Baseline autoantibody profiles predict normalization of complement and anti-dsDNA autoantibody levels following rituximab treatment in systemic lupus erythematosus

CD19 Chimeric Antigen Receptor T Cell Treatment: Unraveling the Role of B Cells in Systemic Lupus Erythematosus

B cell generation of autoantibodies is a crucial step in the pathogenesis of systemic lupus erythematosus (SLE). After their differentiation in the bone marrow, B cells populate the secondary lymphatic organs, where they undergo further maturation leading to the development of memory B cells as well as antibody-producing plasmablasts and plasma cells. Targeting B cells is an important strategy to treat autoimmune diseases such as SLE, in which B cell tolerance is disturbed and autoimmune B cells and autoantibodies emerge. This review discusses the functional aspects of antibody- and cell-based B cell-depleting therapy in SLE. It thereby particularly focuses on lessons learned from chimeric antigen receptor (CAR) T cell treatment on the role of B cells in SLE for understanding B cell pathology in SLE. CAR T cells model a deep B cell depletion and thereby allow understanding the role of aberrant B cell activation in the pathogenesis of SLE. Furthermore, the effects of B cell depletion on autoantibody production can be better described, ie, explaining the concept of different cellular sources of (auto-) antibodies in the form of short-lived plasmablasts and long-lived plasma cells, which differ in their susceptibility to B cell depletion and require different targeted therapeutic approaches. Finally, the safety of deep B cell depletion in autoimmune disease is discussed.

Anti-topoisomerase 1 Antibody Level Changes after B Cell Depletion Therapy in Systemic Sclerosis

The aim of our study was to assess the relationship between the changes of antinuclear autoantibodies (ANAs) and autoantibodies to topoisomerase 1 (anti-Topo 1) in systemic sclerosis (SSs) patients on rituximab (RTX) therapy. The prospective study included 88 patients (73 women) with a mean age of 47 (17-71) years. The mean disease duration was 5.9 ± 4.8 years. The mean follow-up period was more than 2 years (27 (12-42) months). We documented a statistically significant change in skin score, the disease activity index, improvement of pulmonary function and reduction of mean dose of prednisolone after RTX treatment. There was a significant decrease in the number of patients with high levels of ANA and overall decrease of the ANA and anti-Topo 1 levels. A moderate positive statistically significant correlation was found between ANA and anti-Topo 1 (r = 0.403). In the group of patients positive for anti-Topo 1 there were a more pronounced depletion of B lymphocytes, significantly higher increase in forced vital capacity and diffusion capacity, decrease in the disease activity index, compared with patients negative for anti-Topo 1. We observed the decline in the level of ANA and anti-Topo 1 in SSc patients after RTX therapy, and it was correlated by an improvement of the main outcome parameters of the disease. Therefore, anti-Topo 1 positivity could be considered as a predictor of a better response to RTX treatment, especially in SSc patients with hyperproduction of anti-Topo 1.

T Cell Help in the Autoreactive Germinal Center

The germinal center serves as a site of B cell selection and affinity maturation, critical processes for productive adaptive immunity. In autoimmune disease tolerance is broken in the germinal center reaction, leading to production of autoreactive B cells that may propagate disease. Follicular T cells are crucial regulators of this process, providing signals necessary for B cell survival in the germinal center. Here we review the emerging roles of follicular T cells in the autoreactive germinal center. Recent advances in immunological techniques have allowed study of the gene expression profiles and repertoire of follicular T cells at unprecedented resolution. These studies provide insight into the potential role follicular T cells play in preventing or facilitating germinal center loss of tolerance. Improved understanding of the mechanisms of T cell help in autoreactive germinal centers provides novel therapeutic targets for diseases of germinal center dysfunction.

The gene silencing of IRF5 and BLYSS effectively modulates the outcome of experimental lupus nephritis

Systemic lupus erythematosus is a highly complex and heterogeneous autoimmune disease mostly mediated by B cells. It is characterized by circulating self-reactive antibodies that deposit and form immune complexes in kidney, leading to irreparable tissue damage and resulting in lupus nephritis. In a New Zealand Black X New Zealand White F1 mouse model, we tested two different small interfering RNA (siRNA) silencing treatments against interferon regulatory factor 5 (IRF5) and B cell-activating factor (BLYSS) expression and their combination in a second set of animals. The administration of these two siRNAs separately prevented the progression of proteinuria and albuminuria at similar levels to that in cyclophosphamide animals. These treatments effectively resulted in a reduction of serum anti-double-stranded DNA (dsDNA) antibodies and histopathological renal score compared with non-treated group. Treated groups showed macrophage, T cell, and B cell infiltrate reduction in renal tissue. Moreover, kidney gene expression analysis revealed that siRNA treatments modulated very few pathways in contrast to cyclophosphamide, despite showing similar therapeutic effects. Additionally, the combined therapy tested in a second set of animals, in which the disease appeared more virulent, exhibited better results than monotherapies in the disease progression, delaying the disease onset and ameliorating the disease outcome. Herein, we provide the potential therapeutic effect of both selective IRF5 and BLYSS silencing as an effective and potential treatment, particularly in early phases of the disease.

New insights into the role of antinuclear antibodies in systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is a prototypic autoimmune disease characterized by antinuclear antibodies (ANAs) that form immune complexes that mediate pathogenesis by tissue deposition or cytokine induction. Some ANAs bind DNA or associated nucleosome proteins, whereas other ANAs bind protein components of complexes of RNA and RNA-binding proteins (RBPs). Levels of anti-DNA antibodies can fluctuate widely, unlike those of anti-RBP antibodies, which tend to be stable. Because anti-DNA antibody levels can reflect disease activity, repeat testing is common; by contrast, a single anti-RBP antibody determination is thought to suffice for clinical purposes. Experience from clinical trials of novel therapies has provided a new perspective on ANA expression during disease, as many patients with SLE are ANA negative at screening despite previously testing positive. Because trial results suggest that patients who are ANA negative might not respond to certain agents, screening strategies now involve ANA and anti-DNA antibody testing to identify patients with so-called 'active, autoantibody-positive SLE'. Evidence suggests that ANA responses can decrease over time because of the natural history of disease or the effects of therapy. Together, these findings suggest that, during established disease, more regular serological testing could illuminate changes relevant to pathogenesis and disease status.

Are lupus animal models useful for understanding and developing new therapies for human SLE?

Systemic lupus erythematosus is a systemic autoimmune disease driven by a complex combination of genetic, environmental, and other immunoregulatory factors. The development of targeted therapies is complicated by heterogeneous clinical manifestations, varying organ involvement, and toxicity. Despite advances in understanding the mechanisms contributing to SLE, only one biologic drug, belimumab, is FDA-approved. The identification and development of potential therapies have largely been driven by studies in lupus animal models. Therefore, direct comparison of both the therapeutic and immunological findings in human and murine SLE studies is critical and can reveal important insights into indeed how useful and relevant are murine studies in SLE drug development. Studies involving belimumab, mycophenolate mofetil, abatacept, rituximab, and anti-interferon strategies generally demonstrated analogous findings in the attenuation of SLE manifestations and modulation of select immune cell populations in human and murine SLE. While further basic and translational studies are needed to identify SLE patient subsets likely to respond to particular therapeutic modalities and in dissecting complex mechanisms, we believe that despite some inherent weaknesses SLE mouse models will continue to be integral in developing targeted SLE therapies.

Role of anti-DNA auto-antibodies as biomarkers of response to treatment in systemic lupus erythematosus patients: hypes and hopes. Insights and implications from a comprehensive review of the literature

Introduction: Due to the polymorphic clinical presentations and manifestations of systemic lupus erythematosus (SLE), biomarkers with enough diagnostic and prognostic value are of paramount importance. Recently, anti-double stranded DNA (anti-dsDNA) auto-antibodies have been proposed to monitor the response to different therapies. It has also been suggested that they should be employed as entry markers in trial studies. However, their clinical use remains still debated and, sometimes, controversial, due to conflicting findings reported. Areas covered: Through an extensive literature review, we evaluated changes in anti-dsDNA auto-antibodies levels before and after the administration of the treatment (either biological or non-biological). Expert opinion: Anti-dsDNA auto-antibodies related findings are still difficult to compare mainly because of the different detecting methods employed, even though in most studies included in this review a consistent decreasing pattern after the treatment seems to emerge. Hence, if properly standardized, anti-dsDNA auto-antibody profile may be a reliable biomarker to monitor the effectiveness of biologics as well as of non-biological drugs, especially if grouped in composite outcomes scores, such as the 'Lupus Multivariable Outcome Score' (LUMOS) or measured with other biomarkers, such as anti-nucleosome auto-antibodies. We recommend the assessment of anti-dsDNA auto-antibodies levels in both daily practice and research settings.

The long and the short of it: insights into the cellular source of autoantibodies as revealed by B cell depletion therapy

High titers of pathogenic autoantibodies are a hallmark of many autoimmune diseases. However, much remains unknown about the self-reactive plasma cells that are key mediators of disease. We propose a model in which the varying efficacy of precursor B cell depletion for the treatment of humoral autoimmunity can be explained by differences in the relative contributions of pathogenic antibodies by short-lived versus long-lived plasma cells. Beyond therapeutic considerations, this model suggests that we can infer the cellular source of disease-associated autoantibodies by the durability of serum titers following B cell depletion. Data from clinical trials and animal models across different autoimmune diseases may provide useful insights into the lifespan, lifestyle and fate of autoreactive plasma cells.

Efficacy and safety of anti-CD20 antibody rituximab for patients with refractory systemic lupus erythematosus

Objective

We examined the efficacy and safety of rituximab in patients with refractory systemic lupus erythematosus (SLE).

Methods

The study enrolled 63 SLE patients who were treated with rituximab between 2002 and 2015. The participants underwent a battery of tests before treatment and at one year. Treatment ranged from two to four times at 500 or 1000 mg.

Results

Baseline characteristics were males:females = 6:57, age 33.9 years, and disease duration 87.2 months. The primary endpoint: The rate of major clinical response (MCR) was 60% while the partial clinical response (PCR) was 25%. Thirty of 36 (83%) patients with lupus nephritis (WHO II: 2, III: 5, IV: 22, V: 4, IV+V: 2, not assessed: 1) and 22 of 24 patients (92%) with neuropsychiatric SLE, who could be followed at one year, showed changes from BILAG A or B score to C or D score at one year. Multivariate analysis identified high anti-dsDNA antibody and shorter disease duration as significant determinants of MCR at one year. Repeat examination was conducted at five years. Primary failure was recorded in 8.8% and secondary failure in 32.4% (time to relapse: 24.4 months). Rituximab was well tolerated although 65 adverse events, mostly infections, were recorded within one year.

Conclusion

Rituximab is potentially efficacious for the treatment of patients with refractory SLE.

Predictive and prognostic factors influencing outcomes of rituximab therapy in systemic lupus erythematosus (SLE): A systematic review

BACKGROUND

The clinical outcomes following rituximab (RTX) treatment in patients with systemic lupus erythematosus (SLE) is highly variable. We aimed to identify predictive and prognostic factors associated with RTX therapy outcomes in patients with SLE.

METHODS

Studies in adults and paediatric patients with SLE were included. We included randomized clinical trials (RCTs) for predictors of differential treatment effect and cohort studies for potential prognostic factors in patients treated with RTX (global clinical, cutaneous and renal either response or relapse, and side effects). Methodological quality was assessed using Cochrane Collaboration Risk of Bias tool and the Quality In Prognosis Studies Tool (QUIPS) for RCTs and cohort studies, respectively. The quality of subgroup analyses testing predictors of differential treatment response was also evaluated. A best evidence synthesis was performed using the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) framework.

RESULTS

Sixteen articles were included (3 from 2 RCTs and 13 from 6 cohort studies). The overall quality of evidence (QoE) was low to very low (GRADE framework). QoE for predictive factors based on RCTs analysing sociodemographic variables, was rated very low due to the lack of interaction tests, limited power of subgroup analyses, study limitations, and imprecisions. Disease-related factors including clinical phenotype and severity, baseline anti-ENA antibodies and anti-Ro antibodies, interleukin (IL) 2/21 single nucleotide polymorphism (SNP), as well as post-RTX complete B-cell depletion and earlier B-cell repopulation showed some evidence for prognostic value, but were rated low to very low QoE because of early phase of investigation (exploratory analysis), insufficient adjustment for confounding in most studies, high risk of bias, inconsistency, and imprecisions.

CONCLUSIONS

To date, studies addressing prognostic factors are hypothesis generating and cannot be used to make any specific recommendations for routine clinical practice. A number of potential predictors/prognostic factors were identified, which require to be validated as being specific for response to RTX therapy and to enable more personalised use of this agent.

Network Analysis Identifies Proinflammatory Plasma Cell Polarization for Secretion of ISG15 in Human Autoimmunity

Plasma cells (PCs) as effectors of humoral immunity produce Igs to match pathogenic insult. Emerging data suggest more diverse roles exist for PCs as regulators of immune and inflammatory responses via secretion of factors other than Igs. The extent to which such responses are preprogrammed in B-lineage cells or can be induced in PCs by the microenvironment is unknown. In this study, we dissect the impact of IFNs on the regulatory networks of human PCs. We show that core PC programs are unaffected, whereas PCs respond to IFNs with distinctive transcriptional responses. The IFN-stimulated gene 15 (ISG15) system emerges as a major transcriptional output induced in a sustained fashion by IFN-α in PCs and linked both to intracellular conjugation and ISG15 secretion. This leads to the identification of ISG15-secreting plasmablasts/PCs in patients with active systemic lupus erythematosus. Thus, ISG15-secreting PCs represent a distinct proinflammatory PC subset providing an Ig-independent mechanism of PC action in human autoimmunity.

Rituximab usage in systemic lupus erythematosus-associated antiphospholipid syndrome: A single-center experience

OBJECTIVES

Although the data from primary antiphospholipid syndrome (APS) suggests a beneficial effect of rituximab usage, its therapeutic role remains to be defined in systemic lupus erythematosus (SLE)-associated APS, a complex clinical situation with thrombotic events and lupus activity.

METHODS

A single-center retrospective analysis of rituximab usages in APS was performed in 800 hospitalized SLE patients.

RESULTS

There were 63 SLE-associated APS cases with 6 on rituximab therapy, all female aged 37.7 ± 9.0 years with 1 catastrophic and 16 thrombotic episodes. Therapeutic indications included warfarin failure despite the adequate target international normalized ratio with an average duration of 17.3 ± 11.2 months between the thrombotic recurrences. After the rituximab therapy, there was no relapse of thrombosis with a mean follow-up period of 39.3 ± 20.9 months, and a decrease in lupus activity (SLEDAI-2K, 9.7 ± 5.5 to 5.3 ± 2.2). Infection complications were observed, including episodes of bronchitis and urinary tract infection.

CONCLUSIONS

In this single-center study with largest case numbers and a long-term follow-up period, there were no recurrent thrombotic events after the rituximab therapy, implicating further consideration of large-scale trials enrolling more ethnic groups to evaluate its therapeutic role in SLE-associated APS patients.

[Modulating the survival and maturation system of B lymphocytes: Current and future new therapeutic strategies in systemic lupus erythematosus]

Systemic lupus erythematosus is an autoimmune disease associated with an aberrant production of autoantibodies by self-reactive B lymphocytes. The study of the phenotypic characteristics of B lymphocytes and the identification of their surface receptors such as BAFF-R, TACI and BCMA, which are responsible of their survival and maturation, have contributed to the development of new therapeutic strategies in recent years.

Efficacy and safety of rituximab in Japanese patients with systemic lupus erythematosus and lupus nephritis who are refractory to conventional therapy

Objectives. To evaluate the efficacy and safety of rituximab in Japanese patients with systemic lupus erythematosus (SLE) and lupus nephritis (LN) who are refractory to conventional immunosuppressive therapy.

Methods. Eligible patients received rituximab at a dose of 1,000 mg at days 1, 15, 169, and 183, and were followed for 53 weeks after the first dose of rituximab. Overall disease activity was assessed monthly using a British Isles Lupus Assessment Group activity index. Patients with LN (Upr/Ucr ≥ 1.0 at study entry) were identified and their renal responses were evaluated according to the criteria proposed by the American College of Rheumatology (ACR) and the Lupus Nephritis Assessment with Rituximab (LUNAR) study.

Results. A total of 34 patients were enrolled and received at least one dose of rituximab. Decrease in disease activity was achieved in 16 (76.5%) out of 34 patients. In 17 patients with LN, response rates of 58.8% and 52.9% by ACR and LUNAR criteria, respectively, were seen. Successful steroid tapering was achieved in association with disease remission. Rituximab was well tolerated, and most adverse drug reactions were grade 1–2 in severity.

Conclusions. Rituximab is effective for treatment of Japanese patients with SLE and LN refractory to conventional therapy.

Efficacy and Safety of Rituximab in Systemic Lupus Erythematosus and Sjögren Syndrome Patients With Refractory Thrombocytopenia: A Retrospective Study of 21 Cases

OBJECTIVE

Recent studies suggested a potential of rituximab (RTX) in treating autoimmune thrombocytopenia (AITP) secondary to autoimmune diseases. In this study, we retrospectively evaluated the efficacy and safety of RTX therapy in patients with refractory AITP secondary to systemic lupus erythematosus (SLE) and Sjögren syndrome (SS).

METHODS

Twenty-one SLE and/or SS patients with treatment-resistant AITP were treated once or repeatedly with RTX at the Rheumatology Clinic Renji Hospital, during the period March 2012 to June 2014. Clinical and laboratory variables recorded at every follow-up visit were analyzed.

RESULTS

The median age of all patients was 37.05 ± 3.15 years (range, 13-67 years; 20 female and 1 male). The median AITP duration before RTX treatment was 5.46 years. Previous treatments of 21 patients included immunosuppressive agents such as corticosteroids (n = 19), cyclosporine (n = 9), mycophenolate mofetil (n = 2), methotrexate (n = 3), cyclophosphamide (n = 2), vincristine (n = 3), and hydroxychloroquine (n = 15), and 7 patients received concomitantly intravenous immunoglobulin therapy. Two patients had undergone splenectomy without improvement. Seventeen patients (80.95%) were treated repeatedly with RTX during the follow-up period. The overall response rate to RTX treatment (including complete response, 52.38%; partial response, 28.57%) was 80.95%. A significant increase (P < 0.05) of platelet counts was seen after 1 month (median, 32.24 × 10/mL vs 66.53 × 10/mL). Relapses occurred mostly during the first 9 months, and maintaining duration of response was 10.27 months (range, 2-17 months) on average after the first RTX infusion. Antiplatelet antibodies, especially IgG isotype, decreased significantly (P < 0.05) after RTX treatment. No adverse effects were observed among 15 patients (71.4%); however, 2 cases died of severe pneumonia, and another developed lymphoma.

CONCLUSIONS

Rituximab is an additional potent therapeutic treatment option for SLE and SS patients with AITP refractory to conventional immunosuppressive treatments. For most patients, RTX was safe and well tolerated.

[Biologics therapy for systemic lupus erythematosus. Current situation]

BACKGROUND

Improved understanding of the immunopathogenesis of systemic lupus erythematosus (SLE) has paved the way for new specific immune interventions for this inflammatory disease similar to those for rheumatoid arthritis and spondylarthritides.

METHODS

New biologics were developed on this basis or are in the process of clinical development and open up new therapy options for patients. In this context belimumab is of particular importance. As an innovative biologic the monoclonal antibody against the cytokine BAFF/BLyS (belimumab) has been approved for the treatment of serologically active SLE. A number of other biologics against other cytokines are in the clinical development phase and appear to be promising for further improvement of the current therapeutic possibilities in SLE. This article addresses the current aspects of immune interventions with biologics for SLE and the specific challenges of this disease.

Systemic lupus erythematosus and other autoimmune rheumatic diseases: challenges to treatment

Increased understanding of the molecular mechanisms underlying the pathogenenesis of autoimmune rheumatic diseases has led to targeted biological treatments that modulate various aspects of the immune response. These new treatments, together with more judicious use of other immunosuppressive drugs, have resulted in marked improvements in morbidity and mortality. Although belimumab, an agent that inhibits B-cell survival, is the first drug to be approved by the US Food and Drug Administration for the treatment of systemic lupus erythematosus in 50 years, many other immunological targets are under investigation. We discuss the recent advances in the biological treatment of autoimmune rheumatic diseases, with a particular focus on systemic lupus erythematosus.

Anti B-cell therapy against refractory thrombocytopenia in SLE and MCTD patients: long-term follow-up and review of the literature

OBJECTIVE

The objective of this study was to retrospectively evaluate the clinical and immunological effects of anti-B cell treatment in patients with systemic lupus erythematosus (SLE) and mixed connective-tissue disease (MCTD) with autoimmune thrombocytopenia (AITP) refractory to conventional immunosuppressive treatment.

METHODS

Rituximab (RTX) was added to the ongoing treatment of 16 patients (median age 36 years, range 17-84, all female) with treatment-resistant AITP. Thirteen patients had SLE and three had MCTD. RTX was given intravenously on four occasions during four consecutive weeks at a dose of 375 mg/m(2). Clinical and laboratory disease activity variables recorded at every follow-up visit were analyzed.

RESULTS

The median disease duration before RTX treatment was nine years (range 0.2-27) and the median post-treatment follow-up time was 28 months (range 3 to 92). Ten patients (63%) were treated repeatedly with RTX during the follow-up period. Complete depletion of B cells was achieved in 94% of cases one month after RTX treatment. A significant increase (p = 0.0001) of platelet counts was seen already after one month (median 58 × 10(9)/ml vs 110 × 10(9)/ml) whereas within three months platelet counts normalized in 10 patients (median 223 × 10(9)/ml). Three patients did not respond to RTX treatment (median platelet count 69 × 10(9)/ml). High titers of anti-platelet antibodies were detected in seven patients before RTX treatment, and the autoantibody titers decreased significantly (p < 0.03) after RTX treatment in six of these patients who also achieved complete remission. A review of the literature revealed 24 articles including 18 case reports, one retrospective cohort study and five prospective studies documenting the outcomes of 65 RTX-treated patients with SLE- or MCTD-related thrombocytopenia with an overall treatment response rate of 80%. In conclusion, these findings indicate that RTX is an additional potent therapeutic treatment option for SLE patients with AITP refractory to conventional immunosuppressive treatment whereas best response may be expected in patients with high titers of anti-platelet antibodies at baseline.

Biologic therapy for autoimmune diseases: an update

Biologic therapies for rheumatologic diseases, which are targeted at molecules involved in the mechanisms of the immune system, provide an alternative to the existing treatment methods of disease-modifying anti-rheumatic drugs and other immunosuppressive medications. However, the current drawbacks of biologic therapies, including the inconvenience of intravenous administration, the high costs of these drugs, and the adverse events associated with them, prevent their wide use as first-line medications. This review provides an update of the recent literature on the new biologic therapies available. The review concentrates on nine drugs: tocilizumab, rituximab, ofatumumab, belimumab, epratuzumab, abatacept, golimumab, certolizumab, and sifalimumab, which are used as therapies for rheumatoid arthritis, spondyloarthritis, systemic lupus erythematosus, systemic sclerosis, or vasculitis.

B-cell depletion in SLE: clinical and trial experience with rituximab and ocrelizumab and implications for study design

B cells are believed to be central to the disease process in systemic lupus erythematosus (SLE), making them a target for new therapeutic intervention. In recent years there have been many publications regarding the experience in SLE of B-cell depletion utilising rituximab, an anti-CD20 mAb that temporarily depletes B cells,reporting promising results in uncontrolled open studies and in routine clinical use. However, the two large randomised controlled trials in extra-renal lupus (EXPLORER study) and lupus nephritis (LUNAR study) failed to achieve their primary endpoints. Based on the clinical experience with rituximab this failure was somewhat unexpected and raised a number of questions and concerns, not only into the true level of benefit of B-cell depletion in a broad population but also how to test the true level of effectiveness of an investigational agent as we seek to improve the design of therapeutic trials in SLE. A better understanding of what went wrong in these trials is essential to elucidate the underlying reasons for the disparate observations noted in open studies and controlled trials. In this review, we focus on various factors that may affect the ability to accurately and confidently establish the level of treatment effect of the investigational agent, in this case rituximab, in the tw studies and explore hurdles faced in the randomised controlled trials investigating the efficacy of ocrelizumab, the humanised anti-CD20 mAb, in SLE. Further, based on the lessons learned from the clinical trials, we make suggestions that could be implemented in future clinical trial design to overcome the hurdles faced.

Homozygous FCGR3A-158F mutation is associated with delayed B-cell depletion following rituximab but with preserved efficacy in a patient with refractory lupus nephritis

Rituximab (RTX), an anti-CD20 monoclonal antibody, has shown promising results in a small group of systemic lupus erythematosus (SLE) patients treated for lupus nephritis (LN). However, such observations were not confirmed in the double-blind LUNAR study. Accordingly, the factors associated with the clinical response remain to be characterized. We report the case of a young woman with known LN successfully re-treated with RTX and steroids and homozygous for the low-affinity FCG3RA 158F genotype. Although B-cell depletion was delayed, complete remission with anti-DNA antibody negativity and proteinuria normalization were maintained for 5 years. The implications for disease pathogenesis and clinical monitoring are discussed.

Translational Mini-Review Series on B cell subsets in disease. Transitional B cells in systemic lupus erythematosus and Sjögren's syndrome: clinical implications and effects of B cell-targeted therapies

Systemic lupus erythematosus (SLE) and Sjögren's syndrome are autoimmune disorders which are characterized by a disturbed B cell homeostasis which leads ultimately to dysfunction of various organs. One of the B cell subsets that appear in abnormal numbers is the population of transitional B cells, which is increased in the blood of patients with SLE and Sjögren's syndrome. Transitional B cells are newly formed B cells. In mice, transitional B cells undergo selection checks for unwanted specificity in the bone marrow and the spleen in order to eliminate autoreactive B cells from the circulating naive B cell population. In humans, the exact anatomical compartments and mechanisms of the specificity check-points for transitional B cells remain unclear, but appear to be defective in SLE and Sjögren's syndrome. This review aims to highlight the current understanding of transitional B cells and their defects in the two disorders before and after B cell-targeted therapies.

Are autoantibodies the targets of B-cell-directed therapy?

B-cell-directed therapy-the use of agents that eliminate B cells or block cytokines important for B-cell function-is emerging as a promising approach to the treatment of rheumatic disease. Target diseases, including systemic lupus erythematosus (SLE), display diverse patterns of autoantibody production and aberrant activation of B cells. Despite the success of this general approach, the mechanisms by which B-cell-directed therapy ameliorates disease, and the role of autoantibodies as biomarkers of clinical response remain unclear. Importantly, although B-cell-directed therapy can reduce the production of some autoantibodies, the effects can be variable and heterogeneous, probably reflecting the critical (but ill-defined) roles of different B-cell and plasma cell populations in autoantibody production. Future studies during clinical trials of these agents are needed to define which B-cell and autoantibody populations are affected (or ought to be), and to discover informative biomarkers of clinical response that can be used to advance this therapeutic approach.

Normalization of serum-free light chains in patients with systemic lupus erythematosus upon rituximab treatment and correlation with biological disease activity

Increased free light chain (FLC) levels have been reported as useful in various autoimmune conditions. We investigated how FLC concentrations change upon B cell targeted therapy in systemic lupus erythematosus (SLE) patients and if they correlate with disease activity. We retrospectively studied 11 SLE patients without renal failure, whom were treated with rituximab. Quantitative determination of IgG, IgA, IgM, and serum FLC was performed before and after rituximab. At baseline, 70% had abnormal serum FLC levels, including increased kappa and lambda levels, while the kappa/lambda ratio was normal for all. A strong correlation was observed between complement C3 fraction and kappa levels (r = -0.929, P < 0.001) or lambda levels (r = -0.854, P = 0.003), but not with IgG, IgA, or IgM levels. After rituximab treatment, kappa and lambda FLC concentrations decreased significantly whilst total concentrations of IgG, IgA, and IgM also decreased but remained within the normal range. There was a strong correlation only between kappa FLC levels and complement C3 fraction consumption (r = -0.543, P = 0.003). In SLE patients without renal failure, increased FLC levels (mainly kappa) with normal kappa/lambda ratios are a common feature, and in contrast to total IgG levels, FLC concentrations correlate with biological disease activity.

B cell immunotherapy in autoimmunity--2010 update

B cells play important roles in normal immunity and human disease. While much has been learned from elegant studies utilizing genetically modified mice or with immunotherapy in normal and in autoimmune mice, we are merely at the start of learning about the mechanism(s) by which B cells contribute to human autoimmune disease. Here, I will review the most recent insights obtained with immunomodulatory therapies in human disease highlighting the clinical and immunological lessons we have learned with B cell depleting (e.g., rituximab) and immunomodulatory (e.g., BAFF/BLys neutralization through belimumab) therapies.

Contemporary treatment of systemic lupus erythematosus: an update for clinicians

The prognosis for patients with systemic lupus erythematosus (SLE) has improved significantly, with 20-year survival now approximately 80% owing partly to effective treatment. SLE treatment has evolved from the use of conventional drugs such as hydroxychloroquine and corticosteroids, nonspecific immunosuppressants including mycophenolate mofetil, to targeting selective components of the immune cascade with a view to increased efficacy, tolerability and safety profile. These novel treatments include B-cell-depleting antibodies and fusion proteins that block the costimulatory pathways of B and T cells. A discussion of these pharmacological options and ongoing research forms the basis of this review.