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Epigallocatechin-3-O-gallate up-regulates microRNA-199a-3p expression by down-regulating the expression of cyclooxygenase-2 in stimulated human osteoarthritis chondrocytes.

ABSTRACT: Osteoarthritis (OA) is a most common form of arthritis worldwide leading to significant disability. MicroRNAs (miRNAs) are non-coding RNAs involved in various aspects of cartilage development, homoeostasis and pathology. Several miRNAs have been identified which have shown to regulate expression of target genes relevant to OA pathogenesis such as matrix metalloproteinase (MMP)-13, cyclooxygenase (COX)-2, etc. Epigallocatechin-3-O-gallate (EGCG), the most abundant and active polyphenol in green tea, has been reported to have anti-arthritic effects, however, the role of EGCG in the regulation of miRNAs has not been investigated in OA. Here, we showed that EGCG inhibits COX-2 mRNA/protein expression or prostaglandin E2 (PGE2 ) production via up-regulating microRNA hsa-miR-199a-3p expression in interleukin (IL)-1β-stimulated human OA chondrocytes. This negative co-regulation of hsa-miR-199a-3p and COX-2 by EGCG was confirmed by transfection of OA chondrocytes with anti-miR-199a-3p. Transfection of OA chondrocytes with anti-miR-199a-3p significantly enhanced COX-2 expression and PGE2 production (P < 0.001), while EGCG treatment significantly inhibited anti-miR-199a-3p transfection-induced COX-2 expression or PGE2 production in a dose-dependent manner. These results were further re-validated by co-treatment of these transfection OA chondrocytes with IL-1β and EGCG. EGCG treatment consistently up-regulated the IL-1β-decreased hsa-miR-199a-3p expression (P < 0.05) and significantly inhibited the IL-1β-induced COX-2 expression/PGE2 production (P < 0.05) in OA chondrocytes transfected with anti-hsa-miR-199a-3p. Taken together, these results clearly indicate that EGCG inhibits COX-2 expression/PGE2 production via up-regulation of hsa-miR-199a-3p expression. These novel pharmacological actions of EGCG on IL-1β-stimulated human OA chondrocytes provide new suggestions that EGCG or EGCG-derived compounds inhibit cartilage breakdown or pain by up-regulating the expression of microRNAs in human chondrocytes.

SUBMITTER: Rasheed Z

PROVIDER: S-EPMC5134388 | biostudies-other | 2016 Dec

REPOSITORIES: biostudies-other

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Project description:Epigallocatechin-3-gallate (EGCG) is a bioactive polyphenol of green tea and exerts potent anti-inflammatory effects by inhibiting signaling events and gene expression. Interleukin-1beta (IL-1?) is the principal cytokine linked to cartilage degradation in osteoarthritis (OA). The objective of this study was to evaluate the global effect of EGCG on IL-1?-induced expression of proteins associated with OA pathogenesis in human chondrocytes.Primary OA chondrocytes were pretreated with EGCG (10 to 100 uM) and then stimulated with IL-1? (5 ng/ml) for 24 hours. Culture supernatants were incubated with cytokine antibody arrays and immunoreactive proteins (80 proteins) were visualized by enhanced chemiluminiscence. Effect of EGCG on IL-1?-induced expression of 18 selected genes was verified by Real time-PCR and effect on IL-6, IL-8 and tumor necrosis factor-alpha (TNF-?) production was determined using specific ELISAs. Western immunoblotting was used to analyze the effect of EGCG on the interleukin-1 receptor-associated kinase 1 (IRAK-1) and TNF receptor-associated factor 6 (TRAF-6) proteins in IL-1?-stimulated chondrocytes. The role of nuclear factor kappa-B (NF-?B) and mitogen activated protein kinases (MAPKs) in the regulation of selected genes and the mechanism involved in EGCG mediated modulation of these genes was determined by using specific inhibitors for NF- ?B (MG132) and MAPKs (p38-MAPK, SB202190; JNK-MAPK, SP600125, ERK-MAPK, PD98059).Out of 80 proteins present on the array, constitutive expression of 14% proteins was altered by EGCG treatment. No significant stimulatory effect was observed on the proteins associated with cartilage anabolic response. Stimulation with IL-1? enhanced the expression of 29 proteins. Expression of all 29 proteins up-regulated by IL-1? was found to be suppressed by EGCG. EGCG also inhibited the expression of the signaling intermediate TRAF-6 at 50 and 100 uM concentrations (P < 0.05). Our results identified several new targets of EGCG, including epithelial neutrophil activating peptide-78 (ENA-78), granulocyte macrophage colony stimulation factor (GM-CSF), growth- related oncogene (GRO), GRO-?, IL-6, IL-8, monocyte chemotactic protein-1 (MCP-1), MCP-3, macrophage inflammatory protein-1beta (MIP-1?), granulocyte chemotactic protein-2 (GCP-2), MIP-3alpha, interferon-gamma-inducible protein-10 (IP-10), nucleosome assembly protein-2 (NAP-2) and leukemia inhibitory factor (LIF). The inhibitory effects of EGCG were mainly mediated by inhibiting the activation of NF-?B and c-Jun N-terminal Kinase (JNK)-MAPK in human chondrocytes.Our results suggest that the potential of EGCG in OA treatment/prevention may be related to its ability to globally suppress the inflammatory response in human chondrocytes. These results identify additional new targets of EGCG and advocate that EGCG may be a potent chondroprotective agent in OA.

Project description:Trisomy of human chromosome 21 (Down syndrome, DS) alters development of multiple organ systems, including the face and underlying skeleton. Besides causing stigmata, these facial dysmorphologies can impair vital functions such as hearing, breathing, mastication, and health. To investigate the therapeutic potential of green tea extracts containing epigallocatechin-3-gallate (GTE-EGCG) for alleviating facial dysmorphologies associated with DS, we performed an experimental study with continued pre- and postnatal treatment with two doses of GTE-EGCG supplementation in a mouse model of DS, and an observational study of children with DS whose parents administered EGCG as a green tea supplement. We evaluated the effect of high (100 mg/kg/day) or low doses (30 mg/kg/day) of GTE-EGCG, administered from embryonic day 9 to post-natal day 29, on the facial skeletal development in the Ts65Dn mouse model. In a cross-sectional observational study, we assessed the facial shape in DS and evaluated the effects of self-medication with green tea extracts in children from 0 to 18 years old. The main outcomes are 3D quantitative morphometric measures of the face, acquired either with micro-computed tomography (animal study) or photogrammetry (human study). The lowest experimentally tested GTE-EGCG dose improved the facial skeleton morphology in a mouse model of DS. In humans, GTE-EGCG supplementation was associated with reduced facial dysmorphology in children with DS when treatment was administered during the first 3 years of life. However, higher GTE-EGCG dosing disrupted normal development and increased facial dysmorphology in both trisomic and euploid mice. We conclude that GTE-EGCG modulates facial development with dose-dependent effects. Considering the potentially detrimental effects observed in mice, the therapeutic relevance of controlled GTE-EGCG administration towards reducing facial dysmorphology in young children with Down syndrome has yet to be confirmed by clinical studies.

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Epigallocatechin-3-O-gallate up-regulates microRNA-199a-3p expression by down-regulating the expression of cyclooxygenase-2 in stimulated human osteoarthritis chondrocytes.

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