Helicobacter pylori genetic diversity and risk of human disease

Abstract

Microbes residing on a mucosal surface may communicate in complex ways with their neighboring host tissue. Signals derived from a bacterium may include metabolites or specific host-directed substances such as secreted toxins, or they may result from direct contact with host cells. Conversely, certain host activities or responses may be considered as signals to the microbe, including production of molecules that can be used by the microbe as substrates, release of defense molecules (e.g., antibodies, defensins, mucus), or organ-specific physiologic traits, including peristalsis and acid secretion in the stomach. In the case of Helicobacter pylori, a common resident of the human stomach, these bidirectional signals appear to have coevolved over long periods such that, in most cases, carriage of H. pylori is, if not mutually beneficial, at least well tolerated by the human host. Here, we examine the relationship of H. pylori and humans in the context of these diverse signals.