Low density granulocytes and neutrophil extracellular trap formation are increased in incomplete systemic lupus erythematosus.

OBJECTIVE: To investigate the proportion of low-density granulocytes (LDGs), circulating plasma neutrophil extracellular traps (NETs), and serum-induced NET formation in patients with incomplete systemic lupus erythematosus (iSLE) and systemic lupus erythematosus (SLE). METHODS: LDGs were measured cross-sectionally in 18 iSLE patients, 11 SLE patients and 14 healthy controls (HCs), whereas circulating NETs and serum-induced NET formation were assessed in 35 iSLE patients, 41 SLE patients and 16 HCs. LDGs (CD14lowCD15+) were measured in PBMCs using flow cytometry and circulating plasma NETs were measured using anti-myeloperoxidase-DNA, anti-citrullinated histone H3 and anti-elastase-DNA complex ELISAs. Serum-induced NET formation was assessed by incubating healthy neutrophils with serum from iSLE patients, SLE patients or HCs and visualizing NETs with fluorescence microscopy. RESULTS: Proportions of LDGs and circulating plasma NETs were similarly elevated in iSLE and SLE patients compared with those in HCs. Furthermore, patients under hydroxychloroquine (HCQ) treatment had lower proportions of LDGs than those without. Serum from iSLE and SLE patients similarly induced NET formation in healthy neutrophils. In iSLE patients, myeloperoxidase-DNA complexes were correlated with proportions of age-associated B-cells, memory B-cells and negatively with naïve B-cells, while we did not find associations between measures of NETs or serum-induced NET formation and interferon score or clinical parameters. CONCLUSION: These results show that neutrophil dysfunction, including higher proportions of LDGs, and increased NET formation, already occur in iSLE, similar to SLE, despite differences in disease manifestations. Thereby, neutrophil dysfunction may contribute to sustained exposure to autoantigens and autoreactivity in early stages of SLE.

Systemic oxidative stress may be associated with reduced IgG antibody titers against SARS-CoV-2 in vaccinated kidney transplant recipients: A post-hoc analysis of the RECOVAC-IR observational study.

BACKGROUND: Coronavirus disease 2019 (COVID-19) poses an increased risk for severe illness and suboptimal vaccination responses in patients with kidney disease, in which oxidative stress may be involved. Oxidative stress can be reliably measured by determining circulating free thiols (R-SH, sulfhydryl groups), since R-SH are rapidly oxidized by reactive species. In this study, we aimed to examine the association between serum free thiols and the ability to mount a humoral immune response to SARS-CoV-2 vaccination in kidney patients. METHODS: Serum free thiol concentrations were measured in patients with chronic kidney disease stages 4/5 (CKD G4/5) (n = 46), on dialysis (n = 43), kidney transplant recipients (KTR) (n = 73), and controls (n = 50). Baseline serum free thiol and interferon-γ-induced protein-10 (IP-10) - a biomarker of the interferon response - were analyzed for associations with seroconversion rates and SARS-CoV-2 spike (S1)-specific IgG concentrations after two doses of the mRNA-1273 vaccine. RESULTS: Albumin-adjusted serum free thiol concentrations were significantly lower in patients with CKD G4/5 (P < 0.001), on dialysis (P < 0.001), and KTR (P < 0.001), as compared to controls. Seroconversion rates after full vaccination were markedly reduced in KTR (52.1%) and were significantly associated with albumin-adjusted free thiols (OR = 1.76, P = 0.033). After adjustment for MMF use, hemoglobin, and eGFR, this significance was not sustained (OR = 1.49, P = 0.241). CONCLUSIONS: KTR show suboptimal serological responses to SARS-CoV-2 vaccination, which is inversely associated with serum R-SH, reflecting systemic oxidative stress. Albeit this association was not robust to relevant confounding factors, it may at least partially be involved in the inability of KTR to generate a positive serological response after SARS-CoV-2 vaccination.

High serum C-X-C motif chemokine ligand 10 (CXCL10) levels may be associated with new onset interstitial lung disease in patients with systemic sclerosis: evidence from observational, clinical, transcriptomic and in vitro studies.

BACKGROUND: Systemic sclerosis-interstitial lung disease (SSc-ILD) is the leading cause of death in patients with SSc. There is an unmet need for predictive biomarkers to identify patients with SSc at risk of ILD. Previous studies have shown that interferon (IFN) pathways may play a role in SSc. We assessed the use of C-X-C motif chemokine ligand 10 (CXCL10) as a predictive biomarker for new onset of ILD in patients with SSc. METHODS: One-hundred-sixty-five (Female, N = 130) patients with SSc (SSc-ILD, N = 41) and 13 (Female, N = 8) healthy controls were investigated retrospectively. CXCL10 protein levels were measured by ELISA. We performed log rank analysis with baseline CXCL10 serum levels. CXCL10 nanoString data from lung tissues obtained from transplanted patients with SSc-ILD were extracted. Fifteen (Female, N = 10) patients with SSc (SSc-ILD, N = 7) were recruited for bronchoalveolar lavage (BAL) procedure. Lung fibroblasts were treated with BAL-fluid or serum from patients with SSc with or without ILD. Inflammatory/fibrotic genes were assessed. FINDINGS: Serum CXCL10 levels were higher in patients with SSc-ILD compared to SSc patients without ILD [Median (IQR):126 pg/ml (66-282.5) vs. 78.5 pg/ml (50-122), P = 0.029, 95% CI: 1.5 × 10-6 to 0.4284]. Survival analysis showed that baseline CXCL10 levels >78.5 pg/ml have a 2.74-fold increased risk of developing new onset of ILD (Log-rank: P = 0.119) on follow-up. CXCL10 levels in BAL supernatant were not different in patients with SSc-ILD compared to SSc without ILD [76.1 pg/ml (7.2-120.8) vs. 22.3 pg/ml (12.1-43.7), P = 0.24, 95% CI: -19.5 to 100]. NanoString showed that CXCL10 mRNA expression was higher in inflammatory compared to fibrotic lung tissues [4.7 (4.2-5.6) vs. 4.3 (3.6-4.7), P = 0.029]. Fibroblasts treated with SSc-ILD serum or BAL fluids overexpressed CXCL10. INTERPRETATIONS: Clinical, transcriptomic, and in vitro data showed that CXCL10 is potentially involved in early SSc-ILD. More research is needed to confirm whether CXCL10 can be classified as a prospective biomarker to detect patients with SSc at higher risk of developing new onset ILD. FUNDING: This collaborative project is co-financed by the Ministry of Economic Affairs and Climate Policy of the Netherlands utilizing the PPP-allowance made available by the Top Sector Life Sciences & Health to stimulate public-private partnerships (PPP-2019_007). Part of this study is financially supported by Sanofi Genzyme (NL8921).

Biomarkers of Oxidative Stress in Systemic Lupus Erythematosus Patients with Active Nephritis.

Oxidative stress plays an important role in systemic lupus erythematosus (SLE) and especially in lupus nephritis (LN). The aim of this study was to compare redox-related biomarkers between patients with active LN, quiescent SLE (Q-SLE) and healthy controls (HC) and to explore their association with clinical characteristics such as disease activity in patients. We investigated levels of plasma free thiols (R-SH, sulfhydryl groups), levels of soluble receptor for advanced glycation end products (sRAGE) and levels of malondialdehyde (MDA) in SLE patients with active LN (n = 23), patients with quiescent SLE (n = 47) and HC (n = 23). Data of LN patients who previously participated in Dutch lupus nephritis studies and longitudinal samples up to 36 months were analyzed. Thiol levels were lower in active LN at baseline and Q-SLE patients compared to HC. In generalized estimating equation (GEE) modelling, free thiol levels were negatively correlated with the Systemic Lupus Erythematosus Disease Activity Index (SLEDAI) over time (p < 0.001). sRAGE and MDA were positively correlated with the SLEDAI over time (p = 0.035 and p = 0.016, respectively). These results indicate that oxidative stress levels in LN patients are increased compared to HC and associated with SLE disease activity. Therefore, interventional therapy to restore redox homeostasis may be useful as an adjunctive therapy in the treatment of oxidative damage in SLE.

The soluble receptor for advanced glycation end products is potentially predictive of pulmonary arterial hypertension in systemic sclerosis.

Introduction: Pulmonary arterial hypertension (PAH) and interstitial lung disease (ILD) are the leading causes of death in systemic sclerosis (SSc). Until now, no prospective biomarker to predict new onset of SSc-ILD or SSc-PAH in patients with SSc has reached clinical application. In homeostasis, the receptor for advanced glycation end products (RAGE) is expressed in lung tissue and involved in cell-matrix adhesion, proliferation and migration of alveolar epithelial cells, and remodeling of the pulmonary vasculature. Several studies have shown that sRAGE levels in serum and pulmonary tissue vary according to the type of lung-related complication. Therefore, we investigated levels of soluble RAGE (sRAGE) and its ligand high mobility group box 1 (HMGB1) in SSc and their abilities to predict SSc-related pulmonary complications. Methods: One hundred eighty-eight SSc patients were followed retrospectively for the development of ILD, PAH, and mortality for 8 years. Levels of sRAGE and HMGB1 were measured in serum by ELISA. Kaplan-Meier survival curves were performed to predict lung events and mortality and event rates were compared with a log-rank test. Multiple linear regression analysis was performed to examine the association between sRAGE and important clinical determinants. Results: At baseline, levels of sRAGE were significantly higher in SSc-PAH-patients (median 4099.0 pg/ml [936.3-6365.3], p = 0.011) and lower in SSc-ILD-patients (735.0 pg/ml [IQR 525.5-1988.5], p = 0.001) compared to SSc patients without pulmonary involvement (1444.5 pg/ml [966.8-2276.0]). Levels of HMGB1 were not different between groups. After adjusting for age, gender, ILD, chronic obstructive pulmonary disease, anti-centromere antibodies, the presence of puffy fingers or sclerodactyly, use of immunosuppression, antifibrotic therapy, or glucocorticoids, and use of vasodilators, higher sRAGE levels remained independently associated with PAH. After a median follow-up of 50 months (25-81) of patients without pulmonary involvement, baseline sRAGE levels in the highest quartile were predictive of development of PAH (log-rank p = 0.01) and of PAH-related mortality (p = 0.001). Conclusions: High systemic sRAGE at baseline might be used as a prospective biomarker for patients with SSc at high risk to develop new onset of PAH. Moreover, high sRAGE levels could predict lower survival rates due to PAH in patients with SSc.

Release of High-Mobility Group Box-1 after a Raynaud's Attack Leads to Fibroblast Activation and Interferon-γ Induced Protein-10 Production: Role in Systemic Sclerosis Pathogenesis.

Raynaud's Phenomenon (RP) leading to repetitive ischemia and reperfusion (IR) stress, is the first recognizable sign of systemic sclerosis (SSc) leading to increased oxidative stress. High-mobility group box-1 (HMGB1) is a nuclear factor released by apoptotic and necrotic cells after oxidative stress. Since HMGB1 can signal through the receptor for advanced glycation end products (RAGE), we investigated whether an RP attack promotes the release of HMGB1, leading to fibroblast activation and the upregulation of interferon (IFN)-inducible genes. A cold challenge was performed to simulate an RP attack in patients with SSc, primary RP (PRP), and healthy controls. We measured levels of HMGB1 and IFN gamma-induced Protein 10 (IP-10) at different time points in the serum. Digital perfusion was assessed by photoplethysmography. In vitro, HMGB1 or transforming growth factor (TGF-ß1) (as control) was used to stimulate healthy human dermal fibroblasts. Inflammatory, profibrotic, and IFN-inducible genes, were measured by RT-qPCR. In an independent cohort, sera were obtained from 20 patients with SSc and 20 age- and sex-matched healthy controls to determine HMGB1 and IP-10 levels. We found that HMGB1 levels increased significantly 30 min after the cold challenge in SSc compared to healthy controls. In vitro stimulation with HMGB1 resulted in increased mRNA expression of IP-10, and interleukin-6 (IL-6) while TGF-ß1 stimulation promoted IL-6 and Connective Tissue Growth Factor (CTGF). In serum, both HMGB1 and IP-10 levels were significantly higher in patients with SSc compared to healthy controls. We show that cold challenge leads to the release of HMGB1 in SSc patients. HMGB1 induces IP-10 expression in dermal fibroblasts partly through the soluble RAGE (sRAGE) axis suggesting a link between RP attacks, the release of HMGB1 and IFN-induced proteins as a putative early pathogenetic mechanism in SSc.

Mucosal-associated invariant T cells in patients with axial spondyloarthritis.

Background: Several studies implicate Th17-cells and its cytokine (IL-17) in disease pathogenesis of spondyloarthritis (SpA), with available evidence supporting a pathogenic role of CD8+ T-cells. However, data on the involvement of CD8+ mucosal-associated invariant T-cells (MAIT) and their phenotypic characterization and inflammatory function including IL-17 and Granzyme A production in a homogenous population of SpA-patients with primarily axial disease (axSpA) are lacking. Objectives: Quantify and characterize the phenotype and function of circulating CD8+MAIT-cells in axSpA-patients with primarily axial disease. Methods: Blood samples were obtained from 41 axSpA-patients and 30 age- and sex-matched healthy controls (HC). Numbers and percentages of MAIT-cells (defined as CD3+CD8+CD161highTCRVα7.2 +) were determined, and production of IL-17 and Granzyme A (GrzA) by MAIT-cells were examined by flow cytometry upon in vitro stimulation. Serum IgG specific for CMV was measured by ELISA. Results: No significant differences in numbers and percentages of circulating MAIT-cells were found between axSpA-patients and HCr zijn meer resultaten de centrale memory CD8 T cellen. cellen van patirculating MAIT cells.. Further phenotypic analysis revealed a significant decrease in numbers of central memory MAIT-cells of axSpA-patients compared to HC. The decrease in central memory MAIT-cells in axSpA patients was not attributed to an alteration in CD8 T-cell numbers, but correlated inversely with serum CMV-IgG titers. Production of IL-17 by MAIT-cells was comparable between axSpA-patients and HC, whereas a significant decrease in the production of GrzA by MAIT-cells from axSpA-patients was observed. Conclusions: The decrease in cytotoxic capability of circulating MAIT-cells in axSpA-patients might implicate that these cell types migrate to the inflamed tissue and therefore associate with the axial disease pathogenesis.

Proportions of B-cell subsets are altered in incomplete systemic lupus erythematosus and correlate with interferon score and IgG levels.

OBJECTIVES: Incomplete SLE (iSLE) patients display symptoms typical for SLE but have insufficient criteria to fulfil the diagnosis. Biomarkers are needed to identify iSLE patients that will progress to SLE. IFN type I activation, B-cell-activating factor (BAFF) and B-cell subset distortions play an important role in the pathogenesis of SLE. The aim of this cross-sectional study was to investigate whether B-cell subsets are altered in iSLE patients, and whether these alterations correlate with IFN scores and BAFF levels. METHODS: iSLE patients (n = 34), SLE patients (n = 41) with quiescent disease (SLEDAI ≤4) and healthy controls (n = 22) were included. Proportions of B-cell subsets were measured with flow cytometry, IFN scores with RT-PCR and BAFF levels with ELISA. RESULTS: Proportions of age-associated B-cells were elevated in iSLE patients compared with healthy controls and correlated with IgG levels. In iSLE patients, IFN scores and BAFF levels were significantly increased compared with healthy controls. Also, IFN scores correlated with proportions of switched memory B-cells, plasma cells and IgG levels, and correlated negatively with complement levels in iSLE patients. CONCLUSION: In this cross-sectional study, distortions in B-cell subsets were observed in iSLE patients and were correlated with IFN scores and IgG levels. Since these factors play an important role in the pathogenesis of SLE, iSLE patients with these distortions, high IFN scores, and high levels of IgG and BAFF may be at risk for progression to SLE.

Interferon score is increased in incomplete systemic lupus erythematosus and correlates with myxovirus-resistance protein A in blood and skin.

OBJECTIVES: Patients with incomplete systemic lupus erythematosus (iSLE) have lupus features, but do not meet classification criteria for SLE. Type I interferons (IFN) are important early mediators in SLE, and IFN upregulation in incomplete SLE may be associated with progression to SLE. Since many patients present with skin symptoms, the aim of this study is to investigate IFN type I expression and IFN-related mediators in the blood and skin of iSLE patients. METHODS: Twenty-nine iSLE patients (ANA titer ≥ 1:80, symptoms < 5 years, ≥ 1 objectified clinical criterion), 39 SLE patients with quiescent disease (fulfilling ACR or SLICC criteria, SLEDAI ≤4), and 22 healthy controls were included. IFN signature was measured in whole blood, based on 12 IFN-related genes, using RT-PCR, and IFN-score was calculated. IFN-related mediators myxovirus-resistance protein A (MxA), IFN-γ-induced protein 10 (IP-10), and monocyte chemoattractant protein (MCP-1) were measured using ELISA. IFN type I expression in the unaffected skin was analyzed by immunostaining with MxA. RESULTS: IFN-score was increased in 50% of iSLE patients and 46% of SLE patients and correlated positively with the number of autoantibodies, anti-SSA titer, ESR, and IgG and negatively with C4 in iSLE. Levels of MxA correlated strongly with IFN-score (r = 0.78, p < 0.0001). Furthermore, MxA expression was found in 29% of unaffected skin biopsies of iSLE and 31% of SLE patients and also correlated with IFN-score (r = 0.54, p < 0.0001). CONCLUSIONS: IFN-score was increased in half of the iSLE patients, and given the correlation with complement and autoantibody diversity, this suggests a higher risk for disease progression. MxA in the blood and unaffected skin correlated strongly with the IFN-score and is possibly an easily applicable marker for IFN upregulation.

Differential expression of granulopoiesis related genes in neutrophil subsets distinguished by membrane expression of CD177.

OBJECTIVE: Differential gene expression in CD177+ and CD177- neutrophils was investigated, in order to detect possible differences in neutrophil function which could be related to the pathogenesis of ANCA-associated Vasculitides (AAV). METHODS: Neutrophils were isolated from healthy controls (HC) with high, negative or bimodal CD177 expression, and sorted into CD177+ and CD177- subpopulations. Total RNA was screened for expression of 24,000 probes with Illumina Ref-8 Beadchips. Genes showing differential expression between CD177+ and CD177- subsets in microarray analysis were re-assessed using quantitative-PCR. CD177 expression on neutrophil precursors in bone marrow was analyzed using quantitative PCR and flowcytometry. RESULTS: The proportion of CD177+ cells increased during neutrophil maturation in bone marrow. Fold change analysis of gene expression profile of sorted CD177+ and CD177- neutrophils resulted in 14 genes with fold change (fc) >3 difference in expression. Interestingly, 10 of these genes have been reported to change significantly in expression during neutrophil maturation, and most of these genes were granule protein (GP) coding genes. mRNA expression levels measured by RT-PCR of a number of these GP, and of PR3 and MPO were higher in the CD177- neutrophil subset in HC, however, particular granule protein amounts were comparable between CD177+ and CD177- neutrophil subsets. AAV patients had higher amounts of CD177+ neutrophils, but contrary to neutrophils from HC expression of GP-genes was increased, possibly due to activation. CONCLUSION: The neutrophil population can be distinguished by membrane expression of CD177 into subsets that are different in expression of GP mRNA but not in GP protein production. GP gene expression is also elevated in AAV patients, which is not explained by skewed distribution of CD177+ and CD177- subsets but may be associated with neutrophil activation during on-going inflammation.

Increased frequency of circulating IL-21 producing Th-cells in patients with granulomatosis with polyangiitis (GPA).

INTRODUCTION: The present study aimed to explore a possible role for IL-21 producing Th-cells in the immunopathogenesis of granulomatosis with polyangiitis (GPA). METHODS: Peripheral blood from 42 GPA patients in remission and 29 age-matched healthy controls (HCs) were stimulated in vitro, and the frequencies of IL-21 producing Th-cells were determined by flow cytometry. Since Th17-cells produce a low level of IL-21, IL-17 was also included in the analysis. Given that IL-21 is a hallmark cytokine for T follicular helper cells (T(FH)), we next evaluated the expression of their key transcription factor BCL-6 by RT-PCR and flow cytometry. To investigate the effect of IL-21 on autoantibody-production, PBMCs from GPA patients were stimulated in vitro with BAFF/IL-21 and total IgG and ANCA levels were measured in supernatants. In addition, the expression of IL-21-receptor on B-cells was analyzed. RESULTS: Percentages of IL-21 producing Th-cells were significantly elevated in GPA-patients compared to HCs, and were restricted to ANCA-positive patients. The expression of BCL-6 was significantly higher in ANCA-positive GPA-patients, as compared with ANCA-negative patients and HCs. IL-21 enhanced the production of IgG and ANCA in vitro in stimulated PBMCs from GPA patients. No difference was found in the expression of the IL-21-receptor on B-cells between ANCA-negative patients, ANCA-positive patients, and HCs. CONCLUSION: The increased frequency of circulating IL-21 producing Th-cells in ANCA-positive GPA patients and the stimulating capacity of IL-21 on ANCA-production suggest a role for these cells in the immunopathogenesis of GPA. Blockade of IL-21 could constitute a new therapeutic strategy for GPA.

Periodontitis in established rheumatoid arthritis patients: a cross-sectional clinical, microbiological and serological study.

INTRODUCTION: The association between rheumatoid arthritis (RA) and periodontitis is suggested to be linked to the periodontal pathogen Porphyromonas gingivalis. Colonization of P. gingivalis in the oral cavity of RA patients has been scarcely considered. To further explore whether the association between periodontitis and RA is dependent on P. gingivalis, we compared host immune responses in RA patients with and without periodontitis in relation to presence of cultivable P. gingivalis in subgingival plaque. METHODS: In 95 RA patients, the periodontal condition was examined using the Dutch Periodontal Screening Index for treatment needs. Subgingival plaque samples were tested for presence of P. gingivalis by anaerobic culture technique. IgA, IgG and IgM antibody titers to P. gingivalis were measured by ELISA. Serum and subgingival plaque measures were compared to a matched control group of non-RA subjects. RESULTS: A higher prevalence of severe periodontitis was observed in RA patients in comparison to matched non-RA controls (27% versus 12%, p < 0.001). RA patients with severe periodontitis had higher DAS28 scores than RA patients with no or moderate periodontitis (p < 0.001), while no differences were seen in IgM-RF or ACPA reactivity. Furthermore, RA patients with severe periodontitis had higher IgG- and IgM-anti P. gingivalis titers than non-RA controls with severe periodontitis (p < 0.01 resp. p < 0.05), although subgingival occurrence of P. gingivalis was not different. CONCLUSIONS: Severity of periodontitis is related to severity of RA. RA patients with severe periodontitis have a more robust antibody response against P. gingivalis than non-RA controls, but not all RA patients have cultivable P. gingivalis.

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

INTRODUCTION: In 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. METHODS: Membrane 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. RESULTS: Expression 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. CONCLUSIONS: Expression 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.

Increase in IL-21 producing T-cells in patients with systemic lupus erythematosus.

INTRODUCTION: Systemic lupus erythematosus (SLE) is an autoimmune disease accompanied by a disturbed T-cell balance skewed towards effector T-cells, in particular Th17-cells. The novel cytokine interleukin-21 (IL-21) is suggested to be crucial for triggering T-cell responses towards IL-17 producing cells. Thus, we aimed to investigate the ability of T-cells to produce IL-21 and IL-17 in SLE patients. METHODS: Peripheral blood of 34 SLE patients and 18 healthy controls (HC) was stimulated with phorbol myristate acetate (PMA) and calcium ionophore (Ca-Io). Percentages of IL-21- and IL-17A expressing T-cells were analysed by flow cytometry. The expression levels of the transcription factors B-cell lymphoma-6 (BCL-6) and factors retinoid-related orphan receptor (ROR-γt) were assessed in T-cells by real-time RT-PCR and flow cytometry. Additionally, IL-21 receptor (IL-21R) expression on B- and T-cells of patients and HC was analyzed. RESULTS: Significantly increased percentages of IL-21 expressing CD4+ T-cells and CD8+ T-cells were found in SLE patients as compared to HC. The percentages of IL-21+ CD4+ T-cells and CD8+ T-cells correlated significantly with the percentages of IL-17A+ CD4+ T-cells and CD8+ T-cells, respectively. The relative expression of BCL-6 and ROR-γt did not differ between SLE patients and HC. IL-21R expression occurred mainly on B-cells and was not different comparing SLE patients and HC. CONCLUSIONS: This study demonstrates an increased proportion of IL-21+ T-cells in SLE patients correlating with the proportion of IL-17+ T-cells. This suggests a pivotal role of IL-21 in the pathogenesis of SLE.

Expression and regulation of HIF-1alpha in macrophages under inflammatory conditions; significant reduction of VEGF by CaMKII inhibitor.

BACKGROUND: Macrophages expressing the pro-angiogenic transcription factor hypoxia-inducible factor (HIF)-1alpha have been demonstrated in rheumatoid arthritis (RA) in the synovial tissue. Aim of the present study was to investigate intracellular signal transduction regulation of pro-inflammatory HIF-1 alpha expression in macrophages to identify possible new intervention strategies. We investigated the effects of CaMKII-inhibitors amongst other kinase inhibitors, on HIF-1 alpha expression and downstream production of pro-angiogenic factors in macrophages. METHODS: Differentiated THP-1 cells and synovial fluid (SF) macrophages were stimulated with 1 microg/ml LPS with or without pretreatment with specific inhibitors of the ERK pathway (PD98059), the PI3K pathway (LY294002), and the CaMKII pathway (KN93 and SMP-114). mRNA and protein expression of HIF-1 alpha, VEGF, MMP-9, and IL-8 was measured in cell lysates and cell supernatants. RESULTS: HIF-1 alpha protein expression in LPS-stimulated THP-1 macrophages could be blocked by ERK- and PI3K-inhibitors, but also by the CaMKII inhibitor KN93. THP-1 and SF macrophages produced high levels of VEGF, IL-8, and MMP-9, and VEGF protein production was significantly inhibited by PI3K-inhibitor, and by both CaMKII inhibitors. LPS stimulation in an hypoxic environment did not change VEGF levels, suggesting that LPS induced VEGF production in macrophages is more important than the hypoxic induction. CONCLUSIONS: Expression of HIF-1 alpha and downstream effects in macrophages are regulated by ERK-, PI3K, but also by CaMKII pathways. Inhibition of HIF-1alpha protein expression and significant inhibition of VEGF production in macrophages was found using CaMKII inhibitors. This is an unknown but very interesting effect of the CaMKII inhibitor SMP-114, which has been in clinical trial as DMARD for the treatment of RA. This effect may contribute to the anti-arthritic effects of SMP-114.

Role for CaMKII inhibition in rheumatoid arthritis: effects on HIF-1-induced VEGF production by rheumatoid synovial fibroblasts.

BACKGROUND AND AIMS: The present study was designed to investigate the effects of a novel CaMKII inhibitor SMP-114, which was effective in a collagen-induced arthritis model in rats, on rheumatoid synovial fibroblasts. METHODS: Rheumatoid synovial fibroblasts (RSF) were cultured under pro-inflammatory (IL-1beta stimulation) and hypoxic conditions. Protein and mRNA expression of HIF-1alpha and the effects of inhibitors of the CaMKII-, PI3K-, and ERK pathway on VEGF and IL-6 production were analyzed. RESULTS: Stimulation under hypoxic conditions induced higher expression of HIF-1alpha and VEGF mRNA than treatment with either IL-1beta or hypoxia alone. However, incubation with a specific CaMKII inhibitor did not result in reduced VEGF production in RSF. CONCLUSIONS: CaMKII activation has been reported to be involved in HIF-1alpha stabilization, but incubation with SMP-114, a specific CaMKII inhibitor, had no effect on HIF-1-induced VEGF production by rheumatoid synovial fibroblasts.

Regulation of cytokine-induced HIF-1alpha expression in rheumatoid synovial fibroblasts.

The transcription factor hypoxia-inducible factor (HIF)-1 plays a central physiological role in oxygen and energy homeostasis, and is activated during hypoxia by stabilization of the subunit HIF-1alpha. Activation can also occur by proinflammatory cytokines during inflammation. Hypoxia, as well as proinflammatory cytokines, plays an important role in the synovia in rheumatoid arthritis (RA) patients. Expression of HIF-1alpha has been demonstrated in RA synovial lining layer. The aim of the study was to investigate the regulation of the intracellular signal transduction pathways, involved in the expression of HIF-1alpha, and in the expression of genes regulated by HIF-1alpha in rheumatoid synovial fibroblasts (RSF). RSF were cultured under proinflammatory conditions (IL-1beta and TNF-alpha stimulation) and under chemical hypoxia (CoCl2 treatment). Expression of HIF-1alpha was analyzed in nuclear extracts by Western blotting. The effect of inhibitors of the PI3K and the ERK pathway on HIF-1alpha protein expression was measured. mRNA expression of HIF-1alpha, COX-2, vascular endothelial growth factor (VEGF), and stromal cell-derived factor (SDF)-1 was determined by real-time RT-PCR, and protein production of VEGF and SDF-1 by ELISA. Treatment of the synovial fibroblasts with 150 mM CoCl2 as well as stimulation with 10 ng/mL IL-1beta or TNF-alpha resulted in strong protein expression of HIF-1alpha, measured with Western blotting. Pretreatment with the MEK1/2 inhibitor PD98059 as well as the PI3K inhibitor LY294002 resulted in inhibition of the cytokine-induced HIF-1alpha expression. Furthermore, it was shown that cytokine-induced mRNA expression of HIF-1alpha was inhibited by the PI3K inhibitor. We found that cytokine stimulation induced VEGF mRNA and protein production, but no significant effect of kinase inhibition was found on VEGF production in cytokine-stimulated RSF. Both the ERK pathway and the PI3K pathway are involved in the cytokine-induced HIF-1alpha expression in RSF and in the expression of proangiogenic factors.

Functional defect of circulating regulatory CD4+ T cells in patients with Wegener's granulomatosis in remission.

OBJECTIVE: Accumulating data support the role of regulatory T cells, a subset of CD4+ T cells that expresses CD25(high) and the transcription factor forkhead box P3 (FoxP3), in controlling and preventing autoimmunity. In Wegener's granulomatosis (WG), an autoimmune vasculitis, up-regulation of CD25 on circulating CD4+ T cells has been observed, even in patients in remission. The objective of this study was to test whether the frequency and/or function of Treg cells from WG patients in remission are disturbed. METHODS: Peripheral blood mononuclear cells were freshly isolated from 52 WG patients in remission and from 27 age- and sex-matched healthy control subjects. The proportion of circulating Treg cells was assessed by flow cytometry using CD4, CD25, FoxP3, and CD45RO markers. Anergy and suppressive function of CD25(high),CD4+ T cells were determined using polyclonal stimulants and coculture assay in 10 WG patients in remission and in 10 age- and sex-matched healthy controls. RESULTS: In WG patients, a significant increase was observed in the percentage of circulating CD25(high),CD4+ and CD25(low),CD4+ T cells, whereas CD25-,CD4+ T cells were decreased, as compared with healthy controls. Among circulating CD4+ T cells, an expanded percentage of Treg cells (CD25(high),FoxP3+) with memory phenotype was present in WG patients. However, when the suppressive function of CD25(high),CD4+ T cells was tested, CD25(high),CD4+ T cells from WG patients showed diminished or absent suppression of responder T cell proliferation. The impaired suppression was not due to responder cell resistance (as shown by crisscross experiments with T cells from healthy controls) or altered survival of Treg cells. CONCLUSION: These data indicate that WG patients in remission have an expanded proportion of Treg cells that are functionally defective. This observation may be relevant to the development and relapsing course of this autoimmune vasculitis.