Abstract
The weed wall pellitory, Parietaria judaica, is one the most important pollen allergen sources in the Mediterranean area causing severe symptoms of hay fever and asthma in allergic patients. We report the expression of the major Parietaria allergens, Par j 1 and Par j 2 which belong to the family of lipid transfer proteins, in insect cells. According to circular dichroism analysis and gel filtration, the purified allergens represented folded and monomeric proteins. Insect cell-expressed, folded Par j 2 exhibited higher IgE binding capacity and more than 100-fold higher allergenic activity than unfolded Escherichia coli-expressed Par j 2 as demonstrated by IgE ELISA and basophil activation testing. IgE ELISA inhibition assays showed that Par j 1 and Par j 2, contain genuine and cross-reactive IgE epitopes. IgG antibodies induced by immunization with Par j 2 inhibited binding of allergic patients IgE to Par j 1 only partially. IgE inhibition experiments demonstrated that insect cell-expressed Par j 1 and Par j 2 together resembled the majority of allergenic epitopes of the Parietaria allergome and therefore both should be used for molecular diagnosis and the design of vaccines for allergen-specific immunotherapy of Parietaria allergy.
Highlights
The weed wall pellitory, Parietaria judaica, is one the most important pollen allergen sources in the Mediterranean area causing severe symptoms of hay fever and asthma in allergic patients
Par j 2 and Par j 1, showed a relatively low sequence identity of less than 35% with the other plant lipid transfer proteins (LTP) allergens whereas sequence identities of up to >90% (e.g., Pru p 1 vs. Pru ar 3) between certain LTPs, mainly from somatic tissues were found (Supplementary Fig. S1a, colors)
The phylogenetical comparison analysis of the LTPs shows that Par j 1 and Par j 2 represent an independent branch highlighting the evolutionary differences with other proteins of this family as represented in Supplementary Fig. S1b
Summary
The weed wall pellitory, Parietaria judaica, is one the most important pollen allergen sources in the Mediterranean area causing severe symptoms of hay fever and asthma in allergic patients. IgE inhibition experiments demonstrated that insect cell-expressed Par j 1 and Par j 2 together resembled the majority of allergenic epitopes of the Parietaria allergome and both should be used for molecular diagnosis and the design of vaccines for allergen-specific immunotherapy of Parietaria allergy. Score important advantages over conventional allergen-extract-based diagnosis because it allows revealing the allergic patients molecular sensitization pattern and aids in the diagnostic resolution of difficult cases and in the refined prescription of allergen-specific immunotherapy[21,22,23], the only causal and disease-modifying treatment for IgE-associated allergies[24]. We studied the extent of IgE cross-reactivity of rPar j 1 and rPar j 2 by IgE inhibition studies and demonstrated that only both allergens together resemble the spectrum of IgE epitopes of natural Parietaria pollen extract
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