Long-term effects of botulinum neurotoxins on neuronal viability

描述(申请人提供)：肉毒杆菌神经毒素是一个由七种细菌毒素(BONT/A-G)组成的家族，可导致人类和动物的肉毒杆菌中毒。它们以神经元为靶点，裂解突触囊泡胞吐所需的宿主蛋白，从而阻止突触传递，使宿主瘫痪。这种作用模式及其在发病机制中的作用已经得到了很好的证实。人类过去主要通过食物中毒接触到BoNTs，但人与BoNT的相互作用发生了重大变化。首先，医学进步现在可以使以前无法治愈的患者从急性骨质疏松症中恢复过来。其次，BoNTs被用作治疗药物，通过长时间的局部注射来靶向神经元。这些变化使人们迫切需要审查暴露于BoNTs的额外的长期后果。事实上，以前的报道和我们的初步研究表明，BoNTs的一个亚群除了阻断突触囊泡的胞吐外，还可能诱导培养的啮齿动物神经元退化。在目标1中，我们将研究BoNTs是否可以在模拟治疗应用的活体啮齿动物模型中诱导人类神经元的退化。我们还将研究人类的遗传变异是否会使某些人群容易受到主要治疗性毒素BONT/A的潜在细胞毒性的影响。在目标2中，我们将检验我们的假设，即BoNTs诱导神经变性是因为它们的底物在维持质膜上的膜平衡方面起着至关重要的作用。目标1将为建立潜在的临床相关性提供坚实的基础。目的2将提供对BONT细胞毒性的机制的理解。总之，这些研究将确定神经元细胞毒性是由于人体与人体相互作用的变化而产生的一种“新出现的”长期后果，对于了解肉毒杆菌中毒对患者的长期影响以及确保将BoNTs用作治疗性毒素的安全性具有重要意义。

DESCRIPTION (provided by applicant): Botulinum neurotoxins are a family of seven bacterial toxins (BoNT/A-G) that cause the disease botulism in humans and animals. They target neurons and cleave host proteins required for synaptic vesicle exocytosis, thereby blocking synaptic transmission and paralyzing the hosts. This mode of action and its role in pathogenesis has been well established. Humans used to get exposed to BoNTs mainly via food poisoning, but significant changes have occurred in human- BoNT interactions. First, medical advances can now revive previously untreatable patients from acute BoNT actions. Second, BoNTs are utilized as therapeutics to target neurons via local injections over long periods of time. These changes have raised the critical need to examine the additional long-term consequences of exposure to BoNTs. Indeed, previous reports and our preliminary studies have revealed that a subset of BoNTs may induce degeneration of cultured rodent neurons in addition to blocking synaptic vesicle exocytosis. In Aim 1, we will examine whether BoNTs may induce degeneration of human neurons and in in vivo rodent models that mimic therapeutic applications. We will also investigate whether human genetic variations might render certain populations susceptible to potential cytotoxicity from the major therapeutic toxin BoNT/A. In Aim 2, we will examine our hypothesis that BoNTs induce neurodegeneration because their substrates play an essential role in maintaining the membrane balance at plasma membranes. Aim 1 will provide a solid foundation for establishing the potential clinical relevance. Aim 2 will provide a mechanistic understanding for BoNT cytotoxicity. Together, these studies will establish neuronal cytotoxicity as a "newly emerged" long-term consequence due to changes in BoNT-human interactions, with significant implications for understanding long-term effects of botulism in patients and for ensuring the safety of using BoNTs as therapeutic toxins.