Seasonal asthma caused by airborne Platanus pollen

On pollen and airborne virus transmission

This study investigates how airborne pollen pellets (or grains) can cause severe respiratory-related problems in humans. Given that pollen pellets can capture ribonucleic acid viruses, we show that airborne pollen grains could transport airborne virus particles such as the airborne coronavirus (CoV) disease (COVID-19) or others. We consider the environmental conditions featuring the highest pollen concentration season and conduct computational multiphysics, multiscale modeling and simulations. The investigation concerns a prototype problem comprising the transport of 10⁴ airborne pollen grains dropped from a mature willow tree at a wind speed of ( U wind = 4   km / h ) . We show how pollen grains can increase the coronavirus (CoV) transmission rate in a group of people, including some infected persons. In the case of high pollen grains concentrations in the air or during pollination in the spring, the social distance of 2 m does not hold as a health safety measure for an outdoor crowd. Thus, the public authorities should revise the social distancing guidelines.

Identification and characterization of PaGL1-like genes from Platanus acerifolia related to the regulation of trichomes

Two PaGL1-like genes were identified in London plane and functional in Arabidopsis, moreover, may play an important role in the regulation of trichome development in London plane. Trichome development is governed by a complex regulatory network. In Arabidopsis, subgroup 15 of the R2R3 MYB transcription factor family, which includes GLABRA1 (GL1), is involved in trichome development. In this study, we isolated and characterized two PaGL1-like genes from London plane (Platanus acerifolia). Sequence alignment and phylogenetic analysis indicated that these PaGL1-like genes are homologous to AtGL1. Quantitative real-time PCR (qRT-PCR) analysis showed that PaGL1-like1 was expressed in all of the tested organs taken from adult London plane trees, including trichomes, petioles after trichome removal, stems after trichome removal, and leaves after trichome removal, and also in the roots, cotyledons, hypocotyls and true leaves of seedlings. By contrast, the PaGL1-like2 was expressed only in the trichomes and leaves after trichome removal from adult trees, and in the cotyledons and true leaves of seedlings. Overexpression of PaGL1-like genes caused trichome abortion when transferred into wild type Arabidopsis and promoted trichome formation in the gl1 mutant. The expression profiles of some trichome-related genes were changed in transgenic Arabidopsis lines, and yeast two-hybrid analysis indicated that PaGL1-like proteins can directly interact with trichome-related bHLH proteins from both P. acerifolia and Arabidopsis. These results suggest that PaGL1-like genes are functional in Arabidopsis and may play an important role in the regulation of trichome development in London plane.

PaMYB82 from Platanus acerifolia regulates trichome development in transgenic Arabidopsis

The control of epidermal cell fate is an elaborate molecular process mediated by the TTG1-bHLH-MYB regulatory complex. In this study, we isolated PaMYB82 from London plane. PaMYB82 was revealed to be a nuclear-localized transcription activator and was found to be expressed ubiquitously in the tissues of roots, stems, leaves, cotyledons and hypocotyls. Expression of the PaMYB82 gene under the control of the viral CaMV35S promoter caused a nearly glabrous phenotype in wild type Arabidopsis and can partially rescue the gl1 mutant phenotype. Protein interaction analysis revealed that PaMYB82 physically interacts with PaGL3 and itself, in addition, PaMYB82 could interact with trichome related bHLH transcription factors AtGL3, AtEGL3 and AtMYC1. Expression levels of AtGL2, AtTTG2 and several R3 MYB genes were greatly increased in 35S::PaMYB82 lines. The expression of AtMYB23 was reduced in 35S::PaMYB82 transgenic lines, whereas, expression levels of AtGL1 remained unchanged indicating that differences in the transcriptional regulation of AtMYB23 and AtGL1 during trichome development. Together, the data presented here indicate that PaMYB82 encodes a functional R2R3 MYB transcription factor which can control the initiation of Arabidopsis trichome development.

Single-repeat R3 MYB transcription factors from Platanus acerifolia negatively regulate trichome formation in Arabidopsis

Four R3 MYB genes were cloned and identified from Platanus acerifolia and analysed according to endogenous gene expression profiles, protein-protein interaction patterns, phenotypic effects and related gene expression profiles in transgenic Arabidopsis, suggesting that London plane R3 MYB genes inhibit trichome formation in Arabidopsis. The CPC-like MYB transcription factors including CAPRICE (CPC), TRIPTYCHON (TRY), ENHANCER OF TRY AND CPC 1, 2 and 3 (ETC1, ETC2 and ETC3), TRICHOMELESS1 (TCL1) and TRICHOMELESS2(TCL2) play important roles in controlling trichome patterning in Arabidopsis. In this study, four sequences homologous with the Arabidopsis CPC family were identified from London plane and named PaTRY, PaCPC-like1, PaCPC-like2 and PaCPC-like3. Over-expression of PaTRY, PaCPC-like1, PaCPC-like2 and PaCPC-like3 in Arabidopsis resulted in glabrous phenotypes. In addition, expression of endogenous GL2, GL1, MYB23, TTG2 and a set of R3 MYB-encoding genes was markedly reduced. Furthermore, the protein products of PaTRY, PaCPC-like1, PaCPC-like2 and PaCPC-like3 were shown to interact with PaGL3 in yeast two-hybrid assays. Together, these results likely suggest that the mechanisms of trichome regulation in London plane have similarities with those in Arabidopsis.

Molecular cloning of plane pollen allergen Pla a 3 and its utility as diagnostic marker for peach associated plane pollen allergy

BACKGROUND

Non-specific lipid transfer proteins (nsLTP) are considered to provoke allergic symptoms to plane tree pollen, which are frequently associated with peach allergy.

OBJECTIVE

The objective was to clone the cDNA of plane pollen nsLTP Pla a 3, to characterize IgE-binding and allergenic potency of recombinant Pla a 3 in comparison to its natural counterpart and peach nsLTP Pru p 3.

METHODS

Natural Pla a 3 was purified from plane pollen and analysed by mass spectrometry (MS). Recombinant Pla a 3 was characterized by SDS-PAGE and CD spectroscopy. Specific IgE to extract, components of plane pollen and Pru p 3 was measured by ImmunoCAP in sera of patients allergic to either plane pollen (n = 10), peach (n = 15) or both (n = 15). Biological potency of the proteins was investigated by in vitro mediator release assays and IgE cross-reactivity by competitive ELISA.

RESULTS

Two Pla a 3 isoforms were identified. Recombinant Pla a 3 showed high purity, structural integrity, IgE-binding capacity comparable to nPla a 3 and biological potency. Sensitization to plane pollen extract was confirmed in 24/25 plane pollen allergics. The frequency of sensitization to Pla a 3 was 53% among patients allergic to both plane pollen and peach and 10% among plane pollen allergics tolerating peach where most patients were sensitized to Pla a 1. Pla a 3 and Pru p 3 showed strong bi-directional IgE cross-reactivity in patients allergic to peach and plane pollen, but not in peach allergics tolerating plane pollen. Levels of IgE-binding were generally higher to Pru p 3 than to Pla a 3.

CONCLUSION

Sensitization to Pla a 3 is relevant in a subgroup of plane pollen allergics with concomitant peach allergy. IgE testing with Pla a 3 may serve as a marker to identify plane pollen allergic patients at risk of LTP-mediated food reactions and thereby improve in vitro diagnostic procedures.

Expression and purification of a major allergen, Pla a 1, from Platanus acerifolia pollen and the preparation of its monoclonal antibody

Platanus acerifolia pollen is considered an important source of airborne allergens in numerous cities. Pla a 1 is a major allergen from P. acerifolia pollen. The present study aimed to express and purify Pla a 1, and to prepare its monoclonal antibody. In the present study, the Pla a 1 gene was subcloned into a pET‑28a vector and transformed into the ArcticExpress™ (DE3) RP Escherichia coli host strain. The purified Pla a 1 was then used to immunize BALB/c mice. When serum detection was positive, spleen cells were isolated from the mice and fused with SP2/0 myeloma cells at a ratio of 10:1. Hybridoma cells were screened by indirect ELISA and limiting dilution. Positive cells were used to induce the formation of antibody‑containing ascites fluid, and the antibodies were purified using protein A‑agarose. The results of the present study demonstrated that recombinant Pla a 1 was successfully expressed and purified, and exhibited positive immunoglobulin E‑binding to serum from patients allergic to P. acerifolia. A total of 11 hybridomas that steadily secreted anti‑Pla a 1 antibody were obtained and an immunoblotting analysis indicated that all of these monoclonal antibodies specifically recognized the Pla a 1 protein. These results suggested that specific anti‑Pla a 1 antibodies may be obtained, which can be used for the rapid detection of Pla a 1 allergens and in the preparation of vaccines against P. acerifolia pollen.

Expression, purification and epitope analysis of Pla a 3 allergen from Platanus acerifolia pollen

Platanus acerifolia (P. acerifolia) is an important cause of pollinosis in cities. The use of allergen extracts on patients with allergic diseases is the most commonly applied method to attempt to treat pollinosis. Pla a 3, a non‑specific lipid transfer protein, is a major allergen present in P. acerifolia pollen extracts. In the present study, the Pla a 3 gene was sub‑cloned into a pSUMO‑Mut vector using Stu I and Xho I sites and transformed into the Arctic Express™ (DE3) RP E. coli host strain. The purified Pla a 3 allergen was analyzed by western blotting and the results revealed that the Pla a 3 allergen has the ability to bind IgE in the P. acerifolia pollen of allergic patients' sera. Moreover, the authors predicted the potential B cell epitopes of the Pla a 3 allergen using the DNAStar Protean system, the Bioinformatics Predicted Antigenic Peptides system and the BepiPred 1.0 server. In addition, the T cell epitopes were predicted by the SYFPEITHI database and the NetMHCII‑2.2 server. As a result, two B cell epitopes (35‑45 and 81‑86) and four potential T cell epitopes including 2‑15, 45‑50, 55‑61 and 67‑73 were predicted in the present study. The current results can be used to contribute to allergen immunotherapies and useful in peptide‑based vaccine designs of pollen allergy.

Detoxification strategies and regulation of oxygen production and flowering of Platanus acerifolia under lead (Pb) stress by transcriptome analysis

Toxic metal pollution is a major environmental problem that has received wide attention. Platanus acerifolia (London plane tree) is an important greening tree species that can adapt to environmental pollution. The genetic basis and molecular mechanisms associated with the ability of P. acerifolia to respond lead (Pb) stress have not been reported so far. In this study, 16,246 unigenes differentially expressed unigenes that were obtained from P. acerifolia under Pb stress using next-generation sequencing. Essential pathways such as photosynthesis, and gibberellins and glutathione metabolism were enriched among the differentially expressed unigenes. Furthermore, many important unigenes, including antioxidant enzymes, plants chelate compounds, and metal transporters involved in defense and detoxification mechanisms, were differentially expressed in response to Pb stress. The unigenes encoding the oxygen-evolving enhancer Psb and OEE protein families were downregulated in Pb-stressed plants, implying that oxygen production might decrease in plants under Pb stress. The relationship between gibberellin and P. acerifolia flowering is also discussed. The information and new insights obtained in this study will contribute to further investigations into the molecular regulation mechanisms of Pb accumulation and tolerance in greening tree species.

Airborne pollen levels and drug consumption for seasonal allergic rhinoconjunctivitis: a 10-year study in France

BACKGROUND

Few time-series studies, and none lasting longer than 4 years, have investigated the etiology of treated seasonal allergic rhinoconjunctivitis (SAR) on the basis of anti-allergic medication prescriptions. The aim of this article was to study the short-term relationship between pollen exposure and drug-treated SAR over 10 years in an urban area in central France.

METHODS

A SAR case was defined as the association between an oral antihistamine and a local anti-allergic drug on the same prescription. The relationship between daily changes in pollen concentrations and daily changes in the number of treated SAR cases was analysed using generalized additive models, taking into account confounding factors such as air pollution, weather and days of the week.

RESULTS

Between 2003 and 2012, the total yearly number of treated SAR cases rose from 7265 to 11 315. The relative risk of treated SAR associated with an interquartile increase in pollen concentration increased significantly for Fraxinus, Betula, Carpinus, Platanus, Poaceae and Urticaceae for the whole pollen season, and for Urticaceae in the first semester.

CONCLUSIONS

The prevalence of treated SAR cases rose by about 55% in 10 years. The study not only confirmed the highly allergenic role of Fraxinus, Betula and Poaceae pollens but also showed a relatively unknown association between treated SAR and Carpinus and Platanus pollens, despite their pollen counts being <1% of overall pollen concentration. It also showed robust correlations with Urticaceae pollens, especially during the first semester, suggesting a potential allergenic role of Parietaria pollination in this non-Mediterranean area.

Pla a_1 aeroallergen immunodetection related to the airborne Platanus pollen content

Platanus hispanica pollen is considered an important source of aeroallergens in many Southern European cities. This tree is frequently used in urban green spaces as ornamental specie. The flowering period is greatly influenced by the meteorological conditions, which directly affect its allergenic load in the atmosphere. The purpose of this study is to develop equations to predict the Platanus allergy risk periods as a function of the airborne pollen, the allergen concentration and the main meteorological parameters. The study was conducted by means two volumetric pollen samplers; a Lanzoni VPPS 2000 for the Platanus pollen sampling and a Burkard multivial Cyclone Sampler to collect the aeroallergen particles (Pla a_1). In addiction the Dot-Blot and the Raman spectroscopy methods were used to corroborate the results. The Pla a_1 protein is recorded in the atmosphere after the presence of the Platanus pollen, which extend the Platanus pollen allergy risk periods. The Platanus pollen and the Pla a 1 allergens concentration are associated with statistical significant variations of some meteorological variables: in a positive way with the mean and maximum temperature whereas the sign of the correlation coefficient is negative with the relative humidity. The lineal regression equation elaborated in order to forecast the Platanus pollen content in the air explain the 64.5% of variance of the pollen presence in the environment, whereas the lineal regression equation elaborated in order to forecast the aeroallergen a 54.1% of the Pla a_1 presence variance. The combination of pollen count and the allergen quantification must be assessed in the epidemiologic study of allergic respiratory diseases to prevent the allergy risk periods.

Isolation and functional analyses of a putative floral homeotic C-function gene in a basal eudicot London plane tree (Platanus acerifolia)

The identification of mutants in model plant species has led to the isolation of the floral homeotic function genes that play crucial roles in flower organ specification. However, floral homeotic C-function genes are rarely studied in basal eudicots. Here, we report the isolation and characterization of the AGAMOUS (AG) orthologous gene (PaAG) from a basal eudicot London plane tree (Platanus acerifolia Willd). Phylogenetic analysis showed that PaAG belongs to the C- clade AG group of genes. PaAG was found to be expressed predominantly in the later developmental stages of male and female inflorescences. Ectopic expression of PaAG-1 in tobacco (Nicotiana tabacum) resulted in morphological alterations of the outer two flower whorls, as well as some defects in vegetative growth. Scanning electron micrographs (SEMs) confirmed homeotic sepal-to-carpel transformation in the transgenic plants. Protein interaction assays in yeast cells indicated that PaAG could interact directly with PaAP3 (a B-class MADS-box protein in P. acerifolia), and also PaSEP1 and PaSEP3 (E-class MADS-box proteins in P. acerifolia). This study performed the functional analysis of AG orthologous genes outside core eudicots and monocots. Our findings demonstrate a conserved functional role of AG homolog in London plane tree, which also represent a contribution towards understanding the molecular mechanisms of flower development in this monoecious tree species.

Isolation and expression analysis of a LEAFY/FLORICAULA homolog and its promoter from London plane (Platanus acerifolia Willd.)

The LEAFY/FLORICAULA (LFY/FLO) homologous genes are necessary for normal flower development in diverse angiosperm species. To understand the genetic and molecular mechanisms underlying floral initiation and development in Platanaceae, an early divergent eudicot family consisting of large monoecious trees, we isolated a homolog of LFY/FLO, PlacLFY, and its promoter from London plane (Platanus acerifolia). PlacLFY is 1,419 bp in length, with an ORF of 1,122 bp encoding a predicted polypeptide of 374 amino acids and 5'/3'-UTR of 54 and 213 bp, respectively. The putative PlacLFY protein showed a high degree of identity (56-84 %) with LFY/FLO homologs from other species, including two highly conserved regions, the N and C domains, and a less conserved amino-terminal proline-rich region. Real-time PCR analysis showed that PlacLFY was expressed mainly in male inflorescences from May of the first year to March of next year, with the highest expression level in December, and in female inflorescences from June to April of next year. PlacLFY mRNA was also detected strongly in subpetiolar buds of December from 4-year-old and adult trees, and slightly in stem of young seedling and young leaf of adult plant. Additionally, we cloned 1,138 bp promoter sequence of PlacLFY and we drove GUS expression in transgenic tobacco by the chimerical pPlacLFY::GUS construction. Histological GUS staining analysis indicated that PlacLFY promoter can drive GUS gene expression in shoot apex, stem, young leaf and petiole, flower stalk, petal tip, and young/semi-mature fruits of transgenic tobacco, which is almost identical to the expression pattern of PlacLFY in London plane. The results revealed that the PlacLFY gene isolated from London plane is expressed not only in reproductive organ but also in vegetative organs. Moreover, this expression pattern is consistent with the expression pattern in tobacco of a GUS reporter gene under the control of the potential promoter region of PlacLFY.

London Plane Tree bioaerosol exposure and allergic sensitization in Sydney, Australia

BACKGROUND

Exposure to London Plane Tree (Platanus) bioaerosols in Sydney, Australia has been anecdotally linked to respiratory irritation, rhinitis, and conjunctivitis.

OBJECTIVE

To determine the relationships between Platanus bioaerosol exposure, allergic sensitization, and symptoms.

METHODS

Sixty-four subjects with self-reported Platanus symptoms were recruited from inner-urban Sydney. Allergic sensitization was determined by skin prick test (SPT) to 13 allergens. Airborne concentrations of Platanus pollen, trichomes, and achene fibers, and other pollen and fungal spores, were measured over the spring and summer of 2006-2007. Subjects' allergic symptoms were monitored concurrently. The Halogen immunoassay (HIA) was used to measure subjects' immunoglobulin E (IgE) reactivity to collected bioaerosols.

RESULTS

Platanus pollen constituted 76% of total pollen between July 2006 and April 2007. Airborne concentrations of Platanus pollen peaked from August until October. Non-Platanus pollen peaked from July to December. Elevated concentrations of trichomes and achene fibers occurred from September to December and August to October, respectively. As determined by SPT, 85.9% of subjects were sensitized, 65.6% to any pollen tested, 56.3% to Lolium perenne, and 23.4% to Platanus. Higher mean daily symptom scores were only associated with high counts of non-Platanus pollens. HIA analysis demonstrated IgE binding to Platanus pollen in all Platanus sensitized subjects. Personal nasal air sampling detected airborne trichomes that were capable of being inhaled. Platanus trichomes or achene fibers did not bind IgE from any subject.

CONCLUSIONS

Platanus bioaerosols exist in high concentrations between August and November in inner-urban Sydney but were not associated with seasonal symptoms. Platanus trichomes are inhaled and may constitute a respiratory irritant.

TRIAL REGISTRATION

Clinicaltrials.gov Identifier: NCTXXXXX.

The FLOWERING LOCUS T orthologous gene of Platanus acerifolia is expressed as alternatively spliced forms with distinct spatial and temporal patterns

The FLOWERING LOCUS T (FT) protein is a likely component of the 'florigen' signal that plays a crucial role in regulating the transition from vegetative to reproductive growth. Here, we report the isolation of full-length cDNAs and the corresponding genomic clones encoding orthologous FT proteins (PaFT) of London plane (Platanus acerifolia Willd). Two genes with high sequence identity were isolated (PaFT1-2), but 34 different transcript products were identified, comprising 21 splice forms produced by alternative splicing of the PaFT pre-mRNAs. Expression of the alternative splicing forms of PaFT varied according to tissue type and developmental stage. PaFT transcripts were detected throughout adult trees, whereas in juvenile trees they were only detected in dormant sub-petiolar buds. In adult trees, levels of the various alternative splicing PaFT forms were related to flower development stage and tree dormancy. Ectopic expression of the archetypal splice form of PaFT-A in tobacco and Arabidopsis developed multiple altered phenotypes, notably early flowering and attenuation of apical dominance. The evidence in this study indicates that complex alternative processing of PaFT transcripts in P. acerifolia may be associated with multiple regulatory roles, including initiation of flowering, flower development, apical dominance, tree dormancy and dormancy release.

Airborne pollen of ornamental tree species in the NW of Spain

This study analyzed airborne pollen counts for the tree taxa most widely used for ornamental purposes in the northwestern Iberian Peninsula (Platanus, Cupressaceae, Olea, Myrtaceae, Cedrus, and Casuarina) at four sites (Vigo, Ourense, Santiago, and Lugo), using aerobiological data recorded over a long period (1993-2007). The abundance and the temporal and spatial distribution of these pollen types were analyzed, and the influence of weather-related factors on airborne pollen counts was assessed. Platanus (in Ourense) and Olea (in Vigo) were the taxa contributing most to pollen counts. In general terms, the results may be taken as indicators of potential risk for pollen-allergy sufferers and therefore used in planning future green areas.

Identification of cyclophilin as a novel allergen from Platanus orientalis pollens by mass spectrometry

Oriental plane trees are an important source of airborne allergens in cities of southwest Asia. In spite of extensive studies on Platanus acerifolia allergy, there are no reports on the molecular characterization of pollen allergens from Platanus orientalis trees. In this study, a newly recognized member of cyclophilin family with a molecular weight of 18 kDa was identified as being partly responsible for IgE reactivity of P. orientalis pollen extract.

Meteorological factors, aeroallergens and asthma-related visits in Kuwait: a 12-month retrospective study

BACKGROUND

The increasing prevalence of asthma in many countries has been related to weather factors and aeroallergen concentrations, but this has not been studied in Kuwait. We evaluated the effect of meteorological factors and the occurrence of aerobiologicals on the number of asthma cases in Kuwait.

METHODS

The number of daily asthma visits to the allergy center and emergency department at Al-Sabha Hospital for 1 year were examined on a monthly basis for correlation with major metereological factors (temperature, relative humidity, rain, wind speed and direction). Spore and pollen counts were collected hourly.

RESULTS

A total of 4353 patients received asthma treatment during the year. The highest pollen count was in the month of September with a maximum relative humidity of 47% and no precipitation, but with a high mean temperature of 39.7 degrees C. Pollen counts were higher in the late summer (September) and occurred with a high patient visit to the allergy center. Fungal spore counts were significantly higher in early winter (December). The high fungal spore count seemed related to with high relative humidity and high precipitation with a low mean average temperature of 19.7 degrees C. The increase number of patients with bronchial asthma visiting an emergency clinic during December was significantly associated with high aerial counts for fungal spores (P<.03), and the months of September and October were more significant for pollen.

CONCLUSION

This study indicates that meteorological factors, aeroallergen concentrations and asthma-related visits are interrelated. The results may prove useful in the generation of hypotheses and development of designs for more comprehensive, individual-based epidemiological studies.

Purified allergens vs. complete extract in the diagnosis of plane tree pollen allergy

BACKGROUND

Plane tree pollen allergy is a clinical disorder affecting human population in cities of Europe, North America, South Africa, and Australia.

OBJECTIVE

To compare IgE-reactivity of the natural and recombinant forms of two major plane allergens, Pla a 1 and Pla a 2, with the reactivity of Platanus acerifolia pollen extract.

METHODS

Forty-seven patients with P. acerifolia allergy, 15 of them monosensitized, and 24 control subjects were included in the study. Natural Pla a 1 and Pla a 2 were purified by standard chromatographic methods and recombinant proteins were expressed in Escherichia coli. Skin prick test and determination of specific IgE were performed with commercial P. acerifolia extract and natural and recombinant purified allergens.

RESULTS

Pla a 1 and Pla a 2 were responsible for 79% of the IgE-binding capacity against P. acerifolia pollen extract. A high correlation has been found between the IgE response to nPla a 1 (R = 0.80; P < 0.001) or nPla a 2 (R = 0.79; P < 0.001) vs. P. acerifolia extract as well as between natural and recombinant Pla a 1 (R = 0.89; P < 0.001). Skin testing showed no significant differences between extract and nPla a 2, whereas a higher reactivity was found with nPla a 1. In contrast, rPla a 1 revealed markedly reduced sensitivity in comparison with extract by skin prick test and specific IgE. The sensitivity of the mix Pla a 1+Pla a 2 was 100% and 87.5% for monosensitized and polysensitized patients, respectively, with no false-positive reactions detected. Conclusion Pla a 1 and Pla 2 are sufficient for a reliable diagnosis of P. acerifolia in most patients and induce comparable skin test reactivity as a whole extract.

Development of a Sandwich-Type ELISA for Measuring Pla a 1, the Major Allergen of Platanus acerifolia Pollen

BACKGROUND

Platanus acerifolia is an important cause of pollinosis in Western European cities. Pla a 1, a nonglycosylated 18-kDa protein with a prevalence of 80%, is a major allergen in P. acerifolia pollen extracts. Our aim was to develop a Pla a 1-specific ELISA to quantify this protein in allergenic extracts and preparations for clinical use.

METHODS

Pla a 1 was purified by cation exchange at pH 7.0, gel filtration, and anion exchange chromatography at pH 10.0. Monoclonal (mAb) and polyclonal antibodies were obtained by immunizing mice and rabbits with nPla a 1. One (5C1) of the 13 mAb obtained was used as capture antibody at 5 mug/ml and biotin-labeled specific polyclonal antiserum at 0.63 microg/ml served for detection.

RESULTS

The prevalence of Pla a 1-specific IgE to purified Pla a 1 among 47 P. acerifolia-allergic patients was 79%. The Pla a 1-ELISA developed has a linear range of 3-25 ng/ml, high sensitivity with a detection limit of 0.5 ng/ml and is highly specific as none of the 24 pollen, mite, mold, and plant food extracts tested gave positive results. The assay could quantify Pla a 1-like proteins in other planetree pollen extracts. A good correlation was obtained between Pla a 1 content of 11 P. acerifolia pollen extracts (average content 0.69% of the total protein) and their IgE-binding activity.

CONCLUSIONS

The described two-site sandwich ELISA to measure Pla a 1 is useful for standardization of planetree pollen extracts intended for clinical use.

Key pollen allergens in North America

OBJECTIVE

To discuss major pollen aeroallergens in North America that are essential for effective immunotherapy and to propose a list of pollen aeroallergens that could be prioritized for allergen standardization.

DATA SOURCES

PubMed was used to search the existing medical literature. No date restrictions were used. Keywords included allergy, aeroallergen, taxonomy, cross-reactivity, pollen, and specific genus and species names.

RESULTS

Tree species possess relatively unique allergens, and representative members should be chosen at the genus or family level. In the Composite family, there is significant cross-reactivity between ragweed species within the Ambrosia genus. Selection of one species should be sufficient for skin testing and immunotherapy. Extensive allergenic cross-reactivity exists among grasses. Selection of timothy grass alone or in combination with a single northern grass species provides adequate coverage in the northeastern regions of North America.

CONCLUSIONS

One of the goals within the field of allergy should be to identify high-priority targets for future development of standardized commercial extracts. The standardization of increasing numbers of allergen extracts potentially benefits the discipline of allergy by facilitating transfer of care among physician practices, improving uniformity of patient care, and providing a template on which geographically specific extract choices can be built.

The major Platanus acerifolia pollen allergen Pla a 1 has sequence homology to invertase inhibitors

BACKGROUND

Sycamores or plane trees are an important source of airborne allergens in many cities of the United States and Western Europe. Pla a 1 has been described as a major allergen from Platanus acerifolia (London plane tree).

OBJECTIVE

To clone and characterize the cDNA for Pla a 1 and to express the recombinant protein.

METHODS

Pla a 1 was isolated by cationic exchange, gel filtration, and reverse-phase chromato-graphies. Pla a 1 cDNA was cloned by reverse transcription followed by polymerase chain reaction, using amino acid sequences from tryptic peptides of the allergen. The Pla a 1 encoding sequence has been subcloned into the pKN172 expression vector and expressed in Escherichia coli as a non-fusion protein. Purified recombinant protein has been tested for its IgE-binding capacity in immunoblot, immunoblot inhibition, and ELISA.

RESULTS

Pla a 1 reacted with serum IgE from 35 of the 42 (83.3%) Platanus-allergic patients studied and represented 60% of the total IgE-binding capacity of the P. acerifolia pollen extract. The allergen displayed 43% sequence identity to a grape invertase inhibitor and showed a predicted secondary structure characteristic of all-alpha proteins. Serological analysis revealed that both natural and recombinant forms of Pla a 1 displayed similar IgE-binding capacity.

CONCLUSIONS

Pla a 1 belongs to a new class of allergens related to proteinaceous invertase inhibitors. Recombinant Pla a 1 binds IgE in vitro like its natural counterpart and, therefore, it can be useful for specific diagnosis and structural studies.

Adventitious shoot regeneration from in vitro cultured leaves of London plane tree (Platanus acerifolia Willd.)

Adventitious shoots were successfully regenerated from leaf explants of in vitro cultures of Platanus acerifolia Willd. The leaves of three clones (genotypes), designated as PH1, PH2 and PC, respectively, were wounded by three to four transverse cuts through the midvein and cultured on 26 media based on Murashige and Skoog (MS) basal medium, containing different concentrations of 6-benzylaminopurine (BAP) in combination with different concentrations of indole-3-butyric acid (IBA). The highest regeneration rate (>90%) and the largest number of shoot clumps per regenerating leaf (>4 shoot clumps/explant) were obtained with leaves of genotype PH2 cultured on MS basal medium supplemented with 17.76 microM BAP and 4.92 microM IBA. The other two genotypes, PH1 and PC, showed very low capability of shoot regeneration (<10%) on all the media tested. Shoots on leaf explants originated mainly from callus that developed around the cut end of petioles and along the cuts across the midvein. The regenerated shoots were micropropagated, rooted and transplanted to the soil successfully.

Pollen allergy related to the area of residence in the city of Córdoba, south-west Spain

The aim of this study was to analyse the relationship between the distribution of hay-fever patients in the city of Córdoba, south-western Iberian Peninsula, and the specific atmospheric biological content originating from local sources. Four different districts were established in the metropolitan area of the city, according to vegetational and urbanistic characteristics. Air samples were taken in each area using portable Hirst-type samplers (Lanzoni VPPS 1000) and the spectrum of biological content was defined. Patients attending the Allergy Unit at Córdoba Teaching Hospital in 2000 with allergic rhinitis and/or asthma, and displaying a positive reaction to aeroallergen extracts, were distributed within the areas as a function of their district of residence. Aerobiological results revealed differences in pollen content between areas, in terms of both quantity and number of pollen types recorded. These differences were largely due to proximity to rural areas, prevalence of pollen from typically urban species and the possible effect of urban architecture as a barrier to the dispersal/ concentration of particles and other pollutants. Patients were not uniformly distributed within the city. The majority lived in districts in which pollen from rural species was mixed with pollen from ornamentals. Patients living in typically urban districts displayed a higher prevalence of allergy to pollen from ornamentals. It is concluded that a high degree of exposure to the same environment may influence the development of sensitisation to the particular pollen load associated with that area.

Purification and characterization of Pla a 1, a major allergen from Platanus acerifolia pollen

BACKGROUND

Plane trees, as Platanus acerifolia, are an important source of airborne allergens in cities of the United States and Western Europe. Little is known about the relevant allergens of this pollen. The aim of this study was to identify relevant allergens from P. acerifolia pollen and purify and characterize a major allergen of 18 kDa.

METHODS

P. acerifolia pollen extract was fractionated using ion exchange, gel filtration, and reverse-phase chromatography. Analyzes were carried out by EAST, SDS-PAGE, isoelectric focusing, immunoblotting and amino-acid sequencing.

RESULTS

An 18-kDa protein from the P. acerifolia pollen extract, which we named Pla a 1, was purified. This nonglycosylated protein had an isoelectric point value higher than 9.3 and was recognized by up to 92% of monosensitized Platanus allergic patients and 83% of polyzensitized patients. Sequencing of its N-terminal yielded an amino acid sequence which showed no homology to the known proteins in the databases. Other relevant allergens detected in monosensitized patients were proteins of 43 and 52 kDa, with immunoglobulin (Ig)E-binding prevalences of 83 and 42%, respectively. Profilin was an important allergen in polyzensitized patients.

CONCLUSIONS

The most relevant allergens from the P. acerifolia pollen have been determined. A major allergen, specific of this pollen, and named Pla a 1, has been purified and characterized.

Pollen-related allergy in Europe

The increasing mobility of Europeans for business and leisure has led to a need for reliable information about exposure to seasonal airborne allergens during travel abroad. Over the last 10 years or so, aeropalynologic and allergologic studies have progressed to meet this need, and extensive international networks now provide regular pollen and hay-fever forecasts. Europe is a geographically complex continent with a widely diverse climate and a wide spectrum of vegetation. Consequently, pollen calendars differ from one area to another; however, on the whole, pollination starts in spring and ends in autumn. Grass pollen is by far the most frequent cause of pollinosis in Europe. In northern Europe, pollen from species of the family Betulaceae is a major cause of the disorder. In contrast, the mild winters and dry summers of Mediterranean areas favor the production of pollen types that are rarely found in central and northern areas of the continent (e.g., the genera Parietaria, Olea, and Cupressus). Clinical and aerobiologic studies show that the pollen map of Europe is changing also as a result of cultural factors (e.g., importation of plants for urban parklands) and greater international travel (e.g., the expansion of the ragweed genus Ambrosia in France, northern Italy, Austria, and Hungary). Studies on allergen-carrying paucimicronic or submicronic airborne particles, which penetrate deep into the lung, are having a relevant impact on our understanding of pollinosis and its distribution throughout Europe.

Climate and aeroallergen levels in asthma: a 12 month prospective study

BACKGROUND

There is evidence to suggest that changes in weather and airborne fungal spore and pollen counts may affect asthma symptoms.

METHODS

The relationship between climate, airborne fungal spore, and pollen counts and peak expiratory flow rate (PEFR) and asthma symptoms was prospectively investigated in a population of mild to moderate asthmatic subjects in Blenheim, New Zealand. Subjects recorded twice daily PEFR measurements and asthma symptom scores for up to one year. Spore and pollen counts were measured two hourly and meteorological data were measured hourly. Individual, within person, multiple linear regression analyses were conducted, adjusting for auto-correlation. A random effects model was assumed for the individual regression co-efficients and weighted estimates of the mean of these coefficients were obtained by the method of maximum likelihood.

RESULTS

One hundred and thirty nine asthmatic patients (60% atopic) aged 17-80 years completed the study. Of the weather variables, only temperature showed a small but consistent association with PEFR. The mean rise in PEFR for an 8.8 degrees C (2 SD) change in temperature was 0.78% (95% CI 0.44% to 1.11%), approximately 3.0 l/min. There was a weak association between days of high basidiospore counts and increased nocturnal wakening and reliever medication use. Pollen counts showed no consistent association with either PEFR or asthma symptoms.

CONCLUSIONS

The results of this study suggest that the effects of weather and aeroallergens on PEFR and asthma symptoms in this population are small, and that other causes need to be sought to account for variations in asthma severity and exacerbations.