Efficacy of B-cell-targeted therapy with rituximab in patients with rheumatoid arthritis

Treatment of Graves' disease and associated ophthalmopathy with the anti-CD20 monoclonal antibody rituximab: an open study

INTRODUCTION

Hyperthyroid Graves' disease (GD) is a B-cell-mediated condition caused by TSH receptor antibodies (TRAb), which decline when GD remits. Anti-CD20 monoclonal antibody rituximab (RTX) induces transient B-cell depletion that may potentially modify the active inflammatory phase of thyroid-associated ophthalmopathy (TAO).

METHODS

Nine patients with GD, (seven with active TAO, two with mild lid signs) were studied. The trial was only approved as an open pilot study; thus we compared the effect of RTX therapy to that of i.v. glucocorticoids (IVGC) in 20 consecutive patients. Patients were treated with RTX (1000 mg i.v. twice at 2-week interval) or with IVGC (500 mg i.v. for 16 weeks). TAO was assessed by the clinical activity score (CAS) and severity was classified using NOSPECS (No signs or symptoms; Only signs (lid); Soft tissue involvement; Proptosis, Extraocular muscle involvement; Corneal involvement; Sight loss). Thyroid function and lymphocyte count were measured by standardized methods.

RESULTS

All patients attained peripheral B-cell depletion with the first RTX infusion. Minor side effects were reported in three patients. Thyroid function was not affected by RTX therapy and hyperthyroid patients required therapy with methimazole. After RTX, the changes in the levels of thyroglobulin antibodies, thyroperoxidase antibodies and TRAb were neither significant nor correlated with CD20+ depletion (P = NS). CAS values before RTX were 4.7 +/- 0.5 and decreased to 1.8 +/- 0.8 at the end of follow-up (P < 0.0001) and more significantly compared with IVGC (P < 0.05). Proptosis decreased significantly after RTX both in patients with active TAO (ANOVA; P < 0.0001) and those with lid signs (ANOVA; P < 0.003). The degree of inflammation (class 2) decreased significantly in response to RTX (ANOVA; P < 0.001). Relapse of active TAO was not observed in patients treated with RTX, but occurred in 10% of those treated with IVGC, who also experienced adverse effects more frequently (45 vs 33% of patients).

CONCLUSIONS

RTX positively affects the clinical course of TAO, independently of either thyroid function or circulating antithyroid antibodies, including TRAb. If our findings are confirmed in large controlled studies, RTX may represent a useful therapeutic tool in patients with active TAO.

Early effects of rituximab on the synovial cell infiltrate in patients with rheumatoid arthritis

OBJECTIVE

To study the specific effects of rituximab treatment on the synovium in patients with rheumatoid arthritis (RA) early after initiation of treatment.

METHODS

Seventeen RA patients underwent an arthroscopic synovial biopsy procedure directly before and 1 month after receiving 2 infusions of the chimeric anti-CD20 monoclonal antibody rituximab (1,000 mg on days 1 and 15; both without methylprednisolone premedication). Immunohistochemical analysis was performed to characterize the cell infiltrate. Stained tissue sections were analyzed by digital image analysis. Statistical analysis was performed using Wilcoxon's signed rank test.

RESULTS

No significant change in the Disease Activity Score 28-joint assessment was found at 4 weeks after the first rituximab infusion. At 2 and 4 weeks after infusion, B cells in peripheral blood were almost completely depleted. Most B cells in the synovium were found in large lymphocyte aggregates. Interestingly, a significant reduction in B cell numbers at sites of inflammation was observed 4 weeks after treatment (median 26 cells/mm(2) [interquartile range 4-150] before treatment and 11 cells/mm(2) [interquartile range 0-29] after treatment; P < 0.02). B cells disappeared completely in 3 patients, whereas there was partial depletion in 11 patients. In the other 3 patients, no B cells were present in biopsy tissues obtained either pretreatment or posttreatment. No reductions in other synovial cell populations were observed at 4 weeks.

CONCLUSION

Rituximab treatment leads to a rapid and significant decrease in synovial B cell numbers, but not in all patients. Whether the variable tissue response is related to the clinical response over time remains to be clarified.

Cell therapy for autoimmune diseases

Cell therapy, pioneered for the treatment of malignancies in the form of bone marrow transplantation, has subsequently been tested and successfully employed in autoimmune diseases. Autologous haemopoietic stem cell transplantation (HSCT) has become a curative option for conditions with very poor prognosis such as severe forms of scleroderma, multiple sclerosis, and lupus, in which targeted therapies have little or no effect. The refinement of the conditioning regimens has virtually eliminated transplant-related mortality, thus making HSCT a relatively safe choice. Although HSCT remains a nonspecific approach, the knowledge gained in this field has led to the identification of new avenues. In fact, it has become evident that the therapeutic efficacy of HSCT cannot merely be the consequence of a high-dose immuno-suppression, but rather the result of a resetting of the abnormal immune regulation underlying autoimmune conditions. The identification of professional and nonprofessional immunosuppressive cells and their biological properties is generating a huge interest for their clinical exploitation. Regulatory T cells, found abnormal in several autoimmune diseases, have been proposed as central to achieve long-term remissions. Mesenchymal stem cells of bone marrow origin have more recently been shown not only to be able to differentiate into multiple tissues, but also to exert a potent antiproliferative effect that results in the inhibition of immune responses and prolonged survival of haemopoietic stem cells. All of these potential resources clearly need to be investigated at the preclinical level but support a great deal of enthusiasm for cell therapy of autoimmune diseases.

Induction of dominant tolerance using monoclonal antibodies

Monoclonal antibodies (MAb) have been shown to be effective in inducing immune tolerance in transplantation and autoimmunity. Several different MAb have tolerogenic properties and their effect has been studied in a range of experimental animal models and, in some cases, in clinical trials. The tolerant state seems to be maintained by CD4+ regulatory T cells (Treg), induced in the periphery, capable of suppressing other T cells specific for the same antigens or antigens presented by the same antigen presenting cells. Furthermore, following the initial induction of Treg cells under MAb treatment, Treg cells themselves can maintain the tolerant state in a dominant way in the absence of the therapeutic MAb or other immunosuppressive agents, and are able to recruit other T cells into the regulatory pool--a process named infectious tolerance.

Rheumatoid arthritis and the complement system

Complement activation contributes to a pathological process in a number of autoimmune and inflammatory diseases, including rheumatoid arthritis (RA). In this review we summarize current knowledge of complement contribution to RA, based on clinical observations in patients and in vivo animal models, as well as on experiments in vitro aiming at elucidation of underlying molecular mechanisms. There is strong evidence that both the classical and the alternative pathways of complement are pathologically activated during RA as well as in animal models for RA. The classical pathway can be initiated by several triggers present in the inflamed joint such as deposited autoantibodies, dying cells, and exposed cartilage proteins such as fibromodulin. B cells producing autoantibodies, which in turn form immune complexes, contribute to RA pathogenesis partly via activation of complement. It appears that anaphylatoxin C5a is the main product of complement activation responsible for tissue damage in RA although deposition of membrane attack complex as well as opsonization with fragments of C3b are also important. Success of complement inhibition in the experimental models described so far encourages novel therapeutic approaches to the treatment of human RA.

Clinical trial of a leucotriene B4 receptor antagonist, BIIL 284, in patients with rheumatoid arthritis

BACKGROUND

Several clinical and experimental lines of evidence suggest that leucotriene B4 (LTB4), an arachidonic acid derivative with potent proinflammatory properties, plays a key role in the pathophysiology of rheumatoid arthritis (RA).

OBJECTIVE

To evaluate the efficacy and safety of BIIL 284, an oral long-acting LTB4 receptor antagonist, as monotherapy for the treatment of patients with active RA.

METHODS

This was a multi-centre, randomised, double-blind, placebo-controlled trial of patients with active RA of 3 months' duration. A total of 342 patients were randomised to receive 5 mg, 25 mg or 75 mg of BIIL 284 or placebo. The primary end point was the percentage of patients achieving an American College of Rheumatology (ACR) 20.

RESULTS

Although a higher percentage of ACR 20 responders was observed in the groups treated with 25 mg and 75 mg of BIIL 284 compared with those treated with placebo, no statistically significant differences were found between any of the three active treatment groups compared with the placebo group with regard to the primary or secondary end points. All trial treatments were safe and well tolerated.

CONCLUSIONS

This clinical trial demonstrates that treatment of patients with active RA with a potent oral long-acting LTB4 receptor antagonist produced only modest improvements in disease activity. The results of this trial support the conclusion that LTB4 is not a major contributor to the inflammatory process in RA.

Does our current understanding of the molecular basis of immune tolerance predict new therapies for autoimmune disease?

The creation of specific immune tolerance has often been referred to as the ultimate goal of immunotherapy, because it would allow autoimmune disease to be reversed without the need for nonspecific and potentially harmful immunosuppressive therapy. Studies performed during the past decade have been immensely fruitful in terms of advances in our understanding of the cellular and molecular mechanisms of immune tolerance, and have paved the way for successful exploitation of these mechanisms for therapeutic purposes. Important developments include an increased understanding of central and peripheral tolerance, and treatment strategies that mimic the mechanisms behind deletion of self-reactive cells, the identification of crucial gene products that are involved in the induction of anergy, and the characterization of regulatory T cells and protocols for their induction and expansion for therapeutic applications. These landmarks of immune-tolerance research are summarized and their potential use in the immunotherapy of autoimmune disease discussed.

Changes in macrophage function after rituximab treatment in patients with rheumatoid arthritis

OBJECTIVE

To assess changes in macrophage phenotype and function after rituximab-induced B cell depletion in patients with rheumatoid arthritis (RA).

METHODS

10 patients with RA were treated with rituximab, achieving significant B cell depletion 4 months later. Clinical improvement, rheumatoid factor (RF), anti-cyclic citrullinated peptide (anti-CCP) antibodies, mRNA of B cell activating factor (BAFF), interleukin (IL) 10 and CD86 in human monocyte-derived macrophages (HMDMs) and tumour necrosis factor alpha (TNFalpha) secretion from cultured HMDMs were assessed at baseline and after the depletion.

RESULTS

A clinical response of American College of Rheumatology (ACR) 50% improvement was noted in six patients, and another two patients responded with moderate improvement, equivalent to ACR 20-50% improvements. RF and anti-CCP antibodies were positive at baseline in seven of ten patients. RF disappeared or declined in six patients 4 months after treatment, correlating with clinical improvement. By contrast, anti-CCP remained unchanged in six patients. After rituximab treatment, and in association with clinical improvement, BAFF, IL10 and CD86 mRNA expression in HMDM were significantly upregulated compared with values at baseline. A significant decrease in TNFalpha in the supernatant of cultured HMDM was also noted.

CONCLUSIONS

In addition to B cell depletion and attenuation in some of the specific autoantibodies, clinical improvement in rituximab-treated patients with RA occurred in association with changes in macrophage function.

Autoantibodies in rheumatoid arthritis: a review

Emerging insights into the importance of B cells in the pathogenesis of rheumatoid arthritis (RA) as highlighted by the efficacy of B cell depletion is one factor that has contributed to the upsurge of interest in the potential role of autoantibodies both as disease markers and with respect to a pathogenic role. Since the initial description of rheumatoid factor (RF), a large number of both disease-specific and non-specific autoantibodies have been described in patients with RA including antibodies to type II collagen (CII), immunoglobulin binding protein (BiP) and antibodies directed at citrullinated peptides (anti-CCP) and other citrullinated proteins such as vimentin (anti-Sa) . Despite some overlap the serological profile of RA does appear to be distinct from other diseases such as SLE . Although the precise mechanisms responsible for the formation of these antibodies have not been well defined their presence must reflect the interaction between T and B cells believed to be relevant to the pathogenesis of RA. The specificity of the association of such factors as anti-CCP and anti-BiP with RA may reflect unique pathogenic events leading to the processing and presentation of the "cryptic self" . Ease of measurement and stability make autoantibodies attractive diagnostic and prognostic markers particularly in early disease when it may be difficult to distinguish self-limiting synovitis from persistent disease . The purpose of this article is to provide an overview of the current state of knowledge of the spectrum of autoantibodies thus far characterised in individuals with rheumatoid arthritis, and discuss their diagnostic, prognostic and pathogenetic relevance.

Targeting BAFF: Immunomodulation for autoimmune diseases and lymphomas

In an effort to develop more effective treatments for inflammatory diseases, immunologists have targeted numerous molecular pathways, but with limited success. Notable exceptions are anti-TNF agents, which have proved efficacious in a proportion of rheumatoid arthritis (RA) patients. Another TNF family member, termed BAFF ("B cell-activating factor belonging to the TNF family"), plays a central role in autoimmune diseases, as well as in B cell maturation, survival, and T cell activation. Agents that block BAFF have proven to be highly effective in the treatment of certain autoimmune conditions in mice. In addition, phase II data in human clinical trials for RA appear very promising. BAFF is also a survival factor for certain B cell lymphomas. Despite the relatively recent identification of BAFF, this molecule has provided considerable new insight into B cell homeostasis and immune function, and represents an important new molecular target for treatment of autoimmune diseases and lymphomas.

Quantitative analysis of protein co-localization on B cells opsonized with rituximab and complement using the ImageStream multispectral imaging flow cytometer

Binding of the chimeric, humanized anti-CD20 mAb Rituximab (RTX) to B lymphocytes activates complement and promotes covalent deposition of C3 fragments (C3b/iC3b) on cells. Previous fluorescence microscopy studies, based on examination of B cell lines and of blood samples from RTX-treated CLL patients, suggest that C3b/iC3b is closely associated with cell-bound RTX. We examined Raji cells opsonized with serum and RTX with the ImageStream imaging flow cytometer. Cells were stained with fluorescently-labeled RTX and mAbs specific for C3b/iC3b fragments or for human IgG, and then imaged using the ImageStream cytometer and analyzed with an algorithm (Similarity Bright Detail Score, SBDS) which tests for co-localization of fluorescent probes. SBDS, calculated on 10,000 cells, verified that the majority of deposited C3b/iC3b is co-localized with bound RTX. In contrast, when cells were first opsonized in serum alone, washed and then reacted with RTX, SBDS confirmed that RTX and C3b/iC3b are poorly co-localized, thus demonstrating that cell-bound RTX directs deposition of C3b. In addition, a sulfhydryl-specific probe, maleimide conjugated to AF488, exhibited substantial co-localization with an anti-C3b/iC3b mAb on Raji cells opsonized with RTX and serum, thus validating maleimide labeling as an alternative for detecting cell-bound C3b/iC3b. The digital imaging method described should have wide applicability for quantitative analysis of co-localization.

Immune therapies of autoimmune diseases: are we approaching a real cure?

In developed countries, autoimmune diseases represent the third major cause of morbidity and mortality after cancer and atherosclerosis and their incidence has steadily increased over the past three decades. Conventional therapeutic approaches are essentially palliative, anti-inflammatory or immunosuppressive; in addition, they are non-specific, unrelated to the antigens involved in disease pathogenesis. This explains the growing attention to modern technologies that made new biological agents and methods available. A few of these are already approved for regular clinical practice; others are still in clinical development but hold great promise. The question is: will these new tools allow us to develop a real cure for autoimmunity, restoring self-tolerance to target autoantigens? This goal is ambitious, namely harnessing the pathogenic immune response while preserving the host response to exogenous or unrelated antigens.

B lymphocytes as therapeutic targets in systemic lupus erythematosus

In recent years, experimental evidence supporting a major role of B cells in the pathogenesis of autoimmune diseases has grown. This includes the discovery of novel mechanisms of autoantibody pathogenicity and the potential of B cells to mediate inflammation and tissue injury. In some instances, engagement of the B cell receptor and other surface receptors is sufficient to stimulate B cells to produce antibody. As a result, B cells have become targets for immunointervention. In lupus, targeting B cell activation factor (BAFF, BLys) indicates that specific blockade of this longevity factor might be sufficient to suppress systemic autoimmunity. Targeting CD20 represents another promising avenue for the treatment of refractory lupus in both adults and children. Although the clinical data add weight to the importance of B cells in the pathogenesis of lupus, new targets for B cell depletion therapy are being investigated. In experimental models, combining CD19 and CD20 antibodies was more effective than either treatment alone.

Association of HLA-C3 and smoking with vasculitis in patients with rheumatoid arthritis

OBJECTIVE

To compare HLA-C genotypes and smoking habits in patients with vasculitis or other severe extraarticular manifestations of rheumatoid arthritis (ExRA) with those in RA patients without extraarticular disease.

METHODS

Patients were recruited from a large research database of patients with RA at the Mayo Clinic, from 2 Swedish cohorts of prevalent RA cases, and from a regional Swedish early RA cohort. Patients with severe ExRA (n = 159) and control patients with RA but no history of ExRA (non-ExRA controls) (n = 178) were matched for duration of RA and for clinical center. Data on smoking at RA onset, rheumatoid factor (RF) status, and antinuclear antibodies (ANAs) were extracted from the medical records. Polymerase chain reaction-based HLA-C genotyping was performed using a sequence-specific primer kit.

RESULTS

The distribution of HLA-C alleles was significantly different between patients with RA-associated vasculitis and non-ExRA controls (P = 0.014). This was mainly due to a positive association of the HLA-C3 allele with vasculitis (allele frequency 0.411 in vasculitis patients versus 0.199 in non-ExRA controls; P < 0.001) and a decreased frequency of HLA-C7 (0.122 and 0.243, respectively; P = 0.018). The association between HLA-C3 and vasculitis was not due to linkage disequilibrium with HLA-DRB1. Smoking (P = 0.001), RF positivity (P < 0.0001), and presence of ANAs (P < 0.0001) were all associated with ExRA. HLA-C3 and smoking were both significant predictors of vasculitis in a multivariate model.

CONCLUSION

Vasculitis in RA is associated with HLA-C3. Smoking is an independent predictor of vasculitis and other types of severe ExRA. Our results suggest that these variables are among the genetic and environmental factors that contribute significantly to the pathomechanisms of systemic RA.

Long-term comparison of rituximab treatment for refractory systemic lupus erythematosus and vasculitis: Remission, relapse, and re-treatment

OBJECTIVE

Current treatments for systemic lupus erythematosus (SLE) and vasculitis contribute to mortality and incapacity and are only partially effective; thus, newer therapies are clearly needed. Depletion of B cells has led to disease control in patients with autoimmune disorders. We sought to assess the long-term efficacy and safety of a B cell-depleting therapy in patients with SLE and patients with vasculitis.

METHODS

In a prospective study with a median followup of 24 months, 11 patients with active or refractory SLE and 11 patients with active or refractory antineutrophil cytoplasmic antibody-associated vasculitis (AAV) received a course of therapy with rituximab (an anti-CD20 monoclonal antibody) along with a single dose of intravenous cyclophosphamide.

RESULTS

Remission followed rapid B cell depletion, with response rates of 100% among the 11 patients with SLE (6 patients had a complete response, and 5 patients had a partial response) and 91% among the 11 patients with AAV (9 patients had a complete response, and 1 patient had partial remission). A renal response occurred in all 6 patients with lupus nephritis. Clinical improvement was accompanied by significant reductions in the daily dose of prednisolone. Relapse occurred in 64% of the patients with SLE and in 60% of those with AAV. B cell return preceded relapse in the majority of patients, and further treatment with rituximab proved effective. IgG and IgM levels were maintained in the normal range. The incidence of infective complications was low; however, infusion reactions were common, and human antichimeric antibodies developed in 5 of 14 patients.

CONCLUSION

B cell depletion offers the prospect of sustained disease remission and improved disease control combined with low toxicity in patients with active or refractory SLE or AAV. Relapse following treatment is common, but re-treatment is rapidly effective.

High IgA rheumatoid factor levels are associated with poor clinical response to tumour necrosis factor alpha inhibitors in rheumatoid arthritis

OBJECTIVE

To investigate whether rheumatoid factor isotypes and anti-cyclic citrullinated peptide (anti-CCP) antibodies are related to clinical response in patients with rheumatoid arthritis treated with tumour necrosis factor alpha (TNFalpha) inhibitors.

METHODS

The study was carried out on 132 patients with advanced rheumatoid arthritis refractory to disease-modifying antirheumatic drugs. Patients were treated with infliximab (n = 63), etanercept (n = 35) or adalimumab (n = 34). All patients completed 1 year of follow-up, and 126 were evaluable for clinical response according to the disease activity score (DAS) criteria. IgM, IgA and IgG rheumatoid factors and anti-CCP antibodies were assessed by ELISA both before anti-TNFalpha treatment and 1 year later.

RESULTS

The DAS response was reached in 66% of evaluable patients (61% infliximab, 65% etanercept and 76% adalimumab; p = 0.354). A significant reduction in the rheumatoid factor level was reported by all treatment groups after 1 year. The frequency of positive tests for the different antibodies did not differ between responders and non-responders at baseline; however, significantly higher IgA rheumatoid factor levels were reported by the non-responder group (130.4 U/ml (interquartile range 13.8-276.7) v 24.8 U/ml (10.2-90.8); p = 0.003). A significant decrease (p<0.001) in the levels of all rheumatoid factor isotypes in the responder group was reported after 1 year of treatment, whereas anti-CCP antibody levels were not significantly affected.

CONCLUSIONS

According to the clinical response, anti-TNFalpha agents seem to reduce IgM, IgG and IgA rheumatoid factor levels. More interestingly, high pretreatment levels of IgA rheumatoid factor are associated with a poor clinical response to TNFalpha inhibitors.

B cells drive early T cell autoimmunity in vivo prior to dendritic cell-mediated autoantigen presentation

Both B cells and dendritic cells (DCs) have been implicated as autoantigen-presenting cells in the activation of self-reactive T cells. However, most self-proteins are ubiquitously and/or developmentally expressed, making it difficult to determine the source and the exposure of autoantigens to APCs in a controlled manner. In this study, we have used an Ig transgenic mouse model to examine the mechanisms by which B cells and other APCs acquire and present lupus autoantigens in vivo. Targeting a lupus autoantigen, the small nuclear ribonucleoprotein particle D protein, to the BCR activates autoreactive T cells in the periphery. Our in vivo studies demonstrate that autoantigen-specific B cells, when present in the repertoire, are the first subset of APCs to capture and present self-proteins for activating T cells. Thereafter, DCs acquire self-Ag and become effective APCs for stimulating the same subsets of autoreactive T cells. This mechanism provides one explanation of how early steps in autoimmunity can focus responses, via BCR, at a small group of self-proteins among the total milieu of intracellular self-proteins. Subsequently, DCs and other professional APCs may then amplify and perpetuate the autoimmune T cell response.

Novel therapies for rheumatoid arthritis

Rheumatoid arthritis (RA) is a chronic, systemic inflammatory disease that causes significant morbidity and mortality. The pathogenesis outlined to date in RA consists of a cascade of pro-inflammatory cytokines and chemokines leading to the recruitment of inflammatory cells and the self perpetuation of inflammation, ultimately leading to cartilage and bone destruction. The dramatic progress in understanding the molecular immunology in RA has led to a transition from conventional treatment with aggressive immune suppression to targeted biological-based therapies that control the inflammatory pathways associated with RA. This article reviews the current biological and small-molecule therapies approved for the treatment of RA and those in development, including antibodies, tolerising agents and vaccines.

B-cell targeted therapies in rheumatoid arthritis and systemic lupus erythematosus

B cells appear to have a central role in the immunopathogenesis of rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE); both autoantibody production and B-cell anomalies are characteristic of these diseases. With the recent availability of biologic agents that can deplete B cells or block their function in vivo, it has become possible to target B cells therapeutically. Evidence strongly suggests that novel B-cell targeting agents are effective. In addition, the mechanistic specificity of B-cell targeted approaches, combined with the ability to test them in large randomized controlled trials, will provide an unprecedented opportunity to study the precise roles of B cells in the immunopathogenesis of RA and SLE. The largest volume of information is available for rituximab, a chimeric monoclonal antibody that depletes B cells by binding to the CD20 cell-surface antigen. Information from multiple investigator-sponsored trials and from off-label use suggests efficacy of this antibody in RA, SLE, and other autoimmune syndromes. Randomized controlled trials have also provided solid evidence for the efficacy of rituximab in RA and are ongoing in SLE. Other therapeutic agents supported by controlled data include cytotoxic T-lymphocyte-associated protein 4 immunoglobulin and antibodies against the interleukin-6 receptor and the B-cell survival molecule BLyS. Additional agents and targets are in earlier stages of development. The concerns about infectious complications have so far not proven to be justified. We can reasonably expect important advances in the understanding and treatment of RA and SLE in the next 5-10 years, as B-cell targeting methods become more widespread and sophisticated.

Critical issues of current and future developments in the treatment of immune thrombocytopenic purpura

B-cell depletion with rituximab has become a reasonable option for thrombocytopenic purpura (ITP) patients who are refractory for corticosteroids and/or splenectomy, with a response rate of about 55%. The side effects are mostly mild and easily manageable. Long lasting responses are likely in patients who achieve normal platelet counts. The mechanism of action of rituximab in immune-mediated disease in general and ITP in particular is not completely clear. Most probably, depletion of the memory B-cell compartment causes a decrease in autoantibody formation. To date it is impossible to predict the response to rituximab, although the presence of a high affinity Fc receptor for IgG seems to have positive predictive value. Future studies will have to clarify these issues, as well as possible effects of repeated rituximab treatment on primary and secondary immune responses.

Treatment with rituximab affects both the cellular and the humoral arm of the immune system in patients with SLE

Herein we investigated how rituximab-induced B cell depletion affected leukocyte subpopulations and antibody titers in SLE patients. We focused our analysis on time points related to absence and return of B cells after depletion. A correlation was found between the baseline frequency and time to repopulation; the fewer B cells initially, the longer to their return. While the few B cells remaining after treatment were of memory, double-negative (IgD-CD27-), and CD5+ phenotype, the returning B cells were mainly naïve, indicating de novo production of B cells. Serum levels of IgG and antibodies against Ro52, Ro60, La44, measles and tetanus remained unchanged, while decreases in IgM, IgE, anti-dsDNA and anti-C1q antibodies were observed. Additionally, a significant increase in activated CD4+ and CD8+ T cells, as well as CD25bright FOXP3+ regulatory T cells was observed. In conclusion, both the humoral and the cellular immune systems were affected by treatment with rituximab.

Increase of B cell-activating factor of the TNF family (BAFF) after rituximab treatment: insights into a new regulating system of BAFF production

BACKGROUND

The cytokine B cell-activating factor of the TNF family (BAFF) is involved in the pathogenesis of autoimmune diseases.

OBJECTIVE

To access changes in serum protein and mRNA levels of BAFF after rituximab treatment.

METHODS

Serum and peripheral blood mononuclear cells (PBMCs) were isolated from five patients (two with lupus, two with Sjögren's syndrome, one with rheumatoid arthritis) before and 12 weeks (range 7-17) after a first course of rituximab infusion. Monocytes and B cells were selected from healthy controls and cocultured for 72 h. BAFF protein and mRNA levels were assessed by ELISA and real-time PCR, respectively.

RESULTS

After rituximab treatment, median serum BAFF protein level and BAFF to actin mRNA ratio in PBMCs significantly increased. In monocytes cocultured with autologous B cells, BAFF protein level decreased, whereas the mRNA level was stable. In one closely monitored patient, the mRNA ratio of BAFF to actin in PBMCs increased later than the BAFF serum level.

CONCLUSIONS

Two distinct mechanisms are probably involved in the increase in BAFF level after B cell depletion: (1) the decrease in its receptors leading to a release of BAFF; (2) a delayed regulation of BAFF mRNA transcription. This could favour the re-emergence of autoreactive B cells.

B cells in the pathophysiology of autoimmune neurological disorders: A credible therapeutic target

There is evidence that B cells are involved in the pathophysiology of many neurological diseases, either in a causative or contributory role, via production of autoantibodies, cytokine secretion, or by acting as antigen-presenting cells leading to T cell activation. Clonal expansion of B cells either in situ or intrathecally and circulating autoantibodies are critical elements in multiple sclerosis (MS), Devic's disease, paraneoplastic central nervous system disorders, stiff-person syndrome, myasthenia gravis, autoimmune demyelinating neuropathies and dermatomyositis. The pathogenic role of B cells and autoantibodies in central and peripheral nervous system disorders, as reviewed here, provides a rationale for investigating whether depletion of B cells with new agents can improve clinical symptomatology and, potentially, restore immune function. Preliminary results from several clinical studies and case reports suggest that B cell depletion may become a viable alternative approach to the treatment of autoimmune neurological disorders.

Treating very early rheumatoid arthritis

Rheumatoid arthritis (RA) is common and leads to joint damage due to persistent synovitis. The persistence of inflammation is maintained by hyperplastic stromal tissue, which drives the accumulation of leukocytes in the synovium. Aggressive treatment after the first 3-4 months of symptoms, with either disease modifying anti-rheumatic drugs or anti-tumor necrosis factor (TNF)-alpha therapy, reduces the rate of disease progression. However, it rarely switches off disease such that remission can be maintained without the continued need for immunosuppressive therapy. There is increasing evidence that the first few months after symptom onset represent a pathologically distinct phase of disease. This very early phase may translate into a therapeutic window of opportunity during which it may be possible to permanently switch off the disease process. The rationale for, and approaches to, treatment within this very early window are discussed.

Update on the treatment of lupus nephritis

Lupus nephritis (LN) is a major cause of morbidity and mortality in patients with systemic lupus erythematosus. Although the use of aggressive immunosuppression has improved both patient and renal survival over the past several decades, the optimal treatment of LN remains challenging. Improved outcomes have come at the expense of significant adverse effects owing to therapy. Moreover with long-term survival, the chronic adverse effects of effective therapies including risk of malignancy, atherosclerosis, infertility, and bone disease all become more important. Finally, some patients fail to achieve remission with standard cytotoxic therapy and others relapse when therapy is reduced. For these reasons, recent clinical trials have attempted to define alternate treatment protocols that appear to be efficacious in achieving and maintaining remission, but with less toxicity than standard regimens. This paper discusses established and newer treatment options for patients with proliferative and membranous LN, with an emphasis on the results of these recent clinical trials. We also review the experimental and human data regarding some of the novel targeted forms of therapy that are under investigation and in different phases of clinical trials.

An uncontrolled trial of rituximab for antibody associated paraneoplastic neurological syndromes

Anti-CD20 monoclonal antibody (rituximab) is effectively used in the treatment of B-cell lymphomas. Recent reports in the literature suggest that antibody associated autoimmune disorders may respond to rituximab. We therefore treated nine patients with anti-Hu or anti-Yo associated paraneoplastic neurological syndromes (PNS) with a maximum of four monthly IV infusions of rituximab (375mg/m(2)). In this uncontrolled, unblinded trial of rituximab, three patients improved > or =1 point on the Rankin Scale (RS). One patient with limbic encephalitis improved dramatically (RS from 5 to 1). Further studies of rituximab in autoantibody associated PNS are warranted.

B cell-targeted therapy for rheumatoid arthritis: an update on the evidence

Rheumatoid arthritis (RA) is a human systemic autoimmune disease with a prevalence of about 1%. Although an important role for B cells has been demonstrated in animal models of autoimmune, inflammatory arthritis, the importance of B cells in RA has been controversial for decades. The development of therapies targeting B cells may help to resolve this debate. Rituximab, a mouse-human chimeric monoclonal antibody against the B cell-specific antigen CD20, was the first B cell-targeted therapy tested in double-blind, placebo-controlled trials for RA. On the basis of the data from three separate trials, addition of rituximab to methotrexate appears to reduce significantly the signs and symptoms of rheumatoid factor-seropositive RA, as assessed by American College of Rheumatology (ACR) 20, 50 and 70 response criteria, and to be relatively safe. Significant questions about rituximab therapy still need to be addressed, including whether or not treatment with rituximab reduces radiographic progression of joint damage, the safety and efficacy of repeated courses of rituximab, and the long-term effects of rituximab on the immune system. Preliminary data on treatment of RA with belimumab, a fully human monoclonal antibody against B lymphocyte stimulator (a growth and survival factor for B cells) is now available. In a double-blind, placebo-controlled, phase II trial, belimumab was well tolerated and had a significant beneficial effect on the ACR 20 response. Thus, therapies specifically targeting B cells do appear to be effective in the treatment of RA, providing direct evidence that B cells are important in the pathogenesis of RA.

Drug insight: rituximab in renal disease and transplantation

Rituximab, a monoclonal antibody directed against the CD20 molecule found on pre-B cells and mature B cells (but not on plasma cells), was introduced in the late 1990s for the treatment of non-Hodgkin's lymphoma. Recently, this antibody has been used to treat autoimmune diseases, especially those associated with a prominent humoral component and with potentially pathogenic autoantibodies. Small cohort studies have indicated that rituximab could have an important role in the management of these disorders. Rituximab has also been utilized in the transplant setting, to diminish levels of alloreactive antibodies in highly sensitized patients, to manage ABO-incompatible transplants, and to treat rejection associated with B cells and antibodies. The exact mechanism by which rituximab exerts its effects in autoimmunity and transplantation remains unclear, as specific autoantibody or alloantibody levels often seem not to diminish in parallel with clinical improvement. A role for rituximab in depleting B cells and compromising their antigen-presenting function seems likely; rituximab might also inhibit T-cell activation. A synergistic effect has been noted in vitro following administration of corticosteroids to B-cell lines, with accentuation of B-cell cytotoxicity; this observation might be relevant to certain studies, as some regimens have utilized both agents simultaneously. This article reviews the current use of rituximab in renal disease and transplantation, and includes discussion of the drug's potential role in novel therapeutic protocols.

Use of biologics in rheumatoid arthritis: Where are we going?

PURPOSE

The pharmacology, efficacy, safety, and costs of biologic agents that are approved by the Food and Drug Administration or are under review for the management of rheumatoid arthritis (RA) are discussed. Biologic therapies that are currently under investigation in early- and late-phase clinical trials are summarized at the end of this report.

SUMMARY

The use of biologic agents for the treatment of RA has significantly improved the management of this disease. Experimental and clinical studies have shown that these agents ameliorate the signs and symptoms of RA, slow radiographic progression of disease, and improve physical function and quality of life. Data also support that early initiation of therapy with these agents improves long-term outcomes. However, biologic agents are associated with adverse effects that health care providers need to recognize and manage.

CONCLUSION

Biologic agents have revolutionized the treatment of RA by reducing the signs and symptoms of RA, slowing radiographic progression of joint destruction, and improving physical function and quality of life in affected patients.

Selective tyrosine kinase inhibition by imatinib mesylate for the treatment of autoimmune arthritis

Tyrosine kinases play a central role in the activation of signal transduction pathways and cellular responses that mediate the pathogenesis of rheumatoid arthritis. Imatinib mesylate (imatinib) is a tyrosine kinase inhibitor developed to treat Bcr/Abl-expressing leukemias and subsequently found to treat c-Kit-expressing gastrointestinal stromal tumors. We demonstrate that imatinib potently prevents and treats murine collagen-induced arthritis (CIA). We further show that micromolar concentrations of imatinib abrogate multiple signal transduction pathways implicated in RA pathogenesis, including mast cell c-Kit signaling and TNF-alpha release, macrophage c-Fms activation and cytokine production, and fibroblast PDGFR signaling and proliferation. In our studies, imatinib attenuated PDGFR signaling in fibroblast-like synoviocytes (FLSs) and TNF-alpha production in synovial fluid mononuclear cells (SFMCs) derived from human RA patients. Imatinib-mediated inhibition of a spectrum of signal transduction pathways and the downstream pathogenic cellular responses may provide a powerful approach to treat RA and other inflammatory diseases.

Immunological memory stabilizing autoreactivity

The etiopathologies of autoimmune diseases are complex. A broad variety of cell types and gene products are involved. However, clinical and experimental evidence suggests that the importance of an individual factor changes during the course of the disease. Factors and cell types that induce acute autoreactivity and initiate an autoimmune disease could be distinct from those that drive a chronic course of that disease. Autoreactive immunological memory, in particular B cell and plasma cell memory, contributes to chronicity through several mechanisms. Formation of autoreactive memory B cells leads to an increase in the numbers of autoreactive cells. In comparison to naive B cells, these memory B cells show a decreased threshold for activation. Additionally, a fraction of memory B cells express the chemokine receptor CXCR3, which supports their accumulation within chronically inflamed tissues. This may allow their escape from mechanisms for induction of peripheral tolerance. Within the inflamed tissue, inflammatory cytokines and autoantigens provide activation signals that promote plasma cell differentiation and survival. The autoantibodies produced locally by these plasma cells contribute to the severity of inflammation. Together, an autoreactive loop of autoantibody-induced inflammation is formed. Another integral part of immunological memory are long-lived plasma cells. These cells provide persistent humoral antibody memory. Though not all autoantibodies are produced by long-lived plasma cells, these cells have a special impact on immune pathology. Long-lived plasma cells are relatively resistant to existing therapies of immunosuppression and continuously secrete antibodies, without need for restimulation. Long-lived plasma cells provide titers of autoantibodies even during clinically quiescent phases and after immunosuppression. These persisting autoantibody titers, though often low and not causing acute clinical symptoms, are likely to maintain a low level of chronic inflammation and progressive tissue destruction, which reduces the threshold for another break of immunological tolerance.

Perioperative management of medications used in the treatment of rheumatoid arthritis

Patients with rheumatoid arthritis (RA), an inflammatory arthritis that can destroy joint structures, are often on multiple medications to control disease activity. These medications may have significant toxicities and side effects. Over the course of their lifetime, patients with this disease often require orthopedic procedures, including total joint arthroplasty, and the medications they are taking present management issues specific to the perioperative period. As many of these medications are immunosuppressive, the concern for postoperative infection and delayed wound healing are particularly worrisome. We conducted a review of the available literature pertaining to the perioperative use of the most commonly prescribed medications for RA. Although the existing data directly addressing perioperative complications in orthopedic surgery is sparse, information on relevant complications resulting from the general use of these drugs may be used as a basis for conservative recommendations.

Tolerance and efficacy of rituximab and changes in serum B cell biomarkers in patients with systemic complications of primary Sjögren's syndrome

OBJECTIVE

To investigate the safety and efficacy of rituximab (RTX) for systemic symptoms in patients with primary Sjögren's syndrome (pSS), and changes in B cell biomarkers.

PATIENTS AND METHODS

The records of 16 patients with pSS according to the American European consensus group criteria were reviewed retrospectively.

RESULTS

Patients, all women, had a median age of 58.5 (range 41-71) years and a disease duration of 9.5 (range 0-25) years. RTX was prescribed for lymphoma (n = 5), refractory pulmonary disease with polysynovitis (n = 2), severe polysynovitis (n = 2), mixed cryoglobulinaemia (n = 5), thrombocytopenia (n = 1) and mononeuritis multiplex (n = 1). The median follow-up duration was 14.5 (range 2-48) months. Three patients experienced adverse events, including one mild serum sickness-like reaction with the presence of human antichimeric antibodies. Efficacy of treatment was observed in 4 of 5 patients with lymphomas and in 9 of 11 patients with systemic involvement. Dryness was improved in only a minority of patients. Corticosteroid dose was reduced in 11 patients. RTX induced decreased rheumatoid factor, gamma-globulin and beta2-microglobulin levels, and the level of B cell activating factor of the tumour necrosis factor family (BAFF) increased concomitantly with B cell depletion. Five patients were re-treated, with good efficacy and tolerance, except for one with probable serum sickness-like reaction.

CONCLUSION

This study shows good efficacy and fair tolerance of RTX for systemic features. In addition, RTX allows for a marked reduction in corticosteroid use. Except for BAFF, the level of which increases, serum B cell biomarker levels decrease after taking RTX. Controlled trials should be performed to confirm the efficacy of RTX in pSS.

Treatment of refractory polymyositis and dermatomyositis

Polymyositis (PM) and dermatomyositis (DM) are autoimmune inflammatory diseases that primarily target muscle. Although similar, PM and DM have different pathophysiologic mechanisms. Current therapy for PM and DM does not take into account these pathophysiologic differences. Recent work has started to define outcome measures to apply to future therapeutic trials, which will allow better comparison of treatment outcomes. For patients who are unresponsive to standard therapy with high dose prednisone supplemented by methotrexate and/or azathioprine it is not clear what represents the next best choice for therapy. Although there are few controlled studies in the area, there is reason to be optimistic for use of intravenous methylprednisolone pulses, intravenous gammaglobulin, cyclosporine A, tacrolimus, mycophenolate mofetil, and rituximab for nonresponding patients. Better understanding of the underlying pathophysiology of PM and DM, as well as carefully performed multicenter clinical trials is going to be necessary to make better recommendations in the future.

Epratuzumab (humanised anti-CD22 antibody) in autoimmune diseases

B cells play an important role in the pathogenesis of many autoimmune diseases. Different approaches targeting the B cell compartment are under investigation. Selective modulation of B cells has been recently achieved using a humanised monoclonal antibody against the B cell surface marker CD22. This antibody (epratuzumab) was originally developed for the treatment of non-Hodgkin's lymphoma and was found to be effective, with a very good safety profile. Recent studies have demonstrated the efficacy and safety of epratuzumab in several autoimmune diseases, including systemic lupus erythematosus and primary Sjögren's syndrome.

B cells move to centre stage: novel opportunities for autoimmune disease treatment

The B-cell arm of the immune system has long been appreciated for its crucial role in pathogen resistance, but in the study of many autoimmune diseases, T cells have dominated the limelight for decades. However, the development of the B-cell-depleting antibody rituximab as a lymphoma therapy has provided a tool to probe the contribution made by B cells in several immune disorders. Recently, the success of B-cell depletion with rituximab in the treatment of rheumatoid arthritis has stimulated investigation of its effects in several other immune disorders, and considerable interest in the potential of drugs that can modulate B-cell function for the treatment of such diseases in general. This article discusses the role of B cells in a range of autoimmune disorders, including rheumatoid arthritis and systemic lupus erythematosus, and analyses approaches to therapeutic B-cell manipulation.

Follicular dendritic cells are related to bone marrow stromal cell progenitors and to myofibroblasts

Follicular dendritic cells (FDC) are involved in the presentation of native Ags to B cells during the secondary immune response. Some authors consider FDC to be hemopoietic cells, whereas others believe them to be mesenchymal cells. The low proportion of FDC in the lymphoid follicle, together with technical difficulties in their isolation, make these cells difficult to study. We show that Fibroblast Medium can be used successfully to isolate and maintain FDC lines. In this culture medium, we obtained 18 FDC lines from human tonsils, which proliferated for as long as 18 wk and showed a stable Ag phenotype as detected by flow cytometry and RT-PCR. FDC lines were CD45-negative and expressed Ags associated to FDC (CD21, CD23, CD35, CD40, CD73, BAFF, ICAM-1, and VCAM-1) and Ags specific for FDC (DRC-1, CNA.42, and HJ2). These cell lines were also able to bind B cells and secrete CXCL13, functional activities characteristic of FDC. Nevertheless, the additional expression of STRO-1, together with CD10, CD13, CD29, CD34, CD63, CD73, CD90, ICAM-1, VCAM-1, HLA-DR, alkaline phosphatase, and alpha-smooth muscle actin (alpha-SM actin) indicated that FDC are closely related to bone marrow stromal cell progenitors. The expression of alpha-SM actin also relates FDC with myofibroblasts. Like myofibroblasts, FDC lines expressed stress fibers containing alpha-SM actin and were able to contract collagen gels under the effect of TGFbeta1 and platelet-derived growth factor. These findings suggest that FDC are a specialized form of myofibroblast and derive from bone marrow stromal cell progenitors.