Cross-Linking of B7-H1 on EBV-Transformed B Cells Induces Apoptosis through Reactive Oxygen Species Production, JNK Signaling Activation, and fasL Expression
Cross-Linking of B7-H1 on EBV-Transformed B Cells Induces Apoptosis through Reactive Oxygen Species Production, JNK Signaling Activation, and fasL Expression
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DOI：
10.4049/jimmunol.181.9.6158
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发表时间：
2008-11-01
影响因子：
4.4
通讯作者：
Hur, Dae Young
中科院分区：
文献类型：
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作者：
Kim, Yeong Seok;Park, Ga Bin;Hur, Dae Young
B7-H1是B7家族中新发现的成员，在细胞介导的免疫反应中具有重要的调节功能，在人类免疫细胞和多种肿瘤中表达。我们首先观察到B细胞表面B7-H1的表达在EBV永生化过程中增加，这与炎症和肿瘤发生密切相关。使用抗 B7-H1 Ab（克隆 130002）交联 EBV 转化的 B 细胞上的 B7-H1 会诱导活性氧 (ROS) 产生、线粒体破坏、线粒体中凋亡蛋白的释放以及随后的细胞凋亡。抑制 caspase 和 ROS 生成可恢复 B7-H1 介导的细胞凋亡和 caspase-8、-9 和 -3 的蛋白水解活性。我们观察到 B7-H1 刺激诱导 fasL 的转录和翻译。 ZB4（一种拮抗性抗 fas 抗体）和 NOK-1（一种拮抗性抗 fasL 抗体）可有效阻止细胞凋亡，而不对 ROS 产生产生任何影响。 N-乙酰半胱氨酸 (NAC) 完全阻断 fasL mRNA 和蛋白质的诱导。我们发现 B7-H1 刺激激活了 JNK 和 c-jun 的磷酸化，并下调了 ERK1/2 和 p-Akt。 NAC阻断JNK的激活和ERK的下调，但z-VAD-fmk（N-苄氧基羰基-Val-Ala-Asp-氟甲基酮）和ZB4均不抑制B7-H1刺激的JNK激活。 SP600125 阻断快速、诱导和凋亡，但不影响 B7-H1 刺激后 ROS 的产生。综上所述，我们得出结论，EBV 转化的 B 细胞上 B7-H1 介导的细胞凋亡可能参与了 fasL 的诱导，这是由 B7-H1 交联后 ROS 生成和 JNK 激活引起的。这些结果为理解 B7-H1 的反向信号传导以及使用抗 B7-H1 的肿瘤免疫治疗的另一种机制提供了新概念。免疫学杂志，2008，181：6158-6169。
B7-H1 is a newly identified member of the B7 family with important regulatory functions in cell-mediated immune responses, and it is expressed in human immune cells and several tumors. We first observed that expression of surface B7-H1 on B cells was increased during the immortalization process by EBV, which is strongly related to both inflammation and tumorigenesis. Crosslinking of B7-H1 on EBV-transformed B cells using anti-B7-H1 Ab (clone 130002) induced reactive oxygen species (ROS) generation, mitochondrial disruption, release of apoptotic proteins from mitochondria, and subsequent apoptosis. Inhibition of caspases and ROS generation recovered B7-H1-mediated apoptosis and proteolytic activities of caspase-8, -9, and -3. We observed that B7-H1 stimulation induced both transcription and translation of fasL. ZB4, an antagonistic anti-fas Ab, and NOK-1, an antagonistic anti-fasL Ab, effectively blocked apoptosis without exerting any influence on ROS generation. N-acetylcysteine (NAC) completely blocked the induction of fasL mRNA and protein. We found that B7-H1 stimulation activated the phosphorylation of JNK and c-jun and down-regulated ERK1/2 and p-Akt. NAC blocked the activation of JNK and down-regulation of ERK, but both z-VAD-fmk (N-benzyloxycarbonyl-Val-Ala-Asp-fluoromethylketone) and ZB4 did not inhibit JNK activation of B7-H1 stimulation. SP600125 blocked fast, induction and apoptosis but did not affect ROS generation after B7-H1 stimulation. Taken together, we concluded that B7-H1-mediated apoptosis on EBV-transformed B cells may be involved in the induction of fasL, which is evoked by ROS generation and JNK activation after cross-linking of B7-H1. These results provide a new concept for understanding reverse signaling through B7-H1 and another mechanism of tumor immunotherapy using anti-B7-H1. The Journal of Immunology, 2008, 181: 6158-6169.