Autologous stem cell transplantation in children with severe progressive systemic or polyarticular juvenile idiopathic arthritis: Long-term followup of a prospective clinical trial

Advances in the pathogenesis and treatment of systemic juvenile idiopathic arthritis

Systemic juvenile idiopathic arthritis (s-JIA) is clinically distinct from other types of JIA. It is typified by extraarticular features such as quotidian fevers, rash, splenomegaly, lymphadenopathy, laboratory abnormalities (including leukocytosis, thrombocytosis, anemia, hyperferritinemia, and elevated inflammatory markers), and a close association with the macrophage activation syndrome. Recent investigations have highlighted dysregulation of the innate immune system as the critical pathogenic driver of s-JIA. Key innate immune mediators of s-JIA are the macrophage-derived cytokines interleukin-1 (IL-1) and IL-6. Increased understanding of the roles of IL-1 and IL-6 in the pathogenesis of s-JIA has led to major changes in therapeutic options. Until recently, the most commonly used medications included corticosteroids, methotrexate, and tumor necrosis factor (TNF) inhibitors, which are incompletely effective in most cases. Newer biologic agents targeting IL-1 and IL-6 have proven very effective in treating s-JIA and in minimizing corticosteroid exposure. Here we review recent advances in the understanding of the pathogenesis of s-JIA and the recent clinical trials that have revolutionized the care of children with s-JIA.

Could mesenchymal stromal cells have a role in childhood autoimmune diseases?

Mesenchymal stromal cells (MSCs) comprise a promising source for cellular therapy due to their ability to be readily isolated from various tissues and expand ex vivo. A unique property of these cells is the modulation of immune responses, making them attractive candidates for the treatment of autoimmune diseases. Recently, several clinical trials, mainly in adults, suggest the use of MSCs for therapy of refractory autoimmune diseases. There are a very limited number of reports in the literature addressing the cellular therapy options for pediatric patients with autoimmune diseases refractory to standard therapy. This review discusses the possible mechanisms underlying the immunosuppressive effects of MSCs on almost all cell types, and also the recent advances in cellular therapy of autoimmune diseases using MSCs as modulators of immune response, especially in children.

An update on stem cell transplantation in autoimmune rheumatologic disorders

Stem cell transplant (SCT) has long been the standard of care for several hematologic, immunodeficient, and oncologic disorders. Recently, SCT has become an increasingly utilized therapy for refractory autoimmune rheumatologic disorders (ARDs). The efficacy of SCT in ARDs has been attributed to resetting an aberrant immune system either through direct immune replacement with hematopoietic stem cells or through immunomodulation with mesenchymal stem cells. Among ARDs, refractory systemic sclerosis (SSc) and systemic lupus erythematosus (SLE) are the most common indications for SCT. SCT has also been used in refractory rheumatoid arthritis, inflammatory myopathies, antiphospholipid syndrome, granulomatosis with polyangiitis, and pediatric ARDs. Complete responses have been reported in approximately 30 % of patients in all disease categories. Transplant-related mortality, however, remains a concern. Future large multi-center prospective randomized clinical trials will help to better define the specific role of SCT in the treatment of patients with ARDs.

Hematopoietic stem cell transplantation for curing children with severe autoimmune diseases: is this a valid option?

The cure of children with severe AD, especially patients with severe, progressive, and therapy-resistant autoimmunity, represents a challenge for current medical practice. The idea of HSCT as a promising therapeutic opportunity was borne accidentally from finding patients who, after undergoing HSCT for a hematological indication, were cured of a concomitant AD. Thus, over the last two decades, HSCT has been extensively investigated, and it has become an appealing therapy for rheumatological (juvenile rheumatoid arthritis, systemic lupus erythematosus, systemic sclerosis) and hematological diseases (immune cytopenias). Recently, interesting results have been also described in type 1 diabetes mellitus and Crohn's disease. Although the use of HSCT has been steadily rising in the last few years, many questions are still open, especially after the discoveries of many new biological agents. Given the low incidence of ADs in children, most of the data about the use of the HSCT for these diseases are taken from a mixed cohort of adults and children. The aim of this review is to summarize the published studies and to try to answer the question as to whether this procedure can be considered a promising approach.

Hematologic, immunologic reconstitution, and outcome of 342 autologous peripheral blood stem cell transplantations after cryopreservation in a -80°C mechanical freezer and preserved less than 6 months

BACKGROUND

Controlled-rate freezing and storage in nitrogen is the standard technique for cryopreservation of peripheral hematopoietic progenitor cells (PHPCs) but presents high cost and dimethyl sulfoxide (DMSO) toxicity. Cryopreservation at -80°C, by uncontrolled rate freezing with only 3.5% DMSO, preserves the functional capacities of PHPCs, produces successful engraftment, and reduces toxicity during infusion.

STUDY DESIGN AND METHODS

Long-term hematopoietic and immunologic reconstitution for 342 autografts (311 adults, 31 children) after PHPCs were cryopreserved at -80°C was studied at 3, 6, and 12 months. The median (range) storage time of PHPCs cryopreserved was 1.7 (0.1-5.99) months.

RESULTS

Hemoglobin (Hb), white blood cells, and platelets (PLTs) reach normal values to trilineage at 12 months for 39% patients. Multivariate analysis shows a significant impact on CD34+ infused and on conditioning regimen for PLTs. Hb was influenced by growth factor administration at 3 months. Long-term recovery is also highly dependent on blood counts (Hb, PLT, and neutrophil) at start of high-dose chemotherapy. Only 43% of patients had reached normal lymphocyte values at 12 months after transplant, and a profound CD4+ T-lymphocyte deficit remained, as others reported.

CONCLUSION

Transplantation with PHPCs cryopreserved at -80°C for no more than 6 months is satisfactory for long-term hematopoietic and immunologic reconstitution, even if a profound CD4+ T lymphocyte deficit persists at 1 year. This easier and cheaper cryopreservation method also leads to successful engraftment.

Haematopoietic SCT in severe autoimmune diseases: updated guidelines of the European Group for Blood and Marrow Transplantation

In 1997, the first consensus guidelines for haematopoietic SCT (HSCT) in autoimmune diseases (ADs) were published, while an international coordinated clinical programme was launched. These guidelines provided broad principles for the field over the following decade and were accompanied by comprehensive data collection in the European Group for Blood and Marrow Transplantation (EBMT) AD Registry. Subsequently, retrospective analyses and prospective phase I/II studies generated evidence to support the feasibility, safety and efficacy of HSCT in several types of severe, treatment-resistant ADs, which became the basis for larger-scale phase II and III studies. In parallel, there has also been an era of immense progress in biological therapy in ADs. The aim of this document is to provide revised and updated guidelines for both the current application and future development of HSCT in ADs in relation to the benefits, risks and health economic considerations of other modern treatments. Patient safety considerations are central to guidance on patient selection and HSCT procedural aspects within appropriately experienced and Joint Accreditation Committee of International Society for Cellular Therapy and EBMT accredited centres. A need for prospective interventional and non-interventional studies, where feasible, along with systematic data reporting, in accordance with EBMT policies and procedures, is emphasized.

Application of autologous stem cell transplantation in various adult and pediatric rheumatic diseases

In the past 15 years, more than 1,500 patients worldwide have received a hematopoietic stem cell transplant, mostly autologous, as treatment for a severe autoimmune disease (AD). A recent retrospective analysis of 900 patients showed that the majority had multiple sclerosis, systemic sclerosis, systemic lupus erythematosus (SLE), rheumatoid arthritis (RA), and juvenile idiopathic arthritis (JIA; n = 65) and idiopathic cytopenic purpura. An overall 85% 5-year survival and 43% progression-free survival was seen, with 100-day transplant-related mortality (TRM) ranging between 1% (RA) and 11% (SLE and JIA). Around 30% of patients in all disease subgroups had a complete response, despite full immune reconstitution. In many patients, morphological improvement was documented beyond any predicted known effects of intense immunosuppression alone. It is hoped that the results of three ongoing large prospective, randomized, controlled trials will allow modification of the protocols to reduce the high TRM, which relates to regimen intensity, age of patient, and comorbidity. Multipotent mesenchymal stromal cells (MSCs), including autologous MSCs, have recently been tested in various ADs, exploiting their immune-modulating properties and apparent low acute toxicity. Despite encouraging small phase I/II studies, no positive data from randomized, prospective studies are as yet available in the peer-reviewed literature.

Complications of autologous hematopoietic stem cell transplantation for patients with autoimmune diseases

Autologous hematopoietic stem cell transplantation (HSCT) has been used to treat severe and refractory autoimmune diseases (ADs) in children and adults for more than 15 years. The aim of this treatment is to restore tolerance through an intense lymphodepleting conditioning, and many patients have achieved lasting remissions. However, HSCT is associated with significant morbidity and mortality and is therefore not yet standard of care. Pre-existing reduced organ function of patients with ADs may increase the organ toxicity of conditioning. In the early post-HSCT phase, bacterial or fungal infections occur and therapy-associated lymphopenia sets patients at risk for reactivation of endogenous viruses and other opportunistic infections. During re-emerging of lymphopoiesis after HSCT, de novo autoimmunity may develop through loss of central or peripheral control mechanisms. Late effects of autologous HSCT (e.g., on the endocrine system) and a potentially increased frequency of secondary malignancies are of concern. The steadily increasing knowledge about specific complications occurring in patients with ADs after HSCT has led to the adaption of treatment protocols and has already reduced toxicity. Further prospective long-term follow-up studies are needed to identify patients at risk for developing serious complications after HSCT.

Macrophage activation syndrome as part of systemic juvenile idiopathic arthritis: diagnosis, genetics, pathophysiology and treatment

Macrophage activation syndrome (MAS) is a severe, frequently fatal complication of systemic juvenile idiopathic arthritis (sJIA) with features of hemophagocytosis leading to coagulopathy, pancytopenia, and liver and central nervous system dysfunction. MAS is overt in 10% of children with sJIA but occurs subclinically in another 30-40%. It is difficult to distinguish sJIA disease flare from MAS. Development of criteria for establishing MAS as part of sJIA are under way and will hopefully prove sensitive and specific. Mutations in cytolytic pathway genes are increasingly being recognized in children who develop MAS as part of sJIA. Identification of these mutations may someday assist in MAS diagnosis. Defects in cytolytic genes have provided murine models of MAS to study pathophysiology and treatment. Recently, the first mouse model of MAS not requiring infection but rather dependent on repeated stimulation through Toll-like receptors was reported. This provides a model of MAS that may more accurately reflect MAS pathology in the setting of autoinflammation or autoimmunity. This model confirms the importance of a balance between pro- and anti-inflammatory cytokines. There has been remarkable progress in the use of anti-pro-inflammatory cytokine therapy, particularly against interleukin-1, in the treatment of secondary forms of MAS, such as in sJIA.

Autologous hematopoietic cell transplantation following high-dose immunosuppressive therapy for advanced multiple sclerosis: long-term results

The purpose of the study was to determine the long-term safety and effectiveness of high-dose immunosuppressive therapy (HDIT) followed by autologous hematopoietic cell transplantation (AHCT) in advanced multiple sclerosis (MS). Total body irradiation, cyclophosphamide, and antithymocyte globulin were followed by transplantation of autologous, CD34-selected peripheral blood stem cells (PBSC). Neurological examinations, brain MRIs and cerebrospinal fluid (CSF) for oligoclonal bands (OCB) were serially evaluated. Patients (n=26, mean EDSS=7.0, 17 secondary progressive, 8 primary progressive, 1 relapsing/remitting) were followed for a median of 48 months after HDIT followed by AHCT. The 72-month probability of worsening ≥ 1.0 EDSS point was 0.52 (95% CI, 0.30 to 0.75). Five patients had an EDSS at baseline of ≤ 6.0; four of these had not failed treatment at last study visit. OCB in CSF persisted with minor changes in the banding pattern. Four new or enhancing lesions were seen on MRI, all within 13 months of treatment. In this population with high baseline EDSS, a significant proportion of patients with advanced MS remained stable as long as 7 years after transplant. Non-inflammatory events may have contributed to neurological worsening after treatment. HDIT/AHCT may be more effective in patients with less advanced relapsing/remitting MS.

Juvenile idiopathic arthritis: new insights into classification, measures of outcome, and pharmacotherapy

Significant advances have taken place in recent years in our understanding of the aetiopathogenesis, management, and clinical outcome of juvenile idiopathic arthritis (JIA). Fundamental to this advancement has been international collaborative efforts of the clinical scientific community and all those involved in the multidisciplinary care of children and young people with JIA. A key factor has been facing the challenge of developing a robust classification system for JIA, a clinically very heterogeneous group of conditions. JIA illustrates the necessity of disease classification to enable scientific progress but also the iterative and evolving process this entails. What is emerging is the imperative to improve our understanding of the biologic and genetic basis of JIA to underpin classification systems. Growing emphasis is centered on improved holistic care and outcome of children and young people with JIA. The expectation of patients, their families, and clinicians is the goal of inactive disease, remission off treatment, and the health and psychosocial well-being of young people emerging into adulthood. Validated tools that reflect these challenges are being developed, including those measuring disease improvement, flare, remission and minimal disease activity, health-related quality of life, and composite scores of activity and damage. Clinical research networks have driven success in developing an evidence-base for the treatment of JIA. Randomized comparative trials have demonstrated the benefit of early use of intra-articular corticosteroid injections, and the importance of methotrexate as the first-line, disease-modifying antirheumatic drug in JIA. The introduction of biologic therapies has opened a major new epoch in the medical management of JIA, with recent trials published on etanercept, infliximab, adalimumab, abatacept, tocilizumab, and anakinra. This review focuses on recent advances in JIA, especially developments in its classification, validation of appropriate measures of holistic outcome, and the specific contribution of established and newer pharmacologic agents available for treating children and young people.

Autologous hematopoietic stem cell transplantation in autoimmune diseases

The term 'autoimmune diseases' encompasses a spectrum of diseases whose clinical manifestations and, possibly, biological features vary widely. The results of conventional treatment are considered unsatisfactory in aggressive forms, with subsets of patients having short life expectancies. Relying on wide experimental evidence and more feeble clinical data, some research groups have used autologous hematopoietic stem cell transplantation (HSCT) in the most disabling autoimmune diseases with the aim of resetting the patient's immune system. Immunoablative conditioning regimens are preferred over their myeloablative counterparts, and some form of in vivo and/or ex vivo T-cell depletion is generally adopted. Despite 15 years' experience, published controlled clinical trials are still lacking, with the evidence so far available coming from pilot studies and registry surveys. In multiple sclerosis, clinical improvement, or at least lasting disease stabilization, can be achieved in the majority of the patients; nevertheless, the worst results are observed in patients with progressive disease, where no benefit can be expected from conventional therapy. Concerning rheumatologic diseases, wide experience has been acquired in systemic sclerosis, with long-term improvements in cutaneous disease being frequently reported, although visceral involvement remains unchanged at best. Autografting has proved to be barely effective in rheumatoid arthritis and quite toxic in juvenile idiopathic arthritis, whereas it leads to clinical remission and the reversal of visceral impairment in the majority of patients with systemic lupus erythematosus. A promising indication is Crohn's disease, in which long-term endoscopic remission is frequently observed. Growing experience with autologous HCST in autoimmune diseases has progressively reduced concerns about transplant-related mortality and secondary myelodysplasia/leukemia. Therefore, a sustained complete remission seems to be within the reach of autografting in some autoimmune diseases; in others, the indications, risks and benefits of autografting need to be better defined. Consequently, the search for new drugs should also be encouraged.

Successes and failures of stem cell transplantation in autoimmune diseases

Over the past 15 years, more than 1500 patients have received HSCT, mostly autologous, as treatment for a severe autoimmune disease (AD). More than 1000 of these have been registered in the European Group for Bone Marrow Transplantation (EBMT) and European League Against Rheumatism (EULAR) combined database. A recent retrospective analysis of 900 patients showed that the majority had multiple sclerosis (MS; n = 345) followed by systemic sclerosis (SSc; n = 175), systemic lupus erythematosus (SLE; n = 85), rheumatoid arthritis (RA; n = 89), juvenile idiopathic arthritis (JIA; n = 65), and idiopathic cytopenic purpura (ITP; n = 37). An overall 85% 5-year survival and 43% progression-free survival was seen, with 100-day transplantation-related mortality (TRM) ranging between 1% (RA) and 11% (SLE and JIA). Approximately 30% of patients in all disease subgroups had a complete response, often durable despite full immune reconstitution. In many patients, such as in those with SSc, morphological improvement such as reduction of skin collagen and normalization of microvasculature was documented beyond any predicted known effects of intense immunosuppression alone. The high TRM was in part related to conditioning intensity, comorbidity, and age, but until the results of the 3 prospective randomized trials are known, an evidence-based modification of the conditioning regimen will not be possible.(1) In recent years, multipotent mesenchymal stromal cells (MSCs) have been tested in various AD, exploiting their immune-modulating properties and apparent low acute toxicity. Despite encouraging small phase 1/2 studies, no positive data from randomized, prospective studies are as yet available in the peer-reviewed literature.

Stem cells in the treatment of inflammatory arthritis

Autologous haematopoietic stem cell transplantation in patients with rheumatoid arthritis (RA) resulted in a positive short-term outcome clinically with low treatment-related toxicity. However, early conditioning regimens were of low immunoablative intensity and most patients relapsed. Mechanistic studies suggest that residual lesional effector cells may have been responsible for the relapses. The introduction of biopharmaceuticals has, for the moment, reduced the need for further experimental studies. Juvenile idiopathic arthritis patients, mostly of the systemic subgroup, have shown nearly 33% durable drug-free remission, but with significant toxicity, including fatal macrophage-activation syndrome early in the programme. Later modifications to the protocol have reduced this toxicity. Mesenchymal stem cells (MSCs), derived from several sources including bone marrow and adipose tissue, are being tested as tissue-regenerative and immunomodulating agents in many autoimmune diseases and animal models of inflammatory arthritis have been positive. MSCs and other stromal cells derived from actively inflamed synovium and peripheral blood of RA patients do not always demonstrate a full range of differentiation potential compared with healthy MSCs, although their immunomodulalatory capacity is unimpaired.

Treating to re-establish tolerance in inflammatory arthritis - lessons from other diseases

Therapeutic tolerance embraces the concept of 'switching off' immunopathology by specifically targeting elements of the immune system. It has been achievable in preclinical models of transplantation and auto-immunity for more than two decades; however, previous attempts to translate to the clinic have been unsuccessful. Nonetheless, an improved understanding of tolerance mechanisms, along with novel therapeutic agents and strategies, are starting to bear fruit in a number of disease areas. True tolerance is achievable in transplantation settings, and long-term remissions can be induced in various auto-immune and atopic conditions. Equivalent outcomes should be achievable in inflammatory arthritis, although this may require an improved understanding of the immune dysregulation that is intrinsic to rheumatoid arthritis (RA), and better definitions of RA autoantigens. Biomarkers of tolerance induction would rapidly advance the field in all therapeutic areas. This article summarises the advances made in other therapeutic areas, and the lessons learned that we can now apply to RA.

Undifferentiated spondyloarthritis following allogeneic stem cell transplantation

BACKGROUND

Stem cell transplant has been utilized in the treatment of malignancies and rheumatic disease. Rheumatic disease may be transferred from the donor with active disease or may be developed in a recipient de novo as a late complication of SCT.

CASE PRESENTATION

We here report the rare case of a 26-year old male patient, who has been diagnosed with undifferentiated spondyloarthropathy after unique circumstance. The patient suffered from intermittent inflammatory back pain and peripheral joint swelling for several years and did not find relief through multiple emergency room visits at different medical facilities. After a thorough history and physical exam, it was noted that our patient had developed signs of axial disease along with dactylitis and overall that he had been insidiously developing an undifferentiated spondyloarthopathy after allogeneic stem cell transplantation.

CONCLUSION

Our observation supports the hypothesis that de novo rheumatic disease can develop after stem cell transplant for a variety of reasons. Thus, larger studies and awareness of this association are needed to delineate the exact underlying mechanism(s).

Current perspectives of autologous stem cell transplantation for severe Juvenile Idiopathic Arthritis

The majority of children with Juvenile Idiopathic Arthritis can nowadays be treated adequately. However despite the use of combinations of antirheumatic drugs, corticosteroids and the newer so called biologicals (blocking the TNF, Interleukin 1 or Interleukin 6 pathways) a proportion of children with arthritis remain resistant also to these therapies and suffer from a very severe, debilitating and potentially fatal disease. For such children autologous stem cell transplantation (ASCT) is successfully performed since 1997. Here we describe the long term outcome of the initial cohort of children with resistant Juvenile Idiopathic arthritis, treated with ASCT. The initial cohort of children was treated with a conditioning regimen containing Cyclophosphamide, anti thymocyte globulins and low dose Total Body irradiation. Overall favourable responses were seen, with a drug free remission rate of 50-55 %. In the more recent years late relapses were noted with lower percentages for drug free long term outcome. Special emphasis is given on 2 cases showing very late relapses, occurring after 7 and 9 years. The observed relapses are often less severe compared to the situation before SCT and can be treated successfully with conventional drugs in the majority of cases. More recently, ASCT was performed in 4 JIA children with a fludarabin containing regimen in stead of low dose TBI. With a 4 to 5 year follow up, these 4 patients are all in drug free full remission. Allogeneic transplant with an HLA matched family donor was reported in 2 JIA cases. Follow up of 1 and 3 year is sofar show clinical disease remission and tapering of medition. In conclusion, given the favourable long term outcome, SCT remains a valuable treatment option for children with drug resistant JIA.

Immunosenescence and juvenile idiopathic arthritis

Aging of the immune system (immunosenescence) is characterized by diminished thymus function, decreased output of recent thymic emigrants, compensatory peripheral proliferation of mature T cells and oligoclonal expansions of specific CD28(-) T cells. Clinical consequences are poor responses to new antigens or vaccinations, increased infection rates with higher morbidity and mortality, and increasing incidence of autoimmune diseases with advancing age. Premature immunosenescence is suggested to play a role in the pathogenesis of adult rheumatoid arthritis and in children with juvenile idiopathic arthritis (JIA). However, so far, there is not enough evidence for supporting one of the two theories: the first, favoring premature immunosenscence in children developing autoimmune conditions as the primary defect causing break-down of self-tolerance; the second, that premature immunosenescence in children with autoimmune disorders is secondary to chronic stimulation and activation of the immune system by inflammatory processes by the autoimmune disease itself. This contradictory view of etiology and pathogenesis of autoimmune diseases in the very young underlines the need for population-based longitudinal studies on immune-risk factors for autoimmune diseases beginning at infancy.

Autologous hematopoietic stem cell transplantation for childhood autoimmune disease

Autologous and allogeneic hematopoietic stem cell transplantation (HSCT) can be used in the management of patients with autoimmune disorders. Experience gained in adults has helped to better define the conditioning regimens required and appropriate selection of patients who are most likely to benefit from autologous HSCT. The field has been shifting toward the use of safer and less intense nonmyeloablative regimens used earlier in the disease course before patients accumulate extensive irreversible organ damage. This article reviews the experience of using autologous HSCT in treating the most common childhood autoimmune and rheumatic diseases, primarily juvenile idiopathic arthritis, systemic lupus erythematosus, and diabetes mellitus.

Regulatory T cells as therapeutic targets in rheumatoid arthritis

Regulatory T cells (TREG) are a subset of CD4+ T cells with a critical role in the prevention of autoimmunity. Whether defects in TREG contribute to the pathogenesis of rheumatoid arthritis (RA) is unclear. However, a variety of approved and experimental drugs for RA may work, in part, by promoting the function or increasing numbers of TREG. Furthermore, animal studies demonstrate that direct injection of TREG ameliorates a wide range of experimental models of inflammatory and autoimmune diseases. Thus, cell-based therapy with TREG has the potential to produce durable disease remission in patients with RA.

Histiocytic disorders: recent insights into pathophysiology and practical guidelines

The Histiocytoses are defined as non-malignant disorders due to abnormal accumulation and behavior of cells of the mononuclear phagocytic system. The best known histiocytoses, Langerhans cell histiocytosis (LCH), and hemophagocytic lymphohistiocytosis (HLH), each with an estimated incidence of 1/50,000 to 1/150,000, are sufficiently "common," complex and costly, to constitute an important problem in medical practice. At the same time, LCH, HLH and an array of other and more rare histiocytoses are sufficiently uncommon that most physicians lack the experience to diagnose, let alone care for patients with these conditions. The pathophysiology of most of the histiocytoses is unknown and, in the case of the widely-disseminated and potentially fatal forms, treatments to date have been variably effective and sometimes highly toxic. MAS has been reported to occur in association with almost any rheumatic disease, it is by far most common in the systemic form of Juvenile Idiopthic Arthritis (SoJIA). It is now recognized that MAS bears a close resemblance to Hemophagocytic Lymphohistiocytosis or HLH, and MAS is recognized as the major fatal complication of soJIA.

Hematopoietic stem cell transplantation for pediatric autoimmune disease: where we stand and where we need to go

In children, autoimmune diseases and their therapies cause significant morbidity, especially in those with severe or refractory disease. The constant development of new immunosuppressants and targeted biological therapies leads to a unique 'moving target' with regard to the gold standard of treatment for these patients. However, incidental findings of cure after hematopoietic stem cell transplant (HSCT) in patients with concomitant benign or malignant hematologic disorders and autoimmune disease raise the question of whether HSCT can be used as upfront therapy for patients with severe autoimmune diseases. Animal data have been helpful in investigating both the efficacy of this modality and the mechanisms underlying cure. The potential for a therapeutic 'graft vs autoimmunity' (GVA) effect with an allogeneic approach highlights the already acknowledged need for clinical trials of allogeneic vs autologous transplant in these diseases where an autologous transplant would be the 'intuitive' albeit potentially erroneous choice. We critically review the data generated in the field thus far, and emphasize the need for an organized, interdisciplinary approach to conduct prospective clinical trials to answer these and other questions and advance the field.

Thymic function in juvenile idiopathic arthritis

OBJECTIVE

Thymic function declines exponentially with age. Impaired thymic function has been associated with autoimmune disease in adults but has never been formally assessed in childhood autoimmunity. Therefore, thymic function in children with the autoimmune disease juvenile idiopathic arthritis (JIA) was determined.

METHODS

Thymic function was measured in 70 children and young adults with JIA (age range 2.1-30.8 (median 10.4)) and 110 healthy age-matched controls using four independent assays. T cell receptor excision circles (WBLogTREC/ml) and the proportion of CD4(+) CD45RA(+)CD31(+) T cells (representing recent thymic emigrants; %RTEs) were quantified and intrathymic proliferation measured by calculating the alphaTREC/SigmabetaTREC ratio. Lastly, regulatory T cells (T(Reg)) of thymic origin (CD4(+)FOXP3(+)) were quantified in peripheral blood to assess the ability of the thymus in JIA to generate this T cell subset.

RESULTS

Thymic function was equivalent by all four parameters in JIA when compared with the control population. Furthermore, there was no consistent effect of JIA subtype on thymic function, although intrathymic proliferation was higher in the small rheumatoid factor (RF)(+) polyarticular group. There were no significant effects of disease-modifying antirheumatic drugs (DMARDs) or oral corticosteroids on thymic function, although those with the worst prognostic ILAR (International League of Associations for Rheumatology) subtypes were also those most likely to be on a DMARD.

CONCLUSIONS

It is demonstrated that children and young adults with JIA, unlike adults with autoimmune diseases, have thymic function that is comparable with that of healthy controls. The varied pathologies represented by the term "JIA" suggest this observation may not be disease specific and raises interesting questions about the aetiology of thymic impairment in adult autoimmunity.

[Current value of stem-cell transplantation in autoimmune diseases]

Transplantations of autologous or allogeneic stem cells from bone marrow or peripheral blood are preformed for the treatment of resistant autoimmune diseases. Data have been systematically collected since 1996. We describe the historical development of this procedure for autoimmune diseases, the possible mechanisms of action, the options for stem cell collection, purging and conditioning (high-dose chemotherapy, combination with monoclonal anti-T- or B-cell antibodies, total body irradiation), as well as the reported outcomes in the literature.

Haematopoietic stem cell transplantation for autoimmune disorders

PURPOSE OF REVIEW

To summarize recent evidence and current trends in the use of haematopoietic stem cell transplantation (HSCT) for autoimmune diseases.

RECENT FINDINGS

Updates of published trials and data from the registries indicate a long-lasting, immunosuppression-free condition in about 50% of the patients who underwent an HSCT for a severe, progressive autoimmune disease. For all diseases, autologous HSCT is largely preferred for safety reasons, whereas allogeneic HSCT is to be considered only for carefully selected cases. Transplant-related mortality (TRM) has decreased in the past 5 years, due to both better selection of patients and the use of less intensive conditioning regimens. The most employed conditioning regimens in Europe are BCNU (carmustine), etoposide, ARA-C (cytosine arabinoside), M (melphalan) (BEAM)/anti-thymocyte globulin in multiple sclerosis and high-dose cyclophosphamide/anti-thymocyte globulin for all other diseases, with a trend for more intense regimens in North America. Multiple sclerosis and systemic sclerosis are currently the most frequent diagnoses. Prospective comparative trials are currently ongoing both in Europe and North America.

SUMMARY

Recent reports confirm the evidence that HSCT is able to induce a high rate of sustained remissions in most severe autoimmune diseases, unresponsive to conventional treatments. Valuable information is expected by the finalization of the ongoing prospective, comparative trials.

Recent developments in anti-rheumatic drugs in pediatrics: treatment of juvenile idiopathic arthritis

Juvenile idiopathic arthritis (JIA) is the most common autoimmune-autoinflammatory disease in childhood and affects approximately 1 in 1,000 children. Despite advances in diagnosis and treatment options, JIA remains a chronic condition for most affected children. Recent evidence suggests that disease control at onset may determine the tempo of subsequent disease course and long-term outcomes, and raises the concept of a therapeutic window of opportunity in patients with JIA. This underscores the importance of early aggressive treatment in patients with JIA. With the advent of novel biologic therapeutics, the repertoire of agents available for treatment of children with JIA has greatly increased. The present article will summarize recent developments in the medical treatment of children with JIA and will offer insights into emerging therapies.

Stem cell transplantation for rheumatic autoimmune diseases

Immunoablative therapy and hematopoietic stem cell transplantation (HSCT) is an intensive treatment modality aimed at 'resetting' the dysregulated immune system of a patient with immunoablative therapy and allow outgrowth of a nonautogressive immune system from reinfused hematopoietic stem cells, either from the patient (autologous HSCT) or a healthy donor (allogeneic HSCT). HSCT has been shown to induce profound alterations of the immune system affecting B and T cells, monocytes, and natural killer and dendritic cells, resulting in elimination of autoantibody-producing plasma cells and in induction of regulatory T cells. Most of the available data have been collected through retrospective cohort analyses of autologous HSCT, case series, and translational studies in patients with refractory autoimmune diseases. Long-term and marked improvements of disease activity have been observed, notably in systemic sclerosis, systemic lupus erythematosus, and juvenile idiopathic arthritis, and treatment-related morbidity and mortality have improved due to better patient selection and modifications of transplant regimens. Treatment-related mortality has decreased to approximately 7%. Prospective, randomised, controlled clinical trials are ongoing or planned in systemic sclerosis, systemic lupus erythematosus, and several nonrheumatological conditions.

Resetting the adaptive immune system after autologous stem cell transplantation: lessons from responses to vaccines

Autologous stem cell transplantation (ASCT) to treat autoimmune diseases (AID) is thought to reset immunological memory directed against autoantigens. This hypothesis can only be studied indirectly because the exact nature of the pathogenetic autoantigens is unknown in most AID. Therefore, 19 children with juvenile idiopathic arthritis (JIA) or systemic lupus erythematodes (SLE) and 10 adults with multiple sclerosis (MS) were vaccinated with the T-cell-dependent neoantigen rabies and the recall antigen tetanus toxoid after, respectively before, bone marrow harvest. Both vaccinations were repeated after ASCT. All except two of the responders mounted a primary antibody response to rabies after revaccination, and 44% of the responders mounted a primary antibody response to tetanus boost after ASCT. These data show that immunological memory to a neoantigen is lost in most patients with AID after immunoablative pretreatment; however, memory to a recall antigen boosted before bone marrow harvest is only lost in part of the patients. Disease progression was arrested in all patients with JIA/SLE except one, but only in a minority of MS patients. Clinical outcome on a per case basis was not associated with the profile of the immune response toward the vaccination antigens after ASCT.