Current and emerging techniques for ANCA detection in vasculitis

An update on risk factors for relapse in antineutrophil cytoplasmic antibody-associated vasculitis

Ongoing therapeutic advances in antineutrophil cytoplasmic antibody-associated vasculitis (AAV) have significantly reduced the risk of death in AAV, but 30%-50% of patients still relapse. Relapse is a major problem in these diseases, leading to increased morbidity and mortality. It is, therefore, necessary to find predictors of relapse at the end of the remission induction and maintenance phases in order to personalize treatment.

Effect of antinuclear antibody positivity on antineutrophil cytoplasmic antibody results by indirect immunofluorescence assay

BACKGROUND

The indirect immunofluorescence assay (IIFA) utilizing antineutrophil cytoplasmic antibodies (ANCA) is widely used as a diagnostic test for autoimmune vasculitis. The presence of antinuclear antibodies (ANA) might lead to a misleading interpretation of ANCA. This study aims to explore the impact of the presence of ANA on the interpretation of ANCA.

METHODS

This retrospective research examined samples negative for antiMPO and antiPR3 ANCA by IIFA and explored correlations between the ANA-IIFA results and the ANCA interpretation frequencies. Our analysis involved the use of suitable statistical methods, including Chi-square and kappa statistics.

RESULTS

Up to 75.2% of the ANCA-IIFA-positive samples exhibited a positive p-ANCA pattern when using the ethanol-fixed substrate, with c-ANCA positivity at 24.8%. In the ANA-IIFA-positive samples, ~77.3% displayed p-ANCA patterns on ethanol-fixed substrates. A comparison between the ANA-IIFA titers and the p-ANCA results revealed that p-ANCA positivity was notably more common in samples with higher titers, and this correlation was found to be statistically significant.

CONCLUSION

Positive ANA results by IIFA tests are linked to a higher incidence of p-ANCA interpretation, particularly in cases with higher titer patterns. This insight aids laboratories in establishing effective workflows to investigate potential p-ANCA interference.

Measurement of Neutrophil Extracellular Traps as a Biomarker for the Differential Diagnosis Between Antineutrophil Cytoplasmic Antibody-Positive Individuals With Antineutrophil Cytoplasmic Antibody-Associated Vasculitis and Nonautoimmune Diseases

BACKGROUND/OBJECTIVE

Neutrophil extracellular traps (NETs) have a correlation with disease activity in antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV). However, it is not known whether there is an association between NETs and the presence of ANCA in other diseases. This study aimed to assess the occurrence of NETs in individuals with ANCA and whether serum NET quantitation is capable of distinguishing them with regard to the diagnosis.

METHODS

This was a cross-sectional, observational study. From the positive ANCA by indirect immunofluorescence, 94 individuals were divided into groups: AAV, infectious diseases, and neoplastic diseases. Healthy controls served for comparisons. Neutrophil extracellular traps were evaluated through the investigation of NET remnants, by detecting cell-free DNA bound to proteins such as histone, myeloperoxidase, and neutrophil elastase (NE).

RESULTS

In patients with perinuclear ANCA (p-ANCA) the detection of NETs by NE was able to distinguish AAV from infection/neoplasia and healthy controls. Receiver operating characteristic curves for serum NETs by NE in patients with p-ANCA were drawn in 2 situations: AAV versus infection/neoplasia, showing a sensitivity of 0.65 and specificity of 0.84, with an area under the curve of 65%; and AAV versus controls, showing a sensitivity of 0.84 and a specificity of 0.88, with an area under the curve of 96%.

CONCLUSIONS

For p-ANCA-positive individuals, we found higher serum NETs detected by NE-DNA in those with chronic infectious and neoplastic diseases than in AAV individuals and healthy controls. This allows us to infer that the evaluation of serum NETs may be of value as a biomarker for differential diagnosis.

Clinical Biomarkers in Otolaryngology-Head and Neck Surgery: Autoimmune Diseases

OBJECTIVE

The purpose of this article is to review the literature and compile promising and clinically relevant biomarkers in autoimmune disease related to otolaryngology-head and neck surgery.

STUDY DESIGN

Narrative review.

METHODS

Pubmed and Google Scholar were queried using combined key words such as "biomarkers" and "otolaryngology." Additional queries were made with combined key words such as "biomarkers" and a particular subspecialty such as "autoimmune" or "Meniere's" to maximize yield of relevant titles. Subsequently, specific biomarkers identified, such as "anti-TPO-antibodies," were used as key words. Relevant titles were reviewed and selected for abstract review. Applicable abstracts were then selected for review of the full text.

RESULTS

Biomarkers that are currently in clinical use for the management of autoimmune diseases within the field of otolaryngology were included in this review. The compiled biomarkers were then detailed individually regarding their molecular characteristics, function, and clinical significance.

CONCLUSIONS

Based on this literature review, there are several biomarkers currently in clinical use within the field of otolaryngology relating to autoimmune diseases. The majority of these biomarkers are in the form of proteins such as Cogan peptide and c-ANCA. This survey may serve as a comprehensive resource on biomarkers for autoimmune diseases in clinical otolaryngology.

Interference of anti-nuclear antibodies on determination of anti-neutrophil cytoplasmic antibodies in patients suspected of vasculitis: a case series

Anti-neutrophil cytoplasmic antibodies (ANCA) are mainly associated with medium and small vessel vasculitis. Two main methodologies currently available for detection of these antibodies are indirect immunofluorescence (IIF) and monospecific proteinase 3 (PR3) and myeloperoxidase (MPO) based immunoassays. However, well-defined guidelines regarding mode of testing for ANCA in laboratories still don't exist, leading to problems in diagnosis and further patient management. Anti-neutrophil cytoplasmic antibodies testing by IIF and enzyme linked immunosorbent assay (ELISA) often pose a significant challenge in diseases other than vasculitis and in overlapping autoimmune conditions. Anti-neutrophil cytoplasmic antibodies reporting by IIF can be challenging in certain circumstances. This case series aims to discuss four cases with probable interference of anti-nuclear antibodies (ANA) during ANCA testing by IIF resulting in ANCA false positivity. All four cases on subsequent reflex testing by line immunoassay (LIA) for PR3, MPO and glomerular basement membrane (GBM) antigens proved otherwise. While analysing for the presence of ANCA by IIF, the possible interference of ANA leading to a false positive ANCA result should be kept in mind and alternative methods of testing like ELISA, extended granulocyte based IIF assays with MPO and PR3 coated beads, etc., should also be advised. Probability of atypical ANCA in diseases other than vasculitis should also be considered in case of ambiguous results.

Changing Phenotypes and Clinical Outcomes Over Time in Microscopic Polyangiitis

Introduction

Diagnosis and management of microscopic polyangiitis (MPA) have evolved considerably over the past decades, but it is unknown whether clinical and histological presentation and patient and renal outcomes have changed accordingly.

Methods

We compared clinical and histopathological characteristic at diagnosis, risk of death, end-stage kidney disease (ESKD), and relapse rate in patients diagnosed with MPA between 1980 and 2022, after grouping them in 2 periods (p): p1980-2001 and p2002-2022. We compared the mortality rate between the 2 periods using Kaplan-Meier estimator and Cox-regression, and competing risks of ESKD and death using the Aalen-Johansen estimator, Fine-Gray multiple regression, and multistate models.

Results

Out of 187 patients, 77 were in p1980-2001 and 110 in p2002 to 2022. Patients in p2002 to 2022 were older (66.2 ± 14.0 SD vs. 57.7 ± 15.8; P < 0.001), had a better kidney function (estimated glomerular filtration rate [eGFR] 25.9 ± 24.8 vs. 21.5 ± 28.2 ml/min per 1.73 m2; P = 0.011) and a lower prevalence of the Berden sclerotic class (5.9 vs. 20.9%; P = 0.011). Despite a similar crude and adjusted patient survival, the risk of ESKD decreased during p2002 to 2022 (subdistribution hazard ratio [HR] 0.30, 95% confidence interval [CI]: 0.16-0.57; P < 0.001). The results remained significant after accounting for death after ESKD and after adjusting for potential confounders (HR 0.33 [95% CI: 0.18-0.63; P < 0.001]). The risk of relapse was numerically higher during p2002 to 2022 (subdistribution-HR 1.64 [95% CI: 0.95-2.83; P = 0.075]).

Conclusion

MPA kidney involvement has become less severe over the past decades, leading to a reduced risk of ESKD and a higher relapse rate, despite a comparable risk of death.

Improvement of indirect immunofluorescence technique to detect antineutrophil cytoplasmic antibodies and its impact on test positivity rate

The indirect immunofluorescence (IIF) technique for antineutrophil cytoplasmic antibodies (ANCA) detection is subject to substantial differences across laboratories. This study aimed to assess the impact of improvements in the IIF-ANCA technique on the positivity rate of ANCA tests. A cross-sectional study was performed with serum samples from patients with ANCA-associated vasculitis (AAV), autoimmune hepatitis (AIH), and ulcerative colitis (UC). A paired analysis was performed for IIF-ANCA results using the traditional method and a modified protocol after a series of specific adjustments in the technique based on the protocol of IIF-ANCA test performed at a nation-wide private laboratory in Brazil. ANCA specificity was assessed by ELISA for anti-proteinase 3 (PR3) and anti-myeloperoxidase (MPO) antibodies. Sixty-one patients were evaluated. The positivity rate of IIF-ANCA tests at disease presentation performed at the University reference laboratory was 32.3% in AAV, AIH, and UC patients, whereas the positivity rates of IIF-ANCA and ELISA tests in other laboratories were 75.0 and 72.7%, respectively. After modifications in the IIF-ANCA technique, there was a significant increase in the positivity rate (14.8 vs 34.3%; P=0.0002) and in median titers [1/40 (1/30-1/160) vs 1/80 (1/40-1/80); P=0.0003] in AAV, AIH, and UC patients. UC had the highest increment in positive results from 5.3 to 36.8%. There was poor agreement between MPO- or PR3-ANCA and both IIF-ANCA techniques. In conclusion, modifications in the IIF-ANCA protocol led to a significant improvement in its positivity rate and titers.

A case of left foot drop as initial symptom of granulomatosis with polyangiitis: Triggered by COVID-19 disease?

In Granulomatosis with polyangiitis (GPA), involvement of the peripheral nervous system is frequent but its occurrence as an initial presentation is unusual. This case highlights the importance of this occurrence to permit an early diagnosis. Moreover, GPA started after a coronavirus disease 2019 infection and could have been induced by this.

The physicians should recognize peripheral neuropathy as one of the first presentations of GPA, even if it’s rare, in order to permit an early diagnosis. Moreover, this case complements previously reported cases of COVID‐19‐induced auto‐immune disease.

Laboratory Diagnosis of ANCA-Associated Vasculitis (AAV) Using a Combination of Immunofluorescence Test (IIFT) and Line Immunoassay (LIA): Single-Centre Report From India

INTRODUCTION

Anti-neutrophil cytoplasmic autoantibodies (ANCA) associated vasculitis (AAV) is a small vessel vasculitis with insufficient epidemiological estimates in India. We aimed to determine demographic, clinical features, and laboratory diagnosis of AAV patients presenting to a large tertiary care centre in India.

MATERIAL AND METHODS

1289 patient samples were screened for ANCA by indirect immunofluorescence test (IIFT) and confirmation of ANCA target antigens was done by line immunoassay. Association between IIFT and LIA was determined in AAV.

RESULTS

By IIFT, ANCA was detected in 13.0% (168 out of 1289), of which 23.8% (40/168) were positive with P-ANCA pattern, 25.0% (42/168) were positive with C-ANCA and 47.6% (80/168) showed an atypical pattern. On evaluation with a line immunoassay, 6.7% (86/1289) were positive out of which 52.3% (45/86), 41.9% (36/86), 8.8% (6/86) were positive for anti-MPO, anti-PR3, and anti-GBM respectively. In eosinophilic granulomatosis with polyangiitis (EGPA) 87.5% (7/8), and microscopic polyangiitis (MPA/RLV) 91.3% (21/23), anti-MPO was the predominantly observed antibody. In granulomatosis with polyangiitis (GPA) anti-PR3 antibody was predominant in 87.5% (28/32) cases. Out of 168 IIF positive samples 8, 32, and 23 cases of EGPA, GPA, and MPA/RLV were observed respectively.

CONCLUSIONS

The primary aim of the study was to provide single-centre data to determine the laboratory diagnosis of AAV. A combination of IIFT and LIA was found to be an optimum testing strategy for the laboratory diagnosis of AAV.

Elevated Serum IgG4 Was Found in Eosinophilic Granulomatosis With Polyangiitis

OBJECTIVE

The aim was to determine the levels and clinical impact of immunoglobulin G4 (IgG4) and other IgG subclasses in a Chinese population with eosinophilic granulomatosis with polyangiitis (EGPA).

METHODS

We enrolled 49 patients who had EGPA, 27 who had granulomatosis with polyangiitis (GPA), 31 who had microscopic polyangiitis (MPA), and 30 healthy controls (HCs). Serum IgG subclasses were measured using commercial immunonephelometric assays and compared among different groups.

RESULTS

Fifteen EGPA patients (30.61%) had elevated IgG4 levels, based on a cutoff value of 135 mg/dL. In addition, 2 GPA patients (7.40%) and 1 MPA patient (3.33%) had elevated IgG4 levels. The EPGA group had a higher IgG4 level (65.60 mg/dL) than the GPA group (32.70 mg/dL, p = 0.0021), the MPA group (30 mg/dL, p = 0.0021), and the HC group (28.55 mg/dL, p = 0.0002). The EPGA group also had a higher IgG4/IgG ratio (0.0644) than the GPA group (0.0322, p = 0.13), the MPA group (0.0289, p = 0.0055), and the HC group (0.0212, p < 0.0001).

CONCLUSIONS

Our results indicate that Chinese patients with EGPA have increased levels of serum IgG4. Further study is needed to determine the pathogenic role of IgG4 and IgG4 antineutrophil cytoplasmic antibodies in EGPA.

Prevalence of Osteopenia in Drug-Naive Patients With Antineutrophil Cytoplasmic Antibody-Associated Vasculitis: A Monocentric Study

OBJECTIVES

To examine the bone mineral density and prevalence of osteoporosis and osteopenia in glucocorticoid- and immunosuppressive drug-naive patients younger than 55 years with antineutrophil cytoplasmic antibody-associated vasculitis (AAV).

METHODS

This was a cross-sectional study. We reviewed the medical records of 35 AAV patients and 35 age-, sex-, and body mass index (BMI)-matched control subjects. We collected clinical data such as AAV-related variables and conventional risk factors for osteoporosis and assessed bone mineral density and the prevalence of osteoporosis and osteopenia in both groups. Categorical and continuous variables were compared between the 2 groups using the χ2 or Fisher exact test and Mann-Whitney U test, respectively. Multivariate logistic regression analysis was used to calculate the odds ratio (OR).

RESULTS

There were no statistically significant differences between the demographical data of AAV patients and control subjects. Patients with AAV showed significantly higher frequencies of conventional risk factors for osteoporosis than the control subjects, except for hyperthyroidism. Osteopenia was found more commonly in AAV patients than in control subjects (57.1% vs. 31.4%, p = 0.030). In the univariate logistic regression analysis, BMI (OR, 0.813) and AAV (OR, 2.620) were associated with osteopenia in all participants. In the multivariate analysis, both BMI and AAV were associated with osteopenia, but this was not statistically significant. In contrast, when analyzing AAV patients only, neither conventional risk factors nor AAV-related variables were associated with the prevalence of osteopenia.

CONCLUSIONS

Antineutrophil cytoplasmic antibody-associated vasculitis and BMI were both associated with osteopenia.

A Comparative Evaluation of Antigen-Specific Sandwich Immunoassay and Indirect Immunofluorescence Assay (IIF) in Detecting Antineutrophil Cytoplasmic Antibodies: Are We Ready to Replace IIF with ELISA as the Primary Screening Method?

Background Antineutrophil cytoplasmic antibodies (ANCA) are important biomarkers in the diagnosis of ANCA-associated vasculitis, and indirect immunofluorescence (IIF) had been the method of choice for its detection from the very beginning. However, international consensus on ANCA testing (2017) advocates the use of high-quality immunoassays as the primary screening method. The purpose of this study was to evaluate the diagnostic performance of enzyme-linked immunosorbent assay (ELISA) compared to IIF in detecting ANCA. Methods One-hundred eighty-nine serum samples of suspected or known cases of systemic vasculitis were screened for ANCA by IIF and proteinase-3- and myeloperoxidase-ELISA. In IIF, positive results were further divided into cytoplasmic pattern of ANCA and perinuclear pattern of ANCA, depending upon the pattern of fluorescence. McNemar's chi-squared test was applied to check the equality of proportions of positive results, and Kappa statistics was used to measure the agreement between the two methods. Diagnostic performance of ELISA was evaluated taking IIF as reference. Results IIF detected ANCA in 17.5% cases and ELISA detected it in 11.6% cases. A good agreement between the overall performance of ELISA and IIF was observed ( K -value: 6.8, p -value: < 001). However, a significant difference in the proportion of positive results by the two methods was observed in McNemar's test (two-sided p -value: 0.007). Taking IIF as standard, ELISA showed 60.6% sensitivity, 98.7% specificity, and predictive value of positive and negative results of 90.9 and 92.2%, respectively. Conclusion The new generation antigen-specific ELISAs had high specificity but the chances of missing cases in primary screening due to the low sensitivity and high false negativity (39.4%) need to be dealt with.

Evaluation of PR3- and MPO-ANCA line and dot immunoassays in ANCA-associated vasculitis

OBJECTIVE

This study was performed to evaluate the diagnostic accuracy of novel line and dot immunoassays for detection of MPO and PR3 ANCA.

METHODS

Sera from 50 patients with ANCA-associated vasculitis (AAV), including granulomatosis with polyangiitis and microscopic polyangiitis, and from 45 disease controls were tested by IIF and for the presence of PR3-ANCA and MPO-ANCA by four different line or dot immunoassays, as well as by a chemiluminescence immunoassay.

RESULTS

The area under the curve of the receiver operating characteristic curve to discriminate AAV from controls was 0.858 (95% CI 0.785-0.931) for the IIF method. For the antigen-specific immunoassays, the area under the curve varied between 0.869 (95% CI 0.797-0.941) and 0.936 (95% 0.886-0.985).

CONCLUSIONS

Our comparison of various ANCA detection methods showed a high degree of diagnostic precision for all of the PR3- and MPO-ANCA line and dot immunoassays investigated. The performance was equal to or better than the performance of IIF. These results indicate that novel line and dot immunoassays can serve as a first-line test method in patients with the suspected diagnosis of AAV.

Levamisole and ANCA positivity in childhood nephrotic syndrome

BACKGROUND

This study aimed to determine the prevalence of ANCA positivity in children managed with levamisole as a steroid-sparing agent for nephrotic syndrome (NS).

METHODS

Medical records of children with steroid-sensitive NS managed with levamisole therapy at Sydney Children's Hospital between 1/1/2000 and 31/12/2018 were retrospectively reviewed. Main outcome measure was side effects of levamisole therapy including ANCA positivity.

RESULTS

Seventy-one children, median age 3 years and 1 month (IQR 29-68 months) at first presentation, were subsequently managed with levamisole. 60.6% were male and 65% Caucasian. 47.9% had frequently relapsing (FR)NS and 52.1% steroid-dependent (SD)NS. Overall, there was a median reduction in relapses from 3 (IQR 1-5) to 0.4 relapses (IQR 0-1) per year after levamisole was commenced. Levamisole was successful in preventing relapse in 19 (29%) patients and was used for median 24 (22 to 25) months. Levamisole was discontinued due to relapse in 25 patients (38%) after median 12 (5-28) months. Side effects occurred in 28 patients (42.4%); the most common side effect was ANCA positivity in 12 patients. In eleven of these patients, levamisole was discontinued; in one patient, low-level titres were documented and spontaneously resolved without cessation of levamisole. Two patients developed ANCA-associated vasculitis.

CONCLUSION

ANCA positivity is a common side effect of levamisole and was seen in 18.2% of our patients. Monitoring is required to determine side effects including ANCA positivity and treatment modified accordingly.

Increased prevalence rate of metabolic syndrome is an independent predictor of cardiovascular disease in patients with antineutrophil cytoplasmic antibody-associated vasculitis

OBJECTIVE

We investigated the prevalence of metabolic syndrome (MetS) in all or nonobese patients with antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) and compared it with age- and gender-matched controls. Also, we assessed the effect of variables at diagnosis on the risk of cardiovascular disease (CVD) in all or nonobese AAV patients.

METHODS

In this study, 173 AAV patients and 344 controls were included and MetS was defined by the National Cholesterol Education Program Adults Treatment Panel III criteria. The obesity based on body mass index (BMI) was defined as BMI ≥ 25 kg/m². The follow-up duration was defined as the period from diagnosis to the last visit or to each poor outcome occurrence.

RESULTS

The median age of AAV patients was 58.7 years and 57 patients were men. The prevalence of MetS was 50.9% in all AAV patients and 46.5% in nonobese AAV patients, which were significantly higher than 37.8% in all controls and 28.2% in nonobese controls. In Kaplan-Meier survival analysis, Mets at diagnosis significantly reduced the cumulative CVD-free survival rate in both all and nonobese AAV patients. In the multivariable Cox hazards model analysis, CVD during follow-up was significantly associated with both Birmingham vasculitis activity score (BVAS) (HR 1.159) and MetS at diagnosis (HR 9.036) in nonobese AAV patients.

CONCLUSIONS

The prevalence of MetS at diagnosis in all or nonobese AAV patients was significantly higher than those in all or nonobese controls. Furthermore, both BVAS and MetS at diagnosis increased the risk of CVD in nonobese AAV patients.

Antineutrophil Cytoplasmic Antibody in Lupus Nephritis: Correlation with Clinicopathological Characteristics and Disease Activity

BACKGROUND

Lupus nephritis (LN) represents 40%-50% of all systemic lupus erythematosus (SLE) patients, and rapidly progressive glomerulonephritis is associated with significant morbidity and mortality. Antineutrophil cytoplasmic antibody (ANCA) might be involved in the pathogenesis of LN.

OBJECTIVE

We evaluated the role of myeloperoxidase (MPO)-ANCA, proteinase 3 (PR3)-ANCA, and anti-glomerular basement membrane autoantibodies (anti-GBM autoAb) for the diagnosis of LN.

METHODS

In this cross-sectional study, 95 SLE patients were divided into 2 subgroups: LN group (n = 60) and non-LN group (n = 35). For further analysis, we subclassified the LN group into ANCA- positive (n = 16) and ANCA-negative (n = 44) LN patients. The entire Non-LN group was ANCA- negative. The SLE disease activity index (SLEDAI) was reported for each patient. Determination of MPO-ANCA, PR3-ANCA, and anti-GBM autoAb was performed using a novel multiplex bead-based technology in all patients. Data analyses were done using SPSS, version 20. Approval was obtained from the institutional review board of Zagazig University (ZU-IRB#6000).

RESULTS

Of 95 patients with SLE, 16 patients (16.84%) had ANCA-positive LN, all of which were MPO-ANCA. There was a positive correlation between MPO-ANCA and SLEDAI, as well as with class IV LN. Receiver operating characteristic analyses revealed that the sensitivity and specificity of MPO-ANCA were 81.3% and 99.8%, respectively, in discriminating LN from systemic lupus without nephritis.

CONCLUSION

MPO-ANCA level was significantly correlated with SLEDAI, inflammatory markers, kidney function tests, and LN class IV.

Clinical features of Korean elderly patients with antineutrophil cytoplasmic antibody-associated vasculitis

BACKGROUND/AIMS

We compared the clinical and laboratory data between elderly and non-elderly patients with antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) at diagnosis; further, we investigated the predictors at diagnosis for all-cause mortality and end-stage renal disease (ESRD) occurrence during follow-up in Korean elderly patients with AAV.

METHODS

We reviewed the medical records of 191 AAV patients regarding clinical manifestations and laboratory results at diagnosis and during follow-up. The follow-up duration was defined as the period from diagnosis to death for deceased patients or to the time of dialysis for ESRD patients, or to the last visit. Elderly (n = 67) and non-elderly (n = 124) patients were grouped based on an age threshold of 65 years.

RESULTS

At diagnosis, elderly patients exhibited higher median Birmingham Vasculitis Activity Score (BVAS) and higher frequencies of ANCA positivity and pulmonary manifestations than non-elderly patients. Furthermore, elderly patients exhibited increased median white blood cell count, blood urea nitrogen (BUN), alkaline phosphatase, erythrocyte sedimentation rate, and C-reactive protein and decreased median hemoglobin. However, there were no significant differences in all-cause mortality and ESRD occurrence between elderly and non-elderly patients. Meanwhile, elderly patients exhibited lower cumulative patients' and ESRD-free survival rates than non-elderly patients. In the multivariable Cox hazards model, BUN, creatinine and serum albumin at diagnosis were independent predictors for ESRD occurrence, whereas there were no independent predictors at diagnosis for all-cause mortality.

CONCLUSION

Elderly AAV patients exhibited substantially higher rates of all-cause mortality and ESRD occurrence during follow-up compared than non-elderly AAV patients.

Unclassifiable repeated antineutrophil cytoplasmic antibody (ANCA) positivity in diseases other than ANCA-associated vasculitis

BACKGROUND AND OBJECTIVE

Antineutrophil cytoplasmic antibody (ANCA) is a specific autoantibody for ANCA-associated vasculitis (AAV). However, ANCA can be detected in various diseases other than AAV. Hence, in this study, we investigated and provided the name of diseases with repeated ANCA positivity and the frequency of each disease other than AAV.

METHODS

We retrospectively screened the results of the tests of ANCA in 26,499 patients using the Clinical Data Repository System and included in this study only 173 patients with repeated ANCA positivity more than twice. 'Unclassifiable ANCA' was defined when ANCA was detected in patients with diseases other than AAV. 'Unclassifiable repeated ANCA' was also defined when unclassifiable ANCA was successively detected more than twice.

RESULTS

Among rheumatic and autoimmune diseases, the most common disease with unclassifiable repeated ANCA was vasculitis undetermined (21.0%). In terms of cardiovascular and cerebrovascular diseases, the most common disease with unclassifiable repeated ANCA was atherosclerotic heart disease (12.1%). In terms of disorders in liver, kidneys and lungs, the most common disease with unclassifiable repeated ANCA was chronic kidney disease (51 cases, 29.5%). In addition, among infections with confirmed infectious pathogens, the most common pathogen with unclassifiable repeated ANCA was varicella-zoster virus (6.9%) followed by Candida (4.6%).

CONCLUSION

Overall, regardless of category, the common diseases with unclassifiable repeated ANCA were chronic kidney disease followed by interstitial lung disease and vasculitis undetermined. Thus, we carefully suggest that physicians should pay more attention to the development of AAV or vasculitis other than AAV and, furthermore, kidneys and lungs should be monitored regularly and closely in patients with unclassifiable repeated ANCA.

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

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

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

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Dysregulated complement system primes neutrophils.

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

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

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.

Increasing incidence and prevalence of ANCA-associated vasculitis in Northern Norway

OBJECTIVE

ANCA-associated vasculitides (AAV) have increased in prevalence since the 1980s. We aimed to investigate the incidence and prevalence of AAV during a 15-year period from 1999 to 2013 in Northern Norway, looking for variations during this period.

METHODS

Patient records were retrieved from The Northern Norwegian Vasculitis Registry; in addition we searched all regional hospital databases. Patients diagnosed with AAV from 1999 through to 2013 were included. For prevalence data, patients residing in the area, but with AAV diagnosis prior to 1999, were also included. The diagnosis of AAV was based on the European Medicines Agency algorithm.

RESULTS

We identified 140 cases; 88 were classified as granulomatosis with polyangiitis (GPA), 37 as microscopic polyangiitis (MPA) and 15 as eosinophilic granulomatosis with polyangiitis (EGPA). Adult (age ≥15 years) annual incidence rates per million were as follows: for GPA 15.6 (95% CI: 12.5, 19.2), MPA 6.5 (95% CI: 4.6, 9.0), EGPA 2.7 (95% CI: 1.5, 4.5) and overall AAV 24.7 (95% CI: 20.8, 29.2). Incidences of MPA and overall AAV showed an increasing trend (P < 0.05). Adult point prevalence rates per million in 2013 were 261 (95% CI: 213, 316) for GPA, 58.2 (95% CI: 36.9, 87.3) for MPA, 32.9 (95% CI: 17.5, 56.3) for EGPA and 351 (95% CI: 296, 416) for overall AAV.

CONCLUSION

The incidence rate of GPA and the prevalence rates of GPA and EGPA are currently the highest reported. MPA increased significantly from a prior low incidence. The overall AAV annual incidence and prevalence are still increasing.

The biology, pathogenetic role, clinical implications, and open issues of serum anti-neutrophil cytoplasmic antibodies

Anti-neutrophil cytoplasmic antibodies (ANCA) are a group of autoantibodies, predominantly IgG, involved in the pathogenesis of several autoimmune disorders, detected either through indirect immunofluorescence or enzyme-linked immunosorbent assay. By means of indirect immunofluorescence, the main patterns are C-ANCA (cytoplasmic) and P-ANCA (perinuclear), while proteinase 3 (PR3) and myeloperoxidase (MPO) represent the main autoantigens in granulomatosis with polyangiitis and microscopic polyangiitis, both belonging to the family of ANCA-associated vasculitis (AAV). While several experiments established the pathogenicity of MPO-ANCA, evidence remains elusive for PR3-ANCA and an additional target antigen, i.e. LAMP2, has been postulated with specific clinical relevance. The presence of a subset of AAV without ANCA may be explained by the presence of further target antigens or the presence of molecules in blood which make ANCA undetectable. A rise in ANCA titers is not necessarily predictive of a flare of disease in AAV if not accompanied by clinical manifestations. ANCA may develop through variable mechanisms, such as autoantigen complementarity, apoptosis impairment, neutrophil extracellular traps dysfunction and molecular mimicry. We will provide herein a comprehensive review of the available evidence on the biological mechanisms, pathogenetic role, and clinical implications of ANCA testing and disease management. Further, we will address the remaining open challenges in the field, including the role of ANCA in inflammatory bowel disease and in cocaine-induced vasculitis.

Acute interstitial nephritis and PR3-ANCA following reintroduction of pembrolizumab: a case report

Renal toxicity from immune checkpoint inhibitors (ICIs) is an increasingly recognized cause of acute kidney injury among patients with cancer. ICI-associated acute kidney injuries typically present as acute interstitial nephritis and the timing of onset is highly variable. Herein, we present a case of a patient with relapsed metastatic melanoma previously treated with pembrolizumab who developed grade 3 immune-related renal toxicity after reintroduction of the same ICI, secondary to acute interstitial nephritis with accompanying high PR3-antineutrophil cytoplasmic antibody titer. The patient improved after steroid treatment and discontinuation of pembrolizumab. This case highlights the importance of not excluding ICI-related nephrotoxicity as a possible cause of renal failure, including in those who previously tolerated ICI treatment, since it is a treatable entity.

Serum granzyme B is associated with otorhinolaryngological, pulmonary, and renal involvement of antineutrophil cytoplasmic antibody-associated vasculitis

We investigated whether serum granzyme B (GrB) can reflect the inflammatory burden such as cross-sectional disease activity and organ-specific involvement in immunosuppressive drug-naïve patients with antineutrophil cytoplasmic antibody-associated vasculitis (AAV). Seventy-eight immunosuppressive drug-naïve patients with AAV were included in this study. At the time of the first classification, whole blood was obtained from each patient and sera was immediately isolated and stored at - 80℃. On the day of the blood sampling, we performed routine laboratory tests including antineutrophil cytoplasmic antibody tests and collected both clinical and laboratory data. AAV-specific indices included Birmingham Vasculitis Activity Score (BVAS) and Five-Factor Score (FFS). The median age of patients with AAV was 62 years and 26 patients were men. Serum GrB was not associated with the cross-sectional BVAS; however, patients with serum GrB positivity exhibited higher frequencies of otorhinolaryngological manifestation than those without (p=0.037). When serum GrB levels were compared after dividing the patients into two groups based on the presence of organ-specific involvement, patients with pulmonary involvement exhibited a significantly higher serum GrB than those without (p=0.042). On the other hand, patients with renal involvement showed a significantly lower serum GrB than those without (p=0.023). In addition, serum GrB was inversely correlated with the cross-sectional FFS (r=-0.249, p=0.028). Even though serum GrB could not reflect the inflammatory burden of AAV, serum GrB was associated with otorhinolaryngological, pulmonary, and renal involvement in immunosuppressive drug-naïve patients with AAV.

Frequency of Positive ANCA Test in a Population With Clinical Symptoms Suggestive of Autoimmune Disease and the Interference of ANA in its Interpretation

BACKGROUND

Antibodies against neutrophil cytoplasm (ANCA) are associated with vasculitis. There are different methods to determine their presence. The interference of antinuclear antibodies (ANA) in the differentiation between P-ANCA and C-ANCA patterns has been described.

OBJECTIVE

To determine the frequency of ANCA in a population with manifestations of autoimmune disease, and evaluate the interference of ANA in its interpretation.

MATERIALS AND METHODS

Retrospective, descriptive nonexperimental cross-sectional study, including 3,330 data. The presumptive diagnosis was autoimmune disease and a test for ANCA was requested. The ANCA and ANA determinations were made by indirect immunofluorescence, L-ANCA® and CytoBead® ANCA. Anti-proteinase 3 and anti-myeloperoxidase were detected by ELISA and CytoBead® ANCA.

RESULTS

ANCAs were positive in 10.21% and 12.64% of those positive for ANCA were positive for ANA. The inter-rater agreement statistic (Kappa) for anti-PR3 between CytoBead ANCA and ELISA was 100% (K=1.00; P<.05) and the agreement between anti- myeloperoxidase by ELISA and CytoBead® ANCA was high (K=0.94; P<.05). 30% of those with ANCAs had a diagnosis of a type of vasculitis; 20% of them had an autoimmune disease.

CONCLUSIONS

The results suggest an overestimated request for ANCAs as a diagnostic aid in primary care which was not addressed. For an adequate evaluation of ANCAs, the indirect immunofluorescence technique should be implemented for the control and confirmation with the determination of specific antigens for anti- proteinase 3 and anti- myeloperoxidase in any of the confirmatory assays. The high concordance shown by ANCA CytoBeads makes us consider the use of this alternative for the determination of ANCAs and the confirmation. Given the interference of ANAs, the ANA test by IFI in the presence of positive P-ANCA results is recommended in order to minimize "false positives".

Laboratory Diagnosis of ANCA-Associated Vasculitis (AAV) Using a Combination of Immunofluorescence Test (IIFT) and Line Immunoassay (LIA): Single-Centre Report From India

INTRODUCTION

Anti-neutrophil cytoplasmic autoantibodies (ANCA) associated vasculitis (AAV) is a small vessel vasculitis with insufficient epidemiological estimates in India. We aimed to determine demographic, clinical features, and laboratory diagnosis of AAV patients presenting to a large tertiary care centre in India.

MATERIAL AND METHODS

1289 patient samples were screened for ANCA by indirect immunofluorescence test (IIFT) and confirmation of ANCA target antigens was done by line immunoassay. Association between IIFT and LIA was determined in AAV.

RESULTS

By IIFT, ANCA was detected in 13.0% (168 out of 1289), of which 23.8% (40/168) were positive with P-ANCA pattern, 25.0% (42/168) were positive with C-ANCA and 47.6% (80/168) showed an atypical pattern. On evaluation with a line immunoassay, 6.7% (86/1289) were positive out of which 52.3% (45/86), 41.9% (36/86), 8.8% (6/86) were positive for anti-MPO, anti-PR3, and anti-GBM respectively. In eosinophilic granulomatosis with polyangiitis (EGPA) 87.5% (7/8), and microscopic polyangiitis (MPA/RLV) 91.3% (21/23), anti-MPO was the predominantly observed antibody. In granulomatosis with polyangiitis (GPA) anti-PR3 antibody was predominant in 87.5% (28/32) cases. Out of 168 IIF positive samples 8, 32, and 23 cases of EGPA, GPA, and MPA/RLV were observed respectively.

CONCLUSIONS

The primary aim of the study was to provide single-centre data to determine the laboratory diagnosis of AAV. A combination of IIFT and LIA was found to be an optimum testing strategy for the laboratory diagnosis of AAV.

The performance of the chemiluminescent immunoassay for measuring serum myeloperoxidase and proteinase 3 antibodies

Background

Enzyme‐linked immunosorbent assay (ELISA) has traditionally been used to detect myeloperoxidase (MPO) and proteinase 3 (PR3) antibodies, although it is time‐consuming and physically demanding. As a novel and highly effective immunoassay, we compared chemiluminescent immunoassay (CIA) with ELISA to verify the application value of CIA in MPO and PR3 antibodies detection.

Methods

By ELISA and CIA, serum levels of anti‐MPO and anti‐PR3 antibodies were measured in 63 anti‐neutrophil cytoplasmic antibody (ANCA)‐associated vasculitis (AAV) patients (AAV group), including 47 microscopic polyangiitis (MPA) patients and 16 granulomatosis with polyangiitis (GPA) patients, in addition, 68 patients in interference control group (IC group), 19 healthy subjects in healthy control group (HC group). We compared MPO and PR3 antibodies levels and positive rates measured by these two methods among groups. Relationship and coincidence rate between ELISA and CIA were investigated. Diagnostic values for clinical outcomes for MPO and PR3 antibodies were assessed by receiver operator characteristic (ROC) curve.

Results

In AAV patients, when detecting anti‐MPO (r = .90) and anti‐PR3 (r = .81), CIA was highly correlated with ELISA, companying with highly total (88.89%, 92.06%, respectively) and positive coincidence rates (84.78%, 77.27%, respectively). In HC group, anti‐PR3 positive rate detected by both immunoassay were 0, anti‐MPO almost were 0, which without statistically significant difference (P = .32). In IC group, the total (76.47%, 58.82, respectively) and positive coincidence rates (48.38%, 30.00%, respectively) of anti‐MPO and anti‐PR3 were the lowest, but the negative coincidence rates reached 100%. By CIA, similar to ELISA, the levels of anti‐MPO were significantly higher both in AAV patients (56.00; [4.40‐235.30]) and MPA patients (98.00; [27.90‐324.70]) compared with either IC group (3.20; [3.20‐18.55) (P < .0001) or HC group (3.20; [3.20‐3.20]) (P < .0001), yielded an area under curve (AUC) of 0.76 for AAV and 0.89 for MPA, the concentration of anti‐PR3 in GPA group (66.65; [24.43‐150.00]) was significantly higher than that in IC group (2.3; [2.3‐10.95]) (P < .0001) and HC group (2.3; [2.3‐2.3]) (P < .0001), with an AUC of 0.92.

Conclusion

Similar to ELISA, CIA was competent to detect MPO and PR3 antibodies in AAV patients and healthy population, thus distinguish AAV patients from IC group and HC group and effectively diagnose MPA and GPA.

Peripheral Neuropathies Associated With Vasculitis and Autoimmune Connective Tissue Disease

PURPOSE OF REVIEW

This article discusses peripheral neuropathies associated with vasculitis (isolated or in the setting of systemic vasculitis) and autoimmune connective tissue disease and provides a brief overview of their diagnostic evaluation and management.

RECENT FINDINGS

The classification of systemic vasculitic neuropathy and nonsystemic vasculitic neuropathy continues to evolve. Classification according to the presence of antineutrophil cytoplasmic antibodies and their subtypes facilitates prognostication and management. Recent research on antineutrophil cytoplasmic antibody-associated vasculitis has added to our understanding of its neurologic complications. The treatment of vasculitis is also evolving, and new nonsystemic vasculitic neuropathy classification has impacted the treatment and management of this disorder. New classification criteria for Sjögren syndrome (which commonly causes neurologic complications) facilitate accurate and timely diagnosis.

SUMMARY

Vasculitis and autoimmune connective tissue disease are underrecognized and treatable causes of peripheral neuropathy. Furthermore, peripheral neuropathy may reveal an underlying rheumatologic or vasculitic disorder. Rapid recognition and treatment are essential. Familiarity with the diagnosis and treatment of neuropathies in the setting of connective tissue disease and vasculitis reduces morbidity and, in some cases, mortality.

The role of surgery in antineutrophil cytoplasmic antibody-associated vasculitides affecting the nose and sinuses: A systematic review

Background:

The ear, nose and throat region has been reported to be one of the commonest sites involved in antineutrophil cytoplasmic antibody (ANCA)–associated vasculitis diseases and often precedes the diagnosis of ANCA–associated vasculitis by many months. Although treatment for ANCA–associated vasculitis primarily requires systemic immunosuppressive therapy, there are specific indications for sinonasal surgery during the course of the disease process. The three major roles for surgery in sinonasal vasculitis are to aid diagnosis through biopsy, enable symptom relief and nasal reconstructive surgery consideration when in remission.

Purpose:

The aim of this systematic review is to provide an overview of the surgical procedures which can be performed in patients with ANCA–associated vasculitis presenting with sinonasal involvement.

Materials and methods:

A systematic literature search was performed for scientific articles on MEDLINE (PubMed Advanced MEDLINE Search) and EMBASE. The search included all articles up to April 2020.

Conclusion:

Surgical intervention during the active phase of ANCA–associated vasculitis disease can improve the patient’s symptoms and enable histological diagnosis. The surgical decision to manage the nose requires a multidisciplinary approach involving the vasculitis specialist and the ear, nose and throat surgeon. Nasal reconstruction can be performed to restore form and function but only when the disease is in remission so as to maximise success and minimise complications.

Association between the antineutrophil cytoplasmic antibody and late coronary arterial occlusive disease in patients with Takayasu arteritis

BACKGROUND

No study has provided evidence of the clinical significance of the antineutrophil cytoplasmic antibody (ANCA) in patients with Takayasu arteritis (TAK). Therefore, we investigated the frequency of ANCA positivity and its clinical implications in patients with TAK.

METHODS

We retrospectively reviewed the medical records of 121 patients with established TAK, who had results for ANCA status at diagnosis. We collected demographic and clinical data and the ANCA results at diagnosis. Additionally, we obtained information on patients' medications and complications during follow-up. Early coronary arterial occlusive disease (CAOD) and late CAOD were defined based on a 30-day interval after TAK classification. The chi-square test, Fisher's exact test, Mann-Whitney test, and Kaplan-Meier survival analysis were used to analyze the data.

RESULTS

The patients' mean age was 44.6 years, and 21 patients were men (17.4%). ANCA was detected in 8 patients (6.6%), of which 2 had both the myeloperoxidase ANCA (or perinuclear ANCA) and proteinase 3 ANCA (or cytoplasmic ANCA). Early CAOD was observed in 10 patients (8.3%), and late CAOD was found in 9 patients (7.4%). In the comparative analysis, the proportion of late CAOD exhibited a tendency to increase in the ANCA-positive group compared to that in the ANCA-negative group. Kaplan-Meier analysis showed that patients with ANCA exhibited a lower cumulative late CAOD-free survival rate than those without ANCA (p=0.012). When the algorithm for the classification of ANCA-associated vasculitis (AAV) proposed by the European Medicine Agency in 2007 was applied to 8 patients with ANCA, all were not reclassified as having AAV.

CONCLUSIONS

ANCA can be detected in a minority of patients with established TAK, and it may not contribute to the reclassification of AAV. Furthermore, ANCA positivity may be associated with late CAOD in patients with TAK.

Autoantibody Biomarkers in Rheumatic Diseases

Autoantibodies encountered in patients with systemic rheumatic diseases bear clinical significance as a biomarker to help or predict diagnosis, clinical phenotypes, prognosis, and treatment decision-making. Furthermore, evidence has accumulated regarding the active involvement of disease-specific or disease-associated autoantibodies in the pathogenic process beyond simple association with the disease, and such knowledge has become essential for us to better understand the clinical value of autoantibodies as a biomarker. This review will focus on the current update on the autoantibodies of four rheumatic diseases (rheumatoid arthritis, myositis, systemic sclerosis, and anti-neutrophil cytoplasmic antibody associated vasculitis) where there has been a tremendous progress in our understanding on their biological effects and clinical use.

Comparison between enzyme-linked immunosorbent assay and indirect immunofluorescence for detection of antineutrophil cytoplasmic antibodies

Objective

To evaluate the performance of enzyme-linked immunosorbent assay and indirect immunofluorescence methods for the detection of antineutrophil cytoplasmic antibodies in a routine clinical laboratory setting.

Methods

A total of 227 samples were tested by indirect immunofluorescence and enzyme-linked immunosorbent assay with antigen specificity for antiproteinase 3 and antimyeloperoxidase. The proportions of positive samples were compared by McNemar hypotheses and agreement was described by Cohen’s Kappa coefficient.

Results

The agreement of the tests was 96.5%, and the Kappa coefficient obtained was 0.70 (95%CI: 0.50-0.90; p<0.001). Considering indirect immunofluorescence as the gold standard, the sensitivity of the enzyme-linked immunosorbent assay was 0.62 and the specificity was 0.99, with diagnostic accuracy in 96% of cases. Some samples were negative in enzyme-linked immunosorbent assay and positive in indirect immunofluorescence. This situation occurred in all immunofluorescence patterns, but particularly in atypical patterns. Two samples with antiproteinase 3 positivity were considered negative in indirect immunofluorescence.

Conclusion

The enzyme-linked immunosorbent assay had high specificity but lower sensitivity. The performance of indirect immunofluorescence increases diagnostic sensitivity, while the search for antiproteinase 3 by enzyme-linked immunosorbent assay may also add diagnostic power.

Can antineutrophil cytoplasmic antibody positivity at diagnosis predict the poor outcomes of Sjögren's syndrome?

We investigated the clinical implication of ANCA positivity at diagnosis on the poor outcomes in patients with Sjögren's syndrome. The medical records of 606 Korean patients with Sjögren's syndrome were retrospectively reviewed. The results of perinuclear (P)-ANCA, myeloperoxidase (MPO)-ANCA, cytoplasmic (C)-ANCA, and proteinase 3 (PR3)-ANCA were collected and the frequencies of all-cause mortality, interstitial lung disease (ILD), end-stage renal disease (ESRD), and lymphoma were assessed as the poor outcomes of Sjögren's syndrome. Comparison of the cumulative patient survivals between the two groups was analysed by the Kaplan-Meier survival analysis. Of the 606 patients, ANCA was detected in 10.2% of Sjögren's syndrome patients without AAV. Twenty-one patients (3.5%) died, 99 patients (16.3%) suffered from ILD, and 8 patients had ESRD. Lymphoma occurred in 5 patients (0.8%) during 37.5 months. Sjögren's syndrome patients with ANCA positivity exhibited a lower cumulative ILD-free survival rate than those with ANCA negativity (P = 0.001). Sjögren's syndrome patients with P-ANCA positivity and those with MPO-ANCA (or P-ANCA) positivity showed a lower cumulative ILD-free survival rate than those without (P = 0.012 and P < 0.001). Also, Sjögren's syndrome patients with P-ANCA positivity exhibited a lower cumulative ESRD-free survival rate than those without (P = 0.043). ANCA positivity was associated with neither all-cause mortality nor lymphoma in Sjögren's syndrome patients. ANCA positivity and MPO-ANCA (or P-ANCA) positivity at diagnosis was associated with the development of ILD during follow-up in patients with Sjögren's syndrome.

Detection by flow cytometry of anti-neutrophil cytoplasmic antibodies in a novel approach based on neutrophil extracellular traps

BACKGROUND

Anti-neutrophil-cytoplasmic antibodies (ANCA) are auto-antibodies directed against components of neutrophil granulocytes and may be found in various inflammatory conditions, like small-vessel vasculitis or ulcerative colitis (UC). Routine ANCA screening is performed on ethanol-fixed neutrophils using indirect immunofluorescence technique. Yet, how neutrophil granule proteins become available to immunologic presentation is a matter of debate. In recent years, various studies have shown that neutrophils are able to extrude their chromatin decorated with granular proteins as neutrophil extracelullar traps (NETs).

AIM

We hypothesized that (I) ANCA immunoreactivity may be found on NETs and (II) NETs may serve as a useful tool in a novel approach for ANCA detection.

METHODS

Sera from patients suffering from either ANCA-associated vasculitis (n = 10), UC (n = 30) or sera from patients without diagnosed ANCA-associated diseases (n = 20), respectively, were subjected to indirect immunofluorescence and a newly developed method to detect ANCA by flow cytometry employing microbead technology.

RESULTS

ANCA-related immunofluorescence was readily detectable on ethanol-fixed NETs, establishing NETs as a structure carrying ANCA target antigens. Moreover, we observed that neutrophils form NETs in response to microbeads and stick to the surface of these beads. Using these NET-coated microbeads in flow cytometry, we were capable of reliably detecting p-ANCA, c-ANCA, and a-ANCA in tested patient sera. UC-related complex DNase-1-sensitive ANCA (NET-ANCA) antigens were also detected on NET-coated microbeads.

CONCLUSION

NET-coated microbeads may be commercially developed as a novel tool for automated ANCA screening assays using flow cytometry.

Antineutrophil Cytoplasmic Antibodies Testing and Interpretation

The discovery of antineutrophil cytoplasmic antibodies (ANCA) helped establish ANCA-associated vasculitis as a separate and well-defined clinical entity. Its progressive incorporation into the clinical diagnosis algorithms has made ANCA testing a cornerstone immunoassay embedded in the management of ANCA-associated vasculitis. After its description by indirect immunofluorescence, proteinase-3 and myeloperoxidase were identified as principal ANCA targets. ANCA, and proteinase-3 and myeloperoxidase immunoassessment, have undergone iterative rounds of improvement in sensitivity and specificity. This article traces landmarks in the development of ANCA tests, describes common pitfalls arising during ANCA interpretation, and discusses new technologies to improve the future of ANCA testing.

Multivariable index for assessing the activity and predicting all-cause mortality in antineutrophil cytoplasmic antibody-associated vasculitis

Background

So far, there has been no tool to estimate activity at diagnosis and predict all‐cause mortality in patients with ANCA‐associated vasculitis (AAV). Hence, we determined the initial predictors of them in patients with AAV.

Methods

We retrospectively reviewed the medical records of 182 patients with AAV. Severe AAV was defined as Birmingham Vasculitis Activity Score (BVAS) ≥ 16. The cutoffs were extrapolated by the receiver operator characteristic (ROC) curve. The odds ratio (OR) and the relative risk (RR) were assessed using the multivariable logistic regression analysis and the chi‐square test, respectively.

Results

In the comparison analysis, patients with severe AAV exhibited the higher neutrophil and platelet counts, creatinine, erythrocyte sedimentation rate and C‐reactive protein, and the lower lymphocyte count, hemoglobin, and serum albumin than those without. In the multivariable logistic regression analysis, creatinine ≥ 0.9 mg/dL (OR 2.264), lymphocyte count ≤ 1430.0/mm³ (OR 1.856), and hemoglobin ≤ 10.8 g/dL (OR 2.085) were associated with severe AAV. We developed a new equation of a multivariable index for AAV (MVIA) = 0.6 × (Lymphocyte count ≤ 1430.0/mm³) + 0.7 × (Hemoglobin ≤ 10.8 g/dL) + 0.8 × (Creatinine ≥ 0.9 mg/dL). The optimal cutoff of MVIA for severe AAV was set as 1.35. Severe AAV was identified more frequently in patients with MVIA at diagnosis ≥1.35 than those without (RR 4.432). Patients with MVIA at diagnosis ≥1.35 exhibited the lower cumulative patient survival rate than those without.

Conclusion

Multivariable index for AAV could assess the cross‐sectional activity and predict all‐cause mortality in patients with AAV.

Neutrophil extracellular traps (NET) induced by different stimuli: A comparative proteomic analysis

Neutrophil extracellular traps (NET) formation is part of the neutrophil response to infections, but excessive or inappropriate NETosis may trigger the production of autoantibodies and cause organ damage in autoimmune disorders. Spontaneously netting neutrophils are not frequent and induction of NET in vitro by selected stimuli is necessary to investigate their structure. In the present work, the protein composition and post-translational modifications of NET produced under different stimuli have been studied by means of proteomic analysis. Neutrophils from healthy donors were stimulated by PMA, A23187, Escherichia coli LPS or untreated; after three hours, cells were washed, treated with DNase and supernatants collected for mass spectrometry. Data were analyzed by unsupervised hierarchical clustering analyses. We identified proteins contained in NETs of any source or exclusive of one stimulus: LPS-induced and spontaneous NET diverge in protein composition, while PMA- and A23187-induced NET appear more similar. Among the post-translational modifications we examined, methionine sulfoxidation is frequent especially in PMA- and LPS-induced NETs. Myeloperoxidase is the protein more extensively modified. Thus, proteomic analysis indicates that NETs induced by different stimuli are heterogeneous in terms of both protein composition and post-translational modifications, suggesting that NET induced in different conditions may have different biological effects.

An international survey on anti-neutrophil cytoplasmic antibodies (ANCA) testing in daily clinical practice

Background:

Detection of anti-neutrophil cytoplasmic antibodies (ANCA) is important for the diagnosis of the ANCA-associated vasculitides (AAV). For AAV, especially ANCA directed against myeloperoxidase (MPO) and proteinase 3 (PR3) are most relevant. ANCA with less well-defined specificities may, however, also be detected in other inflammatory and non-inflammatory conditions.

Methods:

A questionnaire, initiated by the European Autoimmunity Standardisation Initiative (EASI), was used to gather information on methods and testing algorithms used for ANCA in clinical laboratories of 12 European countries (EASI survey).

Results:

Four hundred and twenty-nine responses were included in the EASI survey analysis which revealed differences within countries and between countries. Laboratories overall were poor in adherence to international consensus on ANCA testing. Substantial variation was observed with respect to the use of ANCA indirect immunofluorescence (IIF) in the algorithm, application of distinct methods for MPO- and PR3-ANCA, the daily availability of new ANCA results, and interpretation of test results.

Conclusions:

Awareness of these differences may stimulate further harmonization and standardization of ANCA testing. This may be promoted by an update of the international ANCA consensus and the introduction of international standards.

ANCA-Associated Vasculitides and Hematologic Malignancies: Lessons from the Past and Future Perspectives

The purpose of this paper is to collect and summarize all evidences relating to an association between ANCA-associated vasculitides (AAVs) and hematologic malignancies, in the form of either a paraneoplastic vasculitis or leukemias and lymphomas developing on a preexisting vasculitis. Additionally, the role of cyclophosphamide in vasculitis treatment has been assessed and compared to rituximab. Paraneoplastic AAV seems to be an uncommon presentation of hemopathies. Hematologic malignancy risk in AAV is more likely to be increased by cyclophosphamide, although not yet definitely proven. Furthermore, the pathogenesis of ANCA-associated vasculitis has been reviewed with particular emphasis on the role of proteinase 3 (PR3) in fuelling granulomatosis with polyangiitis (GPA) inflammation. PR3 is a bactericidal protein expressed by neutrophilic granules and on their plasma membrane. Derangements in its expression and function have been linked to leukemias and GPA alike. PR3-derived PR1 peptide is being studied as an immunotherapy target in leukemia and multiple myeloma. This study is aimed at bringing together various evidences from the field of immunological and hematological research, at exposing contradictions, and at revealing novel insights on the association between ANCA-associated vasculitis and hematologic malignancies.

The Diagnostic and Clinical Utility of Autoantibodies in Systemic Vasculitis

Considerable progress has been made in understanding the role of autoantibodies in systemic vasculitides (SV), and consequently testing for anti-neutrophil cytoplasmic antibodies (ANCA), anti-glomerular basement membrane antibodies (anti-GBM), and anti-C1q antibodies is helpful and necessary in the diagnosis, prognosis, and monitoring of small-vessel vasculitis. ANCA-directed proteinase 3 (PR3-) or myeloperoxidase (MPO-) are sensitive and specific serologic markers for ANCA-associated vasculitides (AAV), anti-GBM antibodies are highly specific for the patients with anti-GBM antibody disease (formerly Goodpasture’s syndrome), and autoantibodies to C1q are characteristic of hypocomlementemic urticarial vasculitis syndrome (HUVS; anti-C1q vasculitis). The results of a current EUVAS study have led to changes in the established strategy for the ANCA testing in small-vessel vasculitis. The revised 2017 international consensus recommendations for ANCA detection support the primary use PR3- and MPO-ANCA immunoassays without the categorical need for additional indirect immunofluorescence (IIF). Interestingly, the presence of PR3- and MPO-ANCA have led to the differentiation of distinct disease phenotype of AAV: PR3-ANCA-associated vasculitis (PR3-AAV), MPO-ANCA-associated vasculitis (MPO-AAV), and ANCA-negative vasculitis. Further studies on the role of these autoantibodies are required to better categorize and manage appropriately the patients with small-vessel vasculitis and to develop more targeted therapy.

Systemic immune-inflammation index could estimate the cross-sectional high activity and the poor outcomes in immunosuppressive drug-naïve patients with antineutrophil cytoplasmic antibody-associated vasculitis

OBJECTIVES

We investigated whether systemic immune-inflammation index (SII) at diagnosis can estimate the cross-sectional high activity and predict the poor outcomes in immunosuppressive drug-naïve patients with antineutrophil cytoplasmic antibody-associated vasculitis (AAV).

METHODS

We retrospectively reviewed the medical records of 163 patients with AAV and obtained clinical and laboratory data. We calculated Birmingham vasculitis activity score (BVAS) as well as five-factor score (FFS) (2009) at diagnosis. SII at diagnosis was calculated by the equation of (SII at diagnosis = platelet count × neutrophil count/lymphocyte count at diagnosis). Severe AAV was defined as BVAS at diagnosis ≥16. The odds ratio was assessed using the multivariable logistic regression analysis and cumulative survival rates were compared by the Kaplan-Meier survival analysis.

RESULTS

The median age at diagnosis was 58.0 years old and 51 patients were men. The median BVAS was 12.0. Fifty-seven patients had severe AAV. The median SII at diagnosis was 1349.6. In the multivariable analysis, only SII exhibited a significant odds ratio for the cross-sectional severe AAV (P = 0.043). We obtained the cut-off of SII at diagnosis for severe AAV as 1573.56. Patients with SII at diagnosis ≥1573.56 exhibited a significantly high relative risk of the cross-sectional severe AAV compared to those without (relative risk 4.625). Furthermore, patients with SII at diagnosis ≥1573.56 exhibited significantly the lower cumulative relapse free and renal survivals than those without.

CONCLUSION

Systemic immune-inflammation index at diagnosis could estimate the cross-section severe AAV and predict the poor outcomes in AAV patients.

Laboratory Assessment of Patients with Suspected Rheumatic Musculoskeletal Diseases: Challenges and Pitfalls

Current patient care in rheumatology relies primarily on a combination of traditional clinical assessment and standard laboratory tests. Investigators seek to discover new biomarkers and novel technologies to boost the research in this field. Mechanistic biomarkers such as cytokines, cell types, antibodies, signaling molecules, are rooted in the mechanism underlying the disease and can guide the clinical management of the disease. Conversely, descriptive biomarkers are byproducts of the disease process, depict the state of a disease but are not involved in its pathogenesis. In this article, we reviewed the field of common laboratory biomarkers in rheumatology, highlighting both their descriptive or mechanistic value as well as their role in clinical practice.

Should nasal biopsy inevitably be performed for classifying granulomatosis with polyangiitis in patients with rhinosinusitis? A retrospective chart review study

Nasal biopsy is the essential method for differentiating and diagnosing granulomatosis with polyangiitis (GPA) in patients with chronic rhinosinusitis. Nevertheless, in the real clinical settings, there are several cases unable for nasal biopsy. Hence, in this study, we investigated initial clinical manifestations and laboratory factors which could be helpful for diagnosing GPA in cases unable for nasal biopsy performance. We retrospectively reviewed the medical records of 45 patients with GPA. Twenty-five patients exhibited chronic rhinosinusitis, among which 16 patients underwent nasal biopsy. We applied the 2007 European Medicines Agency algorithm for the classification of GPA, the 2012 Chapel Hill Consensus Conferences Nomenclature of Vasculitis and the 2017 American College of Rheumatology/European League Against Rheumatism provisional classification criteria for GPA to them for reclassifying GPA. Among six patients without granuloma on nasal biopsy, three patients with only antineutrophil cytoplasmic antibody (ANCA) and chronic rhinosinusitis could be classified as GPA due to proteinase 3 (PR3)-ANCA (or cytoplasmic (C)-ANCA) positivity. Among nine patients without nasal biopsy, three patients with only chronic rhinosinusitis could be classified as GPA due to GPA-specific lung lesions. When we excluded an item of granuloma in ten GPA patients with granuloma on nasal biopsy, four patients without ANCAs could be classified as GPA due to GPA-specific lung lesions and cartilaginous involvement. In conclusion, PR3-ANCA (or C-ANCA) positivity, GPA-specific lung lesions and cartilaginous involvement could help physicians in charge make a final diagnosis of GPA in cases unable for nasal biopsy.

Persistent antiphospholipid antibodies are associated with thrombotic events in ANCA-associated vasculitis: A retrospective monocentric study

AIM

We investigated whether persistent antiphospholipid syndrome (APLAs) at diagnosis are associated with the risk of thrombotic events during follow-up in patients with ANCA-associated vasculitis (AAV).

METHODS

We retrospectively reviewed the medical records of 138 AAV patients. Thrombotic events were defined as arterial and venous thrombosis confirmed by magnetic resonance imaging, computed tomography, angiography and Doppler ultrasonography. Clinical and laboratory variables at diagnosis and during follow-up between patients with and without thrombotic events were compared. The univariable and multivariable Cox hazard model analyse to appropriately obtain hazard ratio (HR) considering the follow-up duration were conducted.

RESULTS

The mean age of 138 AAV patients was 55.1 years and 44 were male. Persistent APLAs were detected in 18 patients with AAV (13.0%). Thrombotic events were observed in 26 patients with AAV (18.8%) during follow-up. At the time of a retrospective study point, persistent APLAs at diagnosis were observed more frequently in patients with thrombotic events than those without. In the multivariable Cox hazard model analysis, age at diagnosis (HR 1.075) and persistent APLAs (HR 2.902), but not ANCAs. Thrombotic events were identified more frequently in patients with persistent APLAs at diagnosis than those without (38.9% vs. 15.8%, relative risk 3.383).

CONCLUSION

Persistent APLAs at diagnosis are significantly associated with the risk of thrombotic events during follow-up of AAV. We suggest that physicians should closely monitor the development of thrombotic events during follow-up.

Prognostic nutritional index is associated with disease severity and relapse in ANCA-associated vasculitis

AIM

The prognostic nutritional index (PNI), calculated by serum albumin and peripheral blood lymphocyte count, is considered to reflect immune-related nutritional status. In this study, we first investigated the clinical significance of PNI in patients with antineutrophil cytoplasmic antibody-associated vasculitis (AAV).

METHOD

Medical records of 160 patients classified as AAV from October 2000 to September 2017 were reviewed. We calculated the Birmingham vasculitis activity score (BVAS) and collected laboratory data including erythrocyte sedimentation rate (ESR), C-reactive protein (CRP) level, white blood cell, lymphocyte, and platelet counts, and serum albumin, aspartate aminotransferase, and alanine aminotransferase levels at diagnosis. PNI at diagnosis was calculated as (10 × serum albumin [g/dL] + 0.005 × lymphocyte count [/mm³ ]). Associations between laboratory variables, PNI, and BVAS were assessed by linear regression analyses, and Cox proportional hazard analysis was used to evaluate factors associated with disease relapse.

RESULTS

The mean age was 55.2 years and 48 patients (30.0%) were male. In univariable linear regression analysis, BVAS was positively correlated with ESR and CRP and negatively with lymphocyte count, serum albumin, and PNI (r = -0.307). In multivariable linear regression analysis, among ESR, CRP, and PNI, PNI was associated with BVAS (β = -0.299). PNI also significantly correlated with the included laboratory data. In Cox proportional hazard analysis, myeloperoxidase-antineutrophil cytoplasmic antibody positivity (odds ratio [OR] 2.875, P = 0.003) and PNI ≤36.75 (OR 2.066, P = 0.042) revealed to be independent predictors of disease relapse during the follow-up period.

CONCLUSIONS

Prognostic nutritional index at diagnosis might be useful for assessing disease severity and predicting the prognosis of AAV patients.

Clinical significance of positive anti-neutrophil cytoplasmic antibodies without evidence of anti-neutrophil cytoplasmic antibodies-associated vasculitis

AIM

Anti-neutrophil cytoplasmic antibodies (ANCA) have a role in the diagnostic workup of ANCA-associated vasculitis. However, the clinical significance of positive ANCA in the absence of vasculitis is yet to be determined. Therefore, we sought to investigate the clinical spectrum and rate of patients with a positive ANCA without evidence of vasculitis.

METHODS

Retrospective analysis of patients positive for cytoplasmic ANCA (C-ANCA) and proteinase 3 (PR3) or P-ANCA and myeloperoxidase (MPO) between 2007 and 2016 in the Chaim Sheba Medical Center, Israel. The proportion of patients who had no evidence of vasculitis among all patients with a positive C-ANCA/PR3 or P-ANCA/MPO was calculated according to tertiles of enzyme-linked immunosorbent assay (ELISA) antibody levels.

RESULTS

Among 113 patients who tested positive for C-ANCA/PR3 or P-ANCA/MPO, 68 (60.1%) had no evidence of vasculitis. ELISA antibody titers were significantly higher among patients with vasculitis than those without (6.2 vs 3.2, for C-ANCA/PR3 and 5.4 vs 2.6 for P-ANCA/MPO, P < 0.05). The proportion of patients without vasculitis among all patients with a positive C-ANCA/PR3 and among all patients with a positive P-ANCA/MPO declined in parallel to the increases in ELISA antibody level tertiles (96%, 57% and 22% in the 1st, 2nd and highest tertiles, respectively, for patients with C-ANCA/PR3 patients and 100%, 66% and 20% in the 1st, 2nd and highest tertiles, respectively, for patients with P-ANCA/MPO).

CONCLUSION

A significant proportion of patients with a positive C-ANCA/PR3 or P-ANCA/MPO do not have evidence of vasculitis, particularly those with low-medium ELISA antibody titers. Using a higher threshold of ANCA titers may be required to improve specificity.

Central Nervous System Involvement in ANCA-Associated Vasculitis: What Neurologists Need to Know

Objective: To provide a comprehensive review of the central nervous system (CNS) involvement in anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV), including the pathogenesis, clinical manifestations, ancillary investigations, differential diagnosis, and treatment. Particular emphasis is placed on the clinical spectrum and diagnostic testing of AAV.

Recent Findings: AAV is a pauci-immune small-vessel vasculitis characterized by neutrophil-mediated vasculitis and granulomatousis. Hypertrophic pachymeninges is the most frequent CNS presentation. Cerebrovascular events, hypophysitis, posterior reversible encephalopathy syndrome (PRES) or isolated mass lesions may occur as well. Spinal cord is rarely involved. In addition, ear, nose and throat (ENT), kidney and lung involvement often accompany or precede the CNS manifestations. Positive ANCA testing is highly suggestive of the diagnosis, with each ANCA serotype representing different groups of AAV patients. Pathological evidence is the gold standard but not necessary. Once diagnosed, prompt initiation of induction therapy, including steroid and other immunosuppressants, can greatly mitigate the disease progression.

Conclusions and Relevance: Early recognition of AAV as the underlying cause for various CNS disorders is important for neurologists. Ancillary investigations especially the ANCA testing can provide useful information for diagnosis. Future studies are needed to better delineate the clinical spectrum of CNS involvement in AAV and the utility of ANCA serotype to classify those patients.

Evidence Review: We searched Pubmed for relevant case reports, case series, original research and reviews in English published between Sep 1st, 2001 and Sep 1st, 2018. The following search terms were used alone or in various combinations: “ANCA,” “proteinase 3/PR3-ANCA,” “myeloperoxidase/MPO-ANCA,” “ANCA-associated vasculitis,” “Wegener's granulomatosis,” “microscopic polyangiitis,” “Central nervous system,” “brain” and “spinal cord”. All articles identified were full-text papers.