Quercetin exerts anti-inflammatory effects via inhibiting tumor necrosis factor-a-induced matrix metalloproteinase-9 expression in normal human gastric epithelial cells

BACKGROUND & nbsp;Gastric injury is the most common digestive system disease worldwide and involves inflammation, which can lead to gastric ulcer or gastric cancer (GC). Matrix metallopeptidase-9 [MMP-9 (gelatinase-B)] plays an important role in inflammation and GC progression. Quercetin and quercetin-rich diets represent potential food supplements and a source of medications for treating gastric injury given their anti-inflammatory activities. However, the effects and mechanisms of action of quercetin on human chronic gastritis and whether quercetin can relieve symptoms remain unclear.& nbsp;AIM & nbsp;To assess whether tumor necrosis factor-alpha (TNF-alpha)-induced MMP-9 expression mediates the anti-inflammatory effects of quercetin in normal human gastric mucosal epithelial cells.& nbsp;METHODS & nbsp;The normal human gastric mucosa epithelial cell line GES-1 was used to establish a normal human gastric epithelial cell model of TNF-alpha-induced MMP-9 protein overexpression to evaluate the anti-inflammatory effects of quercetin. The cell counting Kit-8 assay was used to evaluate the effects of varying quercetin doses on cell viability in the normal GES-1 cell line. Cell migration was measured using Transwell assay. The expression of proto-oncogene tyrosine-protein kinase Src (c-Src), phospho (p)-c-Src, extracellular-signal-regulated kinase 2 (ERK2), p-ERK1/2, c-Fos, p-c-Fos, nuclear factor kappa B (NF-kappa B/p65), and p-p65 and the effects of their inhibitors were examined using Western blot analysis and measurement of luciferase activity. p65 expression was detected by immunofluorescence. MMP-9 mRNA and protein levels were measured by quantitative reverse transcription polymerase chain reaction (qRT-PCR) and gelatin zymography, respectively.& nbsp;RESULTS & nbsp;qRT-PCR and gelatin zymography showed that TNF-alpha induced MMP-9 mRNA and protein expression in a dose- and time-dependent manner. These effects were reduced by the pretreatment of GES-1 cells with quercetin or a TNF-alpha antagonist (TNFR inhibitor) in a dose- and time-dependent manner. Quercetin and TNF-alpha antagonists decreased the TNF-alpha-induced phosphorylation of c-Src, ERK1/2, c-Fos, and p65 in a dose- and time-dependent manner. Quercetin, TNF-alpha antagonist, PP1, U0126, and tanshinone IIA (TSIIA) reduced TNF-alpha-induced c-Fos phosphorylation and AP-1-Luciferase (Luc) activity in a dose- and time-dependent manner. Pretreatment with quercetin, TNF-alpha antagonist, PP1, U0126, or Bay 11-7082 reduced TNF-alpha-induced p65 phosphorylation and translocation and p65-Luc activity in a dose- and time-dependent manner. TNF-alpha significantly increased GES-1 cell migration, and these results were reduced by pretreatment with quercetin or a TNF-alpha antagonist.& nbsp;CONCLUSION & nbsp;Quercetin significantly downregulates TNF-alpha-induced MMP-9 expression in GES-1 cells via the TNFR-c-Src-ERK1/2 and c-Fos or NF-kappa B pathways.