Follow-up of avidity and titre of anti-myeloperoxidase antibodies in sera from patients with propylthiouracil-induced vasculitis

OBJECTIVE: Propylthiouracil (PTU) has been known to induce myeloperoxidase-antineutrophil cytoplasmic antibody (MPO-ANCA) positive vasculitis. Our previous study indicated that the increase of avidity of MPO-ANCA might be associated with the occurrence of clinical vasculitis in patients with PTU-induced ANCA. The current study aimed to follow-up the avidity and titre of anti-MPO antibodies in sequential sera from patients with PTU-induced ANCA-associated systemic vasculitis (AASV). METHODS: Six patients with PTU-induced vasculitis were enrolled in the current study. Serial sera in both active phase and in remission were collected. MPO-ANCA avidity was assessed by antigen-inhibition enzyme-linked immunosorbent assays (ELISAs), and avidity constant (aK) was determined as the reciprocal value of the MPO molar concentration in the liquid phase resulting in 50% inhibition of anti-MPO antibody binding to MPO in solid phase ELISA. Titres of MPO-ANCA were determined by using serial serum dilutions in MPO-ELISA. RESULTS: After cessation of PTU and initiation of immunosuppressive therapy, the avidity and titre of MPO-ANCA decreased significantly during follow-up in sera from all the patients, and the avidity decreased much more quickly than the titres. CONCLUSION: Our study indicates that avidity of anti-MPO antibodies might be more closely associated with clinical vasculitis than titre.     

The clinical features and pathology of vasculitis associated with anti-myeloperoxidase autoantibodies

Autoantibodies to myeloperoxidase (MPO) are associated with the autoimmune disease, systemic vasculitis, in humans. This results in severe inflammation and microscopic necrosis of multiple organs, especially the kidneys, leading to renal failure and death. The discovery of MPO autoantibodies has permitted the development of new diagnostic tests allowing earlier diagnosis and more effective therapy. Furthermore these antibodies are directly implicated in tissue injury by binding to MPO on the neutrophil cell membrane and stimulating neutrophil activation and degranulation. The causes for the breakdown in tolerance to MPO are not known although rare cases are drug-induced and remit on drug withdrawal. An understanding of the biology of MPO and its involvement in the pathogenesis of vasculitis is of importance in understanding the pathogenesis of vasculitis and the development of newer therapies.     

Circulating DNA and myeloperoxidase indicate disease activity in patients with thrombotic microangiopathies

Thrombotic microangiopathies (TMAs) are a group of life-threatening disorders characterized by thrombocytopenia, fragmentation of erythrocytes, and ischemic organ damage. Genetic disorders, autoimmune disease, and cancer are risk factors for TMAs, but an additional, unknown trigger is needed to bring about acute disease. Recent studies suggest that DNA and histones are released during inflammation or infection and stimulate coagulation, thrombosis, thrombocytopenia, and organ damage in mice. We show that extracellular DNA and histones as well as markers of neutrophils are present in acute TMAs. Analysis of plasma from TMA patients of different clinical categories revealed elevated levels of DNA-histone complexes and myeloperoxidase (MPO) from neutrophil granules as well as S100A8/A9, a heterocomplex abundant in neutrophil cytosol. During therapy of thrombotic thrombocytopenic purpura, a subtype of TMAs often associated with severe ADAMTS13 (a disintegrin and metalloproteinase with thrombospondin type 1 motifs, member 13) deficiency, plasma DNA and MPO were inversely correlated with platelet counts, and their levels indicated amelioration or exacerbation of the disease. ADAMTS13 deficiency together with increased levels of plasma DNA and MPO were characteristic for acute thrombotic thrombocytopenic purpura. A minor infection often precedes acute TMA and extracellular DNA and histones released during the inflammatory response could provide the second hit, which precipitates acute TMA in patients with pre-existing risk factors.     

Progressive systemic sclerosis associated with anti-myeloperoxidase ANCA vasculitis with renal and cutaneous involvement

Sclerodema renal crisis is the usual form of presentation of renal disease in systemic sclerosis. We report a woman who at age 63 was given a diagnosis of scleroderma with Raynaud's phenomenon and cutaneous, oesophageal and lung involvement but no evidence of renal disease and no treatment with D-penicillamine. Two years later she developed progressive renal failure, nephrotic range proteinuria, haematuria and the presence of serum MPO-ANCA; she was normotensive. Renal biopsy revealed extracapillary and necrotizing glomerulonephritis and skin biopsy showed leucocytoclastic vasculitis. This clinical picture was compatible with necrotizing vasculitis of the microscopic polyarterits type. After treatment with pulse steroids followed by oral steroids and monthly intravenous cyclophosphamide her renal function stabilised and the serum MPO-ANCA disappeared.     

Propylthiouracil (PTU)-induced vasculitis associated with antineutrophil antibody against myeloperoxidase (MPO-ANCA)

A 54-year-old woman had been administered propylthiouracil (PTU) for Graves' disease for 4 years. Recently, she complained of hemoptysis due to pulmonary alveolar hemorrhage causing anemia, and also had microhematuria. Antineutrophil cytoplasmic antibody against myeloperoxidase (MPO-ANCA) was positive, and she was diagnosed with PTU-induced vasculitis. Cessation of PTU and the administration of corticosteroids ameliorated these manifestations.     

Contribution of myeloperoxidase in vasculitis development

Infiltrated neutrophils is believed to contribute to the progression of vasculitis. In particular, myeloperoxidase (MPO)-specific antibodies against neutrophils, anti-neutrophil cytoplasmic antibodies (MPO-ANCA) is involved in the development of vasculitis microscopic polyangiitis etc. In Japan a higher percentage of MPO-ANCA than that in Europe has been reported In addition, we showed a correlation of MPO-ANCA epitopes of Kawasaki disease patients by 47% with that of mothers'. On the other hand, mice having CADS/CAWS-induced vasculitis is a good model for the analysis of the production of MPO-ANCA. We have clarified that MPO is a major antigen for MPO-ANCA production using MPO KO mice. We also investigated the role of activated neutrophils in nephritis renal lesions using SCG/Kj mice. In the phase of nephritis with low grade of proteinuria, the spontaneous release of MPO from peripheral neutrophils increased, indicating that neutrophils are activated and contribute to the development of active crescentic lesion in SCG/Kj mice.     

Autoreactive T-cell responses to myeloperoxidase in patients with antineutrophil cytoplasmic antibody-associated vasculitis and in healthy individuals

The aim of this study was to evaluate the characteristics of autoreactive T cells to myeloperoxidase (MPO) in patients with MPO-antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis. Peripheral blood T cells from 15 patients with MPO-ANCA-associated vasculitis and 14 healthy individuals were cultured with three recombinant proteins that together comprised the entire MPO sequence (L, all 112 amino acids (AA) of the light chain; HI, AA 1-227 of the heavy chain; HII, AA 212-467 of the heavy chain), and the antigen-specific T-cell proliferative response was measured by 3H-thymidine incorporation. T-cell responses to MPO-L and HI were both detected in four patients and three healthy donors, and responses to MPO-HII were detected in four patients and seven healthy donors. These findings indicate that at least three independent T-cell epitopes exist on the MPO molecule. Interestingly, the patients whose T cells showed these MPO-induced responses were mainly in remission. Peripheral blood T cells reactive with MPO were primarily of the HLA-DR-restricted CD4+ phenotype. In summary, we successfully used recombinant MPO fragments to detect autoreactive CD4+ T cells to multiple MPO epitopes in blood samples from patients with MPO-ANCA-associated vasculitis and healthy individuals.     

Autoreactive T-cell responses to myeloperoxidase in patients with antineutrophil cytoplasmic antibody-associated vasculitis and in healthy individuals

Abstract

The aim of this study was to evaluate the characteristics of autoreactive T cells to myeloperoxidase (MPO) in patients with MPO-antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis. Peripheral blood T cells from 15 patients with MPO-ANCA-associated vasculitis and 14 healthy individuals were cultured with three recombinant proteins that together comprised the entire MPO sequence (L, all 112 amino acids (AA) of the light chain; HI, AA 1-227 of the heavy chain; HII, AA 212-467 of the heavy chain), and the antigen-specific T-cell proliferative response was measured by ³H-thymidine incorporation. T-cell responses to MPO-L and HI were both detected in four patients and three healthy donors, and responses to MPO-HII were detected in four patients and seven healthy donors. These findings indicate that at least three independent T-cell epitopes exist on the MPO molecule. Interestingly, the patients whose T cells showed these MPO-induced responses were mainly in remission. Peripheral blood T cells reactive with MPO were primarily of the HLA-DR-restricted CD4⁺ phenotype. In summary, we successfully used recombinant MPO fragments to detect autoreactive CD4⁺ T cells to multiple MPO epitopes in blood samples from patients with MPO-ANCA-associated vasculitis and healthy individuals.     

Reduced lung uptake of iodine-123 metaiodobenzylguanidine in patients with myeloperoxidase antineutrophil cytoplasmic antibodies-positive vasculitis

BACKGROUND: Iodine-123 metaiodobenzylguanidine ((123)I-MIBG) lung uptake in the early phase has been proposed as a potential marker of endothelial function because MIBG behaves qualitatively similarly to norepinephrine in pulmonary circulation. OBJECTIVES: The purpose of the present study was to examine the lung uptake of (123)I-MIBG in patients diagnosed with myeloperoxidase antineutrophil cytoplasmic antibodies (MPO-ANCA)-associated vasculitis without clinical or radiological abnormalities of the thorax. METHODS: Six patients with MPO-ANCA-associated vasculitis were enrolled. They had severe renal damage (mean creatinine: 5.1 mg/dl, mean blood urea nitrogen: 54.6 mg/dl), but no respiratory symptoms clinically or radiographic findings on chest computed tomography. The total lung to upper mediastinum ratio of (123)I-MIBG uptake (L/M) 15 min after the injection was measured. The result was compared with those for 6 patients with renal damage due to other diseases (mean creatinine: 6.2 mg/dl, blood urea nitrogen: 51.7 mg/dl) and for 8 healthy subjects. RESULTS: The mean value of L/M in patients with MPO-ANCA-positive vasculitis was 1.21 +/- 0.04, which was significantly less than that of other groups (1.41 +/- 0.06 for patients with renal failure and 1.45 +/- 0.03 for normal volunteers). There were no significant differences in MIBG accumulation in the heart among the groups. CONCLUSIONS: The reduction in kinetic behavior of MIBG in the lung reflects the presence of pulmonary endothelial impairment in patients with MPO-ANCA-associated vasculitis, even though there are no clinical manifestations in the lungs.     

Rheumatoid arthritis complicated with myeloperoxidase antineutrophil cytoplasmic antibody (MPO-ANCA)-associated vasculitis: a case report

This article describes a patient with rheumatoid arthritis (RA) with crescentic glomerulonephritis (CrGN) associated with myeloperoxidase-antineutrophil cytoplasmic antibodies (MPO-ANCA), who responded well to methotrexate (MTX). A 48-year-old woman with a 4-year history of RA was admitted with fever and elevated C-reactive protein. On laboratory evaluation, her level of MPO-ANCA was 422 EU, and urinalysis revealed proteinuria and hematuria. Because she was also suffering from episcleritis, vasculitis was considered. A renal biopsy was performed, which revealed necrotizing CrGN. We diagnosed RA complicated with MPO-ANCA-associated vasculitis. We considered treatment with high-dose oral prednisolone for vasculitis, but the patient refused this treatment. We started MTX at a dose of 8 mg/week for RA from the time of admission, and the patient responded immediately. Biochemical parameters, including C-reactive protein, erythrocyte sedimentation rate, rheumatoid factor, and MPO-ANCA, improved. Seven months later, MPO-ANCA had decreased to 46 EU. In clinical studies, few patients have been reported with RA complicated with ANCA-associated CrGN. This case differs from previous cases in the treatment given. No high-dose steroid with intensive immunosuppression or plasma exchange was required.     

Rheumatoid arthritis complicated with myeloperoxidase antineutrophil cytoplasmic antibody (MPO-ANCA)-associated vasculitis: a case report

Abstract

This article describes a patient with rheumatoid arthritis (RA) with crescentic glomerulonephritis (CrGN) associated with myeloperoxidase–antineutrophil cytoplasmic antibodies (MPO-ANCA), who responded well to methotrexate (MTX). A 48-year-old woman with a 4-year history of RA was admitted with fever and elevated C-reactive protein. On laboratory evaluation, her level of MPO-ANCA was 422?EU, and urinalysis revealed proteinuria and hematuria. Because she was also suffering from episcleritis, vasculitis was considered. A renal biopsy was performed, which revealed necrotizing CrGN. We diagnosed RA complicated with MPO-ANCA-associated vasculitis. We considered treatment with high-dose oral prednisolone for vasculitis, but the patient refused this treatment. We started MTX at a dose of 8?mg/week for RA from the time of admission, and the patient responded immediately. Biochemical parameters, including C-reactive protein, erythrocyte sedimentation rate, rheumatoid factor, and MPO-ANCA, improved. Seven months later, MPO-ANCA had decreased to 46?EU. In clinical studies, few patients have been reported with RA complicated with ANCA-associated CrGN. This case differs from previous cases in the treatment given. No high-dose steroid with intensive immunosuppression or plasma exchange was required.     

Circulating endothelial cells and vasculitis

Systemic vasculitides are a heterogeneous group of disorders with inflammation of blood vessels as their common pathogenetic hallmark. They often pose difficulties with regard to diagnosis and monitoring of disease activity, both at the initial presentation and during follow-up. Novel markers of disease activity are therefore eagerly awaited. Circulating endothelial cells have recently emerged as one such marker and we have demonstrated their clinical use in ANCA-associated small-vessel vasculitis. Not only entire cells but also endothelial microparticles can be detected in vasculitis although their use is not established to date. Repair of endothelial damage is believed to occur via endothelial progenitor cells and their precise role in vasculitis is also unclear at present. Circulating endothelial cells may complement, rather than replace, conventional markers of disease activity. The ultimate aim of our studies may thus be a panel of various laboratory markers for systemic vasculitis.     

Circulating C3 levels predict renal and global outcome in patients with renal vasculitis

Several studies have demonstrated the crucial role of complement activation in the pathogenesis of ANCA-associated vasculitis. We aimed to assess the association between baseline serum C3 (sC3) levels and long-term outcomes in patients with renal vasculitis. This retrospective study included 111 patients with renal vasculitis from three hospitals who underwent a renal biopsy between 1997 and 2014. Serum levels of C3 were measured at the onset and the study population was divided into three tertiles according to sC3 concentrations (tertile 1 <106 mg/dl; tertile 2 106–128 mg/dl; tertile 3 >128 mg/dl). Patients with lower sC3 (tertile 1) were compared with those having higher levels of sC3 (tertile 2 and tertile 3). Histological, clinical, and laboratory data were recorded for analysis. The primary end point was the composite of end-stage renal disease (ESRD) and death from any cause. Lower sC3 levels were associated with a higher need for dialysis and lower response rate to treatment (p = 0.04 and p = 0.007, respectively). Renal and global survival at 1 and 5 years was 53 and 46 % in patients with lower sC3 (tertile 1) compared with 72 and 65 % in patients with higher sC3 (upper two tertiles) (p = 0.04). In a multivariate Cox-regression model, when adjusted by renal function and histopatholologic categories, lower sC3 remained as an independent predictor of ESRD and death (HR, 1.9; 95 % CI, 1.1 to 3.4; p = 0.02). Baseline serum C3 levels have an independent prognostic value in predicting long-term renal and global survival in patients with renal vasculitis.     

Circulating IgG antibody to protamine in patients treated with protamine-insulins

Sera from patients with different types of protamine-insulin were assayed for IgG antibody to protamine. A high prevalence of circulating antibody was found in patients treated with either bovine isophane insulin (26 out of 28 patients; 26 of whom also had antibodies to insulin), or bovine protamine zinc insulin (27 out of 30 patients; all 30 had antibodies to insulin). In sera from 24 patients treated with highly purified porcine isophane insulin, protamine antibody was detected in nine; circulating insulin-antibody was detected in 12 patients, eight of whom had protamine-antibody; in the 12 patients with no detectable antibody to insulin, antibody to protamine was detected in only one (x2 = 8.7, p less than 0.01). This relationship between insulin and protamine antigenicity is of interest as it suggests that the protamine-insulin complex is itself immunogenic.     

Association of autoantibodies to myeloperoxidase with different forms of vasculitis

Antineutrophil cytoplasmic autoantibodies with specificity for myeloperoxidase (MPO) were found in 53 patient sera that were routinely submitted for antineutrophil cytoplasmic antibody determination. Based on clinical and histologic criteria, 15 of these 53 patients were classified as having systemic necrotizing vasculitis of the polyarteritis group, 11 patients were classified as having Wegener's granulomatosis (WG), and 14 were classified as having idiopathic crescentic glomerulonephritis. The remaining 13 patients did not fulfill the diagnostic criteria for these disorders, although most of these patients had clinical symptoms compatible with these disorders. While all patients with WG had renal involvement, only 4 of the 15 patients with systemic necrotizing vasculitis of the polyarteritis group had glomerulonephritis. The sensitivity of autoantibodies to MPO for either systemic necrotizing vasculitis of the polyarteritis group, WG, or idiopathic crescentic glomerulonephritis was further tested in all our patients with these disorders (n = 104). Twenty-seven of 104 patients had autoantibodies to MPO. Furthermore, 69 of the remaining 77 patients had autoantibodies specific for the 29-kd serine protease, which has been reported to be specifically associated with WG. Sera from 8 patients were negative for either of these antibodies (92% sensitivity of autoantibodies to MPO and/or the 29-kd serine protease). The specificity of autoantibodies to MPO for either systemic necrotizing vasculitis of the polyarteritis group, WG, or idiopathic crescentic glomerulonephritis was also tested in selected groups of patients who had closely related diseases. Two of 144 patients had autoantibodies to MPO (specificity 99%).(ABSTRACT TRUNCATED AT 250 WORDS)     

The clinical significance of circulating follicular helper T cells in patients with anti-neutrophil cytoplasmic myeloperoxidase antibody-associated vasculitis

正Objective To investigate the change of circulating follicular helper T cells (cTfh) in patients with anti-neutrophil cytoplasmic myeloperoxidase antibody-associated vasculitis (MPO-AAV),and to analyze the relationship between cTfh and disease activity. Methods Thirty-eight     

Neutrophil functions of patients with vasculitis related to myeloperoxidase-specific anti-neutrophil antibody

Neutrophils are hypothesized to cause tissue damage resulting in the development of vasculitis and glomerulonephritis, although they are known to primarily take part in host defense functions. The infiltration of inflammatory cells. notably neutrophils and macrophages, is observed in the progression of vasculitis. Neutrophils with activated status and anti-neutrophil cytoplasmic antibodies (ANCAs), especially myeloperoxidase-specific (MPO)-ANCA, have been implicated in the development of vasculitis. The target molecule of MPG-ANCA is a lysosomal enzyme MPO that usually acts to kill bacteria, viruses, and fungi and that causes damage to the tissue due to the toxicity of its product, hypochlorite (OCl-). To elucidate the role of MPO-ANCA in the progression of vasculitis, a set of MPO-peptide fragments has been developed, and the corresponding epitope site for the specific monoclonal and/or oligoclonal antibody resulting in vasculitis has been determined. Recently some mouse models have been used for analyzing the correlation between MPO and MPO-ANCA in relation to damage of blood vessels followed by the development of vasculitis. This review focuses on the role of activated neutrophils in the development of vasculitis associated with MPO-ANCA and the target molecules of ANCA. In addition, the reactivities of ANCA and inflammatory cytokines involving leukocyte-derived chemotaxin 2 (LECT2) are also discussed.     

丙硫氧嘧啶相关性小血管炎和原发性小血管炎血清髓过氧化物酶抗体抗原决定簇结合谱的比较

目的比较丙硫氧嘧啶(PTU)相关性小血管炎和原发性小血管炎髓过氧化物酶(MPO)抗体的抗原决定簇结合谱.方法以人MPO制备的MPO亲和层析柱,分别从1例PTU相关性小血管炎和1例显微镜下型多血管炎(MPA)患者的血浆置换液中分离纯化MPO抗体(Pab1和Pab2),并经辣根过氧化物酶标记(Pab1-HRP和Pab2-HRP). 以Pab1-HRP和Pab2-HRP以及两种鼠抗人MPO单克隆抗体(3D8和6B9)分别作为识别MPO分子上不同抗原决定簇的探针,应用竞争性ELISA对10例PTU引起的抗中性粒细胞胞浆抗体(ANCA)阳性小血管炎患者和10例MPA患者血清中MPO抗体的抗原决定簇结合谱进行比较研究.结果 PTU组10例标本均可抑制3D8,平均抑制率为44.7%, 9/10例标本可抑制6B9, 平均抑制率为35.6%; MPA组10例标本均可抑制3D8和6B9, 平均抑制率分别为68.4%和62.2%, 与PTU组相比差异具有显著性(P<0.01).两组标本对Pab1-HRP的平均抑制率均达80%以上,MPA组标本对Pab2-HRP的抑制率均值显著大于PTU组(76.3% 比 58.9%, P<0.01).结论丙硫氧嘧啶相关性小血管炎和MPA患者血清中的MPO抗体均可识别MPO分子上多个抗原决定簇,二者识别的抗原决定簇有一定程度的交叉,但PTU组识别的抗原决定簇可能较局限.抗原决定簇结合谱的不同可能与临床表现的不同有关.