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Helicobacter pylori (HP) genetics may determine its clinical outcomes. Despite high prevalence of HP infection in Latin America (LA), there have been no phylogenetic studies in the region. We aimed to understand the structure of HP populations in LA mestizo individuals, where gastric cancer incidence remains high. The genome of 107 HP strains from Mexico, Nicaragua and Colombia were analyzed with 59 publicly available worldwide genomes. To study bacterial relationship on whole genome level we propose a virtual hybridization technique using thousands of high-entropy 13 bp DNA probes to generate fingerprints. Phylogenetic virtual genome fingerprint (VGF) was compared with Multi Locus Sequence Analysis (MLST) and with phylogenetic analyses of cagPAI virulence island sequences. With MLST some Nicaraguan and Mexican strains clustered close to Africa isolates, whereas European isolates were spread without clustering and intermingled with LA isolates. VGF analysis resulted in increased resolution of populations, separating European from LA strains. Furthermore, clusters with exclusively Colombian, Mexican, or Nicaraguan strains were observed, where the Colombian cluster separated from Europe, Asia, and Africa, while Nicaraguan and Mexican clades grouped close to Africa. In addition, a mixed large LA cluster including Mexican, Colombian, Nicaraguan, Peruvian, and Salvadorian strains was observed; all LA clusters separated from the Amerind clade. With cagPAI sequence analyses LA clades clearly separated from Europe, Asia and Amerind, and Colombian strains formed a single cluster. A NeighborNet analyses suggested frequent and recent recombination events particularly among LA strains. Results suggests that in the new world, H. pylori has evolved to fit mestizo LA populations, already 500 years after the Spanish colonization. This co-adaption may account for regional variability in gastric cancer risk.

ObjectiveHelicobacter pylori (Hp) is a major risk factor for gastric cancer (GC). Hp promotes DNA damage and proteasomal degradation of p53, the guardian of genome stability. Hp reduces the expression of the transcription factor USF1 shown to stabilise p53 in response to genotoxic stress. We investigated whether Hp-mediated USF1 deregulation impacts p53-response and consequently genetic instability. We also explored in vivo the role of USF1 in gastric carcinogenesis.DesignHuman gastric epithelial cell lines were infected with Hp7.13, exposed or not to a DNA-damaging agent camptothecin (CPT), to mimic a genetic instability context. We quantified the expression of USF1, p53 and their target genes, we determined their subcellular localisation by immunofluorescence and examined USF1/p53 interaction. Usf1-/- and INS-GAS mice were used to strengthen the findings in vivo and patient data examined for clinical relevance.ResultsIn vivo we revealed the dominant role of USF1 in protecting gastric cells against Hp-induced carcinogenesis and its impact on p53 levels. In vitro, Hp delocalises USF1 into foci close to cell membranes. Hp prevents USF1/p53 nuclear built up and relocates these complexes in the cytoplasm, thereby impairing their transcriptional function. Hp also inhibits CPT-induced USF1/p53 nuclear complexes, exacerbating CPT-dependent DNA damaging effects.ConclusionOur data reveal that the depletion of USF1 and its de-localisation in the vicinity of cell membranes are essential events associated to the genotoxic activity of Hp infection, thus promoting gastric carcinogenesis. These findings are also of clinical relevance, supporting USF1 expression as a potential marker of GC susceptibility.

Biomarkers may facilitate detection of gastric cancer at an earlier stage and reduce mortality. Here we sought to determine if the glycosylation profile of serum immunoglobulin G (IgG) could distinguish patients with non-atrophic gastritis (NAG), duodenal ulcer (DU) and gastric cancer (GC). Serum IgG was released and analyzed using nano-LC-TOF mass spectrometry. Statistically significant false discovery rate (FDR)-adjusted p-values were observed for 18 glycans, eight that differed significantly between NAG and GC, three that distinguished NAG from DU, and eight that differed between DU and GC. The IgG glycosylation signature may be useful as a predictive marker for gastric cancer.

Infection by Helicobacter pylori affects about 50% of the human population. Of those infected, 10% to 15% will develop peptic ulcer and up to 3% will present with gastric cancer. These estimates suggest that around 7% of the world's population will eventually develop H. pylori -associated gastroduodenal disease. In fact, gastric cancer remains the second cause of cancer mortality worldwide (1). Fortunately, evidence suggests that the prevalence of H. pylori infection is decreasing in developed countries; accordingly, a decrease in peptic ulcer and cancer is also being observed (2). It remains uncertain whether the infection is also decreasing in developing countries. The aim of this review is to present the trend of both H. pylori infection and gastric cancer in Mexico, a country where sanitary and public health conditions have been improving during the last decades.

Tumour Necrosis Factor (TNF) and Heat Shock Protein 70 (HSP70) are important molecules in inflammatory, infectious and tumoral processes. The genes codifying these molecules are polymorphic and certain alleles have been associated with susceptibility to disease. Gastric cancer is associated with an Helicobacter pylori‐induced chronic inflammatory response. The aim of this work was to analyze whether polymorphisms in inflammation‐related genes are associated with the development of gastric cancer. We studied 447 Mexican adult patients including 228 with non‐atrophic gastritis, 98 with intestinal metaplasia, 63 with gastric cancer and 58 with duodenal ulcer, and 132 asymptomatic individuals as well. DNA from peripheral white blood cells was typed for the Single Nucleotide Polymorphisms (SNPs) −308 of TNF‐α, +252 of TNF‐β, +190 of HSP70‐1, +1267 of HSP70‐2 and +2437 of HSP70‐HOM. Compared with the asymptomatic group, we found a significant association of TNF‐β*A and HSP70‐1*C alleles with gastric cancer (OR 5.69 and 3.76, respectively) and HSP70‐1*C with duodenal ulcer (OR 3.08). Genotype TNF‐β G/G showed a significant gene‐dose effect with gastric cancer (OR 0.09); whereas HSP70‐1 C/G showed significant association with both, gastric cancer (OR 13.31) and duodenal ulcer (OR 16.19). Polymorphisms in TNF and HSP70 showed a significant severity‐dose‐response as risk markers from preneoplastic lesions to gastric cancer in Mexican population, probably because of their association with an intense and sustained inflammatory response.

Helicobacter pylori strains frequently express Lewis X (Lex) and/or Ley on their cell surfaces as constituents of the O antigens of their lipopolysaccharide molecules. To assess the effect of Lex and Ley expression on the ability of H. pylori to colonize the mouse stomach and to adhere to epithelial cells, isogenic mutants were created in which fucT1 alone or fucT1 and fucT2, which encode the fucosyl transferases necessary for Lex and Ley expression, were deleted. C3H/HeJ mice were experimentally challenged with either wild-type 26695 H. pylori or its isogenic mutants. All strains, whether passaged in the laboratory or recovered after mouse passage, colonized the mice well and without consistent differences. During colonization by the mutants, there was no reversion to wild type. Similarly, adherence to AGS and KatoIII cells was unaffected by the mutations. Together, these findings indicate that Le expression is not necessary for mouse gastric colonization or for H. pylori adherence to epithelial cells

Mexican children respond to H. pylori infection with a low inflammatory response, a balanced increase of T and B lymphocytes, and a high regenerative activity.