Shigematsu T, Miura S, Hirokawa M, Hokari R, Higuchi H, Watanabe N, Tsuzuki Y, Kimura H, Tada S, Nakatsumi R C, Saito H, Ishii H
Department of Internal Medicine, School of Medicine, Keio University, Tokyo 160-8582, Japan.
Am J Physiol. 1998 Sep;275(3):G556-63. doi: 10.1152/ajpgi.1998.275.3.G556.
Endothelin (ET), a vasoconstrictive peptide, is known to have a variety of biological actions. Although ET is released by vascular endothelial cells, other cell populations also have been reported to synthesize and release ET. In this study, we examined whether ET is synthesized by intestinal epithelial cells and whether it affects induction of epithelial cell proliferation by interleukin-2 (IL-2). Subconfluent monolayers of intestinal epithelial cells (IEC-6 and IEC-18) were maintained in serum-free medium before addition of rat IL-2. Both IEC-6 and IEC-18 cells released ET-1 into the medium under unstimulated conditions, as determined by a sandwich ELISA. IL-2 significantly enhanced ET-1 release in a time-dependent manner. ET-3 was not detectable in the culture media of either cell line. Expression of ET-1 and ET-3 mRNA in epithelial cells was assessed by competitive PCR. Both cell lines were shown to express ET-1 mRNA, but no ET-3 mRNA was detected. IL-2 treatment enhanced ET-1 mRNA expression by both IEC-6 and IEC-18 cells. Both cell lines also expressed mRNA for ETA and ETB receptor subtypes. When cell proliferation was assessed, exogenous ET-1 induced a slight proliferative response in both types of cells that was consistent and significant at low ET-1 concentrations; cell growth was inhibited at a higher concentration (10(-7) M). IL-2 produced a significant proliferative response in both cell lines. However, the addition of ET-1 (10(-7) M) to culture media attenuated the IL-2-induced increase in cell proliferation. ETA-receptor antagonists significantly enhanced cellular proliferation, suggesting involvement of the ETA receptor in modulation of IL-2-induced intestinal epithelial cell growth.
内皮素（ET）是一种血管收缩肽，已知具有多种生物学作用。尽管ET由血管内皮细胞释放，但也有报道称其他细胞群体也能合成和释放ET。在本研究中，我们检测了肠道上皮细胞是否合成ET，以及它是否影响白细胞介素-2（IL-2）诱导的上皮细胞增殖。在添加大鼠IL-2之前，将亚汇合的肠道上皮细胞单层（IEC-6和IEC-18）维持在无血清培养基中。通过夹心ELISA测定，IEC-6和IEC-18细胞在未刺激条件下均将ET-1释放到培养基中。IL-2以时间依赖性方式显著增强ET-1的释放。在两种细胞系的培养基中均未检测到ET-3。通过竞争性PCR评估上皮细胞中ET-1和ET-3 mRNA的表达。两种细胞系均显示表达ET-1 mRNA，但未检测到ET-3 mRNA。IL-2处理增强了IEC-6和IEC-18细胞中ET-1 mRNA的表达。两种细胞系也表达ETA和ETB受体亚型的mRNA。当评估细胞增殖时，外源性ET-1在两种类型的细胞中均诱导了轻微的增殖反应，在低ET-1浓度下这种反应是一致且显著的；在较高浓度（10^(-7) M）时细胞生长受到抑制。IL-2在两种细胞系中均产生了显著的增殖反应。然而，向培养基中添加ET-1（10^(-7) M）减弱了IL-2诱导的细胞增殖增加。ETA受体拮抗剂显著增强了细胞增殖，表明ETA受体参与调节IL-2诱导的肠道上皮细胞生长。
