- 作者列表："Vallabh SM","Minikel EV","Williams VJ","Carlyle BC","McManus AJ","Wennick CD","Bolling A","Trombetta BA","Urick D","Nobuhara CK","Gerber J","Duddy H","Lachmann I","Stehmann C","Collins SJ","Blennow K","Zetterberg H","Arnold SE
BACKGROUND:Prion disease is neurodegenerative disease that is typically fatal within months of first symptoms. Clinical trials in this rapidly declining symptomatic patient population have proven challenging. Individuals at high lifetime risk for genetic prion disease can be identified decades before symptom onset and provide an opportunity for early therapeutic intervention. However, randomizing pre-symptomatic carriers to a clinical endpoint is not numerically feasible. We therefore launched a cohort study in pre-symptomatic genetic prion disease mutation carriers and controls with the goal of evaluating biomarker endpoints that may enable informative trials in this population. METHODS:We collected cerebrospinal fluid (CSF) and blood from pre-symptomatic individuals with prion protein gene (PRNP) mutations (N = 27) and matched controls (N = 16), in a cohort study at Massachusetts General Hospital. We quantified total prion protein (PrP) and real-time quaking-induced conversion (RT-QuIC) prion seeding activity in CSF and neuronal damage markers total tau (T-tau) and neurofilament light chain (NfL) in CSF and plasma. We compared these markers cross-sectionally, evaluated short-term test-retest reliability over 2-4 months, and conducted a pilot longitudinal study over 10-20 months. RESULTS:CSF PrP levels were stable on test-retest with a mean coefficient of variation of 7% for both over 2-4 months in N = 29 participants and over 10-20 months in N = 10 participants. RT-QuIC was negative in 22/23 mutation carriers. The sole individual with positive RT-QuIC seeding activity at two study visits had steady CSF PrP levels and slightly increased tau and NfL concentrations compared with the others, though still within the normal range, and remained asymptomatic 1 year later. T-tau and NfL showed no significant differences between mutation carriers and controls in either CSF or plasma. CONCLUSIONS:CSF PrP will be interpretable as a pharmacodynamic readout for PrP-lowering therapeutics in pre-symptomatic individuals and may serve as an informative surrogate biomarker in this population. In contrast, markers of prion seeding activity and neuronal damage do not reliably cross-sectionally distinguish mutation carriers from controls. Thus, as PrP-lowering therapeutics for prion disease advance, "secondary prevention" based on prodromal pathology may prove challenging; instead, "primary prevention" trials appear to offer a tractable paradigm for trials in pre-symptomatic individuals.
背景: 朊病毒病是一种神经退行性疾病，通常在首次出现症状的 6 个月内致命。在这个快速下降的症状患者人群中的临床试验已被证明具有挑战性。遗传性朊病毒病终生风险高的个体可以在症状发作前几十年被识别出来，并为早期治疗干预提供机会。然而，将症状前携带者随机分配到临床终点在数值上是不可行的。因此，我们在症状前遗传朊病毒疾病突变携带者和对照中开展了一项队列研究，目的是评估生物标志物终点，可能使该人群的信息试验成为可能。 方法: 我们收集了朊蛋白基因 (PRNP) 突变 (N = 27) 和匹配对照 (N = 16) 的症状前个体的脑脊液 (CSF) 和血液,在马萨诸塞州总医院的队列研究中。我们定量了总朊蛋白 (PrP) 和实时抖动诱导的转化 (RT-QuIC) 朊病毒在 CSF 中的接种活性和神经元损伤标志物总 tau (T-tau) 和 CSF 和血浆中的神经丝轻链 (NfL)。我们对这些标志物进行了横断面比较，在 2-4 个月内评价了短期重测信度，并在 10-20 个月内进行了初步纵向研究。 结果: CSF PrP 水平在重测时稳定，平均变异系数为 7%，在 N = 29 名参与者中超过 2-4 个月，在 N = 20 个月中超过 10-20 个月。10 名与会者。22/23 例突变携带者 RT-QuIC 阴性。在两次研究访视时 RT-QuIC 播种活性阳性的个体与其他个体相比，CSF PrP 水平稳定，tau 和 NfL 浓度略有增加，尽管仍在正常范围内。1 年后仍无症状。T-tau 和 NfL 在 CSF 或血浆中显示突变携带者与对照组无显著差异。 结论: CSF PrP 将被解释为在有症状前个体中降低 PrP 治疗的药效学读数，并可能在该人群中作为信息替代生物标志物。相比之下，朊病毒播种活性和神经元损伤的标志物不能可靠地将突变携带者与对照区分开来。因此，随着 PrP 降低治疗朊病毒病的进展，基于前驱病理的 “二级预防” 可能被证明具有挑战性; 相反,“一级预防” 试验似乎为症状前个体的试验提供了可追踪的范例。
METHODS:OBJECTIVE:To report the incidence of prion disease in the United States. METHODS:Prion disease decedents were retrospectively identified from the US national multiple cause-of-death data for 2003-2015 and matched with decedents in the National Prion Disease Pathology Surveillance Center (NPDPSC) database through comparison of demographic variables. NPDPSC decedents with neuropathologic or genetic test results positive for prion disease for whom no match was found in the multiple cause-of-death data were added as cases for incidence calculations; those with cause-of-death data indicating prion disease but with negative neuropathology results were removed. Age-specific and age-adjusted average annual incidence rates were then calculated. RESULTS:A total of 5,212 decedents were identified as having prion disease, for an age-adjusted average annual incidence of 1.2 cases per million population (range 1.0 per million [2004 and 2006] to 1.4 per million ). The median age at death was 67 years. Ten decedents were <30 years of age (average annual incidence of 6.2 per billion); only 2 of these very young cases were sporadic forms of prion disease. Average annual incidence among those ≥65 years of age was 5.9 per million. CONCLUSIONS:Prion disease incidence can be estimated by augmenting mortality data with the results of neuropathologic and genetic testing. Cases <30 years of age were extremely rare, and most could be attributed to exogenous factors or the presence of a genetic mutation. Continued vigilance for prion diseases in all age groups remains prudent.
METHODS::The conformational conversion of the cellular prion protein (PrPC) to the misfolded and aggregated isoform, termed scrapie prion protein (PrPSc), is key to the development of a group of neurodegenerative diseases known as transmissible spongiform encephalopathies (TSEs). Although the conversion mechanism is not fully understood, the role of gene polymorphisms in varying susceptibilities to prion diseases is well established. In ovine, specific gene polymorphisms in PrPC alter prion disease susceptibility: the Valine136-Glutamine171 variant (Susceptible structure) displays high susceptibility to classical scrapie while the Alanine136-Arginine171 variant (Resistant structure) displays reduced susceptibility. The opposite trend has been reported in atypical scrapie. Despite the differentiation between classical and atypical scrapie, a complete understanding of the effect of polymorphisms on the structural dynamics of PrPC is lacking. From our structural bioinformatics study, we propose that polymorphisms locally modulate the network of residue interactions in the globular C-terminus of the ovine recombinant prion protein while maintaining the overall fold. Although the two variants we examined exhibit a densely connected group of residues that includes both β-sheets, the β2-α2 loop and the N-terminus of α-helix 2, only in the Resistant structure do most residues of α-helix 2 belong to this group. We identify the structural role of Valine136Alanine and Glutamine171Arginine: modulation of residue interaction networks that affect the connectivity between α-helix 2 and α-helix 3. We propose blocking interactions of residue 171 as a potential target for the design of therapeutics to prevent efficient PrPC misfolding. We discuss our results in the context of initial PrPC conversion and extrapolate to recently proposed PrPSc structures.Communicated by Ramaswamy H. Sarma.
METHODS::Although experimental transmission of bovine spongiform encephalopathy (BSE) to pigs and transgenic mice expressing pig cellular prion protein (PrPC) (porcine PrP [PoPrP]-Tg001) has been described, no natural cases of prion diseases in pig were reported. This study analyzed pig-PrPC susceptibility to different prion strains using PoPrP-Tg001 mice either as animal bioassay or as substrate for protein misfolding cyclic amplification (PMCA). A panel of isolates representatives of different prion strains was selected, including classic and atypical/Nor98 scrapie, atypical-BSE, rodent scrapie, human Creutzfeldt-Jakob-disease and classic BSE from different species. Bioassay proved that PoPrP-Tg001-mice were susceptible only to the classic BSE agent, and PMCA results indicate that only classic BSE can convert pig-PrPC into scrapie-type PrP (PrPSc), independently of the species origin. Therefore, conformational flexibility constraints associated with pig-PrP would limit the number of permissible PrPSc conformations compatible with pig-PrPC, thus suggesting that pig-PrPC may constitute a paradigm of low conformational flexibility that could confer high resistance to the diversity of prion strains.