms that limit the amount of immunoglobulin E (IgE) antibody production, whereas T-cell responses are large even in nonallergic subjects. With the possible exception of responses to cat allergen, however, T cells from nonallergic subjects have limited effector function of helping IgG antibody, and in house-dust mite allergy, this declines with age. Regulation by interleukin 10 (IL-10)-producing cells and CD25⁺ T-regulatory cells has been proposed, but critically, there is limited evidence for this, and many studies show the highest IL-10 production by cells from allergic subjects. Recent studies have shown the importance of nonlymphoid chemokines thymic stromal lymphopoietin and IL-27, so studying responses in situ is critical. Most sources of allergens have 1 or 2 dominant allergens, and for house-dust mite, it has been shown that people have a predictable responsiveness to high-, mid-and poor-IgE-binding proteins regardless of the total size of their response. This allergen hierarchy can be used to design improved allergen preparations and to investigate how antiallergen responses are regulated.

A protein allergen microarray detects specific IgE to pollen surface, cytoplasmic, and commercial allergen extracts

Background

Current diagnostics for allergies, such as skin prick and radioallergosorbent tests, do not allow for inexpensive, high-throughput screening of patients. Additionally, extracts used in these methods are made from washed pollen that lacks pollen surface materials that may contain allergens.

Methodology/Principal Findings

We sought to develop a high-throughput assay to rapidly measure allergen-specific IgE in sera and to explore the relative allergenicity of different pollen fractions (i.e. surface, cytoplasmic, commercial extracts). To do this, we generated a protein microarray containing surface, cytoplasmic, and commercial extracts from 22 pollen species, commercial extracts from nine non-pollen allergens, and five recombinant allergenic proteins. Pollen surface and cytoplasmic fractions were prepared by extraction into organic solvents and aqueous buffers, respectively. Arrays were incubated with <25 uL of serum from 176 individuals and bound IgE was detected by indirect immunofluorescence, providing a high-throughput measurement of IgE. We demonstrated that the allergen microarray is a reproducible method to measure allergen-specific IgE in small amounts of sera. Using this tool, we demonstrated that specific IgE clusters according to the phylogeny of the allergen source. We also showed that the pollen surface, which has been largely overlooked in the past, contained potent allergens. Although, as a class, cytoplasmic fractions obtained by our pulverization/precipitation method were comparable to commercial extracts, many individual allergens showed significant differences.

Conclusions/Significance

These results support the hypothesis that protein microarray technology is a useful tool for both research and in the clinic. It could provide a more efficient and less painful alternative to traditionally used skin prick tests, making it economically feasible to compare allergen sensitivity of different populations, monitor individual responses over time, and facilitate genetic studies on pollen allergy.

Analysis of airborne pollen grains in Bilecik, Turkey

In this study, pollen grains in the atmosphere of Bilecik were studied for a continuous period of 2 years (2005 and 2006) by using Durham sampler. During this period, pollen grains belonging to 46 taxa were recorded, 26 of which belonged to arboreal plants and 20 to non-arboreal. Of total 14,269 pollen grains determined in Bilecik atmosphere, 6,675 were recorded in 2005 and 7,594 were in 2006. From these, 75.74% were arboreal, 21.80% were non-arboreal and 2.47% unidentifiable. Pinus sp., Poaceae, Cupressaceae, Platanus sp., Quercus sp., Salix sp., Ailanthus sp., Fagus sp., Urticaceae, Chenopodiaceae/Amaranthaceae were the main pollen producers in the atmosphere of Bilecik, respectively. Pollen concentrations reached their highest levels in May. Atmospheric pollen concentrations in February, March, September, October and November were less than those in other months.

Understanding patient sensitization profiles in complex pollen areas: a molecular epidemiological study

BACKGROUND

Allergy diagnosis in patients exposed to multiple pollen species is complex and misdiagnosis is often a cause for unsuccessful specific immunotherapy.

OBJECTIVE

We studied the sensitization profile of individual allergens (major, minor and pan-allergens) in pollen-sensitized patients in a region with high exposure to olive pollen by investigating the influence of minor allergens on allergic disease and the association between pan- and minor allergen sensitizations.

METHODS

A panel of 13 purified allergens, which included the most relevant allergens in the area, as well as minor olive allergens and pan-allergens, were screened using a high-capacity technology (ADVIA-Centaur) in 891 patients.

RESULTS

Olive allergy as measured by specific IgE to Ole e 1 was the leading pollinosis in the area. The minor olive allergens Ole e 7 and Ole e 9 were markers of more severe allergic illness. Profilin sensitization was associated mainly with grass allergy, the second most prevalent pollinosis. Salsola kali pollen allergy was the third most common cause of pollinosis in the area. The prevalence of sensitization to the peach allergen Pru p 3, a nonspecific lipid-transfer protein, was notable.

CONCLUSION

Epidemiological analysis by component-resolved diagnosis is a new method, which elucidates the interaction between allergen exposure gradient and patient sensitization. High exposure leads to differential sensitization profiles some of which are associated with more severe allergic conditions. Profilin sensitization, related mainly to grass pollinosis, was a marker of more severe grass pollen sensitization.

Solution structure of the C-terminal domain of Ole e 9, a major allergen of olive pollen

Ole e 9 is an olive pollen allergen belonging to group 2 of pathogenesis-related proteins. The protein is composed of two immunological independent domains: an N-terminal domain (NtD) with 1,3-beta-glucanase activity, and a C-terminal domain (CtD) that binds 1,3-beta-glucans. We have determined the three-dimensional structure of CtD-Ole e 9 (101 amino acids), which consists of two parallel alpha-helices forming an angle of approximately 55 degrees , a small antiparallel beta-sheet with two short strands, and a 3-10 helix turn, all connected by long coil segments, resembling a novel type of folding among allergens. Two regions surrounded by aromatic residues (F49, Y60, F96, Y91 and Y31, H68, Y65, F78) have been localized on the protein surface, and a role for sugar binding is suggested. The epitope mapping of CtD-Ole e 9 shows that B-cell epitopes are mainly located on loops, although some of them are contained in secondary structural elements. Interestingly, the IgG and IgE epitopes are contiguous or overlapped, rather than coincident. The three-dimensional structure of CtD-Ole e 9 might help to understand the underlying mechanism of its biochemical function and to determine possible structure-allergenicity relationships.

New insights into the pathogenesis, diagnosis and treatment of human T-cell leukemia virus type 1-induced disease

It has been over 25 years since the discovery of human T-cell leukemia virus type 1 (HTLV-1); however, the exact sequence of events that occur during primary infection, clinical latency or the development of disease remains unresolved. The advances in molecular virology and neuroimmunology have contributed significantly to our understanding of HTLV-1 pathogenesis, but also uncovered the complexity of the virus–host interaction both in the peripheral blood and the CNS. Here, we overview the general pathologic features of HTLV-1, molecular mechanisms of oncogenic transformation and characteristics of the host immune response during the associated neuroinflammatory process. We also discuss both current and new approaches in the diagnosis and therapy of HTLV-1 associated diseases – adult T-cell leukemia and HTLV-1-associated myelopathy/tropical spastic paraparesis. Finally, potentially important emerging areas of research that may have an impact on our understanding of the pathogenic mechanism have been briefly introduced.