Targeted Silencing of TLR Adaptor Genes Using Mannose Liposome to Prolong Cardiac Allograft Survival
X. Zhang,1 J. Jiang,2 X. Zheng,1 J. Shi,3 T. Zwiep,1 N. Johnston,1 D. Quan,1,2 W.-P. Min.1,2,3
1Department of Surgery, Pathology and Oncology, Western University, London, ON, Canada 2Multi-Organ Transplant Program, London Health Sciences Centre, London, ON, Canada 3Jiangxi Academy of Medical Sciences, The First Affiliated Hospital, and Institute of Immunotherapy of Nanchang, NanChang, Jiangxi, China.
Background: MyD88 and TRIF, the common adaptors of Toll-like receptors (TLRs) signaling, evoke dendritic cells (DCs)-mediated antigen-specific immune rejection. Abolish TLR-induced adaptive immune response in DC may prevent cardiac grafts rejection. We hypothesized that mannose-conjugated liposome with small interference RNA (siRNA) can specifically deliver siRNA to DCs that abundantly express mannose receptor specifically block TLR adaptor pathway and may prolong allogeneic heart graft survival.
Method: Mannose liposomes were made in order to incorporate siRNA specific forMyD88 (Man-siMyD88) and TRIF siRNA Man-siTRIF). Recipients (BALB/c mice) were treated with Man-siMyD88 + Man-siTRIF, 3 and 7 days prior to heart transplantation and 7, 14, 21 days after transplantation. Control groups were injected with mannose liposome with scramble siRNA (Man-siGl2) and non-targeted liposome without mannose (lipo-siMyD88 and lipo-siTRIF). After siRNA treatment, a fully MHC-mismatched (C57/BL6 to BALB/c) heart transplantation was performed.
Result: Gene silencing in spleen DCs using Man-siMyD88 and siTRIF were demonstrated by and by qPCR and western blot. A significant prolongation of allograft survival was observed in the recipients treated by Man-siMyD88 + Man-siTRIF (mean survival time MST=63.5 days). In contrast, MST of allogeneic hearts in recipients treated with Man-siGl2 or non-targeted lipo-siMyD88 + lipo-siTRIF was 5.8 days and 15.7 days respectively. The prolongation of allograft survival is associated with immunomodulation induced by generation of tolerogenic DCs and Treg cells in recipients. Additionally, lower levels of INF-γ, IL1-β and higher levels of IL-10 and IL-6 were shown in an MLR when using DCs isolated from Man-siMyD88 + Man-siTRIF treated recipients, suggesting that targeted silencing of TLR pathways in DCs promoted Th differentiation.
Conclusion: This study demonstrated a new method of DC-specifically targeted siRNA delivery in vivo which specifically deliver siRNA to the spleen DCs, knock down TLR adaptors, and prolong allograft survival, implying the potential of a novel and effective RNAi-based anti-rejection therapeutics in heart transplantation.
Zhang X, Jiang J, Zheng X, Shi J, Zwiep T, Johnston N, Quan D, Min W-P. Targeted Silencing of TLR Adaptor Genes Using Mannose Liposome to Prolong Cardiac Allograft Survival [abstract]. Am J Transplant. 2015; 15 (suppl 3). https://atcmeetingabstracts.com/abstract/targeted-silencing-of-tlr-adaptor-genes-using-mannose-liposome-to-prolong-cardiac-allograft-survival/. Accessed July 12, 2020.