Immune response in Takayasu arteritis

High estrogen induces trans-differentiation of vascular smooth muscle cells to a macrophage-like phenotype resulting in aortic inflammation via inhibiting VHL/HIF1a/KLF4 axis

Estrogen is thought to have a role in slowing down aging and protecting cardiovascular and cognitive function. However, high doses of estrogen are still positively associated with autoimmune diseases and tumors with systemic inflammation. First, we administered exogenous estrogen to female mice for three consecutive months and found that the aorta of mice on estrogen develops inflammatory manifestations similar to Takayasu arteritis (TAK). Then, in vitro estrogen intervention was performed on mouse aortic vascular smooth muscle cells (MOVAS cells). Stimulated by high concentrations of estradiol, MOVAS cells showed decreased expression of contractile phenotypic markers and increased expression of macrophage-like phenotypic markers. This shift was blocked by tamoxifen and Krüppel-like factor 4 (KLF4) inhibitors and enhanced by Von Hippel-Lindau (VHL)/hypoxia-inducible factor-1α (HIF-1α) interaction inhibitors. It suggests that estrogen-targeted regulation of the VHL/HIF-1α/KLF4 axis induces phenotypic transformation of vascular smooth muscle cells (VSMC). In addition, estrogen-regulated phenotypic conversion of VSMC to macrophages is a key mechanism of estrogen-induced vascular inflammation, which justifies the risk of clinical use of estrogen replacement therapy.

The Contribution of Innate Immunity in Large-Vessel Vasculitis: Detangling New Pathomechanisms beyond the Onset of Vascular Inflammation

Large-vessel vasculitis (LVV) are autoimmune and autoinflammatory diseases focused on vascular inflammation. The central core of the intricate immunological and molecular network resides in the disruption of the "privileged immune state" of the arterial wall. The outbreak, initially primed by dendritic cells (DC), is then continuously powered in a feed-forward loop by the intimate cooperation between innate and adaptive immunity. If the role of adaptive immunity has been largely elucidated, knowledge of the critical function of innate immunity in LVV is still fragile. A growing body of evidence has strengthened the active role of innate immunity players and their key signaling pathways in orchestrating the complex pathomechanisms underlying LVV. Besides DC, macrophages are crucial culprits in LVV development and participate across all phases of vascular inflammation, culminating in vessel wall remodeling. In recent years, the variety of potential pathogenic actors has expanded to include neutrophils, mast cells, and soluble mediators, including the complement system. Interestingly, new insights have recently linked the inflammasome to vascular inflammation, paving the way for its potential pathogenic role in LVV. Overall, these observations encourage a new conceptual approach that includes a more in-depth study of innate immunity pathways in LVV to guide future targeted therapies.

Design and Protocol for Beijing Hospital Takayasu Arteritis (BeTA) Biobank

BACKGROUND

Although hundreds of studies have been conducted, our understanding of the pathogenesis, indications for surgical intervention, and disease markers of Takayasu arteritis (TAK) are still limited. Collection of biological specimens, clinical data and imaging data will facilitate translational research and clinical studies. In this study, we aim to introduce the design and protocol for the Beijing Hospital Takayasu Arteritis (BeTA) Biobank.

METHODS

Based in the Department of Vascular Surgery of Beijing Hospital and Beijing Hospital Clinical Biological Sample Management Center, the BeTA Biobank is composed of clinical data and sample data from patients with TAK requiring surgical treatment. All clinical data of participants are collected, including demographic characteristics, laboratory tests, imaging results, operation information, perioperative complications, follow-up data, etc. Both blood samples including plasma, serum and cells, and vascular tissues or perivascular adipose tissue are collected and stored. These samples will promote the establishment of a multiomic database for TAK and help to identify disease markers and to explore potential targets for specific future drugs for TAK.

Transcriptome profiling of abdominal aortic tissues reveals alterations in mRNAs of Takayasu arteritis

Takayasu arteritis (TA) is a chronic granulomatous vasculitis involving in the main branches of aorta. Previous studies mainly used peripheral blood and some vascular tissues but seldom studies have sequenced vascular tissues. Here in this study, we aimed to explore the alterations of mRNA in TA by performing bulk RNA sequencing. A total of 14 abdominal aortic tissues including 8 from renal transplantation and 6 from patient with TA undergoing bypass surgeries. Bulk RNA sequencing were performed and after the quality control, a total of 1897 transcripts were observed to be significantly differently (p < 0.05 and Log2FC > 1) expressed between the TA and control group, among which 1,361 transcripts were in TA group and 536 in the Control group. Reactome Pathway Enrichment Comparison analysis revealed interleukin-10 signaling and signaling by interleukins were highly expressed in TA group. Besides, extracellular matrix organization was also observed in this group. WGCNA and PPI obtained 26 core genes which were highly correlated with the clinical phenotype. We then also perform deconvolution of the bulk RNA-seq data by using the scRNA-seq dataset and noticed the high proportion of smooth muscle cells in our dataset. Additionally, immunohistochemical staining confirmed our bioinformatic analysis that TA aortic tissues express high levels of IL-1R1 and IL-1R2. Briefly, this study revealed critical roles of interleukins in TA pathogenesis, and SMCs may also participate in the reconstruction in vessel wall at late stage of TA.

The innate face of Giant Cell Arteritis: Insight into cellular and molecular innate immunity pathways to unravel new possible biomarkers of disease

Giant cell arteritis (GCA) is an inflammatory chronic disease mainly occurring in elderly individuals. The pathogenesis of GCA is still far from being completely elucidated. However, in susceptible arteries, an aberrant immune system activation drives the occurrence of vascular remodeling which is mainly characterized by intimal hyperplasia and luminal obstruction. Vascular damage leads to ischemic manifestations involving extra-cranial branches of carotid arteries, mostly temporal arteries, and aorta. Classically, GCA was considered a pathological process resulting from the interaction between an unknown environmental trigger, such as an infectious agent, with local dendritic cells (DCs), activated CD4 T cells and effector macrophages. In the last years, the complexity of GCA has been underlined by robust evidence suggesting that several cell subsets belonging to the innate immunity can contribute to disease development and progression. Specifically, a role in driving tissue damage and adaptive immunity activation was described for dendritic cells (DCs), monocytes and macrophages, mast cells, neutrophils and wall components, such as endothelial cells (ECs) and vascular smooth muscle cells (VSMCs). In this regard, molecular pathways related to cytokines, chemokines, growth factors, vasoactive molecules and reactive oxygen species may contribute to the inflammatory process underlying GCA. Altogether, innate cellular and molecular pathways may clarify many pathogenetic aspects of the disease, paving the way for the identification of new biomarkers and for the development of new treatment targets for GCA. This review aims to deeply dissect past and new evidence on the innate immunological disruption behind GCA providing a comprehensive description of disease development from the innate perspective.

Single-Cell RNA Sequencing Revealed CD14+ Monocytes Increased in Patients With Takayasu's Arteritis Requiring Surgical Management

Objectives: Takayasu Arteritis (TA) is a highly specific vascular inflammation and poses threat to patients’ health. Although some patients have accepted medical treatment, their culprit lesions require surgical management (TARSM). This study aimed at dissecting the transcriptomes of peripheral blood mononuclear cells (PBMCs) in these patients and to explore potential clinical markers for TA development and progression.

Methods: Peripheral blood were collected from four TA patients requiring surgical management and four age-sex matched healthy donors. Single cell RNA sequencing (scRNA-seq) was adopted to explore the transcriptomic diversity and function of their PBMCs. ELISA, qPCR, and FACS were conducted to validate the results of the analysis.

Results: A total of 29918 qualified cells were included for downstream analysis. Nine major cell types were confirmed, including CD14⁺ monocytes, CD8⁺ T cells, NK cells, CD4⁺ T cells, B cells, CD16⁺ monocytes, megakaryocytes, dendritic cells and plasmacytoid dendritic cells. CD14⁺ monocytes (50.0 vs. 39.3%, p < 0.05) increased in TA patients, as validated by FACS results. TXNIP, AREG, THBS1, and CD163 increased in TA patients. ILs like IL-6, IL-6STP1, IL-6ST, IL-15, and IL-15RA increased in TA group.

Conclusion: Transcriptome heterogeneities of PBMCs in TA patients requiring surgical management were revealed in the present study. In the patients with TA, CD14⁺ monocytes and gene expressions involved in oxidative stress were increased, indicating a new treatment and research direction in this field.

Elevated chemokines concentration is associated with disease activity in Takayasu arteritis

BACKGROUND

Chemokines were seldom investigated in Takayasu arteritis (TA) patients. This study aimed to evaluate the plasma levels of chemokines and their association with disease activity, including C-C chemokine ligand (CCL) 2, CCL3, CCL11, CCL20, C-X-C chemokine ligand (CXCL) 8 and CXCL10.

METHODS

Chemokines were measured in 85 TA patients, and 28 age- and gender-matched healthy controls. The disease activity of these TA patients was assessed according to the National Institute of Health (NIH) criteria. The relationship between the plasma levels of chemokines and disease activity was analyzed.

RESULTS

Among the 85 TA patients, 24 (28.2%) patients had active disease according to the NIH criteria. Significantly increased levels of CCL2, CCL3, CCL20, CXCL8 and CXCL10 were observed in TA patients when compared to healthy controls, while increased levels of CCL2, CCL20, CXCL8 and CXCL10 in TA patients with active disease when compared to those with inactive disease (all p < 0.05). The plasma cut-off values of CCL2, CCL20, CXCL8 and CXCL10 were 309.6 pg/ml, 131.4 pg/ml, 4.7 pg/ml, and 282.1 pg/ml, which maximized the ability of disease activity assessment and had a sensitivity/specificity of 66.7%/67.2%, 54.2%/77.1%,70.8%/72.1%,83.3%/54.1%, respectively (p < 0.05). Among patients with negative erythrocyte sedimentation rate, C-reactive protein or high-sensitivity C-reactive protein, CCL2, CCL20, CXCL8, and CXCL10 still had a high-sensitivity to recognize patients in the active phase.

CONCLUSIONS

This study showed that the expression level of CCL2, CCL20, CXCL8 and CXCL10 was elevated in active TA patients, indicating that these chemokines might act as potential biomarkers in evaluating the disease activity.

Targeting JAK/STAT pathway in Takayasu's arteritis

OBJECTIVE

Takayasu's arteritis (TAK) is a large vessel vasculitis with important infiltration of proinflammatory T cells in the aorta and its main branches, but its aetiology is still unknown. Our work aims to explore the involvement of Janus Kinase/Signal Transducers and Activators of Transcription (JAK/STAT) signalling pathway in proinflammatory T cells differentiation and disease activity of TAK.

METHODS

We analysed transcriptome and interferons gene signatures of fluorescence-activated cell sorting (FACS-sorted) CD4+ and CD8+ T cells from healthy donors (HD) and in 25 TAK (median age of 37.6 years including 21 active TAK with National Institutes of Health (NIH) score >1). Then we tested, in vitro and in vivo, the effects of JAK inhibitors (JAKinibs) in TAK.

RESULTS

Transcriptome analysis showed 248 and 432 significantly dysregulated genes for CD4+ and CD8+ samples between HD and TAK, respectively. Among dysregulated genes, we highlighted a great enrichment for pathways linked to type I and type II interferons, JAK/STAT and cytokines/chemokines-related signalling in TAK. We confirmed by Real Time Reverse Transcription Polymerase Chain Reaction (RT-qPCR) the upregulation of type I interferons gene signature in TAK as compared with HD. JAKinibs induced both in vitro and in vivo a significant reduction of CD25 expression by CD4+ and CD8+ T cells, a significant decrease of type 1 helper T cells (Th1) and Th17 cells and an increase of Tregs cells in TAK. JAKinibs also decreased C reactive protein level, NIH score and corticosteroid dose in TAK patients.

CONCLUSIONS

JAK/STAT signalling pathway is critical in the pathogenesis of TAK and JAKinibs may be a promising therapy.

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.

T-614 inhibits human aortic adventitial fibroblast proliferation and promotes interleukin-8 production in vitro

Objectives

The effect and underlying mechanism of T-614 (iguratimod) on Takayasu’s arteritis (TA) are unknown. Here, we report the effects of T-614 on cell proliferation and interleukin-8 (IL-8) production in human aortic adventitial fibroblasts (HAAFs) in vitro and explore its initial benefit in terms of vascular wall inflammation and remodeling for patients with TA.

Methods

HAAFs were cultured with 0, 5, 50, 100, or 250 μg/ml T-614 in the absence or presence of tumor necrosis factor-α (TNF-α) in vitro. Cell viability was determined by a modified MTT assay. Supernatant IL-8 levels were measured by enzyme-linked immunosorbent assays.

Results

In the presence of TNF-α, compared to that in the control group, cell viability of HAAFs significantly decreased in the 50, 100, and 250 μg/ml T-614 treatment groups (OD value: P <  0.01, P <  0.001, P <  0.001, respectively; survival fraction (SF): P <  0.05, P <  0.001, P <  0.001, respectively). However, there was no significant difference in cell viability between TNF-α-stimulated and unstimulated groups at the same concentration of T-614. In the absence or presence of TNF-α, T-614 suppressed HAAF cell viability dose-dependently (OD value: r = −0.915, P =  0.000; r = −0.926, P =  0.000, respectively; SF: r = −0.897, P =  0.000; r = −0.885, P =  0.000, respectively). Compared to that in the control group, in the absence of TNF-α, IL-8 levels in the 5 and 100 μg/ml T-614-treated groups were significantly higher ( P <  0.05); in the presence of TNF-α, IL-8 levels in the 5, 50, and 100 μg/ml T-614-treated groups were significantly higher ( P <  0.001, P <  0.001, P <  0.01, respectively). Further, there was a negative correlation between supernatant IL-8 levels and T-614 concentration in groups stimulated with TNF-α ( r = −0.670, P =  0.000), but there was no significant correlation between these parameters in groups that were not stimulated with TNF-α.

Conclusions

In the absence or presence of TNF-α, T-614 can inhibit HAAF proliferation and promote IL-8 production in vitro; therefore, it could be used to prevent adventitial thickening of the aorta and improve vascular remodeling in inflammatory environments in vitro and might provide a new immunotherapeutic intervention for TA.

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.