AUTOINDUCTION OF TRANSFORMING GROWTH-FACTOR-BETA IN HUMAN LUNG FIBROBLASTS
AUTOINDUCTION OF TRANSFORMING GROWTH-FACTOR-BETA IN HUMAN LUNG FIBROBLASTS
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DOI：
10.1165/ajrcmb/8.4.417
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发表时间：
1993-04-01
影响因子：
6.4
通讯作者：
ABSHER, M
中科院分区：
文献类型：
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作者：
KELLEY, J;SHULL, S;ABSHER, M
β型转化生长因子（TGF-β）是一类对细胞增殖、分化、细胞外基质成分的转换、癌基因表达和细胞表型的其他方面具有不同影响的强效细胞因子。与某些物种的肺成纤维细胞不同，未刺激的人肺成纤维细胞系在培养物中产生很少或不产生TGF-β。然而，据报道，TGF-β在某些人类肿瘤细胞和啮齿动物细胞系中自动调节其自身的产生。为了测试这种现象是否在来自正常人肺组织的成纤维细胞中起作用，将IMR90正常胎儿肺成纤维细胞的汇合培养物暴露于TGF-β。在无血清条件下将培养物短暂暴露于纯化的TGF-β 1，并通过免疫印迹和使用中和抗体进行特异性生物测定来确定随后72小时内新合成的TGF-β的分泌。通过对总细胞RNA进行北方和狭缝印迹杂交分析，检测TGF-β 1 mRNA的稳态水平。2.5 kb TGF-β 1 mRNA种类在IMR90细胞暴露于TGF-β 1的1.5 h内升高，并在16 h后达到最高水平。在暴露开始后9小时，在条件培养基中检测到TGF-β水平增加。此后，TGF-β继续以升高的速率（90 +/-7 vs未诱导细胞中小于或等于15 pg/10（6）个细胞/h）蓄积长达72 h。低至1 ng/ml TGF-β 1自身诱导TGF-β分泌。增加外源性TGF-β的浓度（1至10 ng/ml）以浓度依赖性方式提高分泌的TGF-β的自诱导。所有由刺激的IMR90成纤维细胞释放的TGF-β均为潜伏形式，证实其为新合成的细胞因子。此外，条件培养基与抗TGF-β中和抗体的孵育抑制分泌的TGF-β的活性。生物测定数据也通过蛋白质印迹证实，表明在来自自诱导成纤维细胞的条件培养基中特异性24 kD 1型TGF-β蛋白的量增加。成人肺成纤维细胞系的平行评价表明，自诱导也发生在他们身上。这些研究证实，在正常肺成纤维细胞中发生自诱导，表明细胞因子信号放大发生在肺间质中。
The type beta transforming growth factors (TGF-betas) are a family of potent cytokines with diverse effects on proliferation, differentiation, turnover of extracellular matrix components, oncogene expression, and other aspects of cellular phenotype. Unlike lung fibroblasts of certain species, unstimulated human lung fibroblast lines produce little or no TGF-beta in culture. However, TGF-beta has been reported to autoregulate its own production in certain human tumor cells and in rodent cell lines. To test whether this phenomenon is operative in fibroblasts from normal human lung tissue, confluent cultures of IMR90 normal fetal lung fibroblasts were exposed to TGF-beta. Cultures were exposed briefly to purified TGF-beta1 under serum-free conditions and secretion of newly synthesized TGF-beta over the ensuing 72 h was determined by immunoblotting and bioassays made specific with the use of neutralizing antibodies. Steady-state levels of mRNA for TGF-beta1 were detected by Northern and slot blot hybridization analysis of total cellular RNA. The 2.5 kb TGF-beta1 mRNA species rose within 1.5 h of exposure of IMR90 cells to TGF-beta1 and reached maximal levels after 16 h. Increased levels of TGF-beta were detected in conditioned medium 9 h after the start of the exposure. Thereafter, TGF-beta continued to accumulate at an elevated rate (90 +/- 7 versus less-than-or-equal-to 15 pg/10(6) cells/h in uninduced cells) for up to 72 h. As little as 1 ng/ml TGF-beta1 auto-induced TGF-beta secretion. Increasing concentrations of exogenous TGF-beta (1 to 10 ng/ml) raised the auto-induction of secreted TGF-beta in a concentration dependent manner. All of the TGF-beta released by stimulated IMR90 fibroblasts was in latent form, confirming that it is newly synthesized cytokine. Furthermore, incubation of conditioned medium with anti-TGF-beta neutralizing antibodies inhibited the activity of secreted TGF-beta. Bioassay data were also confirmed by Western blots demonstrating a specific 24 kD type 1 TGF-beta protein in increased amounts in conditioned medium from auto-induced fibroblasts. Parallel evaluation of adult human lung fibroblast lines indicated that auto-induction occurred in them as well. These studies establish that auto-induction occurs in normal lung fibroblasts, suggesting that cytokine signal amplification occurs in the pulmonary interstitium.