Differences in interleukin 8 expression in Helicobacter pylori-infected gastric mucosa tissues from patients in Bhutan and the Dominican Republic

SummaryThe outcomes of Helicobacter pylori infection vary geographically. H pylori strains, disease presentation, and environments differ markedly in Bhutan and Dominican Republic. The aims were to compare the strains, histology, and expression of interleukin (IL) 8 and IL-10 from gastric mucosa from the 2 countries. H pylori status was assessed by the combination of rapid urease test, culture, and histology. Histology was evaluated using the updated Sydney System, and cytokines in gastric biopsies were measured using real-time polymerase chain reaction (PCR). There were 138 subjects from Bhutan and 155 from Dominican Republic. The prevalence of H pylori infection was 65% and 59%, respectively. The genotype of cagA was predominantly East Asian type in Bhutan versus Western type in Dominican Republic. Gastritis severity was significantly higher in H pylori-infected subjects from Bhutan than those from Dominican Republic. IL-8 expression by H pylori infection was 5.5-fold increased in Bhutan versus 3-fold in Dominican Republic (P < .001); IL-10 expression was similar. IL-8 expression levels among H pylori-infected cases tended to be positively correlated with polymorphonuclear leucocyte and monocyte infiltration scores in both countries. IL-8 expression among those with grade 2 and 3 polymorphonuclear leucocyte and monocyte infiltration was significantly higher in Bhutan than in Dominican Republic. The difference in IL-8 expression in the 2 countries is reflected in the different disease pattern between them. Whether the dominant factor is differences in H pylori virulence, in host-H pylori-environmental interactions, genetic factors or all remains unclear. However, severity of inflammation appears to be a critical factor in disease pathogenesis. We compared IL-8 messenger RNA levels between the high gastric cancer risk country, Bhutan (mainly East Asian-type H pylori), and the lower gastric cancer risk country, Dominican Republic (mainly Western-type H pylori).