Generation of oral vaccine for mite allergy

在本研究中，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。我们发现了新的尘螨抗原，包括16组主要过敏原Der f16 （gelsolin家族），17组过敏原Der f17 （EF-hand calcium binding过敏原）和一个新的过敏原Mag133 （UK114家族成员）。当考虑将这些新的过敏原应用于口服疫苗时，它们具有相当有趣的特性。我们发现钙与Der f17的结合对其IgE结合活性至关重要，而缺乏钙结合的Der f17突变体会损害IgE反应活性。这些结果表明，Der f17突变体可用于产生“低过敏性疫苗”，该疫苗可诱导T细胞应答而无过敏副作用。关于Mag133，我们发现该过敏原除了具有高IgE结合特性外，还具有Th2偏斜的效力，这意味着Mag133可能在螨虫过敏患者中常见的偏斜Th2反应中发挥作用。我们还分析了Th1/Th2细胞因子产生对Der f14的反应，Der f14是另一种重要的主要过敏原，也具有强效的T细胞刺激活性。我们发现对Der f14片段有不同的Th1/Th2细胞因子分泌；Der f14 n端片段触发排他的Th2反应，而内部的ma3片段则相反诱导th1主导的反应。这种由Der f14片段调控的细胞因子差异可能有助于T细胞靶向疫苗的设计，从而改善致病性Th2反应。特别是，Mag 3可能对th1诱导疫苗有效。通过与Th1佐剂结合，可以很容易地将n端片段改造成Th1诱导疫苗。综上所述，我们认为本项目获得的结果应该为下一代抗螨过敏口服疫苗的产生提供见解。

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.