Prevention of autoimmune diabetes by intramuscular gene therapy with a nonviral vector encoding an interferon-gamma receptor/IgG1 fusion protein

Exploring Novel Treatment Modalities for Type 1 Diabetes Mellitus: Potential and Prospects

Despite the effectiveness of insulin injections in managing hyperglycemia in type 1 diabetes mellitus (T1DM), they fall short in addressing autoimmunity and regenerating damaged islets. This review aims to explore the potential and prospects of emerging treatment modalities for T1DM, including mesenchymal stem cells (MSCs), MSC-derived exosomes, gene therapy, islet allotransplantation, pancreatic islet cell transplantation, and teplizumab. We review emerging treatment modalities for T1DM, highlighting several promising strategies with varied mechanisms and outcomes. Mesenchymal stem cells demonstrate potential in modulating the immune response and preserving or restoring beta-cell function, although variability in sources and administration routes necessitates further standardization. Similarly, MSC-derived exosomes show promise in promoting beta-cell regeneration and immune regulation, supported by early-stage studies showing improved glucose homeostasis in animal models, albeit with limited clinical data. Gene therapy, utilizing techniques like CRISPR-Cas9, offers targeted correction of genetic defects and immune modulation; however, challenges in precise delivery and ensuring long-term safety persist. Islet allotransplantation and pancreatic islet cell transplantation have achieved some success in restoring insulin independence, yet challenges such as donor scarcity and immunosuppression-related complications remain significant. Teplizumab, an anti-CD3 monoclonal antibody, has demonstrated potential in delaying T1DM onset by modulating immune responses and preserving beta-cell function, with clinical trials indicating prolonged insulin production capability. Despite significant progress, standardization, long-term efficacy, and safety continue to pose challenges across these modalities. Conclusion: While these therapies demonstrate significant potential, challenges persist. Future research should prioritize optimizing these treatments and validating them through extensive clinical trials to enhance T1DM management and improve patient outcomes.

Evolving Antibody Therapies for the Treatment of Type 1 Diabetes

Type 1 diabetes (T1D) is widely considered to be a T cell driven autoimmune disease resulting in reduced insulin production due to dysfunction/destruction of pancreatic β cells. Currently, there continues to be a need for immunotherapies that selectively reestablish persistent β cell-specific self-tolerance for the prevention and remission of T1D in the clinic. The utilization of monoclonal antibodies (mAb) is one strategy to target specific immune cell populations inducing autoimmune-driven pathology. Several mAb have proven to be clinically safe and exhibit varying degrees of efficacy in modulating autoimmunity, including T1D. Traditionally, mAb therapies have been used to deplete a targeted cell population regardless of antigenic specificity. However, this treatment strategy can prove detrimental resulting in the loss of acquired protective immunity. Nondepleting mAb have also been applied to modulate the function of immune effector cells. Recent studies have begun to define novel mechanisms associated with mAb-based immunotherapy that alter the function of targeted effector cell pools. These results suggest short course mAb therapies may have persistent effects for regaining and maintaining self-tolerance. Furthermore, the flexibility to manipulate mAb properties permits the development of novel strategies to target multiple antigens and/or deliver therapeutic drugs by a single mAb molecule. Here, we discuss current and potential future therapeutic mAb treatment strategies for T1D, and T cell-mediated autoimmunity.

Combined Oral Administration of GABA and DPP-4 Inhibitor Prevents Beta Cell Damage and Promotes Beta Cell Regeneration in Mice

γ-aminobutyric acid (GABA) or glucagon-like peptide-1 based drugs, such as sitagliptin (a dipeptidyl peptidase-4 inhibitor), were shown to induce beta cell regenerative effects in various diabetic mouse models. We propose that their combined administration can bring forth an additive therapeutic effect. We tested this hypothesis in a multiple low-dose streptozotocin (STZ)-induced beta cell injury mouse model (MDSD). Male C57BL/6J mice were assigned randomly into four groups: non-treatment diabetic control, GABA, sitagliptin, or GABA plus sitagliptin. Oral drug administration was initiated 1 week before STZ injection and maintained for 6 weeks. GABA or sitagliptin administration decreased ambient blood glucose levels and improved the glucose excursion rate. This was associated with elevated plasma insulin and reduced plasma glucagon levels. Importantly, combined use of GABA and sitagliptin significantly enhanced these effects as compared with each of the monotherapies. An additive effect on reducing water consumption was also observed. Immunohistochemical analyses revealed that combined GABA and sitagliptin therapy was superior in increasing beta cell mass, associated with increased small-size islet numbers, Ki67⁺ and PDX-1⁺ beta cell counts; and reduced Tunel⁺ beta cell counts. Thus, beta cell proliferation was increased, whereas apoptosis was reduced. We also noticed a suppressive effect of GABA or sitagliptin on alpha cell mass, which was not significantly altered by combining the two agents. Although either GABA or sitagliptin administration delays the onset of MDSD, our study indicates that combined use of them produces superior therapeutic outcomes. This is likely due to an amelioration of beta cell proliferation and a decrease of beta cell apoptosis.

Gene therapy in systemic lupus erythematosus

Preclinical studies have provided proof of concept for the feasibility and efficacy of gene therapy in human systemic lupus erythematosus (SLE). Successful efforts include gene constructs that alter the expression of cytokines or limit the cognate interaction of immune cells. Other efforts may include gene modified cell transfersuch as autologousB cells transfectedwith tolerogenicconstructsor T cells in which specific molecular aberrations have been corrected.

Oral administration of recombinant Lactococcus lactis expressing HSP65 and tandemly repeated P277 reduces the incidence of type I diabetes in non-obese diabetic mice

Diabetes mellitus type 1 (DM1) is an autoimmune disease that gradually destroys insulin-producing beta-cells. We have previously reported that mucosal administration of fusion protein of HSP65 with tandem repeats of P277 (HSP65-6P277) can reduce the onset of DM1 in non-obese diabetic (NOD) mice. To deliver large amounts of the fusion protein and to enhance long-term immune tolerance effects, in the present study, we investigated the efficacy of using orally administrated L. lactis expressing HSP65-6P277 to reduce the incidence of DM1 in NOD mice. L. lactis strain NZ9000 was engineered to express HSP65-6P277 either constitutively or by nisin induction. After immunization via gavage with the recombinant L. lactis strains to groups of 4-week old female NOD mice for 36 weeks, we observed that oral administration of recombinant L. Lactis resulted in the prevention of hyperglycemia, improved glucose tolerance and reduced insulitis. Immunologic analysis showed that treatment with recombinant L. lactis induced HSP65- and P277- specific T cell immuno-tolerance, as well as antigen-specific proliferation of splenocytes. The results revealed that the DM1-preventing function was in part caused by a reduction in the pro-inflammatory cytokine IFN-γ and an increase in the anti-inflammatory cytokine IL-10. Orally administered recombinant L. lactis delivering HSP65-6P277 may be an effective therapeutic approach in preventing DM1.

Polymer-based delivery of glucagon-like Peptide-1 for the treatment of diabetes

The incretin hormones, glucagon-like peptide-1 (GLP-1) and its receptor agonist (exendin-4), are well known for glucose homeostasis, insulinotropic effect, and effects on weight loss and food intake. However, due to the rapid degradation of GLP-1 by dipeptidylpeptidase-IV (DPP-IV) enzyme and renal elimination of exendin-4, their clinical applications have been restricted. Although exendin-4 has longer half-life than GLP-1, it still requires frequent injections to maintain efficacy for the treatment of diabetes. In recent decades, various polymeric delivery systems have been developed for the delivery of GLP-1 and exendin-4 genes or peptides for their long-term action and the extra production in ectopic tissues. Herein, we discuss the modification of the expression cassettes and peptides for long-term production and secretion of the native peptides. In addition, the characteristics of nonviral or viral system used for a delivery of a modified GLP-1 or exendin-4 are described. Furthermore, recent efforts to improve the biological half-life of GLP-1 or exendin-4 peptide via chemical conjugation with various smart polymers via chemical conjugation compared with native peptide are discussed.

Cationic nanomicelles for delivery of plasmids encoding interleukin-4 and interleukin-10 for prevention of autoimmune diabetes in mice

PURPOSE

To evaluate the in vivo transfection efficiency of N-acyl derivatives of low-molecular weight chitosan (LMWC) to deliver pVIVO2-mIL4-mIL10 plasmid encoding interleukin-4 (IL-4) and interleukin-10 (IL-10) in multiple, low-dose streptozotocin induced diabetic mouse model.

METHODS

N-acyl LMWC nanomicelles were characterized for size and charge. The pVIVO2-mIL4-mIL10/N-acyl LMWC polyplexes were injected intramuscularly in mice and compared for transfection efficiency with naked DNA and FuGENE® HD. Bicistronic pVIVO2-mIL4-mIL10 plasmid was compared with individual plasmids encoding IL-4 and IL-10 for efficacy. The levels of blood glucose and serum IL-4, IL-10, TNF-α and IFN-γ were monitored. The ability of plasmid administration to protect from insulitis and biocompatibility of N-acyl LMWC were studied.

RESULTS

The N-acyl LMWC led to significantly higher (p < 0.05) expression of IL-4 and IL-10 and reduced the levels of blood glucose, TNF-α and IFN-γ, especially in animals treated with pVIVO2-mIL4-mIL10 plasmid. The pancreas of pDNA/N-acyl LMWC polyplex treated animals exhibited protection from insulitis and the delivery systems were found to be biocompatible.

CONCLUSIONS

N-acyl derivatives of LMWC are efficient and biocompatible gene delivery vectors, and the administration of bicistronic pVIVO2-mIL4-mIL10 plasmid polyplexes can protect the pancreatic islets from insulitis, possibly due to the synergistic effect of IL-4 and IL-10 encoding plasmids.

Genetic vaccination for re-establishing T-cell tolerance in type 1 diabetes

Type 1 diabetes (T1D) is a T-cell mediated autoimmune disease resulting in the destruction of the insulin-secreting β cells. Currently, there is no established clinical approach to effectively suppress long-term the diabetogenic response. Genetic-based vaccination offers a general strategy to reestablish β-cell specific tolerance within the T-cell compartment. The transfer of genes encoding β-cell autoantigens, anti-inflammatory cytokines and/or immunomodulatory proteins has proven to be effective at preventing and suppressing the diabetogenic response in animal models of T1D. The current review will discuss genetic approaches to prevent and treat T1D with an emphasis on plasmid DNA- and adeno-associated virus-based vaccines.

Impaired negative regulation of homeostatically proliferating T cells

Acute lymphopenia-induced homeostatic proliferation (HP) of T cells promotes antitumor immunity, but the mechanism is unclear. We hypothesized that this is due to a lack of inhibitory signals that allows activation of T cells with low affinity for self-antigens. Tumors resist immunity in part by expressing inhibitory molecules such as PD-1 ligand 1 (PD-L1), B7-H4, and TGF-beta. In irradiated mice undergoing HP, we found that T cells displayed a severe deficit in the activation-induced expression of inhibitory molecules PD-1 and CTLA-4, and TGF-beta1-induced expression of Foxp3. HP T cells were also less suppressed by B7-H4/Ig and, unlike control T cells, failed to produce IL-10 in response to this molecule. This deficiency in regulation was reversed as normal T-cell numbers were restored. We conclude that T cells are weakly regulated by inhibitory molecules during the acute phase of HP, which could explain their increased effectiveness in cancer immunotherapy.

Induction of robust diabetes resistance and prevention of recurrent type 1 diabetes following islet transplantation by gene therapy

We have previously shown that the development of type 1 diabetes (T1D) can be prevented in nonobese diabetic (NOD) mice by reconstitution with autologous hemopoietic stem cells retrovirally transduced with viruses encoding MHC class II I-A beta-chain molecules associated with protection from the disease. In this study we examined whether a blockade of the programmed death-1 (PD-1)-programmed death ligand-1 (PD-L1) pathway, a major pathway known to control diabetes occurrence, could precipitate T1D in young NOD mice following reconstitution with autologous bone marrow retrovirally transduced with viruses encoding protective MHC class II I-A beta-chain molecules. In addition, we examined whether the expression of protective MHC class II alleles in hemopoietic cells could be used to prevent the recurrence of diabetes in mice with pre-existing disease following islet transplantation. Protection from the occurrence of T1D diabetes in young NOD mice by the expression of protective MHC class II I-A beta-chain molecules in bone marrow-derived hemopoietic cells was resistant to induction by PD-1-PD-L1 blockade. Moreover, reconstitution of NOD mice with pre-existing T1D autologous hemopoietic stem cells transduced with viruses encoding protective MHC class II I-A beta-chains allowed for the successful transplantation of syngeneic islets, resulting in the long-term reversal of T1D. Reversal of diabetes was resistant to induction by PD-1-PDL-1 blockade and depletion of CD25(+) T cells. These data suggest that expression of protective MHC class II alleles in bone marrow-derived cells establishes robust self-tolerance to islet autoantigens and is sufficient to prevent the recurrence of autoimmune diabetes following islet transplantation.

ApoE gene delivery inhibits severe hypercholesterolemia in newborn ApoE-KO mice

Apolipoprotein E, a key regulator in cholesterol-rich lipoprotein metabolism, is considered a strong candidate for treating hypercholesterolemia and cardiovascular disease. Inherited deficiency of this protein results in type III hyperlipoproteinemia in humans. ApoE-knockout mice, which develop spontaneous hypercholesterolemia, are an excellent model of human atherosclerosis. Here we investigated the therapeutic effects of a plasmid vector encoding human APOE3 sequence intramuscularly injected in hypercholesterolemic newborn mice at the ages of 5 and 14 days. We further explored the possibility of inducing tolerance in newborns when injected early. Our data show that direct i.m. naked DNA injection reduces severe hypercholesterolemia in newborn mice. Moreover, when naked DNA is administrated early, no immune response is generated against the human APOE, allowing repeated administrations. Neonatal therapies are important for the treatment of many genetic childhood diseases where early administration is required to prevent developmental damage. We propose the use of direct i.m. naked gene transfer in newborns to prevent long-term damages arising from hypercholesterolemic conditions.

In vivo expression of GLP-1/IgG-Fc fusion protein enhances beta-cell mass and protects against streptozotocin-induced diabetes

Glucagon-like peptide 1 (GLP-1) and its analogue exendin-4 (Ex4) have displayed potent glucose homeostasis-modulating characteristics in type 2 diabetes (T2D). However, there are few reports of effectiveness in type 1 diabetes (T1D) therapy, where there is massive loss of beta cells. We previously described a novel GLP-1 analogue consisting of the fusion of active GLP-1 and IgG heavy chain constant regions (GLP-1/IgG-Fc), and showed that in vivo expression of the protein, via electroporation-enhanced intramuscular plasmid-based gene transfer, normalized blood glucose levels in T2D-prone db/db mice. In the present study, GLP-1/IgG-Fc and Ex4/IgG-Fc were independently tested in multiple low-dose streptozotocin-induced T1D. Both GLP-1/IgG-Fc and Ex4/IgG-Fc effectively reduced fed blood glucose levels in treated mice and ameliorated diabetes symptoms, where as control IgG-Fc had no effect. Treatment with GLP-1/IgG-Fc or Ex4/IgG-Fc improved glucose tolerance and increased circulating insulin and GLP-1 levels. It also significantly enhanced islet beta-cell mass, which is likely a major factor in the amelioration of diabetes. This suggests that GLP-1/IgG-Fc gene therapy may be applicable to diseases where there is either acute or chronic beta-cell injury.

Plasmid-based gene therapy of diabetes mellitus

Type I diabetes mellitus (T1D) is due to a loss of immune tolerance to islet antigen and thus, there is intense interest in developing therapies that can re-establish it. Tolerance is maintained by complex mechanisms that include inhibitory molecules and several types of regulatory T cells (Tr). A major historical question is whether gene therapy can be employed to generate Tr cells. This review shows that gene transfer of immunoregulatory molecules can prevent T1D and other autoimmune diseases. In our studies, non-viral gene transfer is enhanced by in vivo electroporation (EP). This technique can be used to perform DNA vaccination against islet cell antigens and when combined with appropriate immune ligands results in the generation of Tr cells and protection against T1D. In vivo EP can also be applied for non-immune therapy of diabetes. It can be used to deliver protein drugs such as glucagon-like peptide 1 (GLP-1), leptin or transforming growth factor beta (TGF-beta). These act in T1D or type II diabetes (T2D) by restoring glucose homeostasis, promoting islet cell survival and growth or improving wound healing and other complications. Furthermore, we show that in large animals EP can deliver peptide hormones, such as growth hormone releasing hormone (GHRH). We conclude that the non-viral gene therapy and EP represent a safe and efficacious approach with clinical potential.

Protective Regulatory T Cell Generation in Autoimmune Diabetes by DNA Covaccination with Islet Antigens and a Selective CTLA-4 Ligand

DNA vaccination of autoimmune diabetes-prone NOD mice with unmodified target islet antigens, i.e., preproinsulin (PPIns) or glutamic acid decarboxylase 65 (GAD65), is poorly protective. However, in this study, we demonstrate protection against disease by covaccination with a mutant B7-1 molecule (B7-1wa) that binds the negative T cell regulator CTLA-4 (CD152), but not CD28. Codelivery of plasmids encoding a PPIns-GAD65 fusion construct and B7-1wa protected against both insulitis and diabetes. In vitro, the T cells of covaccinated mice had negative responses to both insulin and GAD65, and this was restored by adding blocking antibodies to transforming growth factor beta1 (TGF-beta1), suggesting a role for this cytokine. Adoptive transfer experiments revealed that DNA vaccination generated protective CD4(+) regulatory T cells (Tr) of either CD25(+) or CD25(-) phenotype. Furthermore, vaccinated mice had increased numbers of T cells with Tr-associated markers, such as CTLA-4, Foxp3, and membrane-bound TGF-beta1. Tr cells inhibited the responses of diabetogenic T cells to islet antigens, and depletion of T cells expressing membrane-bound TGF-beta1 abolished the suppressive effect. Thus, selective engagement of CTLA-4 during islet-antigen DNA vaccination induces Tr cells that protect against this autoimmune disease.

Gene therapy of diabetes using a novel GLP-1/IgG1-Fc fusion construct normalizes glucose levels in db/db mice

Glucagon-like peptide (GLP-1), a major physiological incretin, plays numerous important roles in modulating blood glucose homeostasis and has been proposed for the treatment of type 2 diabetes. The major obstacles for using native GLP-1 as a therapeutic agent are that it must be delivered by a parenteral route and has a short half-life. In an attempt to develop a strategy to prolong the physiological t(1/2) and enhance the potency of GLP-1, a fusion protein consisting of active human GLP-1 and mouse IgG(1) heavy chain constant regions (GLP-1/Fc) was generated. A plasmid encoding an IgK leader peptide-driven secretable fusion protein of the active GLP-1 and IgG(1)-Fc was constructed for mammalian expression. This plasmid allows for expression of bivalent GLP-1 peptide ligands as a result of IgG-Fc homodimerization. In vitro studies employing purified GLP-1/Fc indicate that the fusion protein is functional and elevates cAMP levels in insulin-secreting INS-1 cells. In addition, it stimulates insulin secretion in a glucose concentration-dependent manner. Intramuscular gene transfer of the plasmid in db/db mice demonstrated that expression of the GLP-1/Fc peptide normalizes glucose tolerance by enhancing insulin secretion and suppressing glucagon release. This strategy of using a bivalent GLP-1/Fc fusion protein as a therapeutic agent is a novel approach for the treatment of diabetes.

Gene therapy for type 1 diabetes

The most intensively studied autoimmune disorder, type 1 diabetes mellitus (DM1), has attracted perhaps the greatest interest for gene-based therapeutic and prophylactic interventions. The final clinical manifestation of this immunologically and genetically complex disease, the absence of insulin, is the major starting point for almost all the gene therapy modalities attempted to date. Insulin replacement by transplantation of islets of Langerhans or surrogate beta cells is the obvious choice, but the allogeneic nature of the transplants activates potent antidonor immunoreactivity necessitating gene and cell-based immunosuppressive strategies as an alternative to the toxic pharmacologic immunosuppressives indicated for classic solid organ transplants. Accumulating knowledge of the cellular mechanisms involved in onset, however, have yielded promising tolerance induction prophylactic approaches using genes and cells. Despite the early successes in a number of animal models, the true test of efficacy in humans remains to be demonstrated.

Therapeutic antibody gene transfer: an active approach to passive immunity

Advances in gene transfer approaches are enabling the possibility of applying therapeutic antibodies using DNA. In particular gene transfer in combination with electroporation is promising and can result in generating in vivo antibody concentrations in the low therapeutic range. However, several important problems need to be dealt with before antibody gene transfer can become a valuable supplement to the current therapies. As antibody production following gene transfer is difficult to control, the danger of inducing autoimmune conditions or uncontrollable side effects occurs in cases in which autologous antigens are targeted. It is suggested that the most promising area of application therefore appears to be infectious disease in which heterologous antigens are targeted and concerns for long-term antibody exposure are minimal. Finally, genes encoding fully human antibodies will enhance long-term expression and decrease problems linked to immunogenicity.

DNA vaccination with an insulin construct and a chimeric protein binding to both CTLA4 and CD40 ameliorates type 1 diabetes in NOD mice

Type 1 diabetes (T1D), a T-cell-mediated autoimmune disease, could be attributed to many defects in nonobese diabetic (NOD) mice, including deficient expressions of costimulatory molecules that impair antigen presentation. Thus, this deficient antigen presentation may result in a reduced ability to induce a tolerogenic response through negative selection/regulation of autoreactive T cells. Improperly activated T cells seem to be able to induce autoimmune responses causing diabetes. To re-establish tolerance to autoantigens by modulating costimulation, we constructed and tested a new type of DNA vaccine encoding a membrane-bound preproinsulin (mbPPI) and a chimeric gene vector encoding mutant B7.1/CD40L (mB7.1/CD40L) fusion protein. This mutant B7.1 binds CTLA4 but not CD28. We report that young NOD mice immunized with mbPPI along with mB7.1/CD40L DNA vectors significantly reduced diabetes incidence while treatment with CTLA4/IgG1 exacerbated diabetes. In conclusion, the combination of mbPPI and mB7.1/CD40L was able to protect against autoimmunity and diabetes in NOD mice possibly by promoting a more efficient presentation of autoantigen PPI and inducing specific tolerance to PPI by negatively regulating autoreactive T cells.

Interferons as pathogenic effectors in autoimmunity

Interferons (IFNs) type-1 (IFN alpha/beta) and type-II (IFN-gamma) are the most pleiotropic molecules in the intricate cytokine network. This dominance arises from three crucial factors: (i) initiation of IFN-alpha/beta and IFN-gamma production at the inception of most innate immune responses, which primes for the ensuing adaptive immune responses, primarily through the sine qua non upregulation of major histocompatibility complex and costimulatory molecules; (ii) magnification of their production and signaling by cross-talk between themselves, and synergistic or antagonistic effects on other cytokines; and (iii) direct or indirect initiation of transcription of hundreds of immunologically relevant genes. Considering that aberrant immune responses against self-molecules seem to depend on the same constituents and pathways as those against exogenous antigens, it follows that IFNs are also major effectors in the pathogenesis of autoimmunity. Here, we review the diverse biological effects of IFNs on the immune system, discuss findings pertaining to the nature of exogenous and endogenous stimuli that might induce IFN production through the engagement of Toll-like receptors, and summarize the detrimental and, in some instances, beneficial effects of IFNs in systemic and organ-specific autoimmune diseases.

Defects in the interferon-gamma and interleukin-12 pathways

The interferon-gamma (IFN-gamma)/interleukin-12 (IL-12) pathway is a pivotal player in the immune system and is central to controlling mycobacterial infections. We highlight the most recent and relevant advances in understanding this pathway and their repercussions on basic and clinical science. Human mutations in IFN-gamma receptor-1 (IFN-gammaR1), IFN-gammaR2, IL-12p40, IL-12 receptor-beta1, signal transducer and activator of transcription-1, and nuclear factor-kappaB essential modulator are analyzed in the context of genetic susceptibility to mycobacterial diseases. A diagnostic and therapeutic approach is described. The IFN-gamma/IL-12 pathway is central in immune control of both environmental and autochthonous challenges, as reflected in human mutations and animal models. Besides being crucial for mycobacterial control, the IFN-gamma/IL-12 pathway is also involved in the pathogenesis of autoimmune disease as well as tumor development and control. Genotype-phenotype correlations have been established for certain genes in this pathway, some of which have therapeutic implications.

Prevention of type 1 diabetes by gene therapy

The autoimmune disease type 1 diabetes in humans and NOD mice is determined by multiple genetic factors, among the strongest of which is the inheritance of diabetes-permissive MHC class II alleles associated with susceptibility to disease. Here we examined whether expression of MHC class II alleles associated with resistance to disease could be used to prevent the occurrence of diabetes. Expression of diabetes-resistant MHC class II I-Abeta chain molecules in NOD mice following retroviral transduction of autologous bone marrow hematopoietic stem cells prevented the development of autoreactive T cells by intrathymic deletion and protected the mice from the development of insulitis and diabetes. These data suggest that type 1 diabetes could be prevented in individuals expressing MHC alleles associated with susceptibility to disease by restoration of protective MHC class II expression through genetic engineering of hematopoietic stem cells.

Progression to islet destruction in a cyclophosphamide-induced transgenic model: a microarray overview

Type 1 diabetes appears to progress not as an uncontrolled autoimmune attack on the pancreatic islet beta-cells, but rather in a highly regulated manner. Leukocytic infiltration of the pancreatic islets by autoimmune cells, or insulitis, can persist for long periods of time before the terminal destruction of beta-cells. To gain insight on the final stage of diabetogenesis, we have studied progression to diabetes in a CD4(+) T-cell receptor transgenic variant of the NOD mouse model, in which diabetes can be synchronously induced within days by a single injection of cyclophosphamide. A time-course analysis of the gene expression profiles of purified islets was performed using microarrays. Contrary to expectations, changes in transcripts subsequent to drug treatment did not reflect a perturbation of gene expression in CD4(+) T-cells or a reduction in the expression of genes characteristic of regulatory T-cell populations. Instead, there was a marked decrease in transcripts of genes specific to B-cells, followed by an increase in transcripts of chemokine genes (cxcl1, cxcl5, and ccl7) and of other genes typical of the myelo-monocytic lineages. Interferon-gamma dominated the changes in gene expression to a striking degree, because close to one-half of the induced transcripts issued from interferon-gamma-regulated genes.

Plasmids encoding membrane-bound IL-4 or IL-12 strongly costimulate DNA vaccination against carcinoembryonic antigen (CEA)

Vaccination with plasmids encoding an antigen of interest (DNA vaccination) is a new strategy to achieve effective immunization against many agents. DNA vaccination can be ameliorated by co-administration of plasmids encoding a cytokine. Thus far, only plasmids encoding soluble cytokines have been used for this purpose. However, these plasmids can induce release of cytokines into the circulation and could potentially cause many undesirable effects. We undertook this study to determine whether membrane-bound cytokines, which would restrict their localization at the site of administration, can act as immunoadjuvants. We and others have previously shown that plasmids encoding soluble IL-4 and IL-12 are effective adjuvants for DNA vaccination. In this study, we demonstrate that DNA co-vaccination with membrane-bound IL-4 (mbIL-4) or membrane-bound IL-12 (mbIL-12) both enhance anti-CEA immunity, as detected by in vitro and in vivo assays. Mice co-injected with plasmids encoding CEA and either type of membrane-bound cytokine rejected transplanted CEA-positive tumor cells strongly. Notably, unlike secreted IL-4, mbIL-4 was the most effective adjuvant for anti-tumor immunity. This study demonstrates that membrane-bound cytokines are suitable adjuvants for DNA vaccination.

Intramuscular gene transfer of soluble B7.1/IgG(1) fusion cDNA induces potent antitumor immunity as an adjuvant for DNA vaccination

Soluble B7.1/IgG Fc fusion protein, which has costimulatory effects, is an effective molecular adjuvant in tumor immune therapy. Here, we describe a nonviral intramuscular (i.m.) gene transfer method to deliver this therapeutic protein. Gene transfer was greatly enhanced by electroporation and highly efficient production of this protein was achieved. Serum levels reached up to 1 microg/ml with considerable length of expression and without apparent systemic adverse effects. Lymphocytes from mice coinjected with soluble B7.1/IgG(1) and carcinoembryonic antigen (CEA)-encoding plasmids showed significantly elevated CEA-stimulated proliferation, cytokine production, and cytotoxic T-lymphocyte (CTL) activity. These mice gained significant protection against a CEA-positive transplanted tumor, in terms of reduced tumor incidence and growth. The effects were superior when soluble B7.1/IgG(1) was expressed as compared to membrane-bound wild-type B7.1. Notably, expression of soluble B7.1/IgG(1) alone did not induce any protection against tumor, confirming its primary role as a costimulatory molecule rather than a direct antitumor agent. The plasmid encoding B7.1/IgG(1) did not have to be injected at the same site as the antigen-encoding plasmid to exert its adjuvant effect, indicating that circulating protein was sufficient. Muscle histopathology revealed minimal damage to DNA-injected muscles. Importantly, we show that, after gene transfer, muscle tissue can produce this protein in large quantity to exert its immune costimulatory effect for cancer therapy and it would be otherwise difficult and expensive to maintain this high a level of recombinant protein.

Immunopathology and the gene therapy of lupus

Lupus is a chronic autoimmune inflammatory disease with complex clinical manifestations. In humans, lupus, also known as systemic lupus erythematosus (SLE), affects between 40 and 250 individuals, mostly females, in each 100 000 of the population. There are also a number of murine models of lupus widely used in studies of the genetics, immunopathology, and treatment of lupus. Human patients and murine models of lupus manifest a wide range of immunological abnormalities. The most pervasive of these are: (1) the ability to produce pathogenic autoantibodies; (2) lack of T- and B-lymphocyte regulation; and (3) defective clearance of autoantigens and immune complexes. This article briefly reviews immunological abnormalities and disease mechanisms characteristic of lupus autoimmunity and highlight recent studies on the use of gene therapy to target these abnormalities.

Gene- and cell-based therapeutics for type I diabetes mellitus

Type 1 diabetes mellitus, an autoimmune disorder is an attractive candidate for gene and cell-based therapy. From the use of gene-engineered immune cells to induce hyporesponsiveness to autoantigens to islet and beta cell surrogate transplants expressing immunoregulatory genes to provide a local pocket of immune privilege, these strategies have demonstrated proof of concept to the point where translational studies can be initiated. Nonetheless, along with the proof of concept, a number of important issues have been raised by the choice of vector and expression system as well as the point of intervention; prophylactic or therapeutic. An assessment of the current state of the science and potential leads to the conclusion that some strategies are ready for safety trials while others require varying degrees of technical and conceptual refinement.

Regulatory cytokine production stimulated by DNA vaccination against an altered form of glutamic acid decarboxylase 65 in nonobese diabetic mice

Nonobese diabetic (NOD) mice develop a T-cell dependent autoimmune form of diabetes, in which glutamic acid decarboxylase 65 (GAD65) is an important islet target antigen. Intramuscular DNA vaccination with a plasmid encoding native GAD65 (a cytosolic antigen) did not significantly alter the incidence of diabetes, but vaccination against an altered form of GAD65 with a signal peptide (spGAD), which is secreted in vitro, was protective. The preventive effect was further enhanced by repeated injections of the spGAD plasmid. Following DNA injection into muscle GAD65 was expressed for several months, and this was not accompanied by an inflammatory response. Immunization against GAD65 was not associated with substantial alterations in cytokine production by splenic lymphocytes stimulated with immunogenic GAD65 peptides. In contrast, spGAD induced increased secretion of both interleukin 10 and interferon gamma and a striking decrease in the interferon gamma/interleukin 10 ratio in culture supernatants. Similarly, spGAD-immunized mice had higher serum interleukin 10 levels and lower serum interferon gamma levels than other groups, suggesting a systemic effect. In nondiabetic mice there was increased basal production of transforming growth factor beta(1), which was enhanced by antigenic stimulation. These alterations in regulatory cytokine production were apparent both early and late after the treatment was initiated. These findings suggest that DNA vaccination against spGAD protects NOD mice by increasing regulatory cytokine production.

Gene and cell therapies for diabetes mellitus: strategies and clinical potential

The last 5 years have witnessed an explosion in the use of genes and cells as biomedicines. While primarily aimed at cancer, gene engineering and cell therapy strategies have additionally been used for Mendelian, neurodegenerative and metabolic disorders. The main focus of gene and cell therapy strategies in metabolism has been diabetes mellitus. This disease is a disorder of glucose homeostasis, either due to the immune-mediated eradication of pancreatic beta cells in the islets of Langerhans (type 1 diabetes) or resulting from insulin resistance and obesity syndromes where the insulin-producing capability of the beta cell is ultimately exhausted in the face of insensitivity to the effects of insulin in the peripheral glucose-utilising tissues (type 2 diabetes). A significant number of animal studies have demonstrated the potential in restoring normoglycaemia by islet transplantation in the context of immunoregulation achieved by gene transfer of immunoregulatory genes to allo- and xenogeneic islets ex vivo. Additionally, gene and cell therapy has also been used to induce tolerance to auto- and alloantigens and to generate the tolerant state in autoimmune rodent animal models of type 1 diabetes or rodent recipients of allogeneic/xenogeneic islet transplants. The achievements of gene and cell therapy in type 2 diabetes are less evident, but seminal studies promise that this modality can be relevant to treat and perhaps prevent the underlying causes of the disease. Here we present an overview of the current status of gene and cell therapy for type 1 and 2 diabetes and we propose potential therapeutic options that could be clinically useful. For type 1 diabetes, transplantation of islets engineered to evade or suppress the recipient immune response is the most readily-available technology today. A number of gene delivery vectors encoding proteins that impair a variety of immune cells have already been examined and proven versatile. More challenging but, nonetheless, just over the horizon are attempts to promote tolerance to islet allografts. Type 2 diabetes will likely require a better understanding of the processes that determine insulin sensitivity in the periphery. Targeting tissues such as muscle and fat with vectors encoding genes whose products promote insulin sensitivity and glucose uptake is an approach that does not carry with it the side-effects often associated with pharmacologic agents currently in use. In the end, progress in vector design, elucidation of antigen-specific immunity and insulin sensitivity will provide the framework for gene drug use in the treatment of type 1 and type 2 diabetes.

Optimization of Naked DNA Delivery for Interferon Subtype Immunotherapy in Cytomegalovirus Infection

Type I interferon (IFN) gene therapy modulates the immune response leading to inflammatory heart disease following cytomegalovirus (CMV) infection in a murine model of post-viral myocarditis. Efficacy of different immunisation protocols for the IFN constructs was influenced by the dose of DNA, subtype choice, combination use, pre-medication, and timing of DNA administration. Optimal efficacy was found with bupivacaine treatment prior to DNA inoculation of 200mg IFN DNA 14 days prior to virus challenge. Maximal antiviral and antimyocarditic effects were achieved with this vaccination schedule. Furthermore, inoculation of synergistic IFN subtypes demonstrated enhanced efficacy when delivered either alone or with CMV gB DNA vaccination in the CMV model. Thus naked DNA delivery of IFN provides an avenue of immunotherapy for regulating herpesvirus-induced diseases.

The pathogenesis of oral lichen planus

Both antigen-specific and non-specific mechanisms may be involved in the pathogenesis of oral lichen planus (OLP). Antigen-specific mechanisms in OLP include antigen presentation by basal keratinocytes and antigen-specific keratinocyte killing by CD8(+) cytotoxic T-cells. Non-specific mechanisms include mast cell degranulation and matrix metalloproteinase (MMP) activation in OLP lesions. These mechanisms may combine to cause T-cell accumulation in the superficial lamina propria, basement membrane disruption, intra-epithelial T-cell migration, and keratinocyte apoptosis in OLP. OLP chronicity may be due, in part, to deficient antigen-specific TGF-beta1-mediated immunosuppression. The normal oral mucosa may be an immune privileged site (similar to the eye, testis, and placenta), and breakdown of immune privilege could result in OLP and possibly other autoimmune oral mucosal diseases. Recent findings in mucocutaneous graft-versus-host disease, a clinical and histological correlate of lichen planus, suggest the involvement of TNF-alpha, CD40, Fas, MMPs, and mast cell degranulation in disease pathogenesis. Potential roles for oral Langerhans cells and the regional lymphatics in OLP lesion formation and chronicity are discussed. Carcinogenesis in OLP may be regulated by the integrated signal from various tumor inhibitors (TGF-beta 1, TNF-alpha, IFN-gamma, IL-12) and promoters (MIF, MMP-9). We present our recent data implicating antigen-specific and non-specific mechanisms in the pathogenesis of OLP and propose a unifying hypothesis suggesting that both may be involved in lesion development. The initial event in OLP lesion formation and the factors that determine OLP susceptibility are unknown.

In vivo generation of dendritic cells by intramuscular codelivery of FLT3 ligand and GM-CSF plasmids

Dendritic cells (DCs) are the major cells responsible for the uptake and the transport of antigens to regional lymphoid tissues and for the presentation of antigenic peptides to T cells. They are highly effective in immunotherapy. However, in lymphoid and other tissues, DCs constitute only a small population and are difficult to isolate in large numbers. Our objective was to devise a method with which to rapidly expand splenic DCs in vivo. We accomplished this by intramuscular injection of plasmids encoding mouse granulocyte-macrophage colony stimulating factor (GM-CSF) and fms-like tyrosine kinase 3-ligand (FLT3-L). Gene transfer was amplified by electroporation. Both cytokine vectors significantly increased DC numbers, but they were more effective in combination. When either control plasmid (Blank), or FLT3-L or GM-CSF expression plasmids were injected individually, the mean numbers of CD11c(+)/MHC II(+) DCs in spleen cell suspensions were, respectively, 6, 11, and 23 million. When FLT3-L and GM-CSF plasmids were codelivered, this increased to 36 million. Peak levels occurred 7 days postinjection of DNA. To further characterize these DCs, we stained them with myeloid (CD11b, F4/80)- and lymphoid (CD8alpha)-related markers. FLT3-L cDNA favored lymphoid DC expansion and GM-CSF cDNA favored myeloid DC expansion, whereas combined treatment expanded both types with a myeloid predominance. We confirm the ability of these DCs to present antigen to CD4(+) T cells and to stimulate in mixed lymphocyte cultures. We demonstrate that DCs can be rapidly expanded by this simple gene transfer method, which has numerous potential applications.

Immunoinhibitory DNA vaccine protects against autoimmune diabetes through cDNA encoding a selective CTLA-4 (CD152) ligand

Cytotoxic T lymphocyte antigen 4 (CTLA-4 or CD152) is a strong negative regulator of T cell activity. Like CD28 (a positive regulator) it binds to B7-1 and B7-2, and there is no known natural selective ligand. Monoclonal antibodies to CTLA-4 generally have a masking effect, enhancing rather than suppressing responses. However, a single amino acid substitution in B7-1 (W88 > A; denoted B7-1wa) abrogates binding to CD28 but not to CTLA-4. We constructed plasmids encoding B7-1 or B7-1wa, as cell-surface or Ig fusion proteins. In a bound state, B7-1-Ig enhanced CD3-mediated T cell activation, but B7-1wa-Ig was inhibitory, as expected of a CTLA-4 ligand. To alter immunity in vivo, we inoculated mice intramuscularly (i.m.) with a carcinoembryonic antigen (CEA) plasmid. Gene transfer was amplified by electroporation. Co-injection of a B7-1wa (membrane-bound form) plasmid blocked induction of anti-CEA immunity, whereas a B7-1 plasmid was stimulatory. We studied this DNA covaccination method in nonobese diabetic (NOD) mice with autoimmune diabetes. Delivery of either preproinsulin I (PPIns) or B7-1wa cDNA alone did not suppress the autoimmune anti-insulin response of spleen cells. However, co-delivery of B7-1wa and PPIns cDNA abrogated reactivity to insulin and ameliorated disease. Interferon-gamma and interleukin-4 were both depressed, arguing against a Th2 bias. Reactivity to glutamic acid decarboxylase 65, another major islet autoantigen, was not altered and suppressor cells were not identified, suggesting induction of tolerance to insulin by either T cell anergy or deletion. Selective engagement of CTLA-4 through gene transfer represents a novel and powerful way to block autoimmunity specifically.

Serum IFN-gamma and IL-10 levels are associated with disease progression in non-obese diabetic mice

BACKGROUND

The goal of the present study was to determine whether cytokines in the peripheral blood of naive NOD mice correlate with the disease process and thereby would provide a marker for monitoring disease activity.

METHODS

Female NOD mice (5, 10 and 14-16 weeks of age) were investigated in a cross-sectional study. In the group of 14-16-week-old mice, non-diabetic and diabetic mice were analysed as different subgroups. The Th1 cytokine (IFN-gamma) and the Th2 cytokine (IL-10) were quantified in serum by sandwich enzyme-linked immunosorbent assay (ELISA). Pancreatic mRNA for IFN-gamma and IL-10 was determined by reverse transcriptase-polymerase chain reaction (RT-PCR) from the same animals.

RESULTS

Serum levels of IFN-gamma were initially low but increased with age in NOD mice, reaching the highest levels at diabetes onset (p<0.002 compared to 10 weeks). A similar rise was noted in IFN-gamma gene expression in pancreatic lesions. In contrast, an early peak of serum IL-10 levels was observed in non-diabetic NOD mice (10 weeks) at a stage where non-destructive insulitis occurs. With increasing age a continuous loss of IL-10 until progression towards diabetes was observed. The pancreatic IL-10 mRNA expression correlated with serum IL-10 changes. As a consequence, the ratio of IFN-gamma/IL-10, reflecting the Th1/Th2 balance in the serum, was significantly increased in diabetic compared to non-diabetic NOD mice (p<0.005).

CONCLUSION

These results demonstrate, for the first time, that an increased Th2 pattern in the non-diabetic stage preceding a Th1 shift is associated with the development of diabetes in naive NOD mice. Serum cytokines correlate with disease progression and pancreatic cytokine expression during prediabetes. Soluble cytokines measured in the periphery are therefore promising surrogate markers of diabetes development.

Immunotherapy of type 1 diabetes: lessons for other autoimmune diseases

The nonobese diabetic (NOD) mouse is a well-recognised animal model of spontaneous autoimmune insulin-dependent diabetes mellitus. The disease is T-cell mediated, involving both CD4 and CD8 cells. Its progress is controlled by a variety of regulatory T cells. An unprecedented number of immunological treatments have been assessed in this mouse strain. This chapter systematically reviews most of these therapeutic manoeuvres, discussing them in the context of their significance with regard to the underlying mechanisms and the potential clinical applications. The contrast between the surprisingly high rate of success found for a multitude of treatments (more than 160) administered early in the natural history of the disease and the few treatments active at a late stage is discussed in depth. Most of the concepts and strategies derived from this model apply to other autoimmune diseases, for which no such diversified data are available.

Gene therapy in autoimmune disease

Recent work on gene therapies for autoimmune disease has continued to provide insight into the pathogenesis of autoimmunity. Reliable, effective and targeted gene therapy applications have been achieved by using transduced dendritic cells and antigen-specific T cells as delivery vehicles. Bioluminescence imaging has been implemented to visualize cell trafficking and homing in vivo. As a first step into human gene therapy, a phase I clinical trial for assessing the feasibility and safety of gene transfer has been completed in a group of rheumatoid arthritis patients.

IFN-gamma affects homing of diabetogenic T cells

IFN-gamma is a cytokine with pleiotropic functions that participates in immune and autoimmune responses. The lack of IFN-gamma is known to delay the development of autoimmune diabetes in nonobese diabetic (NOD) mice. Splenocytes from diabetic NOD and IFN-gamma knockout (KO) NOD mice transfer diabetes into NOD recipients equally well. However, adoptive transfer of diabetogenic T cells from NOD mice into NOD.IFN-gamma-KO or NOD mice lacking beta-chain of IFN-gamma receptor (NOD.IFN-gammaRbeta-KO) appeared to be much less efficient. We found that IFN-gamma influences the ability of diabetogenic cells to penetrate pancreatic islets. Tracing in vivo of insulin-specific CD8+ T cells has shown that homing of these cells to the islets of Langerhans was affected by the lack of IFN-gamma. While adhesion of insulin-specific CD8+ cells to microvasculature was normal, the diapedesis was significantly impaired. This effect was reversible by treatment of the animals with rIFN-gamma. Thus, IFN-gamma may, among other effects, influence immune and autoimmune responses by supporting the homing of activated T cells.

Inhibitors of phosphodiesterase isoforms III or IV suppress islet-cell nitric oxide production

The general phosphodiesterase (PDE) inhibitor pentoxifylline (PTX), and the PDE type IV inhibitor rolipram (ROL), both increase intracellular cAMP levels and suppress inflammatory cytokine production by T cells and macrophages. We have previously shown that PTX and ROL protect from autoimmune diabetes in nonobese diabetic (NOD) mice. These drugs may mediate some of their anti-inflammatory effects by blocking nitric oxide (NO) production by macrophages. In this study, we investigated the effect of PDE inhibitors in blocking NO production by insulin-secreting NIT-1 insulinoma cells and mouse islet cells in vitro and in vivo. Insulinoma cells and islet cells produced NO when stimulated with a combination of inflammatory cytokines and lipopolysaccharide (LPS). We found that both PTX and ROL markedly suppressed this induced NO production. Islet cells express PDEs III and IV and, accordingly, the PDE III inhibitor cilostamide (CIL) also suppressed NO production, and a combination of ROL and CIL had a synergistic effect. This suppression appeared to be mediated, at least in part, by elevating cAMP level and was mimicked by other cAMP-elevating agents, ie, membrane-permeable cAMP analogs (dibutyryl cAMP and 8-bromo cAMP) and an adenylate cyclase stimulator (forskolin). PDE inhibitors suppressed the expression of inducible nitric oxide synthase (iNOS) mRNA. In vivo treatment with PTX or ROL prevented iNOS protein expression in the islets of NOD mice with cyclophosphamide-accelerated disease. Our findings suggest that PDE inhibitors can protect islets against autoimmunity.

Efficient naked plasmid cotransfection of lung grafts by extended lung/plasmid exposure time

BACKGROUND

Multiple gene cotransfection may be an effective strategy to modulate concurrent pathologic events after lung transplantation. We investigated in vivo naked plasmid lung cotransfection during cold preservation and the role of lung parenchyma/naked plasmid exposure time.

METHODS

F344 rats underwent left main bronchus instillation of pCF1-CAT (chloramphenicol acetyl transferase) (130 microg) +/- pCF1-beta-Gal (beta-galactosidase) (130 microg) in saline. Part Ia: 4 degrees C preservation versus cotransfection. Lung isografts (4 groups, n = 8) were stored after transfection for 1 (2 groups: one received only pCF1-CAT), 6, and 18 hours. Recipient sacrifice was after 48 hours. Part Ib: 4 degrees C preservation versus transgene expression. Rats were sacrificed 48 hours after transfection in a nontransplant setting (2 groups, n = 8; one received only pCF1-CAT). In a third group (n = 8) lungs were harvested 24 hours after transfection, stored for 18 hours, and recipients were sacrificed after 24 hours. The CAT and beta-Gal enzymatic-linked immunosorbent assays were performed. Part II: Lung/plasmid exposure time. In three groups (n = 6) after pCF1-CAT transfection the left main bronchus was not clamped, clamped for 10 minutes, or clamped for 1 hour. Sacrifice was after 48 hours.

RESULTS

Part Ia: Lung CAT protein was (in picograms per 100 microg of total protein): median, 42 (range, 25 to 95) after 1 hour (only CAT); 67 (19 to 296) after 1 hour, 32 (6 to 157) after 6 hours; and 9 (5 to 243) after 18 hours. Lung beta-Gal protein was (in picograms per 100 microg of total protein): median, 20 (range, 5 to 353) after 1 hour; 17 (6 to 157) after 6 hours; 4 (1 to 74) after 18 hours (1 hour versus 18 hours, p = 0.04 for both proteins). CAT and beta-Gal production were significantly correlated (p = 0.0001, r = 0.924). Part Ib: Lung CAT protein was (in picograms per 100 microg of total protein): median, 2 (range, 0.6 to 10) no transplant, only CAT; 7 (0.3 to 13) no transplant; 3 (0.9 to 14) transplant. Part II: Left lung CAT protein was (in picograms per 100 microg of total protein): median, 31 (range, 6 to 83) no clamp; 74 (25 to 430) 10 minutes of clamp; 111 (30 to 263) 1 hour of clamp. Right lung CAT protein was (in picograms per 100 microg of total protein): median, 0.06 (range, 0 to 0.9) no clamp; 1 (0 to 6) 10 minutes of clamp; 1 (0 to 18) 1 hour of clamp.

CONCLUSIONS

Efficient lung isograft endobronchial cotransfection results from using naked plasmid. Cold preservation affects transfection efficiency but not transgene expression. Lung parenchyma/naked plasmid exposure time determines transfection efficiency.

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.

The activity of immunoregulatory T cells mediating active tolerance is potentiated in nonobese diabetic mice by an IL-4-based retroviral gene therapy

Splenocytes from nonobese diabetic mice overexpressing murine IL (mIL)-4 upon recombinant retrovirus infection lose their capacity to transfer diabetes to nonobese diabetic-scid recipients. Diabetes appeared in 0-20% of mice injected with mIL-4-transduced cells vs 80-100% of controls injected with beta-galactosidase-transduced cells. Protected mice showed a majority of islets (60%) presenting with noninvasive peri-insulitis at variance with beta-galactosidase controls that exhibited invasive/destructive insulitis. Importantly, in all recipients, the transduced proteins were detected within islet infiltrates. Infiltrating lymphocytes from recipients of mIL-4-transduced cells produced high levels of mIL-4, as assessed by ELISA. In recipients of beta-galactosidase-transduced cells, approximately 60% of TCRalphabeta(+) islet-infiltrating cells expressed beta-galactosidase, as assessed by flow cytometry. The protection from disease transfer is due to a direct effect of mIL-4 gene therapy on immunoregulatory T cells rather than on diabetogenic cells. mIL-4-transduced purified CD62L(-) effector cells or transgenic BDC2.5 diabetogenic T cells still transferred disease efficiently. Conversely, mIL-4 transduction up-regulated the capacity of purified immunoregulatory CD62L(+) cells to inhibit disease transfer. These data open new perspectives for gene therapy in insulin-dependent diabetes using T cells devoid of any intrinsic diabetogenic potential.

Effects of plasmid DNA injection on cyclophosphamide-accelerated diabetes in NOD mice

Type 1 diabetes results in most cases from the destruction of insulin-secreting beta cells by the immune system. Several immunization methods based on administration of autoantigenic polypeptides such as insulin and glutamic acid decarboxylase (GAD) have been used to prevent autoimmune diabetes in the non-obese diabetic (NOD) mouse. In the work presented here, a gene-based approach was taken for a similar purpose. A plasmid carrying different cDNAs was used to investigate the effects of injecting naked DNA on cyclophosphamide-accelerated diabetes in female NOD mice. Four-week-old animals received intramuscular injections of plasmid DNA encoding either intracellular GAD, a secreted form of GAD, or a secreted form of a soft coral luciferase. Monitoring of glycosuria and hyperglycemia indicated that injection of plasmid DNA encoding secreted GAD and secreted luciferase could prevent and delay diabetes, respectively. In contrast, injection of DNA encoding intracellular GAD did not suppress the disease significantly. Analysis of anti-GAD IgG(1) antibody titers in animal sera indicated that diabetes prevention after injection of GAD-encoding DNA was possibly associated with increased Th2-type activity. These results suggest that cellular localization of GAD is a factor to consider in the design of GAD-based genetic vaccines for the prevention of autoimmune diabetes.

Immunotherapeutic gene transfer into muscle

Immuno-gene therapy can be advantageously performed with nonviral approaches. Genes that encode regulatory cytokines or inflammatory cytokine inhibitors can be delivered intramuscularly and expressed for weeks or months. This type of gene transfer into muscle has been shown to ameliorate several autoimmune diseases and is relevant to the development of effective DNA vaccines in autoimmune diseases, infectious diseases and cancer.

The phosphodiesterase inhibitors pentoxifylline and rolipram suppress macrophage activation and nitric oxide production in vitro and in vivo

We studied the effects of the phosphodiesterase inhibitors pentoxifylline (PTX) and rolipram (ROL) on nitric oxide (NO) production by macrophages and correlated this with cellular cAMP levels. The RAW 264.7 cell line or mouse peritoneal macrophages were activated with lipopolysaccharide (LPS) and interferon gamma (IFN gamma), with or without ROL, PTX, cAMP analogues, or Forskolin. In vivo, peritoneal macrophages were stimulated with staphylococcal enterotoxin B with or without administration of ROL. Nitrite levels in culture and the total cellular cAMP levels were measured. ROL and PTX suppressed NO production of LPS/IFN gamma-stimulated macrophages. ROL (IC(50) = 68-74 microM) was about 40 times more potent than PTX (IC(50) = 2.4-2.9 mM). The suppression paralleled increased total cellular cAMP level (EC(50) = 68-72 microM) and was mimicked by other cAMP elevating agents. ROL and PTX suppressed inducible NO synthase at the mRNA level. The inhibition of NO production of macrophages by ROL or PTX could be beneficial in NO-mediated inflammatory and/or autoimmune disorders.

Degradable polymeric carrier for the delivery of IL-10 plasmid DNA to prevent autoimmune insulitis of NOD mice

Recently, we have reported that biodegradable poly [alpha-(4-aminobutyl)-L-glycolic acid] (PAGA) can condense and protect plasmid DNA from DNase I. In this study, we investigated whether the systemic administration of pCAGGS mouse IL-10 (mIL-10) expression plasmid complexed with PAGA can reduce the development of insulitis in non-obese diabetic (NOD) mice. PAGA/mIL-10 plasmid complexes were stable for more than 60 min, but the naked DNA was destroyed within 10 min by DNase I. The PAGA/DNA complexes were injected into the tail vein of 3-week-old NOD mice. Serum mIL-10 level peaked at 5 days after injection, and could be detected for more than 9 weeks. The prevalence of severe insulitis on 12-week-old NOD mice was markedly reduced by the intravenous injection of PAGA/DNA complex (15.7%) compared with that of naked DNA injection (34.5%) and non-treated controls (90.9%). In conclusion, systemic administration of pCAGGS mIL-10 plasmid/PAGA complexes can reduce the severity of insulitis in NOD mice. This study shows that the PAGA/DNA complex has the potential for the prevention of autoimmune diabetes mellitus. Gene Therapy (2000) 7, 2099-2104.

Treatment of severe hypercholesterolemia in apolipoprotein E-deficient mice by intramuscular injection of plasmid DNA

We report on systemic delivery and long-term biological effects of apolipoprotein E (apoE) obtained by intramuscular (i.m.) plasmid DNA injection. ApoE plays an important role in lipoprotein catabolism and apoE knock-out mice develop severe hypercholesterolemia and diffuse atherosclerosis. We have injected apoE-deficient mice with 80 microg of a plasmid vector (pCMV-E3) encoding the human apoE3 cDNA under the control of the CMV promoter-enhancer in both posterior legs. Local expression of the transgene was demonstrated throughout 16 weeks. Human apoE3 recombinant protein reached 0.6 ng/ml serum level. After i.m. injection of pCMV-E3 expression vector the mean serum cholesterol concentrations decreased from 439 +/- 57 mg/dl to 253 +/- 99 mg/dl (P < 0.05) 2 weeks after injection and persisted at a significantly reduced level throughout the 16 weeks observation period (P < 0.005). Serum cholesterol was unaffected and reached an absolute level of 636 +/- 67 mg/dl in control groups. Finally, injection of pCMV-E3 into apoE-deficient mice resulted in a redistribution of cholesterol content between lipoprotein fractions, with a marked decrease in VLDL, IDL and LDL cholesterol content and an increase in HDL cholesterol. These results demonstrate that severe hypercholesterolemia in apoE-deficient mice can be effectively reversed by i.m. DNA injection, and indicate that this approach could represent a useful tool to correct several hyperlipidemic conditions resulting in atherosclerosis.