Antimyeloperoxidase antibodies are a useful marker of disease activity in antineutrophil cytoplasmic antibody-associated vasculitides

Progression to ANCA-associated vasculitis in patients with idiopathic interstitial pneumonia and positive ANCA

OBJECTIVE

This study explored the development of antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) and its risk factors in patients with idiopathic interstitial pneumonia (IIP) and positive ANCA results.

METHODS

Data of patients diagnosed with IIP with positive ANCA results at a single tertiary center in South Korea were retrospectively reviewed from January 2013 to August 2023. Cox regression analysis was performed to identify variables associated with AAV occurrence following IIP diagnosis. Kaplan-Meier curves were employed to investigate the relationship between autoantibodies and the occurrence of AAV.

RESULTS

In a cohort of 154 IIP-diagnosed patients with positive ANCA results but without AAV, 10.4 % of them eventually developed AAV. The AAV and non-AAV groups did not significantly differ by sex, age, smoking status, urinalysis, or chest computed tomography findings. All the patients who subsequently developed AAV were anti-myeloperoxidase (MPO) positive, while 48.8 % of the non-AAV patients were anti-MPO positive (P < 0.001). Rheumatoid factor (RF) positivity differed significantly (62.5 % vs. 29.2 %, P = 0.007) between the AAV and non-AAV groups. Multivariate Cox regression and Kaplan-Meier analyses revealed RF (HR 4.02; P = 0.004) and anti-MPO (HR 38.10; P < 0.001) positivity as risk factors associated with AAV occurrence.

CONCLUSION

Approximately 10 % of ANCA-positive IIP patients developed AAV after an IIP diagnosis. Anti-MPO or co-occurring positive RF poses a significant risk for subsequent AAV occurrence. This emphasizes the importance of careful monitoring in patients with high-risk antibody profiles, even if the complete features of AAV are not present at IIP diagnosis.

Diagnostic accuracy of antineutrophil cytoplasmic antibodies (ANCA) in predicting relapses of ANCA-associated vasculitis: systematic review and meta-analysis

Relapse in antineutrophil cytoplasmic antibodies (ANCA)-associated vasculitis (AAV) is associated with significant morbidity and mortality. Utility of ANCA for prediction of relapses is still controversial. PubMed/MEDLINE, Scopus, and WebOfScience were searched, screened and confirmed for inclusion [PROSPERO No: CRD42020220308]. Studies measuring serial ANCA by ELISA or indirect immunofluorescence (IF), reporting relapses with sufficient data to calculate sensitivity and specificity were included. Diagnostic odds ratio (OR), sensitivity, specificity and likelihood ratios (LR) were synthesized using a bivariate mixed-effect regression model. Sub-group analysis included a comparison between ELISA and IIF, anti-myeloperoxidase (MPO) and -proteinase 3(PR3), and type of rise in ANCA. For meta-analysis of survival outcomes, hazard ratios were synthesized using a random-effect model. QUADAS-2 was used for assessing quality of studies, I² statistic for heterogeneity Begg's test for publication bias. 2946 abstracts and 43 full-texts were reviewed to identify 26 eligible studies that included 2623 patients with AAV and 848 relapses. Overall heterogeneity was high [I² = 99%] and the overall risk of bias was low to moderate. ANCA positivity by either ELISA or immunofluorescence for predicting relapse of AAV had a sensitivity of 0.70(95% CI 0.58-0.81), specificity of 0.66(0.55-0.76), positive LR of 2.1(1.6-42.7) and negative LR of 0.44(0.30-0.60). ELISA performed marginally better [OR: 5(3-7)] than IIF [OR: 4(2-9)] with similar sensitivity, specificity, PLR and NLR. The area under the curve for PR3 was 0.74(0.7-0.77), while that for MPO was not computed as the number of eligible studies was only three. In the survival analysis, the hazard ratio for relapse was 3.11(1.7-5.65). The meta-analysis shows modest accuracy of ANCA in predicting relapses of ANCA vasculitis and supports the use of serial ANCA monitoring as a biomarker for relapse.

Maintenance of Remission and Risk of Relapse in Myeloperoxidase-Positive ANCA-Associated Vasculitis with Kidney Involvement

BACKGROUND

The optimal strategy for remission-maintenance therapy in patients with myeloperoxidase-ANCA (MPO-ANCA)-associated vasculitis is not established. Defining parameters to guide maintenance therapy is required.

METHODS

This was a retrospective cohort study of all patients with MPO-ANCA-associated vasculitis (microscopic with polyangiitis and granulomatosis with polyangiitis) and GN followed at the Mayo Clinic between 1996 and 2015. Relapse rate, MPO-ANCA status, and remission-maintenance therapies were reviewed. Logistic regression models, Kaplan-Meier method, and Cox proportional hazards regression models were applied.

RESULTS

We analyzed 159 patients with active MPO-ANCA-associated vasculitis with GN. Sixty-six (42%) patients had at least one relapse, and 52 (33%) relapsed before 60 months. Patients with MPO-ANCA who became persistently negative did not relapse (hazard ratio [HR], 0.03; 95% confidence interval [95% CI], 0.002 to 0.431; P =0.01). The reappearance of MPO-ANCA was associated with a higher risk of relapse (HR, 1.91; 95% CI, 1.109 to 3.293; P =0.02). Immunosuppression was withdrawn in 80 (50%) patients, and this was less likely in those who received cyclophosphamide for remission induction or in patients with persistently positive MPO-ANCA (odds ratio [OR], 0.44; 95% CI, 0.228 to 0.861; P =0.02 and OR, 0.42; 95% CI, 0.213 to 0.820; P =0.01, respectively). Relapse frequency was not different between patients with persistently positive MPO-ANCA and patients with MPO-ANCA reappearance (44% versus 39%, P =0.49), irrespective of remission-maintenance treatment. Ear, nose, and throat involvement (OR, 6.10; 95% CI, 1.280 to 29.010; P =0.02) and MPO-ANCA reappearance (OR, 9.25; 95% CI, 3.126 to 27.361; P <0.001) were independently associated with relapse after treatment withdrawal.

CONCLUSIONS

Patients persistently MPO-ANCA negative are at low risk for relapse even without remission-maintenance therapy. Persistence or subsequent reappearance of MPO-ANCA is associated with a higher risk of relapse.

PODCAST

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Old known and possible new biomarkers of ANCA-associated vasculitis

Antineutrophil cytoplasm antibody (ANCA)-associated vasculitis (AAV) comprises a group of multisystem disorders involving severe, systemic, small-vessel vasculitis with short- and long term serious and life-threating complications. Despite the simplification of treatment, fundamental aspects concerning assessment of its efficacy and its adaptation to encountered complications or to the relapsing/remitting/subclinical disease course remain still unknown. The pathogenesis of AAV is complex and unique, and despite the progress achieved in the last years, much has not to be learnt. Foremost, there is still no accurate marker enabling us to monitoring disease and guide therapy. Therefore, the disease management relays often on clinical judgment and follows a" trial and error approach". In the recent years, an increasing number of new molecules s have been explored and used for this purpose including genomics, B- and T-cell subpopulations, complement system factors, cytokines, metabolomics, biospectroscopy and components of our microbiome. The aim of this review is to discuss both the role of known historical and clinically established biomarkers of AAV, as well as to highlight potential new ones, which could be used for timely diagnosis and monitoring of this devastating disease, with the goal to improve the effectiveness and ameliorate the complications of its demanding therapy.

The effect of achieving serological remission on subsequent risk of relapse, end-stage renal disease and mortality in ANCA-associated vasculitis: a target trial emulation study

OBJECTIVE

To evaluate the effect of achieving a negative postinduction antineutrophil cytoplasmic antibody ANCA) assay on the risk of relapse, end-stage renal disease (ESRD) and death in ANCA-associated vasculitis (AAV).

METHODS

We emulated a target trial using observational data from the Mass General Brigham AAV cohort comparing patients who achieved versus did not achieve serological remission (negative ANCA assay) within 180 days of induction. Outcomes were relapse, ESRD or death within 5 years, obtained from medical records, the US Renal Data System and the National Death Index. We placed a 'clone' of each patient in both trial arms, censored those deviating from their assigned protocol and weighted each by the inverse probability of censoring. Outcomes were assessed by pooled logistic regression.

RESULTS

The study included 506 patients with AAV. The mean age was 61 years (SD 18) and the majority were women (58%), white (87%), myeloperoxidase-ANCA+ (72%) and had renal involvement (68%). Rituximab (59%) or cyclophosphamide (33%) was most often used for induction treatment. Within 5 years, 81 (16%) died, 51 (10%) had ESRD and 64 (13%) had relapse. Patients treated to a negative ANCA assay within 180 days had HR 0.55 (95% CI 0.38 to 0.81) for relapse and HR 0.87 (95% CI 0.61 to 1.25) for the composite of ESRD or death within 5 years.

CONCLUSIONS

In this emulated target trial from a large AAV cohort, achieving serological remission within 180 days of induction was associated with lower risk of relapse, but no statistically significant difference in ESRD or mortality outcomes.

Do Relapses Follow ANCA Rises? A Systematic Review and Meta-Analysis on the Value of Serial ANCA Level Evaluation

Objectives

ANCA-vasculitis (AAV) patients frequently suffer from relapses and risk subsequent organ damage. There is much debate on the value of serial ANCA level evaluation to monitor disease activity. We aimed to evaluate the association between ANCA rises and disease relapses at (I) moment of the rise, (II) within 6 months or (III) within a year from the rise.

Methods

3 databases (MEDLINE, EMBASE, COCHRANE) were searched from 1993 through September 2021. We included studies that reported relapse incidence within 12 months after an ANCA rise measured by antigen-specific immunoassays in peripheral blood of AAV patients in remission. Quality assessment was performed using QUADAS-2. Finally, a meta-analysis was carried out to estimate average OR using a random effects model.

Results

Twenty unique studies were included. The methodological quality was limited due to risk of selection bias. An ANCA rise often preceded a disease relapse within 6 months (OR 3.65, 95% CI 1.66–8.03) and less often within 12 months (OR 2.88, 95% CI 1.21–6.88), while it was not indicative of a concurrent relapse (OR 0.13, 95% CI 0.03–0.53). Once a relapse is diagnosed, ANCA is significantly more often present than not (OR 10.80, 95% CI 3.82–30.55). As expected based on clinical, technical and methodological variability between studies, there was substantial heterogeneity across studies in all analyses (I2 = 70–87%).

Conclusion

In previously ANCA-positive patients, the ANCA test is often positive upon clinical suspicion of a disease relapse. Patients with a rise in ANCA are at risk of encountering disease relapses in the upcoming 6 or 12 months.

Anti-Inflammatory and/or Anti-Fibrotic Treatment of MPO-ANCA-Positive Interstitial Lung Disease: A Short Review

The presence of a lung lesion is common in microscopic polyangiitis (MPA), and interstitial lung disease (ILD) can lead to a poor prognosis. Although myeloperoxidase antineutrophil cytoplasmic antibodies (MPO-ANCA) are often present in patients with MPA, patients with ILD and MPO-ANCA positivity but without other manifestations of systemic vasculitis have also been reported. Therefore, the possible association between MPO-ANCA, MPA, and idiopathic ILD remains unclear. This problematic matter has influenced the treatment strategy of MPO-ANCA-positive ILD patients without systemic vasculitis. Clinicians should undertake treatment with careful consideration of the four major causes of death in MPO-ANCA-positive ILD: acute exacerbation of ILD, progressive lung fibrosis, infectious comorbidities, and diffuse alveolar hemorrhage. Further, clinicians need to carefully judge whether inflammation or fibrosis is the dominant condition with reference to the patient’s clinical domain and radiopathological lung features. Recently, anti-fibrotic agents such as nintedanib and pirfenidone were shown to be effective in treating various etiologies associated with ILD and have thus led to the widening of treatment options. In this review, the clinical characteristics, radiopathology, prognosis, and therapeutic options in patients with MPO-ANCA-positive ILD are summarized using limited information from previous studies.

Serum Biomarkers of Disease Activity in Longitudinal Assessment of Patients with ANCA-Associated Vasculitis

OBJECTIVE

Improved biomarkers of current disease activity and prediction of relapse are needed in antineutrophil cytoplasmic antibody-associated vasculitis (AAV). For clinical relevance, biomarkers must perform well longitudinally in patients on treatment and in patients with nonsevere flares.

METHODS

Twenty-two proteins were measured in 347 serum samples from 74 patients with AAV enrolled in a clinical trial. Samples were collected at Month 6 after remission induction, then every 3 months until Month 18, or at the time of flare. Associations of protein concentrations with concurrent disease activity and with future flare were analyzed using mixed-effects models, Cox proportional hazards models, and conditional logistic regression.

RESULTS

Forty-two patients had flares during the 12-month follow-up period, and 32 remained in remission. Twenty-two patients had severe flares. Six experimental markers (CXCL13, IL-6, IL-8, IL-15, IL-18BP, and matrix metalloproteinase-3 [MMP-3]) and ESR were associated with disease activity using all three methods (P < 0.05, with P < 0.01 in at least one method). A rise in IL-8, IL-15, or IL-18BP was associated temporally with flare. Combining C-reactive protein (CRP), IL-18BP, neutrophil gelatinase-associated lipocalin (NGAL), and sIL-2Rα improved association with active AAV. CXCL13 and MMP-3 were increased during treatment with prednisone, independent of disease activity. Marker concentrations during remission were not predictive of future flare.

CONCLUSION

Serum biomarkers of inflammation and tissue damage and repair have been previously shown to be strongly associated with severe active AAV were less strongly associated with active AAV in a longitudinal study that included mild flares and varying treatment. Markers rising contemporaneously with flare or with an improved association in combination merit further study.

Assessment of the correlation of commonly used laboratory tests with clinical activity, renal involvement and treatment of systemic small-vessel vasculitis with the presence of ANCA antibodies

Background

The aim of the study was to assess the correlation of commonly used laboratory tests with clinical activity, degree of kidney involvement and treatment of systemic small-vessel vasculitis with the presence of ANCA antibodies.

Methods

The study included 28 patients with active AAV (BVAS ≥ 3). The following tests were performed: MPO-ANCA, PR3-ANCA, peripheral blood count, ESR, CRP, procalcitonin, creatinine, GFR, urea, albumin, fibrinogen, d-dimer, components of the C3 and C4 complement systems, urinalysis with sediment evaluation and diurnal proteinuria. The assessments were conducted twice: at study entry (A0) and after 6 months (A6) (BVAS = 0).

Results

At the time of inclusion in the study, the mean creatinine concentration was 3.39 mg/dl (GFR 33.17 ml/min/1.73 m²), after achieving remission in 11 patients (39.3 %) GFR remained below 30 ml/min/1.73 m², 4 patients (14.3 %) continued renal replacement therapy, and 3 patients (10.7 %) with advanced renal failure died. Microscopic hematuria occurred in 80.9 % of the studied population, withdrew in most patients, strongly correlated with renal involvement p < 0.001 and was not related to disease severity p = 0.147. CRP, ESR, fibrinogen, d-dimer, albumin and hemoglobin in the peripheral blood showed a strong correlation with the clinical activity of AAV and well identified severe patients. High procalcitonin concentrations correlated with a severe form of the disease, pulmonary involvement with respiratory failure and alveolar hemorrhage (mean 3.41 ng/ml, median 0.91 ng/ml, SD 7.62, p = 0.000), and were associated with the occurrence of infectious complications and the need to administer antibiotic therapy. ANCA antibodies were useful in the evaluation of patients with AAV, the amount of antibodies did not correlate with the severity of vasculitis (p = 0.685) and the results in many patients did not match the expected assumptions.

Conclusions

CRP, ESR, fibrinogen, d-dimers, albumin and hemoglobin in the peripheral blood correlate well with the activity of vasculitis and identify severe patients. The resolution of microscopic hematuria suggests remission of the disease in the renal area. Procalcitonin may be slightly increased in patients with active AAV without infection, high concentrations are strongly associated with infectious complications. ANCA antibodies should always be interpreted in the context of the observed clinical symptoms.

Occurrence and Antigenic Specificity of Perinuclear Anti-Neutrophil Cytoplasmic Antibodies (P-ANCA) in Systemic Autoimmune Diseases

Perinuclear anti-neutrophilic cytoplasmic antibodies (P-ANCA) recognize heterogeneous antigens, including myeloperoxidase (MPO), lactoferrin, elastase, cathepsin-G and bactericidal/permeability-increasing protein. Although P-ANCA have diagnostic utility in vasculitides, they may also be found in patients with various other systemic autoimmune rheumatic diseases (SARDs). Nevertheless, the clinical significance and the targets recognized by P-ANCA in such patients remain unclear. For this purpose, herein we investigated the occurrence of ANCA-related antigenic specificities in 82 P-ANCA-positive sera by multiplex ELISA, as well as their association with other autoantibodies. The P-ANCA-positive sera corresponded to patients with vasculitides (n = 24), systemic lupus erythematosus (n = 28), antiphospholipid syndrome (n = 5), Sjögren’s syndrome (n = 7), rheumatoid arthritis (n = 3), systemic scleroderma (n = 1), sarcoidosis (n = 1) and Hashimoto′s thyroiditis (n = 13). In most P-ANCA-positive patients studied (51/82, 62.3%), these autoantibodies occurred in high titers (>1:160). The analysis of P-ANCA-positive sera revealed reactivity to MPO in only 50% of patients with vasculitides, whereas it was infrequent in the other disease groups studied. Reactivity to other P-ANCA-related autoantigens was also rarely detected. Our findings support that high P-ANCA titers occur in SARD. The P-ANCA-positive staining pattern is associated with MPO specificity in vasculitides, while in other autoimmune diseases, it mostly involves unknown autoantigens.

Antibody subtypes and titers predict clinical outcomes in ANCA-associated vasculitis

The objective of this study is to evaluate the association between antineutrophil cytoplasmic autoantibody (ANCA) subtype and ANCA titers on clinical outcomes and disease activity among a cohort of patients from Central Appalachia diagnosed with ANCA-associated vasculitis (AAV) over a 3-decade period. This is a retrospective chart review of all patients diagnosed with AAV. ANCA subtypes (myeloperoxidase (MPO) and proteinase 3 (PR3)) and titers at the time of diagnosis and at the time of relapse or last follow-up were evaluated along with patient outcomes. Outcomes of interest included relapse, development of end-stage renal disease (ESRD) and mortality. Sensitivity analysis and multivariable analysis were performed. Of the 202 patients, 111 patients were MPO-ANCA positive and 91 patients were PR3-ANCA positive. Relapse was more frequent among patients with PR3-ANCA compared to MPO-ANCA (35% vs 12%, p < 0.001). In both ANCA subgroups, the strongest predictor of relapse was an increase in titers prior to relapse, HR 8.1 (95% CI 1.6-40), p 0.009. Patients who achieved serological remission had a lower risk of ESRD [sub-HR 0.31 (95% CI 0.11-0.89)] and mortality [HR (95% CI) 0.24 (0.07-0.7)]. PR3-ANCA was associated with higher risk of ESRD [sub-HR 3.1 (95% CI 1.1-8.5)]. There was no difference in mortality between patients with MPO-ANCA and PR3-ANCA. Our study supports the use of both ANCA subtypes and titer levels for predicting clinical outcomes in patients receiving treatment for AAV. Monitoring of ANCA antibody titers may be useful since both serological remission and increase in titers provide prognostic information.

Antimyeloperoxidase and proteinase 3 antibodies for nephritis flare prediction in ANCA-associated-vasculitis

BACKGROUND

The value of myeloperoxidase and proteinase 3 antibodies titers in the assessment of renal disease activity and flare prediction in patients with ANCA-associated-vasculitis (AAV) is not well-known.

METHODS

Retrospective study including 113 AVV patients with a renal biopsy-proven pauci-immune necrotizing glomerulonephritis from seven Spanish hospitals. The main inclusion criteria were assessment of MPO antibodies (MPOab) using multiplex flow immunoassay and PR3 antibodies (PR3ab) measurements using immunoassay chemiluminescence with an identical range of values for all participating centers.

RESULTS

Serum MPOab, 3 ± 1.2 months before relapse, was higher in patients who relapsed (19.2 ± 12.2 vs 3.2 ± 5.1 AI, p < 0.001). The discrimination value of MPOab 3 months before renal relapse had an AUC of 0.82 (95%CI 0.73-0.92; p < 0.001). ΔMPOab (change in antibodies titration 6 months before relapse) was higher in patients who relapsed [8.3 ± 12 vs 0.9 ± 3.1 AI, p = 0.001) (AI; antibody index unit). The discrimination value of ΔMPO had an AUC of 0.76 (95%CI 0.63-0.88; p < 0.001). The positive predictive value of renal relapse in PR3 patients is 100% and the negative predictive value of renal relapse in patients with PR3 positive titers is 57.1%. Serum PR3ab was higher in patients who relapsed 2.8 ± 1.4 months before relapse (58.6 ± 24.6 vs 2.0 ± 0.6 AI, p < 0.001).

CONCLUSIONS

MPO antibody level monitorization using multiplex flow immunoassay and PR3 measurements using immunoassay chemiluminescence are useful and sensitive tools for the prediction of renal relapse in the follow-up of AAV patients with renal disease, and relevant surrogate markers of renal disease activity.

Proposal for a more practical classification of antineutrophil cytoplasmic antibody-associated vasculitis

The nomenclature for antineutrophil cytoplasmic antibody (ANCA)-associated kidney disease has evolved from honorific eponyms to a descriptive-based classification scheme (Chapel Hill Consensus Conference 2012). Microscopic polyangiitis, granulomatosis with polyangiitis and eosinophilic granulomatosis with polyangiitis do not correlate with presentation, response rates and relapse rates as when comparing myeloperoxidase versus leukocyte proteinase 3. Here we discuss the limitations of the currently used classification and propose an alternative, simple classification according to (i) ANCA type and (ii) organ involvement, which provides important clinical information of prognosis and outcomes.

Relapse rate and renal prognosis in ANCA-associated vasculitis according to long-term ANCA patterns

Long-term observation of patients with ANCA-associated vasculitis (AAV) allows the identification of different longitudinal patterns of ANCA levels during follow-up. This study aimed to characterize these patterns and to determine their prognostic significance. All ANCA determinations performed in two university hospitals during a 2-year period were retrospectively reviewed. Patients were included in the analysis if they had high titers of anti-myeloperoxidase (anti-MPO) or anti-proteinase 3 (anti-PR3) antibodies at least once, ≥ 5 serial ANCA determinations and AAV diagnosed by biopsy or American College of Rheumatology (ACR) classification criteria. Patients' time-course ANCA patterns were classified as monophasic, remitting, recurrent or persistent. Associations between ANCA patterns and prognostic variables (relapse rate and renal outcome) were analysed by univariate and multivariate statistics. A total of 99 patients [55 with microscopic polyangiitis (MPA), 36 with granulomatosis with polyangiitis (GPA) and eight with eosinophilic granulomatosis with polyangiitis (EGPA)] were included. Median follow-up was 9 years. Among patients diagnosed with MPA or GPA, recurrent or persistent ANCA patterns were associated with a higher risk of clinical relapse [hazard ratio (HR) = 3·7, 95% confidence interval (CI) = 1·5-9·1 and HR = 2·9, 95% CI = 1·1-8·0, respectively], independently of clinical diagnosis or ANCA specificity. In patients with anti-MPO antibodies, the recurrent ANCA pattern was associated with worsening renal function [odds ratio (OR) = 5·7, 95% CI = 1·2-26·0]. Recurrent or persistent ANCA patterns are associated with a higher risk of clinical relapse. A recurrent ANCA pattern was associated with worsening renal function in anti-MPO-associated vasculitis.

Clinical Utility of Serial Measurements of Antineutrophil Cytoplasmic Antibodies Targeting Proteinase 3 in ANCA-Associated Vasculitis

Background: The utility of ANCA testing as an indicator of disease activity in ANCA-associated vasculitis (AAV) remains controversial. This study aimed to determine the association of ANCA testing by various methods and subsequent remission and examine the utility of a widely used automated addressable laser-bead immunoassay (ALBIA) to predict disease relapses.

Methods: Data from the Rituximab vs. Cyclophosphamide for ANCA-Associated Vasculitis (RAVE) trial were used. ANCA testing was performed by direct ELISA, capture ELISA, and ALBIA. Cox proportional hazards regression models were used to evaluate the association of PR3-ANCA level and subsequent remission or relapse. The ALBIA results are routinely reported as >8 when the value is high. For this study, samples were further titrated. A decrease and increase in PR3-ANCA were defined as a halving or doubling in value, respectively.

Results: A decrease in ANCA by ALBIA at 2 months was associated with shorter time to sustained remission (HR 4.52, p = 0.035). A decrease in ANCA by direct ELISA at 4 months was associated with decreased time to sustained remission (HR 1.77, p = 0.050). There were no other associations between ANCA decreases or negativity and time to remission. An increase in PR3-ANCA by ALBIA was found in 78 of 93 subjects (84%). Eleven (14%) had a PR3-ANCA value which required titration for detection of an increase. An increase of ANCA by ALBIA was associated with severe relapse across various subgroups.

Conclusions: A decrease in ANCA by ALBIA at 2 months and by direct ELISA at 4 months may be predictive of subsequent remission. These results should be confirmed in a separate cohort with similarly protocolized sample and clinical data collection. A routinely used automated ALBIA for PR3-ANCA measurement is comparable to direct ELISA in predicting relapse in PR3-AAV. Without titration, 14% of the increases detected by ALBIA would have been missed. Titration is recommended when this assay is used for disease monitoring. The association of an increase in PR3-ANCA with the risk of subsequent relapse remains complex and is affected by disease phenotype and remission induction agent.

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.

Microscopic polyangiitis: an incidental finding in a patient with stroke

Microscopic polyangiitis (MPA) is a primary systemic vasculitis characterized by inflammation of small-sized vessels associated with the presence of anti-neutrophilic cytoplasmic antibodies. We report a case of a 39-year-old female diagnosed with microscopic polyangiitis as an incidental finding who presented with signs and symptoms of a stroke at a young age. Usually, it presents with fever, malaise, skin rash, weight loss, mononeuritis multiplex, and arthralgia/myalgia. Very rarely, it can involve meninges to cause meningeal vasculitis which can present as a febrile seizure. The most frequent neurological manifestation is peripheral neuropathy. Cerebral infarction or hemorrhage as an isolated finding is very rarely observed in the patient with MPA as was seen in our patient.

Factors Determining the Clinical Utility of Serial Measurements of Antineutrophil Cytoplasmic Antibodies Targeting Proteinase 3

OBJECTIVE

Relapse following remission is common in antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV), particularly with ANCAs directed at proteinase 3 (PR3). This study was undertaken to evaluate the association of an increase in PR3-ANCA level with subsequent relapse.

METHODS

Data from the Rituximab versus Cyclophosphamide for ANCA-Associated Vasculitis (RAVE) trial were used. Starting from the time of achieving complete remission, serial measurements by direct and capture enzyme-linked immunosorbent assays (ELISAs) were analyzed in 93 patients with PR3-ANCA, using Cox proportional hazards regression.

RESULTS

An increase in PR3-ANCA level was identified in 58 of 93 subjects (62.4%) by direct ELISA and in 59 of 93 (63.4%) by capture ELISA. Relapses occurred in 55 of 93 subjects (59.1%), with 25 and 21 occurring within 1 year after an increase by direct ELISA and capture ELISA, respectively. An increase by direct ELISA was associated with subsequent severe relapses (hazard ratio [HR] 4.57; P < 0.001), particularly in patients presenting with renal involvement (HR 7.94; P < 0.001) and alveolar hemorrhage (HR 24.19; P < 0.001). Both assays identified increased risk for severe relapse in the rituximab group (HR 5.80; P = 0.002 for direct ELISA and HR 4.54; P = 0.007 for capture ELISA) but not the cyclophosphamide/azathioprine group (P = 0.103 and P = 0.197, respectively).

CONCLUSION

The association of an increase in PR3-ANCA level with the risk of subsequent relapse is partially affected by the PR3-ANCA detection methodology, disease phenotype, and remission induction treatment. An increase in PR3-ANCA level during complete remission conveys an increased risk of relapse, particularly severe relapse, among patients with renal involvement or alveolar hemorrhage and those treated with rituximab. Serial measurements of PR3-ANCA may be informative in this subset of patients, but the risk of relapse must be weighed carefully against the risks associated with therapy.

Negative anti-neutrophil cytoplasm antibody at switch to maintenance therapy is associated with a reduced risk of relapse

BACKGROUND

Relapse of disease is frequent in anti-neutrophil cytoplasm antibody (ANCA)-associated vasculitis (AAV). It is unclear whether persistent ANCA when starting maintenance therapy increases the risk of relapse. We examined the association between ANCA status and relapse in two randomised controlled trials.

METHODS

ANCA-positive patients in two trials, CYCLOPS and IMPROVE, were switched from cyclophosphamide to maintenance therapy after achieving clinical remission. We classified patients as being either ANCA-positive or ANCA-negative at the time they started maintenance therapy. We compared the risk of relapse in ANCA-positive and ANCA-negative patients.

RESULTS

Of 252 patients included, 102 (40%) experienced at least one relapse during the follow-up period. At the time of the switch from induction to maintenance therapy, 111 were ANCA-positive, of whom 55 (50%) relapsed, compared to 141 patients who were ANCA-negative, of whom 47 (33%) relapsed. In multivariable time-to-event analysis, a reduced risk of relapse was associated with having become ANCA-negative at the time of switching to maintenance therapy (hazard ratio 0.63, 95% confidence interval 0.42-0.95; p = 0.026). In addition, initial proteinase 3 (PR3)-ANCA, younger age, lower serum creatinine, pulsed cyclophosphamide for remission induction, and mycophenolate mofetil for remission maintenance were all associated with an increased risk of relapse.

CONCLUSIONS

Becoming ANCA-negative before the switch to maintenance is associated with a reduced risk of relapse.

TRIAL REGISTRATION

CYCLOPS: ClinicalTrials.gov, NCT00430105 . Registered retrospectively on 31 January 2007.

IMPROVE

ClinicalTrials.gov, NCT00307645 . Registered retrospectively on 27 March 2006.

ANCA-associated vasculitis - clinical utility of using ANCA specificity to classify patients

The anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitides (AAV) are a heterogeneous group of rare syndromes characterized by necrotizing inflammation of small and medium-sized blood vessels and the presence of ANCAs. Several clinicopathological classification systems exist that aim to define homogeneous groups among patients with AAV, the main syndromes being microscopic polyangiitis (MPA), granulomatosis with polyangiitis (GPA) and eosinophilic GPA (EGPA). Two main types of ANCA can be detected in patients with AAV. These ANCAs are defined according to their autoantigen target, namely leukocyte proteinase 3 (PR3) and myeloperoxidase (MPO). Patients with GPA are predominantly PR3-ANCA-positive, whereas those with MPA are predominantly MPO-ANCA-positive, although ANCA specificity overlaps only partially with these clinical syndromes. Accumulating evidence suggests that ANCA specificity could be better than clinical diagnosis for defining homogeneous groups of patients, as PR3-ANCA and MPO-ANCA are associated with different genetic backgrounds and epidemiology. ANCA specificity affects the phenotype of clinical disease, as well as the patient's initial response to remission-inducing therapy, relapse risk and long-term prognosis. Thus, the classification of AAV by ANCA specificity rather than by clinical diagnosis could convey clinically useful information at the time of diagnosis.

Diagnostic value of antineutrophil cytoplasmic antibodies in children with bronchiolitis obliterans

BACKGROUND

Diagnosis of childhood bronchiolitis obliterans (BO) is difficult owing to non-specific clinical presentations and limited investigational options. There is a lack in established serum biomarkers for BO. While the diagnostic value of antineutrophil cytoplasmic antibodies (ANCAs) has been discussed, little is known about this in BO. We aimed to investigate the serological profiles of ANCAs against myeloperoxidase (MPO-ANCA) and proteinase-3 (PR3-ANCA) in BO and acute pneumonia.

METHODS

In this study, 42 BO children (BO group) and 43 with mild acute pneumonia (pneumonia group) were included, based on rigorous diagnostic criteria and additional constraints for minimizing selection bias. Serum MPO-ANCA and PR3-ANCA levels were measured on the first (baseline) and the last day of hospitalization (on discharge) by enzyme linked immunosorbent assay.

RESULTS

Although the BO children had a longer hospital stay, the overall rate of positivity (≥180 AAU/mL) and median serum level of MPO-ANCA were higher in the BO group compared with the pneumonia group, either at baseline (69.1% vs. 9.3%, 292.00 vs. 104.75 AAU/mL, both P<0.001) or on discharge (61.9% vs. 9.3%, 310.50 vs. 95.42 AAU/mL). Similar was found for PR3-ANCA (38.1% vs. 4.7%, 106.66 vs. 54.56 AAU/mL at baseline; 35.7% vs. 2.3%, 97.98 vs. 57.23 AAU/mL on discharge, both P<0.001). There were a higher rate of dual-positivity and a lower rate of dual-negativity to both ANCAs in the BO group than those in the pneumonia group (all P<0.001).

CONCLUSIONS

Detection of MPO- and PR3-ANCA can help diagnosis of childhood BO.

Can antineutrophil cytoplasmic antibody levels be used to inform treatment of pauci-immune vasculitis?

PURPOSE OF REVIEW

The role of serial antineutrophil cytoplasmic antibody (ANCA) measurements to guide immunosuppressive therapy in pauci-immune vasculitis is an area of ongoing controversy. Evidence elucidating the relationship between ANCA levels and disease activity continues to grow.

RECENT FINDINGS

The finding that proteinase 3-ANCA and myeloperoxidase-ANCA-associated diseases differ genetically has challenged the traditional classification and study of pauci-immune vasculitis. Multiple studies have also found that the clinical features and course of disease differ by ANCA antigen specificity more than clinical diagnosis. Advances in diagnostic assays and new techniques for the evaluation of ANCA levels over time have yielded improved assay performance in specific subsets of patients. In addition, increasing use of rituximab has added to our understanding of the relationship of ANCA levels to B-cell counts and disease relapse, which may differ by treatment regimen.

SUMMARY

The relationship between ANCA levels and disease activity is impacted by multiple factors, including antigen specificity, disease manifestations, clinical assay, and therapeutic regimen. Each of these must be taken into account when determining the significance of ANCA levels during long-term follow-up of pauci-immune vasculitis.

Rapidly progressive IgA nephropathy: a form of vasculitis or a complement-mediated disease?

A rapidly progressive and crescentic IgA nephropathy (IgAN) is uncommon, but it has a high risk of progression to end-stage renal disease and variable response to immunosuppression. The importance of a positive anti-neutrophil cytoplasmic antibody (ANCA) serology in this group of patients is not fully understood but may have prognostic significance. On the other hand, there is growing evidence of the role of complement in the pathogenesis of IgAN, especially in cases of crescentic IgAN. Therapies directed against the complement system are a potential and rational therapeutic approach. In this issue, two clinical studies of crescentic IgAN are presented. The first work, is a retrospective case-control study describing clinical presentation, histological findings and response to treatment of crescentic IgAN/positive ANCA patients, comparing them with IgAN/negative ANCA patients and ANCA vasculitis patients. The second is a case report showing the effect of eculizumab, a humanized monoclonal antibody that is a terminal cascade complement inhibitor, as salvage therapy for crescentic IgAN resistant to conventional immunosuppression. Both studies broaden our approach to patients with aggressive forms of IgAN.

Evaluation and validation of biomarkers in granulomatosis with polyangiitis and microscopic polyangiitis

BACKGROUND

Studies in anti-neutrophil cytoplasm antibody (ANCA)-associated vasculitis (AAV) have revealed promising biomarkers. The aim of our study was to validate the most encouraging markers of granulomatosis with polyangiitis and microscopic polyangiitis identified by literature search and to create biomarker panels.

METHODS

A systematic literature review was performed and we identified 161 marker molecules that were ranked by their quantitative differential expression between active and inactive disease. Enzyme-linked immunosorbent assays were used to validate the results in a cross-sectional cohort of patients with renal involvement. Active vasculitis as assessed by the Birmingham Vasculitis Score version 3 (BVAS v3) was defined as BVAS v3 ≥1 and inactive disease as BVAS v3 = 0. Statistical analysis was performed with SPSS version 21 and the Salford Predictive Modeler 7.0 was used to generate a predictive biomarker panel.

RESULTS

The review indicated abundant expression of sC5bC9, C3a, C5a and monocyte chemotactic protein (MCP)-1 in urine, whereas granulocyte macrophage colony-stimulating factor, C-reactive protein (CRP), soluble fms-like tyrosine kinase-1, interleukin-17A (IL-17A), C5a, hyaluronan, C3a and interleukin-18 binding protein (IL-18BP) were identified to be highly diverse in active and inactive disease in blood samples. Our cross-sectional analysis revealed significant up-regulation of CRP, C5a, C3a, IL-18BP in blood and C5a and MCP-1 in urine samples during active AAV (all P < 0.05). Creation of a biomarker panel comprising CRP and urinary MCP-1 yielded a sensitivity and specificity of 76% (area under the curve 0.89).

CONCLUSIONS

We identified promising biomarkers in a literature-based review that were in part corroborated as has been shown for CRP, C3a, C5a, IL-18BP in blood and MCP-1 and C5a in urine samples. Moreover, we propose a biomarker panel comprising CRP and urinary MCP-1 in patients with AAV and renal involvement. Further investigations to confirm our preliminary results are clearly warranted, including the reliability to predict disease relapses.

Linking classification and therapeutic management of vasculitides

Vasculitides are classified by the size, type and location of the predominantly involved vessels and by their primary or secondary nature. Their treatment depends on the type of vasculitis, its etiology (when known), and its severity and must be further adjusted by the individual characteristics and comorbidities of patients. In this paper, we review how the classification and definition of vasculitides have evolved over the past years and how it has affected therapeutic changes. As new genetic markers are being discovered and the pathogenesis of vasculitides continues to be elucidated, further modifications in classification and treatment can be expected.

Microscopic polyangiitis: Advances in diagnostic and therapeutic approaches

Microscopic polyangiitis (MPA) is an idiopathic autoimmune disease characterized by systemic vasculitis. The disease predominantly affects small-calibre blood vessels and is associated with the presence of antineutrophil cytoplasmic autoantibodies (ANCA). Microscopic polyangiitis was considered to be a disease entity by Savage et al. in 1985. Microscopic polyangiitis has a reported low incidence and a slight male predominance. The aetiology of MPA remains unknown. There is, however, increased evidence that MPA is an autoimmune disease in which ANCAs, particularly those reacting with MPO, are pathogenic. MPA belongs to the systemic vasculitides, indicating that multiple organs can be affected. The major organs involved in MPA are the kidneys and the lungs. As expected for an illness that affects multiple organ systems, patients with MPA can present with a myriad of different symptoms. Ear, nose and throat (ENT) manifestations are not considered to be clinical symptoms of MPA, but in the majority of populations described, ENT involvement was found in surprisingly high percentages. MPA is part of the ANCA-associated vasculitides, which are characterized by necrotizing vasculitis of small vessels. Diagnosis is mainly established by clinical manifestations, computed tomography (TC), ANCA antibody detection and renal and pulmonary biopsy. The introduction of aggressive immunosuppressive treatment has substantially improved the prognosis. The standardized therapeutic regimen is based on cyclophosphamide and corticosteroids. Using this regimen, remission can be achieved in most of the patients. Rituximab may represent an important alternative to cyclophosphamide for patients who may not respond adequately to antimetabolite therapies.

ANCA as a predictor of relapse: useful in patients with renal involvement but not in patients with nonrenal disease

The value of measuring ANCA during follow-up to predict a relapse is controversial. On the basis of recently obtained pathophysiologic insights, we postulated that measuring ANCA is useful in patients with renal involvement but is less valuable in patients with nonrenal disease. One hundred sixty-six consecutive patients with ANCA-associated vasculitis, positive for either proteinase 3 (PR3)-ANCA or myeloperoxidase (MPO)-ANCA, were included in our study, followed at regular intervals, and tested for PR3-ANCA and MPO-ANCA. In this cohort, 104 patients had renal involvement (72 with PR3-ANCA, 32 with MPO-ANCA) and 62 patients had nonrenal disease (36 with PR3-ANCA, 26 with MPO-ANCA). During an average (±SD) follow-up of 49±33 months and 18±14 ANCA measurements, 89 ANCA rises and 74 relapses were recorded. ANCA rises correlated with relapses in patients who presented with renal involvement (hazard ratio [HR], 11.09; 95% confidence interval [95% CI], 5.01 to 24.55), but in comparison, associated only weakly with relapses in patients who presented with nonrenal disease (HR, 2.79; 95% CI, 1.30 to 5.98). In conclusion, longitudinal ANCA measurements may be useful in patients with renal involvement but is less valuable in patients with nonrenal disease.

Novel clinical and diagnostic aspects of antineutrophil cytoplasmic antibodies

Antineutrophil cytoplasmic antibodies (ANCA) are the serological hallmark of some idiopathic systemic vasculitides. Besides the investigation of ANCA-associated vasculitis (AAV) and constant effort for a standardized nomenclature and classification of the AAV, a main focus of research during the last few years has been to constantly improve the performance of enzyme immunoassays. With the latest so called third generation ELISA, this goal seemed to be fulfilled. The International Consensus Statement on Testing and Reporting of ANCA gave recommendations for standardized strategies for the serological diagnosis of ANCA. New developments now target the system immanent drawbacks of the respective diagnostic methods, be it the need for batching and the long time to result for ELISA, or the high likelihood of error and subjectivity of indirect immunofluorescence (IIF). Random access technology and multiplexing for solid phase assays as well as digital imaging for IIF are tools which may help to expedite and simplify routine diagnostics in the lab and in emergency settings. Recent findings indicate that PR3-ANCA have clinical utility beyond the diagnosis of AAV. PR3-ANCA can also serve as an aid for the differentiation between ulcerative colitis (UC) and Crohn's disease (CrD) and the stratification of UC patients. This review provides a detailed review of what is known about ANCA and highlights the latest research and state-of-the-art developments in this area.

The diagnosis and classification of microscopic polyangiitis

Microscopic Polyangiitis (MPA) is a small vessel vasculitis. The disease is defined by the 2012 revised Chapel Hill Consensus Conference Nomenclature of Vasculitides [1] as necrotizing vasculitis, with few or no immune deposits, predominantly affecting small vessels (i.e. capillaries, venules, or arterioles). Necrotizing arteritis involving small and medium arteries may be present. Necrotizing glomerulonephritis is very common. Pulmonary capillaritis often occurs. Granulomatous inflammation is absent. MPA belongs to the ANCA-associated vasculitides (AAV). ANCA in MPA are predominantly directed against myeloperoxidase (MPO-ANCA) but may, in a minority of patients, be directed against proteinase 3 (PR3-ANCA). Not all patients, however, have ANCA. Microscopic polyangiitis (MPA) belongs to the anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitides. MPA is clinically characterized by small-vessel vasculitis primarily affecting the kidneys and the lungs but other organs may be involved as well. Renal involvement, which can be the only manifestation, is clinically apparent as rapidly progressive glomerulonephritis and histopathologically as pauci-immune necrotizing and crescentic glomerulonephritis. ANCA in MPA are mainly directed to myeloperoxidase (MPO-ANCA). Besides their diagnostic significance, MPO-ANCA appear pathogenic in MPA. Rituximab with steroids is at least as effective as cyclophosphamide with steroids for induction of remission.

Aortic stenosis concomitant with microscopic polyangiitis: a challenge in medical reasoning and thinking

Microscopic polyangiitis (MPA) is part of the anti-neutrophil cytoplasmic antibodies (ANCA)-related vasculitis, which usually presents as renal pulmonary syndrome. It is defined as a pauci-immune necrotizing small vessel vasculitis, which usually affects the kidneys, followed by the lungs. It also presents systemic symptoms. The etiology of MPA is still unclear, but evidence reinforces the autoimmune mechanisms as the main etiopathogenic factor. Aortic valve stenosis (AS) is not an uncommon disease whose etiology varies according to geographical differences and the patient's age. The natural history of AS begins with a prolonged asymptomatic period, but when symptomatic, respiratory failure is one of its main clinical presentations. The authors present the case of a 55-year-old woman who was admitted with the diagnosis of renal failure, anemia, and a cardiac murmur. The patient had been recently diagnosed with pneumonia. During hospitalization, diagnostic workup disclosed a normal kidney size as well as parenchymal thickness. A renal biopsy was undertaken but the specimen was exiguous, showing 4 sclerotic glomeruli and 1 glomerulus with crescentic glomerulonephritis. The search for ANCA was positive. The investigation of the cardiac murmur disclosed AS. The patient, on hemodialysis, presented episodes of respiratory failure, which was interpreted as acute pulmonary edema, but a suspicion of ANCA-related pulmonary renal syndrome was raised. However, the aortic valve replacement was prioritized. While awaiting cardiac surgery, the patient died because of respiratory insufficiency. Autopsy findings concluded that MPA with pulmonary hemorrhage due to vasculitis was the immediate cause of death. Although AS was present at autopsy and classified as moderate/severe, this lesion was a bystander in the process of this patient's end of life, demonstrating the value of autopsy for medical learning and reasoning purposes.

AP-VAS 2012 case report: MPO-ANCA-negative relapse of MPO-ANCA-associated vasculitis

A 79-year-old female was admitted to our hospital with fever, proteinuria, hematuria, high levels of C-reactive protein (CRP), and high titer of myeloperoxidase antineutrophil cytoplasmic antibody (MPO-ANCA). Our diagnosis was microscopic polyangiitis (MPA) and she was treated with steroid pulse therapy. Clinical remission was induced; however, the disease relapsed with saddle nose and necrotizing vasculitis of the nasal cavity mucosa 1 year later. Although there was no elevation of the MPO-ANCA titer, we diagnosed the patient with relapse of MPO-ANCA-positive granulomatosis with polyangiitis (GPA). Remission was induced again with steroids and azathioprine. It has been reported that the number of MPO-ANCA-positive patients in Asian countries is relatively higher than in Western countries. We checked 29 GPA patients in our hospital and 9 patients (31.0 %) were MPO-ANCA-positive. In addition, it is not rare that an ANCA-associated vasculitis (AAV) patient who has been in remission with negative ANCA relapses without any elevation of ANCA titer. We checked the transition of ANCA titer of 24 AAV patients in our hospital who relapsed and 6 patients (25 %) relapsed without any elevation of ANCA titer. We should be careful for a relapse, even if the ANCA titer remains negative. It is also possible that ANCA had been changed so as not to be detected by the same enzyme-linked immunosorbent assay (ELISA) kit. Thus, it is also important to change the detection system if clinical symptoms are worsened while ANCA is still negative.

[The pulmonary-renal syndrome: a diagnostic and therapeutic emergency for the internist and the intensivist]

The pulmonary-renal syndrome is a rare and life-threatening condition. It is defined as the association of a diffuse alveolar hemorrhage and a rapidly progressive glomerulonephritis. The characteristic histological lesion common to all underlying diseases is a necrotizing and crescentic glomerulonephritis. The pulmonary-renal syndrome is a diagnostic and therapeutic emergency: any delay in its management will lead to death or serious functional damage as pulmonary and renal impairment. ANCA-associated vasculitis and Goodpasture's disease are the main disorders associated to pulmonary-renal syndrome. More rarely systemic lupus, cryoglobulinaemia, Henoch-Schonlein purpura or subacute endocarditis may induce a pulmonary-renal syndrome. Differential diagnosis can sometimes be difficult, highlighting some ambiguity in the definition of the syndrome. Initial treatment usually associates systemic corticosteroid, cyclophosphamide and plasma exchange. The role of biotherapy as first line therapy remains to be determined.

Detection of autoantibodies in a point-of-care rheumatology setting

Autoimmune rheumatic diseases are common and confront society with serious medical, social, and financial burdens imposed by their debilitating nature. Many autoimmune diseases are associated with a particular set of autoantibodies, which have emerged as highly useful to define and classify disease, predict flares, or monitor efficacy of therapy. However, current practice for monitoring autoantibodies is protracted, labor-intensive, and expensive. This review provides an overview on the value of point-of-care (POC) biosensor technology in the diagnosis and management of patients with autoimmune rheumatic diseases. Real-time measurement of autoantibodies will clearly benefit the rheumatology practice in emergency and urgent care settings, where definitive diagnosis is essential for initiation of correct critical care therapy. Immediate serological information in clinic will provide considerable value for long-term patient care and an opportunity for an instant, result-deduced therapeutic action, avoiding delays and improving compliance, especially in field-based and remote areas. We describe the particular autoantibodies that are useful disease and activity markers and would, therefore, be attractive to POC applications. Already existing biosensors and platforms that show promise for autoantibody testing are summarized and comparatively evaluated. As POC assessment is gaining momentum in several areas of patient care, we propose that rheumatology is poised to benefit from this innovative and affordable technology.

Antineutrophil cytoplasmic antibody-associated vasculitides: is it time to split up the group?

Antineutrophil cytoplasmic antibody (ANCA)-associated vasculitides are a heterogeneous group of diseases corresponding to necrotising inflammation of small vessels with a wide range of clinical presentations. At least two of the diseases are believed to exhibit a common ground of pathophysiological mechanisms. These are granulomatosis with polyangiitis (GPA, formerly known as Wegener's granulomatosis) and microscopic polyangiitis (MPA). ANCA directed against proteinase 3 (PR3) are preferentially associated with GPA, and anti-myeloperoxidase (MPO) ANCA are associated mainly with MPA and eosinophilic GPA (formerly known as Churg-Strauss syndrome). Anti-MPO and anti-PR3 antibodies can activate neutrophils in vitro. In vivo data are available for humans and mice on the pathogenicity of anti-MPO but it is more controversial for PR3-ANCA. A recent genome-wide association study of patients with ANCA-associated vasculitides confirmed the genetic contribution to the pathogenesis of these conditions, with significant association of PR3-ANCA and human leukocyte antigen-DP and the genes encoding α1-antitrypsin and PR3. MPO-ANCA were significantly associated with human leukocyte antigen-DQ. Thus, recent results from epidemiological studies, genome-wide association study and therapeutic trials have suggested that these entities are, in fact, distinct. We have summarised these results and discuss the idea that these two entities should be studied separately as the nature of the two auto-antigens suggests at a molecular level despite shared ANCA involvement.

Antineutrophil cytoplasmic autoantibodies: how are they detected and what is their use for diagnosis, classification and follow-up?

Antineutrophil cytoplasmic antibodies (ANCA) are traditionally detected by an indirect immunofluorescence technique. According to the international consensus on ANCA testing, ANCA should also be tested by antigen-specific tests for myeloperoxidase-ANCA and proteinase 3-ANCA. The direct noncompetitive enzyme-linked immunosorbent assay (ELISA) used to be the method of choice. Nowadays, these assays are called "first-generation" assays. Second-generation tests (capture ELISA) or third-generation tests (anchor ELISA) are more sensitive and specific for ANCA testing. We postulate that ANCA as detected by these newer ANCA tests may replace the need to perform indirect immunofluorescence-based assays. For classification of patients, ANCA serotype seems more important than classifying patients according to their clinical subtype, since genetics, clinical manifestations and response to therapy are more related to ANCA serotype than to clinical subtype. Detection of ANCA to monitor disease activity is still a controversial issue. Treatment based on ANCA levels is at present only experimentally performed in those patients who are treated with B-cell depletion therapy with rituximab. Future studies are needed to establish whether this way of monitoring patients is warranted.

Long-term outcomes of 118 patients with eosinophilic granulomatosis with polyangiitis (Churg-Strauss syndrome) enrolled in two prospective trials

The purpose of this study was to assess the outcomes of 118 patients with eosinophilic granulomatosis with polyangiitis (EGPA) enrolled in 2 prospective, randomized, open-label clinical trials (1994-2005), with or without Five-Factor Score (FFS)-defined poor-prognosis factors, focusing on survival, disease-free survival, relapses, clinical and laboratory findings, therapeutic responses, and factors predictive of relapse. Forty-four patients with FFS ≥ 1 were assigned to receive 6 or 12 cyclophosphamide pulses plus corticosteroids and the seventy-four with FFS = 0 received corticosteroids alone, with immunosuppressant adjunction when corticosteroids failed. Patients were followed (2005-2011) under routine clinical care in an extended study and data were recorded prospectively. Mean ± SD follow-up was 81.3 ± 39.6 months. Among the 118 patients studied, 29% achieved long-term remission and 10% died. Among the 115 patients achieving a first remission, 41% experienced ≥1 relapses, 26.1 ± 26.8 months after treatment onset, with 57% of relapses occurring when corticosteroid-tapering reached <10 mg/day. Treatment achieved new remissions in >90%, but relapses recurred in 38%. Overall survival was good, reaching 90% at 7 years, regardless of baseline severity. Age ≥65 years was the only factor associated with a higher risk of death during follow-up. The risk of relapse was higher for patients with anti-myeloperoxidase antibodies and lower for those with >3000 eosinophils/mm(3). Sequelae remained frequent, usually chronic asthma and peripheral neuropathy. In conclusion, EGPA patients' survival rate is very good when treatment is stratified according to the baseline FFS. Relapses are frequent, especially in patients with anti-myeloperoxidase antibodies and baseline eosinophilia <3000/mm(3).

Susac syndrome: an organ-specific autoimmune endotheliopathy syndrome associated with anti-endothelial cell antibodies

Susac syndrome (SS) is the triad of encephalopathy, branch retinal artery occlusions (BRAOs), and hearing loss. Migraines may herald and accompany encephalopathy. Little is known about pathogenesis. Based on light microscopic findings in brain biopsy material analogous to anti-endothelial cell antibody (AECA)-mediated microvascular injury, we postulated that SS microangiopathy was attributable to AECAs. We examined serum samples from 11 patients with SS for AECAs; 9 were positive by indirect immunofluorescence and Western blot studies. A highly distinctive band on Western blots corresponding to a 50-kDa protein was observed in 8 positive SS samples; the other positive case exhibited specific reactivity with a protein band at 40 kDa. Of the 2 negative cases, 1 had been inactive since 1988; the other was an abortive variant characterized solely by BRAOs. There was enhanced surface binding of SS serum using live endothelial cell substrates compared with samples from healthy subjects. Additional serum samples from apparently healthy patients, 2 with atypical migraines, and patients with other forms of autoinflammatory disease did not show the distinctive band of immunoreactivity. SS is a distinct autoimmune endotheliopathy syndrome associated with AECAs; the antibody target seems specific in many cases and may be a disease biomarker. The exact role of AECAs in disease propagation remains unanswered.

Value of ANCA measurements during remission to predict a relapse of ANCA-associated vasculitis--a meta-analysis

OBJECTIVE

The value of repeated ANCA measurements among patients with an established diagnosis of ANCA-associated vasculitis (AAV) remains controversial. The aim of this study was to explore whether either of the two distinct patterns of ANCA values during remission, a rise in ANCA or persistently positive ANCA, predicted future relapse.

METHODS

MEDLINE and EMBASE searches were performed. Studies with at least 10 subjects with AAV from which both sensitivity and specificity of a rise in ANCA and/or persistent ANCA for future disease relapse could be calculated were included. Likelihood ratios were calculated for each study and pooled to arrive at summary estimates. I(2)-values were calculated as a measure of heterogeneity and meta-regression was used to explore sources of heterogeneity.

RESULTS

Nine articles on a rise in ANCA and nine articles on persistent ANCA were included. The summary estimates for positive likelihood ratio (LR(+)) and negative likelihood ratio (LR(-)) of a rise in ANCA during remission on subsequent relapse of disease were 2.84 (95% CI 1.65, 4.90) and 0.49 (95% CI 0.27, 0.87), respectively. The summary estimates for LR(+) and LR(-) of persistent ANCA during remission for subsequent disease relapse were 1.97 (95% CI 1.43, 2.70) and 0.73 (95% CI 0.50, 1.06), respectively. There was substantial between-study heterogeneity, which was partially explained by the frequency of ANCA measurements.

CONCLUSION

Among patients with AAV, a rise in or persistence of ANCA during remission is only modestly predictive of future disease relapse. There is limited use to serial ANCA measurements during disease remission to guide treatment decisions for individual patients with AAV.

Epitope specificity of myeloperoxidase antibodies: identification of candidate human immunodominant epitopes

Anti-neutrophil cytoplasmic autoantibodies (ANCA) are a common feature of systemic vasculitides and have been classified as autoimmune conditions based, in part, on these autoantibodies. ANCA are subdivided further based on their primary target: cytoplasm (c-ANCA) or perinuclear region (p-ANCA). p-ANCAs commonly target myeloperoxidase (MPO), an enzyme with microbicidal and degradative activity. MPO antibodies are non-specific for any single disease and found in a variety of vasculitides, most commonly microscopic polyangiitis. Despite their prevalence, their role in human disease pathogenesis remains undefined. We sought to characterize the sequential antigenic determinants of MPO in vasculitis patients with p-ANCA. Of 68 patients with significant levels of p-ANCA, 12 have significant levels of MPO antibodies and were selected for fine specificity epitope mapping. Sequential antigenic targets, including those containing amino acids (aa) 213-222 (WTPGVKRNGF) and aa 511-522 (RLDNRYQPMEPN), were commonly targeted with a prevalence ranging from 33% to 58%. Subsequent analysis of autoantibody binding to the RLDNRYQPMEPN peptide was assessed using a confirmatory enzyme-linked immunosorbent assay format, with six patients displaying significant binding using this method. Antibodies against this epitope, along with four others (aa 393-402, aa 437-446, aa 479-488 and aa 717-726), were reactive to the heavy chain structure of the MPO protein. One epitope, GSASPMELLS (aa 91-100), was within the pro-peptide structure of MPO. B cell epitope prediction algorithms identified all or part of the seven epitopes defined. These results provide major common human anti-MPO immunodominant antigenic targets which can be used to examine further the potential pathogenic mechanisms for these autoantibodies.

Pulmonary vasculitis: clinical presentation, differential diagnosis, and management

This review focuses on vasculitides with prominent pulmonary manifestations and discusses key contributions from the recent literature. Pulmonary vasculitis should be considered when clinical findings include alveolar hemorrhage, nodular and cavitary lung disease, airway stenosis, pulmonary artery aneurysms, or pulmonary artery stenosis. The differential diagnostic considerations for common clinical presentations of vasculitis in the lung are important, and several recent additions are discussed. Treatment for established pulmonary vasculitis is effective and has decreased the morbidity and mortality associated with these diseases while introducing an increased risk of infectious complications. Advances in immunosuppressive therapy have improved treatment of refractory disease and are likely to change initial treatment strategies in the future.