Anti-inflammatory activity of an aqueous extract of vitis vinifera L. (var. teinturiers) in gastric epithelial cells

Helicobacter pylori (H. pylori) is the bacterium main involved in the pathogenesis of gastric diseases such as peptic ulcer and gastritis; in gastric inflammation, macrophages produce pro-inflammatory cytokines, including TNFα and IL-1β, which determine the activation of NF-κB in gastric epithelial cells (Mai, U.E.). NF- κB is an important transcription factor that controls the expression of numerous genes involved in inflammatory processes, including the gene of IL-8, at the level of gastric epithelium (Yasumoto, K.). Today, antacids and proton pump inhibitors are mainly used to fight gastritis, often in combination with antibiotics in the case of H. pylori infection; however, it has also been shown that the intake of this drugs causes severe adverse effects (Yang, Y.X., Laheij R.G.). For this reason, it is necessary to search for new strategies that are useful in the treatment of this pathology. The water extract of Vitis vinifera L. leaves is a component of various food supplements, but currently there are no studies in the literature on anti-inflammatory activity in the gastrointestinal tract. The aim of this study was to evaluate the effect of the extract of Vitis vinifera L. on gastric inflammation. The water extract was obtained from dried leaves of Vitis vinifera L., var. teinturiers and characterized by pH differential method and HPLC-DAD analysis; the extract was assayed on human gastric epithelial cells (AGS) stimulated with TNFα and IL-1β (both at 10 ng/mL). NF-κB driven transcription was evaluated by transient transfection with a plasmid containing the luciferase gene. NF-κB nuclear translocation and IL-8 secretion were performed by an ELISA assay, after 1 and 6 hours treatment respectively. Quantitative analysis showed that kaempferol-3-O-glucoside was the most abundant flavonoid, and cyanidin-3-O-glucoside the main anthocyanoside. The extract inhibited NF-κB driven transcription in concentration-dependent way, after stimulation with both TNFα and IL-1β, with statistically significant inhibition starting from 5 μg/mL and 25 μg/mL, respectively. One hour pre-treatment with the same concentrations of the extract, followed by 6 hours stimulus lead to an inhibitory effect on NF-κB driven transcription. The extract inhibited NF-κB translocation in concentration-dependent manner; the translocation was reported at the level of unstimulated control at the highest concentration assayed (50 μg/mL), after stimulation with TNFα and IL-1β. IL-8 secretion was inhibited in dose-dependent way after stimulation with TNFα while, after stimulation with IL-1β, the extract inhibited IL-8 secretion, in statistically significant way, only at the concentration of 200 μg/mL. In conclusion, this study indicates that the extract of Vitis vinifera L. is able to exert a possible beneficial effect on gastric inflammation; if this effect will be confirmed by in vivo studies, the extract of Vitis vinifera L. could be used in the treatment of gastric inflammations.