Universidade Estadual do Norte Fluminense-Darcy Ribeiro - UENF, Centro de Biociências e Biotecnologia - CBB, Laboratório de Química e Função de Proteínas e Peptídeos - LQFPP, Campos dos Goytacazes, RJ, Brasil.
Universidade Federal do Paraná - UFPR, Departamento de Patologia Básica - DPB, Laboratório de Imunologia Comparada - LIC, Curitiba, PR, Brasil.
Braz J Biol. 2024 Feb 26;83:e274260. doi: 10.1590/1519-6984.274260. eCollection 2024.
Several studies have been carried out to expand the use of Ricinus communis L. castor bean (Ricinus communis L castor bean.). This oilseed finds appropriate conditions for its development in Brazil, with more than 700 applications. The main allergens of this plant are Ric c1 and Ric c3, that cross-react with various aeroallergens and food allergens such as peanuts, soybeans, corn, and wheat. This study aimed to determine the effect of mutations in Ric c3 amino acid residues known to affect IgE binding and allergy challenges. Based on the Ric c3 structure, B-cell epitopes, and amino acid involved in IgE binding, we produce recombinant mutant protein, mrRic c3, secreted from E. coli. Strategic glutamic acid residues in IgE-biding regions were changed by Leucine. The allergenicity of mrRic c3 was evaluated by determination of IgE, IgG1, and total IgG in immunized Balb/c mice and by degranulation assays of mast cells isolated from Wistar rats. The mrRic c3 presented a percentage of mast cell degranulation close to that seen in the negative control, and the immunization of mice with mrRic c3 presented lower levels of IgE and IgG1 than the group treated with the protein without mutations. The mutant mrRic c3 had an altered structure and reduced ability to stimulate pro-inflammatory responses and bind IgE but retained its ability to induce blocking antibodies. Thus, producing a hypoallergenic mutant allergen (mrRic c3) may be essential in developing new AIT strategies.
已经进行了多项研究来扩大蓖麻（Ricinus communis L castor bean）的用途。这种油籽在巴西找到了适宜的发展条件，有超过 700 种应用。该植物的主要过敏原是 Ric c1 和 Ric c3，与各种空气过敏原和食物过敏原（如花生、大豆、玉米和小麦）发生交叉反应。本研究旨在确定已知影响 IgE 结合和过敏挑战的 Ric c3 氨基酸残基突变的影响。基于 Ric c3 的结构、B 细胞表位和与 IgE 结合有关的氨基酸，我们从大肠杆菌中分泌出重组突变蛋白 mrRic c3。通过将 IgE 结合区域中的谷氨酸残基突变为亮氨酸来改变 IgE 结合区域中的氨基酸。通过测定免疫 Balb/c 小鼠的 IgE、IgG1 和总 IgG 以及分离自 Wistar 大鼠的肥大细胞脱颗粒试验来评估 mrRic c3 的变应原性。mrRic c3 的肥大细胞脱颗粒百分比接近阴性对照，与未突变蛋白处理组相比，用 mrRic c3 免疫的小鼠的 IgE 和 IgG1 水平较低。突变体 mrRic c3 的结构发生改变，刺激促炎反应和结合 IgE 的能力降低，但保留诱导阻断抗体的能力。因此，产生低变应原性突变过敏原（mrRic c3）可能对于开发新的 AIT 策略至关重要。
