A Retrospective Evaluation of the Treatment Effects of Rituximab in Patients with Progressive and Symptomatic Fibrosing Mediastinitis.

RATIONALE: Fibrosing mediastinitis is an uncommon fibro-inflammatory condition without established or effective medical therapies. Infiltrating B-lymphocytes are commonly present, and progressive fibrosis compromises mediastinal structures including blood vessels and airways resulting in significant morbidity and mortality. OBJECTIVE: To evaluate the benefits and side effects of Rituximab in patients with progressive and symptomatic fibrosing mediastinitis. METHODS: We treated 22 patients (median age 35 years, range: 15-68 years, 45% female) with metabolically active, progressive fibrosing mediastinitis with off-label rituximab. Additionally, patients were put on pneumocystis and antifungal prophylaxis when immunosuppressed with rituximab. Modeling of longitudinal treatment response based on changes in relative lesion volume from baseline was performed retrospectively using functional data analysis; time-to-event modeling was performed to estimate treatment response rates based on a >30% reduction in pre-treatment volume. MEASUREMENTS: The primary end points were lack of disease progression and change in mediastinal lesion volume by CT (evaluated retrospectively). MAIN RESULTS: No patient experienced disease progression after rituximab therapy. Median clinical follow-up was 42 months (range: 7 to 94) and imaging follow-up 21 months (range: 7 to 62). 82% of patients had confirmed histoplasmosis-associated fibrosing mediastinitis. After rituximab treatment a 49.6% (95% CI = [17.5%, 64.4%]) mean estimated decrease in pre-treatment lesion volume was observed at 24 months. The estimated objective treatment response rate was 47.9% (95% CI = [26.7%, 70.3%]). CONCLUSION: This observational study suggests that Rituximab is well tolerated and potentially effective therapy in a cohort of patients with symptomatic and progressive FM.

Treatment of Antineutrophil Cytoplasmic Antibody-Associated Vasculitis With Diffuse Alveolar Hemorrhage With Avacopan.

OBJECTIVE: Avacopan, an activated complement factor 5 receptor antagonist, has been approved as adjunct therapy for severe active antineutrophil cytoplasmic antibody-associated vasculitis (AAV). Current evidence supports the management of AAV presenting with diffuse alveolar hemorrhage (DAH) by administering glucocorticoids combined with either rituximab or cyclophosphamide in addition to supportive care. The role of avacopan in patients with DAH as a primary severe disease manifestation of AAV has not been well established. Furthermore, concerns remain regarding timely access to avacopan, the best glucocorticoid tapering regimen, and long-term efficacy and safety of the drug. We sought to identify clinical features and outcomes of patients presenting with DAH secondary to AAV who received avacopan in addition to glucocorticoids and rituximab or cyclophosphamide. METHODS: We performed a retrospective cohort study of all consecutive patients presenting with DAH as part of active severe granulomatosis with polyangiitis or microscopic polyangiitis. Demographic and clinical characteristics were collected at presentation and follow-up. RESULTS: Fifteen patients met inclusion criteria and were observed for a median time of 17 weeks (interquartile range [IQR] 6-37 weeks) after initiation of avacopan. Patients were predominantly female and White, had never smoked, and were a median age of 66 years (IQR 52-72 years) at diagnosis. The majority had newly diagnosed severe AAV with renal involvement. Three patients progressed to respiratory failure. The timing of avacopan introduction and patterns of glucocorticoid tapers varied widely in this cohort. Two serious adverse events related to infection were observed, including one opportunistic infection leading to the patient's death, although neither was directly attributed to avacopan administration. CONCLUSION: We describe the clinical course of patients who presented with the severe AAV disease manifestation of DAH and received avacopan as adjunct therapy. Most patients achieved remission during follow-up, and adverse events, including infection, were observed.

Granulomatosis With Polyangiitis With And Without Antineutrophil Cytoplasmic Antibodies: A Case-Control Study.

BACKGROUND: ANCA-negative GPA remains a diagnosis of exclusion. Clinical differences between patients with ANCA-negative vs ANCA-positive GPA have not been analyzed in sizable case-control studies, and the effects of ANCA-seroconversion from negative to positive are not well documented. METHODS: A single-center, sex, and age matched case-control study evaluated ANCA-negative vs ANCA-positive GPA from January 1, 1996, to December 31, 2015. Patients who experienced seroconversion were the subject of a case crossover study. Clinical data and outcomes were retrieved from electronic medical records. RESULTS: ANCA-negative GPA was identified in 110 patients; 65% were female; median age was 55 (IQR 39-65) years at time of diagnosis. Disease severity was milder in ANCA-negative GPA (BVAS/WG = 2 vs 6, p< 0.001). Mucous membranous/eye manifestations were more frequent in ANCA-negative GPA. General symptoms, pulmonary, and renal involvement were more frequent in ANCA-positive GPA. Patients with ANCA-positive GPA relapsed more over 60 months (21.8% vs.9.1%, p= 0.009) compared with ANCA-negative GPA and had shorter time to event (p= 0.043). Patients with general manifestations, BMI > 30kg/m2 and necrotizing granulomatous inflammation were more likely to relapse. The 16 patients who seroconverted into ANCA-positive during follow-up had higher mean BVAS/WG at time of diagnosis (p< 0.001) and increased incidence of relapses (p= 0.004) after seroconversion. Necrotizing granulomatous inflammation on biopsy in ANCA-negative GPA patients was identified as a risk factor for subsequent seroconversion to ANCA-positivity. CONCLUSION: Patients with ANCA-negative GPA have milder disease and a lower frequency of relapse than those with ANCA-positive GPA. ANCA appearance portended higher disease severity and an increased frequency of relapses.

Pulmonary function in patients with ANCA-associated vasculitis.

BACKGROUND AND AIM: Although pulmonary manifestations occur frequently in ANCA-associated vasculitis (AAV), empirical evidence of their impact on pulmonary function is scarce. This study analyzed pulmonary function test (PFT) data from a large cohort of patients with AVV. Results were correlated with findings from diagnostic imaging and disease activity. METHODS: Data from AAV patients with PFTs performed between 2008 and 2018 were extracted retrospectively from the database of a tertiary vasculitis center. Demographic and disease characteristics, imaging data and follow-up results were assessed and compared to PFT results. RESULTS: The final analysis encompassed 147 patients. The mean time between first PFT and follow-up was 7.0 ± 11.0 months. In Granulomatosis with Polyangiitis (GPA), forced expiratory vital capacity (FVCex, p<0.001), residual volume (RV, p<0.001) and the diffusion capacity of carbon oxide (TLCO, p=0.003) were significantly reduced compared to the reference value of 100% predicted. There was no significant difference between patients with or without pulmonary manifestations. In Microscopic Polyangiitis (MPA), reductions of FVCex (p<0.001), TLC (p=0.005), and TLCO (p=0.003) were observed. In Eosinophilic Granulomatosis with Polyangiitis (EGPA), total airway resistance (RAWtot, p=0.024) and RV (p=0.009) were significantly elevated and TLCO was reduced (p=0.014). Interstitial lung disease (ILD) is associated with a decline of FVCex (-15.7%, p=0.0028), TLC (-26.5%, p<0.001), RV (-38.9%, p=0.023) and TLCO (-29.1%, p=0.007). Significant differences were neither detected between first PFT and follow-up examination, nor between patients with active versus inactive disease. CONCLUSIONS: AAV patients presented with characteristic alterations in PFTs according to their respective pulmonary and/or airway manifestations. These results did not change over time and were independent from vasculitis activity.

Predictive Factors of Renal Recovery and Progression to End-Stage Kidney Disease in Patients With Antineutrophil Cytoplasmic Autoantibody-Associated Vasculitis With Severe Kidney Disease.

Introduction: A significant number of patients with antineutrophil cytoplasmic antibodies (ANCA)- associated vasculitis (AAV) with glomerulonephritis (AAV-GN) still progress to end-stage kidney disease (ESKD, estimated glomerular filtration rate [eGFR] <15 ml/min per 1.73 m2) despite advances in remission-induction treatment. Methods: This is a retrospective cohort study on myeloperoxidase (MPO)-ANCA or proteinase 3 (PR3)-ANCA positive patients with AAV (microscopic polyangiitis, MPA; or granulomatosis with polyangiitis, GPA) and eGFR <15 ml/min per 1.73 m2 or ESKD at presentation. Renal recovery, dialysis discontinuation, and persistence of ESKD after standard remission-induction, with or without the use of plasma exchange (PLEX) were analyzed. Results: We analyzed 166 patients with biopsy-proven active AAV-GN and eGFR <15 ml/min per 1.73 m2 at the time of diagnosis. Patients received glucocorticoids with cyclophosphamide (CYC) (n = 84) or with rituximab (RTX) (n = 72) for remission-induction, and 49 received PLEX. The predictors of renal recovery were erythrocyte sedimentation rate, serum creatinine (SCr) at diagnosis, and minimal or mild chronicity changes. We further analyzed 71 patients who started dialysis with or without PLEX within 4 weeks of AAV-GN diagnosis. The predictors of dialysis discontinuation were minimal chronicity changes in kidney biopsy at diagnosis (odds ratio = 6.138; 95% confidence interval [CI]: 1.389-27.118; P = 0.017). Predictors of persistence of ESKD within 12 months included higher SCr at diagnosis (incidence rate ratio [IRR] = 1.086; 95% CI: 1.005-1.173; P = 0.037), and moderate (IRR = 3.797; 95% CI: 1.090-13.225; P = 0.036), or severe chronicity changes in kidney biopsy (IRR = 5.883; 95% CI: 1.542-22.439; P =0.009). Conclusion: In our cohort, kidney recovery, dialysis discontinuation, and persistence of ESKD in patients with AAV-GN and eGFR <15 ml/min per 1.73 m2 depended on SCr and histologic findings on kidney biopsies at the time of diagnosis and was not affected by the addition of PLEX.

Proteinase 3-specific antineutrophil cytoplasmic antibody-associated vasculitis.

Proteinase 3 (PR3)-specific antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis is one of two major ANCA-associated vasculitis variants and is pathogenically linked to granulomatosis with polyangiitis (GPA). GPA is characterised by necrotising granulomatous inflammation that preferentially affects the respiratory tract. The small vessel vasculitis features of GPA are shared with microscopic polyangiitis. Necrotising granulomatous inflammation of GPA can lead to PR3-ANCA and small vessel vasculitis via activation of neutrophils and monocytes. B cells are central to the pathogenesis of PR3-ANCA-associated vasculitis. They are targeted successfully by remission induction and maintenance therapy with rituximab. Relapses of PR3-ANCA-associated vasculitis and toxicities associated with current standard therapy contribute substantially to remaining mortality and damage-associated morbidity. More effective and less toxic treatments are sought to address this unmet need. Advances with cellular and novel antigen-specific immunotherapies hold promise for application in autoimmune disease, including PR3-ANCA-associated vasculitis. This Series paper describes the inter-related histopathological and clinical features, pathophysiology, as well as current and future targeted treatments for PR3-ANCA-associated vasculitis.

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.

Alveolar Hemorrhage in Antineutrophil Cytoplasmic Antibody-Associated Vasculitis: Results of an International Randomized Controlled Trial (PEXIVAS).

Rationale: Diffuse alveolar hemorrhage (DAH) is a life-threatening manifestation of antineutrophil cytoplasmic antibody-associated vasculitis (AAV). The PEXIVAS (Plasma Exchange and Glucocorticoids in Severe Antineutrophil Cytoplasmic Antibody-Associated Vasculitis) (NCT00987389) trial was the largest in AAV and the first to enroll participants with DAH requiring mechanical ventilation. Objectives: Evaluate characteristics, treatment effects, and outcomes for patients with AAV with and without DAH. Methods: PEXIVAS randomized 704 participants to plasma exchange (PLEX) or no-PLEX and reduced or standard-dose glucocorticoids (GC). DAH status was defined at enrollment as no-DAH, nonsevere, or severe (room air oxygen saturation of ⩽ 85% as measured by pulse oximetry, or use of mechanical ventilation). Measurements and Main Results: At enrollment, 191 (27.1%) participants had DAH (61 severe, including 29 ventilated) and were younger, more frequently relapsing, PR3 (proteinase 3)-ANCA positive, and had lower serum creatinine but were more frequently dialyzed than participants without DAH (n = 513; 72.9%). Among those with DAH, 8/95 (8.4%) receiving PLEX died within 1 year versus 15/96 (15.6%) with no-PLEX (hazard ratio, 0.52; confidence interval [CI], 0.21-1.24), whereas 13/96 (13.5%) receiving reduced GC died versus 10/95 (10.5%) with standard GC (hazard ratio, 1.33; CI, 0.57-3.13). When ventilated, ventilator-free days were similar with PLEX versus no-PLEX (medians, 25; interquartile range [IQR], 22-26 vs. 22-27) and fewer with reduced GC (median, 23; IQR, 20-25) versus standard GC (median, 26; IQR, 25-28). Treatment effects on mortality did not vary by presence or severity of DAH. Overall, 23/191 (12.0%) with DAH died within 1 year versus 34/513 (6.6%) without DAH. End-stage kidney disease and serious infections did not differ by DAH status or treatments. Conclusions: Patients with AAV and DAH differ from those without DAH in multiple ways. Further data are required to confirm or refute a benefit of PLEX or GC dosing on mortality. Original clinical trial registered with www.clinicaltrials.gov (NCT00987389).

Urine and Plasma Complement Ba Levels During Disease Flares in Patients With Antineutrophil Cytoplasmic Autoantibody-Associated Vasculitis.

Introduction: Although the alternative complement pathway has been implicated in the pathogenesis of antineutrophil cytoplasmic autoantibody (ANCA)-associated vasculitis (AAV), the specific nature of its involvement is unclear. This study measured levels of urine and plasma complement fragment Ba at multiple time points in a group of patients with AAV. Methods: The complement fragment Ba was measured by enzyme-linked immunosorbent assay in serial urine and plasma samples from 21 patients with AAV who developed a renal flare, 19 who developed a nonrenal flare, and 20 in long-term remission. Urine Ba levels were corrected for urine creatinine concentration. Changes in Ba levels were modeled using mixed linear-effect models. A logistic regression model was fit to predict a renal flare using Ba levels at the time of flare versus the nonrenal flare and long-term remission groups. Results: Data from 60 patients with AAV were used for this analysis; 53% were male, 93% were White, and 74% had antiproteinase3-ANCA. Urine Ba levels increased at renal flare (P < 0.001) but remained stable during a nonrenal flare or long-term remission. Plasma Ba levels were stable over time in all groups. Urine Ba levels predicted a renal flare with an area under the curve of 0.76 (P < 0.001), with a cutoff of 12.53 ng/mg urine creatinine yielding a sensitivity of 76.2% and a specificity of 68.4%. Conclusion: Urine Ba levels, but not plasma Ba levels, are increased at the time of a renal flare in AAV, suggesting intrarenal complement activation and highlighting the potential use of this biomarker for surveillance of active renal vasculitis.

Mayo Clinic consensus report on membranous nephropathy: proposal for a novel classification.

Membranous nephropathy (MN) is a pattern of injury caused by autoantibodies binding to specific target antigens, with accumulation of immune complexes along the subepithelial region of glomerular basement membranes. The past 20 years have brought revolutionary advances in the understanding of MN, particularly via the discovery of novel target antigens and their respective autoantibodies. These discoveries have challenged the traditional classification of MN into primary and secondary forms. At least 14 target antigens have been identified, accounting for 80%-90% of cases of MN. Many of the forms of MN associated with these novel MN target antigens have distinctive clinical and pathologic phenotypes. The Mayo Clinic consensus report on MN proposes a 2-step classification of MN. The first step, when possible, is identification of the target antigen, based on a multistep algorithm and using a combination of serology, staining of the kidney biopsy tissue by immunofluorescence or immunohistochemistry, and/or mass spectrometry methodology. The second step is the search for a potential underlying disease or associated condition, which is particularly relevant when knowledge of the target antigen is available to direct it. The meeting acknowledges that the resources and equipment required to perform the proposed testing may not be generally available. However, the meeting consensus was that the time has come to adopt an antigen-based classification of MN because this approach will allow for accurate and specific MN diagnosis, with significant implications for patient management and targeted treatment.

Mayo Clinic Consensus Report on Membranous Nephropathy: Proposal for a Novel Classification.

Membranous nephropathy (MN) is a pattern of injury caused by autoantibodies binding to specific target antigens, with accumulation of immune complexes along the subepithelial region of glomerular basement membranes. The past 20 years have brought revolutionary advances in the understanding of MN, particularly via the discovery of novel target antigens and their respective autoantibodies. These discoveries have challenged the traditional classification of MN into primary and secondary forms. At least 14 target antigens have been identified, accounting for 80%-90% of cases of MN. Many of the forms of MN associated with these novel MN target antigens have distinctive clinical and pathologic phenotypes. The Mayo Clinic consensus report on MN proposes a 2-step classification of MN. The first step, when possible, is identification of the target antigen, based on a multistep algorithm and using a combination of serology, staining of the kidney biopsy tissue by immunofluorescence or immunohistochemistry, and/or mass spectrometry methodology. The second step is the search for a potential underlying disease or associated condition, which is particularly relevant when knowledge of the target antigen is available to direct it. The meeting acknowledges that the resources and equipment required to perform the proposed testing may not be generally available. However, the meeting consensus was that the time has come to adopt an antigen-based classification of MN because this approach will allow for accurate and specific MN diagnosis, with significant implications for patient management and targeted treatment.

Clinical features, risk factors, and outcomes of diffuse alveolar hemorrhage in antiphospholipid syndrome: A mixed-method approach combining a multicenter cohort with a systematic literature review.

BACKGROUND: Antiphospholipid syndrome (APS) is a systemic autoimmune disease clinically associated with thrombotic and obstetric events. Additional manifestations have been associated with APS, like diffuse alveolar hemorrhage (DAH). We aimed to summarize all the evidence available to describe the presenting clinical features, their prognostic factors, and short- and long-term outcomes. METHODS: We performed a mixed-method approach combining a multicenter cohort with a systematic literature review (SLR) of patients with incident APS-associated DAH. We described their clinical features, treatments, prognostic factors, and outcomes (relapse, mortality, and requirement of mechanical ventilation [MV]). Kaplan-Meier methods were used to estimate relapse and mortality rates, and Cox and logistic regression models were used to assess the factors associated as appropriate. RESULTS: We included 219 patients with incident APS-associated DAH (61 from Mayo Clinic and 158 from SLR). The median age was 39.5 years, 51% were female, 29% had systemic lupus erythematosus, and 34% presented with catastrophic APS (CAPS). 74% of patients had a history of thrombotic events, and 26% of women had a history of pregnancy morbidity; half of the patients had a history of thrombocytopenia, and a third had valvulopathy. Before DAH, 55% of the patients were anticoagulated. At DAH onset, 65% of patients presented hemoptysis. The relapse rate was 47% at six months and 52% at one year. Triple positivity (HR 4.22, 95% CI 1.14-15.59) was associated with relapse at six months. The estimated mortality at one and five years was 30.3% and 45.8%. Factors associated with mortality were severe thrombocytopenia (< 50 K/µL) (HR 3.10, 95% CI 1.39-6.92), valve vegetations (HR 3.22, 95% CI 1.14-9.07), CAPS (HR 3.80, 95% CI 1.84-7.87), and requirement of MV (HR 2.22, 95% CI 1.03-4.80). Forty-two percent of patients required MV on the incident DAH episode. Patients presenting with severe thrombocytopenia (OR 6.42, 95% CI 1.77-23.30) or CAPS (OR 4.30, 95% CI 1.65-11.16) were more likely to require MV. CONCLUSION: APS-associated DAH is associated with high morbidity and mortality, particularly when presenting with triple positivity, thrombocytopenia, valvular involvement, and CAPS.

Large vessel involvement in antineutrophil cytoplasmic antibody-associated vasculitis.

OBJECTIVES: Anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) is currently categorized under the small vessel vasculitides. There is limited knowledge about large vessel involvement in AAV (L-AAV), mainly described in case reports and small series. L-AAV can involve temporal arteries (TA-AAV), aorta (A-AAV), and periaortic soft tissue (PA-AAV). We sought to characterize the features of patients with L-AAV. METHODS: Patients older than 18 years at diagnosis of TA-AAV, A-AAV and PA-AAV seen at the Mayo Clinic, Rochester between January 1, 2000, and December 31, 2021, were identified through a proprietary medical text search algorithm. Patients were included if diagnosed with L-AAV, fulfilled 2022 ACR/EULAR classification criteria for GPA, MPA, or EGPA, had positive ANCA test results, and had more than one outpatient or inpatient visit. RESULTS: The study cohort consists of 36 patients with L-AAV. Of those, 23 had p-ANCA and/or MPO-ANCA; 13 had c-ANCA and/or PR3-ANCA. Mean (SD) age at AAV diagnosis was 63.4 (12.79); 20 (56%) were male. Seventeen patients had TA-AAV, 10 had A-AAV and 9 had PA-AAV. Most patients (n = 25, 69%) were diagnosed with large vessel vasculitis and AAV within a one-year timespan. Twenty-five (69%) patients had histopathologic confirmation of AAV diagnosis in a location other than temporal artery, aorta, or periaortic soft tissue. Glucocorticoids (36/36), rituximab (19/36), and methotrexate (18/36) were the most frequent treatments. CONCLUSIONS: This is the largest single-center cohort of patients with L-AAV to date. AAV can involve large arteries, albeit infrequent. AAV-targeted therapy should be considered in patients with L-AAV.

The Association Between Age at Diagnosis and Disease Characteristics and Damage in Patients With ANCA-Associated Vasculitis.

OBJECTIVE: This study examined the relationship between age at diagnosis and disease characteristics and damage in patients with antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV). METHODS: Analysis of a prospective longitudinal cohort of patients with granulomatosis with polyangiitis (GPA), microscopic polyangiitis (MPA), and eosinophilic GPA (EGPA) in the Vasculitis Clinical Research Consortium (2013-2021). Disease cohorts were divided by age at diagnosis (years): children (<18), young adults (18-40), middle-aged adults (41-65), and older adults (>65). Data included demographics, ANCA type, clinical characteristics, Vasculitis Damage Index (VDI) scores, ANCA Vasculitis Index of Damage (AVID) scores, and novel disease-specific and non-disease-specific damage scores built from VDI and AVID items. RESULTS: Analysis included data from 1020 patients with GPA/MPA and 357 with EGPA. Female predominance in GPA/MPA decreased with age at diagnosis. AAV in childhood was more often GPA and proteinase 3-ANCA positive. Children with GPA/MPA experienced more subglottic stenosis and alveolar hemorrhage; children and young adults with EGPA experienced more alveolar hemorrhage, need for intubation, and gastrointestinal involvement. Older adults (GPA/MPA) had more neurologic manifestations. After adjusting for disease duration, medications, tobacco, and ANCA, all damage scores increased with age at diagnosis for GPA/MPA (P < 0.001) except the disease-specific damage score, which did not differ (P = 0.44). For EGPA, VDI scores increased with age at diagnosis (P < 0.009), whereas all other scores were not significantly different. CONCLUSION: Age at diagnosis is associated with clinical characteristics in AAV. Although VDI and AVID scores increase with age at diagnosis, this is driven by non-disease-specific damage items.

Proprotein convertase subtilisin/kexin type 6 (PCSK6) is a likely antigenic target in membranous nephropathy and nonsteroidal anti-inflammatory drug use.

Drugs are an important secondary cause of membranous nephropathy (MN) with the most common drugs associated with MN being nonsteroidal anti-inflammatory drugs (NSAIDs). Since the target antigen in NSAID-associated MN is not known, we performed laser microdissection of glomeruli followed by mass spectrometry (MS/MS) in 250 cases of PLA2R-negative MN to identify novel antigenic targets. This was followed by immunohistochemistry to localize the target antigen along the glomerular basement membrane and western blot analyses of eluates of frozen biopsy tissue to detect binding of IgG to the novel antigenic target. MS/MS studies revealed high total spectral counts of a novel protein Proprotein Convertase Subtilisin/Kexin Type 6 (PCSK 6) in five of the 250 cases in the discovery cohort. A validation cohort using protein G immunoprecipitation, MS/MS, and immunofluorescence detected PCSK6 in eight additional cases. All cases were negative for known antigens. Ten of 13 cases had a history of heavy NSAID use with no history available in one case. The mean serum creatinine and proteinuria at kidney biopsy were 0.93 ± 0.47 mg/dL and 6.5 ± 3.3 gms/day, respectively. Immunohistochemistry/immunofluorescence showed granular staining for PCSK6 along the glomerular basement membrane, and confocal microscopy showed co-localization of IgG and PCSK6. IgG subclass analysis in three cases revealed codominance of IgG1 and IgG4. Western blot analysis using eluates from frozen tissue showed IgG binding to PCSK6 in PCSK6-associated but not in PLA2R-positive MN. Thus, PCSK6 may be a likely novel antigenic target in MN in patients with prolonged NSAID use.

Neutrophil extracellular trap formation in anti-neutrophil cytoplasmic antibody-associated and large-vessel vasculitis.

Levels of neutrophil extracellular traps (NETs) were measured in plasma of healthy controls (HC, n = 30) and patients with granulomatosis with polyangiitis (GPA, n = 123), microscopic polyangiitis (MPA, n = 61), Takayasu's arteritis (TAK, n = 58), and giant cell arteritis (GCA, n = 68), at times of remission or activity and correlated with levels of the platelet-derived thrombospondin-1 (TSP-1). Levels of NETs were elevated during active disease in patients with GPA (p < 0.0001), MPA (p = 0.0038), TAK (p < 0.0001), and GCA (p < 0.0001), and in remission for GPA, p < 0.0001, MPA, p = 0.005, TAK, p = 0.03, and GCA, p = 0.0009. All cohorts demonstrated impaired NET degradation. Patients with GPA (p = 0.0045) and MPA (p = 0.005) had anti-NET IgG antibodies. Patients with TAK had anti-histone antibodies (p < 0.01), correlating with presence of NETs. Levels of TSP-1 were increased in all patients with vasculitis, and associated with NET formation. NET formation is a common process in vasculitides. Targeting NET formation or degradation could be potential therapeutic approaches for vasculitides.

PLEX in AAV-GN: insights from the meta-analysis results and impact on remission induction treatment recommendations.

The risk of progression to end-stage kidney disease (ESKD) in patients with antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) and glomerulonephritis (AAV-GN) remains high. At 5 years of follow-up, 14-25% of patients will evolve to ESKD, suggesting that kidney survival is not optimized in patients with AAV. The addition of plasma exchange (PLEX) to standard remission induction has been the standard of care, particularly in patients with severe renal disease. However, there is still some debate regarding which patients benefit from PLEX. A recently published meta-analysis concluded that the addition of PLEX to standard remission induction in AAV probably reduced the risk of ESKD at 12 months and that PLEX was associated with an estimated absolute risk reduction for ESKD at 12 months of 16.0% for those at high risk or with a serum creatinine >5.7 mg/dl (high certainty of important effects). These findings were interpreted as supportive of offering PLEX to patients with AAV and a high risk of progression to ESKD or requiring dialysis and are making their way into societies recommendations. However, the results of the analysis can be debated. We provide an overview on the meta-analysis as an attempt to guide the audience through how the data were generated, to comment on our interpretation of the results and to explain why we feel uncertainty remains. In addition, we would like to provide insights in two questions that we believe are very relevant to consider when addressing the role of PLEX: the role of kidney biopsy findings in the decision making of whom might benefit from PLEX and the impact of novel treatments (i.e. complement factor 5a inhibitors) in avoiding progression to ESKD at 12 months. The treatment of patients with severe AAV-GN is complex and further studies that include only patients at high risk of progression to ESKD are needed.

Vitamin D status in ANCA-associated vasculitis.

Objective: Vitamin D might participate in the pathogenesis of several immune-mediated diseases, but few related data are available for ANCA-associated vasculitis (AAV). In this study, we analysed the association between vitamin D status and disease in patients with AAV. Methods: Serum levels of 25(OH)D2/ 3 were measured in 125 randomly selected patients with AAV [granulomatosis with polyangiitis (n = 50), eosinophilic granulomatosis with polyangiitis (n = 50) or microscopic polyangiitis (n = 25)] enrolled in the Vasculitis Clinical Research Consortium Longitudinal Studies at the time of enrolment and a subsequent relapse visit. Sufficient, insufficient and deficient vitamin D status were defined as 25(OH)D3 levels >30, 20-30 and ˂20 ng/ml, respectively. Results: Seventy of 125 patients (56%) were female, with a mean age of 51.5 (16) years at diagnosis; 84 (67%) were ANCA positive. Mean 25(OH)D was 37.6 (16) ng/ml, with vitamin D deficiency in 13 (10.4%) and insufficiency in 26 (20.8%). In univariate analysis, lower vitamin D status was associated with male sex (P = 0.027) and disease activity (P = 0.047). In univariate and multivariate analyses, deficient vitamin D status was associated with disease activity (P = 0.015). Mean 25(OH)D status in the 21 patients with a subsequent relapse did not differ between baseline and relapse visit [37.8 (16) vs 38.0 (10) ng/ml, respectively; P = 0.92]. Conclusion: Most patients with AAV have sufficient 25(OH)D levels, although those with lower vitamin D status were more likely to be male and to have active disease. Whether optimization of vitamin D status alters disease manifestations or activity in AAV remains to be determined. Trial Registration: Vasculitis Clinical Research Consortium (VCRC) Longitudinal Study (LS), NCT00315380, https://clinicaltrials.gov/ct2/show/NCT00315380.