Induction of RNA interference for immunomodulation            

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.

siRNA-expressing vector

Transfecting Dendritic Cells with siRNA or siRNA-expressing vector

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. Similar strategy has been also applied on EAE model by silencing TNF-alpha, and RelB genes.  These studies suggested a potent tolerogenic vaccine that would be useful for treatment of autoimmune diseases.

Reinstallation of anti-cancer immunity by breaking tumor-derived immuno-suppression

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, indoleamine 2,3-dioxygenase(IDO), using small interfering RNA (siRNA). Murine melanoma cell line B16 expressed IDO, which can be efficiently silenced by siRNA specific to IDO (IDO-siRNA). IDO expressed in B16 induced T cell apoptosis and suppressed T cell responses in vitro and in vivo. Transduction of IDO-siRNA into B16 prevented calabolization of tryptophan, the most critical component for T cell survival, as well as inhibited T cell apoptosis. Silencing IDO in 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. Furthermore, silencing IDO resulted in recovery of T cells responses and enhancement of tumor-specific killing. Taken together, silencing IDO may break tumor-derived immune suppression and RNA interference could be an alternative potential for caner therapy through reinstalling anti-cancer immunity.