抗髓过氧化物酶抗体阳性的韦格纳肉芽肿病的特点

目的 分析抗髓过氧化物酶(MPO)抗体阳性的韦格纳肉芽肿病(WG)患者的临床病理特点及其与传统的抗蛋白酶3(PR3)抗体阳性者之间的差异&#65377;方法 89例WG患者经本院肾内科确诊,分析其临床病理资料并对比抗MPO抗体阳性和抗PR3抗体阳性的两组患者之间的差异&#65377;结果 89例患者中54例抗MPO抗体阳性,34例抗PR3抗体阳性&#65377;抗MPO抗体阳性患者中男性所占的比例显著低于抗PR3抗体阳性者(男:女分别为23:31与24:10, P<0.05)&#65377;抗MPO抗体阳性的WG临床亦呈多器官受累的表现,其中关节痛&#65380;皮疹&#65380;眼&#65380;耳受累的发生率显著低于抗PR3抗体阳性者(分别为46.3%比70.6%,P < 0.05; 20.4%比44.1%,P < 0.05;27.8%比58.8%,P < 0.01和40.7%比67.6%,P < 0.05);伯明翰血管炎活动度积分(BVAS)显著低于抗PR3抗体阳性者(22.2±6.2比24.7±6.9, P < 0.05);而在确诊时Scr增高的发生率则显著高于抗PR3抗体阳性者(81.5%比61.8%, P < 0.05)&#65377;结论 在国人的WG患者中,抗MPO抗体阳性者可能不占少数,它与抗PR3抗体阳性者临床表现有所不同&#65377;     

Renal histology in Chinese patients with anti-myeloperoxidase autoantibody-positive Wegener's granulomatosis.

BACKGROUND: Proteinase-3 antineutrophil cytoplasmic antibody (PR3-ANCA) was the serological marker for Wegener's granulomatosis (WG), while myeloperoxidase (MPO)-ANCA was the serological marker for microscopic polyangiitis (MPA). However, our previous study suggested that patients with MPO-ANCA positive WG were common in Chinese. This study aimed to analyse the renal histology of patients with MPO-ANCA positive WG. METHODS: Patients in our centre with WG were selected according to both the Chapel Hill Consensus Conference (CHCC) definition and American College of Rheumatology classification criteria. Patients with MPA were selected according to the CHCC definition. The renal histology was compared between patients with MPO-ANCA positive WG and with PR3-ANCA positive WG as well as patients with MPO-ANCA positive MPA. RESULTS: Sixty-one patients with WG had complete renal histological data, 39/61 with positive MPO-ANCA and 22/61 with positive PR3-ANCA. Among patients with crescents in glomeruli, those with MPO-ANCA had fewer cellular crescents and more fibrous crescents than those with PR3-ANCA (P < 0.01 and P < 0.05, respectively). Interstitial fibrosis and tubular atrophy were more prevalent and severe in patients with MPO-ANCA than in those with PR3-ANCA (P < 0.01 and P < 0.05, respectively). Compared with 44 patients with MPO-ANCA positive MPA, patients with MPO-ANCA positive WG had fewer glomeruli with crescents and more normal glomeruli (P < 0.01 and P < 0.01, respectively). CONCLUSION: Patients with MPO-ANCA positive WG are common in Chinese. In renal histology, chronic lesions were more severe and prevalent in patients with MPO-ANCA positive WG than in patients with PR3-ANCA positive WG. Glomerular lesions were less severe and less prevalent in patients with MPO-ANCA positive WG than in those with MPO-ANCA positive MPA.     

ANCA-associated vasculitis with renal involvement: an outcome analysis.

BACKGROUND: The anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitides are a group of heterogeneous diseases. This study was undertaken to investigate the outcome of Wegener's granulomatosis (WG), microscopic polyangiitis (MPA) and renal-limited vasculitis (RLV). Furthermore, we analysed the differences in patients with proteinase 3-ANCA (PR3-ANCA) and those with myeloperoxidase-ANCA (MPO-ANCA), which have not been assessed in a homogeneously treated group of patients with renal involvement. METHODS: In this retrospective analysis, 80 patients with a new diagnosis of WG, MPA or RLV with biopsy-proven renal involvement were followed over a median of 46.7 months (range: 0.8-181.9 months). All patients had induction treatment with cyclophosphamide and oral corticosteroids. RESULTS: At the end of follow-up, 23% were dependent on dialysis. Renal survival was significantly worse in patients with WG compared with patients with MPA or RLV (P = 0.04). A higher rate of end-stage renal disease (ESRD) was noticed in PR3-ANCA- vs MPO-ANCA-positive patients. A total of 21 patients (26%) died. Predictors of patient mortality were development of ESRD, older age and the maximum creatinine in the first month. Mortality was found to be higher in patients with WG and was significantly higher in PR3-ANCA-positive cases (P = 0.02). The relative risk of death was 9.32 times higher in PR3-ANCA- vs MPO-ANCA-positive patients. CONCLUSIONS: Our data underscore the pathogenetic potential of ANCA by demonstrating a more aggressive disease state and a poorer outcome in patients with PR3-ANCA.     

Clinical characteristics and prognosis of ANCA-associated vasculitis in patients with renal injury

Objective To investigate the characteristics and outcome of anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) in patients with renal injury. Methods AAV patients with renal injury diagnosed in the Department of Nephrology, Renmin Hospital of Wuhan University, from January 2012 to January 2017 were included into this study. Patients were divided into MPO-ANCA positive and PR3-ANCA positive groups for further study. The clinical characteristics, pathological and laboratory indexes, treatment and prognosis were retrospectively analyzed. Results A total of 68 cases were enrolled, among which 52 cases (76.5%) were MPO-ANCA positive and 16 cases (23.5%) were PR3-ANCA positive, and 41 patients (60.3%) were over 65 years old. The incidences of interstitial lung disease, digestive and nervous system damage in PR3-ANCA positive group were significantly higher than those MPO-ANCA positive group (P＜0.05). There were significant differences of hemoglobin, complement C3, complement C1q, IgE, 24 h urinary protein, erythrocyte sedimentation rate, procalcitonin, BVAS score and eGFR in two groups (P＜0.05). 19 cases had done renal biopsy,among them 14 cases were MPO-ANCA positive and 5 cases were PR3-ANCA positive. Incidence of crescentic necrotizing glomerulonephritis in PR3-ANCA positive group was significantly higher than that in MPO-ANCA positive group, and incidence of diffuse global glomerulosclerosis in MPO-ANCA positive group was significantly higher than that in PR3-ANCA positive group (all P＜0.05). At the median follow-up time of 32 months, the relapse rate at 6 month of MPO-ANCA-positive and PR3-ANCA-positive patients were 46.2% and 75.0%, respectively (P＜0.05). Multivariate logistic regression analysis showed that PR3-ANCA positive, age≥65 years old, baseline eGFR＜30 ml?min-1?(1.73 m2)-1, and combined with pulmonary interstitial lesions were all independent risk factors for relapse. And the incidence of ESRD were 42.3% and 75.0% during the follow-up period and 10 patients (14.7%) died. COX regression analysis showed that patients older than 65 years old, BVAS score≥18 points, eGFR＜30 ml?min-1?(1.73 m2)-1 and complicated with pulmonary interstitial disorders at the onset were independent risk factors causing ESRD or death. Conclusion The PR3-ANCA-positive patients had more severe renal injury than those with MPO-ANCA-positive patients, and the injury of extrarenal organs was more serious, recurrence rate was higher, and the prognosis was worse.     

Antineutrophil cytoplasmic antibodies (ANCA) in Chinese patients with anti-GBM crescentic glomerulonephritis

OBJECTIVE: To study the prevalence of ANCA and their target antigen in Chinese patients with anti-GBM crescentic glomerulonephritis (CGN), and to evaluate the possible role of ANCA in Chinese anti-GBM CGN patients with coexisting serum ANCA by studying clinicopathologic features of this disease. MATERIAL AND METHODS: Twenty-three sera were collected from 23 renal biopsy-proven anti-GBM CGN patients. According to the standardized procedures, all of the sera were determined by both, indirect immunofluorescence (IIF) ANCA, and enzyme-linked immunosorbent assay (ELISA) MPO-ANCA, PR3-ANCA and BPI-ANCA. The patients were divided into two groups according to serum ANCA positivity (Group A) or negativity (Group B). Thirty-three ANCA-associated pauci-immune CGN patients were regarded as control group (Group C). Their clinicopathologic features were compared to reveal whether ANCA correlated with disease activity. RESULTS: There were 11 (47.8%) cases with positive serum ANCA in 23 anti-GBM glomerulonephritis patients. There were 4/11 MPO-ANCA (one with positive PR3-ANCA and C-ANCA, three with negative IIF-ANCA), 1/11 PR3-ANCA (with positive MPO-ANCA and C-ANCA), 3/11 P-ANCA (with negative ELISA-ANCA) and 5/11 C-ANCA (one with positive PR3-ANCA and MPO-ANCA, and the other four with negative ELISA-ANCA). No BPI-ANCA was detected. No different clinicopathologic features were found between Groups A and B. Both were different from Group C in age, sex ratio, frequence of anuria and ESRD, variety of crescents, glomerular sclerosis, vessel lesion and prognosis. CONCLUSION: Our data demonstrate that ANCA in Chinese patients with anti-GBM CGN is not rare. The major target antigen of ANCA is MPO. ANCA seems not to be correlated with disease activity.     

Renal histology in ANCA-associated vasculitis: differences between diagnostic and serologic subgroups.

BACKGROUND: Differences in renal histopathology between microscopic polyangiitis (MPA) and Wegener's granulomatosis (WG), and between anti-neutrophil cytoplasm autoantibody (ANCA) test results in patients with ANCA-associated vasculitis may provide insight into the differences in pathogenesis and raise the opportunity of classifying the vasculitides more accurately. The possible differences in histopathology are investigated in this study. METHODS: We report an analysis of 173 patients with renal disease in microscopic polyangiitis or Wegener's granulomatosis. A total of 173 renal biopsies, performed at diagnosis, were scored by two observers separately, using a previously standardized protocol. Consensus on each biopsy was achieved during a central review. RESULTS: Normal glomeruli were more common in WG than in MPA (P < 0.001). Glomerulosclerosis was more prominent in MPA than in WG (P=0.003). Interstitial fibrosis (P < 0.001), tubular atrophy (P < 0.001), and tubular casts (P=0.005) were more frequently present and more severe in MPA than in WG. Presence of glomerulosclerosis was more extensive in patients with myeloperoxidase (MPO)-ANCA than with proteinase 3 (PR3)-ANCA (P=0.022). Interstitial fibrosis (P=0.008), tubular necrosis (P=0.030), tubular atrophy (P=0.013), and intra-epithelial infiltrates (P=0.006) were more frequently present and more severe in MPO-ANCA than in PR3-ANCA. CONCLUSIONS: Glomerulonephritis in relation to MPA has more characteristics of chronic injury at the time of presentation than glomerulonephritis in relation to WG. This difference may be due to a delayed establishment of diagnosis in patients with MPA compared to patients with WG. Both active and chronic lesions are more abundantly present in MPO-ANCA-positive patients than in patients with PR3-ANCA-positivity, which suggests that the pathogenesis of renal disease in these ANCA subsets could be different. Our results also suggest that ANCA test results may be useful in classifying ANCA-associated vasculitides.     

Neutrophil membrane expression of proteinase 3 (PR3) is related to relapse in PR3-ANCA-associated vasculitis

Wegener granulomatosis (WG) is strongly associated with the presence of antineutrophil cytoplasm autoantibodies (ANCA) with specificity for proteinase 3 (PR3). Relapses of WG are frequently preceded by a rise of autoantibody titer and PR3-ANCA are able to activate primed neutrophils in vitro. Except being stored intracellularly and translocated to the cell surface upon neutrophil stimulation, PR3 can also be detected on the surface of non-stimulated neutrophils (membrane PR3 or mPR3), with an interindividual variability in percentages of mPR3(-)-positive cells and level of mPR3 expression. This study began with the hypothesis that the presence of PR3 on the surface of non-stimulated neutrophils enables interaction with PR3-ANCA and influences clinical manifestations of the disease. It analyzed mPR3 expression on neutrophils of 89 WG patients in complete remission and 72 healthy controls to evaluate whether the presence of PR3 on the surface of resting neutrophils is related to clinical manifestations of WG and/or to the susceptibility to develop relapses. The number of patients with a bimodal mPR3 expression on resting neutrophils did not differ between patients and controls. However, in WG patients, an increased percentage of mPR3(+) neutrophils and an elevated level of mPR3 expression compared with healthy individuals (P = 0.037) were found. Within the group of WG patients, an elevated level of mPR3 expression was significantly associated with an increased risk for relapse (P = 0.021) and with an increased relapse rate (P = 0.011), but not with the disease extent or particular manifestations at diagnosis or at relapse. These data support the hypothesis that PR3 expression on the membrane of neutrophils plays a role in the pathophysiology of PR3-ANCA associated vasculitis.     

IgG subclass distribution, affinity of anti-myeloperoxidase antibodies in sera from patients with Wegener's granulomatosis and microscopic polyangiitis

Aim: Our previous study suggested that patients with MPO-ANCA (myeloperoxidase antineutrophil cytoplasmic autoantibodies)-positive Wegener's granulomatosis (WG) were common in Chinese, indicating that patients with MPO-ANCA could manifest as either WG or microscopic polyangiitis (MPA). The aim of this study was to compare the immunological characteristics of MPO-ANCA in patients with WG and MPA. Methods: Fifteen patients with WG and 21 patients with MPA were enrolled in the current study. Anti-MPO IgG subclasses and their titres were detected by antigen-specific enzyme-linked immunosorbent assays (ELISA); affinity was assessed by antigen-inhibition ELISAs. The sera from all patients were employed to inhibit biotin conjugated affinity-purified human anti-MPO antibodies (Probe-biotin), from plasma exchange of a patient with MPA, in a competitive inhibition ELISAs system. Results: All four anti-MPO subclasses could be detected in sera from patients with WG and MPA. The titres of anti-MPO IgG4 subclass in patients with WG were significantly higher than those with MPA (1:1878 vs 1:218, P < 0.005). The affinity constants of MPO-ANCA were comparable between patients with WG and MPA (0.3–70/M vs 0.3–140/M respectively). Eleven out of the 15 sera and 18 out of the 21 sera could inhibit the binding of the Probe-biotin in patients with WG and MPA respectively. The average inhibition rate was 47.7% ± 11.5% and 61.7% ± 14.5% respectively (P < 0.05). Conclusion: MPO-ANCA IgG4 subclass might play a role in the development of WG. The MPO-ANCA in WG and MPA might recognize overlapping but different epitopes on native MPO molecule. The difference in immunological characteristics of MPO-ANCA might contribute to different disease entities.     

Cimetidine-induced tubulointerstitial nephritis with both MPO-ANCA and PR3-ANCA

We describe a 75-year-old man with tubulointerstitial nephritis (TIN) with myeloperoxidase (MPO)-antineutrophil antibody (ANCA) and proteinase-3 (PR3)-ANCA. He had a slight fever and eruption with itching after taking cimetidine (prescribed after gastrectomy for gastric cancer) and he was admitted to a nearby hospital. There, he showed proteinuria, serum creatinine (sCr) of 2.9 mg/dl, and creatinine clearance (Ccr) of 44 ml/min per 1.73 m². His MPO-ANCA titer was 267 EU, and PR3-ANCA titer was 112 EU. Abnormal concentrations in bilateral kidneys were found by gallium scintigraphy. For these reasons, he was transferred to our hospital. Percutaneous renal biopsy was performed after admission. Severe tubular atrophy, mild interstitial fibrosis, and severe mononuclear cell infiltration of the interstitium were noted. Drug-induced renal impairment was suspected, and cimetidine administration was withdrawn. Lymphocyte stimulation tests (DLSTs) were performed. The cimetidine titer was positive, at 2,537 cpm. After the withdrawal of cimetidine, the PR3-ANCA titer was reduced gradually, and, next, the MPO-ANCA titer was also reduced. The sCr level was reduced to 1.2 mg/dl. In summary, we report herein the first case of cimetidine-induced TIN associated with both MPO-ANCA and PR3-ANCA.     

ANCA相关性血管炎肾损害临床特征及早期诊治探讨

目的 分析抗中性粒细胞胞浆抗体(ANCA)相关性血管炎的临床表现和肾脏病理特征,探讨早期诊断和治疗对预后的影响.方法选取本院2000年1月至2009年8月明确诊断的ANCA相关性血管炎共21例,18例行肾活检.总结患者的临床病理资科.分析不同治疗时机对肾功能转归的影响.结果本组21例ANCA相关性血管炎平均年龄(52.5±11.5)岁,显微镜下多血管炎(MPA)16例,韦格纳肉芽肿(WG)3例,变应性肉芽肿性血管炎(CSS)2例.肾外表现主要为发烧17例(80.1%)、下呼吸道症状18例(85.7%)、肺影像学改变21例(100%)、贫血16例(76.2%)、眼耳鼻受累8例(38.1%);肾脏表现血尿21例(100%),蛋白尿19例(90.1%),血肌酐正常6例(28.5%),升高15例(71.4%),8例需透析替代.ANCA检测pANCA和MPO-ANCA阳性16例,cANCA和PR3-ANCA阳性3例.pANCA/MPO-ANCA和cANCA/PR3-ANCA均阳性1例,全阴性1例.肾活检可见节段性小血管壁纤维素样坏死,新月体多见.免疫荧光无或微量免疫复合物沉积.治疗采用糖皮质激素联合环磷酰胺,重症加用血浆置换.7例血肌酐异常但不需透析者5例治疗后血肌酐恢复正常;8例需透析者2例治疗后血肌酐恢复正常,2例脱离透析但血肌酐异常,4例未能脱离透析.结论ANCA相关性小血管炎临床表现多样,肺、肾是最常见的受累器官.ANCA检测和肾活检有助于早期诊断,尽早积极治疗有助于肾功能的恢复.     

The clinical features of anti-neutrophil cytoplasmic antibody-associated systemic vasculitis in Chinese children

Anti-neutrophil cytoplasmic antibody (ANCA)-associated systemic vasculitis is reported mainly in adults. Studies in children are limited. The current study retrospectively analyzed the clinical characteristics and pathology of ANCA-associated systemic vasculitis in children in our hospital during the past 7 years. Twenty-four pediatric patients were diagnosed as having ANCA-associated systemic vasculitis, including 19 patients with microscopic polyangiitis (MPA), one with Wegener’s granulomatosis (WG), three with propylthiouracil (PTU)-induced ANCA-positive vasculitis and one with anti-glomerular basement membrane (GBM) disease. Of patients with primary ANCA-associated systemic vasculitis (MPA and WG), with an average age of 10.8±2.8 (6–14) years, 18 patients (90%) were female and two (10%) were male. Nineteen patients (95%) were p-ANCA/MPO-ANCA positive and one (5%) was c-ANCA/PR3-ANCA positive. The interval between onset and diagnosis was 8.5±24.3 (0.2–108) months. The majority of the patients (85%) had multi-organ involvement. All patients had clinical evidence of renal involvement and presented with hematuria and proteinuria. Of 20 patients, 16 (80%) also had acute renal failure, and five patients were dialysis dependent. Nine patients underwent renal biopsy and were diagnosed with necrotizing and crescentic glomerulonephritis. However, six biopsies showed immune complex deposition. All patients received immunosuppressive therapy including prednisone and cyclophosphamide, and ten patients also received intravenous administration of methylprednisone pulse therapy according to their clinical situation and renal pathology. Sixteen patients achieved clinical remission, and four patients presented as treatment failure. Patients were followed up for 12.3±5.1 months (median 12 months; range 1 to 91 months). Ten patients maintained their clinical remission, and ten progressed to renal failure requiring dialysis. Our study showed that the clinical features and pathology of primary ANCA-associated systemic vasculitis in children were similar to those of adults, but there were a predominance of female patients and late diagnoses. We suggest that early recognition and prompt aggressive treatment might improve outcome.     

High proteinase 3-anti-neutrophil cytoplasmic antibody (ANCA) level measured by the capture enzyme-linked immunosorbent assay method is associated with decreased patient survival in ANCA-associated vasculitis with renal involvement

Wegener granulomatosis (WG) and microscopic polyangiitis (MP), diseases associated with antineutrophil cytoplasmic antibodies (ANCA), had an extremely poor prognosis before the introduction of cyclophosphamide and corticosteroids for their treatment. However, there is still reduced patient survival, and some studies have documented severe side effects of the immunosuppressants used. This 10-yr follow-up study assessed 117 consecutive patients with WG or MP with biopsy-confirmed renal involvement. The cumulative relative patient survival was lower: 0.664 for women and 0.648 for men. The causes of death (n = 64) were in most cases registered as associated with the vasculitic disease. Analysis of possible predictive factors for patient survival by multiple Cox regression analysis revealed that a very high level of proteinase 3 (PR3)-ANCA measured by the capture ELISA method, a diagnosis of MP, and older age were factors predicting poorer patient survival. High levels of B-thrombocytes at time of diagnosis were associated with a better prognosis. For patients surviving the first year, remission-sustaining therapy with azathioprine for longer than 12 mo was associated with improved patient survival. Thirty-nine patients developed end-stage renal failure. Elevated serum creatinine at time of diagnosis and a very high level of PR3-ANCA by capture ELISA were factors predicting a higher risk for renal failure during follow-up. The epitope on PR3 assessed by capture ELISA needs to be further analyzed and explored: it seemed to implicate poorer patient and renal survival in WG or MP with renal involvement.     

Clinicopathological analysis of Sjogren's syndrome complicated with ANCA associated vasculitis with renal involvement

Objective To investigate the clinical and pathological features of patients with a combination of Sjogren's syndrome (SS) and antineutrophil cytoplasmic antibody (ANCA) associated vasculitis with renal involvement. Methods By searching the Peking Union Medical College Hospital medical database and literature between January 1990 and June 2017, patients had a combination of SS and ANCA associated vasculitis with renal involvement were included. Data of clinical information, autoimmune antibodies, renal manifestations and renal pathology were retrieved and analyzed. Results Eighteen patients were enrolled: 4 from our hospital and 14 from literature. SS was diagnosed no later than ANCA associated vasculitis in all the patients, among which 83.3%(15/18) of patients had extra-glandular and extra-renal organs involved. All the patients were tested positive for myeloperoxidase (MPO)-ANCA, and only two were protein 3 (PR3)-ANCA positive concurrently. The positivity rates of antinuclear antibody (ANA), rheumatoid factor (RF), anti-SSA antibody, and anti-SSB antibody were 83.3%(15/18), 55.6%(10/18), 77.8%(14/18), and 38.9%(7/18), respectively. The renal manifestations were characterized by renal insufficiency with a median serum creatinine of 174 μmol/L, hematuria, moderate proteinuria with a median 24 hour urine protein of 1.70 g, and necrotizing vasculitis with oligo-immune complex and varying degrees of interstitial damage in pathology. Conclusions A combination of Sjogren's syndrome and ANCA associated vasculitis with renal involvement is rare in clinical setting, and almost all of the patients are MPO-ANCA positive, with high probability of ANA positivity and extra-glandular involvement. Physicians should beware of ANCA associated glomerulonephritis in SS patients with inexplicable renal dysfunction and renal biopsy should be carried out in time.     

Anti-laminin auto antibodies in ANCA-associated vasculitis.

BACKGROUND: Endothelial cell damage occurs during vasculitic processes in vivo. With the alteration of the endothelium, exposure to basement membrane components may occur with induction of humoral immunity. METHODS: In the present study, we evaluated the prevalence of antibodies against the basement membrane antigen laminin (LMN) in patients with ANCA-associated systemic vasculitis (AASV), pathologic controls (systemic lupus erythematosus, mixed cryoglobulinaemia, Henoch-Sch?nlein purpura, primary glomerulonephritis) and normal individuals. RESULTS: By ELISA, 21.6% of AASV (16/74) and 10% of pathologic controls (3/30), but only one of the normal controls (2. 8%) had these antibodies (P=0.02). When AASV patients were divided into two groups according to diagnosis and ANCA antigen specificity, antibodies to LMN were found in 27.5% of MPO-ANCA positive microscopic polyangiitis patients (11/40) vs. only 14.7% of PR3-ANCA positive Wegener granulomatosis patients (5/34). There was no correlation between the presence or titre of anti-LMN antibodies and the main clinical and laboratory parameters. CONCLUSION: These results indicate that basement membrane antigens may become immunogenic in patients with AASV, especially in those with MPO-ANCA positivity. These antibodies are most likely the result of endothelial damage secondary to the initial inflammatory process but may well perpetuate further vascular damage in some patients.     

Antineutrophil cytoplasmic antibodies to proteinase 3 in Wegener's granulomatosis: epitope analysis using synthetic peptides

BACKGROUND: Antineutrophil cytoplasmic antibodies (ANCA) to proteinase 3 (PR3) are strongly associated with Wegener's granulomatosis (WG) and are thought to be involved in its pathogenesis. Levels of PR3-ANCA do not always correspond to clinical disease activity nor to functional effects of these antibodies in vitro, suggesting differences in epitope specificity. To define relevant epitopes for PR3-ANCA, sera of WG patients were analyzed on their reactivity to linear peptides of PR3. METHODS: Fifty linear peptides of 15 amino acids in length with an overlap of 10 aa spanning the entire PR3 sequence were synthesized. Sera of 27 WG patients with active disease and 27 age- and sex-matched healthy controls, eight anti-PR3 monoclonal antibodies (mAbs), and a rabbit anti-PR3 serum were tested by enzyme-linked immunosorbent assay for reactivity to PR3 peptides. RESULTS: Rabbit anti-PR3 serum recognized three distinct peptide areas, whereas none of the anti-PR3 mAbs bound PR3 peptides. Sera of both WG patients and healthy controls recognized a restricted number of PR3 peptides. Four of these peptide areas were recognized significantly more strongly by WG sera than by control sera. Sera drawn at the initial presentation of WG mainly recognized these peptides. Two of the recognized peptide areas were located near the active center of PR3. CONCLUSION: A restricted number of epitope areas of PR3 are recognized both by WG patient sera and control sera. Four peptide areas were bound stronger by sera of WG patients at initial presentation than by healthy controls.     

Human anti-neutrophil cytoplasm autoantibodies to proteinase 3 (PR3-ANCA) bind to neutrophils

BACKGROUND: Recently, the in vivo pathogenic role of anti-neutrophil cytoplasm autoantibodies (ANCA) in ANCA-associated vasculitis has been challenged by Abdel-Salam et al. In their report, they observed that ANCA directed against proteinase 3 (PR3) cannot bind to their target autoantigen PR3 on circulating neutrophils (PMN). Here we present evidence that human PR3-ANCA do specifically bind to PMN that express PR3 on their membrane. METHODS: PMN were isolated from donors showing bimodal membrane PR3 expression on their PMN (N= 3). TNFalpha-primed PMN or PMA-stimulated PMN were incubated with serum or plasma from PR3-ANCA-positive patients with Wegener's granulomatosis (WG) (N= 8) or healthy controls (N= 8). Binding of IgG in serum or plasma samples to PMN was assessed by indirect immunofluorescence. RESULTS: Binding of IgG in undiluted plasma or serum from PR3-ANCA-positive WG-patients to PMN was significantly increased compared to plasma or serum from healthy controls. Dilution of plasma and serum showed concentration-dependent binding of IgG. Double staining for PR3 and IgG demonstrated that IgG in plasma or serum from PR3-ANCA-positive patients only bound to those PMN that expressed PR3, and not to PMN that lacked PR3 expression on their membrane. CONCLUSION: PR3-ANCA in undiluted serum or plasma from PR3-ANCA-positive WG patients bind to TNFalpha- primed and PMA-stimulated PMN that express PR3 on their membrane. Therefore, the hypothesis that PR3-ANCA can bind and activate primed PMN is still the most attractive explanation for the contribution of PR3-ANCA to the pathogenesis of Wegener's granulomatosis.     

Clinical manifestations of granulomatosis with polyangiitis (Wegener’s granulomatosis) in the upper respiratory tract seen by otolaryngologists in Japan

We studied 91 patients with granulomatosis with polyangiitis (GPA; Wegener’s granulomatosis) who were dealt with by otolaryngologists in Japan. The upper respiratory tract (URT) alone was involved in 56%. Regarding findings of PR3-ANCA, histology and initial diagnosis, of the 40 patients in whom sites other than the URT were involved, 64 and 73 % were positive for PR3-ANCA and histology, respectively. On the other hand, of 51 patients in whom only the URT was involved, only 49 and 31 % were positive for PR3-ANCA and histology, respectively. With regard to diagnosis, definitive and probable diagnoses were made in 78 and 20 %, respectively, of patients involving sites other than the URT. On the other hand, definitive and probable diagnoses were made in only 22 and 37 %, respectively, of patients involving the URT alone; the Japanese diagnostic criteria were inapplicable to 41 %. Of the 21 patients to whom the diagnostic criteria were inapplicable, 13 (62 %) developed additional symptoms and signs during the observation period, and they then fulfilled the Japanese diagnostic criteria. Among these patients, 8 were MPO-ANCA-positive and 3 patients had 2 or more sub-lesions in the URT. If the diagnostic criteria included cases with MPO-ANCA (±) and 2 lesions in the URT, the diagnostic rates increased from 59 to 86 % even though they were of limited form. Thus, about 60 % of the patients with URT symptoms alone did not satisfy the Japanese diagnostic criteria at the initial visit.     

Mycophenolate mofetil versus cyclophosphamide for inducing remission of ANCA vasculitis with moderate renal involvement.

OBJECTIVE: We performed a single-centre non-blinded clinical trial to compare the clinical efficacies of mycophenolate mofetil (MMF) and intermittent cyclophosphamide (CTX) pulse therapy as induction treatments in patients with antineutrophil cytoplasmic antibody (ANCA) vasculitis (AAV) and moderate renal involvement. METHODS: Patients with active AAV and serum creatinine <500 micromol/L received either MMF treatment (MMF group) or monthly CTX pulse therapy (CTX group) for 6 months. Disease activity was assessed using the Birmingham Vasculitis Activity Score (BVAS). The disease activity, remission rate, renal function and adverse reactions were compared between the two groups. RESULTS: A total of 35 patients (15 male, 20 female: aged 49.1 +/- 12.2 years) were enrolled, with 18 in the MMF group and 17 in the CTX group. Of the 35 patients, 28 were MPO-ANCA positive and 2 were PR3-ANCA positive. Four patients were lost to follow-up in the CTX group. At Month 6, BVAS scores were much lower in the MMF group than in the CTX group (0.2 +/- 0.89 versus 2.6 +/- 1.7, P < 0.05). In the intent-to-treatment analysis, 14 of 18 patients (77.8%) treated with MMF and 8 of 17 patients receiving CTX (47.1%) had complete remission with an absolute difference of 30.7%. Eight of 18 patients (44.4%) in the MMF group and 2 of 17 patients (15.4%) in the CTX group recovered renal function. Serum ANCA decreased to normal in 41.7% of patients in the MMF group and in 16.7% in the CTX group. Side effects in the MMF group were pneumonia (1), herpes zoster (1) and gastrointestinal symptoms (2), and in the CTX group were leukocytopenia (1), gastrointestinal distress (4) and pneumonia (1). CONCLUSION: Our study suggests that MMF effectively ameliorates disease activity and considerably improves renal function in patients with AAV. Further large-scale multicentre prospective randomized controlled trials will be needed to confirm these findings.     

Antibodies with dual reactivity to plasminogen and complementary PR3 in PR3-ANCA vasculitis

Patients with inflammatory vascular disease caused by anti-neutrophil cytoplasmic autoantibodies (ANCA) can harbor antibodies not only to the autoantigen proteinase 3 (PR3) but also to complementary PR3 (cPR3(105-201)), a recombinant protein translated from the antisense strand of PR3 cDNA. The purpose of this study was to identify potential endogenous targets of anti-cPR3(105-201) antibodies. Patients' plasmapheresis material was tested for the presence of antigens reactive with affinity-purified rabbit and chicken anti-cPR3(105-201) polyclonal antibodies. Antigen-containing fractions were tested with patients' anti-cPR3(105-201) affinity-purified IgG, and putative protein targets were sequenced by mass spectrometry. Unexpectedly, plasminogen was identified as a target of anti-cPR3(105-201). Reactivity of affinity-purified antibodies from two patients was lost when plasminogen was converted to plasmin, indicating restricted specificity. Antiplasminogen antibodies from five patients bound plasminogen at a surface-exposed loop structure within the protease domain. This loop contains an amino acid motif that is also found in a portion of recombinant cPR3(105-201); site-directed mutagenesis of this sequence decreased antibody reactivity by 30%. Functionally, antiplasminogen antibodies delayed the conversion of plasminogen to plasmin and increased the dissolution time of fibrin clots. Serologically, antiplasminogen antibody levels were higher in PR3-ANCA patients (n = 72) than healthy control subjects (n = 63), myeloperoxidase-ANCA patients (n = 34), and patients with idiopathic thrombosis (n = 57; P = 0.001). Of the patients with PR3-ANCA, nine had documented deep venous thrombosis events, five of whom were positive for antiplasminogen antibodies. In summary, capitalizing on interactions with complementary proteins, specifically complementary PR3, this study identified plasminogen as a previously undescribed autoantigen in PR3-ANCA vasculitis.     

No association of G-463A myeloperoxidase gene polymorphism with MPO-ANCA-associated vasculitis.

BACKGROUND: The activation of neutrophils and monocytes by ANCA, resulting in the release of reactive oxygen species and proteases like myeloperoxidase (MPO), is essential to the pathogenesis of ANCA-associated vasculitis. As the A allele of the G-463A MPO gene polymorphism is associated with diminished activity of MPO, it is conceivable that the presence of this allele protects against MPO-ANCA-associated vasculitis. METHODS: Allelic frequencies of the G-463A polymorphism were studied in 119 ANCA-associated vasculitis patients, 48 with MPO-ANCA and 71 with proteinase 3 (PR3)-ANCA. RESULTS: Allelic frequencies of MPO G-463A promoter polymorphism did not differ between MPO-ANCA- and PR3-ANCA-associated vasculitis patients. Moreover, allelic distribution was similar to that of the normal population. CONCLUSIONS: The data suggest that G-463A polymorphism does not seem to contribute to either MPO-ANCA- or PR3-ANCA-associated vasculitis formation.