Nesbit Jacqueline B, Schein Catherine H, Braun Benjamin A, Gipson Stephen A Y, Cheng Hsiaopo, Hurlburt Barry K, Maleki Soheila J
Dept of Agriculture-Agricultural Research Service-Southern Regional Research Center (USDA-ARS-SRRC), New Orleans, LA, United States.
Department of Biochemistry and Molecular Biology, Institute for Human Infection and Immunity, University of Texas Medical Branch at Galveston (UTMB), TX, United States.
Mol Immunol. 2020 May 19;122:223-231. doi: 10.1016/j.molimm.2020.03.017.
Many individuals with peanut (PN) allergy have severe reactions to tree nuts (TN) such as walnuts or cashews. Although allergenic proteins in TN and PN have overall low identity, they share discrete sequences similar in physicochemical properties (PCP) to known IgE epitopes. Here, PCP-consensus peptides (cp, 13 aa and 31 aa) were identified from an alignment of epitope rich regions of walnut vicilin, Jug r 2, leader sequence (J2LS) and cross-reactive epitopes in the 2S albumins of peanut and synthesized. A peptide similarity search in the Structural Database of Allergenic Proteins (SDAP) revealed a network of peptides similar (low property distance, PD) to the 13 aa cp (13cp) in many different plant allergens. Peptides similar to the 13cp in PN and TN allergens bound IgE from sera of patients allergic to PN and TN in peptide microarray analysis. The 13cp was used to produce a rabbit consensus peptide antibody (cpAB) that detected proteins containing repeats similar to the 13cp in western blots of various nut extracts, in which reactive proteins were identified by mass spectrometry. The cpAB bound more specifically to allergens and nut extracts containing multiple repeats similar to the 13 cp, such as almond (Pru du 6), peanut (Ara h 2) and walnut (Jug r 2). IgE binding to various nut extracts is inhibited by recombinant J2LS sequence and synthetic 31cp. Thus, several repeated sequences similar to the 13cp are bound by IgE. Multiple similar repeats in several allergens could account for reaction severity and clinically relevant cross-reactivity to PN and TN. These findings may help improve detection, diagnostic, and therapeutic tools.
许多对花生（PN）过敏的个体对核桃或腰果等坚果（TN）会产生严重反应。尽管TN和PN中的致敏蛋白总体上同源性较低，但它们共享一些与已知IgE表位理化性质（PCP）相似的离散序列。在此，通过对核桃伴球蛋白Jug r 2的富含表位区域、前导序列（J2LS）以及花生2S白蛋白中的交叉反应表位进行比对，鉴定出了PCP-共有肽（cp，13个氨基酸和31个氨基酸）并进行了合成。在变应原蛋白结构数据库（SDAP）中进行的肽相似性搜索揭示了许多不同植物变应原中与13个氨基酸的cp（13cp）相似（低性质距离，PD）的肽网络。在肽微阵列分析中，PN和TN变应原中与13cp相似的肽与对PN和TN过敏患者血清中的IgE结合。13cp被用于制备兔共有肽抗体（cpAB），该抗体在各种坚果提取物的蛋白质印迹中检测到含有与13cp相似重复序列的蛋白质，其中通过质谱鉴定出了反应性蛋白。cpAB更特异性地结合含有多个与13cp相似重复序列的变应原和坚果提取物，如杏仁（Pru du 6）、花生（Ara h 2）和核桃（Jug r 2）。重组J2LS序列和合成的31cp可抑制IgE与各种坚果提取物的结合。因此，几个与13cp相似的重复序列可被IgE结合。几种变应原中的多个相似重复序列可能解释了反应的严重程度以及与PN和TN临床相关的交叉反应性。这些发现可能有助于改进检测、诊断和治疗工具。
