Identification and analysis of multivalent proteolytically resistant peptides from gluten: Implications for Celiac Sprue
Identification and analysis of multivalent proteolytically resistant peptides from gluten: Implications for Celiac Sprue
复制标题
DOI：
10.1021/pr050173t
复制
发表时间：
2005-09-01
影响因子：
4.4
通讯作者：
Khosla, C
中科院分区：
文献类型：
--
作者：
Shan, L;Qiao, SW;Khosla, C
来自小麦、黑麦和大麦的膳食面筋蛋白是乳糜泻（一种广泛存在的小肠免疫疾病）的免疫发病机制的主要触发因素。最近的分子和结构分析的代表性面筋蛋白，最显着的α和γ-麦醇溶蛋白从小麦，提高了我们对这些致病机制的理解。特别是，基于在生理条件下由α-麦醇溶蛋白产生的33-mer肽的性质，已经提出了谷蛋白的消化抗性和炎症特性之间的联系。在这里，我们报告三条线的调查，以支持这一假设。首先，α-2麦胶蛋白的缺失突变体的生物化学和免疫学分析证实，DQ 2限制性T细胞对α-2麦胶蛋白的应答是针对聚集在33-mer内的表位。第二，代表性的γ-麦醇溶蛋白的蛋白水解分析导致另一种多价26聚体肽的鉴定，该肽也对进一步的胃、胰腺和肠刷状缘降解具有抗性，并且是人转氨酶2（TG 2）的良好底物。与33-mer类似，合成的26-mer肽与单价对照肽相比显示出显著增强的T细胞抗原性。最后，谷蛋白质组的计算机分析导致至少60个推定的肽的鉴定，这些肽具有33-mer和26-mer肽的共同特征。总之，这些结果突出了生理产生的，蛋白水解稳定的，TG 2反应性的多价肽在乳糜泻患者对膳食麸质的免疫应答中的关键作用。脯氨酰内肽酶处理被证明消除了33-mer和26-mer肽的抗原性，并且还被预测对从谷蛋白蛋白质组内的其他多肽中鉴定的其他富含脯氨酸的puronectin免疫毒性肽具有相当的影响。
Dietary gluten proteins from wheat, rye, and barley are the primary triggers for the immunopathogenesis of Celiac Sprue, a widespread immune disease of the small intestine. Recent molecular and structural analyses of representative gluten proteins, most notably alpha- and gamma-gliadin proteins from wheat, have improved our understanding of these pathogenic mechanisms. In particular, based on the properties of a 33-mer peptide, generated from alpha-gliadin under physiological conditions, a link between digestive resistance and inflammatory character of gluten has been proposed. Here, we report three lines of investigation in support of this hypothesis. First, biochemical and immunological analysis of deletion mutants of alpha-2 gliadin confirmed that the DQ2 restricted T cell response to the alpha-2 gliadin are directed toward the epitopes clustered within the 33-mer. Second, proteolytic analysis of a representative gamma-gliadin led to the identification of another multivalent 26-mer pepticle that was also resistant to further gastric, pancreatic and intestinal brush border degradation, and was a good substrate of human transglutaminase 2 (TG2). Analogous to the 33-mer, the synthetic 26-mer pepticle displayed markedly enhanced T cell antigenicity compared to monovalent control peptides. Finally, in silico analysis of the gluten proteome led to the identification of at least 60 putative peptides that share the common characteristics of the 33-mer and the 26-mer peptides. Together, these results highlight the pivotal role of physiologically generated, proteolytically stable, TG2-reactive, multivalent peptides in the immune response to dietary gluten in Celiac Sprue patients. Prolyl endopeptidase treatment was shown to abolish the antigenicity of both the 33-mer and the 26-mer peptides, and was also predicted to have comparable effects on other proline-rich putatively immunotoxic peptides identified from other polypeptides within the gluten proteome.