Inhibition of angiogenesis, fibrosis and thrombosis by tetramethylpyrazine: mechanisms contributing to the SDF-1/CXCR4 axis.

Xiaoxiao Cai,Pei Chen,Jing Zhang,Kaijing Li,Jian Ge,Ying Yang,Keming Yu,Lei Xia,Jing Zhuang,Xueke Pan,Zhao Chen,Huan Hu,Michael Bader

doi:10.1371/journal.pone.0088176

Abstract

BackgroundTetramethylpyrazine (TMP) is one of the active ingredients extracted from the Chinese herb Chuanxiong, which has been used to treat cerebrovascular and cardiovascular diseases, pulmonary diseases and cancer. However, the molecular mechanisms underlying the actions of TMP have not been fully elucidated. In a previous study we showed that TMP-mediated glioma suppression and neural protection involves the inhibition of CXCR4 expression. The SDF-1/CXCR4 axis plays a fundamental role in many physiological and pathological processes. In this study, we further investigated whether the regulation of the SDF-1/CXCR4 pathway is also involved in the TMP-mediated inhibition of neovascularization or fibrosis and improvement of microcirculation.Methodology/Principal FindingsUsing a scratch-wound assay, we demonstrated that TMP significantly suppressed the migration and tubule formation of the human umbilical vein endothelial cell line ECV304 in vitro. The expression of CXCR4 in ECV304 cells is notably down-regulated after TMP treatment. In addition, TMP significantly suppresses corneal neovascularization in a rat model of corneal alkali burn injury. The expression of CXCR4 on days 1, 3 and 7 post-injury was determined through RT-PCR analysis. Consistent with our hypotheses, the expression of CXCR4 in the rat cornea is significantly increased with alkali burn and dramatically down-regulated with TMP treatment. Moreover, TMP treatment significantly attenuates bleomycin-induced rat pulmonary fibrosis, while immunofluorescence shows a notably decreased amount of CXCR4-positive cells in the TMP-treated group. Furthermore, TMP significantly down-regulates the expression of CXCR4 in platelets, lymphocytes and red blood cells. Whole-blood viscosity and platelet aggregation in rats are significantly decreased by TMP treatment.ConclusionsThese results show that TMP exerts potent effects in inhibiting neovascularization, fibrosis and thrombosis under pathological conditions; thus, the underlying mechanism of TMP might partially contribute to the down-regulation of CXCR4.

Highlights

Chuanxiong (Ligusticum wallichi Franchat) was first described in the Chinese traditional medicine book Shennong Bencaojing, written in 200 BC
These results show that TMP exerts potent effects in inhibiting neovascularization, fibrosis and thrombosis under pathological conditions; the underlying mechanism of TMP might partially contribute to the down-regulation of CXCR4
TMP blocks angiogenesis in vitro Because the SDF-1/CXCR4 interaction plays a pivotal role in angiogenesis, we first examined CXCR4 expression in ECV304 cells after treatment with TMP at different concentrations in vitro (0, 50, 100, 200 mM)

Summary

Introduction

Chuanxiong (Ligusticum wallichi Franchat) was first described in the Chinese traditional medicine book Shennong Bencaojing (a guide to Traditional Chinese Medicine), written in 200 BC. Chuanxiong is used in many clinical treatments, including those for ischemia, cerebral infarction and degenerative diseases of the central nervous system (Alzheimer’s disease, Parkinson’s disease and multiple sclerosis); myocardial and pulmonary fibrosis; and tumors, with mild side effects [1,2,3,4,5,6]. This herbal supplement can significantly attenuate platelet aggregation and thrombus formation, which improves whole-blood viscosity [7,8]. We further investigated whether the regulation of the SDF-1/CXCR4 pathway is involved in the TMP-mediated inhibition of neovascularization or fibrosis and improvement of microcirculation

Methods

Results

Discussion

Conclusion