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

不同环境下伯氏疏螺旋体形态和运动的生物物理学

• 批准号: 7986828
• 负责人: CHARLES W WOLGEMUTH
• 金额: $ 34.84万
• 依托单位: UNIVERSITY OF CONNECTICUT SCH OF MED/DNT
• 依托单位国家: 美国
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-05-01 至 2014-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7986828
• 关键词: Address; Adhesions; Affect; Antibiotics; Arthropod Vectors; Asses; Automobile Driving; Back; Bacteria; Basal lamina; Basement membrane; Behavior; Binding; Biological Assay; Biological Models; Biophysics; Black-legged Tick; Blood; Blood Vessels; Borrelia; Borrelia burgdorferi; Cell Shape; Cell Wall; Cells; Cellular Morphology; Collagen; Complex; Coupling; Dose; Endothelium; Environment; Epithelial Cells; Extracellular Matrix; Extracellular Matrix Proteins; Fibronectins; Filament; Flagella; Fluorescence Microscopy; Funding; Gel; Gelatin; Goals; Grant; Heart; Hemolymph; Homologous Gene; Image; Immigration; In Vitro; Infection; Invaded; Joints; Knock-out; Lead; Leptospiraceae; Liquid substance; Lyme Disease; Mammals; Measurement; Measures; Membrane; Methods; Methylcellulose; Microscopic; Microscopy; Microspheres; Midgut; Modeling; Molecular Conformation; Morphology; Mus; Mutation; Nervous system structure; Order Spirochaetales; Organ; Organism; Pathogenesis; Penetration; Penicillins; Peptidoglycan; Physical shape; Physics; Physiological; Point Mutation; Polymers; Process; Proteins; Relative (related person); Research; Role; Rotation; Salivary Glands; Salivary duct structure; Shapes; Skin; Solutions; Speed; Stretching; Surface; Swimming; Testing; Ticks; Tight Junctions; Time; Tissues; Translations; United States; United States National Institutes of Health; Vancomycin; Vascular Endothelium; Work; cell behavior; cell motility; crosslink; enzootic; genetic manipulation; mathematical model; monolayer; mutant; novel therapeutics; optical traps; pathogen; periplasm; physical process; public health relevance; research study; response; transmission process

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.

描述（由申请人提供）：由伯氏疏螺旋体螺旋体引起，是美国最常见的蜱传播疾病。如果不治疗，莱姆病会导致一系列并发症，通常涉及心脏、关节或神经系统。人们普遍认为，伯氏疏螺旋体的运动对于莱姆病的发病机制至关重要。伯氏疏螺旋体通过旋转位于周质空间（外膜和细胞壁材料之间的空间）中的螺旋丝（鞭毛）来游泳。这些周质鞭毛相对于细胞壁的旋转导致细胞圆柱体的变形，并且这些变形对外部环境施加力。该细菌在节肢动物载体（硬蜱）和哺乳动物宿主之间转换。这种地方性动物循环需要细菌与极其不同的环境相互作用。例如，螺旋体必须能够定植于蜱中肠，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，穿透基底层，并进入唾液管。然后，伯氏疏螺旋体被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才能进入小血管，这些小血管为通过血液传播提供了门户。为了侵入关节和其他宿主组织，细胞必须粘附在目标器官的血管内皮上并穿透它们。据推测，伯氏疏螺旋体独特的运动性和形态驱动了许多这些过程，因此被认为是莱姆病发病机制的主要因素。该提议的主要假设是，当螺旋体在蜱和哺乳动物宿主之间移动时，驱动伯氏疏螺旋体运动的内部机制（即鞭毛旋转）基本上没有变化，但由于差异，其运动策略有很大不同与不同宿主组织的相互作用。这个推理表明形状；物理参数，例如鞭毛和细胞柱的刚度；驱动运动的内部机制已经进化到可以在这些不同的环境中进行定向迁移。因此，这项研究将首先通过实验测试由 PI 开发的数学模型的预测，该模型描述了伯氏疏螺旋体的形状和运动性，使用抗生素处理的细胞和基因操作来改变细胞壁和鞭毛的硬度。接下来，将在明胶基质中检查伯氏疏螺旋体的运动性，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用于确定上皮细胞层以及蜱和小鼠的运动机制。这些目标旨在将当前对非生理液体和/或甲基纤维素溶液中运动性的理解转移到生物学真实环境中，在该环境中螺旋体粘附在细胞或ECM上，以完成其地方性动物循环并完成其寄生策略。 公共卫生相关性：本提案中描述的研究将确定莱姆病发生的传播和侵袭宿主所涉及的生物物理机制。具体来说，将开发莱姆病进展期间病原体与宿主相互作用的定量模型并进行实验测试，这将提供对感染过程的详细了解，并可能带来新的治疗方法。