Targeting Key Factors Involved in Immune Reactions mediated by Tick Bites to the Carbohydrate alpha-Gal

对红肉的迟发过敏反应取决于半乳糖-α-1，3-半乳糖（α-Gal）的IgE抗体的存在。临床症状是由接触红肉或内脏引发的，但也有明胶或携带治疗抗体的α-Gal。最近，我们可以从猪肾中鉴定出携带α-Gal的蛋白质氨肽酶N和血管紧张素转换酶I，并通过诱导嗜碱性粒细胞活化和α-Gal过敏患者皮肤点刺试验的阳性反应来显示其临床相关性。与针对α-Gal的IgG抗体（其在生命早期通过接触微生物而生理学诱导）相反，目前接受的假设是针对α-Gal的IgE的诱导是由蜱叮咬介导的。这得到了几条证据的支持：Alpha-Gal过敏与世界不同地区Amblyomma，Ixodes和Haemaphysalis物种的蜱叮咬之间的强相关性，蜱叮咬后针对Alpha-Gal的IgE的增强以及在Ixodes ricinus胃肠道中检测到Alpha-Gal。本提案的目的是i）分析携带天然和工程分子的α-gal的变应原性，ii）在健康、致敏和最近暴露的个体中对α-gal表位的免疫应答中涉及的细胞的表型，iii）通过诱导对α-gal的免疫反应来分析α-1，3-半乳糖基转移酶缺陷小鼠中的致敏机制。为此，将在添加和不添加蜱唾液作为天然佐剂的情况下研究通过皮肤模拟蜱叮咬的不同抗原接触途径。识别蜱虫中的IgE反应分子将有助于更好地诊断和风险管理患者。更重要的是，使用Alpha-Gal过敏作为模型疾病，我们的结果将阐明通过皮肤引发免疫反应和对碳水化合物过敏原致敏的基本机制。

Delayed anaphylaxis to red meat is dependent on the presence of IgE-antibodies to galactose-alpha-1,3-galactose (Alpha-Gal). Clinical symptoms are triggered by contact to red meat or innards but also gelatin or Alpha-Gal carrying therapeutic antibodies. Recently we could identify the Alpha-Gal carrying proteins Aminopeptidase N and Angiotensin converting enzyme I from pork kidney and show their clinical relevance by inducing basophil activation and positive responses in skin prick tests in patients with Alpha-Gal allergy. In contrast to IgG antibodies directed to Alpha-Gal, which are physiologically induced by contact to microbes in early life, the currently accepted hypothesis is that the induction of IgE directed to Alpha-Gal is mediated by tick bites. This is supported by several lines of evidence: a strong correlation between Alpha-Gal allergy and tick bites from Amblyomma, Ixodes and Haemaphysalis species in different parts of the world, a boosting of IgE directed against Alpha-Gal after a tick bite and the detection of Alpha-Gal in the gastrointestinal tract of Ixodes ricinus. The objectives of the present proposal are i) analysing the allergenicity of Alpha-gal carrying natural and engineered molecules, ii) the phenotyping of cells implicated in immune responses to Alpha-gal epitopes in healthy, sensitized and recently exposed individuals, iii) the analysis of the sensitizing mechanism in an alpha-1,3-galactosyltransferase deficient mouse by inducing immune reactions to Alpha-gal. To this end, different routes of antigen contact via the skin, mimicking a tick bite, will be investigated with and without addition of tick saliva as natural adjuvant. The identification of IgE reactive molecules in ticks will contribute to a better diagnosis and risk management of patients. More important, using Alpha-Gal allergy as a model disease, our results will elucidate the basic mechanisms eliciting immune responses and sensitization to carbohydrate allergens via the skin.