Neointimal myofibroblasts contribute to maintaining Th1/Tc1 and Th17/Tc17 inflammation in giant cell arteritis.

Vascular smooth muscle cells (VSMCs) have been shown to play a role in the pathogenesis of giant cell arteritis (GCA) through their capacity to produce chemokines recruiting T cells and monocytes in the arterial wall and their ability to migrate and proliferate in the neointima where they acquire a myofibroblast (MF) phenotype, leading to vascular stenosis. This study aimed to investigate if MFs could also impact T-cell polarization. Confocal microscopy was used to analyze fresh fragments of temporal artery biopsies (TABs). Healthy TAB sections were cultured to obtain MFs, which were then treated or not with interferon-gamma (IFN-γ) and tumor necrosis factor-alpha (TNF-α) and analyzed by immunofluorescence and RT-PCR. After peripheral blood mononuclear cells and MFs were co-cultured for seven days, T-cell polarization was analyzed by flow cytometry. In the neointima of GCA arteries, we observed a phenotypic heterogeneity among VSMCs that was consistent with a MF phenotype (α-SMA+CD90+desmin+MYH11+) with a high level of STAT1 phosphorylation. Co-culture experiments showed that MFs sustain Th1/Tc1 and Th17/Tc17 polarizations. The increased Th1 and Tc1 polarization was further enhanced following the stimulation of MFs with IFN-γ and TNF-α, which induced STAT1 phosphorylation in MFs. These findings correlated with increases in the production of IL-1ß, IL-6, IL-12 and IL-23 by MFs. Our study showed that MFs play an additional role in the pathogenesis of GCA through their ability to maintain Th17/Tc17 and Th1/Tc1 polarizations, the latter being further enhanced in case of stimulation of MF with IFN-γ and TNF-α.

Regulatory T-cell dysfunctions are associated with increase in tumor necrosis factor α in autoimmune hemolytic anemia and participate in Th17 polarization.

Warm autoimmune hemolytic anemia (wAIHA) is a rare acquired autoimmune disease mediated by antibodies targeting red blood cells. The involvement of CD4 T-helper cells has been scarcely explored, with most findings extrapolated from animal models. Here, we performed quantification of both effector T lymphocytes (Teff) and regulatory T cells (Treg), associated with functional and transcriptomic analyses of Treg in human wAIHA. We observed a shift of Teff toward a Th17 polarization concordant with an increase in serum interleukin-17 concentration that correlates with red blood cell destruction parameters, namely lactate dehydrogenase and bilirubin levels. A decrease in circulating Treg, notably effector Treg, associated with a functional deficiency, as represented by their decrease capability to inhibit Teff proliferation, were also observed. Treg deficiency was associated with a reduced expression of Foxp3, the master transcription factor known to maintain the Treg phenotype stability and suppressive functions. Transcriptomic profiling of Treg revealed activation of the tumor necrosis facto (TNF)-α pathway, which was linked to increased serum TNF-α concentrations that were twice as high as in controls. Treg transcriptomic profiling also suggested that post-translational mechanisms possibly accounted for Foxp3 downregulation and Treg dysfunctions. Since TNF-α participates in the rupture of immune tolerance during wAIHA, its inhibition could be of interest. To this end, the effects of fostamatinib, a SYK inhibitor, were investigated in vitro, and we showed that besides the inhibition of erythrocyte phagocytosis by monocytes, fostamatinib is also able to dampen TNF-α production, thus appearing as a promising multitargeting therapy in wAIHA (clinicaltrials gov. Identifier: NCT02158195).

PET/CT of cranial arteries for a sensitive diagnosis of giant cell arteritis.

OBJECTIVES: To investigate the performance of cranial PET/CT for the diagnosis of GCA. METHODS: All patients with a suspected diagnosis of GCA were prospectively enrolled in this study and had a digital PET/CT with evaluation of cranial arteries if they had not started glucocorticoids >72 h previously. The diagnosis of GCA was retained after at least 6 months of follow-up if no other diagnosis was considered by the clinician and the patient went into remission after at least 6 consecutive months of treatment. Cranial PET/CT was considered positive if at least one arterial segment showed hypermetabolism similar to or greater than liver uptake. RESULTS: For cranial PET/CT, sensitivity (Se), specificity (Sp), positive predictive value (PPV) and negative predictive value (NPV) were 73.3%, 97.2%, 91.7% and 89.7%, respectively. For extracranial PET/CT, diagnostic performance was lower (Se = 66.7%, Sp = 80.6%, PPV = 58.8%, NPV = 85.3%). The combination of cranial and extracranial PET/CT improved overall sensitivity (Se = 80%) and NPV (NPV = 90.3%) while decreasing overall specificity (Sp = 77.8%) and PPV (PPV = 60%). CONCLUSION: Cranial PET/CT can be easily combined with extracranial PET/CT with a limited increase in examination time. Combined cranial and extracranial PET/CT showed very high diagnostic accuracy for the diagnosis of GCA. TRIAL REGISTRATION: ClinicalTrials.gov, https://clinicaltrials.gov, NCT05246540.

Mucosal-associated invariant T cells in Giant Cell Arteritis.

This study aimed to assess the implication of mucosal-associated invariant T (MAIT) cells in GCA. Blood samples were obtained from 34 GCA patients (before and after 3 months of treatment with glucocorticoids (GC) alone) and compared with 20 controls aged >50 years. MAIT cells, defined by a CD3+CD4-TCRγδ-TCRVα7.2+CD161+ phenotype, were analyzed by flow cytometry. After sorting, we assessed the ability of MAIT cells to proliferate and produce cytokines after stimulation with anti CD3/CD28 microbeads or IL-12 and IL-18. MAIT were stained in temporal artery biopsies (TAB) by confocal microscopy. MAIT cells were found in the arterial wall of positive TABs but was absent in negative TAB. MAIT frequency among total αß-T cells was similar in the blood of patients and controls (0.52 vs. 0.57%; P = 0.43) and not modified after GC treatment (P = 0.82). Expression of IFN-γ was increased in MAIT cells from GCA patients compared to controls (44.49 vs. 32.9%; P = 0.029), and not modified after 3 months of GC therapy (P = 0.82). When they were stimulated with IL-12 and IL-18, MAIT from GCA patients produced very high levels of IFN-γ and displayed a stronger proliferation compared with MAIT from controls (proliferation index 3.39 vs. 1.4; P = 0.032). In GCA, the functional characteristics of MAIT cells are modified toward a pro-inflammatory phenotype and a stronger proliferation capability in response to IL-12 and IL-18, suggesting that MAIT might play a role in GCA pathogenesis. Our results support the use of treatments targeting IL-12/IL-18 to inhibit the IFN-γ pathway in GCA.

Heamatological malignancies in giant cell arteritis: a French population-based study.

OBJECTIVES: An increased risk of haematological malignancies (HM) has been reported in GCA patients. Our study aimed to investigate the incidence and the type of HM occurring in GCA. METHODS: All patients with GCA and HM living in Côte d'Or (France) were identified by crossing data from the RHEMCO (Registre des Hémopathies Malignes de Côte d'Or) and those having a positive temporal artery biopsy between 1 January 2001 and 31 December 2018. RESULTS: Among 276 biopsy-proven GCA patients, 14 HM were identified in 12 patients (4.3%). In comparison with the general population aged >50 y, the incidence of myeloid HM and myeloproliferative syndromes were increased in GCA patients [standardized incidence ratios (SIR) = 2.71 and 5.16, respectively], with a specific increase in men with GCA (SIR = 4.82 and 9.04, respectively) but not in women. In addition, the study of SIR depending on the chronology between GCA and HM diagnoses suggests that there was an increased risk of developing GCA in men but not in women, after a diagnosis of myeloid HM (SIR = 9.56), especially if it was a MPS (SIR = 17.56). CONCLUSIONS: Our study shows a particular epidemiology of HM in GCA patients, which is characterized by an increased incidence of myeloid HM, especially MPS, in male GCA patients. The chronology of the diagnoses of GCA and HM raises the hypothesis that clonal hematopoiesis may be implicated in some cases of GCA.

An overview of 18F-fluorodeoxyglucose positron emission tomography/computed tomography in giant cell arteritis.

PET/CT is an imaging modality that is increasingly being used to diagnose large-vessel vasculitis. In the case of giant cell arteritis, it was first used to demonstrate inflammation of the walls of large arterial trunks such as the aorta and its main branches, showing that aortic involvement is common in this vasculitis and associated with the occurrence of aortic complications such as aneurysms. More recently, with the advent of digital PET/CT, study of the cranial arteries (i.e., temporal, occipital, maxillary and vertebral arteries) has become possible, further increasing the diagnostic interest of this examination for the diagnosis of GCA. Despite these advantages, there are still limitations and questions regarding the use of PET/CT for the diagnosis and especially the follow-up of GCA. The aim of this review is to take stock of currently available data on the use of PET/CT for GCA diagnosis and follow-up.

Diagnostic accuracy of serum biomarkers to identify giant cell arteritis in patients with polymyalgia rheumatica.

INTRODUCTION: Polymyalgia rheumatica (PMR) and giant cell arteritis (GCA) are frequently overlapping conditions. Unlike in GCA, vascular inflammation is absent in PMR. Therefore, serum biomarkers reflecting vascular remodelling could be used to identify GCA in cases of apparently isolated PMR. MATERIALS AND METHODS: 45 patients with isolated PMR and 29 patients with PMR/GCA overlap were included. Blood samples were collected before starting glucocorticoids for all patients. Serum biomarkers reflecting systemic inflammation (interleukin-6 (IL-6), CXCL9), vascular remodelling (MMP-2, MMP-3, MMP-9) and endothelial function (sCD141, sCD146, ICAM-1, VCAM-1, vWFA2) were measured by Luminex assays. RESULTS: Patients with GCA had higher serum levels of sCD141 (p=0.002) and CXCL9 (p=0.002) than isolated PMR. By contrast, serum levels of MMP-3 (p=0.01) and IL-6 (p=0.004) were lower in GCA than isolated PMR. The area under the curve (AUC) was calculated for sCD141, CXCL9, IL-6 and MMP-3. Separately, none of them were >0.7, but combinations revealed higher diagnostic accuracy. The CXCL9/IL-6 ratio was significantly increased in patients with GCA (p=0.0001; cut-off >32.8, AUC 0.76), while the MMP-3/sCD141 ratio was significantly lower in patients with GCA (p<0.0001; cut-off <5.3, AUC 0.79). In patients with subclinical GCA, which is the most difficult to diagnose, sCD141 and MMP-3/sCD141 ratio demonstrated high diagnostic accuracy with AUC of 0.81 and 0.77, respectively. CONCLUSION: Combined serum biomarkers such as CXCL9/IL-6 and MMP-3/sCD141 could help identify GCA in patients with isolated PMR. It could allow to select patients with PMR in whom complementary examinations are needed.

Recommendations of the French Society of Rheumatology for the management in current practice of patients with polymyalgia rheumatica.

OBJECTIVE: To develop recommendations for the routine management of patients with polymyalgia rheumatica (PMR). METHODS: Following standard procedures, a systematic review of the literature by five supervised junior rheumatologists, based on the questions selected by the steering committee (5 senior rheumatologists), was used as the basis for working meetings, followed by a one-day plenary meeting with the working group (15 members), leading to the development of the wording and determination of the strength of the recommendations and the level of agreement of the experts. RESULTS: Five general principles and 19 recommendations were drawn up. Three recommendations relate to diagnosis and the use of imaging, and five to the assessment of the disease, its activity and comorbidities. Non-pharmacological therapies are the subject of one recommendation. Three recommendations concern initial treatment based on general corticosteroid therapy, five concern the reduction of corticosteroid therapy and follow-up, and two concern corticosteroid dependence and steroid-sparing treatments (anti-IL-6). CONCLUSION: These recommendations take account of current data on PMR, with the aim of reducing exposure to corticosteroid therapy and its side effects in a fragile population. They are intended to be practical, to help practitioners in the day-to-day management of patients with PMR.

Diagnosis and treatment of Tropheryma whipplei infection in patients with inflammatory rheumatic disease: Data from the French Tw-IRD registry.

OBJECTIVES: Tropheryma whipplei infection can manifest as inflammatory joint symptoms, which can lead to misdiagnosis of inflammatory rheumatic disease and the use of disease-modifying antirheumatic drugs. We investigated the impact of diagnosis and treatment of Tropheryma whipplei infection in patients with inflammatory rheumatic disease. METHODS: We initiated a registry including patients with disease-modifying antirheumatic drugs-treated inflammatory rheumatic disease who were subsequently diagnosed with Tropheryma whipplei infection. We collected clinical, biological, treatment data of the inflammatory rheumatic disease, of Tropheryma whipplei infection, and impact of antibiotics on the evolution of inflammatory rheumatic disease. RESULTS: Among 73 inflammatory rheumatic disease patients, disease-modifying antirheumatic drugs initiation triggered extra-articular manifestations in 27% and resulted in stabilisation (51%), worsening (34%), or improvement (15%) of inflammatory rheumatic disease. At the diagnosis of Tropheryma whipplei infection, all patients had rheumatological symptoms (mean age 58 years, median inflammatory rheumatic disease duration 79 months), 84% had extra-rheumatological manifestations, 93% had elevated C-reactive protein, and 86% had hypoalbuminemia. Treatment of Tropheryma whipplei infection consisted mainly of doxycycline plus hydroxychloroquine, leading to remission of Tropheryma whipplei infection in 79% of cases. Antibiotic treatment of Tropheryma whipplei infection was associated with remission of inflammatory rheumatic disease in 93% of cases and enabled disease-modifying antirheumatic drugs and glucocorticoid discontinuation in most cases. CONCLUSIONS: Tropheryma whipplei infection should be considered in inflammatory rheumatic disease patients with extra-articular manifestations, elevated C-reactive protein, and/or hypoalbuminemia before disease-modifying antirheumatic drugs initiation or in inflammatory rheumatic disease patients with an inadequate response to one or more disease-modifying antirheumatic drugs. Positive results of screening and diagnostic tests for Tropheryma whipplei infection involve antibiotic treatment, which is associated with complete recovery of Tropheryma whipplei infection and rapid remission of inflammatory rheumatic disease, allowing disease-modifying antirheumatic drugs and glucocorticoid discontinuation.

Comparison of sacroiliac CT findings in patients with and without ankylosing spondylitis aged over 50 years.

Diagnosis of axial spondyloarthritis (axSpA) is nowadays commonly made with the help of pelvic radiography or magnetic resonance imaging (MRI). However, there is an important inter-observer variability in radiography, and MRI is subject to possible false positives and is not the best modality for studying structural lesions. Conversely, pelvic computed tomography (CT) has excellent specificity and appears to be more effective than radiography for the diagnosis of ankylosing spondylitis (AS). However, its findings in patients over 50 years of age have not yet been studied. The objectives of this study were to describe the CT characteristics of sacro-iliac joints (SIJ) and the presence of intra-articular gas in patients with AS aged over 50 years and to compare them with controls of the same age and sex. This two-center, cross-sectional, observational study was performed using the medical records of the rheumatology departments of two University Hospitals. We included patients with a clinical diagnosis of axSpA, who had both definite radiographic sacroiliitis according to the modified New York criteria and met the ASAS 2009 criteria for axSpA (that is, AS), and who had undergone any CT scan including the whole SIJ. Each patient was matched for age and sex to a control randomly selected on the Picture Archiving and Communication System (PACS), symptomatic or asymptomatic, and without spondyloarthritis. For each individual, CT scans were interpreted blindly by two independent rheumatologists and scored for joint space narrowing (JSN), erosions, sclerosis, intra-articular gas, and diffuse idiopathic skeletal hyperostosis (DISH). Ninety patients and 90 controls were included in the study. The rates of positive JSN, erosion, and sclerosis scores were higher in the AS group (91% vs. 21%, p < 0.0001; 31% vs. 2%, p < 0.0001; 27% vs. 13%, p = 0.03, respectively), but the rates of intra-articular gas and DISH were higher in the control group (24% vs. 68%, p < 0.0001; 7% vs. 33%, p < 0.0001, respectively). 58% of patients had complete bilateral ankylosis. A total of 83 (92.2%) patients had a CT scan considered positive for AS, compared with only seven controls (7.8%). Sclerosis and erosions were predominantly on the anterosuperior part and iliac side of the joint in controls and were more diffuse in patients with AS. CT findings in patients with AS over 50 years of age are mostly represented by changes in the joint space; patients with AS have more erosions and sclerosis changes, but less intra-articular gas than controls.

Diagnostic Value of an Additional Sequence (Large-Field Coronal Stir) in a Routine Lumbar Spine MR Imaging Protocol to Investigate Lumbar Radiculopathy.

OBJECTIVE: Lumbar radiculopathy mainly originates in the spine (lumbar disc herniation or spine osteoarthritis) but can sometimes be explained by extra-spinal nerve compression or confused with referred pain mimicking radiculopathy. Our main objective was to demonstrate the clinical benefit of the large-field coronal STIR (coroSTIR) sequence in the etiological assessment of lumbar radiculopathy with a duration of more than six weeks. MATERIALS AND METHODS: Six hundred consecutive lumbar MRI scans performed using the same protocol were retrospectively reviewed. Two musculoskeletal radiologists independently assessed the coroSTIR sequence for the presence of extra-spinal anomalies (ESA) that could explain or contribute to the lumbar radiculopathy. The presence of an ESA was then correlated with sex, age, topography and lateralization of radiculopathy, history of vertebral surgery, as well as the presence of a spinal cause explaining the symptoms. Extra-spinal incidentalomas (ESI) with potential clinical impact visible only on the coroSTIR sequence were also systematically reported. RESULTS: An extra-spinal cause was detected on the coroSTIR sequence in 68 cases (11.3%), mainly gluteal tendinobursitis (30.9%), congestive hip osteoarthritis (25%), degenerative sacroiliac arthropathy (14.7%), or inflammatory sacroilitis (7.3%). Their prevalence was significantly correlated in multivariate regression with age (58 years vs. 53 years, p = 0.01), but not with the type of radiating pain (sciatica or cruralgia). The presence of ESI was also frequent (70 cases, 11.7%), including some potentially severe diagnoses (38% of tumor or pseudo-tumor mass requiring further assessment or monitoring). CONCLUSIONS: Considering its acceptable acquisition time, the detection of a significant number of potentially symptom-related extra-spinal anomalies, and the discovery of a non-negligible number of extra-spinal incidentalomas with potential clinical impact, the coronal STIR should be performed systematically in routine MRI for lumbar radiculopathy.

New Insights into the Pathogenesis of Giant Cell Arteritis: Mechanisms Involved in Maintaining Vascular Inflammation.

The giant cell arteritis (GCA) pathophysiology is complex and multifactorial, involving a predisposing genetic background, the role of immune aging and the activation of vascular dendritic cells by an unknown trigger. Once activated, dendritic cells recruit CD4 T cells and induce their activation, proliferation and polarization into Th1 and Th17, which produce interferon-gamma (IFN-γ) and interleukin-17 (IL-17), respectively. IFN-γ triggers the production of chemokines by vascular smooth muscle cells, which leads to the recruitment of additional CD4 and CD8 T cells and also monocytes that differentiate into macrophages. Recent data have shown that IL-17, IFN-γ and GM-CSF induce the differentiation of macrophage subpopulations, which play a role in the destruction of the arterial wall, in neoangiogenesis or intimal hyperplasia. Under the influence of different mediators, mainly endothelin-1 and PDGF, vascular smooth muscle cells migrate to the intima, proliferate and change their phenotype to become myofibroblasts that further proliferate and produce extracellular matrix proteins, increasing the vascular stenosis. In addition, several defects in the immune regulatory mechanisms probably contribute to chronic vascular inflammation in GCA: a defect in the PD-1/PD-L1 pathway, a quantitative and qualitative Treg deficiency, the implication of resident cells, the role of GM-CSF and IL-6, the implication of the NOTCH pathway and the role of mucosal-associated invariant T cells and tissue-resident memory T cells.