Effect of bile salts and bile acids on human gastric mucosal epithelial cells

Abstract

Objective To explore the effect of bile salt and bile acid on cultured eternalized human gastric mucosa epithelium GES-1cells. Methods Cultured eternalized human gastric mucosa epithelium GES-1 cells were treated with media containing 6 different kinds of bile salts and 3 different kinds of bile acids and their mixture with different concentrations: GCDC (glycochenodeoxycholate), GDC (glycodeoxycholate), GC (glycocholate), TCDC (taurochenodeoxycholate), TDC (taurodeoxycholate), TC (taurocholate), LCA (lithocholicacid), CA (cholic acid), DCA (deoxycholic acid)(50 μ mol/L,250 μ mol/L,500 μ mol/L,1000 μ mol/L), DY (mixture of bile salts) and DS (mixture of bile acids)(250 μ mol/L,500 μ mol/L,1000 μ mol/L,1500 μ mol/L, 2000 μ mol/L), in comparison with the control group (in normal media without bile salts and bile acids). Cell proliferation was assessed by MTT (3-[4,5-Dimethylthiaolyl]-2,5-diphenyl-tetrazolium bromide) assay for 72 hours with different concentrations and the apoptotic cells were assayed by flow cytometry (FCM) with Annex V-FITC conjugated with propidium iodide (PI) staining for 24 hours with different concentrations (1500,2000μ mol/L). Results There was no significant difference in morphology and cell proliferation in GC group after 24∼72 h. Low concentration (50 μ mol/L) of GCDC, GDC, TCDC, TDC and TC accelerated gastric epithelial cell growth in a dosage-time dependent manner. At middle concentration (250-500 μ mol/L), it showed positive effect after 24∼48 h, while negative effect after 72 h. At high concentration (1000 μ mol/L), it accelerated gastric epithelial cell growth after 24h and show consistent inhibition even leading to necrosis after 48∼72 h. LCA and CA showed a positive effect on the concentration of 50 μ mol/L after 24∼72 h, while 250–1000 μ mol/L showed a trend towards apoptosis after 24∼72 h. At 50–500 μ mol/L, DCA showed proliferation after 24 h and apoptosis after 48∼72 h, but showed necrosis after 24∼72 h at 1000 μ mol/L. DY and DS could facilitate normal gastric mucosa epithelial cell growth at low concentration (250-500 μ mol/L), however at 1000–2000 μ mol/L the trend shifted from apoptosis to necrosis. FCM with Annexin-V conjugated with PI staining revealed that GCDC, GDC, GC, TCDC, TDC, TC, LCA, CA, DCA, DY and DS induced apoptosis of human gastric mucosal epithelial cells. They were all significantly higher than that of the control ( P < 0.05), but there was no significant difference in GC group ( P > 0.05). The bile salts induced apoptosis in a time-dose-dependent manner. Conclusion Our results suggested that bile acid and bile salt is the trigger of injury in human gastric mucosal epithelial cells.