Disease Activity and Tendency to Relapse in ANCA-Associated Vasculitis Are Reflected in Neutrophil and Intermediate Monocyte Frequencies.

Antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) is a group of autoimmune diseases with inflammation affecting small blood vessels and includes granulomatosis with polyangiitis (GPA) and microscopic polyangiitis (MPA). In this study, we investigated granulocyte and monocyte subsets in a large cohort of AAV patients with emphasis on disease activity and tendency to relapse. A cohort of 105 patients with GPA or MPA and 126 healthy controls (HCs) were included. Clinical and laboratory data were collected for all patients, including disease activity, tendency to relapse, and pharmacological treatment. Using flow cytometry, circulating eosinophils, basophils, neutrophils, and monocytes were assessed. The monocytes were subdivided into classical (CD14++CD16-), intermediate (CD14++CD16+), and nonclassical (CD14-CD16+) monocytes. Mature (CD16high) or newly released (CD16dim) neutrophils were defined, as well as the frequency of CD177+ neutrophils. AAV patients displayed increased frequencies of intermediate monocytes, mature and newly released neutrophils, and an expanded population of CD177+ neutrophils compared to HC. MPA patients differed from GPA patients in terms of lower frequency of classical monocytes. No differences in cell frequencies regarding ANCA phenotype were observed. Paired data from 23 patients demonstrated that active disease was associated with an increased frequency of mature neutrophils and a decreased frequency of monocytes, in particular intermediate monocytes. Moreover, GPA patients with a tendency to relapse displayed an increased frequency of mature neutrophils with increased expression of CD177+. Relapsing MPA patients, on the other hand, showed decreased frequency of intermediate monocytes. Finally, rituximab treatment was associated with increased frequencies of classical and intermediate monocytes. In conclusion, AAV patients exhibit a skewing of different neutrophil and monocyte subpopulations that are associated with disease subtypes, disease activity, rituximab treatment, and propensity to relapse. These changes may contribute to the inflammatory process and could potentially be used as biomarkers for relapse prediction.

Neutrophil extracellular trap formation in anti-neutrophil cytoplasmic antibody-associated and large-vessel vasculitis.

Levels of neutrophil extracellular traps (NETs) were measured in plasma of healthy controls (HC, n = 30) and patients with granulomatosis with polyangiitis (GPA, n = 123), microscopic polyangiitis (MPA, n = 61), Takayasu's arteritis (TAK, n = 58), and giant cell arteritis (GCA, n = 68), at times of remission or activity and correlated with levels of the platelet-derived thrombospondin-1 (TSP-1). Levels of NETs were elevated during active disease in patients with GPA (p < 0.0001), MPA (p = 0.0038), TAK (p < 0.0001), and GCA (p < 0.0001), and in remission for GPA, p < 0.0001, MPA, p = 0.005, TAK, p = 0.03, and GCA, p = 0.0009. All cohorts demonstrated impaired NET degradation. Patients with GPA (p = 0.0045) and MPA (p = 0.005) had anti-NET IgG antibodies. Patients with TAK had anti-histone antibodies (p < 0.01), correlating with presence of NETs. Levels of TSP-1 were increased in all patients with vasculitis, and associated with NET formation. NET formation is a common process in vasculitides. Targeting NET formation or degradation could be potential therapeutic approaches for vasculitides.

Microscopic polyangiitis plasma-derived exosomal miR-1287-5p induces endothelial inflammatory injury and neutrophil adhesion by targeting CBL.

Background: An inflammatory environment around the vessel wall caused by leukocyte infiltration is one of the characteristic histopathological features of microscopic polyangiitis (MPA); however, the pathogenic mechanisms are not fully understood. Studies have found that circulating microRNA (miRNA) can be used as potential biomarkers for the diagnosis and classification of anti-neutrophil cytoplasmic autoantibody (ANCA)-associated vasculitides (AAV), and the E3 ubiquitin ligase casitas B-lineage lymphoma (CBL) seems to be associated with inflammation. In addition, evidence indicates that miRNA can be tracked into exosomes and transferred into recipient cells to mediate the process of vascular endothelial injury. Herein, we aimed to identify the profiles of exosomal miRNA, and determine the effect of exosomal miR-1287-5p and its target gene CBL on vascular endothelial cells in MPA. Method: We isolated plasma exosomes from patients with MPA (MPA-exo) and healthy controls (HC-exo) by ultracentrifugation and conducted exosome small-RNA sequencing to screen differential miRNA expression in MPA-exo (n = 3) compared to HC-exo (n = 3). We measured the expression levels of miR-1303, miR-1287-5p, and miR-129-1-3p using quantitative reverse transcription-polymerase chain reaction (qRT-PCR, n = 6) and performed dual luciferase reporter gene assays to confirm the downstream target gene of miR-1287-5p. In addition, we treated human umbilical vein endothelial cell (HUVEC) with MPA-exo, or transfected them with miR-1287-5p mimic/inhibitor or with CBL-siRNA/CBL-siRNA+ miR-1287-5p inhibitor. After cell culture, we evaluated the effects on vascular endothelial cells by examining the mRNA levels of IL-6, IL-8, MCP-1, ICAM-1 and E-selectin using qRT-PCR and performed neutrophil adhesion assay with haematoxylin staining. Result: Transmission electron microscopy, Western blot and nanoparticle tracking analysis showed that we successfully purified exosomes and MPA-exo could be absorbed into HUVEC. We screened a total of 1,077 miRNA by sequencing and observed a high abundance of miR-1287-5p in the exosomes obtained from MPA plasma. The dual luciferase reporter assay identified CBL as a downstream target gene of miR-1287-5p, and the results revealed that MPA-exo decreased CBL protein expression in HUVEC. In addition, treatment with MPA-exo, up-regulating miR-1287-5p or silencing of CBL in HUVEC significantly increased the mRNA expression of inflammatory factors (including IL-6, IL-8, and MCP-1) and adhesion molecules (including ICAM-1 and E-selection) and promoted the adhesion of neutrophils to HUVEC. However, down-regulating miR-1287-5p had the opposite effect. Conclusion: Our study revealed that MPA-exo was involved in the intercellular transfer of miR-1287-5p and subsequently promote the development of acute endothelial injury in MPA. MiR-1287-5p and CBL agonists may be promising therapeutic approach for MPA-induced vascular inflammatory injury.

Oxidative Stress Promotes Instability of Regulatory T Cells in Antineutrophil Cytoplasmic Antibody-Associated Vasculitis.

We investigated the characteristics of regulatory T cells (Tregs), focusing on the relationship between their stability and reactive oxygen species (ROS), in antineutrophil cytoplasmic antibody-associated vasculitis (AAV). Intracellular expressions of effector cytokines, forkhead box protein 3 (FoxP3), ROS, phosphorylated mammalian target of rapamycin (mTOR), and sirtuin 1 (SIRT1) in Tregs from peripheral blood mononuclear cells (PBMCs) of patients with AAV and healthy controls (HC) were analyzed. The alterations in and functional ability of Tregs were compared before and after resveratrol (RVL) treatment of PBMCs in patients with AAV. Significantly higher expressions of interferon (IFN)-γ, interleukin (IL)-17, IL-4, ROS, and phosphorylated mTOR (pho-mTOR) and lower expression of SIRT1 in CD4+CD25+FoxP3+ cells were found in patients with AAV than in the HC. FoxP3 expression in CD4+CD25+ cells and suppressive function of Tregs were significantly lower in patients with AAV than in the HC. Tregs after RVL treatment demonstrated significant decreases in IFN-γ, ROS, and pho-mTOR levels and increases in FoxP3, SIRT1 levels, and functional activity. Conversely, the direct activation of SIRT1 by SRT1720 resulted in decreased FoxP3 expression, with no reduction in ROS levels. The pho-mTOR levels were significantly higher in Tregs after activation by SRT1720 than in those after RVL treatment. This study suggested that imbalanced changes in Tregs could be attributed to mTOR activation, in which ROS overproduction was predominantly implicated. Therefore, ROS is a key mediator for promoting Tregs instability in AAV.

Skewed peripheral B- and T-cell compartments in patients with ANCA-associated vasculitis.

OBJECTIVES: To characterize lymphocytes dysregulation in patients with granulomatosis with polyangiitis (GPA) and microscopic polyangiitis (MPA). METHODS: Using flow cytometry, we analysed B- and T-cell subsets in peripheral blood from 37 untreated patients with active disease (29 GPA and 8 MPA) and 22 healthy controls (HCs). RESULTS: GPA patients had increased Th2 (1.8 vs 1.0%, P = 0.02), Th9 (1.1 vs 0.2%, P = 0.0007) and Th17 (1.4 vs 0.9%, P = 0.03) cells compared with HC. Patients with MPO-ANCAs had significantly more CD21- B cells than HC or PR3-ANCA patients (6.9 vs 3.3% and 4.4%, P = 0.01). CD69 expressing B cells were significantly higher in GPA and MPA (3.0 and 5.9 vs 1.4%, P = 0.02 and P = 0.03, respectively) compared with HC, whereas B-cell activating factor-receptor expression was decreased in GPA and MPA (median fluorescence intensity ratio 11.8 and 13.7 vs 45.1 in HC, P < 0.0001 and P = 0.003, respectively). Finally, IL-6-producing B cells were increased in GPA vs HC (25.8 vs 14.9%, P < 0.0001) and decreased in MPA vs HC (4.6 vs 14.9%, P = 0.005), whereas TNF-α-producing B cells were lower in both GPA and MPA patients compared with controls (15 and 8.4 vs 30%, P = 0.01 and P = 0.006, respectively). CONCLUSION: Skewed T-cell polarization towards Th2, Th9 and Th17 responses characterizes GPA, whereas B-cell populations are dysregulated in both GPA and MPA with an activated phenotype and a decreased B-cell activating factor-receptor expression. Finally, inflammatory B cells producing IL-6 are dramatically increased in GPA, providing an additional mechanism by which rituximab could be effective.

Relapse rate and renal prognosis in ANCA-associated vasculitis according to long-term ANCA patterns.

Long-term observation of patients with ANCA-associated vasculitis (AAV) allows the identification of different longitudinal patterns of ANCA levels during follow-up. This study aimed to characterize these patterns and to determine their prognostic significance. All ANCA determinations performed in two university hospitals during a 2-year period were retrospectively reviewed. Patients were included in the analysis if they had high titers of anti-myeloperoxidase (anti-MPO) or anti-proteinase 3 (anti-PR3) antibodies at least once, ≥ 5 serial ANCA determinations and AAV diagnosed by biopsy or American College of Rheumatology (ACR) classification criteria. Patients' time-course ANCA patterns were classified as monophasic, remitting, recurrent or persistent. Associations between ANCA patterns and prognostic variables (relapse rate and renal outcome) were analysed by univariate and multivariate statistics. A total of 99 patients [55 with microscopic polyangiitis (MPA), 36 with granulomatosis with polyangiitis (GPA) and eight with eosinophilic granulomatosis with polyangiitis (EGPA)] were included. Median follow-up was 9 years. Among patients diagnosed with MPA or GPA, recurrent or persistent ANCA patterns were associated with a higher risk of clinical relapse [hazard ratio (HR) = 3·7, 95% confidence interval (CI) = 1·5-9·1 and HR = 2·9, 95% CI = 1·1-8·0, respectively], independently of clinical diagnosis or ANCA specificity. In patients with anti-MPO antibodies, the recurrent ANCA pattern was associated with worsening renal function [odds ratio (OR) = 5·7, 95% CI = 1·2-26·0]. Recurrent or persistent ANCA patterns are associated with a higher risk of clinical relapse. A recurrent ANCA pattern was associated with worsening renal function in anti-MPO-associated vasculitis.

Fc receptor-like 5 and anti-CD20 treatment response in granulomatosis with polyangiitis and microscopic polyangiitis.

BACKGROUNDBaseline expression of FCRL5, a marker of naive and memory B cells, was shown to predict response to rituximab (RTX) in rheumatoid arthritis. This study investigated baseline expression of FCRL5 as a potential biomarker of clinical response to RTX in granulomatosis with polyangiitis (GPA) and microscopic polyangiitis (MPA).METHODSA previously validated quantitative PCR-based (qPCR-based) platform was used to assess FCRL5 expression in patients with GPA/MPA (RAVE trial, NCT00104299).RESULTSBaseline FCRL5 expression was significantly higher in patients achieving complete remission (CR) at 6, 12, and 18 months, independent of other clinical and serological variables, among those randomized to RTX but not cyclophosphamide-azathioprine (CYC/AZA). Patients with baseline FCRL5 expression ≥ 0.01 expression units (termed FCRL5hi) exhibited significantly higher CR rates at 6, 12, and 18 months as compared with FCRL5lo subjects (84% versus 57% [P = 0.016], 68% versus 40% [P = 0.02], and 68% versus 29% [P = 0.0009], respectively).CONCLUSIONOur data taken together suggest that FCRL5 is a biomarker of B cell lineage associated with increased achievement and maintenance of complete remission among patients treated with RTX and warrant further investigation in a prospective manner.FUNDINGThe analysis for this study was funded by Genentech Inc.

Hyperuricemia is associated with decreased renal function and occurrence of end-stage renal disease in patients with microscopic polyangiitis and granulomatosis with polyangiitis: a retrospective study.

Current evidence suggests that high uric acid levels are associated with accelerated renal damage. However, the clinical impact of serum uric acid level on patients with microscopic polyangiitis (MPA) and granulomatosis with polyangiitis (GPA) is unknown. We aimed to evaluate the impact of hyperuricemia on such patients. A retrospective study was performed to obtain patients' demographic, clinical, and laboratory data from when they were diagnosed with MPA and GPA. Multivariable logistic regression and Cox hazard model analyses were performed to evaluate factors associated with hyperuricemia at diagnosis and predictive factors of end-stage renal disease (ESRD) development. Among 156 patients, 35 (22.4%) had hyperuricemia at baseline. Hyperuricemic patients had renal manifestation and impaired renal function more frequently than non-hyperuricemic patients. Logistic regression analysis revealed that serum creatinine was significantly associated with hyperuricemia at diagnosis [odds ratio 1.995; 95% confidence interval (CI), 1.503-2.648; P < 0.001]. Cox hazard model analysis revealed that body mass index and serum creatinine were significantly associated with ESRD when all variables were included, but hyperuricemia was independently associated with ESRD [hazard ratio (HR), 3.799; 95% CI 1.719-8.222; P < 0.001) when serum creatinine was excluded. Additionally, in a subgroup analysis of patients with decreased glomerular filtration rates (GFRs), serum uric acid was the sole predictor of ESRD (HR, 1.243; 95% CI 1.048-1.475; P = 0.013). Hyperuricemia is associated with renal damage and ESRD occurrence in MPA and GPA patients. Serum uric acid level is associated with ESRD occurrence in patients with decreased GFRs.

Anti-neutrophil cytoplasmic antibody-associated glomerulonephritis with detection of myeloperoxidase and phospholipase A2 receptor in membranous nephropathy-lesions: report of two patients with microscopic polyangiitis.

BACKGROUND: Podocyte phospholipase A2 receptor (PLA2R) is a major target antigen in idiopathic adult membranous nephropathy (MN). Histological PLA2R staining in the renal tissue has proven to be useful for the detection of idiopathic MN. However, glomerular PLA2R deposits have also been recently observed in several patients with secondary MN, such as hepatitis B virus-associated, hepatitis C virus-associated, and neoplasm-associated MN. Certain inflammatory environments have been suggested to lead to abnormal expression of PLA2R epitopes, with the resulting production of PLA2R autoantibodies. CASE PRESENTATION: We report two patients diagnosed with anti-neutrophil cytoplasmic antibody (ANCA)-associated glomerulonephritis with MN-lesions, in whom ANCA titers for myeloperoxidase (MPO) were persistently positive. The first patient was a 52-years-old man who presented with interstitial pneumonitis. Microscopic hematuria and proteinuria were found when the interstitial pneumonitis became more severe. Renal biopsy findings yielded a diagnosis of ANCA-associated glomerulonephritis (mixed class) with MN-lesions. The second patient was a 63-years-old woman who had been treated for relapsing polychondritis. Her renal tissue showed evidence of focal ANCA-associated glomerulonephritis with MN-lesions. Interestingly, both MPO and PLA2R were detected in the glomerular subepithelial deposits of both patients. Immunoglobulin G (IgG) 1 and IgG2 were positive in the glomeruli of patient 2, and all subclasses of IgGs were positive in patient 1. CONCLUSION: The present cases suggest that ANCA-associated glomerulonephritis could expose PLA2R, leading to the development of MN-lesions.

The effect and possible clinical efficacy of in vivo inhibition of neutrophil extracellular traps by blockade of PI3K-gamma on the pathogenesis of microscopic polyangiitis.

OBJECTIVE: Neutrophil extracellular traps (NETs) are peculiar structures composed of the externalized chromatin with intracellular proteins and formed by activated neutrophils in a reactive oxygen species (ROS)-dependent manner. Aberrant NETs are considered to be autoantigens for anti-neutrophil cytoplasmic antibodies (ANCAs) underling the development of microscopic polyangiitis (MPA). However, little is known regarding the therapeutic efficacy of in vivo inhibition of NET formation (NETosis) on MPA pathogenesis. This study determines whether reducing NETosis prevents ANCA production and improves characteristic involvement. METHODS: A mouse model of MPA induced by administering a novel extract from Candida albicans was devised. By applying this method to mice lacking phosphoinositide 3-kinase gamma (PI3K-gamma), which is indispensable for ROS production in neutrophils, we investigated the levels of in vivo NETs, ANCA titers and histological damage. RESULTS: Our model exhibited accumulation of NETs in vivo, elevation of ANCA titers and characteristic pathologies mimicking human MPA, including small-vessel vasculitis and crescentic glomerulonephritis. Strikingly, these abnormalities were reduced by genetically and/or pharmacologically blocking PI3K-gamma. Moreover, a pharmacological PI3K-gamma blockade decreased the levels of human NETs. CONCLUSION: Our results suggest that in vivo inhibition of NETosis by blocking PI3K-gamma could be a promising therapeutic strategy for the pathogenesis of MPA.

Plasma pentraxin 3 (PTX3) level is associated with the disease activity of microscopic polyangiitis (MPA).

A 20-year-old woman, who was suffering from appetite loss, weight loss and livedo reticularis for one and half months, was referred to our hospital. On admission, laboratory studies demonstrated proteinuria (1.0 g/g Cr), hematuria (erythrocytes': 50 - 99/HPF), ,.enal dysfunction (Cr : 2.09 mg/dL), elevated C reactive protein (CRP: 10.82 mg/dL), elevated MPO-ANCA titer (11.6 U/mL) and elevated pentraxin3 (PTX3: 24.05 ng/mL). Her kidney and skin biopsy revealed massive crescentic necrotizing glomerulonephritis and leukocytoclastic vasculitis, respectively. She was diagnosed with microscopic polyangiitis (MPA), and treated with 500 mg/day of intravenous methyl-prednisolone (mPSL) for 3 days followed by 40 mg/day of oral PSL, rituximab (375 mg/m² once a week for a month) and plasma exchange. When PSL tapered to 30 mg/day in 4 weeks, her renal function was only partially recovered, while the CRP level had been normalized and the MPO-ANCA titer was almost negative (3.6 IU/mL). To evaluate histological activity, a second renal biopsy was conducted, which showed fibrocellular crescents in 32% of her glomeruli. The PTX3 level remained high (14.82 ng/mL) at that point. Taken together, the vasculitis was considered to be active still. Steroid pulse therapy for 3 days was administered again, followed by oral PSL 30 mg/day. Her renal function completely recovered in 70 days. The PTX3 level also normalized in 161 days. PTX3 is one of the short pentraxins, produced by a variety of cell types in response to pro-inflammatory signals such as IL-1 and TNF-α. It was reported that PTX3 reflects activity of vasculitis independently from CRP. In the presenting case, when the second renal biopsy revealed a histologically active lesion of the vasculitis, PTX3 was elevated independently from CRP and MPO-ANCA, suggesting that PTX3 may be a more sensitive marker of the disease activity than other tests.

Myeloperoxidase anti-neutrophil cytoplasmic antibody affinity is associated with the formation of neutrophil extracellular traps in the kidney and vasculitis activity in myeloperoxidase anti-neutrophil cytoplasmic antibody-associated microscopic polyangiitis.

Anti-neutrophil cytoplasmic antibody (ANCA) is associated with small-vessel vasculitis particularly in the kidneys and can induce the formation of neutrophil extracellular traps (NETs) from primed neutrophils. Recently we have reported that the induction of NETs correlates with ANCA affinity for myeloperoxidase (MPO) and disease activity in patients with MPO-ANCA-associated microscopic polyangiitis. To investigate whether MPO-ANCA affinity is associated with the formation of NETs in vivo, we examined the occurrence of NETs in the renal tissues of patients with MPO-ANCA-associated microscopic polyangiitis and ANCA affinity by double immunofluorescence staining for NET components of citrullinated histone, MPO and PAD4 and by ELISA competition with MPO, respectively. We divided 30 MPO-ANCA-associated microscopic polyangiitis patients into 2 groups based on their ANCA affinity levels (IC50 for the high: 0.11 ± 0.04 µg/mL (Group1) and IC50 for the low: 0.66 ± 0.24 µg/mL (Group2)). Group1 showed a higher Birmingham vasculitis activity score (15.6 ± 5.7) and 73% of the patients presented clinically with rapidly progressive glomerulonephritis and histologically with focal/crescentic glomerulonephritis (GN). Group 2 showed a lower Birmingham vasculitis activity score (9.2 ± 4.9) and 73% of the patients presented clinically with chronic renal failure and histologically with mixed/sclerotic GN. Group 1 showed a much higher occurrence of NETs than Group 2. Our findings indicate that ANCA affinity was associated with the in vivo formation of NETs, which might be involved in the pathophysiology of patients with MPO-ANCA-associated microscopic polyangiitis.

Rituximab como terapia de mantenimiento en las vasculitis asociadas a ANCA: ¿cómo, cuándo y por qué? / Rituximab as maintenance therapy for ANCA associated vasculitis: how, when and why?

Las vasculitis asociadas a ANCA son enfermedades autoinmunes crónicas que se caracterizan por inflamación y destrucción de vasos de pequeño tamaño. El rituximab es un tratamiento efectivo para la fase de inducción de estas patologías. Durante los últimos años, varios estudios no controlados han reportado que también es eficaz durante la fase de mantenimiento terapéutico. En estas series, el fármaco se administró solo durante las recaídas, a intervalos fijos o sobre la base en cambios en algunos biomarcadores. Los resultados del estudio MAINRITSAN mostraron que el rituximab es superior a la azatioprina como terapia de mantenimiento en estas enfermedades. Este trabajo de revisión resume la información más reciente sobre el uso de rituximab como opción para la fase de mantenimiento de las vasculitis asociadas a ANCA, detallando su efectividad, los diversos protocolos de administración, el perfil de seguridad y el uso potencial de biomarcadores para guiar el tratamiento (AU)

ANCA-associated vasculitides (AAV) are chronic autoimmune diseases characterized by inflammation and destruction of small vessels. Rituximab is now licensed for use as a remission-induction agent in the treatment of these disorders. During recent years, several non-controlled studies have suggested that rituximab may be of value in maintaining disease remission in AAV. In these series, 3 techniques have been tried: 'watch-and-wait', repeated cycles in fixed intervals, or administration based on proposed biomarkers. More importantly, the results of the MAINRITSAN trial showed that this anti-CD20 agent is superior to azathioprine for preventing major relapses in AAV. This review summarizes current information regarding the effectiveness, timing, dosing, duration and safety of rituximab as a valid option for remission maintenance (AU)

Evaluation and validation of biomarkers in granulomatosis with polyangiitis and microscopic polyangiitis.

BACKGROUND: Studies in anti-neutrophil cytoplasm antibody (ANCA)-associated vasculitis (AAV) have revealed promising biomarkers. The aim of our study was to validate the most encouraging markers of granulomatosis with polyangiitis and microscopic polyangiitis identified by literature search and to create biomarker panels. METHODS: A systematic literature review was performed and we identified 161 marker molecules that were ranked by their quantitative differential expression between active and inactive disease. Enzyme-linked immunosorbent assays were used to validate the results in a cross-sectional cohort of patients with renal involvement. Active vasculitis as assessed by the Birmingham Vasculitis Score version 3 (BVAS v3) was defined as BVAS v3 ≥1 and inactive disease as BVAS v3 = 0. Statistical analysis was performed with SPSS version 21 and the Salford Predictive Modeler 7.0 was used to generate a predictive biomarker panel. RESULTS: The review indicated abundant expression of sC5bC9, C3a, C5a and monocyte chemotactic protein (MCP)-1 in urine, whereas granulocyte macrophage colony-stimulating factor, C-reactive protein (CRP), soluble fms-like tyrosine kinase-1, interleukin-17A (IL-17A), C5a, hyaluronan, C3a and interleukin-18 binding protein (IL-18BP) were identified to be highly diverse in active and inactive disease in blood samples. Our cross-sectional analysis revealed significant up-regulation of CRP, C5a, C3a, IL-18BP in blood and C5a and MCP-1 in urine samples during active AAV (all P < 0.05). Creation of a biomarker panel comprising CRP and urinary MCP-1 yielded a sensitivity and specificity of 76% (area under the curve 0.89). CONCLUSIONS: We identified promising biomarkers in a literature-based review that were in part corroborated as has been shown for CRP, C3a, C5a, IL-18BP in blood and MCP-1 and C5a in urine samples. Moreover, we propose a biomarker panel comprising CRP and urinary MCP-1 in patients with AAV and renal involvement. Further investigations to confirm our preliminary results are clearly warranted, including the reliability to predict disease relapses.

Decreased tumour necrosis factor-α production by monocytes of granulomatosis with polyangiitis.

OBJECTIVES: We hypothesized that monocytes in patients with granulomatosis with polyangiitis (GPA) are polarized towards alternative activation with decreased tumour necrosis factor (TNF)-α production and that tissue-infiltrating monocytes/macrophages in granulomatous GPA lesions express CD163, a marker of alternative macrophage activation. METHOD: CD16+ monocytes in peripheral blood mononuclear cells (PBMCs) were quantified by flow cytometry. Monocytes were stimulated with increasing concentrations of lipopolysaccharide (LPS), and TNF-α production was measured at 4 and 24 h. CD163 expression in lung biopsies of patients with GPA was detected by immunohistochemistry. RESULTS: Circulating CD16+ monocytes were more frequent in GPA patients compared to controls (4.7 ± 2.8% vs. 1.9 ± 1.2%, p < 0.001). Upon activation with LPS, TNF-α production did not differ between CD16+ and CD16- monocytes. Stimulated monocytes from GPA patients produced significantly less TNF-α compared with monocytes from healthy controls (2903 ± 1320 pg/mL vs. 8335 ± 4569 pg/mL, p < 0.001). Macrophages expressing CD163 were enriched in granulomatous lung lesions of GPA patients. CONCLUSIONS: Decreased TNF-α production by circulating monocytes and CD163 overexpression by tissue monocytes/macrophages in granulomatous pulmonary lesions may suggest that monocytes/macrophages are alternatively activated in GPA.

Tissue-specific microvascular endothelial cells show distinct capacity to activate NK cells: implications for the pathophysiology of granulomatosis with polyangiitis.

The relevance of tissue specificity of microvascular endothelial cells (MECs) in the response to inflammatory stimuli and sensitivity to immune cell-mediated injury is not well defined. We hypothesized that such MEC characteristics might shape their interaction with NK cells through the use of different adhesion molecules and NK cell receptor ligands or the release of different soluble factors and render them more or less vulnerable to NK cell injury during autoimmune vasculitis, such as granulomatosis with polyangiitis (GPA). To generate a comprehensive expression profile of human MECs of renal, lung, and dermal tissue origin, we characterized, in detail, their response to inflammatory cytokines and to proteinase 3, a major autoantigen in GPA, and analyzed the effects on NK cell activation. In this study, we show that renal MECs were more susceptible than lung and dermal MECs to the effect of inflammatory signals, showing upregulation of ICAM-1 and VCAM-1 on their surface, as well as release of CCL2, soluble fractalkine, and soluble VCAM-1. Proteinase 3-stimulated renal and lung MECs triggered CD107a degranulation in control NK cell. Notably, NK cells from GPA patients expressed markers of recent in vivo activation (CD69, CD107a), degranulated more efficiently than did control NK cells in the presence of renal MECs, and induced direct killing of renal MECs in vitro. These results suggest that, upon inflammatory conditions in GPA, renal MECs may contribute to the recruitment and activation of NK cells in the target vessel wall, which may participate in the necrotizing vasculitis of the kidney during this disease.

Ficolin-1 is up-regulated in leukocytes and glomeruli from microscopic polyangiitis patients.

Microscopic polyangiitis (MPA) is a systemic autoimmune disease that often has a fatal outcome. Although delineating the molecular pathogenesis is essential for its remedy, an understanding of its molecular mechanism has remained elusive. To search for new markers of active lesions that might help better understand the molecular basis of MPA and aid in its diagnosis, we here performed DNA microarray analysis with peripheral blood mononuclear cells (PBMCs). Compared to normal control, several genes were up- or down-regulated in MPA patients, including up-regulation of the mRNA level of ficolin-1 (FCN1 or M-ficolin), an innate pattern recognition complement molecule. The amount of ficolin-1, as detected by immunohistochemistry, was higher in the glomeruli of another group of MPA patients than in the glomeruli of control patients who harbored almost normal glomeruli. Many of the ficolin-1 dots were also positive for CD68, suggesting that the ficolin-1-positive cells were monocytes, such as macrophages or dendritic cells. This is not due to the difference in the number of neutrophil or monocytes in the blood samples of MPA and control patients. Taken together, we conclude that increased ficolin-1 expression could serve as a new marker for the characterization of MPA, especially when it is associated with local active lesions.

Prediction of response to treatment by gene expression profiling of peripheral blood in patients with microscopic polyangiitis.

The JMAAV study was an open-labeled prospective clinical trial, which proposed severity-based treatment protocols for patients with microscopic polyangiitis (MPA). The results suggest that the proposed protocols are useful (remission rate: 89.4%), but are also indicative of relapse or patient demise regardless of the treatment (recurrence rate: 19.0%; mortality rate: 10.6%). The aim of this study is to develop the method to predict response to the treatment in patients with MPA. In the present study, transcriptome analysis was performed using peripheral blood from patients enrolled in the JMAAV study before and 1-week after the beginning of treatment. The gene expression profile before treatment was not directly related to the response to the treatment. However, when the samples from 9 patients with good response (persistent remission for 18 months) were examined, the expression of 88 genes was significantly altered by the treatment. Thirty statistically reliable genes were selected, and then the alteration of expression by the treatment was examined among 22 patients, including 17 with good response, which was defined as persistent remission for 18 months and 5 with poor response, which was defined as relapse after remission or no remission. Discrimination analysis between the alteration of expression of the 30 genes by the treatment and the response identified a combination of 16 genes as the most valuable gene set to predict the response to the treatment. This preliminary study identified IRF7, IFIT1, IFIT5, OASL, CLC, GBP-1, PSMB9, HERC5, CCR1, CD36, MS4A4A, BIRC4BP, PLSCR1, DEFA1/DEFA3, DEFA4, and COL9A2 as the important genes that can predict the response to the treatment in patients with MPA at an early point during the therapy.

Increased frequency of CCR4+ and CCR6+ memory T-cells including CCR7+CD45RAmed very early memory cells in granulomatosis with polyangiitis (Wegener's).

INTRODUCTION: Chemokine receptors play an important role in mediating the recruitment of T cells to inflammatory sites. Previously, small proportions of circulating Th1-type CCR5+ and Th2-type CCR3+ cells have been shown in granulomatosis with polyangiitis (GPA). Wondering to what extent CCR4 and CCR6 expression could also be implicated in T cell recruitment to inflamed sites in GPA, we investigated the expression of CCR4 and CCR6 on T cells and its association with T cell diversity and polarization. METHODS: Multicolor flow cytometry was used to analyze CCR4, CCR6, and intracellular cytokine expression of T cells from whole blood of GPA-patients (n = 26) and healthy controls (n = 20). CCR7 and CD45RA were included for phenotypic characterization. RESULTS: We found a significant increase in the percentages of circulating CCR4+ and CCR6+ cells within the total CD4+ T cell population in GPA. In contrast, there was no difference in the percentages of CD8+CCR4+ and CD8+CCR6+ T cells between GPA and healthy controls. CCR4 and CCR6 expression was largely confined to central (TCM) and effector memory T cells (TEM, TEMRA). A significant increase in the frequency of CCR4+ and CCR6+ TEMRA and CCR6+ TCM was shown in GPA. Of note, we could dissect CCR4 and CCR6 expressing CCR7+CD45RAmed very early memory T cells (TVEM) from genuine CCR7+CD45RAhigh naïve T cells lacking CCR4 and CCR6 expression for peripheral tissue-migration within the CCR7+CD45RA+ compartment. The frequencies of CCR4+ and CCR6+ TVEM were also significantly increased in GPA. An increased percentage of IL-17+ and IL-22+ cells was detected in the CCR6+ cell subsets and IL-4+ cells in the CRR4+ cell subset when compared with CD4+ cells lacking CCR4 and CCR6 expression. CONCLUSIONS: Increased frequencies of circulating CCR4+ and CCR6+ memory T cell subsets including hitherto unreported TVEM suggest persistent T cell activation with the accumulation of CCR4+ and CCR6+ cells in GPA. CCR4 and CCR6 could be involved in the recruitment of T cells including cytokine-producing subsets to inflamed sites in GPA.