Jorge M. B. Vítor

Transmission pathway of Helicobacter pylori: does food play a role in rural and urban areas?

Helicobacter pylori is a Gram-negative microaerophilic bacterium that has colonized the human gastric mucosa. This infection is very common and affects more than half of the human population. The prevalence is however unbalanced between rural developing areas (more than 80%) and urban developed areas (less than 40%). H. pylori is responsible for several pathologies, such as gastritis, peptic ulcer and gastric cancer but its transmission pathway is still not clear. The risk factors for H. pylori infection include poor social and economic development; poor hygienic practices; absence of hygienic drinking water; and unsanitary prepared food. There is evidence supporting a gastro-oral, oral-oral and faecal-oral transmission, but no predominant mechanism of transmission has been yet identified. Transmission may occur in a vertical mode (e.g. from parents to child) or in a horizontal mode (across individuals or from environmental contamination). In either case, the involvement of water and food cannot be excluded as vehicles or sources of infection. Indirect evidence of presence of H. pylori in water and food, namely the detection of its DNA and survival studies after artificial contamination of food and water has been described. This paper reviews data both favourable and against the role of water and food in the transmission of H. pylori, exploring their role as a potential transmission vehicle for person-to-person and food-chain transmission. The likelihood of the transmission pathway in developing rural and developed urban areas appears to be different. In developed areas, person-to-person transmission within families appears to be dominant, while in the rural developing areas the transmission pathway appears to be more complex. In this later case, the transmission by contaminated food, water, or via intensive contact between infants and non-parental caretakers may have a greater influence than within-family transmission.

Alternative therapies for Helicobacter pylori: probiotics and phytomedicine

Helicobacter pylori is a common human pathogen infecting about 30% of children and 60% of adults worldwide and is responsible for diseases such as gastritis, peptic ulcer and gastric cancer. Treatment against H. pylori is based on the use of antibiotics, but therapy failure can be higher than 20% and is essentially due to an increase in the prevalence of antibiotic-resistant bacteria, which has led to the search for alternative therapies. In this review, we discuss alternative therapies for H. pylori, mainly phytotherapy and probiotics. Probiotics are live organisms or produced substances that are orally administrated, usually in addition to conventional antibiotic therapy. They may modulate the human microbiota and promote health, prevent antibiotic side effects, stimulate the immune response and directly compete with pathogenic bacteria. Phytomedicine consists of the use of plant extracts as medicines or health-promoting agents, but in most cases the molecular mode of action of the active ingredients of these herbal extracts is unknown. Possible mechanisms include inhibition of H. pylori urease enzyme, disruption of bacterial cell membrane, and modulation of the host immune system. Other alternative therapies are also reviewed.

Geographic distribution of methyltransferases of Helicobacter pylori: evidence of human host population isolation and migration

BackgroundHelicobacter pylori colonizes the human stomach and is associated with gastritis, peptic ulcer, and gastric cancer. This ubiquitous association between H. pylori and humans is thought to be present since the origin of modern humans. The H. pylori genome encodes for an exceptional number of restriction and modifications (R-M) systems. To evaluate if R-M systems are an adequate tool to determine the geographic distribution of H. pylori strains, we typed 221 strains from Africa, America, Asia, and Europe, and evaluated the expression of different 29 methyltransferases.ResultsIndependence tests and logistic regression models revealed that ten R-M systems correlate with geographical localization. The distribution pattern of these methyltransferases may have been originated by co-divergence of regional H. pylori after its human host migrated out of Africa. The expression of specific methyltransferases in the H. pylori population may also reflect the genetic and cultural background of its human host. Methyltransferases common to all strains, M. HhaI and M. NaeI, are likely conserved in H. pylori, and may have been present in the bacteria genome since the human diaspora out of Africa.ConclusionThis study indicates that some methyltransferases are useful geomarkers, which allow discrimination of bacterial populations, and that can be added to our tools to investigate human migrations.

Genomic methylation: a tool for typing Helicobacter pylori isolates

ABSTRACT The genome sequences of three Helicobacter pylori strains revealed an abundant number of putative restriction and modification (R-M) systems within a small genome (1.60 to 1.67 Mb). Each R-M system includes an endonuclease that cleaves a specific DNA sequence and a DNA methyltransferase that methylates either adenosine or cytosine within the same DNA sequence. These are believed to be a defense mechanism, protecting bacteria from foreign DNA. They have been classified as selfish genetic elements; in some instances it has been shown that they are not easily lost from their host cell. Possibly because of this phenomenon, the H. pylori genome is very rich in R-M systems, with considerable variation in potential recognition sequences. For this reason the protective aspect of the methyltransferase gene has been proposed as a tool for typing H. pylori isolates. We studied the expression of H. pylori methyltransferases by digesting the genomic DNAs of 50 strains with 31 restriction endonucleases. We conclude that methyltransferase diversity is sufficiently high to enable the use of the genomic methylation status as a typing tool. The stability of methyltransferase expression was assessed by comparing the methylation status of genomic DNAs from strains that were isolated either from the same patient at different times or from different stomach locations (antrum and corpus). We found a group of five methyltransferases common to all tested strains. These five may be characteristic of the genetic pool analyzed, and their biological role may be important in the host/bacterium interaction.

Proteome variability among Helicobacter pylori isolates clustered according to genomic methylation

To understand whether the variability found in the proteome of Helicobacter pylori relates to the genomic methylation, virulence and associated gastric disease.

Genomic structure and insertion sites of Helicobacter pylori prophages from various geographical origins.

Helicobacter pylori genetic diversity is known to be influenced by mobile genomic elements. Here we focused on prophages, the least characterized mobile elements of H. pylori. We present the full genomic sequences, insertion sites and phylogenetic analysis of 28 prophages found in H. pylori isolates from patients of distinct disease types, ranging from gastritis to gastric cancer, and geographic origins, covering most continents. The genome sizes of these prophages range from 22.6–33.0 Kbp, consisting of 27–39 open reading frames. A 36.6% GC was found in prophages in contrast to 39% in H. pylori genome. Remarkably a conserved integration site was found in over 50% of the cases. Nearly 40% of the prophages harbored insertion sequences (IS) previously described in H. pylori. Tandem repeats were frequently found in the intergenic region between the prophage at the 3′ end and the bacterial gene. Furthermore, prophage genomes present a robust phylogeographic pattern, revealing four distinct clusters: one African, one Asian and two European prophage populations. Evidence of recombination was detected within the genome of some prophages, resulting in genome mosaics composed by different populations, which may yield additional H. pylori phenotypes.

Probiotics as an Alternative Therapy for Helicobacter pylori -Associated Diseases

Probiotics are live microorganisms which, when administered in adequate amounts, confer a health benefit to the host. Probiotics are not part of the current treatment therapies prescribed for Helicobacter pylori eradication, but there are numerous studies, most of them using probiotics as adjuvants to therapy, showing a reduction of side effects in the greater majority of cases. The probiotics administered vary hugely in the composition of microorganisms used, as well as the duration and mode of administration, which renders the comparison difficult. However, the most used probiotics for H. pylori infection are composed of Lactobacillus, Bifidobacterium, Saccharomyces, and Streptococcus. The mode of action of these probiotics relies on competition for nutrients and for adhesion to cell receptors, antimicrobial activity, and modulation of the immune system and microbiota.

Proteome analysis of clustered helicobacter pylori strains

no.: WS1.1 HELICOBACTER PYLORI INFECTION AND MARKERS OF GASTRIC CANCER RISK IN ALASKA NATIVE PEOPLE J. Keck,* K. Miernyk,* L. Bulkow,* J. Kelly, B. McMahon, F. Sacco, T. Hennessy* and M. G. Bruce* *Centers for Disease Control and Prevention, Anchorage, AK, USA; Alaska Native Tribal Health Consortium, Anchorage, AK, USA Background: Alaska Native gastric cancer incidence and mortality rates are 3 to 4-times higher than general US population rates. We evaluated pepsinogen I, pepsinogen I/II ratio, anti-H. pylori and CagA antibodies, and blood group to determine their association with gastric cancer development in Alaska Native people. Methods: We conducted a retrospective case-control study that matched gastric cancers reported to the Alaska Native Tumor Registry from 1969–2008 to three controls on known demographic risk factors for H. pylori infection, using previously collected sera from the Alaska Area Specimen Bank. Conditional logistic regression evaluated the associations between serum markers and gastric cancer. Results: We included 122 gastric cancer cases with sera predating cancer diagnosis (mean = 13 years) and 346 matched controls. One hundred and twelve cases (91.8%) and 285 controls (82.4%) had evidence of previous or ongoing H. pylori infection as measured by anti-H. pylori antibodies. Gastric cancer cases had 2.63-fold increased odds of positive anti-H. pylori antibodies compared with their matched controls (p = .01). In a multivariate model, non-cardia gastric cancer (n = 94) was associated with anti-H. pylori antibodies (adjusted OR 3.92, p = .004) and low pepsinogen I (aOR 6.04, p = .04). We found no association between gastric cancer and blood group, anti-CagA antibodies, or pepsinogen I/II ratio. Conclusions: Alaska Native people with gastric cancer had increased odds of previous H. pylori infection. Low pepsinogen I might function as a pre-cancer marker for non-cardia cancer. Impact: Future research to identify Alaska Native individuals with increased gastric cancer risk includes H. pylori genotype and host characteristic studies. Abstract no.: WS1.2 CLUSTERING OF HELICOBACTER PYLORI STRAINS FROM GASTRIC CANCER C. Wang, S. Zhan and Q. Dong Qingdao Municipal Hospital, Qingdao City, Chinano.: WS1.2 CLUSTERING OF HELICOBACTER PYLORI STRAINS FROM GASTRIC CANCER C. Wang, S. Zhan and Q. Dong Qingdao Municipal Hospital, Qingdao City, China Genetic differences between strains play an important role in the determination of clinical outcomes of Helicobacter pylori infection. This study aimed to determine the sequencing types of H. pylori strains from gastric cancer. Materials and Methods: Twenty-two strains of H. pylori were enrolled, including 12 strains from patients with gastric cancer. MLST was used to determine the sequencing type. Results: The seven genetic loci of H. pylori were PCR amplified and sequenced. Those sequences of the seven genes were concatenated, and aligned with the sequences of strains from Europe (5), Africa (5), Asia (5) and other parts of China (16) extracted from the MLST database. A neighbour-joining tree with a kimura 2-parameter model was subsequently constructed. The results showed that all 22 strains, as well as Asia strains from database fell into the HpEastAsia haplogroup which could divided into two groups, groups I and II. Group I consisted of seven cancer strains but only one non-cancer strain of H. pylori, in addition to five strains form database. Fisher’s exact test revealed a statistically significant difference (p = .027). Discussion and Conclusion: The clustering of cancer strains of H. pylori is consistent with a recent report showing that the phylogeopraphic origin of H. pylori is a determinant of gastric cancer risk. This may reflect the consequence of long-term interaction of the bacterium with individual hosts of different genetic ground. The results suggested that the sequencing types could possibly be used to predict the clinical outcomes of H. pylori infection. Abstract no.: WS1.3 LACK OF ASSOCIATION BETWEEN GENE POLYMORPHISMS OF ANGIOTENSIN CONVERTING ENZYME, NOD-LIKE RECEPTOR 1, TOLL-LIKE RECEPTOR 4 AND FAS/FASL WITH THE PRESENCE OF HELICOBACTER PYLORI-INDUCED PREMALIGNANT GASTRIC LESIONS AND GASTRIC CANCER IN CAUCASIANS J. Kupcinskas,* T. Wex, J. Bornschein, M. Selgrad, M. Leja, L. Jonaitis* and P. Malfertheiner *Department of Gastroenterology, Lithuanian University of Health Sciences, Kaunas, Lithuania; Clinic of Gastroenterology, Hepatology and Infectious Diseases, Otto von Guericke University, Magdeburg, Germany; Faculty of Medicine, University of Latvia, Digestive Diseases Center, Hospital Lizeners, Riga, Latvia Background: Several polymorphisms of genes involved in the immunological recognition of Helicobacter pylori and regulating apoptosis and proliferation have been linked to gastric carcinogenesis, however reported data are partially conflicting. The aim of our study was to evaluate potential associations between the presence of gastric cancer (GC) and high risk atrophic gastritis (HRAG) and polymorphisms of genes encoding Angiotensin converting enzyme (ACE), Nod-like receptor 1 (NOD1), Toll-like receptor 4 (TLR4) and FAS/FASL. Methods: Gene polymorphisms were analyzed in 574 subjects (GC: n = 114; HRAG: n = 222, controls: n = 238) of Caucasian origin. ACE I/D (rs4646994), NOD1 796G>A (rs5743336), TLR4 3725G>C (rs11536889), FAS 1377G>A (rs2234767), FAS 670A>G (rs1800682) and FASL 844T>C (rs763110) were genotyped by different PCR approaches and RFLP analysis. Results: Frequencies of genotypes in our study are similar to the data reported on subjects of Caucasian ethnicity. There was a tendency for NOD1 796G/G genotype to be associated with increased risk of HRAG (62.4% vs 54.5% in controls, p = .082). FAS 670G/G genotype was more frequent in HRAG when compared to controls, 23.9% and 17.2% respectively, however it failed to reach significance level (p = .077). We did not find any significant associations for all examined polymorphism in relation to GC or HRAG. NOD1 796G>A and TLR4 3725G>C gene polymorphisms were also not linked with Helicobacter pylori seropositivity status. Conclusions: ACE, NOD1, TRL4 and FAS/FASL gene polymorphisms are not linked with gastric carcinogenesis in Caucasians, and therefore they should not be considered as potential biomarkers for identifying individuals with higher risk for GC. Abstract no.: WS1.4 ATROPHIC GASTRITIS BY THE OLGA STAGES AND HELICOBACTER CAGA SEROPOSITIVITY IN GASTRIC CANCER T. Vorobjova,* K. Kull,* H. Saar,* R. Labotkin,* A. Zimmermann and H. Maaroos* *University of Tartu, Tartu, Estonia; University of Bern, Bern, Switzerlandno.: WS1.4 ATROPHIC GASTRITIS BY THE OLGA STAGES AND HELICOBACTER CAGA SEROPOSITIVITY IN GASTRIC CANCER T. Vorobjova,* K. Kull,* H. Saar,* R. Labotkin,* A. Zimmermann and H. Maaroos* *University of Tartu, Tartu, Estonia; University of Bern, Bern, Switzerland Introduction: Operative Link on Gastritis Assessment (OLGA) express extent of gastric atrophy in terms of gastritis staging, which severity should be related to gastric cancer. Aim: To study how the OLGA stages of atrophic gastritis are associated with the morphological type, and Helicobacter pylori CagA positivity in gastric cancer. Patients: Twenty two gastric carcinoma patients (8 male, 14 female; mean age 64 ± 12) were operated on. The intestinal type of carcinoma was diagnosed in 12, diffuse in 8, mixed and indeterminate type in two cases (according to Lauren). Methods: Gastric mucosa samples (altogether up to 15) from the each operation specimen were stained with haematoxylin and eosin. Tissue material was received from the primary tumour and the tumour surrounding antral and corpus mucosa. The stage of atrophy by OLGA was established by combining the extent of histologically scored atrophy with the topography of atrophy. IgG antibodies to H. pylori cell surface proteins and CagA were evaluated using ELISA. Results: Of the 12 patients with intestinal type of gastric cancer eight had OLGA stage III or IV, four had OLGA stage II and nobody had OLGA stage I (p < .05). Five patients with diffuse cancer had OLGA stage I and II, two had III stage and one had IV stage. There was no association of OLGA stage or cancer type with CagA positivity. Conclusion: Gastric cancer patients represented all stages of gastric atrophy from OLGA stage I to OLGA stage IV which was not associated with cancer type and CagA seropositivity. a 2011 Blackwell Publishing Ltd, Helicobacter 16 (Suppl. 1): 77–143 79 WS1 Gastric Cancer