Abstract
Helicobacter pylori is a Gram-negative bacterium that is recognized as one of the key factors in gastric diseases such as gastritis, peptic ulcer and gastric cancer. Recent studies have shown relationships between H. pylori and extra-digestive diseases, and the presence of H. pylori in the middle ear and upper respiratory tract has been reported. However, the role of H. pylori in middle ear disease remains unclear. The present study demonstrated that H. pylori whole-cell protein directly induces macrophage migration inhibitory factor, macrophage inflammatory protein 2, interleukin 1 beta and tumor necrosis factor alpha in middle ear epithelium in mice, and severe proliferation of inflammatory cells was observed in middle ear cavity inoculated with H. pylori whole-cell protein. In addition, trans-tympanic injection of macrophage migration inhibitory factor up-regulated expression of macrophage inflammatory protein 2 in the middle ear. These findings indicate that H. pylori infection causes immunological inflammation in middle ear epithelium, and H. pylori may play a significant role in otitis media.