Molecular signature of neutrophil extracellular trap mediating disease module in idiopathic inflammatory myopathy.

The rarity and heterogeneity of idiopathic inflammatory myopathy (IIM) pose challenges for researching IIM in affected individuals. We analyzed integrated transcriptomic datasets obtained using muscle tissues from patients with five distinct IIM subtypes to investigate the shared and distinctive cellular and molecular characteristics. A transcriptomic dataset of muscle tissues from normal controls (n = 105) and patients with dermatomyositis (n = 89), polymyositis (n = 33), inclusion body myositis (n = 121), immune-mediated necrotizing myositis (n = 75), and anti-synthetase syndrome (n = 18) was used for differential gene-expression analysis, functional-enrichment analysis, gene set-enrichment analysis, disease-module identification, and kernel-based diffusion scoring. Damage-associated molecular pattern-associated pathways and neutrophil-mediated immunity were significantly enriched across different IIM subtypes, although their activities varied. Interferons-signaling pathways were differentially activated across all five IIM subtypes. In particular, neutrophil extracellular trap (NET) formation was significantly activated and correlated with Fcγ R-mediated signaling pathways. NET formation-associated genes were key for establishing disease modules, and FCGRs, C1QA, and SERPINE1 markedly perturbed the disease modules. Integrated transcriptomic analysis of muscle tissues identified NETs as key components of neutrophil-mediated immunity involved in the pathogenesis of IIM subtypes and, thus, has therapeutically targetable value.

De novo molecular subtyping of salivary gland tissue in the context of Sjögren's syndrome heterogeneity.

Understanding the mechanistic features and molecular taxonomy of diseases holds promise for the development of more effective treatments, especially for complex heterogeneous diseases. Here, we analyzed transcriptomic datasets of salivary gland tissues from patients with Sjögren's syndrome (SjS) to identify shared and divergent cellular and molecular signatures. Three molecular subtypes of SjS salivary gland tissue were identified: oxidative phosphorylation (OxPhos)-dominant (C1), weak inflammatory with type I interferon signatures (C2), and B cell receptor (BCR) signaling pathway-dominant (C3). C3 had the highest focus score. Type I helper T cells and B cells were the dominant cell types in C1 and C3 tissues, respectively. Metformin and drugs targeting PI3K, BTK, and JAKs were predicted to be effective treatments for C1 and C3 subtypes, respectively. Three subtypes of SjS salivary gland with distinct molecular signatures were identified. The results could contribute to optimal stratification of patients for more effective treatment approaches.

Integrative analysis of lung molecular signatures reveals key drivers of systemic sclerosis-associated interstitial lung disease.

OBJECTIVES: Interstitial lung disease is a significant comorbidity and the leading cause of mortality in patients with systemic sclerosis. Transcriptomic data of systemic sclerosis-associated interstitial lung disease (SSc-ILD) were analysed to evaluate the salient molecular and cellular signatures in comparison with those in related pulmonary diseases and to identify the key driver genes and target molecules in the disease module. METHODS: A transcriptomic dataset of lung tissues from patients with SSc-ILD (n=52), idiopathic pulmonary fibrosis (IPF) (n=549), non-specific interstitial pneumonia (n=49) and pulmonary arterial hypertension (n=81) and from normal healthy controls (n=331) was subjected to filtration of differentially expressed genes, functional enrichment analysis, network-based key driver analysis and kernel-based diffusion scoring. The association of enriched pathways with clinical parameters was evaluated in patients with SSc-ILD. RESULTS: SSc-ILD shared key pathogenic pathways with other fibrosing pulmonary diseases but was distinguishable in some pathological processes. SSc-ILD showed general similarity with IPF in molecular and cellular signatures but stronger signals for myofibroblasts, which in SSc-ILD were in a senescent and apoptosis-resistant state. The p53 signalling pathway was the most enriched signature in lung tissues and lung fibroblasts of SSc-ILD, and was significantly correlated with carbon monoxide diffusing capacity of lung, cellular senescence and apoptosis. EEF2, EFF2K, PHKG2, VCAM1, PRKACB, ITGA4, CDK1, CDK2, FN1 and HDAC1 were key regulators with high diffusion scores in the disease module. CONCLUSIONS: Integrative transcriptomic analysis of lung tissues revealed key signatures of fibrosis in SSc-ILD. A network-based Bayesian approach provides deep insights into key regulatory genes and molecular targets applicable to treating SSc-ILD.

Deep phenotyping of synovial molecular signatures by integrative systems analysis in rheumatoid arthritis.

OBJECTIVE: RA encompasses a complex, heterogeneous and dynamic group of diseases arising from molecular and cellular perturbations of synovial tissues. The aim of this study was to decipher this complexity using an integrative systems approach and provide novel insights for designing stratified treatments. METHODS: An RNA sequencing dataset of synovial tissues from 152 RA patients and 28 normal controls was imported and subjected to filtration of differentially expressed genes, functional enrichment and network analysis, non-negative matrix factorization, and key driver analysis. A naïve Bayes classifier was applied to the independent datasets to investigate the factors associated with treatment outcome. RESULTS: A matrix of 1241 upregulated differentially expressed genes from RA samples was classified into three subtypes (C1-C3) with distinct molecular and cellular signatures. C3 with prominent immune cells and proinflammatory signatures had a stronger association with the presence of ACPA and showed a better therapeutic response than C1 and C2, which were enriched with neutrophil and fibroblast signatures, respectively. C2 was more occupied by synovial fibroblasts of destructive phenotype and carried highly expressed key effector molecules of invasion and osteoclastogenesis. CXCR2, JAK3, FYN and LYN were identified as key driver genes in C1 and C3. HDAC, JUN, NFKB1, TNF and TP53 were key regulators modulating fibroblast aggressiveness in C2. CONCLUSIONS: Deep phenotyping of synovial heterogeneity captured comprehensive and discrete pathophysiological attributes of RA regarding clinical features and treatment response. This result could serve as a template for future studies to design stratified approaches for RA patients.

Clinical phenotype with high risk for initiation of biologic therapy in rheumatoid arthritis: a data-driven cluster analysis.

OBJECTIVES: The clinical manifestations and treatment outcome in patients with rheumatoid arthritis (RA) are heterogeneous. We classified RA patients into subgroups with distinct phenotypes through unsupervised clustering and evaluated the utility of this subclassification for evaluation of clinical outcome. METHODS: A total of 1,103 patients with RA were clustered in an unbiased manner using a k-means clustering method, based on their clinical and phenotypic profiles. Initiation of biological disease-modifying anti-rheumatic drugs (bDMARDs) was evaluated in the segregated clusters to investigate the differential clinical course of each cluster. RESULTS: Patients with RA were classified into four clusters, each with distinct phenotypes. The key features for subclassification were sex, smoking, hypertension, and dyslipidaemia. Cluster 1 consisted of male smokers, who were most likely to initiate bDMARDs by 30 months (p=0.04). Multivariate analysis revealed that overweight, smoking, erythrocyte sedimentation rate, autoantibodies of high titre, and disease activity were the independent predictors of bDMARD initiation at 30 months. Cluster 1 was the highest or the second highest for these independent predictors, suggesting that cluster 1 contained a high-risk group for early initiation of bDMARDs. CONCLUSIONS: The unsupervised clustering of RA patients demonstrated the feasibility of the novel subclassification with respect to predicting clinical outcome. Identifying high-risk patients by a combination of clinical parameters may be useful for the management of RA.

Novel classification of axial spondyloarthritis to predict radiographic progression using machine learning.

OBJECTIVES: Prediction and determination of drug efficacy for radiographic progression is limited by the heterogeneity inherent in axial spondyloarthritis (axSpA). We investigated whether unbiased clustering analysis of phenotypic data can lead to coherent subgroups of axSpA patients with a distinct risk of radiographic progression. METHODS: A group of 412 patients with axSpA was clustered in an unbiased way using a agglomerative hierarchical clustering method, based on their phenotype mapping. We used a generalised linear model, naïve Bayes, Decision Trees, K-Nearest-Neighbors, and Support Vector Machines to construct a consensus classification method. Radiographic progression over 2 years was assessed using the modified Stoke Ankylosing Spondylitis Spine Score (mSASSS). RESULTS: axSpA patients were classified into three distinct subgroups with distinct clinical characteristics. Sex, smoking, HLA-B27, baseline mSASSS, uveitis, and peripheral arthritis were the key features that were found to stratifying the phenogroups. The three phenogroups showed distinct differences in radiographic progression rate (p<0.05) and the proportion of progressors (p<0.001). Phenogroup 2, consisting of male smokers, had the worst radiographic progression, while phenogroup 3, exclusively suffering from uveitis, showed the least radiographic progression. The axSpA phenogroup classification, including its ability to stratify risk, was successfully replicated in an independent validation group. CONCLUSIONS: Phenotype mapping results in a clinically relevant classification of axSpA that is applicable for risk stratification. Novel coupling between phenotypic features and radiographic progression can provide a glimpse into the mechanisms underlying divergent and shared features of axSpA.

Association of influenza infection with hospitalisation-related systemic lupus erythematosus flares: a time series analysis.

OBJECTIVES: This study aimed to investigate whether the influenza annual outbreak in Korea is related to hospitalisation-related flares in systemic lupus erythematosus (SLE) patients. METHODS: The weekly frequency of hospitalisation-related SLE flares (2012-2015) was collected from the Korean National Health Insurance claim database. The weekly laboratory-confirmed detection rate of influenza infection was obtained from the Korea Centers for Disease Control and Prevention database. A generalised linear model was used to examine the relative risks (RRs) of hospitalisation-related SLE flares associated with influenza infection, after adjusting for time trends and meteorological data. RESULTS: A total of 2,223 hospitalisation-related SLE flares were analysed. An interquartile range (24.5%) increase in influenza infection was associated with a 14.0% increase in hospitalisation-related SLE flares (RR, 1.14; 95% confidence interval [CI]: 1.04-1.25; p=0.006). In addition, influenza infections at lag 0-1 (over 2 weeks including concurrent and 1 previous week) and lag 0-2 (over 3 weeks including concurrent and 2 previous weeks) were associated with increase in hospitalisation-related SLE flares (RR, 1.14; 95% confidence interval [CI]: 1.03-1.26; p=0.014 and RR, 1.13; 95% CI: 1.02-1.26; p=0.023). Significant associations were especially observed in women (RR, 1.15; 95% CI: 1.15-1.16; p=0.006) and immunosuppressant (RR, 1.26; 95% CI: 1.26-1.27; p<0.001) or glucocorticoid recipients (RR, 1.17, 95% CI: 1.16-1.17; p=0.004). CONCLUSIONS: This study shows a significant association between seasonal influenza infection and flares in SLE patients, which suggests influenza can be a novel environmental risk factor for SLE flares.

Integrative analysis of lung molecular signatures reveals key drivers of idiopathic pulmonary fibrosis.

BACKGROUND: Idiopathic pulmonary fibrosis (IPF) is a devastating disease with a high clinical burden. The molecular signatures of IPF were analyzed to distinguish molecular subgroups and identify key driver genes and therapeutic targets. METHODS: Thirteen datasets of lung tissue transcriptomics including 585 IPF patients and 362 normal controls were obtained from the databases and subjected to filtration of differentially expressed genes (DEGs). A functional enrichment analysis, agglomerative hierarchical clustering, network-based key driver analysis, and diffusion scoring were performed, and the association of enriched pathways and clinical parameters was evaluated. RESULTS: A total of 2,967 upregulated DEGs was filtered during the comparison of gene expression profiles of lung tissues between IPF patients and healthy controls. The core molecular network of IPF featured p53 signaling pathway and cellular senescence. IPF patients were classified into two molecular subgroups (C1, C2) via unsupervised clustering. C1 was more enriched in the p53 signaling pathway and ciliated cells and presented a worse prognostic score, while C2 was more enriched for cellular senescence, profibrosing pathways, and alveolar epithelial cells. The p53 signaling pathway was closely correlated with a decline in forced vital capacity and carbon monoxide diffusion capacity and with the activation of cellular senescence. CDK1/2, CKDNA1A, CSNK1A1, HDAC1/2, FN1, VCAM1, and ITGA4 were the key regulators as evidence by high diffusion scores in the disease module. Currently available and investigational drugs showed differential diffusion scores in terms of their target molecules. CONCLUSIONS: An integrative molecular analysis of IPF lungs identified two molecular subgroups with distinct pathobiological characteristics and clinical prognostic scores. Inhibition against CDKs or HDACs showed great promise for controlling lung fibrosis. This approach provided molecular insights to support the prediction of clinical outcomes and the selection of therapeutic targets in IPF patients.

Compendium of synovial signatures identifies pathologic characteristics for predicting treatment response in rheumatoid arthritis patients.

Rheumatoid arthritis (RA) is therapeutically challenging due to patient heterogeneity and variability. Herein we describe a novel integration of RA synovial genome-scale transcriptomic profiling of different patient cohorts that can be used to provide predictive insights on drug responses. A normalized compendium consisting of 256 RA synovial samples that cover an intersection of 11,769 genes from 11 datasets was build and compared with similar datasets derived from OA patients and healthy controls. Differentially expression genes (DEGs) that were identified in three independent methods were fed into functional network analysis, with subsequent grouping of the samples based on a non-negative matrix factorization method. RA-relevant pathway activation scores and four machine learning classification techniques supported the generation of a predictive model of patient treatment response. We identified 876 up-regulated DEGs including 24 known genetic risk factors and 8 drug targets. DEG-based subgrouping revealed 3 distinct RA patient clusters with distinct activity signatures for RA-relevant pathways. In the case of infliximab, we constructed a classifier of drug response that was highly accurate with an AUC/AUPR of 0.92/0.86. The most informative pathways in achieving this performance were the NFκB-, FcεRI- TCR-, and TNF signaling pathways. Similarly, the expression of the HMMR, PRPF4B, EVI2A, RAB27A, MALT1, SNX6, and IFIH1 genes contributed in predicting the patient outcome. Construction and analysis of normalized synovial transcriptomic compendia can provide useful insights for understanding RA-related pathway involvement and drug responses for individual patients.

Compendium of skin molecular signatures identifies key pathological features associated with fibrosis in systemic sclerosis.

OBJECTIVES: Treatment of patients with systemic sclerosis (SSc) can be challenging because of clinical heterogeneity. Integration of genome-scale transcriptomic profiling for patients with SSc can provide insights on patient categorisation and novel drug targets. METHODS: A normalised compendium was created from 344 skin samples of 173 patients with SSc, covering an intersection of 17 424 genes from eight data sets. Differentially expressed genes (DEGs) identified by three independent methods were subjected to functional network analysis, where samples were grouped using non-negative matrix factorisation. Finally, we investigated the pathways and biomarkers associated with skin fibrosis using gene-set enrichment analysis. RESULTS: We identified 1089 upregulated DEGs, including 14 known genetic risk factors and five potential drug targets. Pathway-based subgrouping revealed four distinct clusters of patients with SSc with distinct activity signatures for SSc-relevant pathways. The inflammatory subtype was related to significant improvement in skin fibrosis at follow-up. The phosphoinositide-3-kinase-protein kinase B (PI3K-Akt) signalling pathway showed both the closest correlation and temporal pattern to skin fibrosis score. COMP, THBS1, THBS4, FN1, and TNC were leading-edge genes of the PI3K-Akt pathway in skin fibrogenesis. CONCLUSIONS: Construction and analysis of normalised skin transcriptomic compendia can provide useful insights on pathway involvement by SSc subsets and discovering viable biomarkers for a skin fibrosis index. Particularly, the PI3K-Akt pathway and its leading players are promising therapeutic targets.

Leukocyte-specific protein 1 regulates T-cell migration in rheumatoid arthritis.

Copy number variations (CNVs) have been implicated in human diseases. However, it remains unclear how they affect immune dysfunction and autoimmune diseases, including rheumatoid arthritis (RA). Here, we identified a novel leukocyte-specific protein 1 (LSP1) deletion variant for RA susceptibility located in 11p15.5. We replicated that the copy number of LSP1 gene is significantly lower in patients with RA, which correlates positively with LSP1 protein expression levels. Differentially expressed genes in Lsp1-deficient primary T cells represent cell motility and immune and cytokine responses. Functional assays demonstrated that LSP1, induced by T-cell receptor activation, negatively regulates T-cell migration by reducing ERK activation in vitro. In mice with T-cell-dependent chronic inflammation, loss of Lsp1 promotes migration of T cells into the target tissues as well as draining lymph nodes, exacerbating disease severity. Moreover, patients with RA show diminished expression of LSP1 in peripheral T cells with increased migratory capacity, suggesting that the defect in LSP1 signaling lowers the threshold for T-cell activation. To our knowledge, our work is the first to demonstrate how CNVs result in immune dysfunction and a disease phenotype. Particularly, our data highlight the importance of LSP1 CNVs and LSP1 insufficiency in the pathogenesis of RA and provide previously unidentified insights into the mechanisms underlying T-cell migration toward the inflamed synovium in RA.

Elevated levels of soluble CD40 ligand are associated with antiphospholipid antibodies in patients with systemic lupus erythematosus.

OBJECTIVES: The CD40L/CD40 pathway is involved in the pathophysiology of atherothrombotic disease, and elevated levels of soluble CD40L (sCD40L) were reported in SLE patients. However, the clinical implication of sCD40L in SLE remains elusive. METHODS: We measured levels of plasma sCD40L in 241 SLE patients and 37 healthy controls and investigated its association with clinical manifestation and laboratory parameters. RESULTS: Levels of plasma sCD40L in SLE patients were significantly elevated compared with healthy controls (p=0.013) and positively correlated with levels of soluble P-selectin (γ=0.336, p<0.001). SLE patients who experienced arterial thrombosis had a higher level of sCD40L than those who did not (p=0.029). Plasma sCD40L levels were positively correlated with the titers of anti-cardiolipin and anti-ß2 glycoprotein I antibodies (γ=0.338, p<0.001 and γ=0.364, p<0.001, respectively). Its levels were also significantly higher in patients with clinical antiphospholipid syndrome (APS) than in non-APS patients, irrespective of antiphospholipid antibody (aPL) positivity. Of those with arterial thrombosis, sCD40L levels were significantly elevated in patients with positive aPL, compared to those with negative aPL (p=0.011). Multiple regression analysis revealed that the presence of hypertension and positive aPL were independently associated with the occurrence of arterial thrombosis in SLE patients. A parallel analysis showed that sCD40L was also an independent variable for arterial thrombosis; however, this association disappeared when aPL, a strong variable, was included in the model because of collinearity between aPL and sCD40L. CONCLUSIONS: Plasma sCD40L levels were elevated in SLE patients who had positive aPL and experienced arterial thrombosis, suggesting that enhanced release of sCD40L through platelet activation presumably by aPL could contribute to the development of atherothrombotic disease.

Identification of key regulators for the migration and invasion of rheumatoid synoviocytes through a systems approach.

Rheumatoid synoviocytes, which consist of fibroblast-like synoviocytes (FLSs) and synovial macrophages (SMs), are crucial for the progression of rheumatoid arthritis (RA). Particularly, FLSs of RA patients (RA-FLSs) exhibit invasive characteristics reminiscent of cancer cells, destroying cartilage and bone. RA-FLSs and SMs originate differently from mesenchymal and myeloid cells, respectively, but share many pathologic functions. However, the molecular signatures and biological networks representing the distinct and shared features of the two cell types are unknown. We performed global transcriptome profiling of FLSs and SMs obtained from RA and osteoarthritis patients. By comparing the transcriptomes, we identified distinct molecular signatures and cellular processes defining invasiveness of RA-FLSs and proinflammatory properties of RA-SMs, respectively. Interestingly, under the interleukin-1ß (IL-1ß)-stimulated condition, the RA-FLSs newly acquired proinflammatory signature dominant in RA-SMs without losing invasive properties. We next reconstructed a network model that delineates the shared, RA-FLS-dominant (invasive), and RA-SM-dominant (inflammatory) processes. From the network model, we selected 13 genes, including periostin, osteoblast-specific factor (POSTN) and twist basic helix-loop-helix transcription factor 1 (TWIST1), as key regulator candidates responsible for FLS invasiveness. Of note, POSTN and TWIST1 expressions were elevated in independent RA-FLSs and further instigated by IL-1ß. Functional assays demonstrated the requirement of POSTN and TWIST1 for migration and invasion of RA-FLSs stimulated with IL-1ß. Together, our systems approach to rheumatoid synovitis provides a basis for identifying key regulators responsible for pathological features of RA-FLSs and -SMs, demonstrating how a certain type of cells acquires functional redundancy under chronic inflammatory conditions.

Association of inflammatory bowel disease with ankylosing spondylitis and rheumatoid arthritis: A nationwide population-based study.

OBJECTIVES: Tantalizing connections between autoimmune rheumatic diseases (ARDs) and inflammatory bowel disease (IBD) have become evident with regard to their genetic and immunologic background. However, the association between these two disease entities remains unclear. The aim of this study is to investigate the association between each ARD and IBD. METHODS: A nationwide population-based cross-sectional study was performed using the Korean National Health Insurance Claims database. The data of patients with IBD and age- and sex-matched controls between 2009 and 2013 were collected from the database. The prevalence of ARDs, including systemic lupus erythematosus (SLE), inflammatory myositis (polymyositis and dermatomyositis), systemic sclerosis (SSc), Sjögren's syndrome (SjS), ankylosing spondylitis (AS), and rheumatoid arthritis (RA), was determined. The associations between each ARD and IBD were analyzed using multivariate logistic regression models. RESULTS: A total of 40,843 IBD patients (28,197 patients with ulcerative colitis and 12,646 with Crohn's disease) and 122,529 controls were enrolled. The nonstratified analysis revealed that patients with IBD had significant risk of being concomitantly affected by AS (odds ratio [OR] 5.140, 95% confidence interval [95% CI] 4.069-6.492) and RA (OR: 3.474, 95% CI: 2.671-4.519) after adjusting for age and sex. No significant association was observed between IBD and other ARDs including SLE, inflammatory myositis, SSc, and SjS. CONCLUSION: IBD is significantly associated with AS and RA in the large-scaled population-based study. This result suggests that etiopathogenesis of IBD might be shared with AS and RA.

A case of multicentric reticulohistiocytosis.

Multicentric reticulohistiocytosis (MRH) is a rare non-Langerhans histiocytosis of unknown etiology with a predilection for joint and skin. The characteristic clinical features are papulonodular skin eruptions and inflammatory polyarthritis, sometimes progressive to arthritis mutilans, a severe destructive arthropathy. Although these manifestations can present at the same time, it is more common that one feature precedes the others. Notably, these features are similar to those found in some rheumatic diseases, such as rheumatoid arthritis or dermatomyositis, and this can lead to a misdiagnosis, especially during periods where only one feature is present. Herein, we report a female patient with polyarthralgia and subsequent skin eruptions, who was eventually diagnosed with MRH. Her symptoms seemed to resemble those of some rheumatic diseases, but several features such as affected joints and the characteristic shape of the skin lesions did not correspond to that. The histological result of infiltration of histiocytes and multinucleated giant cells in the skin ultimately facilitated the correct diagnosis. In this paper, we review MRH briefly and highlight several differential points which enable us to increase the likelihood of correctly diagnosing MRH.

Interaction of mesenchymal stem cells with fibroblast-like synoviocytes via cadherin-11 promotes angiogenesis by enhanced secretion of placental growth factor.

Bone marrow-derived mesenchymal stem cells (MSC) exist in the synovium of patients with rheumatoid arthritis (RA), yet the role of MSC in RA is elusive. Placental growth factor (PlGF) expression is increased in RA synovial fluids, and blocking of PlGF attenuates progression of arthritis in mice. In this study, we observed that PlGF induced chemotaxis of MSC in a dose-dependent manner, which was blocked by anti-vascular endothelial growth factor receptor-1 peptide. MSC exposed to PlGF elicited increased phosphorylation of Akt and p38 MAPK. PlGF-mediated chemotaxis was inhibited by PI3K inhibitor (LY294002) and p38 MAPK inhibitor (SB203580), but not by ERK1/2 inhibitor (PD98059). Fibroblast-like synoviocytes (FLS) constitutively produced PlGF, but MSC released negligible amounts of PlGF. Of note, when FLS of RA patients and MSC were cocultured, PlGF production by FLS was significantly increased; such an increase was dependent on the number of added MSC. Moreover, coculture conditioned medium promoted chemotaxis of MSC and increased angiogenesis in Matrigel plugs assay, and these were suppressed by preincubation of the medium with anti-PlGF Ab. Transwell experiments revealed that MSC to FLS contact was required for the increase in PlGF production by coculture. Cadherin-11 was expressed both in FLS and MSC, and small interfering RNA knockdown of cadherin-11 in FLS significantly abrogated the enhanced PlGF production under coculture conditions. These data indicate that increased levels of PlGF in RA joints could induce the migration of MSC to the synovium, and interaction of migrated MSC with FLS via cadherin-11 may contribute to angiogenesis and chronic synovitis by enhancing the secretion of PlGF.

Osteoprotegerin causes apoptosis of endothelial progenitor cells by induction of oxidative stress.

OBJECTIVE: Elevated serum osteoprotegerin (OPG) levels represent an independent risk factor for atherosclerotic disease, although the underlying mechanism is not clear. The aim of this study was to investigate the association of serum OPG levels and circulating endothelial progenitor cell (EPC) numbers, and to explore the effect of OPG on EPC apoptosis and its underlying mechanisms. METHODS: Flow cytometry was used to enumerate EPCs in the peripheral blood of 91 patients with systemic lupus erythematosus (SLE). Cultured EPCs, isolated from peripheral blood, were challenged with OPG, and apoptosis was evaluated by TUNEL staining. Expression of apoptosis-related proteins was measured by real-time quantitative polymerase chain reaction (qPCR) and Western blotting. Reactive oxygen species (ROS) were detected by flow cytometry, and the expression of NADPH oxidase (NOX) and MAP kinases (MAPK) was measured by qPCR and Western blotting. RESULTS: The serum OPG level was independently associated with reduced numbers of EPCs in patients with SLE. In vitro treatment with OPG significantly induced apoptosis of EPCs; this effect was mediated by syndecan 4. OPG-induced apoptosis was abolished by the ROS scavenger N-acetylcysteine and the NOX inhibitor diphenyleniodonium. OPG increased ROS production through activation of NOX-2 and NOX-4 and triggered phosphorylation of ERK-1/2 and p38 MAPK. Quenching of ROS by knockdown of NOX-2 or NOX-4 transcripts inhibited phosphorylation of ERK-1/2 and p38 MAPK. Moreover, inhibitors of ERK-1/2 and p38 MAPK decreased ROS production and subsequent EPC apoptosis, indicating a feed-forward loop between NOX and MAPK to amplify ROS production related to apoptosis. CONCLUSION: Elevated OPG levels increase apoptosis of EPCs by induction of oxidative stress.

The Impact of Lifestyle on Cardiovascular Risk in Patients with Gout: a Population-based Cohort Study.

AIMS: Gout is associated with a significant burden of cardiovascular disease. The aim of this study was to evaluate the impact of a favorable lifestyle on incident cardiovascular events in patients with gout. METHODS: We identified 9 110 patients with gout from the UK Biobank cohort based on self-report and/or hospital diagnostic codes. Lifestyle behaviors, including smoking status, physical activity, obesity, and diet, were categorized into three patterns: favorable (3-4 healthy factors), intermediate (2 healthy factors), and unfavorable (0-1 healthy factor). The cardiovascular risk of participants with and without gout was estimated based on their serum uric acid levels and lifestyle patterns. RESULTS: Among 9 110 patients with gout and 457 596 participants without gout, the median follow-up duration was 8.9 years. The incidence rate of cardiovascular disease was significantly higher in the gout population than in the non-gout population (11.38 vs 5.49 per 1000 person-years). The gout population consistently exhibited a high cardiovascular risk, irrespective of uric acid levels, whereas a positive correlation was observed between uric acid levels and cardiovascular risk in the non-gout population. Adopting a favorable lifestyle pattern was associated with a lower risk of cardiovascular disease in both gout and non-gout populations. Across all categories of uric acid, a favorable lifestyle was found to reduce cardiovascular risk in patients with gout. CONCLUSION: Patients with gout remain at high risk of developing cardiovascular disease despite having normal uric acid levels. Lifestyle modifications may represent an effective and cost-efficient therapeutic approach for preventing cardiovascular events in this population.

Thrombotic risk in patients with immune thrombocytopenia and its association with antiphospholipid antibodies.

Patients with immune thrombocytopenia (ITP) paradoxically have an increased risk of thrombosis. The presence of antiphospholipid antibodies (aPL) has been observed in a substantial proportion of ITP patients, but its clinical significance remains to be established. This study retrospectively investigated the prevalence and clinical significance of aPL in ITP patients and assessed the risk factors for thrombosis. One hundred and sixty-five subjects with ITP were included in the study and followed for a mean period of 63·4 months. Sixty-nine (41·6%) patients were positive for aPL at diagnosis, and their clinical characteristics and course of ITP were not different from those of aPL-negative patients. Twenty-one (12·7%) patients developed a thrombotic event during follow-up and the cumulative incidence rate ratio of aPL-positive to aPL-negative patients for thromboembolism was 3·15 [95% confidence interval (CI) 1·21-8·17] after adjusting for confounding factors. Lupus anticoagulant and hypertension were identified by Cox regression analysis as independent risk factors for thrombosis [hazard ratio (HR) 4·1, 95% CI 1·4-11·9, P = 0·009 and HR 5·6, 95% CI 1·9-15·8, P = 0·001, respectively]. Our results showed that a substantial proportion of ITP patients were aPL-positive, and that lupus anticoagulant and hypertension were independent risk factors for thrombosis. Detection of aPL can provide useful information for identifying patients at high-risk for developing thrombosis.