Antisense Oligonucleotides Down-Regulating Costimulation Confer Diabetes-Preventive Properties to Nonobese Diabetic Mouse Dendritic Cells

Immunomodulation of autoimmune diabetes by dendritic cells

The biology and properties of dendritic cells (DCs) have been intensely studied in the research areas of infectious diseases, tumor immunology, and vaccine development. This unique subset of immune cells has recently also moved to the center of interest for basic and clinical research in autoimmunity, owing not only to the extraordinary importance of DCs in the initiation and sustenance of adaptive immune responses, but also to more recent discoveries about their profound ability to control and downregulate ongoing T-cell responses. We review current progress of using DCs in mice for induction and propagation of autoimmune T-cell responses and their therapeutic potential to dampen or even stop beta-cell-specific autoimmunity. Finally, we offer our perspective on how basic research progress in DC technology, mostly from mouse models, may translate into emerging diagnostic and therapeutic applications for human type 1 diabetes.

Gene transfer of antisense B7.1 attenuates acute rejection against splenic allografts in rats

Blockade of CD80-CD28 costimulatory pathway induces unresponsiveness of T cells to alloantigens and protects allografts against immune rejection in numerous animal models. The aim of this study was to investigate whether blocking expression of B7.1 (CD80) on donor splenocytes by an antisense technique protected splenic allografts against immune rejection. Splenic grafts from Wistar-Furth rats were intra-arterially transfused with an antisense B7.1 expression vector, before they were transplanted into Sprague-Dawley rats. The rats were sacrificed at scheduled times, and the splenic allografts histologically examined. Antisense gene transfer resulted in marked down-regulation of B7.1 in donor spleens, hyporesponsiveness of recipient T cells, and attenuated acute immune rejection against splenic allografts. No obvious damage to skin, liver, or gut due to graft-versus-host disease was detected in the recipients. In conclusion, blocking expression of B7.1 in donor spleens by antisense gene therapy represented a potential alloantigen-specific immunosuppressive strategy to inhibit acute rejection against splenic allografts.

Induction of immune tolerance to facilitate beta cell regeneration in type 1 diabetes

A definitive cure for type 1 diabetes is currently being pursued with enormous effort by the scientific community. Different strategies are followed to restore physiologic production of insulin in diabetic patients. Restoration of self-tolerance remains the milestone that must be reached in order to move a step further and recover a cell source capable of independent and functional insulin production. Multiple strategies aimed at modulation of both central and peripheral immunity must be considered. Promising results now show that the immune system can be modulated in a way that acquisition of a "diabetes-suppressive" phenotype is possible. Once self-tolerance is achieved, reversal of the disease may be obtained by simply allowing physiologic rescue and/or regeneration of the beta cells to take place. Given that these outcomes have already been confirmed in humans, refinement of existing protocols along with novel methods adapted to T1DM reversal will allow translation into clinical trials.

Immunoregulatory dendritic cells to prevent and reverse new-onset Type 1 diabetes mellitus

Herein, the authors provide an overview of where dendritic cells lie in the immunopathology of autoimmune Type 1 diabetes mellitus and how dendritic cell-based therapy may be usefully translated to treat and reverse the disease. The immunopathology of Type 1 diabetes mellitus offers a number of windows at which immunotherapy can be applied to delay, stop and even reverse the autoimmune processes, especially in light of the recent antibody-based accomplishment of improvement in residual beta-cell mass function. As in almost all cell-specific inflammatory processes, dendritic cells are central regulators of diabetes onset and progression. This realisation, along with accumulating data confirming a role for dendritic cells in maintaining and inducing tolerance in multiple therapeutic settings, has prompted a line of investigation to identify the most effective embodiments of dendritic cells for diabetes immunotherapy.

Systemic expression of heme oxygenase-1 ameliorates type 1 diabetes in NOD mice

Heme oxygenase-1 (HO-1) is an enzyme with potent immunoregulatory capacity. To evaluate the effect of HO-1 on autoimmune diabetes, female NOD mice at 9 weeks of age received a single intravenous injection of a recombinant adeno-associated virus bearing HO-1 gene (AAV-HO-1; 0.5 x 10(10)-2.5 x 10(10) viruses/mouse). In a dose-dependent manner, HO-1 transduction reduced destructive insulitis and the incidence of overt diabetes examined over a 15-week period. HO-1-mediated protection was associated with a lower type 1 T-helper cell (Th1)-mediated response. Adaptive transfer experiments in NOD.scid mice demonstrated that splenocytes isolated from AAV-HO-1-treated mice were less diabetogenic. Flow cytometry analysis revealed no significant difference in the percentages of CD4(+)CD25(+) regulatory T-cells between saline-treated and AAV-HO-1-treated groups. However, the CD11c(+) major histocompatibility complex II(+) dendritic cell population was much lower in the AAV-HO-1-treated group. A similar protective effect against diabetes was observed in NOD mice subjected to carbon monoxide (CO) gas (250 ppm CO for 2 h, twice per week). These data suggest that HO-1 slows the progression to overt diabetes in pre-diabetic NOD mice by downregulating the phenotypic maturity of dendritic cells and Th1 effector function. CO appears to mediate at least partly the beneficial effect of HO-1 in this disease setting.

Dendritic cell immunotherapy for autoimmune diabetes

Dendritic cells (DC) play important roles in the initiation of immune responses and maintenance of self-tolerance. We have been studying the role of DC in the pathogenesis of type 1 diabetes and exploring the ability of specific DC subsets to prevent diabetes in non-obese diabetic (NOD) mice. DC subsets that prevent diabetes in this model have a mature phenotype and induce the production of regulatory Th2 cells. We review here recent advances in this area and highlight the importance of optimizing culture conditions and purification methods in the isolation of therapeutic DC.

Immune tolerance induced by adoptive transfer of dendritic cells in an insulin-dependent diabetes mellitus murine model

AIM

To investigate the effect and underlying mechanisms of immune-tolerance induced by the adoptive transfer of bone marrow (BM)-derived dendritic cells (DC) in insulin-dependent diabetes mellitus (IDDM) mice.

METHODS

The IDDM model was established by a low dose of streptozotocin (STZ) in Balb/c mice. Two DC subpopulations were generated from the BM cells with granulocyte-macrophage colony-stimulating factor with or without interleukin-4. The purity and the T cell stimulatory capability of DC were identified. These cells were used to modulate autoimmune response in pre-diabetic mice. Blood glucose was examined weekly; pancreas tissues were taken for histopathological analysis, and CD4(+) T cells were isolated to detect lymphocyte proliferation by MTT assay and the ratio of CD4(+)CD25(+) T cells by fluorescence-activated cell sorting (FACS). The cytokine secretion was determined by ELISA analysis.

RESULTS

Two DC subsets were generated from BM, which have phenotypes of mature DC (mDC) and immature DC (iDC), respectively. The level of blood glucose decreased significantly by transferring iDC (P< 0.01) rather than mDC. Less lymphocyte infiltration was observed in the islets, and pancreatic structure was intact. In vitro, proliferation of lymphocytes decreased and the proportion of CD4(+)CD25(+) T cells increased remarkably, compared with the mDC-treated groups (P< 0.05), which were associated with increased level of the Th2 cytokine and reduced level of the Th1 cytokine after iDC transfer.

CONCLUSION

Our data showed that iDC transfer was able to confer protection to mice from STZ-induced IDDM. The immune-tolerance to IDDM may be associated with promoting the production of CD4(+)CD25(+) T cells and inducing regulatory Th2 responses in vivo.

Fetal calf serum-primed dendritic cells induce a strong anti-fetal calf serum immune response and diabetes protection in the non-obese diabetic mouse

In recent years, several investigators have shown that transfer of dendritic cells (DC) prevents diabetes development in non-obese diabetic (NOD) mice. Accumulating evidences showing that DC cultured in medium containing fetal calf serum (FCS) can induce a dominant unspecific immune response in tumor models after i.v. injection prompted us to investigate if the protecting effect of DC on diabetes development in NOD mice might be supported by the induction of an anti-FCS immune response in recipient mice. Five-week-old NOD mice were injected i.v. with FCS-cultured bone marrow-derived DC or PBS as control. Levels of anti-FCS and anti-bovine serum albumin (BSA) antibodies were measured in the serum of recipient mice. Anti-FCS cellular immune responses were also analysed after a single DC injection using in vitro proliferation of splenocytes either in RPMI supplemented with FCS, AIMV-BSA or RPMI containing autologous mouse serum or BSA as a read out. DC injection prevented diabetes development in NOD mice and high titers of anti-FCS and anti-BSA antibodies were detected in serum of all DC-injected mice. Besides, splenocytes isolated from DC-injected mice proliferated vigorously in the presence of bovine proteins in contrast to splenocytes isolated from control mice but removing bovine proteins abrogated the high level of proliferation of those splenocytes suggesting that lymphocytes have been primed against bovine proteins in vivo after DC injection. All together, our data show that DC transfer induced cellular and humoral anti-FCS immune responses in recipient NOD mice suggesting that the protective effect of DC relies on their unspecific immunostimulatory effects.

Rehabilitation of adaptive immunity and regeneration of beta cells

Type 1 Diabetes (T1D) is an autoimmune disease resulting from the destruction of pancreatic insulin-producing beta cells that most frequently occurs in genetically predisposed children. Recent observations illustrating the regenerative capability of the endocrine pancreas in addition to advances in stem cell and gene therapy technologies enable the exploration of alternatives to allogeneic islet transplantation. Living-cell-mediated approaches can abrogate autoimmunity and the consequent destruction of beta cells without the need for immunosuppressive drugs. Such approaches can be used as a foundation for new protocols that more easily translate to the clinical setting. The twin goals of controlling autoimmune disease and promoting stable regeneration of insulin-producing beta cells should be considered the cornerstones of the successful development of a cure for this chronic disease.

Dendritic Cells Expressing Transgenic Galectin-1 Delay Onset of Autoimmune Diabetes in Mice

Type 1 diabetes (T1D) is a disease caused by the destruction of the beta cells of the pancreas by activated T cells. Dendritic cells (DC) are the APC that initiate the T cell response that triggers T1D. However, DC also participate in T cell tolerance, and genetic engineering of DC to modulate T cell immunity is an area of active research. Galectin-1 (gal-1) is an endogenous lectin with regulatory effects on activated T cells including induction of apoptosis and down-regulation of the Th1 response, characteristics that make gal-1 an ideal transgene to transduce DC to treat T1D. We engineered bone marrow-derived DC to synthesize transgenic gal-1 (gal-1-DC) and tested their potential to prevent T1D through their regulatory effects on activated T cells. NOD-derived gal-1-DC triggered rapid apoptosis of diabetogenic BDC2.5 TCR-transgenic CD4+ T cells by TCR-dependent and -independent mechanisms. Intravenously administered gal-1-DC trafficked to pancreatic lymph nodes and spleen and delayed onset of diabetes and insulitis in the NODrag1(-/-) lymphocyte adoptive transfer model. The therapeutic effect of gal-1-DC was accompanied by increased percentage of apoptotic T cells and reduced number of IFN-gamma-secreting CD4+ T cells in pancreatic lymph nodes. Treatment with gal-1-DC inhibited proliferation and secretion of IFN-gamma of T cells in response to beta cell Ag. Unlike other DC-based approaches to modulate T cell immunity, the use of the regulatory properties of gal-1-DC on activated T cells might help to delete beta cell-reactive T cells at early stages of the disease when the diabetogenic T cells are already activated.

Regulatory T Cells and Systemic Lupus Erythematosus

CD4+CD25+ regulatory T cells (Treg) constitute an important mechanism of peripheral immune tolerance. Organ-specific autoimmune conditions, such as thyroiditis and insulin-dependent diabetes mellitus have been attributed to a breakdown of this tolerance mechanism. However, this T-cell subset has not been well studied in patients and mice with systemic lupus erythematosus (SLE; lupus). The information that has been gathered so far using new tools that discriminate Treg from activated T cells indicates that reduced numbers of Treg may exist in patients with lupus. In addition, potential defects in SLE Treg function have been documented in humans and mice. Our group has demonstrated equivalent proportions of thymic Treg in lupus prone and normal mice. We therefore propose that Treg function in SLE is the more important factor to address in future studies of murine lupus. Recent studies have shown that Toll-like receptor (TLR) ligation can result in an abrogation of Treg-mediated suppression; specifically ligation of TLR-2, -4, -8 and -9. We address this new information about TLRs and Treg and propose a model for Treg tolerance breakdown to nucleic acid-binding SLE autoantigens.

Is facilitating pancreatic beta cell regeneration a valid option for clinical therapy?

Type 1 diabetes (T1D) is an autoimmune disease in which the clinical onset most frequently presents in adolescents who are genetically predisposed. There is accumulating evidence that the endocrine pancreas has regenerative properties, that hematopoietic chimerism can abrogate destruction of beta cells in autoimmune diabetes, and that, in this manner, physiologically sufficient endogenous insulin production can be restored in clinically diabetic NOD mice. Recapitulating what also has been seen sporadically in humans, we set out to test reliable and clinically translatable alternatives able to achieve these same goals. Recently, Tian and colleagues demonstrated that T1D can be prevented in genetically susceptible mice by substituting a "diabetes-susceptible" class II MHC beta chain with a "diabetes-resistant" allelic transgene on their hematopoietic stem cells through gene supplantation. The expression of the newly formed diabetes-resistant molecule in the reinfused hematopoietic cells was sufficient to prevent T1D onset even in the presence of the native, diabetogenic molecule. If this approach to obtain autoimmunity abrogation could facilitate a possible recovery of autologous insulin production in diabetic patients, safe induction of an autoimmunity-free status might become a new promising therapy for T1D.

Suppression of complement regulatory proteins (CRPs) exacerbates experimental autoimmune anterior uveitis (EAAU)

This study was undertaken to explore the role of complement regulatory proteins (CRPs) in experimental autoimmune anterior uveitis (EAAU). We observed that the levels of CRPs, Crry and CD59, in the eyes of Lewis rats increased during EAAU and remained elevated when the disease resolved. The in vivo role of these CRPs in EAAU was explored using neutralizing mAbs, antisense oligodeoxynucleotides (AS-ODNs), and small interfering RNAs against rat Crry and CD59. Suppression of Crry in vivo at days 9, 14, or 19 by neutralizing mAb or AS-ODNs resulted in the early onset of disease, the exacerbation of intraocular inflammation, and delayed resolution. Suppression of CD59 was only effective when the Abs and ODNs were given before the onset of disease. The most profound effect on the disease was observed when a mixture of Crry and CD59 mAbs or AS-ODNs was administered. A similar effect was observed with a combination of Crry and CD59 small interfering RNA. There was no permanent histologic damage to ocular tissue after the inflammation cleared in these animals. Increased complement activation as determined by increased deposition of C3, C3 activation fragments, and membrane attack complex was observed in the eyes of Lewis rats when the function and/or expression of Crry and CD59 was suppressed. Thus, our results suggest that various ocular tissues up-regulate the expression of Crry and CD59 to avoid self-injury during autoimmune uveitis and that these CRPs play an active role in the resolution of EAAU by down-regulating complement activation in vivo.

Immunization with murine breast cancer cells treated with antisense oligodeoxynucleotides to type I insulin-like growth factor receptor induced an antitumoral effect mediated by a CD8+ response involving Fas/Fas ligand cytotoxic pathway

We have demonstrated that in vivo administration of phosphorothioate antisense oligodeoxynucleotides (AS[S]ODNs) to type I insulin-like growth factor receptor (IGF-IR) mRNA resulted in inhibition of C4HD breast cancer growth in BALB/c mice. The present study focused on whether in vivo administration of C4HD tumor cells pretreated with IGF-IR AS[S]ODN and irradiated could provide protection against C4HD wild-type tumor challenge and also on elucidating the mechanism mediating this effect. Our results showed that mice immunized with IGF-IR AS[S]ODN-treated C4HD cells experienced a growth inhibition of 53.4%, 61.6%, and 60.2% when compared with PBS-treated mice, wild-type C4HD cell-injected mice, or phosphorothioate sense oligodeoxynucleotide-treated C4HD cell-injected mice, respectively. The protective effect was C4HD-specific, because no cross-protection was observed against other syngeneic mammary tumor lines. The lack of protection against tumor formation in nude mice indicated that T cells were involved in the antitumoral response. Furthermore, cytotoxicity and splenocyte proliferation assays demonstrated that a cellular CD8(+)-dependent immune response, acting through the Fas/Fas ligand death pathway, could be mediating the antitumor effect induced by immunization with AS[S]ODN-treated cells. Immunization also induced splenocytes to produce Ag-dependent IFN-gamma, indicating the presence of a type 1 response. We demonstrated for the first time that IGF-IR AS[S]ODN treatment of breast cancer cells induced expression of CD86 and heat shock protein 70 molecules, both involved in the induction of the immunogenic phenotype. Immunization with these tumor immunogens imparted protection against parental tumor growth through activation of a specific immune response.

Clinical application of expanded CD4+25+ cells

A central goal immunologists has been to develop targeted therapies that will induce or maintain immunologic tolerance in the absence of potentially harmful immunosuppression. The ability to isolate and expand regulatory T-cell populations with immune suppressive activity will enable new forms of adoptive immunotherapy that may achieve this long held dream. Assuming that certain technical challenges regarding the manufacturing of regulatory T cells can be overcome, a wide variety of clinical applications can be envisioned using adoptively transferred CD4(+)CD25(+) regulatory T cells. It is likely that suppressor T cells will first be tested for their ability to prevent or treat graft-versus-host disease (GVHD) following allogeneic bone marrow or stem cell transplantation. A related approach will be clinical studies to induce allogeneic or xenogeneic tolerance using regulatory T cells in solid organ transplantation. A more technically challenging approach will be the use of regulatory T-cell therapy for autoimmune disorders. Finally on the horizon are approaches that will use genetically engineered lymphocytes to replace regulatory T cells in the immune dysregulation, polyendocrinopathy, enteropathy, X-linked (IPEX) syndrome, and potentially to create more potent regulatory T (Treg) cells with enhanced suppressive activity.

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.

Facilitating physiologic self-regeneration: a step beyond islet cell replacement

Type 1 diabetes (T1D) is an autoimmune disease, the clinical onset of which most frequently presents in children and adolescents who are genetically predisposed. T1D is characterized by specific insulin-producing beta cell destruction. The well-differentiated and specialized islet beta cells seem to physiologically retain the ability to compensate for the cells lost by reproducing themselves, whereas undifferentiated cell sources may help in generating new ones, even while the autoimmune process takes place. Diabetes clinical onset, i.e., establishment of a detectable, chronic hyperglycemia, occurs at a critical stage when autoimmunity, having acted for a while, supersedes the regenerative effort and reduces the number of beta cells below the physiologic threshold at which the produced insulin becomes insufficient for the body's needs. Clinical solutions aimed at avoiding cumbersome daily insulin administrations by the reestablishment of physiologic insulin production, like whole pancreas or pancreatic islet allotransplantation, are limited by the scarcity of pancreas donors and by the toxic effects of the immunosuppressive drugs administered to prevent rejection. However, new accumulating evidence suggests that, once autoimmunity is abrogated, the endocrine pancreas properties may be sufficient to allow the physiological regenerative process to restore endogenous insulin production, even after the disease has become clinically manifest. Knowledge of these properties of the endocrine pancreas suggests the testing of reliable and clinically translatable protocols for obliterating autoimmunity, thus allowing the regeneration of the patient's own endocrine cells. The safe induction of an autoimmunity-free status might become a new promising therapy for T1D.

Dendritic cell subsets and type I diabetes: focus upon DC-based therapy

Type I diabetes (TID) is an autoimmune disease characterized by a T cell-mediated destruction of insulin-producing beta cells. The destructive response is believed to be caused by a Th1-dominant immune attack targeted to several autoantigens including glutamate decarboxylase (GAD) and insulin in the presence of an ineffective regulatory response. The development of both the Th1 biased effector cells as well as regulatory T-cell response can be guided by dendritic cells (DC), professional antigen presenting cells (APC) that efficiently capture and process self antigens, and present them to T-cells. These APC can either prime effector T cells or activate regulatory T cells depending on the function of the DC or perhaps distinct DC subsets. Because DC uniquely orchestrate the delicate balance between T cell immunity and regulation, efforts are being made to investigate the potential of DC therapy for the prevention and/or treatment of autoimmune diseases such as TID through augmentation of regulatory responses. As the subset and functional stage of DC appear to be critical for tolerance induction, several strategies for engineering these cells are emerging. Furthermore, the delineation of T1D-associated target antigens allows for the development of antigen-specific DC-based therapy. Here we review recent advances and considerations for this exciting approach and discuss the selection of the appropriate DC subset, self-peptide, and route of administration for the optimization of immunotherapy using these cells.

SOCS1 restricts dendritic cells' ability to break self tolerance and induce antitumor immunity by regulating IL-12 production and signaling

DC-based tumor vaccine research has largely focused on enhancing DC maturation/costimulation and antigen presentation in order to break tolerance against self tumor-associated antigens. DC immunization can activate autoreactive T cells but rarely causes autoimmune pathologies, indicating that self tolerance at the host level is still maintained in the vaccinated hosts. This study in mice reveals a novel regulatory mechanism for the control of self tolerance at the host level by DCs through the restriction of positive cytokine feedback loops by cytokine signaling inhibitor SOCS1. The study further finds the requirement of persistent antigen presentation by DCs for inducing pathological autoimmune responses against normal tissues and tumor, which can be achieved by silencing SOCS1 to unleash the unbridled signaling of IL-12 and the downstream cytokine cascade. However, the use of higher-affinity self peptides, enhancement of DC maturation, and persistent stimulation with cytokines or TLR agonists fail to break tolerance and induce pathological antitumor immunity. Thus, this study indicates the necessity of inhibiting SOCS1, an antigen presentation attenuator, to break self tolerance and induce effective antitumor responses.

Targeted gene therapy of autoimmune diseases: advances and prospects

Idealized gene therapy of autoimmune diseases would mean getting the right drug to the right place at the right time to affect the right mechanism of action. In other words, a specific gene therapy strategy needs to have functional, spatial and temporal specificity. Functional specificity implies targeting the cellular, molecular and/or genetic mechanisms relevant to the disease, without affecting nondiseased organs or tissues through mechanisms that cause adverse effects. Spatial specificity means the delivery of the therapeutic agent exclusively to sites and cells that are relevant to the disease. Temporal specificity is, in principle, synonymous with controlled on-demand expression of the therapeutic gene and thus represents a major safety feature. This article reviews recent advances in strategies to use gene therapy in the treatment of autoimmune diseases.

Regeneration of the pancreatic beta cell

Type 1 diabetes is the result of an autoimmune attack against the insulin-producing beta cells of the endocrine pancreas. Current treatment for patients with type 1 diabetes typically involves a rigorous and invasive regimen of testing blood glucose levels many times a day along with subcutaneous injections of recombinant DNA-derived insulin. Islet transplantation, even with its substantially improved outcome in recent years, is still not indicated for pediatric patients. However, in light of the fact that some regenerative capabilities of the endocrine pancreas have been documented and recent research has shown that human ES cell lines can be derived in vitro, this review discusses whether it is practical or even possible to combine these lines of research to more effectively treat young diabetic patients.

Regeneration of the pancreatic beta cell

Type 1 diabetes is the result of an autoimmune attack against the insulin-producing beta cells of the endocrine pancreas. Current treatment for patients with type 1 diabetes typically involves a rigorous and invasive regimen of testing blood glucose levels many times a day along with subcutaneous injections of recombinant DNA-derived insulin. Islet transplantation, even with its substantially improved outcome in recent years, is still not indicated for pediatric patients. However, in light of the fact that some regenerative capabilities of the endocrine pancreas have been documented and recent research has shown that human ES cell lines can be derived in vitro, this review discusses whether it is practical or even possible to combine these lines of research to more effectively treat young diabetic patients.