A novel molecular mechanism of vascular fibrosis in Takayasu arteritis: macrophage-derived GPNMB promoting adventitial fibroblast extracellular matrix production in the aorta.

Takayasu arteritis (TAK) is a chronic large vessel disease characterized by aortic fibrotic thickening, which was mainly mediated by activation of aorta adventitial fibroblasts (AAFs). Our previous genetic study demonstrated that TAK-associated locus IL6 rs2069837 regulated glycoprotein non-metastatic melanoma protein B (GPNMB) expression. Thus, this study aimed to investigate the pathogenic role of GPNMB in TAK. Through pathological staining, we find that GPNMB was mainly expressed in vascular adventitia and positively correlated with adventitial extracellular matrix (ECM) expression in TAK vascular lesion. Specifically, GPNMB was increased in adventitial CD68+ macrophages, which were closely located with CD90+ adventitial fibroblasts. In in-vitro cell culture, THP-1-derived macrophages with GPNMB overexpression promoted ECM expression in AAFs. This effect was also confirmed in aortic tissue or AAFs culture with GPNMB overexpression or active GPNMB protein stimulation. Mechanistically, Co-IP assay and siRNA or inhibitor intervention demonstrated that integrin αVß1 receptor mediated GPNMB effect on AAFs, which also activated downstream Akt and Erk pathway in AAFs. Furthermore, we showed that leflunomide treatment inhibited GPNMB-mediated fibrosis in AAFs, as well as GPNMB expression in macrophages, which were also partially validated in leflunomide-treated patients. Taken together, these data indicated that macrophage-derived GPNMB promotes AAFs ECM expression via the integrin αVß1 receptor and Akt/Erk signaling pathway and leflunomide might play an anti-fibrotic role in TAK by interfering with the macrophage-derived GPNMB/AAFs axis. This study provides evidence that targeting GPNMB is a potential therapeutic strategy for treating vascular fibrosis in TAK.

A comprehensive profile of chemokines in the peripheral blood and vascular tissue of patients with Takayasu arteritis.

BACKGROUND: Takayasu arteritis (TAK) is a chronic granulomatous large vessel vasculitis with multiple immune cells involved. Chemokines play critical roles in recruitment and activation of immune cells. This study aimed to investigate chemokine profile in the peripheral blood and vascular tissue of patients with TAK. METHODS: A total of 58 patients with TAK and 53 healthy controls were enrolled. Chemokine array assay was performed in five patients with TAK and three controls. Chemokines with higher levels were preliminarily validated in 20 patients and controls. The validated chemokines were further confirmed in another group of samples with 25 patients and 25 controls. Their expression and distribution were also examined in vascular tissue from 8 patients and 5 controls. Correlations between these chemokines and peripheral immune cells, cytokines, and disease activity parameters were analyzed. Their serum changes were also investigated in these 45 patients after glucocorticoids and immunosuppressive treatment. RESULTS: Patients and controls were age and sex-matched. Twelve higher chemokines and 4 lower chemokines were found based on the chemokine array. After validation, increase of 5 chemokines were confirmed in patients with TAK, including CCL22, RANTES, CXCL16, CXCL11, and IL-16. Their expressions were also increased in vascular tissue of patients with TAK. In addition, levels of RANTES and IL-16 were positively correlated with peripheral CD3+CD4+ T cell numbers. Close localization of CCL22, CXCL11, or IL-16 with inflammatory cells was also observed in TAK vascular tissue. No correlations were found between these chemokines and cytokines (IL-6, IL-17, IFN-γ) or inflammatory parameters (ESR, CRP). No differences were observed regarding with these chemokines between active and inactive patients. After treatment, increase of CCL22 and decrease of RANTES and CXCL16 were found, while no changes were showed in levels of CXCL11 and IL-16. CONCLUSIONS: CCL22, RANTES, CXCL16, CXCL11, and IL-16 were identified as the major chemokines involved in the recruitment of immune cells in the vascular tissue of patients with TAK. Additionally, the persistently high levels of CCL22, CXCL11, and IL-16 observed after treatment indicate their role in vascular chronic inflammation or fibrosis and demonstrate the need for developing more efficacious treatment options.

Potential Role of Macrophage Phenotypes and CCL2 in the Pathogenesis of Takayasu Arteritis.

Objectives: To investigate vascular macrophage phenotype as well as vascular and peripheral chemokine (C-C motif) ligand 2 (CCL2) expression during different stages of disease progression in patients with Takayasu Arteritis (TA). Methods: In this study, 74 patients with TA and 50 controls were recruited. TA disease activity was evaluated with Kerr scores. Macrophage phenotype and CCL2 expression were examined by immunohistochemistry in vascular specimens from 8 untreated and 7 treated TA patients, along with 4 healthy controls. Serum CCL2 were quantified by enzyme-linked immune-absorbent assay from TA patients at baseline (n=59), at 6-months (n=38), and from 46 healthy volunteers. Vascular macrophage phenotype, vascular CCL2 expression and serum CCL2 levels during different stages, as well as the relationship between serum CCL2 and disease activity or other inflammatory parameters (erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), and interleukin 6 (IL-6)) were investigated. Results: In untreated patients, vascular M1 macrophages and CCL2 showed increased expression, mainly in the adventitia. In contrast, in treated patients, vascular adventitial M1 and CCL2 expression were decreased, while vascular medial M2 macrophages and CCL2 levels were increased. Distribution of macrophages and CCL2 was consistent within the TA vascular lesions regardless of the disease stage. Furthermore, peripheral CCL2 was elevated in patients with TA (TA: 160.30 ± 120.05 vs. Control: 65.58 ± 54.56 pg/ml, P < 0.001). CCL2 levels were found to correlate with ESR, CRP, and IL-6 (all R values between 0.55 and 0.6, all P < 0.001). Receiver operating curve analysis demonstrated that CCL2 (at the cut-off value of 100.36 pg/ml) was able to predict disease activity (area under the curve = 0.74, P = 0.03). Decrease in CCL2 level was observed in patients with clinical remission (CR), but not in patients without CR, after 6 months of treatment (CR patients: baseline 220.18 ± 222.69 vs. post-treatment 88.71 ± 55.89 pg/ml, P = 0.04; non-CR patients: baseline 142.45 ± 104.76 vs. post-treatment 279.49 ± 229.46 pg/ml, P = 0.02). Conclusions: Macrophages contribute to vascular pathological changes in TA by undergoing phenotype transformation. CCL2 is an important factor for recruiting macrophages and a potential biomarker for disease activity.

Risk assessment model for heart failure in Chinese patients with Takayasu's arteritis.

OBJECTIVES: We aimed to construct and validate a risk assessment model to identify risk factors for heart failure (HF) in patients with Takayasu's arteritis (TAK). METHODS: Three hundred sixty-five patients with TAK were recruited in the East China Takayasu Arteritis Cohort from January 2012 to December 2019. Patients were assigned into training and validation sets following a 2:1 ratio according to the date of enrollment. Clinical characteristics were compared between heart failure (HF) and non-HF subgroups in the training set, and a risk assessment model for HF and its scoring algorithm was established based on logistic regression, which was tested in the validation set. RESULTS: Among total of 74 (20.27%) TAK patients exhibited HF, and 55 cases (74.32%) were in the training set. The risk factors for HF of TAK patients included onset age >38 years, serum tumor necrosis factor (TNF)-α concentration >10 pg/ml, aortic valve involvement, coronary artery involvement, and pulmonary hypertension. We constructed the model without TNF-α (Model 1) and with TNF-α (Model 2). Patients in the training set with the score ≥ 3 appeared to be associated with an increased risk of HF with an area under curve (AUC) of 0.88 and 0.90 in Model 1 and Model 2 respectively. The AUC reached to 0.88 and 0.89 in the validation set that proved the accuracy of the model. CONCLUSIONS: We presented a risk assessment model of HF in TAK, which may help clinicians alert the complication of HF in the patients with specifically cardiac impairments. Key Points • Heart failure was not rare in Chinese Takayasu's arteritis patients, and there were approximately 20% of patients with heart failure in ECTA cohort. • Cardiac involvements on echocardiography include pathological valvular and atrioventricular abnormalities. • The onset age >38 years, serum tumor necrosis factor (TNF)-α concentration >10 pg/ml, aortic valve involvement, coronary artery involvement, and pulmonary hypertension were risk factors for heart failure in Takayasu's arteritis patients. • We constructed the model without TNF-α (Model 1) and with TNF-α (Model 2). Patients with the risk assessment model score of ≥ 3 appeared to be associated with an increased risk of heart failure.

Pro-fibrotic effect of IL-6 via aortic adventitial fibroblasts indicates IL-6 as a treatment target in Takayasu arteritis.

OBJECTIVES: This study aimed to clarify potential mechanism of IL-6 involved in adventitial fibrosis via adventitial fibroblast in Takayasu arteritis (TAK). METHODS: Immunohistochemistry and double-labelled immunofluorescence were performed on vascular tissue from patients with TAK and controls. Human aorta adventitial fibroblast (AAF) was cultured and stimulated with interleukine 6 (IL-6)/IL-6 receptor (IL-6R). Real-time PCR, western blot, enzyme-linked immunosorbent assays, chromatin immunoprecipitation (ChIP) and reporter assay were conducted in vitro experiments to determine effect of IL-6/IL-6R on AAF. RESULTS: The expression of IL-6, IL-6R, collagen I, collagen III, fibronectin, α-smooth muscle actin (α-SMA), and transforming growth factor (TGF-ß) in TAK arteries was significantly higher than that in the normal arteries. Co-localisation of α-SMA and IL-6 and a positive correlation between their expression were observed in local lesions. In vitro experiments, collagen I, collagen III, fibronectin, α-SMA, and TGF-ß expression increased significantly after stimulation and this fibrogenesis of AAFs was induced in TGF-ß-dependent and -independent manners. Additionally, phosphorylation of JAK2, STAT3 and Akt was significantly enhanced both in IL-6/IL-6R-treated AAFs in vitro and in TAK adventitial α-SMA positive cells. When AAFs were pretreated with inhibitors against JAK2, STAT3, and Akt, fibrosis was significantly reduced. Furthermore, IL-6/IL-6R promoted mRNA expression of IL-6 and MCP-1 in AAFs. Finally, according to ChIP and reporter assay results, STAT3 was the main transcriptional factor in the fibrosis of AAFs induced by IL-6/IL-6R. CONCLUSIONS: IL-6/IL-6R induces fibrogenesis of AAFs via the JAK2/STAT3 and JAK2/Akt pathways, which provides theoretical evidence for IL-6 as a treatment target in TAK.

The critical role of IL-6 in the pathogenesis of Takayasu arteritis.

OBJECTIVES: To investigate T cell subsets and immune cytokine profiles in untreated Takayasu arteritis (TAK) patients and the underlying immunopathological mechanism. METHODS: We enrolled 50 untreated TAK patients and 40 age-matched controls (20 healthy controls, 20 untreated SLE patients). Enzyme-linked immunosorbent assays (ELISAs) were used to define cytokine profiles in all patients, and flow cytometry was performed for 9 TAK patients and 12 healthy controls. Hematoxylin and eosin (Handamp;E) staining and immunohistochemistry (IHC) were performed in aortic tissues of 9 TAK and 9 atherosclerosis patients; clinical data were also collected. RESULTS: Circulating CD4(+) T cells were more frequent in TAK patients (p<0.05). Frequencies of Th1, Th2, and Th17 cells were higher, whereas Treg cells were reduced in TAK. Significantly higher levels of IL-6 and lower levels of IFN-γ, IL-4, and IL-17 were detected in TAK patients (p<0.05). By H & E staining, thickened vascular walls with proliferation of collagen fibre were observed in most patients. Inflammatory sites with infiltrating macrophages, lymphocytes, and neutrophils were located in adventitia. IHC revealed T cells (mainly CD4(+) T cells) in vascular lesions. Additionally, IL-6 was positive throughout the vascular wall in most specimens, whereas IFN-γ, IL-12, and IL-17 were detected in inflammatory sites of active patients. IL-6 levels were positively related to ESR, CRP, and Kerr scores (p<0.05). CONCLUSIONS: Significantly increased levels of IL-6 were detected in peripheral blood and aortic tissues of untreated patients. IL-6 might be a sensitive biomarker to assess disease activity and could be critical in the immunopathogenesis of TAK.

A population-based study examining calcaneus quantitative ultrasound and its optimal cut-points to discriminate osteoporotic fractures among 9352 Chinese women and men.

CONTEXT: No generally accepted thresholds for quantitative ultrasound (QUS) parameters to screen individuals at high risk of osteoporotic fractures have been defined. OBJECTIVE: We sought to define appropriate cutoff points for osteoporotic fractures of calcaneus ultrasound according to participants' prevalent osteoporotic fractures. DESIGN AND SETTING: This was a cross-sectional, population-based study conducted in Shanghai, China. PARTICIPANTS: A total of 9352 Chinese women and men aged 40 and older were studied. MAIN OUTCOME MEASURES: We measured calcaneus QUS (Achilles Express, GE Lunar) values and their relationships with osteoporotic fractures. RESULTS: A prevalence of 14.9 and 12.2% of osteoporotic fractures was found in the women and men (P<0.001), respectively. Subjects with osteoporotic fractures had significantly lower QUS values than those without (P<0.001). One sd decline in the stiffness index (SI)-derived T-score was associated with a high risk of nonvertebral fracture [odds ratio (OR)=1.50; 95% confidence interval (CI), 1.39-1.62; P<0.001], clinical vertebral fracture (OR=1.49; 95% CI, 1.18-1.90; P<0.01), and multi-fractures (OR=1.98; 95% CI, 1.63-2.40; P<0.001). The receiver operating characteristic analysis showed that QUS could differentiate osteoporotic fractures in postmenopausal women and men, but not in premenopausal women. The optimal cutoff points for the SI-derived T-score to detect a high risk of nonvertebral fractures, clinical vertebral fractures, and multi-fractures were -1.25, -1.55, and -1.80 in postmenopausal women, respectively, and -1.30, -1.90, and -2.00 in males, respectively. CONCLUSIONS: As a screening tool, the SI-derived T-score obtained from the Achilles QUS device for a postmenopausal woman or man that is less than -1.25 and -1.30, respectively, may indicate an increased risk of osteoporotic fractures and should be further evaluated by central DXA.