Biophysics of the morphology and motility of Borrelia burgdorferi in diverse envi

描述（由申请人提供）：由伯氏疏螺旋体引起，是美国最常见的蜱传播疾病。如果不治疗，莱姆病可能导致广泛的并发症，通常涉及心脏，关节或神经系统。人们普遍认为，B的运动性。莱姆病的发病机制中必不可少的。B。伯氏菌通过位于周质空间（外膜和细胞壁材料之间的空间）中的旋转螺旋丝（鞭毛）游动。这些周质鞭毛对细胞壁的旋转导致细胞柱的变形，并且这些变形对外部环境施加力。细菌在节肢动物载体（硬蜱）和哺乳动物宿主之间转换。这种地方性流行病循环需要细菌与极其不同的环境相互作用。例如，螺旋体必须能够定殖于蜱中肠，然后从中肠迁移到血腔中。一旦进入血腔，细菌必须向唾液腺移动，附着在腺泡表面，穿透基膜，进入唾液腺管。B。然后将伯氏菌接种到其哺乳动物宿主的皮肤中，在那里它必须通过细胞外基质移位，以便进入为通过血液传播提供入口的小血管。为了侵入关节和其他宿主组织，细胞必须粘附在靶器官的血管内皮上并穿透它们。B独特的运动性和形态。据推测，伯氏菌驱动许多这些过程，因此被认为是莱姆病发病机制中的主要因素。这一建议的主要假设是，驱动B运动的内部机制。Burgdorferi（即，当螺旋体在蜱和哺乳动物宿主之间移动时，鞭毛旋转）在很大程度上是不变的，但是由于与不同宿主组织的相互作用的差异，其运动策略是实质上不同的。这种推理表明，形状;物理参数，如鞭毛和细胞柱的刚度;和内部机制驱动运动已经进化到允许在这些不同的环境中定向迁移。因此，本研究将首先通过实验测试PI开发的描述B形状和运动性的数学模型的预测。burgdorferi使用驱虫处理的细胞和遗传操作来改变细胞壁和鞭毛的硬度。其次是B的能动性。将在明胶基质中检查burgdorferi，以便通过模拟ECM的可控模型系统来量化运动性。最后，建模和延时荧光显微镜将被用来确定上皮细胞层的运动机制，并在蜱和小鼠。这些目标是针对移动目前的理解运动在非生理液体和/或甲基纤维素的解决方案，以生物现实的环境中，螺旋体粘附到细胞或ECM，以完成其地方病周期，并完成其寄生策略。 公共卫生相关性：本提案中描述的研究将确定莱姆病中发生的传播和入侵宿主的生物物理机制。具体而言，莱姆病进展过程中的病原体-宿主相互作用的定量模型将被开发和实验测试，这将提供对感染过程的详细了解，并可能导致新的治疗方法。

DESCRIPTION (provided by applicant): which is caused by the spirochete Borrelia burgdorferi, is the most common tick-transmitted illness in the United States. If untreated, Lyme disease can lead to a wide array of complications typically involving the heart, joints, or nervous system. It is widely believed that the motility of B. burgdorferi is essential for the pathogenesis of Lyme disease. B. burgdorferi swims by rotating helical filaments (flagella) that reside in the periplasmic space (the space between the outer membrane and the cell wall material). The rotation of these periplasmic flagella against the cell wall leads to deformations of the cell cylinder, and these deformations exert force against the external environment. The bacterium transitions between the arthropod vector (Ixodid ticks) and mammalian host. This enzootic cycle requires the bacterium to interact with extremely different environments. For example, spirochetes must be able to colonize the tick midgut, and then migrate out of the midgut into the hemocoel. Once in the hemocoel, the bacterium must navigate towards the salivary glands, attach to the acinar surface, penetrate the basal lamina, and enter the salivary ducts. B. burgdorferi is then inoculated into the skin of its mammalian host where it must translocate through the extracellular matrix in order to access small vessels which provide portals for dissemination through the blood. To invade joints and other host tissue, the cells must adhere to the endothelium of blood vessels in target organs and penetrate through them. The unique motility and morphology of B. burgdorferi are presumed to drive many of these processes and are, therefore, considered to be major factors in the pathogenesis of Lyme disease. The principal hypothesis of this proposal is that the internal mechanism driving the motility of B. burgdorferi (i.e., flagellar rotation) is largely unchanged when the spirochete moves between the tick and the mammalian host, but its strategy for motility is substantially different due to differences in the interactions with the different host tissues. This reasoning suggests that the shape; physical parameters, such as the stiffness of the flagella and cell cylinder; and the internal mechanism driving motility have evolved to allow for directed migration in these diverse environments. Therefore, this research will first experimentally test the predictions of a mathematical model developed by the PI that describes the shape and motility of B. burgdorferi using antibiotic-treated cells and genetic manipulations to alter the stiffnesses of the cell wall and flagella. Next, the motility of B. burgdorferi will be examined in gelatin matrices, in order to quantify motility through a controllable model system that mimics the ECM. Finally, modeling and time-lapse fluorescence microscopy will be used to determine the mechanisms of motility in epithelial cell layers, and in the tick and mouse. These aims are directed toward moving the current understanding of motility in non-physiological liquid and/or methycellulose solutions to biologically realistic environments in which spirochetes adhere to cells or ECM in order to complete their enzootic cycle and accomplish their parasitic strategy. PUBLIC HEALTH RELEVANCE: The research described in this proposal will determine the biophysical mechanisms that are involved in the transmission to and invasion of the host that occurs in Lyme disease. Specifically, a quantitative model of the pathogen-host interactions during the progression of Lyme disease will be developed and experimentally tested, which will provide a detailed understanding of the infection process and may lead to novel therapeutic methods.