Gun Woo Son

Eriodictyol Protects Endothelial Cells against Oxidative Stress-Induced Cell Death through Modulating ERK/Nrf2/ARE-Dependent Heme Oxygenase-1 Expression

The pathophysiology of cardiovascular diseases is complex and may involve oxidative stress-related pathways. Eriodictyol is a flavonoid present in citrus fruits that demonstrates anti-inflammatory, anti-cancer, neurotrophic, and antioxidant effects in a range of pathophysiological conditions including vascular diseases. Because oxidative stress plays a key role in the pathogenesis of cardiovascular disease, the present study was designed to verify whether eriodictyol has therapeutic potential. Upregulation of heme oxygenase-1 (HO-1), a phase II detoxifying enzyme, in endothelial cells is considered to be helpful in cardiovascular disease. In this study, human umbilical vein endothelial cells (HUVECs) treated with eriodictyol showed the upregulation of HO-1 through extracellular-regulated kinase (ERK)/nuclear factor erythroid 2-related factor 2 (Nrf2)/antioxidant response element (ARE) signaling pathways. Further, eriodictyol treatment provided protection against hydrogen peroxide-provoked cell death. This protective effect was eliminated by treatment with a specific inhibitor of HO-1 and RNA interference-mediated knockdown of HO-1 expression. These data demonstrate that eriodictyol induces ERK/Nrf2/ARE-mediated HO-1 upregulation in human endothelial cells, which is directly associated with its vascular protection against oxidative stress-related endothelial injury, and propose that targeting the upregulation of HO-1 is a promising approach for therapeutic intervention in cardiovascular disease.

Microarray analysis of gene expression in 3-methylcholanthrene-treated human endothelial cells

Cigarette smoke has many toxic components that can lead to the disruption of various cellular processes. Increase in oxidative stress due to cigarette smoke causes production of reactive oxygen species, which induce vascular disease. 3-methylcholanthrene (3MC) is an environmental contaminant derived from the incomplete combustion of cigarette smoke and is one of the major polycyclic aromatic hydrocarbons. 3MC activates the aryl hydrocarbon receptor and contributes to carcinogenesis and vascular disease. The present study investigated gene expression in 3MC-treated human umbilical vein endothelial cells by microarray gene expression profiling. We found 1,279 and 717 genes with altered gene expression within 24 h of 100 nM and 1 μM 3MC treatment, respectively; these genes were distributed into distinct functional groups. Some of the genes including ICAM1, PTGS2, APOL3, and GPX-1, were related to cardiovascular disease. Our results support the hypothesis that 3MC-stimulated gene expression in endothelial cells may play a role in the development of cardiovascular disease.

Analysis of miRNA expression profiling in melatonin-exposured endothelial cells

Melatonin is produced from tryptophan and is secreted by the pineal gland in periods of darkness; it has cytoprotective effects in endothelial cells. It has been reported that melatonin mediates the regulation of gene expression at the post-transcriptional level through its effect on miRNA expression. miRNAs are small non-coding RNAs that silence gene expression, regulate most cellular processes involved in development, and maintain cell functions. In this study, we confirmed the expression of 136 and 154 miRNAs when endothelial cells were treated with melatonin concentrations of 100 μM and 1 mM, respectively. We investigated anti-correlations in miRNA-target-mRNA pairs, and we identified a total of 13 and 44 mRNAs showing an expression difference of >1.5 fold, following exposure to melatonin concentrations of 100 μM and 1 mM, respectively. These profiling data revealed a variety of biological effects, including cell death, apoptosis and proliferation, via a Gene Ontology analysis of biological processes. The results of this study suggest that melatonin may regulate miRNA and gene expression and may have a cytoprotective effect on endothelial cells.

Effects of Eicosapentaenoic Acid on the Cytoprotection Through Nrf2-Mediated Heme Oxygenase-1 in Human Endothelial Cells

Abstract: Consumption of omega-3 polyunsaturated fatty acid, particularly eicosapentaenoic acid (EPA), is associated with a significant reduction in the risk of developing cardiovascular disease. The aim of this study was to investigate whether heme oxygenase-1 (HO-1) induction contributes to the cytoprotective effects of EPA in endothelial cells threatened with oxidative damage. In this study, we investigated the effect of EPA on the induction of HO-1 by NF-E2-related factor 2 (Nrf2) in human umbilical vein endothelial cells. In cells treated with low concentrations of EPA (10–25 &mgr;M), HO-1 expression increased in a time- and concentration-dependent manner. Additionally, EPA treatment increased Nrf2 nuclear translocation and antioxidant response element activity, leading to the upregulation of HO-1 expression. Furthermore, treatment with EPA reduced hydrogen peroxide (H2O2)-induced cell death. The reduction in cell death was reversed by treatment with zinc protoporphyrin, an inhibitor of HO-1, indicating that HO-1 contributed to the protective effect of EPA. These data suggest that EPA protects against H2O2-induced oxidative stress in endothelial cells by activating Nrf2 and inducting HO-1 expression.

β2 integrins (CD11/18) are essential for the chemosensory adhesion and migration of polymorphonuclear leukocytes on bacterial cellulose.

Bacterial cellulose (BC) has been studied widely for applications in biomedical materials such as prosthetic artificial blood vessels owing to its unique characteristics, which include nontoxicity and nonimmunogenicity as compared with synthetic biopolymers such as expanded polytetrafluorethylene (ePTFE). However, to date, studies on the relative effect of leukocytes on BC as a prosthetic vascular graft are insufficient. Polymorphonuclear leukocytes (PMN) play a pivotal role in early-phase immune response to bacterial or periprosthetic infection. PMN recruitment at sites of infection or inflammation mediated by various integrins such as β2 integrin family (CD11/CD18 family). Therefore, we discuss our investigations into the mechanisms by which β2 integrins-mediated chemosensory adhesion and migration of PMN on the vascular graft surface, BC. Our results show that CD11b/CD18 components mainly mediate PMN adherence on BC. CD11b/CD18 displays weak coordination with the other two α subunits (CD11a and CD11c). Furthermore, it was found that the β subunit (CD18) plays a critical role in both the adhesion and migration of N-formylmethionyl-leucyl-phenylalanine (fMLP)-stimulated PMN on BC. The activity of CD18 contrasts with that of the individual α subunits. Among these, only CD11b displayed inhibition of PMN migration on BC surfaces.

Crotonaldehyde-exposed macrophages induce heme oxygenase-1 expression as an adaptive mechanism

Cigarette smoke represents one of the most significant risk factors for the progression of vascular disease. Exposure to cigarette smoke induces oxidative stress in the vascular system and results in vascular dysfunction. Crotonaldehyde, a highly reactive α, β-unsaturated aldehyde, is a foremost compound of cigarette smoke and a product of endogenous lipid peroxidation. Heme oxygenase-1 (HO-1) expression plays an essential role in cellular defense against environmental insults and represents an adaptive response. Here, we showed the effects of crotonaldehyde on the induction of HO-1 expression in RAW 264.7 macrophages. Crotonaldehyde treatment resulted in significantly increased phosphorylation of p38 mitogen-activated protein kinase (MAPK) and nuclear translocation of nuclear factor erythroid 2-related factor 2 (Nrf2). Furthermore, treatment with zinc protoporphyrin (ZnPP; the specific HO-1 inhibitor) markedly augmented the death of crotonaldehyde-treated macrophages. In summary, these results highlight the role of the HO-1 upregulation through p38 MAPK-Nrf2 activation in the adaptive response to crotonaldehyde in macrophages.

Profiling of gene expression using microarray in acrolein-treated human pulmonary fibroblasts

Pulmonary fibroblasts are essential for the integrity of alveolar structures and to restore lung tissue after injury. They are also important for inflammatory responses through their ability to attract leukocytes. Cigarette smoke has many harmful components, and causes various pulmonary and lung diseases including chronic obstructive pulmonary disease (COPD), chronic bronchitis, and emphysema. Acrolein (ACR), one of the compounds in cigarette smoke, induces inflammatory cytokines and the generation of DNA adducts, resulting in dysfunction of respiratory cells such as pulmonary fibroblasts. In this study, we examined the expression of genes in ACR-treated human pulmonary fibroblasts by microarray profiling. We identified 2,378 and 312 genes that were differentially expressed within 6 h of treatment with 10 μM or 25 μM ACR, respectively. These genes were classified as being involved in many biological processes including apoptosis, immune responses, cell cycle, and signal transduction. Some genes, including HSPA1B, HMOX1, CASP3, PRDX3, and ANXA1, are related to COPD. These results support the hypothesis that ACR may increase cytotoxicity and tissue injury in respiratory cells and may attribute to the development of pulmonary disease.

Identification and characterization of MicroRNAs in acrolein-stimulated endothelial cells: Implications for vascular disease

MicroRNAs (miRNAs) have been implicated in the regulation of physiological and pathophysiological processes such as vascular disease. Analysis of miRNA expression profiles in vascular disease provides new insights into the possible mechanisms underlying and therapeutic targets of disease. Acrolein is a highly reactive component of cigarette smoke, which has been implicated in the development of vascular disease. In this study, we investigated whether miRNAs play a role in the modulation of various gene expression responses to acrolein in human endothelial cells. We analyzed whole-genome miRNA and mRNA expression and found that acrolein induced differential expression of 151 miRNAs in endothelial cells. We further classified a number of target genes of the differentially expressed miRNAs. Among the differentially expressed miRNAs, miR-342-3p and 422a were upregulated, and the expression levels demonstrated a high inverse correlation with their targets, the vascular disease- related genes CLDN1 and PON1. Thus, integrating specific patterns of miRNA and mRNA levels may improve the diagnosis of vascular diseases induced by exposure to environmental pollutants such as acrolein.

Integrative analysis of miRNA and mRNA profiles in response to myricetin in human endothelial cells

MicroRNAs (miRNAs) are associated with a diverse range of biological processes, human diseases, and metabolic disorders. Myricetin, which is the most abundant polyphenol class in the human diet, has antioxidative, antiapoptotic, and anti-inflammatory properties. The present study aimed to evaluate whether myricetin modulates miRNA expression. Using microarray analysis, we investigated miRNA expression in human endothelial cells treated with 25 µM and 100 µM of myricetin for 24 hours, and found that 101 and 191 miRNAs, respectively, were differential expressed by at least 1.5-fold. Based on several bioinformatic systems, we also identified signatures of the potential biological processes and signaling pathways that are influenced by dysregulated miRNAs. Therefore, integrating specific patterns of miRNA and mRNA levels may suggest a new mechanism of action of myricetin.

Functional screening of altered microRNA expression in 3-methylcholanthrene-treated human umbilical vein endothelial cells

The common environmental contaminant 3-methylcholanthrene (3MC) is found in cigarette smoke and is produced by incomplete combustion of fat, wood and coal. 3MC is a poly aromatic hydrocarbon that interacts with an aryl hydrocarbon receptor and causes inflammation and induces vascular dysfunction; 3MC forms the DNA adducts structure and regulates cell cycle, which increase oxidative stress and inflammation. MicroRNAs (miRNAs) are non-coding RNA molecules that negatively regulate gene expression; these RNAs also play a role in cellular and molecular responses to toxicants, and can post-transcriptionally regulate gene expression. In this study, we examined whether miRNAs affect the regulation of gene expression in 3MC-treated human umbilical vein endothelial cells (HUVECs). We carried out pair-wise correlation analysis and identified 131 and 116 miRNAs with altered expression upon treatment of HUVECs with 100 nM and 1 μM 3MC, respectively. Furthermore, we identified 188 and 85 mRNAs with altered expression upon treatment with 100 nM and 1 μM 3MC; we subsequently analyzed their anti-correlations. The Gene Ontology (GO) enrichment analysis on the altered expression of miRNA-related genes displayed significant enrichment for genes involved in certain biological processes. Specifically, our results suggest that changes in miRNA expression caused by 3MC treatment are associated with inflammation of endothelial cells and may play a role in cardiovascular disease.