Inhibition of Angiogenesis, Fibrosis and Thrombosis by Tetramethylpyrazine: Mechanisms Contributing to the SDF-1/CXCR4 Axis

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.

Tetramethylpyrazine Attenuates Transdifferentiation of TGF-β2–Treated Human Tenon's Fibroblasts

“…16,17 To test this, we measured whether TMP (200 lM) affected transit of serum-starved, TGF-b2-exposed HTFs through the cell cycle. We found that, whereas in the presence of TGF-b2 (10 ng/mL), 7.387 6 1.225% of cells were in Sphase, TMP treatment counteracted the effect of TGF-b2, such that the percentage of cells in S-phase dropped to 4.27 6 0.517% (Figs.…”

“…These findings agree with previous studies of trabecular meshwork cells and ECV 304 cells. 16,24 In addition, it is well established that the actin cytoskeleton is associated with the vimentin filament system, which is involved in regulating cell shape and tissue homeostasis. 25 By immunofluorescence staining assay, more pronounced vimentin expression was observed in TGF-b2-treated HTFs, but counteracted by TMP treatment (vimentin content: con, 26.92 6 6.67; TMP, 19.11 6 3.48; TGF-b2, 77.52 6 9.39; TGF-b2 þ TMP, 42.67 6 8.38, *P < 0.01, #P < 0.01, Figs.…”

“…[14][15][16][17] In vivo and in vitro studies indicate that TMP protects the liver from CCl4-induced fibrogenesis by modulating the NLRP3 inflammasome pathway 18 ; and our previous studies in rats demonstrated that TMP protects against pulmonary bleomycininduced fibrosis by modulating the SDF-1/CXCR4 axis. 16 Studies in the liver suggest that TMP likely exerts antifibrotic effects by inhibiting Smad2/3 expression; and in hypoxic myocardial cells, protective doses of TMP downregulated the p38 MAPK pathway. 19,20 Accumulating evidence suggests that TMP may have therapeutic potential as a complementary therapy for various ocular diseases, including vascular retinopathy, corneal neovascularization, optic neuropathy, and glaucoma.…”

“…19,20 Accumulating evidence suggests that TMP may have therapeutic potential as a complementary therapy for various ocular diseases, including vascular retinopathy, corneal neovascularization, optic neuropathy, and glaucoma. 16,[21][22][23] In particular, our latest investigation implicated TMP in attenuation of TGF-b-induced pathologic changes in trabecular meshwork cells, showing that it inhibits cytoskeleton remodeling and ECM accumulation through the SDF/CXCR4 axis. 24 Prompted by these previous reports, we sought to characterize the bioactivity of TMP and its underlying mechanism.…”

A Potential Role of SDF-1/CXCR4 Chemotactic Pathway in Wound Healing and Hypertrophic Scar Formation

“…Other antagonists of the SDF-1/CXCR4 have also been shown to have attenuating effects on fibrosis in other FPD. These include plerixafor (AMD3100), 4F-benzoyl-TN14003 (T140) and tetramethylpyrazine (TMP) [23,51,52] .…”