1. Induction of RNA interference for preventing organ/islet rejection.
My laboratory is the first in the world to utilize short interfering RNA (siRNA) to silence immune associated genes in immune cells (PCT CA03/00867). This new technology allows us to potently and specifically silence gene expression across multiple cell generations. By blocking immune activating genes, we can generate large numbers of Tol-DC in vitro, which can be used clinically for treatment of autoimmune diseases and transplant rejection. (J Immunol. 2003, 171:691). Recently we have developed 3 methods of inducing RNA interference using siRNA-expression cassettes (SEC), SEC-containing vectors, and plasmids encoding hairpin siRNA. We have successfully silenced MHC II, CD40, CD80, CD86, IL-12 and the transcription factor RelB in DC, 50 other immune-associated genes using siRNA.
2. Treatment of autoimmune diseases by “tolerogenic vaccination” using siRNA modified dendritic cells.
Using the murine model of rheumatoid arthritis, collagen II-induced arthritis (CIA), we demonstrated that administration of siRNA-IL12 treated DC, pulsed with CII, were sufficient to block progression of disease as observed by decreased pathological score, inhibited inflammatory infiltrate as seen by immunohistochemistry, and suppressed T cell and B cell responses as witnessed by dampened recall and antibody responses (Arthritis Therapy and Research. 2006, 8:141). Similar strategy has been also applied on EAE model by silencing TNF?, and RelB genes. These studies suggested a potent tolerogenic vaccine that would be useful for treatment of autoimmune diseases
3. Reinstallation of anti-cancer immunity by silencing tumor-derived immuno-suppressive genes.
Tumor-derived immune suppression in the main of cancer evasion from immune privilege, and is a major hurdle for the cancer immune/gene therapy. We developed a novel strategy to disrupt tumor-derived immune suppression by silencing tumor-originated tolerogenic molecule using small interfering RNA (siRNA). Silencing IDO in murine melanoma cell line B16 in vitro inhibited tumor growth and disabled tumor formation in vivo after inoculation in syngeneic and allogeneic recipients. In addition, Treatment with IDO-siRNA in B16-bearing mice successfully postponed tumor formation time and significantly decreased tumor size.(J Immunol. 2006, 177:5639). This study highlights that RNA interference could be an alternative potential for caner therapy through reinstalling anti-cancer immunity.
4. Development of novel organ/islet preservation solution using siRNA.
Ischemia-reperfusion (I/R) injury occurs in organ transplantation. We hypothesize that siRNA can effectively suppress inflammatory, apoptosis and complement genes which contribute to I/R injury. We developed a novel siRNA-containing preservation solution, which offers an alternative for protection of donor organs. This is the first demonstration of a novel siRNA solution that can prevent renal and cardiac I/R injury, protect organ function, and prolong graft survival in transplantation (Am J Transplant. 2006, 6: 2099), implying a significant and potential application in clinic.
5. Dendritic cell-mediated tolerance and immune regulatory feedback loop.
In our animal models of transplant tolerance, we discovered a self-maintaining feedback loop where Tol-DC activate T regulatory cells, which protect the graft and also give rise to more Tol-DC from the DC progenitors. This loop is specific to the donor antigen because the allograft long-lasting survivors permanently accept donor-derived skins but reject non-donor strain. We are the first group to report DC-T "two way" regulation in transplant tolerance (J Immunol. 2003, 170:1304).
6. Cellular therapy by in vitro generated tolerogenic dendritic cells and T regulatory cells.
In a murine transplant tolerance model, we have identified tolerogenic DC (Tol-DC) that have the following characteristics: immature and DC2-like phenotype; inhibited mixed lymphocyte reaction; impaired antigen presenting function, reduced costimulatory function and giving rise to Th2 cells. For therapeutic purposes we have established various strategies for generation of Tol-DC through: 1) Genetic modification, 2) Biological manipulation, and 3) Pharmacological targeting (Transplantation Immunology 2003, 11: 295). These in vitro generated Tol-DC can prevent allograft rejection in transplantation, as well as can promote T-regulatory cell differentiation. We are currently establishing protocols for the ex vivo generation and expansion of antigen-specific T-regulatory cells for treatment of autoimmune disease and transplant rejection.
