S100A8 and chronic gastritis: H. pylori strains that express the cagA and vacA genes are associated with development of chronic gastritis and intestinal metaplasia as well as increased risk for gastric cancer [48, 49]. H. pylori has shown that approximately 50–60% of strains have a 40 kb DNA segment called the cytotoxin-associated gene (cagA) pathogenecity island (PAI) [50].