Anti-inflammatory effect of external use of escin on cutaneous inflammation: possible involvement of glucocorticoids receptor.

Escin, as an internally applied anti-inflammatory agent, has been widely used in the treatment of inflammation and edema resulting from trauma or operation in the clinic. However, the effect of its external use on cutaneous inflammation and edema remains unexplored. In the present study, the anti-inflammatory and anti-edematous effects of external use of escin were studied in carrageenan-induced paw edema and histamine-induced capillary permeability in rats, paraxylene-induced ear swelling in mice, and cotton pellet-induced granuloma in rats. Effects of external use of escin gel on prostaglandin E2 (PGE2), tumor necrosis factor-α (TNF-α), and interleukin-1ß (IL-1ß) were determined by ELISA. The anti-inflammatory mechanism was explored by detecting the expression of glucocorticoid receptor (GR) with Western blotting and Real-time PCR analyses, with further exploration of nuclear factor-κB (NF-κB), p38 mitogen-activated protein kinase (P38MAPK) and activator protein-1 (AP-1) expressions. We demonstrated that external use of escin showed significant anti-inflammatory effects on acute and chronic inflammation in different animal models and its anti-inflammatory effects might be related to down-regulation of PGE2, TNF-α, and IL-1ß. The results also showed that escin exerted its anti-inflammatory effects by promoting the expression of GR, with the possible mechanism being inhibition of the expressions of GR-related signaling molecules such as NF-κB and AP-1.

Bacterial Outer Membrane Vesicles from Dextran Sulfate Sodium-Induced Colitis Differentially Regulate Intestinal UDP-Glucuronosyltransferase 1A1 Partially Through Toll-Like Receptor 4/Mitogen-Activated Protein Kinase/Phosphatidylinositol 3-Kinase Pathway.

UDP-glucuronosyltransferase 1A1 (UGT1A1) constitutes an important part of intestinal epithelial barrier and catalyzes glucuronidation of many endogenous compounds and drugs. Downregulation of UGT1A1 in inflammation has been reported, whereas the association with gut dysbiosis is poorly defined. This study verified the involvement of gut microbiota in intestinal UGT1A1 regulation using dextran sulfate sodium (DSS)-induced rat colitis model plus fecal microbiota transplantation (FMT). Generally, both DSS induction and colitis-to-normal FMT suppressed mRNA and protein expressions of UGT1A1 and nuclear xenobiotic receptors (NRs) in colon, but enhanced mRNA and decreased protein of rat UGT1A1/rat NRs in small intestine. Normal-to-colitis FMT alleviated DSS-induced changes. Bacterial outer membrane vesicles (OMVs) from colitis rats and rats receiving colitis feces reduced both mRNA and protein of human UGT1A1 (hUGT1A1)/human NRs (hNRs) in Caco-2 cells. Interestingly, using deoxycholate to reduce lipopolysaccharide, normal OMVs upregulated hUGT1A1/hNRs, whereas colitis OMVs decreased, indicating the involvement of other OMVs components in UGT1A1 regulation. The 10- to 50-kDa fractions from both normal and colitis OMVs downregulated hUGT1A1, human PXR, and human PPAR-γ, whereas >50-kDa fractions from normal rats upregulated hUGT1A1 and human CAR. Additionally, the conditioned medium from OMVs-stimulated rat primary macrophages also reduced hUGT1A1/hNRs expression. Both Toll-like receptor (TLR)2 and TLR4 were activated by DSS, colitis-to-normal FMT, and the opposite, whereas only TLR4 was increased in OMVs-treated cells. TLR4 small interfering RNA blocked hUGT1A1/hNRs downregulation and phosphatidylinositol 3-kinase/Akt, extracellular signal-regulated kinase, and nuclear factor κB phosphorylation evoked by bacterial OMVs. Taken together, this study demonstrated that gut microbiota regulate intestinal UGT1A1 partially through secreting OMVs, which interact with intestinal epithelial cells directly or via activating macrophage.

Inhibitory effects of 2,3,4',5-tetrahydroxystilbene-2-O-ß-D-glucoside on angiotensin II-induced proliferation of vascular smooth muscle cells.

OBJECTIVE: To investigate the effect of 2,3,4',5-tetrahydroxystilbene-2-O-ß-D-glucoside (TSG), an active component extracted from the root of Polygonum multiflorum, on angiotensin II (Ang II)-induced proliferation of cultured rat vascular smooth muscle cells (VSMCs) and to identify the potential mechanism. METHODS: Cell proliferation and cell cycle were determined by cell counting, 5-bromo-2'-deoxyuridine incorporation assay, proliferating cell nuclear antigen protein expression and flow cytometry. Levels of phosphorylated extracellular signal-regulated kinase 1/2 (ERK1/2), mitogenic extracellular kinase 1/2 (MEK1/2) and Src in VSMCs were measured by Western blot. The expression of c-fos, c-jun and c-myc mRNA were measured by reverse transcription polymerase chain reaction (RT-PCR). Intracellular reactive oxygen species (ROS) was measured by fluorescence assay. RESULTS: TSG significantly inhibited Ang II-induced VSMCs proliferation and arrested cells in the G /S checkpoint (P<0.05 or P<0.01). TSG decreased the levels of phosphorylated ERK1/2, MEK1/2 and Src in VSMCs (P<0.05 or P<0.01). TSG also suppressed c-fos, c-jun and c-myc mRNA expression <0.05 or P<0.01). In addition, the intracellular ROS was reduced by TSG (P<0.01). CONCLUSIONS: TSG inhibited Ang II-induced VSMCs proliferation. Its antiproliferative effect might be associated with down-regulation of intracellular ROS, followed by the suppression of the Src-MEK1/2-ERK1/2 signal pathway, and hence, blocking cell cycle progression.

2,3,4',5-Tetrahydroxystilbene-2-O-ß-D-glucoside inhibits angiotensin II-induced cardiac fibroblast proliferation via suppression of the reactive oxygen species-extracellular signal-regulated kinase 1/2 pathway.

Cardiac fibroblasts (CF) have direct and potent effects on myocardial remodelling by proliferating, differentiating and secreting extracellular matrix proteins. Prolonged activation of CF leads to cardiac fibrosis and reduces myocardial contractile function. In previous studies we showed that 2,3,4',5-tetrahydroxystilbene-2-O-ß-d-glucoside (TSG) exerts cardiac protection, but the mechanism involved remains unclear. The aim of the present study was to evaluate the effects of TSG on angiotensin (Ang) II-induced CF proliferation and to explore the underlying intracellular mechanisms. Angiotensin II (100 nmol/L)-induced proliferation of rat neonatal fibroblasts was significantly inhibited by TSG (3-100 µmol/L), as evidenced by investigations of cell numbers and 5-bromodeoxyuridine (BrdU) incorporation. In addition, 30 µmol/L TSG suppressed AngII-induced expression of nuclear antigen, matrix metalloproteinase (MMP)-2 and MMP-9. Moreover, TSG attenuated AngII-induced activation of mitogen-activated protein kinase kinase (MEK) and extracellular signal-regulated kinase (ERK) 1/2. Angiotensin II (100 nmol/L)-induced generation of reactive oxygen species (ROS) was reduced by 30 µmol/L TSG, as was H(2) O(2) -induced activation of ERK1/2. However, the MEK inhibitor 50 µmol/L PD98059 did not reduce ROS generation, although it did inhibit cell proliferation. There was a significant correlation between the inhibition of ERK1/2 activation and suppression of cell proliferation by TSG. However, there were no additive effects on either the inhibition of ERK1/2 or the suppression of cell proliferation following treatment of cells with both PD98059 and TSG. In conclusion, the results of the present study suggest that TSG inhibits ERK1/2 activation, likely via buffering of ROS, and consequently suppresses cell proliferation.

2,3,4',5-tetrahydroxystilbene-2-O-ß-D-glucoside inhibits proliferation of vascular smooth muscle cells: involvement of NO/cGMP/PKG pathway.

The proliferation of vascular smooth muscle cells (VSMCs) induced by injury to the intima of arteries is an important etiologic factor in vascular proliferative disorders such as atherosclerosis and restenosis. 2,3,4',5-Tetrahydroxystilbene-2-O-ß-D-glucoside (TSG), an active component extracted from Polygonum multiflorum, has been found to have an antiatherosclerotic effect. The aim of this study was to investigate the effects of TSG on platelet derived growth factor (PDGF)-BB induced VSMCs proliferation and to explore the possible mechanisms of such effects. Pretreatment of VSMCs with TSG significantly inhibited PDGF-BB-induced cell proliferation in a concentration-dependent but not time-dependent manner. In addition, flow cytometry analysis of the DNA content revealed blocking of the PDGF-BB-inducible cell cycle progression by TSG. On the contrary, an inhibitory effect of TSG on VSMCs proliferation and expression of cell cycle regulators were markedly attenuated by addition of an nitric oxide (NO) synthase inhibitor, a soluble guanylate cyclase inhibitor and a cyclic GMP (cGMP)-dependent protein kinase (PKG) inhibitor: N(G)-nitro-L-arginine methyl ester (L-NAME), 1H-[1,2,4] oxadiazolo [4,3-α] quinoxalin-1-one (ODQ) and KT5823, respectively. It was also demonstrated that TSG enhanced NO and cGMP formation through up-regulating endothelial NO synthase expression in VSMCs. The findings indicate that TSG inhibited VSMCs proliferation induced by PDGF-BB may involve the NO/cGMP/PKG signal pathway.

2,3,4',5-Tetrahydroxystilbene-2-O-ß-d-glucoside inhibits platelet-derived growth factor-induced proliferation of vascular smooth muscle cells by regulating the cell cycle.

1. 2,3,4',5-Tetrahydroxystilbene-2-O-ß-d-glucoside (TSG) has been shown to have an anti-atherosclerotic effect. Vascular smooth muscle cell (VSMC) proliferation contributes to the pathobiology of atherosclerosis. The aim of the present study was to investigate the effects of TSG on platelet-derived growth factor (PDGF)-BB-induced VSMC proliferation and to explore the molecular mechanisms underlying the effects. 2. Cultured rat VSMC were pretreated with TSG (l-50 µmol/L) for 1 h, followed by exposure to PDGF-BB (10 ng/mL) for 24 h, after which cell proliferation and cell cycle stages were examined. The expression of protein cell cycle regulators, including retinoblastoma (Rb), cyclin D1/E, cyclin-dependent kinase (CDK) 2/4, CDK inhibitors p21 and p27 and proliferative cell nuclear antigen (PCNA), was examined. Activation of extracellular signal-regulated kinase (ERK) 1/2 was evaluated to elucidate the possible upstream mechanism by which TSG affects cell cycle regulators. 3. The results showed that TSG dose-dependently inhibited PDGF-BB-induced VSMC proliferation, possibly by blocking the progression of the cell cycle from the G(1) to S phase. In addition, TSG significantly inhibited PDGF-BB-induced phosphorylation of Rb and the expression of cyclin D1, CDK4, cyclin E, CDK2 and PCNA. In addition, TSG suppressed PDGF-BB-induced downregulation of p27 and upregulation of p21, as well as PDGF-BB-induced activation of ERK1/2. 4. Together, the findings of the present study provide the first evidence that TSG can inhibit PDGF-BB-stimulated VSMC proliferation via cell cycle arrest in association with modulation of the expression of cell cycle regulators, which may be mediated, at least in part, by suppression of ERK1/2 activation.