Selective inhibition of vascular smooth muscle cell proliferation by coptisine isolated from Coptis rhizoma, one of the crude drugs composing Kampo medicines Unsei-in

Coptisine inhibits neointimal hyperplasia through attenuating Pak1/Pak2 signaling in vascular smooth muscle cells without retardation of re-endothelialization

BACKGROUND AND AIMS

Vascular injury-induced endothelium-denudation and profound vascular smooth muscle cells (VSMCs) proliferation and dis-regulated apoptosis lead to post-angioplasty restenosis. Coptisine (CTS), an isoquinoline alkaloid, has multiple beneficial effects on the cardiovascular system. Recent studies identified it selectively inhibits VSMCs proliferation. However, its effects on neointimal hyperplasia, re-endothelialization, and the underlying mechanisms are still unclear.

METHODS

Cell viability was assayed by 3-[4,5-dimethylthiazole-2-yl]-2,5-diphenyltetrazolium bromide (MTT) and cell counting kit-8 (CCK-8). Cell proliferation and apoptosis were measured by flow cytometry and immunofluorescence of Ki67 and TUNEL. Quantitative phosphoproteomics (QPP) was employed to screen CTS-responsive phosphor-sites in the key regulators of cell proliferation and apoptosis. Neointimal hyperplasia was induced by balloon injury of rat left carotid artery (LCA). Adenoviral gene transfer was conducted in both cultured cells and LCA. Re-endothelialization was evaluated by Evan's blue staining of LCA.

RESULTS

1) CTS had strong anti-proliferative and pro-apoptotic effects in cultured rat VSMCs, with the EC50 4∼10-folds lower than that in endothelial cells (ECs). 2) Rats administered with CTS, either locally to LCA's periadventitial space or orally, demonstrated a potently inhibited balloon injury-induced neointimal hyperplasia, but had no delaying effect on re-endothelialization. 3) The QPP results revealed that the phosphorylation levels of Pak1S144/S203, Pak2S20/S197, Erk1T202/Y204, Erk2T185/Y187, and BadS136 were significantly decreased in VSMCs by CTS. 4) Adenoviral expression of phosphomimetic mutants Pak1D144/D203/Pak2D20/D197 enhanced Pak1/2 activities, stimulated the downstream pErk1T202/Y204/pErk2T185/Y187/pErk3S189/pBadS136, attenuated CTS-mediated inhibition of VSMCs proliferation and promotion of apoptosis in vitro, and potentiated neointimal hyperplasia in vivo. 5) Adenoviral expression of phosphoresistant mutants Pak1A144/A203/Pak2A20/A197 inactivated Pak1/2 and totally simulated the inhibitory effects of CTS on platelet-derived growth factor (PDGF)-stimulated VSMCs proliferation and PDGF-inhibited apoptosis in vitro and neointimal hyperplasia in vivo. 6) LCA injury significantly enhanced the endogenous phosphorylation levels of all but pBadS136. CTS markedly attenuated all the enhanced levels.

CONCLUSIONS

These results indicate that CTS is a promising medicine for prevention of post-angioplasty restenosis without adverse impact on re-endothelialization. CTS-directed suppression of pPak1S144/S203/pPak2S20/S197 and the subsequent effects on downstream pErk1T202/Y204/pErk2T185/Y187/pErk3S189 and pBadS136 underline its mechanisms of inhibition of VSMCs proliferation and stimulation of apoptosis. Therefore, the phosphor-sites of Pak1S144/S203/Pak2S20/S197 constitute a potential drug-screening target for fighting neointimal hyperplasia restenosis.

Liposomes for effective drug delivery to the ocular posterior chamber

Background

Age-related macular degeneration (AMD) is a leading cause of severe visual deficits and blindness. Meanwhile, there is convincing evidence implicating oxidative stress, inflammation, and neovascularization in the onset and progression of AMD. Several studies have identified berberine hydrochloride and chrysophanol as potential treatments for ocular diseases based on their antioxidative, antiangiogenic, and anti-inflammatory effects. Unfortunately, their poor stability and bioavailability have limited their application. In order to overcome these disadvantages, we prepared a compound liposome system that can entrap these drugs simultaneously using the third polyamidoamine dendrimer (PAMAM G3.0) as a carrier.

Results

PAMAM G3.0-coated compound liposomes exhibited appreciable cellular permeability in human corneal epithelial cells and enhanced bio-adhesion on rabbit corneal epithelium. Moreover, coated liposomes greatly improved BBH bioavailability. Further, coated liposomes exhibited obviously protective effects in human retinal pigment epithelial cells and rat retinas after photooxidative retinal injury. Finally, administration of P-CBLs showed no sign of side effects on ocular surface structure in rabbits model.

Conclusions

The PAMAM G3.0-liposome system thus displayed a potential use for treating various ocular diseases.

Electronic supplementary material

The online version of this article (10.1186/s12951-019-0498-7) contains supplementary material, which is available to authorized users.

Plant-Derived Products for Treatment of Vascular Intima Hyperplasia Selectively Inhibit Vascular Smooth Muscle Cell Functions

Natural products are used widely for preventing intimal hyperplasia (IH), a common cardiovascular disease. Four different cells initiate and progress IH, namely, vascular smooth muscle, adventitial and endothelial cells, and circulation or bone marrow-derived cells. Vascular smooth muscle cells (VSMCs) play a critical role in initiation and development of intimal thickening and formation of neointimal hyperplasia. In this review, we describe the different originating cells involved in vascular IH and emphasize the effect of different natural products on inhibiting abnormal cellular functions, such as VSMC proliferation and migration. We further present a classification for the different natural products like phenols, flavonoids, terpenes, and alkaloids that suppress VSMC growth. Abnormal VSMC physiology involves disturbance in MAPKs, PI3K/AKT, JAK-STAT, FAK, and NF-κB signal pathways. Most of the natural isolate studies have revealed G1/S phase of cell cycle arrest, decreased ROS production, induced cell apoptosis, restrained migration, and downregulated collagen deposition. It is necessary to screen optimal drugs from natural sources that preferentially inhibit VSMC rather than vascular endothelial cell growth to prevent early IH, restenosis following graft implantation, and atherosclerotic diseases.

Coptisine-induced inhibition of Helicobacter pylori: elucidation of specific mechanisms by probing urease active site and its maturation process

In this study, we examined the anti-Helicobactor pylori effects of the main protoberberine-type alkaloids in Rhizoma Coptidis. Coptisine exerted varying antibacterial and bactericidal effects against three standard H. pylori strains and eleven clinical isolates, including four drug-resistant strains, with minimum inhibitory concentrations ranging from 25 to 50 μg/mL and minimal bactericidal concentrations ranging from 37.5 to 125 μg/mL. Coptisine’s anti-H. pylori effects derived from specific inhibition of urease in vivo. In vitro, coptisine inactivated urease in a concentration-dependent manner through slow-binding inhibition and involved binding to the urease active site sulfhydryl group. Coptisine inhibition of H. pylori urease (HPU) was mixed type, while inhibition of jack bean urease was non-competitive. Importantly, coptisine also inhibited HPU by binding to its nickel metallocentre. Besides, coptisine interfered with urease maturation by inhibiting activity of prototypical urease accessory protein UreG and formation of UreG dimers and by promoting dissociation of nickel from UreG dimers. These findings demonstrate that coptisine inhibits urease activity by targeting its active site and inhibiting its maturation, thereby effectively inhibiting H. pylori. Coptisine may thus be an effective anti-H. pylori agent.

Emodin as a selective proliferative inhibitor of vascular smooth muscle cells versus endothelial cells suppress arterial intima formation

A well-known natural anthraquinone "Emodin", has been proven to inhibit the proliferation of vascular smooth muscle cells (VSMCs). But the anti-proliferative effects of emodin on both VSMCs versus vascular endothelial cells (VECs) are still largely unknown. Herein, a comparative study for the evaluation of anti-proliferation effects of emodin on human VSMCs and VECs was designed. Various methodologies including MTS, EdU assay, FACS analysis, qRT-PCR and mitochondrial fluorescent probes were used for detecting cell viabilities, DNA synthesis rate, cell cycle, proliferation genes expression levels and mitochondrial activities, respectively. In addition, carotid arteries balloon injury was performed to evaluate the effects of emodin on intima hyperplasia (IH) and re-endothelialization. The emodin showed a dose-dependent (0.05 to 5 μM) inhibition of hVSMCs proliferation was quiet higher than hVECs in vitro. Conditioned culture media with a range of emodin concentrations (2.5, and 5 μM) reduced CDK1, Ki67, and E2F-1 gene expression, along with inhibition of mitochondrial activities in both hVSMCs and hVECs cells, while former remained highly sensitive. Emodin (10 mg/kg) was injected intraperitoneally for 2 weeks, and had obvious alleviation in an endothelial denudation induced-IH formation and limited interfere-endothelialization in injured arteries in vivo. Emodin preferentially inhibited hVSMCs proliferation but not the hVECs in vitro and had limited influence on the re-endothelialization of later in a rat artery endothelial denudation model. It is concluded that emodin will provide a promising approach for efficient prevention of blood vessel restenosis.

Rh(iii)-catalyzed synthesis of tetracyclic isoquinolinium salts via C–H activation and [4+2] annulation of 1-phenyl-3,4-dihydroisoquinolines and alkynes in ethanol

An efficient and convenient method to construct tetracyclic isoquinolinium salts via [Cp*RhCl₂]₂ catalyzed C–H activation and [4 + 2] annulation reactions in ethanol is described. This reaction is very fast and highly efficient in the green solvent ethanol. The reaction works with a broad substrate scope affording the products in good to excellent yields in a short time. Moreover, a ratio of S/C up to 10 000 could be achieved with gram scale synthesis.

An efficient method to construct tetracyclic isoquinolinium salts via C–H activation and [4 + 2] annulation reactions in ethanol is described.

Pharmacokinetics and tissue distribution of coptisine in rats after oral administration by liquid chromatography-mass spectrometry

Coptisine, one of the main components isolated from Coptidis rhizoma, has been reported to have many beneficial pharmacological effects including anti-inflammatory, anti-hypercholesterolemia, neuroprotective and cardioprotective properties. However, to date the information related to the in vivo pharmacokinetics (PK) of coptisine is very limited. The purposes of our study are to establish a fast and sensitive quantification method of coptisine using liquid chromatography-mass spectrometry (LC-MS) and evaluate the PK profile of coptisine in rats. The calibration curve for coptisine was linear from 0.78 to 50 ng/mL. After single-dose oral administration of coptisine, the mean peak plasma concentration values for groups treated with 30, 75 and 150 mg/kg doses ranged from 44.15 to 66.89 ng/mL, and the mean area under the concentration-time curve values ranged from 63.24 to 87.97 mg/L h. The absolute bioavailability was calculated to range from 1.87 to 0.52%. Coptisine remained in all analyzed samples at low concentrations after oral administration of 30 mg/kg.

Neuroprotective mechanism of BNG-1 against focal cerebral ischemia: a neuroimaging and neurotrophin study

BNG-1 is a herb complex used in traditional Chinese medicine to treat stroke. In this study, we attempted to identify the neuroprotective mechanism of BNG-1 by using neuroimaging and neurotrophin analyses of a stroke animal model. Rats were treated with either saline or BNG-1 for 7 d after 60-min middle cerebral artery occlusion by filament model. The temporal change of magnetic resonance (MR) imaging of brain was studied using a 7 Tesla MR imaging (MRI) system and the temporal expressions of neurotrophin-3 (NT-3), brain-derived neurotrophic factor (BDNF), and nerve growth factor (NGF) in brain were analyzed before operation and at 4 h, 2 d, and 7 d after operation. Compared with the saline group, the BNG-1 group exhibited a smaller infarction volume in the cerebral cortex in T2 image from as early as 4 h to 7 d, less edema in the cortex in diffusion weighted image from 2 to 7 d, earlier reduction of postischemic hyperperfusion in both the cortex and striatum in perfusion image at 4 h, and earlier normalization of the ischemic pattern in the striatum in susceptibility weighted image at 2 d. NT-3 and BDNF levels were higher in the BNG-1 group than the saline group at 7 d. We concluded that the protective effect of BNG-1 against cerebral ischemic injury might act through improving cerebral hemodynamics and recovering neurotrophin generation.

Amitozyn impairs chromosome segregation and induces apoptosis via mitotic checkpoint activation

Amitozyn (Am) is a semi-synthetic drug produced by the alkylation of major celandine (Chelidonium majus L.) alkaloids with the organophosphorous compound N,N'N'-triethylenethiophosphoramide (ThioTEPA). We show here that the treatment of living cells with Am reversibly perturbs the microtubule cytoskeleton, provoking a dose-dependent cell arrest in the M phase. Am changed the dynamics of tubulin polymerization in vitro, promoted the appearance of aberrant mitotic phenotypes in HeLa cells and induced apoptosis by the activation of caspase-9, caspase-3 and PARP, without inducing DNA breaks. Am treatment of HeLa cells induced changes in the phosphorylation of the growth suppressor pRb that coincided with maximum mitotic index. The dose-dependent and reversible anti-proliferative effect of Am was observed in several transformed cell lines. Importantly, the drug was also efficient against multidrug-resistant, paclitaxel-resistant or p53-deficient cells. Our results thus open the way to further pre-clinical evaluation of Am.

Analysis of the mechanisms underlying the vasorelaxant action of coptisine in rat aortic rings

The aim of the present study was to evaluate the vasorelaxant effects of coptisine and its possible mechanisms in isolated rat aortic rings. Coptisine was evaluated on isolated rat aortic rings precontracted with norepinephrine (NE) and KCl. The mechanisms were evaluated in the presence or absence of specific pharmacological inhibitors. Coptisine (1 ~ 200 μM) relaxed NE (1 μM) or KCl (60 mM) induced sustained contraction with pEC(50) values of 4.49 ± 0.48 and 4.85 ± 0.57 in a concentration dependent manner. Pretreatment with coptisine (10, 50 or 100 μM) also inhibited concentration-response curves to NE and KCl. The vasorelaxant effect of coptisine was attenuated significantly by endothelium removal, and incubation with Nω-nitro-L-arginine methyl ester (L-NAME, 100 μM), methylene blue (10 μM) and indomethacin (5 μM) partially reduced the vasorelaxant effect of coptisine. In endothelium-denuded rings, the vasorelaxant effect of coptisine was reduced significantly by 4-aminopyridine (4-AP, 100 μM), but not glibenclamide (10 μM) ortetraethylammonium (TEA, 5 mM). Coptisine also reduced NE-induced transient contraction in Ca(2+)-free solution, and inhibited contraction induced by increasing external calcium in Ca(2+)-free medium plus 60 mM KCl. It was concluded that coptisine induced both endothelium-dependent and -independent relaxation in rat aortic rings. The NO-cGMP mediated pathway may be involved in the endothelium-dependent relaxation and in the activation of voltage-dependent K(+) channels, contributing in part to the endothelium-independent relaxation bycoptisine. Coptisine also blocks extracellular Ca(2+) influx by interacting with both voltage- and receptor-operated Ca(2+) channels.

Differential gene expression in rat vascular smooth muscle cells following treatment with coptisine exerts a selective antiproliferative effect

It is known that coptisine (1), an isoquinoline alkaloid, selectively inhibits proliferation of rat primary vascular smooth muscle cells (VSMCs). In the present study, the characteristics of its antiproliferative effect on several types of smooth muscle-like cells were investigated and compared to the effects of berberine (2) and palmatine (3). To clarify further the mechanism underlying the VSMC-selective antiproliferative effect of 1, the genes responsible were investigated by determining which mRNAs showed expression regulated by 1. Coptisine (1) showed a greater antiproliferative effect on smooth muscle cells derived from the aorta than on those derived from other organs. Analysis of the mRNA expression revealed that 1 upregulated two genes, growth arrest and DNA-damage-inducible alpha (Gadd45a) and response gene to complement32 (Rgc32). Both genes remained unchanged in 3Y1 fibroblasts and were not affected by 2 and 3. Coptisine (1) was found to induce the mRNA of the Gadd45a and Rgc32 genes, specifically in VSMC. Activation of these genes by 1 may mediate inhibition of cell-cycle progression. However, as these genes are commonly expressed in various cell types, a selective target for 1 activity is likely to exist upstream of these genes.

Selective regulation of multidrug resistance protein in vascular smooth muscle cells by the isoquinoline alkaloid coptisine

When the biological activites of hydrophobic drugs or xenobiotics are studied, it is important to clarify their effects on expression and function of multidrug resistance (MDR) protein. We therefore evaluated the effects of coptisine on MDR in comparison with the structurally related isoquinoline alkaloids berberine and palmatine. To achieve this, we investigated the effects of the three alkaloids on the expression and function of P-glycoprotein/MDR1, MDR1 gene products, in vascular smooth muscle cells (VSMCs). In A10 cells (a rat VSMC line), coptisine upregulated the mRNAs of Mdr1a and Mdr1b, rodent homologues of human MDR1, and these effects were completely abrogated by actinomycin D. Coptisine also induced Mdr1a/1b protein expression and enhanced the efflux of rhodamine 123 from A10 cells. In contrast, berberine and palmatine slightly upregulated the mRNAs of Mdr1a and Mdr1b, but failed to induce Mdr1a/1b protein expression or stimulate rhodamine 123 efflux. To clarify whether these effects occurred in other cells, the effects of the three alkaloids on Mdr1a/1b function were examined in 3Y1, dRLh-84 and B16 cells. Coptisine and berberine enhanced rhodamine 123 efflux in all three cell types, while palmatine inhibited it, based on the finding that palmatine efficiently activated the Mdr1a ATPase activity as a good substrate for Mdr1a. Therefore, the three isoquinoline alkaloids regulated MDR differently in cell type-specific manners. In particular, only coptisine induced Mdr1a/1b in A10 cells and stimulated rhodamine 123 efflux. Taken together, coptisine appears to exert VSMC-selective effects on Mdr1a/1b induction in contrast to berberine and palmatine.

Berberine inhibits platelet-derived growth factor-induced growth and migration partly through an AMPK-dependent pathway in vascular smooth muscle cells

Platelet-derived growth factor (PDGF) is released from vascular smooth muscle cells (VSMCs), endothelial cells, or macrophages after percutaneous coronary intervention and is related with neointimal proliferation and restenosis. Berberine is a well-known component of the Chinese herb medicine Huanglian (Coptis chinensis), and is capable of inhibiting growth and endogenous PDGF synthesis in VSMCs after in vitro mechanical injury. We analyzed the effects of berberine on VSMC growth, migration, and signaling events after exogenous PDGF stimulation in vitro in order to mimic a post-angioplasty PDGF shedding condition. Pretreatment of VSMCs with berberine inhibited PDGF-induced proliferation. Berberine significantly suppressed PDGF-stimulated Cyclin D1/D3 and Cyclin-dependent kinase (Cdk) gene expression. Moreover, berberine increased the activity of AMP-activated protein kinase (AMPK), which led to phosphorylation activation of p53 and increased protein levels of the Cdk inhibitor p21(Cip1). Compound C, an AMPK inhibitor, partly but significantly attenuated berberine-elicited growth inhibition. In addition, stimulation of VSMCs with PDGF led to a transient increase in GTP-bound, active form of Ras, Cdc42 and Rac1, as well as VSMC migration. However, pretreatment with berberine significantly inhibited PDGF-induced Ras, Cdc42 and Rac1 activation and cell migration. Co-treatment with farnesyl pyrophosphate and geranylgeranyl pyrophosphate drastically reversed berberine-mediated anti-proliferative and migratory effects in VSMCs. Based on these findings, we conclude that berberine inhibited PDGF-induced VSMC growth via activation of AMPK/p53/p21(Cip1) signaling while inactivating Ras/Rac1/Cyclin D/Cdks and suppressing PDGF-stimulated migration via inhibition of Rac1 and Cdc42. These observations offer a molecular explanation for the anti-proliferative and anti-migratory properties of berberine.

Double blockade of cell cycle progression by coptisine in vascular smooth muscle cells

Coptisine, an isoquinoline alkaloid isolated from rhizome of Coptis japonica, inhibits proliferation of vascular smooth muscle cells (VSMCs). The aim of this study was to evaluate the action of coptisine, along with berberine (a structurally similar isoquinoline alkaloid), on progression of the cell cycle in VSMCs. Coptisine displayed antiproliferative action against VSMCs by blocking the cell cycle at G(1) and G(2)/M phases. The G(1) block was shown by inhibition of [(3)H]thymidine incorporation into VSMCs at coptisine concentrations higher than 15 microM. The mechanism underlying the G(1) arrest involved a decrease in cyclin D1 protein, although cyclin E, A, and B were not affected by coptisine treatment. The selective reduction in cyclin D1 protein was mainly attributable to accelerated proteolysis via proteasome-dependent pathway, since it was inhibited by a proteasome inhibitor, N-carbobenzoxy-L-leucinyl-L-leucinyl-L-norleucinal (MG132) and further the mRNA level of cyclin D1, protein synthesis, and mitogen-activated protein kinase (MAPK) activity remained unaltered. The mechanism underlying the G(2)/M arrest involved partial inhibition of tubulin polymerization, which was apparent at coptisine concentration of 3 microM. Berberine arrested the cell cycle at G(1) phase via a mechanism identical with coptisine, but did not cause block at G(2)/M phase. The results demonstrate that a small difference in the structure between isoquinoline alkaloids produces a big difference in activity, and that coptisine has a unique double action in arresting the cell cycle of VSMCs.