改造抗原肽在抗肾小球基底膜病中的免疫治疗作用

Anti-glomerular basement membrane (GBM) disease is a classic autoimmune disorder characterized by the presence of autoantibodies directed against GBM. Current treatment is plasmapheresis coupled with broadly immunosuppressive therapy, which is either costly or has tremendous side effects. Attempts to introduce a greater degree of specificity into the treatment would be much beneficial. Our previous work identified a nephrogenic T cell epitope P14 (α3 127-148) on GBM, which could induce crescentic glomerulonephritis in Wistar-Kyoto rats with the hallmarks of human ant-GBM disease. Moreover, P14 was proved to have intermediate to high affinity to HLA-DR15b，which has strong association with anti-GBM disease. We further defined the critical amino acid residues of P14 for its pathogenicity and the binding motif to HLA-DR15b. In the present study, we aim to design a set of altered peptide ligands derived from P14 by substituting the TCR contacting amino acids with the ones from α1 chain. Peptides will be screened in vitro by its binding affinity to HLA-DR15b and the inhibitory effects of T cell activation. The therapeutic effects of these peptides will be further explored in HLA-DRB1*1501 transgenic mice model of anti-GBM disease.

抗肾小球基底膜（glomerular basement membrane, GBM）病是经典的自身免疫性肾脏病，起病急、预后差，目前尚缺乏有效的治疗方案。我们的前期工作在肾小球基底膜α3链上发现了一个T细胞抗原表位P14，是启动抗GBM病及抗原表位扩展的初始位点，并且明确了P14上致病的关键氨基酸。我们的前期研究还发现基底膜上的α1链与α3链高度同源，但不具有致病性。因此，利用氨基酸同源替换、改造P14的致病位点而设计的治疗肽，有可能实现疾病抗原特异性的免疫治疗。本课题拟采用α1链上相应的氨基酸，对P14与T细胞受体结合的致病位点进行替换，设计一组改造抗原肽。通过体外细胞学实验，筛选其中可以抑制P14诱导的T细胞活化的肽段，进而在HLA-DRB1*1501转基因小鼠的疾病模型中验证这些肽段对疾病的预防及治疗作用，并探讨其发挥作用的免疫机制，从而为抗GBM病的治疗提供新的方向。

本课题前期研究在肾小球基底膜GBM上发现了的一个致病抗原表位P14。通过对其序列上致病性关键氨基酸以及与HLA-DR15分子的结合位点（分子建模）的鉴定，设计并合成了一条治疗肽m-P14，替换了原有P14上的一个致病关键氨基酸。.体外实验证实该治疗肽m-P14免疫动物时没有致病作用。我们在前期工作中建立的WKY大鼠抗GBM病模型中进一步研究了m-P14的治疗作用，结果显示，m-P14在早期治疗组（造模开始给药）以及治疗组（出现肾脏损害开始给药）均有较显著的治疗作用，大鼠的肾损害均显著减轻。我们进一步研究了m-P14的治疗机制，发现其可以影响体内Th细胞亚群的分化，抗原表位的扩展等发挥治疗作用。该研究结果发表在肾脏病领域的重要杂志JASN,并已申请专利。

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