Osteopontin: A major player on hypertension-induced vascular remodeling

A Pivotal Role for AP-1-Mediated Osteopontin Expression in the Increased Migration of Vascular Smooth Muscle Cells Stimulated With HMGB1

Migration of vascular smooth muscle cells (VSMCs) plays an essential role in the development of vascular remodeling in the injured vasculatures. Previous studies have identified high-mobility group box 1 (HMGB1) as a principal effector mediating vascular remodeling; however, the mechanisms involved have not been fully elucidated. Thus, this study investigated the role of HMGB1 on VSMC migration and the underlying molecular mechanisms involved. VSMCs were ex plant cultured using rat thoracic aorta, and the cellular migration was measured using wound-healing assay. Osteopontin (OPN) mRNA and protein were determined by reverse transcription polymerase chain reaction (RT-PCR) and Western blot, respectively. The OPN promoter was cloned into pGL3 basic to generate a pLuc-OPN-2284 construct. Migration of VSMCs stimulated with HMGB1 (100ng/ml) was markedly increased, which was significantly attenuated in cells pretreated with MPIIIB10 (100–300ng/ml), a neutralizing monoclonal antibody for OPN as well as in cells deficient of OPN. In VSMCs stimulated with HMGB1, OPN mRNA and protein levels were significantly increased in association with an increased promotor activity of OPN gene. Putative-binding sites for activator protein 1 (AP-1) and CCAAT/enhancer-binding protein beta (C/EBPβ) in the indicated promoter region were suggested by TF Search, and the HMGB1-induced expression of OPN was markedly attenuated in cells transfected with siRNA for AP-1. VSMC stimulated with HMGB1 also showed an increased expression of AP-1. Results of this study suggest a pivotal role for AP-1-induced OPN expression in VSMC migration induced by HMGB1. Thus, the AP-1-OPN signaling axis in VSMC might serve as a potential therapeutic target for vascular remodeling in the injured vasculatures.

Preliminary observation of chemokine expression in patients with Stanford type A aortic dissection

Stanford type A Aortic dissection (TAAD) is a deadly cardiovascular disease but the relationship between inflammatory cytokines and disease pathogenesis is still unclear. Observation of the changes of different chemokines may help to explore the etiology of TAAD much further. Clinical data was collected from TAAD patients (TAAD group) and healthy controls (HC group) in our institute between October 2013 and December 2014. Blood sample was harvested from each subject of two groups. The expression levels of eighty chemokines were examined by protein array technology. Then we tested the expressions of macrophage inflammatory protein 1β (MIP-1β), epithelial neutrophil activating peptide 78 (ENA-78), interleukin 16 (IL-16), interferon inducible protein 10 (IP-10), and FMS-like tyrosine kinase 3 (Flt-3) ligand by using luminex technology. Osteopontin (OPN) and monocyte chemotaxis protein (MCP) levels were analyzed by ELISA kits. The mean age of TAAD group is 49.9 ± 11.2 and 48.7 ± 9.9 in HC group, respectively. 76.0% of TAAD patients and 72.0% of healthy controls were male. MIP-1β and ENA-78 expression in TAAD group were significantly lower than that in HC group, while significant increasing IL-16 level was found. Plasma levels of OPN in TAAD group increased remarkably compared with HC group, but MCP-1 and MCP-2 expression significantly decreased. No correlation was shown between serum CRP levels and plasma level of these cytokines by using Spearman analysis. ROC analysis showed that OPN could be indicators for TAAD diagnosis with sensitivity of 0.92 and specificity of 0.99. Our results provide a reasonable way to focus on the chemokines in understanding the pathogenesis of human TAAD.

A multi-stage association study of plasma cytokines identifies osteopontin as a biomarker for acute coronary syndrome risk and severity

Cytokines play a critical role in the pathogenesis and development of cardiovascular diseases. However, data linking cytokines to risk and severity of acute coronary syndrome (ACS) are still limited. We measured plasma profile of 280 cytokines using a quantitative protein microarray in 12 ACS patients and 16 healthy controls, and identified 15 differentially expressed cytokines for ACS. Osteopontin, chemokine ligand 23, brain derived neurotrophic factor and C-reactive protein (CRP) were further validated using immunoassay in two independent case-control studies with a total of 210 ACS patients and 210 controls. We further examined their relations with incident ACS among 318 case-control pairs nested within the Dongfeng-Tongji cohort, and found plasma osteopontin and CRP concentrations were associated with incident ACS, and the multivariable-adjusted odds ratio (95% confidence interval) was 1.29 (1.06-1.57) per 1-SD increase for osteopontin and 1.30 (1.02-1.66) for CRP, respectively. Higher levels of circulating osteopontin were also correlated with higher severity of ACS, and earlier ACS onset time. Adding osteopontin alone or in combination with CRP modestly improved the predictive ability of ACS beyond the Framingham risk scores. Our findings suggested that osteopontin might be a biomarker for incident ACS, using osteopontin adds moderately to traditional cardiovascular risk factors.

Osteopontin in the Pathogenesis of Aortic Dissection by the Enhancement of MMP Expressions

The pathogenesis of aortic dissection (AD) is unclear. The aim of this study was to explore the relationship between osteopontin (OPN) and AD. Fifty AD patients were enrolled; 29 had hypertension with AD (H-AD) and 21 no hypertension with HD (NH-AD). Twenty-five healthy controls (NH-C) and 14 patients with hypertension (H-C) were also enrolled. Serum and aortic wall OPN levels were determined. Human vascular muscle cells (HVSMC) were stimulated by both low (1 μg/mL) and high (5 μg/mL) concentrations of OPN and cell proliferation as well as apoptosis was measured. Transforming growth factor-β (TGF-β), matrix metalloproteinase 1 (MMP-1), MMP-2, MMP-9, TIMP-1, and TIMP-2 gene expressions by HVSMC were measured and Akt, IκB, Smad1/5/8 and Erk1/2 signaling pathways were detected. Our results showed that AD patients demonstrated significantly higher levels of serum and local OPN expressions compared to healthy controls. In those with hypertension, the serum concentrations of OPN were increased compared to those without hypertension. In in vitro culture, a high dose of OPN stimulation promoted the proliferation of HVSMC but did not affect cell apoptosis. Both concentrations of OPN enhanced MMP-2 gene expression and its activity in HVSMC. Moreover, Akt and IκB signaling pathways were significantly activated after OPN stimulation while the Smad1/5/8 and Erk1/2 signaling pathways were not changed. The addition of an IκB inhibitor significantly abrogated MMP-2 gene expression. Our data show that OPN may participate in the pathogenesis of AD by the enhancement of MMP-2 expression.

A Novel α-Calcitonin Gene-Related Peptide Analogue Protects Against End-Organ Damage in Experimental Hypertension, Cardiac Hypertrophy, and Heart Failure

Supplemental Digital Content is available in the text.

Research into the therapeutic potential of α-calcitonin gene–related peptide (α-CGRP) has been limited because of its peptide nature and short half-life. Here, we evaluate whether a novel potent and long-lasting (t_½ ≥7 hours) acylated α-CGRP analogue (αAnalogue) could alleviate and reverse cardiovascular disease in 2 distinct murine models of hypertension and heart failure in vivo.

α-Iso-Cubebene Inhibits PDGF-Induced Vascular Smooth Muscle Cell Proliferation by Suppressing Osteopontin Expression

α-Iso-cubebene (ICB) is a dibenzocyclooctadiene lignin contained in Schisandra chinensis (SC), a well-known medicinal herb that ameliorates cardiovascular symptoms. Thus, we examined the effect of ICB on vascular smooth muscle cell (VSMC) proliferation, a key feature of diverse vascular diseases. When VSMCs primary cultured from rat thoracic aorta were stimulated with PDGF (1-10 ng/ml), cell proliferation and osteopontin (OPN) expression were concomitantly up-regulated, but these effects were attenuated when cells were treated with MPIIIB10, a neutralizing monoclonal antibody for OPN. In aortic tissues exposed to PDGF, sprouting VSMC numbers increased, which was attenuated in tissues from OPN-deficient mice. Furthermore, VSMC proliferation and OPN expression induced by PDGF were attenuated dose-dependently by ICB (10 or 30 μg/ml). Reporter assays conducted using OPN promoter-luciferase constructs showed that the promoter region 538-234 bp of the transcription start site was responsible for transcriptional activity enhancement by PDGF, which was significantly inhibited by ICB. Putative binding sites for AP-1 and C/EBPβ in the indicated promoter region were suggested by TF Search, and increased binding of AP-1 and C/EBPβ in PDGF-treated VSMCs was demonstrated using a ChIP assay. The increased bindings of AP-1 and C/EBPβ into OPN promoter were attenuated by ICB. Moreover, the PDGF-induced expression of OPN was markedly attenuated in VSMCs transfected with siRNA for AP-1 and C/EBPβ. These results indicate that ICB inhibit VSMC proliferation by inhibiting the AP-1 and C/EBPβ signaling pathways and thus downregulating OPN expression.