Prevention Of Autoimmune Diseases Research Articles

CD40 Ligand in Pathogenesis of Autoimmune Ovarian Disease of Day 3-Thymectomized Mice: Implication for CD40 Ligand Antibody Therapy

The blockade of CD40 ligand (CD40L) is effective in autoimmune disease prevention. Recently, a brief period of CD40L mAb treatment was reported to induce tolerance and enhancement of CD4(+)CD25(+) regulatory T cell activity. We therefore determined the efficacy of CD40L mAb treatment in autoimmunity that resulted from CD4(+)CD25(+) regulatory T cell deficiency. Autoimmune ovarian disease (AOD) and oocyte autoantibody response of day 3-thymectomized (d3tx) mice were inhibited by continuous CD40L mAb treatment from day 3, or from days 10-14, whereas CD40L mAb treatment confined to the neonatal week was ineffective. The enhanced expression of memory markers (CD44 and CD62L(low)) on CD4(+) T cells of the d3tx mice was unaffected by CD40L mAb treatment. In contrast, their increased T cell activation markers (CD69 and CD25) were eliminated by CD40L mAb treatment. Moreover, ex vivo activated T cells of d3tx mice expressed elevated intracellular IFN-gamma, and this was also blocked by CD40L mAb. The memory T cells, although nonpathogenic in CD40L mAb-positive environment, transferred severe AOD to CD40L mAb(-) neonatal recipients. Most importantly, CD40L mAb treatment inhibited AOD in recipients of T cells from d3tx donors with severe AOD and led to regression of AOD in d3tx mice documented at 4 wk. Therefore, 1) the continuous presence of CD40L mAb both prevents and causes regression of AOD in the d3tx mice; and 2) the multiple steps of the d3tx autoimmune disease, including T cell activation, cytokine production, T cell-mediated inflammation, and tissue injury, are CD40L dependent.

Protection against experimental autoimmune encephalomyelitis generated by a recombinant adenovirus vector expressing the V beta 8.2 TCR is disrupted by coadministration with vectors expressing either IL-4 or -10.

Adenovirus vectors are increasingly being used for genetic vaccination and may prove highly suitable for intervention in different pathological conditions due to their capacity to generate high level, transient gene expression. In this study, we report the use of a recombinant adenovirus vector to induce regulatory responses for the prevention of autoimmune diseases through transient expression of a TCR beta-chain. Immunization of B10.PL mice with a recombinant adenovirus expressing the TCR Vbeta8.2 chain (Ad5E1 mVbeta8.2), resulted in induction of regulatory type 1 CD4 T cells, directed against the framework region 3 determinant within the B5 peptide (aa 76-101) of the Vbeta8.2 chain. This determinant is readily processed and displayed in an I-A(u) context, on ambient APC. Transient genetic delivery of the TCR Vbeta8.2 chain protected mice from Ag-induced experimental autoimmune encephalomyelitis. However, when the Ad5E1 mVbeta8.2 vector was coadministered with either an IL-4- or IL-10-expressing vector, regulation was disrupted and disease was exacerbated. These results highlight the importance of the Th1-like cytokine requirement necessary for the generation and activity of effective regulatory T cells in this model of experimental autoimmune encephalomyelitis.

The role of CD4+CD25+ immunoregulatory T cells in the induction of autoimmune gastritis.

A number of experimental models of organ-specific autoimmunity involve a period of peripheral lymphopenia prior to disease onset. There is now considerable evidence that the development of autoimmune disease in these models is due to the absence of CD4+CD25+ regulatory T cells. However, the role of CD4+CD25+ regulatory T cells in the prevention of autoimmune disease in normal individuals has not been defined. Here we have assessed the affect of depletion of CD4+CD25+ regulatory T cells in BALB/c mice on the induction of autoimmune gastritis. The CD4+CD25+ T cell population was reduced to 95% of the original population in adult thymectomized mice by treatment with anti-CD25 mAb. By 48 days after the anti-CD25 treatment, the CD4+CD25+ regulatory T cell population had returned to a normal level. Treatment of thymectomized adult mice for up to 4 weeks with anti-CD25 mAb did not result in the development of autoimmune gastritis. Furthermore, we have demonstrated that depletion of CD4+CD25+ regulatory T cells, together with transient CD4+ T lymphopenia, also did not result in the development of autoimmune gastritis, indicating that peripheral expansion of the CD4+ T cell population, per se, does not result in autoimmunity in adult mice. On the other hand, depletion of CD4+CD25+ T cells in 10-day-old euthymic mice resulted in a 30% incidence of autoimmune gastritis. These data suggest that CD4+CD25+ regulatory T cells may be important in protection against autoimmunity while the immune system is being established in young animals, but subsequently other factors are required to initiate autoimmunity.

Human plasmacytoid-derived dendritic cells and the induction of T-regulatory cells

Suppression by T-regulatory (Tr) cells is essential for the induction of T-cell tolerance and the prevention of autoimmune diseases, organ rejection, and graft-versus-host disease. Increasing attention has been devoted to understand the role of dendritic cells (DC) in the control of Tr-cell differentiation. Here we review the recent evidence that cluster designation (CD)40-ligand activated plasmacytoid-derived DCs (DC2) have the ability to induce primary Tr-cell differentiation. We propose that in addition to the regulatory functions of immature myeloid DC, Tr-cell induction by DC2 represents a nonredundant mechanism for the safeguard of peripheral T-cell tolerance. DC2 can be used as tool to drive potent antigen specific Tr-cell differentiation and expansion in vitro and in vivo.

Mixed peripheral blood stem cell transplantation for autoimmune disease in BXSB/MpJ mice

We examined whether mixed allogeneic transplantation with syngeneic plus allogeneic peripheral blood stem cells (PBSCs) is sufficient to interrupt autoimmune processes in BXSB mice and confer a potential therapeutic option for the treatment of patients with autoimmune diseases. Eight-week-old BXSB mice were lethally irradiated and reconstituted with BALB/c (H-2(d))+BXSB (H-2(b)) PBSCs, in which the number of injected allogeneic progenitor cells was 5 times that of syngeneic progenitor cells. The survival of mixed PBSC chimeras (BALB/c+BXSB-->BXSB) was 80% at the age of 48 weeks, whereas that of full chimeras (BALB/c-->BXSB) was 90%. Mixed PBSC transplantation (PBSCT) prevented the production of anti-DNA antibodies and the development of lupus nephritis in BXSB recipients and induced tolerance to both allogeneic and syngeneic antigens. Moreover, mixed chimeras exhibited immunological functions superior to fully allogeneic chimeras. On the other hand, increases in the number of BXSB PBSCs resulted in the transfer of lupus nephritis in BXSB+BALB/c-->BALB/c mice. Thus, the number of hematopoietic progenitor cells from normal mice proved critical to the prevention of autoimmune diseases. We propose that mixed allogeneic PBSCT for the interruption of the autoimmune process can be carried out by injecting increased numbers of allogeneic normal hematopoietic progenitor cells to prevent the relapse of autoimmune diseases, although it is necessary to decide upon a minimum dose of syngeneic PBSCs to achieve the desired beneficial effects on autoimmunity.

Protein kinase Cdelta controls self-antigen-induced B-cell tolerance.

Interaction of a B cell expressing self-specific B-cell antigen receptor (BCR) with an auto-antigen results in either clonal deletion or functional inactivation. Both of these processes lead to B-cell tolerance and are essential for the prevention of auto-immune diseases. Whereas clonal deletion results in the death of developing autoreactive B cells, functional inactivation of self-reactive B lymphocytes leads to complex changes in the phenotype of peripheral B cells, described collectively as anergy. Here we demonstrate that deficiency in protein kinase Cdelta (PKC-delta) prevents B-cell tolerance, and allows maturation and terminal differentiation of self-reactive B cells in the presence of the tolerizing antigen. The importance of PKC-delta in B-cell tolerance is further underscored by the appearance of autoreactive anti-DNA and anti-nuclear antibodies in the serum of PKC-delta-deficient mice. As deficiency of PKC-delta does not affect BCR-mediated B-cell activation in vitro and in vivo, our data suggest a selective and essential role of PKC-delta in tolerogenic, but not immunogenic, B-cell responses.

The Role of NK Cells in Autoimmune Disease

NK cells are a subset of mononuclear cells which have long been suspected of playing an immuno-regulatory role in the prevention of autoimmune diseases. Here, we briefly discuss the characteristics of NK cells--particularly what is known of their functional capabilities--and summarise the major findings from studies of NK cells in human and animals susceptible to three major autoimmune diseases: multiple sclerosis, systemic lupus erythematosus and type 1 (autoimmune) diabetes mellitus. In each case, we present the evidence for an association between disease and deficiencies in NK cells. The prospect of clinical interventions that stimulate NK cell activity are discussed and the current status described.

Approaches to detecting immunotoxic effects of environmental contaminants in humans.

Experimental animal studies indicate that environmental contaminants can have adverse effects on several organs and tissues of the immune system. Such effects are known to lead to increased host susceptibility to microbial infections and to compromised immunosurveillance mechanisms normally instrumental in the elimination of neoplastic cells and the prevention of autoimmune diseases. Evaluation of the potential risk environmental contaminants pose to the human immune system is currently accomplished via extrapolation of experimentally derived animal data to humans. Presently, this process requires that uncertainty factors such as interspecies differences and genetic variability be considered. Naturally, the process of risk assessment would be greatly facilitated if it were based on clinically relevant data derived from studying humans known to be exposed to environmental contaminants. However, the existing human data are scarce and often described as very limited in scope. To generate the much-needed human data we need to identify a set of clinically relevant immunologic end points that, when adequately standardized, can be incorporated easily into the design of prospective epidemiologic studies.

Human CD4+CD25+ cells: a naturally occurring population of regulatory T cells

AbstractDespite thymic deletion of cells with specificity for self-antigens, autoreactive T cells are readily detectable in the normal T-cell repertoire. In recent years, a population of CD4+ T cells that constitutively express the interleukin-2 receptor-α chain, CD25, has been shown to play a pivotal role in the maintenance of self-tolerance in rodent models. This study investigated whether such a regulatory population exists in humans. A population of CD4+CD25+ T cells, taken from the peripheral blood of healthy individuals and phenotypically distinct from recently activated CD4+ T cells, was characterized. These cells were hyporesponsive to conventional T-cell stimuli and capable of suppressing the responses of CD4+CD25− T cells in vitro. Addition of exogenous interleukin-2 abrogated the hyporesponsiveness and suppressive effects of CD4+CD25+ cells. Suppression required cell-to-cell contact but did not appear to be via the inhibition of antigen-presenting cells. In addition, there were marked changes in the expression of Notch pathway molecules and their downstream signaling products at the transcriptional level, specifically in CD4+CD25+ cells, suggesting that this family of molecules plays a role in the regulatory function of CD4+CD25+ cells. Cells with similar phenotype and function were detected in umbilical venous blood from healthy newborn infants. These results suggest that CD4+CD25+ cells represent a population of regulatory T cells that arise during fetal life. Comparison with rodent CD4+CD25+ cells suggests that this population may play a key role in the prevention of autoimmune diseases in humans.

Series Introduction: Autoimmune diseases: are markers ready for prediction?

An increasing number of individuals throughout the world are affected by autoimmune disease, a large and diverse group of disorders that are categorized by tissue injury or pathology. In general, these diseases are associated with humoral or cell-mediated immune reactions against one or more of the body’s own constituents, but it has been customary to divide autoimmune diseases into two categories — systemic, such as systemic lupus erythematosus, and organ-specific, such as autoimmune thyroiditis. The Perspective series beginning in this issue will address the ways in which autoantigen-specific responses arise, and the mechanisms by which they provoke cell type‐ and organ-specific pathologies. In addition, given our growing knowledge of etiologically significant autoantigens, one can envision that the occurrence of these diseases may soon be predictable in a clinical setting. How close are we, in fact, to taking this crucial step toward the management or prevention of autoimmune disorders?

Autoimmune diseases: are markers ready for prediction?

An increasing number of individuals throughout the world are affected by autoimmune disease, a large and diverse group of disorders that are categorized by tissue injury or pathology. In general, these diseases are associated with humoral or cell-mediated immune reactions against one or more of the body’s own constituents, but it has been customary to divide autoimmune diseases into two categories — systemic, such as systemic lupus erythematosus, and organ-specific, such as autoimmune thyroiditis. The Perspective series beginning in this issue will address the ways in which autoantigen-specific responses arise, and the mechanisms by which they provoke cell type– and organ-specific pathologies. In addition, given our growing knowledge of etiologically significant autoantigens, one can envision that the occurrence of these diseases may soon be predictable in a clinical setting. How close are we, in fact, to taking this crucial step toward the management or prevention of autoimmune disorders?

Modulatory effects of octreotide on anti-CD3 and dexamethasone-induced apoptosis of murine thymocytes

In an attempt to elucidate the effects of somatostatin on two crucial processes that regulated T-cell differentiation and selection in thymus in this study, we investigated in vivo and in vitro the effects of octreotide (SMS 201-995) on dynamics of apoptosis, induced by dexamethasone (DEX) or by anti-CD3 monoclonal antibodies (mAb). The data were estimated by analysis of absolute cellularity, DNA fragmentation and maturational stage of thymocytes, detecting the CD4 and/or CD8 and T cell receptor (TCR) expression on thymocytes. The results, obtained by estimation of subdiploid peak of DNA and ladder DNA formation, have shown that SMS given in vivo, may potentiate the early phase of DEX-induced nuclear fragmentation (at 24 h), accelerating simultaneously the elimination of thymic cells with double positive (DP) CD4 high CD8 high phenotype (expressed both as percentage and absolute number). On the contrary, SMS, given both in vivo and in vitro, down-regulated the late process (at 72 h) of nuclear fragmentation, induced by anti-CD3 mAb, minimizing simultaneously the elimination of DP cells (expressed both as percentage and absolute number). In anti-CD3-treated cultures of thymocytes, SMS retarded also the elimination of immature thymocytes, expressing the TRC α/β low or intermediate phenotype. The data emphasize that octreotide might have important regulatory effect on processes of thymic differentiation and maturation, which are crucial for T cell selection, induction of tolerance and prevention of autoimmune diseases.

Cutting Edge: Control of CD8+ T Cell Activation by CD4+CD25+ Immunoregulatory Cells

CD4(+)CD25(+) regulatory T cells inhibit organ-specific autoimmune diseases induced by CD4(+)CD25(-) T cells and are potent suppressors of CD4(+)CD25(-) T cell activation in vitro. We demonstrate that CD4(+)CD25(+) T cells also suppress both proliferation and IFN-gamma production by CD8(+) T cells induced either by polyclonal or Ag-specific stimuli. CD4(+)CD25(+) T cells inhibit the activation of CD8(+) responders by inhibiting both IL-2 production and up-regulation of IL-2Ralpha-chain (CD25) expression. Suppression is mediated via a T-T interaction as activated CD4(+)CD25(+) T cells suppress the responses of TCR-transgenic CD8(+) T cells stimulated with soluble peptide-MHC class I tetramers in the complete absence of APC. These results broaden the immunoregulatory role played by CD4(+)CD25(+) T cells in the prevention of autoimmune diseases, but also raise the possibility that they may hinder the induction of effector CD8(+) T cells to tumor or foreign Ags.

Immunosuppression by CD4+ regulatory T cells induced by chronic retroviral infection.

Normal levels of CD4(+) regulatory T cells are critical for the maintenance of immunological homeostasis and the prevention of autoimmune diseases. However, we now show that the expansion of CD4(+) regulatory T cells in response to a chronic viral infection can lead to immunosuppression. Mice persistently infected with Friend retrovirus develop approximately twice the normal percentage of splenic CD4(+) regulatory T cells and lose their ability to reject certain tumor transplants. The role of CD4(+) regulatory T cells was demonstrated by the transmission of immunosuppression to uninfected mice by adoptive transfers of CD4(+) T cells. CD4(+) T cells from chronically infected mice were also immunosuppressive in vitro, inhibiting the generation of cytolytic T lymphocytes in mixed lymphocyte cultures. Inhibition occurred at the level of blast-cell formation through a mechanism or mechanisms involving transforming growth factor-beta and the cell surface molecule CTLA-4 (CD152). These results suggest a possible explanation for HIV- and human T cell leukemia virus-I-induced immunosuppression in the absence of T cell depletion.

The heat shock response reduces myelin oligodendrocyte glycoprotein-induced experimental autoimmune encephalomyelitis in mice.

The stress response (SR) can block inflammatory gene expression by preventing activation of transcription factor nuclear factor-kappa B (NF-kappaB). As inflammatory gene expression contributes to the pathogenesis of demyelinating diseases, we tested the effects of the SR on the progression of the demyelinating disease experimental autoimmune encephalomyelitis (EAE). EAE was actively induced in C57BL/6 mice using an encephalitogenic myelin oligodendrocyte glycoprotein (MOG(35-55)) peptide. Whole body hyperthermia was used to induce a heat shock response (HSR) in immunized mice 2 days after the booster MOG(35-55) peptide injection. The HSR reduced the incidence of EAE by 70%, delayed disease onset by 6 days, and attenuated disease severity. The HSR attenuated leukocyte infiltration into CNS assessed by quantitation of perivascular infiltrates, and by reduced staining for CD4 and CD25 immunopositive T-cells. T-cell activation, assessed by the production of interferon gamma (IFNgamma) in response to MOG(35-55), was also decreased by the HSR. The HSR reduced inflammatory gene expression in the brain that normally occurs during EAE, including the early increase in RANTES (regulated on activation of normal T-cell expressed and secreted) expression, and the later expression of the inducible form of nitric oxide synthase. The early activation of transcription factor NF-kappaB was also blocked by the HSR. The finding that the SR reduces inflammation in the brain and the clinical severity of EAE opens a novel therapeutic approach for prevention of autoimmune diseases.

Mucosal antigen primes diabetogenic cytotoxic T-lymphocytes regardless of dose or delivery route.

Administration of antigens via mucosal routes, such as orally or intranasally, can induce specific immunological tolerance and has been used as a rational basis for the treatment of autoimmune diseases, including type 1 diabetes. Recently, however, orally delivered antigens were shown to induce CD8 cytotoxic T-lymphocytes (CTLs) capable of causing autoimmune diabetes. In this report, we have examined several mucosal routes for their ability to induce CTLs and autoimmune diabetes, with the aim of identifying approaches that would maximize tolerance and minimize CTL generation. In normal C57BL/6 mice, ovalbumin (OVA) delivered by either the oral or nasal routes or by aerosol inhalation was able to prime CTL immunity in both high- and low-dose regimens. To address the relevance of these CTLs to autoimmune disease, OVA was given to mice that transgenically expressed this antigen in their pancreatic beta-cells. Irrespective of antigen dose or the route of delivery, mucosal OVA triggered diabetes, particularly after intranasal administration. These findings suggest that CTL immunity is likely to be a consequence of mucosal antigen delivery, regardless of the regimen, and should be considered in the clinical application of mucosal tolerance to autoimmune disease prevention.

Autoimmune dilated cardiomyopathy in PD-1 receptor-deficient mice.

Dilated cardiomyopathy is a severe pathology of the heart with poorly understood etiology. Disruption of the gene encoding the negative immunoregulatory receptor PD-1 in BALB/c mice, but not in BALB/c RAG-2-/- mice, caused dilated cardiomyopathy with severely impaired contraction and sudden death by congestive heart failure. Affected hearts showed diffuse deposition of immunoglobulin G (IgG) on the surface of cardiomyocytes. All of the affected PD-1-/- mice exhibited high-titer circulating IgG autoantibodies reactive to a 33-kilodalton protein expressed specifically on the surface of cardiomyocytes. These results indicate that PD-1 may be an important factor contributing to the prevention of autoimmune diseases.

Prevention of Autoimmune Type 1 Diabetes via Mucosal Tolerance: Is Mucosal Autoantigen Administration As Safe and Effective As It Should?

Mucosal immune response to an antigen leads to a state of attenuated systemic response to the same antigen, known as mucosal or oral tolerance. Thus, autoantigen administration via mucosal routes could be useful in the prevention of autoimmune diseases. Although in various models of autoimmune disease it is often effective, in some cases it is ineffective and in other cases even harmful. In these cases it is likely that, concomitantly with tolerance, a productive immune response is induced that exacerbates autoimmunity. Recent evidence suggests that induction of cytotoxic T lymphocytes capable of destroying pancreatic beta cells may be an unavoidable consequence of mucosal administration of pancreatic beta-cell associated autoantigen. To improve the safety and efficacy of mucosal tolerance induction in the prevention of type 1 diabetes, further means to control the induction of cytotoxic T lymphocytes and other potentially tissue-destructive immune effectors may be required.

Successful prevention of autoimmune disease by transplantation of adequate number of fully allogeneic hematopoietic stem cells.

We have previously shown successful engraftment of allogeneic hematopoietic stem cells (HSCs) when transplanted across the major histocompatibility antigen barriers if transplanted along with a preparation of facilitator cells (osteoblasts). We have investigated whether or not fully allogeneic HSCs from healthy mouse donors prevent the development of autoimmunities in the autoimmune-prone W/B F1 mice. W/B F1 is a strain of mice that spontaneously develop autoimmunities, a coronary vascular disease, thrombocytopenia, and systemic lupus-like syndrome. The 6- to 8-week-old (before the onset of the disease) W/B F1 mice have been transplanted with either a preparation of HSCs alone, or along with facilitator cells from MHC-incompatible autoimmune-resistant BALB/c mice, then followed to determine longterm survival and whether or not they developed signs of the autoimmune disease. The number of the transplanted HSCs acts as the determining factor in achieving successful and durable engraftment. Survival of the W/B F1 mice significantly improved by transplantation of increasing numbers of HSCs, either alone or along with facilitator cells. When W/B F1 mice were transplanted with 2-5 million HSCs, more than 1-year survival was 100%, all the transplanted mice were fully engrafted with allogeneic HSCs, and were free of signs of the autoimmune disease. Histological sections of the hearts, lungs, and kidneys of the transplanted mice showed absence of the autoimmune-associated pathology. We thus report herein the successful prevention of autoimmune disease by transplantation of a sufficiently large number of purified fully allogeneic HSCs in W/B F1 mice.

Nonsteroidal anti-estrogens inhibit the functional differentiation of human monocyte-derived dendritic cells

Dendritic cells (DC) are professional antigen-presenting cells with a unique capacity to initiate and regulate immune responses. Immature CD1a(+) DC can be cultured from CD14(+) monocytes in the presence of interleukin (IL)-4 and granulocyte macrophage colony-stimulating factor in vitro. Results of this study show that the nonsteroidal anti-estrogens toremifene and tamoxifen inhibit this differentiation. In the presence of anti-estrogens the cells lose CD14 expression, but remain CD1a(-) and clearly have less dendritic processes than immature DC. Functionally, anti-estrogen-treated cells are inferior to immature DC in inducing proliferation of allogeneic T cells and in producing IL-12 p70 protein after CD40 ligation. The expression of the costimulatory molecules CD80 and CD86 is differentially regulated by anti-estrogens during DC differentiation. Furthermore, anti-estrogens are also able to inhibit the terminal maturation of DC. By inhibiting the functional differentiation of DC, anti-estrogens may have a role in the treatment and prevention of autoimmune diseases. (Blood. 2000;95:2875-2882)