Dendritic cells transduced to express interleukin-4 prevent diabetes in nonobese diabetic mice with advanced insulitis

Prolongation of heart allograft survival by immature dendritic cells generated from recipient type bone marrow progenitors

Recent studies suggest that particular dendritic cells (DC) subpopulations may be tolerogenic. To test the capacity of different DC subpopulations to modulate allograft rejection, we generated two distinct populations of rat bone marrow-derived DCs (BMDC) with low doses of GM-CSF and IL-4. The non-adherent population (nBMDC), which are the 'classical' DCs was able to stimulate naive allogeneic T cells and could be induced to completely mature using various stimuli. In contrast, the adherent population (aBMDC), which displayed an immature phenotype, was unable to stimulate T cells and was more resistant to maturation. We found that syngeneic aBMDCs, injected one day before transplantation, induced significant prolongation of heart allograft survival and decreased anti-donor humoral and cellular responses. Similarly, syngeneic aBMDCs inhibited T-cell responses to KLH in the spleen but not in lymph node in a KLH immunization model without graft. This effect was not antigen specific and could be reversed using an inhibitor of inducible nitric oxide synthase. This compartmentalized inhibition could be in part explained by the fact that the majority of syngeneic adherent cells administered intravenously were found in the spleen with some of them reaching the T-cell areas. These data suggest that syngeneic aBMDCs can modulate immune responses.

Autoimmune diabetes is suppressed by transfer of proinsulin-encoding Gr-1+ myeloid progenitor cells that differentiate in vivo into resting dendritic cells

The nature of the T-cell response to antigen is governed by the activation state of the antigen-presenting dendritic cell (DC). Immature or resting DCs have been shown to induce T-cell responses that may protect against the development of autoimmune disease. Effectively harnessing this "tolerogenic" effect of resting DCs requires that it be disease-specific and that activation of DCs by manipulation ex vivo is avoided. We reasoned that this could be achieved by transferring in vivo partially differentiated myeloid progenitor cells encoding a disease-specific autoantigen. With the aim of preventing autoimmune diabetes, we transferred myeloid progenitor cells encoding proinsulin into NOD mice. Bone marrow (BM) was cultured in granulocyte macrophage colony-stimulating factor (GM-CSF) and transforming growth factor-beta1, a cytokine combination that expands myeloid cells but inhibits terminal DC differentiation, to yield Gr-1(+)/CD11b(+)/CD11c(-) myeloid progenitor cells and a minor population of CD11c(+)/CD11b(+)/CD86(lo) immature DCs. After transfer, Gr-1(+) myeloid cells acquired the characteristics of resting DCs (CD11c(+)/MHC classII(int)/CD86(lo)/CD40(lo)). Gr-1(+) myeloid cells generated from transgenic NOD mice that expressed proinsulin controlled by a major histocompatibility complex (MHC) class II promoter, but not from wild-type NOD mice, transferred into 4-week-old female NOD mice significantly suppressed diabetes development. The transfer of DC progenitors encoding a disease-specific autoantigen is, therefore, an effective immunotherapeutic strategy that could be applied to humans.

In Vivo Imaging of Autoimmune Disease in Model Systems

Autoimmune diseases are characterized by infiltration of the target tissue with specific immune cells that ultimately leads to the destruction of normal tissue and the associated disease. There is a need for imaging tools that allow the monitoring of ongoing inflammatory disease as well as the response to therapy. We discuss new magnetic resonance imaging-based technologies that have been used to monitor inflammation and disease progression in animal models of type 1 diabetes, multiple sclerosis, and rheumatoid arthritis. Therapeutic strategies for these diseases include the transfer of immune cells, such as dendritic cells, with the aim of preventing or halting the disease course. We discuss several new MRI labeling techniques developed to allow tracking of immune cells in vivo. These include direct ex vivo labeling techniques as well as the genetic modification of cells to allow them to produce their own contrast agents. This is an area of intense recent research and can be expanded to other conditions such as cancer.

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.

IgG4-subclass of glutamic acid decarboxylase antibody is more frequent in latent autoimmune diabetes in adults than in type 1 diabetes

AIMS/HYPOTHESIS

Glutamic acid decarboxylase autoantibodies (GADA) are the most frequent beta-cell-specific autoantibodies in type 1 diabetes and in latent autoimmune diabetes in adults (LADA). The autoimmune attack on pancreatic islet cells is associated with a T helper 1 cell (T(h)1) response, mainly represented by IgG(1)-subclass in humans. It has been proposed that the presence of IgG(4) may be associated with a T(h)2 response. The aim of our study was to compare the GADA IgG-subclass distribution between adult patients with type 1 diabetes and LADA.

METHODS

Patients with type 1 diabetes (n=45) and patients with LADA (n=60) were included. Radioimmunoprecipitation assay with IgG-subclass specific Sepharose (IgG(1), IgG(2), IgG(3) and IgG(4)) was used to precipitate the antibody/antigen-complex.

RESULTS

We only detected IgG(4)-subclass of GADA in subjects with LADA (26.7%; p<0.001). IgG(1) was the most common GADA-subclass in both groups, however IgG(1) as the solely expressed subclass was more common among type 1 diabetic patients (77.8%; p<0.05). The rank order of the frequencies of IgG-subclasses in type 1 diabetes was IgG(1)>IgG(3)>IgG(2)>IgG(4) and in LADA patients IgG(1)>IgG(4)>IgG(2)>IgG(3).

CONCLUSIONS/INTERPRETATION

The difference in GADA IgG-subclasses could indicate a different immune response, possibly an altered balance between T(h)1 and T(h)2 cytokine profile in pancreatic islets. This difference could contribute to the slower rate of beta cell destruction in LADA patients, as reflected by a higher C-peptide level at clinical onset.

Gene therapy for autoimmune diseases: quo vadis?

Biological therapies using antibodies and cytokines are becoming widespread for the treatment of chronic inflammatory autoimmune diseases. However, these treatments have several limitations - such as expense, the need for repeated injections and unwanted side-effects - that can be overcome by genetic delivery. This review summarizes the ingenuity, sophistication and variety of gene-therapy approaches that have been taken in the design of therapeutic molecules and vectors, the engineering of cells and the regulation of gene expression for the targeting of disease outcome. We focus our attention on multiple sclerosis, type 1 diabetes and rheumatoid arthritis.

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

Phenotypically "immature" dendritic cells (DCs), defined by low cell surface CD40, CD80, and CD86 can elicit host immune suppression in allotransplantation and autoimmunity. Herein, we report the most direct means of achieving phenotypic immaturity in NOD bone marrow-derived DCs aiming at preventing diabetes in syngeneic recipients. CD40, CD80, and CD86 cell surface molecules were specifically down-regulated by treating NOD DCs ex vivo with a mixture of antisense oligonucleotides targeting the CD40, CD80, and CD86 primary transcripts. The incidence of diabetes was significantly delayed by a single injection of the engineered NOD DCs into syngeneic recipients. Insulitis was absent in diabetes-free recipients and their splenic T cells proliferated in response to alloantigen. Engineered DC promoted an increased prevalence of CD4(+)CD25(+) T cells in NOD recipients at all ages examined and diabetes-free recipients exhibited significantly greater numbers of CD4(+)CD25(+) T cells compared with untreated NOD mice. In NOD-scid recipients, antisense-treated NOD DC promoted an increased prevalence of these putative regulatory T cells. Collectively, these data demonstrate that direct interference of cell surface expression of the major costimulatory molecules at the transcriptional level confers diabetes protection by promoting, in part, the proliferation and/or survival of regulatory T cells. This approach is a useful tool by which DC-mediated activation of regulatory T cells can be studied as well as a potential therapeutic option for type 1 diabetes.

T-cell anergy

Self-reactive T cells that escape negative selection in the thymus must be inactivated in the periphery. Anergy constitutes one means of imposing peripheral tolerance. Anergic T cells are functionally inactivated and unable to initiate a productive response even when antigen is encountered in the presence of full co-stimulation. Recent studies have provided new insights into the mechanisms responsible for the induction and maintenance of T-cell anergy. These studies have helped clarify the nature of the signals that induce tolerance, the cells able to deliver them and the molecular processes that underlie the unresponsive state.

Qualitative and quantitative abnormalities in splenic dendritic cell populations in NOD mice

The phenotype and function of splenic DC populations from diabetes-prone NOD mice were characterized and compared to DC from diabetes-resistant strains in the presence or absence of Flt3 ligand (FL) treatment. NOD mice were found to have significantly fewer CD8alpha+ DC than both B10.BR and C57BL/6 mice, and this defect was reversed by FL treatment. Freshly isolated CD8alpha+ and CD8alpha- DC from all three strains were found to express similar levels of costimulatory molecules and this was similar in both FL-treated and untreated animals. IL-12 p40 production was significantly lower in purified CD11c+ DC from NOD mice compared to DC from C57BL/6 or B10.BR mice. CD8alpha+ DC isolated from NOD mice produced lower levels of IL-12p40 than CD8alpha+ DC from C57CBL/6 and this was dependent on the nature of the stimulus given. In contrast both CD8alpha+ and CD8alpha- DC from FL-treated mice produced high levels of IL-12p40 following activation, but only the CD8alpha- DC produced IL-12p70. Functionally, freshly isolated CD8alpha- DC were more stimulatory than CD8alpha+ DC in a primary allogeneic mixed lymphocyte reaction. However, DC maturation resulted in increased T cell stimulatory capacity for both DC subsets, and this pattern was seen in all strains. These results demonstrate significant differences in phenotype and function of splenic NOD CD8alpha+ DC, and further suggest that FL treatment may reverse some of these abnormalities.

The TRAIL to arthritis

Antigen-specific lymphocytes are involved in synovial proliferation within inflamed joints. Activated lymphocytes and synoviocytes from patients with rheumatoid arthritis express receptors that can bind TNF-related apoptosis-inducing ligand (TRAIL). A new study demonstrates that DCs pulsed with collagen and transduced with an adenovirus-based vector able to express TRAIL limit the incidence of arthritis in a model of collagen-induced arthritis and joint inflammation. These results suggest that gene-modified cell therapy represents a therapeutic option for systemic rheumatic diseases.

Dendritic cells, T cell tolerance and therapy of adverse immune reactions

Dendritic cells (DC) are uniquely able to either induce immune responses or to maintain the state of self tolerance. Recent evidence has shown that the ability of DC to induce tolerance in the steady state is critical to the prevention of the autoimmune response. Likewise, DC have been shown to induce several type of regulatory T cells including Th2, Tr1, Ts and NKT cells, depending on the maturation state of the DC and the local microenvironment. DC have been shown to have therapeutic value in models of allograft rejection and autoimmunity, although no success has been reported in allergy. Several strategies, including the use of specific DC subsets, genetic modification of DC and the use of DC at various maturation stages for the treatment of allograft rejection and autoimmune disease are discussed. The challenge for the future use of DC therapy in human disease is to identify the appropriate DC for the proposed therapy; a task made more daunting by the extreme plasticity of DC that has recently been demonstrated. However, the progress achieved to date suggests that these are not insurmountable obstacles and that DC may become a useful therapeutic tool in transplantation and autoimmune disease.