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变应原的免疫化学性质。我们鉴定了新的尘螨抗原，包括第16组主要变应原Der f 16(明胶蛋白家族)、17组变应原Der f 17(EF-手钙结合变应原)和一种新变应原Mag133(UK114家族成员)。这些新变应原在口服疫苗中的应用具有非常有趣的特征。我们发现与Der f 17的钙结合是其IgE结合活性的关键，而缺乏钙结合的Der f 17突变体降低了IgE的反应性。关于Mag133，我们发现该变应原除了具有高的IgE结合活性外，还具有Th2偏斜的能力，暗示Mag133可能在尘螨过敏患者常见的Th2偏斜的应答中发挥作用。我们还分析了Th1/Th2细胞因子对另一种重要的主要变应原Der f 14的反应，该变应原也具有很强的T细胞刺激活性。我们发现Der f 14片段刺激Th1/Th2细胞因子的分泌存在差异，Der f 14 N端片段触发排他性Th2应答，而内部MAG 3片段则相反地诱导Th1占优势的应答。Der f 14片段的这种不同的细胞因子调节可能有助于T细胞靶向疫苗的设计，从而可以改善致病性Th2反应。尤其是MAG3对Th1诱导疫苗可能是有效的。通过与Th1佐剂的结合，N端片段可以很容易地被设计成Th1诱导疫苗。综上所述，我们相信该项目的结果将为下一代抗螨变应口服疫苗的开发提供借鉴。

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.