BRONCHIOLAR CLARA CELLS: A ROLE IN TYPE 2 CELL FUNCTION

肺的无纤毛细支气管上皮(Clara)细胞仍然是一种 谜团，特别是关于它在小动物中的生物学作用 呼吸道和近端肺泡。辨认她·克拉拉的主要障碍 细胞的功能活动是在获得 大量的这些细胞用于研究。为了努力开发一种 这个问题领域的独特方法，我们最近建立了一个小鼠 本实验室建立的肺腺瘤模型--经胎盘暴露所致 到N，乙基亚硝脲。通过适当的操作，我们已经能够 产生肺部良性肿瘤，主要由Clara细胞组成 起源。我们的初步形态研究已经证实了结构 这些细胞的特征是小鼠Clara细胞的特征。 在我们最初的调查中，我们观察到了不寻常的 在Clara细胞瘤附近的2型细胞。这些 异常的2型细胞积聚大量的表面活性物质 胞质液泡中的磷脂物质。这些看起来是直接的 与Clara细胞肿瘤的年龄和大小有关--年龄和体积越大 肿瘤变大，每细胞和总包裹体范围越广 涉及的类型2单元格的数量。 这项提案中概述的研究旨在检验这一假设 细支气管克拉拉细胞与之有明确的功能相互作用 肺泡上皮细胞；具体地说，2型细胞的调节 通过Clara细胞生产的产品合成/分泌表面活性物质。 克拉拉细胞生物学的主要领域将被研究。第一个涉及到 细胞的分离、纯化及功能鉴定 从我们的肿瘤模型中获得。这些单元格将在 生物化学特性，如混合功能氧化酶的隔离状态 脂类降解活性(磷脂酶)，化学物质 它们分泌颗粒的组成及其部分成分的鉴定 调节这些分泌物的合成和释放的因素。 第二种方法将尝试开发最佳条件，以便 将分离的Clara细胞保存在培养皿中。然后建立共同文化 新分离的大鼠肺2型细胞与Clara细胞的比较，A549人 肺细胞系，如有必要，病毒转化的大鼠肺2型细胞 为了重现我们观察到的第二类细胞效应 活着。小鼠肺Clara细胞腺瘤模型的应用 检验提出的假设的独特方法。

The nonciliated bronchiolar epithelial (Clara) cell of the lung remains an enigma, particularly with respect to its biological role in the small airway and proximal alveoli. A major barrier to identifying tha Clara cell's functional activity is the great difficulty encountered in obtaining significant quantities of these cells for study. In an effort to develop a unique approach to this problem area, we have recently established a murine lung adenoma model in our laboratory -- induced by transplacental exposure to N,ethylnitrosourea. With appropriate manipulation, we have been able to produce benign tumors of the lung that are primarily of Clara cells origin. Our preliminary morphologic studies have confirmed the structural characteristics of thse cells as being those of the murine Clara cell. During our initial investigations, we observed the development of unusual Type 2 cells in the immediate vicinity of Clara cell tumors. These abnormal Type 2 cell accumulate abundant quantities of surfactant-like phospholipid material in cytoplasmic vacuoles. These appear to be directly related to the age and size of the Clara cell tumor -- the older and larger the tumor becames, the more extensive the inclusions per cell and total number of Type 2 cells involved. The studies outlined in this proposal are designed to test the hypothesis that the bronchiolar Clara cell has a defined functional interaction with alveolar epithelial cells; specifically, the modulation of Type 2 cell surfactant synthesis/secretion via a product produced by Clara cells. The major areas of Clara cell biology will be examined. The first involves the isolation, purification and functional characterization of cells obtained from our tumor model. These cells will be examined in the isolated state for biocemical features such as mixed-function oxidase activity, lipid degrading activity (phospholipases), the chemical compositions of their secretory granules and identification of some of the factors regulating synthesis and release of these secretions. The second approach will attempt to develop optimum conditions for maintaining isolated Clara cells in cutlure. Then to establish co-cultures of Clara cells with freshly isolated rat lung Type 2 cells, the A549 human lung cell line, and if necessary, virus transformed rat lung Type 2 cells in an effort to reproduce the Type 2 cell effects we have observed in vivo. The application of the mouse lung Clara cell adenoma model is a unique approach to testing the proposed hypothesis.