Laboratory of Immunology, Research Centre Hospitalier de l'Université de Montréal, Notre-Dame Hospital, Montreal, Quebec, Canada.
J Immunol. 2009 Dec 15;183(12):8157-66. doi: 10.4049/jimmunol.0901165.
The islet primary nonfunction (PNF) is a serious problem in islet transplantation. In this study, we investigated whether DcR3-secreting transgenic (Tg) islets could reduce PNF. We generated Tg mice expressing human DcR3. The transgenically expressed DcR3 protected islets from IFN-gamma plus IL-1beta- or TNF-alpha plus IL-1beta-induced dysfunction and apoptosis in vitro. The Tg islets presented significantly reduced PNF after transplantation. Mechanistically, in addition to the known FasL apoptotic pathway, components of two other apoptosis pathways, that is, HVEM/LTbetaR for the LIGHT pathway and DR3 for the TL1A pathway, were found to be expressed in islets. Recombinant LIGHT- and TL1A-induced islet apoptosis in the absence of the FasL/Fas pathway, as well as DcR3, could block such induction. These results for the first time demonstrated that LIGHT and TL1A were capable of inducing islet apoptosis in addition to FasL, while DcR3 protected the islets by blocking all three apoptosis pathways. By DNA microarray analysis, we discovered that Adcyap was up-regulated >700-fold and Bank1 was down-regulated 50-fold in the cytokine-assaulted Tg islets, compared with WT islets. Forced overexpression of Adcyap1 by plasmid transfection or knockdown of Bank1 expression by small interfering RNA in insulinoma NIT-1 cells protected them from cytokine-triggered apoptosis, indicating that indeed DcR3 protects beta cells via the action of these two downstream molecules. This study has revealed novel mechanisms by which DcR3 protects islet survival, and it has identified new therapeutic targets of diabetes.
胰岛原发性无功能（PNF）是胰岛移植中的一个严重问题。在这项研究中，我们研究了是否表达人 DcR3 的转基因（Tg）胰岛能够减少 PNF。我们生成了表达人 DcR3 的 Tg 小鼠。转染的 DcR3 在体外保护胰岛免受 IFN-γ+IL-1β-或 TNF-α+IL-1β诱导的功能障碍和凋亡。Tg 胰岛在移植后 PNF 显著减少。在机制上，除了已知的 FasL 凋亡途径外，两种其他凋亡途径的组成部分，即 LIGHT 途径的 HVEM/LTβR 和 TL1A 途径的 DR3，在胰岛中被发现表达。在没有 FasL/Fas 途径的情况下，重组 LIGHT 和 TL1A 诱导胰岛凋亡，以及 DcR3，可以阻断这种诱导。这些结果首次表明，除了 FasL 之外，LIGHT 和 TL1A 也能够诱导胰岛凋亡，而 DcR3 通过阻断这三种凋亡途径来保护胰岛。通过 DNA 微阵列分析，我们发现与 WT 胰岛相比，在细胞因子攻击的 Tg 胰岛中，Adcyap 被上调了 >700 倍，Bank1 被下调了 50 倍。质粒转染中 Adcyap1 的过表达或胰岛素瘤 NIT-1 细胞中 Bank1 表达的小干扰 RNA 敲低，保护它们免受细胞因子触发的凋亡，表明 DcR3 确实通过这两个下游分子的作用来保护β细胞。这项研究揭示了 DcR3 保护胰岛存活的新机制，并确定了糖尿病的新治疗靶点。
