Downregulated Expression of miR-200c-3p in Plasma Exosome as a Potential Biomarker in Takayasu's Arteritis

Our previous work identified several differentially expressed miRNAs (DEmiRNAs) in plasma exosomes from Takayasu's arteritis (TAK) patients. This study aimed to validate these findings and explore the correlation between DEmiRNAs and clinical parameters in untreated TAK. Plasma exosomes were isolated from 30 untreated TAK patients and 20 healthy controls. qPCR was used to quantify miR-34a-5p, miR-143-3p, miR-22-3p, miR-200c-3p, and miR-21-5p expression. Correlations between miRNA levels, clinical data, inflammation markers, and T helper cell frequencies were analyzed. The target genes of validated DEmiRNAs were identified using mirDIP, and pathway enrichment analysis was performed using GO/KEGG. The effect of validated DEmiRNAs on the MAPK pathway and proliferation in human aortic endothelial cells (HAECs) was investigated in vitro. Only miR-200c-3p expression was validated as significantly downregulated in plasma exosomes from untreated TAK patients. Lower miR-200c-3p levels correlated negatively with ITAS-2010 scores and were associated with relapsed disease. MiR-200c-3p levels also negatively correlated with circulating Th17.1 cell frequencies. In vitro, the TAK exosome treatment activated ERK1/2 and JNK pathways and promoted HAEC proliferation, which was inhibited by the miR-200c-3p mimic. The pathway enrichment analysis showed that the MAPK pathway may be involved. This study confirms the reduced miR-200c-3p expression in plasma exosomes from TAK patients, suggesting its potential as a biomarker for vascular inflammation. MiR-200c-3p may exert protective effects in TAK by suppressing MAPK pathway activation and EC proliferation.

Active withdrawal of corticosteroids using tocilizumab and its association with autoantibody profiles in relapsed Takayasu arteritis: a multicentre, single-arm, prospective study (the Ab-TAK study)

Objectives

The feasibility of corticosteroid withdrawal (CW) for Takayasu arteritis (TAK) remains uncertain. Two autoantibodies (Abs) are identified against endothelial protein C receptor (EPCR) and scavenger receptor class B type 1 (SR-BI) in TAK, determining its three subgroups. This study aimed to evaluate CW using tocilizumab (TCZ) and its association with the Ab profile.

Methods

This prospective study, lasted for 24 weeks, included patients with relapsed but stable TAK. Scheduled tapering of prednisolone (PSL) was performed with subcutaneous TCZ (CW at week 20). The primary endpoint was the difference in type A remission, defined by CW and the absence of inflammatory signs, according to the Ab profile at week 24.

Results

Twenty patients were included and 18 patients with a mean PSL dose of 4.9 ± 2.8 mg/day were analysed. Anti-EPCR Ab-positive (E+), anti-SR-BI Ab-positive (S+), and double-negative (DN) groups included four (22.2%), eight (44.4%), and six (33.3%) patients, respectively. At week 24, the mean PSL dose was 2.0 ± 2.7 mg/day. Type A remission was observed in eight patients (44.4%), with significant differences based on the Ab profile: E+ (three patients, 75%), S+ (five patients, 62.5%), and DN (zero patients, 0%) (P=0.018). Besides, age, disease duration, PSL dose, type V arterial lesion, arterial dilation, and C-reactive protein >0.01 mg/dL were identified as risks for CW failure.

Conclusion

CW using TCZ was achieved in 44.4% of patients with TAK relapse and was significantly higher in E+ and S+ patients. CW can be a feasible target, and the precise selection of patients is critical.

Multi-Omics Exploration of the Role of PTGS2 as a Hub Gene in Ferroptosis Within the Artery of Takayasu Arteritis

Introduction

Takayasu arteritis (TAK) is an autoimmune disease affecting the aorta and its branches. Despite anti-inflammatory treatments, some patients require surgical vascular reconstruction due to rapid disease progression. The mechanisms behind persistent inflammation are unclear due to a lack of arterial samples. This study explores ferroptosis in TAK using high-throughput and single-cell transcriptomics.

Methods

Transcriptomic data were collected from 8 TAK patients (2 for single cell RNA-seq and 6 for bulk RNA-seq) and 8 renal transplant donors, with single-cell data from 3 public carotid artery samples for control. Bioinformatic analysis was performed to identify ferroptosis-related genes in inflamed arteries.

Results

We identified 1526 differentially expressed genes and 46 ferroptosis-related genes, with 6 genes including PTGS2 and HIF1A as hub genes. Single-cell analysis of 27,828 cells revealed increased M1-like macrophages, with PTGS2 highly expressed in these cells. Enrichment analysis indicated NF-κB signal pathway involvement.

Conclusion

PTGS2 is a core ferroptosis-related gene in TAK vascular inflammation, highly expressed in M1-like macrophages, potentially upregulated via the IL1B-NF-κB pathway.

mTOR signalling controls the formation of smooth muscle cell-derived luminal myofibroblasts during vasculitis

The accumulation of myofibroblasts within the intimal layer of inflamed blood vessels is a potentially catastrophic complication of vasculitis, which can lead to arterial stenosis and ischaemia. In this study, we have investigated how these luminal myofibroblasts develop during Kawasaki disease (KD), a paediatric vasculitis typically involving the coronary arteries. By performing lineage tracing studies in a murine model of KD, we reveal that luminal myofibroblasts develop independently of adventitial fibroblasts and endothelial cells, and instead derive from smooth muscle cells (SMCs). Notably, the emergence of SMC-derived luminal myofibroblasts-in both mice and patients with KD, Takayasu's arteritis and Giant Cell arteritis-coincided with activation of the mechanistic target of rapamycin (mTOR) signalling pathway. Moreover, SMC-specific deletion of mTOR signalling, or pharmacological inhibition, abrogated the emergence of luminal myofibroblasts. Thus, mTOR is an intrinsic and essential regulator of luminal myofibroblast formation that is activated in vasculitis patients and therapeutically tractable. These findings provide molecular insight into the pathogenesis of coronary artery stenosis and identify mTOR as a therapeutic target in vasculitis.

Vasa vasorum interna in the carotid wall of active forms of Takayasu arteritis evidenced by ultrasound localization microscopy

Introduction: Takayasu arteritis (TA) is associated with microvascularization of the wall of large arteries and is related to inflammation. Ultrasound localization microscopy (ULM), combining ultrafast ultrasound imaging with microbubble (MB) injection, can track the path of MBs within the arterial wall and thus provide imaging of the vasa vasorum. From the analysis of MB tracks in the common carotid arteries of patients with active TA, we report the presence of microvessels in connection with the carotid lumen (i.e., vasa vasorum interna [VVI]). Methods: ULM maps were obtained on five patients with active disease in the observational single-center series of the TAK-UF study. MB tracks connected to the carotid lumen were automatically identified, allowing the reconstruction of VVI. Results: MB tracking allows us to observe a microvascular network on the inner part of the wall, with some vessels in communication with the carotid lumen. This type of vessel was identified in all patients with active TA (n = 5) with a median of 2.2 [1.1-3.0] vessels per acquisition (2D longitudinal view of 3 cm of the common carotid artery). The blood flow within these vessels is mainly centrifugal; that is, toward the adventitia (88% [54-100] of MB tracks with flow directed to the outer part of the wall). Conclusion: VVI are present in humans in the case of active TA and emphasize the involvement of the intima in the pathological process. ClinicalTrials.gov Identifier: NCT03956394.

Arterial wall fibrosis in Takayasu arteritis and its potential for therapeutic modulation

Arterial wall damage in Takayasu arteritis (TAK) can progress despite immunosuppressive therapy. Vascular fibrosis is more prominent in TAK than in giant cell arteritis (GCA). The inflamed arterial wall in TAK is infiltrated by M1 macrophages [which secrete interleukin-6 (IL-6)], which transition to M2 macrophages once the inflammation settles. M2 macrophages secrete transforming growth factor beta (TGF-β) and glycoprotein non-metastatic melanoma protein B (GPNMB), both of which can activate fibroblasts in the arterial wall adventitia. Mast cells in the arterial wall of TAK also activate resting adventitial fibroblasts. Th17 lymphocytes play a role in both TAK and GCA. Sub-populations of Th17 lymphocytes, Th17.1 lymphocytes [which secrete interferon gamma (IFN-γ) in addition to interleukin-17 (IL-17)] and programmed cell death 1 (PD1)-expressing Th17 (which secrete TGF-β), have been described in TAK but not in GCA. IL-6 and IL-17 also drive fibroblast activation in the arterial wall. The Th17 and Th1 lymphocytes in TAK demonstrate an activation of mammalian target organ of rapamycin 1 (mTORC1) driven by Notch-1 upregulation. A recent study reported that the enhanced liver fibrosis score (derived from serum hyaluronic acid, tissue inhibitor of metalloproteinase 1, and pro-collagen III amino-terminal pro-peptide) had a moderate-to-strong correlation with clinically assessed and angiographically assessed vascular damage. In vitro experiments suggest the potential to target arterial wall fibrosis in TAK with leflunomide, tofacitinib, baricitinib, or mTORC1 inhibitors. Since arterial wall inflammation is followed by fibrosis, a strategy of combining immunosuppressive agents with drugs that have an antifibrotic effect merits exploration in future clinical trials of TAK.

Elevated serum immunoglobulin level predicts high risk of 1-year recurrence in patients with Takayasu arteritis

BACKGROUND

The mechanism of humoral immunity to Takayasu arteritis (TAK) is not clear. In our study, we aimed to investigate the correlation between immunoglobulins and disease activity and the relationship between immunoglobulins and the prognosis of TAK patients.

METHODS

One hundred ninety TAK patients divided into two groups according to whether they had elevated immunoglobulins or not. We compared the demographic data and the clinical data between the two groups. Pearson correlation was used to analyze the relationship between immunoglobulin and disease activity, as well as the relationship between their changes. Immunohistochemical staining was used to compare the expression of humoral immune cells in TAK and atherosclerotic patients. One hundred twenty TAK patients who achieved remission within 3 months after discharge were followed up for 1 year. Logistic regression was used to explore the relationship between elevated immunoglobulins and recurrence.

RESULTS

Disease activity and inflammatory factors were significantly higher in the group with elevated immunoglobulins than in the normal group [NIH (3.0 vs. 2.0, P = 0.001), ITAS-A (9.0 vs. 7.0, P = 0.006)]. Compared with atherosclerotic patients, CD138 + plasma cells were significantly increased in the aortic wall of patients with TAK (P = 0.021). Changes in IgG correlated well with CRP and ESR [CRP (r = 0.40, P = 0.027), ESR (r = 0.64, P < 0.001)]. For patients with TAK in remission, elevated immunoglobulins was associated with 1-year recurrence [OR95%, CI: 2.37 (1.03, 5.47), P = 0.042].

CONCLUSIONS

Immunoglobulins is of clinical value in evaluating disease activity in TAK patients. Moreover, the dynamic changes of IgG were correlated with the changes in inflammatory indicators in TAK patients.

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.

Mechanistic Target of Rapamycin Inhibition Prevents Coronary Artery Remodeling in a Murine Model of Kawasaki Disease

OBJECTIVE

Remodeling of the coronary arteries is a common feature in severe cases of Kawasaki disease (KD). This pathology is driven by the dysregulated proliferation of vascular fibroblasts, which can lead to coronary artery aneurysms, stenosis, and myocardial ischemia. We undertook this study to investigate whether inhibiting fibroblast proliferation might be an effective therapeutic strategy to prevent coronary artery remodeling in KD.

METHOD

We used a murine model of KD (induced by the injection of the Candida albicans water-soluble complex [CAWS]) and analyzed patient samples to evaluate potential antifibrotic therapies for KD.

RESULTS

We identified the mechanistic target of rapamycin (mTOR) pathway as a potential therapeutic target in KD. The mTOR inhibitor rapamycin potently inhibited cardiac fibroblast proliferation in vitro, and vascular fibroblasts up-regulated mTOR kinase signaling in vivo in the CAWS mouse model of KD. We evaluated the in vivo efficacy of mTOR inhibition and found that the therapeutic administration of rapamycin reduced vascular fibrosis and intimal hyperplasia of the coronary arteries in CAWS-injected mice. Furthermore, the analysis of cardiac tissue from KD fatalities revealed that vascular fibroblasts localizing with inflamed coronary arteries up-regulate mTOR signaling, confirming that the mTOR pathway is active in human KD.

CONCLUSION

Our findings demonstrate that mTOR signaling contributes to coronary artery remodeling in KD, and that targeting this pathway offers a potential therapeutic strategy to prevent or restrict this pathology in high-risk KD patients.

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.

Risk factors and surgical prognosis in patients with aortic valve involvement caused by Takayasu arteritis

Objective

Aortic valve involvement is not uncommon in patients with Takayasu arteritis (TAK) and leading to poor prognosis. The aim of our study was to explore the risk factors of aortic valve involvement and to evaluate the prognosis in TAK patients with aortic valve involvement.

Method

In this retrospective study, 172 TAK patients were divided into groups with or without aortic valve involvement to identify the risk factors. Patients who underwent aortic valve surgical treatment were followed up to assess cumulative incidence of postoperative adverse events.

Results

A total of 92 TAK patients (53.49%) had aortic valvular lesion. The infiltration of inflammatory cells was found in surgical specimens of aortic valve. Numano type IIb, elevated high-sensitivity C-reactive protein (hs-CRP) level, and dilation of ascending aorta and aortic root were statistically associated with aortic valvular lesion in TAK patients (OR [95%CI] 6.853 [1.685–27.875], p=0.007; 4.896 [1.646–14.561], p=0.004; 4.509 [1.517–13.403], p=0.007; 9.340 [2.188–39.875], p=0.003). The 1-, 5-, and 7-year cumulative incidence of postoperative adverse events were 14.7%, 14.7%, and 31.8%, respectively. Surgical methods (p=0.024, hazard ratio (HR) 0.082) and postoperatively anti-inflammatory therapy (p=0.036, HR 0.144) were identified as potential predictors of postoperative adverse events.

Conclusions

Regularly echocardiogram screening is suggested in patients with Numano type IIb and aggressive treatment should be performed early in TAK patients. As for TAK patients with aortic valve surgery, aortic root replacement seems to be the preferred option and regular anti-inflammatory therapy may reduce the occurrence of adverse events of them.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13075-022-02788-9.

An Update on Childhood-Onset Takayasu Arteritis

Takayasu Arteritis (TAK) is a rare large vessel vasculitis affecting the aorta and its major branches. The heterogeneous and often severe clinical manifestations result from systemic and local inflammation as well as end-organ ischemia. Disease flares are common and contribute to accrued damage over time with significant morbidity and mortality. Newer understanding of the pathogenesis in TAK has paved the way for the use of pathway targeting agents such as tumor necrosis factor (TNF)α- or interleuking (IL)-6-inhibitors with improved disease control. Nevertheless, long-term data are lacking, particularly in children; prognosis often remains guarded and the disease burden high. This article aims at providing a comprehensive review of childhood-onset TAK with a focus on recent publications.

Critical Role of Notch-1 in Mechanistic Target of Rapamycin Hyperactivity and Vascular Inflammation in Patients With Takayasu Arteritis

OBJECTIVE

Takayasu arteritis (TA) is a major type of large vessel vasculitis characterized by progressive inflammation in vascular layers. In our recent study we identified a central role of mechanistic target of rapamycin (mTOR) hyperactivity in proinflammatory T cell differentiation in TA. This study was undertaken to explore potential mechanisms underpinning T cell-intrinsic mTOR hyperactivity and vascular inflammation in TA, with a focus on Notch-1.

METHODS

Notch-1 expression and activity was determined according to Notch-1, activated Notch-1, and HES-1 levels. We detected mTOR activity with intracellular expression of phosphorylated ribosomal protein S6. Differentiation of proinflammatory T cells was analyzed by detecting Th1 and Th17 lineage-determining transcription factors. The function of Notch-1 was evaluated using γ-secretase inhibitor DAPT and gene knockdown using a short hairpin RNA (shRNA) strategy. We performed our translational study using humanized NSG mouse chimeras in which human vasculitis was induced using immune cells from TA patients.

RESULTS

CD4+ T cells from TA patients exerted Notch-1^high , leading to mTOR hyperactivity and spontaneous maldifferentiation of Th1 cells and Th17 cells. Blockade of Notch-1 using DAPT and Notch-1 shRNA efficiently abrogated mTOR complex 1 (mTORC1) activation and proinflammatory T cell differentiation. Mechanistically, Notch-1 promoted mTOR expression, interacted with mTOR, and was associated with lysosomal localization of mTOR. Accordingly, systemic administration of DAPT and CD4+ T cell-specific gene knockdown of Notch-1 could alleviate vascular inflammation in humanized TA chimeras.

CONCLUSION

Expression of Notch-1 is elevated in CD4+ T cells from TA patients, resulting in mTORC1 hyperactivity and proinflammatory T cell differentiation. Targeting Notch-1 is a promising therapeutic strategy for the clinical management of TA.

Large-vessel vasculitis

Large-vessel vasculitis (LVV) manifests as inflammation of the aorta and its major branches and is the most common primary vasculitis in adults. LVV comprises two distinct conditions, giant cell arteritis and Takayasu arteritis, although the phenotypic spectrum of primary LVV is complex. Non-specific symptoms often predominate and so patients with LVV present to a range of health-care providers and settings. Rapid diagnosis, specialist referral and early treatment are key to good patient outcomes. Unfortunately, disease relapse remains common and chronic vascular complications are a source of considerable morbidity. Although accurate monitoring of disease activity is challenging, progress in vascular imaging techniques and the measurement of laboratory biomarkers may facilitate better matching of treatment intensity with disease activity. Further, advances in our understanding of disease pathophysiology have paved the way for novel biologic treatments that target important mediators of disease in both giant cell arteritis and Takayasu arteritis. This work has highlighted the substantial heterogeneity present within LVV and the importance of an individualized therapeutic approach. Future work will focus on understanding the mechanisms of persisting vascular inflammation, which will inform the development of increasingly sophisticated imaging technologies. Together, these will enable better disease prognostication, limit treatment-associated adverse effects, and facilitate targeted development and use of novel therapies.

Age as a risk factor in vasculitis

Two vasculitides, giant cell arteritis (GCA) and Takayasu arteritis (TAK), are recognized as autoimmune and autoinflammatory diseases that manifest exclusively within the aorta and its large branches. In both entities, the age of the affected host is a critical risk factor. TAK manifests during the 2nd-4th decade of life, occurring while the immune system is at its height of performance. GCA is a disease of older individuals, with infrequent cases during the 6th decade and peak incidence during the 8th decade of life. In both vasculitides, macrophages and T cells infiltrate into the adventitia and media of affected vessels, induce granulomatous inflammation, cause vessel wall destruction, and reprogram vascular cells to drive adventitial and neointimal expansion. In GCA, abnormal immunity originates in an aged immune system and evolves within the aged vascular microenvironment. One hallmark of the aging immune system is the preferential loss of CD8⁺ T cell function. Accordingly, in GCA but not in TAK, CD8⁺ effector T cells play a negligible role and anti-inflammatory CD8⁺ T regulatory cells are selectively impaired. Here, we review current evidence of how the process of immunosenescence impacts the risk for GCA and how fundamental differences in the age of the immune system translate into differences in the granulomatous immunopathology of TAK versus GCA.

Integrated analysis of long non-coding RNA-microRNA-mRNA competing endogenous RNAregulatory networks in thromboangiitis obliterans

Thromboangiitis obliterans (TAO) is a non-atherosclerotic, segmental, chronic vascular inflammatory disease. Our aim was to explore the underlying mechanisms of long non-coding RNA (lncRNA)-related competing endogenous RNAs (ceRNAs) in TAO. Six blood samples were collected from patients with TAO and healthy individuals (three for each category). Total RNA was extracted from the blood of each participant and sequenced. Differentially expressed lncRNAs (DE-lncRNAs) and miRNAs (DE-miRNAs) were screened, and ceRNA networks associated with TAO were constructed. Thereafter, the genes in the ceRNA network were subjected to functional analyses. Finally, a ceRNA relationship (lncRNA NEAT1-hsa-miR-1-3p-mRNA GNA12) was selected for further validation. Analysis revealed that 347 DE-lncRNAs (150 downregulated and 197 upregulated) and 16 DE-miRNAs (3 downregulated and 13 upregulated) were identified in TAO. Further, TAO-associated ceRNA networks, which included 219 lncRNAs, 6 miRNAs, and 53 mRNAs, were proposed and subjected to gene annotation and pathway analysis. Additionally, NEAT1 and GNA12 levels were significantly upregulated, while miR-1-3p levels were evidently downregulated in TAO patients, as compared with those in healthy controls. Dual luciferase reporter assays showed that NEAT1, miR-1-3p, and GNA12 interacted with each other. We report potential TAO-associated ceRNA regulatory networks and suggest activation of NEAT1/miR-1-3p/GNA12 signaling as a novel mechanism for TAO progression.

Highlights in clinical medicine-Giant cell arteritis, polymyalgia rheumatica and Takayasu's arteritis: pathogenic links and therapeutic implications

Giant cell arteritis (GCA), frequently associated with polymyalgia rheumatica (PMR), and Takayasu's arteritis (TAK) are characterized by extensive vascular remodeling that results in occlusion and stenosis. The pathophysiological mechanisms underlying the onset of GCA/PMR and TAK are still hypothetical. However, similarities and differences in the immunopathology and clinical phenotypes of these diseases point toward a possible link between them. The loss of tolerance in the periphery, a breakdown of tissue barriers, and the development of granulomatous vasculitis define a disease continuum. However, statistically powered studies are needed to confirm these correlations. In addition to glucocorticoids, inhibition of the interleukin-6 axis has been proposed as a cornerstone in the treatment of GCA/PMR and TAK. Novel biologic agents targeting the pathogenic pathway at various levels hold promise to achieve glucocorticoid-free sustained remission.

Application progress of multiple imaging modalities in Takayasu arteritis

Takayasu arteritis (TA) is a chronic, idiopathic, granulomatous large vessel vasculitis of unknown etiology. The clinical manifestations of TA are incredibly variable, mainly depending on the location of the lesions. In the light of its insidious progress and the diversity of clinical manifestations, a substantial proportion of patients might experience a considerable delay in diagnosis, which leads to irreversible malignant complications, highlighting the importance of early diagnosis. There has been accumulating evidence that early identification of disease is pivotal to initiate timely therapy and ameliorate the prognosis. Therefore, this review discusses and summarizes the latest evidence on the application progress of multiple imaging modalities.

Takayasu arteritis: a cohort of Italian patients and recent pathogenetic and therapeutic advances

Takayasu arteritis (TAK) is a rare granulomatous vasculitis of unknown etiology that mainly affects the aorta and its major branches. The aim is to describe the clinical features, diagnostic procedures, pathogenesis, and management of TAK in a longitudinal cohort of patients recruited within a single region of southern Italy. The cohort included 43 patients who were diagnosed with TAK and followed up according to a standard protocol, in a collaboration between four university tertiary referral centers and a regional hospital. Clinical and imaging classification criteria were those established by the American College of Rheumatology. Thirty-five patients (81.4%) were female, and the mean age at disease onset was 32.6 (range 16–54) years. Angiographic assessment of the vascular involvement allowed disease classification in five different types. Clinical features ranged from constitutional symptoms in the early inflammatory stage of the disease to cardiovascular ischemic symptoms in the late, chronic stage. Noninvasive imaging techniques were employed to assess the extent and severity of the arterial wall damage and to monitor the clinical course and response to therapy. Medical treatment, based on pathogenetic insights into the roles of humoral and cell-mediated immune mechanisms, included glucocorticoids mostly combined with steroid-sparing immunosuppressive agents and, in patients with relapsing/refractory disease, biologic drugs. Significant clinical and angiographic differences have been detected in TAK patients from different geographic areas. Patients with life-threatening cardiovascular and neurologic manifestations as well as sight-threatening ophthalmologic signs and symptoms should be promptly diagnosed, properly treated, and closely followed up to avoid potentially severe consequences.

Cellular Signaling Pathways in Medium and Large Vessel Vasculitis

Autoimmune and autoinflammatory diseases of the medium and large arteries, including the aorta, cause life-threatening complications due to vessel wall destruction but also by wall remodeling, such as the formation of wall-penetrating microvessels and lumen-stenosing neointima. The two most frequent large vessel vasculitides, giant cell arteritis (GCA) and Takayasu arteritis (TAK), are HLA-associated diseases, strongly suggestive for a critical role of T cells and antigen recognition in disease pathogenesis. Recent studies have revealed a growing spectrum of effector functions through which T cells participate in the immunopathology of GCA and TAK; causing the disease-specific patterning of pathology and clinical outcome. Core pathogenic features of disease-relevant T cells rely on the interaction with endothelial cells, dendritic cells and macrophages and lead to vessel wall invasion, formation of tissue-damaging granulomatous infiltrates and induction of the name-giving multinucleated giant cells. Besides antigen, pathogenic T cells encounter danger signals in their immediate microenvironment that they translate into disease-relevant effector functions. Decisive signaling pathways, such as the AKT pathway, the NOTCH pathway, and the JAK/STAT pathway modify antigen-induced T cell activation and emerge as promising therapeutic targets to halt disease progression and, eventually, reset the immune system to reestablish the immune privilege of the arterial wall.

Cardiac valvular involvement of Takayasu arteritis

OBJECTIVE

This study aimed to investigate the imaging and serological features in Takayasu arteritis (TA) patients with valvular involvement and determine the relationship between them.

METHOD

This is a retrospective single-center study enrolled 103 TA patients fulfilling the American College of Rheumatology criteria. An independent medical chart review was performed by two senior rheumatologists from Beijing Anzhen Hospital, Capital Medical University. The logistic analysis was used to investigate the relationship between valvular involvement in TA patients and the imaging and serological features of them.

RESULTS

Sixty-six TA patients (64.08%) had cardiac valvular involvement in our study. Aortic insufficiency (62.12%) was the most common valvular involvement. Twelve (22.22%) patients developed heart failure. In patients with valvular involvement, the most common angiographic type was Numano type V, which was significantly higher than that in patients without valvular involvement (53.30% vs 32.43%, p = 0.044), followed by coronary involvement (28.79% vs 10.81%, p = 0.036) and Numano type IIb (21.21% vs 5.41%, p = 0.034). Serum levels of immunoglobulin A (2.84 ± 1.42 g/L vs 2.26 ± 0.97 g/L, p = 0.032) and immunoglobulin G (13.5 ± 4.71 g/L vs 11.42 ± 3.01 g/L, p = 0.015) were significantly higher in patients with valvular involvement. Numano type IIb is significantly related to moderate-severe aortic valvular regurgitation in TA patients (4.10 [1.03-16.33], p = 0.04). Elevated C-reactive protein (CRP) level is associated with moderate-severe mitral valve involvement in TA patients (p = 0.05, OR = 17.75, 95% CI 1.07-295.41).

CONCLUSIONS

CRP elevation and Numano type IIb are significantly related to different types of valvular involvement in TA patients. Key Points • The Numano types IIb and V were common in TA patients with valvular involvement. • CRP elevation and Numano type IIb are close related to valvular involvement in TA patient. • Echocardiogram screening and CRP level examination are reasonable to TA patients which might have valvular involvement.

Identification of two major autoantigens negatively regulating endothelial activation in Takayasu arteritis

The presence of antiendothelial cell antibodies (AECAs) has been documented in Takayasu arteritis (TAK), a chronic granulomatous vasculitis. Here, we identify cell-surface autoantigens using an expression cloning system. A cDNA library of endothelial cells is retrovirally transfected into a rat myeloma cell line from which AECA-positive clones are sorted with flow cytometry. Four distinct AECA-positive clones are isolated, and endothelial protein C receptor (EPCR) and scavenger receptor class B type 1 (SR-BI) are identified as endothelial autoantigens. Autoantibodies against EPCR and SR-BI are detected in 34.6% and 36.5% of cases, respectively, with minimal overlap (3.8%). Autoantibodies against EPCR are also detected in ulcerative colitis, the frequent comorbidity of TAK. In mechanistic studies, EPCR and SR-BI function as negative regulators of endothelial activation. EPCR has also an effect on human T cells and impair Th17 differentiation. Autoantibodies against EPCR and SR-BI block the functions of their targets, thereby promoting pro-inflammatory phenotype.

Autoantibodies against endothelium have been recognized in Takayasu arteritis (TAK). Here the authors identify endothelial protein C receptor and scavenger receptor class B type 1 as major autoantigens in TAK, and find autoantibodies inhibit the negative regulation of endothelial activation.

Metabolic pathways mediate pathogenesis and offer targets for treatment in rheumatic diseases

PURPOSE OF REVIEW

The cause of autoimmune diseases remains incompletely understood. Here, we highlight recent advances in the role of proinflammatory metabolic pathways in autoimmune disease, including treatment with antioxidants and mechanistic target of rapamycin (mTOR) inhibitors.

RECENT FINDINGS

Recent studies show that mTOR pathway activation, glucose utilization, mitochondrial oxidative phosphorylation, and antioxidant defenses play critical roles in the pathogenesis of autoimmune diseases, including rheumatoid arthritis, immune thrombocytopenia, Sjögren's syndrome, large vessel vasculitis, and systemic lupus erythematosus. mTOR activity leads to Th1 and Th17 cell proliferation, Treg depletion, plasma cell differentiation, macrophage dysfunction, and increased antibody and immune complex production, ultimately resulting in tissue inflammation. mTOR also affects the function of connective tissue cells, including fibroblast-like synoviocytes, endothelial cells, and podocytes. mTOR inhibition via rapamycin and N-acetylcysteine, and blockade of glucose utilization show clinical efficacy in both mouse models and clinical trials, such as systemic lupus erythematosus.

SUMMARY

The mTOR pathway is a central regulator of growth and survival signals, integrating environmental cues to control cell proliferation and differentiation. Activation of mTOR underlies inflammatory lineage specification, and mTOR blockade-based therapies show promising efficacy in several autoimmune diseases.

Elevated antistreptolysin O titer is closely related to cardiac mitral insufficiency in untreated patients with Takayasu arteritis

Background

The etiology of Takayasu arteritis (TA) is unknown; however, a possible relationship between streptococcal infection and TA has been proposed. This study aimed to identify the clinical features and cardiac valvular involvement in untreated TA patients with an elevated antistreptolysin O (ASO) titer.

Methods

In this retrospective study, the clinical characteristics and features of valvular involvement were compared in TA patients with or without an elevated ASO titer.

Results

Of the 74 untreated TA patients, 13 patients were found have elevated ASO titers (17.6%). Mitral insufficiency was the most common in patients with elevated ASO (69.2%, 9/13), followed by aortic valve insufficiency (46.2%, 5/13) and tricuspid insufficiency (46.2%, 5/13), which were no significantly different than that in normal ASO group. The proportions of moderate to severe mitral (30.8% vs 1.6%, p = 0.000) and tricuspid valve (15.4% vs 1.64%, p = 0.023) insufficiency in the ASO positive group were significantly higher than those in the ASO negative group. The odds of mitral regurgitation in patients with elevated ASO titers were 3.9 times higher than those in the group with normal ASO titers (p = 0.053, OR = 3.929, 95% confidence interval [CI]: 0.983–15.694). Furthermore, the risk of moderate to severe mitral insufficiency in patients with elevated ASO titers was 41.6 times higher than that in patients with normal ASO titers (p = 0.002, OR = 41.600, 95% CI: 3.867–447.559).

Conclusions

An increase in ASO titer is related to valvular involvement in TA and is closely linked to mitral insufficiency.

[Physiopathology of giant cell arteritis: From inflammation to vascular remodeling]

Giant cell arteritis (GCA) is a large-vessel vasculitis involving the aorta and its main branches, especially supra aortic branches. Although much progress has been made, the pathophysiology remains incompletely understood. An initial trigger, suspected of infectious origin, lead to the maturation and recruitment of dendritic cells (DC). The lack of migration of these DC allows the local recruitment of T-lymphocytes (LT). These LT- CD4⁺ polarize in Type 1 helper (Th1), Th17 but also Th9. A qualitative and quantitative deficit in regulatory T cells (Treg) is observed under the influence of IL-21 overproduction. In addition, an imbalance in the Th17/Treg balance is favored by IL-6. The secretion of IFN-γ, IL-17, IL-6, IL-33 is responsible for a sustained local inflammatory reaction that is organized around tertiary lymphoid follicles. Locally recruited macrophages secrete reactive forms of oxygen together with VEGF and PDGF. These growth factors, together with neurotrophins and endothelin contribute to increase the proliferation of vascular smooth muscle cells (VSMCs). The imbalance between matrix metalloproteases (MMP)-2, MMP-9 and MMP-14 and tissue inhibitors of metalloproteases (TIMP)-1 and TIMP-2 also contribute to the remodeling process occurring in the vessel wall. Finally, arterial neovascularization contribute to the perpetuation of lymphocyte recruitment. This persistent remodeling is sometimes complicated by ischemic events responsible for the initial severity of the disease.

Refractory Takayasu arteritis successfully treated with rituximab: case-based review

Takayasu arteritis (TAK) is a subtype of the large-vessel vasculitis, affecting the aorta and its major branches. Although T cell-mediated autoimmunity is mainly involved in vascular inflammation, in recent years, accumulating evidence suggests the important role of B cells in the pathogenesis and effectiveness of B-cell-targeted therapy with rituximab (RTX), a chimeric anti-CD20 monoclonal antibody in refractory TAK. Herein, we report for the first time a case involving a 34-year-old man with TAK who was refractory to four different biologic agents, such as one selective T-cell co-stimulation modulator (abatacept), one anti-interleukin-6 receptor monoclonal antibody (tocilizumab), and two tumor necrosis factor-α inhibitors (infliximab and etanercept), but eventually achieved remission with RTX. He received a total of six courses of RTX, and doses of prednisolone and methotrexate were tapered without relapse. The current case provided further evidence to the potential role of RTX therapy in patients with refractory TAK, and its efficacy needs to be validated in a controlled trial.

New Insights on the Pathogenesis of Takayasu Arteritis: Revisiting the Microbial Theory

Takayasu arteritis (TAK) is a chronic vasculitis that mainly affects the aorta, its major branches, and the pulmonary arteries. Since the description of the first case by Mikito Takayasu in 1908, several aspects of this rare disease, including the epidemiology, diagnosis, and the appropriate clinical assessment, have been substantially defined. Nevertheless, while it is well-known that TAK is associated with a profound inflammatory process, possibly rooted to an autoimmune disorder, its precise etiology has remained largely unknown. Efforts to identify the antigen(s) that trigger autoimmunity in this disease have been unsuccessful, however, it is likely that viruses or bacteria, by a molecular mimicry mechanism, initiate or propagate the auto-immune process in this disease. In this article, we summarize recent advances in the understanding of TAK, with emphasis on new insights related to the pathogenesis of this entity that may contribute to the design of novel therapeutic approaches.

mTOR pathway activation in large vessel vasculitis

BACKGROUND

Mammalian target of rapamycin complex 1 (mTORC 1) drives the proinflammatory expansion of T helper (TH) type 1, TH17 cells and controls fibroblast proliferation, typical features of large vessel vasculitis (LVV) pathogenesis. Molecular pathways involved in arterial lesions of LVV are unknown.

METHODS

We evaluate mTORC pathway activation in vascular aorta lesions and in T cell homeostasis of patients with LVV.

RESULTS

Proliferation of both endothelial cells and vascular smooth-muscle cells was shown in vascular lesions in LVV. The vascular endothelium of proliferating aorta vessels from patients with LVV showed indications of activation of the mTORC1 pathway (S6RP phosphorylation). In cultured vascular endothelial cells, sera from patients with LVV stimulated mTORC1 through the phosphorylation of S6RP. mTORC1 activation was found also in Th1 and Th17 cells both systemically and in inflamed vessels. Patients with LVV exhibited a diminished S6RP phosphorylation in Tregs. Inhibition of mTORC1 pathway with rapamycin, increase Tregs and decrease effector CD4⁺IFNγ⁺, CD4⁺IL17⁺ and CD4⁺IL21⁺ T cells in patients with LVV.

CONCLUSIONS

We provided evidence that mTORC1 pathway has a central role in driving T cell inflammation and vascular lesions in LVV. Targeting mTORC pathway may represent a new therapeutic option in patients with LVV.