Objective  This study investigated the effects of live Helicobacter pylori on the apoptosis of the human hepatoma cells (HepG2).

  Methods  The effect of the co-incubation with different concentrations of the H.pylori NCTC11637 strain(4.0×10⁵, 4.0×10⁶, 4.0×10⁷ and 4.0×10⁸ CFU/ml) for 24 h on the apoptotic rates of HepG2 cells were investigated by the MTT assay, fluorescence imaging, ultrastructural analysis, and flow cytometry.

  Results  H.pylori significantly inhibited the HepG2 cell growth in a dose-dependent manner (P < 0.05).The respective inhibition ratios were(2.64±0.34)%, (16.35±4.24)%, (27.15±3.19)%, and(33.35±2.36)%, in the order of increasing NCTC11637 concentrations, after 24 h of incubation.H.pylori promoted the apoptosis of HepG2 cells, and this effect was enhanced with the increased bacterial concentration.The different phases of the apoptosis were observed after the co-incubation with H.pylori using an electron microscope.The respective apoptotic rates of the HepG2 cells were(2.50±0.45)%, (6.00±0.35)%, (11.10±0.45)%, and(14.65±0.27)%after 24 h of incubation with the increasing NCTC11637 concentrations.Differences in the apoptotic rates that were higher than(2.50±0.45)%were considered significant(P < 0.05).The Bcl-2 protein levels were inhibited, whereas the Bax protein levels were increased in the HepG2 cells after treatment with H.pylori.

  Conclusion  The co-incubation of HepG2 cells with H.pylori increases their rate of apoptosis in a concentration-dependent manner through the Bcl-2/Bax mechanism.