Immune modulation by IL-10 gene transfer via viral vector and plasmid DNA: implication for gene therapy

Viral Vector Mediated Interleukin-10 Gene Transfer in Skin Allograft

BACKGROUND

Expression of genes with immunoregulatory capacity can potentially decrease rejection of allograft. According to recent studies, viral interleukin (IL)-10 can reduce immune response during allotransplantation and is one of the most promising methods for the prevention of rejection. Our study aimed to analyze the immunosuppressive potential of recombinant adenovirus-mediated rat IL-10 in rat skin allograft.

METHODS

We performed skin graft surgery 1 hour after infecting the donated skin with adenovirus-mediated rat IL-10. On day 7 postoperatively, the skin allografts were harvested, and acute rejection was graded histologically.

RESULTS

Viral IL-10 gene transfer into rat skin allografts improved graft survival and reduced acute rejections.

CONCLUSION

The results of our study suggest that the therapeutic potential of graft viral IL-10 gene transfer is an effective immunosuppressive method for preventing skin allograft rejection.

Electroporating Human Corneal Epithelial Cells With Interleukin 10 and Fas Ligand pDNA

PURPOSE

To develop an optimal electroporation protocol for plasmid (pDNA) transfection of a human corneal epithelial cell (hCEC) line and investigate the immunomodulatory capacity of interleukin 10 and Fas ligand (FasL) transfection on hCECs.

DESIGN

A controlled experimental study.

METHODS

Human corneal epithelial cells were electroporated with pDNA encoding enhanced green fluorescent protein, interleukin 10, or FasL. Supernatants were analyzed for cytokine secretion using enzyme-linked immunosorbent assay. To test potential immunosuppression, electroporated hCECs were cocultured with allogeneic peripheral blood mononuclear cells, and the supernatants analyzed for interferon γ production.

RESULTS

Maximum transfection efficiencies were obtained using optimized settings, and transgene expression was detected up to 13 days following transfection. Interleukin 10 levels peaked at day 4 and FasL at day 2 following electroporation. Coculture supernatants showed significantly lower levels of interferon γ in the modulated groups compared with control.

CONCLUSIONS

Our results demonstrate highly efficient transfection of hCECs using an optimized electroporation protocol. Interleukin 10 and FasL may provide a means of immune modulation of corneal epithelial cells.

Effects of interleukin-4 or interleukin-10 gene therapy on trinitrobenzenesulfonic acid-induced murine colitis

Background

Inflammatory bowel disease (IBD) is characterized by disturbance of pro-inflammatory cytokines and anti-inflammatory cytokines. Previous studies have demonstrated the effect of anti-inflammatory cytokines, such as interleukin-10 (IL-10) or IL-4 on IBD, but their data were controversial. This study further investigated the effect of IL-4 (IL-4), IL-10 and their combination on treatment of trinitrobenzenesulfonic acid (TNBS)-induced murine colitis.

Methods

pcDNA3.0 carrying murine IL-4 or IL-10 cDNA was encapsulated with LipofectAMINE 2000 and intraperitoneally injected into mice with TNBS-induced colitis. The levels of intestinal IL-4 and IL-10 mRNA were confirmed by quantitative-RT-PCR. Inflamed tissues were assessed by histology and expression of interferon (IFN)-γ, tumor necrosis factor (TNF)-α and IL-6.

Results

The data confirmed that IL-4 or IL-10 over-expression was successfully induced in murine colon tissues after intraperitoneal injection. Injections of IL-4 or IL-10 significantly inhibited TNBS-induced colon tissue damage, disease activity index (DAI) and body weight loss compared to the control mice. Furthermore, expression of IFN-γ, TNF-α and IL-6 was markedly blocked by injections of IL-4 or IL-10 plasmid. However, there was less therapeutic effect in mice injected with the combination of IL-4 and IL-10.

Conclusions

These data suggest that intraperitoneal injection of IL-4 or IL-10 plasmid was a potential strategy in control of TNBS-induced murine colitis, but their combination had less effect.

The effect of gene therapy using CTLA4Ig/silica-nanoparticles on canine experimental autoimmune thyroiditis

BACKGROUND

The present study aimed to determine the effect of canine CTLA4Ig on canine autoimmune thyroiditis. In a previous study, we established a canine model of autoimmune thyroiditis by immunizing normal dogs with bovine thyroglobulin. An in vitro study using recombinant CTLA4Ig revealed that this protein can inhibit the expression of Th1-type cytokines and the pro-inflammatory cytokines tested.

METHODS

As a result of the in vitro study, we constructed therapeutic CTLA4Ig/silica-nanoparticles and applied them to the treatment of experimentally induced canine autoimmune thyroiditis.

RESULTS

Gene therapy resulted in significant reductions in anti-canine-thyroglobulin autoantibody titer, anti-T4 antibody titer and T-cell proliferation against thyroglobulin and in the mRNA expressions of interleukin-18 in fresh peripheral blood mononuclear cells (PBMC) from all dogs. There was also a significant reduction compared to day 0 in tumor necrosis factor-alpha and interferon-gamma levels in the supernatant from cultured PBMC.

CONCLUSIONS

The CTLA4Ig-induced suppression of Th1 cytokines is relatively more significant than it appears because autoimmune thyroiditis is a Th1-polarized disease. Thus, CTLA4Ig can improve Th1/Th2 cytokine balance in autoimmune thyroiditis by downregulating Th1 cytokines.

Co-delivery of plasmid-encoded cytokines modulates the immune response to a DNA vaccine delivered by in vivo electroporation

In this study, in vivo electroporation of a DNA vaccine adjuvanted with plasmids encoding different cytokines was investigated in large animals. Sheep were injected intramuscularly with a DNA vaccine encoding an antigen of Haemonchus contortus (pNPA) and plasmids encoding different cytokines followed by in vivo electroporation. Plasmids (pCI) carrying the genes of different cytokines including ovine IL-4(pCI-IL4), IL-10(pCI-IL10), GM-CSF(pCI-GMCSF), and MCP-1alpha(pCI-MCP1alpha), and pCI-IL4+pCI-GMCSF were co-delivered with pNPA. The results showed that co-delivery of pCI-GMCSF or pCI-IL4+pCI-GMCSF significantly enhanced both antibody responses and T cell proliferation responses to the antigen after two DNA immunisations compared to co-delivery of pCI. In contrast, antibody responses of the sheep that received pCI-IL10 were decreased significantly. Other cytokine expressing plasmids did not significantly alter the measured immune responses. Furthermore, co-delivery of pCI-GMCSF increased IgG2 response more than IgG1 responses, suggesting a Th1 bias. However, the increase in IgG2 over IgG1 was less apparent when co-delivery of pCI-IL4 with pCI-GMCSF. Interestingly, the co-delivery of pCI-IL4 alone did not increase the IgG1 titre, suggesting that both pCI-GMCSF and pCI-IL4 are required for optimal IgG1 production. Thus, co-delivery of plasmid-encoded cytokine genes with in vivo electroporation has the ability to effectively modulate immune responses to a DNA vaccine in a large animal.

Interleukin-10 Gene Transfer: Prevention of Multiple Organ Injury in a Murine Cecal Ligation and Puncture Model of Sepsis

INTRODUCTION

The aim of this study was to determine the effect of immunoregulatory cytokine interleukin-10 (IL-10) gene therapy on multiple organ injury (MOI) induced by a cecal ligation and puncture (CLP) model of sepsis in mice.

METHODS

Male Balb/c mice subjected to CLP were treated with either an hIL-10-carrying vector or an empty control vector. We assessed the degree of lung, liver, and kidney tissue destruction biochemically by measuring myeloperoxidase (MPO) and malondialdehyde (MDA) activity. Histologic assessments were based on neutrophil infiltration in lung and liver tissue. IL-10 protein expression was examined immunohistochemically, and ultrastructural changes in the liver were studied by transmission electron microscopy. We analyzed the expression of tumor necrosis factor-alpha (TNFalpha) mRNA by reverse transcription polymerase chain reaction 3, 8, and 24 hours after CLP in all organs.

RESULTS

Organ damage was significantly reduced by hIL-10 gene transfer, which was associated at the tissue level with reduced MPO activity in the liver, lung, and kidney and decreased leukocyte sequestration and MDA formation in the lung. The liver MDA was not significantly higher in the hIL-10 gene therapy group than in the controls and seemed not to be affected by hIL-10 gene transfer. The reduced portal tract neutrophilic infiltration and preserved ultrastructure of the hepatocytes also showed that tissue function was not impaired. The lung and kidney TNFalpha mRNA expression was suppressed markedly in the hIL-10 gene therapy group, but liver TNFalpha mRNA expression varied over time.

CONCLUSIONS

These findings showed that IL-10 gene therapy significantly attenuated sepsis-induced MOI.

Targeted in vitro and in vivo gene transfer into T lymphocytes: potential of direct inhibition of allo-immune activation

Background

Successful inhibition of alloimmune activation in organ transplantation remains one of the key events in achieving a long-term graft survival. Since T lymphocytes are largely responsible for alloimmune activation, targeted gene transfer of gene of cyclin kinase inhibitor p21 into T cells might inhibit their aberrant proliferation. A number of strategies using either adenoviral or lentiviral vectors linked to mono or bispecific antibodies directed against T cell surface markers/cytokines did not yield the desired results. Therefore, this study was designed to test if a CD3promoter-p21 chimeric construct would in vitro and in vivo transfer p21 gene to T lymphocytes and result in inhibition of proliferation. CD3 promoter-p21 chimeric constructs were prepared with p21 in the sense and antisense orientation. For in vitro studies EL4-IL-2 thyoma cells were used and for in vivo studies CD3p21 sense and antisense plasmid DNA was injected intramuscularly in mice. Lymphocyte proliferation was quantified by ³H-thymidine uptake assay; IL-2 mRNA expression was studied by RT-PCR and using Real Time PCR assay, we monitored the CD3, p21, TNF-α and IFN-γ mRNA expression.

Results

Transfection of CD3p21 sense and antisense in mouse thyoma cell line (EL4-IL-2) resulted in modulation of mitogen-induced proliferation. The intramuscular injection of CD3p21 sense and antisense plasmid DNA into mice also modulated lymphocyte proliferation and mRNA expression of pro-inflammatory cytokines.

Conclusion

These results demonstrate a novel strategy of in vitro and in vivo transfer of p21 gene to T cells using CD3-promoter to achieve targeted inhibition of lymphocyte proliferation and immune activation.

Interleukin-10 gene therapy attenuates pulmonary tissue injury caused by mesenteric ischemia-reperfusion in a mouse model

To investigate the role of interleukin (IL)-10 gene therapy on the reperfusion-induced lung injury, we utilised the technique of liposomal gene delivery before the induction of intestinal ischemia. Plasmid DNA encoding human IL10 (hIL-10) or empy vector was injected intraperitoneally 24 h before the study. Male Balb/c mice randomized into three groups: Sham operated control (n = 12), empty plasmid vector (n = 12), and hIL-10 gene therapy group (n = 12). The ischemia was generated by selective occlusion of superior mesenteric artery for 60 min and followed by reperfusion for 30 min. Lung tissue neutrophil infiltration was determined by myeloperoxidase assay and neutrophil counts. For the determination of lung tissue microvascular permeability, Evans blue dye injection was made and the lung edema was assessed by wet/dry ratio. hIL-10 protein expression was studied by immunostaining and ELISA. We found that pre-ischemic hIL-10 overexpression attenuated dye extravasation, leukocyte sequestration and reduced pulmonary tissue injury compared to the empty vector-injected control. Our study indicates that pre-ischemic hIL-10 overexpression attenuates lung injury caused by intestinal ischemia-reperfusion.

Reciprocal role of cyclins and cyclin kinase inhibitor p21WAF1/CIP1 on lymphocyte proliferation, allo-immune activation and inflammation

Background

Immune activation that results due to the aberrant proliferation of lymphocytes leads to inflammation and graft rejection in organ transplant recipients. We hypothesize that the cell cycle control and inflammation are parallel events, inhibition of cellular proliferation by cyclin kinase inhibitor specifically p21 will limit inflammation and prevent allograft rejection.

Methods

We performed in vitro and in vivo studies using lymphocytes, and rat heart transplant model to understand the role of cyclins and p21 on mitogen and allo-induced lymphocyte activation and inflammation. Lymphocyte proliferation was studied by ³H-thymidine uptake assay and mRNA expression was studied RT-PCR.

Results

Activation of allo- and mitogen stimulated lymphocytes resulted in increased expression of cyclins, IL-2 and pro-inflammatory cytokines, which was inhibited by cyclosporine. The over-expression of p21 prolonged graft survival in a completely mismatched rat heart transplant model resulted by inhibiting circulating and intra-graft expression of proinflammatory cytokines.

Conclusion

Cyclins play a significant role in transplant-induced immune activation and p21 over-expression has potential to inhibit T cell activation and inflammation. The results from this study will permit the design of alternate strategies by controlling cell cycle progression to achieve immunosuppression in transplantation.

Immunomodulation by topical particle-mediated administration of cytokine plasmid DNA suppresses herpetic stromal keratitis without impairment of antiviral defense

BACKGROUND

We investigated whether the course of herpetic stromal keratitis (HSK) in BALB/c mice could be altered by topical gene-gun-mediated administration of interleukin (IL)-4 or IL-10 plasmid DNA.

METHODS

Corneas of BALB/c mice were transfected with plasmids expressing beta-galactosidase (beta-gal), IL-4, IL-10, granulocyte-macrophage colony-stimulating factor (GM-CSF), and pCR3.1 (control) 2 days before Herpes simplex virus-1 (HSV-1; KOS) infection. Development of keratitis and cell infiltration were studied. HSV-1 replication was monitored by plaque assay. Expression of cytokines was detected by enzyme-linked immunosorbent assay. HSV-specific proliferation in the regional lymph nodes and spleens was measured. HSV-1 neutralizing antibody titers and IgG2A/IgG1 ratios were determined.

RESULTS

Expression of beta-gal was found in the treated corneas, but not in other tissues. IL-4 or IL-10 plasmid administration induced cytokine production in the corneas. After treatment with 300 psi, the severity of HSK was attenuated (each P<0.05), and the numbers of infiltrating inflammatory cells were lower than in the pCR3.1-treated controls (P<0.001). IL-6, but not IL-1alpha, expression in the cornea was reduced after treatment with IL-4 or IL-10 plasmid DNA. The HSV-1-specific DTH response, corneal Th1 cytokine profile, IgG/IgG2a/IgG1 ratio, neutralizing antibody titers, and virus clearance did not differ between the groups.

CONCLUSIONS

Thus, topically administered IL-4 and IL-10 plasmid DNA can lead to a milder course of HSK without impeding viral clearance. The gene gun technique for corneal delivery of plasmid cytokine DNA may be useful for modulating local immune responses without affecting antiviral defense.

Immune responses against SIV envelope glycoprotein, using recombinant SV40 as a vaccine delivery vector

Vaccination protocols using viral gene delivery vectors have often generated relatively weak responses, largely owing to difficulties in boosting immune responses effectively following the primary injection. Because recombinant gene delivery vectors derived from SV40 permit multiple inoculations, to yield incremental immune responses, we tested the use of rSV40s to deliver lentiviral envelope antigens for immunization. An rSV40 carrying SIVmac239 envelope glycoprotein gp130 cDNA (SV(gp130)) was given multiple times to BALB/c mice, with or without a prior priming inoculation using vaccinia virus carrying the same SIV envelope cDNA (VVenvSIV). Sera from these mice were tested for antibodies binding gp130, applying a novel cell-based ELISA protocol that used as targets cloned P815 cells stably transfected with plasmid-derived gp130 cDNA. The same gp130-expressing clone of P815 cells, labeled with 51Cr was used as targets for direct lymphocyte-mediated cytolytic assays using spleen and popliteal lymph node cells as effectors. After six inoculations with SV(gp130), mice made detectable anti-gp130 antibody responses, but high levels of splenic and popliteal lymph node cytotoxic activity were apparent after as few as three injections of SV(gp130) (>40% specific lysis). A single primary inoculation with VVenvSIV preceding SV(gp130) boosts significantly enhanced antibody responses against SIV gp130, but had little effect on cytotoxic lymphocyte responses. Thus, rSV40 vectors may be useful vehicles for delivering lentiviral envelope antigens to elicit protective humoral and cell-mediated immune responses.

The nasal epithelium as a factory for systemic protein delivery

We have previously shown that recombinant Sendai virus (SeV) produces efficient in vivo airway epithelial gene transfer. The ability to produce therapeutic levels of circulating proteins following noninvasive gene transfer would have widespread clinical application. Here, we compared nose, lung, and skeletal muscle for the ability to produce circulating levels of the secreted mouse antiinflammatory cytokine interleukin-10 (IL10) following SeV-mediated gene transfer. High levels of serum IL10 were obtained from each site with a potency order of lung > nose > muscle for a given viral titer. Serum levels from each site were within the likely required range for anti-inflammatory effects. The combination of a high-efficiency gene transfer agent (SeV) and sites that can be assessed noninvasively (nose or lung) may circumvent several current challenges to gene therapy.

Local drug and gene delivery through microbubbles

Ultrasound contrast agents (microbubbles) lower the threshold for cavitation by ultrasound energy. Ultrasound microbubbles may be used as cavitation nuclei for drug and gene delivery. By tailoring the physical properties of microbubbles and coating materials, drugs and genetic drugs can be incorporated into ultrasound contrast agents. As the microbubbles enter the region of insonation, the microbubbles cavitate, locally releasing the therapeutic agents. Cavitation also causes a local shockwave that improves cellular uptake of the therapeutic agent. As a result of the human genome project and continuing advances in molecular biology, many therapeutic genes have been discovered. In the cardiovascular system, gene therapy has the potential to improve myocardial vascularization and ameliorate congestive heart failure. For successful development of clinical gene therapy, however, effective gene delivery vectors are needed. Ultrasound contrast agents can be used to develop new, more effective vectors for gene delivery. Transthoracic ultrasound can be focused on the heart so that an intravenous injection of gene-bearing microbubbles will deliver genes relatively selectively to the myocardium. Using this technique, we have produced high levels of transgene expression in the insonated region of the myocardium. This new technology, using microbubbles and ultrasound for drug and gene delivery, merits further study and development.

Anticytokine gene therapy of autoimmune diseases

Viral and nonviral gene therapy vectors have been successfully employed to deliver inflammatory cytokine inhibitors (anticytokines), or anti-inflammatory cytokines, such as transforming growth factor beta-1 (TGF-beta 1), which protect against experimental autoimmune diseases. These vectors carry the relevant genes into a variety of tissues, for either localised or systemic release of the encoded protein. Administration of cDNA encoding soluble IFN-gamma receptor (IFN-gamma R)/IgG-Fc fusion proteins, soluble TNF-alpha receptors, or IL-1 receptor antagonist (IL-1ra), protects against either lupus, various forms of arthritis, autoimmune diabetes, or other autoimmune diseases. These inhibitors, unlike many cytokines, have little or no toxic potential. Similarly, TGF-beta 1 gene therapy protects against numerous forms of autoimmunity, though its administration entails more risk than anticytokine therapy. We have relied on the injection of naked plasmid DNA into skeletal muscle, with or without enhancement of gene transfer by in vivo electroporation. Expression plasmids offer interesting advantages over viral vectors, since they are simple to produce, non-immunogenic and nonpathogenic. They can be repeatedly administered and after each treatment the encoded proteins are produced for relatively long periods, ranging from weeks to months. Moreover, soluble receptors which block cytokine action, encoded by gene therapy vectors, can be constructed from non-immunogenic self elements that are unlikely to be neutralised by the host immune response (unlike monoclonal antibodies [mAbs]), allowing long-term gene therapy of chronic inflammatory disorders.

Genetic adjuvants for DNA vaccines

The relatively low efficacy of DNA vaccines in inducing immune responses, especially in large animal species and humans, has impaired their practical use. Despite considerable effort expended on improving DNA vaccine delivery, only minute amounts of Ag are available for immune induction following DNA vaccination. Two complementary strategies have been used to improve and modulate the immune response induced by DNA vaccines: (i) supplementing DNA vaccines with plasmids encoding cytokines and (ii) targeting the Ag encoded by DNA vaccine through genetically fusing the Ag to molecules binding cell surface receptors. This paper reviews recent progress in these two areas and possible mechanisms responsible for the observed effects.

On the mechanisms of T cell silencing by IL-10 DNA: direct and indirect inhibition of T cell functions

Previously we reported that mucosal IL-10 DNA administration resulted in long-term suppression of virus-induced inflammatory responses by silencing Th1-type CD4+ T cell functions. However, the mechanism by which IL-10 silences the activity of CD4+ T cells was not clear. The present report has shown that mucosal IL-10 DNA administration led to the reduction of reactivity of T cells following TCR stimulation. IL-10 DNA also downregulated APC functions to stimulate T cells but the effect was temporary. Bystander suppression, including that of IL-10 producing regulatory cells, appeared not to be directly involved in the inhibition of T cell reactivity because both anti-IL-10 and anti-IL-10R could not block the suppression of T cell functions. This silenced state could be maintained following adoptive transfer to untreated animals. The nature of the silencing appears to be a reversible anergic state since Ag stimulation in the presence of exogenous IL-2 restored T cell reactivity. Furthermore, IL-10-induced silenced T cells could be induced in vitro by culturing the T cells with rIL-10 in the presence or the absence of antigen stimulation. This state persisted in the absence of rIL-10 and persisted for at least 3 days. A more notable effect, however, was observed when the T cells were incubated with IL-10 in the presence of APC and Ag. These results indicate that IL-10 induced a long-term silenced state in T cells by direct and indirect inhibition of T cell functions.

In vitro and in vivo transfection of p21 gene enhances cyclosporin A-mediated inhibition of lymphocyte proliferation

Cyclosporine has potent antiproliferative properties, some of which may be via the induction of the cyclin inhibitor p21. In this study, we describe the effects of in vitro and in vivo transfection of p21 in lymphoid and nonlymphoid cells. For in vitro studies, p21 sense plasmid DNA was transfected in A-549 cells (lung adenocarcinoma cell line) and Jurkat cells (human lymphoid cell line). This in vitro transfection of p21 resulted in the inhibition of spontaneous and mitogen-induced cellular proliferation ([3H]thymidine uptake) and also augmented the antiproliferative effects of cyclosporine. In vivo transfection of p21 was accomplished in mice via the i.m. injection of p21 sense plasmid DNA complexed with cationic lipids. As was the case in the cell lines, p21 mRNA was augmented in heart, lung, liver, and spleen 7 days after i.m. injection of p21 sense plasmid DNA. The mitogen (anti-CD3)-induced proliferation of splenocytes from p21-overexpressing mice was significantly decreased, and again this effect was augmented by cotreatment with cyclosporine. These novel findings demonstrate the potential of targeting the cell cycle directly to inhibit alloimmune activation in organ transplantation. This may serve as an alternate strategy to induce immunosuppression, perhaps with less toxicity than that which is seen with conventional immunosuppressive agents.

Gene therapy of autoimmune diseases with vectors encoding regulatory cytokines or inflammatory cytokine inhibitors

Gene therapy offers advantages for the immunotherapeutic delivery of cytokines or their inhibitors. After gene transfer, these mediators are produced at relatively constant, non-toxic levels and sometimes in a tissue-specific manner, obviating limitations of protein administration. Therapy with viral or nonviral vectors is effective in several animal models of autoimmunity including Type 1 diabetes mellitus (DM), experimental allergic encephalomyelitis (EAE), systemic lupus erythematosus (SLE), colitis, thyroiditis and various forms of arthritis. Genes encoding transforming growth factor beta, interleukin-4 (IL-4) and IL-10 are most frequently protective. Autoimmune/ inflammatory diseases are associated with excessive production of inflammatory cytokines such as IL-1, IL-12, tumor necrosis factor alpha (TNFalpha) and interferon gamma (IFNgamma). Vectors encoding inhibitors of these cytokines, such as IL-1 receptor antagonist, soluble IL-1 receptors, IL-12p40, soluble TNFalpha receptors or IFNgamma-receptor/IgG-Fc fusion proteins are protective in models of either arthritis, Type 1 DM, SLE or EAE. We use intramuscular injection of naked plasmid DNA for cytokine or anticytokine therapy. Muscle tissue is accessible, expression is usually more persistent than elsewhere, transfection efficiency can be increased by low-voltage in vivo electroporation, vector administration is simple and the method is inexpensive. Plasmids do not induce neutralizing immunity allowing repeated administration, and are suitable for the treatment of chronic immunological diseases.

Amelioration of established collagen induced arthritis by systemic IL-10 gene delivery

A novel formulation of cationic liposomes containing the novel cytofectin ACHx was used for delivery of an anti-inflammatory cytokine gene, IL-10, to mice with established collagen induced arthritis. A single intraperitoneal injection of human IL-10 expression plasmid complexed with liposomes 2 to 4 days after the onset of arthritis was sufficient to give significant and prolonged amelioration of arthritis for 30 days. Preliminary experiments suggested that the therapeutic effect was IL-10 dose-dependent. The distribution of the human IL-10 DNA after injection was widespread, including the inflamed paws. Human IL-10 mRNA was also detected in the paws 24 h after injection. IL-10 protein was below the level of detection in paws and serum but was detected in some tissues up to 10 days after injection. The target cell of transfection was demonstrated to be the macrophage. These results suggest that systemic therapy with plasmid DNA complexed with cationic liposomes merits further development as an alternative method for anti-inflammatory treatment of arthritis.

Limitations of in vivo IL-12 supplementation strategies to induce Th1 early life responses to model viral and bacterial vaccine antigens

The limited induction of Th1 and cytotoxic immune responses is regarded as the main reason for the increased susceptibility to intracellular microorganisms in early life. Recently, in vitro IL-12 supplementation was shown to enhance the limited IFN-gamma release of measles-specific infant T cells. Using a series of IL-12 delivery systems, we show here that in vivo IL-12 supplementation may enhance early life murine Th1 responses to two model vaccine antigens, measles virus hemagglutinin and tetanus toxin peptide. However, this required multiple repeat injections of recombinant rIL-12, which were poorly tolerated in young mice. Local IL-12 delivery by an IL-12 expressing canarypox vector proved safe but failed to modulate vaccine responses. An IL-12 DNA plasmid or a CD40L DNA plasmid efficiently enhanced neonatal Th1 responses to measles hemagglutinin DNA vaccine. However, both plasmids only enhanced Th1 responses to DNA and not to peptide, protein, or live viral vaccines. Thus, inducing adult-like Th1 responses may be achieved in vivo by inducing (CD40L) or substituting for (IL-12 supplementation) optimal activation of neonatal APC. However, these immunomodulatory effects appear limited to certain antigen-presentation approaches and may not be broadly applicable to vaccines.

Distribution Fate and Mechanism of Immune Modulation Following Mucosal Delivery of Plasmid DNA Encoding IL-10

DNA vaccination has been widely studied in several models of vaccination and in the treatment of inflammatory diseases, even though the mechanism involved is still unclear. This report demonstrates that mucosal administration of plasmid DNA leads to rapid and widespread distribution around the body. Dissemination likely occurred via the bloodstream because plasmid DNA was present in blood plasma. The plasmid DNA was also detectable in several tissues including draining lymph nodes, spleen, liver, bone marrow, and even the dermis of ear pinnae. Except for the site of administration, plasmid DNA was no longer detectable in tissues after 3 wk postadministration. RNA and protein expression was also found in the tissues and bloodstream. Animals previously primed by HSV infection and subsequently given IL-10 DNA via the nasal mucosa, showed diminished Ag-induced delayed type hypersensitivity reactions for up to 5 wk posttreatment. The mechanism of modulation involved diminished the Ag-specific proliferation and production of Th1 cytokines. The Ag-specific silencing effects persisted beyond the duration of detectable plasmid encoded protein and was maintained upon adoptive transfer of T cells into a plasmid-free environment. The silenced T cells were not a source of IL-10, and their anergic state was reversible by exposure to Ag in the presence of exogenous IL-2.