Lee Sukmook, Ha In Su, Kim Jae Hyeon, Park Kyong Soo, Han Kyu Hyun, Kim Sun-Hee, Chae Young Chan, Kim Sun Hee, Kim Yun Hee, Suh Pann-Ghill, Ryu Sung Ho, Kim Jung-Eun, Bang Kitae, Hwang Jong-Ik, Yang Jaeseok, Park Kwang-Wook, Chung Junho, Ahn Curie
Clinical Research Institute, Seoul National University Hospital, Seoul, Korea.
Transplantation. 2008 Nov 15;86(9):1257-66. doi: 10.1097/TP.0b013e318188ab04.
The use of porcine islets as alternatives to transplantable human islets is hampered by xenotransplant rejection. To identify molecular mechanisms that would allow subversion of xenoislet rejection, we investigated the role of H2O2 in vascular cell adhesion molecule-1 (VCAM-1) expression by porcine and mouse islets and beta-cell lines.
Porcine islets were treated with H2O2, tumor necrosis factor alpha, interferon-gamma, interleukin-1beta, and lipopolysaccharide, to assess the effects of inflammatory stimulators on VCAM-1 expression using flow cytometry. The role of Ca2+ in H2O2-induced VCAM-1 expression was investigated in beta-cell lines using an extracellular Ca2+ chelator and Ca2+-depleted media. Furthermore, H2O2-induced VCAM-1 expression was measured in beta-cells, pretreated with inhibitors of protein kinase C, phospholipase D, and phosphatidylinositol-3 kinase/Akt. Finally, H2O2-induced VCAM-1 expression was evaluated in porcine islets and rodent beta-cell lines infected with an adenovirus encoding catalase, a H2O2-removing enzyme.
H2O2 was most potent inflammatory stimulator of VCAM-1 expression in porcine islets and had the greatest effect on VCAM-1 expression by beta-cells. Signaling pathway analysis demonstrated that extracellular Ca2+ influx was critical to H2O2-mediated VCAM-1 expression; however, protein kinase C, phospholipase D, and phosphatidylinositol-3 kinase/Akt activation were not required for VCAM-1 expression. Finally, catalase overexpression inhibited H2O2-induced VCAM-1 expression by islets and beta-cell lines.
An extracellular calcium-dependent H2O2 pathway is the critical mediator of VCAM-1 expression by pancreatic islets and beta-cells. Inhibition of this pathway by catalase overexpression in donor islets can be exploited to protect against xenoislet immune responses.
猪胰岛作为可移植人胰岛的替代物，其应用受到异种移植排斥的阻碍。为了确定能够颠覆异种胰岛排斥的分子机制，我们研究了过氧化氢（H2O2）在猪和小鼠胰岛及β细胞系血管细胞黏附分子-1（VCAM-1）表达中的作用。
用H2O2、肿瘤坏死因子α、干扰素-γ、白细胞介素-1β和脂多糖处理猪胰岛，通过流式细胞术评估炎症刺激物对VCAM-1表达的影响。在β细胞系中，使用细胞外Ca2+螯合剂和Ca2+耗尽的培养基研究Ca2+在H2O2诱导的VCAM-1表达中的作用。此外，在预先用蛋白激酶C、磷脂酶D和磷脂酰肌醇-3激酶/Akt抑制剂处理的β细胞中测量H2O2诱导的VCAM-1表达。最后，在感染了编码过氧化氢酶（一种H2O2清除酶）的腺病毒的猪胰岛和啮齿动物β细胞系中评估H2O2诱导的VCAM-1表达。
H2O2是猪胰岛中VCAM-1表达最有效的炎症刺激物，对β细胞的VCAM-1表达影响最大。信号通路分析表明，细胞外Ca2+内流对H2O2介导的VCAM-1表达至关重要；然而，VCAM-1表达不需要蛋白激酶C、磷脂酶D和磷脂酰肌醇-3激酶/Akt激活。最后，过氧化氢酶过表达抑制了H2O2诱导的胰岛和β细胞系的VCAM-1表达。
细胞外钙依赖性H2O2途径是胰岛和β细胞中VCAM-1表达的关键介质。通过在供体胰岛中过表达过氧化氢酶来抑制该途径，可用于预防异种胰岛免疫反应。
