Jung-Suk Choi

(-)Epigallocatechin gallate hampers collagen destruction and collagenase activation in ultraviolet-B-irradiated human dermal fibroblasts : Involvement of mitogen-activated protein kinase

Ultraviolet (UV) irradiation leads to distinct changes in skin connective tissues by degradation of collagen, which is a major structural component in the extracellular matrix most likely mediated by matrix metalloproteinases (MMP), collagenases. These changes in collagenous skin tissues have been suggested to be causes of the skin wrinkling observed in premature aging of the skin. This study mimicked the action of environmental ultraviolet on skin and investigated whether (-)epigallocatechin gallate (EGCG), a bioactive catechin component of green tea, mechanistically inhibited activation of MMP-1, MMP-8, and MMP-13 and destruction of collagen in UV-B irradiated human dermal fibroblasts by modulating cellular signaling pathways. Cell viability was moderately decreased by > or = 30% in human dermal fibroblasts treated with 100 mJ/cm2 UV-B, accompanying a substantial generation of reactive oxygen species evidenced by DCF staining. Western blot analysis and immunocytochemical staining revealed that EGCG markedly suppressed collagen degradation enhanced in UV-B-exposed human dermal fibroblast. Pre-treatment of fibroblasts with EGCG also inhibited UV-B-induced production of collagenases, MMP-1, MMP-8 and MMP-13, in a dose-dependent manner. In addition, EGCG rapidly and substantially hampered UV-B irradiation-induced activation of ASK-1 and phosphorylation of MAPK, JNK, p38 MAPK, and ERK1/2, in dermal fibroblasts. These results demonstrate that EGCG has abilities to hamper UV-B-induced collagenolytic MMP production via interfering with the MAPK-responsive pathways. Therefore, EGCG may be a potential agent for the prevention and treatment of skin photoaging.

Dietary compound ellagic acid alleviates skin wrinkle and inflammation induced by UV-B irradiation

Please cite this paper as: Dietary compound ellagic acid alleviates skin wrinkle and inflammation induced by UV‐B irradiation. Experimental Dermatology 2010; 19: e182–e190.

Bog blueberry anthocyanins alleviate photoaging in ultraviolet-B irradiation-induced human dermal fibroblasts.

Fruits of bog blueberry (Vaccinium uliginosum L.) are rich in anthocyanins that contribute pigmentation. Anthocyanins have received much attention as agents with potentials preventing chronic diseases. This study investigated the capacity of anthocyanin-rich extract from bog blueberry (ATH-BBe) to inhibit photoaging in UV-B-irradiated human dermal fibroblasts. BBe anthocyanins were detected as cyanidin-3-glucoside, petunidin-3-glucoside, malvidin-3-glucoside, and delphinidin3-glucoside. ATH-BBe attenuated UV-B-induced toxicity accompanying reactive oxygen species (ROS) production and the resultant DNA damage responsible for activation of p53 and Bad. Preincubation of ATH-BBe markedly suppressed collagen degradation via blunting production of collagenolytic matrix metalloproteinases (MMP). Additionally, ATH-BBe enhanced UV-B-downregulated procollagen expression at transcriptional levels. We next attempted to explore whether ATH-BBe mitigated the MMP-promoted collagen degradation through blocking nuclear factor kappaB (NF-kappaB) activation and MAPK-signaling cascades. UV-B radiation enhanced nuclear translocation of NF-kappaB, which was reversed by treatment with ATH-BBe. The UV-B irradiation rapidly activated apoptosis signal-regulating kinase-1 (ASK-1)-signaling cascades of JNK and p38 mitogen-activated protein kinase (p38 MAPK), whereas ATH-BBe hampered phosphorylation of c-Jun, p53, and signal transducers and activators of transcription-1 (STAT-1) linked to these MAPK signaling pathways. ATH-BBe diminished UV-B augmented-release of inflammatory interleukin (IL)-6 and IL-8. These results demonstrate that ATH-BBe dampens UV-B-triggered collagen destruction and inflammatory responses through modulating NF-kappaB-responsive and MAPK-dependent pathways. Therefore, anthocyanins from edible bog blueberry may be protective against UV-induced skin photoaging.

Licorice isoliquiritigenin dampens angiogenic activity via inhibition of MAPK-responsive signaling pathways leading to induction of matrix metalloproteinases

The aberrant expression of matrix metalloproteinases (MMPs) has been implicated in matrix degradation leading to angiogenesis. This study examined the inhibitory effects of isoliquiritigenin (ISL) on phorbol myristate acetate (PMA)-induced MMP production and its tissue inhibitor of MMP (TIMP) in endothelial cells. No induction of either necrotic or apoptotic cell death was observed in response to a treatment with ISL at <or=25 microM. ISL dose-dependently suppressed PMA-induced expression and activity of MMP-2 and membrane type 1-MMP at >or=1 microM while diminishing the elevated MMP-2 transcript level. In addition, ISL inhibited PMA-triggered migration and tube formation in a dose-dependent manner. ISL further increased the TIMP production up-regulated by PMA with a biphasic effect on TIMP-2 expression. This study further attempted to investigate whether a c-Jun N-terminal kinase (JNK)- or p38 mitogen-activated protein kinase (MAPK)-responsive mechanism was responsible for the MMP production and whether ISL disturbed these signaling pathways. PMA stimulated signaling of JNK and p38 MAPK, which was dampened by >or=10 microM ISL. These results demonstrate that ISL blocked JNK- or p38 MAPK-responsive pathways leading to direct MMP activation of PMA-exposed endothelial cells. Therefore, the ISL inhibition of MMP may boost a therapeutic efficacy during angiogenesis.

Attenuation of monocyte adhesion and oxidised LDL uptake in luteolin-treated human endothelial cells exposed to oxidised LDL.

Oxidative modification of LDL is causally involved in the development of atherosclerosis and occurs in vivo in the blood as well as within the vascular wall. The present study attempted to explore whether polyphenolic flavonoids influence monocyte-endothelium interaction and lectin-like oxidised LDL receptor 1 (LOX-1) expression involved in the early development of atherosclerosis. The flavones luteolin and apigenin inhibited THP-1 cell adhesion onto oxidised LDL-activated human umbilical vein endothelial cells (HUVEC), while the flavanols of (-)epigallocatechin gallate and (+)catechin, the flavonols of quercetin and rutin, and the flavanones of naringin, naringenin, hesperidin and hesperetin did not have such effects. Consistently, Western blot analysis revealed that the flavones at 25 microM dramatically and significantly abolished HUVEC expression of vascular cell adhesion molecule-1 and E-selectin evidently enhanced by oxidised LDL; these inhibitory effects were exerted by drastically down regulating mRNA levels of these cell adhesion molecules. In addition, quercetin and luteolin significantly attenuated expression of LOX-1 protein up regulated in oxidised LDL-activated HUVEC with a fall in transcriptional mRNA levels of LOX-1. In addition, quercetin and luteolin clearly blunted oxidised LDL uptake by HUVEC treated with oxidised LDL. The results demonstrate that the flavones luteolin and apigenin as well as quercetin were effective in the different initial steps of atherosclerosis process by inhibiting oxidised LDL-induced endothelial monocyte adhesion and/or oxidised LDL uptake. Therefore, certain flavonoids qualify as anti-atherogenic agents in LDL systems, which may have implications for strategies attenuating endothelial dysfunction-related atherosclerosis.

Blockade of Cytokine-Induced Endothelial Cell Adhesion Molecule Expression by Licorice Isoliquiritigenin Through NF-κB Signal Disruption

Numerous polyphenolic compounds have been found to inhibit adhesion and migration of leukocytes to sites of inflammation that are partly regulated by the expression of cell adhesion molecules (CAM) such as vascular cell adhesion molecule-1 (VCAM-1), E-selectin, and platelet endothelial cell adhesion molecule-1 (PECAM-1). Licorice root extracts have been used in traditional Chinese, Tibetan, and Indian medicine for the treatment of pulmonary diseases and inflammatory processes. Expression of CAM proteins was examined in human umbilical vein endothelial cells (HUVEC) treated with a licorice component (isoliquiritigenin, 18β-glycyrrhetinic acid, glycyrrhizin, formononetin, or ononin) and exposed to TNF-α. The involvement of NF-κB in the transcriptional control of CAM proteins was assessed by degradation of IκBα and nuclear translocation of NF-κB using Western blotting techniques and immunocytochemical staining. At nontoxic ≥10 μM, isoliquiritigenin blocked the induction of VCAM-1 and E-selectin on activated HUVEC and markedly interfered with THP-1 monocyte adhesion to TNF-α-activated endothelial cells. Isoliquiritigenin abolished TNF-α-induced mRNA accumulation of VCAM-1 and E-selectin. Additionally, immunocytochemical staining revealed that isoliquiritigenin attenuated PECAM-1 expression induced by TNF-α. In contrast, other components recognized in licorice, 18β-glycyrrhetinic acid, glycyrrhizin, formononetin, and ononin did not down-regulate the expression of VCAM-1 and/or PECAM-1 activated by TNF-α, implying that these components are inactive in modulating adhesion of leukocytes to stimulated endothelial cells. Isoliquiritigenin downregulated CAM proteins in TNF-α-activated HUVEC at the transcriptional levels by blocking degradation of IκBα and nuclear translocation of NF-κB. These results demonstrate that the induction blockade of VCAM-1 and E-selectin by isoliquiritigenin was directly mediated by its interference with the CAM mRNA transcription through NF-κB-dependent mechanisms under inflammatory conditions.

Blockade of Oxidized LDL-Triggered Endothelial Apoptosis by Quercetin and Rutin through Differential Signaling Pathways Involving JAK2

Oxidized LDL is highly atherogenic, as it stimulates foam cell formation and promotes inflammatory and thrombotic processes. The present study elucidated whether the antioxidants quercetin and its rutinoside rutin exert antiapoptosis in endothelial cells exposed to Cu(2+)-oxidized LDL. Quercetin and rutin inhibited the oxidized LDL-induced endothelial toxicity at nontoxic doses of </=25 muM with an inhibition of intracellular oxidant accumulation. These effects accompanied disappearance of apoptotic bodies and suppression of caspase-3 activation. Additionally, condensed nuclei vanished in oxidized LDL-exposed cells treated with quercetin and rutin. This study further explored whether such effects were achieved by redox manipulation via JAK2-STAT3-responsive death/survival signaling pathways involving multiple MAPK. Unlike quercetin, rutin blocked the activation of oxidized LDL-induced JNK and p38 MAPK as well as the upstream ASK1 phosphorylation. Quercetin dose-dependently attenuated the JAK2 phosphorylation evoked by oxidized LDL, whereas rutin abolished the JAK signaling accompanying nuclear transactivation of STAT3 and enhanced the JAK activity-inhibiting SOCS3 expression. Conversely, oxidized LDL-induced IL-6 release was minimal for the JAK2 activation, although this effect was counteracted by quercetin and rutin. These results suggest that quercetin and rutin inhibit Cu(2+)-oxidized LDL-induced endothelial apoptosis through modulating JAK2-STAT3 pathways and that rutin may modulate a signaling crosstalk between JAK2 and MAPK.

Blockade of Chronic High Glucose–Induced Endothelial Apoptosis by Sasa borealis Bamboo Extract

Hyperglycemia is a causal factor in the development of diabetic vascular complications including impaired vascular smooth muscle contractility and increased cell proliferation. The present study was designed to investigate the effects of Sasa borealis water-extract (SBwE) on chronic hyperglycemia-induced oxidative stress and apoptosis in human umbilical endothelial cells (HUVEC). HUVEC were cultured in 5.5 mM low glucose, 5.5 mM glucose plus 27.5 mM mannitol as an osmotic control, or 33 mM high glucose for 5 days in the absence and presence of 1–30 μg/ ml SBwE. Caspase-3 activation and Annexin V staining revealed chronic high glucose–induced endothelial apoptotic toxicity with a generation of oxidants detected by DCF-fluorescence, and these effects were reversed by SBwE at ≥1 μg/ml in a dose-dependent manner. Cytoprotective SBwE substantially reduced the sustained high glucose–induced expression of endothelial nitric oxide synthase and attenuated the formation of peroxynitrite radicals. The suppressive effects of SBwE were most likely mediated through blunting activation of PKCβ2 and NADPH oxidase promoted by high glucose. In addition, this bamboo extract modulated the high glucose–triggered mitogen-activated protein kinase–dependent upregulation of heat-shock proteins. Our results suggest that SBwE suppressed these detrimental effects caused by PKC-dependent peroxynitrite formation via activation of NADPH oxidase and induction of nitric oxide synthase and heat-shock protein family that may be essential mechanisms responsible for increased apoptotic oxidative stress in diabetic vascular complications. Moreover, the blockade of high glucose–elicited heat-shock protein induction appeared to be responsible for SBwE-alleviated endothelial apoptosis. Therefore, SBwE may be a therapeutic agent for the prevention and treatment of diabetic endothelial dysfunction and related complications.

Roasted licorice extracts dampen high glucose-induced mesangial hyperplasia and matrix deposition through blocking Akt activation and TGF-β signaling

Diabetic nephropathy (DN) characterized as nephrotic syndrome and diffuse glomerulosclerosis can cause renal failure and end-stage kidney disease. Expansion of mesangial matrix around capillaries in the kidney glomeruli is a prominent feature of DN. This study investigated whether licorice extracts inhibited mesangial cell (MC) proliferation and matrix accumulation induced by high glucose (HG). Human renal MC were cultured in media containing 5.5 mM glucose plus 27.5 mM mannitol as an osmotic control or 33 mM glucose for 3 d in the presence of water or ethanol extracts from raw licorice (LW, LE) or roasted licorice (RLW, RLE). Non-polar components including glycyrrhetic acid were elevated during licorice roasting, whereas polar components soluble in water extracts were diminished. Exposure of cells to HG caused significant increases in collagen IV secretion and connective tissue growth factor (CTGF) expression, which was appeased by RLW and RLE at transcriptional levels. The inhibitory potency was high in the order of RLE > or = RLW > or = LE > > LW. Non-polar glycyrrhetic acid but not glycyrrhizin retarded HG-stimulated mesangial matrix deposition through diminishing CTGF expression. In addition, RLW and RLE but not LW modulated membrane type matrix metalloproteinase-1 (MT-1 MMP) expression, MMP-2 activity and tissue inhibitor of MMP-2 (TIMP-2), which facilitated the degradation of mesangial matrix. Furthermore, the augmented expression of CTGF and TIMP-2 in HG-exposed cells was mediated by Akt activation and TGF-beta/Smad signaling through PKCbeta2-responsive signaling pathways. However, HG-down-regulated MT-1 MMP expression was independent of activation of ERK1/2 and Akt when using their inhibitors of DB98059 (ERK1/2) and LY294002 (Akt) alone or in combination. These results demonstrate that extracts from roasted licorice may be highly potent therapeutic agents for the prevention and treatment of mesangial fibrosis and glomerulosclerosis leading to diabetes nephropathy due to longstanding diabetes mellitus.

Ginsenoside metabolite compound K differentially antagonizing tumor necrosis factor-α-induced monocyte–endothelial trafficking

Human leukocyte endothelial adhesion and transmigration occur in the early stage of the pathogenesis of atherosclerosis. Vascular endothelial cells are targeted by pro-inflammatory cytokines modulating many gene proteins responsible for cell adhesion, thrombosis and inflammatory responses. This study examined the potential of compound K to inhibit the pro-inflammatory cytokine TNF-α induction of monocyte adhesion onto TNF-α-activated human umbilical vein endothelial cells (HUVEC). HUVEC were cultured with 10ng/ml TNF-α with individual ginsenosides of Rb1, Rc, Re, Rh1 and compound K (CK). Ginsenosides at doses of ⩽50μM did not show any cytotoxicity. TNF-α induced THP-1 monocyte adhesion to HUVEC, and such induction was attenuated by Rh1 and CK. Consistently, CK suppressed TNF-α-induced expression of HUVEC adhesion molecules of VCAM-1, ICAM-1 and E-selectin, and also Rh1 showed a substantial inhibition. Rh1 and CK dampened induction of counter-receptors, α4/β1 integrin VLA-4 and αL/β2 integrin LFA-1 in TNF-α-treated THP-1 cells. Additionally, CK diminished THP-1 secretion of MMP-9 required during transmigration, inhibiting transendothelial migration of THP-1 cells. CK blunted TNF-α-promoted IL-8 secretion of HUVEC and CXCR1 expression of THP-1 monocytes. Furthermore, TNF-α-activated endothelial IκB phosphorylation and NF-κB nuclear translocation were disturbed by CK, and TNF-α induction of α4/β1 integrin was abrogated by the NF-κB inhibitor SN50. These results demonstrate that CK exerts anti-atherogenic activity with blocking leukocyte endothelial interaction and transmigration through negatively mediating NF-κB signaling.