Neutrophil Cytoplasmic Antigens Research Articles

Neutrophil fixation protocols suitable for substrates to detect anti-neutrophil cytoplasmic antibodies by indirect immunofluorescence

Anti-neutrophil cytoplasmic antibodies (ANCAs) are autoantibodies that recognize neutrophil cytoplasmic antigens. The major ANCA antigens are myeloperoxidase and proteinase 3. Necrotizing small vessel vasculitis accompanied by ANCA production is called ANCA-associated vasculitis (AAV). In addition to AAV, ANCA is sometimes produced in patients with connective tissue diseases, such as systemic lupus erythematosus, and inflammatory bowel diseases. Indirect immunofluorescence (IIF) and enzyme immunoassay (EIA) have been used to detect ANCAs. Recently, the accuracy of EIA has improved and it has become the gold standard for ANCA detection. However, IIF does not lose its role in ANCA detection because EIA cannot detect ANCAs that recognize antigens other than those coated on the plate. For IIF, neutrophil substrates prepared with two different fixations, namely, ethanol fixation and formalin fixation, are used. There is a recommended protocol for ethanol fixation but not for formalin fixation. This study prepared neutrophil substrates according to the recommended protocol for ethanol fixation and protocols in the literature and original protocols for formalin fixation and then examined ANCA specificity and how storage period would influence the number of cells, antigen distribution, and antigenicity of the substrates. As a result, the number of cells and antigen distribution did not change after storage for up to 2 months regardless of fixation protocols, whereas a time-dependent decline in ANCA antigenicity and a fixation protocol-dependent difference in ANCA specificity were observed. How neutrophils are fixed on the glass slide needs to be checked upon evaluation of ANCAs by IIF.

Circulating argonaute-bound microRNA-126 reports vascular dysfunction and treatment response in acute and chronic kidney disease.

SummaryVascular and kidney dysfunction commonly co-exist. There is a need for biomarkers of vascular health. Circulating microRNAs are biomarkers; miR-126 is endothelial cell-enriched. We measured circulating miR-126 in rats with nephrotoxic nephritis (NTN) and humans with acute endothelial and renal injury (vasculitis associated with autoantibodies to neutrophil cytoplasm antigens (ANCAs)). We compared these findings to those from patients with chronic kidney disease (CKD) and end-stage renal disease (ESRD) and explored the relationship between miR-126 and vascular dysfunction. In NTN, miR-126 was reduced. In ANCA vasculitis (N = 70), pre-treatment miR-126 was reduced compared to health (N = 60) (88-fold). miR-126 increased 3.4-fold post-treatment but remained lower than in health (∼26-fold). Argonaute 2-bound miR-126 increased with ANCA vasculitis treatment. miR-126 did not differ between CKD (N = 30) and health but its concentration correlated with endothelial dysfunction. miR-126 was reduced in ESRD (N = 15) (∼350 fold). miR-126 may be a marker of vascular inflammation and could aid decision-making.

Comparative assessment of cardiac-specific autoantibodies levels in persons with occupational pathology caused by exposure to physical and chemical factors

Introduction. The pathology of the cardiovascular system is one of the dominant causes of mortality. It has been established that exposure to vibration and mercury is associated with the development of heart and vascular diseases. Specific autoantibodies can be used as markers of exposure effects. The aim of the work was a comparative assessment of the levels of cardiac-specific autoantibodies in individuals with vibrational disease (VD) and chronic mercury intoxication. Material and methods. We examined VD patients, with chronic mercury intoxication (CMI), who work in contact with a toxicant and in the long-term post-exposure period, and the comparison group. The relative content of specific autoantibodies to nitric oxide synthase (NOS), platelet membrane components (PMC), neutrophil cytoplasm, and vascular endothelial cell antigens (c-ANCA), plasminogen, collagen, and PAPP-A protein were studied in the patient’s blood serum. Results. In individuals with CMI, the levels of autoantibodies PCM, c-ANCA are lower for plasminogen and higher for collagen than in the comparison group and in VD patients. Elevated levels of anti-collagen antibodies were found in 70% of individuals with CMI. Among patients with CMI, elevated levels of antibodies to NOS were found in 60% of persons exposed to mercury and were not detected in the long-term post-exposure period. Discussion. The high frequency of elevated levels of antibodies to collagen and correlations between their level and the rest of the indices may indicate its important role in the development of endothelial dysfunction in persons with CMI. Elevated levels of autoantibodies to NOS in patients exposed to mercury are accompanied by a decrease in NO levels and may be an important part of the pathogenesis of endothelial dysfunction. Conclusion. The profile of cardiac-specific autoantibodies in VD patients is similar to that in the comparison group. Elevated levels of antibodies to collagen and decreased levels of antigens of platelets and plasminogen play an important role in the development of endothelial dysfunction in patients with CMI. The high frequency of hyper immunoreactivity of autoantibodies to NOS and c-ANCA, which is observed in patients with CMI who are in contact with a toxicant, decreases in the long-term post-exposure period.

Circulating Argonaute-Bound MicroRNA-126 Reports Vascular Dysfunction & Response to Treatment in Acute & Chronic Kidney Disease

Vascular and kidney dysfunction commonly co-exist. There is an unmet need for biomarkers of vascular health. Circulating microRNAs (miRs) are disease biomarkers; miR-126 is endothelial cell-enriched. We measured circulating miR-126 in rats with nephrotoxic nephritis (NTN) and humans with acute endothelial and renal injury (vasculitis associated with autoantibodies to neutrophil cytoplasm antigens (ANCA)). We then compared these findings to those from patients with chronic kidney disease (CKD) and end-stage renal disease (ESRD) and explored the relationship between miR-126 and markers of vascular dysfunction. In rats, NTN was induced with nephrotoxic serum. Samples were prospectively collected from 70 patients with ANCA vasculitis (at presentation and once in treatment-induced remission), healthy subjects (n=60), patients with CKD (n=30) and ESRD before and after dialysis (n=15). In humans and rats, miR-126 and miR-122 (liver-specific control) were measured and correlated with vascular function. In NTN rats, miR-126 was selectively reduced. In ANCA vasculitis, pre-treatment circulating miR-126 was reduced compared to health (88-fold reduction, ROC-AUC 0.87 (0.80-0.94)). miR-126 increased 3.4-fold post-treatment but remained lower than in health (~26-fold). There was no change in miR-122. Plasma fractionation demonstrated that argonaute 2-bound miR-126 increased with treatment of ANCA vasculitis. Urinary miR-126 decreased post-treatment. miR-126 did not differ between CKD and health but its concentration significantly correlated with measures of endothelial dysfunction. miR-126 was substantially reduced in ESRD (~350 fold compared to health and CKD). miR-126 may be a marker of vascular inflammation and has the potential to aid in clinical decision-making.

Linked help from bacterial proteins drives autoantibody production in small vessel vasculitis

The small vessel vasculitides granulomatosis with polyangiitis (GPA) and microscopic polyangiitis are associated with autoantibodies to neutrophil cytoplasm antigens (ANCA), principally proteinase-3 (PR3) and myeloperoxidase (MPO). There is an association between GPA and nasal carriage of Staphylococcus aureus. The recent finding that S. aureus produces proteins that bind tightly to and block the function of both PR3 and MPO suggests a mechanism for ANCA formation. The bacterial protein-autoantigen conjugate is recognised by B cells with ANCA specificity, internalised, and the bacterial protein processed and presented to T cells with specificity for bacterial peptides. The T cell can then provide help to the B cell, allowing class switching, affinity maturation and the production of pathogenic ANCA. This mechanism predicts that T cells with this specificity will be found in patients, and that the bacterial protein-autoantigen conjugate will be particularly efficient at eliciting ANCA production.

ANCA-Associated Vasculitis Pathogenesis: A Commentary.

The ANCA-associated vasculitides are a group of small vessel vasculitides characterized by autoantibodies recognizing the neutrophil cytoplasmic antigens PR3 and MPO. We examine the current clinical and molecular immunology understanding of ANCA-associated vasculitides and discuss the current needs in our understanding of the pathogenic mechanisms of these rare diseases. The majority of efforts to understand the pathogenesis of these diseases have focused on dissecting neutrophil biology because the neutrophil is the primary expressor of ANCA autoantigens. However, a number of important genetic, clinical, and cellular biology observations suggest that attempts to understand the pathogenesis of ANCA vasculitides should move away from emphasis on the role of the neutrophil and instead re-focus on the potential role of other immune cell mediators. Whether or not neutrophils are the key determinant of ANCA-associated vasculitis pathogenesis should be revisited in detail. A neutrophil-centric view of the pathogenesis of these diseases cannot fully account for important genetic, clinical, and cellular biology observations that implicate important and under-appreciated roles for monocytes and T cells. Refocusing on these findings will likely lead to new discovery of novel therapeutic targets and the identification of clinically useful biomarkers for disease activity.

A Case of Rituximab Use as an Induction and Maintenance of Remission in ANCA-Associated Vasculitis

Antineutrophil cytoplasmic antibody- (ANCA-) associated vasculitis (AAV) is a multisystem autoimmune disease affecting mainly microscopic blood vessels due to circulating autoantibodies against neutrophil cytoplasmic antigens. We report a case of a 57-year-old female patient presenting with hemoptysis, sinusitis, and conjunctivitis. Based on lung biopsy, the diagnosis of antineutrophil cytoplasmic antibody- (ANCA-) associated vasculitis (AAV) was established. She was put on rituximab as induction and maintenance therapy. She responded initially to rituximab as induction therapy but failed to respond in the maintenance course of the drug. Rituximab was stopped and mycophenolate mofetil was administered. She responded as laboratory c-ANCA titers turned negative and symptoms subsided. There are no randomized clinical trials addressing rituximab effect in induction and remission at the same time. This case report doubts the efficacy of the use of rituximab therapy for both induction and maintenance of remission at the same time, waiting for the results of the ongoing trials.

Autoantibodies in renal diseases - clinical significance and recent developments in serological detection.

Autoimmune dysfunctions are the “bête noire” in a range of debilitating nephropathies. Autoimmune-mediated damage to the kidneys can be triggered by autoantibodies directed against specific proteins or renal structures, for example, the phospholipase A2 receptor or the glomerular basement membrane, resulting in glomerular diseases such as primary membranous nephropathy or Goodpasture’s disease. Moreover, secondary damage to the kidney can be part of the wide-reaching effects of systemic autoimmune diseases such as vasculitis or systemic lupus erythematosus (SLE) – the latter counts lupus nephritis among its most severe manifestations. Systemic autoimmune diseases are characterized by non-organ-specific autoantibodies, directed for example against neutrophil cytoplasmic antigens in systemic vasculitis and against double-stranded DNA and nucleosomes in SLE. A large variety of innovative and highly specific and sensitive autoantibody tests have been developed in the last years that are available to identify autoimmune kidney diseases at an early stage. Thus, serological in vitro diagnostics allow for appropriate interventional therapy in order to prevent disease progression often resulting in need of dialysis and transplantation.

Twenty-five years of European Union collaboration in ANCA-associated vasculitis research.

This special edition reviews the progress in understanding of systemic vasculitis associated with autoantibodies to neutrophil cytoplasmic antigens (ANCA). European research groups have contributed to this research including the original observations of the association between ANCA and vasculitis. Areas of interest include classification and epidemiology, genetics and pathogenesis, disease assessment, histology and long-term outcomes. Clinical trials conducted by the European Vasculitis Study group have helped to define the current standard of care for the treatment of patients with vasculitis and provided a platform for the investigation of newer therapies. The prognosis of patients with ANCA-associated vasculitis has improved over this period as a result of facilitated diagnosis and development of consensus, evidence-based, treatment recommendations. The ANCA story represents an example of the power of a biomarker in influencing a disease area, inspiring research and providing physicians with better tools to treat patients with these disorders.

SAT0183 Autoantibodies for Several Antigens in Neutrophil Cytoplasm other than PR3 and MPO Promote Release of Nets from Neutrophils

BackgroundNeutrophil extracellular traps (NETs) were first described as web-like structures that trap and neutralize microbes at sites of infection. NETs are comprised of chromatin components and neutrophil cytoplasmic proteins. Because...

Cutaneous vasculitis: Report of 117 cases

Proteinase-3 mRNA expressed by glomerular epithelial cells correlates with crescent formation in Wegener's granulomatosis.Wegener's granulomatosis (WG) is characterized by systemic vasculitis with crescentic glomerulonephritis (CGN) and circulating autoantibodies directed against neutrophil cytoplasmic antigens (ANCA). Proteinase 3 (PR-3), a neutral serine proteinase in neutrophils implicated in the growth control of myeloid cells, has been identified as the target antigen for ANCA in WG. Since the kidneys are frequently involved in WG, we studied the in situ expression of PR-3 by renal parenchymal cells.We assessed the expression of PR-3 in kidney biopsies of 15 patients with WG by immunohistochemistry (IHC) and in situ hybridization (ISH). Normal kidney tissue served as the control.We detected PR-3 mRNA and PR-3 protein in distal tubular epithelial cells (TECs) and glomerular epithelial cells (GECs) in normal kidney tissue and in CGN. Furthermore, a strong glomerular PR-3mRNA expression restricted to the site of cellular crescents was detected in patients with WG. The analysis of 144 glomeruli with cellular or sclerotic crescents revealed a positive correlation of glomerular PR-3mRNA expression with the percentage of cellular crescents per glomerulus. The capability of human TECs and GECs to synthesize PR-3 was confirmed by Northern blot and ISH on cultured cells.These data provide evidence that nonhematopoetic renal parenchymal cells express PR-3 and that glomerular expression of PR-3 is associated with crescent formation in WG. Our findings suggest that renal parenchymal cells may directly be involved in the pathogenesis of CGN in WG.

Severe warm autoimmune haemolytic anaemia due to anti-Jk(a) autoantibody associated with Parvovirus B19 infection in a child.

Severe warm autoimmune haemolytic anaemia due to anti-Jk(a) autoantibody associated with Parvovirus B19 infection in a child.

Hypereosinophilic syndrome induced cystitis mimicking bladder tumor

Hypereosinophilic syndrome induced cystitis mimicking bladder tumor

Azathioprine Hypersensitivity Presenting as Cardiogenic Shock and Sweet's Syndrome in a Patient with Microscopic Polyangiitis

Azathioprine hypersensitivity is a clinical syndrome which may manifest from isolated fever and rash to multi-organ failure. This rare condition is usually self-limiting following the discontinuation of azathioprine. Therefore, it is important to maintain a high index of clinical suspicion for hypersensitivity reactions with azathioprine therapy. We report a case of azathioprine hypersensitivity in a 69-year-old woman who developed cardiogenic shock and Sweet's syndrome following the initiation of azathioprine for her underlying autoantibodies to neutrophil cytoplasmic antigens (ANCA) associated microscopic polyangiitis.

Acetylcysteine as Adjuvant Therapy for Vasculitis Associated with Antineutrophil Cytoplasmic Antibody

To the Editor: Antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis, including Wegener’s granulomatosis (WG) and microscopic polyangiitis, is a multisystem autoimmune disorder characterized by vasculitis predominantly affecting microscopic vessels and circulating autoantibodies to neutrophil cytoplasmic antigens. Treatment of this vasculitis has 2 main components, induction of remission and maintenance immunosuppressive therapy to prevent relapse. Recently, new treatments have been used, such as rituximab1,2,3, although the combination of cyclophosphamide and glucocorticoids is the preferred regimen as initial immunosuppressive therapy. Once remission is induced with cyclophosphamide, patients are switched to maintenance treatment with less toxic immunosuppressive drugs, usually methotrexate or azathioprine. … Address correspondence to Dr. Fernández-Fernández; E-mail: fjf-fernandez{at}terra.es

Pathogenesis of small vessel vasculitis associated with autoantibodies to neutrophil cytoplasmic antigens: new insights from animal models

Morbidity and mortality associated with current treatment strategies in ANCA associated small vessel vasculitis (AASV) are unacceptably high and more specific therapies will require more detailed knowledge of the pathogenesis of the disease. In-vitro experiments have provided invaluable insight into the molecular mechanisms of antibody action and their subcellular effects; however, they may not reflect the in-vivo situation that can only be assessed in animal models. Rodent models provide convincing evidence that myeloperoxidase (MPO) and antibodies to it can cause small vessel vasculitis but the development of rodent models of anti-proteinase 3 (PR3) antibody mediated injury is proving much more problematic. Insight into the molecular differences of the human and mouse antigens and antibodies to them as well as analysis of the molecular interaction with their binding partner(s) have highlighted potential resolutions to this discrepancy. The recent characterization of autoimmunity to lysosomal membrane glycoprotein-2 (LAMP-2) in AASV and the possible inductions of autoantibodies to it by molecular mimicry open an entirely new area for study. Recent advances in the development of animal models that more faithfully model the disease and the discovery of novel ANCA antigens such as LAMP-2 provide new opportunities to dissect the mechanisms involved in the pathogenesis of AASV.

Long-term treatment results and the immunoglobulin G subclass distribution patterns of proteinase-3-antineutrophil cytoplasm antibody (ANCA) and myeloperoxidase-ANCA in ANCA-associated vasculitis

Small vessel vasculitis associated with antibodies to neutrophil cytoplasm antigens has been denominated antineutrophil cytoplasm antibody (ANCA)-associated vasculitis (AAV). Ninety-eight patients with various forms of AAV with renal involvement were studied retrospectively with regard to treatment, side-effects and outcome. The immunoglobulin G (IgG) subclass distribution patterns in serum were determined in 51 patients with nephelometry and those of anti-proteinase-3 (PR3) and anti-myeloperoxidase (MPO) in 44 patients by enzyme-linked immunosorbent assay. Fifty-nine patients with a mean age of 63 years were given treatment with intermittent intravenous regimens of cyclophosphamide and continuous corticosteroids, whereas 39 patients with a mean age of 58 years were given continuous oral treatment. Malignancy, mainly due to skin tumours, was more common in AAV than in the general population. The total IgG subclass distribution pattern was asymmetric. The response to PR3 was of IgG(1), IgG(3) and IgG(4) isotypes, while IgG(1) and IgG(3) predominated in the response to MPO. The aberrant IgG subclass distribution pattern detected in the autoantibodies may be of importance in the pathogenesis of AAV.

Molecular mimicry in pauci-immune focal necrotizing glomerulonephritis

Pauci-immune focal necrotizing glomerulonephritis (FNGN) is a severe inflammatory disease associated with autoantibodies to neutrophil cytoplasmic antigens (ANCA). Here we characterize autoantibodies to lysosomal membrane protein-2 (LAMP-2) and show that they are a new ANCA subtype present in almost all individuals with FNGN. Consequently, its prevalence is nearly twice that of the classical ANCAs that recognize myeloperoxidase or proteinase-3. Furthermore, antibodies to LAMP-2 cause pauci-immune FNGN when injected into rats, and a monoclonal antibody to human LAMP-2 (H4B4) induces apoptosis of human microvascular endothelium in vitro. The autoantibodies in individuals with pauci-immune FNGN commonly recognize a human LAMP-2 epitope (designated P(41-49)) with 100% homology to the bacterial adhesin FimH, with which they cross-react. Rats immunized with FimH develop pauci-immune FNGN and also develop antibodies to rat and human LAMP-2. Finally, we show that infections with fimbriated pathogens are common before the onset of FNGN. Thus, FimH-triggered autoimmunity to LAMP-2 provides a previously undescribed clinically relevant molecular mechanism for the development of pauci-immune FNGN.

Cutaneous vasculitis in breast cancer treated with chemotherapy

A patient from the University of California Los Angeles Medical Center who developed cutaneous vasculitis during the course of treatment for metastatic breast cancer is presented (status: post-lumpectomy and radiation therapy). Since the onset of vasculitis occurred during the course of therapy for the neoplasm, it was difficult to differentiate between drug-induced vasculitis and paraneoplastic vasculitis. The patient had been exposed to medications including gabapentin, methimazole, trastuzumab, fulvestrant, and letrozole — which could cause endothelial cell toxicity. Drug-induced small vessel vasculitis usually attacks the skin or subcutaneous parts of the skin. In cancer therapy, there have been case reports that hormonal drugs such as estrogen receptor antagonists, aromatase inhibitors, and epidermal growth factor receptor (EGFR) inhibitors can induce cutaneous vasculitis. On the other hand, paraneoplastic syndromes manifested as cutaneous vasculitis have been documented, possibly mediated by unknown immunological mechanisms associated with the tumor such as formation of immune complexes, direct antibody-mediated effects on endothelial cells, or direct effects of tumor cells on the vascular wall. Some patients with drug-induced cutaneous vasculitis have antineutrophil cytoplasm antibodies (ANCA) directed to one or more neutrophil cytoplasm antigens — the most common being granule protein myeloperoxidase (MPO), human leukocyte elastase (HLE), cathepsin G and lactoferrin. Some patients also have antibodies against histones and antiphospholipid. Serologic testing and measurements suggest an influence of therapy on vasculitis, yet the lack of sensitivity and specificity for a biomarker in endothelial injury indicate the need to search and evaluate new markers for improved predictive value of the tests, and to provide guidance in therapy.

CpG oligodeoxynucleotide stimulates production of anti-neutrophil cytoplasmic antibodies in ANCA associated vasculitis.

BackgroundWegener's Granulomatosis and Microscopic Polyangiitis are life-threatening systemic necrotizing vasculitides of unknown aetiology. The appearance of circulating antibodies to neutrophil cytoplasmic antigens (ANCA) is strongly associated with the development of the disease. A link between infection and disease has long been suspected, and the appearance of ANCA antibodies has been reported following bacterial and viral infections. The depletion of circulating B cells with monoclonal antibody therapy can induce remission, and this observation suggests a pathogenic role for B cells in this disease. As bacterial DNA is known to induce B cell proliferation and antibody production via TLR-9 stimulation, we have explored the possibility that unmethylated CpG oligodeoxynucleotide, as found in bacterial and viral DNA, may play a role in stimulating circulating autoreactive B cells to produce ANCA in patients with vasculitis.ResultsWe have confirmed that unmethylated CpG oligonucleotide is a potent stimulator of antibody production by PBMC in vitro. The stimulation of PBMC with CpG oligonucleutides resulted in the production of similar amounts of IgG in both ANCA+ patients and normal controls. In spite of this, PR3 ANCA+ patients synthesised significantly higher amount of IgG ANCA than normal controls. In MPO ANCA+ patients, there was a tendency for patients to produce higher amount of ANCA than controls, however, the difference did not reach significance. Furthermore, we were able to detect circulating MPO-reactive B cells by ELISpot assay from the peripheral blood of 2 MPO+ ANCA vasculitis patients. Together, this indicates that circulating anti-neutrophil autoreactive B cells are present in ANCA+ vasculitis patients, and they are capable of producing antibodies in response to CpG stimulation. Of note, CpG also induced the production of the relevant autoantibodies in patients with other types of autoimmune diseases.ConclusionCirculating ANCA autoreactive B cells are present in patients with ANCA+ vasculitis. The production of ANCA from these cells in response to unmethylated CpG stimulation lead us to propose that stimulation of these cells by immunostimulatory DNA sequences such as CpG oligodeoxynucleotide during infection may provide a link between infection and ANCA associated vasculitis. This phenomenon may also apply to other antibody mediated autoimmune diseases.