Differential B- and T-cell activation in Wegener's granulomatosis

Study protocol for a randomised, phase II, double-blind, experimental medicine study of obinutuzumab versus rituximab in ANCA-associated vasculitis: ObiVas

INTRODUCTION

Relapses in ANCA-associated vasculitis (AAV) increase the incidence of end-organ damage and their prevention requires prolonged immunosuppressive therapy. Rituximab, a type I anti-CD20 B cell depleting monoclonal antibody, is the current standard of care for induction of disease remission. Rituximab is not always effective and is associated with a high subsequent relapse risk. Obinutuzumab is a type II anti-CD20 humanised monoclonal antibody with the potential to obtain greater tissue B cell depletion than rituximab and reduce relapse risk in AAV.

METHODS AND ANALYSIS

ObiVas is a randomised, phase II, double-blind controlled trial that will compare the mechanistic effects of rituximab and obinutuzumab in the induction treatment of patients with AAV positive for proteinase 3 ANCA (PR3-ANCA). 26 patients, either newly diagnosed or relapsing, will be recruited from a single centre and randomised in a 1:1 ratio to receive 1000 mg rituximab or obinutuzumab as induction therapy on days 1 and 15, alongside a tapering glucocorticoid regimen. The primary end point is CD19+ B cell depletion in nasal-associated lymphoid tissue (NALT), assessed as change from baseline to week 26. Secondary outcomes will compare the safety and clinical efficacy of rituximab and obinutuzumab and their impact on immune biomarkers, including tissue and peripheral blood lymphocyte subsets and PR3-ANCA binding levels. Patients are followed through to week 78. The trial opened for recruitment in January 2023 and is forecasted to complete recruitment by the end of 2024.

ETHICS AND DISSEMINATION

For all patients, informed written consent will be obtained in keeping with Good Clinical Practice. Trial results will be disseminated to the relevant scientific, clinical and patient communities on trial closure. NALT data analysis will start before trial completion. Other analyses will be reported after trial completion. This trial was given ethical approval by Edgbaston (West Midlands) Research Ethics Committee (approval reference 22/WM/0174).

TRIAL REGISTRATION NUMBER

ISRCTN13069630.

Treatment strategies for ANCA-associated vasculitides: from standard protocols to future horizons

INTRODUCTION

ANCA-associated vasculitides (AAV), classified into granulomatosis with polyangiitis, microscopic polyangiitis, and eosinophilic granulomatosis with polyangiitis represent a group of disorders characterized by necrotizing vasculitis of small vessels, endothelial injury and tissue damage. The outcomes and prognosis of AAV have undergone significant changes with the introduction of glucocorticoids (GCs) and other immunosuppressants (cyclophosphamide, azathioprine, methotrexate, and mycophenolate mofetil). The enhanced understanding of pathogenesis has subsequently led to the incorporation into clinical practice of drugs targeting specific therapeutic targets.

AREAS COVERED

After an extensive literature search of Pubmed, Medline, Embase of the most recent evidence, we provide an overview of available treatments, highlighting how newer drugs have integrated into standard protocols. Our review also explores potential new therapeutic targets, including B cell depletion and inhibition, T cell inhibition, complement inhibition, and IL-5 and IgE inhibition.

EXPERT OPINION

There is hope that the new treatment targets currently under study in AAV may enable a faster and more lasting clinical response, ensuring the reduction of possible side effects from therapies. Moreover, numerous aspects necessitate further exploration in the future, such as tailoring of GCs, integration of GCs-sparing agents, efficacy of combination therapy, optimal maintenance therapy, to reduce organ-damage and improve quality of life.

Longitudinal monitoring of circulating immune cell phenotypes in anti-neutrophil cytoplasmic antibody-associated vasculitis

Anti-neutrophil cytoplasmic antibody-associated vasculitis (AAV) is a necrotizing multiorgan autoimmune disease that affects small- to medium-sized blood vessels. Despite the improvements in treatments, half of the patients with AAV still experience disease relapses. In this review, we focus on peripheral leukocyte properties and phenotypes in patients with AAV. In particular, we explore longitudinal changes in circulating immune cell phenotypes during the active phase of the disease and treatment. The numbers and phenotypes of leukocytes in peripheral blood were differs between AAV and healthy controls, AAV in active versus inactive phase, AAV in treatment responders versus non-responders, and AAV with and without severe infection. Therefore, biomarkers detected in peripheral blood immune cells may be useful for longitudinal monitoring of disease activity in AAV.

Rituximab pediatric drug development: Pharmacokinetic and pharmacodynamic modeling to inform regulatory approval for rituximab treatment in patients with granulomatosis with polyangiitis or microscopic polyangiitis

Anti-neutrophil cytoplasmic antibody-associated vasculitides granulomatosis with polyangiitis (GPA) and microscopic polyangiitis (MPA) are rare, potentially organ- and life-threatening autoimmune conditions affecting adult and pediatric patients. An open-label phase II study was conducted to determine safe and effective dosing regimens of rituximab in pediatric patients with GPA/MPA. To determine the selection of an appropriate dose regimen in children for induction and maintenance, a population pharmacokinetic approach was used (nonlinear mixed-effect modeling), combining pediatric data with data from adults with GPA/MPA. The time course of B-cell depletion was assessed in both populations. The exposure-effect relationship was assessed by logistic regression. Twenty-five pediatric patients (80% female patients; age range, 6-17 years) were enrolled in the trial and received the induction regimen of intravenous rituximab 375 mg/m² weekly for 4 weeks, which resulted in a similar exposure to that of adults. Based on pharmacokinetic modeling, a maintenance dosing regimen of 250 mg/m² administered twice over 14 days followed by 250 mg/m² every 6 months is expected to result in similar rituximab exposure as that of adults receiving the approved maintenance dose of 500 mg administered twice over 14 days followed by 500 mg every 6 months. The time course of B-cell depletion was similar between the pediatric and adult populations, supporting the similarities in response in both populations and allowing extrapolation to patients less than 6 years old. Using a partial extrapolation approach helped identify safe and effective dosing regimens of rituximab in pediatric patients with GPA/MPA and lead to regulatory approval.

Phase IIa Global Study Evaluating Rituximab for the Treatment of Pediatric Patients With Granulomatosis With Polyangiitis or Microscopic Polyangiitis

OBJECTIVE

To assess the safety, tolerability, pharmacokinetics, and efficacy of rituximab (RTX) in pediatric patients with granulomatosis with polyangiitis (GPA) or microscopic polyangiitis (MPA).

METHODS

The Pediatric Polyangiitis Rituximab Study was a phase IIa, international, open-label, single-arm study. During the initial 6-month remission-induction phase, patients received intravenous infusions of RTX (375 mg/m2 body surface area) and glucocorticoids once per week for 4 weeks. During the follow-up period, patients could receive further treatment, including RTX, for GPA or MPA. The safety, pharmacokinetics, pharmacodynamics, and exploratory efficacy outcomes with RTX were evaluated.

RESULTS

Twenty-five pediatric patients with new-onset or relapsing disease were enrolled at 11 centers (19 with GPA [76%] and 6 with MPA [24%]). The median age was 14 years (range 6-17 years). All patients completed the remission-induction phase. During the overall study period (≤4.5 years), patients received between 4 and 28 infusions of RTX. All patients experienced ≥1 adverse event (AE), mostly grade 1 or grade 2 primarily infusion-related reactions. Seven patients experienced 10 serious AEs, and 17 patients experienced 31 infection-related AEs. No deaths were reported. RTX clearance correlated with body surface area. The body surface area-adjusted RTX dosing regimen resulted in similar exposure in both pediatric and adult patients with GPA or MPA. Remission, according to the Pediatric Vasculitis Activity Score, was achieved in 56%, 92%, and 100% of patients by months 6, 12, and 18, respectively.

CONCLUSION

In pediatric patients with GPA or MPA, RTX is well tolerated and effective, with an overall safety profile comparable to that observed in adult patients with GPA or MPA who receive treatment with RTX. RTX is associated with a positive risk/benefit profile in pediatric patients with active GPA or MPA.

Novel Targets for Drug Use in Eosinophilic Granulomatosis With Polyangiitis

Eosinophilic Granulomatosis with Polyangiitis (EGPA) is a rare autoimmune disease characterized by medium and small vessels inflammation. Cardiac vasculitic involvement is one of the most severe manifestations with a significant impact on patients' long-term prognosis: anyway, a specific therapeutic approach for heart involvement in EGPA has not been explored yet. Current regimen consists of a long-term therapy with high dose of glucocorticoids, causing the well-known related-adverse events; immunosuppressive drugs are used in patients with severe manifestations, with some limitations. New therapeutic approaches are needed for patients with refractory disease or contraindications to conventional therapies. The quest for the ideal therapy is going toward a more and more personalized approach: on the one hand, efforts are made to use already existing therapies in the most appropriate way; on the other hand, new insights into EGPA pathogenesis allow the discovery of new targets, as demonstrated by mepolizumab and rituximab, targeting eosinophils, and B-cell compartments. This review summarizes the emerging therapies used in EGPA, focusing on the most recent studies on biologics and analyzing their efficacy and safety.

The Emerging Role of B Lymphocytes in Cardiovascular Disease

B cells are traditionally known for their ability to produce antibodies in the context of adaptive immune responses. However, over the last decade B cells have been increasingly recognized as modulators of both adaptive and innate immune responses, as well as players in an important role in the pathogenesis of a variety of human diseases. Here, after briefly summarizing our current understanding of B cell biology, we present a systematic review of the literature from both animal models and human studies that highlight the important role that B lymphocytes play in cardiac and vascular disease. While many aspects of B cell biology in the vasculature and, to an even greater extent, in the heart remain unclear, B cells are emerging as key regulators of cardiovascular adaptation to injury.

ANCA-Associated Vasculitis: An Update

Anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) represents a group of small vessel vasculitides characterized by granulomatous and neutrophilic tissue inflammation, often associated with the production of antibodies that target neutrophil antigens. The two major antigens targeted by ANCAs are leukocyte proteinase 3 (PR3) and myeloperoxidase (MPO). AAV can be classified into 3 categories based on patterns of clinical involvement: namely, granulomatosis with polyangiitis (GPA), microscopic polyangiitis (MPA) and eosinophilic GPA (EGPA). Clinically, AAV involves many organ systems including the lungs, kidneys, skin, and nervous system. The prognosis of AAV has improved dramatically due to advances in the understanding of its pathogenesis and treatment modalities. This review will highlight some of the recent updates in our understanding of the pathogenesis, clinical manifestations, and treatment options in patients with AAV focusing on kidney involvement.

Pathogenesis and pathology of anti-neutrophil cytoplasmic antibody（ANCA）-associated vasculitis

•

AAV is characterized by necrotizing small vessel vasculitis with positive serum ANCA.

•

MPO/PR3-ANCA and neutrophils play central roles in AAV pathogenicity.

•

Dysregulated complement system primes neutrophils.

•

MPO-ANCA directly activates neutrophils to induce NETosis followed by releasing NETs.

•

B cells, T cells, and dendritic cells also contribute to the pathogenicity of AAV.

Increased Frequencies of Switched Memory B Cells and Plasmablasts in Peripheral Blood from Patients with ANCA-Associated Vasculitis

B cells are thought to play a central role in the pathogenesis of antineutrophil cytoplasmic antibody- (ANCA-) associated vasculitis (AAV). ANCAs have been proposed to cause vasculitis by activating primed neutrophils to damage small blood vessels. We studied a cohort of AAV patients of which a majority were in remission and diagnosed with granulomatosis with polyangiitis (GPA). Using flow cytometry, the frequencies of CD19⁺ B cells and subsets in peripheral blood from 106 patients with AAV and 134 healthy controls were assessed. B cells were divided into naive, preswitch memory, switched memory, and exhausted memory cells. Naive and switched memory cells were further subdivided into transitional cells and plasmablasts, respectively. In addition, serum concentrations of immunoglobulin A, G, and M were measured and clinical data were retrieved. AAV patients displayed, in relation to healthy controls, a decreased frequency of B cells of lymphocytes (5.1% vs. 8.3%) and total B cell number. For the subsets, a decrease in percentage of transitional B cells (0.7% vs. 4.4%) and expansions of switched memory B cells (22.3% vs. 16.5%) and plasmablasts (0.9% vs. 0.3%) were seen. A higher proportion of B cells was activated (CD95⁺) in patients (20.6% vs. 10.3%), and immunoglobulin levels were largely unaltered. No differences in B cell frequencies between patients in active disease and remission were observed. Patients in remission with a tendency to relapse had, compared to nonrelapsing patients, decreased frequencies of B cells (3.5% vs. 6.5%) and transitional B cells (0.1% vs. 1.1%) and an increased frequency of activated exhausted memory B cells (30.8% vs. 22.3%). AAV patients exhibit specific changes in frequencies of CD19⁺ B cells and their subsets in peripheral blood. These alterations could contribute to the autoantibody-driven inflammatory process in AAV.

Immunopathogenesis of ANCA-Associated Vasculitis

Anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis is an autoimmune disorder which affects small- and, to a lesser degree, medium-sized vessels. ANCA-associated vasculitis encompasses three disease phenotypes: granulomatosis with polyangiitis (GPA), microscopic polyangiitis (MPA), and eosinophilic granulomatosis with polyangiitis (EGPA). This classification is largely based on clinical presentations and has several limitations. Recent research provided evidence that genetic background, risk of relapse, prognosis, and co-morbidities are more closely related to the ANCA serotype, proteinase 3 (PR3)-ANCA and myeloperoxidase (MPO)-ANCA, compared to the disease phenotypes GPA or MPA. This finding has been extended to the investigation of biomarkers predicting disease activity, which again more closely relate to the ANCA serotype. Discoveries related to the immunopathogenesis translated into clinical practice as targeted therapies are on the rise. This review will summarize the current understanding of the immunopathogenesis of ANCA-associated vasculitis and the interplay between ANCA serotype and proposed disease biomarkers and illustrate how the extending knowledge of the immunopathogenesis will likely translate into development of a personalized medicine approach in the management of ANCA-associated vasculitis.

Updates in the treatment of granulomatosis with polyangiitis and microscopic polyangiitis: At a crossroad

There have been great advances in the management of ANCA associated vasculitis over the past decades. We have gone from an era where the disease was almost universally fatal to trying to prevent long-term side effects of treatment regimens. With the ability to use pulse cyclophosphamide or rituximab as alternates to oral cyclophosphamide for induction of remission, side effects of therapy have been greatly reduced. New approaches have drastically changed our approach to maintenance and we now favor much longer durations of maintenance therapy, as they are more successful in preventing relapse. Steroids have long been the bane of treatment as they are associated with a significant risk of infection and metabolic consequences. We are now in a steroid-sparing and looking ahead to a steroid-free era with new data being published showing lower doses of steroids being equally effective and several ongoing seminal trials looking at agents that could completely replace steroids very early on.

Rituximab treatment of ANCA-associated vasculitis

INTRODUCTION

Rituximab, an anti-B-cell biological therapy, has been investigated in several clinical trials on antineutrophil cytoplasmic antibody (ANCA)-associated vasculitides (AAVs).

AREAS COVERED

In this paper, the clinical trials and open-label studies on rituximab efficacy and safety in treating AAVs are reviewed.

EXPERT OPINION

Rituximab achieved high remission-induction and sustained-maintenance rates for patients with these severe diseases, thereby challenging the cornerstone treatment of corticosteroids and cyclophosphamide followed by azathioprine. Rituximab should be used as first-line therapy with corticosteroids to induce remission of severe AAVs, especially in situations in which cyclophosphamide may be problematic (relapse after cyclophosphamide, women of childbearing age, risk of malignancy). Cyclophosphamide indications are likely to be restricted in the future. Whenever possible, rituximab should be preferred to azathioprine to maintain remission. The current maintenance regimen has been extended to at least 18 months but its optimal duration remains unknown and recent data suggest the possibility to extend treatment to 4 years. Future challenges include defining the best dose regimen: at present, different schedules are used as alternatives to those recognized as standards by health authorities. In addition, it remains to identify which patients will benefit the most from long-term retreatment: potentially those with relapsing disease or anti-proteinase-3 ANCA-positivity.

B-cell treatment in ANCA-associated vasculitis

The pivotal role of B-cells in ANCA-associated vasculitis has been suggested by experimental data that demonstrate the direct pathogenicity of ANCAs. Rituximab (RTX), an anti-CD20 monoclonal antibody that targets B-cells, has proven its efficacy for induction of remission in severe ANCA vasculitis. RTX is equivalent to CYC for induction of remission, and is probably superior in relapsing patients. Long-term B cell depletion by prolonged RTX treatment has been shown to significantly reduce the relapse rate, when compared with AZA maintenance therapy. Biomarkers, such as B-cell subpopulations or ANCA monitoring, may help the clinician to determine the optimal dose and duration of RTX therapy.

Management of ANCA associated vasculitis

Anti-neutrophil cytoplasmic antibody (ANCA) associated vasculitis (AAV) is a small to medium vessel vasculitis associated with excess morbidity and mortality. This review explores how management of AAV has evolved over the past two decades with pivotal randomized controlled trials shaping the management of induction and maintenance of remission. Contemporary AAV care is characterized by approaches that minimize the cumulative exposure to cyclophosphamide and glucocorticoids, increasingly use rituximab for remission induction and maintenance, and consider therapies with less toxicity (for example, methotrexate, mycophenolate mofetil) for manifestations of AAV that do not threaten organ function or survival. Simultaneously, improvements in outcomes, such as renal and overall survival, have been observed. Additional trials and observational studies evaluating the comparative effectiveness of agents for AAV in various patient subgroups are needed. Prospective studies are necessary to assess the effect of psychosocial interventions on patient reported outcomes in AAV. Despite the expanding array of treatments for AAV, little guidance on how to personalize AAV care is available to physicians.

Severe infections in patients with anti-neutrophil cytoplasmic antibody-associated vasculitides receiving rituximab: A meta-analysis

INTRODUCTION

The efficacy of rituximab (RTX) for remission induction and maintenance in patients with anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitides (AAV) is now established, but the safety, particularly concerning severe infection risk, is not well known.

OBJECTIVE

The purpose of this meta-analysis is to assess the prevalence and incidence of severe infections and the factors explaining heterogeneity in AAV patients treated with RTX.

METHODS

PubMed and Embase were searched up to December 2017. Prevalence and incidence was pooled using a random-effects model in case of significant heterogeneity (I² > 50%). Severe infection was defined as severe when it led to hospitalization, intravenous antibiotics therapy, and/or death. The heterogeneity was explored by subgroup analyses and meta-regression.

RESULTS

The included studies encompassed 1434 patients with a median age of 51.9 years. The overall prevalence and incidence of severe infections was 15.4% (95% CI [8.9; 23.3], I² = 90%, 33 studies) and 6.5 per 100 person-years (PY) (95% CI [2.9; 11.4], I² = 76%, 18 studies), respectively. The most common infections were bacterial (9.4%, 95% CI [5.1; 14.8]). The prevalence of opportunistic infection was 1.5% (95% CI [0.5; 3.1], I² = 58%) including pneumocytis jirovecii infections (0.2%, 95% CI [0.0; 0.6], I² = 0), irrespective of prophylaxis administration. Mortality related to infection was estimated at 0.7% (95% CI [0.2; 1.2], I² = 27%). The RTX cumulative dose was positively associated with prevalence of infections (13 studies, prevalence increase of 4% per 100 mg, p < .0001). The incidence of infection was negatively associated with duration of follow-up (8 studies, incidence decrease of 9% per year, p = .03).

CONCLUSION

Prevalence and incidence of severe infections, mainly bacterial ones, were high in AAV patients treated with RTX. This meta-analysis highlights the need for prospective studies to stratify infectious risk and validate cumulative RTX dose and duration of follow-up as modifying factors.

Urinary and serum soluble CD25 complements urinary soluble CD163 to detect active renal anti-neutrophil cytoplasmic autoantibody-associated vasculitis: a cohort study

Background

Early detection of renal involvement in anti-neutrophil cytoplasmic autoantibody (ANCA)-associated vasculitis (AAV) is of major clinical importance to allow prompt initiation of treatment and limit renal damage. Urinary soluble cluster of differentiation 163 (usCD163) has recently been identified as a potential biomarker for active renal vasculitis. However, a significant number of patients with active renal vasculitis test negative using usCD163. We therefore studied whether soluble CD25 (sCD25), a T cell activation marker, could improve the detection of renal flares in AAV.

Methods

sCD25 and sCD163 levels in serum and urine were measured by enzyme-linked immunosorbent assay in 72 patients with active renal AAV, 20 with active extrarenal disease, 62 patients in remission and 18 healthy controls. Urinary and blood CD4+ T and CD4+ T effector memory (TEM) cell counts were measured in 22 patients with active renal vasculitis. Receiver operating characteristics (ROC) curves were generated and recursive partitioning was used to calculate whether usCD25 and serum soluble CD25 (ssCD25) add utility to usCD163.

Results

usCD25, ssCD25 and usCD163 levels were significantly higher during active renal disease and significantly decreased after induction of remission. A combination of usCD25, usCD163 and ssCD25 outperformed all individual markers (sensitivity 84.7%, specificity 95.1%). Patients positive for sCD25 but negative for usCD163 (n = 10) had significantly higher C-reactive protein levels and significantly lower serum creatinine and proteinuria levels compared with the usCD163-positive patients. usCD25 correlated positively with urinary CD4+ T and CD4+ TEM cell numbers, whereas ssCD25 correlated negatively with circulating CD4+ T and CD4+ TEM cells.

Conclusion

Measurement of usCD25 and ssCD25 complements usCD163 in the detection of active renal vasculitis.

Is There a Future for Anti-CD38 Antibody Therapy in Systemic Autoimmune Diseases?

CD38 is a type II glycoprotein highly expressed on plasmablasts, short-lived and long-lived plasma cells, but weakly expressed on other lymphoid cells, myeloid cells and non-hematopoietic cells. This expression pattern makes CD38 an interesting target for a targeted therapy aiming to deplete antibody-producing plasma cells. We present data suggesting that anti-CD38 therapy may be effective for the prevention at the preclinical stage and for the treatment of established autoimmune diseases, such as systemic lupus erythematosus, systemic sclerosis, Sjögren’s syndrome and anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis. Given the high unmet need for efficacious disease-modifying treatment in these diseases, studies are warranted to determine if anti-CD38 antibody-based therapies may delay or prevent the disease progression of systemic autoimmune diseases.

Remission maintenance in ANCA-associated vasculitis: does one size fit all?

Introduction: The majority of the patients with anti-neutrophil cytoplasmic autoantibody (ANCA) associated vasculitis (AAV) achieve remission with effective induction therapy. Therefore, prevention of relapses and avoiding long-term damage and treatment-related toxicity are major challenges.Areas covered: This review provides an update on maintenance therapy in AAV, emphasizing the available treatment options for granulomatosis with polyangiitis (GPA) and microscopic polyangiitis (MPA). Among the spectrum of all patients with AAV, those at higher risk of relapse have recently been identified. Clinical trials have yielded robust results about various options for maintenance of remission including common disease-modifying anti-rheumatic drugs (DMARDs, i.e. azathioprine, methotrexate, and mycophenolate mofetil) and rituximab (RTX). However, outcomes of these studies are not easy to compare.Expert opinion: Regardless of the treatment used, patients presenting with an anti-proteinase-3 ANCA, relapsing GPA have a substantially higher risk of relapse compared to patients with newly diagnosed MPA or positive anti-myeloperoxidase ANCA. While the efficacy of common DMARDs for remission maintenance is heterogeneous, the role of RTX seems particularly promising for the high-risk patients, although the most appropriate dose and timing of retreatment with RTX remain under controversial. Low-dose glucocorticoid use for remission maintenance versus complete discontinuation also remains under investigation.

Biologics for childhood systemic vasculitis

Recent advances have allowed better understanding of vasculitis pathogenesis and led to more targeted therapies. Two pivotal randomized controlled trials, RITUXVAS and rituximab in ANCA-associated vasculitis (RAVE), provide high-quality evidence demonstrating rituximab (RTX) is efficacious in inducing remission in adult ANCA-associated vasculitis (AAV) patients compared with cyclophosphamide (CYC). RAVE also demonstrated superiority of RTX to oral CYC for induction of remission in relapsing disease. Disappointingly, the RTX regimen was not associated with reduction in early serious adverse events. At least nine randomized trials are in progress, aiming to further delineate optimal dosing and duration of RTX therapy in AAV. In particular, the 6-month interim results of the PEPRS trial provide encouraging data specific to children. Due to special concerns related to growth, preservation of fertility, and potential for high cumulative medication doses, children with AAV should be considered as candidates for RTX even as a first-line remission induction therapy. Two randomized clinical trials have defined the role of infliximab in Kawasaki disease (KD), which appears to be as an alternative to a second infusion of intravenous immunoglobulin (IVIG) for treatment-resistant disease. Support for other biologics in the treatment of AAV or for biologics in the treatment of other vasculidities is largely lacking due to either unimpressive trial results or lack of trials. Except for the KD trials and the PEPRS, trials enrolling children remain scant. This review touches on the key trials and case series with biologics in the treatment of vasculitis that have influenced practice and shaped current thinking.

Th17 cells in renal inflammation and autoimmunity

Th17 cells are a distinct lineage of T-cells. These T-cells express IL-17A and the lineage-defining transcription factor RORγt. Th17 cells have a pivotal, physiological role in host defense against pathogens. These pro-inflammatory T-cells are also key players in autoimmunity and a pathogenic role has been demonstrated in several diseases such as rheumatoid arthritis or psoriasis. Recently, there is evidence that Th17 cells may drive renal inflammation and renal autoimmunity in anti-neutrophil-cytoplasmic-antibody-(ANCA)-vasculitis and systemic lupus erythematosus. The aim of this review is to discuss the possible involvement of Th17 cells in renal autoimmunity and its value for future therapeutic approaches.

Pathogenesis of ANCA-Associated Pulmonary Vasculitis

Antineutrophil cytoplasmic antibodies (ANCAs) are autoantibodies specific for antigens located in the cytoplasmic granules of neutrophils and lysosomes of monocytes. ANCAs are associated with a spectrum of necrotizing vasculitis that includes granulomatosis with polyangiitis, microscopic polyangiitis, and eosinophilic granulomatosis with polyangiitis. Pulmonary vasculitis and related extravascular inflammation and fibrosis are frequent components of ANCA vasculitis. In this review, we detail the factors that have been associated with the origin of the ANCA autoimmune response and summarize the most relevant clinical observations, in vitro evidence, and animal studies strongly indicating the pathogenic potential of ANCA. In addition, we describe the putative sequence of pathogenic mechanisms driven by ANCA-induced activation of neutrophils that result in small vessel necrotizing vasculitis and extravascular granulomatous necrotizing inflammation.

Phenotypic Characterization of Circulating CD4+ T Cells in ANCA-Associated Vasculitis

T cell-mediated immune responses are thought to play an important role in the pathogenesis of anti-neutrophil cytoplasmic antibody- (ANCA-) associated vasculitides (AAV). CD4⁺ T cells can be divided into subsets depending on their expression of chemokine receptors. In this study, different CD4⁺ T cell populations in patients with AAV were analysed and compared to healthy blood donors as well as therapy controls. 18 patients with active AAV, 46 in remission, 21 healthy controls (HBD), and 15 therapy controls (TC) were enrolled. CD4⁺ T cells were divided into Th1, Th2, and Th17 cells and further subdivided into naïve, central memory, effector memory, and effector cells. Regulatory T cells were also analysed. Concentrations of cytokines and chemokines produced by the respective CD4⁺ T cell subset in plasma from 33 of the patients were measured by ELISA and compared to HBD. Clinical data were collected on all patients. CCL20 concentrations and percentages of Th17 cells (p = 0.019) were elevated in AAV patients compared to HBD. AAV patients had lower percentages of naïve CD4⁺ T cells (p = 0.0016) and a corresponding increase in proportion of effector memory CD4⁺ T cells when comparing to HBD (p = 0.027). Therapy controls showed similar results as AAV patients. In this study, we found that CD4⁺ T cell phenotype distribution is altered in AAV patients, in line with previously published work. However, no differences were found between AAV patients and TC, stressing the importance of treatment impact on this kind of studies.

Targeted immunotherapy strategies in ANCA-associated vasculitis

Targeted immunotherapy is substantially improving the management of ANCA-associated vasculitides (AAV), which include granulomatosis with polyangiitis (GPA, Wegener's granulomatosis), microscopic polyangiitis (MPA), and eosinophilic granulomatosis with polyangiitis (EGPA, Churg-Strauss syndrome). This article reviews the current role for targeted immunotherapy in AAV, its validated indications, and avenues for further development. Rituximab is a validated induction treatment for GPA and severe MPA. Rituximab in these indications is not less effective than cyclophosphamide and is particularly useful in patients with refractory or relapsing disease, women of childbearing potential, and patients previously treated with cyclophosphamide. Rituximab is more effective than cyclophosphamide for treating relapses. For remission maintenance therapy, which is indispensable, rituximab has been proven superior over conventional immunosuppressive treatment. Rituximab is licensed in the USA and in Europe for the induction treatment of severe forms of GPA and MPA. An extension study for remission maintenance therapy is ongoing. In EGPA, although maintenance treatment with the interleukin-5 antagonist mepolizumab is effective in decreasing glucocorticoid requirements and in alleviating asthma and sinonasal symptoms, its efficacy on the vasculitis remains somewhat unclear. Mepolizumab is licensed for use in EGPA, and rituximab is also being evaluated as an induction and maintenance agent. Immunoglobulins can be helpful as an adjuvant treatment for active AAV with severe immunedepression, notably when infections occur. Plasma exchange is indicated in AAV with advanced renal dysfunction and, perhaps, in the event of alveolar hemorrhage, a possibility that will be assessed in 2018 in a large international study.

Anti-CD20 monoclonal antibodies: reviewing a revolution

Since the inception of rituximab in the 1990s, anti-CD20 monoclonal antibodies have revolutionised the treatment of B cell hematological malignancies and have become a cornerstone of modern gold-standard practice. Additionally, the potent efficacy of these agents in depleting the B cell compartment has been used in the management of a broad array of autoimmune diseases. Multiple iterations of these agents have been investigated and are routinely used in clinical practice. In this review, we will discuss the physiology of CD20 and its attractiveness as a therapeutic target, as well as the pharmacology, pre-clinical and clinical data for the major anti-CD20 monoclonal antibodies: rituximab, obinutuzumab and ofatumumab.

Recent advances in understanding of the pathogenesis of ANCA-associated vasculitis

Anti-neutrophil cytoplasm antibody (ANCA)-associated vasculitides (AAV) are rare systemic autoimmune diseases characterised by inflammation of small blood vessels. Recent developments have been made in our understanding of the pathogenesis of these diseases, including the pathogenic role of ANCA, neutrophils and monocytes as mediators of injury, dysregulation of the complement system, and the role of T and B cells. Current treatment strategies for AAV are based on broad immunosuppression, which may have significant side effects. Advances in understanding of the pathogenesis of disease have led to the identification of new therapeutic targets which may lead to treatment protocols with less-toxic side effects. The aim of this review is to summarise current information and recent advances in understanding of the pathogenesis of AAV.

Could Lymphocyte Profiling be Useful to Diagnose Systemic Autoimmune Diseases?

Considering the implications of B, T, and natural killer (NK) cells in the pathophysiology of systemic autoimmune diseases, the assessment of their distribution in the blood could be helpful for physicians in the complex process of determining a precise diagnosis. In primary Sjögren's syndrome, transitional and active naive B cells are increased and memory B cells are decreased compared to healthy controls and other systemic diseases. However, their utility to improve the accuracy of classification criteria has not been proven. In early untreated rheumatoid arthritis, proportions of regulatory T cells are constantly reduced, but other patterns are difficult to determine given the heterogeneity of published studies. In systemic lupus erythematosus, the lack of studies using large cohorts of patients and the diversity of the possible pathological mechanisms involved are also important impediments. Nevertheless, transitional B cell and plasma cell proportions are increased in most of the studies, the CD4/CD8 ratio is decreased, and the number of NK cells is reduced. Despite the low number of studies, anomalies of lymphocyte subset distribution was also described in ANCA-associated vasculitis, systemic scleroderma, and myositis. For now, flow cytometric analysis of lymphocyte subsets has focused mainly on specific subpopulations and is more useful for basic and translational research than for diagnostics in clinical practice. However, new modern methods such as mass cytometry and bioinformatics analyses may offer the possibility to simultaneously account for the relative proportions of multiple lymphocyte subsets and define a global profile in homogeneous groups of patients. The years to come will certainly incorporate such global lymphocyte profiling in reclassification of systemic autoimmune diseases.

Targeting B Cells and Plasma Cells in Glomerular Diseases: Translational Perspectives

The unique contributions of memory B cells and plasma cells in kidney diseases remain unclear. In this review, we evaluate the clinical experience with treatments directed at B cells, such as rituximab, and at plasma cells, such as proteasome inhibition, to shed light on the role of these two B lineage compartments in glomerular diseases. Specifically, analysis of these targeted interventions in diseases such as ANCA-associated vasculitis, SLE, and antibody-mediated transplant rejection permits insight into the pathogenetic effect of these cells. Notwithstanding the limitations of preclinical models and clinical studies (heterogeneous populations, among others), the data suggest that memory B and plasma cells represent two engines of autoimmunity, with variable involvement in these diseases. Whereas memory B cells and plasma cells appear to be key in ANCA-associated vasculitis and antibody-mediated transplant rejection, respectively, SLE seems likely to be driven by both autoimmune compartments. These conclusions have implications for the future development of targeted therapeutics in immune-mediated renal disease.

Chemokine receptor co-expression reveals aberrantly distributed TH effector memory cells in GPA patients

Background

Persistent expansion of circulating CD4⁺ effector memory T cells (T_EM) in patients with granulomatosis with polyangiitis (GPA) suggests their fundamental role in disease pathogenesis. Recent studies have shown that distinct functional CD4⁺ T_EM cell subsets can be identified based on expression patterns of chemokine receptors. The current study aimed to determine different CD4⁺ T_EM cell subsets based on chemokine receptor expression in peripheral blood of GPA patients. Identification of particular circulating CD4⁺ T_EM cells subsets may reveal distinct contributions of specific CD4⁺ T_EM subsets to the disease pathogenesis in GPA.

Method

Peripheral blood of 63 GPA patients in remission and 42 age- and sex-matched healthy controls was stained immediately after blood withdrawal with fluorochrome-conjugated antibodies for cell surface markers (CD3, CD4, CD45RO) and chemokine receptors (CCR4, CCR6, CCR7, CRTh2, CXCR3) followed by flow cytometry analysis. CD4⁺ T_EM memory cells (CD3⁺CD4⁺CD45RO⁺CCR7^-) were gated, and the expression patterns of chemokine receptors CXCR3⁺CCR4^-CCR6^-CRTh2^-, CXCR3^-CCR4⁺CCR6^-CRTh2⁺, CXCR3^-CCR4⁺CCR6⁺CRTh2^-, and CXCR3⁺CCR4^-CCR6⁺CRTh2^- were used to distinguish T_EM1, T_EM2, T_EM17, and T_EM17.1 cells, respectively.

Results

The percentage of CD4⁺ T_EM cells was significantly increased in GPA patients in remission compared to HCs. Chemokine receptor co-expression analysis within the CD4⁺ T_EM cell population demonstrated a significant increase in the proportion of T_EM17 cells with a concomitant significant decrease in the T_EM1 cells in GPA patients compared to HC. The percentage of T_EM17 cells correlated negatively with T_EM1 cells in GPA patients. Moreover, the circulating proportion of T_EM17 cells showed a positive correlation with the number of organs involved and an association with the tendency to relapse in GPA patients. Interestingly, the aberrant distribution of T_EM1 and T_EM17 cells is modulated in CMV- seropositive GPA patients.

Conclusions

Our data demonstrates the identification of different CD4⁺ T_EM cell subsets in peripheral blood of GPA patients based on chemokine receptor co-expression analysis. The aberrant balance between T_EM1 and T_EM17 cells in remission GPA patients, showed to be associated with disease pathogenesis in relation to organ involvement, and tendency to relapse.

Electronic supplementary material

The online version of this article (doi:10.1186/s13075-017-1343-8) contains supplementary material, which is available to authorized users.

Immunoglobulin levels and infection risk with rituximab induction for anti-neutrophil cytoplasmic antibody-associated vasculitis

Background

Rituximab (RTX), a B cell–depleting anti-CD20 monoclonal antibody, is approved for treatment of anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV). Low immunoglobulin (Ig) levels have been observed surrounding RTX treatment. The association between the degree of Ig deficiency and infection risk is unclear in AAV patients.

Methods

AAV patients treated with RTX for remission induction at a single center (2005–15) with serum Ig measurements were included. Patient characteristics; serum IgG, IgM and IgA levels and occurrence of infections were collected retrospectively. Low IgG was defined as mild (376–749 mg/dL) or severe (>375 mg/dL). Logistic regression models were adjusted for age at RTX administration, estimated glomerular filtration rate (eGFR) and race to examine the association of degree and type of Ig deficiency and infection risk.

Results

Our cohort of 30 patients had a mean age of 63 (SD 7) years, 23 were women, 16 had granulomatosis with polyangiitis and 13 were PR3 ANCA positive. Nine patients received concomitant cyclophosphamide. The mean IgG level was 625 mg/dL (SD 289), mean IgM level was 55 mg/dL (SD 41) and mean IgA level was 133 mg/dL (SD 79). In this cohort, 20 patients had low serum IgG levels (<750 mg/dL) following RTX treatment. During the follow-up period, four individuals developed infections requiring hospitalization. In unadjusted logistic regression analysis, an IgG level ≤ 375 mg/dL was associated with 23 times higher odds of hospitalized infection [95% confidence interval (CI) 1.8–298.4; P = 0.02]. After adjustment for age, race and eGFR, results were similar [odds ratio (OR) 21.1 (95% CI 1.1–404.1) P = 0.04]. Low IgA was also associated with an increased risk of infections requiring hospitalization after adjusting for age, race and eGFR [OR 24.6 (95% CI 1.5–799.5) P = 0.03]. Low IgM was not associated with a higher risk of infections requiring hospitalization.

Conclusions

Severe hypogammaglobulinemia was associated with increased odds of infection requiring hospitalization in this cohort. Further investigation is warranted given our study is limited by small sample size, concomitant cyclophosphamide use and variable timing of Ig measurement.

MPO-ANCA-associated necrotizing glomerulonephritis in rheumatoid arthritis; a case report and review of literature

Background

Renal involvement in rheumatoid arthritis (RA) is common and has a negative impact on patient survival. Only few cases have been reported of necrotizing glomerulonephritis (GN) associated with myeloperoxidase anti-neutrophil cytoplasmic antibody (MPO-ANCA) in patients with RA.

Case Presentation

We report a patient with RA who developed a necrotizing GN associated with ANCA-MPO, treated with rituximab (RTX). A 55-year-old man with a 27-year history of RA under secukinumab was referred to our nephrology clinic with worsening renal function associated with microhematuria and proteinuria. Our laboratory evaluation showed hypocomplementemia and positive titers for MPO-ANCA (615 U/mL). A renal biopsy demonstrated pauci-immune necrotizing GN. The patient was treated with 3 consecutive pulses of methylprednisolone followed by oral prednisolone (1 mg/Kg) and rituximab (1000 mg, repeated 14 days later). After a 10-month follow-up, the arthritis remains well-controlled, renal function stabilized, proteinuria improved and MPO-ANCA titer normalized (6.3 U/mL).

Conclusions

Necrotizing GN is a rare but a serious condition and an early diagnosis is essential to treatment. This is the first case of necrotizing GN (without extra-renal manifestations of vasculitis) in a patient with active RA, successfully treated with RTX.

Recent advances in understanding and treating vasculitis

Anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitides (AAVs) are near universally fatal conditions if untreated. Although effective therapeutic options are available for these diseases, treatment regimens are associated with both short- and long-term adverse effects. The recent identification of effective B-cell-targeted therapy with an anti-CD20 monoclonal antibody has transformed the treatment landscape of AAV. Questions, nevertheless, remain regarding the appropriate timing, dose, frequency, duration, and long-term effects of treatment. The aim of this article is to provide an overview of the current information, recent advances, ongoing clinical trials, and future treatment possibilities in AAV.

Place in therapy of rituximab in the treatment of granulomatosis with polyangiitis and microscopic polyangiitis

Granulomatosis with polyangiitis and microscopic polyangiitis are small vessel vasculitides characterized by circulating antineutrophil circulating antibodies. Standard treatment for active severe disease has consisted of cyclophosphamide with glucocorticoids with or without plasmapheresis, which achieves approximately 75% sustained remission, but carries significant adverse effects such as malignancy, infertility, leukopenia, and infections. The role of B cells in the pathogenesis of anti-neutrophil circulating antibodies-associated vasculitis has been established, and as such, rituximab, a monoclonal anti-CD20 antibody, has been studied in treatment of active granulomatosis with polyangiitis and microscopic polyangiitis (induction) and in maintaining remission. Rituximab has been shown to be effective in inducing remission in several retrospective studies in patients with refractory disease or cyclophosphamide intolerance. The RAVE and RITUXVAS trials demonstrated rituximab is a noninferior alternative to standard cyclophosphamide-based therapy; however, its role in elderly patients and patients with severe renal disease warrants further investigation. Rituximab has been compared with azathioprine for maintaining remission in the MAINRITSAN trial and may be more efficacious in maintaining remission in patients treated with cyclophosphamide induction. Rituximab is not without risks and carries a similar adverse event risk rate as cyclophosphamide in randomized control trials. However, its use can be considered over cyclophosphamide in patients who have relapsing or refractory disease or in young patients seeking to preserve fertility.

Rituximab as maintenance therapy for ANCA associated vasculitis: how, when and why?

ANCA-associated vasculitides (AAV) are chronic autoimmune diseases characterized by inflammation and destruction of small vessels. Rituximab is now licensed for use as a remission-induction agent in the treatment of these disorders. During recent years, several non-controlled studies have suggested that rituximab may be of value in maintaining disease remission in AAV. In these series, 3 techniques have been tried: "watch-and-wait", repeated cycles in fixed intervals, or administration based on proposed biomarkers. More importantly, the results of the MAINRITSAN trial showed that this anti-CD20 agent is superior to azathioprine for preventing major relapses in AAV. This review summarizes current information regarding the effectiveness, timing, dosing, duration and safety of rituximab as a valid option for remission maintenance.

Pro: Should all patients with anti-neutrophil cytoplasmic antibody-associated vasculitis be primarily treated with rituximab?

Randomized controlled trials have shown that rituximab is non-inferior to cyclophosphamide followed by azathioprine (CYC/AZA) for remission induction in severe granulomatosis with polyangiitis (GPA) and microscopic polyangiitis (MPA). The efficacy of rituximab is on par with CYC/AZA for 18 months, for patients with GPA and MPA alike, and for patients with any degree of renal impairment. The Rituximab in ANCA-associated Vasculitis (RAVE) trial also showed superiority of rituximab for patients presenting with a severe disease relapse. An exploratory analysis of the RAVE data further suggests that rituximab may be preferable for PR3-ANCA-positive patients as superiority was also achieved in that subset. When considering treatment options for patients with disease presentations for which only non-inferiority has been documented, safety concerns, compliance issues, the overall cost of each treatment approach to the patient, to society and to insurers, as well as individual patient preferences all should affect the decision-making process. The trials failed to uncover any difference in adverse events between rituximab and CYC/AZA. However, daily oral cyclophosphamide given for 3-6 months has measurable negative effects on fertility. Rituximab has certain compliance and convenience advantages. When assessing cost, the overall cost of a treatment, the societal context of the individual patient and not merely the sticker price of the drug should be considered. For all of these reasons, the author believes that CYC/AZA should be reserved for patients with newly diagnosed, MPO-ANCA-positive disease who raise no fertility, compliance or malignancy concerns.

Efficacy and safety of rituximab as maintenance therapy for relapsing granulomatosis with polyangiitis—a case series

The objective of this work was to study the efficacy and safety of pre-emptive rituximab (RTX) in a series of patients with severe relapsing granulomatosis with polyangiitis (GPA). GPA is a systemic vasculitis with a high relapse rate despite successful remission induction. Drug toxicity with repeated induction treatments and long-standing immunosuppression poses a problem. Based on the findings in reports on RTX for rheumatoid arthritis, we treated patients with severe relapsing GPA with pre-emptive RTX, 1,000 mg 2 weeks apart every 6 months, aiming at achieving sustainable remission. All patients at one centre with relapsing GPA in spite of traditional maintenance treatment, who had received more than or equal to three cycles of RTX as regularly repeated pre-emptive maintenance therapy every 6 months, were included in this retrospective study. Information on disease manifestations and activity, treatments, lab parameters and adverse events was extracted from the medical files. Of the 12 included patients, all with a positive proteinase 3–anti-neutrophil cytoplasmic antibodies, generalised disease and a median disease duration of 35 months (21–270), 92 % (11/12) achieved sustainable remission during a median follow-up time of 32 months (range 21–111) from first RTX treatment. Concomitant immunosuppressants were reduced. Infections were the most common adverse events, but infections were an issue also before the start of RTX. RTX administered every 6 months seems to be an effective maintenance treatment in a population with severe, relapsing long-standing GPA. Granulomatous as well as vasculitic manifestations responded equally well. Infections are a problem in this patient group but no new safety problems were identified.

Are urinary levels of high mobility group box 1 markers of active nephritis in anti-neutrophil cytoplasmic antibody-associated vasculitis?

The objective of this study is to evaluate urinary high mobility group box 1 (HMGB1) levels as markers for active nephritis in patients with anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) in comparison with urinary CD4(+) effector memory T cells and urinary monocyte chemoattractant protein-1 (MCP-1). Twenty-four AAV patients with active nephritis and 12 healthy controls (HC) were evaluated. In nine patients, samples were also obtained during remission. Urinary levels of HMGB1 were measured by Western blot. CD4(+) T cells and CD4(+) effector memory T cells (CD4(+) CD45RO(+) CCR7(-) ) were determined in urine and whole blood by flow cytometry. Measurement of urinary levels of MCP-1 and serum HMGB1 levels were performed by enzyme-linked immunosorbent assay (ELISA). AAV patients with active nephritis had higher median intensity of HMGB1 in urine than HC [10·3 (7·05-18·50) versus 5·8 (4·48-7·01); P = 0·004]. Both urinary HMGB1 and MCP-1 levels decreased significantly from active nephritis to remission. The urinary MCP-1/creatinine ratio correlated with Birmingham Vasculitis Activity Score (BVAS) (P = 0·042). No correlation was found between the HMGB1/creatinine ratio and 24-h proteinuria, estimated glomerular filtration rate (eGFR), MCP-1/creatinine ratio, BVAS and serum HMGB1. A positive correlation was found between urinary HMGB1/creatinine ratio and CD4(+) T cells/creatinine ratio (P = 0·028) and effector memory T cells/creatinine ratio (P = 0·039) in urine. Urinary HMGB1 levels are increased in AAV patients with active nephritis when compared with HC and patients in remission, and urinary HMGB1 levels are associated with CD4(+) T cells and CD4(+) effector memory T cells in urine. Measurement of urinary HMGB1 may be of additional value in identifying active glomerulonephritis in AAV patients.