ALVEOLAR MACROPHAGE PHI REGULATION AND CELL FUNCTION

肺泡巨噬细胞 PHI 调节和细胞功能

基本信息

批准号：
6043813
负责人：
AKHIL BIDANI
金额：
$ 25.58万
依托单位：
UNIVERSITY OF TEXAS MED BR GALVESTON
依托单位国家：
美国
项目类别：
财政年份：
1995
资助国家：
美国
起止时间：
1995-08-01 至 2000-07-31
项目状态：
已结题

项目摘要

Alveolar macrophages play a vital role in the inflammatory response to inhaled pathogens and particulates and, by that, are a crucial element of host defense. Further, they participate in antigen presentation and secrete biologically-active substances that modulate the growth and differentiation of lung cells and interact with other phagocytes. Despite the importance of alveolar macrophages in lung physiology and pathophysiology, there is limited knowledge of the factors that modulate and regulate their crucial effector functions (i.e., scavenger activity and secretory properties). Over the past decade, many studies have shown that intracellular pH (pHi) affects and is affected by cell functions. It is not surprising, therefore, that patterns of pHi regulation are cell- specific and "function-related". We recently identified a novel mechanism for pHi regulation in alveolar macrophages, namely, a plasmalemmal vacuolar-type H+-ATPase (V-ATPase) whose activity is allosterically activated with reductions in pHi. V-ATPase activity persists at low extracellular pH (pH0), where other mechanisms for pHi regulation (e.g., Na+-H+ exchange) may be limited. We postulate that the activity of plasmalemmal V-ATPase preserves pHi and, therefore, the ability of alveolar macrophages to maintain pHi-sensitive functions in regions of acidic pH0 (e.g., tumors and abscesses). The proposed research seeks insight into the links between macrophage effector functions and the activity of plasmalemmal acid-base transporters. Our strategy is to correlate selected markers of macrophage functional competence with the activity of plasmalemmal acid-base transporters. Studies will be conducted to characterize the biophysical determinants of specific acid- base transporters, as a function of pHi and pH0. Tightly coupled to these measurements, quantitative theoretical models of whole cell PHi regulation will be used to characterize the kinetic properties of the constituent acid-base transporters. Hypothesis-driven studies then will be conducted to define the mechanisms underlying the responses of individual acid-base transporters to selected exogenous agonists, namely endotoxin and phorbol esters. Concurrently, the pHi/pH0-sensitivity of selected effector functions (phagocytosis, TNFalpha release, superoxide generation) will be determined using a variety of alternate methods to verify the specificity of the observed effects. These tightly-coupled measurements will clarify and quantify the relationships between pHi regulation and macrophage functional competence in resident alveolar macrophages. The results should provide important insights into the mechanisms that modulate alveolar macrophage functions in health and the derangements associated with pulmonary infections and acute lung injury.

肺泡巨噬细胞在炎症反应中起着至关重要的作用吸入的病原体和颗粒物，由此是关键元素主持人防御。此外，他们参加了抗原演示和分泌生物活性物质，调节生长和肺细胞的分化并与其他吞噬细胞相互作用。尽管肺泡巨噬细胞在肺部生理学和病理生理学，对调节因素的了解有限并调节其关键效应子功能（即清道夫活动和分泌属性）。在过去的十年中，许多研究表明细胞内pH（PHI）影响并受细胞功能的影响。它因此，毫不奇怪，PHI调节的模式是细胞 - 具体和“功能相关”。我们最近确定了一种新型机制对于肺泡巨噬细胞中的PHI调节，即浆膜液泡型H+-ATPase（V-ATPase）的活性在变构中通过减少PHI激活。 V-ATPase活性持续到低细胞外pH（PH0），其中其他用于PHI调控的机制（例如， NA+ -H+交换）可能受到限制。我们假设活动的活动血浆emalmal v-atpase保留了phi，因此，肺泡巨噬细胞在区域维持PHI敏感功能酸性PH0（例如肿瘤和脓肿）。拟议的研究寻求深入了解巨噬细胞效应器函数与血浆酸碱转运蛋白的活性。我们的策略是将巨噬细胞功能能力的选定标记与血浆酸碱转运蛋白的活性。研究将是进行的是表征特异性酸的生物物理决定因素基本转运蛋白，是PHI和PH0的函数。紧密耦合到这些测量，全细胞PHI调控的定量理论模型将用于表征成分的动力学特性酸碱转运蛋白。然后将进行假设驱动的研究定义单个酸碱反应的基础机制转运蛋白到选定的外源激动剂，即内毒素和凤凰酯。同时，选定效应器的PHI/PH0敏感性功能（吞噬作用，TNFalpha释放，超氧化物的产生）将是使用多种替代方法确定验证特异性观察到的效果。这些紧密耦合的测量将澄清并量化PHI调节与巨噬细胞之间的关系居民肺泡巨噬细胞的功能能力。结果应该提供对调节肺泡的机制的重要见解巨噬细胞在健康中起作用和与肺部感染和急性肺损伤。