EPITHELIAL CELL/MACROPHAGE INTERACTIONS IN LUNG FIBROSIS

肺纤维化是对一组不同类型的 承认和不承认的侮辱。两项组织学研究都来自 肺纤维化患者与纤维化肺的动物研究 疾病已经证明，无法重新建立正常的 当正常愈合时，上皮细胞预示着进展为纤维化 上皮细胞的数量预示着恢复而不会出现纤维化。我们假定 肺泡上皮细胞(AEC)参与相互的、局部的 与肺巨噬细胞的调节相互作用以防御 肺泡上皮层的完整性。我们的初步数据 证实粒细胞-巨噬细胞集落的AEC生成受损 刺激因子(GM-CSF)在功能障碍中起关键作用 上皮细胞再生与纤维化的发展。中环 这一应用的假设是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 导致巨噬细胞介质的表达，如肝细胞 生长因子(HGF)，保护正常的肺泡结构。当AEC 在炎症环境中GM-CSF表达受损， 肺泡微环境改变，HGF和纤溶 活跃度降低，导致肺纤维化， 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。在此基础上 假设，我们设计了研究来实现5个目标：1)比较 正常人和博莱霉素对AEC产生GM-CSF的调节作用 体外损伤大鼠。我们将确定GM-CSF受损的时间进程 炎症反应中GM-CSF的表达及比较 从博莱霉素处理的动物到对照的II型细胞中的激动剂。2) 探讨GM-CSF表达下调的分子机制 博莱霉素处理的动物的II型细胞。实验将确定 博莱霉素暴露后GM-CSF mRNA的表达是否受损 GM-CSF转录和/或mRNA稳定性改变的后果。3)至 明确GM-CSF在巨噬细胞活性调节中的作用 从正常和博莱霉素处理的动物的肺中分离出来。 将进行实验，以检验GM-CSF单独 或与其他细胞因子结合，产生和维持肺泡 和/或间质巨噬细胞表达HGF、IL-1β和uPA，a 有益于肺修复的系列产品。4)确定 肝细胞生长因子对正常和博莱霉素诱导的II型血管内皮细胞的影响 动物。将进行实验以检验肝细胞生长因子的能力 对II型细胞增殖和uPA表达的影响 对博莱霉素的反应过程。5)确定致病作用 巨噬细胞集落刺激因子在肝纤维化中的作用及治疗价值 回应。体内调节GM-CSF活性对人脐静脉内皮细胞生长的影响 纤维化反应将使用中和抗体来确定 阻断和基因转移增强GM-CSF在AEC中的表达。 了解上皮细胞-巨噬细胞的相互作用将提供 对纤维性和非纤维性修复需要的必要见解 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.