Outcome of intensive immunosuppression and autologous stem cell transplantation in patients with severe rheumatoid arthritis is associated with the composition of synovial T cell infiltration

Efficacy and safety of Duhuo-Jisheng decoction in rheumatoid arthritis: A systematic review and meta-analysis of 42 randomized controlled trials

BACKGROUND

Duhuo-Jisheng decoction (DJD) is a Chinese herb formula. Previous studies have reported that the clinical symptoms and laboratory indicators of rheumatoid arthritis (RA) patients could be improved by DJD. However, the existing evidence was not robust enough and controversial.

METHODS

Randomized controlled trials of DJD for RA were retrieved from Chinese and English databases from their inception to April 16, 2023. Meta-analysis was performed by Stata 17 software. We used subgroup analysis, meta-regression, and sensitivity analysis to identify potential sources of heterogeneity. The subgroup analysis and meta-regression were conducted from 6 aspects, including age, course of disease, course of treatment, interventions used in the experimental or control group, and random sequence generation. Galbraith plot was used to find studies with possible heterogeneity. Publication bias was assessed by Egger's test and funnel plots when the number of relevant studies was greater than or equal to 10.

RESULTS

Forty-two studies were included, involving 3635 patients and 19 outcome indicators. Meta-analysis showed that, compared with the routine disease-modifying antirheumatic drugs (rDMARDs), DJD could better improve the level of laboratory indicators, main symptoms and signs, and questionnaire scores of RA patients. The laboratory indicators included rheumatoid factor, T lymphocyte subpopulation (including CD4+, CD8+, and CD4+/CD8+), and inflammatory biomarkers (including erythrocyte sedimentation rate, C-reactive protein, tumor necrosis factor-α, interleukin 6, interleukin 1β, and interleukin 1). The main symptoms and signs included the duration of morning stiffness, the number of joint tenderness, the number of swollen joints, and the grip strength of both hands. The questionnaire included visual analogue scale, health assessment questionnaire, and disease activity score in 28 joints. In addition, the adverse events of DJD treatment were significantly lower than those of rDMARDs. However, the results of a few subgroup analyses differed from the overall results. Furthermore, the publication bias assessment showed that, out of 11 evaluated results, 4 had publication bias.

CONCLUSION

DJD could be a satisfactory complementary and alternative therapy for RA. However, due to a small number of subgroup analysis results being different from the overall results, it should be verified by further studies.

Cell-based therapies for the treatment of rheumatoid arthritis

Autoimmune diseases, including rheumatoid arthritis that is the most prevalent rheumatic autoimmune disorder, affect autologous connective tissues caused by the breakdown of the self-tolerance mechanisms of the immune system. During the last two decades, cell-based therapy, including stem cells and none-stem cells has been increasingly considered as a therapeutic option in various diseases. This is partly due to the unique properties of stem cells that divide and differentiate from the specialized cells in the damaged tissue. Moreover, stem cells and none-stem cells, impose immunomodulatory properties affecting the diseases caused by immunological abnormalities such as rheumatic autoimmune disorders. In the present review, the efficacy of cell-based therapy with four main types of stem cells, including mesenchymal stem cells, hematopoietic stem cells, embryonic stem cells, and human amniotic membrane cells, as well as none-stem cells, including regulatory T cells, chimeric antigen receptor T cells, and tolerogenic dendritic cells will be evaluated. Moreover, other related issues, including safety, changes in immunological parameters, suitable choice of stem cell and none-stem cell origin, conditioning regimen, limitations, and complications will be discussed.

The immunology of rheumatoid arthritis

The immunopathogenesis of rheumatoid arthritis (RA) spans decades, beginning with the production of autoantibodies against post-translationally modified proteins (checkpoint 1). After years of asymptomatic autoimmunity and progressive immune system remodeling, tissue tolerance erodes and joint inflammation ensues as tissue-invasive effector T cells emerge and protective joint-resident macrophages fail (checkpoint 2). The transition of synovial stromal cells into autoaggressive effector cells converts synovitis from acute to chronic destructive (checkpoint 3). The loss of T cell tolerance derives from defective DNA repair, causing abnormal cell cycle dynamics, telomere fragility and instability of mitochondrial DNA. Mitochondrial and lysosomal anomalies culminate in the generation of short-lived tissue-invasive effector T cells. This differentiation defect builds on a metabolic platform that shunts glucose away from energy generation toward the cell building and motility programs. The next frontier in RA is the development of curative interventions, for example, reprogramming T cell defects during the period of asymptomatic autoimmunity.

Association of a Type 2-Polarized T Cell Phenotype With Methotrexate Nonresponse in Patients With Rheumatoid Arthritis

OBJECTIVE

Rheumatoid arthritis (RA) is a chronic inflammatory disease mediated through complex immunologic pathways. Among RA patients receiving low-dose methotrexate (MTX) monotherapy, approximately one-half exhibit a meaningful clinical response within the first 6 months of starting treatment. Whether baseline immune phenotypes differ between subsequent MTX responders and nonresponders is unknown. This study utilized comprehensive T cell immunophenotyping to identify specific immunologic pathways associated with MTX-nonresponsive joint inflammation in patients with RA.

METHODS

In total, 32 patients with recent-onset RA were treated with MTX therapy. After 6 months, 15 patients were categorized as responders and 17 as nonresponders. Comprehensive blood T cell immunophenotyping, using multiparameter immunofluorescence flow cytometry analyses, was performed at baseline and following 6 months of treatment.

RESULTS

Baseline measures of disease activity (Disease Activity Score in 28 joints [DAS28], C-reactive protein level, and erythrocyte sedimentation rate) did not differ between MTX responders and nonresponders following MTX treatment. Frequencies of CD4+ and CD8+ T cells were skewed to favor higher CD4:CD8 T cell ratios in MTX responders compared to nonresponders (P < 0.05). The proportion of inducible costimulator-expressing Treg cells was significantly greater among MTX nonresponders. Interleukin-13 (IL-13)-producing, but not interferon-γ- or IL-17-producing, CD4+ effector memory T (Tem) cells were significantly more frequent in MTX nonresponders (P < 0.05). The ratio of IL-13+:IL-17+ Tem cells among CD4+ Tem cells was 1.9-fold higher in MTX nonresponders compared to responders (P < 0.05). Both the CD4:CD8 T cell ratio and the frequency of IL-13+CD4+ Tem cells correlated with changes in the DAS28 score following MTX treatment, whereas T cell expression of immune checkpoint inhibitor markers (CTLA-4, programmed death 1, and T cell immunoglobulin and mucin domain-containing protein 3) did not differ between MTX responders and nonresponders.

CONCLUSION

We observed a bias toward type 2-polarized T cell inflammatory responses in the peripheral blood of MTX-nonresponsive RA patients. Targeting the IL-13+CD4+ T cell pathway could be a new therapeutic strategy in RA patients whose disease remains resistant to MTX.

Hematopoietic stem cell therapy for autoimmune diseases - Clinical experience and mechanisms

With accumulating evidence and improved outcomes along with recognition that modern biological therapies are not universally effective, require chronic administration and have high acquisition costs, hematopoietic stem cell transplantation (HSCT) has become an emerging direction for cell therapy in autoimmune diseases (ADs). The goal of this therapy is to induce medication-free remissions by resetting the immune system into a naïve and self-tolerant state through eradication of the autoreactive immunologic memory and profound re-configuration of the immune system induced by the transplant procedure. Safety of HSCT has generally improved by implementing internal quality management and external accreditation. Inter-disciplinary guidelines for patient selection, transplant technique and supportive care along with greater center experience should optimize safe and appropriate delivery of HSCT in specific ADs. In this review, we discuss the current role and future perspectives of HSCT in AD, focusing on recent published clinical and scientific studies and recommendations in the field.

Hematopoietic stem cell transplantation for non-malignant gastrointestinal diseases

Both, autologous and allogeneic hematopoietic stem cell transplantation (HSCT) can be used to cure or ameliorate a variety of malignant and non-malignant diseases. The rationale behind this strategy is based on the concept of immunoablation using high-dose chemotherapy, with subsequent regeneration of naive T-lymphocytes derived from reinfused hematopoietic progenitor cells. In addition, the use of HSCT allows for the administration of high-dose chemotherapy (whether or not combined with immunomodulating agents such as antithymocyte globulin) resulting in a prompt remission in therapy-refractory patients. This review gives an update of the major areas of successful uses of HSCT in non-malignant gastrointestinal disorders. A Medline search has been conducted and all relevant published data were analyzed. HSCT has been proved successful in treating refractory Crohn’s disease (CD). Patients with refractory celiac disease type II and a high risk of developing enteropathy associated T-cell lymphoma have shown promising improvement. Data concerning HSCT and mesenchymal SCT in end-stage chronic liver diseases are encouraging. In refractory autoimmune gastrointestinal diseases high-dose chemotherapy followed by HSCT seems feasible and safe and might result in long-term improvement of disease activity. Mesenchymal SCT for a selected group of CD is promising and may represent a significant therapeutic alternative in treating fistulas in CD.

Brief report: Autologous stem cell transplantation restores immune tolerance in experimental arthritis by renewal and modulation of the Teff cell compartment

OBJECTIVE

Autologous stem cell transplantation (ASCT) induces long-term drug-free disease remission in patients with juvenile idiopathic arthritis. This study was undertaken to further unravel the immunologic mechanisms underlying ASCT by using a mouse model of proteoglycan-induced arthritis (PGIA).

METHODS

For initiation of PGIA, BALB/c mice received 2 intraperitoneal injections of human PG in a synthetic adjuvant on days 0 and 21. Five weeks after the first immunization, the mice were exposed to total body irradiation (7.5 Gy) and received (un)manipulated bone marrow (BM) grafts from mice with PGIA. Clinical scores, T cell reconstitution, (antigen-specific) T cell cytokine production, and intracellular cytokine expression were determined following autologous BM transplantation (ABMT).

RESULTS

ABMT resulted in amelioration and stabilization of arthritis scores. BM grafts containing T cells and T cell-depleted grafts provided the same clinical benefit, with similar reductions in PG-induced T cell proliferation and the number of PG-specific autoantibodies. In vivo reexposure to PG did not exacerbate disease. Following ABMT, basal levels of disease-associated proinflammatory cytokines (interferon-γ [IFNγ], interleukin-17 [IL-17], and tumor necrosis factor α [TNFα]) were reduced. In addition, restimulation of T cells with PG induced a strong reduction in disease-associated proinflammatory cytokine production. Finally, although the remaining host T cells displayed a proinflammatory phenotype following ABMT, IFNγ, IL-17, and TNFα production by the newly reconstituted donor-derived T cells was significantly lower.

CONCLUSION

Taken together, our data suggest that ABMT restores immune tolerance by renewal and modulation of the Teff cell compartment, leading to a strong reduction in proinflammatory (self antigen-specific) T cell cytokine production.

An immunological biomarker to predict MTX response in early RA

OBJECTIVES

The therapeutic goal for patients with rheumatoid arthritis (RA) is clinical remission. This is best achieved by early diagnosis and appropriate therapeutic intervention. RA is associated with dysregulation of T-cell subsets (naïve, regulatory (Treg) and inflammation-related cells (IRC)) early in the disease. Our aim was to test the hypothesis that T-cell subset quantification can predict the achievement of clinical remission with early treatment in RA.

METHODS

T-cell subsets were quantified in 108 drug-naïve, early RA patients commencing methotrexate (MTX) or MTX+antitumor necrosis factor (anti-TNF) and in 105 healthy controls (HC). The primary outcome assessed was remission (DAS28<2.6). A pilot study used frozen cells (38 patients and 35 HCs, see online supplementary material) and was validated with fresh blood (70 patients and 70 HCs).

RESULTS

Immune dysregulation in early RA was confirmed with an association between age and reduced naïve cells compared with HCs (p=0.006), a lower age-adjusted Treg and higher IRC frequency (p=0.001). Anticitrullinated peptide antibody (ACPA) positivity was associated with lower naïve (p=0.031) and Treg frequencies (p=0.039). In 50 patients treated with MTX, ACPA/age-adjusted analysis demonstrated that higher naïve cell frequency (relative to HC) was associated with remission (OR 5.90 (1.66 to 20.98), p=0.006, sensitivity/specificity 62%/79%, Positive Predictive Value (PPV)/Negative Predictive Value (NPV) 66%/76%). Remission with MTX+anti-TNF (n=20) was not found to be associated with naïve cell frequency, and for patients with reduced naïve cells the remission rate increased from 24% (MTX) to 42% (MTX+anti-TNF).

CONCLUSIONS

Baseline T-cell subset analysis has a value in predicting early RA remission with first therapy with MTX. Immunological analysis could be used in conjunction with clinical/serological features to predict response to MTX and help select the most appropriate therapy at disease presentation.

Current and future immunomodulation strategies to restore tolerance in autoimmune diseases

Autoimmune diseases reflect a breakdown in self-tolerance that results from defects in thymic deletion of potentially autoreactive T cells (central tolerance) and in T-cell intrinsic and extrinsic mechanisms that normally control potentially autoreactive T cells in the periphery (peripheral tolerance). The mechanisms leading to autoimmune diseases are multifactorial and depend on a complex combination of genetic, epigenetic, molecular, and cellular elements that result in pathogenic inflammatory responses in peripheral tissues driven by self-antigen-specific T cells. In this article, we describe the different checkpoints of tolerance that are defective in autoimmune diseases as well as specific events in the autoimmune response which represent therapeutic opportunities to restore long-term tolerance in autoimmune diseases. We present evidence for the role of different pathways in animal models and the therapeutic strategies targeting these pathways in clinical trials in autoimmune diseases.

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.

Mapping pathogenesis of arthritis through small animal models

Animal models have been used for a number of decades to study arthritis and have contributed greatly to unravelling mechanisms of pathogenesis and validating new targets for treatment. All animal models have sets of limitations and over the years there has been natural refinement of existing models as well as creation of new ones. The success of genetic modification in mice has fuelled an exponential increase in the use of murine models for arthritis research and has significantly increased our understanding of disease processes. This review focuses on those rodent models of RA and OA that have current utility and are widely used by the research community. We highlight the subtle but important differences in existing models by positioning them on a pathogenesis map whereby model selection is determined by the specific aspect of disease to be studied. We discuss the evolving challenges in in vivo arthritis studies and our perceived gaps for future new model development. The document includes technical and cost implications of performing the described models, and the ethical considerations of such approaches.

Chronic Proliferative Dermatitis in Mice: NFκB Activation Autoinflammatory Disease

Autoinflammatory diseases are a heterogeneous group of congenital diseases characterized by the presence of recurrent inflammation, in the absence of infectious agents, detectable autoantibodies or antigen-specific autoreactive T-cells. SHARPIN deficient mice presents multiorgan chronic inflammation without known autoantibodies or autoreactive T-cells, designated Sharpin(cpdm). Histological studies demonstrated epidermal hyperproliferation, Th-2 inflammation, and keratinocyte apoptosis in this mutant. The mutant mice have decreased behavioral mobility, slower growth, and loss of body weight. Epidermal thickness and mitotic epidermal cells increase along with disease development. K5/K14 expression is distributed through all layers of epidermis, along with K6 expression in interfollicular epidermis, suggesting epidermal hyperproliferation. K1/K10 is only detectable in outer layers of spinosum epidermis, reflecting accelerated keratinocyte migration. Alpha smooth muscle actin is overexpressed in skin blood vessels, which may release the elevated white blood cells to dermis. CD3(+)CD45(+) cells and granulocytes, especially eosinophils and mast cells, aggregate in the mutant skin. TUNEL assay, together with Annexin-V/propidium iodide FACS analysis, confirmed the increase of apoptotic keratinocytes in skin. These data validate and provide new lines of evidence of the proliferation-inflammation-apoptosis triad in Sharpin(cpdm) mice, an NFκB activation autoinflammatory disease.

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.

Autologous stem cell transplantation in autoimmune and rheumatic diseases: from the molecular background to clinical applications

Autoimmune diseases have a multifactorial origin. Because of disturbances of the immune system, autoreactive T and B cells target self-antigens, leading to permanent organ damage. Despite novel therapeutic protocols, the disease course is chronic and in many instances the outcome is lethal. The efficacy of stem cell therapy has been observed in autoimmune animal models and in autoimmune diseases related to haematological abnormalities. Although the therapy is more than 30 years old, its broad spread has been delayed by the serious side-effects due to the conditioning treatments based on oncological protocols. Evaluation of the data of patients who have undergone autologous stem cell therapy reinforced the view that protocols used for conditioning treatments, mostly causing lymphoablation, and procedures carried out in specialist centres significantly reduced mortality, with an almost optimal therapeutical efficacy. New, multicentre investigations have been launched to compare the efficacy of various protocols. In this review, we summarize certain aspects of the molecular background of autologous stem cell transplantation and also depict the response to therapy in various autoimmune and rheumatic diseases.

The role of T cells in rheumatoid arthritis: new subsets and new targets

PURPOSE OF REVIEW

To update the knowledge on the contribution of T cells in rheumatoid arthritis, a selection of publications between the end of 2005 and 2006 were reviewed.

RECENT FINDINGS

Th17 cells driven by TGF-beta, IL-1, IL-6 and IL-23 challenge previous concepts of 'Th1'-induced rheumatoid arthritis. Other advancements in IL-17 studies include novel concepts on the IL-17 receptor and additional information on the mechanism of IL-17-induced effects. Regulatory T cells fail to control disease due to defective function secondary to the synovial inflammatory milieu. The predominance of pathogenic effector T cells in the presence of impaired T-cell regulatory mechanisms may therefore contribute to rheumatoid arthritis chronicity. Cellular therapies attempt to restore the balance that includes production of immunoregulatory cytokines such as IL-4 or IL-10. Better T-cell-targeted therapies controlling costimulation are in place with purported increased efficacy and durability, including anti-tumour necrosis factor nonresponders. Additional direct and indirect T-cell approaches include antagonism of T-cell-derived cytokines, T-cell activation or B-cell ablation.

SUMMARY

A renewed interest in T cells comes from the discovery of Th17 in rheumatoid arthritis and from novel findings on the role of T cells in rheumatoid arthritis induction, chronicity and relapse.

Comparison of efficacy of arthroscopic lavage plus administration of corticosteroids, arthroscopic lavage plus administration of placebo, and joint aspiration plus administration of corticosteroids in arthritis of the knee: A randomized controlled trial

OBJECTIVE

To compare the efficacy of arthroscopic lavage plus administration of corticosteroids (ALC), arthroscopic lavage plus administration of placebo (ALP), and joint aspiration plus administration of corticosteroids (JAC) in knee arthritis, and to evaluate whether clinical or histologic characteristics determine outcome.

METHODS

Patients with knee arthritis (not due to gout, osteoarthritis, or septic arthritis) were randomized over 3 treatment arms: ALC, ALP, and JAC. The primary end point was event-free survival, with events defined as 1) recurrence or persistence of symptomatic knee swelling necessitating local re-treatment, or 2) nonimprovement of the knee joint score. Synovial tissue specimens were collected and analyzed histologically to identify predictive factors of responsiveness.

RESULTS

A total of 78 patients were enrolled; 3 patients did not receive their allocated therapy and 3 were lost to followup. The median time until recurrence was 9.6 months after ALC, 3.0 months after JAC, and 1.0 month after ALP, corresponding to a relative risk (RR) of arthritis recurrence of 2.2 for JAC (95% confidence interval [95% CI] 1.2-4.2, P = 0.02) and 4.7 for ALP (95% CI 2.3-9.4, P < 0.0001) compared with ALC. A high versus low synovial extent of fibrosis conferred an RR for recurrence of 5.7 (95% CI 1.6-20.5, P < 0.01) after ALC.

CONCLUSION

Arthroscopic lavage plus administration of corticosteroids was more effective than arthroscopic lavage plus administration of placebo or joint aspiration plus injection of corticosteroids. The absence of fibrosis was a histologic predictor of a beneficial response.

T-cell-targeted therapies in rheumatoid arthritis

T cells regulate the disease process in rheumatoid arthritis (RA) on multiple levels and represent a logical choice for anti-inflammatory therapy. In the inflamed joint they promote neoangiogenesis and lymphoid organogenesis, and stimulate synoviocyte proliferation and development of bone-eroding osteoclasts. The design of T-cell-targeted therapies for RA needs to take into account the uniqueness of T-cell generation, turnover and differentiation in affected patients. Patients accumulate 'old' T cells that respond to alternate regulatory signals because of an accelerated immune aging process; any therapeutic interventions that increase the replicative stress of T cells should, therefore, be avoided. Instead, therapeutic approaches that raise the threshold for T-cell activation are more promising. As a rule, antigen-derived signals synergize with co-stimulatory signals to stimulate T cells; such co-stimulatory signals are now targeted in novel immunosuppressive therapies. An example is abatacept (soluble cytotoxic-T-lymphocyte-associated protein 4-immunoglobulin), which binds with high affinity to CD80/CD86 and effectively suppresses inflammatory activity in RA. The therapeutic benefits gained by disrupting T-cell co-stimulation indicate that the pathogenesis of RA is driven by a more generalized abnormality in T-cell activation thresholds rather than a highly selective action of arthritogenic antigens.

[Hematopoietic stem cell transplantation in systemic autoimmune diseases. State of the art]

The use of stem cell transplantation for severe autoimmune diseases refractory to conventional therapy arose from two discoveries: the excellent results of animal experiments, and serendipitous observations in human coincidental diseases. Experimental data and early phase I-II trials in highly selected patients suggest that highdose chemotherapy followed by autologous hematopoietic stem cell transplantation can arrest progression of severe autoimmune diseases with an acceptable risk/benefit ratio. The present article reviews the phase II-III prospective, multicenter, randomized trials that have been performed in distinct autoimmunediseases. In addition, allogeneic stem cell transplantation for autoimmune diseases is being cautiously explored in current protocols.

Co-stimulatory blockade as therapy for rheumatoid arthritis

There is substantial evidence that rheumatoid arthritis is an autoimmune disease in which T cells are aberrantly activated. Existing therapies, including anti-tumor necrosis factor therapies, are successful for many patients, but the goal of lasting remission still frequently proves elusive. One novel therapeutic strategy is the blockade of T-cell co-stimulation to modulate T-cell activation. The first co-stimulation blocker to reach clinical trials is abatacept (CTLA4Ig). Initial abatacept trials have shown promise and further phase III trials are underway.