Long-term effects of botulinum neurotoxins on neuronal viability

描述（由申请人提供）：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，可导致人类和动物肉毒杆菌中毒。它们靶向神经元并切割突触囊泡胞吐所需的宿主蛋白质，从而阻断突触传递并使宿主瘫痪。这种作用模式及其在发病机制中的作用已得到充分证实。人类过去主要通过食物中毒接触BoNT，但人类与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疗的患者从急性BoNT行动中恢复过来。其次，BoNT被用作治疗剂，通过长时间的局部注射靶向神经元。这些变化提出了迫切需要研究暴露于BoNT的额外长期后果。事实上，以前的报告和我们的初步研究表明，一个子集的BoNT可以诱导培养的啮齿动物神经元的变性，除了阻断突触囊泡胞吐。在目标1中，我们将研究BoNTs是否可以诱导人类神经元的变性和模拟治疗应用的体内啮齿动物模型。我们还将研究人类遗传变异是否可能使某些人群对主要治疗毒素BoNT/A的潜在细胞毒性敏感。在目标2中，我们将检验我们的假设，即BoNT诱导神经变性，因为它们的底物在维持质膜的膜平衡中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BoNT细胞毒性的机制理解。总之，这些研究将建立神经元细胞毒性作为一个“新出现的”长期后果，由于在BoNT-人类相互作用的变化，具有重要意义的理解长期影响肉毒杆菌中毒的患者和确保安全使用BoNT作为治疗毒素。

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.