Jeong T C, Yang K H, Jordan S D, Stevens W D, Holsapple M P
Department of Pharmacology and Toxicology, Medical College of Virginia/Virginia Commonwealth University, Richmond.
Toxicology. 1994 Aug 12;91(3):253-68. doi: 10.1016/0300-483x(94)90013-2.
We have previously reported that the hormone-supplemented culture condition for primary hepatocytes is required in dimethylnitrosamine (DMN)-induced suppression of antibody response to sheep erythrocytes in the mixed cultures of murine hepatocytes and splenocytes. In the present investigation, the components of the hormone supplement were screened to identify the component(s) responsible for the increased ability of hepatocytes to activate DMN to its immunosuppressive form. The presence of hydrocortisone in the hepatocyte culture media had the primary role in DMN activation in the co-culture system. Other components of the hormone supplement showed slight or no effects. The effects of hydrocortisone were clearly confirmed through the dose-response study of both DMN and hydrocortisone. To characterize whether the effect of hydrocortisone is glucocorticoid-dependent we tested another potent glucocorticoid, dexamethasone (DEX), and determined if the activity by hydrocortisone could be reversed by RU 486. It was found that hepatocytes cultured in DEX-containing media could also activate DMN to its immunosuppressive form. However, the activity by hydrocortisone to increase DMN-induced immunosuppression was not reversed by RU 486. Furthermore, a possible direct interaction between DMN and hydrocortisone was ruled out. Finally, we transferred DMN-pre-treated culture supernatant from hepatocytes to spleen cell cultures, and found that the metabolite of DMN was very unstable, and that DMN-induced suppression of T-dependent antibody response was hepatocyte-dependent. The present results suggest that glucocorticoids, including hydrocortisone and DEX, in hepatocyte culture media can affect DMN-induced immunosuppression in the hepatocyte/splenocyte co-culture system via a pathway which does not appear to be related to the glucocorticoid receptor.
我们之前报道过，在小鼠肝细胞和脾细胞的混合培养物中，二甲基亚硝胺（DMN）诱导的对绵羊红细胞抗体反应的抑制需要用于原代肝细胞的激素补充培养条件。在本研究中，对激素补充剂的成分进行了筛选，以确定负责肝细胞将DMN激活为其免疫抑制形式能力增强的成分。肝细胞培养基中氢化可的松的存在在共培养系统中对DMN的激活起主要作用。激素补充剂的其他成分显示出轻微或无影响。通过对DMN和氢化可的松的剂量反应研究，明确证实了氢化可的松的作用。为了表征氢化可的松的作用是否依赖于糖皮质激素，我们测试了另一种强效糖皮质激素地塞米松（DEX），并确定RU 486是否可以逆转氢化可的松的活性。发现培养在含DEX培养基中的肝细胞也可以将DMN激活为其免疫抑制形式。然而，RU 486不能逆转氢化可的松增加DMN诱导的免疫抑制的活性。此外，排除了DMN与氢化可的松之间可能的直接相互作用。最后，我们将DMN预处理的肝细胞培养上清液转移到脾细胞培养物中，发现DMN的代谢产物非常不稳定，并且DMN诱导的对T细胞依赖性抗体反应的抑制是肝细胞依赖性的。目前的结果表明，肝细胞培养基中的糖皮质激素，包括氢化可的松和DEX，可以通过一条似乎与糖皮质激素受体无关的途径影响肝细胞/脾细胞共培养系统中DMN诱导的免疫抑制。
