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Key Points Giant cell arteritis (GCA) is best understood as an inflammatory vascular syndrome with features of cranial and/or large-vessel vasculitis, systemic inflammation and polymyalgia rheumatica (PMR), which frequently overlap GCA and PMR are among the most common inflammatory rheumatic diseases in the elderly; the prevalence of these diseases is expected to increase due to ageing of the population The role and value of imaging in GCA and PMR is evolving quickly The pathophysiology of GCA is characterized by phases of initiation, transmural inflammation and chronic vessel wall injury and repair, each of which might be novel drug targets Glucocorticoids are the standard-of-care treatment for GCA and PMR, although methotrexate is used in individual cases and anti-IL-6 therapy is now approved for the treatment of GCA The selection of patients for biologic DMARD therapy, defining the best treatment strategies and the development of reliable outcome parameters are challenges in the future management of GCA and PMR Rapid progress in the fields of giant cell arteritis and polymyalgia rheumatica has resulted in the introduction of imaging techniques into routine clinical practice and in promising reports on the efficacy of biologic agents for treatment. Further research should further advance our understanding of the epidemiology, pathogenesis, imaging and treatment of these diseases. The fields of giant cell arteritis (GCA) and polymyalgia rheumatica (PMR) have advanced rapidly, resulting in a new understanding of these diseases. Fast-track strategies and improved awareness programmes that prevent irreversible sight loss through early diagnosis and treatment are a notable advance. Ultrasonography and other imaging techniques have been introduced into routine clinical practice and there have been promising reports on the efficacy of biologic agents, particularly IL-6 antagonists such as tocilizumab, in treating these conditions. Along with these developments, which should improve outcomes in patients with GCA and PMR, new questions and unmet needs have emerged; future research should address which pathogenetic mechanisms contribute to the different phases and clinical phenotypes of GCA, what role imaging has in the early diagnosis and monitoring of GCA and PMR, and in which patients and phases of these diseases novel biologic drugs should be used. This article discusses the implications of recent developments in our understanding of GCA and PMR, as well as the unmet needs concerning epidemiology, pathogenesis, imaging and treatment of these diseases.

The complement cascade is crucial for clearance and control of invading pathogens, and as such is a key target for pathogen mediated host modulation. C3 is the central molecule of the complement cascade, and plays a vital role in opsonization of bacteria and recruitment of neutrophils to the site of infection. Streptococcal species have evolved multiple mechanisms to disrupt complement-mediated innate immunity, among which ScpA (C5a peptidase), a C5a inactivating enzyme, is widely conserved. Here we demonstrate for the first time that pyogenic streptococcal species are capable of cleaving C3, and identify C3 and C3a as novel substrates for the streptococcal ScpA, which are functionally inactivated as a result of cleavage 7 amino acids upstream of the natural C3 convertase. Cleavage of C3a by ScpA resulted in disruption of human neutrophil activation, phagocytosis and chemotaxis, while cleavage of C3 generated abnormally-sized C3a and C3b moieties with impaired function, in particular reducing C3 deposition on the bacterial surface. Despite clear effects on human complement, expression of ScpA reduced clearance of group A streptococci in vivo in wildtype and C5 deficient mice, and promoted systemic bacterial dissemination in mice that lacked both C3 and C5, suggesting an additional complement-independent role for ScpA in streptococcal pathogenesis. ScpA was shown to mediate streptococcal adhesion to both human epithelial and endothelial cells, consistent with a role in promoting bacterial invasion within the host. Taken together, these data show that ScpA is a multi-functional virulence factor with both complement-dependent and independent roles in streptococcal pathogenesis.

The role of the endothelium in protecting from chronic liver disease and TGFβ-mediated fibrosis remains unclear. Here we describe how the endothelial transcription factor ETS-related gene (ERG) promotes liver homoeostasis by controlling canonical TGFβ-SMAD signalling, driving the SMAD1 pathway while repressing SMAD3 activity. Molecular analysis shows that ERG binds to SMAD3, restricting its access to DNA. Ablation of ERG expression results in endothelial-to-mesenchymal transition (EndMT) and spontaneous liver fibrogenesis in EC-specific constitutive hemi-deficient ( Erg cEC-Het ) and inducible homozygous deficient mice ( Erg iEC-KO ), in a SMAD3-dependent manner. Acute administration of the TNF-α inhibitor etanercept inhibits carbon tetrachloride (CCL 4 )-induced fibrogenesis in an ERG-dependent manner in mice. Decreased ERG expression also correlates with EndMT in tissues from patients with end-stage liver fibrosis. These studies identify a pathogenic mechanism where loss of ERG causes endothelial-dependent liver fibrogenesis via regulation of SMAD2/3. Moreover, ERG represents a promising candidate biomarker for assessing EndMT in liver disease. The transcription factor ERG is key to endothelial lineage specification and vascular homeostasis. Here the authors show that ERG balances TGFβ signalling through the SMAD1 and SMAD3 pathways, protecting the endothelium from endothelial-to-mesenchymal transition and consequent liver fibrosis in mice via a SMAD3-dependent mechanism.

[This corrects the article DOI: 10.1371/journal.pone.0147990.].

Spontaneous reports from patients able to report vascular sequelae in real time, and recognition that serum non transferrin bound iron may reach or exceed 10μmol/L in the blood stream after iron tablets or infusions, led us to hypothesize that conventional iron treatments may provoke acute vascular injury. This prompted us to examine whether a phenotype could be observed in normal human endothelial cells treated with low dose iron. Confluent primary human endothelial cells (EC) were treated with filter-sterilized iron (II) citrate or fresh media for RNA sequencing and validation studies. RNA transcript profiles were evaluated using directional RNA sequencing with no pre-specification of target sequences. Alignments were counted for exons and junctions of the gene strand only, blinded to treatment types. Rapid changes in RNA transcript profiles were observed in endothelial cells treated with 10μmol/L iron (II) citrate, compared to media-treated cells. Clustering for Gene Ontology (GO) performed on all differentially expressed genes revealed significant differences in biological process terms between iron and media-treated EC, whereas 10 sets of an equivalent number of randomly selected genes from the respective EC gene datasets showed no significant differences in any GO terms. After 1 hour, differentially expressed genes clustered to vesicle mediated transport, protein catabolism, and cell cycle (Benjamini p = 0.0016, 0.0024 and 0.0032 respectively), and by 6 hours, to cellular response to DNA damage stimulus most significantly through DNA repair genes FANCG, BLM, and H2AFX. Comet assays demonstrated that 10μM iron treatment elicited DNA damage within 1 hour. This was accompanied by a brisk DNA damage response pulse, as ascertained by the development of DNA damage response (DDR) foci, and p53 stabilization. These data suggest that low dose iron treatments are sufficient to modify the vascular endothelium, and induce a DNA damage response.

Arterial involvement is the cardinal feature of large-vessel vasculitis (LVV) and prevention of disease progression is the principal therapeutic goal. However, development of tools for its evaluation represents a major unmet need. To address this, a widely-applicable imaging tool for LVV, analysing arterial involvement in 17 arterial territories, has been developed and validated. Individual stenosis and dilation scores were generated and combined in a composite score. The methodology was validated cross-sectionally and longitudinally in 131 patients, 96 Takayasu arteritis (TA), 35 large-vessel giant-cell arteritis (LV-GCA). In total, 4420 arterial segments from 260 imaging studies were evaluated. The new scores allowed quantitative grading of LVV arterial involvement with high consistency, revealing inter-patient differences. TA had higher stenosis and composite scores and lower dilation scores than LV-GCA. Baseline stenotic and composite scores reflected arterial damage rather than disease-activity. Longitudinal changes in all three scores correlated with disease activity and mirrored arterial disease evolution, reflecting both progressive injury and lesion improvement. Increases ≥1 in any score were specific for arterial disease progression. The scores objectively quantify arterial involvement in LVV, providing precise definition of disease phenotype and evolution. We propose that they represent novel vascular outcome measures essential for future clinical trials.

Takayasu arteritis is associated with considerable morbidity and premature mortality, which could potentially be avoided if this rare granulomatous vasculitis could be diagnosed and treated at an earlier stage. The challenges currently faced in the diagnosis and management of Takayasu arteritis are discussed here, with a focus of the potential utility of noninvasive imaging techniques. Takayasu arteritis, a rare granulomatous vasculitis affecting young people, is associated with considerable morbidity and premature mortality. In most patients the diagnosis is delayed until after the development of substantial arterial injury. Studies of noninvasive imaging techniques suggest that these approaches might facilitate earlier diagnosis and have a role in monitoring disease progress; however, they remain limited in their ability to accurately quantify inflammatory disease activity in the arterial wall. A lack of controlled clinical trial data complicates the choice of therapy for Takayasu arteritis, and clinical indices for monitoring disease activity are currently suboptimal. Increasing knowledge of the pathogenesis of the large vessel vasculitides might eventually lead to novel targeted therapies. Preliminary data from open-label trials of anti-tumor necrosis factor therapy are encouraging, but there is an urgent need for controlled clinical trials to establish optimum therapeutic approaches for this disease. These trials should include a prospective assessment of the use of noninvasive imaging modalities in the diagnosis and subsequent management of Takayasu arteritis. Key Points The rarity of Takayasu arteritis and its heterogeneous clinical presentation typically results in delayed diagnosis and extensive arterial injury Current outcomes for patients are relatively poor, with substantial morbidity and considerable mortality Treatment decisions are complicated by the lack of available clinical trial data 18 FDG-CT-PET, MRA, CTA and US imaging might allow diagnosis of pre-stenotic disease and noninvasive monitoring of arterial injury; however, they remain limited in their ability to monitor disease activity Controlled clinical trials are required to establish optimum therapeutic approaches, to demonstrate a beneficial effect on vascular outcome and to determine the utility of noninvasive imaging techniques Improved understanding of disease pathogenesis and early trials of anti-tumor necrosis factor therapy offers the prospect of a targeted biological approach to treatment in the future

Some autoimmune diseases are associated with an increased risk of cardiovascular disease. We aimed to determine whether or not this is true, and to what extent, for a broad range of autoimmune conditions. In this population-based study, we used linked primary and secondary care records from the Clinical Practice Research Datalink (CPRD), GOLD and Aurum datasets, to assemble a cohort of individuals across the UK who were newly diagnosed with any of 19 autoimmune diseases between Jan 1, 2000, and Dec 31, 2017, younger than 80 years at diagnosis, and free of cardiovascular diseases up to 12 months after diagnosis. We also assembled a matched cohort with up to five individuals matched on age, sex, socioeconomic status, region, and calendar year, who were free of autoimmune disease and free of cardiovascular diseases up to 12 months after study entry. Both cohorts were followed up until June 30, 2019. We investigated the incidence of 12 cardiovascular outcomes and used Cox proportional hazards models to examine differences in patients with and without autoimmune diseases. Of 22 009 375 individuals identified from the CPRD databases, we identified 446 449 eligible individuals with autoimmune diseases and 2 102 830 matched controls. In the autoimmune cohort, mean age at diagnosis was 46·2 years (SD 19·8), and 271 410 (60·8%) were women and 175 039 (39·2%) were men. 68 413 (15·3%) people with and 231 410 (11·0%) without autoimmune diseases developed incident cardiovascular disease during a median of 6·2 years (IQR 2·7–10·8) of follow-up. The incidence rate of cardiovascular disease was 23·3 events per 1000 patient-years among patients with autoimmune disease and 15·0 events per 1000 patient-years among those without an autoimmune disease (hazard ratio [HR] 1·56 [95% CI 1·52–1·59]). An increased risk of cardiovascular disease with autoimmune disease was seen for every individual cardiovascular disease and increased progressively with the number of autoimmune diseases present (one disease: HR 1·41 [95% CI 1·37–1·45]; two diseases: 2·63 [2·49–2·78]); three or more diseases: 3·79 [3·36–4·27]), and in younger age groups (age <45 years: 2·33 [2·16–2·51]; 55–64 years: 1·76 [1·67–1·85]; ≥75 years: 1·30 [1·24–1·36]). Among autoimmune diseases, systemic sclerosis (3·59 [2·81–4·59]), Addison's disease (2·83 [1·96–4·09]), systemic lupus erythematosus (2·82 [2·38–3·33]), and type 1 diabetes (2·36 [2·21–2·52]) had the highest overall cardiovascular risk. These findings warrant targeted cardiovascular prevention measures, in particular in younger patients with autoimmune diseases, and further research into pathophysiological mechanisms underlying these complications. Horizon 2020 Marie Skłodowska-Curie Actions and European Society of Cardiology.

The aim of this study was to develop and validate an automated pipeline that could assist the diagnosis of active aortitis using radiomic imaging biomarkers derived from [18F]-Fluorodeoxyglucose Positron Emission Tomography-Computed Tomography (FDG PET-CT) images. The aorta was automatically segmented by convolutional neural network (CNN) on FDG PET-CT of aortitis and control patients. The FDG PET-CT dataset was split into training (43 aortitis:21 control), test (12 aortitis:5 control) and validation (24 aortitis:14 control) cohorts. Radiomic features (RF), including SUV metrics, were extracted from the segmented data and harmonized. Three radiomic fingerprints were constructed: A—RFs with high diagnostic utility removing highly correlated RFs; B used principal component analysis (PCA); C—Random Forest intrinsic feature selection. The diagnostic utility was evaluated with accuracy and area under the receiver operating characteristic curve (AUC). Several RFs and Fingerprints had high AUC values (AUC > 0.8), confirmed by balanced accuracy, across training, test and external validation datasets. Good diagnostic performance achieved across several multi-centre datasets suggests that a radiomic pipeline can be generalizable. These findings could be used to build an automated clinical decision tool to facilitate objective and standardized assessment regardless of observer experience.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.An amendment to this paper has been published and can be accessed via a link at the top of the paper.