Department of Biochemistry and Molecular Biology, School of Chemistry, Complutense University, Madrid, Spain.
Inmunotek, Alcalá de Henares, Spain; Department of Immunology, Hospital Clínico San Carlos, Madrid, Spain.
J Allergy Clin Immunol. 2016 Aug;138(2):558-567.e11. doi: 10.1016/j.jaci.2016.02.029. Epub 2016 Apr 13.
Allergen immunotherapy (AIT) is the only curative treatment for allergy. AIT faces pitfalls related to efficacy, security, duration, and patient compliance. Novel vaccines overcoming such inconveniences are in demand.
We sought to study the immunologic mechanisms of action for novel vaccines targeting dendritic cells (DCs) generated by coupling glutaraldehyde-polymerized grass pollen allergoids to nonoxidized mannan (PM) compared with glutaraldehyde-polymerized allergoids (P) or native grass pollen extracts (N).
Skin prick tests and basophil activation tests with N, P, or PM were performed in patients with grass pollen allergy. IgE-blocking experiments, flow cytometry, confocal microscopy, cocultures, suppression assays, real-time quantitative PCR, ELISAs, and ELISpot assays were performed to assess allergen capture by human DCs and T-cell responses. BALB/c mice were immunized with PM, N, or P. Antibody levels, cytokine production by splenocytes, and splenic forkhead box P3 (FOXP3)(+) regulatory T (Treg) cells were quantified. Experiments with oxidized PM were also performed.
PM displays in vivo hypoallergenicity, induces potent blocking antibodies, and is captured by human DCs much more efficiently than N or P by mechanisms depending on mannose receptor- and dendritic cell-specific intercellular adhesion molecule 3-grabbing nonintegrin-mediated internalization. PM endorses human DCs to generate functional FOXP3(+) Treg cells through programmed death ligand 1. Immunization of mice with PM induces a shift to nonallergic responses and increases the frequency of splenic FOXP3(+) Treg cells. Mild oxidation impairs these effects in human subjects and mice, demonstrating the essential role of preserving the carbohydrate structure of mannan.
Allergoids conjugated to nonoxidized mannan represent suitable vaccines for AIT. Our findings might also be of the utmost relevance to development of therapeutic interventions in other immune tolerance-related diseases.
变应原免疫疗法（AIT）是治疗过敏的唯一根治方法。AIT 面临着与疗效、安全性、持续时间和患者依从性相关的困难。人们需要开发能够克服这些不便的新型疫苗。
我们旨在研究新型疫苗的免疫作用机制，该疫苗通过将戊二醛聚合的草花粉变应原与未氧化甘露聚糖（PM）偶联来靶向树突状细胞（DC），与戊二醛聚合变应原（P）或天然草花粉提取物（N）进行比较。
对草花粉过敏的患者进行 N、P 或 PM 的皮肤点刺试验和嗜碱性粒细胞活化试验。进行 IgE 阻断实验、流式细胞术、共聚焦显微镜、共培养、抑制实验、实时定量 PCR、ELISA 和 ELISpot 检测，以评估人 DC 对变应原的捕获和 T 细胞反应。用 PM、N 或 P 对 BALB/c 小鼠进行免疫。定量检测抗体水平、脾细胞产生的细胞因子和脾叉头框 P3（FOXP3）+调节性 T（Treg）细胞。还进行了氧化 PM 的实验。
PM 在体内显示出低变应原性，诱导出有效的阻断抗体，并且通过甘露糖受体和树突状细胞特异性细胞间黏附分子 3 抓取非整联蛋白介导的内化等机制，比 N 或 P 更有效地被人 DC 捕获。PM 通过程序性死亡配体 1 促进人 DC 生成功能性 FOXP3+Treg 细胞。用 PM 免疫小鼠可诱导向非过敏反应转变，并增加脾 FOXP3+Treg 细胞的频率。轻度氧化会损害这些在人体和小鼠中的作用，表明保持甘露聚糖的碳水化合物结构至关重要。
与未氧化甘露聚糖偶联的变应原代表了 AIT 的合适疫苗。我们的发现对于开发其他免疫耐受相关疾病的治疗干预措施也可能具有至关重要的意义。
