Trinh Vu B, Fairclough Robert H
Department of Neurology, Davis School of Medicine, University of California, 1515 Newton Court, Davis, CA 95618, USA.
Biochemistry, Molecular, Cellular, and Developmental Biology Graduate Group, University of California, Davis, CA 95618, USA.
Int J Mol Sci. 2024 Dec 30;26(1):229. doi: 10.3390/ijms26010229.
We have designed and produced 39 amino acid peptide mimics of the and human acetylcholine receptors' (AChRs) main immunogenic regions (MIRs). These conformationally sensitive regions consist of three non-contiguous segments of the AChR α-subunits and are the target of 50-70% of the anti-AChR autoantibodies (Abs) in human myasthenic serum and in the serum of rats with a model of that disease, experimental autoimmune myasthenia gravis (EAMG), induced by immunizing the rats with the electric organ AChR. These MIR segments covalently joined together bind a significant fraction of the monoclonal antibodies (mAbs) raised in rats against electric organ AChR. Many of these mAbs cross react with the rat neuromuscular AChR MIR and induce myasthenic symptoms when injected into naïve rats. The human MIR mimic peptide (H39MIR) is evolutionarily related to that of the electric organ MIR mimic peptide (39MIR) with eight amino acid differences between the two MIR mimics. The mAbs raised to the electric organ AChR MIR cross react with the human and scores of other species' neuromuscular AChRs. However, the mAbs do not cross react with the H39MIR mimic attached to the N-terminus of an intein-chitin-binding domain (H39MIR-IChBD) even though they do bind to the 39MIR-IChBD construct. To account for this difference in binding anti-MIR mAbs, each of the eight human amino acids was substituted individually into the 39MIR-IChBD, and four of them were found to weaken mAb recognition. Substituting the corresponding four amino acids individually and in combination into the homologous positions in H39MIR-IChBD makes chimeric human MIR mimic peptides (/H39MIR), some of which bind anti-MIR mAbs and anti-MIR Abs from rat EAMG and human MG sera. The best mAb binding chimeric peptide constructs may potentially serve as the basis of a diagnostic anti-MIR Ab titer assay that is both prognostic and predictive of disease severity. Furthermore, the best peptides may also serve as the targeting element of a non-steroidal antigen-specific treatment of MG to remove anti-AChR MIR Abs, either as fused to the N-terminals of the human immunoglobin F fragment or as the targeting component of a T cell chimeric autoantibody receptor (CAAR) directed to anti-MIR memory B cells for elimination.
我们设计并制备了39个氨基酸的肽模拟物，它们模拟了电鳗和人类乙酰胆碱受体（AChRs）的主要免疫原性区域（MIRs）。这些构象敏感区域由AChRα亚基的三个不连续片段组成，是人类重症肌无力血清以及通过用电鳗电器官AChR免疫大鼠诱导的该疾病模型（实验性自身免疫性重症肌无力，EAMG）大鼠血清中50 - 70%抗AChR自身抗体（Abs）的靶点。这些共价连接在一起的MIR片段能结合相当一部分在大鼠中产生的针对电器官AChR的单克隆抗体（mAbs）。许多这些mAbs与大鼠神经肌肉AChR MIR发生交叉反应，并在注射到未免疫的大鼠体内时诱发重症肌无力症状。人类MIR模拟肽（H39MIR）在进化上与电鳗电器官MIR模拟肽（39MIR）相关，这两种MIR模拟物之间有8个氨基酸差异。针对电器官AChR MIR产生的mAbs与人类以及许多其他物种的神经肌肉AChRs发生交叉反应。然而，这些mAbs不与连接在内含肽 - 几丁质结合结构域（IChBD）N端的H39MIR模拟物（H39MIR - IChBD）发生交叉反应，尽管它们确实能结合39MIR - IChBD构建体。为了解释抗MIR mAbs结合的这种差异，将8个人类氨基酸中的每一个分别替换到39MIR - IChBD中，发现其中4个会削弱mAb的识别。将相应的4个电鳗氨基酸分别或组合替换到H39MIR - IChBD的同源位置，制成嵌合人类MIR模拟肽（/H39MIR），其中一些能结合来自大鼠EAMG和人类MG血清的抗MIR mAbs和抗MIR Abs。最佳的mAb结合嵌合肽构建体可能潜在地作为一种诊断抗MIR Ab滴度测定的基础，该测定既能预测疾病又能预测疾病严重程度。此外，最佳肽还可作为MG非甾体抗原特异性治疗的靶向元件，用于清除抗AChR MIR Abs，要么与人类免疫球蛋白F片段的N端融合，要么作为针对抗MIR记忆B细胞的T细胞嵌合自身抗体受体（CAAR）的靶向成分用于清除。
Zotero 插件
