Antineutrophil Cytoplasmic Autoantibodies Research Articles

Antineutrophil Cytoplasmic Autoantibody Levels in Patients in the Avacopan Phase 3 Trial

Antineutrophil Cytoplasmic Autoantibody Levels in Patients in the Avacopan Phase 3 Trial

Cocaine- and Levamisole-Induced Vasculitis: Defining the Spectrum of Autoimmune Manifestations.

Drug-induced or associated vasculitis is a prevalent form of vasculitis that resembles primary idiopathic antineutrophil cytoplasmic autoantibody (ANCA) vasculitis (AAV). Cocaine is a diffuse psychostimulant drug and levamisole is a synthetic compound used to cut cocaine. Their abuse may result in a spectrum of autoimmune manifestations which could be categorized into three overlapping clinical pictures: cocaine-induced midline destructive lesion (CIMDL), levamisole-adulterated cocaine (LAC) vasculopathy/vasculitis, and cocaine-induced vasculitis (CIV). The mechanisms by which cocaine use leads to disorders resembling AAV are not well understood. Cocaine can cause autoimmune manifestations ranging from localized nasal lesions to systemic diseases, with neutrophils playing a key role through NETosis and ANCA development, which exacerbates immune responses and tissue damage. Diagnosing and treating these conditions becomes challenging when cocaine and levamisole abuse is not suspected, due to the differences and overlaps in clinical, diagnostic, therapeutic, and prognostic aspects compared to primary idiopathic vasculitides.

Myeloperoxidase-ANCA IgG induces different forms of small vessel vasculitis based on type of synergistic immune stimuli

Anti-neutrophil cytoplasmic autoantibody (ANCA) vasculitis has diverse patterns of injury including microscopic polyangiitis (MPA), granulomatosis with polyangiitis (GPA), and eosinophilic granulomatosis with polyangiitis (EGPA). Necrotizing and crescentic glomerulonephritis (NCGN) occurs in all syndromes and as renal limited vasculitis (RLV). Single dose intravenous ANCA IgG-specific for mouse myeloperoxidase (MPO) causes RLV in mice. Although multiple mouse models have elucidated ANCA-IgG induced necrotizing and crescentic glomerulonephritis (NCGN), pathogenesis of ANCA-induced granulomatosis and vasculitis outside the kidney has not been clarified. To investigate this, we used intravenous MPO-ANCA IgG in the same strain of mice to induce different patterns of lung disease mirroring patients with granulomatosis with polyangiitis (GPA), microscopic polyangiitis (MPA), and eosinophilic granulomatosis with polyangiitis (EGPA). Repeated intravenous MPO-ANCA IgG induced GPA with NCGN, lung capillaritis, arteritis and granulomatosis. Lung leukocyte phenotypes were evaluated by immunohistochemical image analysis and by flow cytometry. ANCA lung capillaritis and microabscesses began within one day and evolved into granulomas in under seven days. Influenza plus single dose MPO-ANCA IgG induced MPA with NCGN, lung capillaritis and arteritis, but no granulomatosis. Allergic airway disease caused by house dust mites or ovalbumin plus single dose intravenous MPO-ANCA IgG induced EGPA with eosinophilic bronchiolitis, NCGN, capillaritis, arteritis, and granulomatosis. Thus, our study shows that the occurrence and pattern of lung lesions are determined by the same ANCA IgG accompanied by different synergistic immune factors.

Genetic and Non-Genetic Contributions to Eosinophilic Granulomatosis with Polyangiitis: Current Knowledge and Future Perspectives.

In this work, we present a comprehensive overview of the genetic and non-genetic complexity of eosinophilic granulomatosis with polyangiitis (EGPA). EGPA is a rare complex systemic disease that occurs in people presenting with severe asthma and high eosinophilia. After briefly introducing EGPA and its relationship with the anti-neutrophil cytoplasmic autoantibodies (ANCA)-associated vasculitis (AAVs), we delve into the complexity of this disease. At first, the two main biological actors, ANCA and eosinophils, are presented. Biological and clinical phenotypes related to ANCA positivity or negativity are explained, as well as the role of eosinophils and their pathological subtypes, pointing out their intricate relations with EGPA. Then, the genetics of EGPA are described, providing an overview of the research effort to unravel them. Candidate gene studies have investigated biologically relevant candidate genes; the more recent genome-wide association studies and meta-analyses, able to analyze the whole genome, have confirmed previous associations and discovered novel risk loci; in the end, family-based studies have dissected the contribution of rare variants and the heritability of EGPA. Then, we briefly present the environmental contribution to EGPA, reporting seasonal events and pollutants as triggering factors. In the end, the latest omic research is discussed and the most recent epigenomic, transcriptomic and microbiome studies are presented, highlighting the current challenges, open questions and suggesting approaches to unraveling this complex disease.

Update on antineutrophil cytoplasmic autoantibody vasculitis in children.

Antineutrophil cytoplasmic autoantibody (ANCA)-associated vasculitis (AAV) is often organ- or life-threatening in children and impacts them during important periods of psychosocial and physical development. This review covers recent advances in the pathophysiology, diagnosis, management, and outcomes of AAV in children and highlights the ongoing need for funding and increased research collaboration. Recent work has improved our understanding of AAV disease pathogenesis, potentially identifying new biomarkers and therapeutic targets. Collaborative clinical studies have also highlighted the variable manifestations in children and identified potential factors associated with poorer outcomes. Consensus-based treatment guidelines are also appearing, but clinical trials are still essential to better understanding treatment efficacy and safety in children affected by AAV. New, validated outcome measures, including those that are patient-reported, will facilitate these much-needed clinical trials in pediatric AAV. There is a continued need for more rigorous study in pediatric AAV, however, there is certainly excitement with the increase in recent research relevant to the pediatric population.

Avacopan in Anti-Neutrophil Cytoplasmic Autoantibodies–Associated Vasculitis in a Real-World Setting

Avacopan in Anti-Neutrophil Cytoplasmic Autoantibodies–Associated Vasculitis in a Real-World Setting

ANCA-Positive Small-Vessel Vasculitis Following SARS-CoV-2 Vaccination-A Systematic Review.

As vaccinations against the SARS-CoV-2 virus have become a crucial tool in controlling the spread of the disease, reports of rare health complications have emerged, including new-onset antineutrophil cytoplasmic autoantibodies (ANCA)-associated vasculitis (AAV). We systematically reviewed new-onset AAV following COVID-19 vaccination case reports and case series published in three databases before January 2024 following PRISMA guidelines to understand the characteristics of possible causal relationships or coincidences. In total, 404 articles were screened respectively by title, abstracts, and full-texts. Thirty-four papers fulfilled the inclusion criteria and have been analyzed, covering 44 patients with new-onset AAV after COVID-19 vaccination with no prior history of COVID-19 infection. Data regarding patients' metrics, comorbidities, vaccination characteristics, symptoms, diagnostics, treatment, and outcomes were investigated and summarized. The cohort consisted predominantly of females. AAV diagnosis was confirmed via biopsy, with renal dysfunction as a prevailing manifestation. In most cases, the first symptoms of AAV developed after the second dose; moreover, Pfizer-BioNTech was the most frequently administered vaccine among the analyzed cohort. Primary treatment involved glucocorticoid therapy, with a mostly favourable response. This systematic review aims to raise awareness among clinicians in the field regarding this rare but possible complication, to promote the prompt recognition and diagnosis of de novo ANCA-positive small-vessel vasculitis in timely association with SARS-CoV-2 vaccination.

Antineutrophil cytoplasmic antibody-associated vasculitis.

This review focuses on latest developments in managing antineutrophil cytoplasmic autoantibody (ANCA)-associated vasculitis (AAV), a systemic autoimmune condition characterized by inflammation and necrosis of small blood vessels due to circulating autoantibodies that target neutrophilic granules. Our understanding of AAV pathogenesis has evolved in the past decades highlighting the central pathogenic roles of autoantibodies and complement activation. In parallel, the appreciation for glucocorticoid toxicity has led the research on crucial steroid-sparing therapeutic alternatives. Complement inhibitors (like avacopan) that have emerged are associated with better preservation of kidney function in AAV patients with severe kidney impairment. The role of plasma-exchange (PLEX) was revisited in updated guidelines that recommended its potential use in the context of diffuse alveolar hemorrhage associated hypoxia and severe kidney involvement, particularly with a serum creatinine level above 3.4 mg/dl. The ANCA Kidney Risk Score risk prediction and Glucocorticoid Toxicity Index score aid in identifying high-risk patients and individualizing management plans. Kidney involvement in AAV requires prompt diagnosis and initiation of immunosuppression to prevent irreversible nephron loss. Newer therapeutic targets are on the horizon and offer hope for personalized treatment strategies.

#1517 Glomerular immune complex deposits on electron microscopy in ANCA associated vasculitis: clinical and outcomes features

Abstract Background and Aims Glomerulonephritis related to antineutrophil cytoplasmic autoantibodies (ANCA) is typically referred to as “pauci-immune”, however, it is not unusual for kidney biopsies to exhibit some immune complex deposition within glomeruli on electron microscopic study. Such deposits in ANCA-glomerulonephritis have not been widely studied, and their potential pathologic and clinical significance is not clear, although a possible synergistic effect between immune complexes and ANCA in producing more severe glomerulonephritis is suggested in the literature. Method An observational retrospective study was conducted using a dataset comprising all patients with ANCA associated vasculitis diagnosis from a Portuguese Center between march 2011 and march 2023. Demographic and clinical data were collected from medical records. Electron microscopy reports from kidney biopsies were examined for the presence of electron-dense deposits. Descriptive statistics were used to describe all reports. The objective of this study was to explore associations between the presence or absence of such deposits and clinical data, including serum creatinine, urine protein-creatinine ratio levels (PCR) at the time of biopsy as well as overall survival and renal outcomes at follow-up. Non-parametric Mann-Whitney U test and the Chi-squared test were used for continuous and categorical variables respectively. Kaplan-Meier curves were used for assessing time to event data. All analyses were two-tailed and a p value ≤ 0.05 was considered significant. Results From a total of 39 patients with ANCA associated vasculitis diagnosis, 33 underwent at least one kidney biopsy, and among them, 17 were analysed by electron microscopy. 8 (47%) of biopsies showed glomerular immune complex deposits by electron microscopy; Table 1 describes demographic data of both groups (immune complex deposits—D; no-immune complex deposits—ND). The median numbers of glomeruli examined by electron microscopy were identical between the two groups. In group D there was less patients with positive titers for ANCA (p = 0.034) and serum creatinine levels were higher at admission (mean 7.1 mg/dL IQR: 5.6-8.1 versus 4.2 IQR 3.2-7.1), despite the lack of definitive statistical significance (p = 0.123). Urine protein-to-creatinine ratio did not differ between groups. The need for renal replacement therapy at admission was greater for patients with dense deposits on kidney biopsy (p = 0.008). At the end of follow-up (median 48, IQR 24-48 months), death and progression to end stage kidney disease occurred in 25.0% and 37.5% of group D patients versus 11.1% and 22.2% of ND patients, respectively (Fig. 1). Conclusion Immune complex deposits were found on electron microscopy in nearly half of kidney biopsies. Our data suggest that these immune complex deposits are common and might play a role in clinical presentation, overall survival and renal prognosis. The small sample size of our cohort is a limitation, as well as the retrospective nature of the study. Larger cohorts and more comprehensive electron microscopic studies are warranted to better characterize this population.

Laboratory diagnostics for vasculitis beyond antineutrophil cytoplasmatic autoantibodies

The diagnosis of systemic vasculitis (SV) is amajor clinical challenge due to the very different forms of presentation and requires an interdisciplinary approach. Targeted laboratory diagnostics support making the diagnosis, differential diagnosis and classification and are also akey component in the detection of active organ manifestations and treatment complications. The basic laboratory tests include the erythrocyte sedimentation rate (ESR), C‑reactive protein (CRP), blood count, serum creatinine, urinalysis, specific autoantibodies, complement, immunoglobulins, cryoglobulins and hepatitisB and C serology. Antineutrophil cytoplasmic autoantibodies (ANCA), antiglomerular basement membrane antibodies (anti-GBM antibodies) and anti-C1q antibodies are valuable laboratory markers for the diagnosis of the various forms of small vessel vasculitis. There are no specific laboratory tests for the diagnosis of medium and large vessel vasculitis. Despite advances in our understanding of the pathogenesis of vasculitis, no biomarkers have yet been identified that can be reliably used to guide treatment or that are useful in distinguishing vasculitis from other inflammatory diseases such as infections or treatment complications.

The Diagnosis of Granulomatosis With Polyangiitis When Serology and Biopsies are Negative.

Granulomatosis with polyangiitis (GPA) is a potentially fatal condition which often manifests in the head and neck. Currently, diagnosis relies on antineutrophil cytoplasmic autoantibody (c-ANCA) serology and mucosal or renal biopsy. However, a significant proportion of patients with GPA limited to the head and neck are seronegative and biopsy negative. This study evaluates the role of clinical diagnosis of GPA in the absence of positive laboratory findings. Case series with chart review. Academic Tertiary Medical Center. This was a retrospective review of 143 patients treated in an outpatient otolaryngology clinic at a tertiary care hospital for known or suspected GPA from 1998 to 2021. Presenting symptoms, C-ANCA status at initial presentation, biopsy results, long-term serology results, and time to initiation of treatment were analyzed. Twenty-six of 143 (18.2%) patients were seronegative; only 3 of these patients (12%) had positive biopsies. Seventeen (73.9%) of these patients presented with nasal and sinus disease and 12 (52.2%) presented with airway involvement. Only 4 (17.4%) patients had renal involvement. Delay in treatment of patients with negative laboratory workup ranged from 0 months to 11 years. All patients who were seronegative and/or biopsy negative at presentation responded clinically to immunosuppressive therapy. GPA cases are often limited to the upper respiratory tract, making diagnosis difficult, particularly in seronegative patients. These results suggest that, when GPA is suspected, despite negative serology, the diagnosis of GPA should be made on clinical grounds, and empiric therapy encouraged to prevent delay in treatment.

Real-World Experience With Avacopan in Antineutrophil Cytoplasmic Autoantibody-Associated Vasculitis

Postmarketing data on outcomes of avacopan use in antineutrophil cytoplasmic autoantibody (ANCA)-associated vasculitis (AAV) are lacking. We performed a multicenter retrospective analysis of 92 patients with newly diagnosed or relapsing AAV who received therapy with avacopan. The coprimary outcome measures were clinical remission at 26 and 52 weeks. We use descriptive statistics and univariate logistic regression to assess outcomes and predictors of remission, respectively. Of the 92 patients, 23% (n = 21) had a baseline estimated glomerular filtration rate (eGFR)< 15 ml/min per 1.73 m2 and 10% on kidney replacement therapy at baseline. Among those with kidney involvement, mean (SD) enrollment eGFR was 33 (27) ml/min per 1.73 m2 with a mean (SD) change of+12 (25) and+20 (23) ml/min per 1.73 m2 at weeks 26 and 52, respectively. In addition to avacopan, 47% of patients received combination therapy of rituximab and low-dose cyclophosphamide, and 14% of patients received plasma exchange (PLEX). After induction, the median (interquartile range [IQR]) time to start avacopan was 3.6 (2.1-7.7) weeks, and the median time to discontinue prednisone after starting avacopan was 5.6 (3.3-9.5) weeks. Clinical remission was achieved in 90% of patients at week 26 and 84% of patients at week 52. Of the patients, 20% stopped avacopan due to adverse events, with the most common being elevated serum aminotransferases (4.3%). A high rate of remission and an acceptable safety profile were observed with the use of avacopan in the treatment of AAV in this postmarketing analysis, including the populations excluded from the ADVOCATE trial.

High-resolution epitope mapping of commercial antibodies to ANCA antigens by yeast surface display

Epitope mapping provides critical insight into antibody-antigen interactions. Epitope mapping of autoantibodies from patients with autoimmune diseases can help elucidate disease immunogenesis and guide the development of antigen-specific therapies. Similarly, epitope mapping of commercial antibodies targeting known autoantigens enables the use of those antibodies to test specific hypotheses. Anti-Neutrophil Cytoplasmic Autoantibody (ANCA) vasculitis results from the formation of autoantibodies to multiple autoantigens, including myeloperoxidase (MPO), proteinase-3 (PR3), plasminogen (PLG), and peroxidasin (PXDN). To perform high-resolution epitope mapping of commercial antibodies to these autoantigens, we developed a novel yeast surface display library based on a series of >5000 overlapping peptides derived from their protein sequences. Using both FACS and magnetic bead isolation of reactive yeast, we screened 19 commercially available antibodies to the ANCA autoantigens. This approach to epitope mapping resulted in highly specific, fine epitope mapping, down to single amino acid resolution in many cases. Our study also identified cross-reactivity between some commercial antibodies to MPO and PXDN, which suggests that patients with apparent autoantibodies to both proteins may be the result of cross-reactivity. Together, our data validate yeast surface display using maximally overlapping peptides as an excellent approach to linear epitope mapping.

Pharmacokinetic Evaluation of the CYP3A4 and CYP2C9 Drug-Drug Interaction of Avacopan in 2 Open-Label Studies in Healthy Participants.

Avacopan, a complement 5a receptor (C5aR) antagonist approved for treating severe active antineutrophil cytoplasmic autoantibody (ANCA)-associated vasculitis, was evaluated in 2 clinical drug-drug interaction studies. The studies assessed the impact of avacopan on the pharmacokinetics (PK) of CYP3A4 substrates midazolam and simvastatin and CYP2C9 substrate celecoxib, and the influence of CYP3A4 inhibitor itraconazole and inducer rifampin on the PKs of avacopan. The results indicated that twice-daily oral administration of 30mg of avacopan increased the area under the curve (AUC) of midazolam by 1.81-fold and celecoxib by 1.15-fold when administered without food, and twice-daily oral administration of 30 or 60mg of avacopan increased the AUC of simvastatin by approximately 2.6-3.5-fold and the AUC of the active metabolite β-hydroxy-simvastatin acid by approximately 1.4-1.7-fold when co-administered with food. Furthermore, the AUC of avacopan increased by approximately 2.19-fold when co-administered with itraconazole and decreased by approximately 13.5-fold when co-administered with rifampin. These findings provide critical insights into the potential drug-drug interactions involving avacopan, which could have significant implications for patient care and treatment planning. (NCT06207682).

Efficacy and safety of avacopan in patients with ANCA-associated vasculitis receiving rituximab in a randomised trial

ObjectivesTo evaluate the efficacy and safety of avacopan in the subgroup of patients with antineutrophil cytoplasmic autoantibody (ANCA)-associated vasculitis receiving background induction therapy with rituximab in the phase 3 ADVOCATE...

Granulomatosis with polyangiitis and microscopic polyangiitis

Granulomatosis with polyangiitis (GPA) and microscopic polyangiitis (MPA) are two entities of ANCA-associated vasculitis (AAV). Both diseases are characterised by systemic necrotising small-vessel vasculitis, which can affect any organ. In GPA, extravascular necrotising granulomatous inflammation, usually affecting the respiratory tract, is found in addition. In the majority of cases, the clinical presentation is dominated by a pulmonary-renal syndrome with alveolar haemorrhage and rapidly progressive glomerulonephritis. Other organ involvement is found as well. In GPA, the upper respiratory tract is commonly affected. GPA is associated with anti-neutrophil cytoplasmic autoantibodies (ANCA) with specificity for proteinase 3 (PR3-ANCA) and MPA with specificity for myeloperoxidase (MPO-ANCA). Immunosuppressive therapy depends on disease activity and the severity of organ involvement.

Development of a Kidney Prognostic Score in a Japanese Cohort of Patients With Antineutrophil Cytoplasmic Autoantibody Vasculitis

Glomerulonephritis is frequent in antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) and crucial to disease outcomes. We conducted a detailed assessment of renal pathology in Japanese patients with AAV, and developed a new score that would predict renal outcome. Two hundred twenty-one patients who were diagnosed with AAV and underwent a kidney biopsy were enrolled. Data on glomerular, tubular, interstitial, and vascular lesions from kidney biopsies were analyzed; the 3 established classification and prognostic scoring systems (Berden Classification, Mayo Clinic/RPS Chronicity Score [MCCS], and ANCA Renal Risk Score [ARRS]) were validated. Further, we developed a new prognostic score by including variables relevant for Japanese patients with ANCA-glomerulonephritis. Median follow-up was 60 months (interquartile range: 6-60). End-stage kidney disease (ESKD) risk prediction by the MCCS and the ARRS was confirmed. Moreover, our analysis identified 4 items with significant ESKD risk prediction capacity, namely percentage of cellular, fibrocellular, and fibrous crescents; and sclerotic glomeruli. Based on our findings, we created a score evaluating the percentage of these lesions to total glomeruli, the Percentage of ANCA Crescentic Score (PACS). The area under the receiver operating characteristic (ROC) curve evaluating PACS was 0.783. The PACS had a comparable performance as the ARRS in predicting ESKD. The optimal PACS cut-off for ESKD risk over 60 months was 43%. In addition, the percentage of cellular crescents and presence of interstitial inflammation were independent predictors of kidney function recovery. We developed a new score predicting renal prognosis using histopathological data of Japanese patients with ANCA-glomerulonephritis. Studies are needed to validate our results in international cohorts.

Antineutrophil Cytoplasmic Autoantibody-negative Pauci-immune Necrotizing Glomerulonephritis with Plasma Cell-rich Tubulointerstitial Nephritis Complicated with Pleuritis and Digital Ischemia.

Antineutrophil cytoplasmic autoantibody (ANCA)-associated vasculitis (AAV) predominantly affects small vessels. Almost all AAV patients are positive for myeloperoxidase- or proteinase 3-ANCA, and ANCA plays a crucial role in the pathogenesis of AAV. We herein report an ANCA-negative AAV patient with pauci-immune necrotizing glomerulonephritis and plasma cell-rich tubulointerstitial nephritis who was complicated with pleuritis and digital ischemia. ANCA-negative AAV is a rare clinical entity that is difficult to diagnose, and pleuritis and digital ischemia are rare manifestations of AAV. An early diagnosis and appropriate treatment are important, as any delay in the diagnosis may worsen the prognosis.

Cardiac valvular involvement in granulomatosis with polyangiitis in long-term observation

Introduction and objectivesGranulomatosis with polyangiitis (GPA) is an antineutrophil cytoplasmic autoantibody (ANCA)-associated systemic vasculitis and is characterized by inflammation of blood vessels. The aim of the present study was to assess cardiac valvular changes in patients with GPA in a cohort of 105 patients followed for a mean of six years. MethodsWe followed 105 patients (mean age 50.4 years, 67 female) for a mean of 6.2±1.3 years. Echocardiography and laboratory tests were performed in all patients. ResultsAt baseline, 43% of patients were diagnosed with aortic regurgitation (AR), which was the most common valvular lesion. Moreover, it was the only valvular involvement that significantly increased during observation (p=0.01). In a multivariate model, only D-dimer level was a predictor of AR in this group of patients (OR 8.0 (95% CI: 1.7–38.2, p=0.01). ConclusionsInvolvement of the heart valves is a common finding in patients with GPA, but significant valvular disease is a rare complication. The most common valvular disease in this group of patients is AR. Aortic valves are also the most prone to degeneration in the course of the vasculitis.

Prediction-Related Hint, Result and Effect of Anti-Neutrophil Cytoplasmic Autoantibodies with Myeloperoxidase Level of Detail in Anti-Glomerular Basement Membrane Disease

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