Serum proteomics in giant cell arteritis in response to a three-day pulse of glucocorticoid followed by tocilizumab monotherapy (the GUSTO trial).

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.

CD47 blockade ameliorates autoimmune vasculitis via efferocytosis of neutrophil extracellular traps.

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.

Deficiency of the CD155-CD96 immune checkpoint controls IL-9 production in giant cell arteritis.

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. CD155low 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.

Human monocyte-derived suppressive cells (HuMoSC) for cell therapy in giant cell arteritis.

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.

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

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

Giant cell arteritis: what is new in the preclinical and early clinical development pipeline?

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.

Dysregulated Expression of Arterial MicroRNAs and Their Target Gene Networks in Temporal Arteries of Treatment-Naïve Patients with Giant Cell Arteritis.

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.

A Distinct Macrophage Subset Mediating Tissue Destruction and Neovascularization in Giant Cell Arteritis: Implication of the YKL-40/Interleukin-13 Receptor α2 Axis.

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.

CD8+ T Cells in GCA and GPA: Bystanders or Active Contributors?

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.

The Immunopathology of Giant Cell Arteritis Across Disease Spectra.

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.

Specific microbiome profile in Takayasu's arteritis and giant cell arteritis.

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.

The Role of Multimodality Imaging in Monitoring Disease Activity and Therapeutic Response to Tocilizumab in Giant Cell Arteritis.

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.

Temporal artery involvement in AL amyloidosis: an important differential diagnosis for giant cell arteritis. A case report and literature review.

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.

ROS-producing immature neutrophils in giant cell arteritis are linked to vascular pathologies.

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.

Monitoring and long-term management of giant cell arteritis and polymyalgia rheumatica.

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.

Systematic literature review informing the 2018 update of the EULAR recommendation for the management of large vessel vasculitis: focus on giant cell arteritis.

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.

Leukocyte Dynamics Reveal a Persistent Myeloid Dominance in Giant Cell Arteritis and Polymyalgia Rheumatica.

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.

Cytokine expression in temporal arteries: comparative analysis between patients with biopsy-positive giant cell arteritis, biopsy-negative giant cell arteritis and biopsy-negative without arteritis.

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.

Treatment of giant cell arteritis.

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.

Cytokines, growth factors and proteases in medium and large vessel vasculitis.

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.