Susan L. Hogan

Clinical course of anti-neutrophil cytoplasmic autoantibody-associated glomerulonephritis and systemic vasculitis

OBJECTIVES To determine the spectrum of clinical manifestations in patients with anti-neutrophil cytoplasmic autoantibody (ANCA)-associated glomerulonephritis; to determine renal and patient survival in these patients; to compare survival among patients treated with corticosteroids alone, corticosteroids plus intravenous cyclophosphamide or corticosteroids plus oral cyclophosphamide; and to assess the correlation of disease manifestations and treatment response with ANCA subtypes and serial autoantibody titers. DESIGN Inception cohort study; mean follow-up of 24 months. SETTING Collaborative network of 120 university and private practice nephrologists (The Glomerular Disease Collaborative Network). PARTICIPANTS Seventy patients with ANCA and pauci-immune necrotizing and crescentic glomerulonephritis, of whom 59 were treated with either corticosteroids alone (14 patients), corticosteroids plus oral cyclophosphamide (30 patients), or corticosteroids plus intravenous cyclophosphamide (15 patients). MAIN RESULTS Of the 70 patients, 18 had renal-limited disease (idiopathic crescentic glomerulonephritis); 15, nonpulmonary extrarenal disease consistent with polyarteritis nodosa; and 37, pulmonary disease consistent with Wegener granulomatosis or alveolar capillaritis. There were overlapping manifestations of disease between patients with autoantibodies producing a cytoplasmic pattern and patients with autoantibodies producing a perinuclear pattern; however, the perinuclear pattern occurred more frequently in patients with renal-limited disease. Renal and patient survival was 75% at 24 months, and no difference in survival was seen between patients with renal-limited disease and those with systemic disease. No differences in survival were seen between patients treated with oral cyclophosphamide and those treated with intravenous cyclophosphamide; however, the comparative data from patients treated with corticosteroids alone were inconclusive. In general, autoantibody titers correlated with response to treatment and disease activity, but there were exceptions. CONCLUSIONS Patients with ANCA have various forms of necrotizing vascular inflammation, ranging from renal-limited disease to widespread systemic vasculitis, including polyarteritis nodosa and Wegener granulomatosis. Oral corticosteroids with either oral or intravenous cyclophosphamide appear to be equally effective therapy for ANCA-associated glomerulonephritis.

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

Effect of ACE inhibitors in diabetic and nondiabetic chronic renal disease: A systematic overview of randomized placebo-controlled trials

Clinical trials have shown the beneficial effects of angiotensin-converting enzyme (ACE) inhibitors in delaying the progression of diabetic renal disease. There is less evidence from primary clinical trials of nondiabetic renal disease. We performed an updated meta-analysis to determine the efficacy of ACE inhibitors in slowing the progression of renal disease over a broad range of functional renal impairment. We included published and unpublished randomized, placebo-controlled, parallel trials with at least 1 year of follow-up available from January 1970 to June 1999. In nine trials of subjects with diabetic nephropathy and microalbuminuria, the relative risk for developing macroalbuminuria was 0.35 (95% confidence interval [CI], 0.24 to 0.53) for individuals treated with an ACE inhibitor compared with placebo. In seven trials of subjects with overt proteinuria and renal insufficiency from a variety of causes (30% diabetes, 70% nondiabetes), the relative risk for doubling of serum creatinine concentration or developing end-stage renal disease was 0.60 (95% CI, 0.49 to 0.73) for individuals treated with an ACE inhibitor compared with placebo. Treatment of individuals with chronic renal insufficiency with ACE inhibitors delays the progression of disease compared with placebo across a spectrum of disease causes and renal dysfunction.

Predictors of treatment resistance and relapse in antineutrophil cytoplasmic antibody–associated small‐vessel vasculitis: Comparison of two independent cohorts

OBJECTIVE Predictors of treatment resistance and relapse have been identified in patients with antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis in the Glomerular Disease Collaborative Network (GDCN) in the southeastern US. This study was undertaken to evaluate the applicability of those predictors in an independent cohort followed up by the French Vasculitis Study Group. METHODS Predictors of treatment resistance were evaluated using logistic regression models and reported as odds ratios (ORs) with 95% confidence intervals (95% CIs). Predictors of relapse were evaluated using Cox proportional hazards models and reported as hazard ratios (HRs) with 95% CIs. Models were controlled for age, sex, race, baseline serum creatinine level, and cyclophosphamide therapy. RESULTS The French cohort (n = 434) and the GDCN cohort (n = 350) had similar median followup periods (44 months versus 45 months) and initial percentages of patients taking cyclophosphamide (82% versus 78%). The French cohort included more patients with proteinase 3 (PR3) ANCA (58% versus 40%), lung involvement (58% versus 49%), and upper respiratory tract involvement (62% versus 31%). Of the predictors of treatment resistance in the GDCN cohort (female sex, African American race, presence of myeloperoxidase ANCA, elevated creatinine level, and age), only age predicted treatment resistance in the French cohort (OR 1.32 per 10 years [95% CI 1.05-1.66]). Predictors of relapse in the GDCN cohort were PR3 ANCA (HR 1.77 [95% CI 1.11-2.82]), lung involvement (HR 1.68 [95% CI 1.10-2.57), and upper respiratory tract involvement (HR 1.58 [95% CI 1.00-2.48]), while predictors in the French cohort were PR3 ANCA (HR 1.66 [95% CI 1.15-2.39]) and lung involvement (HR 1.56 [95% CI 1.11-2.20]), but not upper respiratory tract involvement (HR 0.96 [95% CI 0.67-1.38]). CONCLUSION Our findings indicate that older age is a predictor of treatment resistance, and that PR3 ANCA and lung involvement are predictors of relapse in both cohorts. Discrepancies in predictors of treatment tract resistance may reflect differences in access to care, and differences in predictors of relapse may reflect variations in disease expression.

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.

Clinical trial of focal segmental glomerulosclerosis in children and young adults

This NIH-funded multicenter randomized study of focal segmental glomerulosclerosis (FSGS) treatment compared the efficacy of a 12-month course of cyclosporine to a combination of oral pulse dexamethasone and mycophenolate mofetil in children and adults with steroid-resistant primary FSGS. Of the 192 patients enrolled, 138 were randomized to cyclosporine (72) or to mycophenolate/dexamethasone (66). The primary analysis compared the levels of an ordinal variable measuring remission during the first year. The odds ratio (0.59) for achieving at least a partial remission with mycophenolate/dexamethasone compared to cyclosporine was not significant. Partial or complete remission was achieved in 22 mycophenolate/dexamethasone- and 33 cyclosporine-treated patients at 12 months. The main secondary outcome, preservation of remission for 26 weeks following cessation of treatment, was not significantly different between these two therapies. During the entire 78 weeks of study, 8 patients treated with cyclosporine and 7 with mycophenolate/dexamethasone died or developed kidney failure. Thus, our study did not find a difference in rates of proteinuria remission following 12 months of cyclosporine compared to mycophenolate/dexamethasone in patients with steroid-resistant FSGS. However, the small sample size might have prevented detection of a moderate treatment effect.

A review of therapeutic studies of idiopathic membranous glomerulopathy

The treatment of idiopathic membranous glomerulopathy remains an enigma. We have reviewed many of the important clinical trials concerning membranous glomerulopathy using a meta-analysis and a secondary pooled analysis to test the effects of corticosteroid or alkylating, therapy compared with no treatment on renal survival and complete remission of the nephrotic syndrome. A search was performed using MEDLINE (1968 through 1993) for articles on idiopathic membranous glomerulopathy and glomerulonephritis. Bibliographies of articles were reviewed for completeness. Sixty-nine articles were reviewed. Meta-analysis was performed for four trials that evaluated corticosteroids compared with no treatment and for three trials that evaluated alkylating therapy compared with no treatment. Pooled analysis was performed on randomized and prospective studies (10 studies) and then with 22 case series added. All studies evaluated renal biopsy-proven disease. Meta-analysis was performed on the relative chance of being in complete remission for each study. Renal survival could be evaluated by pooled analysis only. For pooled analyses, Coxs proportional hazard and logistic regression models were used to test the effect of therapy on renal survival and the nephrotic syndrome, respectively. Data concerning gender, nephrotic syndrome, and geographic region were used in all statistical models. Evaluation of renal survival revealed no differences by treatment group (P > 0.1). By meta-analysis, the relative chance of complete remission was not improved for corticosteroid-treated patients (1.55; 95% confidence interval, 0.99 to 2.44; P > 0.1), but was improved for patients treated with alkylating agents (4.8; 95% confidence interval, 1.44 to 15.96; P < 0.05) when compared with no treatment. Pooled analysis of randomized and prospective studies, as well pooled analysis with all studies, supported the findings of the meta-analysis. Corticosteroids or alkylating therapy did not improve renal survival in idiopathic membranous glomerulopathy. Complete remission of the nephrotic syndrome was observed more frequently with the use of alkylating agents.

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.

Internalization of Proteinase 3 Is Concomitant with Endothelial Cell Apoptosis and Internalization of Myeloperoxidase with Generation of Intracellular Oxidants

The important issue addressed by the studies presented here is the mechanism of neutrophil-mediated damage to endothelial and epithelial cells during inflammation. Binding of neutrophil-released granule proteins to endothelial cells may be involved in vascular damage in patients with inflammatory vascular diseases. We have determined whether granule proteins proteinase 3(PR3) and/or myeloperoxidase (MPO) are internalized into endothelial cells, as examined by UV light, confocal, and electron microscopy. Coincident induction of apoptosis and/or the generation of intracellular oxidants were monitored. The results indicate that human endothelial cells (human umbilical vein endothelial cells, human umbilical arterial endothelial cells, human lung microvascular endothelial cells) internalize both PR3 and MPO, which are detected on the cell surface, in the cytoplasm, and possibly nuclear. Epithelial cells (small airway epithelial cells) internalized MPO but not PR3, implying that the mechanism of PR3 internalization may be cell-type specific and different from that of MPO. Internalization of PR3, but not MPO, correlated with activation of apoptosis. Internalization of MPO correlated with an increase in intracellular oxidant radicals. The requirement for the proteolytic activity of PR3 for the induction of apoptosis was examined by generating PR3-truncated fragments that did not contain the components of the catalytic triad. An apoptotic function was localized to the C-terminal portion of PR3. These studies reveal novel mechanisms by which the neutrophil granule proteins PR3 and MPO contribute to tissue injury at sites of inflammation.

Design of the nephrotic syndrome study network (NEPTUNE) to evaluate primary glomerular nephropathy by a multidisciplinary approach

The Nephrotic Syndrome Study Network (NEPTUNE) is a North American multi-center collaborative consortium established to develop a translational research infrastructure for Nephrotic Syndrome. This includes a longitudinal observational cohort study, a pilot and ancillary studies program, a training program, and a patient contact registry. NEPTUNE will enroll 450 adults and children with minimal change disease, focal segmental glomerulosclerosis and membranous nephropathy for detailed clinical, histopathologic, and molecular phenotyping at the time of clinically-indicated renal biopsy. Initial visits will include an extensive clinical history, physical examination, collection of urine, blood and renal tissue samples, and assessments of quality of life and patient-reported outcomes. Follow-up history, physical measures, urine and blood samples, and questionnaires will be obtained every 4 months in the first year and bi-annually, thereafter. Molecular profiles and gene expression data will be linked to phenotypic, genetic, and digitalized histologic data for comprehensive analyses using systems biology approaches. Analytical strategies were designed to transform descriptive information to mechanistic disease classification for Nephrotic Syndrome and to identify clinical, histological, and genomic disease predictors. Thus, understanding the complexity of the disease pathogenesis will guide further investigation for targeted therapeutic strategies.