ALVEOLAR MACROPHAGE PHI REGULATION AND CELL FUNCTION

肺泡巨噬细胞 PHI 调节和细胞功能

• 批准号: 6199082
• 负责人: AKHIL BIDANI
• 金额: $ 32.3万
• 依托单位: UNIVERSITY OF TEXAS MED BR GALVESTON
• 依托单位国家: 美国
• 财政年份: 1995
• 资助国家: 美国
• 起止时间: 1995-08-01 至 2004-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6199082
• 关键词: acid base balance; acidity /alkalinity; adenosinetriphosphatase; alveolar macrophages; biophysics; cell membrane; cell morphology; enzyme activity; homeostasis; intracellular transport; laboratory rabbit; leukocyte activation /transformation; mathematical model; membrane potentials; membrane transport proteins; oxidizing agents; phagocytosis; superoxides

Alveolar macrophages (mphi) are a crucial element of the host defense response. Nonetheless, the factors that modulate and regulate their effector functions (e.g., scavenger and secretion activities) are unclear. Our current studies show that the functions of alveolar (mphi) are selectively pH-sensitive. As such, alterations in intracellular pH (pHi) due to endogenous (e.g., increased cellular metabolism during mphi activation) or exogenous factors (e.g., pathologic changes in mphi microenvironment) can have profound effects on mphi competence. Mphi pHi is determined by the balance between processes that generate intracellular acid-base equivalents and membrane transporters that regulate the efflux of such equivalents. We have identified the major acid-base transporters in alveolar mphi: electrogenic plasmalemma V-type H+-ATPase and electroneutral exchangers (Na+/H+ and C1-/HCO3 ). These transporters link the regulation of mphi pHi, cell volume, and Em. We hypothesize that (1) in resting (unstimulated) mphi pHi and volume are both tightly regulated although with different kinetics, (2) in activated mphi pHi regulation takes precedence over volume regulation such that pHi (and pH-sensitive cell functions) are preserved at the expense of volume homeostasis, and (3) this hierarchy in housekeeping functions has important consequences for mphi activation. Previous efforts to kinetically characterize acid-base transporters have used measurements of pHi recovery from challenges induced with weak base/acid prepulses. Our studies show that this approach leads to erroneous estimates of transport kinetics, with potential errors in data interpretation. We will use tightly-coupled mathematical and experimental studies (incorporating pHi, volume, Em, and plasmalemma ion conductances/fluxes) to overcome this limitation. To test our hypotheses, we propose coupled mathematical/experimental studies to quantify the hierarchy and kinetics of pHi/volume regulation in alveolar mphi (resting or activated) and monocytes, and to determine the interaction of mphi pHi/volume regulation and oxidant production (NO, superoxide, and peroxynitrite). Our findings should provide new fundamental insights into the mechanisms that modulate alveolar mphi functions in health and disease.

肺泡巨噬细胞 (mphi) 是宿主防御反应的关键要素。 尽管如此，调节和调控其效应功能（例如清除剂和分泌活性）的因素尚不清楚。 我们目前的研究表明，肺泡 (mphi) 的功能选择性地对 pH 值敏感。 因此，内源性（例如，mphi 激活过程中细胞代谢增加）或外源性因素（例如，mphi 微环境的病理变化）引起的细胞内 pH (pHi) 的变化可能对 mphi 能力产生深远的影响。 Mphi pHi 由生成细胞内酸碱当量的过程与调节此类当量流出的膜转运蛋白之间的平衡决定。 我们已经确定了肺泡 mphi 中的主要酸碱转运蛋白：生电质膜 V 型 H+-ATP 酶和电中性交换器（Na+/H+ 和 C1-/HCO3）。 这些转运蛋白将 mphi、pHi、细胞体积和 Em 的调节联系起来。 我们假设 (1) 在静息（未刺激）mphi 中，尽管动力学不同，pHi 和体积均受到严格调节，(2) 在激活的 mphi 中，pHi 调节优先于体积调节，从而保留 pHi（和 pH 敏感细胞功能）以牺牲体积稳态为代价，(3) 这种管家功能的层次结构对 mphi 激活具有重要影响。 以前对酸碱转运蛋白进行动力学表征的努力已经使用了弱碱/酸预脉冲引起的挑战中 pHi 恢复的测量。 我们的研究表明，这种方法会导致传输动力学的错误估计，并可能导致数据解释错误。 我们将使用紧密耦合的数学和实验研究（结合 pHi、体积、Em 和质膜离子电导/通量）来克服这一限制。为了检验我们的假设，我们建议进行数学/实验耦合研究，以量化肺泡 mphi（静息或激活）和单核细胞中 pHi/体积调节的层次结构和动力学，并确定 mphi pHi/体积调节与氧化剂产生（NO 、超氧化物和过氧亚硝酸盐）。 我们的研究结果应该为健康和疾病中调节肺泡 mphi 功能的机制提供新的基本见解。