Caroline E. Jennette

Predictors of Relapse and Treatment Resistance in Antineutrophil Cytoplasmic Antibody–Associated Small-Vessel Vasculitis

Context Patients with antineutrophil cytoplasmic autoantibody (ANCA)associated small-vessel vasculitis sometimes experience relapses and resistance to glucocorticoid and cyclophosphamide treatment. Contribution This study followed 350 patients with ANCA-associated vasculitis for a median of 49 months. Of 258 patients attaining remission, 109 (42%) relapsed. Upper or lower respiratory tract disease and proteinase-3 ANCA seropositivity were associated with increased risk for relapse. Of 334 treated patients, 77 (23%) had progressive disease despite treatment. Severe kidney disease, black ethnicity, and female sex were associated with an increased risk for treatment resistance. Cautions The participants were primarily selected on the basis of their condition being identified by renal biopsy. The Editors Antineutrophil cytoplasmic antibody (ANCA)associated small-vessel vasculitis includes microscopic polyangiitis, Wegener granulomatosis, the ChurgStrauss syndrome, and renal-limited vasculitis (ANCA-associated glomerulonephritis) (1, 2). The cornerstone of treatment for ANCA-associated vasculitis includes induction therapy with pulse corticosteroids and the prompt institution of daily oral glucocorticoids and cyclophosphamide (3-6). Approximately 85% of patients achieve remission with this therapy (5), but 11% to 57% of patients have a relapse (7-11). Some relapses are severe, resulting in worsening end-organ damage. Most relapses respond to therapy, but patients are subjected to additional immunosuppressive or cytotoxic drugs. Fear of relapsing disease has impelled physicians to prescribe prolonged maintenance therapies in most patients. Because 43% to 89% of patients may never have a disease relapse (7-11), use of long-term immunomodulating therapy often presents unnecessary risks and may well outweigh the benefits of preventing relapse. Little is known regarding predictors for relapse; identification of these risk factors would conceivably allow maintenance immunomodulatory therapy to be tailored to patients at high risk while sparing others unnecessary exposure to these drugs. Over the course of almost 2 decades, we recruited a large cohort of patients with ANCA-associated glomerulonephritis and vasculitis. From this sample, we sought to ascertain the following: Which patients were more likely to be resistant to treatment; which patients were more likely to progress to end-stage kidney disease; the potential to determine which patients were more likely to relapse; the impact of relapse on long-term outcome; the correlation between length of immunosuppressive therapy and the likelihood of relapse; and the viability of discontinuing immunosuppressive therapy in patients who have attained remission. Methods Patient Sample and Definitions Patients were eligible for this study if they had biopsy-proven vasculitis (diagnosed between 1985 and 2003) with positive ANCA determination by immunofluorescence microscopy or antigen-specific enzyme-linked immunosorbent assay (12); the patients were also required to be followed by physicians of the Glomerular Disease Collaborative Network (GDCN). The GDCN and a subset of the cohort were previously described elsewhere (4, 7), but the cohort was expanded to evaluate predictors of relapse. We used the University of North Carolina (UNC) Nephropathology Laboratory, which evaluates more than 1500 renal biopsies each year, to recruit participants for the GDCNs registry of patients with ANCA-associated vasculitis. All patients with a native kidney biopsy diagnosis of pauci-immune necrotizing and crescentic glomerulonephritis with or without granulomatous inflammation were eligible to enroll in the registry (n= 639). Patients were invited to give informed consent to participate through their treating nephrologist. We then collected medical records dating back to the initial diagnosis of ANCA-associated vasculitis. A total of 307 patients (48% of eligible participants) with a biopsy-proven diagnosis were enrolled in this study. An additional 59 (9%) patients signed consent to participate but were deemed ineligible because of negative ANCA test results or overlapping disease. Another 43 patients who had not undergone renal biopsy were recruited through the multidisciplinary UNC Vasculitis Clinic and through other GDCN nephrologists who work in collaboration with other medical specialists to care for patients with ANCA-associated vasculitis. Estimates of potentially eligible patients without a kidney biopsyproven diagnosis were not available because no centralized service exists to evaluate nonrenal biopsy tissue. Initial biopsy diagnosis, whatever the organ, was used as each patients start date in the registry. Detailed information on duration of symptoms before biopsy diagnosis was not always described in medical records and therefore was not available for analysis in this study. The Committee on the Protection of Human Subjects at UNC approved this study. Patients in the cohort received clinically indicated care from their primary nephrologists, who were affiliated with 63 different GDCN private practice offices (1 to 12 nephrologists per office) and 5 academic medical centers, including UNC. Therapeutic interventions and frequency of clinical evaluations were not determined by protocol. Physicians were instructed to update GDCN records for patients on a yearly basis; follow-up calls and written reminders were provided if information was not received. Consequently, patient follow-up did not vary substantially across clinics. Patients were categorized as having cytoplasmic ANCA, antiproteinase-3 (anti-PR3) ANCA, or both, or perinuclear ANCA, anti-myeloperoxidase (anti-MPO) ANCA, or both. Patients having only perinuclear ANCA were required to have a negative antinuclear antibody test. Categories of ANCA-associated vasculitis included Wegener granulomatosis, microscopic polyangiitis, and renal-limited disease (1, 2). The single patient with the ChurgStrauss syndrome was included with the microscopic polyangiitis group. Organ involvement was determined by biopsy or by previously described criteria (4, 7). For example, lung involvement was considered likely in the presence of hemoptysis; pulmonary hemorrhage; respiratory failure; or radiographic proof of infiltrates, nodules, or cavities without evidence of infection. Upper respiratory tract disease was considered likely with clinical or radiographic studies revealing sinusitis, otitis media, nasal crusting, or subglottic disease. Treatment categories were determined by the first therapy regimen used at diagnosis (corticosteroids alone or in combination with cyclophosphamide, as previously described) (3). In brief, induction therapy was typically initiated with 3 daily pulses of methylprednisolone (7 mg/kg of body weight per day) followed by daily oral prednisone. Prednisone therapy was started at a dose of 1 mg/kg per day for the first month and was tapered over 3 to 4 months. Cyclophosphamide was administered by intravenous pulse (0.5 to 1 g/m2 per month) or orally (1 to 2 mg/kg per day). Other immunosuppressive regimens included azathioprine, mycophenolate mofetil, and cyclosporine, usually after completion of induction therapy. The duration of therapy with various immunosuppressive medications was recorded. Patients were considered to be treated if they received any immunosuppressive therapy, regardless of duration. Medical records were reviewed on an ongoing basis. Drs. Falk and Nachman determined the outcomes, which included treatment resistance, remission while receiving therapy, remission without therapy, relapse, and end-stage kidney disease (4, 7). Treatment resistance was defined as progressive decline in kidney function with persistence of active urine sediment, or new or persisting extrarenal manifestations of vasculitis despite immunosuppressive therapy. Resistance to therapy was determined at least 1 month after the start of treatment. Remission was defined as stabilization or improvement of kidney function as measured by serum creatinine levels and resolution of hematuria and other manifestations of systemic vasculitis for more than 1 month. Remission without therapy was defined as remission while receiving only 7.5 mg of corticosteroids per day or less. Relapse could only occur in patients who reached remission (with or without therapy). Relapse was defined as vasculitic signs or symptoms in any organ system, as previously described (4, 7). Histopathologic renal evaluations included assessment of disease activity, chronicity, and vascular sclerosis. Scores ranging from 0 to 4 were used to designate degrees of glomerular necrosis, cellular crescents, neutrophil infiltration, capillary wall thickening, glomerular hypercellularity, and interstitial leukocytes; the sum of these scores was used to grade overall renal activity (range, 0 to 24). Chronicity was quantified by the sum of the scores (0 to 4 for each) for glomerular sclerosis, fibrotic crescents, interstitial fibrosis, and tubular atrophy (range, 0 to 16). Vascular sclerosis was scored from 0 to 4. The 4-variable Modification of Diet in Renal Disease equation (13, 14) was used to estimate glomerular filtration rate (GFR). Improvement or decline in GFR of 8 mL/min or more over 4 months was considered a clinically significant change in renal function. Statistical Analyses Logistic regression was used to assess factors associated with treatment resistance. A time-to-event analysis was not used because actual time to resistance is not known and because outcomes occurred within a short time. Results were expressed as odds ratios with 95% CIs. KaplanMeier estimators were used to estimate median survival times and probability of survival without end-stage kidney disease (15, 16). Cause-specific proportional hazards models were used to study, as competing risks, the 2 mutually exclusive outcomes of time to relapse (active disease outcome) and time to end-stage kidney disease

Classification of antineutrophil cytoplasmic autoantibody vasculitides: the role of antineutrophil cytoplasmic autoantibody specificity for myeloperoxidase or proteinase 3 in disease recognition and prognosis.

OBJECTIVE To compare the usefulness of 3 currently used classification systems in predicting the outcomes of treatment resistance, disease relapse, end-stage renal disease (ESRD), and death in patients with antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV). METHODS Three classification systems were applied to 502 patients with biopsy-proven AAV: 1) the Chapel Hill Consensus Conference (CHCC) definition with categories for granulomatosis with polyangiitis (GPA) (Wegeners), microscopic polyangiitis (MPA), and kidney-limited disease; 2) the European Medicines Agency (EMA) system with categories for GPA and MPA; and 3) classification based on ANCA with specificity for myeloperoxidase (MPO ANCA) versus ANCA with specificity for proteinase 3 (PR3 ANCA). Outcomes included treatment resistance, relapse, ESRD, and death. Proportional hazards models were compared between systems using an information-theoretic approach to rank models by predictive fit. Hazard ratios (HRs) with 95% confidence intervals (95% CIs) and P values are reported. RESULTS ANCA specificity was predictive of relapse, with PR3 ANCA-positive patients almost twice as likely to relapse as those with MPO ANCA (HR 1.89 [95% CI 1.33-2.69], P = 0.0004), and ANCA specificity had the best predictive model fit (model rank 1) compared to the CHCC and EMA systems. The CHCC and EMA systems did not predict relapse. By ANCA specificity, categories of GPA, MPA, and kidney-limited disease did not distinguish differences in probability of relapse-free survival. None of the systems predicted treatment resistance, ESRD, or death. CONCLUSION ANCA specificity independently predicts relapse among patients with AAV with renal disease. Classification and diagnostic systems that incorporate ANCA specificity, such as PR3 ANCA-positive MPA and MPO ANCA-positive MPA, provide a more useful tool than the clinical pathologic category alone for predicting relapse.

Association of Silica Exposure with Anti–Neutrophil Cytoplasmic Autoantibody Small-Vessel Vasculitis: A Population-Based, Case-Control Study

Anti-neutrophil cytoplasmic autoantibodies (ANCA) are associated with a category of small-vessel vasculitis (SVV) with frequent glomerulonephritis. The goal of this study was to evaluate the association of lifetime silica exposure with development of ANCA-SVV, with particular attention to exposure dosage, intensity, and time since last exposure. A southeastern United States, population-based, case-control study was conducted. Case patients had ANCA-SVV with pauci-immune crescentic glomerulonephritis. Population-based control subjects were frequency-matched to case patients by age, gender, and state. Jobs were assessed in a telephone interview. Silica exposure scores incorporated exposure duration, intensity, and probability for each job and then were categorized as none, low/medium, or high lifetime exposure. Logistic regression models were used to estimate adjusted odds ratios (OR) and 95% confidence intervals (CI). Silica exposure was found in 78 (60%) of 129 case patients and in 49 (45%) of 109 control subjects. There was no increased risk for disease from low/medium exposure relative to no exposure (OR 1.0; 95% CI 0.4 to 2.2) but increased risk with high exposure (OR 1.9; 95% CI 1.0 to 3.5; P = 0.05). Crop harvesting was associated with elevated risk (OR 2.5; 95% CI 1.1 to 5.4; P = 0.03). However, both agricultural and traditional occupational sources contributed to the cumulative silica exposure scores; therefore, the overall effect could not be attributed to agricultural exposures alone. There was no evidence of decreasing by duration of time since last exposure. High lifetime silica exposure was associated with ANCA-SVV. Exposure to silica from specific farming tasks related to harvesting may be of particular importance in the southeastern United States. Interval of time since last exposure did not influence development of ANCA-SVV.

Venous Thromboembolism in Patients with Membranous Nephropathy

BACKGROUND AND OBJECTIVES The aims of this study were to determine the frequency of venous thromboembolic events in a large cohort of patients with idiopathic membranous nephropathy and to identify predisposing risk factors. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS We studied patients with biopsy-proven membranous nephropathy from the Glomerular Disease Collaborative Network (n=412) and the Toronto Glomerulonephritis Registry (n=486) inception cohorts. The cohorts were pooled after establishing similar baseline characteristics (total n=898). Clinically apparent and radiologically confirmed venous thromboembolic events were identified. Potential risk factors were evaluated using multivariable logistic regression models. RESULTS Sixty-five (7.2%) subjects had at least one venous thromboembolic event, and this rate did not differ significantly between registries. Most venous thromboembolic events occurred within 2 years of first clinical assessment (median time to VTE = 3.8 months). After adjusting for age, sex, proteinuria, and immunosuppressive therapy, hypoalbuminemia at diagnosis was the only independent predictor of a venous thromboembolic event. Each 1.0 g/dl reduction in serum albumin was associated with a 2.13-fold increased risk of VTE. An albumin level <2.8 g/dl was the threshold below which risk for a venous thromboembolic event was greatest. CONCLUSIONS We conclude that clinically apparent venous thromboembolic events occur in about 7% of patients with membranous nephropathy. Hypoalbuminemia, particularly <2.8 g/dl, is the most significant independent predictor of venous thrombotic risk.

DRB1*15 Allele Is a Risk Factor for PR3-ANCA Disease in African Americans

Anti-neutrophil cytoplasmic autoantibody (ANCA) disease rarely occurs in African Americans and risk factors for the disease in this population are unknown. Here, we genotyped MHC class II alleles and found that, among African Americans, those with proteinase 3-ANCA (PR3-ANCA) had 73.3-fold higher odds of having HLA-DRB1*15 alleles than community-based controls (OR 73.3; 95% CI 9.1 to 591). In addition, a disproportionate number of African American patients carried the DRB1*1501 allelic variant of Caucasian descent rather than the DRB1*1503 allelic variant of African descent. Among Caucasians, those with PR3-ANCA had 2.2-fold higher odds of carrying DRB1*1501 than controls (OR 2.2; 95% CI 1.2 to 4.0). A validation study supported by the Vasculitis Clinical Research Consortium confirmed the strong association between the DRB1*15 allele and PR3-ANCA disease, among African Americans. Furthermore, we found that DRB1*1501 protein binds with high affinity to amino acid sequences of sense-PR3, purportedly an antigenic epitope, and to the amino acid sequence complementary to this epitope in vitro. Peptides of sense-PR3 and complementary-PR3 also bound to TNF-α-induced surface expression of DRB1*1501 on peripheral neutrophils. Taken together, these data suggest HLA-DRB1*15 alleles contribute to the pathogenesis of PR3-ANCA disease.

Glucocorticoids and Relapse and Infection Rates in Anti-Neutrophil Cytoplasmic Antibody Disease

BACKGROUND AND OBJECTIVES The optimal course of glucocorticoid therapy in anti-neutrophil cytoplasmic autoantibody (ANCA) disease is unknown. This cohort study evaluates effects of glucocorticoid therapy duration on patient outcomes and adverse events. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS This study assessed 147 patients diagnosed between January 1, 2000 and January 1, 2009 who were treated with glucocorticoids and cyclophosphamide. Patients with end stage kidney disease at presentation, treatment resistance, or who had died within 6 months were excluded. Patients were divided into three groups: 0, 5, or >5 mg prednisone daily at 6 months after therapy initiation. The latter two groups were combined for assessment of adverse events. Wilcoxon rank sum, Kruskal-Wallis, or Fishers exact tests were used for between-group comparisons. Time to relapse was evaluated by the Kaplan-Meier method with log-rank test for comparison. RESULTS There were no differences between groups in ANCA specificity, serum creatinine, frequency of risk factors for relapse, or length of therapy with immunosuppressants. Length of glucocorticoid therapy had no impact on time to relapse (hazard ratio, 0.69 [95% confidence interval (CI), 0.23-2.02]; 1.01, [95% CI, 0.57-1.81] for the 5-mg and >5-mg groups, respectively), relapse-free survival, end stage kidney disease, or death. Patients receiving glucocorticoids beyond 6 months had significantly higher incidence of infections (0.64 infections per person-year versus 0.39, P<0.0001) and a marginally significant higher frequency of new-onset diabetes mellitus (odds ratio, 2.03; 95% CI, 0.94-4.38). CONCLUSIONS Glucocorticoid therapy beyond 6 months is associated with a significantly greater risk of infections but not a significantly decreased risk of relapse.

The clinical course of ANCA small-vessel vasculitis on chronic dialysis

Antineutrophil cytoplasmic autoantibody (ANCA)-associated small-vessel vasculitis frequently affects the kidney. Here we describe the rates of infection, disease relapse, and death in patients with ANCA small-vessel vasculitis before and after end-stage renal disease (ESRD) in an inception cohort study and compare them to those of patients with preserved renal function. All patients had biopsy-proven ANCA small-vessel vasculitis. Fishers exact tests and Wilcoxon rank sum tests were used to compare the characteristics by ESRD status. ESRD follow-up included time on dialysis with transplants censored. Over a median follow-up time of 40 months, 136 of 523 patients reached ESRD. ESRD was associated with new-onset ANCA small-vessel vasculitis in 51% of patients, progressive chronic kidney disease without active vasculitis in 43%, and renal relapse in 6% of patients. Relapse rates of ANCA small-vessel vasculitis, reported as episodes/person-year, were significantly lower on chronic dialysis (0.08 episodes) compared with the rate of the same patients before ESRD (0.20 episodes) or with patients with preserved renal function (0.16 episodes). Infections were almost twice as frequent among patients with ESRD on maintenance immunosuppressants and were an important cause of death. Given the lower risk of relapse and higher risk of infection and death, we suggest that immunosuppression be geared to patients with ESRD who present with active vasculitis.

High Basal Activity of the PTPN22 Gain-of-Function Variant Blunts Leukocyte Responsiveness Negatively Affecting IL-10 Production in ANCA Vasculitis

Consequences of expression of the protein tyrosine phosphatase nonreceptor 22 (PTPN22) gain-of-function variant were evaluated in leukocytes from patients with anti-neutrophil cytoplasmic autoantibody (ANCA) disease. The frequency of the gain-of-function allele within the Caucasian patient cohort was 22% (OR 1.45), compared to general American Caucasian population (16.5%, p = 0.03). Examination of the basal phosphatase activity of PTPN22 gain-of-function protein indicated persistently elevated activity in un-stimulated peripheral leukocytes, while basal activity was undetectable in leukocytes from patients without the gain-of-function variant. To examine consequences of persistently high PTPN22 activity, the activation status of ERK and p38 MAPK were analyzed. While moderate levels of activated ERK were observed in controls, it was undetectable in leukocytes expressing PTPN22 gain-of-function protein and instead p38MAPK was up-regulated. IL-10 transcription, reliant on the ERK pathway, was negatively affected. Over the course of disease, patients expressing variant PTPN22 did not show a spike in IL-10 transcription as they entered remission in contrast to controls, implying that environmentally triggered signals were blunted. Sustained activity of PTPN22, due to the gain-of-function mutation, acts as a dominant negative regulator of ERK activity leading to blunted cellular responsiveness to environmental stimuli and expression of protective cytokines.