Background Frontotemporal dementia (FTD) is the second leading cause of early onset dementia following Alzheimer’s disease. It involves atrophy of the frontal and temporal regions of the brain affecting language, memory, and behavior. Transactive response DNA-binding protein 43 (TDP-43) pathology is found in most FTD and ALS cases. It plays a role in transcription, translation and serves as a shuttle between the nucleus and cytoplasm. Prior to its aggregation, TDP-43 exists as polyubiquitinated, hyperphosphorylated C-terminal fragments that correlate well with FTD disease progression. Because of the importance of TDP-43 in these diseases, reagents that can selectively recognize specific toxic TDP variants associated with onset and progression of FTD can be effective diagnostic and therapeutic tools. Results We utilized a novel atomic force microscopy (AFM) based biopanning protocol to isolate single chain variable fragments (scFvs) from a phage display library that selectively bind TDP variants present in human FTD but not cognitively normal age matched brain tissue. We then used the scFvs (FTD-TDP1 through 5) to probe post-mortem brain tissue and sera samples for the presence of FTD related TDP variants. The scFvs readily selected the FTD tissue and sera samples over age matched controls. The scFvs were used in immunohistochemical analysis of FTD and control brain slices where the reagents showed strong staining with TDP in FTD brain tissue slice. FTD-TDP1, FTD-TDP2, FTD-TDP4 and FTD-TDP5 all protected neuronal cells against FTD TDP induced toxicity suggesting potential therapeutic value. Conclusions These results show existence of different disease specific TDP variants in FTD individuals. We have identified a panel of scFvs capable of recognizing these disease specific TDP variants in postmortem FTD tissue and sera samples over age matched controls and can thus serve as a biomarker tool.

中文翻译：

---

对人 FTD 脑源性 TDP-43 变体具有选择性的抗体片段的分离和表征

背景 额颞叶痴呆 (FTD) 是继阿尔茨海默病之后早发性痴呆的第二大原因。它涉及影响语言、记忆和行为的大脑额叶和颞叶区域的萎缩。在大多数 FTD 和 ALS 病例中发现了反式反应 DNA 结合蛋白 43 (TDP-43) 病理。它在转录、翻译中发挥作用，并作为细胞核和细胞质之间的穿梭机。在其聚集之前，TDP-43 以多泛素化、过度磷酸化的 C 端片段形式存在，与 FTD 疾病进展密切相关。由于 TDP-43 在这些疾病中的重要性，可以选择性识别与 FTD 发病和进展相关的特定毒性 TDP 变体的试剂可以成为有效的诊断和治疗工具。结果我们利用一种新的基于原子力显微镜 (AFM) 的生物淘选协议从噬菌体展示文库中分离出单链可变片段 (scFvs)，该文库选择性地结合人类 FTD 中存在的 TDP 变体，但不与认知正常年龄匹配的脑组织结合。然后我们使用 scFvs（FTD-TDP1 到 5）来探测死后脑组织和血清样本中是否存在 FTD 相关的 TDP 变体。scFvs 很容易选择年龄匹配对照的 FTD 组织和血清样本。scFv 用于 FTD 和对照脑切片的免疫组织化学分析，其中试剂在 FTD 脑组织切片中显示出与 TDP 强染色。FTD-TDP1、FTD-TDP2、FTD-TDP4 和 FTD-TDP5 都保护神经元细胞免受 FTD TDP 诱导的毒性，表明潜在的治疗价值。结论 这些结果表明在 FTD 个体中存在不同的疾病特异性 TDP 变异。我们已经确定了一组 scFv，能够识别死后 FTD 组织和年龄匹配对照的血清样本中的这些疾病特异性 TDP 变异，因此可以用作生物标志物工具。