CD5 blockade, a novel immune checkpoint inhibitor, enhances T cell anti-tumour immunity and delays tumour growth in mice harbouring poorly immunogenic 4T1 breast tumour homografts

CD5 is a member of the scavenger receptor cysteine-rich superfamily that is expressed on T cells and a subset of B cells (B1a) cell and can regulate the T cell receptor signaling pathway. Blocking CD5 function may have therapeutic potential in treatment of cancer by enhancing cytotoxic T lymphocyte recognition and ablation of tumour cells. The effect of administering an anti-CD5 antibody to block or reduce CD5 function as an immune checkpoint blockade to enhance T cell anti-tumour activation and function in vivo has not been explored. Here we challenged mice with poorly immunogenic 4T1 breast tumour cells and tested whether treatment with anti-CD5 monoclonal antibodies (MAb) in vivo could enhance non-malignant T cell anti-tumour immunity and reduce tumour growth. Treatment with anti-CD5 MAb resulted in an increased fraction of CD8+ T cells compared to CD4+ T cell in draining lymph nodes and the tumour microenvironment. In addition, it increased activation and effector function of T cells isolated from spleens, draining lymph nodes, and 4T1 tumours. Furthermore, tumour growth was delayed in mice treated with anti-CD5 MAb. These data suggest that use of anti-CD5 MAb as an immune checkpoint blockade can both enhance activation of T cells in response to poorly immunogenic antigens and reduce tumour growth in vivo. Exploration of anti-CD5 therapies in treatment of cancer, alone and in combination with other immune therapeutic drugs, is warranted.

CRISPR/Cas9 library screening uncovered methylated PKP2 as a critical driver of lung cancer radioresistance by stabilizing β-catenin

Radiation resistance is a major cause of lung cancer treatment failure. Armadillo (ARM) superfamily proteins participate in various fundamental cellular processes; however, whether ARM proteins regulate radiation resistance is not fully understood. Here, we used an unbiased CRISPR/Cas9 library screen and identified plakophilin 2 (PKP2), a member of the ARM superfamily of proteins, as a critical driver of radiation resistance in lung cancer. The PKP2 level was significantly higher after radiotherapy than before radiotherapy, and high PKP2 expression after radiotherapy predicted poor overall survival (OS) and postprogression survival (PPS). Mechanistically, mass spectrometry analysis identified that PKP2 was methylated at the arginine site and interacted with protein arginine methyltransferase 1 (PRMT1). Methylation of PKP2 by PRMT1 stabilized β-catenin by recruiting USP7, further inducing LIG4, a key DNA ligase in nonhomologous end-joining (NHEJ) repair. Concomitantly, PKP2-induced radioresistance depended on facilitating LIG4-mediated NHEJ repair in lung cancer. More strikingly, after exposure to irradiation, treatment with the PRMT1 inhibitor C-7280948 abolished PKP2-induced radioresistance, and C-7280948 is a potential radiosensitizer in lung cancer. In summary, our results demonstrate that targeting the PRMT1/PKP2/β-catenin/LIG4 pathway is an effective approach to overcome radiation resistance in lung cancer.

Reduced CD5 on CD8+ T Cells in Tumors but Not Lymphoid Organs Is Associated With Increased Activation and Effector Function

CD5, a member of the scavenger receptor cysteine-rich superfamily, is a marker for T cells and a subset of B cells (B1a). CD5 associates with T-cell and B-cell receptors and increased CD5 is an indication of B cell activation. In tumor-infiltrating lymphocytes (TILs) isolated from lung cancer patients, CD5 levels were negatively correlated with anti-tumor activity and tumor‐mediated activation-induced T cell death, suggesting that CD5 could impair activation of anti-tumor T cells. We determined CD5 levels in T cell subsets in different organs in mice bearing syngeneic 4T1 breast tumor homografts and assessed the relationship between CD5 and increased T cell activation and effector function by flow cytometry. We report that T cell CD5 levels were higher in CD4⁺ T cells than in CD8⁺ T cells in 4T1 tumor-bearing mice, and that high CD5 levels on CD4⁺ T cells were maintained in peripheral organs (spleen and lymph nodes). However, both CD4⁺ and CD8⁺ T cells recruited to tumors had reduced CD5 compared to CD4⁺ and CD8⁺ T cells in peripheral organs. In addition, CD5^high/CD4⁺ T cells and CD5^high/CD8⁺ T cells from peripheral organs exhibited higher levels of activation and associated effector function compared to CD5^low/CD4⁺ T cell and CD5^low/CD8⁺ T cell from the same organs. Interestingly, CD8⁺ T cells among TILs and downregulated CD5 were activated to a higher level, with concomitantly increased effector function markers, than CD8⁺/CD5^high TILs. Thus, differential CD5 levels among T cells in tumors and lymphoid organs can be associated with different levels of T cell activation and effector function, suggesting that CD5 may be a therapeutic target for immunotherapeutic activation in cancer therapy.

Intranasal administration of regulatory dendritic cells is useful for the induction of nasal mucosal tolerance in a mice model of allergic rhinitis

Background

Intranasally administered dendritic cells (DCs) migrate into blood and thymus to induce immune responses. Regulatory dendritic cells (DCs) are also useful agents for allergy control. However, to the best of our knowledge, the effects of intranasal administration of regulatory DCs on allergy have not been reported until now. Therefore, we examined the effects of intranasal route of administration of CD40-silenced DCs on allergic responses and compared these with the effects of other administration routes, based on our previous findings on the inhibitory effects of CD40-silenced DCs on allergic responses.

Methods

Mice with allergic rhinitis were treated intranasally, subcutaneously, intraperitoneally, or intravenously with CD40-silenced ovalbumin (OVA)-pulsed DCs that were transfected with CD40 siRNAs and pulsed with OVA antigen. The effects of these DCs on allergic reactions and symptoms were estimated.

Results

Intranasal, subcutaneous, intraperitoneal, or intravenous administration of OVA-pulsed CD40-silenced DCs inhibited allergic responses and symptoms in mice. Furthermore, intranasal administration of OVA-pulsed CD40-silenced DCs significantly reduced allergic symptoms and the number of eosinophils in the nasal mucosa compared with subcutaneous, intraperitoneal, or intravenous administration of these DCs. Intranasal administration of OVA-pulsed CD40-silenced DCs resulted in significantly up-regulated IL-10, IL-35, and Foxp3 expression, and enhanced the percentage of CD11c⁺CD40⁻ and CD4⁺CD25⁺ cells within the cervical lymph nodes compared to subcutaneous, intraperitoneal, or intravenous routes of administration.

Conclusions

We believe that this is the first report to demonstrate that regulatory DCs infiltrate into the cervical lymph nodes after intranasal administration of these cells and that intranasal administration of regulatory DCs is more effective for the induction of tolerance in the nasal mucosa than subcutaneous, intraperitoneal, or intravenous administration.

CD5 blockade enhances ex vivo CD8+ T cell activation and tumour cell cytotoxicity

CD5 is expressed on T cells and a subset of B cells (B1a). It can attenuate TCR signalling and impair CTL activation and is a therapeutic targetable tumour antigen expressed on leukemic T and B cells. However, the potential therapeutic effect of functionally blocking CD5 to increase T cell anti-tumour activity against tumours (including solid tumours) has not been explored. CD5 knockout mice show increased anti-tumour immunity: reducing CD5 on CTLs may be therapeutically beneficial to enhance the anti-tumour response. Here, we show that ex vivo administration of a function-blocking anti-CD5 MAb to primary mouse CTLs of both tumour-naïve mice and mice bearing murine 4T1 breast tumour homografts enhanced their capacity to respond to activation by treatment with anti-CD3/anti-CD28 MAbs or 4T1 tumour cell lysates. Furthermore, it enhanced TCR signalling (ERK activation) and increased markers of T cell activation, including proliferation, CD69 levels, IFN-γ production, apoptosis and Fas receptor and Fas ligand levels. Finally, CD5 function-blocking MAb treatment enhanced the capacity of CD8⁺ T cells to kill 4T1-mouse tumour cells in an ex vivo assay. These data support the potential of blockade of CD5 function to enhance T cell-mediated anti-tumour immunity.

Induction and characterization of anti-tumor endothelium immunity elicited by ValloVax therapeutic cancer vaccine

ValloVax is a placental endothelium derived vaccine which induces tissue-nonspecific antitumor immunity by blocking tumor angiogesis. To elucidate mechanisms of action, we showed that production of ValloVax, which involves treating placental endothelial cells with IFN-gamma, results in upregulation of HLA and costimulatory molecules. It was shown that in mixed lymphocyte reaction, ValloVax induces Type I cytokines and allo-proliferative responses. Plasma from ValloVax immunized mice was capable of killing in vitro tumor-like endothelium but not control endothelium. Using defined antigens associated with tumor endothelial cells, specific molecular entities were identified as being targeted by ValloVax induced antibodies. Binding of predominantly IgG antibodies to ValloVax cells was confirmed by flow cytometry. Further suggesting direct killing of tumor endothelial cells was expression of TUNEL positive cells, as well as, reduction in tumor oxygenation. Supporting a role for antibody mediated responses, cell depletion experiments suggested a predominant role of B cells in maintaining an intact anti-tumor endothelial response. Adoptive transfer experiments suggested that infusion of CD3+ T cells from immunized mice was sufficient to transfer tumor protection. Generation of memory T cells selective to tumor endothelial specific markers was observed. Functional confirmation of memory responses was observed in tumor rechallenge experiments. Furthermore, we observed that both PD-1 or CTLA-4 blockade augmented antitumor effects of ValloVax. These data suggest a T cell induced B cell mediated anti-tumor endothelial response and set the framework clinical trials through elucidation of mechanism of action.

Non-Covalently Functionalized of Single-Walled Carbon Nanotubes by DSPE-PEG-PEI for SiRNA Delivery

The expression of a gene can be specifically downregulated by small interfering RNA (SiRNA). Modified carbon nanotubes (CNT) can be used to protect SiRNA and facilitate its entry into cells. Regardless of that, simple and efficient functionalization of CNT is lacking. Effective SiRNA delivery can be carried out using non-covalently functionalized CNT, where non-covalent (versus covalent) functionalization is simpler and more expeditious. Non-covalently functionalized single walled carbon nanotubes (SWCNT) that include a lipopolymer are described here. Polyethylenimine (PEI) conjugated to 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-N-[amino(polyethylene glycol)-2000] (DSPE-PEG) was generated and the products used to disperse CNT to form DSPE-PEG-PEI/CNT (DGI/C), an agent capable of facilitating SiRNA delivery to cells in vitro and organs and cells in vivo.

Induction of tumor inhibitory anti-angiogenic response through immunization with interferon Gamma primed placental endothelial cells: ValloVax™

BACKGROUND

While the concept of angiogenesis blockade as a therapeutic intervention for cancer has been repeatedly demonstrated, the full promise of this approach has yet to be realized. Specifically, drugs such as VEGF-blocking antibodies or kinase inhibitors suffer from the drawbacks of resistance development, as well as off-target toxicities. Previous studies have demonstrated feasibility of specifically inducing immunity towards tumor endothelium without consequences of systemic autoimmunity in both animal models and clinical settings.

METHOD

Placenta-derived endothelial cells were isolated and pretreated with interferon gamma to enhance immunogenicity. Syngeneic mice received subcutaneous administration of B16 melanoma, 4 T1 mammary carcinoma, and Lewis Lung Carcinoma (LLC), followed by administration of control saline, control placental endothelial cells, and interferon gamma primed endothelial cells (ValloVax™). Tumor volume was quantified. An LLC metastasis model was also established and treated under similar conditions. Furthermore, a safety analysis in non-tumor bearing mice bracketing the proposed clinical dose was conducted.

RESULTS

ValloVax™ immunization led to significant reduction of tumor growth and metastasis as compared to administration of non-treated placental endothelial cells. Mitotic inactivation by formalin fixation or irradiation preserved tumor inhibitory activity. Twenty-eight day evaluation of healthy male and female mice immunized with ValloVax™ resulted in no abnormalities or organ toxicities.

CONCLUSION

Given the established rationale behind the potential therapeutic benefit of inhibiting tumor angiogenesis as a treatment for cancer, immunization against a variety of endothelial cell antigens may produce the best clinical response, enhancing efficacy and reducing the likelihood of the development of treatment resistance. These data support the clinical evaluation of irradiated ValloVax™ as an anti-angiogenic cancer vaccine.

Synergic silencing of costimulatory molecules prevents cardiac allograft rejection

Background

While substantial progress has been made in blocking acute transplant rejection with the advent of immune suppressive drugs, chronic rejection, mediated primarily by recipient antigen presentation, remains a formidable problem in clinical transplantation. We hypothesized that blocking co-stimulatory pathways in the recipient by induction of RNA interference using small interference RNA (siRNA) expression vectors can prolong allogeneic heart graft survival.

Method

Vectors expressing siRNA specifically targeting CD40 and CD80 were prepared. Recipients (BALB/c mice) were treated with CD40 and/or CD80 siRNA expression vectors via hydrodynamic injection. Control groups were injected with a scrambled siRNA vector and sham treatment (PBS). After treatment, a fully MHC-mismatched (BALB/c to C57/BL6) heart transplantation was performed.

Result

Allogeneic heart graft survival (>100 days) was approximately 70% in the mice treated simultaneously with CD40 and CD80 siRNA expression vectors with overall reduction in lymphocyte interstitium infiltration, vascular obstruction, and edema. Hearts transplanted into CD40 or CD80 siRNA vector-treated recipients had an increased graft survival time compared to negative control groups, but did not survive longer than 40 days. In contrast, allogenic hearts transplanted into recipients treated with scrambled siRNA vector and PBS stopped beating within 10–16 days. Real-time PCR (RT-PCR) and flow cytometric analysis showed an upregulation of FoxP3 expression in spleen lymphocytes and a concurrent downregulation of CD40 and CD80 expression in splenic dendritic cells of siRNA-treated mice. Functional suppressive activity of splenic dendritic cells (DCs) isolated from tolerant recipients was demonstrated in a mixed lymphocyte reaction (MLR). Furthermore, DCs isolated from CD40- and CD80-treated recipients promoted CD4 + CD25 + FoxP3+ regulatory T cell differentiation in vitro.

Conclusion

This study demonstrates that the simultaneous silencing of CD40 and CD80 genes has synergistic effects in preventing allograft rejection, and may therefore have therapeutic potential in clinical transplantation.

BML-11, a lipoxin receptor agonist, protected carbon tetrachloride-induced hepatic fibrosis in rats

Inflammation plays an important role in the occurrence and development of fibrosis. Lipoxins (LXs) and BML-111 (lipoxin A4 agonist) have been approved for potent anti-inflammatory properties. Previously, we and others had showed LXs and BML-111 could protect acute hepatic injury, inhibit the growth and invasion of hepatic tumor. However, there are few reports dealing with their effects on hepatic fibrosis. To explore whether LXs and the analog could interrupt the process of hepatic fibrosis, the effects of BML-111 on tetrachloride-induced hepatic fibrosis were observed and the possible mechanism were discussed. Sprague-Dawley rats were induced liver fibrosis by carbon tetrachloride (CCl4) for 10 weeks with or without BML-111, and the histopathology and collagen content were employed to quantify hepatic necro-inflammation and fibrosis. Moreover, the expression levels of α-smooth muscle actin (α-SMA), transforming growth factor-β1 (TGF-β1), and platelet-derived growth factor (PDGF) were examined via Western blot or ELISA. Rats treated with BML-111 improved hepatic necro-inflammation and inhibited hepatic fibrosis in association with reduction of α-SMA expression and decreased collagen deposition. Furthermore, BML-111 could downregulate the expressions of TGF-β1 and PDGF significantly. BML-111 played a critical protective role in CCl4-induced hepatic fibrosis through inhibiting the levels of TGF-β1 and PDGF in rats.

Non-covalently functionalized single-walled carbon nanotube for topical siRNA delivery into melanoma

RNAi can specifically regulate gene expression, but efficient delivery of siRNA in vivo is difficult while it has been shown that modified carbon nanotubes (CNT) protect siRNA, facilitate entry into cells and enhance transdermal drugs delivery. Single-walled carbon nanotubes (SWCNT) were functionalized non-covalently with succinated polyethyleimine (PEI-SA). In this study, the water soluble CNT, PEI-SA/CNT (IS/C) were isolated and characterized, the gene silencing induced by IS/C/siRNA complexes was achieved in vitro in B16-F10 cells. In vivo delivery was topically applied to shaved mouse skin, as well as topically to a C57BL/6 mice melanoma model. We found significant uptake of Cy3-labeled siRNA specific to Braf (siBraf) and gene silencing in the tumor tissue. Treatment with IS/C/siBraf resulted in attenuation of tumor growth over a 25-day period. This new delivery method has provided a new possibility for future siRNA delivery and therapy, which providing insight for the potential application and development of CNT-based siRNA delivery.

A novel in vivo siRNA delivery system specifically targeting liver cells for protection of ConA-induced fulminant hepatitis

Background

Fulminant hepatitis progresses to acute liver failure (ALF) when the extent of hepatocyte death exceeds the liver's regenerative capacity. Although small interfering RNA (siRNA) appears promising in animal models of hepatitis, the approach is limited by drawbacks associated with systemic administration of siRNA. The aim of this study is to develop a hepatocyte-specific delivery system of siRNA for treatment of fulminant hepatitis.

Methodology/Principal Findings

Galactose-conjugated liposome nano-particles (Gal-LipoNP) bearing siRNA was prepared, and the particle size and zeta potential of Gal-LipoNP/siRNA complexes were measured. The distribution, cytotoxicity and gene silence efficiency were studied in vivo in a concanavalin A (ConA)-induced hepatitis model. C57BL/6 mice were treated with Gal-LipoNP Fas siRNA by i.v. injection 72 h before ConA challenge, and hepatocyte injury was evaluated using serum alanine transferase (ALT) and aspartate transaminase (AST) levels, as well as liver histopathology and TUNEL-positive hepatocytes. The galactose-ligated liposomes were capable of encapsulating >96% siRNA and exhibited a higher stability than naked siRNA in plasma. Hepatocyte-specific targeting was confirmed by in vivo delivery experiment, in which the majority of Gal-LipoNP-siRNA evaded nuclease digestion and accumulated in the liver as soon as 6 h after administration. In vivo gene silencing was significant in the liver after treatment of Gal-Lipo-siRNA. In the ConA-induced hepatitis model, serum levels of ALT and AST were significantly reduced in mice treated with Gal-lipoNP-siRNA as compared with control mice. Additionally, tissue histopathology and apoptosis showed an overall reduction of injury in the Gal-LipoNP siRNA-treated mice.

Conclusions/Significance

This study is the first to our knowledge to demonstrate reduction of hepatic injury by liver-specific induction of RNA interference using Gal-LipoNP Fas siRNA, highlighting a novel RNAi-based therapeutic potential in many liver diseases.

Double negative Treg cells promote nonmyeloablative bone marrow chimerism by inducing T-cell clonal deletion and suppressing NK cell function

The establishment of immune tolerance and prevention of chronic rejection remain major goals in clinical transplantation. In bone marrow (BM) transplantation, T cells and NK cells play important roles for graft rejection. In addition, graft-versus-host-disease (GVHD) remains a major obstacle for BM transplantation. In this study, we aimed to establish mixed chimerism in an irradiation-free condition. Our data indicate that adoptive transfer of donor-derived T-cell receptor (TCR) αβ(+) CD3(+) CD4(-) CD8(-) NK1.1(-) (double negative, DN) Treg cells prior to C57BL/6 to BALB/c BM transplantation, in combination with cyclophosphamide, induced a stable-mixed chimerism and acceptance of C57BL/6 skin allografts but rejection of third-party C3H (H-2k) skin grafts. Adoptive transfer of CD4(+) and CD8(+) T cells, but not DN Treg cells, induced GVHD in this regimen. The recipient T-cell alloreactive responsiveness was reduced in the DN Treg cell-treated group and clonal deletions of TCRVβ2, 7, 8.1/2, and 8.3 were observed in both CD4(+) and CD8(+) T cells. Furthermore, DN Treg-cell treatment suppressed NK cell-mediated BM rejection in a perforin-dependent manner. Taken together, our results suggest that adoptive transfer of DN Treg cells can control both adoptive and innate immunities and promote stable-mixed chimerism and donor-specific tolerance in the irradiation-free regimen.

Establishment of nonmyeloablative bone marrow chimerism by double negative Treg cells through inducing T cell clonal deletion and suppressing NK cell function (126.1)

In bone marrow transplantation, T cells and NK cells play important role for graft rejection. In addition, graft-versus-host-disease and establishment of stable chimeric states without complete marrow ablation remain as major obstacles post bone marrow transplantation. In this study, we aimed to establish mixed chimerism in a non-irradiation condition. Our data indicate that adoptive transfer of donor-derived TCRαβ+CD3+CD4-CD8-NK1.1-(double negative, DN) Treg cells prior to C57BL/6 to BALB/c bone marrow transplantation, in combination with cyclophosphamide but not cyclosporine, FK506, or rapamycin, established stable mixed chimerism that led to acceptance of C57BL/6 skin allografts and rejection of 3rd party C3H skin grafts. Adoptive transfer of CD4+ and CD8+ T cells, but not DN-Treg cells, induced graft-versus-host diseases in this regimen. The recipient T cell alloreacitve responsiveness was reduced in the DN-Treg cell-treated group and T cell receptor Vβ2, Vβ7 and Vβ8 clonal deletions were observed in both CD4+ and CD8+ T cells. Furthermore, DN-Treg cell treatment suppressed NK cell-mediated donor bone marrow rejection in perforin-dependent manner. Taken together, our results suggest that adoptive transfer of DN-Treg cells can control both adoptive and innate immunity and promote a stable mixed chimerism and donor-specific tolerance in the non-irradiation regimen.

Gene silencing of IL-12 in dendritic cells inhibits autoimmune arthritis

Background

We have previously demonstrated that immune modulation can be accomplished by administration of gene silenced dendritic cells (DC) using siRNA. In this study, we demonstrate the therapeutic utilization of shRNA-modified DC as an antigen-specific tolerogenic vaccine strategy for autoimmune arthritis.

Methods

A shRNA that specifically targets IL-12 p35 was designed and cloned into a plasmid vectors (IL-12 shRNA). Bone marrow-derived DC from DBA/1 mice were transfected with the IL-12 shRNA construct in vitro. Mice with collagen II (CII)-induced arthritis (CIA) were treated with the modified DCs expressing the shRNA. Recall response and disease progression were assessed.

Results

After gene silencing of IL-12 in DC, DC were shown to selectively inhibit T cell proliferation on recall responses and in an MLR. In murine CIA, we demonstrated that administration of IL-12 shRNA-expressing DC that were pulsed with CII inhibited progression of arthritis. The therapeutic effects were evidenced by decreased clinical scores, inhibition of inflammatory cell infiltration in the joint, and suppression of T cell and B cell responses to CII.

Conclusion

We demonstrate a novel tolerance-inducing protocol for the treatment of autoimmune inflammatory joint disease in which the target antigen is known, utilizing DNA-directed RNA interference.

Prevention of hyperglycemia-induced myocardial apoptosis by gene silencing of Toll-like receptor-4

Background

Apoptosis is an early event involved in cardiomyopathy associated with diabetes mellitus. Toll-like receptor (TLR) signaling triggers cell apoptosis through multiple mechanisms. Up-regulation of TLR4 expression has been shown in diabetic mice. This study aimed to delineate the role of TLR4 in myocardial apoptosis, and to block this process through gene silencing of TLR4 in the myocardia of diabetic mice.

Methods

Diabetes was induced in C57/BL6 mice by the injection of streptozotocin. Diabetic mice were treated with 50 μg of TLR4 siRNA or scrambled siRNA as control. Myocardial apoptosis was determined by TUNEL assay.

Results

After 7 days of hyperglycemia, the level of TLR4 mRNA in myocardial tissue was significantly elevated. Treatment of TLR4 siRNA knocked down gene expression as well as diminished its elevation in diabetic mice. Apoptosis was evident in cardiac tissues of diabetic mice as detected by a TUNEL assay. In contrast, treatment with TLR4 siRNA minimized apoptosis in myocardial tissues. Mechanistically, caspase-3 activation was significantly inhibited in mice that were treated with TLR4 siRNA, but not in mice treated with control siRNA. Additionally, gene silencing of TLR4 resulted in suppression of apoptotic cascades, such as Fas and caspase-3 gene expression. TLR4 deficiency resulted in inhibition of reactive oxygen species (ROS) production and NADPH oxidase activity, suggesting suppression of hyperglycemia-induced apoptosis by TLR4 is associated with attenuation of oxidative stress to the cardiomyocytes.

Conclusions

In summary, we present novel evidence that TLR4 plays a critical role in cardiac apoptosis. This is the first demonstration of the prevention of cardiac apoptosis in diabetic mice through silencing of the TLR4 gene.

Safety evaluation of allogeneic umbilical cord blood mononuclear cell therapy for degenerative conditions

Background

The current paradigm for cord blood transplantation is that HLA matching and immune suppression are strictly required to prevent graft versus host disease (GVHD). Immunological arguments and historical examples have been made that the use of cord blood for non-hematopoietic activities such as growth factor production, stimulation of angiogenesis, and immune modulation may not require matching or immune suppression.

Methods

114 patients suffering from non-hematopoietic degenerative conditions were treated with non-matched, allogeneic cord blood. Doses of 1-3 × 10⁷ cord blood mononuclear cells per treatment, with 4-5 treatments both intrathecal and intravenously were performed. Adverse events and hematological, immunological, and biochemical parameters were analyzed for safety evaluation.

Results

No serious adverse effects were reported. Hematological, immunological, and biochemical parameters did not deviate from normal ranges as a result of therapy.

Conclusion

The current hematology-based paradigm of need for matching and immune suppression needs to be revisited when cord blood is used for non-hematopoietic regenerative purposes in immune competent recipients.

A novel allergen-specific therapy for allergy using CD40-silenced dendritic cells

BACKGROUND

Induction of RNA interference with small interfering RNA (siRNA) has demonstrated therapeutic potential through the knockdown of target genes. We have previously reported that systemic administration of CD40 siRNA is capable of attenuating allergic symptoms but in an allergen-nonspecific fashion. However, siRNA-based allergen-specific therapy for allergy has not been developed.

OBJECTIVE

We attempted to develop a new allergen-specific therapy for allergy using CD40-silenced and allergen-pulsed dendritic cells (DCs).

METHODS

Bone marrow-derived DCs were silenced with CD40 siRNA and pulsed with ovalbumin (OVA). Mice had allergy after intraperitoneal sensitization with OVA and keyhole limpet hemocyanin, followed by intranasal challenge with the same allergens. The mice were treated with CD40-silenced and OVA-pulsed DCs (CD40-silenced OVA DCs) either before allergic sensitization or after establishing allergic rhinitis.

RESULTS

Mice receiving CD40-silenced OVA DCs either before or after the establishment of allergic rhinitis showed remarkable reductions in allergic symptoms caused by OVA challenge, as well as anti-OVA IgE levels in sera. Additionally, CD40-silenced OVA DCs suppressed eosinophil infiltration at the nasal septum, OVA-specific T-cell responses, T-cell production of IL-4 and IL-5 after stimulation with OVA, and CD4(+)CD25(-) effector T-cell responses. Furthermore, CD40-silenced OVA DCs facilitated the generation of CD4(+)CD25(+) forkhead box protein 3-positive OVA-specific regulatory T cells, which inhibit allergic responses in vivo. However, CD40-silenced OVA DCs suppressed only OVA-specific allergy but did not inhibit keyhole limpet hemocyanin-induced allergy, suggesting that CD40-silenced OVA DCs induce allergen-specific tolerance.

CONCLUSIONS

This study is the first to demonstrate a novel allergen-specific therapy for allergy through DC-mediated immune modulation after gene silencing of CD40.

RNAi-mediated CD40-CD154 interruption promotes tolerance in autoimmune arthritis

INTRODUCTION

We have previously demonstrated that ex vivo inhibition of costimulatory molecules on antigen-pulsed dendritic cells (DCs) can be useful for induction of antigen-specific immune deviation and suppression of autoimmune arthritis in the collagen induced arthritis (CIA) model. The current study evaluated a practical method of immune modulation through temporary systemic inhibition of the costimulatory molecule CD40.

METHODS

Mice with collagen II (CII)-induced arthritis (CIA) were administered siRNA targeting the CD40 molecule. Therapeutic effects were evaluated by clinical symptoms, histopathology, Ag-specific T cell and B cell immune responses.

RESULTS

Systemic administration of CD40-targeting siRNA can inhibit antigen-specific T cell response to collagen II, as well as prevent pathogenesis of disease in both a pre- and post-immunization manner in the CIA model. Disease amelioration was associated with suppression of Th1 cytokines, attenuation of antibody production, and upregulation of T regulatory cells.

CONCLUSIONS

These studies support the feasibility of transient gene silencing at a systemic level as a mechanism of resetting autoreactive immunity.

siRNA specific delivery system for targeting dendritic cells

siRNA therapy offers immense potential for clinical application. Under physiological conditions, however, siRNA was demonstrated to have a short half-life. Additionally, it may also cause ubiquitous gene silencing as it does not possess a tissue-specific homing mechanism. Thus, the rate-limiting step in the emergence of siRNA as a potential therapeutic agent is the current lack of a safe and tissue- or cell-specific in vivo delivery system. Herein, we propose a novel, cell-specific method for the in vivo delivery of siRNA to dendritic cells (DCs) with the purpose of inducing immune modulation. CD40 siRNA was incorporated within the interior of 86 nm liposomes, which were decorated with surface-bound mAb NLDC-145 as a targeting mechanism. The siRNA encapsulation efficiency was determined to be approximately 7%. CD40 siRNA immunoliposomes (CD40 siILs) were able to specifically bind to DCs and silence CD40 expression in vitro. Furthermore, in vitro CD40-silenced DCs significantly inhibited the proliferation of alloreactive T cells in an MLR. Upon in vivo administration, siIL-encapsulated, Cy3-labeled siRNA exhibited moderate uptake by the liver at an early time point following administration with greater accumulation in the spleen at a later time point. In contrast, naked siRNA primarily accumulated in the kidney immediately after administration and circulated out in a short time period. To address in vivo gene silencing and immune modulation, mice were simultaneously immunized with KLH and subcutaneously injected with DC-specific CD40 siILs, siILs containing negative control siRNA, naked CD40 siRNA, or PBS. A second injection of CD40 siILs, or control treatments, followed 24 h later. Flow cytometry, reverse transcriptase PCR, and quantitative real-time PCR analysis of CD11c(+) DCs from mice treated with CD40 siILs demonstrated reduced expression of CD40, in comparison with control groups. CD11c(-) cells were also analyzed by flow cytometry, but no differences were observed between treatment groups. Furthermore, CD40 siIL-treated mice were found to have an increased proportion of Treg cells (CD4(+)CD25(+) FoxP3(+)), and DCs cells from these mice were able to inhibit T cell proliferation in an antigen-specific recall response. In summary, CD40 siILs were shown to specifically target and deliver CD40 siRNA to DCs, significantly reducing CD40 expression and resulting in DC-mediated immune modulation as well as generation of Treg cells. These findings highlight the therapeutic potential for siRNA-based and DC-mediated immunotherapy in the clinic. To the best of our knowledge, this is the first study to use siILs for targeted delivery of siRNA to DCs and for immune modulation.

Preventing immune rejection through gene silencing

Dendritic cells (DCs) comprise a family of professional antigen-presenting cells responsible for the induction of primary immune responses. DCs are also important for the induction of immunological tolerance. Recent research has revealed that DC maturation is associated with activation of the NF-kappaB pathway. RelB, one of the five families of Rel proteins involved in the NF-kappaB pathway, plays a critical role in coordinating the terminal stages of DC maturation and has the ability to induce optimal Th1 T cell responses. DCs generated from mouse bone marrow can be silenced using siRNA specific for the target gene. Silencing RelB in DCs will result in the generation of immunoregulatory dendritic cells that inhibit allogenic T cell responses. The KLH-specific T cell response should also be inhibited after the RelB siRNA treatment. Furthermore, silencing the RelB gene in DCs can generate regulatory T cells. Administering donor-derived RelB-silencing DCs can prevent allograft rejection in murine heart transplantation.

Preventing tissue injury using siRNA

RNA interference (RNAi) is a process through which double-stranded RNA induces the activation of endogenous cellular pathways of RNA degradation, resulting in selective and potent silencing of genes that have homology to the double strand. Much of the excitement surrounding small interfering RNA (siRNA)-mediated therapeutics arises from the fact that this approach overcomes many of the shortcomings previously experienced with alternative approaches to selective blocking that use antibodies, antisense oligonucleotides or pharmacological inhibitors. Induction of RNAi through administration of siRNA has been successfully applied to the treatment of hepatitis, viral infections, and cancer. Increased success in addressing issues of siRNA delivery and efficiency will permit this approach to evolve as a new paradigm in clinical therapeutics. In this chapter, we present applications of RNAi in tissue injury, and the possibilities of using this highly promising approach in the context of transplantation.

Non-expanded adipose stromal vascular fraction cell therapy for multiple sclerosis

The stromal vascular fraction (SVF) of adipose tissue is known to contain mesenchymal stem cells (MSC), T regulatory cells, endothelial precursor cells, preadipocytes, as well as anti-inflammatory M2 macrophages. Safety of autologous adipose tissue implantation is supported by extensive use of this procedure in cosmetic surgery, as well as by ongoing studies using in vitro expanded adipose derived MSC. Equine and canine studies demonstrating anti-inflammatory and regenerative effects of non-expanded SVF cells have yielded promising results. Although non-expanded SVF cells have been used successfully in accelerating healing of Crohn's fistulas, to our knowledge clinical use of these cells for systemic immune modulation has not been reported. In this communication we discuss the rationale for use of autologous SVF in treatment of multiple sclerosis and describe our experiences with three patients. Based on this rationale and initial experiences, we propose controlled trials of autologous SVF in various inflammatory conditions.

Human embryonic stem cells hemangioblast express HLA-antigens

Background

It has been suggested that the initial differentiation of endothelial and hematopoietic cells during embryogenesis occurs from a common progenitor, called hemangioblast (hB). We hypothesized that these cells with dual hematopoietic/endothelial potential could be used in future regenerative medicine.

Methods

We used the two-step differentiation technology to generate bipotential blast cells from human embryonic stem cells (hES). This involved short differentiation in our in vitro EB system followed by differentiation in semisolid culture medium supplemented with mixture of cytokines.

Results

The occurrence of blast-colony-forming cells (BL-CFC) during EB differentiation (day 0–6) was transient and peaked on day 3. The emergence of this event was associated with expression of mesoderm gene T, and inversely correlated with expression of endoderm gene FoxA2. Similarly, the highest BL-CFC number was associated with increase in expression of early hematopoietic/endothelial genes: CD34, CD31 and KDR. The derived colonies were composed of 30–50 blast cells on day 6 in culture. These cells had homogenous appearance in Wright-Giemsa stain, but to a different extent expressed markers of immature hematopoietic and endothelial cells (CD31, CD34, VE-cadherin, Flt-1) and mature differentiated cells (CD45, CD33, CD146). We found that some of them expressed fetal and embryonic globin genes. Interestingly, these cells expressed also HLA class I molecules, however at very low levels compared to endothelial and hematopoietic cells. The blast cells could be successfully differentiated to hematopoietic cells in a CFU assay. In these conditions, blast cells formed CFU-M colonies (63.4 ± 0.8%) containing macrophages, BFU-E colonies (19.5 ± 3.5%) containing nucleated red blood cells, and CFU-EM colonies (17.1 ± 2.7%) composed of macrophages and nucleated erythrocytes. Cells of CFU-EM and BFU-E colonies expressed both ε – and γ- globin genes, but not adult-type γ-globin. When in endothelial cell culture conditions, blast cells differentiated to endothelial cells which had the ability to take up Dil-Ac-LDL and to form complex vascular networks in Matrigel.

Conclusion

1) Hematoendothelial precursors exist transiently in early embryonic development and form single cell-derived colonies; 2) their differentiation can be tracked by the use of chosen molecular markers; 3) blast colonies consist of cells having properties of endothelial and hematopoietic precursors, however the issue of their ability to maintain dual properties over time needs to be further explored; 4) blast cells can potentially be used in regenerative medicine due to their low expression of HLA molecules.

Inhibition of intracranial glioma growth by endometrial regenerative cells

Animal studies have demonstrated that selective tropism of mesenchymal stem cells (MSC) for glioma may be used as a means of selective delivery of cytotoxic payloads. Endometrial Regenerative Cells (ERC) are a population of mesenchymal-like cells which possesse pluripotent differentiation capacity and is characterized by unique surface markers and growth factor production. In this study we sought to determine whether unmanipulated ERC would alter the growth of glioma using the aggressive C6/LacZ7 (C6) into Sprague Dawley rat model. ERC administration by intravenous (i.v.) or intratumoral (i.t.) showed significant inhibition of glioma: volume reduction of 49% after i.v. treatment (p < 0.05), and about 46% i.t. treatment (p < 0.05). Tumor reduction was associated with inhibition of angiogenesis and reduced numbers of CD133 positive cells in the incranial tumor. Despite the angiogenic potential of ERC in the hindlimb ischemia model, these data support a paradoxical tumor inhibitory activity of ERC. Further studies are needed to determine the qualitative differences between physiological angiogenesis, which seems to be supported by ERC and tumor angiogenesis which appeared to be inhibited.

Feasibility investigation of allogeneic endometrial regenerative cells

Endometrial Regenerative Cells (ERC) are a population of mesenchymal-like stem cells having pluripotent differentiation activity and ability to induce neoangiogenesis. In vitro and animal studies suggest ERC are immune privileged and in certain situations actively suppress ongoing immune responses. In this paper we describe the production of clinical grade ERC and initial safety experiences in 4 patients with multiple sclerosis treated intravenously and intrathecally. The case with the longest follow up, of more than one year, revealed no immunological reactions or treatment associated adverse effects. These preliminary data suggest feasibility of clinical ERC administration and support further studies with this novel stem cell type.

NK cells induce apoptosis in tubular epithelial cells and contribute to renal ischemia-reperfusion injury

Renal ischemia-reperfusion injury (IRI) can result in acute renal failure with mortality rates of 50% in severe cases. NK cells are important participants in early-stage innate immune responses. However, their role in renal tubular epithelial cell (TEC) injury in IRI is currently unknown. Our data indicate that NK cells can kill syngeneic TEC in vitro. Apoptotic death of TEC in vitro is associated with TEC expression of the NK cell ligand Rae-1, as well as NKG2D on NK cells. In vivo following IRI, there was increased expression of Rae-1 on TEC. FACS analyses of kidney cell preparations indicated a quantitative increase in NKG2D-bearing NK cells within the kidney following IRI. NK cell depletion in wild-type C57BL/6 mice was protective, while adoptive transfer of NK cells worsened injury in NK, T, and B cell-null Rag2(-/-)gamma(c)(-/-) mice with IRI. NK cell-mediated kidney injury was perforin (PFN)-dependent as PFN(-/-) NK cells had minimal capacity to kill TEC in vitro compared with NK cells from wild-type, FasL-deficient (gld), or IFN-gamma(-/-) mice. Taken together, these results demonstrate for the first time that NK cells can directly kill TEC and that NK cells contribute substantially to kidney IRI. NK cell killing may represent an important underrecognized mechanism of kidney injury in diverse forms of inflammation, including transplantation.

Novel vaccination for allergy through gene silencing of CD40 using small interfering RNA

Small interfering RNA (siRNA) is a potent means of inducing gene-specific silencing. Gene silencing strategies using siRNA have demonstrated therapeutic benefits in animal models of various diseases, and are currently in clinical trials. However, the utility of gene silencing as a treatment for allergic diseases has not yet been reported. In this study, we report a novel therapy for allergy through gene silencing of CD40, a critical costimulatory molecule and a key factor in allergic immune responses. Silencing CD40 resulted in generation of immunoregulatory dendritic cells (DCs). Administration of CD40 siRNA remarkably reduced nasal allergic symptoms and local eosinophil accumulation in the OVA-induced allergic mice. The OVA-specific T cell response was inhibited after the CD40 siRNA treatment. Additionally, anti-OVA specific IgE and production of IL-4 and IL-5 of T cells stimulated by OVA were significantly decreased in CD40 siRNA-treated mice. Furthermore, we demonstrated that the therapeutic effects by CD40 siRNA were associated with impaired Ag-presenting functions of DCs and B cells, and generation of regulatory T cells. The present study highlights a therapeutic potential of siRNA-based treatment for allergic diseases.

Gene silencing of complement C5a receptor using siRNA for preventing ischemia/reperfusion injury

Ischemia/reperfusion (I/R) injury in organ transplantation significantly contributes to graft failure and is untreatable using current approaches. I/R injury is associated with activation of the complement system, leading to the release of anaphylatoxins, such as C5a, and the formation of the membrane attack complex. Here, we report a novel therapy for kidney I/R injury through silencing of the C5a receptor (C5aR) gene using siRNA. Mice were injected with 50 microg of C5aR siRNA 2 days before induction of ischemia. Renal ischemia was then induced through clamping of the renal vein and artery of the left kidney for 25 minutes. The therapeutic effects of siRNA on I/R were evaluated by assessment of renal function, histopathology, and inflammatory cytokines. siRNA targeting C5aR efficiently inhibited C5aR gene expression both in vitro and in vivo. Administering C5aR siRNA to mice preserved renal function from I/R injury, as evidenced by reduced levels of serum creatinine and blood urea nitrogen in the treated groups. Inhibition of C5aR also diminished in vivo production of the pro-inflammatory cytokine tumor necrosis factor-alpha and chemokines MIP-2 and KC, resulting in the reduction of neutrophils influx and cell necrosis in renal tissues. This study demonstrates that siRNA administration represents a novel approach to preventing renal I/R injury and may be used in a variety of clinical settings, including transplantation and acute tubular necrosis.

Exosomes as a tumor immune escape mechanism: possible therapeutic implications

Advances in cancer therapy have been substantial in terms of molecular understanding of disease mechanisms, however these advances have not translated into increased survival in the majority of cancer types. One unsolved problem in current cancer therapeutics is the substantial immune suppression seen in patients. Conventionally, investigations in this area have focused on antigen-nonspecific immune suppressive molecules such as cytokines and T cell apoptosis inducing molecules such as Fas ligand. More recently, studies have demonstrated nanovesicle particles termed exosomes are involved not only in stimulation but also inhibition of immunity in physiological conditions. Interestingly, exosomes secreted by cancer cells have been demonstrated to express tumor antigens, as well as immune suppressive molecules such as PD-1L and FasL. Concentrations of exosomes from plasma of cancer patients have been associated with spontaneous T cell apoptosis, which is associated in some situations with shortened survival. In this paper we place the "exosome-immune suppression" concept in perspective of other tumor immune evasion mechanisms. We conclude by discussing a novel therapeutic approach to cancer immune suppression by extracorporeal removal of exosomes using hollow fiber filtration technology

Generation of therapeutic dendritic cells and regulatory T cells for preventing allogeneic cardiac graft rejection

Tolerogenic dendritic cells (Tol-DCs) and regulatory T cells (Treg) are key factors in the induction and maintenance of transplantation tolerance. We previously demonstrated that ex vivo-isolated Tol-DCs promote Treg generation, and vice versa, in an in vitro co-culture system. Here we demonstrate the occurrence of such an immune regulatory feedback loop in vivo. Tol-DC generated in vitro by treatment with LF 15-0195 exhibited features of immature DC and express low levels of MHC class II, CD86 and CD40. These Tol-DCs were capable of augmenting CD4(+)CD25(+)CTLA4(+) and FoxP3(+) Treg cell numbers and activity in cardiac allograft recipients. On the other hand, Tol-DCs possessed an ability to generate Treg cells in vitro. The adoptive transfer of these in vitro-generated Treg cells resulted in an increase of Tol-DC in vivo, suggesting that an immune regulatory feedback loop, between Tol-DC and Treg, exists in vivo. Furthermore, the administration of in vitro-generated Tol-DCs or Treg cells prevented rejection of allografts. Co-administration of Tol-DC and Treg synergized efficacy of promoting allograft survival heart transplantation. The present study highlights the therapeutic potential of preventing allograft rejection using in vitro-generated Tol-DCs and Treg.

Selective apoptosis of breast cancer cells by siRNA targeting of BORIS

Brother of the regulator of imprinted sites (BORIS) is an epigenetically acting transcription factor which represses the tumor inhibitor functions of the tumor suppressor protein CTCF. BORIS expression has not been documented in adult females, making it an exciting molecular target for drug development in breast cancer. Previously, we demonstrated that vaccination of mice with zing-finger (ZF)-deleted non-functional BORIS results in regression of breast cancer and generation of potent anti-tumor immune responses. RNAi induction can be used as an alternative approach for selective tumor cell killing. Short interfering RNA (siRNA) molecules targeting BORIS were generated and their efficacy was tested in MDA-MB-231 breast cancer and non-malignant epithelial cell lines. Treatment with BORIS-specific siRNA, but not control siRNA led to a concentration-dependent reduction in BORIS expression and proportional apoptotic death of the cancer but not control cells. To our knowledge this is first report demonstrating a critical role of BORIS in maintaining tumor cell viability.

Antigen-specific therapy of rheumatoid arthritis

BACKGROUND

Immunotherapy offers the promise of antigen-specific suppression of pathological immune responses in conditions such as autoimmunity and organ transplantation. Substantial advances have been made in recent years in terms of understanding basic immunological mechanisms of autoreactivity, as well as clinically implementing immune-based therapies that are antigen nonspecific.

OBJECTIVE

To provide an integrated overview of the current state of the art in terms of antigen-specific tolerance induction, as well as to predict future directions for the field.

METHODS

Examples of successes and failures of antigen-specific immunotherapy were sought. Particular attention was paid to the well-established collagen II-induced model of arthritis.

RESULTS/CONCLUSIONS

Previous failures of antigen-specific immunotherapy were associated with lack of identification of clinically relevant antigens, as well as inappropriate tolerogenic methodologies. The advances in proteomics combined with novel gene-specific immune modulatory techniques place today's translational researchers in a unique position to tackle the problem of antigen-specific immunotherapeutic protocols.

Immune modulation and tolerance induction by RelB-silenced dendritic cells through RNA interference

Dendritic cells (DC), the most potent APCs, can initiate the immune response or help induce immune tolerance, depending upon their level of maturation. DC maturation is associated with activation of the NF-kappaB pathway, and the primary NF-kappaB protein involved in DC maturation is RelB, which coordinates RelA/p50-mediated DC differentiation. In this study, we show that silencing RelB using small interfering RNA results in arrest of DC maturation with reduced expression of the MHC class II, CD80, and CD86. Functionally, RelB-silenced DC inhibited MLR, and inhibitory effects on alloreactive immune responses were in an Ag-specific fashion. RelB-silenced DC also displayed strong in vivo immune regulation. An inhibited Ag-specific response was seen after immunization with keyhole limpet hemocyanin-pulsed and RelB-silenced DC, due to the expansion of T regulatory cells. Administration of donor-derived RelB-silenced DC significantly prevented allograft rejection in murine heart transplantation. This study demonstrates for the first time that transplant tolerance can be induced by means of RNA interference using in vitro-generated tolerogenic DC.

A novel in vivo siRNA delivery technology for dendritic cell-specific gene silencing and immune modulation (89.5)

Silencing immune molecules, such as the costimulatory molecule CD40, using siRNA was shown to have therapeutic potential and promise in immune modulation. However, a major barrier to the clinical application of siRNA is the current lack of an effective and cell-specific delivery system. Herein, we present a new method of selectively delivering siRNA to DC in vivo using stealth immunoliposomes (SILs). CD40 siRNA-containing SILs were generated using 4 types of lipids and decorated with surface-bound, DC-specific mAbs. DC-specific binding capacity of SILs was demonstrated by fluorescence microscopy and flow cytometry. Upon treatment with CD40 siRNA-SILs, DC expression of CD40 was successfully suppressed in vitro. Administration of CD40 siRNA-SILs resulted in DC-specific tissue targeting, as evidenced by increased uptake of fluorescence-tagged siRNA. Additionally, DC from mice treated with CD40 siRNA-SILs exhibited CD40-specific gene silencing in vivo. Tolerogenic properties of DC treated with CD40 siRNA-SILs were determined by inhibition of allogeneic T cell proliferation in MLR. Furthermore, a strong in vivo immune modulation was observed in mice treated with CD40 siRNA-SILs. In conclusion, this is the first demonstration of DC-specific siRNA delivery and gene silencing in vivo, which highlights the potential of DC-mediated immune modulation and the feasibility of siRNA-based clinical therapy.

A Novel Immune-Based Cancer Therapy Using Gene-Silenced Dendritic Cells (48.8)

Hyporesponsiveness is a major hallmark in dendritic cells (DC)-mediated anticancer immunotherapy. Indoleamine 2, 3-dioxygenase (IDO), an immunosuppressive molecule expressed by DC, is a critical factor mediating hyporesponsiveness to cancer immune therapy. We hypothesized that silencing of IDO in DC using siRNA would enhance anticancer therapy. In this study, DC were cultured in vitro, exposed to melanoma B16 lysate, silenced with IDO siRNA, and injected into C57/BL6 mice. Mice were then challenged with B16 tumor cells. The anticancer effects of IDO-silenced DC therapy, compared with non-silenced, conventional control DC vaccine, were evidenced by

postponed melanoma tumor onset time, anddecreased tumor size.

In addition, after immunization with IDO-silenced DC, the number of CD8+ T cells was significantly increased while CD4+ and CD8+ T cell apoptosis in draining lymph nodes was remarkably reduced. Furthermore, immunization with IDO-silenced DC enhanced tumor antigen-specific T cell proliferation and CTL activity, and decreased numbers of CD4+CD25+FoxP3+ regulatory T cells (Treg). In conclusion, this study is the first to demonstrate a novel anti-tumor vaccine by silencing an immunosuppressive gene (IDO) in DC, which enhanced anti-tumor immunity, reduced T cell apoptosis and Treg cell formation, and prevented tumor growth. IDO-silenced DC have clinical potential as an immune-based therapy.

Antitumor Effect of Large Doses IL-2-Activated HLA Haploidentical Peripheral Blood Stem Cells on Refractory Metastatic Solid Tumor Treatment

OBJECTIVE

The traditional immunotherapy for patients with refractory metastatic solid tumors is limited because tumors induce immunosuppression. New treatment is, therefore, needed. The aim of this study was to evaluate the clinical efficacy of infusion of high-dose interleukin (IL)-2-activated allogeneic haploidentical peripheral blood stem cells (haplo-PBSCTs) on patients with an advanced stage of refractory solid tumors.

METHODS

This study involved 11 patients with refractory metastatic tumors and haploidentical relatives as donors for haplo-PBSCs. The therapeutic outcome of the IL-2-activated haplo-PBSC infusion and patients' cytokine levels were evaluated. The cytotoxicity of IL-2-activated haplo-PBSCs for tumor cells was determined using in vitro cytotoxicity assays.

RESULTS

A range from 2.5 to 5.6 x 10(10) of activated haplo-PBSCs were harvested after exposure to rhIL-2, along with a significant increase in the proportion of natural killer (NK) cells and activated lymphocytes (CD69+ and CD25+), and enhanced cytotoxicity of haplo-PBSCs for several tumor cell lines. Following treatment, 1 (1/11) patient achieved a partial response (PR), 1 (1/11) achieved a mild response (MR), 6 (6/11) achieved stable disease (SD), and 3 (3/11) achieved progressive disease (PD). For all of the 11 patients, the median progression-free survival (PFS) was 5 months (3-14 months). We also observed the phenomenon of Th2 shifted to Th1, which played a crucial role in cancer immunotherapy.

CONCLUSIONS

The adoptive transfusion of IL-2-activated haplo-PBSCs has potent antitumor effects both in vitro and in vivo. This finding suggests that IL-2-activated haplo-PBSCs may serve as an alternative therapy for advanced-stage solid tumors, especially for those patients who are refractory or ineligible for chemo- or radiotherapy.

Immune modulation through silencing CD80 and CD86 in dendritic cells using siRNA (88.4)

Dendritic cells (DC) are central cells of the immune system that can stimulate or suppress immune responses, partially depending on their expression of costimulatory molecules. CD80 and CD86 are critical costimulatory molecules for both T cell responses and Th differentiation. Thus, silencing DC expression of CD80 and CD86, using siRNA, could potentially enable manipulation of immune responses. Since silencing of CD80 or CD86 in DC has not been reported, in this study we investigated the tolerogenesis and Th differentiation capacity of CD80/CD86 in DC after siRNA-mediated gene silencing. Gene silencing was performed by transfecting mouse bone marrow-derived DC with CD80 or CD86 siRNA. The gene silencing efficacy was measured by flow cytometry, RT-PCR, and real time PCR. DC that were transfected with CD80 or CD86 siRNA induced inhibition of T cell responses in MLR and generated T regulatory cells. The CD4+CD25+FoxP+ cell subset was significantly increased in a co-culture system that contained CD80- or CD86-silenced DC and allogeneic T cells. Furthermore, CD80 siRNA significantly decreased IFN-gamma, although a reduction in IL-4 was not observed. Conversely, CD86 siRNA significantly reduced IL-4 but did not reduce IFN-gamma. This study suggested, for the first time, that CD80 siRNA and CD86 siRNA can be useful tools for generating tolerogenic DC with a differential effect on modulating cytokine production.

Novel therapy for allergic disease through gene silencing of CD40 (37.7)

Gene silencing is a potent, selective, and easily-inducible method for specifically blocking expression of desired genes. Gene silencing strategies have been successfully tested in animal models of various diseases. However, the therapeutic potential of gene silencing allergic diseases has not yet been reported. CD40 is an important costimulatory molecule that plays a critical role in immune responses. We attempted to develop a new therapy for allergic diseases through gene silencing using a short hairpin siRNA-expressing vector (shRNA) specific to CD40. The allergic mouse model was made by intraperitoneal immunization with ovalbumin (OVA), followed by intranasal challenges with the same antigen. CD40 shRNA was administered before or after OVA immunization. CD40 shRNA treatment reduced CD40 expression in splenic DC, remarkably reduced nasal allergic symptoms, and decreased nasal eosinophilia. The OVA-specific T cell response was inhibited after CD40 shRNA treatment. Additionally, anti-OVA specific IgE was significantly decreased in CD40-shRNA treated mice, as detected by ELISA. The production of IL-4 and IL-5 was suppressed in the CD40-shRNA treated mice. Finally, CD40 shRNA facilitated the generation of regulatory T cells, in particular, the CD4+CD25+Foxp3+ subset of cells. This study, for the first time, has demonstrated a novel therapy for allergic disease through gene silencing.

Tolerogenic Vaccination Using IL-12 Gene-Silenced Dendritic Cells for Autoimmune Arthritis (131.9)

We have recently demonstrated that dendritic cell (DC)-mediated immune modulation and deviation can be accomplished through RNA interference (RNAi), highlighting the therapeutic potential of RNAi-modified DC as antigen-specific tolerogenic vaccines. To date, an RNAi-based vaccine has not been reported. The current study was designed to develop siRNA-modified DC as antigen-specific, tolerogenic vaccines for prevention and intervention of autoimmune arthritis. Using small interfering RNA (siRNA) that specifically targets IL-12p35 gene (IL-12 siRNA), we have generated a type of DC that exhibits multiple tolerogenic characteristics. Immunization with type II collagen (CII)-pulsed and IL-12 gene-silenced DC (CII-pulsed/gene-silenced DC) resulted in antigen-specific nonresponsiveness in T cell responses. Vaccination with CII-pulsed/gene-silenced DC prevented collagen-induced arthritis (CIA) onset in a murine rheumatoid arthritis model. Furthermore, administration of CII-pulsed/gene-silenced DC was sufficient to inhibit progression of CIA. The therapeutic effects were further evidenced by decreased clinical scores, inhibited inflammatory infiltrates, and suppressed T cell and B cell responses to CII. In conclusion, this study is the first to demonstrate the therapeutic utilization of RNAi-modified DC as antigen-specific tolerogenic vaccines for autoimmune arthritis.

Identification of viruses in patients with postviral olfactory dysfunction

Objective: Causative viruses of postviral olfactory dysfunction (PVOD) have not yet been identified. The aim of this study was to investigate causative viruses in patients with PVOD.

Study Design and Methods: Nasal discharge was collected from 24 patients with PVOD. We investigated the presence of 10 viruses in nasal discharge and examined the time course, with regard to changes in olfactory dysfunction and nasal obstruction in patients with PVOD, using questionnaires, acoustic rhinometry, and olfactory tests.

Results: Rhinoviruses were detected in 10 patients by electrophoresis. Rhinoviruses were also confirmed in four patients by nucleotide sequences. Viral serotypes were identified to be human rhinovirus (HRV)‐40, HRV‐75, HRV‐78, and HRV‐80. One of the four patients complained of anosmia, whereas another complained of dysosmia. Olfactory testing did not show significant improvement at 4, 8, 11, and 24 weeks after the first visit in the four patients, although results of acoustic rhinometry significantly improved. Two of the four patients complained of olfactory dysfunction even 6 months after the first visit. Coronavirus and parainfluenza virus were detected in one patient each, and Epstein‐Barr viruses were detected in three patients.

Conclusions: This study for the first time detected rhinovirus, coronavirus, parainfluenza virus, and Epstein‐Barr virus in nasal discharge of patients with PVOD. Furthermore, the present study suggests that rhinoviruses can cause olfactory dysfunction through mechanisms other than nasal obstruction and that rhinoviruses can induce various severities and different time courses of olfactory dysfunction.

Intranasal CpG DNA therapy during allergen exposure in allergic rhinitis

OBJECTIVE

1) To estimate the effectiveness of intranasal administration of CpG DNA alone on allergic rhinitis compared with intradermal administration; and 2) to find out how CpG DNA therapy is useful in treatment of allergic rhinitis.

STUDY DESIGN

Mice were intraperitoneally sensitized and intranasally challenged with Japanese cedar. Therapy with CpG DNA alone was also performed during challenge, either intranasally or intradermally. Immunologic variables and nasal symptom were studied.

RESULTS

Intranasal administration of CpG DNA alone significantly reduced the levels of IgE, IL-5 productions from nasal lymphocytes and splenocytes, nasal eosinophilia, and nasal symptoms, although intradermal administration of CpG DNA alone showed no significant reduction.

CONCLUSION

This study demonstrated that CpG DNA has effects not only on splenocytes but also on nasal lymphocytes to attenuate allergic rhinitis, and that intranasal administration, but not intradermal administration, of CpG DNA alone during allergen exposure is useful for control of allergic rhinitis.

Preventing autoimmune arthritis using antigen-specific immature dendritic cells: a novel tolerogenic vaccine

Conventional treatments for autoimmune diseases have relied heavily on nonspecific immune suppressants, which possess a variety of adverse effects without inhibiting the autoimmune process in a specific manner. In the present study we demonstrate the effectiveness of antigen-specific, maturation-resistant, tolerogenic dendritic cells (DC) in suppressing collagen-induced arthritis, a murine model of rheumatoid arthritis. Treatment of DC progenitors with the NF-κB inhibiting agent LF 15-0195 (LF) resulted in a population of tolerogenic DC that are characterized by low expression of MHC class II, CD40, and CD86 molecules, as well as by poor allostimulatory capacity in a mixed leukocyte reaction. Administering LF-treated DC pulsed with keyhole limpet hemocyanin antigen to naïve mice resulted hyporesponsiveness specific for this antigen. Furthermore, administration of LF-treated DC to mice with collagen-induced arthritis resulted in an improved clinical score, in an inhibited antigen-specific T-cell response, and in reduced antibody response to the collagen. The efficacy of LF-treated DC in preventing arthritis was substantiated by histological examination, which revealed a significant decrease in inflammatory cell infiltration in the joints. In conclusion, we demonstrate that in vitro-generated antigen-specific immature DC may have important potential as a tolerogenic vaccine for the treatment of autoimmune arthritis.