Julie Anne G. McGregor

Epitope specificity determines pathogenicity and detectability in ANCA-associated vasculitis

Anti-neutrophil cytoplasmic antibody-associated (ANCA-associated) small vessel necrotizing vasculitis is caused by immune-mediated inflammation of the vessel wall and is diagnosed in some cases by the presence of myeloperoxidase-specific antibodies (MPO-ANCA). This multicenter study sought to determine whether differences in ANCA epitope specificity explain why, in some cases, conventional serologic assays do not correlate with disease activity, why naturally occurring anti-MPO autoantibodies can exist in disease-free individuals, and why ANCA are undetected in patients with ANCA-negative disease. Autoantibodies from human and murine samples were epitope mapped using a highly sensitive epitope excision/mass spectrometry approach. Data indicated that MPO autoantibodies from healthy individuals had epitope specificities different from those present in ANCA disease. Importantly, this methodology led to the discovery of MPO-ANCA in ANCA-negative disease that reacted against a sole linear sequence. Autoantibodies against this epitope had pathogenic properties, as demonstrated by their capacity to activate neutrophils in vitro and to induce nephritis in mice. The confounder for serological detection of these autoantibodies was the presence of a fragment of ceruloplasmin in serum, which was eliminated in purified IgG, allowing detection. These findings implicate immunodominant epitopes in the pathology of ANCA-associated vasculitis and suggest that autoantibody diversity may be common to other autoimmune diseases.

Patients With Antineutrophil Cytoplasmic Antibody–Associated Vasculitis Have Defective Treg Cell Function Exacerbated by the Presence of a Suppression-Resistant Effector Cell Population

OBJECTIVE The development of pathogenic antineutrophil cytoplasmic antibodies (ANCAs) can result in systemic small vessel vasculitis. However, the breakdown in immune tolerance that results in the induction and persistence of ANCAs is not well understood. We undertook this study to test our hypothesis that abnormal T cell regulation is central to disease pathogenesis in patients with ANCA-associated vasculitis (AAV). METHODS Peripheral blood samples were obtained from 62 patients with AAV and 19 healthy controls for flow cytometric analysis of CD4+ T cell populations. Functional T cell studies were performed with fluorescence-activated cell sorted CD4+ T cell populations stimulated with anti-CD3/anti-CD28. RESULTS We demonstrated two separate abnormalities in T cell regulation in patients with AAV. First, we showed that the Treg cell frequency was increased in the peripheral blood of patients with active disease, but Treg cells from patients with AAV had decreased suppressive function. Treg cells from patients with active disease disproportionately used a FoxP3 isoform lacking exon 2, which might alter Treg cell function. Second, we identified a CD4+ T cell population with increased frequency that was resistant to Treg cell suppression, produced proinflammatory cytokines, and was antigen experienced. CONCLUSION AAV is associated with disruption of the suppressive Treg cell network and with increased frequency of a distinct proinflammatory effector T cell subset that comprises the majority of peripheral CD4+ T cells.

Adverse events and infectious burden, microbes and temporal outline from immunosuppressive therapy in antineutrophil cytoplasmic antibody-associated vasculitis with native renal function

BACKGROUND Disease control in anti-neutrophil cytoplasmic antibody (ANCA) associated vasculitis (AAV) with immunosuppression is effective but burdened by adverse events, especially infections. The study goal was to evaluate risks and types of infections in patients with AAV. METHODS Biopsy-proven AAV patients (diagnosed 1/1991-6/2011) followed in an inception cohort were evaluated for adverse events. Severe infections (requiring intravenous antibiotics, intensive care unit, or causing death) were recorded. Infection number was grouped as none, 1-2 or ≥3. Cox regression was used to estimate hazard ratios with 95% confidence intervals. RESULTS A total of 489 patients (median age 59; 47% female, 55% myeloperoxidase-ANCA) were followed for 2.8 years (median). At 1, 2 and 5 years cumulative incidence of infection was 51, 58 and 65% and severe infection was 22, 23 and 26%. Pulmonary and upper respiratory infections were most common (42 and 30% ever experienced each, respectively), highest in the first 3 months. Staphylococcus aureus was most frequently seen among positive cultures (41%, 78 S. aureus/192 total positive cultures), and only one Pneumocystis jiroveci pneumonia (6 weeks into treatment). All-cause death in 12 months was associated with infections (% deaths: 0 infections 3%; 1-2 infections 10%, ≥3 infections 13%, P = 0.002). Controlling for age, sex and kidney function, patients with severe infections were 4.2 times more likely to die within 12 months (95% CI 2.0-8.7; P = 0.001). CONCLUSIONS More infections increase the risk of a severe infection which increases risk of all-cause mortality. Respiratory and S. aureus infections are dominant. Targeted prophylactic therapy could decrease morbidity.

Trends in Long-Term Outcomes Among Patients With Antineutrophil Cytoplasmic Antibody–Associated Vasculitis With Renal Disease

It is still not clear how advances in the management of antineutrophil cytoplasmic antibody (ANCA)–associated vasculitis (AAV) have impacted long‐term outcomes. We undertook this study to examine changes over 25 years in long‐term clinical outcomes, including the impact of renal function at diagnosis (a potential marker of time to disease detection) and the duration of cyclophosphamide use in AAV patients with renal involvement.

Trends in long‐term outcomes among patients with ANCA‐associated vasculitis with renal disease

It is still not clear how advances in the management of antineutrophil cytoplasmic antibody (ANCA)–associated vasculitis (AAV) have impacted long‐term outcomes. We undertook this study to examine changes over 25 years in long‐term clinical outcomes, including the impact of renal function at diagnosis (a potential marker of time to disease detection) and the duration of cyclophosphamide use in AAV patients with renal involvement.

Rituximab as an immunosuppressant in antineutrophil cytoplasmic antibody-associated vasculitis

BACKGROUND Rituximab has been used in antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) since 2003. Our objective was to describe outcomes and adverse events following rituximab since that time in an inception cohort. METHODS Patients with AAV (diagnosed 1991-2012) who received rituximab (n = 120) were evaluated and incidence per person-year (PPY) with 95% confidence interval was calculated for relapse and infections. Time to remission and relapse by number of rituximab infusions given per treatment course (≤2 versus >2) and by ever having been exposed to cyclophosphamide were compared using Kaplan-Meier curves. Rituximab-treated patients were characterized in comparison with AAV patients treated with cyclophosphamide but not exposed to rituximab (n = 351) using Fishers exact or rank tests. RESULTS Rituximab resulted in 86% achieving remission and 41% having a subsequent relapse in a median of 19 months (range 9-29). Time to remission and relapse were similar between rituximab infusion courses (≤2 versus >2; remission P = 0.86 and relapse P = 0.78, respectively). Incidence of relapse was 0.22 PPY (0.14, 0.31) and of severe infection was 0.12 PPY (0.08, 0.24). Time to relapse was shorter in those never exposed to cyclophosphamide (n = 20): 50% by 8 months versus 50% by 24 and 30 months for those with prior or concurrent exposure to cyclophosphamide (n = 100). Compared with those who never received rituximab, rituximab-treated patients were younger (P < 0.001), more likely to have granulomatosis with polyangiitis (P = 0.001) and had more upper airway (P = 0.01) and less kidney involvement (P = 0.007). CONCLUSIONS Rituximab is beneficial when prescribed outside of a trial setting. Response to treatment and relapse is similar regardless of infusion number. Rituximab without cyclophosphamide may result in a shorter time to relapse supporting combination of these therapies.

Clinical characteristics and outcome of pauci-immune glomerulonephritis in African Americans

OBJECTIVES Pauci-immune glomerulonephritis is rare in African Americans (AA) and the clinical presentation and treatment outcomes of vasculitis have not been well described. METHODS We identified patients who were 2-92 years of age between 1983 and 2011 with a diagnosis of biopsy-proven pauci-immune glomerulonephritis (GN) at any point during their disease course. Comparing AA to Caucasian patients, we examined demographics, clinical features at presentation, treatment and outcomes of relapse, end-stage renal disease (ESRD), and death. RESULTS Of the 672 patients, 75 were AA with the remainder being Caucasian. Compared to Caucasians, disease onset in AA was at an earlier age (52 vs. 57 years, p = 0.05) and was more often myeloperoxidase (MPO)-anti-neutrophil cytoplasmic antibody (ANCA) positive (71% vs. 54%, p = 0.01). AA patients had a shorter median time between onset of symptoms and biopsy compared to Caucasians [median (IQR): 0.23 (0.00, 1.22) months vs. 0.66 (0.00, 3.62) months, p = 0.003]. Median [Interquartile range (IQR)] follow-up in months was 28 (5, 52) in AA and 26 (10, 55) in Caucasian patients. Median estimated glomerular filtration rate was similar at presentation (21 vs. 22 ml/min/m(2)). Both groups had similar induction treatment regimens. There was less favorable treatment response among AA compared to Caucasians for initial treatment resistance (28% vs. 18%, p = 0.05) and complete remission (72% vs. 82%, p = 0.05). There were no differences in the number of renal relapses or number of deaths between the 2 groups. Overall, in multivariable analyses controlling for age, race, ANCA type, and entry serum creatinine, there were not differences by race in treatment response, renal relapse, ESRD, or death over the entire time of follow-up. CONCLUSIONS AA patients with pauci-immune GN are younger and more often MPO-ANCA positive compared to Caucasians. Despite a shorter time to diagnosis for AA patients, there were no differences compared to Caucasians in treatment response, ESRD, renal relapse, or death rates by race over the entire duration of follow-up.

Healthcare utilization and expenditures for United States Medicare beneficiaries with systemic vasculitis

OBJECTIVE The Medicare federal insurance program is the most common United States insurer of patients with systemic vasculitis (SV). We compared healthcare utilization and expenditures for Medicare beneficiaries with versus without SV. METHODS This national, retrospective study used 2010 claims and enrollment data for a 100% cohort of Medicare Part A and B beneficiaries with ≥1 claim including a diagnosis for a form of SV (n = 176,498), and a randomly selected group of non-SV beneficiaries (n = 46,561). Outcomes included annual counts of events in 16 categories of medical services (e.g., inpatient stays, physician visits, tests, and imaging events), and total annual Medicare and patient medical expenditures. We used linear regression with bootstrapped standard errors to compare utilization and expenditures by SV status, before and after matching on age and sex. Prescription drug fills and expenditures for SV (n = 95,157) and non-SV (n = 24,992) beneficiaries with Part D drug benefits were also compared. RESULTS After matching, Medicare spent

ANCA epitope specificity determines pathogenicity, detectability and clinical predictive value

11,004 more per patient in 2010 for medical services, and

Vasculitis: The elusive optimal induction strategy for vasculitis

773 more on prescription drugs, for SV versus non-SV beneficiaries. SV beneficiaries spent