Induction of tolerance to experimental anti-phospholipid syndrome (APS) by syngeneic bone marrow cell transplantation

Contribution of mouse models in our understanding of lupus

Laboratory animal models are beneficial when they recapitulate all or just some of the clinical and immunological manifestations of the disease. Various animals such as cats, rats, dogs, hamsters, guinea pigs, rabbits, horses, minks, pigs, and primates have been described lupus-like phenotype. However, a mouse has remained the preferable animal for scientific investigations as a result of their reduced lifespan, easy reproduction, markedly low costs, public acceptance, ease of genetic management, and the probability to stay under standardized conditions. It is highly challenging to establish a mouse model with all features of lupus because of the difficulty and the heterogeneity of the clinical features in systemic lupus erythematous (SLE). Additionally, due to the multiple differences between the mouse and human immune system, the direct translation usually fails. Each mouse model has specific characteristics and shares many subsets of aspects with the disease observed in humans, which gives researchers a tool to select their particular needs. Over 50 years, many mice models have been developed and used to dissect the pathogenesis of lupus, also to test novel drugs and therapies. In general, mice models that contribute considerably in SLE understanding can be divided into four groups: Spontaneous models, induced models, genetically modified models, along with humanizing mouse models that are the link between the mouse and human immune system. In this updated review, we will present what has been learned from different lupus mice models and how these models have contributed to a better understanding of lupus pathogenesis and treatment.

Haematopoietic stem cell transplantation in autoimmune diseases: From basic science to clinical practice

Based on animal studies and serendipitous clinical cases, haematopoietic stem cell transplantation (HSCT) has been used since 1995 as a specific treatment for patients with severe treatment-resistant autoimmune disease (ADs). Despite other clinical developments for autoimmune diseases, including biological therapies, there has been an ongoing requirement for HSCT in some diseases and several thousand procedures have been registered in databases for a wide variety of diseases, predominantly for treatment with autologous HSCT. Currently, the main indications are multiple sclerosis, systemic sclerosis and Crohn's disease, which are supported by large series and randomised controlled trials (RCTs), whereas retrospective registry analyses support benefit in a range of rarer indications. Research into mechanisms of action has provided insight into how tolerance may be achieved with an intensive one-off treatment. In addition to the profound anti-inflammatory and immunosuppressive effects provided by the cytotoxic regimen, long-term responses in some diseases may be explained by 'resetting' the immune system through thymic reprocessing and generation of increased T-regulatory cell activity. This review aims to summarise the gradual evolution of HSCT in severe autoimmune diseases over the last 20 years, focussing on the recent publication of clinical and scientific studies, as well as evidence-based guidelines and recommendations.

Type 1 and type 2 cytokine-producing CD4+ and CD8+ T cells in primary antiphospholipid syndrome

Antiphospholipid syndrome (APS) is an autoimmune condition characterized by thrombosis and/or recurrent fetal loss as well as the presence of autoantibodies against epitopes present on phospholipid-binding proteins. The role of cellular immunity in the pathogenesis of the syndrome remains unclear. We studied the cellular phenotype and the production of type 1 [interferon (IFN)-gamma, interleukin (IL)-2] and type 2 (IL-4, IL-10) cytokines by CD4+ and CD8+ T-lymphocyte subsets in 13 patients with untreated primary APS (PAPS) and in 32 healthy controls. The production of cytokines was determined in T cells after a 5-h culture with or without mitogenic stimulation using a flow cytometric method of intracellular cytokine staining. In six of the patients these studies were repeated 6 months later. In PAPS patients we found a reduced percentage of circulating CD4+CD45RA+ and an increased percentage and absolute number of CD8+HLA-DR+ cells. A type 1 response was observed in the patients' unstimulated cells, indicated by an increase in IFN-gamma-producing CD8+, IL-2-producing CD4+ T cells, and a decrease in IL-4-producing CD4+ and CD8+ T cells. Similar results were obtained in the patients at follow-up. Taken together, these results suggest a chronic in vivo stimulation of CD4+ and CD8+ T cells in PAPS patients exhibiting a type 1 polarization. Changes of cellular immunity may contribute to the pathogenesis of the clinical manifestations of the syndrome and might be proven to be useful targets for therapeutic interventions in the future.

Preclinical experiments

The clinical use of autologous stem cell transplants for the treatment of refractory severe autoimmune diseases was preceded by convincing proof of its underlying principle in animal models. The various categories of experimental autoimmune disease in laboratory rodents are briefly described here, and the rationale that was used in the selection of suitable experimental autoimmune diseases for translational research is explained. The two models that provided the bulk of the data needed for designing the initial clinical treatment protocols were adjuvant arthritis (AA) and experimental allergic encephalomyelitis (EAE), which were both induced in Buffalo rats. In this strain, AA is manifested as a chronic, progressive, systemic polyarthritis and EAE as a chronic, remitting/relapsing form of encephalomyelitis resembling multiple sclerosis. Both diseases can be cured with autologous stem cell transplantation provided that adequate conditioning is given and that the disease has not yet progressed to the stage of 'scarring'. It is basically the inflammatory stages that respond well to this therapy. The success of treatment depends on how completely the autoantigen-specific activated T-lymphocytes and memory cells are eradicated. Because of a lack of information on the nature of the autoantigens involved in human disease and on the size of those cell populations in the animal models as well as in humans, this aspect of translation is difficult. The experiments have, however, provided important guidelines. High-dose conditioning regimens yield better results than low-dose conditioning, certain conditioning agents perform better than others, and care should be taken not to reintroduce too many T-cells with the autologous graft. The clinical results obtained so far indicate a high predictive power of these two animal models, which are therefore recommended strongly for additional preclinical studies.

Stem cell transplantation in systemic lupus erythematosus

Systemic lupus erythematosus is a heterogeneous, multisystem disease responsive to treatment with corticosteroids and immune suppressives. Many patients fail to achieve treatment-free remissions, and their long-term outcomes remain poor owing to the development of vital organ failure, cumulative drug toxicity and an increased risk of cardiovascular disease and malignancy. Haematopoietic stem cell transplantation (HSCT) offers the potential to improve long-term outcome in those with a poor prognosis. Preliminary phase II and registry studies have usually employed non-myeloablative conditioning with positive CD34 cell selection. They have highlighted the potential efficacy and dangers of HSCT. Patient selection is important but complex, and the influence of HSCT on long-term outcome is unknown. Disease relapse occurs in up to one-third of patients after HSCT, but the consequences of relapse and the role of remission-maintenance strategies are unknown. With the availability of other alternative therapies in refractory disease, there needs to be a clear demonstration of the benefits of HSCT from current randomized trials.

"Black swan in the kidney": renal involvement in the antiphospholipid antibody syndrome

The antiphosphospholipid antibody syndrome (APS) describes a clinical entity with recurrent thrombosis, fetal loss, thrombocytopenia in the presence of lupus anticoagulant and/or antibodies to cardiolipin. These antibodies may be associated with connective tissue diseases such as systemic lupus erythematosus (secondary APS) or be found in isolation (primary APS). Renal syndromes increasingly being reported in association with these antibodies include thrombotic microangiopathy, renal vein thrombosis, renal infarction, renal artery stenosis and/or malignant hypertension, increased allograft vascular thrombosis, and reduced survival of renal allografts. Although much has been understood concerning the biology of these antibodies and the pathogenesis of thrombosis, the optimal therapy remains to be elucidated. This article presents a historical review of the renal involvement in the antiphospholipid syndrome and discusses therapeutic options. Further research is needed.

Induction of tolerance in autoimmune diseases by hematopoietic stem cell transplantation: getting closer to a cure?

Hematopoietic stem cells (HSCs) are the earliest cells of the immune system, giving rise to B and T lymphocytes, monocytes, tissue macrophages, and dendritic cells. In animal models, adoptive transfer of HSCs, depending on circumstances, may cause, prevent, or cure autoimmune diseases. Clinical trials have reported early remission of otherwise refractory autoimmune disorders after either autologous or allogeneic hematopoietic stem cell transplantation (HSCT). By percentage of transplantations performed, autoimmune diseases are the most rapidly expanding indication for stem cell transplantation. Although numerous editorials or commentaries have been previously published, no prior review has focused on the immunology of transplantation tolerance or development of phase 3 autoimmune HSCT trials. Results from current trials suggest that mobilization of HSCs, conditioning regimen, eligibility and exclusion criteria, toxicity, outcome, source of stem cells, and posttransplantation follow-up need to be disease specific. HSCT-induced remission of an autoimmune disease allows for a prospective analysis of events involved in immune tolerance not available in cross-sectional studies.

Induction and treatment of the antiphospholipid syndrome--lessons from animal models

The diagnosis of antiphospholipid syndrome (APS) is based on a combination of clinical and serological criteria. This review summarizes the literature regarding animal models of APS. Animal models of this syndrome help to elucidate pathogenic roles of the characteristic antiphospholipid antibodies in pregnancy morbidity, vascular thrombosis, neurologic disease and atherosclerosis. Furthermore, these models also provide measures to evaluate novel therapies for APS. These include bone-marrow transplantation, intravenous immunoglobulin, anticoagulation, interleukin-3, in addition to other therapies. Experimental induction and treatment of APS largely contributes to our understanding of the disease and to better management of its clinical characteristics.

Linseed oil suppresses the anti-beta-2-glycoprotein-I in experimental antiphospholipid syndrome

The immunomodulatory potential of a diet enriched with n-3 polyunsaturated fatty acids was analysed in naïve mice with experimental antiphospholipid syndrome (APS) induced by active immunization with H-3, a human anti-beta-2-glycoprotein-I (anti-betaGPI) monoclonal antibody (mAb). Fetal loss and other clinical manifestations of APS were prevented in the group of APS mice upon exposure to the enriched n-3 diet compared to the control group. The titers of anti-betaGPI were significantly lower (in O.D. at 405 nm, 1.387+/-0.232 in comparison to non-treated mice 0.637+/-0. 111, P< 0.05). The reduced titer of anti-betaGPI antibodies in the sera of the treated mice was associated with a reduced number of anti-betaGPI forming cells in cultured splenocytes (84+/-14, antibody-forming cells (AFC)/10(5)cells in comparison to 37+/-4 AFC/10(5)cells (P< 0.02).In addition to the suppression of the humoral response in mice with experimental APS fed with linseed oil, we also observed an inhibitory effect on the cellular response. The T-cell response to anti-betaGPI was lower in comparison to mice immunized with H-3 anti-betaGPI mAB, which were kept on a normal diet. These results indicate that polyunsaturated fatty acids may improve clinical and laboratory parameters of APS. The beneficial effects of diets enriched with n-3 should be further examined as a potential mode of therapy for patients with APS.

Treatment of the antiphospholipid antibody syndrome: progress in the last five years?

The gold standard for treatment of the antiphospholipid antibody syndrome (APS) after thrombosis remains high-intensity warfarin, and, in pregnancy, heparin and aspirin. Exciting developments include the potential role of hydroxychloroquine as a prophylactic drug, stem cell transplantation, and B-cell tolerance. Animal models appear to be a fruitful "proving ground" of new therapies. The introduction of revised classification criteria for APS should aid in appropriate characterization of, and selection of, patients for clinical trials.

Anti-idiotype immunomodulation of experimental anti-phospholipid syndrome via effect on Th1/Th2 expression

Mice with experimental anti-phospholipid syndrome (APS), induced by active immunization with a human anti-cardiolipin MoAb (H-3), were treated with mouse anti-idiotypic MoAb (anti-H3, named S2.9) and with an irrelevant anti-idiotype. The immunized mice produced high titres of mouse anti-cardiolipin antibodies along with clinical manifestations of experimental APS: prolonged activated partial thromboplastin time (aPTT), thrombocytopenia and high rate of fetal loss. Treatment with the specific anti-Id (S2.9) as a whole molecule or F(ab)2 fraction, resulted in a decrease in serum levels of the anti-cardiolipin antibodies, rise in platelet count, shortened aPTT and reduced rate of fetal loss. The anti-Id effect was associated with a rise in the number of IL-2 and interferon-gamma (IFN-gamma)-secreting cells (Th1) and reduction in IL-4- and IL-6-secreting cells (Th2). The beneficial effect of the anti-Id treatment in mice with experimental APS induced by active immunization with an idiotype further supports the idiotypic aetiology of experimental APS and points to the role of Th1 cytokines in suppression of its manifestations.

Immunomodulation of experimental antiphospholipid syndrome

The various therapeutic modalities which are found to be beneficial in experimental antiphospholipid syndrome include: bone marrow transplantation, anti-CD4 monoclonal antibodies, bromocriptine, intravenous immunoglobulins and anti-idiotypes, interleukin-3, and various anti-coagulant and anti-aggregate agents. The advantage of animal models is the ability to evaluate experimental treatments that cannot be tested directly on patients. In this paper, we review the effect of these agents on animal models of antiphospholipid syndrome, their mechanisms of action, and their clinical implications.

Ciprofloxacin immunomodulation of experimental antiphospholipid syndrome associated with elevation of interleukin-3 and granulocyte-macrophage colony-stimulating factor expression

OBJECTIVE

To evaluate the immunomodulatory potential of ciprofloxacin in mice with experimental antiphospholipid syndrome (APS).

METHODS

Ciprofloxacin or ceftazidime (control antibiotic) was given to mice with experimentally induced APS. The titers of autoantibodies, levels of cytokines, and number of cytokine-producing cells were determined by enzyme-linked immunosorbent assay. Myeloid progenitor cells were determined by granulocyte-macrophage colony-forming unit, and interleukin-3 (IL-3) messenger RNA (mRNA) was tested by Northern analysis.

RESULTS

A decrease in the incidence of pregnancy loss and an improvement in the clinical manifestations of APS were noted in the mice treated with ciprofloxacin, compared with the mice given ceftazidime. The effect of ciprofloxacin was found to be associated with increased serum levels of IL-3 and with increased IL-3 mRNA transcription in the splenocytes. Expression of granulocyte-macrophage colony-stimulating factor (GM-CSF) was documented by elevated titers in the sera and elevated numbers of colony-forming cells in the bone marrow.

CONCLUSION

Ciprofloxacin prevents the manifestations of experimental APS. This effect may be associated with increased IL-3 levels and GM-CSF expression.

Animal models for antiphospholipid syndrome in pregnancy

Experimental models for antipospholipid syndrome (APS) have been established recently in lupus-prone mice and induced in naive mice. The induction of APS is performed by passive infusion or active immunization of antiphospholipid antibodies (aPL) or the cofactor beta 2GP-1. High levels of diverse aPL develop in the animals in conjunction with clinical manifestations similar to the human disease, entailing low fecundity rate, fetal resorptions, thrombocytopenia, prolonged activated partial thromboplastin time, and neurological and behavioral impairments. The pathogenicity of aPL was confirmed in an in vivo thrombosis model. Immunomodulation of APS manifestations and treatment regimens in the experimental models are discussed.

Immunomodulation of experimental APS: lessons from murine models

During the last few years several murine models for APS have been described. These include spontaneous occurring disease, or APS induced by immunization with pathogenic autoantibodies. Employing those models, several treatment modalities, in different stages of the disease, were studied. Treatments which showed promising potential for application in patients with APS include immunomodulation with specific anti-idiotypic or anti-CD4 antibodies, treatment with IL-3, high-dose intravenous immunoglobulins, ciprofloxacin or bromocriptine, as well as antithrombotic and anticoagulant treatments using aspirin and/or low-molecular-weight heparin. Bone-marrow transplantation was also found to improve clinical and serological manifestations of the disease. These studies might promote the handling of controlled clinical trials assessing their efficacy in APS patients.