Horinouchi H, Wang C C, Shepherd K E, Jones R
Department of Anesthesia, Molecular and Cell Biology Laboratory, Massachusetts General Hospital, Boston 02129, USA.
Am J Respir Cell Mol Biol. 1996 Jun;14(6):548-55. doi: 10.1165/ajrcmb.14.6.8652183.
Alveolar-capillary membrane remodeling, including microvessel wall thickening and interstitial fibrosis, is a well-known sequela of cell proliferation in the hyperoxia-injured lung. The array of growth molecules released locally that potentially mediate this response, and their cell(s) of origin, are currently being defined. To elucidate the role of tumor necrosis factor alpha (TNF alpha), an effector molecule of cell injury and proliferation, and the role of the alveolar macrophage (AM) as its source during the acute (1 to 24 h) and chronic stages (3 to 28 days) of hyperoxia-induced injury, we have analyzed gene and protein expression in cells recovered from rat lung by bronchoalveolar lavage. In the hyperoxic lung, cell number was similar to that in normal lung (1 x 10(6)) except on day 7, when it was higher (5 x 10(6)). Virtually all cells recovered from the normal and hyperoxic lung were AMs, with the exception that on days 3 and 7 of hyperoxia these cells represented 69% and 55% of the population, respectively, and polymorphonuclear leukocytes and lymphocytes the remainder. Probe specificity was confirmed by detection of TNF alpha RNA (1.6 kb) from lung cells recovered after lipopolysaccharide (LPS) treatment (positive control) and from the hyperoxic lung (at day 3), with an extremely low level of constitutive expression detected in cells from normal lung. In cytospin preparations, TNF alpha mRNA transcripts were detected in few AMs recovered from normal lung and in most AMs after LPS treatment. In the hyperoxic lung, a signal was detected at 3 h, when approximately 25% of the population was positive. The number of hybridizing cells then increased, being highest on day 7 (day 1 approximately 30%, day 3 approximately 58%, day 7 approximately 90%, day 28 approximately 65%). No expression of TNF alpha protein was detected in AMs from normal lung; positive cells were detected in the hyperoxic lung from day 1 and thereafter. We conclude from upregulation of the TNF alpha gene in a significant number of cells, and from the increase in the number expressing biologically active protein, that AMs are an important source of this molecule both in the acute and chronic stages of hyperoxic lung injury. It is anticipated that an increased understanding of the cellular sources of mediators effecting vascular and alveolar wall remodeling in vivo will contribute to the development of strategies to inhibit the response.
肺泡 - 毛细血管膜重塑,包括微血管壁增厚和间质纤维化,是高氧损伤肺中细胞增殖的一个众所周知的后遗症。目前正在确定局部释放的一系列可能介导这种反应的生长分子及其细胞来源。为了阐明肿瘤坏死因子α(TNFα)(一种细胞损伤和增殖的效应分子)的作用,以及肺泡巨噬细胞(AM)作为其来源在高氧诱导损伤的急性期(1至24小时)和慢性期(3至28天)的作用,我们分析了通过支气管肺泡灌洗从大鼠肺中回收的细胞中的基因和蛋白质表达。在高氧肺中,细胞数量与正常肺中的细胞数量相似(1×10⁶),但在第7天时较高(5×10⁶)。从正常肺和高氧肺中回收的几乎所有细胞都是肺泡巨噬细胞,不同的是在高氧的第3天和第7天,这些细胞分别占细胞总数的69%和55%,其余为多形核白细胞和淋巴细胞。通过检测脂多糖(LPS)处理后(阳性对照)从肺细胞中回收的以及高氧肺(第3天)中的TNFα RNA(1.6 kb),证实了探针的特异性,在正常肺细胞中检测到极低水平的组成型表达。在细胞涂片制备中,在从正常肺中回收的少数肺泡巨噬细胞以及LPS处理后的大多数肺泡巨噬细胞中检测到TNFα mRNA转录本。在高氧肺中,在3小时时检测到信号,此时约25%的细胞呈阳性。随后杂交细胞的数量增加,在第7天达到最高(第1天约30%,第3天约58%,第7天约90%,第28天约65%)。在正常肺的肺泡巨噬细胞中未检测到TNFα蛋白的表达;在高氧肺中从第1天起及之后检测到阳性细胞。我们从大量细胞中TNFα基因的上调以及表达生物活性蛋白的细胞数量增加得出结论,肺泡巨噬细胞在高氧肺损伤的急性期和慢性期都是该分子的重要来源。预计对体内影响血管和肺泡壁重塑的介质的细胞来源的进一步了解将有助于制定抑制该反应的策略。