Ohira H, Miyata M, Kuroda M, Takagi T, Tojo J, Ochiai H, Kokubun M, Nishimaki T, Kasukawa R, Obara K
Department of Internal Medicine II, Fukushima Medical College, Japan.
J Hepatol. 1996 Dec;25(6):941-7. doi: 10.1016/s0168-8278(96)80300-x.
BACKGROUND/AIMS: The aim of this study was to assess the effect of interleukin-6 (IL-6) on the proliferation of hepatocytes and to study the interaction between IL-6 and hepatocyte growth factor (HGF) in vivo.
IL-6 was injected at a dose of 200 micrograms/mg subcutaneously into rats every day for 14 days. Liver and blood samples were obtained at 1, 3, 7 and 14 days during IL-6 administration. Hepatocyte proliferative activity of sera was measured using 3H-thymidine incorporation into cultured rat hepatocytes. To evaluate the proliferative activity of the hepatocytes in tissue sections, hepatic DNA content and immunostaining of the liver tissue sections for proliferating cell nuclear antigen (PCNA) were performed. Plasma HGF levels were measured using specific EIA. In addition, total RNA was extracted from the liver and expression of HGF mRNA was detected by RT-PCR.
The DNA contents of liver taken from IL-6-treated rats were increased during IL-6 administration compared with untreated rats. Sera taken from IL-6-treated rats at various intervals during administration also significantly increased 3H-thymidine incorporation by cultured rat hepatocytes compared with sera from untreated rats, suppressing 3H-thymidine incorporation at day 1 and 3 by anti-HGF antibody. IL-6 itself did not increase 3H-thymidine incorporation. Increased expression of PCNA in these hepatocytes was noted from 1 day after IL-6 administration, and at 14 days, the number of PCNA-positive cells was sevenfold greater than in the livers of untreated rats. However, plasma HGF levels showed a peak at day 1, decreased gradually from day 3, and became undetectable by day 14. HGF mRNA expression in livers of IL-6-treated rats was suppressed from day 3 to day 14 of IL-6 administration.
These data show that IL-6 induces an early phase of liver cell growth in vivo and suggest that an increase level of HGF mediates this effect.
背景/目的：本研究旨在评估白细胞介素-6（IL-6）对肝细胞增殖的影响，并研究IL-6与肝细胞生长因子（HGF）在体内的相互作用。
每天以200微克/毫克的剂量皮下注射IL-6给大鼠，持续14天。在给予IL-6的第1、3、7和14天采集肝脏和血液样本。使用3H-胸腺嘧啶核苷掺入培养的大鼠肝细胞来测量血清中肝细胞的增殖活性。为了评估组织切片中肝细胞的增殖活性，进行了肝脏DNA含量测定以及肝脏组织切片增殖细胞核抗原（PCNA）的免疫染色。使用特异性酶联免疫吸附测定法（EIA）测量血浆HGF水平。此外，从肝脏中提取总RNA，并通过逆转录聚合酶链反应（RT-PCR）检测HGF mRNA的表达。
与未处理的大鼠相比，在给予IL-6期间，取自IL-6处理大鼠的肝脏DNA含量增加。在给予IL-6的不同时间间隔采集的血清，与未处理大鼠的血清相比，也显著增加了培养的大鼠肝细胞对3H-胸腺嘧啶核苷的掺入，抗HGF抗体在第1天和第3天抑制了3H-胸腺嘧啶核苷的掺入。IL-6本身并未增加3H-胸腺嘧啶核苷的掺入。从给予IL-6后第1天起，这些肝细胞中PCNA的表达增加，在第14天，PCNA阳性细胞的数量比未处理大鼠肝脏中的多七倍。然而，血浆HGF水平在第1天达到峰值，从第3天开始逐渐下降，到第14天无法检测到。在给予IL-6的第3天至第14天，IL-6处理大鼠肝脏中HGF mRNA的表达受到抑制。
这些数据表明IL-6在体内诱导肝细胞生长的早期阶段，并提示HGF水平的升高介导了这种作用。
