Cloning and expression of Che a 1, the major allergen of Chenopodium album in Escherichia coli. Appl Biochem Biotechnol. 2011;163:895-905. [PMID: 20872185 DOI: 10.1007/s12010-010-9093-y]

Allergenicity of recombinant Humulus japonicus pollen allergen 1 after combined exposure to ozone and nitrogen dioxide

Ozone (O₃) and nitrogen dioxide (NO₂) are thought to play primary roles in aggravating air pollution-induced health problems. However, the effects of joint O₃/NO₂ on the allergenicity of pollen allergens are unclear. Humulus japonicus pollen allergen 1 (Hum j1) is a profilin protein that causes widespread pollinosis in eastern Asia. In order to study the effects of combined O₃/NO₂ on the allergenicity of Hum j1, tandem six-histidine peptide tag (His6)-fused recombinant Hum j1 (rHum j1) was expressed in a prokaryotic system and purified through His6 affinity chromatography. The purified rHum j1 was used to immunize SD rats. Rat sera with high titers of IgG and IgE antibodies against rHum j1 were used for allergenicity quantification. The rHum j1 was exposed to O₃/NO₂, and changes in allergenicity of the exposed rHum j1 were assayed using the immunized rat antibodies. Tandem LC-MS/LC (liquid chromatography-mass spectrometer/liquid chromatography spectrometer) chromatography and UV and circular dichroism (CD) spectroscopy were used to study the structural changes in rHum j1. Our data demonstrated that a novel disulfide bond between the sulfhydryl groups of two neighboring cysteine molecules was formed after the rHum j1 exposure to joint O₃/NO₂, and therefore IgE-binding affinity was increased and the allergenicity was reinforced. Our results provided clues to elucidate the mechanism behind air pollution-induced increase in pollinosis prevalence.

Expression of grape class IV chitinase in Spodoptera frugiperda (Sf9) insect cells

INTRODUCTION

Most of pathogenesis related (PR) proteins possess complicated structures; hence their active recombinant forms are usually produced in eukaryotic systems. In this study, we employed an insect cell line to express a recombinant form of a previously identified grape PR3 allergen categorised as class IV chitinase.

METHODS

Grape chitinase cDNA was amplified by RT-PCR and inserted into pFastBacHTA using restriction enzymes. The recombinant pFastBacHTA was applied for the transformation of Escherichia coli DH10Bac cells. The purified recombinant bacmid was used for transfection of Sf9 cells. Finally, the IgE-immunoreactivity of purified recombinant protein was evaluated using grape allergic patient's sera. Moreover, polyclonal anti-6His-tag and monoclonal anti-chitinase antibodies were used for further assessment of recombinant protein.

RESULTS

SDS-PAGE analysis of the transfected Sf9 cells showed expression of a monomeric 25kDa and a dimeric 50 kDa recombinant protein. Western blotting revealed considerable IgE reactivity of the recombinant protein with grape allergic patients' sera. Furthermore, confirmatory assays showed specific reactivity of the recombinant protein with anti-His tag and anti-chitinase antibodies.

CONCLUSION

This study showed that, in contrast to E. coli, insect cells are suitable hosts for the production of a soluble and IgE-reactive recombinant form of grape class IV chitinase. This recombinant allergen could be used for component resolved diagnosis of grape allergy or other immunodiagnostic purposes.

Molecular biomarkers for grass pollen immunotherapy

Grass pollen allergy represents a significant cause of allergic morbidity worldwide. Component-resolved diagnosis biomarkers are increasingly used in allergy practice in order to evaluate the sensitization to grass pollen allergens, allowing the clinician to confirm genuine sensitization to the corresponding allergen plant sources and supporting an accurate prescription of allergy immunotherapy (AIT), an important approach in many regions of the world with great plant biodiversity and/or where pollen seasons may overlap. The search for candidate predictive biomarkers for grass pollen immunotherapy (tolerogenic dendritic cells and regulatory T cells biomarkers, serum blocking antibodies biomarkers, especially functional ones, immune activation and immune tolerance soluble biomarkers and apoptosis biomarkers) opens new opportunities for the early detection of clinical responders for AIT, for the follow-up of these patients and for the development of new allergy vaccines.

Allergens of weed pollen: an overview on recombinant and natural molecules

Weeds represent a botanically unrelated group of plants that usually lack commercial or aesthetical value. Pollen of allergenic weeds are able to trigger type I reactions in allergic patients and can be found in the plant families of Asteraceae, Amaranthaceae, Plantaginaceae, Urticaceae, and Euphorbiaceae. To date, 34 weed pollen allergens are listed in the IUIS allergen nomenclature database, which were physicochemically and immunologically characterized to varying degrees. Relevant allergens of weeds belong to the pectate lyase family, defensin-like family, Ole e 1-like family, non-specific lipid transfer protein 1 family and the pan-allergens profilin and polcalcins. This review provides an overview on weed pollen allergens primarily focusing on the molecular level. In particular, the characteristics and properties of purified recombinant allergens and hypoallergenic derivatives are described and their potential use in diagnosis and therapy of weed pollen allergy is discussed.

Diagnosis of Chenopodium album allergy with a cocktail of recombinant allergens as a tool for component-resolved diagnosis

Chenopodium album pollen is one of the main sources of pollen allergy in desert and semi-desert areas and contains three identified allergens, so the aim of this study is comparison of the diagnostic potential of C. album recombinant allergens in an allergenic cocktail and C. album pollen extract. Diagnostic potential of the allergenic cocktail was investigated in 32 individuals using skin prick test and obtained results were compared with the acquired results from C. album pollen extract. Specific IgE reactivity against the pollen extract and allergenic cocktail was determined by ELISA and western blotting tests. Inhibition assays were performed for the allergenic cocktail characterization. The exact sensitization profile of all patients was identified which showed that 72, 81 and 46% of allergic patients had IgE reactivity to rChe a 1, rChe a 2 and rChe a 3, respectively. Almost all of C. album allergic patients (30/32) had specific IgE against the allergenic cocktail. In addition, there was a high correlation between IgE levels against the allergenic cocktail and IgE levels against the pollen extract. The allergenic cocktail was able to completely inhibit IgE binding to natural Che a 1, Che a 2 and Che a 3 in C. album extract. In addition, positive skin test reactions were seen in allergic patients that tested by the allergenic cocktail. The reliable results obtained from this study confirmed that the allergenic cocktail with high diagnostic potential could be replaced with natural C. album allergen extracts in skin prick test and serologic tests.