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Giant cell arteritis (GCA) is an autoimmune/autoinflammatory disease affecting large vessels in patients over 50 years old. The disease presents as an acute inflammatory response with two phenotypes, cranial GCA and large-vessel vasculitis (LV)-GCA, involving the thoracic aorta and its branches. 18F-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET-CT) is among the imaging techniques contributing to diagnosing patients with systemic disease. However, its association with soluble inflammatory markers is still elusive. This proof-of-concept study aims to identify novel soluble serum biomarkers in PET/CT-positive patients with LV-GCA and associate them with active (0 months) and inactive disease (6 months following treatment), in sequential samples. The most-diseased-segment target-to-background ratio (TBR MDS ) was calculated for 13 LV-GCA patients, while 14 cranial GCA and 14 Polymyalgia Rheumatica patients with negative initial PET/CT scans served as disease controls. Serum macrophage-related cytokines were evaluated by cytometric bead array (CBA). Finally, previously published NMR/metabolomics data acquired from the same blood sampling were analyzed along with PET/CT findings. TBR MDS was significantly increased in active versus inactive disease (3.32 vs. 2.65, p = 0.006). The analysis identified nine serum metabolites as more sensitive to change from the active to inactive state. Among them, choline levels were exclusively altered in the LV-GCA group but not in the disease controls. Cytokine levels were not associated with PET/CT activity. Combining CRP, ESR, and TBR MDS with choline levels, a composite index was generated to distinguish active and inactive LV-GCA (20.4 vs. 11.62, p = 0.001). These preliminary results could pave the way for more extensive studies integrating serum metabolomic parameters with PET/CT imaging data to extract sensitive composite disease indexes useful for everyday clinical practice.

Objective: Giant cell arteritis (GCA) is characterized by granulomatous inflammation of the medium- and large-sized arteries accompanied by remodeling of the vessel wall. Fibroblast activation protein alpha (FAP) is a serine protease that promotes both inflammation and fibrosis. Here, we investigated the plasma levels and vascular expression of FAP in GCA., Methods: Plasma FAP levels were measured with enzyme-linked immunosorbent assay in treatment-naive patients with GCA (n = 60) and polymyalgia rheumatica (PMR) (n = 63) compared with age- and sex-matched healthy controls (HCs) (n = 42) and during follow-up, including treatment-free remission (TFR). Inflamed temporal artery biopsies (TABs) of patients with GCA (n = 9), noninflamed TABs (n = 14), and aorta samples from GCA-related (n = 9) and atherosclerosis-related aneurysm (n = 11) were stained for FAP using immunohistochemistry. Immunofluorescence staining was performed for fibroblasts (CD90), macrophages (CD68/CD206/folate receptor beta), vascular smooth muscle cells (desmin), myofibroblasts (α-smooth muscle actin), interleukin-6 (IL-6), and matrix metalloproteinase-9 (MMP-9)., Results: Baseline plasma FAP levels were significantly lower in patients with GCA compared with patients with PMR and HCs and inversely correlated with systemic markers of inflammation and angiogenesis. FAP levels decreased even further at 3 months on remission in patients with GCA and gradually increased to the level of HCs in TFR. FAP expression was increased in inflamed TABs and aorta of patients with GCA compared with control tissues. FAP was abundantly expressed in fibroblasts and macrophages. Some of the FAP + fibroblasts expressed IL-6 and MMP-9., Conclusion: FAP expression in GCA is clearly modulated both in plasma and in vessels. FAP may be involved in the inflammatory and remodeling processes in GCA and have utility as a target for imaging and therapeutic intervention., (© 2024 The Authors. Arthritis Care & Research published by Wiley Periodicals LLC on behalf of American College of Rheumatology.)

Objective: In polymyalgia rheumatica (PMR), glucocorticoids (GCs) relieve pain and stiffness, but fatigue may persist. We aimed to explore the effect of disease, GCs and PMR symptoms in the metabolite signatures of peripheral blood from patients with PMR or the related disease, giant cell arteritis (GCA)., Methods: Nuclear magnetic resonance spectroscopy was performed on serum from 40 patients with untreated PMR, 84 with new-onset confirmed GCA, and 53 with suspected GCA who later were clinically confirmed non-GCA, and 39 age-matched controls. Further samples from PMR patients were taken one and six months into glucocorticoid therapy to explore relationship of metabolites to persistent fatigue. 100 metabolites were identified using Chenomx and statistical analysis performed in SIMCA-P to examine the relationship between metabolic profiles and, disease, GC treatment or symptoms., Results: The metabolite signature of patients with PMR and GCA differed from that of age-matched non-inflammatory controls (R 2  > 0.7). There was a smaller separation between patients with clinically confirmed GCA and those with suspected GCA who later were clinically confirmed non-GCA (R 2  = 0.135). In PMR, metabolite signatures were further altered with glucocorticoid treatment (R 2  = 0.42) but did not return to that seen in controls. Metabolites correlated with CRP, pain, stiffness, and fatigue (R 2  ≥ 0.39). CRP, pain, and stiffness declined with treatment and were associated with 3-hydroxybutyrate and acetoacetate, but fatigue did not. Metabolites differentiated patients with high and low fatigue both before and after treatment (R 2  > 0.9). Low serum glutamine was predictive of high fatigue at both time points (0.79-fold change)., Conclusion: PMR and GCA alter the metabolite signature. In PMR, this is further altered by glucocorticoid therapy. Treatment-induced metabolite changes were linked to measures of inflammation (CRP, pain and stiffness), but not to fatigue. Furthermore, metabolite signatures distinguished patients with high or low fatigue., Competing Interests: Declaration of competing interest SLM has conducted consultancy on behalf of her institution for Roche/Chugai, Sanofi, AstraZeneca, AbbVie and Pfizer; was supported by Roche to attend EULAR 2019 and by Pfizer to register for virtual attendance at ACR2021. AWM has received research funding from Roche and has conducted consultancy on behalf of her institution for Roche/Chugai, Sanofi, Regeneron, GlaxoSmithKline, AstraZeneca and Vifor. JEM and HMM have received research funding from Novartis. HMM has received funding from Roche and Pfizer. RL has received funding from Celgene, Pfizer, Roche and Vifor. Other authors have no competing interests to declare., (Copyright © 2024 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Introduction: The IL-12-IFNγ-Th1 and the IL-6-IL-23-Th17 axes are considered the dominant pathogenic pathways in Giant Cell Arteritis (GCA). Both pathways signal via activation of the downstream JAK/STAT proteins. We hypothesized that phosphorylated STAT (pSTAT) signatures in circulating immune cells may aid to stratify GCA-patients for personalized treatment., Methods: To investigate pSTAT expression, PBMCs from treatment-naive GCA-patients (n = 18), infection controls (INF, n = 11) and age-matched healthy controls (HC, n = 15) were stimulated in vitro with IL-6, IL-2, IL-10, IFN-γ, M-CSF or GM-CSF, and stained with CD3, CD4, CD19, CD45RO, pSTAT1, pSTAT3, pSTAT5 antibodies, and analyzed by flow cytometry. Serum IL-6, sIL-6-receptor and gp130 were measured by Luminex. The change in percentages of pSTAT3+CD4+T-cells was evaluated at diagnosis and at 3 months and 1-year of follow-up. Kaplan-Meier analyses was used to asses prognostic accuracy., Results: Analysis of IL-6 stimulated immune cell subsets revealed a significant decrease in percentages of pSTAT3+CD4+T-cells of GCA-patients and INF-controls compared to HCs. Following patient stratification according to high (median>1.5 pg/mL) and low (median<1.5 pg/mL) IL-6 levels, we observed a reduction in the pSTAT3 response in GCA-patients with high serum IL-6. Percentages of pSTAT3+CD4+T-cells in patients with high serum IL-6 levels at diagnosis normalized after glucocorticoid (GC) treatment. Importantly, we found that patients with low percentages of pSTAT3+CD4+T-cells at baseline require longer GC-treatment., Conclusion: Overall, in GCA, the percentages of in vitro IL-6-induced pSTAT3+CD4+T-cells likely reflect prior in vivo exposure to high IL-6 and may serve as a prognostic marker for GC-treatment duration and may assist improving personalized treatment options in the future., Competing Interests: Declaration of competing interest The other authors have declared nothing to disclose., (Copyright © 2024 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Objective: The lack of disease-specific autoantibodies in giant cell arteritis (GCA) suggests an alternative role for B-cells readily detected in the inflamed arteries. Here we study the cytokine profile of tissue infiltrated and peripheral blood B-cells of patients with GCA. Moreover, we investigate the macrophage skewing capability of B-cell-derived cytokines., Methods: The presence of various cytokines in B-cell areas in temporal artery (n = 11) and aorta (n = 10) was identified by immunohistochemistry. PBMCs of patients with GCA (n = 11) and polymyalgia rheumatica (n = 10), and 14 age- and sex-matched healthy controls (HC) were stimulated, followed by flow cytometry for cytokine expression in B-cells. The skewing potential of B-cell-derived cytokines (n = 6 for GCA and HC) on macrophages was studied in vitro., Results: The presence of IL-6, GM-CSF, TNFα, IFNγ, LTβ and IL-10 was documented in B-cells and B-cell rich areas of GCA arteries. In vitro, B-cell-derived cytokines (from both GCA and HC) skewed macrophages towards a pro-inflammatory phenotype with enhanced expression of IL-6, IL-1β, TNFα, IL-23, YKL-40 and MMP-9. In vitro stimulated peripheral blood B-cells from treatment-naïve GCA patients showed an enhanced frequency of IL-6+ and TNFα+IL-6+ B-cells compared to HCs. This difference was no longer detected in treatment-induced remission. Erythrocyte sedimentation rate positively correlated with IL-6+TNFα+ B-cells., Conclusion: B-cells are capable of producing cytokines and steering macrophages towards a pro-inflammatory phenotype. Although the capacity of B-cells in skewing macrophages is not GCA specific, these data support a cytokine-mediated role for B-cells in GCA and provide grounds for B-cell targeted therapy in GCA., Competing Interests: Declaration of competing interest KSMvdG reports personal fees from Roche, outside the submitted work. The other authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Neutrophil extracellular trap (NET) formation contributes to immune defense and is a distinct form of cell death. Excessive NET formation is found in patients with anti-neutrophil cytoplasmic antibody-associated (ANCA-associated) vasculitis (AAV), contributing to disease progression. The clearance of dead cells by macrophages, a process known as efferocytosis, is regulated by the CD47-mediated "don't eat me" signal. Hence, we hypothesized that pathogenic NETs in AAV escape from efferocytosis via the CD47 signaling pathway, resulting in the development of necrotizing vasculitis. Immunostaining for CD47 in human renal tissues revealed high CD47 expression in crescentic glomerular lesions of patients with AAV. In ex vivo studies, ANCA-induced netting neutrophils increased the expression of CD47 with the reduction of efferocytosis. After efferocytosis, macrophages displayed proinflammatory phenotypes. The blockade of CD47 in spontaneous crescentic glomerulonephritis-forming/Kinjoh (SCG/Kj) mice ameliorated renal disease and reduced myeloperoxidase-ANCA (MPO-ANCA) titers with a reduction in NET formation. Thus, CD47 blockade would protect against developing glomerulonephritis in AAV via restored efferocytosis of ANCA-induced NETs.

Objective: Proteome analyses in patients with newly diagnosed, untreated giant cell arteritis (GCA) have not been reported previously, nor are changes of protein expression upon treatment with glucocorticoids (GC) and/or tocilizumab (TCZ) known. The GUSTO trial allows to address these questions, provides the opportunity to learn about the differential effects of GC and TCZ on proteomics and may help to identify serum proteins to monitor disease activity., Methods: Serum samples obtained from 16 patients with new-onset GCA at different time points (day 0, 3, 10, and week 4, 24, 52) during the GUSTO trial (NCT03745586) were examined for 1436 differentially expressed proteins (DEPs) based on proximity extension assay technology. The patients received 500 mg methylprednisolone intravenously for 3 consecutive days followed by TCZ monotherapy., Results: When comparing day 0 (before the first GC infusion) with week 52 (lasting remission), 434 DEPs (213↑, 221↓) were identified. In response to treatment, the majority of changes occurred within 10 days. GC inversely regulated 25 proteins compared to remission. No difference was observed between weeks 24 and 52 during established remission and ongoing TCZ treatment. Expression of CCL7, MMP12, and CXCL9 was not regulated by IL6., Conclusion: Disease-regulated serum proteins improved within 10 days and were normalized within 24 weeks, showing a kinetic corresponding to the gradual achievement of clinical remission. The proteins inversely regulated by GC and TCZ shed light on the differential effects of the two drugs. CCL7, CXCL9, and MMP12 are biomarkers that reflect disease activity despite normalized C-reactive protein levels., Competing Interests: LC reports research/non-financial support, advisory fee and stock ownership from Gilead Sciences, F. Hoffmann-La Roche, Novartis, Pfizer, Bristol-Myers Squibb, and Sanofi. FB has received consultancy fees, honoraria and travel expenses from Abbvie, Galapagos, Novartis, Pfizer, Roche, and Sanofi, all unrelated to this manuscript. FK is a shareholder of Roche, was a consultant of Actelion, BMS, Boehringer-Ingelheim, and Pfizer, has grant/research support from Gilead, Pfizer and Roche, and is currently employed by Roche. PV has received consultancy fees, honoraria and travel expenses from F. Hoffmann-La Roche, MSD, Abbvie, Pfizer, Grünenthal, Amgen, Bristol-Myers Squibb, and Janssen. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be constructed as a potential conflict of interest., (Copyright © 2023 Christ, Gloor, Kollert, Gaber, Buttgereit, Reichenbach and Villiger.)

Loss of function of inhibitory immune checkpoints, unleashing pathogenic immune responses, is a potential risk factor for autoimmune disease. Here, we report that patients with the autoimmune vasculitis giant cell arteritis (GCA) have a defective CD155-CD96 immune checkpoint. Macrophages from patients with GCA retain the checkpoint ligand CD155 in the endoplasmic reticulum (ER) and fail to bring it to the cell surface. CD155 low antigen-presenting cells induce expansion of CD4 + CD96 + T cells, which become tissue invasive, accumulate in the blood vessel wall, and release the effector cytokine interleukin-9 (IL-9). In a humanized mouse model of GCA, recombinant human IL-9 causes vessel wall destruction, whereas anti-IL-9 antibodies efficiently suppress innate and adaptive immunity in the vasculitic lesions. Thus, defective surface translocation of CD155 creates antigen-presenting cells that deviate T cell differentiation toward Th9 lineage commitment and results in the expansion of vasculitogenic effector T cells., Competing Interests: Declaration of interests K.J.W. has received clinical trial support from Eli Lilly, GSK, and Kiniksa; he received consulting fees and honoraria from Chemocentryx., (Copyright © 2023 The Author(s). Published by Elsevier Inc. All rights reserved.)

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., Competing Interests: Declaration of Competing Interest Dr. Michailidou received Advisory Board fees from ChemoCentryx. Dr. Khalidi received clinical trial support from BMS, Sanofi and Abbvie, travel support from Astra Zeneca, and Advisory Board fee from Roche. Dr. Koening served on the advisory board for Chemocentryx and Genentech. Dr. Specks reports receiving funds for the following activities: Consulting: AstraZeneca, ChemoCentryx. Research Support: AstraZeneca, GlaxoSmithKline, Bristol-Myers Squibb, Genentech/Roche, InflaRx. Dr. Sreih works at Bristol-Myers Squibb and owns Astra Zeneca and Alexion Stocks. Dr. Warrington received clinical trial support from Eli Lilly and Kiniksa. Dr. Monach received consulting fees from Kiniksa, Celgene/BMC, and ChemoCentryx. Dr. Merkel reports receiving funds for the following activities: Consulting and Research Support: AbbVie, AstraZeneca, Boeringher-Ingelheim, Bristol-Myers Squibb, ChemoCentryx, Forbius, Genentech/Roche, Genzyme/Sanofi, GlaxoSmithKline, InflaRx, Takeda. Consulting only: CSL Behring, Dynacure, EMDSerono, Janssen, Kiniksa, Kyverna, Magenta, MiroBio, Neutrolis, Novartis, Pfizer, Sparrow, Talaris. Royalties: UpToDate. Dr. Lood received research funding from Pfizer, Gilead Sciences, Boehringer Ingelheim, Redd Pharma, Amytryx, and Eli Lilly., (Copyright © 2023 Elsevier Inc. All rights reserved.)

Introduction: The pathogenesis of Giant Cell Arteritis (GCA) relies on vascular inflammation and vascular remodeling, the latter being poorly controlled by current treatments., Methods: This study aimed to evaluate the effect of a novel cell therapy, Human Monocyte-derived Suppressor Cells (HuMoSC), on inflammation and vascular remodeling to improve GCA treatment. Fragments of temporal arteries (TAs) from GCA patients were cultured alone or in the presence of HuMoSCs or their supernatant. After five days, mRNA expression was measured in the TAs and proteins were measured in culture supernatant. The proliferation and migration capacity of vascular smooth muscle cells (VSMCs) were also analyzed with or without HuMoSC supernatant., Results: Transcripts of genes implicated in vascular inflammation ( CCL2 , CCR2 , CXCR3 , HLADR ), vascular remodeling ( PDGF , PDGFR ), angiogenesis (VEGF) and extracellular matrix composition ( COL1A1 , COL3A1 and FN1 ) were decreased in arteries treated with HuMoSCs or their supernatant. Likewise, concentrations of collagen-1 and VEGF were lower in the supernatants of TAs cultivated with HuMoSCs. In the presence of PDGF, the proliferation and migration of VSMCs were both decreased after treatment with HuMoSC supernatant. Study of the PDGF pathway suggests that HuMoSCs act through inhibition of mTOR activity. Finally, we show that HuMoSCs could be recruited in the arterial wall through the implication of CCR5 and its ligands., Conclusion: Altogether, our results suggest that HuMoSCs or their supernatant could be useful to decrease vascular in flammation and remodeling in GCA, the latter being an unmet need in GCA treatment., Competing Interests: MS: Roche–Chugai consulting, AbbVie consulting, Boehringer Ingelheim consulting, Novartis consulting and research grant, VIFOR Pharma consulting; BB: Roche–Chugai personal fees for consulting, Boehringer Ingelheim consulting; CC-G: Horus and Bayer grant, Novartis and Bayer honoraria and Novartis, Bayer, Thea, Horus, Alcon and Allergan medical advisory board; P-HG: Allergan, Bayer and Novartis travel expenses, Novartis and Bayer honoraria; MCC: GlaxoSmithKline consulting, CSL Vifor consulting, AbbVie consulting, Janssen consulting, Astrazeneca consulting, Kiniksa Pharmaceuticals research grant; GE-F: GlaxoSmithKline consulting, Janssen consulting. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 Samson, Genet, Corbera-Bellalta, Greigert, Espígol-Frigolé, Gérard, Cladière, Alba-Rovira, Ciudad, Gabrielle, Creuzot-Garcher, Tarris, Martin, Saas, Audia, Bonnotte and Cid.)

Introduction: Giant Cell Arteritis (GCA) is the most common systemic vasculitis worldwide. For decades, glucocorticoids have represented the mainstay of treatment, at the expense of toxic systemic effects owing to prolonged courses of high-dose treatment regimens. The search for effective drugs permitting lower glucocorticoid treatment regimens in GCA has been afrustrating one. The recent successful therapeutic application of tocilizumab, an interleukin-6 receptor inhibitor, has transformed the treatment of GCA and catalyzed research exploring other promising therapeutic targets., Areas Covered: This review explores emerging drugs in preclinical and clinical development for the management of GCA, in addition to synthesizing data on the current standard of care therapeutic agents. Drug therapies were identified by search of MEDLINE and PubMed in addition to trials from registries (clinicaltrials.gov, clinicaltrialsregister.eu, pubmed.gov) from theyear 2010., Expert Opinion: Tocilizumab has revolutionized the treatment of GCA. However, much remains to be learned about its optimal usage in GCA and asubstantial minority of pa tients do not achieve sustained glucocorticoid-free remission. Numerous exciting new agents are under investigation to fill this treatment gap in GCA, with the GM-CSF inhibitor mavrilimumab, and IL-12/23 blockade with ustekinumab providing promise through targeting the GCA pathogenic pathway in its proximal portion.

Objective: Macrophages mediate inflammation, angiogenesis, and tissue destruction in giant cell arteritis (GCA). Serum levels of the macrophage-associated protein YKL-40 (chitinase 3-like protein 1), previously linked to angiogenesis and tissue remodeling, remain elevated in GCA despite glucocorticoid treatment. This study was undertaken to investigate the contribution of YKL-40 to vasculopathy in GCA., Methods: Immunohistochemistry was performed on GCA temporal artery biopsy specimens (n = 12) and aortas (n = 10) for detection of YKL-40, its receptor interleukin-13 receptor α2 (IL-13Rα2), macrophage markers PU.1 and CD206, and the tissue-destructive protein matrix metalloproteinase 9 (MMP-9). Ten noninflamed temporal artery biopsy specimens served as controls. In vitro experiments with granulocyte-macrophage colony-stimulating factor (GM-CSF)- or macrophage colony-stimulating factor (M-CSF)-skewed monocyte-derived macrophages were conducted to study the dynamics of YKL-40 production. Next, small interfering RNA-mediated knockdown of YKL-40 in GM-CSF-skewed macrophages was performed to study its effect on MMP-9 production. Finally, the angiogenic potential of YKL-40 was investigated by tube formation experiments using human microvascular endothelial cells (HMVECs)., Results: YKL-40 was abundantly expressed by a CD206+MMP-9+ macrophage subset in inflamed temporal arteries and aortas. GM-CSF-skewed macrophages from GCA patients, but not healthy controls, released significantly higher levels of YKL-40 compared to M-CSF-skewed macrophages (P = 0.039). In inflamed temporal arteries, IL-13Rα2 was expressed by macrophages and endothelial cells. Functionally, knockdown of YKL-40 led to a 10-50% reduction in MMP-9 production by macrophages, whereas exposure of HMVECS to YKL-40 led to significantly increased tube formation., Conclusion: In GCA, a GM-CSF-skewed, CD206+MMP-9+ macrophage subset expresses high levels of YKL-40 which may stimulate tissue destruction and angiogenesis through IL-13Rα2 signaling. Targeting YKL-40 or GM-CSF may inhibit macrophages that are currently insufficiently suppressed by glucocorticoids., (© 2021 The Authors. Arthritis & Rheumatology published by Wiley Periodicals LLC on behalf of American College of Rheumatology.)

In this study, we explored expression of microRNA (miR), miR-target genes and matrix remodelling molecules in temporal artery biopsies (TABs) from treatment-naïve patients with giant cell arteritis (GCA, n = 41) and integrated these analyses with clinical, laboratory, ultrasound and histological manifestations of GCA. NonGCA patients ( n = 4) served as controls. GCA TABs exhibited deregulated expression of several miRs (miR-21-5p, -145-5p, -146a-5p, -146b-5p, -155-5p, 424-3p, -424-5p, -503-5p), putative miR-target genes ( YAP1 , PELI1 , FGF2 , VEGFA , KLF4 ) and matrix remodelling factors ( MMP2 , MMP9 , TIMP1 , TIPM2 ) with key roles in Toll-like receptor signaling, mechanotransduction and extracellular matrix biology. MiR-424-3p, -503-5p, KLF4 , PELI1 and YAP1 were identified as new deregulated molecular factors in GCA TABs. Quantities of miR-146a-5p, YAP1 , PELI1 , FGF2 , TIMP2 and MMP9 were particularly high in histologically positive GCA TABs with occluded temporal artery lumen. MiR-424-5p expression in TABs and the presence of facial or carotid arteritis on ultrasound were associated with vision disturbances in GCA patients. Correlative analysis of miR-mRNA quantities demonstrated a highly interrelated expression network of deregulated miRs and mRNAs in temporal arteries and identified KLF4 as a candidate target gene of deregulated miR-21-5p, -146a-5p and -155-5p network in GCA TABs. Meanwhile, arterial miR and mRNA expression did not correlate with constitutive symptoms and signs of GCA, elevated markers of systemic inflammation nor sonographic characteristics of GCA. Our study provides new insights into GCA pathophysiology and uncovers new candidate biomarkers of vision impairment in GCA.

Vasculitis refers to inflammation of blood vessels and can cause a variety of serious complications depending on which vessels are affected. Two different forms of vasculitis are Giant Cell Arteritis (GCA) and Granulomatosis with Polyangiitis (GPA). GCA is the most common form of vasculitis in adults affecting the large arteries and can lead to visual impairment and development of aneurysms. GPA affects small- and medium-sized blood vessels predominantly in the lungs and kidneys resulting in organ failure. Both diseases can potentially be fatal. Although the pathogenesis of GCA and GPA are incompletely understood, a prominent role for CD4+ T cells has been implicated in both diseases. More recently, the role of CD8+ T cells has gained renewed interest. CD8+ T cells are important players in the adaptive immune response against intracellular microorganisms. After a general introduction on the different forms of vasculitis and their association with infections and CD8+ T cells, we review the current knowledge on CD8+ T-cell involvement in the immunopathogenesis of GCA and GPA focusing on phenotypic and functional features of circulating and lesional CD8+ T cells. Furthermore, we discuss to which extent aging is associated with CD8+ T-cell phenotype and function in GCA and GPA., Competing Interests: AB was a consultant for Grünenthal Gmbh until 2017. EB as an employee of the UMCG received speaker/consulting fees from Roche paid to the UMCG. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Reitsema, Boots, van der Geest, Sandovici, Heeringa and Brouwer.)

Recent studies have provided evidence of a close link between specific microbiota and inflammatory disorders. While the vessel wall microbiota has been recently described in large vessel vasculitis (LVV) and controls, the blood microbiome in these diseases has not been previously reported (LVV). We aimed to analyse the blood microbiome profile of LVV patients (Takayasu's arteritis [TAK], giant cell arteritis [GCA]) and healthy blood donors (HD). We studied the blood samples of 13 patients with TAK (20 samples), 9 patients with GCA (11 samples) and 15 HD patients. We assessed the blood microbiome profile by sequencing the 16S rDNA blood bacterial DNA. We used linear discriminant analysis (LDA) coupled with linear discriminant effect size measurement (LEfSe) to investigate the differences in the blood microbiome profile between TAK and GCA patients. An increase in the levels of Clostridia, Cytophagia and Deltaproteobacteria and a decrease in Bacilli at the class level were found in TAK patients compared with HD patients (LDA > 2, p < 0.05). Active TAK patients had significantly lower levels of Staphylococcus compared with inactive TAK patients. Samples of GCA patients had an increased abundance of Rhodococcus and an unidentified member of the Cytophagaceae family. Microbiota of TAK compared with GCA patients was found to show higher levels of Candidatus Aquiluna and Cloacibacterium (LDA > 2; p < 0.05). Differences highlighted in the blood microbiome were also associated with a shift of bacterial predicted metabolic functions in TAK in comparison with HD. Similar results were also found in patients with active versus inactive TAK. In conclusion, patients with TAK were found to present a specific blood microbiome profile in comparison with healthy donors and GCA subjects. Significant changes in the blood microbiome profiles of TAK patients were associated with specific metabolic functions.

Giant cell arteritis (GCA) is a granulomatous systemic vasculitis of large- and medium-sized arteries that affects the elderly. In recent years, advances in diagnostic imaging have revealed a greater degree of large vessel involvement than previously recognized, distinguishing classical cranial- from large vessel (LV)- GCA. GCA often co-occurs with the poorly understood inflammatory arthritis/bursitis condition polymyalgia rheumatica (PMR) and has overlapping features with other non-infectious granulomatous vasculitides that affect the aorta, namely Takayasu Arteritis (TAK) and the more recently described clinically isolated aortitis (CIA). Here, we review the literature focused on the immunopathology of GCA on the background of the three settings in which comparisons are informative: LV and cranial variants of GCA; PMR and GCA; the three granulomatous vasculitides (GCA, TAK, and CIA). We discuss overlapping and unique features between these conditions across clinical presentation, epidemiology, imaging, and conventional histology. We propose a model of GCA where abnormally activated circulating cells, especially monocytes and CD4 + T cells, enter arteries after an unknown stimulus and cooperate to destroy it and review the evidence for how this mechanistically occurs in active disease and improves with treatment., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Robinette, Rao and Monach.)

Giant cell arteritis (GCA) is a common form of primary systemic vasculitis in adults, with no reliable indicators of prognosis or treatment responses. We used single cell technologies to comprehensively map immune cell populations in the blood of patients with GCA and identified the CD66b+CD15+CD10lo/-CD64- band neutrophils and CD66bhiCD15+CD10lo/-CD64+/bright myelocytes/metamyelocytes to be unequivocally associated with both the clinical phenotype and response to treatment. Immature neutrophils were resistant to apoptosis, remained in the vasculature for a prolonged period of time, interacted with platelets, and extravasated into the tissue surrounding the temporal arteries of patients with GCA. We discovered that immature neutrophils generated high levels of extracellular reactive oxygen species, leading to enhanced protein oxidation and permeability of endothelial barrier in an in vitro coculture system. The same populations were also detected in other systemic vasculitides. These findings link functions of immature neutrophils to disease pathogenesis, establishing a clinical cellular signature of GCA and suggesting different therapeutic approaches in systemic vascular inflammation.

Introduction: Giant cell arteritis (GCA) is a large vessel (LV) vasculitis, mainly affecting elder patients. Monitoring GCA activity during tocilizumab (TCZ) treatment is an unmet need, since low serum levels of C-reactive protein (CRP) during treatment may underestimate disease activity. To date, few data are available on the role of different imaging techniques in monitoring GCA activity and response to treatment. We report herein a cohort of GCA patients treated with TCZ and followed up with multimodal imaging. Patients and Methods . We collected clinical, laboratory, and imaging data of 11 GCA patients treated with TCZ 162 mg subcutaneously every week. Disease activity was assessed at baseline and within 12 months from the start of treatment using different imaging techniques such as color Doppler ultrasonography (CDUS), magnetic resonance imaging/angiography (MRI/MRA), computed tomography angiography (CTA), and/or positron emission tomography (PET)., Results: Four patients were affected by cranial and 7 by LV-GCA. All patients were treated with oral glucocorticoids (GCs) (mean dose 55.68 mg ± 8.19 of prednisone or equivalent) in combination with TCZ. Treatment was preceded in 5 cases by 3 intravenous boluses of 1000 mg methylprednisolone. A significant decrease of the mean dose of oral GCs was observed between baseline and the last follow-up visit (4.65 ± 3.69 mg) ( p = 0.003). TCZ treatment significantly decreased erythrocyte sedimentation rate ( p < 0.01) and CRP levels ( p < 0.01). At follow-up (mean 8.18 ± 3.63 months), all patients were in clinical and serological remission. Moreover, PET, CDUS, MRI/MRA, and CTA did not show any LVV finding., Conclusions: Our study highlights TCZ efficacy in inducing GCA remission and its steroid-sparing effect. We highlighted a reliability of imaging procedures in the evaluation of disease activity and treatment response. A close disease monitoring with imaging techniques should be taken into account in GCA patients during TCZ treatment., Competing Interests: The authors declare that the research was carried out in the absence of any personal, professional, or financial relationships that could potentially be construed as a conflict of interest., (Copyright © 2020 Edoardo Conticini et al.)

Giant cell arteritis (GCA) is the most common type of primary vasculitis in Western countries. Polymyalgia rheumatica (PMR) is the second most common inflammatory rheumatic disease of the elderly after rheumatoid arthritis. Glucocorticoids are the cornerstone of treatment for GCA and PMR, which are interrelated diseases. Glucocorticoids are effective, but adverse effects occur in a high proportion of patients. Careful use of glucocorticoids and the application of preventive strategies can minimize these adverse effects. Possible long-term complications of GCA include aneurysm and stenosis of vessels, even in patients with apparently clinically inactive disease; acute blindness is rare during glucocorticoid treatment. In PMR, whether subclinical chronic inflammation can lead to long-term damage is less clear. Management of both GCA and PMR is hampered by the lack of universally accepted definitions of remission and other disease states, such as low disease activity or vessel damage without active disease. In this Review, we outline current evidence on the monitoring and long-term management of patients with GCA and PMR, including the tapering of treatment.

AL amyloidosis (AL) is a systemic disorder due to extracellular tissue deposition of amyloid fibrils, composed of immunoglobulin light chains. Since the description of AL involving temporal arteries in 1986, this disorder has been known as one of the differential diagnoses of giant cell arteritis (GCA). We encountered a case of an elderly female presenting with headache and tender and enlarged temporal arteries, that was pathologically diagnosed with temporal artery involvement of AL due to Bence-Jones-type MM. To our knowledge, this was the first case of AL with temporal artery involvement in Japan, that presented with GCA-like features. Literature review of AL cases with temporal artery involvement showed close similarity between these disorders, but suggested that vasculature involvement (extremity claudication, kidney or heart), macroglossia, carpal tunnel syndrome and normal or low (<0.5 mg/dL) CRP levels may predict AL rather than GCA. Physicians should keep in mind that AL involving temporal arteries can be a pitfall in the diagnosis of GCA, as seen in our and previous cases.

Objectives: To analyse the current evidence for the management of large vessel vasculitis (LVV) to inform the 2018 update of the EULAR recommendations., Methods: Two systematic literature reviews (SLRs) dealing with diagnosis/monitoring and treatment strategies for LVV, respectively, were performed. Medline, Embase and Cochrane databases were searched from inception to 31 December 2017. Evidence on imaging was excluded as recently published in dedicated EULAR recommendations. This paper focuses on the data relevant to giant cell arteritis (GCA)., Results: We identified 287 eligible articles (122 studies focused on diagnosis/monitoring, 165 on treatment). The implementation of a fast-track approach to diagnosis significantly lowers the risk of permanent visual loss compared with historical cohorts (level of evidence, LoE 2b). Reliable diagnostic or prognostic biomarkers for GCA are still not available (LoE 3b).The SLR confirms the efficacy of prompt initiation of glucocorticoids (GC). There is no high-quality evidence on the most appropriate starting dose, route of administration, tapering and duration of GC (LoE 4). Patients with GCA are at increased risk of dose-dependent GC-related adverse events (LoE 3b). The addition of methotrexate or tocilizumab reduces relapse rates and GC requirements (LoE 1b). There is no consistent evidence that initiating antiplatelet agents at diagnosis would prevent future ischaemic events (LoE 2a). There is little evidence to guide monitoring of patients with GCA., Conclusions: Results from two SLRs identified novel evidence on the management of GCA to guide the 2018 update of the EULAR recommendations on the management of LVV., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2019. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)

Giant cell arteritis and Takayasu arteritis are autoimmune vasculitides that cause aneurysm formation and tissue infarction. Extravascular inflammation consists of an intense acute phase response. Deeper understanding of pathogenic events in the vessel wall has highlighted the loss of tissue protective mechanisms, the intrusion of immune cells into "forbidden territory", and the autonomy of self-renewing vasculitic infiltrates. Adventitial vasa vasora critically control vessel wall access and drive differentiation of tissue-invasive T cells. Selected T cells establish tissue residency and build autonomous, self-sufficient inflammatory lesions. Pathogenic effector T cells intrude and survive due to failed immune checkpoint inhibition. Vasculitis-sustaining T cells and macrophages provide a broad portfolio of effector functions, involving heterogeneous populations of pro-inflammatory T cells and diverse macrophage subsets that ultimately induce wall capillarization and intimal hyperplasia. Redirecting diagnostic and therapeutic strategies from control of extravascular inflammatory markers to suppression of vascular inflammation will improve disease management., (Copyright © 2019. Published by Elsevier Inc.)

Giant cell arteritis (GCA) and polymyalgia rheumatica (PMR) are inflammatory diseases requiring long-term glucocorticoid treatment. Limited data on dynamics in leukocyte counts before, during and after treatment are available. Leukocyte counts were measured, as cellular markers of inflammation, at fixed time points in our prospectively studied cohort of pre-treatment glucocorticoid-naive GCA ( N = 42) and PMR ( N = 31) patients. Values were compared with age-matched healthy controls (HCs; N = 51) and infection controls ( N = 16). We report that before start of treatment monocyte and neutrophil counts were higher in GCA and PMR patients than in HCs, while NK- and B-cell counts were lower. C-reactive protein (CRP) levels correlated positively with monocyte counts in GCA, and negatively with B-cell and NK-cell counts in PMR. During glucocorticoid treatment, myeloid subsets remained elevated whereas lymphoid subsets tended to fluctuate. Interestingly, erythrocyte sedimentation rate (ESR) outperformed CRP as marker for relapses in GCA. We defined stable treatment-free remission groups in both GCA and PMR. GCA patients in treatment-free remission still demonstrated elevated monocytes, neutrophils, ESR, and platelets. PMR patients in treatment-free remission had normalized levels of inflammation markers, but did have elevated monocytes, lowered CD8+ T-cell counts and lowered NK-cell counts. Finally, we showed that low hemoglobin level was predictive for long-term GC treatment in PMR. Overall, leukocyte composition shifts toward the myeloid lineage in GCA and PMR. This myeloid profile, likely induced by effects of inflammation on hematopoietic stem cell differentiation, persisted during glucocorticoid treatment. Surprisingly, the myeloid profile was retained in treatment-free remission, which may reflect ongoing subclinical inflammation.

Giant cell arteritis (GCA) is the most common form of vasculitis in adults. Cranial manifestations are typical clinical features of this vasculitis. Sometimes the presenting symptoms are nonspecific and, in some cases, large-vessel involvement may prevail. Polymyalgia rheumatica is a frequent manifestation that in some cases may be the presenting symptom of GCA. Visual complications, in particular the risk of blindness, constitute the most feared manifestations of GCA. Prompt recognition of this vasculitis is required to avoid irreversible complications. Prednisone/prednisolone at a dose of 40-60 mg/day is the cornerstone therapy in GCA. Glucocorticoids lead to rapid improvement of symptoms and may reduce the risk of irreversible visual loss. However, relapses are common when the prednisone dose is tapered. Therefore, additional therapies are required in relapsing GCA or when a rapid reduction of glucocorticoids is needed. The most widely used conventional immunosuppressive drug is methotrexate Adjunctive treatment with methotrexate may decrease the risk of relapses and reduce glucocorticoid exposure. However, comprehensive reviews indicate that the efficacy of methotrexate in GCA is modest. The experience with other conventional immunosuppressive drugs in GCA patients is scarce. In some cases, the new biologic agents are required. Among them, the most frequently used is the recombinant humanized anti-IL-6 receptor antibody tocilizumab. It improves clinical symptoms, reduce the cumulative prednisone dose and the frequency of relapses in GCA patients. However, anti-tumor necrosis factor-α therapy is not useful in GCA. Promising results on other biologic agents, such as abatacept, ustekinumab or anakinra, require further confirmatory studies., (Copyright © 2019 Elsevier Inc. All rights reserved.)

Objectives: To investigate whether expression of pro-inflammatory cytokines in the temporal artery may aid in differentiating biopsy-negative giant cell arteritis (GCA) patients from those with a negative biopsy without arteritis., Methods: We investigated cytokine expression in temporal artery biopsy (TAB) of 54 consecutive patients: 17 with biopsy-positive GCA, 17 with biopsy-negative GCA, and 20 biopsy-negative without arteritis. We compared the expression rate of the following cytokines among these 3 groups of patients: interleukin-6 (IL-6), osteopontin (OPN), COX-2, and TNF-α., Results: IL-6 was expressed in 13 (76%) patients with biopsy-positive GCA, 0 patients in biopsy-negative GCA, and 1(5%) patient with biopsy-negative without arteritis (p<0.05). OPN was expressed in 17 (100%) patients with biopsy-positive GCA, 2 (12%) patients with biopsy-negative GCA, and 0 patients with biopsy-negative without arteritis (p<0.05). Cox-2 was expressed in 16 (94%) patients with biopsy-positive GCA, 0 patients with biopsy-negative GCA, and 3 (15%) patients with biopsy-negative without arteritis (p<0.05). TNF- α was expressed in 17 (100%) patients with biopsy-positive GCA, 14 (82%) patients with biopsy-negative GCA, and 8 (40%) patients with biopsy-negative without arteritis (p<0.05)., Conclusions: IL-6, COX-2 and OPN are significantly more expressed in the presence of a positive TAB compared to a negative TAB. TNF-α is significantly more expressed in GCA patients compared to non-GCA patients. Thus, TNF-α expression may suggest a diagnosis of GCA despite a negative TAB. Further larger studies are needed to confirm these findings.

Background: Although giant cell arteritis (GCA) is a well-known cause of transient and permanent vision loss, diplopia as a presenting symptom of this condition is uncommon. We compared symptoms and signs of patients presenting with diplopia from GCA to those from other causes., Methods: This was a multicenter, retrospective study comparing the clinical characteristics of patients presenting with diplopia from GCA with age-matched controls. Demographic information, review of symptoms, ophthalmic examination, and laboratory data of biopsy-proven patients with GCA were compared with those of age-matched controls presenting with diplopia., Results: A total of 27 patients presented with diplopia from GCA, 19 with constant diplopia, and 8 with transient diplopia. All patients with constant diplopia from GCA were matched with 67 control subjects who had diplopia from other etiologies. Patients with GCA were more likely to describe other accompanying visual symptoms (58% vs 25%, P = 0.008), a greater number of systemic GCA symptoms (3.5, GCA vs 0.6, controls, P < 0.001) such as headache (94% [17/18] vs 39% [23/67]; P < 0.001), jaw claudication (80% [12/15] vs 0% [0/36]; P < 0.001), and scalp tenderness (44% [7/16] vs 7% [3/43]; P < 0.001). Ocular ischemic lesions (26% vs 1%, P < 0.001) were also common in patients with diplopia from GCA. Inflammatory markers were elevated significantly in patients with GCA vs controls (erythrocyte sedimentation rate: 91% [10/11] vs 12% [3/25], P < 0.001; C-reactive protein: 89% [8/9] vs 11% [2/19], P < 0.001)., Conclusions: GCA is a rare but serious cause of diplopia among older adults and must be differentiated from other more common benign etiologies. Our study suggests that most patients with diplopia from GCA have concerning systemic symptoms and/or elevated inflammatory markers that should trigger further work-up. Moreover, careful ophthalmoscopic examination should be performed to look for presence of ocular ischemic lesions in older patients presenting with acute diplopia.

Giant cell arteritis (GCA) is a chronic immune-mediated disease of medium-to-large sized arteries that affects older adults. GCA manifests with arthritis and occlusive symptoms of headaches, stroke or vision loss. Macrophages and T-helper lymphocytes infiltrate the vascular wall and produce a pro-inflammatory response that lead to vessel damage and ischemia. To date, there is no GCA biomarker that can monitor disease activity and guide therapeutic response. Folate receptor beta (FRB) is a glycosylphosphatidylinositol protein that is anchored on cell membranes and normally expressed in the myelomonocytic lineage and in the majority of myeloid leukemia cells as well as in tumor and rheumatoid synovial macrophages, where its expression correlates with disease severity. The ability of FRB to bind folate compounds, folic acid-conjugates and antifolate drugs has made it a druggable target in cancer and inflammatory disease research. This report describes the histopathologic and immunohistochemical methods used to assess expression and distribution of FRB in relation to GCAimmunopathology. Formalin-fixed and paraffin-embedded temporal artery biopsies from GCA and normal controls were stained with Hematoxylin and Eosin to review tissue histology and identify pathognomonic features.Immunohistochemistry was used to detect FRB, CD68 and CD3 expression. A microscopic analysis was performed to quantify the number of positively stained cells on 10 selected high-power-field sections and their respective locations in the arterial wall. Lymphohistiocytic (LH) inflammation accompanied by intimal hyperplasia and disrupted elastic lamina was seen in GCA with none found in controls. The LH infiltrate was composed of approximately 60% lymphocytes and 40% macrophages. FRB expression was restricted to macrophages, comprising 31% of the total CD68+ macrophage population and localized to the media and adventitia. No FRB was seen in controls. This protocol demonstrated a distinct numerical and spatial pattern of the FRB macrophage relative to the vascular immune microenvironment in GCA.

Giant cell arteritis (GCA) primarily involves medium-to-large arteries. Small-vessel inflammation is a recognized phenomenon occurring in association with GCA. However, its significance is poorly elucidated. Histologic sections and medical records of105 temporal artery specimens were retrospectively reviewed between 2008 and 2017 to examine associated clinical manifestations and laboratory data including antinuclear antibody and p-antineutrophilic cytoplasmic antibody titers. Immunohistochemical staining for CD4 and CD8 was performed in select cases to assess the nature of the inflammatory response. Seventy-eight patients meeting the diagnostic criteria of temporal arteritis were included in the analysis. Twenty-eight specimens demonstrated temporal arteritis with small arterial inflammation (SAI), and 50 specimens showed temporal arteritis without SAI. Eight (28.6%) of 28 patients with SAI presented with jaw claudication, whereas 5 (17.9%) were febrile at presentation. In contrast, in 50 patients without SAI, jaw claudication and fever were seen in 11 and 2 cases, respectively (P = .01 and P = .0047, respectively). No statistically significant difference was noted between other symptoms and laboratory indices between the 2 groups. Elevated p-antineutrophilic cytoplasmic antibody titers in GCA may be associated with concomitant polymyalgia rheumatica or treatment-resistant disease. We also identified a higher count of CD4 and CD8 T cells in SAI cases, although the ratio of CD4/CD8 T lymphocytes was within normal limits. In conclusion, simultaneous involvement of arterioles and medium- to large-sized arteries is common in GCA and may be associated with treatment-refractory disease. Documentation of small arterial involvement in GCA will help the clinicians to manage the disease more effectively., (Copyright © 2018 Elsevier Inc. All rights reserved.)

Purpose: To provide quantitative evidence linking the CD68 (cluster of differentiation 68)+ macrophage marker found on temporal artery biopsies (TABs) with disease prognosis., Design: Retrospective, cross-sectional study., Methods: We examined 42 consecutive patients who had undergone unilateral TABs at a single hospital in 2015. Clinical data, laboratory data, and histopathologic features of TABs were recorded. Inclusion criteria were clinical diagnosis of giant cell arteritis (GCA) with TAB performed at the same center. CD68 immunohistochemistry was used to label macrophages in the TABs. Primary outcome was multiple logistic regression and bivariate comparisons to measure the association between CD68+ cells per histologic section with placement on immunomodulatory therapy (IMT)., Results: Twenty seven patients were female (64%), with a mean age of 72 (standard deviation [SD.] ±7.7). Eleven patients (26%) were placed on IMT, 17 (40%) had disease recurrence during steroid taper, and 25 (60%) were referred to rheumatology. Of 42 biopsies, 35 underwent staining with CD68 to confirm active inflammation in suspicious, but not diagnostic, specimens. Patients eventually placed on IMT had increased CD68+ cells per slice compared to those not on IMT (median 5.00 [25th-75th quartile 2.00-7.15] vs 1.21 [0.38-2.57], P = .031, respectively). A receiver operating characteristic (ROC) curve demonstrates that 2.17 CD68+ cells/slice predicts placement on IMT with an odds ratio of 1.54 (95% confidence interval 1.02-2.33, P = .038)., Conclusions: Patients refractory to initial steroid tapers and those eventually placed on IMT had increased CD68 cells per section. CD68+ macrophages and their location on the internal elastic lamina may predict disease severity in patients with presumed GCA. Our results suggest that this marker may expedite patient triaging to alternate treatment to the usual steroid therapy., (Copyright © 2018 Elsevier Inc. All rights reserved.)

Objective: To evaluate whether CD3 staining performed routinely on temporal artery biopsy specimens might improve the sensitivity of temporal artery biopsy in patients with biopsy-negative GCA., Methods: Two hundred and seventy biopsies were considered for this study, stained with haematoxylin and eosin and with an anti-CD3 antibody., Results: The addition of CD3 staining modified the sensibility and the specificity of the histologic examination in 89.47 and 95.00%, respectively, with a positive and negative predictive values of 97.00 and 79.78% ., Conclusion: The addition of CD3 immunostaining to the classic histologic evaluation is accompanied by a significant increase in the sensibility with a comparable specificity.

Introduction: Giant cell arteritis (GCA) is the most frequent type of vasculitis, occurring in people older than 50 years. So far, treatment has been limited to corticosteroids and methotrexate only. Areas covered: Interleukin-6 (IL-6) plays a role in the pathophysiology of GCA. This review covers recent advances in the treatment of GCA with tocilizumab (TCZ), which specifically binds to both soluble and membrane-bound IL-6R and inhibits IL-6R-mediated signaling. Expert commentary: Two randomized controlled trials recently showed the efficacy of the IL-6 receptors inhibitor monoclonal antibody TCZ for the induction and maintenance of remission in patients with new-onset and relapsing GCA. Furthermore, addition of TCZ to prednisone led to a reduction in the cumulative prednisone doses required to control GCA. The profile of adverse events was balanced across treatment groups and no safety concerns were raised during the trial.

A lack of absolute correlation between systemic inflammation parameters and ongoing vascular disease activity is an important problem in some patients with large vessel vasculitis, especially Takayasu arteritis (TAK). Systemic and vascular wall inflammation in TAK are obviously interrelated, but sometimes they may act independently. There are clear discrepancies between these two types of inflammation, including cytokine patterns and responses to treatment. Vascular and systemic inflammation may also be discordant in two subgroups of giant cell arteritis. The first subgroup is mainly characterized by severe systemic inflammation mostly associated with IL-6-driven immunity, while in the second subgroup there is less systemic inflammation but prominent neuro-ophthalmic ischaemic complications characterized mostly by IFN-γ-mediated effects. Although no definite boundaries exist, it may be suggested that the IL-6/Th17/IL-17 pathway primarily drives systemic inflammation while the IL-12/Th1/IFN-γ pathway dominates in vascular wall inflammation both in TAK and giant cell arteritis. Immunosuppressive treatment of TAK (especially corticosteroids) initially suppresses systemic inflammation, while longer treatment duration is required for the suppression of vascular inflammation. Therefore, evaluating only the systemic inflammation may be misleading. Vascular wall inflammation is currently evaluated using expensive imaging methods, which are not feasible for repetitive use. Although pentraxin-3 is superior to erythrocyte sedimentation rate and CRP, we need more reliable biomarkers to reflect vascular wall inflammation in patients with TAK.

Because of their vital function, the wall structures of medium and large arteries are immunoprivileged and protected from inflammatory attack. That vascular immunoprivilege is broken in atherosclerosis and in vasculitis, when wall-invading T cells and macrophages (Mϕ) promote tissue injury and maladaptive repair. Historically, tissue-residing T cells were studied for their antigen specificity, but recent progress has refocused attention to antigen-nonspecific regulation, which determines tissue access, persistence, and functional differentiation of T cells. The coinhibitory receptor PD-1, expressed on T cells, delivers negative signals when engaged by its ligand PD-L1, expressed on dendritic cells, Mϕ, and endothelial cells to attenuate T cell activation, effector functions, and survival. Through mitigating signals, the PD-1 immune checkpoint maintains tissue tolerance. In line with this concept, dendritic cells and Mϕs from patients with the vasculitic syndrome giant cell arteritis (GCA) are PD-L1 lo ; including vessel-wall-embedded DCs that guard the vascular immunoprivilege. GCA infiltrates in the arterial walls are filled with PD-1 + T cells that secrete IFN-γ, IL-17, and IL-21; drive inflammation-associated angiogenesis; and facilitate intimal hyperplasia. Conversely, chronic tissue inflammation in the atherosclerotic plaque is associated with an overreactive PD-1 checkpoint. Plaque-residing Mϕs are PD-L1 hi , a defect induced by their addiction to glucose and glycolytic breakdown. PD-L1 hi Mϕs render patients with coronary artery disease immunocompromised and suppress antiviral immunity, including protective anti-varicella zoster virus T cells. Thus, immunoinhibitory signals affect several domains of vascular inflammation; failing PD-L1 in vasculitis enables unopposed immunostimulation and opens the flood gates for polyfunctional inflammatory T cells, and excess PD-L1 in the atherosclerotic plaque disables tissue-protective T cell immunity., (©2017 Society for Leukocyte Biology.)

Objectives: GCA is characterized by arterial remodelling driven by inflammation. IL-22 is an attractive cytokine which acts at the crosstalk between immune and stromal cells. We hypothesized that IL-22 might be induced in GCA and might be involved in disease pathogenesis., Methods: Patients subjected to temporal artery biopsies (TABs) naïve from therapy were enrolled: 27 biopsy-proven GCA, 8 biopsy-negative GCA, 21 biopsy-negative non-GCA patients. Expression of IL-22 was determined in TABs by immunohystochemistry, in plasma by ELISA, in peripheral blood mononuclear cells by real-time PCR and flow cytometry. Effects of IL-22 on viability and gene expression of primary cultures obtained from TABs were also evaluated., Results: Inflamed TABs from GCA patients showed a higher expression of IL-22 and IL-22 specific receptor subunit (IL-22R1) than non-inflamed TABs. IL-22 was expressed in infiltrating immune cells and spindle shaped cells, IL-22R1 was expressed in endothelial cells. Patients with biopsy-proven GCA showed increased levels of IL-22 in plasma than patients with biopsy-negative GCA, without GCA and healthy subjects. Peripheral blood mononuclear cells from GCA patients expressed higher IL-22 transcript than healthy subjects. After stimulation in vitro with phorbol 12-myristate 13-acetate and ionomycin, the frequencies of Th22 and IL-22+ CD4+ lymphocytes were similar between patients with and without GCA. Treatment with IL-22 of primary cultures obtained from TABs increased cell viability under stress conditions and expression of B-cell activating factor., Conclusion: IL-22 is increased in patients with GCA and affects viability and gene expression of arterial cells, supporting a potential role in disease pathogenesis., (© The Author 2017. Published by Oxford University Press on behalf of the British Society for Rheumatology. All rights reserved. For Permissions, please email: journals.permissions@oup.com)

The increasing availability and improvement of imaging techniques are deeply influencing diagnosis and work-up of patients affected with vasculitis, particularly those with large vessel vasculitis (LVV). Fluorodeoxyglucose ( 18 F-FDG) positron emission tomography (PET), especially when integrated with computed tomography (CT), is taking hold as a useful diagnostic technique to examine the aorta and the other large vessels in giant cell arteritis (GCA) with concomitant large vessel involvement (LV-GCA). In this paper we examined the progresses performed in this field in the last twenty years and the evidence available so far according to two different points of view ('pros' and 'cons'), in order to give a comprehensive answer to a still open question about the role of PET/CT in the diagnosis and follow-up of GCA., (Copyright © 2017 Elsevier B.V. All rights reserved.)

Giant cell arteritis is the most common primary vasculitis of the elderly. The acute complications of untreated giant cell arteritis, such as vision loss or occasionally stroke, can be devastating. The diagnosis is, however, not altogether straightforward due to variable sensitivities of the temporal artery biopsy as a reference diagnostic test. In this review, we discuss the increasing role of imaging in the diagnosis of giant cell arteritis. Glucocorticoid treatment is the backbone of therapy, but it is associated with significant adverse effects. A less toxic alternative is required. Conventional and novel immunosuppressive agents have only demonstrated modest effects in a subgroup of steroid refractory Giant cell arteritis due to the different arms of the immune system at play. However, recently a study of interleukin-6 blockade demonstrated benefits of giant cell arteritis. The current status of these immunosuppressive agents and novel therapies are also discussed in this review., (© 2017 Royal Australasian College of Physicians.)

Background: Giant-cell arteritis (GCA) is an inflammatory disease of large/medium-sized arteries, frequently involving the temporal arteries (TA). Inflammation-induced vascular remodelling leads to vaso-occlusive events. Circulating endothelin-1 (ET-1) is increased in patients with GCA with ischaemic complications suggesting a role for ET-1 in vascular occlusion beyond its vasoactive function., Objective: To investigate whether ET-1 induces a migratory myofibroblastic phenotype in human TA-derived vascular smooth muscle cells (VSMC) leading to intimal hyperplasia and vascular occlusion in GCA., Methods and Results: Immunofluorescence/confocal microscopy showed increased ET-1 expression in GCA lesions compared with control arteries. In inflamed arteries, ET-1 was predominantly expressed by infiltrating mononuclear cells whereas ET receptors, particularly ET-1 receptor B (ET B R), were expressed by both mononuclear cells and VSMC. ET-1 increased TA-derived VSMC migration in vitro and α-smooth muscle actin (αSMA) expression and migration from the media to the intima in cultured TA explants. ET-1 promoted VSMC motility by increasing activation of focal adhesion kinase (FAK), a crucial molecule in the turnover of focal adhesions during cell migration. FAK activation resulted in Y397 autophosphorylation creating binding sites for Src kinases and the p85 subunit of PI3kinases which, upon ET-1 exposure, colocalised with FAK at the focal adhesions of migrating VSMC. Accordingly, FAK or PI3K inhibition abrogated ET-1-induced migration in vitro. Consistently, ET-1 receptor A and ET B R antagonists reduced αSMA expression and delayed VSMC outgrowth from cultured GCA-involved artery explants., Conclusions: ET-1 is upregulated in GCA lesions and, by promoting VSMC migration towards the intimal layer, may contribute to intimal hyperplasia and vascular occlusion in GCA., Competing Interests: Competing interests: None declared., (© Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2017. All rights reserved. No commercial use is permitted unless otherwise expressly granted.)

Giant cell arteritis (GCA) causes autoimmune inflammation of the aorta and its large branches, resulting in aortic arch syndrome, blindness, and stroke. CD4 + T cells and macrophages form organized granulomatous lesions in the walls of affected arteries, destroy the tunica media, and induce ischemic organ damage through rapid intimal hyperplasia and luminal occlusion. Pathogenic mechanisms remain insufficiently understood; specifically, it is unknown whether the unopposed activation of the immune system is because of deficiency of immunoinhibitory checkpoints. Transcriptome analysis of GCA-affected temporal arteries revealed low expression of the coinhibitory ligand programmed death ligand-1 (PD-L1) concurrent with enrichment of the programmed death-1 (PD-1) receptor. Tissue-residing and ex vivo-generated dendritic cells (DC) from GCA patients were PD-L1 lo , whereas the majority of vasculitic T cells expressed PD-1, suggesting inefficiency of the immunoprotective PD-1/PD-L1 immune checkpoint. DC-PD-L1 expression correlated inversely with clinical disease activity. In human artery-SCID chimeras, PD-1 blockade exacerbated vascular inflammation, enriched for PD-1 + effector T cells, and amplified tissue production of multiple T-cell effector cytokines, including IFN-γ, IL-17, and IL-21. Arteries infiltrated by PD-1 + effector T cells developed microvascular neoangiogenesis as well as hyperplasia of the intimal layer, implicating T cells in the maladaptive behavior of vessel wall endogenous cells. Thus, in GCA, a breakdown of the tissue-protective PD1/PD-L1 checkpoint unleashes vasculitic immunity and regulates the pathogenic remodeling of the inflamed arterial wall., Competing Interests: The authors declare no conflict of interest.

CD8(+) T cells participate in the pathogenesis of some vasculitides. However, little is known about their role in Giant Cell Arteritis (GCA). This study was conducted to investigate CD8(+) T cell involvement in the pathogenesis of GCA. Analyses were performed at diagnosis and after 3 months of glucocorticoid treatment in 34 GCA patients and 26 age-matched healthy volunteers. Percentages of CD8(+) T-cell subsets, spectratype analysis of the TCR Vβ families of CD8(+) T cells, levels of cytokines and chemokines and immunohistochemistry of temporal artery biopsies (TAB) were assessed. Among total CD8(+) T cells, percentages of circulating cytotoxic CD8 T lymphocytes (CTL, CD3(+)CD8(+)perforin(+)granzymeB(+)), Tc17 (CD3(+)CD8(+)IL-17(+)), CD63(+)CD8(+) T cells and levels of soluble granzymes A and B were higher in patients than in controls, whereas the percentage of Tc1 cells (CD3(+)CD8(+)IFN-γ(+)) was similar. Moreover, CD8(+) T cells displayed a restricted TCR repertoire in GCA patients. Percentages of circulating CTL, Tc17 and soluble levels of granzymes A and B decreased after treatment. CXCR3 expression on CD8(+) T cells and its serum ligands (CXCL9, -10, -11) were higher in patients. Analyses of TAB revealed high expression of CXCL9 and -10 associated with infiltration by CXCR3(+)CD8(+) T cells expressing granzyme B and TiA1. The intensity of the CD8 T-cell infiltrate in TAB was predictive of the severity of the disease. This study demonstrates the implication and the prognostic value of CD8(+) T-cells in GCA and suggests that CD8(+) T-cells are recruited within the vascular wall through an interaction between CXCR3 and its ligands., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

Recent analysis of archived temporal arteries (TAs) acquired from 13 pathology laboratories in the US, Canada, Iceland, France, Germany and Israel from patients with pathologically-verified giant cell arteritis (GCA-positive) and TAs from patients with clinical features and laboratory abnormalities of GCA but whose TAs were pathologically negative (GCA-negative) revealed VZV antigen in most TAs from both groups. Despite formalin-fixation, VZV DNA was also found in many VZV-antigen positive sections that were scraped, subjected to DNA extraction, and examined by PCR with VZV-specific primers. Importantly, in past studies, the pathological diagnosis (GCA-positive or -negative) was known to the neurovirology laboratory. Herein, GCA-positive and GCA-negative TAs were provided by an outside institution and examined by 4 investigators blinded to the pathological diagnoses. VZV antigen was found in 3/3 GCA-positive TAs and in 4/6 GCA-negative TAs, and VZV DNA in 1/3 VZV antigen-positive, GCA-positive TAs and in 3/4 VZV antigen-positive, GCA-negative TAs. VZV DNA was also detected in one GCA-negative, VZV-antigen negative TA. Overall, the detection of VZV antigen in 78% of GCA-positive and GCA-negative TAs is consistent with previous reports on the prevalence of VZV antigen in patients with clinically suspect GCA., (Copyright © 2016 Elsevier B.V. All rights reserved.)

The Rho kinases, or ROCKs, are a family of serine-threonine kinases that serve as key downstream effectors for Rho GTPases. The ROCKs are increasingly recognized as critical coordinators of a tissue response to injury due to their ability to modulate a wide range of biological processes. Dysregulated ROCK activity has been implicated in several human pathophysiological conditions ranging from cardiovascular and renal disorders to fibrotic diseases. In recent years, an important role for the ROCKs in the regulation of immune responses is also being uncovered. We provide an overview of the role of the ROCKs in immune cells and discuss studies that highlight the emerging involvement of this family of kinases in the pathogenesis of autoimmune diseases. Given the potential promise of the ROCKs as therapeutic targets, we also outline the approaches that could be employed to inhibit the ROCKs in autoimmune disorders.

Objective: Giant cell arteritis (GCA) is pathologically characterized by dysfunctional angiogenesis and inflammatory cell infiltration. Acute-phase serum amyloid A (A-SAA) is an acute-phase reactant, but is also produced at sites of inflammation and may contribute to vascular inflammation in atherosclerosis. This study was undertaken to examine the effect of A-SAA on proinflammatory pathways and angiogenesis in GCA, using a novel ex vivo temporal artery tissue explant model., Methods: Serum A-SAA levels were measured by enzyme-linked immunosorbent assay (ELISA). Temporal artery explants and peripheral blood mononuclear cell (PBMC) cultures were established from patients with GCA. Temporal artery explant morphology, viability, and spontaneous release of proinflammatory mediators following 24-hour culture were assessed by hematoxylin and eosin, calcein viability staining, and ELISA. Temporal artery explants and PBMC cultures were stimulated with A-SAA (10 μg/ml), and interleukin-6 (IL-6), IL-8, vascular endothelial growth factor, Ang2, and matrix metalloproteinase 2 (MMP-2)/MMP-9 were quantified by ELISA and gelatin zymography. The effect of conditioned medium from temporal artery explants on angiogenesis was assessed using endothelial cell Matrigel tube-formation assays. Temporal artery explants were also embedded in Matrigel, and myofibroblast outgrowth was assessed., Results: Serum A-SAA levels were significantly higher in GCA patients versus healthy controls (P < 0.0001). Intact tissue morphology, cell viability, and spontaneous cytokine secretion were demonstrated in temporal artery explants. A-SAA treatment induced a significant increase in the levels of IL-6 and IL-8 from temporal artery explants (P < 0.05) and IL-8 from PBMCs (P < 0.05) compared to basal conditions. Conditioned medium from A-SAA-treated explants significantly induced angiogenic tube formation (P < 0.05 versus basal controls). Finally, A-SAA induced myofibroblast outgrowth and MMP-9 activation., Conclusion: Our findings demonstrate a functional role for A-SAA in regulating temporal artery inflammation, angiogenesis, and invasion, all key processes in the pathogenesis of GCA., (© 2015, American College of Rheumatology.)

Objective: GCA is a large- and medium-vessel arteritis characterized by a range of histological patterns of vascular wall injury. The aim of this study was to immunologically characterize the various histological patterns of GCA., Methods: Thirty-five consecutive patients with biopsy-proven GCA and 15 normal controls were studied. IL-8, IL-9, IL-9R, IL-17, IL-4, TGF-β and thymic stromal lymphopoietin expression was evaluated by RT-PCR and immunohistochemistry on artery biopsy specimens. Confocal microscopy was used to characterize the phenotypes of IL-9-producing and IL-9R-expressing cells. Five additional patients who had received prednisone when the temporal artery biopsy was performed were also enrolled to evaluate the effect of glucocorticoids on IL-9 and IL-17 expression., Results: IL-17 overexpression was observed mainly in arteries with transmural inflammation and vasa vasorum vasculitis. IL-9 overexpression and Th9 polarization predominated in arteries with transmural inflammation and small-vessel vasculitis. The tissue expression of both IL-9 and IL-17 was correlated with the intensity of the systemic inflammatory response. IL-4, TGF-β and thymic stromal lymphopoietin, which are involved in the differentiation of Th9 cells, were overexpressed in arteries with transmural inflammation and small-vessel vasculitis. IL-9R was also overexpressed in GCA arteries with transmural inflammation and was accompanied by increased expression of IL-8., Conclusion: Herein we provide the first evidence that distinct populations of potentially autoreactive T cells, expressing different cytokines (Th17 vs Th9), characterize patients with particular histological subsets of GCA and may thus contribute to the heterogeneity of tissue lesions observed in these patients., (© The Author 2015. Published by Oxford University Press on behalf of the British Society for Rheumatology. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)

Objective: Large vessel vasculitides (LVV) are a group of autoimmune diseases characterized by injury to and anatomic modifications of large vessels, including the aorta and its branch vessels. Disease etiology is unknown. This study was undertaken to identify antigen targets within affected vessel walls in aortic root, ascending aorta, and aortic arch surgical specimens from patients with LVV, including giant cell arteritis, Takayasu arteritis, and isolated focal aortitis., Methods: Thoracic aortic aneurysm specimens and autologous blood were acquired from consenting patients who underwent aorta reconstruction procedures. Aorta proteins were extracted from both patients with LVV and age-, race-, and sex-matched disease controls with noninflammatory aneurysms. A total of 108 serum samples from patients with LVV, matched controls, and controls with antinuclear antibodies, different forms of vasculitis, or sepsis were tested., Results: Evaluation of 108 serum samples and 22 aortic tissue specimens showed that 78% of patients with LVV produced antibodies to 14-3-3 proteins in the aortic wall (93.7% specificity), whereas controls were less likely to do so (6.7% produced antibodies). LVV patient sera contained autoantibody sufficient to immunoprecipitate 14-3-3 protein(s) from aortic lysates. Three of 7 isoforms of 14-3-3 were found to be up-regulated in aorta specimens from patients with LVV, and 2 isoforms (ε and ζ) were found to be antigenic in LVV., Conclusion: This is the first study to use sterile, snap-frozen thoracic aorta biopsy specimens to identify autoantigens in LVV. Our findings indicate that 78% of patients with LVV have antibody reactivity to 14-3-3 protein(s). The precise role of these antibodies and 14-3-3 proteins in LVV pathogenesis deserves further study., (© 2015, American College of Rheumatology.)

Objectives: To study the epidemiology and mortality in patients with biopsy-proven giant cell arteritis (GCA) in southern Sweden., Methods: The study area was the County of Skåne. Patients with a positive temporal artery biopsy between 1997 and 2010 were identified using a regional register and a structured review of all histopathology reports. Standardised mortality ratios (SMR) were calculated using data for the Swedish population as the reference., Results: There were 840 patients with biopsy-proven GCA (626 women). The annual incidence rate per 100,000 inhabitants aged ≥50 years was 14.1 (95% CI 13.1 to 15.0); 7.7 (6.7 to 8.7) for men and 19.6 (18.1 to 21.1) for women, without seasonal variations. The incidence increased with age, with estimates of 2.0, 11.8, and 31.3 per 100,000 in the age groups 50-60, 61-70, 71-80 years, respectively (p<0.001). The age-standardised and sex-standardised incidence rate decreased from 15.9/100,000 in 1997-2001 to 13.3/100,000 in 2007-2010 (p=0.026). Two hundred and seventy-nine patients (207 women) died during the observation period. Mortality was significantly increased over the first 2 years after GCA diagnosis (SMR 1.52 (95% CI 1.20 to 1.85)), but not with longer follow-up. The estimated excess mortality was greater in women and in patients aged ≤70 years at diagnosis., Conclusions: In this large population-based study of biopsy-proven GCA from southern Sweden, the incidence of GCA may have decreased over time. Short-term mortality was increased, in particular among those diagnosed at ≤70 years of age, but long-term survival was not impaired., (Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.)

Objective: Aberrant rho kinase (ROCK) activity is implicated in the pathogenesis of several vascular diseases and is associated with Th17 differentiation. Th17 immune response is recognized in the pathogenesis of GCA. The aim of this study was to assess ROCK activity in GCA., Methods: All patients who underwent temporal artery biopsy (TAB) at a tertiary care centre over 5 years were identified and charts reviewed. Subjects were categorized into three groups: TAB-positive GCA, TAB-negative GCA and age- and sex-matched controls. TABs were stained for phosphorylated ezrin/radixin/moesin (pERM), a surrogate of ROCK activity, and reviewed by a pathologist blinded to clinical status. Three areas were scored for staining intensity on a scale of 0-2, with a maximum possible score of 6., Results: Nineteen subjects with TAB-positive GCA, 17 with TAB-negative GCA and 18 controls were analysed. Compared with controls, GCA subjects with either positive or negative TABs had significantly higher pERM intensity scores (P = 0.0109). Adjusting for diabetes, hypertension, prednisone and statin use, GCA subjects still had higher pERM scores [odds ratio 7.3 (95% CI 1.9, 25.9), P = 0.0046]. The high pERM score had a sensitivity of 90% and a negative predictive value of 91% for the diagnosis of GCA in those with a negative TAB, compared with 51% sensitivity for histopathology alone., Conclusion: Subjects with GCA had more intense pERM staining in TAB specimens compared with age- and sex-matched controls, regardless of whether TAB was positive or negative by routine histopathology, suggesting increased ROCK activity in GCA. The ROCK pathway warrants further investigation in GCA, as it may have diagnostic significance in enhancing the sensitivity of TAB., (© The Author 2014. Published by Oxford University Press on behalf of the British Society for Rheumatology. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)

Giant cell arteritis (GCA) and Takayasu's disease are inflammatory vasculitic syndromes (IVS) causing sudden blindness and widespread arterial obstruction and aneurysm formation. Glucocorticoids and aspirin are mainstays of treatment, predominantly targeting T cells. Serp-1, a Myxomavirus-derived serpin, blocks macrophage and T cells in a wide range of animal models. Serp-1 also reduced markers of myocardial injury in a Phase IIa clinical trial for unstable coronary disease. In recent work, we detected improved survival and decreased arterial inflammation in a mouse Herpesvirus model of IVS. Here we examine Serp-1 treatment of human temporal artery (TA) biopsies from patients with suspected TA GCA arteritis after implant (TAI) into the aorta of immunodeficient SCID (severe combined immunodeficiency) mice. TAI positive for arteritis (GCApos) had significantly increased inflammation and plaque when compared to negative TAI (GCAneg). Serp-1 significantly reduced intimal inflammation and CD11b+ cell infiltrates in TAI, with reduced splenocyte Th1, Th17, and Treg. Splenocytes from mice with GCApos grafts had increased gene expression for interleukin-1 beta (IL-1β), IL-17, and CD25 and decreased Factor II. Serp-1 decreased IL-1β expression. In conclusion, GCApos TAI xenografts in mice provide a viable disease model and have increased intimal inflammation as expected and Serp-1 significantly reduces vascular inflammatory lesions with reduced IL-1β.

Introduction: Giant cell arteritis (GCA) is characterized by intimal hyperplasia leading to ischaemic manifestations that involve large vessels. Neurotrophins (NTs) and their receptors (NTRs) are protein factors for growth, differentiation and survival of neurons. They are also involved in the migration of vascular smooth muscle cells (VSMCs). Our aim was to investigate whether NTs and NTRs are involved in vascular remodelling of GCA., Methods: We included consecutive patients who underwent a temporal artery biopsy for suspected GCA. We developed an enzymatic digestion method to obtain VSMCs from smooth muscle cells in GCA patients and controls. Neurotrophin protein and gene expression and functional assays were studied from these VSMCs. Neurotrophin expression was also analysed by immunohistochemistry in GCA patients and controls., Results: Whereas temporal arteries of both GCA patients (n = 22) and controls (n = 21) expressed nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF), tropomyosin receptor kinase B (TrkB) and sortilin, immunostaining was more intense in GCA patients, especially in the media and intima, while neurotrophin-3 (NT-3) and P75 receptor (P75NTR) were only detected in TA from GCA patients. Expression of TrkB, a BDNF receptor, was higher in GCA patients with ischaemic complications. Serum NGF was significantly higher in GCA patients (n = 28) vs. controls (n = 48), whereas no significant difference was found for BDNF and NT-3. NGF and BDNF enhanced GCA-derived temporal artery VSMC proliferation and BDNF facilitated migration of temporal artery VSMCs in patients with GCA compared to controls., Conclusions: Our results suggest that NTs and NTRs are involved in vascular remodelling of GCA. In GCA-derived temporal artery VSMC, NGF promoted proliferation and BDNF enhanced migration by binding to TrkB and p75NTR receptors. Further experiments are needed on a larger number of VSMC samples to confirm these results.