ANCA-Associated Vasculitis: Practical Issues in Management.

ANCA associated vasculitides are multi-system autoimmune diseases which are increasing in prevalence. In this review we will discuss the clinical manifestations and review the management options. We highlight the various trials of induction and maintenance therapy and discuss the areas of unmet need. These include understanding which patients are at highest risk of relapse, clinical adaptation of improved biomarkers of disease activity and tools to discuss long term prognosis.

Plasma exchange as an adjunctive therapy in anti-neutrophil cytoplasm antibody-associated vasculitis.

INTRODUCTION: We summarize evidence for the role of therapeutic plasma exchange (TPE) in the treatment of anti-neutrophil cytoplasm antibody (ANCA)-associated vasculitis (AAV). TPE rapidly removes ANCA IgG, complement and coagulation factors important in the pathogenesis of AAV. TPE has been used in patients with rapidly deteriorating renal function to achieve early disease control, allowing time for immunosuppressive agents to prevent resynthesis of ANCA. The PEXIVAS trial challenged the utility of TPE in AAV, as it did not show benefit of adjunctive TPE on a combined end point of end stage kidney disease (ESKD) and death. AREAS COVERED: We analyze data from PEXIVAS and other trials of TPE in AAV, an up-to-date meta-analysis, and recently published large cohort studies. EXPERT OPINION: There remains a role for the use of TPE in AAV in certain groups of patients, in particular those with severe renal involvement (Cr >500 µmol/L or dialysis-dependent). It should be considered in patients with Cr >300 µmol/L and rapidly deteriorating function, or with life-threatening pulmonary hemorrhage. A separate indication is patients double positive for anti-GBM antibodies and ANCA. TPE may have the greatest benefit as part of steroid-sparing immunosuppressive treatment strategies.

Defensin Interactions in Relation to Monoclonal and Disease-Related Proteinase 3 Antibodies Binding at the Catalytic Site.

Proteinase 3 (PR3) is a neutrophil granulocyte enzyme and an autoantigen found in several forms of vasculitis. Due to the diagnostic and clinical importance of antibodies (Abs) to PR3, it is important to characterize the protein and the nature of its epitopes. Here, we have characterized PR3 monoclonal antibodies (MAbs) and disease-associated Abs and their dependency on the PR3 structure and modifications, especially interactions with α-defensins. Three MAbs (HYB 172-01, 172-04, 172-05), which bind to PR3 in its native and denatured forms and provide the disulphide bridges, were intact. α-1-antitrypsin (AT) binds to purified human neutrophil granulocyte PR3 and inhibits its proteolytic activity, towards a small synthetic peptide substrate and a large protein substrate (casein). AT also inhibited the binding of the three MAbs to PR3, indicating that they bind in a region affected by AT binding. However, the MAbs did not inhibit PR3 proteolytic activity with a small substrate, showing that they bound at the active site without restricting access to the substrate cleft. Patient-derived Abs showed essentially the same characteristics as the MAbs, with important implications for vasculitis diagnostics and pathophysiology. Current findings illustrate that PR3 epitopes depend on the three-dimensional structure of the PR3/defensin complex, and that the epitopes depend to a smaller or larger degree on PR3/defensin associations.

Computed tomography findings of paranasal sinuses in patients with eosinophilic granulomatosis with polyangiitis: Comparison with other eosinophilic sinus diseases and clinical relevance of their severity.

BACKGROUND: Although paranasal sinuses are one of the most representative organs affected by eosinophilic granulomatosis with polyangiitis (EGPA), they have not been studied sufficiently. The aim of this study was to compare computed tomography (CT) findings in paranasal sinuses of EGPA with those of other eosinophilic sinus diseases and elucidate the clinical relevance of their severity. METHODS: CT findings of paranasal sinuses in EGPA patients prior to therapeutic intervention (n = 30) were evaluated using the Lund-Mackay staging (LMS) system and compared with those of three control diseases [(NSAID-exacerbated respiratory disease (N-ERD), aspirin-tolerant asthma, and eosinophilic chronic rhinosinusitis without asthma (ECRS)]. We divided EGPA patients into three groups based on their LMS scores and examined their association with disease manifestation. RESULTS: Total scores of the LMS system in EGPA were significantly lower than those of N-ERD and ECRS without asthma. There was a large variation in total LMS scores in EGPA, suggesting considerable heterogeneity of their sinus lesions. Although EGPA with low LMS system scores showed only minor findings in maxillary and anterior ethmoid regions, those with high LMS system scores were characterized by high scores in the ostiomeatal complex. However, the frequencies of patients with a Five-Factor Score ≥2 and with cardiac involvement were significantly higher for EGPA with low LMS system scores. CONCLUSIONS: Although paranasal sinus lesions in EGPA were less severe than those of other eosinophilic sinus diseases, their milder CT findings may be associated with a higher frequency of extra-respiratory organ involvement.

CanVasc consensus recommendations for the use of avacopan in antineutrophil cytoplasm antibody-associated vasculitis: 2022 addendum.

OBJECTIVE: In 2020, the Canadian Vasculitis Research Network (CanVasc) published their updated recommendations for the management of ANCA-associated vasculitides (AAV). The current addendum provides further recommendations regarding the use of avacopan in AAV based on a review of newly available evidence. METHODS: An updated systematic literature review on avacopan (formerly, CCX168) using Medline, Embase, and the Cochrane Library was performed for publications up to September 2022. New recommendations were developed and categorized according to the EULAR grading levels, as done for previous CanVasc recommendations. A modified Delphi procedure and videoconferences were used to reach ≥80% consensus on the inclusion, wording and grading of each recommendation. RESULTS: Three new recommendations were developed. They focus on avacopan therapy indication and duration, as well as timely glucocorticoid tapering. CONCLUSION: These 2022 addended recommendations provide rheumatologists, nephrologists and other specialists caring for patients with AAV with guidance for the use of avacopan, based on current evidence and consensus from Canadian experts.

Chemoprophylaxis against Pneumocystis jirovecii pneumonia in Japanese patients with ANCA-associated vasculitis: An observational study.

OBJECTIVES: This study investigated the current practice of prophylactic treatment against Pneumocystis jirovecii pneumonia (PCP) and its effectiveness in patients with anti-neutrophil cytoplasmic antibody-associated vasculitis (AAV). METHODS: This study included 319 patients registered from 53 institutions in Japan and newly diagnosed with AAV. During the 2-year observation period, we examined the frequency of usage, effectiveness and safety of prophylactic drugs against PCP. RESULTS: Most patients received prophylactic drugs against PCP with the initiation of immunosuppressive agents, and >50% of them remained on chemoprophylaxis against PCP at 2 years after. The initial daily dose of oral prednisolone and the proportion of cyclophosphamide administration were higher in patients who received chemoprophylaxis against PCP than in those who did not. PCP occurred in nine patients (3%) and resulted in the death of four. The incidence rate of PCP in patients who received chemoprophylaxis was 1.13/100 patient-years (95% confidence interval, 0.38-2.68) and that in those who did not was 2.74 (1.04-6.02). The incidence rate ratio was 0.41 (0.11-1.53). CONCLUSIONS: The markedly low incidence of PCP may be attributed to the continuous chemoprophylaxis against PCP received by >50% of Japanese patients with AAV, although the effectiveness of chemoprophylaxis against PCP was not statistically confirmed.

Anti-glomerular basement membrane vasculitis.

Antiglomerular basement membrane disease (anti-GBM) is a rare life-threatening autoimmune vasculitis that involves small vessels and it is characterized by circulating autoantibodies directed against type IV collagen antigens expressed in glomerular and alveolar basement membrane. The typical clinical manifestations are the rapidly progressive glomerulonephritis and the alveolar hemorrhage. The diagnosis is usually confirmed by the detection of anti-GBM circulating antibodies. If not rapidly recognized, anti-GBM disease can lead to end stage kidney disease (ESKD). An early diagnosis and prompt treatment with immunosuppressive therapies and plasmapheresis are crucial to prevent a poor outcome. In this review, we discuss the primary form of anti-GBM (the so called Goodpasture syndrome) but also cases associated with other autoimmune diseases such as antineutrophil-cytoplasmic-antibody (ANCA) vasculitis, membranous nephropathy, IgA nephritis and systemic lupus erythematosus (SLE), as well as the few cases of anti-GBM vasculitis complicating kidney transplantation in the Alport syndrome.

More than a 'Hundred Days War': Persistent SARS-CoV-2 infection in a patient with ANCA-associated vasculitis.

BACKGROUND: Few reports exist on the characteristics and outcomes of persistent severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection in immunocompromised hosts. METHODS: A 49-year-old patient with granulomatosis with polyangiitis (GPA) and a renal transplant experienced multiple hospitalizations for coronavirus disease 2019 (COVID-19) pneumonia and relapses between October 2020 and February 2021. Careful chart review of medical history, hospitalizations, and microbiological testing including SARS-CoV-2 cycle threshold values, therapies, and imaging was undertaken. SARS-CoV-2 genome sequencing was performed in five viral samples to distinguish persistent infection from re-infection with a different strain. RESULTS: Sequencing confirmed that all samples tested were from the same viral lineage, indicating a long-term, persistent infection rather than re-infection with a new strain. The patient ultimately stabilized after two courses of remdesivir plus dexamethasone, replacement intravenous immunoglobulin, and bamlanivimab. Rituximab maintenance therapy for vasculitis remains on hold. CONCLUSIONS: SARS-CoV-2 may persist for several months in immunocompromised hosts and may go unrecognized as an ongoing active infection. More studies are needed to determine how to optimize COVID-19 treatment in this vulnerable population.

HISTORIQUE: Il existe peu de rapports sur les caractéristiques et les issues de l'infection par le coronavirus 2 du syndrome respiratoire aigu sévère (SRAS-CoV-2) chez les hôtes immunodéprimés. MÉTHODOLOGIE: UNE PATIENTE de 49 ans receveuse d'une transplantation rénale atteinte d'une granulomatose avec polyangéite a été hospitalisée à de multiples reprises à cause d'une pneumonie à maladie à coronavirus 2019 (COVID-19) et de récidives entre octobre 2020 et février 2021. Les chercheurs ont exécuté une analyse attentive du dossier pour connaître l'histoire médicale de la patiente, les hospitalisations et les tests microbiologiques effectués, y compris les valeurs seuils du cycle du SRAS-CoV-2, les traitements et les techniques d'imagerie. Ils ont procédé au séquençage du génome du SRAS-CoV-2 dans cinq prélèvements viraux pour distinguer l'infection persistante de la réinfection par une souche différente. RÉSULTATS : Le séquençage a confirmé que tous les prélèvements effectués provenaient de la même lignée virale, ce qui détermine une infection persistante prolongée plutôt qu'une réinfection par une nouvelle souche. L'état de la patiente a fini par se stabiliser après deux traitements au remdésivir combiné à de la dexaméthasone, une thérapie de substitution par immunoglobuline intraveineuse et du bamlanivimab. Un traitement d'entretien de la vasculite au rituximab demeure en suspens. CONCLUSIONS: Le SRAS-CoV-2 peut persister plusieurs mois chez les hôtes immunodéprimés, et un état d'infection active continue peut passer inaperçu. Plus d'études devront être réalisées pour déterminer le moyen d'optimiser le traitement de la COVID-19 dans cette population vulnérable.

Negative anti-neutrophil cytoplasmic antibodies and eosinophilic granulomatosis with polyangiitis accompanied by cough variant asthma: a case report.

Eosinophilic granulomatosis with polyangiitis (EGPA), formerly called Churg-Strauss syndrome, is a rare chronic necrotizing eosinophilic granulomatous inflammatory disease characterized by eosinophil-rich granulomatous inflammation and small- to medium-size vessel vasculitis associated with bronchial asthma and eosinophilia, which is positive for anti-neutrophil cytoplasmic antibody (ANCA) in approximately 50-70% of cases. We report a case of a 23-year-old woman was admitted to our hospital because of a of small vesicles on both lower limbs and a 4-month history of small scattered skin rash with pruritus V6 on both lower limbs four-month history of scattered skin rash with pruritus. Laboratory data from peripheral blood revealed leukocytosis, eosinophilia, thrombocytosis, hyperfibrinolysis, and mild renal injury. Her ANCA was negative, and the skin pathological examination showed granuloma lesions with eosinophils, while elevated eosinophils were also found in the bone marrow. EGPA was diagnosed. On the other hand, the patient had 2-year-long rhinosinusitis, 9-month-long nephrotic syndrome, and 1-month-long dry cough, which might be a type of asthma. With steroid therapy followed by systemic immunomodulatory therapy, the patient's symptoms were relieved. Our case report and literature review highlight the importance of recognizing cough variant asthma as an initial presenting symptom of EGPA, providing an opportunity for early diagnosis and treatment to reduce the risk of further disease progression and morbidity.

The role of trimethoprim/sulfametoxazole in reducing relapses and risk of infections in ANCA-associated vasculitis: a meta-analysis.

OBJECTIVES: To assess available evidence from randomized controlled trials (RCTs) and observational studies including a control group regarding the role of trimethoprim/sulfametoxazole (TMP/SMX) in reducing the relapse rate in patients with granulomatosis with polyangiitis (GPA) and the risk of infections in patients with ANCA-associated vasculitis (AAV). METHODS: MEDLINE, EMBASE, The Cochrane Library databases, Scopus, Web of Science and ClinicalTrials.gov were searched from inception until 15 January 2020 to identify controlled studies assessing the role of TMP/SMX in reducing the rate of relapse in patients with GPA (primary outcome) and the number and/or severity of infections in patients with AAV (secondary outcome). Two reviewers independently selected eligible studies and extracted data. Cumulative risk ratios (RRs) with 95% CI were calculated using a random effect meta-analysis. RESULTS: Eight studies were selected out of 2907 records. Seven studies (520 patients) (of which two were RCTs) assessed the role of TMP/SMX in the relapse rate in patients with GPA. TMP/SMX was not associated with a reduced risk of relapse (RR = 1.15, 95% CI: 0.51, 2.55; I2 = 78.5%; P < 0.001). Sensitivity analysis according to the dose of TMP/SMX (960 mg twice daily vs three times/week) confirmed the results. One retrospective cohort study (192 patients) was identified demonstrating a significant reduction of severe infections in patients with AAV receiving prophylaxis with TMP/SMX in association with rituximab. CONCLUSION: TMP/SMX was not associated with a reduced risk of relapse in patients with GPA. TMP/SMX might be useful in the reduction of infectious complications. PROSPERO DATABASE REGISTRATION CODE: CRD42019118983.

Muscle biopsy in anti-neutrophil cytoplasmic antibody-associated vasculitis: diagnostic yield depends on anti-neutrophil cytoplasmic antibody type, sex and neutrophil count.

OBJECTIVES: This study aimed to examine the sensitivity of muscle biopsy (MB) in ANCA-associated vasculitis (AAV), identify factors predicting MB positivity and assess the prognostic value of a positive MB. METHODS: We conducted a single-centre retrospective study of AAV with an MB performed at diagnosis. AAV classification [granulomatosis with polyangiitis (GPA), microscopic polyangiitis (MPA), eosinophilic granulomatosis with polyangiitis (EGPA)] followed the European Medicines Agency algorithm. A logistic regression model was used to identify the factors associated with MB positivity. Survival curves were generated using the Kaplan-Meier method. RESULTS: Among 276 AAV patients (1995-2018), 101 had an MB. Seventy-eight patients were included: 33 with GPA, 25 with MPA and 20 with EGPA. MB samples were positive in 45 cases (58%): 17 GPA, 16 MPA and 12 EGPA. Univariate analysis focussed on GPA and MPA, revealed that the MB yield was higher in females [22/31 (71%) vs 11/27 (41%); P = 0.02] and in anti-MPO patients [25/37 (68%) vs 6/19 (32%) for anti-PR3; P = 0.01]. By multivariate analysis, three factors predicted MB positivity: anti-MPO ANCA [odds ratio (OR) 10.67 (CI 2.09, 81.68)], female sex [OR 5.3 (CI 1.16, 32.35)] and neutrophil count [OR 1.33 (CI 1.07, 1.8)]. MB positivity had no impact on relapse, death or end-stage renal disease-free survival. CONCLUSIONS: MB is a safe and efficient diagnostic tool for AAV. Predictors of MB yield include ANCA type, sex and neutrophil count. MB cannot substitute for kidney biopsy when indicated, but should be considered in other cases.

Update on eosinophilic granulomatosis with polyangiitis.

Eosinophilic granulomatosis with polyangiitis (EGPA) (formerly Churg-Strauss syndrome) is a rare form of anti-neutrophil cytoplasm antibody (ANCA)-associated vasculitis characterized by eosinophil-rich granulomatous inflammation and small to medium-size vessel vasculitis associated with bronchial asthma and eosinophilia. Its rarity and unique features such as eosinophilic inflammation have delayed progress of research regarding EGPA for several years, compared to other forms of ANCA-associated vasculitis. However, recently, attention to EGPA as a research subject has been gradually increasing. To resolve problems in existing criteria for EGPA, new classification criteria for EGPA generated by a large international cohort will be launched and is being expected to accelerate future studies. Pathogenesis and roles of ANCA in EGPA are still largely unknown; however, it has been reported that glomerulonephritis is more frequent in ANCA-positive patients than in ANCA-negative patients, while heart failure is more frequent in ANCA-negative patients than in ANCA-positive patients. In addition, a recent genome-wide association study has suggested the presence of two genetically distinct subgroups of EGPA, which correspond to ANCA-positive and -negative subgroups. Although responses to glucocorticoids in EGPA are generally good, patients with EGPA often experience a relapse. Currently, there is no standard therapy for EGPA based on accumulation of clinical trial results. Recently, clinical benefits of mepolizumab for EGPA were proved by a randomized controlled trial and mepolizumab was approved for EGPA. In addition, various new drugs are under evaluation. To find optimal use of these drugs and to resolve unmet needs, such as relapse prevention, will be needed in future.

Clinical outcome in anti-neutrophil cytoplasmic antibody-associated vasculitis and gene variants of 11ß-hydroxysteroid dehydrogenase type 1 and the glucocorticoid receptor.

OBJECTIVES: We aimed to investigate whether five potential functional haplotypes of the glucocorticoid receptor (GR) gene and a single-nucleotide polymorphism of 11ß-hydroxysteroid dehydrogenase type 1 (HSD11B1) are associated with clinical outcome in ANCA-associated vasculitis. METHODS: Patients diagnosed with ANCA-associated vasculitis (n = 241) were genotyped for five polymorphisms of the GR gene and one polymorphism of the HSD11B1 gene. GR gene haplotypes were predicted based on genotyping results. Relapse-free survival, mortality, renal survival, metabolic adverse events and infections were compared between carriers and non-carriers of GR haplotypes and the HSD11B1 genotype. RESULTS: Carriers of haplotype 4 (ER22/23EK + 9ß+TthIII1) of GR had a significantly higher 5-year mortality risk [hazard ratio (HR) 4.5 (95% CI 1.6, 12.8)] and had a higher risk of developing end-stage renal disease [HR 7.4 (95% CI 1.9, 28.7)]. Carriers of a minor variant of HSD11B1 more frequently experienced relapse [HR 2.5 (95% CI 1.5, 4.1)] except if they also carried haplotype 1 (BclI) of GR. Homozygous carriers of haplotype 1 had a higher risk of developing dyslipidaemia [HR 4.1 (95% CI 1.8, 9.6)]. The occurrence of infections did not differ between GR haplotypes and HSD11B1 genotypes. CONCLUSION: Haplotypes 1 and 4 of GR and a polymorphism of the HSD11B1 gene were associated with clinically relevant inflammatory and metabolic outcomes in ANCA-associated vasculitis.

Pathogenesis and treatment of ANCA-associated vasculitis-a role for complement.

The antineutrophil cytoplasm autoantibody (ANCA)-associated vasculitides (AAV), although rare in childhood, can have devastating effects on affected organs, especially the kidney. In this review we present an update on the pathogenesis and treatment of ANCA vasculitis, with a particular emphasis on the role of the alternative pathway of complement. The rationale and evidence for the current treatment strategies are summarized. Targeting the activation of neutrophils by the anaphylatoxin C5a may serve as an additional therapeutic strategy, however the results of clinical studies are awaited.

Avoidance of Harm From Treatment for ANCA-Associated Vasculitis.

Purpose of review With established immunosuppressant treatment regimens for anti-neutrophil cytoplasm antibody-associated vasculitides (AAV), prognosis has significantly improved. The mainstay of treatment still comprises high-dose corticosteroids and cyclophosphamide for severe forms, although rituximab is being increasingly utilised instead of cyclophosphamide as induction therapy. AAV patients experience an excess of infections, malignancies and cardiovascular events as compared to the general population, which is a combination of the systemic inflammatory process associated with vasculitis and the adverse events from treatment. Recent findings Successful therapy should focus on suppressing disease activity and minimising treatment-related toxicity. Infection is the largest contributor to morbidity and mortality in the first year of treatment, and annual pneumococcal and influenza vaccinations, Pneumocystis jiroveci prophylaxis and tuberculosis (TB) and Hepatitis B virus screening are advised. Patients on high-dose corticosteroid treatment should have regular blood sugar monitoring, a FRAX assessment with vitamin D and calcium supplementation, consideration of prophylaxis for gastric ulcers and a cardiovascular risk assessment. Patients who are treated with cyclophosphamide could also receive MESNA to reduce the risk of chemical cystitis. Cyclophosphamide, methotrexate and azathioprine all require blood monitoring schedules due to the risk of bone marrow suppression, liver and renal toxicity. Hypogammaglobulinaemia is a recognised risk of rituximab treatment. Patients of reproductive age need to be counselled on the infertility risks with cyclophosphamide and the teratogenicity associated with it, methotrexate and mycophenolate mofetil. Summary A greater focus on identifying clinical and biological markers that will help identify those patients at greatest risk of relapse, e.g. GPA and PR3-ANCA specificity, from those patients at greatest risk of toxicity, e.g. increasing age and declining GFR, is required to allow treatment to be tailored accordingly.

Patients double-seropositive for ANCA and anti-GBM antibodies have varied renal survival, frequency of relapse, and outcomes compared to single-seropositive patients.

Co-presentation with both ANCA and anti-GBM antibodies is thought to be relatively rare. Current studies of such 'double-positive' cases report small numbers and variable outcomes. To study this further we retrospectively analyzed clinical features and long-term outcomes of a large cohort of 568 contemporary patients with ANCA-associated vasculitis, 41 patients with anti-GBM disease, and 37 double-positive patients with ANCA and anti-GBM disease from four European centers. Double-positive patients shared characteristics of ANCA-associated vasculitis (AAV), such as older age distribution and longer symptom duration before diagnosis, and features of anti-GBM disease, such as severe renal disease and high frequency of lung hemorrhage at presentation. Despite having more evidence of chronic injury on renal biopsy compared to patients with anti-GBM disease, double-positive patients had a greater tendency to recover from being dialysis-dependent after treatment and had intermediate long-term renal survival compared to the single-positive patients. However, overall patient survival was similar in all three groups. Predictors of poor patient survival included advanced age, severe renal failure, and lung hemorrhage at presentation. No single-positive anti-GBM patients experienced disease relapse, whereas approximately half of surviving patients with AAV and double-positive patients had recurrent disease during a median follow-up of 4.8 years. Thus, double-positive patients have a truly hybrid disease phenotype, requiring aggressive early treatment for anti-GBM disease, and careful long-term follow-up and consideration for maintenance immunosuppression for AAV. Since double-positivity appears common, further work is required to define the underlying mechanisms of this association and define optimum treatment strategies.

Are the 1990 American College of Rheumatology vasculitis classification criteria still valid?

Objectives: Advances in diagnostic techniques have led to better distinction between types of vasculitis, potentially affecting the utility of the 1990 ACR classification criteria for vasculitis. This study tested the performance of these criteria in a contemporary vasculitis cohort. Methods: The Diagnosis and Classification in Vasculitis Study provided detailed clinical, serological, pathological and radiological data from patients with primary systemic vasculitis and clinical context-specific comparator conditions. Fulfilment of six ACR criteria sets and their diagnostic performance was evaluated in patients with a given type of vasculitis and its comparator conditions. Results: Data from 1095 patients with primary systemic vasculitis and 415 with comparator conditions were available. For classification, sensitivities and specificities for ACR classification criteria were, respectively, 81.1% and 94.9% for GCA; 73.6% and 98.3% for Takayasu's arteritis; 65.6% and 88.7% for granulomatosis with polyangiitis; 57.0% and 99.8% for eosinophilic granulomatosis with polyangiitis; 40.6% and 87.8% for polyarteritis nodosa; 28.9% and 88.5% for microscopic polyangiitis; and 72.7% and 96.3% for IgA-vasculitis. Overall sensitivity was 67.1%. Of cases identified by their respective criteria, 16.9% also met criteria for other vasculitides. Diagnostic specificity ranged from 64.2 to 98.9%; overall, 113/415 comparators (27.2%) fulfilled at least one of the ACR classification criteria sets. Conclusion: Since publication of the ACR criteria for vasculitis, the sensitivity for each type of vasculitis, except GCA, has diminished, although the specificities have remained high, highlighting the need for updated classification criteria.

Neutrophil extracellular traps as a potential source of autoantigen in cocaine-associated autoimmunity.

Objective: Exposure to illicit cocaine and its frequent adulterant, levamisole, is associated with ANCAs targeting neutrophil elastase (NE), neutropenia and vasculitic/thrombotic skin purpura. The mechanisms of cocaine/levamisole-associated autoimmunity (CLAA) are unknown. The aim of this study was to assess the ability of cocaine and levamisole to induce the release of neutrophil extracellular traps (NETs), a potential source of autoantigen and tissue injury. Methods: We performed quantitative and qualitative assessment of NET formation in neutrophils from healthy donors exposed to either drug in vitro . In addition, IgG from sera of individuals with CLAA (CLAA-IgG) was assessed for its ability to enhance formation of, and to bind to, drug-induced NETs. Results: Both cocaine and levamisole could induce formation of NETs enriched in NE and, potentially, inflammatory mitochondrial DNA. Both drugs could also augment simultaneous release of B cell-activating factor belonging to the TNF family (BAFF). CLAA-IgG, but not IgG from healthy individuals, could potentiate drug-induced NETosis. Furthermore, CLAA-IgG, but not ANCA + control IgG, bound to drug-induced NETs in a pattern consistent with NE targeting. Conclusion: Both cocaine and levamisole may contribute to the development of ANCAs by inducing release of potentially inflammatory NETs in association with NE autoantigen and BAFF. Enhancement of drug-induced NET release by CLAA-IgG provides a potential mechanism linking vasculitis/pupuric skin disease to acute drug exposure in patients with CLAA. Further study of this under-recognized form of autoimmunity will be likely to provide mechanistic insight into ANCA-associated vasculitis and other diseases associated with NETosis.