Mulligan Jennifer K, Lathers Deanne M R, Young M Rita I
Research Service (151), Ralph H. Johnson VA Medical Center, 109 Bee Street, Charleston, SC 29401, USA.
Cancer Immunol Immunother. 2008 Jul;57(7):951-61. doi: 10.1007/s00262-007-0425-x.
Patients and mice with solid tumors, such as Lewis lung carcinoma (LLC), have defects in functions of immune effector cells. Endothelial cells, a component of the tumor vasculature, are potential regulators of immune cell functions. Therefore, these studies examined the impact of exposure to LLC tumor on the ability of endothelial cells to modulate immune cell functions.
Endothelial cells were pre-treated with LLC tumor-conditioned medium (Endo(T-sup)) for 24 h. Control endothelial cells that were exposed to medium (Endo(Media)) epithelial cell-conditioned medium or (Endo(Epi-sup)). After the initial 24 h incubation, endothelial cells were washed and fresh media was added. Cells were allowed to incubate for an additional 24 h. Supernatants from Endo(Media), Endo(Epi-sup) or Endo(T-sup) were collected and assayed for immune modulatory products and for immune modulatory activity.
Supernatant from Endo(T-sup) contained increased levels of PGE2, IL-6 and VEGF as compared to Endo(Media) and Endo(Epi-sup) controls. NK cell activity, as measured by TNF-alpha and IFN-gamma secretion, was increased following exposure to media conditioned by Endo(Media) and Endo(Epi-sup) Exposure of NK cells to supernatants of Endo(T-sup), also increases TNF-alpha and IFN-gamma secretion, but to a lesser extent than by Endo(Media) and Endo(Epi-sup). Examination of macrophage functions demonstrated that supernatant from Endo(T-sup) decreased microbead phagocytosis and increased production of the immune suppressive mediators, IL-10 and PGE2. Lastly, T-cell responses to stimulation with anti-CD3 in the presence of supernatants from Endo(T-sup) were examined. IFN-gamma production by CD8+ T-cells was reduced after exposure to Endo(T-sup)-conditioned medium, as compared to cells treatments with medium or control conditioned medium. Production of IFN-gamma by CD4+ T-cells exposed to Endo(T-sup) was not altered.
Taken together, these studies demonstrate that tumors skew endothelial cells to disrupt NK cell, T-cell and macrophages functions, and represents a novel mechanism of tumor-induced immune suppression.
患有实体瘤的患者和小鼠，如Lewis肺癌（LLC），其免疫效应细胞功能存在缺陷。内皮细胞作为肿瘤血管系统的一个组成部分，是免疫细胞功能的潜在调节因子。因此，这些研究探讨了暴露于LLC肿瘤对内皮细胞调节免疫细胞功能能力的影响。
内皮细胞用LLC肿瘤条件培养基（Endo(T-sup)）预处理24小时。对照内皮细胞分别暴露于培养基（Endo(Media)）、上皮细胞条件培养基（Endo(Epi-sup)）。在最初孵育24小时后，洗涤内皮细胞并添加新鲜培养基。细胞再孵育24小时。收集Endo(Media)、Endo(Epi-sup)或Endo(T-sup)的上清液，检测免疫调节产物和免疫调节活性。
与Endo(Media)和Endo(Epi-sup)对照相比，Endo(T-sup)的上清液中PGE2、IL-6和VEGF水平升高。通过TNF-α和IFN-γ分泌测定的NK细胞活性，在暴露于Endo(Media)和Endo(Epi-sup)条件培养基后增加。NK细胞暴露于Endo(T-sup)的上清液也会增加TNF-α和IFN-γ分泌，但程度低于Endo(Media)和Endo(Epi-sup)。巨噬细胞功能检测表明，Endo(T-sup)的上清液降低了微珠吞噬作用，并增加了免疫抑制介质IL-10和PGE2的产生。最后，检测了在Endo(T-sup)上清液存在下T细胞对抗CD3刺激的反应。与用培养基或对照条件培养基处理的细胞相比，CD8+ T细胞暴露于Endo(T-sup)条件培养基后IFN-γ产生减少。暴露于Endo(T-sup)的CD4+ T细胞的IFN-γ产生没有改变。
综上所述，这些研究表明肿瘤使内皮细胞发生偏向，从而破坏NK细胞、T细胞和巨噬细胞的功能，这代表了肿瘤诱导免疫抑制的一种新机制。
