Diagnostic value of standardized assays for anti-neutrophil cytoplasmic antibodies in idiopathic systemic vasculitis. EC/BCR Project for ANCA Assay Standardization

Possibly propylthiouracil-induced antineutrophilic cytoplasmic antibody-associated vasculitis manifested as blood coagulation disorders: A case report

BACKGROUND

Propylthiouracil is the most common drug used to treat hyperthyroidism. However, this drug could cause a severe disease, antineutrophilic cytoplasmic antibody-associated vasculitis (AAV), which was usually misdiagnosed.

METHODS

We reported a 60-year-old woman of propylthiouracil-induced AAV manifested as blood coagulation disorders. The patient was admitted because of hyperthyroidism and leukopenia. At the time of hospitalization, she suffered from dry cough, erythema and knee joints ache, and gradually became febrile. And then BP decreased and PLT was reduced with coagulation disorders. ANCA: c-ANCA positive (1:100), p-ANCA positive (1:320), MPO-IgG positive, PR3-IgG positive, GBM-IgG negative. Erythrocyte sedimentation rate and C-reactive protein increased markedly. Chest high-resolution computed tomography (HRCT) showed that scattered spots, patch and ground-glass opacity.

RESULTS

Finally, we made a terminal diagnosis of PTU-induced AAV possibly. After drug withdrawal and use of steroid, the patient recovered well and then accepted RAI therapy. As the patient was given imipenem-cilastatin before the reduction of PLT and coagulation disorders, we considered that the hematologic disorders might be caused by antibiotics or a clinical presentation of the vasculitis itself.

CONCLUSION

Drug-induced vasculitis is relatively good prognosis, but early diagnosis and timely withdrawal of associated drugs are the key to the treatment.

Small vessel vasculitis of the lung

Interstitial Lung Disease Program, National Jewish Medical and Research Center, Division of Pulmonary Sciences and Critical Care Medicine, University of Colorado Health Sciences Center, Denver, Colorado, USA The diagnosis and management of SVV remains one of the most challenging clinical scenarios encountered by a clinician. Careful attention to detail and a thorough knowledge of the specific disorders, their therapies, and complications thereof is required to optimally care for these patients. The recent completion of a number of randomized, controlled, multicenter clinical trials has greatly improved our knowledge base and ability to care for vasculitis patient. The next decade holds even more promise.

Detection of antineutrophil cytoplasmic antibodies (ANCAs): a multicentre European Vasculitis Study Group (EUVAS) evaluation of the value of indirect immunofluorescence (IIF) versus antigen-specific immunoassays

OBJECTIVE

This multicentre study was performed to evaluate the diagnostic accuracy of a wide spectrum of novel technologies nowadays available for detection of myeloperoxidase (MPO) and proteinase 3 (PR3)-antineutrophil cytoplasmic antibodies (ANCAs).

METHODS

Sera (obtained at the time of diagnosis) from 251 patients with ANCA-associated vasculitis (AAV), including granulomatosis with polyangiitis and microscopic polyangiitis, and from 924 disease controls were tested for the presence of cytoplasmic pattern/perinuclear pattern and atypical ANCA (A-ANCA) by indirect immunofluorescence (IIF) (at two sites) and for the presence of PR3-ANCA and MPO-ANCA by eight different immunoassays.

RESULTS

The area under the curve (AUC) of the receiver operating characteristic curve to discriminate AAV from controls was 0.923 (95% CI 0.902 to 0.944) and 0.843 (95% CI 0.814 to 0.871) for the two IIF methods. For the antigen-specific immunoassays, the AUC varied between 0.936 (95% CI 0.912 to 0.960) and 0.959 (95% CI 0.941 to 0.976), except for one immunoassay for which the AUC was 0.919 (95% CI 0.892 to 0.945).

CONCLUSIONS

Our comparison of various ANCA detection methods showed (i) large variability between the two IIF methods tested and (ii) a high diagnostic performance of PR3-ANCA and MPO-ANCA by immunoassay to discriminate AAV from disease controls. Consequently, dual IIF/antigen-specific immunoassay testing of each sample is not necessary for maximal diagnostic accuracy. These results indicate that the current international consensus on ANCA testing for AAV needs revision.

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.

Diseases and Syndromes That Affect the Lungs and the Kidneys: A Radiologic Review

A number of different conditions simultaneously affect both the lungs and the kidneys. These include autoimmune disorders and genetic tumor syndromes. Although manifestations within either organ system alone may not be specific, by observing the pattern of involvement and clinical history, radiologists may be able to suggest the correct 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.

Diagnostic ANCA algorithms in daily clinical practice: evidence, experience, and effectiveness

Detection of antineutrophil cytoplasmic antibodies (ANCA) for ANCA-associated vasculitides (AAV) is based on indirect immunofluorescence (IIF) on ethanol-fixed neutrophils and reactivity toward myeloperoxidase (MPO) and proteinase 3 (PR3). According to the international consensus for ANCA testing, presence of ANCA should at least be screened for by IIF and, if positive, followed by antigen-specific immunoassays. Optimally, all samples are analyzed by both IIF and quantitative antigen-specific immunoassays. Since the establishment of this consensus many new technologies have become available and this has challenged the positioning of IIF in the testing algorithm for AAV. In the current paper, we summarize the novelties in ANCA diagnostics and discuss the possible implications of these developments for the different ANCA algorithms that are currently applied in routine diagnostic laboratories. Possible consequences of replacing ANCA assays by novel methods are illustrated by our data obtained in daily clinical practice. Eventually, it is questioned if there is a need to change the consensus, and if so, whether IIF can be discarded completely, or be used as a confirmation assay instead of a screening assay. Both alternative options require that ANCA requests for AAV can be separated from ANCA requests for gastrointestinal autoimmune diseases.

Predictors of renal histopathology in antineutrophil cytoplasmic antibody associated glomerulonephritis

OBJECTIVES

Prompt, aggressive therapy is vital for anti-neutrophil cytoplasmic antibody (ANCA)-associated glomerulonephritis. In this regard, we aimed to identify predictors of distinct renal histopathological classes at the time of clinical diagnosis.

PATIENTS & METHODS

An inception cohort of patients with biopsy proven ANCA-associated glomerulonephritis was studied retrospectively. Demographics, clinical, laboratory, serological and radiological parameters were analyzed. Patients were classified on the basis of renal histopathology. A risk score was developed for each histopathological class using univariate and stepwise logistic regression analyses.

RESULTS

Variables independently associated with focal class included disease duration up to diagnosis <8 weeks, absence of erythrocyte casts by urine microscopy and eGFR >49 ml/min/1.73 m(2); with crescentic class >40 erythrocytes/hpf, identification of erythrocyte casts in urine, upper respiratory tract involvement and eGFR <49 ml/min/1.73 m(2); with mixed class age >54 years, male gender, and absence of upper respiratory tract involvement. In the presence of these risk factors a predictive risk score for each histopathological classes was calculated: odds ratio, 95% confidence intervals (CI), for focal class (≥2 risk factors, 20.8 (95% CI: 5.1-84.2), p < 0.0001, and 441.0 (95% CI: 16.8-11,590), p = 0.0003 for crescentic class (≥3 risk factors) while the small number of patients in the mixed and sclerotic class precluded any estimates.

CONCLUSION

We propose a predictive algorithm of specific histolopathological classes of ANCA-associated glomerulonephritis, which might provide a crude estimation of the disease activity in the glomeruli at presentation. This tool might assist the clinician in making decisions regarding the level of intensity of inductive immunosuppressive therapy at clinical diagnosis.

Clinical Trials in Vasculitis

The systemic vasculitides include a heterogenous group of diseases characterised by inflammation of blood vessels. Evidence for treatment in this group of patients is limited due to rarity of the diseases, incomplete understanding of the pathogenesis and lack of appropriate biomarkers. In the last 20 years, international collaboration and networking led to clinical trials in a select subgroup of patients with systemic vasculitis. Anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) is the most studied subgroup. This article discusses the treatment options of AAV in light of evidence from clinical trials. Treatment of AAV, which includes an induction and a maintenance phase, is dependent on the severity of the disease. Oral or intravenous cyclophosphamide and high-dose glucocorticoids are considered to be standard of care for induction of remission in AAV patients with generalised disease. Latest evidence supports rituximab as an alternative to cyclophosphamide especially in relapsing patients and is increasingly being used in patients who cannot have cyclophosphamide. Plasma exchange and intravenous immunoglobulins (IVIGs) are used as adjunctive therapies for induction. Azathioprine or methotrexate (in non-renal patients) is considered to be the choice for remission maintenance, whilst mycophenolate mofetil is reserved for patients who cannot tolerate either of them. Rituximab is also being increasingly used for remission maintenance in relapsing patients. Even though an enormous progress has been made in the outlook of patients with AAV, a number of questions remain unanswered with regard to the optimal treatment strategy.

The Prevalence and Management of Anti-Neutrophil Cytoplasmic Antibody-Associated Vasculitis in China

BACKGROUND

Anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) comprises microscopic polyangiitis (MPA), granulomatosis with polyangiitis (GPA) and eosinophilic GPA (EGPA). Myeloperoxidase (MPO) and proteinase 3 (PR3) are the main antigens for ANCA. AAV is a common multisystem autoimmune disease and most of the studies on AAV have been conducted in Western countries. Nowadays in China many efforts are made to investigate this disease.

SUMMARY

This review highlights the progress in the prevalence, management and outcomes of AAV in Chinese patients. With respect to the prevalence of AAV, though there are no precise data, AAV is not rare in the Chinese population. In Chinese patients with AAV there is a striking preponderance of MPA, and MPO-ANCA is much more common than PR3-ANCA. Even in patients with GPA there is a predominance of MPO-ANCA over PR3-ANCA. Propylthiouracil-induced AAV and ANCA-negative pauci-immune glomerulonephritis are stated in this review as well. With respect to the management of AAV, glucocorticoids in combination with cyclophosphamide remain the mainstay of induction therapy. Besides, we describe predictors of different outcomes in Chinese patients, including mortality, relapse, treatment resistance and end-stage renal disease.

KEY MESSAGES

AAV is not rare in the Chinese population. The disease spectrum and subtypes of ANCA are different between patients with AAV in China and Western countries. The treatment strategy for AAV in China is in consistency with that in Western countries. Predictors of different clinical outcomes are provided.

FACTS FROM EAST AND WEST

Treatment options for AAV are shared between the East and West, with corticosteroid combined with cyclophosphamide being the standard regimen for inductive therapy and switching to azathioprine after remission. The major cause of death in treated patients is infection related to immunosuppressive therapy within the first year after diagnosis, and this rate might be higher in China than in Western countries. Western studies demonstrated the efficacy and safety of rituximab for induction of remission in cases with relatively mild disease and maintenance therapy, but this agent is rarely used in China.

Infected Aortic Aneurysm Mimicking Anti-proteinase 3-Antineutrophil Cytoplasmic Antibody-associated Vasculitis

We herein report an unusual case of an infected descending aortic pseudoaneurysm with luminal pathognomonic oscillating vegetation with serological findings and clinical features mimicking anti-proteinase 3-antineutrophil cytoplasmic antibody-associated vasculitis. The positive blood cultures and imaging findings, including a pseudoaneurysm and vegetations in the aorta, suggested the presence of an infected aortic aneurysm. The patient was successfully treated with antibiotics and endovascular aortic repair. A precise diagnosis is crucial in order to avoid inappropriate therapy such as immunosuppressive treatment, which could result in life-threatening consequences in a patient with an infected aortic aneurysm.

Antineutrophil Cytoplasmic Antibodies Associated With Infective Endocarditis

To determine the prevalence of antineutrophil cytoplasmic antibodies (ANCA) in patients with infective endocarditis (IE) in internal medicine; and to compare clinical and biochemical features and outcome between patients exhibiting IE with and without ANCA.Fifty consecutive patients with IE underwent ANCA testing. The medical records of these patients were reviewed.Of the 50 patients with IE, 12 exhibited ANCA (24%). ANCA-positive patients with IE exhibited: longer duration between the onset of first symptoms and IE diagnosis (P = 0.02); and more frequently: weight loss (P = 0.017) and renal impairment (P = 0.08), lower levels of C-reactive protein (P = 0.0009) and serum albumin (P = 0.0032), involvement of both aortic and mitral valves (P = 0.009), and longer hospital stay (P = 0.016). Under multivariate analysis, significant factors for ANCA-associated IE were: longer hospital stay (P = 0.004), lower level of serum albumin (P = 0.02), and multiple valve involvement (P = 0.04). Mortality rate was 25% in ANCA patients; death was because of IE complications in all these patients.Our study identifies a high prevalence of ANCA in unselected patients with IE in internal medicine (24%). Our findings further underscore that ANCA may be associated with a subacute form of IE leading to multiple valve involvement and more frequent renal impairment. Because death was due to IE complications in all patients, our data suggest that aggressive therapy may be required to improve such patients' outcome.

Cutaneous Ulcers as Initial Presentation of Localized Granulomatosis with Polyangiitis: A Case Report and Review of the Literature

Background. Granulomatosis with polyangiitis (GPA) is an ANCA associated small vessel vasculitis characterized by necrotizing granulomatous inflammation involving the upper and the lower respiratory tract and the kidneys. The disease has a broad clinical spectrum that ranges from limited/localized involvement of a single organ system to a generalized systemic vasculitis that affects several organs with evidence of end organ damage. Atypical forms of the disease have been recognized with or without respiratory tract involvement with a long protracted course before manifesting as generalized disease. Case Presentation. We describe a 57-year-old woman who presented with recurrent fever and cutaneous ulcers on her legs who was diagnosed to have granulomatosis with polyangiitis (GPA) after an extensive evaluation which excluded infectious, other vasculitides, connective tissue disease and malignant etiologies. Conclusion. In the absence of typical manifestations, granulomatosis with polyangiitis (GPA) is indeed a diagnostic challenge to the physician. Atypical manifestations like unexplained recurrent fever and cutaneous ulcers nevertheless call for keeping a low threshold for the diagnosis of GPA as the disease can initially present in localized form before heralding into a generalized disease.

Antineutrophil Cytoplasmic Antibody-Positive Small-Vessel Vasculitis Associated with Antithyroid Drug Therapy: How Significant Is the Clinical Problem?

BACKGROUND

The aim of this review was to delineate the characteristics of antineutrophil cytoplasmic antibody (ANCA)-associated small-vessel vasculitis associated with antithyroid drugs (ATD). A PubMed search was made for English language articles using the search terms antithyroid drugs AND ANCA OR ANCA-associated vasculitis.

SUMMARY

The literature includes approximately 260 case reports of ANCA-associated small-vessel vasculitis related to ATD, with 75% of these associated with thiouracil derivatives (propylthiouracil [PTU]) and 25% with methyl-mercapto-imidazole derivatives (MMI/TMZ). The prevalence of ANCA-positive cases caused by ATD varied between 4% and 64% with PTU (median 30%), and 0% and 16% with MMI/TMZ (median 6%). Young age and the duration of ATD therapy were the main factors contributing to the emergence of ANCA positivity. Before ATD therapy initiation, the prevalence of ANCA-positive patients was 0-13%. During ATD administration, 20% of patients were found to be positive for ANCA. Only 15% of ANCA-positive patients treated with ATD exhibited clinical evidence of vasculitis, corresponding to 3% of all patients who received ATD. Clinical manifestations of ANCA-associated vasculitis related to ATD were extremely heterogeneous. When vasculitis occurred, ATD withdrawal was usually followed by rapid clinical improvement and a favorable prognosis.

CONCLUSIONS

ANCA screening is not systematically recommended for individuals on ATD therapy, particularly given the decreasing use of PTU in favor of TMZ/MMI. Particular attention should be given to the pediatric population with Graves' disease who receive ATD, as well as patients treated with thiouracil derivatives and those on long-term ATD therapy.

CanVasc Recommendations for the Management of Antineutrophil Cytoplasm Antibody-associated Vasculitides

Objective.

The Canadian Vasculitis research network (CanVasc) is composed of physicians from different medical specialties and researchers with expertise in vasculitis. One of its aims is to develop recommendations for the diagnosis and management of antineutrophil cytoplasm antibody (ANCA)-associated vasculitides (AAV) in Canada.

Methods.

Diagnostic and therapeutic questions were developed based on the results of a national needs assessment survey. A systematic review of existing non-Canadian recommendations and guidelines for the diagnosis and management of AAV and studies of AAV published after the 2009 European League Against Rheumatism/European Vasculitis Society recommendations (publication date: January 2009) until November 2014 was performed in the Medline database, Cochrane library, and main vasculitis conference proceedings. Quality of supporting evidence for each therapeutic recommendation was graded. The full working group as well as additional reviewers, including patients, reviewed the developed therapeutic recommendations and nontherapeutic statements using a modified 2-step Delphi technique and through discussion to reach consensus.

Results.

Nineteen recommendations and 17 statements addressing general AAV diagnosis and management were developed, as well as appendices for practical use, for rheumatologists, nephrologists, respirologists, general internists, and all other healthcare professionals more occasionally involved in the management of patients with AAV in community and academic practice settings.

Conclusion.

These recommendations were developed based on a synthesis of existing international guidelines, other published supporting evidence, and expert consensus considering the Canadian healthcare context, with the intention of promoting best practices and improving healthcare delivery for patients with AAV.

Genetic variants in ANCA-associated vasculitis: a meta-analysis

BACKGROUND

Genetic factors may influence the pathogenic pathways leading to antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV). We performed a meta-analysis to determine the genetic variants most likely associated with AAV and investigated whether diagnostic and serological subtypes within AAV have distinct genetic backgrounds.

METHODS

Studies investigating the association between genetic variants and AAV in humans were searched in PubMed, EMBASE and Web of Science. All variants investigated in at least two studies were selected. Subsequently, all studies assessing these variants were included in this meta-analysis. Additionally, data on these variants from the largest genome-wide association studies in AAV were included to increase the validity of this meta-analysis.

RESULTS

The literature search yielded 5180 articles. 62 articles investigating 140 genetic variants were included, 33 of which were associated with AAV in a meta-analysis. These genetic variants were in or near the following genes: CD226, CTLA-4, FCGR2A, HLA-B, HLA-DP, HLA-DQ, HLA-DR, HSD17B8, IRF5, PTPN22, RING1/RXRB, RXRB, STAT4, SERPINA1 and TLR9. Moreover, we identified genetic distinctions between granulomatosis with polyangiitis and microscopic polyangiitis and between proteinase 3 ANCA vasculitis and myeloperoxidase ANCA vasculitis. In 76% of the genetic variants, subdivision based on ANCA serotype resulted in higher ORs than subdivision based on clinical diagnosis.

CONCLUSIONS

This meta-analysis identified 33 genetic variants associated with AAV, supporting a role for alpha-1-antitrypsin, the major histocompatibility complex system, and several distinct inflammatory processes in AAV pathogenesis. Our results indicate that subdivision of AAV based on ANCA serotype has a stronger genetic basis than subdivision based on clinical diagnosis.

Neutrophil-Related Gene Expression and Low-Density Granulocytes Associated With Disease Activity and Response to Treatment in Antineutrophil Cytoplasmic Antibody-Associated Vasculitis

OBJECTIVE

To discover biomarkers involved in the pathophysiology of antineutrophil cytoplasmic antibody-associated vasculitis (AAV) and to determine whether low-density granulocytes (LDGs) contribute to gene expression signatures in AAV.

METHODS

The source of clinical data and linked biologic specimens was a randomized controlled treatment trial in AAV. RNA sequencing of whole blood from patients with AAV was performed during active disease at the baseline visit and during remission 6 months later. Gene expression was compared between patients who met versus those who did not meet the primary trial outcome of clinical remission at 6 months (responders versus nonresponders). Measurement of neutrophil-related gene expression was confirmed in peripheral blood mononuclear cells (PBMCs) to validate the findings in whole blood. A negative-selection strategy isolated LDGs from PBMC fractions.

RESULTS

Differential expression between responders (n = 77) and nonresponders (n = 35) was detected in 2,346 transcripts at the baseline visit (P < 0.05). Unsupervised hierarchical clustering demonstrated a cluster of granulocyte-related genes, including myeloperoxidase (MPO) and proteinase 3 (PR3). A granulocyte multigene composite score was significantly higher in nonresponders than in responders (P < 0.01) and during active disease than during remission (P < 0.01). This signature strongly overlapped an LDG signature identified previously in lupus (false discovery rate by gene set enrichment analysis <0.01). Transcription of PR3 measured in PBMCs was associated with active disease and treatment response (P < 0.01). LDGs isolated from patients with AAV spontaneously formed neutrophil extracellular traps containing PR3 and MPO.

CONCLUSION

In AAV, increased expression of a granulocyte gene signature is associated with disease activity and decreased response to treatment. The source of this signature is likely LDGs, a potentially pathogenic cell type in AAV.

Twenty-five years of European Union collaboration in ANCA-associated vasculitis research

This special edition reviews the progress in understanding of systemic vasculitis associated with autoantibodies to neutrophil cytoplasmic antigens (ANCA). European research groups have contributed to this research including the original observations of the association between ANCA and vasculitis. Areas of interest include classification and epidemiology, genetics and pathogenesis, disease assessment, histology and long-term outcomes. Clinical trials conducted by the European Vasculitis Study group have helped to define the current standard of care for the treatment of patients with vasculitis and provided a platform for the investigation of newer therapies. The prognosis of patients with ANCA-associated vasculitis has improved over this period as a result of facilitated diagnosis and development of consensus, evidence-based, treatment recommendations. The ANCA story represents an example of the power of a biomarker in influencing a disease area, inspiring research and providing physicians with better tools to treat patients with these disorders.

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.

Proteinase 3-ANCA Vasculitis versus Myeloperoxidase-ANCA Vasculitis

In patients with GN or vasculitis, ANCAs are directed against proteinase 3 (PR3) or myeloperoxidase (MPO). The differences between PR3-ANCA-associated vasculitis (AAV) and MPO-AAV described in the past have been supplemented during the last decade. In this review, we discuss the differences between these two small-vessel vasculitides, focusing especially on possible etiologic and pathophysiologic differences. PR3-AAV is more common in northern parts of the world, whereas MPO-AAV is more common in southern regions of Europe, Asia, and the Pacific, with the exception of New Zealand and Australia. A genetic contribution has been extensively studied, and there is a high prevalence of the HLA-DPB1*04:01 allele in patients with PR3-AAV as opposed to patients with MPO-AAV and/or healthy controls. Histologically, MPO-AAV and PR3-AAV are similar but show qualitative differences when analyzed carefully. Clinically, both serotypes are difficult to distinguish, but quantitative differences are present. More organs are affected in PR3-AAV, whereas renal limited vasculitis occurs more often in patients with MPO-AAV. For future clinical trials, we advocate classifying patients by ANCA serotype as opposed to the traditional disease type classification.

Myeloperoxidase-antineutrophil Cytoplasmic Antibodies (MPO-ANCA) and Proteinase 3-ANCA without Immunofluorescent ANCA Found by Routine Clinical Testing

OBJECTIVE

Concurrent testing for serum antineutrophil cytoplasmic antibodies (ANCA) by indirect immunofluorescence (IF) and by antiproteinase 3 (PR3)/antimyeloperoxidase (MPO) antibody assays may identify patients with PR3-ANCA or MPO-ANCA despite a negative IF (IF-negative MPO/PR3-positive); however, the significance of this result is not clear. We sought to determine whether IF-negative, MPO/PR3-positive results identified any cases of clinically meaningful systemic vasculitis at our institution.

METHODS

We conducted a retrospective chart review of all IF-negative, MPO/PR3-positive patients identified at our institution over a 2-year period.

RESULTS

Of the 2345 samples tested over 2 years, 1998 were IF-negative. Among these IF-negative samples, 49 samples (2.5%) derived from 38 patients tested positive for MPO-ANCA or PR3-ANCA. Only 1 IF-negative, MPO/PR3-positive patient was subsequently diagnosed with ANCA-associated vasculitis (AAV). Eleven IF-negative, MPO/PR3-positive patients (29%) had been previously diagnosed and treated for AAV, all with positive IF and antibody tests prior to treatment. Four patients had evidence of cutaneous vasculitis not attributed to AAV, while several of the remaining IF-negative, MPO/PR3-positive patients had other immunologic disorders, including systemic lupus erythematosus (5 patients) and inflammatory bowel disease (3 patients).

CONCLUSION

In this real-life cohort assayed simultaneously by IF and multiplexed bead assays, the detection of MPO-ANCA or PR3-ANCA without a positive IF rarely led to a new diagnosis of systemic vasculitis, and was more likely to occur in the context of a non-vasculitic inflammatory condition. Our results suggest that concurrent IF and MPO/PR3 testing may be of limited use in preventing a missed diagnosis of new-onset AAV.

Clinical aspects of indirect immunofluorescence for autoimmune diseases

Because the most common term used in conversations considering autoimmunity is autoantibodies, it is well-expected that the indirect immunofluorescence assay, which detects antibodies directed against various antigens, is one of our most impressive techniques for investigating autoimmune diseases (AIDs). Roughly speaking, the current literature corroborates that this immunopathologic investigation means that autoantibodies detection makes a considerable contribution to both diagnostic and prognostic aspects of AIDs in the clinical setting. However, it varies between different AIDs, autoantibodies, ethnicities or detection methodologies. Directly focusing on the indirect immunofluorescence assay, we present evidence to support this multidimensional variation regarding the subject via reviewing briefly the best-investigated autoantibodies in the well-documented AIDs, including vasculitis, inflammatory bowel disease, scleroderma, autoimmune hepatitis, primary biliary cirrhosis, systemic lupus erythematosus and Sjögren's syndrome.

Recent advances in the understanding of immune-mediated nephrotic syndrome: diagnostic and prognostic implications

Glomerular diseases with severe defects in glomerular permeability give rise to heavy proteinuria and can present as nephrotic syndrome. There are many different causes of the nephrotic syndrome and a renal biopsy is nearly always needed to elucidate the underlying disease. During the last decade, substantial advances have occurred in the understanding of the pathophysiological mechanisms involved in immune-mediated glomerular diseases. Here, we review the diagnostic and prognostic implications of recent progress on the understanding of membranous nephropathy, minimal change disease, focal segmental glomerulosclerosis, amyloidosis, IgA nephropathy and membranoproliferative glomerulonephritis.

Alveolar Hemorrhage

Diffuse alveolar hemorrhage (DAH) is a clinical syndrome characterized by generalized intra-alveolar bleeding originating from the pulmonary microcirculation. The finding of DAH carries an extended differential diagnosis and may be associated with a number of histopathologic patterns. The prompt recognition and diagnosis of DAH is of critical importance to the practicing clinician as accurate diagnosis and prompt initiation of therapy may dramatically improve patient outcomes. This chapter reviews the diagnosis and management of diffuse alveolar hemorrhage.

Churg-Strauss syndrome

Churg-Strauss syndrome (CSS), alternatively known as eosinophilic granulomatosis with polyangiitis (EGPA), was first described in 1951 by Churg and Strauss as a rare disease characterized by disseminated necrotizing vasculitis with extravascular granulomas occurring exclusively among patients with asthma and tissue eosinophilia. EGPA is classified as a small-vessel vasculitis associated with antineutrophil cytoplasmic antibodies (ANCAs) and the hypereosinophilic syndromes (HESs) in which vessel inflammation and eosinophilic proliferation are thought to contribute to organ damage. Although still considered an idiopathic condition, EGPA is classically considered a Th2-mediated disease. Emerging clinical observations provide compelling evidence that ANCAs are primarily and directly involved in the pathogenesis of AASVs, although recent evidence implicates B cells and the humoral response as further contributors to EGPA pathogenesis. EGPA has traditionally been described as evolving through a prodromic phase characterized by asthma and rhino-sinusitis, an eosinophilic phase marked by peripheral eosinophilia and organ involvement, and a vasculitic phase with clinical manifestations due to small-vessel vasculitis. The American College of Rheumatology defined the classification criteria to distinguish the different types of vasculitides and identified six criteria for EGPA. When four or more of these criteria are met, vasculitis can be classified as EGPA. The French Vasculitis Study Group has identified five prognostic factors that make up the so-called five-factor score (FFS). Patients without poor prognosis factors (FFS=0) have better survival rates than patients with poor prognosis factors (FFS≥1). The treatment of patients with CSS must be tailored to individual patients according to the presence of poor prognostic factors. A combination of high-dose corticosteroids and cyclophosphamide is still the gold standard for the treatment of severe cases, but the use of biological agents such as rituximab or mepolizumab seems to be a promising therapeutic alternative.

Necrotizing RPGN with linear anti IgG deposits in a patient with history of granulomatosis with polyangiitis: a case report

Introduction

Diagnosing the etiology of a rapidly progressive glomerulonephritis is of vital importance to guide appropriate therapeutic management. This case highlights the complexity involved in establishing diagnosis when presentation is atypical. In certain cases diagnosis cannot be established based on clinical presentation or biopsy findings alone, and critical analysis of biopsy findings in context of clinical presentation is crucial to guide the clinical decision-making process.

Case presentation

A 47-year-old Hispanic male with history of granulomatosis with polyangiitis (GPA) in remission on azathioprine, presented with fatigue and lethargy. Physical examination was unremarkable. Laboratory data revealed elevated creatinine and otherwise normal electrolytes. Urinalysis showed numerous dysmorphic red blood cells with few red cell casts. His serologic results were all negative except anti-proteinase-3 antibody at very low titers. Kidney biopsy showed necrotizing crescentic glomerulonephritis with linear immunoglobulin G staining along the basement membrane.

Conclusion

This case presented conflicting serologic and histopathologic findings. The presence of anti-proteinase-3 antibody supported diagnosis of recurrence of GPA. However, linear staining of immunoglobulin G (IgG) on immunofluorescence (IF) staining of renal biopsy supported anti-glomerular basement membrane (GBM) disease. The treatment of anti-GBM disease and GPA both involve immunosuppression with prednisone and cyclophosphamide. However, patients with anti-GBM disease are also treated with plasmapheresis early in the disease presentation to prevent further damage. The patient with GPA, on the other hand, was shown to benefit from plasmapheresis only in the case of severe renal disease (serum creatinine level more than 5 mg/dL) or pulmonary hemorrhage. In this case, since the patient did not have detectable circulating anti-GBM antibody, the decision was made not to proceed with plasmapheresis. The patient was treated with a standard immunosuppressive regimen consisting of prednisone and cyclophosphamide with partial renal recovery at 2 months.

Simultaneous estimation of bidirectional particle flow and relative flux using MUSIC-OCT: phantom studies

In an optical coherence tomography (OCT) scan from a living tissue, red blood cells (RBCs) are the major source of backscattering signal from moving particles within microcirculatory system. Measuring the concentration and velocity of RBC particles allows assessment of RBC flux and flow, respectively, to assess tissue perfusion and oxygen/nutrition exchange rates within micro-structures. In this paper, we propose utilizing spectral estimation techniques to simultaneously quantify bi-directional particle flow and relative flux by spectral estimation of the received OCT signal from moving particles within capillary tubes embedded in tissue mimicking phantoms. The proposed method can be directly utilized for in vivo quantification of capillaries and microvessels. Compared to the existing methods in the literature that can either quantify flow direction or power, our proposed method allows simultaneous flow (velocity) direction and relative flux (power) estimation.

Genetic Susceptibility to ANCA-Associated Vasculitis: State of the Art

ANCA-associated vasculitis (AAV) is a group of disorders that is caused by inflammation affecting small blood vessels. Both arteries and veins are affected. AAV includes microscopic polyangiitis (MPA), granulomatosis with polyangiitis (GPA) renamed from Wegener’s granulomatosis, and eosinophilic granulomatosis with polyangiitis (EGPA), renamed from Churg–Strauss syndrome. AAV is primarily due to leukocyte migration and resultant damage. Despite decades of research, the mechanisms behind AAV disease etiology are still not fully understood, although it is clear that genetic and environmental factors are involved. To improve the understanding of the disease, the genetic component has been extensively studied by candidate association studies and two genome-wide association studies. The majority of the identified genetic AAV risk factors are common variants. These have uncovered information that still needs further investigation to clarify its importance. In this review, we summarize and discuss the results of the genetic studies in AAV. We also present the novel approaches to identifying the causal variants in complex susceptibility loci and disease mechanisms. Finally, we discuss the limitations of current methods and the challenges that we still have to face in order to incorporate genomic and epigenomic data into clinical practice.

Vasculitis: an update

The systemic vasculitides are uncommon but serious diseases. Early recognition can be difficult because they mimic many conditions. Aggressive immunosuppression is toxic but effective; a targeted approach with biological agents may improve the outcome.

The immunopathology of ANCA-associated vasculitis

The small-vessel vasculitides are a group of disorders characterised by variable patterns of small blood vessel inflammation producing a markedly heterogeneous clinical phenotype. While any vessel in any organ may be involved, distinct but often overlapping sets of clinical features have allowed the description of three subtypes associated with the presence of circulating anti-neutrophil cytoplasmic antibodies (ANCA), namely granulomatosis with polyangiitis (GPA, formerly known as Wegener’s Granulomatosis), microscopic polyangiitis (MPA) and eosinophilic granulomatosis with polyangiitis (eGPA, formerly known as Churg-Strauss syndrome). Together, these conditions are called the ANCA-associated vasculitidies (AAV). Both formal nomenclature and classification criteria for the syndromes have changed repeatedly since their description over 100 years ago and may conceivably do so again following recent reports showing distinct genetic associations of patients with detectable ANCA of distinct specificities. ANCA are not only useful in classifying the syndromes but substantial evidence implicates them in driving disease pathogenesis although the mechanism by which they develop and tolerance is broken remains controversial. Advances in our understanding of the pathogenesis of the syndromes have been accompanied by some progress in treatment, although much remains to be done to improve the chronic morbidity associated with the immunosuppression required for disease control.

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.

Current and emerging techniques for ANCA detection in vasculitis

Detection of antineutrophil cytoplasmic antibodies (ANCAs) is a well-established diagnostic test used to evaluate suspected necrotizing vasculitis of small blood vessels. Conditions associated with these antibodies, collectively referred to as ANCA-associated vasculitides, include granulomatosis with polyangiitis (formerly known as Wegener granulomatosis), microscopic polyangiitis, and eosinophilic granulomatosis with polyangiitis (formerly known as Churg-Strauss syndrome). The diagnostic utility of ANCA testing depends on the type of assay performed and on the clinical setting. Most laboratories worldwide use standard indirect immunofluorescence tests (IFT) to screen for ANCA and then confirm positive IFT results with antigen-specific tests for proteinase 3 (PR3) and myeloperoxidase (MPO). Developments such as automated image analysis of immunofluorescence patterns, so-called third-generation PR3-ANCA and MPO-ANCA ELISA, and multiplex technology have improved the detection of ANCAs. However, challenges in routine clinical practice remain, including methodological aspects of IFT performance, the diverse antigen-specific assays available, the diagnostic value of testing in clinical settings and the prognostic value of serial ANCA monitoring in the prediction of disease relapse. This Review summarizes the available data on ANCA testing, discusses the usefulness of the various ANCA assays and advises on the clinical indications for the use of ANCA testing.

Headaches and vasculitis

Vasculitis is a spectrum of clinicopathologic disorders defined by inflammation of arteries of veins of varying caliber with variable tissue injury. Headache may be an important clue to vasculitic involvement of central nervous system (CNS) vessels. CNS vasculitis may be primary, in which only intracranial vessels are involved in the inflammatory process, or secondary to another known disorder with overlapping systemic involvement. A suspicion of vasculitis based on the history, clinical examination, or laboratory studies warrants prompt evaluation and treatment to forestall progression and avert cerebral ischemia or infarction.

Good response to surgical treatment and mycophenolate in woman with inflammatory pseudotunor secondary to ANCA positive vasculitis

We present the case of a young woman with ANCA positive vasculitis and infammatory pseudotumor as a granulomatous manifestation, who had a good response to surgical removal and mycophenolate mofetil.

Treatment of ANCA-associated vasculitis: new therapies and a look at old entities

Anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) is a small-vessel vasculitis that primarily comprises 2 clinical syndromes: granulomatosis with polyangiitis and microscopic polyangiitis. Cyclophosphamide and glucocorticoids have traditionally been used for induction of remission. However, more recent studies have shown that rituximab is as effective as cyclophosphamide for induction therapy in patients with newly diagnosed severe AAV and superior for patients with relapsing AAV. There is also accumulating evidence indicating a potential role of rituximab for maintenance therapy in AAV. In this article, we will review the evidence supporting the various treatment choices for patients with AAV.

Performance of two strategies for urgent ANCA and anti-GBM analysis in vasculitis

BACKGROUND

In anti-neutrophil cytoplasmic antibodies (ANCA) associated small vessel vasculitis (AAV), rapid testing for ANCA and anti-glomerular basement membrane (GBM) antibodies may be beneficial for therapeutic purpose.

OBJECTIVE

We analysed the diagnostic performance of two rapid ANCA and anti-GBM test methods in 260 patients with suspected AAV.

METHODS

Between January 2004 and November 2010, we analysed 260 samples by qualitative Dotblot (Biomedical Diagnostics); retrospective analysis followed with directly coated highly sensitive automated Phadia ELiA and ELiA anti-GBM. Results were related to the final clinical diagnosis and compared with routine capture ELISA.

RESULTS

Seventy-four patients had a final diagnosis of AAV (n=62) or anti-GBM disease (n=12). Both Dotblot and ELiA detected all 12 cases of anti-GBM disease; 2 false positive results were found. Dotblot detected ANCA in 56 of 62 AAV patients (sensitivity 90%, NPV 97%), and showed 5 false positives (specificity 97%, PPV 90%). The Phadia ELiA anti-PR3(s) or anti-MPO(s) was positive in 57 of 62 AAV patients (sensitivity 92%, NPV 97%), and had 5 false positives (specificity 97%, PPV 88%). Routine capture ELISA was equally accurate (sensitivity 94%, specificity 97%, PPV 88%, NPV 98%).

CONCLUSION

The Dotblot and Phadia ELiA on anti-GBM, anti-PR3(s) and anti-MPO(s) performed excellently; results were almost identical to routine ELISA. When suspicion of AAV or anti-GBM disease is high and diagnosis is urgently needed, both tests are very powerful for rapid serological diagnosis. Further studies have to confirm the test performances in samples routinely presented for ANCA testing and in follow-up of positive patients.

Anti-neutrophil cytoplasmic autoantibody pathogenicity revisited: pathogenic versus non-pathogenic anti-neutrophil cytoplasmic autoantibody

Anti-neutrophil cytoplasmic autoantibody (ANCA)-associated vasculitis (AAV) is strongly associated with autoantibodies against myeloperoxidase (MPO) and proteinase 3 (PR3). No clear consensus has been reached on the pathogenicity of these autoantibodies. Animal models for MPO-ANCA, in vitro data suggesting pathogenicity of ANCA, and one case of a neonate showing symptoms of vasculitis after transplacental transfer of MPO, argue in favour of a pathogenic role for ANCA. On the other hand, the presence of natural MPO and PR3 autoantibodies in healthy individuals, lack of a strong correlation between ANCA titres and disease activity, and the occurrence of ANCA-negative AAV patients argue against pathogenicity of ANCA. Recent papers have drawn attention to the possibility of epitope specificity defining ANCA pathogenicity. Certain MPO epitopes were found to be specific for active disease, and others remained present during remission or were also present in healthy individuals. One linear epitope, aa447-459, was not only exclusive for active disease, but also detected in the total Ig fraction of ANCA-negative patients, reactivity being masked in serum by ceruloplasmin. So, not all ANCA seems to be equal, some could be pathogenic while others are not. For development of an autoimmune response, a specific ANCA repertoire is required, which may occur through intra-molecular epitope spreading in patients.