Prion Transport Across the Blood-Brain Barrier

描述（由申请人提供）：朊病毒疾病代表了一组不同的感染性神经退行性疾病。最被接受的假设是，传染因子（称为朊病毒）是一种完全没有核酸的正常蛋白质的错误折叠版本。当感染性形式（PrPsc）通过与正常形式（PrPc）可逆结合而将其转化为感染性形式时，疾病就会传播。在痒病中，朊病毒是一种糖蛋白，其核心蛋白约为30,000 MW。为了产生中枢神经系统疾病，PrPsc必须进入大脑，这需要它通过血脑屏障（BBB）。本研究的主要目标是确定PrPsc如何穿过血脑屏障，并最终制定阻断其进入中枢神经系统的治疗策略，从而预防朊病毒疾病。我们和其他人的工作表明，其他神经毒性糖蛋白（如小麦胚芽凝集素和gp120，艾滋病病毒的外壳）通过诱导吸收性内吞作用（AE）穿过血脑屏障。我们假设PrPsc通过AE机制穿过血脑屏障。这一假说提供了一种无细胞PrPsc和受PrPsc感染的免疫细胞通过血脑屏障的机制，并解释了为什么中枢神经系统的某些区域，如胸脊髓，可以成为特别的靶点。虽然我们的工作假设是无细胞PrPsc是主要机制，但这些实验旨在确定PrPsc进入中枢神经系统的其他可能机制（免疫细胞转移，逆行脾神经传递，跨膜扩散，饱和载体/受体介导的运输，通过细胞外途径渗漏）的运作程度。我们将使用高纯度、放射性标记的PrPsc来确定转运和分布到脑区域、脊髓和脑脊液的速率，脾神经和免疫细胞在神经侵袭中的作用，并在体外模型中检查通过脑内皮细胞的细胞生物学。概要：朊病毒引起罕见但毁灭性的疾病，如疯牛病。要引起疾病，朊病毒必须穿过血脑屏障进入大脑。我们将确定朊病毒如何穿过血脑屏障。了解朊病毒是如何进入大脑的，将有助于制定预防朊病毒疾病的策略。

DESCRIPTION (provided by applicant): Prion diseases represent a diverse group of infectious neurodegenerative disorders. The most accepted hypothesis is that the infectious agent (termed prion) is a misfolded version of a normal protein completely devoid of nucleic acids. Disease is propagated when the infectious form (PrPsc) converts the normal form (PrPc) to the infectious form by reversibly combining with it. In scrapie, the prion is a glycoprotein with about a 30,000 MW protein core. To produce central nervous system (CNS) disease, PrPsc must enter the brain, which requires it negotiate the blood-brain barrier (BBB). The major goal of this research is to determine how PrPsc crosses the BBB and ultimately to develop therapeutic strategies for blocking passage into the CNS and so preventing prion disease. Work by us and others have shown that other neurotoxic glycoproteins (such as wheatgerm agglutinin and gp120, the coat of the AIDS virus) cross the BBB by inducing absorptive endocytosis (AE). We hypothesize that PrPsc crosses the BBB through the mechanism of AE. This hypothesis provides a mechanism for passage across the BBB of cell-free PrPsc and of PrPsc- infected immune cells and explains how some regions of the CNS, such as the thoracic spinal cord, can be especially targeted. Although our working hypothesis is that cell-free PrPsc is the major mechanism, these experiments are designed to determine the extent to which the other possible mechanisms of entry into the CNS (immune cell transfer, retrograde splenic nerve transmission, transmembrane diffusion, saturable carrier/receptor mediated transport, leakage via extracellular pathways) are operational for PrPsc. We will use highly purified, radioactively labeled PrPsc to determine rates of transport and distribution into brain regions, spinal cord, and CSF, the role of splenic nerves and immune cells in neuroinvasion, and in vitro models to examine the cellular biology of passage across the brain endothelial cell. Lay Summary: Prions cause rare, but devastating, diseases such as mad cow disease. To cause disease, prions must cross the blood-brain barrier to enter the brain. We will determine how prions cross the BBB. Knowing how prions enter the brain should lead to strategies on how to prevent prion diseases.