Maintenance of clinical remission in ANCA-associated vasculitis

The role of neutrophils in rheumatic disease-associated vascular inflammation

Vascular pathologies underpin and intertwine autoimmune rheumatic diseases and cardiovascular conditions, and atherosclerosis is increasingly recognized as the leading cause of morbidity in conditions such as systemic lupus erythematosus (SLE), rheumatoid arthritis and antineutrophil cytoplasmic antibody-associated vasculitis. Neutrophils, important cells in the innate immune system, exert their functional effects in tissues via a variety of mechanisms, including the generation of neutrophil extracellular traps and the production of reactive oxygen species. Neutrophils have been implicated in the pathogenesis of several rheumatic diseases, and can also intimately interact with the vascular system, either through modulating endothelial barriers at the blood-vessel interface, or through associations with platelets. Emerging data suggest that neutrophils also have an important role maintaining homeostasis in individual organs and can protect the vascular system. Furthermore, studies using high-dimensional omics technologies have advanced our understanding of neutrophil diversity, and immature neutrophils are receiving new attention in rheumatic diseases including SLE and systemic vasculitis. Developments in genomic, imaging and organoid technologies are beginning to enable more in-depth investigations into the pathophysiology of vascular inflammation in rheumatic diseases, making now a good time to re-examine the full scope of roles of neutrophils in these processes.

ROS-producing immature neutrophils in giant cell arteritis are linked to vascular pathologies

Giant cell arteritis (GCA) is a common form of primary systemic vasculitis in adults, with no reliable indicators of prognosis or treatment responses. We used single cell technologies to comprehensively map immune cell populations in the blood of patients with GCA and identified the CD66b⁺CD15⁺CD10^lo/–CD64^– band neutrophils and CD66b^hiCD15⁺CD10^lo/–CD64^+/bright myelocytes/metamyelocytes to be unequivocally associated with both the clinical phenotype and response to treatment. Immature neutrophils were resistant to apoptosis, remained in the vasculature for a prolonged period of time, interacted with platelets, and extravasated into the tissue surrounding the temporal arteries of patients with GCA. We discovered that immature neutrophils generated high levels of extracellular reactive oxygen species, leading to enhanced protein oxidation and permeability of endothelial barrier in an in vitro coculture system. The same populations were also detected in other systemic vasculitides. These findings link functions of immature neutrophils to disease pathogenesis, establishing a clinical cellular signature of GCA and suggesting different therapeutic approaches in systemic vascular inflammation.

Bona fide immature neutrophil subsets produce unchecked extracellular ROS that contributes to vascular pathologies.

Organisation of lymphocytic infiltrates in ANCA-associated glomerulonephritis

AIMS

Renal involvement in anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis contributes to significant morbidity and mortality in patients. In chronic inflammation, B cells are recruited to the inflamed tissue and organised lymphoid structures have been described in several autoimmune diseases. The aim of this study was to correlate the lymphoid organisation in renal biopsies with renal outcome in ANCA-associated glomerulonephritis (GN).

METHODS AND RESULTS

We investigated 112 renal biopsies from patients with newly diagnosed ANCA-associated necrotising GN. We identified four different levels of the intrarenal organisation of lymphocytes: T cells without B cells, scattered B and T cells, clustered lymphocytic infiltrates and nodular compartmentally arranged B and T cell aggregates. Almost half the patients showed clusters of B and T lymphocytes in their biopsies. In 15 of these biopsies, a higher degree of organisation with lymphocytic compartments was detected. Inflammatory cell organisation was associated with renal failure, but not with tubular atrophy and interstitial fibrosis. Patients with organised lymphocytic infiltrates in their biopsy had worse renal function during follow-up and were more likely to develop end stage renal disease.

CONCLUSIONS

In the present study, we show that the renal lymphocytic organisation is associated with renal outcome in ANCA-associated GN. The organisation of the lymphocytic infiltrate may be a morphological correlate of a perpetual and exaggerated inflammation in renal ANCA disease. Classifying the lymphocytic infiltrate could help to predict renal outcome, and might therefore be used for individualised adjustments in the intensity and duration of immunosuppressive therapy.

The Role of Ultrasound Compared to Biopsy of Temporal Arteries in the Diagnosis and Treatment of Giant Cell Arteritis (TABUL): a diagnostic accuracy and cost-effectiveness study

BACKGROUND

Giant cell arteritis (GCA) is a relatively common form of primary systemic vasculitis, which, if left untreated, can lead to permanent sight loss. We compared ultrasound as an alternative diagnostic test with temporal artery biopsy, which may be negative in 9-61% of true cases.

OBJECTIVE

To compare the clinical effectiveness and cost-effectiveness of ultrasound with biopsy in diagnosing patients with suspected GCA.

DESIGN

Prospective multicentre cohort study.

SETTING

Secondary care.

PARTICIPANTS

A total of 381 patients referred with newly suspected GCA.

MAIN OUTCOME MEASURES

Sensitivity, specificity and cost-effectiveness of ultrasound compared with biopsy or ultrasound combined with biopsy for diagnosing GCA and interobserver reliability in interpreting scan or biopsy findings.

RESULTS

We developed and implemented an ultrasound training programme for diagnosing suspected GCA. We recruited 430 patients with suspected GCA. We analysed 381 patients who underwent both ultrasound and biopsy within 10 days of starting treatment for suspected GCA and who attended a follow-up assessment (median age 71.1 years; 72% female). The sensitivity of biopsy was 39% [95% confidence interval (CI) 33% to 46%], which was significantly lower than previously reported and inferior to ultrasound (54%, 95% CI 48% to 60%); the specificity of biopsy (100%, 95% CI 97% to 100%) was superior to ultrasound (81%, 95% CI 73% to 88%). If we scanned all suspected patients and performed biopsies only on negative cases, sensitivity increased to 65% and specificity was maintained at 81%, reducing the need for biopsies by 43%. Strategies combining clinical judgement (clinician's assessment at 2 weeks) with the tests showed sensitivity and specificity of 91% and 81%, respectively, for biopsy and 93% and 77%, respectively, for ultrasound; cost-effectiveness (incremental net monetary benefit) was £485 per patient in favour of ultrasound with both cost savings and a small health gain. Inter-rater analysis revealed moderate agreement among sonographers (intraclass correlation coefficient 0.61, 95% CI 0.48 to 0.75), similar to pathologists (0.62, 95% CI 0.49 to 0.76).

LIMITATIONS

There is no independent gold standard diagnosis for GCA. The reference diagnosis used to determine accuracy was based on classification criteria for GCA that include clinical features at presentation and biopsy results.

CONCLUSION

We have demonstrated the feasibility of providing training in ultrasound for the diagnosis of GCA. Our results indicate better sensitivity but poorer specificity of ultrasound compared with biopsy and suggest some scope for reducing the role of biopsy. The moderate interobserver agreement for both ultrasound and biopsy indicates scope for improving assessment and reporting of test results and challenges the assumption that a positive biopsy always represents GCA.

FUTURE WORK

Further research should address the issue of an independent reference diagnosis, standards for interpreting and reporting test results and the evaluation of ultrasound training, and should also explore the acceptability of these new diagnostic strategies in GCA.

FUNDING

The National Institute for Health Research Health Technology Assessment programme.

Corticosteroid-free treatment of tocilizumab monotherapy for microscopic polyangiitis: a single-arm, single-center, clinical trial

OBJECTIVES

To assess the efficacy of tocilizumab (TCZ) monotherapy for the remission induction of microscopic polyangiitis (MPA) in a prospective single-arm, single-center, cohort, pilot study.

METHODS

Eligible patients were aged between 20 and 80 years and were newly diagnosed with MPA according to Watts' classification algorithm. Seven patients received 8 mg/kg of intravenous TCZ fortnightly for the first 2 months (5 courses), and monthly for the next 10 months (10 courses). One year after TCZ monotherapy, the patients were followed-up without any treatment. The protocol did not permit the use corticosteroids or any other immunosuppressants. Complete remission (CR) was defined as the Birmingham Vasculitis Activity Score of 0 at two consecutive visits made at least a month apart.

RESULTS

CR was achieved in two of six patients (33.3%) at 6 months and three patients (50.0%) at 12 months. Two patients were withdrawn: one because of inefficacy at 6 weeks and the other because of flare at 6 months. One patient voluntarily withdrew after CR at 3 months. Four patients (66.7%) could be kept drug-free after 1 year of TCZ without relapse for 6-15 months at the last visit.

CONCLUSION

TCZ monotherapy may be an alternative treatment strategy in some patients with MPA.

Recent advances in anti-neutrophil cytoplasmic antibody-associated vasculitis

Anti-neutrophil cytoplasmic antibody-associated vasculitis is an uncommon inflammatory disease of small to medium-sized vessels that frequently presents with rapidly progressive glomerulonephritis and renal failure though it can affect any organ system. If untreated, the vast majority of patients will die within a year. Current treatments improve prognosis but affected patients remain at a substantially higher risk of death and adverse outcomes. We review the classification of the disease, our understanding of the pathogenesis and epidemiology, and propose future directions for research. We also evaluate the evidence supporting established treatment regimens and the progress of clinical trials for newer treatments to inform the design of future studies.

Repeat cycles of rituximab on clinical relapse in ANCA-associated vasculitis: identifying B cell biomarkers for relapse to guide retreatment decisions

OBJECTIVE

To assess clinical and B cell biomarkers to predict relapse after rituximab in antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) using retreatment on clinical relapse strategy.

METHODS

35 patients with AAV received treatment with 2×1000 mg rituximab, repeated on clinical relapse (up to 5 cycles). Disease activity was assessed by Birmingham Vasculitis Activity Score (BVAS) and peripheral B cell subsets using highly sensitive flow cytometry (HSFC) as previously described; both performed at baseline and every 3 months.

RESULTS

Response rates were high: >83%, with median time-to-relapse of 82 weeks for cycle 1 (C1) and >54 weeks for all cycles. Prior to rituximab, AAV was characterised by naïve B-lymphopenia compared to healthy controls. This dysregulation was more marked in patients with raised C-reactive protein (CRP) (p<0.05). In C1, no clinical feature predicted relapse. However, repopulation of naïve B cell at 6 months was associated with a reduced risk of relapse (HR: 0.326, 95% 0.114 to 0.930, p=0.036). Relapse rates at 12 and 18 months were 0% and 14% with naïve repopulation at 6 months, and 31% and 54% without naïve repopulation.

CONCLUSIONS

Responses to B cell depletion therapy are long-lasting and relapse post-treatment may be predicted by absence of naïve B cell repopulation at 6 months. Naïve B-lymphopenia may be a biomarker of disease activity in AAV.

Conventional induction and maintenance treatment of Antineutrophil cytoplasmic antibodies-associated vasculitis - still of value for our patients?

INTRODUCTION

Antineutrophil cytoplasmic antibodies-associated vasculitis (AAV) is a group of autoimmune diseases characterized by the necrotizing inflammation of small vessels and associated with the antineutrophil cytoplasmic antibodies. Treatment of AAV can be divided into the induction phase aimed at achieving remission of the disease and the maintenance phase aimed at prevention of relapses. Long-term outcome of AAV dramatically improved with the introduction of cyclophosphamide. Recent clinical studies resulted in the reduction of the cumulative dose of cyclophosphamide and introduction of new treatment options, namely B-cell-depleting antibody rituximab, into both induction and maintenance treatment. This paper aims to evaluate the current role of the conventional induction and maintenance treatment in view of the gradually increasing use of rituximab.

AREAS COVERED

This paper provides an overview of the main clinical studies in induction and maintenance treatment of adult patients with AAV, treatment of relapses of AAV and shortly comments also on the treatment of refractory AAV, treatment of different subgroups of AAV (based on the age, renal function, clinical presentation and type of autoantibody), long-term outcome of patients with AAV, adverse events of treatment and treatment of end-stage renal disease in AAV.

EXPERT OPINION

Our analysis demonstrates that although the introduction of rituximab modified the approach to both the induction and maintenance treatment of AAV, more conventional induction and maintenance treatment with standard immunosuppressive drugs still retains its importance as we need more data on long-term efficacy and safety of biologic treatment, and also its cost-effectiveness still remains an open issue.

B-cell therapy in antineutrophil cytoplasmic antibody-associated vasculitis

Until recently, standard of care for patients with generalized or severe antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) has consisted of an induction regimen with cyclophosphamide (CYC) and corticosteroids followed by maintenance treatment with azathioprine. This regimen is associated with significant toxicity resulting in considerable morbidity and mortality whereas relapses are still not infrequent. In two controlled trials, the Rituximab in ANCA-associated Vasculitis study (RAVE) and the RITUXVAS trial of the European Vasculitis Study Group (EUVAS), rituximab (RTX) proved non-inferior to CYC for induction of remission. In addition, outcome at 18 months for the RAVE trial and 12 months for the RITUXVAS trial showed that RTX without maintenance treatment was as efficacious as CYC followed by azathioprine maintenance. To prevent relapses, which occur particularly in patients positive for PR3-ANCA, 500 mg RTX given every 6 months was shown to be superior to azathioprine in a French study. Thus, RTX is a new and promising therapeutic armamentarium for AAV although long-term safety has still to be established.

Is B-cell depletion first choice in antineutrophil cytoplasmic antibody-associated vasculitis?

PURPOSE OF REVIEW

To discuss in detail the efficacy and safety of rituximab (RTX) for induction and maintenance of remission in patients with antineutrophil cytoplasmic autoantibody (ANCA)-associated vasculitis (AAV) who are either treatment naive, relapsing or refractory to standard of care.

RECENT FINDINGS

In treatment naive AAV patients, RTX without maintenance treatment is as effective as cyclophosphamide (CYC) followed by azathioprine (AZA) for maintenance for up to 18 months. RTX is superior to CYC for induction of remission in patients with relapsing AAV. Nevertheless, long-term follow-up shows relapsing disease in up to 50% of patients with proteinase 3-ANCA, irrespective of the induction regimen. RTX is useful in patients with refractory AAV, but percentages of patients achieving complete remission differ between series. RTX seems more effective than AZA for maintaining remission, but detailed results from prospective studies are being awaited. Adverse events do not differ between RTX and classical induction regimens, but infections related to hypogammaglobulinemia and neutropenia could be items of concern with repeated administration of RTX.

SUMMARY

RTX is an alternative for CYC for induction of remission in generalized AAV and could be first choice for relapsing patients and patients refractory to CYC. RTX is promising for maintenance of remission, but long-term safety should be awaited.

Key advances in the clinical approach to ANCA-associated vasculitis

The updated nomenclature for vasculitis defines this varied group of disorders by aetiology, specific features of pathogenesis and clinical symptoms; diagnostic and classification criteria for clinical practice are in development. Here, I review some important advances in the management of vasculitis within the category of anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV), which encompasses microscopic polyangiitis (MPA), granulomatosis with polyangiitis (GPA) and eosinophilic granulomatosis with polyangiitis (EGPA). The clinical approach to the management of the patient with AAV should include testing for ANCA specificity; proteinase 3 (PR3)-specific ANCAs are most often associated with GPA, whereas myeloperoxidase (MPO)-ANCAs are usually associated with MPA. Also important to the management of AAV is an assessment of the disease stage and severity, to enable tailored treatment based on an algorithm derived from controlled-trial data. Remaining questions pertain to the dosage and duration of corticosteroid treatment, the selection of patients for, and duration of, maintenance treatment after induction of remission, and the identification of safer and more effective therapies than are currently in use. Outcome measures should assess not only disease activity, but also damage and quality of life. Infections, cardiovascular events and malignancies also contribute to outcome, and their prevention should therefore be part of the clinical approach to managing patients with AAV.

Intravascular immunity as a key to systemic vasculitis: a work in progress, gaining momentum

Vascular inflammation contributes to the defence against invading microbes and to the repair of injured tissues. In most cases it resolves before becoming apparent. Vasculitis comprises heterogeneous clinical entities that are characterized by the persistence of vascular inflammation after it has served its homeostatic function. Most underlying mechanisms have so far remained elusive. Intravascular immunity refers to the surveillance of the vasculature by leucocytes that sense microbial or sterile threats to vessel integrity and initiate protective responses that entail most events that determine the clinical manifestations of vasculitis, such as end-organ ischaemia, neutrophil extracellular traps generation and thrombosis, leucocyte extravasation and degranulation. Understanding how the resolution of vascular inflammation goes awry in patients with systemic vasculitis will facilitate the identification of novel pharmacological targets and bring us a step closer in each patient to the selection of more effective and less toxic treatments.

Granuloma in ANCA-associated vasculitides: another reason to distinguish between syndromes?

The 2012 renewed Chapel Hill Consensus Conference (CHCC) officially named three clinicopathological entities, i.e. granulomatosis with polyangiitis (GPA), eosinophilic granulomatosis with polyangiitis (EGPA), and microscopic polyangiitis (MPA), as major variants of anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitides (AAV). Recent genetic and cohort studies revealed the need for further differentiation between the entities, for example regarding differences in outcome. As well as ANCA reactivity, upper and lower airway disease were found to be differentiating factors for AAV variants, improving prognostic ability regarding relapse prediction and associated clinical features. Extravascular granulomatosis, or "granuloma", which describes both clinically relevant granulomatous manifestations and histopathologically documented granulomatous inflammation, is characteristic of localized and systemic GPA, but not MPA. This review summarizes new knowledge regarding granuloma in the head and neck region of AAV, its histomorphological equivalents in the upper and lower respiratory tract, and evidence for a granulomatous phenotype of a persistent localized GPA variant. This comprises the development of disease activity and damage scores for extravascular lesions in the ear, nose, and throat (ENT) regions, and imaging techniques. In addition, findings linking extravascular manifestations to granulomatous inflammation are described. We hypothesize that, as for ANCA, necrotizing granulomatous inflammation and its clinical manifestations are discriminators, assisting subclassification of AAV and/or GPA subphenotypes which will be useful both for designing clinical trials and for treating patients successfully.