Naureckas E T, Hershenson M B, Abe M K, Kelleher M D, Florio C, Heisler S I, Absher M, Evans J N, Samsel R W, Solway J
Department of Medicine, University of Chicago, Illinois 60637.
Am J Respir Cell Mol Biol. 1995 Mar;12(3):268-74. doi: 10.1165/ajrcmb.12.3.7873192.
We previously demonstrated that hyperoxia-exposed immature rats develop airway smooth muscle layer thickening; this remodeling appears partially attributable to smooth muscle hyperplasia. In this study, we tested the hypothesis that excess mitogenic activity for airway smooth muscle cells is present within the lungs of hyperoxia-exposed immature rats. We assessed the proliferative effect of bronchoalveolar lavage (BAL) fluid from air- and O2-exposed animals on cultured rat tracheal smooth muscle cells. BAL fluids from air- or O2-exposed immature rats increased DNA synthesis ([3H]-thymidine incorporation at 24 h of incubation) and cell number (compared with DMEM-treated control cells, at 2 days of incubation), but BAL fluid from O2-exposed animals had significantly greater mitogenic effects. This excess mitogenic activity was lipid inextractable and was ablated by trypsin digestion, indicating that at least one polypeptide growth factor was responsible; molecular sieve fractionation demonstrated a molecular weight of > 10 kD. Because platelet-derived growth factor (PDGF) has been identified in other models of hyperoxia exposure, we tested the further hypothesis that PDGF contributes to the observed excess mitogenic activity. Addition of neutralizing anti-PDGF antibodies to BAL-stimulated smooth muscle cultures did not reduce BAL fluid-induced mitogenesis. These data indicate that the lungs of O2-exposed rats contain excess mitogenic activity for airway smooth muscle, attributable to non-PDGF polypeptide growth factors. It is conceivable that this abnormal mitogenic activity contributes to O2-induced airway smooth muscle remodeling observed in immature rats in vivo.
我们先前证明，暴露于高氧环境的未成熟大鼠会出现气道平滑肌层增厚；这种重塑似乎部分归因于平滑肌增生。在本研究中，我们检验了以下假设：暴露于高氧环境的未成熟大鼠肺内存在针对气道平滑肌细胞的过度促有丝分裂活性。我们评估了来自空气暴露和氧气暴露动物的支气管肺泡灌洗（BAL）液对培养的大鼠气管平滑肌细胞的增殖作用。来自空气暴露或氧气暴露未成熟大鼠的BAL液增加了DNA合成（孵育24小时时的[3H] - 胸腺嘧啶核苷掺入量）和细胞数量（与DMEM处理的对照细胞相比，孵育2天时），但来自氧气暴露动物的BAL液具有明显更强的促有丝分裂作用。这种过度的促有丝分裂活性不可用脂质提取，并且可被胰蛋白酶消化消除，表明至少有一种多肽生长因子起作用；分子筛分级分离显示分子量> 10 kD。因为在其他高氧暴露模型中已鉴定出血小板衍生生长因子（PDGF），我们进一步检验了PDGF促成所观察到的过度促有丝分裂活性的假设。向BAL刺激的平滑肌培养物中添加中和抗PDGF抗体并未降低BAL液诱导的有丝分裂。这些数据表明，氧气暴露大鼠的肺内存在针对气道平滑肌的过度促有丝分裂活性，这归因于非PDGF多肽生长因子。可以想象，这种异常的促有丝分裂活性促成了在未成熟大鼠体内观察到的氧气诱导的气道平滑肌重塑。
