Antineutrophil Cytoplasmic Antibody Research Articles

Comparison of Interstitial Lung Disease Between Antineutrophil Cytoplasmic Antibodies Positive and Negative Patients: A Retrospective Cohort Study.

Positive antineutrophil cytoplasmic antibodies (ANCAs) may occur in the setting of interstitial lung disease (ILD), with or without ANCA-associated vasculitis (AAV). We aim to compare the characteristics and clinical course of patients with ILD and positive ANCA (ANCA-ILD) to those with negative ANCA. We performed a single-center retrospective cohort study from 2018 to 2021. All patients with ILD and ANCA testing were included. Patient characteristics (symptoms, dyspnea scale, and systemic AAV), test results (pulmonary high-resolution computed tomography and pulmonary function tests), and adverse events were collected from electronic medical records. Descriptive statistics and the Fisher exact test were used to compare the outcomes of patients with ANCA-ILD to those with ILD and negative ANCA. A total of 265 patients with ILD were included. The mean follow-up duration was 69.3 months, 26 patients (9.8%) were ANCA positive, and 69.2% of those with ANCA-ILD had another autoantibody. AAV occurred in 17 patients (65.4%) with ANCA-ILD. In 29.4% of patients, AAV developed following ILD diagnosis. Usual interstitial pneumonia was the most common radiologic pattern in patients with ANCA-ILD. There was no association between ANCA status and the evolution of dyspnea,diffusing capacity of the lungs for carbon monoxide, and lung imaging. Forced vital capacity improved over time in 42% of patients with ANCA-ILD and in 17% of patients with negative ANCA (P = 0.006). Hospitalization occurred in 46.2% of patients with ANCA-ILD and in 21.8% of patients with negative ANCA (P = 0.006). Both groups had similar mortality rates. Routine ANCA testing should be considered in patients with ILD. Patients with ANCA-ILD are at risk for AAV. More research is required to better understand and manage patients with ANCA-ILD.

Slowly Progressive ANCA-associated Glomerulonephritis with Strong Mesangial MPO Deposits Following a Diagnosis of Interstitial Lung Disease.

An elderly woman showed positive conversion of myeloperoxidase (MPO)-antineutrophil cytoplasmic antibodies (ANCAs) following the diagnosis of interstitial lung disease (ILD) and glomerular hematuria and subsequently experienced slowly progressive glomerulonephritis. A kidney biopsy revealed chronic damage and necrotizing crescentic glomerulonephritis with mesangial MPO deposits. After corticosteroid treatment, the patient's urinalysis results and MPO-ANCA titers almost normalized and her renal function stabilized. This case is similar to recently reported cases of slowly progressive ANCA-associated glomerulonephritis. ILD likely triggered the production of MPO-ANCAs, and the accumulation of MPO deposits in the glomeruli may have contributed to the progression of her renal disease.

Antineutrophilic Cytoplasmic Antibody–Positive Vasculitis Associated With Thromboangiitis Obliterans in a Middle-Aged Man

Antineutrophilic Cytoplasmic Antibody–Positive Vasculitis Associated With Thromboangiitis Obliterans in a Middle-Aged Man

Risk factors for severe COVID-19 infection and the impact of COVID-19 infection on disease progression among patients with AAV

To identify risk factors for COVID-19 infection and investigate the impact of COVID-19 infection on chronic kidney disease (CKD) progression and vasculitis flare in patients with antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV). This cohort study retrospectively analyzed the prevalence and severity of COVID-19 infection in 276 patients with AAV who were followed up. Logistic regression was employed to estimate the risk of COVID-19 infection as well as CKD progression and vasculitis flare upon COVID-19 infection. During the 6-month observation period, 213 (77.2%) of 276 patients were diagnosed with COVID-19 infection. Of these 213 patients, 49 (23.0%) had a COVID-19-related inpatient admission, including 17 patients who died of COVID-19 infection. AAV patients with severe COVID-19 infection were more likely to be male (OR 1.921 [95% CI 1.020–3.619], P = 0.043), suffered from worse kidney function (serum creatinine [Scr], OR 1.901 [95% CI 1.345–2.687], P < 0.001), had higher C-reactive protein (CRP) (OR 1.054 [95% CI 1.010–1.101], P = 0.017) and less likely to have evidence of initial vaccination (OR 0.469 [95% CI 0.231–0.951], P = 0.036), and Scr and COVID-19 vaccination were proven to be significantly associated with severe COVID-19 infection even after multivariable adjustment. Severe COVID-19 infection was significantly associated with subsequent CKD progression (OR 7.929 [95% CI 2.030–30.961], P = 0.003) and vasculitis flare (OR 11.842 [95% CI 1.048–133.835], P = 0.046) among patients with AAV. AAV patients who were male, and with worse kidney function were more susceptible to severe COVID-19 infection, which subsequently increased the risk of CKD progression and vasculitis flare.

The predictive performance of the ANCA renal risk score in patients over 65 years of age with renal ANCA-associated vasculitis

Abstract Background The anti-neutrophil cytoplasmic antibody (ANCA) renal risk score (ARRS) for predicting renal survival in ANCA-associated vasculitis (AAV) had not previously been validated in adults over 65 years of age and presenting impairments associated with an aging kidney, a high cardiovascular comorbidity burden, and prevalent microscopic polyangiitis. Methods We retrospectively studied a cohort of 192 patients over 65 years of age (median [interquartile range] age: 73 [68; 78]), including 17.2% with renal-limited vasculitis, 49.5% with microscopic polyangiitis and 33.3% with granulomatosis with polyangiitis, at six centres of northern France. The primary study endpoint was the cumulative incidence of end-stage kidney disease (ESKD, maintenance of dialysis for at least 3 months) at 12 months, with death considered as a competing event. Results The median serum creatinine concentration at diagnosis was 300 [202; 502] µmol/L, and 48 (25.0%) patients required dialysis at presentation. The ARRS was high in 43 (22.4%) patients, medium in 106 (55.2%), and low in 43 (22.4%). The cumulative incidence of ESKD at 12 months was 0% in the low-risk group, 13.0% [7.6–20.0] in the medium-risk group, and 44.0% [29.0–58.0] in the high-risk group (p &amp;lt; 0.001). In the subgroup of 149 patients presenting a medium or high score, the ARRS had a C-index of 0.66 [0.58–0.74] for the prediction of ESKD at 12 months; this rose to 0.86 [0.80–0.90] when dialysis status at diagnosis was included. Conclusion The ARRS was a poor predictor of kidney survival at 12 months among patients over 65 years of age with renal AAV involvement—especially in the high ARRS group. The addition of dialysis status at diagnosis as an additional clinical parameter might improve the ARRS's predictive performance.

Hydralazine-Induced Antineutrophilic Cytoplasmic Antibody (ANCA)-Associated Vasculitis Presenting as Crescentic Glomerulonephritis

Hydralazine-Induced Antineutrophilic Cytoplasmic Antibody (ANCA)-Associated Vasculitis Presenting as Crescentic Glomerulonephritis

Antineutrophil cytoplasmic antibody positivity incidence before and during COVID-19 pandemic.

Antineutrophil cytoplasmic antibody positivity incidence before and during COVID-19 pandemic.

E025 From risk to reward: a case of systemic antineutrophilic cytoplasmic antibody associated vasculitis

Abstract Background/Aims The background and aims of this case involve a 70-year-old female patient with a history of complex medical conditions, including bronchiectasis and dementia, who initially presented with respiratory symptoms and fever. The primary aim was to understand the underlying cause of her deteriorating condition, which did not respond to initial antibiotic treatment for suspected pneumonia. Subsequent diagnostic efforts, including extensive vasculitis workup, were undertaken to identify the source of her symptoms, which led to the discovery of positive PR3 results and elevated inflammatory markers. The key goal was to determine the most effective treatment strategy, considering the patient’s unique medical history, balancing the need for immunosuppressive therapy against the potential risks of exacerbating underlying infections. The case ultimately aimed to demonstrate the successful management of the patient’s complex clinical presentation through a multidisciplinary approach, including immunosuppressive therapy and supportive care, resulting in significant improvements in her neurological and functional status. Methods We conducted a comprehensive assessment of a 70-year-old patient with ANCA-associated vasculitis (AAV) involving the central nervous system (CNS) and cutaneous manifestations. Lab tests targeted PR3-positive ANCA, and imaging assessed disease extent. A multidisciplinary team designed a tailored treatment plan with cyclophosphamide, closely monitoring progress. Ethical considerations were adhered to, and a literature review provided context. Data analysis evaluated treatment efficacy, leading to a discussion of lessons learned in managing complex AAV cases. Results We documented the remarkable trajectory of a 70-year-old patient with ANCA-associated vasculitis (AAV) presenting with central nervous system (CNS) involvement and cutaneous manifestations. With a meticulous and tailored treatment plan involving the judicious use of cyclophosphamide, we witnessed a profound recovery marked by significant improvements in both motor and cognitive function. This case underscores the importance of balancing potent immunosuppression with the imperative to curb disease progression and mitigate treatment-associated repercussions in complex AAV presentations. The patient’s restoration to baseline functioning serves as a compelling testament to the potential of precision medicine in managing intricate clinical scenarios of AAV. Our findings emphasize the need for continued awareness and consideration of individualized treatment approaches in similar cases, offering hope and insights for improved outcomes in challenging AAV presentations. Conclusion This case offers valuable lessons on the complexities and challenges involved in diagnosing and managing a multi-faceted condition like AAV. It emphasizes the urgent need for a timely and accurate diagnosis, especially when presented with atypical cases involving the central nervous system and cutaneous manifestations. Moreover, the case enriches our understanding of AAV and contributes insights into its nuanced management. It calls for a sophisticated, patient-centered approach, informed by cutting-edge research, to optimize patient outcomes in this challenging clinical scenario. Disclosure A.J. AlZeera: None. D. Gurdeep: None.

Investigating the concomitance of anti-neutrophil cytoplasmic antibody (ANCA) associated vasculitides and inflammatory bowel disease (IBD)

ObjectiveTo assess relationship between Anti-neutrophil cytoplasmic antibody (ANCA) associated vasculitis and inflammatory bowel disease (IBD). MethodsThis is a retrospective study design. The patients were identified using a preset criteria of patients who have the diagnosis of ANCA associated vasculitis including a diagnosis of granulomatosis with polyangiitis (GPA) or microscopic polyangiitis (MPA) or eosinophilic granulomatosis with polyangiitis (EGPA) with overlapping inflammatory bowel disease (Crohn's disease or ulcerative colitis) in the time period from 01/01/2020 to 08/03/2023. Subsequently data from each patient was collected that will include baseline demographics, disease characteristics, disease activity, treatment information, multiorgan involvement, and pathology findings which were then analyzed. Results39 patients were identified that met criteria. 20 patients carried a diagnosis of GPA, 6 had MPA and 4 patients had EGPA. 20 patients with GPA had inflammatory bowel disease, 13 with ulcerative colitis and 6 with Crohn's disease while 1 GPA patient had unspecified inflammatory bowel disease. 4 patients with EGPA had inflammatory bowel disease, 2 with ulcerative colitis and 2 with Crohn's disease. 6 patients with MPA had inflammatory bowel disease, 4 with ulcerative colitis and 2 with Crohn's disease. IBD diagnosis preceded the diagnosis of ANCA vasculitis in 77.8 % of the cases. ConclusionObjective observation and deductions from this study raise the concern for a possible pathogenic association of ANCA associated vasculitis and inflammatory bowel disease and more research is needed to identify any causal association or influence of the two systemic disease on each other.

On the problem of differential diagnosis in the detection of antineutrophil cytoplasmic antibodies

Vasculitides associated with antineutrophil cytoplasmic antibodies (ANCA) are a group of systemic autoimmune diseases characterized by necrotizing lesions of the walls of predominantly small vessels and the presence of ANCA against proteinase 3 or myeloperoxidase. However, an increase in ANCA levels can also be observed in other diseases, including autoimmune, malignant and infectious diseases, which complicates the interpretation of clinical and laboratory data and requires a differential diagnosis.

Deciphering Three Predominant Biopsy-proved Phenotypes of IgG4-associated Kidney Disease: A Retrospective Study

Abstract Background IgG4-associated kidney disease (IgG4-RKD) encompasses a spectrum of disorders, predominantly featuring tubulointerstitial nephritis (TIN) and membranous glomerulonephropathy (MGN). The limited understanding of the co-occurrence of IgG4-RD-TIN with anti-neutrophil cytoplasmic antibodies (ANCA)-associated vasculitis (AAV) poses a diagnostic and therapeutic challenge. Methods We examined 49 cases, comprising 21 cases of IgG4-RD-TIN (group A), 10 cases of IgG4-RD-TIN accompanied with MGN (group B), and 18 cases of IgG4-RD-TIN concurrent with AAV (group C), at the First Affiliated Hospital of Zhejiang University, China, from June 2015 to December 2022. Results The mean age and gender of the three IgG4-RKD subtypes were not statistically significant. IgG4-RD-TIN exhibited higher serum creatinine and a higher incidence of hypocomplementemia (group A: 47.6%, group B: 30%, group C: 16.7%). IgG4-RD-TIN-MGN was characterized by proteinuria (group A: 0.3 g/d, group B: 4.0 g/d, group C: 0.8 g/d, p &amp;lt; 0.001) and hypoalbuminemia. IgG4-RD-TIN-AAV exhibited hypohemoglobinemia (group A: 103.45 g/L, group B: 119.60 g/L, group C: 87.94 g/L, p &amp;lt; 0.001) and a high level of urine erythrocytes. The primary treatment for IgG4-RD-TIN was steroids alone, whereas IgG4-RD-TIN-MGN and IgG4-RD-TIN-AAV necessitated combination therapy. Group A experienced two relapses, whereas groups B and C had no relapses. There was no significant difference in patient survival among the three groups, and only two cases in group C suffered sudden death. Conclusions This study provides valuable insights into clinical manifestations, auxiliary examination features, pathological characteristics and prognosis of IgG4-RD-TIN, IgG4-RD-TIN-MGN, and IgG4-RD-TIN concurrent AAV. Large-scale studies are required to validate these findings.

Sinonasal manifestations of granulomatosis with polyangiitis: A retrospective analysis

ObjectiveThis study aimed to examine the characteristics of nasal and imaging findings of sinonasal lesions in granulomatosis with polyangiitis (GPA) patients and how these lesions change over time in both the active and remission phases of the disease. MethodsWe retrospectively reviewed GPA patients with sinonasal lesions who were followed up at our department between January 2005 and December 2020. The following data were collected: age, sex, symptoms at initial presentation, anti-neutrophil cytoplasmic antibody (ANCA) type, and histopathological, nasal (initial and follow-up), and imaging (initial and follow-up) findings. ResultsThis study included 17 patients with GPA aged 30 to 79 years. Computed tomography (CT) of the sinuses showed mucosal thickening in 16 patients, bone thickening in 12, bone destruction in 4, and an orbital invasion mass in 3 at the time of diagnosis. After initiating treatment, mucosal thickening of the sinuses improved in 3 of 16 patients and remained unchanged in 13. Bone thickening at the time of diagnosis remained unchanged in 10 of 12 patients and worsened in 2; 1 patient displayed newly developed bone thickening. Destructive nasal findings on CT were positive for proteinase 3-ANCA. ConclusionsOur study revealed that mucosal thickening, bone thickening, bone destruction, and orbital invasion mass were major CT findings in patients with GPA. Intranasal findings such as granulations, crusting, and necrosis were seen in the active phase; moreover, saddle nose, loss of turbinate, and nasal septal perforation were subsequently seen in the course of the disease. Sinonasal findings of GPA vary depending on the disease stage and period.

Clinical outcomes and clinico-pathological correlations in children with MPO-ANCA-associated glomerulonephritis showing renal arteritis.

The aim of this study was to evaluate the clinical features, pathological characteristics, and prognosis in myeloperoxidase (MPO)-antineutrophil cytoplasmic antibodies (ANCA)-associated glomerulonephritis (AAGN) with renal arteritis. The study involved 97 children from five pediatric clinical centers with MPO-AAGN who exhibited distinct clinical features. The patients were divided into AAGN-A+ and AAGN-A-, based on the presence or absence of arteritis, and the disparities in clinical, histopathological characteristics, and prognosis between the two groups was evaluated. In contrast to the AAGN-A- group, the children in the AAGN-A+ group exhibited more pronounced clinical symptoms and renal pathological injury. Arteritis positively moderately correlated with the serum creatinine, interleukin-6, urinary neutrophil gelatinase-associated lipocalin, negatively moderately correlated with serum complement C3. The renal survival rate in the AAGN-A+ group was significantly poorer than AAGN-A- group (χ2 = 4.278, p = 0.039). Arteritis showed a good predictive value for end-stage kidney disease (ESKD), and C3 deposition, ANCA renal risk score and arteritis were independent risk factors for the development of ESKD in children with MPO-AAGN. Arteritis is a significant pathological change observed in children with MPO-AAGN, and the formation of arteritis may be related to the inflammatory response and activation of the complement system.

Antineutrophil cytoplasmic antibody in children with nephrotic syndrome treated with levamisole: a cross-sectional cohort study.

Levamisole is a commonly used steroid-sparing agent (SSA), but the reported incidence of antineutrophil cytoplasmic antibody (ANCA) positivity has been concerning. Observational cross-sectional study wherein children aged 2 to 18years with frequently relapsing/steroiddependent nephrotic syndrome (FRNS/SDNS) on levamisole for ≥ 12months were tested for ANCA. A total of 210 children (33% female), median age of 7.3 (IQR: 5.6-9.6) years, and a median duration of levamisole exposure of 21 (IQR: 15-30) months were tested. ANCA was positive in 18% (n = 37): 89% (n = 33) perinuclear ANCA (pANCA), 3% (n = 1) cytoplasmic ANCA (cANCA), and 8% (n = 3) both. Of ANCA-positive children, none had reduced eGFR or abnormal urinalysis. The majority of these children were asymptomatic (81%, n = 30). Rash was more common among ANCA-positive children [6/37 (16%) vs. 3/173 (2%), p = 0.0001]. On multivariate analysis, higher age (OR = 1.02, [95th CI: 1.01 to 1.03], p = 0.007) and longer duration of levamisole exposure (OR = 1.05, [95th CI: 1.02 to 1.08], p = 0.0007) were associated with ANCA positivity. Levamisole was stopped in ANCA-positive children with the resolution of any clinical manifestations if present. Repeat ANCA testing was performed in 54% (20/37), and all were ANCA negative by 18months. Children with FRNS/SDNS on longer duration of levamisole were associated with increasing prevalence of ANCA positivity, but most of these children were clinically asymptomatic. Prospective studies are required to determine the chronology of ANCA positivity and its clinical implication.

Inflammatory Bowel Disease and Its Association With Perinuclear Antineutrophil Cytoplasmic Antibodies: A Systematic Review.

An idiopathic condition known as inflammatory bowel disease (IBD) is characterized by a dysregulated immune response to the intestinal flora of the host. It falls into one of two primary categories: ulcerative colitis or Crohn's disease. A wide range of disorders, both clinically and genetically, can cause IBD. The purpose of this thorough analysis is to determine the significance and reliability of the correlation between perinuclear antineutrophil cytoplasmic antibodies (p-ANCA) and IBD, as well as the implications of this correlation for the diagnosis and treatment of IBD. Ten pertinent studies were identified from a starting pool of 20 articles in this systematic review, which was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) 2020 guidelines. These studies addressed treatment, complications, limitations, and outcome in addition to the presence or lack of p-ANCA in patients with IBD. In conclusion, p-ANCA is more strongly linked to inflammatory bowel illness than Crohn's disease, primarily ulcerative colitis. Some evidence suggests that there is a decrease in p-ANCA to some extent with medical or surgical interventions, but the exact intervention is not yet clear. There is less evidence suggesting that the medical or surgical treatments used in patients with IBD cause an increase or decrease in p-ANCA.

Clinical features and prognosis of ANCA-associated vasculitis patients who were double-seropositive for myeloperoxidase-ANCA and proteinase 3-ANCA

Anti-neutrophil cytoplasmic antibody (ANCA)–associated vasculitis (AAV) patients with dual positivity for proteinase 3-ANCA (PR3-ANCA) and myeloperoxidase-ANCA (MPO-ANCA) are uncommon. We aimed to investigate these idiopathic double-positive AAV patients’ clinical features, histological characteristics, and prognosis. We reviewed all the electronic medical records of patients diagnosed with AAV to obtain clinical data and renal histological information from January 2010 to December 2020 in a large center in China. Patients were assigned to the MPO-AAV group or PR3-AAV group or idiopathic double-positive AAV group by ANCA specificity. We explored features of idiopathic double-positive AAV. Of the 340 patients who fulfilled the study inclusion criteria, 159 (46.76%) were female, with a mean age of 58.41 years at the time of AAV diagnosis. Similar to MPO-AAV, idiopathic double-positive AAV patients were older and had more severe anemia, lower Birmingham Vasculitis Activity Score (BVAS) and C-reactive protein (CRP) levels, less ear, nose, and throat (ENT) involvement, higher initial serum creatinine and a lower estimated glomerular filtration rate (eGFR) when compared with PR3-AAV (P < 0.05). The proportion of normal glomeruli of idiopathic double-positive AAV was the lowest among the three groups (P < 0.05). The idiopathic double-positive AAV patients had the worst remission rate (58.8%) among the three groups (P < 0.05). The relapse rate of double-positive AAV (40.0%) was comparable with PR3-AAV (44.8%) (P > 0.05). Although there was a trend toward a higher relapse rate of idiopathic double-positive AAV (40.0%) compared with MPO-AAV (23.5%), this did not reach statistical significance (P > 0.05). The proportion of patients who progressed to ESRD was 47.1% and 44.4% in the idiopathic double-positive AAV group and MPO-AAV group respectively, without statistical significance. Long-term patient survival also varied among the three groups (P < 0.05). Idiopathic double-positive AAV is a rare clinical entity with hybrid features of MPO-AAV and PR3-AAV. MPO-AAV is the “dominant” phenotype in idiopathic double-positive AAV.

Thyroid disease in ANCA-associated vasculitis: a clinical and epidemiological study

ObjectivesTo describe clinical and laboratory characteristics and outcomes in patients with antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) and thyroid disease (TD). We also aimed to calculate incidence and identify predictors...

Hepatitis C virus-related autoimmunity before and after viral clearance: a single center, prospective, observational study.

Hepatitis C virus (HCV) chronic infection is frequently associated to autoimmune manifestations. The aim of this study was to prospectively evaluate the occurrence of clinical and/or laboratory features of autoimmunity in a cohort of 140 consecutive HCV chronically infected patients treated with direct-acting antiviral agents (DAAs) and followed-up for 96 weeks. All patients were screened for cryoglobulins, rheumatoid factor (RF), C3, C4, antinuclear antibody (ANA), anti-smooth muscle (ASMA), anti-liver kidney microsome type 1 (anti-LKM1), anti-mitochondrial antibodies (AMA), anti-neutrophil cytoplasmic antibodies (ANCA), and anti-liver cytosol type 1/soluble liver antigen (anti-LC1/SLA) autoantibodies before therapy and 12, 48 and 96 weeks after treatment. They were then grouped according to the expression of laboratory findings and related autoimmune diseases. At baseline, autoimmune manifestations were found in 70 patients: 83% of them were cryoglobulinemic, whereas ANA, AMA, perinuclear ANCA (pANCA) and LKM/LC1 autoantibodies were found in the remaining 17%. An autoimmune disease was diagnosed in 9 cases, two of them featuring an autoimmune liver disease (AILD). At the end of follow-up, despite viral clearance and regression of vasculitis, cryoglobulins persisted in 12 patients (21%), and autoantibodies disappeared or decreased in most of cases but, with the exception of the 2 patients diagnosed as AILD, associated autoimmune diseases remained stable. In one patient with relapsing cryoglobulinemia and ANA positivity, type-1 autoimmune hepatitis was defined. Conversely, autoantibodies first appeared after viral clearance in 5 patients, of whom one was diagnosed with type-1 autoimmune hepatitis and one with pANCA+ primary sclerosing cholangitis. Following DAA-induced viral clearance, cryoglobulins may persist or reappear. Autoantibodies changed dynamically in step with the disappearance of a previously diagnosed or the occurrence of a new AILD. A longer follow-up will be necessary to establish the possible diagnosis of a newly onset AILD, the reactivation of cryoglobulinemic vasculitis and even its progression to non-Hodgkin lymphoma.

Myeloperoxidase-specific antineutrophil cytoplasmic antibody-associated vasculitis.

Myeloperoxidase (MPO)-specific antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (MPO-ANCA-associated vasculitis) is one of two major ANCA-associated vasculitis variants characterised by systemic necrotising vasculitis with few or no immune deposits. MPO-ANCA-associated vasculitis predominantly affects small blood vessels and, in contrast to its counterpart proteinase 3-ANCA-associated vasculitis, is generally not associated with granulomatous inflammation. The kidneys and lungs are the most commonly affected organs. The pathogenesis of MPO-ANCA-associated vasculitis is characterised by loss of tolerance to the neutrophil enzyme MPO. This loss of tolerance leads to a chronic immunopathological response where neutrophils become both the target and effector of autoimmunity. MPO-ANCA drives neutrophil activation, leading in turn to tissue and organ damage. Clinical trials have improved the therapeutic approach to MPO-ANCA-associated vasculitis. However, there remains substantial unmet need regarding relapse frequency, toxicity of current treatment, and long-term morbidity. In this Series paper, we present the current state of research regarding pathogenesis, diagnosis, and treatment of MPO-ANCA-associated vasculitis.

The HLA region in ANCA-associated vasculitis: characterisation of genetic associations in a Scandinavian patient population

ObjectiveThe antineutrophil cytoplasmic antibody (ANCA)-associated vasculitides (AAV) are inflammatory disorders with ANCA autoantibodies recognising either proteinase 3 (PR3-AAV) or myeloperoxidase (MPO-AAV). PR3-AAV and MPO-AAV have been associated with distinct loci...