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7种细菌毒素（BoNT/ a - g）组成的家族，可导致人类和动物肉毒中毒。它们以神经元为靶点，切割突触囊泡胞吐所需的宿主蛋白，从而阻断突触传递，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BoNT，但人类与BoNT的相互作用发生了重大变化。首先，医学的进步现在可以使以前无法治疗的病人从急性BoNT反应中恢复过来。其次，bont被用作治疗药物，通过长时间的局部注射来靶向神经元。这些变化使我们迫切需要检查接触bont的额外长期后果。事实上，先前的报道和我们的初步研究表明，除了阻断突触囊泡胞吐外，bont的一个子集可能会诱导培养的啮齿动物神经元变性。在目的1中，我们将研究BoNTs是否会诱导人类神经元退化，并在体内模拟治疗应用的啮齿动物模型中进行研究。我们还将研究人类遗传变异是否会使某些人群对主要治疗毒素BoNT/A的潜在细胞毒性敏感。在Aim 2中，我们将检验我们的假设，即bont诱导神经变性是因为它们的底物在维持质膜的膜平衡中起重要作用。目的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，这些研究将确立神经细胞毒性作为一种“新出现的”长期后果是由于bont与人类相互作用的变化，这对于理解肉毒杆菌中毒对患者的长期影响以及确保使用bont作为治疗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.