Laboratory for Molecular and Developmental Biology, Institute for Protein Research, Osaka University, Osaka, Japan.
Department of Ophthalmology, Nagoya University Graduate School of Medicine, Aichi, Japan.
Exp Eye Res. 2021 Nov;212:108770. doi: 10.1016/j.exer.2021.108770. Epub 2021 Sep 22.
Cancer-associated retinal ON bipolar cell dysfunction (CARBD), which includes melanoma-associated retinopathy (MAR), has been reported to be caused by autoantibodies against the molecules expressed in ON bipolar cells, including TRPM1. The purpose of this study was to determine the antigenic regions of the autoantibodies against TRPM1 in the sera of CARBD patients, in whom we previously detected anti-TRPM1 autoantibodies.
The antigenic regions against TRPM1 in the sera of eight CARBD patients were examined by Western blots using HEK293T cells transfected with the plasmids expressing FLAG-tagged TRPM1 fragments. The clinical course of these patients was also documented.
The clinical course differed among the patients. The electroretinograms (ERGs) and symptoms were improved in three patients, deteriorated in one patient, remained unchanged for a long time in one patient, and were not followable in three patients. Seven of the eight sera possessed multiple antigenic regions: two sera contained at least four antigen recognition regions, and three sera had at least three regions. The antigen regions were spread over the entire TRPM1 protein: five sera in the N-terminal intracellular domain, six sera in the transmembrane-containing region, and six sera in the C-terminal intracellular domain. No significant relationship was observed between the location of the antigen epitope and the patients' clinical course.
The antigenic regions of anti-TRPM1 autoantibodies in CARBD patients were present not only in the N-terminal intracellular domain, which was reported in an earlier report, but also in the transmembrane-containing region and in the C-terminal intracellular domain. In addition, the antigenic regions for TRPM1 were found to vary among the CARBD patients examined, and most of the sera had multiple antigenic regions.
癌症相关的视网膜 ON 双极细胞功能障碍（CARBD），包括黑色素瘤相关视网膜病变（MAR），据报道是由针对 ON 双极细胞中表达的分子的自身抗体引起的，包括 TRPM1。本研究的目的是确定 CARBD 患者血清中针对 TRPM1 的自身抗体的抗原区域，我们之前在这些患者中检测到了抗 TRPM1 自身抗体。
使用转染表达 FLAG 标记的 TRPM1 片段的质粒的 HEK293T 细胞通过 Western blot 检查 8 名 CARBD 患者血清中针对 TRPM1 的抗原区域。还记录了这些患者的临床过程。
患者的临床过程不同。三名患者的视网膜电图（ERG）和症状改善，一名患者恶化，一名患者长时间保持不变，三名患者无法随访。八项血清中的七种具有多个抗原区域：两种血清含有至少四个抗原识别区域，三种血清至少有三个区域。抗原区域遍布整个 TRPM1 蛋白：五种血清在 N 端细胞内域，六种血清在跨膜包含区域，六种血清在 C 端细胞内域。抗原表位的位置与患者的临床过程之间没有观察到显著关系。
CARBD 患者抗 TRPM1 自身抗体的抗原区域不仅存在于较早报道的 N 端细胞内域，而且存在于跨膜包含区域和 C 端细胞内域。此外，在检查的 CARBD 患者中发现了 TRPM1 的抗原区域存在差异，并且大多数血清具有多个抗原区域。
