title: Induction of alloimmune tolerance in heart transplantation through gene silencing of TLR adaptors.
abstract: Toll-like receptors (TLRs) activate biochemical pathways that evoke activation of innate immunity, which leads to dendritic cell (DC) maturation and initiation of adaptive immune responses that provoke allograft rejection. We aimed to prolong allograft survival by selectively inhibiting expression of the common adaptors of TLR signaling, namely MyD88 and TRIF, using siRNA. In vitro we demonstrated that blocking expression of MyD88 and TRIF led to reduced DC maturation. In vivo treatment of recipients with MyD88 and TRIF siRNA significantly prolonged allograft survival in the BALB/c > C57BL6 cardiac transplant model. Moreover, the combination of MyD88 and TRIF siRNA along with a low dose of rapamycin further extended the allograft survival (88.8 ± 7.1 days). Tissue histopathology demonstrated an overall reduction in lymphocyte interstitium infiltration, vascular obstruction and hemorrhage in mice treated with MyD88 and TRIF siRNA vector plus rapamycin. Furthermore, treatment was associated with an increase in the numbers of CD4(+) CD25(+) FoxP3(+)  regulatory T cells and Th2 deviation. To our knowledge, this study is the first demonstration of prolonging the survival of allogeneic heart grafts through gene silencing of TLR signaling adaptors, highlighting the therapeutic potential of siRNA in clinical transplantation.
authors: Departments of Surgery, Pathology, and Oncology, University of Western Ontario, London, Canada.
authors: X
authors: X
authors: Zhang
authors: M
authors: M
authors: Beduhn
authors: X
authors: X
authors: Zheng
authors: D
authors: D
authors: Lian
authors: D
authors: D
authors: Chen
authors: R
authors: R
authors: Li
authors: L K S
authors: LK
authors: Siu
authors: A
authors: A
authors: Marleau
authors: P W
authors: PW
authors: French
authors: T E
authors: TE
authors: Ichim
authors: W-P
authors: WP
authors: Min
mesh_terms: D000818:Animals; D001483:Base Sequence; D015153:Blotting, Western; D017931:DNA Primers; D020868:Gene Silencing; D016027:Heart Transplantation / Q000276:immunology*; D007108:Immune Tolerance; D007959:Lymphocyte Culture Test, Mixed; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D060888:Real-Time Polymerase Chain Reaction; D051193:Toll-Like Receptors / Q000235:genetics*
chemical_list: D017931:DNA Primers; D051193:Toll-Like Receptors