Figure 7. A hypothetical model of the steps required for a successful Helicobacter pylori colonization of the stomach.

-1- Oral ingestion -2- H. pylori has to remain motile in the gastric lumen, where active pepsins, particularly pepsin C, can cause a rapid loss of motility and could therefore prevent an acute colonization¹⁶,¹⁷.-3- As deduced from the presented experimental series, a postprandial pH difference between lumen and mucus caused by a dynamic decrease of the gastric lumen pH might be essential for H. pylori to be guided toward the mucus surface for colonization. -4- In the gastric mucus, chemotactic movement guided by the bicarbonate-dependent mucus pH-gradient appeared to be one condition required for H. pylori orientation to reach the mucus adjacent to the tissue (juxtamucosal mucus)¹⁵. Within this deep mucus layer, the secreted pepsinogen is not activated and the surrounding pH is less acidic.