Low-Dose Rapamycin Unmasks the Protective Potential of Targeting Intragraft NF-κB for Islet Transplants
| Autor: | Nathan W. Zammit, Bernice M. Tan, Stacey N. Walters, David Liuwantara, Jeanette E. Villanueva, Elisabeth K. Malle, Shane T. Grey |
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| Jazyk: | angličtina |
| Rok vydání: | 2013 |
| Předmět: | |
| Zdroj: | Cell Transplantation, Vol 22 (2013) |
| Druh dokumentu: | article |
| ISSN: | 0963-6897 1555-3892 |
| DOI: | 10.3727/096368912X658737 |
| Popis: | Islet grafts can contribute to their own destruction via the elaboration of proinflammatory genes, many of which are transcriptionally regulated by nuclear factor κ-light-chain-enhancer of activated B-cells (NF-κB). Thus, NF-κB constitutes an enticing gene therapy candidate to improve the success of islet transplantation. To test this hypothesis in vivo, we blocked NF-κB in BALB/c (H2 d ) to C57/BL6 (H2 b ) mouse islet allografts by genetically engineering islets to express the NF-κB superrepressor, IκBα. Here we show by microarray and RTqPCR that islets exhibit an intrinsic early immediate proinflammatory response, with the most highly upregulated proinflammatory genes comprising the chemokines Cxcl1 , Cxcl2 , Cxcl10 , and Ccl2 ; the cytokines Tnf-α and Il-6 ; and the adhesion molecule Icam1 . Overexpression of IκBα inhibited the expression of these genes by 50–95% in islets and MIN6 β-cells in vitro, by inhibiting NF-κB-dependent gene transcription. Histological and RTqPCR analysis at postoperative day (POD) 10 revealed that IκBα-transduced islet allografts exhibited improved islet architecture and strong insulin-labeling with decreased Ccl2 and Il-6 mRNA levels compared to the GFP-transduced control grafts. Despite these protective effects, NF-κB-blocked islet allografts were promptly rejected in our MHC-mismatched mouse model. However, IκBα-expressing grafts did harbor localized “pockets” of Foxp3 + mononuclear cells not evident in the control grafts. This result suggested that the effect of the NF-κB blockade might synergize with regulatory T-cell-sparing rapamycin. Indeed, combining intragraft IκBα expression with low-dose rapamycin increased the mean survival time of islet allografts from 20 to 81 days, with 20% of the grafts surviving for greater than 100 days. In conclusion, rapamycin unmasks the protective potential of intragraft NF-κB blockade, which can, in some cases, permit permanent allograft survival without continuous systemic immunosuppression. |
| Databáze: | Directory of Open Access Journals |
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