Sheerin N S, Zhou W, Adler S, Sacks S H
Department of Nephrology and Transplantation, UMDS, Guy's Hospital, London, United Kingdom.
Kidney Int. 1997 Mar;51(3):703-10. doi: 10.1038/ki.1997.101.
Glomerular endothelial cells are an important site of interaction with the cellular and soluble components of inflammation. To investigate the capacity of these cells to synthesize complement they were cloned from isolated rat glomeruli. Messenger RNA (mRNA) was extracted from the cells, reverse transcribed and used as the template to identify specific gene transcripts with the polymerase chain reaction (PCR). mRNA coding for the third component of the complement cascade (C3) was detected in unstimulated endothelial cells, whereas no message for the fourth component (C4) could be demonstrated. Using a semiquantitative method of PCR, we found that the expression of C3 is up-regulated by the cytokine tumor necrosis factor-alpha (TNF-alpha), but not by the cytokines interferon-gamma (IFN-gamma) and interleukin 1 alpha (IL-1 alpha). The increase in levels of C3 mRNA occurred in a time and dose dependent manner. This increase was dependent on new protein synthesis. Production of the C3 protein was demonstrated by radiolabeling and immunoprecipitation, and this also was stimulated by TNF-alpha. In conclusion, we demonstrate the production of C3 by microvascular endothelium of glomerular origin and its stimulation by TNF-alpha. We believe that this local synthesis could have a role in the pathogenesis of disease, however, the nature of this role at present remains unclear.
肾小球内皮细胞是与炎症的细胞和可溶性成分相互作用的重要部位。为了研究这些细胞合成补体的能力，从分离的大鼠肾小球中克隆了它们。从细胞中提取信使核糖核酸（mRNA），进行逆转录，并用作模板通过聚合酶链反应（PCR）鉴定特定的基因转录本。在未受刺激的内皮细胞中检测到编码补体级联反应第三成分（C3）的mRNA，而未检测到第四成分（C4）的信息。使用半定量PCR方法，我们发现C3的表达受细胞因子肿瘤坏死因子-α（TNF-α）上调，但不受细胞因子干扰素-γ（IFN-γ）和白细胞介素1α（IL-1α）上调。C3 mRNA水平的增加呈时间和剂量依赖性。这种增加依赖于新的蛋白质合成。通过放射性标记和免疫沉淀证明了C3蛋白的产生，并且这也受到TNF-α的刺激。总之，我们证明了肾小球来源的微血管内皮细胞产生C3并受到TNF-α的刺激。我们认为这种局部合成可能在疾病发病机制中起作用，然而，目前这种作用的性质尚不清楚。
