In vivo analysis of the 'bystander effect': a cytokine cascade.
In vivo analysis of the 'bystander effect': a cytokine cascade.
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发表时间：
1996-07
影响因子：
2.6
通讯作者：
R. Ramesh;A. Marrogi;A. Munshi;C. Abboud;S. Freeman
中科院分区：
文献类型：
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作者：
R. Ramesh;A. Marrogi;A. Munshi;C. Abboud;S. Freeman
“旁观者效应”是指未修饰的肿瘤细胞在与更昔洛韦（GCV）暴露的、单纯疱疹病毒-胸苷激酶（HSV-TK）修饰的肿瘤细胞接触时死亡。虽然介导体内旁观者效应的确切机制或机制尚不清楚，但我们的研究结果表明，这种现象的发生需要完整的宿主免疫系统。本研究旨在建立HSV-TK修饰的肿瘤细胞和GCV对肿瘤及其微环境的影响。在亚致死剂量照射和免疫缺陷Balb/c小鼠中，观察到旁观者效应减弱或消失。免疫活性小鼠肿瘤块的组织学检查显示，与对照小鼠（5%）相比，荷瘤小鼠接种HSV-TK修饰的肿瘤细胞和GCV后，肿瘤块出现集中出血性肿瘤坏死（38%），表明肿瘤坏死因子-α（TNF-α）等细胞因子正在局部释放。这一假设是强调使用逆转录酶聚合酶链反应（RT-PCR），通过证明细胞因子mRNA的表达与HSV-TK表达肿瘤和GCV治疗的小鼠。使用PCR-MIMIC对来自第1天和第4天治疗的小鼠的肿瘤样品进行TNF-α的半定量PCR分析，显示mRNA表达水平增加了两倍。此外，TNF-α的免疫组织化学染色显示浸润肿瘤的单核炎性细胞是其来源。最后，实验动物中肿瘤浸润淋巴细胞（TIL）的表征表明，与对照动物相比，巨噬细胞和T细胞的数量增加了2 - 3倍。这些结果表明，在体内，旁观者效应部分介导的抗肿瘤反应通过释放细胞因子。此外，细胞因子环境和肿瘤微环境可以在注射HSV-TK细胞和GCV后调节，以增强宿主免疫应答，这在临床试验中具有潜在的用途。
The "bystander effect" refers to the death of unmodified tumor cells when in contact with ganciclovir (GCV)-exposed, herpes simplex virus-thymidine kinase (HSV-TK)-modified tumor cells. Although the exact mechanism or mechanisms involved in mediating the bystander effect in vivo are unknown, our findings suggest that an intact host immune system is required for the phenomenon to occur. The present study was designed to establish the effect of HSV-TK-modified tumor cells and GCV on the tumor and its microenvironment in vivo. In sublethally irradiated and immunodeficient Balb/c mice, the bystander effect was observed to be diminished or abrogated. Histopathologic examination of the tumor mass from immunocompetent mice demonstrated centralized hemorrhagic tumor necrosis (38%) after inoculation of the HSV-TK-modified tumor cells and GCV in tumor-bearing mice compared with the control mice (5%), indicating that cytokines such as tumor necrosis factor-alpha (TNF-alpha) were being released locally. This hypothesis was underscored using reverse transcriptase polymerase chain reaction (RT-PCR), by the demonstration of cytokine mRNA expression in mice treated with HSV-TK-expressing tumors and GCV. Semiquantitative PCR analysis for TNF-alpha using PCR-MIMIC on tumor samples from mice treated on days 1 and 4 showed a two-fold increase in the level on mRNA expression. Also, immunohistochemical staining for TNF-alpha showed that mononuclear inflammatory cells infiltrating the tumor were its source. Finally, characterization of tumor-infiltrating lymphocytes (TIL) in experimental animals demonstrated a two- to three-fold increase in the number of macrophages and T cells compared with control animals. These results demonstrate that, in vivo, the bystander effect is mediated in part by an antitumor response through the release of cytokines. Further, the cytokine milieu and tumor microenvironment can be modulated following injection of HSV-TK cells and GCV to enhance the host immune response, which is of potential use in clinical trials.