7,8-didehydrocimigenol from Cimicifugae rhizoma inhibits TNF-α-induced VCAM-1 but not ICAM-1expression through upregulation of PPAR-γ in human endothelial cells

PPARγ in Atherosclerotic Endothelial Dysfunction: Regulatory Compounds and PTMs

The formation of atherosclerotic plaques is one of the main sources of cardiovascular disease. In addition to known risk factors such as dyslipidemia, diabetes, obesity, and hypertension, endothelial dysfunction has been shown to play a key role in the formation and progression of atherosclerosis. Peroxisome proliferator-activated receptor-gamma (PPARγ), a transcription factor belonging to the steroid superfamily, is expressed in the aorta and plays a critical role in protecting endothelial function. It thereby serves as a target for treating both diabetes and atherosclerosis. Although many studies have examined endothelial cell disorders in atherosclerosis, the role of PPARγ in endothelial dysfunction is still not well understood. In this review, we summarize the possible mechanisms of action behind PPARγ regulatory compounds and post-translational modifications (PTMs) of PPARγ in the control of endothelial function. We also explore the potential use of endothelial PPARγ-targeted agents in the prevention and treatment of atherosclerosis.

Naturally occurring cell adhesion inhibitors

This paper reviews naturally occurring cell adhesion inhibitors derived from a plant, microbial and marine origin. Plant-derived inhibitors are classified according to a type of structure. Microbially and marine-derived inhibitors were described according to age. In addition, effects of inhibitors on cell proliferation and that of standards on cell adhesion are listed as much as possible.

Human apolipoprotein A-I exerts a prophylactic effect on high-fat diet-induced atherosclerosis via inflammation inhibition in a rabbit model

Apolipoprotein A-I (apoA-I) is the major functional protein fraction of high-density lipoprotein. The prophylactic effect and mechanism of human apoA-I on atherosclerosis (AS) were investigated in a high-fat diet-induced AS rabbit model. The rabbits were injected with apoA-I once a week while fed high-fat diet for 20 weeks. Our results showed that apoA-I could raise the serum level of high-density lipoprotein-cholesterol and reduce those of lipid total cholesterol, triglyceride, and low-density lipoprotein-cholesterol in AS rabbits. Decreased aortic plaque area and aortic injury degree were also observed by Oil Red O staining and HE staining in apoA-I-treated high-fat diet-induced AS rabbits. Further study elucidated that apoA-I could down-regulate the expression of some inflammatory mediators including intercellular adhesion molecule type 1, vascular adhesion molecule-1 (VCAM-1), monocyte chemoattractant protein-1, tumor necrosis factor-α, interleukin-6 (IL-6), and C-reactive protein in serum and aorta of AS rabbits. In addition, real-time quantitative RT-PCR analyses showed that the apoA-I infusions decreased the mRNA levels of two pro-inflammatory molecules, i.e. nuclear factor kappa B (NF-κB) and cyclooxygenase-2 (COX-2), in aorta of AS rabbits, which was associated with a concomitant reduction in endothelial VCAM-1 and IL-6 mRNA transcription. Together, our results support the atheroprotective and prophylactic role of apoA-I in vivo, and this activity may be correlated with its anti-inflammatory effect.

Evaluation of the effects of Cimicifugae Rhizoma on the morphology and viability of mesenchymal stem cells

Cimicifugae Rhizoma is a traditional herbal medicine used to treat various diseases in Korea, China and Japan. Cimicifugae Rhizoma is primarily derived from Cimicifuga heracleifolia Komarov or Cimicifuga foetida Linnaeus. Cimicifugae Rhizoma has been used as an anti-inflammatory, analgesic and antipyretic remedy. The present study was performed to evaluate the extracts of Cimicifugae Rhizoma on the morphology and viability of human stem cells derived from gingiva. Stem cells derived from gingiva were grown in the presence of Cimicifugae Rhizoma at final concentrations that ranged from 0.001 to 1,000 µg/ml. The morphology of the cells was viewed under an inverted microscope and the analysis of cell proliferation was performed using a Cell Counting kit-8 (CCK-8) assay on days 1, 3, 5 and 7. Under an optical microscope, the control cells exhibited a spindle-shaped, fibroblast-like morphology. The shapes of the cells in the groups treated with 0.001, 0.01, 0.1, 1 and 10 µg/ml Cimicifugae Rhizoma were similar to the shapes in the control group. Significant alterations in morphology were noted in the 100 and 1,000 µg/ml groups when compared with the control group. The cells in the 100 and 1,000 µg/ml groups were rounder, and fewer cells were present. The cultures that were grown in the presence of Cimicifugae Rhizoma at a concentration of 0.001 µg/ml on day 1 had an increased CCK-8 value. The cultures grown in the presence of Cimicifugae Rhizoma at a concentration of 10 µg/ml on day 7 had a reduced CCK-8 value. Within the limits of this study, Cimicifugae Rhizoma influenced the viability of stem cells derived from the gingiva, and its direct application onto oral tissues may have adverse effects at high concentrations. The concentration and application time of Cimicifugae Rhizoma should be meticulously controlled to obtain optimal results.

Flavonoids from Citrus unshiu Marc. inhibit cancer cell adhesion to endothelial cells by selective inhibition of VCAM-1

Citrus fruits have been used as edible fruit and a component of traditional medicine for various diseases including cancer since ancient times. Herein, we investigated the anticancer activity of flavonoids of Citrus unshiu Marc. (FCM) focusing on anti-metastatic effects. We prepared FCM and performed experiments using MDA-MB-231 human breast cancer cells. FCM inhibited TNF-induced cancer cell adhesion to human umbilical vein endothelial cells (HUVECs) without showing any toxicity. FCM inhibited the expression of VCAM-1, but not of ICAM-1, on MDA-MB-231 cells as well as HUVECs. FCM inhibited protein kinase C (PKC) phosphorylation, but not Akt phosphorylation. FCM also inhibited cancer cell invasion in a dose-dependent manner, but not MMP-9 expression. In conclusion, this study suggested that FCM inhibits TNF-induced cancer cell adhesion to HUVECs by inhibiting VCAM-1 through inhibition of PKC, providing evidence that FCM have anti-metastatic activity by inhibiting adhesion molecules and invasion on human breast cancer cells.

Vinorelbine-induced oxidative injury in human endothelial cells mediated by AMPK/PKC/NADPH/NF-κB pathways

Vinorelbine tartrate (VNR), a semi-synthetic vinca alkaloid acquired from vinblastine, has extensively been used as an anticancer agent. However, VNR-induced oxidative damage may cause several side effects, such as venous irritation, vascular pain, and necrotizing vasculitis, thereby repressing clinical treatment efficiency. The molecular mechanisms underlying the induced oxidative stress in endothelial cells are still largely unknown. This study was designed to test the hypothesis that VNR induces oxidative injury through modulation of AMP-activated protein kinase (AMPK) and possible mechanisms were then explored. Human umbilical vein endothelial cells (HUVECs) were treated with VNR (5-0.625 μM) to produce oxidative damage. The VNR-mediated AMPK, PKC, and NADPH oxidase expressions were investigated by western blotting. Furthermore, several oxidative stress-induced oxidative damage markers as well as pro-inflammatory responses were also investigated. VNR treatment resulted in dephosphorylation of AMPK, which in turn led to an activation of NADPH oxidase by PKC; however, the phenomena were repressed by AICAR (an agonist of AMPK). Furthermore, VNR suppressed Akt/eNOS and enhanced p38 mitogen-activated protein kinase (MAPK), which in turn activated the NF-κB pathway. Furthermore, VNR facilitated several pro-inflammatory events, such as the adherence of monocytic THP-1 cells to HUVECs, pro-inflammatory cytokines release, and overexpression of adhesion molecular. Our results highlight a possible molecular mechanism for VNR-mediated endothelial dysfunction.

HO-1 Induced by Cilostazol Protects Against TNF-α-associated Cytotoxicity via a PPAR-γ-dependent Pathway in Human Endothelial Cells

A large body of evidence has indicated that induction of endogenous antioxidative proteins seems to be a reasonable strategy for delaying the progression of cell injury. In our previous study, cilostazol was found to increase the expression of the antioxidant enzyme heme oxygenase-1 (HO-1) in synovial cells. Thus, the present study was undertaken to examine whether cilostazol is able to counteract tumor necrosis factor-α (TNF-α)-induced cell death in endothelial cells via the induction of HO-1 expression. We exposed human umbilical vein endothelial cells (HUVECs) to TNF-α (50 ng/ml), with or without cilostazol (10 µM). Pretreatment with cilostazol markedly reduced TNF-α-induced viability loss in the HUVECs, which was reversed by zinc protoporphyrine IX (ZnPP), an inhibitor of HO-1. Moreover, cilostazol increased HO-1 protein and mRNA expression. Cilostazol-induced HO-1 induction was markedly attenuated not only by ZnPP but also by copper-protoporphyrin IX (CuPP). In an assay measuring peroxisome proliferator-activated receptor-γ (PPAR-γ) transcription activity, cilostazol directly increased PPAR-γ transcriptional activity which was completely abolished by HO-1 inhibitor. Furthermore, increased PPAR-γ activity by cilostazol and rosiglitazone was completely abolished in cells transfected with HO-1 siRNA. Taken together, these results indicate that cilostazol up-regulates HO-1 and protects cells against TNF-α-induced endothelial cytotoxicity via a PPAR-γ-dependent pathway.