Analysis of major paralogs encoding the Fra a 1 allergen based on their organ-specificity in Fragaria × ananassa.

KEY MESSAGE: Fra a 1 protein in strawberry causes oral allergic syndrome. Over 39 Fra a 1 paralogs have been identified in strawberry genome. Fra a 1.01 is major accumulating protein in edible organs. Strawberry fruits contain allergenic proteins that cause oral allergic syndrome. The hypothesized major allergen is Fra a 1, an ortholog of the birch pollen allergen protein Bet v 1. We organized Fra a 1 genes and analyzed their localizations at the transcriptional and translational levels. In total, 15 new Fra a 1 proteins were identified from the genomic database, increasing the total number of Fra a 1 to 30 proteins encoded by 39 genes. Fra a 1.02 was mostly expressed in receptacles, and Fra a 1.01 in achenes, when analyzed by RNA sequencing. Immunoblotting showed that the Fra a 1.01 protein was broadly accumulated in strawberry organs, while the Fra a 1.02 protein was mostly expressed in receptacles. Recombinant Fra a 1.01 strongly reacted with human IgE. The mRNA and protein expression levels of Fra a 1 did not correlate, indicating the importance of protein levels when evaluating the abundance of allergens in strawberry. Based on the localizations, accumulation levels and reactivity to human IgE, we determined that Fra a 1.01 was the most important allergen, followed by Fra a 1.02, and then other Fra a 1 proteins. The information obtained here will be useful for selecting the target Fra a 1 paralogs when breeding hypoallergenic strawberry.

Contribution of itch-associated scratch behavior to the development of skin lesions in Dermatophagoides farinae-induced dermatitis model in NC/Nga mice.

Recently, we have reported that the pathophysiological features of dermatitis induced by the repeated application with Dermatophagoides farinae (Df) extract ointment in NC/Nga mice were similar to those observed in the patients with atopic dermatitis. In the present study, we first examined whether the application of Df in other mouse strains could induce dermatitis. The repeated application of Df body (Dfb) ointment to the barrier-disrupted back of ICR, C57BL/6, and Balb/c mice did not cause any apparent skin lesions, although transient increase in serum immunoglobulin E (IgE) levels during antigen application was observed. On the other hand, in NC/Nga mice, dermatitis scores and serum IgE levels increased remarkably, and then these changes sustained for at least 10 days after stopping of antigen elicitation. Using NC/Nga mice, we investigated the contribution of scratching behavior to the development and maintenance of Dfb-induced dermatitis. In correlation with the increase in scratching behavior, erythema, hemorrhage, edema, scarring, erosion and excoriation were observed. Cutting off the hind toenails of mice exhibiting chronic skin lesions dramatically alleviated the dermatitis. From these findings, the onset of skin lesions and its chronically sustained course in Dfb-induced dermatitis in NC/Nga mice were closely associated with increased scratching behavior.

A novel atopic dermatitis model induced by topical application with dermatophagoides farinae extract in NC/Nga mice.

BACKGROUND: Atopic dermatitis is a chronically relapsing inflammatory skin disease. Animal models induced by relevant allergens play a very important role in the elucidation of the disease. The patients with atopic dermatitis are highly sensitized with mite allergens such as Dermatophagoides farinae (Df). Therefore, in the present study, we tried to develop a novel model for atopic dermatitis by repeated application with Df extract ointment. METHODS: Df extract ointment was repeatedly applied to the back of NC/Nga mice together with barrier disruption. Atopic dermatitis-like skin lesions were evaluated by dermatitis scores, skin histology and immunological parameters. The effect of corticosteroid and calcineurin inhibitor was also examined. RESULTS: Repeated application of Df extract ointment caused rapid increase in dermatitis scores. Clinical (skin dryness, erythema, edema and erosion) and histological symptoms (dermal and epidermal thickening, hyperkeratosis, parakeratosis and inflammatory cell infiltration) in this model were very similar to those in human atopic dermatitis. Serum total and Df-specific IgE levels were elevated in this model compared with normal mice, and draining lymph node cells isolated from the mice that exhibited dermatitis produced significant amounts of interleukin-5, interleukin-13 and interferon-gamma after re-stimulation with Df. Furthermore, current first-line drugs for the treatment of human atopic dermatitis, corticosteroid and tacrolimus ointments, were effective against the clinical and histological symptoms in this model. CONCLUSIONS: These results suggest that the model we have established is useful for not only elucidating the pathogenesis of atopic dermatitis but also for evaluating therapeutic agents.