Dysregulation of Autoantigen Genes in ANCA-Associated Vasculitis Involves Alternative Transcripts and New Protein Synthesis (original) (raw)

Epigenetic basis for aberrant upregulation of autoantigen genes in humans with ANCA vasculitis

Journal of Clinical Investigation, 2010

Patients with ANCA aberrantly express neutrophil granule-encoding genes, including 2 that encode autoantigens: proteinase 3 (PR3) and myeloperoxidase (MPO). To uncover a potential transcriptional regulatory mechanism for PR3 and MPO disrupted in patients with ANCA vasculitis, we examined the PR3 and MPO loci in neutrophils from ANCA patients and healthy control individuals for epigenetic modifications associated with gene silencing. We found that levels of the chromatin modification H3K27me3, which is associated with gene silencing, were depleted at PR3 and MPO loci in ANCA patients compared with healthy controls. Interestingly, in both patients and controls, DNA was unmethylated at a CpG island in PR3, whereas in healthy controls, DNA was methylated at a CpG island in MPO. Consistent with decreased levels of H3K27me3, JMJD3, the demethylase specific for H3K27me3, was preferentially expressed in ANCA patients versus healthy controls. In addition, we describe a mechanism for recruiting the H3K27 methyltransferase enhancer of zeste homolog 2 (EZH2) to PR3 and MPO loci mediated by RUNX3. RUNX3 message was decreased in patients compared with healthy controls, and may also be under epigenetic control. DNA methylation was increased at the RUNX3 promoter in ANCA patients. These data indicate that epigenetic modifications associated with gene silencing are perturbed at ANCA autoantigen-encoding genes, potentially contributing to inappropriate expression of PR3 and MPO in ANCA patients.

Increased monocyte transcription of the proteinase 3 gene in small vessel vasculitis

Clinical and Experimental Immunology, 2005

Proteinase 3 (PR3) is a pleiotropic and destructive serine protease and it is also a major target for autoantibodies in systemic small vessel vasculitis. We have shown recently that patients in stable remission have increased circulating levels of PR3, independent of autoantibody titre, inflammation, neutrophil degranulation and renal function. Here we explore the possibility of increased PR3 gene transcription. RNA was purified from peripheral blood monocytes from vasculitis patients and controls. Specific mRNA was measured by Taq Man real-time polymerase chain reaction (PCR). The monocytelike cell lines THP-1 and U937 and human peripheral blod monocytes from healthy controls were stimulated with cytokines and lipopolysaccharide (LPS) for different time periods. PR3 protein was measured in plasma with enzymelinked immunosorbent assay (ELISA). The median result for PR3 mRNA was 9·6 (1·8-680) for 22 patients, compared to 1 (0·1-2·8) for the 15 healthy controls. Elastase expression was also significantly increased, whereas myeloperoxidase and interleukin-8 were not. Stimulation of monocytes with tumour necrosis factor (TNF)-a a a a , interferon (IFN)-g g g g or LPS did not result in any increase of PR3 or elastase transcription, whereas interleukin (IL)-8 transcription was increased 10-fold. Circulating monocytes from patients with systemic vasculitis display increased PR3 gene transcription compared to healthy controls and patients with sytemic lupus erythematosus (SLE). This may be important for the development of vasculitis. Our results do not favour a role for cytokines, antineutrophil cytoplasmic antibodies (ANCA) or immunosuppressive medication in the upregulation of PR3 transcription in vasculitis.

Neutrophil Membrane Expression of Proteinase 3 (PR3) Is Related to Relapse in PR3-ANCA-Associated Vasculitis

Journal of the American Society of Nephrology, 2002

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 Ϫ -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

Increased circulating levels of proteinase 3 in patients with anti-neutrophilic cytoplasmic autoantibodies-associated systemic vasculitis in remission

Clinical and Experimental Immunology, 2003

In systemic small vessel vasculitides, patients form autoantibodies against neutrophil granular proteins, anti-neutrophilic cytoplasmic autoantibodies (ANCA). Some correlation is seen between ANCA titre and disease activity, but whether this is cause or effect is still unknown. It has been reported that levels of proteinase 3 (PR3), one of the main ANCA antigens, are increased in patients with active disease. An increased level of circulating antigen could mean a predisposition to autoimmunity. In order to explore this we measured PR3 levels in patients with stable disease. In addition we measured neutrophil gelatinase-associated lipocalin (NGAL) as a specific marker of neutrophil degranulation, cystatin C as a marker of renal function as well as C-reactive protein (CRP), IL-6 and sTNFr1 as markers of inflammation. PR3, NGAL, IL-6 and sTNFr1 were measured in plasma by the ELISA technique. In the PR3 ELISA, we used anti-PR3 monoclonal antibodies as capture-antibodies and affinity-purified rabbitanti-PR3 antibodies for detection. PR3-ANCA, myeloperoxidase (MPO)-ANCA, CRP and cystatin C were measured by routine methods. PR3 was significantly raised ( P < 0·0001) in vasculitis patients (median 560 m g/l, range 110-3940, n = 59) compared with healthy blood donors (350 m g/l, 110-580, n = 30) as well as disease controls (360, 110-580, n = 46). No correlation was seen with disease activity, inflammation or renal function. The raised NGAL levels correlated strongly with decreased renal function ( r = 0·8, P < 0·001). After correcting for this, slightly increased levels (110, 42-340, n = 59) were observed compared with healthy blood donors (81, 38-130, n = 25), but not compared with the disease controls (120, 57-260, n = 48). In the disease controls, there was a significant correlation between NGAL and proteinase 3 ( r = 0·3, p < 0·05), but this was not the case in the vasculitis patients. Whether patients had PR3-ANCA or MPO-ANCA was of no significance. In our measurements, we found significantly raised levels of PR3 in plasma from patients with small vessel vasculitis, regardless of ANCA specificity. This was not due to decreased renal function, ongoing inflammation or neutrophil activation. Plausible mechanisms for this include defects in the reticuloendothelial system, genetic factors and selective neutrophil degranulation or leakage.

T cell responses to myeloperoxidase (MPO) and proteinase 3 (PR3) in patients with systemic vasculitis

Clinical and Experimental Immunology, 1996

SUMMARY T cell-mediated immune responses are likely to be important in the pathogenesis of systemic vasculitis. However, identifying the T cells involved has proved difficult, and there are conflicting reports regarding T cell proliferation in response to different autoantigens. Perinuclear (P) and cytoplasmic (C) anti-neutrophil cytoplasmic antibodies (ANCA) are closely associated with systemic vasculitis, and are generally specific for MPO or PR3, respectively. We studied the proliferative responses to MPO and PR3 of peripheral blood mononuclear cells from patients with P-ANCA or C-ANCA specific for these antigens by ELISA. These responses were compared with those of normal controls, and of disease controls with P- or C-ANCA not specific for MPO or PR3. The patient group as a whole showed significant T cell proliferation in response to the autoantigens compared with controls (P=0.005). Cells from nine of 13 P-ANCA-positive, anti-MPO-positive patients proliferated in response to MP...

Neutrophil-related gene expression and low-density granulocytes associated with disease activity and response to treatment in ANCA-associated vasculitis

Arthritis & rheumatology (Hoboken, N.J.), 2015

To discover biomarkers involved in the pathophysiology of ANCA-associated vasculitis (AAV) and determine if low-density granulocytes (LDGs) contribute to gene expression signatures in AAV. The source of clinical data and linked biospecimens was a randomized controlled treatment trial in AAV. RNA-sequencing of whole blood from patients with AAV was performed during active disease at the baseline visit (BL) and during remission 6 months later (6M). Gene expression was compared between patients who met versus did not meet the primary trial outcome of clinical remission at 6M (responders vs. nonresponders). Measurement of neutrophil-related gene expression was confirmed in PBMCs to validate findings in whole blood. A negative selection strategy isolated LDGs from PBMC fractions. Differential expression between responders (n=77) and nonresponders (n=35) was detected in 2,346 transcripts at BL visit (p<0.05). Unsupervised hierarchical clustering demonstrated a cluster of granulocyte-re...

Immunopathogenesis of ANCA-Associated Vasculitis

International Journal of Molecular Sciences, 2020

Anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis is an autoimmune disorder which affects small- and, to a lesser degree, medium-sized vessels. ANCA-associated vasculitis encompasses three disease phenotypes: granulomatosis with polyangiitis (GPA), microscopic polyangiitis (MPA), and eosinophilic granulomatosis with polyangiitis (EGPA). This classification is largely based on clinical presentations and has several limitations. Recent research provided evidence that genetic background, risk of relapse, prognosis, and co-morbidities are more closely related to the ANCA serotype, proteinase 3 (PR3)-ANCA and myeloperoxidase (MPO)-ANCA, compared to the disease phenotypes GPA or MPA. This finding has been extended to the investigation of biomarkers predicting disease activity, which again more closely relate to the ANCA serotype. Discoveries related to the immunopathogenesis translated into clinical practice as targeted therapies are on the rise. This review will summarize...