Shinji Tsuboi

Toward Elucidating the Full Spectrum of Mite Allergens. State of the Art.

Our research has focused on the molecular design of immunotherapeutic vaccines and the advancement of mite-allergy diagnosis. Here, we describe the research history of the major group 1 and group 2 allergens, immunoelectrophoretic analyses covering the complete spectrum of mite allergens, our results on allergens with distinctive characteristics (a conjunctival congestion-eliciting antigen [LM2], an immunotherapeutic antigen [HM2] with high efficacy and without definite adverse reactions, and a potent T-cell stimulatory antigen [HM1] with secretion of IFN-gamma), the full spectrum and immunochemical properties of the major and other important mite allergens (including our newly described allergens: a pan-allergen [tropomyosin, group 10], a potent T-cell stimulatory allergen [M-177, apolipophorin, group 14] and its peptide fragments Mag1 and Mag3, a moderate IgE-binding allergen [gelsolin/villin, group 16], an EF-hand Ca2+-binding allergen [group 17], and a less IgE-binding allergen [heat shock protein 70]), and prospects for the development of immunotherapeutic and diagnostic agents.

Der f 16: a novel gelsolin-related molecule identified as an allergen from the house dust mite, Dermatophagoides farinae1

Allergen from the house dust mite (Dermatophagoides sp.) is a major trigger factor of allergic disorders, and its characterization is crucial for the development of specific diagnosis or immunotherapy. Here we report the identification of a novel dust mite (Dermatophagoides farinae) antigen whose primary structure belongs to the gelsolin family, a group of actin cytoskeleton‐regulatory proteins. Isolated mite cDNA, termed Der f 16, encodes 480 amino acids comprising a four‐repeated gelsolin‐like segmental structure, which is not seen in conventional gelsolin family members. Enzyme immunoassay indicated that recombinant Der f 16 protein, prepared using an Escherichia coli expression system, bound IgE from mite‐allergic patients at 47% (8/17) frequency. This is the first evidence that the gelsolin family represents a new class of allergen recognizable by atopic patient IgE.

Therapeutic effect and titers of the specific IgE and IgG antibodies in patients with sea squirt Allergy (Hoya asthma) under a long-term hyposensitization with three sea squirt antigens

Hyposensitization therapy with each of three sea squirt antigens, Gi-rep (molecular weight [MW] 106,000), Ei-M (MW 22,800), and DIIIa (MW 9980), have succeeded in 72%, 90%, and 36% of patients with sea squirt allergy, respectively, within the first year, and the effect has been maintained during subsequent 4-year maintenance therapy. All available sera from some of the hyposensitized patients were also examined for IgE and IgG titers against the most effective therapeutic antigen, Ei-M, and it was revealed that the Ei-M-specific IgG titer increased rapidly in the successfully hyposensitized patients, regardless of the therapeutic antigen used, except for a few patients. Furthermore, the high specific IgG titer, as well as the therapeutic effect, was maintained during the subsequent maintenance therapy. No such increase in the specific IgG titer was detected in all unsuccessfully hyposensitized patients. In contrast, the Ei-M-specific IgE titer was practically unchanged in all allergic patients, independent of the therapy. Therefore, the effect of the hyposensitization therapy was closely dependent on the induction of the specific IgG capable of competing with the specific IgE for a certain asthma-inducing antigen, like DIIIa. The apparently low therapeutic efficiency of DIIIa was attributed to its relatively low immunogenicity to induce the specific IgG.

Der f 34, a Novel Major House Dust Mite Allergen Belonging to a Highly Conserved Rid/YjgF/YER057c/UK114 Family of Imine Deaminases

The high prevalence of house dust mite (HDM) allergy is a growing health problem worldwide, and the characterization of clinically important HDM allergens is a prerequisite for the development of diagnostic and therapeutic strategies. Here, we report a novel HDM allergen that belongs structurally to the highly conserved Rid/YjgF/YER057c/UK114 family (Rid family) with imine deaminase activity. Isolated HDM cDNA, named der f 34, encodes 128 amino acids homologous to Rid-like proteins. This new protein belongs to the Rid family and has seven conserved residues involved in enamine/imine deaminase activity. Indeed, we demonstrated that purified Der f 34 had imine deaminase activity that preferentially acted on leucine and methionine. Native Der f 34 showed a high IgE binding frequency as revealed by two-dimensional immunoblotting (62.5%) or ELISA (68%), which was comparable with those of a major HDM allergen Der f 2 (77.5 and 79%, respectively). We also found that Der f 34 showed cross-reactivity with another prominent indoor allergen source, Aspergillus fumigatus. This is the first report showing that the Rid family imine deaminase represents an additional important pan-allergen that is conserved across organisms.