Prognostic value of 18 FDG-PET at diagnosis and follow-up in giant cell arteritis: An observational restrospective study.

OBJECTIVES: To evaluate the ability of 18FDG PET/CT, at diagnosis of giant cell arteritis (GCA) and during follow-up, to predict occurrence of relapse in large-vessel GCA (LV-GCA). METHODS: We conducted a retrospective study using the French Study Group for Large-Vessel Vasculitis (GEFA) network. Data from patients with LV-GCA diagnosed by PET/CT and who had PET/CT in the following year were collected. For each PET/CT, PET vascular activity score (PETVAS) and total vascular score (TVS) were assessed, and their ability to predict the occurrence of subsequent relapse was assessed. RESULTS: A total of 65 LV-GCA patients were included, of whom 55 had undergone a follow-up PET/CT 3 to 12 months after the diagnosis of GCA. Patients for whom the second PET/CT (PET2) was performed during active GCA were excluded. PETVAS and TVS decreased between PET1 and PET2 in all patients (p < 0.001). There was no correlation between vascular activity scores in PET2 and time to prednisone taper. For relapse prediction, at PET1, the AUC of the TVS and PETVAS were respectively 51.9 and 41.9 at 6 months, 55.3 and 49.7 at 1 year, 55 and 55.7 at 2 years. For PET2, the AUC were respectively 46.1 and 46.7 at 6 months, 52.1 and 48.9 at 1 year, 58.4 and 52.3 at 2 years. CONCLUSION: PET vascular activity scores at diagnosis and at follow-up PET/CT performed outside a period of GCA activity do not display high performance to predict the occurrence of subsequent relapse in LV-GCA patients.

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).

Pro-angiogenic changes of T-helper lymphocytes in hereditary hemorrhagic telangiectasia.

Hereditary hemorrhagic telangiectasia (HHT) is a rare inherited disease due to heterozygous loss-of-function mutations on the BMP9/10 pathway (ENG, ACVRL1 or MADH4 mainly). HHT endothelial cells are prone to lose their quiescence, leading to progressive appearance of numerous telangiectases on skin and mucosa (complicated by epistaxis and anemia), and to larger arteriovenous malformations in lungs, liver and brain. HHT is also associated with T lymphocyte abnormalities, which are currently poorly understood. We quantified by flow-cytometry the main T lymphocyte circulating subsets in 40 HHT patients and 20 matched healthy controls. Immunostaining was done on 2 HHT skin telangiectases. Disruptions in T lymphocyte homeostasis was observed, characterized by increases in subsets known to promote angiogenesis: Th2 (1.38% vs 1.15%, p=0.021), Th17 (0.32% vs 0.22%, p=0.019 2) and Treg (4.94% vs 3.51%, p= 0.027). T angiogenic lymphocytes (Tang), defined as CD3+CD31+CXCR4+ T cells, were at similar levels in both groups, but the proportion of VEGF-A+ Tang after stimulation was higher in the HHT group compared to controls (68.2% vs 44.9%, p=0.012). The global HHT T lymphopenia predominantly affected the effector memory T-helper cells (200 vs 270 cells/mm3, p=0.017), and the lymphocytic infiltrate around HHT telangiectases consisted of memory T-helper cells. The Th17 circulating subset was positively correlated with the monthly epistaxis duration (r coefficient: +0,431, p=0.042), prospectively assessed. HHT T-helper lymphocytes are affected by several pro-angiogenic changes, potentially resulting from their recruitment by abnormal endothelial cells. They could constitute a biologically relevant source of VEGF-A and a valuable therapeutic target in HHT.

Correction: Full-field optical coherence tomography for the diagnosis of giant cell arteritis.

[This corrects the article DOI: 10.1371/journal.pone.0234165.].

Increased neopterin in cerebrospinal fluid in active adult neurohistiocytosis.

Diagnosis of neuro-histiocytosis is challenging and relies on clinical presentation, imaging, and cerebrospinal fluid (CSF) analysis to exclude differential diagnoses. Brain biopsy remains the gold standard for accurate diagnosis, but it is rarely performed because of the risk of the procedure and the low rentability in neurodegenerative presentation. Therefore, there is an unmet need to identify a specific biomarker for diagnosing neurohistiocytosis in adults. Because microglia (brain macrophages) is involved in the pathogenesis of neurohistiocytosis and produces neopterin secondary to aggression, the purpose of our study was to evaluate the value of the CSF neopterin levels for the diagnosis of active neurohistiocytosis. Of the 21 adult patients with histiocytosis, four patients had clinical symptoms compatible with neurohistiocytosis. In the two patients with a confirmed diagnosis of neurohistiocytosis, CSF neopterin levels were elevated as well as IL-6 and IL-10 levels. In contrast, the two other patients in whom the diagnosis of neurohistiocytosis was infirmed and all other patients with histiocytosis without active neurological disease involvement had normal CSF neopterin levels. In summary, increased CSF neopterin concentration represented a valuable tool for diagnosing active neuro-histiocytosis in adults with histiocytic neoplasms in this preliminary study.

Effect of weight-adjusted intermediate-dose versus fixed-dose prophylactic anticoagulation with low-molecular-weight heparin on venous thromboembolism among noncritically and critically ill patients with COVID-19: the COVI-DOSE trial, a multicenter, randomised, open-label, phase 4 trial.

Background: Venous thromboembolism is a major complication of coronavirus disease 2019 (COVID-19). We hypothesized that a weight-adjusted intermediate dose of anticoagulation may decrease the risk of venous thromboembolism COVID-19 patients. Methods: In this multicenter, randomised, open-label, phase 4, superiority trial with blinded adjudication of outcomes, we randomly assigned adult patients hospitalised in 20 French centers and presenting with acute respiratory SARS-CoV-2. Eligible patients were randomly assigned (1:1 ratio) to receive an intermediate weight-adjusted prophylactic dose or a fixed-dose of subcutaneous low-molecular-weight heparin during the hospital stay. The primary outcome corresponded to symptomatic deep-vein thrombosis (fatal) pulmonary embolism during hospitalization (COVI-DOSE ClinicalTrials.gov number: NCT04373707). Findings: Between May 2020, and April 2021, 1000 patients underwent randomisation in medical wards (noncritically ill) (80.1%) and intensive care units (critically ill) (19.9%); 502 patients were assigned to receive a weight-adjusted intermediate dose, and 498 received fixed-dose thromboprophylaxis. Symptomatic venous thromboembolism occurred in 6 of 502 patients (1.2%) in the weight-adjusted dose group and in 10 of 498 patients (2.1%) in the fixed-dose group (subdistribution hazard ratio, 0.59; 95% CI, 0.22-1.63; P = 0.31). There was a twofold increased risk of major or clinically relevant nonmajor bleeding: 5.9% in the weight-adjusted dose group and 3.1% in the fixed-dose group (P = 0.034). Interpretation: In the COVI-DOSE trial, the observed rate of thromboembolic events was lower than expected in patients hospitalized for COVID-19 infection, and the study was unable to show a significant difference in the risk of venous thromboembolism between the two low-molecular-weight-heparin regimens. Funding: French Ministry of Health, CAPNET, Grand-Est Region, Grand-Nancy Métropole.

[Epidemiology and pathophysiology of giant cell arteritis]. / Épidémiologie et physiopathologie de l'artérite à cellules géantes.

EPIDEMIOLOGY AND PATHOPHYSIOLOGY OF GIANT CELL ARTERITIS. Giant cell arteritis (GCA) is a granulomatous vasculitis. It affects patients over 50 years of age, predominantly women. The pathophysiology of GCA involves genetic and environmental factors leading to the development of inflammation and subsequent large artery wall remodelling, the mechanisms of which are increasingly understood. The process is thought to begin with the activation of dendritic cells in the vessel wall. These then recruit and activate CD4 T cells, inducing their proliferation and polarisation into Th1 and Th17 cells, which produce interferon-gamma (IFN-γ) and interleukin-17 (IL-17) respectively. IFN-γ activates vascular smooth muscle cells, which produce chemokines that induce the recruitment of other mononuclear cells (CD4 and CD8 T cells and monocytes). This inflammatory infiltrate, the differentiation of monocytes into macrophages induce the production of other mediators that cause remodeling of the vascular wall based on destruction of the arterial wall, neoangiogenesis and intimal hyperplasia. This remodelling leads to the ischaemic manifestations of GCA by causing stenosis or even occlusion of the affected vessels. More recently, mechanisms have been identified that allow the perpetuation of inflammation and vascular remodelling, explaining the chronic evolution of GCA.

ÉPIDÉMIOLOGIE ET PHYSIOPATHOLOGIE DE L'ARTÉRITE À CELLULES GÉANTES. L'artérite à cellules géantes (ACG) est une vascularite granulomateuse affectant les patients de plus de 50 ans, préférentiellement les femmes. La physiopathologie de l'ACG fait intervenir des facteurs génétiques et environnementaux qui conduisent à l'apparition d'une inflammation, puis d'un remodelage de la paroi des artères de gros calibre dont les mécanismes sont de mieux en mieux compris. On pense que le processus débute par l'activation des cellules dendritiques de la paroi vasculaire qui recrutent ensuite les lymphocytes T CD4, les activent et induisent leur prolifération et leur polarisation en lymphocytes Th1 et Th17, qui produisent respectivement de l'interféron gamma (IFN-γ) et de l'interleukine 17 (IL-17). L'IFN-γ active les cellules musculaires lisses vasculaires qui produisent des chimiokines induisant le recrutement d'autres cellules mononucléées (lymphocytes T CD4 et CD8 ; monocytes). Cet infiltrat inflammatoire, la différenciation des monocytes en macrophages induisent la production d'autres médiateurs qui provoquent un remodelage de la paroi vasculaire reposant sur une destruction de la paroi artérielle, une néoangiogenèse et une hyperplasie intimale. Ce remodelage conduit à la sténose, voire à l'occlusion, des vaisseaux atteints et ainsi aux manifestations ischémiques de l'ACG. Plus récemment, des mécanismes permettant d'entretenir l'inflammation et le remodelage vasculaire ont été mis en évidence et permettent d'expliquer l'évolution chronique de l'ACG.

[Diagnosis of giant cell arteritis]. / Diagnostic de l'artérite à cellules géantes.

DIAGNOSIS OF GIANT CELL ARTERITIS. The diagnosis of giant cell arteritis (GCA) must be made promptly in order to initiate appropriate treatment aimed at relieving symptoms and avoiding ischemic complications, particularly visual ones. The diagnosis of GCA is based on the occurrence, in a patient over 50, of clinical signs of GCA, primarily recent headaches, or polymyalgia rheumatica, as «evidence¼ of large-vessel vasculitis, which is provided by histological analysis of an arterial fragment, usually the temporal artery, or by imaging of the cephalic arteries, the aorta and/ or its main branches by Doppler US scan, angio-CT, 18fluorodeoxyglucose PET scan or more rarely by MRI angiography. In addition, in more than 95% of cases, patients have an elevation in markers of inflammatory syndrome. This is less marked in the case of visual or neurological ischemic complications. Two main GCA phenotypes can be distinguished: on the one hand, cephalic GCA, in which cephalic vessel involvement predominates and which identifies patients at the greatest risk of ischemic complications; on the other hand, extracephalic GCA concerns younger patients with a lower ischemic risk but with more aortic complications and more frequent relapses. The establishment «fast track¼ type structures in specialized centers allows for rapid management in order to identify patients to be treated in order to avoid ischemic complications and to quickly perform the necessary examinations to confirm the diagnosis and ensure that the patient receives appropriate management.

DIAGNOSTIC DE L'ARTÉRITE À CELLULES GÉANTES. Le diagnostic d'artérite à cellules géantes (ACG) doit être porté rapidement pour initier un traitement adapté visant à soulager les symptômes et éviter les complications ischémiques, en particulier visuelles, de la maladie. Le diagnostic repose sur la survenue, chez un patient de plus de 50 ans, de signes cliniques d'ACG, au premier rang desquels les céphalées récentes, ou de pseudopolyarthrite rhizomélique et d'une « preuve ¼ de vascularite des artères de gros calibre qui est apportée par l'analyse histologique d'un fragment artériel, généralement l'artère temporale, ou par l'imagerie des artères céphaliques, de l'aorte et/ou de ses principales branches par l'échographie-Doppler, l'angioscanner, le TEP-scan au 18fluorodéoxyglucose et plus rarement l'angio-IRM. De plus, les patients présentent, dans plus de 95 % des cas, un syndrome inflammatoire biologique. Celui-ci est moins marqué en cas de complication ischémique visuelle ou neurologique. On distingue deux grands phénotypes d'ACG non exclusifs : d'une part, l'ACG céphalique où prédomine l'atteinte des vaisseaux céphaliques avec un risque plus élevé de complication ischémique ; d'autre part, l'ACG extracéphalique, qui concerne des patients moins âgés chez qui le risque ischémique est plus faible mais qui ont davantage de complications aortiques et rechutent plus souvent. La mise en place de structures de type fast track dans des centres spécialisés permet une prise en charge rapide afin d'identifier les patients à traiter en urgence, d'éviter les complications ischémiques et de réaliser rapidement les examens nécessaires à la confirmation du diagnostic et à une prise en charge adaptée.

[Treatment of giant cell arteritis]. / Traitement de l'artérite à cellules géantes.

TREATMENT OF GIANT CELL ARTERITIS. The treatment of giant cell arteritis (GCA) is based on glucocorticoids. This treatment significantly reduces the risk of ischemic complications, especially those of a visual nature, rapidly relieves the symptoms of the disease, and eliminates the inflammatory syndrome. The diagnosis of GCA must be able to question if corticosteroid therapy is ineffective. Once the symptoms have resolved and the inflammatory syndrome has normalized, glucocorticosteroids are tapered very gradually. The goal is to discontinue glucocorticosteroids in 12 to 18 months. Nearly half of patients experience flares during the glucocorticoid taper. These are usually benign, not visually life-threatening, and easily controlled by increasing glucocorticoids. However, these relapses contribute to prolonging the treatment duration and thus the cumulative dose of glucocorticoids received by patients, which leads to the occurrence of adverse effects of glucocorticoids in almost all patients. For this reason, it is sometimes necessary to prescribe glucocorticoid-sparing treatments, particularly methotrexate and tocilizumab. The efficacy of these treatments and others in development is essential and to be discussed. In addition, the management of patients with GCA should include preventive measures to reduce cardiovascular, infectious and osteoporosis risks.

TRAITEMENT DE L'ARTÉRITE À CELLULES GÉANTES. Le traitement de l'artérite à cellules géantes (ACG) repose sur la corticothérapie par voie générale. Ce traitement permet de diminuer significativement le risque de survenue de complication ischémique, en particulier visuelle, soulage rapidement les symptômes de la maladie et fait disparaître le syndrome inflammatoire. Face à une absence d'efficacité de la corticothérapie ou à un échappement rapide après que le traitement a été débuté, le diagnostic d'ACG doit être remis en cause. Une fois les symptômes disparus et le syndrome inflammatoire normalisé, les doses de corticoïdes sont diminuées très progressivement avec pour objectif le sevrage en douze à dix-huit mois. Lors de la décroissance des doses de corticoïdes, près de la moitié des patients présentent une ou plusieurs rechutes de la maladie. Celles-ci sont généralement bénignes, ne mettent pas en jeu le pronostic visuel et sont facilement contrôlées par une augmentation des doses de corticoïdes. Cependant, ces rechutes contribuent à prolonger la durée du traitement et donc la dose cumulée de corticoïdes reçue par les patients, ce qui conduit, chez presque tous les patients, à la survenue d'effets indésirables de la corticothérapie. C'est la raison pour laquelle la prescription de traitements d'épargne en corticoïdes, en particulier le méthotrexate et le tocilizumab, est parfois nécessaire. La place de ces traitements, et d'autres en cours de développement, est essentielle et sujet à débattre. Enfin, la prise en charge des patients atteints d'ACG doit inclure des mesures préventives pour diminuer le risque cardiovasculaire, le risque infectieux et le risque d'ostéoporose.

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.

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.

Predictive Factors of Giant Cell Arteritis in Polymyalgia Rheumatica Patients.

Polymyalgia rheumatica (PMR) is an inflammatory rheumatism of the shoulder and pelvic girdles. In 16 to 21% of cases, PMR is associated with giant cell arteritis (GCA) that can lead to severe vascular complications. Ruling out GCA in patients with PMR is currently a critical challenge for clinicians. Two GCA phenotypes can be distinguished: cranial GCA (C-GCA) and large vessel GCA (LV-GCA). C-GCA is usually suspected when cranial manifestations (temporal headaches, jaw claudication, scalp tenderness, or visual disturbances) occur. Isolated LV-GCA is more difficult to diagnose, due to the lack of specificity of clinical features which can be limited to constitutional symptoms and/or unexplained fever. Furthermore, many studies have demonstrated the existence-in varying proportions-of subclinical GCA in patients with apparently isolated PMR features. In PMR patients, the occurrence of clinical features of C-GCA (new onset temporal headaches, jaw claudication, or abnormality of temporal arteries) are highly predictive of C-GCA. Additionally, glucocorticoids' resistance occurring during follow-up of PMR patients, the occurrence of constitutional symptoms, or acute phase reactants elevation are suggestive of associated GCA. Research into the predictive biomarkers of GCA in PMR patients is critical for selecting PMR patients for whom imaging and/or temporal artery biopsy is necessary. To date, Angiopoietin-2 and MMP-3 are powerful for predicting GCA in PMR patients, but these results need to be confirmed in further cohorts. In this review, we discuss the diagnostic challenges of subclinical GCA in PMR patients and will review the predictive factors of GCA in PMR patients.

T-cell immune response predicts the risk of critical SARS-Cov2 infection in hospitalized COVID-19 patients.

INTRODUCTION: This study aimed to identify markers of disease worsening in patients hospitalized for SARS-Cov2 infection. PATIENTS AND METHODS: Patients hospitalized for severe recent-onset (<1 week) SARS-Cov2 infection were prospectively included. The percentage of T-cell subsets and plasma IL-6 at admission (before any steroid therapy) were compared between patients who progressed to a critical infection and those who did not. RESULTS: Thirty-seven patients (18 men, 19 women) were included; 11 (30%) progressed to critical infection. At admission, the critical infection patients were older (P = 0.021), had higher creatinine levels (P = 0.003), and decreased percentages of circulating B cells (P = 0.04), T cells (P = 0.009), and CD4+ T cells (P = 0.004) than those with a favorable course. Among T cell subsets, there was no significant difference between the two groups except for the percentage of Th17 cells, which was two-fold higher in patients who progressed to critical infection (P = 0.028). Plasma IL-6 at admission was also higher in this group (P = 0.018). In multivariate analysis, the percentage of circulating Th17 cells at admission was the only variable associated with higher risk of progression to critical SARS-Cov2 infection (P = 0.021). CONCLUSION: This study suggests that an elevated percentage of Th17 cells in patients hospitalized for SARS-Cov2 infection is associated with an increased risk of progression to critical disease. If these data are confirmed in a larger study, this marker could be used to better target the population of patients in whom tocilizumab could decrease the risk of progression to critical COVID-19.

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.

Human Monocyte-Derived Suppressor Cell Supernatant Induces Immunoregulatory Effects and Mitigates xenoGvHD.

Recently developed cell-based therapies have shown potential for graft-versus-host disease (GvHD) mitigation. Our team previously developed a protocol to generate human monocyte-derived suppressor Cells (HuMoSC), a subpopulation of CD33+ suppressor cells of monocytic origin. CD33+HuMoSC successfully reduced xenoGvHD severity in NOD/SCID/IL-2Rγc-/- (NSG) mice. While CD33+ HuMoSC culture supernatant inhibits T cell activation and proliferation, the recovery of CD33+ HuMoSC immunosuppressive cells and the subsequent production of their supernatant is limited. An attractive solution would be to use both the CD33+ and the large number of CD14+ cells derived from our protocol. Here, we assessed the immunoregulatory properties of the CD14+HuMoSC supernatant and demonstrated that it inhibited both CD4 and CD8 T cell proliferation and decreased CD8 cytotoxicity. In vivo, injection of CD14+HuMoSC supernatant reduced xenoGvHD in NSG mice. Furthermore, CD14+HuMoSC supernatant maintained its immunoregulatory properties in an inflammatory environment. Proteomic and multiplex analyses revealed the presence of immunosuppressive proteins such as GPNMB, galectin-3 and IL-1R(A) Finally, CD14+HuMoSC supernatant can be produced using good manufacturing practices and be used as complement to current immunosuppressive drugs. CD14+HuMoSC supernatant is thus a promising therapy for preventing GvHD. .

Mimickers of Large Vessel Giant Cell Arteritis.

Giant cell arteritis (GCA) is a large-vessel granulomatous vasculitis occurring in patients over 50-year-old. Diagnosis can be challenging because there is no specific biological test or other diagnoses to consider. Two main phenotypes of GCA are distinguished and can be associated. First, cranial GCA, whose diagnosis is usually confirmed by the evidence of a non-necrotizing granulomatous panarteritis on temporal artery biopsy. Second, large-vessel GCA, whose related symptoms are less specific (fever, asthenia, and weight loss) and for which other diagnoses must be implemented if there is neither cephalic GCA nor associated polymyalgia rheumatica (PMR) features chronic infection (tuberculosis, Coxiella burnetti), IgG4-related disease, Erdheim Chester disease, and other primary vasculitis (Behçet disease, relapsing polychondritis, or VEXAS syndrome). Herein, we propose a review of the main differential diagnoses to be considered regarding large vessel vasculitis.

Temporal Artery Vascular Diseases.

In the presence of temporal arteritis, clinicians often refer to the diagnosis of giant cell arteritis (GCA). However, differential diagnoses should also be evoked because other types of vascular diseases, vasculitis or not, may affect the temporal artery. Among vasculitis, Anti-neutrophil cytoplasmic antibodies (ANCA)-associated vasculitis is probably the most common, and typically affects the peri-adventitial small vessel of the temporal artery and sometimes mimics giant cell arteritis, however, other symptoms are frequently associated and more specific of ANCA-associated vasculitis prompt a search for ANCA. The Immunoglobulin G4-related disease (IgG4-RD) can cause temporal arteritis as well. Some infections can also affect the temporal artery, primarily an infection caused by the varicella-zoster virus (VZV), which has an arterial tropism that may play a role in triggering giant cell arteritis. Drugs, mainly checkpoint inhibitors that are used to treat cancer, can also trigger giant cell arteritis. Furthermore, the temporal artery can be affected by diseases other than vasculitis such as atherosclerosis, calcyphilaxis, aneurysm, or arteriovenous fistula. In this review, these different diseases affecting the temporal artery are described.