The immune modulating activity of the Helicobacter pylori HP-NAP: Friend or foe?

The Helicobacter pylori HP-NAP is a dodecameric protein with a three-dimensional structure similar to that of bacterioferritins. Originally defined as neutrophil-activating protein, because of its ability to stimulate neutrophils to produce oxygen radicals, HP-NAP is now considered a crucial factor in driving the Th1 inflammation in H. pylori infection. This review summarizes recent studies that have provided a deeper understanding of the pro-inflammatory and immune modulatory properties of HP-NAP. We first examine the role of this protein in the H. pylori-associated disease, and then we discuss recent findings that support the possibility for HP-NAP to become a new tool for therapeutic strategies aimed at redirecting Th2 into Th1 responses, for example in atopy, vaccinology and cancer immunotherapy.