Intestinal Helminthiasis in Colombian Children Promotes a Th2 Response to Helicobacter pylori: Possible Implications for Gastric Carcinogenesis

Abstract

Background: Colombians living in coastal Tumaco have a lower incidence of Helicobacter pylori -associated gastric cancer compared with residents of Pasto in the high Andes. Considering the risk for H. pylori disease seems affected by features of bacterial virulence and host polymorphisms, other poorly understood influences, such as concurrent helminthiasis, may also be important. Methods: Fecal samples from 211 children were tested for parasites and sera from another cohort of 159 children and 92 adults were tested for IgE and H. pylori -specific IgG. Results: Most individuals (95%) from both areas were H. pylori seropositive, with a predominant response of IgG1 followed by IgG2 and low IgG3 and IgG4 antibodies. Compared with Pasto children, Tumaco children were more

The CD4+ T Cell-Mediated IFN-γ Response to Helicobacter Infection Is Essential for Clearance and Determines Gastric Cancer Risk

“…Experimental polarization of systemic responses to Helicobacter by concurrent helminth infection was further shown to alleviate gastric premalignant pathology (71), lending considerable support to this model. In fact, an epidemiological study from Colombia looking at T H 2-polarized responses to Helicobacter and concurrent helminth infections in children suggested that populations with low gastric cancer risk had significantly higher rates of helminths than high-risk populations (72). Apart from environmental factors affecting T H 1/T H 2 balance, disease outcome upon chronic infection may be influenced by polymorphisms affecting IFN-␥ signaling, for instance in the IFN-␥ receptor chain 1 (IFNGR) or the IFNG gene itself (25,(73)(74)(75).…”

Inflammation, atrophy, and gastric cancer

“…Studies supporting this Th1/Th2 paradigm as the best explanation for geographic variation in gastric cancer rates among humans and the so-called "African enigma" (whereby in Africa rates of infection with H. pylori are high but rates of gastric cancer are low) have used measurement of IgG subclass responses as surrogate markers for polarization of Th cell function (78). These studies suggested that adults in undeveloped areas of the world mount predominantly Th2 cell-associated IgG1 responses to infection with H. pylori, whereas adults in developed countries mount predominantly Th1 cell-associated IgG2 responses (78); this bias to Th2 cell responses correlates with a higher rate of intestinal helminthiasis (79). Furthermore, individuals infected with H. pylori and Schistosoma mansoni have been found to have reduced numbers of apoptotic gastric epithelial cells and decreased gastric epithelial cell proliferation as compared with persons infected with just H. pylori (80).…”

Helicobacter pylori Evolution: Lineage-Specific Adaptations in Homologs of Eukaryotic Sel1-Like Genes

“…We suggest, rather, that this divergence reflects a condition unique to H. pylori in the Japanese islands at some recent evolutionary time. Possibilities include differences between the islands and the East Asian mainland in prevalence of other pathogens or parasites that affect host responses to H. pylori [55,56] and how H. pylori can best manage them; or host genotype, diet or nutrition, or sociocultural features that could also affect host responses to infection. The divergent Japanese-type hp0519 alleles might have existed at low frequency before being strongly selected in Japan.…”