Epigallocatechin-3-gallate inhibits angiotensin II and interleukin-6-induced C-reactive protein production in macrophages.

BACKGROUND: Consumption of green tea has been associated with health benefits against multiple diseases including cardiovascular diseases. However, the action mechanisms of green tea and its major ingredient epigallocatechin-3-gallate (EGCG) against cardiovascular diseases are still unclear. Emerging evidence has suggested a common role for C-reactive protein (CRP) in the pathogenesis of inflammation and atherosclerosis. Therefore, the effect of EGCG on angiotensin II (Ang II)- and interleukin-6 (IL-6)-induced CRP production in U937 macrophages and the possible mechanisms were observed. METHODS: U937 macrophages were cultured, and Ang II and IL-6 were used as stimulants for generation of CRP. U937 macrophages were preincubated with EGCG at 1, 3, 10 µM for 1 h prior to the stimulation. mRNA expression and protein level were determined by RT-PCR and ELISA, respectively. ROS production was observed by a fluorescence microscope. RESULTS: Pretreatment of macrophages with EGCG prior to the stimulation concentration-dependently inhibited Ang II- and IL-6-induced expression of CRP both in protein and mRNA levels. Meanwhile, EGCG reduced Ang II- and IL-6-stimulated generation of ROS in macrophages. CONCLUSION: EGCG is able to inhibit Ang II- and IL-6-stimulated CRP expression in macrophages to produce an anti-inflammation by interfering with ROS generation. The finding is helpful to update understanding of anti-atherosclerotic effects of EGCG.

Rosiglitazone inhibits angiotensin II-induced C-reactive protein production in human aortic endothelial cells through regulating AT(1)-ROS-MAPK signal pathway.

OBJECTIVE: Atherosclerosis is an inflammatory disease. As an inflammatory molecule, C-reactive protein (CRP) plays a direct role in atherogenesis. Our previous study confirmed that angiotensin II (Ang II) is capable of inducing CRP generation in human aortic endothelial cells (HAECs). The present study observed the effect of rosiglitazone on Ang II-induced CRP expression in HAECs and molecular mechanisms. METHODS: HAECs were cultured, and Ang II (10(-6) M) was used as a stimulant for the generation of CRP and reactive oxygen species (ROS). HAECs were preincubated with rosiglitazone at 1, 10, 100 µM for 18 h prior to the stimulation. mRNA and protein expressions were identified by reverse transcription polymerase chain reaction and Western blot, respectively. ROS production was observed by a fluorescence microscope. RESULTS: Pretreatment of HAECs with rosiglitazone prior to Ang II stimulation markedly downregulated Ang II-induced mRNA and protein expressions of CRP (maximal inhibition of 55.2 and 99.1 %, P < 0.001 vs. Ang II alone) and AT(1) (maximal inhibition of 66.4 and 90.5 %, P < 0.001 vs. Ang II alone) in a concentration-dependent manner, inhibited Ang II-stimulated ROS production (P < 0.01 vs. Ang II alone), and attenuated Ang II-induced phosphorylation of ERK1/2 and JNK (P < 0.001 vs. Ang II alone). Meanwhile, AT(1) receptor blocker losartan also reduced Ang II-stimulated ROS generation in HAECs (P < 0.001 vs. Ang II alone). CONCLUSIONS: Rosiglitazone at the concentrations used in the present experiment is able to inhibit Ang II-induced CRP generation in HAECs by regulating AT(1)-ROS-MAPK signal pathway. These results strengthen our understanding of the anti-inflammatory and anti-atherosclerotic effects of rosiglitazone.

[Mechanism of Dahuang Zhechong pill against atherosclerosis induced by balloon angioplasty in rabbits].

OBJECTIVE: To study the mechanism of Dahuang Zhechong pill (DHZCP) against atherosclerosis induced by balloon angioplasty in rabbits. METHODS: Atherosclerosis model was established by the combination of balloon angioplasty-induced endothelial injury and high cholesterol feeding in rabbit. Male New Zealand rabbits were divided into six groups randomly: normal control, sham, model, positive control and two doses of DHZCP-treated groups. Rabbits in DHZCP-treated groups were intragastrically administered 0.9 and 1.8 g/kg DHZCP for 60 days respectively,and rabbits in positive control group were given 0.5 g/kg Danshen. MDA, NO levels and SOD activity in serum, and MPO activity in the vascular wall were determined with spectrophotometry. Expressions of proliferating cell nuclear antigen (PCNA) and BCL-2 in the vascular wall were detected by SP immuohistochemical technique. RESULTS: Compared with the model group, DHZCP significantly reduced serum MDA level and MPO activity in the vascular wall, increased serum NO level and SOD activity,and inhibited PCNA and BCL-2 expressions in the vascular wall. CONCLUSION: DHZCP inhibits the formation and development of atherosclerosis through anti-oxidative action, protecting endothelium from injury,inhibiting proliferation and promoting apoptosis of vascular smooth muscle cells.

[Progress in signal transduction pathways mediating effects of angiotensin II in endothelial cells].

Angiotensin II (Ang II) not only mediates the effects of vasoconstriction and blood pressure regulation, but is also implicated in inflammation, endothelial dysfunction, atherosclerosis, hypertension and congestive heart failure. Ang 1I activates pathways of MAPK, NADPH and ROS, non-receptor tyrosine kinases and receptor tyrosine kinases via AT1 receptor to produce various effects involved in regulation of endothelial functions, endothelial dysfunction and vascular inflammation response.

[Protection of vascular endothelial cells from ox-LDL induced injury by protocatechualdehyde].

OBJECTIVE: To observe the protective effects of protocatechualdehyde on the human umbilical vein endothelial cells (CRL-1730) induced injury by ox-LDL. METHODS: The CRL-1730 were induced injury by ox-LDL, and then treated with protocatechualdehydes for 24 hours. The cytoactive of CRL-1730 was assessed by colorimetry of MTr, the NO level and NOS activity in the cell culture fluid were observed by colorimetry, and the expression of CD40 protein was determined by flow cytometry. RESULTS: Compared with the ox-LDL group, protocatechualdehyde increased,the number of CRL-1730 and the level of NO and NOS in cell culture fluid. Besides, protocatechualdehyde decreased the expression of CD40 protein, which was increased by ox-LDL. CONCLUSION: Protocatechualdehyde has protective effect on the CRL-1730 induced injury by ox-LDL and its mechanism of action may be related to the CD40/CD40L pathway.

Fenofibrate inhibits tumor necrosis factor-alpha-induced expression of CD40 and matrix metalloproteinase in human vascular endothelial cells.

OBJECTIVE: To investigate the regulatory effects of fenofibrate on TNF-alpha-induced CD40 expression and matrix metalloproteinase (MMP) activity in human vascular endothelial cells (HUVECs). METHODS: Quantitative RT-PCR and flow cytometry were employed to evaluate the effect of fenofibrate on TNF-alpha-induced CD40 mRNA and cell surface CD40 expression in HUVECs, and gelatin zymography was used to determine the effect of fenofibrate on the gelatinolytic activities of MMP-2 and MMP-9 in TNF-alpha-stimulated HUVECs. RESULTS: Fenofibrate at the concentrations of 5x10(-5), 1x10(-4) and 2x10(-4) mol/L significantly reduced TNF-alpha-induced increment of CD40 mRNA and cell surface CD40 expressions (P<0.01), with the maximal inhibition achieved at the concentration of 1x10(-4) mol/L. Fenofibrate at 2x10(-4) mol/L did not further decrease CD40 expression induced by TNF-alpha. Fenofibrate significantly inhibited the stimulatory effect of TNF-alpha on MMP-2 and MMP-9 activities in HUVECs. CONCLUSION: Fenofibrate reduces TNF-alpha-induced increment of CD40 expression and MMP-2 and MMP-9 activities in HUVECs.

Protective effect of tanshinone IIA on human umbilical vein endothelial cell injured by hydrogen peroxide and its mechanism.

Tanshinone IIA (Tan IIA) is isolated from Salvia miltiorrhiza, the root of which is widely used as a traditional Chinese medicine to treat atherosclerosis. The aim of the present study was to evaluate the putative protective effect of Tan IIA in a human umbilical vein endothelial cell line (ECV-304) injured by hydrogen peroxide in vitro and the mechanism of its protection. The percentage of cell viability was evaluated by 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyl tetrazolium bromide (MTT) assay. The endothelial cell apoptosis and expression of cluster of differentiation 40 (CD40) were detected by flow cytometric analysis. Preincubation with Tan IIA significantly increased the viability of ECV-304 cell injured by hydrogen peroxide, which was accompanied with the increased nitric oxide level and superoxide dismutase activity in a dose-dependent manner. Moreover, cell apoptosis and CD40 expression were decreased in a dose-dependent manner. In conclusion, our data suggests that Tan IIA protects ECV-304 cell damage induced by hydrogen peroxide through its anti-oxidant effect and CD40 anti-inflammatory approach.