Aim: To study the effects of Helicobacter pylori (H. pylori) tumor necrosis factor-α (TNF) inducing protein (Tip-α) on cytokine expression and its mechanism.
Methods: We cloned Tip-α from the H. pylori strain 26695, transformed Escherichia coli with an expression plasmid, and then confirmed the expression product by Western blotting. Using different concentrations of Tip-α that affected SGC7901 and GES-1 cells at different times, we assessed cytokine levels using enzyme-linked immunosorbent assay. We blocked SGC7901 cells with pyrrolidine dithiocarbamate (PDTC), a specific inhibitor of nuclear factor κB (NF-κB). We then detected interleukin (IL)-1β and TNF-α levels in SGC7901 cells.
Results: Western blot analysis using an anti-Tip-α antibody revealed a 23-kDa protein, which indicated that recombinant Tip-α protein was recombined successfully. The levels of IL-1β, IL-8 and TNF-α were significantly higher following Tip-α interference, whether GES-1 cells or SGC-7901 cells were used (P < 0.05). However, the levels of cytokines (including IL-1β, IL-8 and TNF-α) secreted by SGC-7901 cells were greater than those secreted by GES-1 cells following treatment with Tip-α at the same concentration and for the same duration (P < 0.05). After blocking NF-κB with PDTC, the cells (GES-1 cells and SGC-7901 cells) underwent interference with Tip-α. We found that IL-1β and TNF-α levels were significantly decreased compared to cells that only underwent Tip-α interference (P < 0.05).
Conclusion: Tip-α plays an important role in cytokine expression through NF-κB.
Keywords: Helicobacter pylori; Interleukin-1β; Interleukin-8; Nuclear factor-κB; Tumor necrosis factor-α; Tumor necrosis factor-α inducing protein.