Role of skin prions in disease transmission and diagnostic testing of human prion disease

摘要 Prion(或PrPSc)是致命性传染性Prion疾病的病原体，包括散发性的 克雅氏病(sCJD，人类最常见的普恩病毒病) 瘙痒病、疯牛病和动物慢性消耗性疾病。SCJD可通过医疗或 由于患者大脑中大量的传染性病毒污染而进行的外科手术。值得注意的是，一些 流行病学研究也将scjd风险与非神经外科手术联系起来，但有实验证据。 因为这样的联系是缺乏的。SCJD目前是无法治愈的。在临床症状出现时，永久性脑 损害已经发生。缺乏对这种疾病侵入性较小的早期诊断测试可能会导致 错过了未来治疗的关键窗口，以及由于文化限制而导致的低脑部尸检率 防止对有效预防医源性sCJD至关重要的sCJD的监测 变速箱。我们最近的研究使用了高灵敏的实时震动诱导转换(RT- Quic)检测和人源化转基因(TG)小鼠的生物检测表明，sCJD的皮肤 患者携带有传染性的普鲁恩病毒(Orrú等人，2017年)。我们新的初步结果进一步表明，皮肤 通过RT-QuIC和序列蛋白质错折叠循环扩增(SPMCA)检测到PrPSc 在普恩病毒感染的动物模型中处于无症状阶段。我们假设皮肤PrPSc可以同时是 医源性病毒传播的来源和临床前/死前/死后的生物标记物 Pron病的诊断性测试。为了检验这一假设，我们将追求以下四个目标： (1)定量检测sCJD患者皮肤中的PrPSc的传染性；(2)确定PrPSc在 皮肤，(3)评估皮肤PrPSc作为医源性传播来源的潜力，以及(4)验证 皮肤PrPSc作为诊断PrP疾病的生物标志物。我们预期拟议的研究不仅会 阐明了人与人之间通过皮肤病毒传播sCJD的潜在风险，但也建立了 Pron病的临床前/死前/死后诊断替代试验。此外，新的 这项研究产生的知识可能适用于更常见的神经退行性疾病，如 如阿尔茨海默氏症和帕金森氏病，这些疾病特异的错误折叠蛋白 在不同患者的皮肤上观察。

ABSTRACT Prions (or PrPSc) are the causal agents of fatal transmissible prion diseases including sporadic Creutzfeldt-Jakob disease (sCJD, the most common human prion disease) in humans as well as scrapie, mad cow disease and chronic wasting disease in animals. sCJD is transmissible via medical or surgical procedures due to contamination by abundant infectious prions in the brain of patients. Notably, some epidemiological studies have also associated sCJD risk with non-neurosurgeries but experimental evidence for such a link is lacking. sCJD is currently incurable. At the onset of clinical symptoms, permanent brain damages already occurred. The absence of less invasive early diagnostic tests for the disease can result in missing the critical window for future treatments, and low brain autopsy rate due to cultural constraints prevents the surveillance of sCJD that is essential for effective prevention of iatrogenic sCJD transmissions. Our recent study using the highly sensitive real-time quaking-induced conversion (RT- QuIC) assay and humanized transgenic (Tg) mice-based bioassay revealed that the skin of sCJD patients harbors infectious prions (Orrú et al., 2017). Our new preliminary results further indicate that skin PrPSc is detectable by both RT-QuIC and serial protein misfolding cyclic amplification (sPMCA) assays even at the asymptomatic stage in a prion-infected animal model. We hypothesize that skin PrPSc can be both a source of iatrogenic prion transmission and a biomarker for preclinical/premortem/postmortem diagnostic testing of prion diseases. To test for the hypothesis, the following four Aims will be pursued: (1) to quantitate infectivity of skin prions from sCJD patients, (2) to pinpoint the distribution of PrPSc within the skin, (3) to evaluate the potential of skin PrPSc as the source of iatrogenic transmission, and (4) to validate skin PrPSc as a biomarker for diagnosis of prion diseases. We expect that the proposed study will not only shed light on the potential risk of human-to-human sCJD transmission via skin prions but also establish alternative preclinical/premortem/postmortem diagnostic assays for prion diseases. Moreover, new knowledge generated from this study may apply to much more common neurodegenerative diseases such as Alzheimer’s and Parkinson’s diseases where the disease-specific misfolded proteins have been observed in the skin of respective patients.