Department of Psychiatry and Behavioral Sciences, Center for Sleep Sciences and Medicine, Stanford University, Palo Alto, CA, USA.
Kleine-Levin Syndrome Foundation, Boston, MA, USA.
Sleep. 2022 Sep 8;45(9). doi: 10.1093/sleep/zsac097.
Kleine-Levin syndrome (KLS) is characterized by relapsing-remitting episodes of hypersomnia, cognitive impairment, and behavioral disturbances. We quantified cerebrospinal fluid (CSF) and serum proteins in KLS cases and controls.
SomaScan was used to profile 1133 CSF proteins in 30 KLS cases and 134 controls, while 1109 serum proteins were profiled in serum from 26 cases and 65 controls. CSF and serum proteins were both measured in seven cases. Univariate and multivariate analyses were used to find differentially expressed proteins (DEPs). Pathway and tissue enrichment analyses (TEAs) were performed on DEPs.
Univariate analyses found 28 and 141 proteins differentially expressed in CSF and serum, respectively (false discovery rate <0.1%). Upregulated CSF proteins included IL-34, IL-27, TGF-b, IGF-1, and osteonectin, while DKK4 and vWF were downregulated. Pathway analyses revealed microglial alterations and disrupted blood-brain barrier permeability. Serum profiles show upregulation of Src-family kinases (SFKs), proteins implicated in cellular growth, motility, and activation. TEA analysis of up- and downregulated proteins revealed changes in brain proteins (p < 6 × 10-5), notably from the pons, medulla, and midbrain. A multivariate machine-learning classifier performed robustly, achieving a receiver operating curve area under the curve of 0.90 (95% confidence interval [CI] = 0.78-1.0, p = 0.0006) in CSF and 1.0 (95% CI = 1.0-1.0, p = 0.0002) in serum in validation cohorts, with some commonality across tissues, as the model trained on serum sample also discriminated CSF samples of controls versus KLS cases.
Our study identifies proteomic KLS biomarkers with diagnostic potential and provides insight into biological mechanisms that will guide future research in KLS.
克莱恩-莱文综合征（KLS）的特征是反复发作的过度嗜睡、认知障碍和行为障碍。我们对 KLS 病例和对照者的脑脊液（CSF）和血清蛋白进行了定量分析。
使用 SomaScan 对 30 例 KLS 病例和 134 例对照者的 1133 种 CSF 蛋白进行了分析，对 26 例病例和 65 例对照者的 1109 种血清蛋白进行了分析。在 7 例患者中同时测量了 CSF 和血清蛋白。使用单变量和多变量分析来寻找差异表达蛋白（DEPs）。对 DEPs 进行了途径和组织富集分析（TEAs）。
单变量分析发现 CSF 和血清中分别有 28 种和 141 种蛋白差异表达（错误发现率<0.1%）。上调的 CSF 蛋白包括 IL-34、IL-27、TGF-b、IGF-1 和骨粘连蛋白，而 DKK4 和 vWF 下调。途径分析显示小胶质细胞改变和血脑屏障通透性破坏。血清图谱显示 Src 家族激酶（SFKs）的上调，这些蛋白参与细胞生长、运动和激活。上调和下调蛋白的 TEA 分析显示脑蛋白的变化（p<6×10-5），特别是来自脑桥、延髓和中脑的蛋白。多变量机器学习分类器表现稳健，在验证队列中 CSF 的曲线下面积为 0.90（95%置信区间[CI]为 0.78-1.0，p=0.0006），血清为 1.0（95% CI = 1.0-1.0，p=0.0002），组织间存在一定的共性，因为在血清样本上训练的模型也可以区分对照者的 CSF 样本与 KLS 病例。
我们的研究确定了具有诊断潜力的 KLS 蛋白质组学生物标志物，并提供了对生物学机制的深入了解，这将指导未来的 KLS 研究。
