EOSINOPHILS, APOPTOSIS, AND ASTHMA

嗜酸性粒细胞、细胞凋亡和哮喘

• 批准号: 6612399
• 负责人: DONNA L BRATTON
• 金额: $ 24.21万
• 依托单位: NATIONAL JEWISH HEALTH
• 依托单位国家: 美国
• 财政年份: 2002
• 资助国家: 美国
• 起止时间: 2002-07-01 至 2003-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6612399
• 关键词: apoptosis; asthma; biological signal transduction; blood tests; cell growth regulation; cell population study; chemical structure function; clinical research; confocal scanning microscopy; cytoprotection; diagnostic respiratory lavage; drug resistance; eosinophil; flow cytometry; gene expression; glucocorticoids; human subject; immunoregulation; laboratory mouse; mitochondria; neutrophil; nuclear factor kappa beta; oxidation reduction reaction; oxidizing agents; pathologic process; superoxide dismutase

Eosinophils are the most abundant and injurious of the effector cells of asthma where there is evidence for their enhanced differentiation and release from bone marrow; recruitment, activation and prolonged survival. It is hypothesized that eosinophil longevity in the asthmatic airway contributes to eosinophil accumulation and capacity to damage the asthmatic airway via production of inflammatory mediators, cytokines, reactive oxygen species, and most importantly, the eosinophilic cationic proteins which lead to the airway hyperreactivity Resolution of asthmatic eosinophilic inflammation requires eosinophil apoptosis and removal, and it is the objective of this proposal to determine the mechanisms by which apoptosis occurs. Apoptotic eosinophils are seen more often in the asthmatic airway lumen than tissue, and it is the objective of this proposal to determine the mechanisms by which apoptosis occurs. Apoptotic eosinophils are seen more often in the asthmatic airway lumen than tissue, and it is hypothesized that this can be explained by three factors: loss of pro- survival cytokine stimulation in the airway lumen; the presence of pro- apoptotic factors at this site; and inefficient clearance by phagocytes in the airway lumen, relative to tissue. While the importance of pro- survival signaling by the HSFs has been investigated, little is known of integrated signaling from the interplay or "mix" of pro-survival (HSFs, integrins, chemotactic factors) and pro-apoptotic signaling (Fas, TNF- alpha, oxidant generation, corticosteroids), which are expected to occur in vivo. From preliminary data, it is hypothesized that constitutive apoptosis is driven by oxidant production from mitochondria, and that responses to "mixed" signaling are determined by oxidant generation, mitochondrial protection by MnSOD, and autocrine production of survival factors. Furthermore, while signaling via NFkappaB, Akt and ERK are thought to be redundant in HSF pro-survival signaling, it is hypothesized that these pathways become critical for survival during "mixed" signaling . These pathways are also expected to determine eosinophil response during corticosteroid treatment where inhibition of NFkappaB results in loss of MnSOD protection of mitochondria, apoptosis and rapid secondary cytolysis (with release of cationic proteins to the tissues). Conversely, pro-apoptosis and rapid secondary cytolysis (with release of cationic proteins to the tissues). Conversely, pro-survival signaling leads to MnSOD expression and mitochondrial protection which results in eosinophil insensitivity to corticosteroids. These hypothesis will be investigated both in vitro in isolated eosinophils, and in vivo using the murine allergen challenge model of airway hyperreactivity and in human allergic asthma. Findings are expected to broaden our understanding of eosinophil longevity and offer new insights into potential therapeutic targets.

嗜酸性粒细胞是最丰富和最有害的哮喘效应细胞，其中有证据表明其增强的分化和从骨髓中释放;募集，活化和延长存活。假设嗜酸性粒细胞在哮喘气道中的寿命有助于嗜酸性粒细胞的积累和通过产生炎性介质、细胞因子、活性氧物质以及最重要的是导致气道高反应性的嗜酸性阳离子蛋白来损害哮喘气道的能力。哮喘嗜酸性粒细胞炎症的解决需要嗜酸性粒细胞凋亡和去除，并且该建议的目的是确定细胞凋亡发生的机制。凋亡的嗜酸性粒细胞在哮喘气道腔中比在组织中更常见，本研究的目的是确定凋亡发生的机制。凋亡的嗜酸性粒细胞在哮喘气道腔中比在组织中更常见，并且假设这可以由三个因素解释：气道腔中促存活细胞因子刺激的丧失;在该部位存在促凋亡因子;以及相对于组织，气道腔中吞噬细胞的清除效率低下.虽然已经研究了HSF促存活信号传导的重要性，但是对于来自促存活（HSF、整联蛋白、趋化因子）和促凋亡信号传导（Fas、TNF-α、氧化剂生成、皮质类固醇）的相互作用或“混合”的整合信号传导知之甚少，预期其在体内发生。从初步的数据，它是假设，组成性细胞凋亡是由线粒体的氧化剂生产，并确定了“混合”信号的响应由氧化剂的产生，线粒体保护MnSOD，和自分泌生产的生存因子。此外，虽然认为经由NF κ B、Akt和ERK的信号传导在HSF促存活信号传导中是冗余的，但假设这些途径在“混合”信号传导期间对于存活变得至关重要。预期这些途径还可确定皮质类固醇治疗期间的嗜酸性粒细胞反应，其中NF κ B的抑制导致线粒体MnSOD保护的丧失、细胞凋亡和快速继发性细胞溶解（伴随阳离子蛋白质向组织的释放）。相反，促细胞凋亡和快速继发性细胞溶解（释放阳离子蛋白到组织）。相反，促存活信号传导导致MnSOD表达和线粒体保护，这导致嗜酸性粒细胞对皮质类固醇不敏感。这些假设将在分离的嗜酸性粒细胞中进行体外研究，并在体内使用气道高反应性的鼠变应原激发模型和人过敏性哮喘中进行研究。研究结果有望拓宽我们对嗜酸性粒细胞寿命的理解，并为潜在的治疗靶点提供新的见解。