S100A8 and peptic ulcer disease: Moreover, studies showed that several virulence factors such as outer inflammatory protein (OipA), epithelial gene A1 (iceA1), babA2-gene positive (encodes BabA protein), duodenal ulcer promoting gene cluster (dupA cluster), vacA s1/m1 genotype, and cagA-gene positive expression are associated with peptic ulcer disease [61].