Impact of Lipids On Intestinal Mucus Transport And Structural Properties

描述（由申请方提供）：本项目的总体目标是阐明胃肠道（GI）中脂质和食物相关理化变化对肠粘液屏障特性的影响。这一信息将激发粘膜屏障控制的策略，使有效的药物载体系统（如粘膜疫苗），增强营养，并可能抑制病原体入侵。胃肠道粘液是一种天然水凝胶，其提供精细调节和惊人的选择性屏障，保护下层上皮免受肠腔中苛刻的物理化学变化（例如，胆盐浓度升高、pH降低），选择性抑制微生物转运，并使有效的胃肠道粘膜保护成为可能。 吸收养分和水分。尽管粘液在健康和疾病中的作用和潜在影响的重要性，但其屏障特性相对知之甚少。初步数据表明，肠粘液特性受食物相关脂质和食物相关理化变化（即pH值和[Ca+2 ]的变化）的显著调节。为了研究这些现象，并使策略的设计，利用它们的治疗目的，微粒，模型微生物和小分子量化合物的运输将使用多粒子跟踪技术和电子顺磁共振（EPR）的新应用进行分析。在不同pH和Ca+2浓度下，将颗粒、微生物和化合物暴露于含有食物相关脂质以及模型禁食状态肠道缓冲液的培养基中的粘液表面。这些分析将在天然粘液以及纯化的粘蛋白凝胶上进行，以提供对响应特定食物相关刺激的粘液结构组分的深入了解。平行进行的微观和宏观流变学分析将表明粘液凝胶结构变化与观察到的运输现象中颗粒/分子和凝胶成分之间发生的相互作用的相对重要性。还将使用先进的显微镜技术，包括速冻深蚀刻显微镜（QF/DEM），检查与暴露于食物相关脂质和理化环境变化相关的粘液凝胶结构变化。将使用EPR和氮氧自由基探针标记的胆汁盐和脂质检查粘液层内由食物相关脂质形成的胶体结构的完整性，因为目前尚不清楚这些结构是否在粘液内保持完整，这可能会显著影响通过这种天然水凝胶的运输性质。跨学科研究团队拥有成功理解并开始利用脂质对GI粘液屏障的影响所需的专业知识，包括PI，一位具有药物输送和粘液中运输现象专业知识的化学工程师，一位具有通过粘液和粘液神学进行病原体运输专业知识的生物化学家，一位具有生物基质结构高级显微镜分析专业知识的机械工程师，以及一位在膜中小分子迁移率的电子顺磁共振分析方面具有专长的化学家。

DESCRIPTION (provided by applicant): The overall goal of this project is to elucidate the impact of lipids and food-associated physicochemical changes in the gastrointestinal (GI) tract on intestinal mucus barrier properties. This information will motivate strategies for mucosal barrier control, enabling efficient drug carrier systems (e.g. mucosal vaccines), enhanced nutrition, and potentially inhibited pathogen invasion. Gastrointestinal mucus is a natural hydrogel providing a finely-tuned and amazingly selective barrier, protecting the underlying epithelium from harsh physicochemical changes in the intestinal lumen (e.g. elevations in bile salt concentration, lowered pH), selectively inhibiting microbial transport, and enabling efficient absorption of nutrients and water. Despite the significance of mucus's role and potential implications in health and disease, its barrier properties are relatively poorly understood. Preliminary data indicates that intestinal mucus properties are significantly modulated by food-associated lipids and physicochemical changes associated with food (i.e. changes in pH and [Ca+2 ]). To study these phenomena and enable design of strategies to exploit them for therapeutic purposes, the transport of micro-particulates, model microbes and small molecular weight compounds will be analyzed using multiple particle tracking techniques and a novel application of electron paramagnetic resonance (EPR). Particles, microbes and compounds will be exposed to mucus surfaces in media containing food-associated lipids as well as model fasted state intestinal buffer, at varied pH and Ca+2 concentrations. These analyses will be performed on both native mucus as well as purified mucin gels to provide insight into mucus structural components responding to specific food-associated stimuli. Micro- and macro-rheological analyses performed in parallel will indicate the relative significance of mucus gel structural changes vs. interactions occurring between particles/molecules and gel constituents in observed transport phenomena. Structural changes in mucus gels associated with exposure to food-associated lipids and physicochemical environmental changes will also be examined using advanced microscopic techniques, including quick-freeze deep etch microscopy (QF/DEM). The integrity of colloidal structures formed by food-associated lipids within the mucus layer will be examined using EPR and nitroxide-probe labeled bile salts and lipids, as it is currently not understood whether these structures stay intact within mucus, which could significantly impact the nature of transport through this natural hydrogel. The interdisciplinary research team possesses the expertise required to successfully understand and begin to exploit the impact of lipids on the GI mucus barrier, including the PI, a chemical engineer with expertise in transport phenomena in drug delivery and mucus, a biochemist with expertise in pathogen transport through mucus and mucus theology, a mechanical engineer with expertise in advanced microscopic analysis of biological matrix structure, and a chemist with expertise in electron paramagnetic resonance analysis of small molecule mobility in membranes.