Generation of oral vaccine for mite allergy

在这项研究中，我们试图阐明适用于重组口服疫苗的重要屋尘螨过敏原的免疫化学特性。我们鉴定了新的尘螨抗原，包括第16组主要过敏原Der f 16（凝溶胶蛋白家族）、第17组过敏原Der f 17（EF-手型钙结合过敏原）和一种新的过敏原Mag 133（UK 114家族成员），这些新的过敏原在考虑应用于口服疫苗时具有相当有趣的特性。我们发现，钙结合到Der f 17是至关重要的，其IgE结合活性，和Der f 17突变体，是缺乏钙结合损害IgE反应性。这些结果表明，Der f 17突变体可用于制备“低变应原疫苗”，其可诱导T细胞应答而无过敏性副作用。关于Mag 133，我们发现该变应原除了具有高IgE结合特性外，还具有Th 2-偏斜效力，提示Mag 133可能在螨过敏患者中经常看到的偏斜的Th 2应答中起作用。我们还分析了Th 1/Th 2细胞因子产生对Der f 14的应答，Der f 14是另一种重要的主要过敏原，也具有有效的T细胞刺激活性。我们发现不同的Th 1/Th 2细胞因子分泌响应于Der f 14片段; Der f 14 N端片段触发排他性Th 2反应，而内部Mag 3片段相反诱导Th 1主导的反应。Der f 14片段的这种差异性细胞因子调节可用于可改善致病性Th 2应答的T细胞靶向疫苗设计。特别是Mag 3可能是一种有效的Th 1诱导疫苗。因此，我们认为本研究的结果将为下一代抗螨过敏口服疫苗的研制提供参考。

In this study, we have tried to elucidate the immunochemical properties of important house dust mite allergens applicable for recombinant oral vaccines. We identified novel dust mite antigens including group 16 major allergen Der f 16 (gelsolin family), group 17 allergen Der f 17 (EF-hand calcium binding allergen), and a new allergen Mag133 (UK114 family member).These new allergens have quite intriguing characteristics when considering then application to oral vaccine. We found that calcium binding to Der f 17 is critical for its IgE binding activity, and that the Der f 17 mutant that was deficient for calcium binding impaired IgE reactivity. These results suggest that the Der f 17 mutant is useful for generating "hypoallergenic vaccine", which can induces T cell response without anaphylactic side effect.Regarding Mag133, we found that this allergen had a Th2-skewing potency in addition to its high IgE binding property, implicating that Mag133 might play a role in the skewed Th2 response frequently seen in mite-allergic patients.We also analyzed Th1/Th2 cytokine production response to Der f 14, another important major allergen which also has potent T cell stimulatory activity. We found differential Th1/Th2 cytokine secretion in response to Der f 14 fragments ; Der f 14 N-terminal fragment triggered exclusive Th2 response, whereas internal Mag 3 fragment conversely induced Th1-dominated response. This differential cytokine regulation by Der f 14 fragments could be useful for T cell-targeted vaccine design that can ameliorate pathogenic Th2 response. Especially, Mag 3 might be effective for Th1-inducing vaccine. The N-terminal fragment could easily be engineered to Th1-inducing vaccine by conjugating with Th1 adjuvants.Taken together, we believe that the results obtained by this project should provide insights into the generation of anti-mite allergy oral vaccines for the next generation.