Reconstitution of the adult B cell repertoire after treatment with rituximab

[Enteroviral infections in adults treated with rituximab: A new case of chronic meningitis and myofasciitis and literature review]

INTRODUCTION

Chronic enterovirus infections can occur in primary immunodeficiency with hypogammaglobulinemia. They usually associate meningitis and myofasciitis. Such infections have also been described in adults with rituximab-induced hypogammaglobulinemia.

CASE REPORT

We report the case of a 33-year-old woman who was given rituximab for immune thrombocytopenia and developed rituximab-induced hypogammaglobulinemia (IgG 4.4g/L). One year after the last rituximab infusion, she developed lower limbs myofasciitis, followed two months later by a chronic lymphocytic meningitis. PCR in the serum and the cerebrospinal fluid at the time of the meningitis and the myofasciitis were positive to the same enterovirus (echovirus 11) while it was negative in the fascia biopsy. Under treatment with intravenous immunoglobulins, all symptoms and laboratory abnormalities improved and enterovirus PCR became negative.

CONCLUSION

We report a case of chronic enterovirus infection associating meningitis and myofasciitis in an adult with rituximab-induced hypogammaglobulinemia. Outcome was favorable under treatment with intravenous immunoglobulins.

Review on the Influence of Protocol Design on Clinical Outcomes in Rheumatoid Arthritis Treated with Rituximab

OBJECTIVE

To critically analyze the influence of protocol design on clinical outcome in patients with rheumatoid arthritis (RA) treated with rituximab.

DATA SOURCES

A PubMed and EMBASE search (January 2000-January 2012) using the key words rheumatoid arthritis and rituximab was performed.

STUDY SELECTION AND DATA EXTRACTION

A search of English-language studies from the data sources was conducted for randomized, double-blind, placebo-controlled studies with 100 patients or more assessing the efficacy and safety of rituximab in the treatment of RA. From these studies, 2 authors independently extracted, compiled, and aggregated the data.

DATA SYNTHESIS

Eight studies met the inclusion criteria. In these studies, some patients had not been treated with tumor necrosis factor-alfa (TNF-α) inhibitors, while most did not respond to it. The variables compared included dose (500 vs 1000 mg), duration of study (24 vs 48 weeks), and number of cycles (1 vs 2). They were statistically analyzed using the χ2 test. There was a statistically significant difference in the response to rituximab compared to the control (methotrexate) (p < 0.001). In patients who were studied for only 24 weeks, given 500 or 1000 mg for 1 or 2 cycles, a 90% or greater response rate was reported in those who achieved an ACR 20, but no statistically significant differences were observed (p = 0.75). In patients studied for 48 weeks who received 2 cycles of either 500 mg or 1000 mg of rituximab and achieved an ACR 20, a statistically significant difference (p < 0.001) was observed in those who received a dose of 1000 mg for 2 cycles (42.77% vs 67.49%).

CONCLUSIONS

In patients who are nonresponsive to disease-modifying antirheumatic drugs and TNF-α inhibitors, rituximab may be a promising and well-tolerated biologic agent. The capacity of rituximab to produce long-term, sustained remissions could not be evaluated because the duration of the studies was limited to 24 weeks or 48 weeks. Studies with longer periods of observation are warranted.

Analysis of B cell subsets following pancreatic islet cell transplantation in a patient with type 1 diabetes by cytometric fingerprinting

Manual gating of bivariate plots remains the most frequently used data analysis method in flow cytometry. However, gating is operator-dependent and cumbersome, particularly with the increasing complexity of modern multicolor immunophenotyping data. A method that can remove operator bias, enable systematic and thorough analysis of complex high-dimensional data, correlate temporal changes in different subsets and lead to biomarker discovery is needed. Here we apply such a method, called cytometric fingerprinting (CF), to data obtained on peripheral blood B cells from an adult patient with type-1 diabetes who underwent pancreatic islet transplantation. We establish that CF can be used to analyze longitudinal trends in immunophenotypic data, and show that results from CF are comparable to those obtained with traditional gating methods. Both methods reveal the appearance of transitional B cells and subsequent accumulation of more mature B cells following immunosuppression and transplantation. This pattern is consistent with a temporally ordered process of B cell auto-reconstitution. We also show the comparative efficiency of fingerprinting in recognizing relative changes in B cell subsets with respect to time, its ability to couple the data with statistical methods (agglomerative clustering) and its potential to define novel subsets.

Systems biology of lupus: mapping the impact of genomic and environmental factors on gene expression signatures, cellular signaling, metabolic pathways, hormonal and cytokine imbalance, and selecting targets for treatment

Systemic lupus erythematosus (SLE) is characterized by the dysfunction of T cells, B cells, and dendritic cells, the release of pro-inflammatory nuclear materials from necrotic cells, and the formation of antinuclear antibodies (ANA) and immune complexes of ANA with DNA, RNA, and nuclear proteins. Activation of the mammalian target of rapamycin (mTOR) has recently emerged as a key factor in abnormal activation of T and B cells in SLE. In T cells, increased production of nitric oxide and mitochondrial hyperpolarization (MHP) were identified as metabolic checkpoints upstream of mTOR activation. mTOR controls the expression T-cell receptor-associated signaling proteins CD4 and CD3zeta through increased expression of the endosome recycling regulator Rab5 and HRES-1/Rab4 genes, enhances Ca2+ fluxing and skews the expression of tyrosine kinases both in T and B cells, and blocks the expression of Foxp3 and the generation of regulatory T cells. MHP, increased activity of mTOR, Rab GTPases, and Syk kinases, and enhanced Ca2+ flux have emerged as common T and B cell biomarkers and targets for treatment in SLE.

Modulation of molecular imprints in the antigen-experienced B cell repertoire by rituximab

OBJECTIVE

Transient B cell depletion by rituximab has recently gained more importance in the treatment of rheumatic disorders. Nevertheless, little is known about the reemerging B cells. We analyzed dynamic changes in the repopulating B cells, particularly the postswitch B cells, and studied the mutational patterns of Ig genes in antigen-experienced B cells.

METHODS

Five patients with active rheumatoid arthritis (RA) were treated with rituximab. In 3 patients, B cell receptor (BCR) gene analysis was performed before treatment and during B cell recovery using genomic DNA. In 2 patients, B cell subsets were studied during the early recovery phase using single-cell technology. For comparison, immunophenotyping of B cell subsets was performed.

RESULTS

Early B cell recovery was marked by a relatively expanded population of highly mutated B cells, which were correlated with B cells with a plasmablast phenotype on comparative immunophenotyping. Analysis of the mutational pattern in these cells revealed increased RGYW/WRCY (where R = A/G, Y = C/T, and W = A/T) hotspot targeting (44% before rituximab versus 59% after) and elevated ratios of replacement to silent mutations within the complementarity-determining regions in Ig genes (1.87 before rituximab versus 2.67 after; P < or = 0.0025).

CONCLUSION

Our findings show that rituximab leads to qualitative changes in the imprints of highly mutated, antigen-experienced BCRs, representing the result of selection, whereas molecular processes such as Ig V rearrangements are not affected by this treatment.

A longitudinal analysis of SLE patients treated with rituximab (anti-CD20): factors associated with B lymphocyte recovery

Identifying factors associated with B lymphocyte depletion and recovery may aid the development of individualized treatment regimens, optimizing therapy for patients with autoimmune disease. In this study, 12 patients with active SLE were monitored at baseline and monthly following treatment with rituximab. The number and phenotype of peripheral blood B lymphocytes, T lymphocytes and natural killer cells were correlated with the extent and longevity of B lymphocyte depletion. This analysis generated three candidate biomarkers for lymphocyte monitoring in patients with autoimmune disease who are treated with rituximab: circulating transitional B cells, the kappa:lambda ratio and natural killer cells. Further refinement of these potential biomarkers may lead to a better understanding of the role of B cells in disease pathogenesis and a more rational use of B cell depletion therapies.

Targeted biologic approaches to the treatment of systemic vasculitis

The introduction of biological agents in the treatment of systemic vasculitis offers the promise of targeted therapy with greater efficacy and fewer side effects than conventional treatments. In this paper, we review the rationale for biological strategies in vasculitis and discuss the results of clinical studies to date. The biotherapies discussed include immune-cell-depleting agents, both B- and T-cell targeted; costimulatory blockade; and cytokine blockade. Although most of these agents remain unproven until ongoing randomized clinical trials are complete, their introduction heralds a new era of vasculitis treatment and has provided novel insights into disease pathogenesis.

B cell modulation in rheumatology

While evidence of dysregulation of the B cell compartment was first demonstrated with the identification of autoantibodies, other functional roles of B lymphocytes in autoimmune pathogenesis have generally been underappreciated or completely overlooked. With the recent approval of the first B cell targeting agent in rheumatoid arthritis, new strategies are being developed to target B cells through a range of membrane-associated lineage-specific molecules and also by interfering with B-cell-specific pro-survival signals. B-cell-directed agents therefore provide an effective new mechanistic approach to treatment and also enable new perspectives from the dissection of the contributions of B cells in physiologic and pathologic immune responses.

A multicenter phase I/II trial of rituximab for refractory systemic lupus erythematosus

Although corticosteroids and immunosuppressants are widely used for the treatments of systemic lupus erythematosus (SLE), safer and more effective therapies are prerequisite. We and others have reported that anti-CD20 antibody rituximab targeting B cells are effective for refractory SLE and, therefore, safety and clinical efficacy of rituximab in SLE was evaluated by a multicenter phase I/II clinical trial. An open-label, multicenter study of 15 patients with active and refractory SLE (total British Isles Lupus Assessment Group [BILAG] score 8 to 17) was conducted. Rituximab was administered to 5 SLE patients as 4 infusions of 500 mg/body every week and to 10 SLE patients as 2 infusions of 1000 mg/body every other week. Assessment of safety, infusion reactions and adverse effects was used as the primary outcome for clinical tolerability and was evaluated by 28 weeks. Rituximab was well tolerated, with most experiencing no significant adverse effects. B cells rapidly reduced in all patients and remained low until 6 months post-treatment. Four patients developed human antichimeric antibodies without affecting efficacy of rituximab. Changes in routine safety laboratory tests clearly related to rituximab were not observed. Nine among 14 evaluable patients achieved the major or partial clinical response of BILAG score and prednisolone dose significantly decreased at the 28 weeks. Rituximab therapy appears to be safe for the treatment of active SLE patients and holds significant therapeutic promise, at least for the majority of patients experiencing profound B-cell depletion.

BAFF-modulated repopulation of B lymphocytes in the blood and salivary glands of rituximab-treated patients with Sjögren's syndrome

OBJECTIVE

Treatment with rituximab depletes B cells from the peripheral blood (PB) and salivary glands (SGs) of patients with primary Sjögren's syndrome (SS). The purpose of this study was to track the repopulation of B cell subsets in PB as well as their subsequent homing into SGs in patients with primary SS treated with rituximab.

METHODS

A series of 4-color flow cytometry experiments delineated B cell subsets in 15 patients with primary SS. All were tested on days 8 and 15 of treatment. Nine of the patients were followed up monthly for 10 months, and the remaining 6 patients were followed up monthly for 24 months. Enzyme-linked immunosorbent assays were developed to measure serum levels of BAFF and rituximab. SGs were biopsied at the start of the study and 4 months after treatment in 15 patients, 12 months after treatment in 3 patients, and 24 months after treatment in 2 patients.

RESULTS

Baseline serum levels of BAFF correlated inversely (r = -0.92, P < 5 x 10(-4)) with the duration of B cell depletion: the higher the BAFF levels, the shorter the duration of B cell depletion. Four B cell subsets repopulated the PB: plasmablasts (CD19+, CD5-,IgD-,CD38++), transitional type 1 (T1) B cells (CD19+,CD5+,IgD+,CD38++), mature Bm2 cells (CD19+,CD5+/-,IgD+,CD38+/-), and memory B cells (CD19+,CD5-,IgD-,CD38-). Increased numbers of Bm2 cells and decreased memory B cells reappeared with time. Sequential SG biopsies revealed that B cells were absent in these glands for 12 months: they were detected 24 months after rituximab treatment. Memory and T1 B cells were the first B cells identified locally.

CONCLUSION

The timing of B cell repopulation is modulated by BAFF and is followed by reconstitution of the preexisting abnormalities.