EPITHELIAL CELL/MACROPHAGE INTERACTIONS IN LUNG FIBROSIS

肺纤维化是一种病理反应， 承认和不承认的侮辱。两项组织学研究 肺纤维化患者和纤维化肺的动物研究 疾病已经证明，无法重建正常的 上皮细胞是纤维化进展的预测因子，而正常愈合 预测恢复无纤维化。我们推测 肺泡上皮细胞（AEC）参与相互的，局部的 调节与肺巨噬细胞的相互作用，以保护 肺泡上皮层的完整性。我们的初步数据 证明粒细胞-巨噬细胞集落的AEC产生受损 刺激因子（GM-CSF）在功能失调的 上皮细胞再生和纤维化的发展。中央 本申请假设AEC和巨噬细胞参与 在双向旁分泌相互作用中，AEC衍生的GM-CSF 导致巨噬细胞介体的表达，如肝细胞 生长因子（HGF），其保持正常肺泡结构。当AEC 在炎症情况下，GM-CSF的表达受损， 肺泡微环境发生改变， 活动减少，结果是肺纤维化， 而不是正常的修复。这些假设将在一个 博莱霉素诱导的大鼠肺纤维化模型。基于此 假设，我们设计了研究，以实现5个目标：1）比较 GM-CSF在正常和博来霉素诱导的AEC中的调节和产生， 体外损伤大鼠。我们将确定受损的GM-CSF的时间进程， 表达，并比较GM-CSF表达对炎症反应的反应。 在II型细胞中，博来霉素处理的动物与对照相比，（二） 为了确定GM-CSF表达减少的分子机制， 来自博来霉素处理的动物的II型细胞。实验将确定 博来霉素暴露后GM-CSF mRNA表达受损是否是一种 这是GM-CSF转录和/或mRNA稳定性改变的结果。3)到 明确GM-CSF在巨噬细胞活性调节中的作用 分离自正常和博来霉素处理的动物的肺。 将进行实验以检验GM-CSF单独 或与其他细胞因子结合，产生并维持肺泡 和/或表达HGF、IL-1 β和uPA的间质巨噬细胞， 有利于肺修复的系列产品。4)确定 肝细胞生长因子对正常人和博来霉素治疗后Ⅱ型血管内皮细胞影响 动物将进行实验以检查HGF的能力， 影响II型细胞增殖和uPA表达 对博来霉素的反应过程。5)为了确定致病作用， 和涉及GM-CSF的网络在纤维化中的治疗益处 反应在体内调节GM-CSF活性对细胞凋亡的影响 纤维化反应将使用中和抗体来确定， 阻断和基因转移以增强AEC表达GM-CSF。 了解上皮细胞-巨噬细胞的相互作用将提供 对纤维化和非纤维化修复的必要见解， 针对上皮细胞或肺巨噬细胞的新疗法。

Pulmonary fibrosis is a pathological response to a diverse group of recognized and unrecognized insults. Both histologic studies from patients with pulmonary fibrosis and animal studies of fibrotic lung disease have demonstrated that the inability to re-establish a normal epithelium is predictive of progression to fibrosis, while normal healing of epithelial cells predicts recovery without fibrosis. We postulate that alveolar epithelial cells (AEC) participate in reciprocal, local regulatory interactions with pulmonary macrophages to defend the integrity of the alveolar epithelial layer. Our preliminary data demonstrate that impaired AEC production of granulocyte-macrophage colony stimulating factor (GM-CSF) plays a crucial role in dysfunctional epithelial cell regeneration and the development of fibrosis. The central hypothesis of this application is that AEC and macrophages participate in a bi-directional paracrine interaction, in which AEC-derived GM-CSF leads to the expression of macrophage mediators, such as hepatocyte growth factor (HGF), that preserve normal alveolar architecture. When AEC expression of GM-CSF is impaired in the setting of inflammation, the alveolar microenvironment is altered so that HGF and fibrinolytic activity are diminished, with pulmonary fibrosis as the consequence, rather than normal repair. These hypotheses will be tested in a bleomycin-induced rat model of pulmonary fibrosis. Based on this hypothesis, we have designed studies to accomplish 5 goals: 1) To compare the regulation and production of GM-CSF in AEC from normal and bleomycin- injured rats in vitro. We will define the time course of impaired GM-CSF expression and compare GM-CSF expression in response to inflammatory agonists in type II cells from bleomycin-treated animals to controls. 2) To determine the molecular mechanisms of diminished GM-CSF expression by type II cells from bleomycin treated animals. Experiments will determine whether impaired GM-CSF mRNA expression after bleomycin exposure is a consequence of altered GM-CSF transcription and/or mRNA stability. 3) To define the role of GM-CSF in the regulation of activity of macrophages isolated from the lungs of normal and bleomycin-treated animals. Experiments will be performed to test the hypothesis that GM-CSF, alone or in conjunction with other cytokines, produces and maintains alveolar and/or interstitial macrophages that express HGF, IL-1beta, and uPA, a series of products beneficial to lung repair. 4) To determine the influence of HGF on type II AEC from both normal and bleomycin-treated animals. Experiments will be performed to examine the ability of HGF to influence type II cell proliferation and uPA expression during the time course of response to bleomycin. 5) To determine the pathogenetic role and therapeutic benefit of networks involving GM-CSF in the fibrotic response. The effects of modulation of GM-CSF activity in vivo on the fibrotic response will be determined using neutralizing antibodies to block and gene transfer to enhance AEC expression of GM-CSF. Understanding epithelial cell-macrophage interactions will provide the necessary insights into fibrotic and non-fibrotic repair required for novel therapies directed at epithelial cells or pulmonary macrophages.