Incidence, prevalence, mortality and chronic renal damage of anti-neutrophil cytoplasmic antibody-associated glomerulonephritis in a 20-year population-based cohort

The value of the current histological scores and classifications of ANCA glomerulonephritis in predicting long-term outcome

Background

Three different histological scores-histopathologic classification (Berden), Renal Risk Score (RRS) and the Mayo Clinic Chronicity Score (MCCS)-for anti-neutrophil cytoplasmic antibody (ANCA)-associated glomerulonephritis (ANCA-GN) were compared to evaluate their association with patient and kidney prognosis of ANCA-GN.

Methods

Patients aged >18 years with at least 1 year of follow-up and biopsy-proven ANCA-GN entered this retrospective study. Renal biopsies were classified according to Berden's classification, RRS and MCCS. The first endpoint was end-stage kidney disease (ESKD), defined as chronic dialysis or estimated glomerular filtration rate <15 mL/min/1.73 m2. The second endpoint was ESKD or death.

Results

Of 152 patients 84 were males, with median age of 63.8 years and followed for 46.9 (interquartile range 12.8-119) months, 59 (38.8%) reached the first endpoint and 20 died. The Kaplan-Meier curves showed that Berden and RRS were associated with first (Berden: P = .004, RRS: P < .001) and second (Berden: P = .001, RRS: P < .001) endpoint, MCCS with the first endpoint only when minimal + mild vs moderate + severe groups were compared (P = .017), and with the second endpoint (P < .001). Among the clinical/histological presentation features, arterial hypertension [odds ratio (OR) = 2.75, confidence interval (95% CI) 1.50-5.06; P = .0011], serum creatinine (OR = 1.17, 95% CI 1.09-1.25; P < .0001), and the percentage of normal glomeruli (OR = 0.97, 95% CI 0.96-0.99; P = .009) were the independent predictors of ESKD at multivariate analysis. When the three scores were included in multivariate analysis, RRS (OR = 2.21, 95% CI 1.15-4.24; P = .017) and MCCS (OR = 2.03, 95% CI 1.04-3.95; P = .037) remained predictive of ESKD, but Berden (OR = 1.17, 95% CI 0.62-2.22; P = .691) did not.

Conclusion

RRS and MCCS scores were independent predictors of kidney survival together with high serum creatinine and arterial hypertension at diagnosis, while Berden classification was not.

Outcomes of Renal Transplantation in ANCA-Associated Vasculitis

BACKGROUND Antineutrophil cytoplasmic antibody-associated vasculitis is characterized by small-vessel inflammation and ANCA-positive serology that often lead to end-stage kidney disease. This study investigated the outcomes of renal transplantation in patients with antineutrophil cytoplasmic antibody-associated vasculitis. MATERIAL AND METHODS A comprehensive search of PubMed, Scopus, and Embase databases was done to retrieve studies that reported on the outcomes of renal transplantation in these patients. Data on mortality, survival, infection, and relapse rates were analyzed. The quality of the included studies was evaluated using the Newcastle-Ottawa Scale for cohort studies. RESULTS Twenty-three retrospective cohort studies were included in this review. Antineutrophil cytoplasmic antibody-associated vasculitis was associated with high post-transplantation mortality rates, with a pooled rate ratio of 11.99 per 100 patient-years, but relatively favorable survival rate (hazard rate of 0.80). After renal transplantation, these patients had elevated infection rates (pooled rate ratio of 52.70 per 100 patient-years), and high risk of relapse (pooled rate ratio of 6.96), emphasizing the importance of vigilant post-transplantation monitoring. CONCLUSIONS End-stage kidney disease patients with vasculitis, undergoing renal transplantation, are at elevated risk of mortality and postoperative infection compared to patients without antineutrophil cytoplasmic antibody-associated vasculitis. The risk of relapse is also high in these patients. However, renal transplantation offers a survival advantage for vasculitis patients who survive the early post-transplantation period.

Significance of the total renal chronicity score in predicting renal outcome in PLA2R-associated membranous nephropathy

BACKGROUND

Phospholipase A2 receptor (PLA2R)-associated membranous nephropathy accounts for the majority of membranous nephropathy; however, few studies have determined the prognostic impact and clinical application of renal pathologic change on this disease.

METHODS

A retrospective cohort study of 262 patients with PLA2R-associated membranous nephropathy was conducted. The total renal chronicity score calculated according to the degree of glomerulosclerosis, interstitial fibrosis, tubular atrophy, and arteriosclerosis was applied to evaluate renal chronicity. Baseline bias was adjusted by inverse probability weight when assessing the prognostic impact of chronicity, and multiple parameters were used to evaluate the application value of renal chronicity.

RESULTS

During a median follow-up of 24.5 months, renal outcome (kidney function deterioration and/or end-stage kidney disease) was observed in 22 (8.40%) patients. Not only did a higher total renal chronicity score independently predict renal outcome [odds ratio (OR): 1.562, 95% confidence interval (CI) 1.073-2.273, P = 0.020], but non-minimal chronicity was also an independent risk factor for renal outcome (OR: 3.170, 95% CI 1.040-9.659, P = 0.042). Moreover, the membranous nephropathy risk classification in the Kidney Disease: Improving Global Outcomes (KDIGO) guideline integrated with non-minimal chronicity showed improvements in categorical net reclassification (0.174, 95% CI 0.012-0.335, P = 0.035), continuous net reclassification (0.462, 95% CI 0.087-0.838, P = 0.016), and integrated discrimination (0.019, 95% CI 0.003-0.035, P = 0.020) compared to the original classification.

CONCLUSIONS

Renal chronicity is closely associated with renal outcomes in PLA2R-associated membranous nephropathy, and combining the KDIGO risk classification with chronicity scores may provide a more accurate prognostic prediction.

The correlation of interstitial change with renal prognosis in patients with myeloperoxidase-ANCA-associated glomerulonephritis: a single-center retrospective analysis

OBJECTS

We aim to explore the correlation between active/chronic tubulointerstitial injury and renal survival, and to compare their predictive value in patients with myeloperoxidase (MPO)-anti-neutrophil cytoplasmic antibody (ANCA)-associated glomerulonephritis (AAGN).

METHOD

A total of 225 patients with MPO-AAGN diagnosed between February 2004 and December 2020 were included. Survival and univariate/multivariate Cox regression analyses were used to analyze the prognostic value of interstitial inflammation and interstitial fibrosis/tubular atrophy (IF/TA).

RESULTS

Of the 225 patients, 73 (32.4%) patients developed end-stage renal disease (ESRD) requiring maintenance dialysis. Interstitial inflammation>50% and IF/TA>50% were important predictors for ESRD in MPO-AAGN in multivariate Cox regression analysis adjusted by age, gender, estimated glomerular filtration rate (eGFR)≤15 ml/min/1.73m2, and normal glomeruli% (classified by <25%, 25-50%, >50%). Furthermore, we conducted stratified Cox regression analysis and found different results in the subgroups of eGFR>15 ml/min/1.73m2 and eGFR≤15 ml/min/1.73m2. Interstitial inflammation>50% and IF/TA>50% were significant risk factors for ESRD in the subgroup of eGFR>15 ml/min/1.73m2, but not or less significant in the subgroup of eGFR≤15 ml/min/1.73m2. Similarly, the survival analysis according to interstitial inflammation>50%/≤50% and IF/TA>50%/≤50% showed significant differences in the subgroup of eGFR>15 ml/min/1.73m2, but not or less significant in the subgroup of eGFR≤15 ml/min/1.73m2.

CONCLUSIONS

Interstitial inflammation>50% and IF/TA>50% were prognostic factors for renal survival in MPO-AAGN. In particular, interstitial inflammation and IF/TA had a better predictive ability in the subgroup of eGFR>15 ml/min/1.73m2. Key Points • Interstitial inflammation>50% and IF/TA>50% can help to predict renal survival in MPO-AAGN. • Both interstitial inflammation and IF/TA had a better predictive ability in the subgroup of eGFR>15 ml/min/1.73m2 than those in the subgroup of eGFR≤15 ml/min/1.73m2.

Adding 6-month parameters for the prediction of kidney prognosis in ANCA-associated glomerulonephritis

Background

Antineutrophil-cytoplasmic antibody (ANCA)-associated vasculitis (AAV) with kidney involvement (AAV-GN) frequently evolves to end-stage kidney disease (ESKD) despite aggressive immunosuppressive treatment. Several risk scores have been used to assess renal prognosis. We aimed to determine whether kidney function and markers of AAV-GN activity after 6 months could improve the prediction of ESKD.

Methods

This retrospective and observational study included adult patients with AAV-GN recruited from six French nephrology centers (including from the Maine-Anjou AAV registry). The primary outcome was kidney survival. Analyses were conducted in the whole population and in a sub-population that did not develop ESKD early in the course of the disease.

Results

When considering the 102 patients with all data available at diagnosis, Berden classification and Renal Risk Score (RRS) were not found to be better than kidney function [estimated glomerular filtration rate (eGFR)] alone at predicting ESKD (C-index = 0.70, 0.79, 0.82, respectively). Multivariables models did not indicate an improved prognostic value when compared with eGFR alone.When considering the 93 patients with all data available at 6 months, eGFR outperformed Berden classification and RRS (C-index = 0.88, 0.62, 0.69, respectively) to predict ESKD. RRS performed better when it was updated with the eGFR at 6 months instead of the baseline eGFR. While 6-month proteinuria was associated with ESKD and improved ESKD prediction, hematuria and serological remission did not.

Conclusion

This work suggests the benefit of the reassessment of the kidney prognosis 6 months after AAV-GN diagnosis. Kidney function at this time remains the most reliable for predicting kidney outcome. Of the markers tested, persistent proteinuria at 6 months was the only one to slightly improve the prediction of ESKD.

Pulmonary hypertension in ANCA-associated vasculitis: a retrospective analysis

BACKGROUND

Little is known about pulmonary hypertension (PH) in antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV).

OBJECTIVES

The aims of this retrospective study, in which echocardiography was used for detection of PH, were to identify the potential causes of PH in AAV and to analyze the risk factors for mortality.

METHODS

We performed a retrospective descriptive review of 97 patients who had AAV with PH at our institution from January 1, 1997, through December 31, 2015. These patients with PH were compared with 558 patients who had AAV without PH. Demographic and clinical data were abstracted from electronic health records.

RESULTS

Among the patients who had PH, 61% were men; mean (SD) age was 70.5 (14.1) years at the time of PH diagnosis. The majority of patients with PH (73.2%) had more than 1 potential cause of PH, with left heart disease and chronic lung disease being the most common causes. Older age, male sex, smoking history, and kidney involvement were associated with the presence of PH. PH was associated with an increased risk of death (hazard ratio, 3.15; 95% CI, 2.37-4.18). On multivariate analysis, PH, age, smoking status, and kidney involvement were independent risk factors for death. Median survival after the diagnosis of PH was 25.9 months (95% CI, 12.2-49.9).

CONCLUSIONS

PH in AAV is often multifactorial, is commonly associated with left heart disease, and is associated with a poor prognosis.

Evaluation of a renal risk score for Japanese patients with ANCA-associated glomerulonephritis in a multi-center cohort study

Background

In patients with anti-neutrophil cytoplasmic antibody (ANCA)-associated glomerulonephritis, prediction of renal survival should guide the choice of therapy, but a prediction of the histological classification has inconsistencies.

Objectives

To evaluate the usefulness of renal risk score (RRS) for Japanese patients with ANCA-associated glomerulonephritis (AAGN) and compare the prediction for end-stage renal disease (ESRD) between RRS and the histological classification.

Methods

We retrospectively analyzed 96 patients with AAGN who underwent a renal biopsy. Renal survival was categorized by RRS, and the histological classification was assessed separately. We compared the predictive values for RRS and the histological classification.

Results

The median observational period was 37.5 (interquartile range [IQR] 21.5-77.0) months. The median RRS point at the time of renal biopsy was 2 (IQR 0-7.8), and the patients were categorized into low- (n = 29), medium- (n = 43), and high-risk groups (n = 24) using RRS. As expected, the renal prognosis was the worst in the "high-risk" group and the best in the "low-risk" group. In the histological classification, the survival deteriorated progressively from "focal" (best) to "mixed," "crescentic," and "sclerotic" (worst) classes, different from the order in the original proposal for this system. Multivariable Cox regression analysis revealed that RRS was independently associated with ESRD. The difference in prediction for renal survival between RRS and the histological classification was not significant using area under receiver-operating-characteristic curves.

Conclusion

We evaluated the usefulness of RRS in Japanese patients with AAGN and found it a stable predictor of renal survival in such patients.

Plasma Exchange for ANCA-Associated Vasculitis: An International Survey of Patient Preferences

Rationale & Objective

We sought to elicit patient preferences regarding the use of plasma exchange in antineutrophil cytoplasmic antibody-associated vasculitis (AAV) and its tradeoffs of risk of kidney failure and risk of serious infection.

Study Design

Patient survey.

Setting & Participants

The online survey was circulated to adults with AAV via kidney and vasculitis networks in Canada, the United Kingdom, and the United States.

Outcomes

Respondents reviewed the estimated 1-year risks of kidney failure and serious infection in AAV with and without plasma exchange across 5 serum creatinine categories (150, 250, 350, 450, and 600 μmol/L). For each scenario, participants indicated whether or not they would choose plasma exchange.

Analytical Approach

Responses were assessed with multilevel multivariable logistic regression models to identify predictors of respondent choice regarding treatment with plasma exchange.

Results

The 470 respondents from the 13 countries (United States 61.7%, United Kingdom 20.0%, Canada 13.8%, and other countries 4.5%) had a mean age of 58.6 (SD 14.3) years, 70.2% women. Respondents were more likely to choose plasma exchange in scenarios at high risk of kidney failure and serious infection (creatinine level of 350 or 450 μmol/L) compared with lower risk scenarios or the highest risk scenario. However, 145 (30.9%) chose plasma exchange across all scenarios, whereas 80 (17.0%) declined plasma exchange across all scenarios. Respondents from the United Kingdom (OR, 2.61; 95% CI, 1.09-6.22) who received previous dialysis (OR, 2.70; 95% CI, 1.12-6.52) or received previous plasma exchange (OR, 5.62; 95% CI, 2.72-11.61) were more likely to choose plasma exchange, whereas older respondents (OR, 0.98; 95% CI, 0.96-0.99 per 1 year increase) were less likely.

Limitations

Unclear generalizability to non-English-speaking, older, and less health literate adults, possible responder bias, survivor bias, lack of individualized risk assessments for kidney failure, and serious infection.

Conclusions

Patients with AAV do not express a consistent choice for plasma exchange, which highlights the need for shared decision making.

Epidemiology of granulomatosis with polyangiitis and microscopic polyangiitis in adults in France

BACKGROUND

Granulomatosis with polyangiitis (GPA) and microscopic polyangiitis (MPA) are rare systemic necrotizing vasculitis. The national incidence and prevalence of GPA/MPA and patient mortality remain unknown in France. A real-life study using retrospective data from the French National Health Data System was set up to describe the epidemiology and demographic characteristics of hospitalized GPA and MPA patients, overall and by disease.

METHODS

All adult patients (≥18 years of age) hospitalized for GPA (ICD-10 M31.3) or MPA (ICD-10 M31.7) between 01 and 01-2010 and 31-12-2017 and affiliated to the General health insurance Scheme (covering 76% of the French population) were included in this national retrospective observational study. Descriptive analyses, univariate and multivariable logistic models, Kaplan-Meier survival analysis, and Cox models were performed.

RESULTS

The study involved 4445 prevalent GPA patients (including 1578 incident patients) and 1833 prevalent MPA patients (878 incident patients). Distinction between GPA and MPA diagnosis could not be made for 303 patients (149 incident patients). In people aged over 20 years, the age-standardized incidence rates of GPA and MPA were 0.5 and 0.3/100,000 person-years, respectively and the age-standardized prevalence rates were 10 and 4/100,000 person-years, respectively. The standardized mortality ratios in GPA and MPA patients aged over 20 years were 2.0 and 2.7, respectively, and remained constant. Renal failure, pulmonary and urinary tract infections, as well as coronary disease were more frequent among MPA than GPA patients. One-year survival rates among GPA and MPA patients were 96% (95%CI 94%-97%) and 94% (92%-95%), respectively. Five-year survival rates among GPA and MPA patients were 81% (95% CI 79%-83%) and 72% (68%-75%), respectively. After adjusting for comorbidities, the risk of death was still higher in MPA (hazard ratio 1.26 [95%CI 1.06-1.50]) than in GPA patients.

CONCLUSIONS

Despite advances in the therapeutic management of patients, mortality rates are still high and stable over time, highlighting the need for improved management.

The Potential Applications of Raman Spectroscopy in Kidney Diseases

Raman spectroscopy (RS) is a spectroscopic technique based on the inelastic interaction of incident electromagnetic radiation (from a laser beam) with a polarizable molecule, which, when scattered, carries information from molecular vibrational energy (the Raman effect). RS detects biochemical changes in biological samples at the molecular level, making it an effective analytical technique for disease diagnosis and prognosis. It outperforms conventional sample preservation techniques by requiring no chemical reagents, reducing analysis time even at low concentrations, and working in the presence of interfering agents or solvents. Because routinely utilized biomarkers for kidney disease have limitations, there is considerable interest in the potential use of RS. RS may identify and quantify urinary and blood biochemical components, with results comparable to reference methods in nephrology.

Histopathological prognostic factors in ANCA-associated glomerulonephritis

Anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) are a group of multisystemic autoimmune diseases characterized by necrotizing inflammation of small vessels. Kidney involvement is frequent in granulomatosis with polyangiitis (GPA) and microscopic polyangiitis (MPA), and accounts for a significant proportion of the morbidity and mortality related to these diseases. Despite improvement in therapeutic management of ANCA-glomerulonephritis (ANCA-GN), end-stage kidney disease (ESKD) still occurs in up to 30% of affected patients within 5 years following diagnosis. Thus, identifying patients for whom aggressive immunosuppressive therapy will be more beneficial than deleterious is of great importance. Several clinical, biological and histological factors have been proposed as predictors of ESKD. The kidney biopsy is essential not only for the diagnosis, but also for evaluating renal prognosis. In this review, we discuss the prognostic value of renal lesions at the diagnosis of ANCA-GN by analyzing each compartment of the nephron. We also review existing ESKD risk classification in ANCA-GN and finally propose an example of a standardized pathology report that could be used in routine practice.

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

Objectives

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

Methods

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

Results

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

Conclusion

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

Diagnostic and Therapeutic Approach in ANCA-Associated Glomerulonephritis: A Review on Management Strategies

Anti-neutrophil cytoplasmic autoantibody (ANCA)-associated vasculitis is a destructive small vessel vasculitis affecting multiple organs. Renal involvement often leads to end-stage renal disease and increases mortality. Prompt diagnosis and initiation of adequate immunosuppressive therapy are critical for the best patient and kidney outcomes. However, considerable heterogeneity in symptoms and severity across the patients frequently hinder the diagnosis and management. The objective of this review is to emphasize the heterogeneity of the ANCA-associated vasculitis, facilitate the recognition and give guidance to the therapeutical possibilities. We present epidemiologic and risk factors, pathogenesis, and provide comprehensive clinical features of the disease. This article also focuses on the currently available therapeutic options and emerging cellular and molecular targets for the management of systemic and especially renal disease. We conducted extensive literature research published on PubMed and Google Scholar. We systematically reviewed, analyzed, and assembled databases, covering a broad spectrum of aspects of the disease. We compared and summarized the recommendations of two recent guidelines on ANCA-associated vasculitis. The incidence of ANCA-associated vasculitis, hence glomerulonephritis shows a steady increase. Familiarity with the presenting symptoms and laboratory abnormalities are necessary for rapid diagnosis. Early initiation of treatment is the key aspect for favorable patient and renal outcomes. A better understanding of the pathogenesis constantly leads to more targeted and therefore more efficient and less toxic treatment.

Acute glomerulonephritis

Glomerulonephritis is a heterogeneous group of disorders that present with a combination of haematuria, proteinuria, hypertension, and reduction in kidney function to a variable degree. Acute presentation with full blown nephritic syndrome or rapidly progressive glomerulonephritis is uncommon and is mainly restricted to patients with post-infectious glomerulonephritis, anti-neutrophil cytoplasmic antibodies-associated vasculitis, and anti-glomerular basement membrane disease. Most frequently, patients present with asymptomatic haematuria and proteinuria with or without reduced kidney function. All glomerulonephritis disorders can show periods of exacerbation, but disease flairs characteristically occur in patients with IgA nephropathy or C3 glomerulopathy. The gold standard for the diagnosis of a glomerulonephritis is a kidney biopsy, with a hallmark glomerular inflammation that translates into various histopathological patterns depending on the location and severity of the glomerular injury. Traditionally, glomerulonephritis was classified on the basis of the different histopathological patterns of injury. In the last few years, substantial progress has been made in unravelling the underlying causes and pathogenetic mechanisms of glomerulonephritis and a causal approach to the classification of glomerulonephritis is now favoured over a pattern-based approach. As such, glomerulonephritis can be broadly classified as immune-complex glomerulonephritis (including infection-related glomerulonephritis, IgA nephropathy, lupus nephritis, and cryoglobulinaemic glomerulonephritis), anti-neutrophil cytoplasmic antibodies-associated (pauci-immune) glomerulonephritis, anti-glomerular basement membrane glomerulonephritis, C3 glomerulopathy, and monoclonal immunoglobulin-associated glomerulonephritis. We provide an overview of the clinical presentation, pathology, and the current therapeutic approach of the main representative disorders in the spectrum of glomerulonephritis.

Automated Computational Detection of Disease Activity in ANCA-Associated Glomerulonephritis Using Raman Spectroscopy: A Pilot Study

Biospectroscopy offers the ability to simultaneously identify key biochemical changes in tissue associated with a given pathological state to facilitate biomarker extraction and automated detection of key lesions. Herein, we evaluated the application of machine learning in conjunction with Raman spectroscopy as an innovative low-cost technique for the automated computational detection of disease activity in anti-neutrophil cytoplasmic autoantibody (ANCA)-associated glomerulonephritis (AAGN). Consecutive patients with active AAGN and those in disease remission were recruited from a single UK centre. In those with active disease, renal biopsy samples were collected together with a paired urine sample. Urine samples were collected immediately prior to biopsy. Amongst those in remission at the time of recruitment, archived renal tissue samples representative of biopsies taken during an active disease period were obtained. In total, twenty-eight tissue samples were included in the analysis. Following supervised classification according to recorded histological data, spectral data from unstained tissue samples were able to discriminate disease activity with a high degree of accuracy on blind predictive modelling: F-score 95% for >25% interstitial fibrosis and tubular atrophy (sensitivity 100%, specificity 90%, area under ROC 0.98), 100% for necrotising glomerular lesions (sensitivity 100%, specificity 100%, area under ROC 1) and 100% for interstitial infiltrate (sensitivity 100%, specificity 100%, area under ROC 0.97). Corresponding spectrochemical changes in paired urine samples were limited. Future larger study is required, inclusive of assigned variables according to novel non-invasive biomarkers as well as the application of forward feature extraction algorithms to predict clinical outcomes based on spectral features.

ANCA Associated Vasculitis Subtypes: Recent Insights and Future Perspectives

The ANCA associated vasculitides (AAVs) affect a range of internal organs including ear nose and throat, respiratory tract, kidneys, skin and nervous system. They include granulomatosis with polyangiitis (GPA), eosinophilic granulomatosis with polyangiitis (EGPA) and microscopic polyangiitis (MPA). The AAVs are treated with high dose glucocorticoids, immunosuppressants, and targeted biological medications. Since the 1990s classification criteria for the AAVs have been based on clinical features, laboratory tests and basic imaging; an initiative to update the classification criteria incorporating newer tests, for example, anti-neutrophil cytoplasmic antibodies (ANCA) and novel imaging techniques will be published this year. There is also evidence for classification of patients based on ANCA subtype; those with anti-proteinase 3 antibodies (PR3) or anti-myeloperoxidase antibodies (MPO) have differences in response to treatment and clinical outcomes. An update is described within this review. The pathogenesis of AAV involves necrotizing inflammation of small to medium blood vessels involving multiple immunological pathways. We present an update on emerging evidence related to auto-antibodies, complement and lymphocyte pathways. This review describes emerging treatment regimens, including evidence for plasma exchange in severe disease and the inhibitor of the complement C5a receptor (C5aR) inhibitor, Avacopan. Lastly, patient reported outcomes are key secondary outcomes in randomised controlled trials and increasingly clinical practice, we report development in disease specific and glucocorticoid-specific PROs.

Kidney Histopathology Can Predict Kidney Function in ANCA-Associated Vasculitides with Acute Kidney Injury Treated with Plasma Exchanges

BACKGROUND

Data from the PEXIVAS trial challenged the role of plasma exchange (PLEX) in ANCA-associated vasculitides (AAV). We aimed to describe kidney biopsy from patients with AAV treated with PLEX, evaluate whether histopathologic findings could predict kidney function, and identify which patients would most benefit from PLEX.

METHODS

We performed a multicenter, retrospective study on 188 patients with AAV and AKI treated with PLEX and 237 not treated with PLEX. The primary outcome was mortality or KRT at 12 months (M12).

RESULTS

No significant benefit of PLEX for the primary outcome was found. To identify patients benefitting from PLEX, we developed a model predicting the average treatment effect of PLEX for an individual depending on covariables. Using the prediction model, 223 patients had a better predicted outcome with PLEX than without PLEX, and 177 of them had >5% increased predicted probability with PLEX compared with without PLEX of being alive and free from KRT at M12, which defined the PLEX-recommended group. Risk difference for death or KRT at M12 was significantly lower with PLEX in the PLEX-recommended group (-15.9%; 95% CI, -29.4 to -2.5) compared with the PLEX not recommended group (-4.8%; 95% CI, 14.9 to 5.3). Microscopic polyangiitis, MPO-ANCA, higher serum creatinine, crescentic and sclerotic classes, and higher Brix score were more frequent in the PLEX-recommended group. An easy to use score identified patients who would benefit from PLEX. The average treatment effect of PLEX for those with recommended treatment corresponded to an absolute risk reduction for death or KRT at M12 of 24.6%.

CONCLUSIONS

PLEX was not associated with a better primary outcome in the whole study population, but we identified a subset of patients who could benefit from PLEX. However, these findings must be validated before utilized in clinical decision making.

Different Types of ANCA Determine Different Clinical Phenotypes and Outcome in ANCA-Associated Vasculitis (AAV)

Aim

Accumulating evidence supports the use of antineutrophil cytoplasmic antibody (ANCA) type to classify different clinical entities. We aimed to evaluate whether the presence and type of ANCA determine different diseases, based on clinical phenotypes, renal involvement, and response to treatment.

Patients and Methods

Differences in terms of clinical manifestations, disease activity, laboratory parameters, and histology were recorded between patients with focal necrotizing glomerulonephritis (FNGN) due to myeloperoxidase (MPO-), proteinase 3-ANCA(+) [PR3-ANCA(+)], and ANCA(-) disease at time of diagnosis. Patients were treated with the same protocol and followed-up for 24 months, in a scheduled basis of every month for the first year and every 3 months for the second year. Primary end points were: (i) Combined end-stage renal disease (ESRD) and/or death and (ii) The presence of major or minor relapse during follow-up and secondary endpoint was the combination of ESRD and reduction of estimated glomerular filtration rate (eGFR) ≥ 50%.

Results

A total of 92 patients (M/F 39/53, mean age 59.1 ± 15 years) diagnosed with FNGN due to ANCA-associated vasculitis (AAV), 36 (39.1%) patients diagnosed with PR3-ANCA, 39 (42.4%) patients diagnosed with MPO-ANCA, and 17 (18.5%) patients diagnosed with ANCA(-) were included. Number of involved systems differed significantly between PR3-, MPO-ANCA, and ANCA(-), with only renal involvement in 3, 25.5, and 29% of patients, two systems involved in 33, 31, and 59% of patients, and > 3 systems involved in 64, 43.5, and 12% of patients, respectively (p = 0.002). Histology classification revealed focal, crescentic, mixed, and sclerotic type in 14, 64, 19, and 3% of PR3-ANCA(+), 8, 28, 18, and 46% of MPO-ANCA, and 41, 29, 6, and 24% of ANCA(-), respectively (p < 0.0001). Primary end point of ESRD ± Death was reached in 11 (30.6%), 16 (41%), and 6 (35.5%) patients with PR3-ANCA(+), MPO-ANCA(+), and ANCA(-), respectively (p = NS); similarly, ESRD± > 50% eGFR reduction in 8 (22.2%), 15 (38.5%), and 5 (29.4%) patients, respectively (p = NS), meaning that patients with MPO-ANCA(+) showed a propensity to decline renal function. Rate of relapse was increased in the presence of patients with PR3-ANCA(+), 14 (38.9%), 4 (11.8%), and 2 (10.3%) of patients with PR3-ANCA(+), MPO-ANCA(+), and ANCA(-), had at least one relapse during the two-year follow-up (p = 0.006).

Conclusion

Clinical phenotype and renal histology differ significantly between PR3-ANCA(+), MPO-ANCA(+), and ANCA(-) disease and FNGN; however, renal function outcome is similar, despite the increased rate of relapses in patients with PR3-ANCA(+).

Early Renal Recovery after the First Flare of Pauci-Immune Glomerulonephritis

INTRODUCTION

Renal involvement is a severe manifestation of antineutrophil cytoplasmic antibody-associated vasculitis. Patients often progress to end-stage renal disease. The potential for renal recovery after the first flare has seldom been studied. Our objectives were to describe the evolution of the estimated glomerular filtration rate (eGFR) and identify factors associated with the change in the eGFR between diagnosis and the follow-up at 3 months (ΔeGFRM0-M3).

METHODS

This was a retrospective study over the period 2003-2018 of incident patients in the Nord-Pas-de-Calais (France). The primary outcome was the ΔeGFRM0-M3.

RESULTS

One hundred and seventy-seven patients were included. The eGFR at 3 months was significantly higher than at diagnosis (mean ± standard deviation, 40 ± 24 vs. 28 ± 26 mL/min/1.73 m2, p < 0.001), with a ΔeGFRM0-M3 of 12 ± 19 mL/min/1.73 m2. The eGFR at 12 months was higher than at 3 months (44 ± 13 vs. 40 ± 24 mL/min/1.73 m2, p = 0.003). The factors significantly associated with the ΔeGFRM0-M3 in multivariate analysis were the percentage of cellular crescents and neurological involvement. The mean increase in the eGFR was 2.90 ± 0.06 mL/min/1.73 m2 for every 10-point gain in the percentage of cellular crescents.

CONCLUSIONS

Early renal recovery after the first flare of pauci-immune glomerulonephritis occurred mainly in the first 3 months of treatment. The percentage of cellular crescents was the main independent predictor of early renal recovery.

Prevalence of ANCA-associated vasculitis amid natural gas drilling sites in West Virginia

BACKGROUND

The epidemiology of ANCA-associated vasculitis (AAV) varies by ethnicity and region. Environmental exposure has been implicated in the pathophysiology of MPO-AAV. The aim of this study was to evaluate the epidemiology of AAV and explore a potential relationship with environmental factors in north central West Virginia.

METHODS

This is a retrospective cohort study of 212 patients diagnosed with AAV at West Virginia University and its affiliated hospitals from January 1, 1990 to December 31, 2019. We assessed prevalence of AAV over time according to patient's zip codes and counties. Silica exposure through natural gas extraction was considered as a possible environmental factor.

RESULTS

The proportion of patients with MPO-ANCA increased after 2010 (37.5% before 2010 vs 61% after 2010, p = 0.008). At the same time, the prevalence of AAV in Monongalia and surrounding counties has increased significantly after 2010 from 64.8 to 141.9 cases per million (p = 0.001). The increase in prevalence of AAV was primarily due to an increase in MPO-AAV (43 vs 101.7 cases per million before and after 2010, respectively, p = 0.028). During this time, the production of natural gas through fracking increased, rising more than tenfold after 2010 (p-value < 0.001). Heat mapping reveals that the increase in cases of AAV occurred in areas of increased fracking activity.

CONCLUSIONS

There was an increase in the prevalence of patients who were newly diagnosed with AAV over time in north central West Virginia. Further studies are required to ascertain the potential role of environmental exposure in the pathophysiology of AAV.

Metabolic Syndrome Severity Score, Comparable to Serum Creatinine, Could Predict the Occurrence of End-Stage Kidney Disease in Patients with Antineutrophil Cytoplasmic Antibody-Associated Vasculitis

This study investigated whether the metabolic syndrome (MetS) severity (MSSS) at diagnosis could predict poor outcomes during follow-up in antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) patients with MetS. The equation for the MSSS at diagnosis used in this study was developed and validated in Korean adults aged 20–59 years. The medical records of 261 patients with AAV were retrospectively reviewed, and finally, 36 AAV patients with MetS aged 20–59 years fulfilling the inclusion criteria were included in this study. All-cause mortality, relapse, end-stage kidney disease (ESKD), cerebrovascular accident, and cardiovascular disease were assessed as the poor outcomes of AAV. Their median age was 51.2 years and 36.1% were male. The MSSS was significantly correlated with age and serum albumin but not AAV-specific indices. Among the five poor outcomes, only ESKD showed a relatively significant area under the curve (area 0.696) in receiver operating characteristic curve analysis. In the multivariable Cox hazards model analysis, both serum creatinine (HR 3.033) and MSSS (HR = 2.221) were significantly associated with ESKD occurrence. When the cut-off of the MSSS for ESKD was set at 1.72, ESKD occurred more frequently in patients with MSSS ≥ 1.72 than in those with MSSS < 1.72 (75.0% versus 14.3%, p = 0.002). Furthermore, patients with MSSS ≥ 1.72 exhibited a significantly lower cumulative ESKD-free survival rate than those with MSSS < 1.72 (p = 0.001). MSSS at the time of AAV diagnosis independently predicted the occurrence of ESKD during follow-up in patients with AAV and MetS.

Comparative Histological Subtyping of Immune Cell Infiltrates in MPO-ANCA and PR3-ANCA Glomerulonephritis

Background

Acute kidney injury (AKI) is a common and severe complication of anti-neutrophil cytoplasmic antibodies (ANCA)-associated vasculitis (AAV), potentially leading to chronic kidney disease (CKD), end-stage renal disease (ESRD), or death. Pathogenic ANCAs, in particular proteinase 3 (PR3) and myeloperoxidase (MPO), trigger a deleterious immune response with intrarenal immune cell infiltration resulting in a pauci-immune necrotizing and crescentic glomerulonephritis (GN). However, a systematic analysis of intrarenal immune cell subtypes concerning neutrophils, eosinophils, plasma cells, and mononuclear cell infiltrates (macrophages, lymphocytes) in ANCA GN remains elusive. Therefore, we aimed to compare distinct immune cell infiltrates in association with clinicopathological findings in ANCA GN.

Methods

A total of 53 kidney biopsies with ANCA GN at the University Medical Center Göttingen were retrospectively analyzed. Histological infiltrates of neutrophils, eosinophils, plasma cells, and mononucleated cells (macrophages, lymphocytes) were quantified as a fraction of the total area of inflammation.

Results

Neutrophilic infiltrates were associated with glomerular necrosis and severe kidney injury in ANCA GN. Among tubulointerstitial lesions, intrarenal neutrophils correlated with interstitial inflammation, tubulitis, and inflammation in areas of interstitial fibrosis/tubular atrophy (IFTA), representing active inflammatory lesions. Concerning eosinophils, infiltrates were associated with severe kidney injury, interstitial inflammation, and cellular casts independent of glomerular lesions, implicating a distinct role in inflammation and damage in ANCA GN. Plasma cell infiltrates correlated with tubulitis and interstitial fibrosis and were associated with renal replacement therapy during the short-term disease course. Finally, mononuclear cell infiltrates correlated with severe kidney injury and active histopathological lesions (glomerular crescents, interstitial inflammation, tubulitis, inflammation, and tubulitis in areas of IFTA) besides chronic lesions (interstitial fibrosis and tubular atrophy) in ANCA GN. Interestingly, intrarenal subtypes of immune cell infiltrates differed in MPO-ANCA versus PR3-ANCA GN and were associated with distinct glomerular and tubulointerstitial lesions, implicating different pathogenic mechanisms of kidney injury in ANCA subtypes.

Conclusion

Our observations imply distinct pathomechanisms contributing to inflammation and renal injury in MPO vs. PR3-associated ANCA GN and potentially contribute to new therapeutic targets in specific ANCA subtypes.

Long-Term Renal Survival in Antineutrophil Cytoplasmic Antibody-Associated Glomerulonephritis With Complement C3 Deposition

Introduction

Recent studies have revealed the pivotal role of complement activation in the pathogenesis of antineutrophil cytoplasmic antibody–associated glomerulonephritis (ANCA-GN). This study investigated the clinicopathologic and prognostic significance of glomerular C3 deposition in the renal histopathology of patients with ANCA-GN.

Methods

We retrospectively identified 142 patients with ANCA-GN from 6 hospitals in Japan (2004–2020). C3 deposition was defined as C3 staining ≥1+ on a scale of 0 to 2+ using direct immunofluorescence (IF). The primary composite end points included a 30% reduction in estimated glomerular filtration rate (eGFR), end-stage kidney disease (ESKD), and death. We compared clinicopathologic features and long-term outcomes between patients with and without C3 deposition.

Results

C3 deposition was observed in 56 of 142 kidney biopsy samples (39.4%). Patients with C3 deposition had a lower serum C3 level (P = 0.002). During a median follow-up of 2.9 (interquartile range: 0.2–5.7) years, 69 events occurred and the cumulative event-free survival rate at 5 years was significantly lower in the C3-positive group than in the C3-negative group (log-rank: P = 0.002). In multivariable analysis, C3 deposition was significantly associated with the composite end points after adjusting for age, sex, baseline eGFR, serum C3 level, treatment, and the percentage of normal glomerulus, cellular crescents, global sclerosis, and interstitial damage (adjusted hazard ratio [HR] = 2.02, 95% confidence interval: 1.20–3.40, P = 0.008).

Conclusion

This study revealed that ANCA-GN patients with glomerular C3 deposition on IF had worse renal and overall survival rates.

The gut microbiome in microscopic polyangiitis with kidney involvement: common and unique alterations, clinical association and values for disease diagnosis and outcome prediction

Background

Microscopic polyangiitis (MPA) is an autoimmune disease characterized by frequent kidney involvement. Imbalance of intestinal flora has been found implicated in multiple immune-mediated disorders. However, the profiling and the role of the gut microbiome in MPA remains unclear.

Methods

We performed 16S rRNA amplicon sequencing on fecal samples from 71 MPA patients with kidney involvement (35 at incipient active stage, 36 at remissive stage) and 34 healthy controls (HCs). Microbial diversity and abundance were compared among the three cohorts. The correlation between altered microbes and clinical indices were investigated. Two random forest models based on the profiling of the gut microbiome were constructed for the diagnosis of MPA.

Results

Two α-diversity indices, including Simpson and Shannon index, were decreased in MPA patients (P<0.001), especially in those with active disease (P=0.001). β-diversity analysis showed biased microbial composition among the three groups. Genus Actinomyces and Streptococcus were more abundant in both MPA cohorts than those in HCs, while genus Subdoligranulum, Eubacterium hallii, Ruminococcaceae UCG013, Eubacterium ventriosum, Dorea and Butyricicoccus were more abundant in HCs than those in both MPA cohorts. All the 6 genera with decreased abundance belong to short-chain fatty acids (SCFA)-producing taxons. Besides, 1 and 2 operational taxonomic units (OTUs) were enriched in patients with active MPA who needed dialysis at sampling and in patients who progressed to end-stage renal disease during follow up, respectively. Furthermore, the model for diagnosis of MPA incorporated 6 OTU markers and achieved an AUC of 93.45% (95% CI, 88.15–98.74%). Similarly, the model for predicting disease activity incorporated 11 OTU markers and achieved an AUC of 90.71% (95% CI, 82.49–98.94%).

Conclusions

Alteration of intestinal flora existed in MPA patients with kidney involvement and was characterized by increased abundance of genus Actinomyces and Streptococcus and decreased abundance of 6 SCFA-producing genera. Gut microbial profiling combined with machining-learning methods showed potentials for diagnosing MPA and predicting disease activity.

Reappraisal of Renal Arteritis in ANCA-associated Vasculitis: Clinical Characteristics, Pathology, and Outcome

BACKGROUND

Renal involvement in ANCA-associated vasculitis (AAV) is associated with poor outcomes. The clinical significance of arteritis of the small kidney arteries has not been evaluated in detail.

METHODS

In a multicenter cohort of patients with AAV and renal involvement, we sought to describe the clinicopathologic characteristics of patients with AAV who had renal arteritis at diagnosis, and to retrospectively analyze their prognostic value.

RESULTS

We included 251 patients diagnosed with AAV and renal involvement between 2000 and 2019, including 34 patients (13.5%) with arteritis. Patients with AAV-associated arteritis were older, and had a more pronounced inflammatory syndrome compared with patients without arteritis; they also had significantly lower renal survival (P=0.01). In multivariable analysis, the ANCA renal risk score, age at diagnosis, history of diabetes mellitus, and arteritis on index kidney biopsy were independently associated with ESKD. The addition of the arteritis status significantly improved the discrimination of the ANCA renal risk score, with a concordance index (C-index) of 0.77 for the ANCA renal risk score alone, versus a C-index of 0.80 for the ANCA renal risk score plus arteritis status (P=0.008); ESKD-free survival was significantly worse for patients with an arteritis involving small arteries who were classified as having low or moderate risk, according to the ANCA renal risk score. In two external validation cohorts, we confirmed the incidence and phenotype of this AAV subtype.

CONCLUSIONS

Our findings suggest AAV with renal arteritis represents a different subtype of AAV with specific clinical and histologic characteristics. The prognostic contribution of the arteritis status remains to be prospectively confirmed.

Survival in ANCA-Associated Vasculitides in a Peruvian Center: 28 Years of Experience

AIM

The aim of this study was to identify demographic and clinical risk factors for mortality in patients with antineutrophil cytoplasmic antibodies-associated vasculitides (AAVs) in a Peruvian tertiary referral hospital.

METHODS

Medical records of patients with AAV according to classification criteria or diagnosed by an experienced rheumatologist, covering the period between January 1990 and December 2018, were reviewed. Granulomatosis with polyangiitis, microscopic polyangiitis, eosinophilic granulomatosis with polyangiitis, and renal-limited vasculitis were included. Potential predictors of mortality were demographic factors, clinical manifestations, antineutrophil cytoplasmic antibodies status, diagnosis, disease categorization, the 2009 Five Factor Score (FFS), and treatment. Cox regression models were used to determine the risk factors for mortality. Univariable and multivariable analyses using a backward selection method were performed.

RESULTS

One hundred ninety-six patients were included; female-to-male ratio was 2:1. The median (interquartile range) age at diagnosis and follow-up were 60.0 (51.0-68.0) and 4.8 (1.3-11.6) years, respectively. One hundred forty-eight patients (75.5%) had microscopic polyangiitis, 37 (18.9%) granulomatosis with polyangiitis, 5 (2.6%) eosinophilic granulomatosis with polyangiitis, and 6 (3.0%) renal-limited vasculitis. Overall survival rates at 1, 5, and 10 years were 83.4%, 68.2%, and 51.7%, respectively. Ocular involvement was protective (hazards ratio [HR], 0.36; 95% confidence interval [CI], 0.17-0.74; p = 0.006), whereas renal (HR, 2.09; 95% CI, 1.33-3.28; p = 0.001) and lung involvement (HR, 2.07; 95% CI, 1.31-3.28; p = 0.002) and the 2009 FFSs were predictive of mortality (2009 FFS = 1: HR, 2.46; 95% CI, 1.50-4.04; p < 0.001; 2009 FFS = 2: HR, 3.07; 95% CI, 1.54-6.10; p = 0.001; 2009 FFS = 3: HR, 13.29; 95% CI, 3.69-47.88; p < 0.001).

CONCLUSIONS

Ocular involvement was protective, whereas 2009 FFS ≥ 1 and renal and lung involvement were predictive factors of mortality in Peruvian AAV patients.

Effect of Tripterygium wilfordii polyglycoside tablets on serum inflammatory factors and T cells in patients with chronic nephritis

OBJECTIVE

Investigate the effect of Tripterygium wilfordii polyglycoside tablets on serum inflammatory factors and T cells in patients with chronic nephritis.

METHODS

A total of 89 patients with chronic nephritis were randomly divided into a control group (44 cases, treated with irbesartan hydrochlorothiazide combined with dipyridamole) and an observation group (45 cases, treated with Tripterygium wilfordii polyglycoside tablets based on irbesartan hydrochlorothiazide and dipyridamole like the control group). Patients in both groups were treated for two months. The renal function, inflammatory factors, the proportion of T lymphocyte subsets, and 24 h urinary protein quantification (24 h Upro) of patients with hemodialysis were compared between the two groups before and after treatment. The occurrence of adverse reactions was recorded.

RESULTS

SCR, BUN levels, 24 h Upro, serum hs-CRP, TNF-α, and IL-8 levels in the two groups after treatment were lower than those before treatment, and those of the observation group were lower than those of the control group (all P<0.05). After treatment, the CD4+ ratio and CD4+/CD8+ ratio of the two groups of patients increased, while the CD8+ ratio decreased. The changes in the observation group were greater than those in the control group (all P<0.05). There was no significant difference in the incidence of total adverse reactions between the two groups during treatment (P>0.05).

CONCLUSION

Treatment combined with Tripterygium wilfordii polyglycosides can significantly alleviate the inflammatory state of patients with chronic glomerulonephritis, reduce the level of proteinuria, and improve renal function. Tripterygium wilfordii polyglycosides can improve immune function of the body and has high safety.

ANCA Status or Clinical Phenotype - What Counts More?

PURPOSE OF REVIEW

There is ongoing debate concerning the classification of antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis. That is, whether classification should be based on the serotype (proteinase 3 (PR3)- or myeloperoxidase (MPO)-ANCA) or on the clinical phenotype (granulomatosis with polyangiitis (GPA) or microscopic polyangiitis (MPA)). To add clarity, this review focused on integration of the most recent literature.

RECENT FINDINGS

Large clinical trials have provided evidence that a serology-based risk assessment for relapses is more predictive than distinction based on the phenotype. Research conducted in the past decade indicated that a serology-based approach more closely resembles the genetic associations, the clinical presentation (i.e., lung involvement), biomarker biology, treatment response, and is also predicting comorbidities (such as cardiovascular death). Our review highlights that a serology-based approach could replace a phenotype-based approach to classify ANCA-associated vasculitides. In future, clinical trials and observational studies will presumably focus on this distinction and, as such, translate into a "personalized medicine."

Characterization of a Rat Model of Myeloperoxidase-Anti-Neutrophil Cytoplasmic Antibody-Associated Crescentic Glomerulonephritis

BACKGROUND/AIM

Necrotizing crescentic glomerulonephritis (GN) associated with anti-neutrophil cytoplasmic antibodies (ANCA) against myeloperoxidase (MPO) is a devastating disease that quickly progresses to kidney failure. Current therapies are broadly immunosuppressive and associated with adverse effects. We wanted to set up a model that could be suitable for testing narrowly targeted therapies.

METHODS

The model was constructed in male Wistar Kyoto rats through injections of human MPO (hMPO) and pertussis toxin, followed by a sub-nephritogenic dose of sheep anti-rat glomerular basement membrane (GBM) serum to boost the disease. Rats were monitored for 35 days. Rats given hMPO alone, saline, or human serum albumin with or without anti-GBM serum were also studied.

RESULTS

Rats receiving hMPO developed circulating anti-hMPO and anti-rat MPO antibodies. Challenging hMPO-immunized rats with the anti-GBM serum led to more glomerular neutrophil infiltration and MPO release, and severe haematuria, heavy proteinuria, and higher blood urea nitrogen than hMPO alone. Pauci-immune GN developed with crescents, affecting 25% of glomeruli. The majority of crescents were fibrocellular. Necrotizing lesions and Bowman capsule ruptures were detected. Cells double positive for claudin-1 (a marker of parietal epithelial cells [PECs]) and neural cell adhesion molecule (NCAM; progenitor PECs) were present in crescents. Double staining for NCAM and Ki-67 established proliferative status of progenitor PECs. Podocyte damage was associated with endothelial and GBM changes by electron microscopy. Monocyte/macrophages and CD4+ and CD8+ T cells accumulated in glomeruli and the surrounding area and in the tubulointerstitium. Lung haemorrhage also manifested.

CONCLUSION

This model reflects histological lesions of human ANCA-associated rapidly progressive GN and may be useful for investigating new therapies.

Efficacy of the fibrosis index for predicting end-stage renal disease in patients with antineutrophil cytoplasmic antibody-associated vasculitis

OBJECTIVE

Kidney involvement is a major manifestation of antineutrophil cytoplasmic antibody-associated vasculitis (AAV) and may progress to end-stage renal disease (ESRD), requiring renal replacement therapy. Unfortunately, there is no reliable kidney-specific index for predicting the progression of renal disease to ESRD. The fibrosis index (FI) reflects the degree of fibrosis in chronic liver disease. This study aimed to investigate whether the FI at the time of diagnosis could predict the development of ESRD in AAV patients.

METHODS

We retrospectively reviewed the medical records of 211 immunosuppressive drug-naïve AAV patients and extrapolated the cut-off FI value for predicting the development of ESRD using receiver operating characteristic curves. The associations between the FI and clinical outcomes, including mortality, relapse, and ESRD development, were determined.

RESULTS

Overall, 39 (18.5%) patients developed ESRD owing to the progression of AAV-associated renal disease. The median FI was higher in AAV patients with ESRD than in those without (1.61 vs 1.04; P = .001). The FI cut-off was 1.72. The incidence of ESRD was higher in patients with FI ≥ 1.72 at the time of diagnosis than in those with an FI < 1.72 at the time of diagnosis (relative risk: 4.655; 95% confidence interval: 2.242-9.662; P < .001). Kaplan-Meier survival analysis revealed that patients with an FI ≥ 1.72 at the time of diagnosis exhibited significantly lower ESRD-free survival rates than those with an FI < 1.72 at the time of diagnosis (P < .001).

CONCLUSION

FI ≥ 1.72 at the time of diagnosis may be an independent predictive marker for ESRD in AAV patients.

Anti-Neutrophil Cytoplasmic Antibody-Associated Glomerulonephritis and Malignancy: A Case of a Patient Diagnosed with Renal Failure and Pulmonary Carcinoma Concurrently

A 70-year-old man presented with proteinuria, microscopic hematuria, and an increased level of serum creatinine. A systemic workup revealed that the patient had bronchogenic carcinoma and anti-neutrophil cytoplasmic antibody (ANCA)-associated glomerulonephritis concurrently. Despite the increase in the cumulative number of publications on paraneoplastic glomerulopathies, an awareness of the link between cancer and ANCA-associated glomerulonephritis is lacking. We strongly recommend the accumulation of more cases similar to our own, thereby allowing us to clarify the management strategies as well as the nature of this disease condition more precisely.

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

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

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

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

Increasing incidence and improved survival in ANCA-associated vasculitis-a Danish nationwide study

BACKGROUND

Anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) carries a high risk of morbidity and mortality, with outcomes modified by treatment and an incidence that may be increasing. We examined temporal changes in incidence and mortality during 2000-15 using nationwide healthcare registries.

METHODS

Patients with incident AAV were identified using International Classification of Diseases Version 10 (ICD10) codes and grouped according to inclusion year (Period 1: 2000-04, Period 2: 2005-09, Period 3: 2010-15). Log link cumulative incidence regression adjusted for age, sex, renal function, cardiovascular disease, diabetes, hypertension and advanced disease severity were used to model survival.

RESULTS

We identified 1631 patients (52% male), corresponding to an incidence of 18.5 persons/million/year (Period 1: 15.1, Period 2: 18.5, Period 3: 21.4). The slope of incident serologic ANCA testing was steeper than that of AAV (P = 0.002). Mean [standard deviation (SD)] age was 60.2 (16.7) years and mean (SD) follow-up was 6.8 (4.7) years. A total of 571 (35%) patients died (5-year mortality of 22.1%), with an absolute risk ratio (ARR) for Periods 2 and 3 compared with Period 1 of 0.80 [confidence interval (CI) 0.65-0.98, P = 0.031] and 0.39 (CI 0.31-0.50, P < 0.001). About 274 patients developed end-stage renal disease (ESRD) [16.8% (Period 1: 23.3%, Period 2: 17.6%, Period 3: 12.5%)], with ARR decreasing over time: Period 2 0.61 (CI 0.42-0.87, P = 0.007) and Period 3 0.57 (CI 0.39-0.83, P = 0.003). The overall risk of death associated with ESRD or chronic kidney disease was 1.74 (CI 1.29-2.37, P < 0.001) and 1.58 (CI 1.21-2.07, P < 0.001).

CONCLUSIONS

Incidence of ANCA testing and AAV diagnosis increased over the test period. Falls over time in mortality and ESRD risk may relate to earlier diagnosis and changes in treatment practice.

The value of anti-neutrophil cytoplasmic antibodies (ANCA) testing for the diagnosis of ANCA-associated vasculitis, a systematic review and meta-analysis

The testing of anti-neutrophil cytoplasmic antibodies (ANCA) takes an important place in the diagnostic workup to ANCA-associated vasculitis (AAV). Nowadays, it is recommended to screen for the presence of PR3 and MPO specific antibodies first using immunoassay, without the need for ANCA measurement by indirect immunofluorescence (IIF). A literature search was performed to assess the diagnostic test value of ANCA IIF and PR3- and MPO-antibody immunoassay to diagnose AAV. This meta-analysis shows that the c-ANCA testing by IIF has a pooled sensitivity of 75.2% and a pooled specificity of 98.4%. For PR3-antibody immunoassay, the pooled sensitivity depended on the immunoassay method used, and ranged from 79.8% to 86.6%, whereas the pooled specificity ranged from 96.8% to 98.3%. For both p-ANCA IIF and MPO-antibody immunoassay (all methods) sensitivity varied considerably showing pooled values of respectively 46.3% and 58.1%, whereas respective pooled specificity was 91.4% and 95.6%. These findings support the 2017 international consensus that primary anti-PR3 and anti-MPO screening by immunoassay, based on superior immunoassay sensitivity without the need for IIF ANCA testing, improves the diagnostic workup of AAV.

Update on the Management of Respiratory Manifestations of the Antineutrophil Cytoplasmic Antibodies-Associated Vasculitides

Antibody-associated vasculitis comprises 3 small vessel vasculitis syndromes: granulomatosis with polyangiitis (GPA), microscopic polyangiitis (MPA), and eosinophilic polyangiitis (EGPA). This article outlines the major tracheobronchial and pulmonary parenchymal disease manifestations of GPA and MPA and their management, as well as relevant recent advances in the treatment of EGPA. Shared trends in the management of all 3 syndromes are: (1) a focus on glucocorticoid avoidance and (2) an increasing reliance on biologic agents. Evidence from randomized controlled trials and large cohort studies in support of these trends as well as ongoing research efforts are summarized.

Anti-neutrophil Cytoplasmic Antibodies (ANCA) as Disease Activity Biomarkers in a "Personalized Medicine Approach" in ANCA-Associated Vasculitis

PURPOSE OF REVIEW

ANCA-associated vasculitides (AAV) are a group of rare diseases characterized by blood vessel inflammation and the presence of circulating anti-neutrophil cytoplasmic antibodies recognizing proteinase-3 (PR3) (PR3-ANCA) or myeloperoxidase (MPO), MPO-ANCA.

RECENT FINDINGS

Historically, ANCAs have been used as biomarkers for disease associations and increases of ANCA levels as predictors of relapse in patients with AAV. In this review, we will summarize and highlight the most recent developments for using ANCA as predictive biomarkers and review some of the important disease-specific features in patients with AAV.

ANCA Renal Risk Score: is prediction of end-stage renal disease at baseline possible?

Despite improved overall prognosis of patients with ANCA-associated vasculitis (AAV), those presenting with impaired renal function remain at risk of developing end-stage renal disease (ESRD). In addition to its role in diagnosis, renal histology provides prognostic information that has permitted definition of subgroups with differing risks of ESRD. In this issue, Brix et al. have developed and validated a risk score to predict the probability of ESRD. Against a background of outcome prediction in AAV, this commentary assesses different approaches to histologic risk and to what extent they assist with decisions on patient management.