Abraham Rutgers

Disturbed B cell homeostasis in newly diagnosed giant cell arteritis and polymyalgia rheumatica

Several lines of evidence indicate that B cells may be involved in the immunopathology of giant cell arteritis (GCA) and polymyalgia rheumatica (PMR). This study was undertaken to examine the distribution of defined B cell subsets, including effector B (Beff) cells and regulatory B (Breg) cells, in patients with GCA and patients with PMR before and after corticosteroid treatment.

Neutrophil myeloperoxidase activity and the influence of two single-nucleotide promoter polymorphisms

Summary.  Myeloperoxidase (MPO) catalyses the formation of hypochlorous acid and is involved in many (patho)physiological processes. The present study was designed to determine the effect of two MPO promoter polymorphisms (463G/A and 129G/A) on enzyme activity. In 243 healthy controls, genotypes were determined and MPO activity was measured on a single‐cell level using a haematological analyser. The 129G/A polymorphism reduces MPO activity in neutrophils, whereas for the 463G/A polymorphism, only gender‐dependent differences in MPO activity in older age groups could be found. When studying these polymorphisms in disease, therefore, age and gender should be included in the analysis.

Serum markers associated with disease activity in giant cell arteritis and polymyalgia rheumatica

OBJECTIVE To compare multiple serum markers for their ability to detect active disease in patients with GCA and in those with PMR. METHODS Twenty-six markers related to immune cells that may be involved in GCA and PMR were determined by ELISA and multiplex assay in the serum of 24 newly diagnosed, untreated GCA/PMR patients, 14 corticosteroid (CS)-treated GCA/PMR patients in remission and 13 healthy controls. Receiver operating characteristic analysis with area under the curve and Spearmans correlation coefficients were performed. RESULTS Serum B-cell activating factor (BAFF), CXCL9 and IL-6 were increased in newly diagnosed GCA and PMR patients. Serum CCL2, CCL11, IL-10 and sIL-2R were modulated in GCA patients only and CXCL10 in PMR patients only. BAFF, CXCL9 and IL-6 accurately distinguished newly diagnosed GCA and PMR patients from healthy controls, as shown by area under the curve > 0.80. Upon CS-induced remission, serum BAFF and IL-6 decreased significantly in both GCA and PMR patients, whereas CXCL9 remained high. Serum BAFF and IL-6 correlated strongly with ESR and CRP in GCA and PMR patients. CONCLUSION Among the serum markers tested, BAFF and IL-6 showed the strongest association with disease activity in both GCA and PMR patients. The diagnostic value of these markers should be evaluated in larger, longitudinal studies with GCA and PMR patients, and in patients with infections or other inflammatory conditions.

ANCA-GBM dot-blot: Evaluation of an assay in the differential diagnosis of patients presenting with rapidly progressive glomerulonephritis

Rapidly progressive glomerulonephritis (RPGN) is characterized by rapid and progressive loss of renal function and the presence of crescentic glomerulonephritis (CGN). Early diagnosis and appropriate treatment is mandatory to prevent death and/or renal failure. We have evaluated an ANCA-GBM dot-blot diagnostic test in terms of sensitivity, specificity, and inter-observer effect in consecutive patients with RPGN (n = 82). Control sera (n = 34) included healthy and relevant disease controls. Dot-blots were independently evaluated by nine observers. Proteinase 3 (PR3)-ANCA, myeloperoxidase (MPO)-ANCA, and both were detected by ELISA in 36, 32, and 3 samples of 71 patients with pauci-immune CGN, respectively. Two additional samples were ANCA negative. The dot-blot revealed a sensitivity of 92–95% for PR3-ANCA and 80–86% for MPO-ANCA. The specificity of the dot-blot for PR3- and MPO-ANCA was 100%. In the patients with anti-GBM nephritis (n = 9) anti-GBM was detected by both ELISA and dot-blot (sensitivity: 100%). The specificity of the anti-GBM dot-blot was 91–94%. However, the inter-observer effect was relatively high for detection of anti-GBM antibodies (24%). In conclusion, the ANCA-GBM dot-blot is a useful screening tool in situations where conventional ANCA testing is not readily available with excellent performance for PR3-ANCA detection, but less optimal sensitivity for MPO-ANCA and specificity for anti-GBM detection. Therefore, it is recommended to include the following advises in the report to the physicians: 1) patients with a high clinical suspicion for MPO-ANCA-associated RPGN and negative dot-blot must have conventional analysis for MPO-ANCA, and 2) negative anti-GBM dot-blot makes anti-GBM disease very unlikely, but positive samples should be confirmed by conventional anti-GBM tests.

Refractory disease in antineutrophil cytoplasmic antibodies associated vasculitis

Purpose of reviewInduction treatment of antineutrophil cytoplasmic antibodies (ANCA) associated vasculitis (AAV) is not always successful and nonresponding patients are considered refractory. Recent findingsRefractory disease should be subdefined to the treatment that was received. Cyclophosphamide refractory AAV occurs in up to 5% of patients. Many more patients develop contraindications to cyclophosphamide or relapse frequently. The latter two patient groups might also benefit from treatment used for cyclophosphamide refractory AAV. SummaryThe most promising drug for treating refractory AAV is rituximab.

Altered B cell balance, but unaffected B cell capacity to limit monocyte activation in anti-neutrophil cytoplasmic antibody-associated vasculitis in remission

OBJECTIVE Regulatory B cells (Bregs) constitute a subset of B cells with immunomodulatory properties. Numerical and functional alterations in the Breg compartment have been associated with autoimmunity. The aim of this study was to assess the frequency and function of Bregs in patients with ANCA-associated vasculitis (AAV). METHODS B cell subsets were determined in the peripheral blood of 48 AAV patients (12 active, 36 in remission) and 41 healthy controls (HCs) by flow cytometry. Bregs were defined within the CD19(+) population as CD24(hi)CD38(hi) or CD24(hi)CD27(+) cells. The percentage of IL-10-positive B cells in circulation was analysed by flow cytometry. Sorted CD19(+) B cells were co-cultured with monocytes to evaluate their capacity to inhibit monocyte TNF-α production upon lipopolysaccharide stimulation. RESULTS The frequency of circulating CD19(+)CD24(hi)CD38(hi) cells was not different in AAV patients in remission compared with HCs, but was decreased in patients with active disease [mean in HCs 5.5% (s.d. 1.6) vs active 3.8% (s.d. 2.8), P = 0.0104]. Furthermore, the percentage of CD19(+)CD24(hi)CD27(+) cells was significantly decreased in both remission and active patients when compared with HCs [HCs 15.0% (s.d. 9.3) vs remission 6.6% (s.d. 4.4) (P < 0.0001) vs active 6.4% (s.d. 6.2) (P = 0.0006)]. The frequency of IL-10-positive B cells was comparable between patients and HCs. B cells from AAV patients suppressed monocyte TNF-α production to a similar extent to cells from HCs. CONCLUSION Based on immunophenotypic classification, Bregs are numerically diminished in AAV patients. However, B cell function in terms of IL-10 production and their capacity to suppress monocyte activation is not compromised in AAV patients in remission.

Different Scoring Methods of FDG PET/CT in Giant Cell Arteritis : Need for Standardization

Abstract Giant cell arteritis (GCA) is the most frequent form of vasculitis in persons older than 50 years. Cranial and systemic large vessels can be involved. [18F] fluorodeoxyglucose (FDG) positron emission tomography (PET)/computed tomography (CT) is increasingly used to diagnose inflammation of the large arteries in GCA. Unfortunately, no consensus exists on the preferred scoring method. In the present study, we aim to define the optimal FDG PET/CT scoring method for GCA diagnosis using temporal artery biopsy and clinical diagnosis as the reference method. FDG PET/CT scans of GCA patients (12 glucocorticoid-naive, 6 on glucocorticoid treatment) and 3 control groups (inflammatory, atherosclerotic, and normal controls) were evaluated. We compared 2 qualitative visual methods (i.e. (1a) first impression and (1b) vascular uptake versus liver uptake) and 4 semiquantitative methods ((2a) SUVmax aorta, (2b) SUVmax aorta-to-liver ratio, (2c) SUVmax aorta-to-superior-caval-vein ratio, and (2d) SUVmax aorta-to-inferior-caval-vein ratio). FDG uptake pattern (diffuse or focal) and presence of arterial calcifications were also scored. Diagnostic accuracy of the visual method vascular versus liver uptake (1b) was highest when the cut-off point “vascular uptake higher than liver uptake” (sensitivity 83%, specificity 91%) was used. Sensitivity increased to 92% when patients on glucocorticoids were excluded from the analysis. Regarding the semiquantitative methods, the aorta-to-liver ratio (2b) with a cutoff of 1.03 had the highest diagnostic accuracy, with a sensitivity and specificity of 69% and 92%, respectively. Sensitivity increased to 90% when patients on glucocorticoids were excluded. The number of vascular segments with diffuse FDG uptake pattern was significantly higher in GCA patients without glucocorticoid use compared with all control patient groups. CRP was not significantly different between positive and negative FDG PET scans in the GCA group. Visual vascular uptake higher than liver uptake resulted in the highest diagnostic accuracy for the detection of GCA, especially in combination with a diffuse FDG uptake pattern. Of the semiquantitative methods, the aorta-to-liver SUVmax ratio (cutoff point = 1.03) had the highest diagnostic accuracy. The diagnostic accuracy increased when patients using glucocorticoids were excluded from the analyses.

Anti-neutrophil cytoplasmic autoantibody pathogenicity revisited: pathogenic versus non-pathogenic anti-neutrophil cytoplasmic autoantibody

Anti-neutrophil cytoplasmic autoantibody (ANCA)-associated vasculitis (AAV) is strongly associated with autoantibodies against myeloperoxidase (MPO) and proteinase 3 (PR3). No clear consensus has been reached on the pathogenicity of these autoantibodies. Animal models for MPO-ANCA, in vitro data suggesting pathogenicity of ANCA, and one case of a neonate showing symptoms of vasculitis after transplacental transfer of MPO, argue in favour of a pathogenic role for ANCA. On the other hand, the presence of natural MPO and PR3 autoantibodies in healthy individuals, lack of a strong correlation between ANCA titres and disease activity, and the occurrence of ANCA-negative AAV patients argue against pathogenicity of ANCA. Recent papers have drawn attention to the possibility of epitope specificity defining ANCA pathogenicity. Certain MPO epitopes were found to be specific for active disease, and others remained present during remission or were also present in healthy individuals. One linear epitope, aa447-459, was not only exclusive for active disease, but also detected in the total Ig fraction of ANCA-negative patients, reactivity being masked in serum by ceruloplasmin. So, not all ANCA seems to be equal, some could be pathogenic while others are not. For development of an autoimmune response, a specific ANCA repertoire is required, which may occur through intra-molecular epitope spreading in patients.

Decreased CXCR1 and CXCR2 expression on neutrophils in anti-neutrophil cytoplasmic autoantibody-associated vasculitides potentially increases neutrophil adhesion and impairs migration

IntroductionIn anti-neutrophil cytoplasmic autoantibody (ANCA)-associated vasculitides (AAV), persistent inflammation within the vessel wall suggests perturbed neutrophil trafficking leading to accumulation of activated neutrophils in the microvascular compartment. CXCR1 and CXCR2, being major chemokine receptors on neutrophils, are largely responsible for neutrophil recruitment. We speculate that down-regulated expression of CXCR1/2 retains neutrophils within the vessel wall and, consequently, leads to vessel damage.MethodsMembrane expression of CXCR1/2 on neutrophils was assessed by flow cytometry. Serum levels of interleukin-8 (IL-8), tumor necrosis factor alpha (TNF-α), angiopoietin 1 and angiopoietin 2 from quiescent and active AAV patients and healthy controls (HC) were quantified by ELISA. Adhesion and transendothelial migration of isolated neutrophils were analyzed using adhesion assays and Transwell systems, respectively.ResultsExpression of CXCR1 and CXCR2 on neutrophils was significantly decreased in AAV patients compared to HC. Levels of IL-8, which, as TNFα, dose-dependently down-regulated CXCR1 and CXCR2 expression on neutrophils in vitro, were significantly increased in the serum of patients with active AAV and correlated negatively with CXCR1/CXCR2 expression on neutrophils, even in quiescent patients. Blocking CXCR1 and CXCR2 with repertaxin increased neutrophil adhesion and inhibited migration through a glomerular endothelial cell layer.ConclusionsExpression of CXCR1 and CXCR2 is decreased in AAV, potentially induced by circulating proinflammatory cytokines such as IL-8. Down-regulation of these chemokine receptors could increase neutrophil adhesion and impair its migration through the glomerular endothelium, contributing to neutrophil accumulation and, in concert with ANCA, persistent inflammation within the vessel wall.

Pauci-immune necrotizing glomerulonephritis

Pauci-immune necrotizing glomerulonephritis is the most frequent cause of rapidly progressive glomerulonephritis and, in most cases, is associated with antineutrophil cytoplasmic antibodies (ANCA). It is either the renal manifestation of Wegeners granulomatosis, microscopic polyangiitis of Churg-Strauss syndrome, or a renal-limited vasculitis. In this review, the histopathologic changes seen in renal biopsies of patients with pauci-immune glomerulonephritis are described. The authors also describe why the disease is sometimes limited to the kidneys, the clinical course of renal disease, treatment issues, how to deal with disease relapses, and how to prevent them from occurring. Furthermore, the necessity of renal biopsy and rebiopsy, the usefulness of rapid ANCA detection at diagnosis, and serial measurement of ANCA during follow-up are discussed. The effect of dialysis on the disease process and the possibility of renal transplantation after disease remission are also debated.