Genetic affinities of Helicobacter pylori isolates from ethnic Arabs in Kuwait

What constitutes an Arabian Helicobacter pylori? Lessons from comparative genomics

BACKGROUND

Helicobacter pylori, the human gastric pathogen, causes a variety of gastric diseases ranging from mild gastritis to gastric cancer. While the studies on H. pylori are dominated by those based on either East Asian or Western strains, information regarding H. pylori strains prevalent in the Middle East remains scarce. Therefore, we carried out whole-genome sequencing and comparative analysis of three H. pylori strains isolated from three native Arab, Kuwaiti patients.

MATERIALS AND METHODS

H. pylori strains were sequenced using Illumina platform. The sequence reads were filtered and draft genomes were assembled and annotated. Various pathogenicity-associated regions and phages present within the genomes were identified. Phylogenetic analysis was carried out to determine the genetic relatedness of Kuwaiti strains to various lineages of H. pylori. The core genome content and virulence-related genes were analyzed to assess the pathogenic potential.

RESULTS

The three genomes clustered along with HpEurope strains in the phylogenetic tree comprising various H. pylori lineages. A total of 1187 genes spread among various functional classes were identified in the core genome analysis. The three genomes possessed a complete cagPAI and also retained most of the known outer membrane proteins as well as virulence-related genes. The cagA gene in all three strains consisted of an AB-C type EPIYA motif.

CONCLUSIONS

The comparative genomic analysis of Kuwaiti H. pylori strains revealed a European ancestry and a high pathogenic potential.

Association between Helicobacter pylori genotypes and severity of chronic gastritis, peptic ulcer disease and gastric mucosal interleukin-8 levels: Evidence from a study in the Middle East

Background

The varied clinical presentations of Helicobacter pylori (H. pylori) infection are most likely due to differences in the virulence of individual strains, which determines its ability to induce production of interleukin-8 (IL-8) in the gastric mucosa. The aim of this study was to examine association between cagA, vacA-s1 and vacA-s2 genotypes of H. pylori and severity of chronic gastritis and presence of peptic ulcer disease (PUD), and to correlate these with IL-8 levels in the gastric mucosa.

Methods

Gastric mucosal biopsies were obtained from patients during esophagogastroduodenoscopy. The severity of chronic gastritis was documented using the updated Sydney system. H. pylori cagA and vacA genotypes were detected by PCR. The IL-8 levels in the gastric mucosa were measured by ELISA.

Results

H. pylori cagA and/or vacA genotypes were detected in 99 patients (mean age 38.4±12.9; 72 males), of whom 52.5% were positive for cagA, 44.4% for vacA-s1 and 39.4% for vacA-s2; and 70.7% patients had PUD. The severity of inflammation in gastric mucosa was increased with vacA-s1 (p=0.017) and decreased with vacA-s2 (p=0.025), while cagA had no association. The degree of neutrophil activity was not associated with either cagA or vacA-s1, while vacA-s2 was significantly associated with decreased neutrophil activity (p=0.027). PUD was significantly increased in patients with cagA (p=0.002) and vacA-s1 (p=0.031), and decreased in those with vacA-s2 (p=0.011). The level of IL-8 was significantly increased in patients with cagA (p=0.011) and vacA-s1 (p=0.024), and lower with vacA-s2 (p=0.004). Higher levels of IL-8 were also found in patients with a more severe chronic inflammation (p=0.001), neutrophil activity (p=0.007) and those with PUD (p=0.001).

Conclusions

Presence of vacA-s1 genotype of H. pylori is associated with more severe chronic inflammation and higher levels of IL-8 in the gastric mucosa, as well as higher frequency of PUD. Patients with vacA-s2 have less severe gastritis, lower levels of IL-8, and lower rates of PUD. The presence of cagA genotype is not associated with the severity of gastritis or IL-8 induction in the gastric mucosa. The association of cagA with PUD may be a reflection of its presence with vacA-s1 genotype.

Study of Helicobacter pylori genotype status in cows, sheep, goats and human beings

Background

Helicobacter pylori is one of the most controversial bacteria in the world causing diverse gastrointestinal diseases. The transmission way of this bacterium still remains unknown. The possibility of zoonotic transmission of H. pylori has been suggested, but is not proven in nonprimate reservoirs. In the current survey, we investigate the presence of H. pylori in cow, sheep and goat stomach, determine the bacterium virulence factors and finally compare the human H. pylori virulence factors and animals in order to examine whether H. pylori might be transmitted from these animals to human beings.

Methods

This cross- sectional study was performed on 800 gastric biopsy specimens of cows, sheep, goats and human beings. The PCR assays was performed to detection of H. pylori, vacA and cagA genes. The PCR products of Ruminant’s samples with positive H. pylori were subjected to DNA sequencing analysis. Statistical tests were applied for data analysis.

Results

Overall 6 (3%) cows, 32 (16%) sheep and 164 (82%) human beings specimens were confirmed to be H. pylori positive; however we were not able to detect this bacterium in all 200 goat samples. The vacA s1a/m1a was the predominant H. pylori genotype in all three kinds of studied population. There was 3.4–8.4% variability and 92.9-98.5% homology between sheep and human samples.

Conclusions

Considering the high sequence homology among DNA of H. pylori isolated from sheep and human, our data suggest that sheep may act as a reservoir for H. pylori and in the some extent share the ancestral host for the bacteria with human.

Phylogenetic analysis of Helicobacter pylori cagA gene of Turkish isolates and the association with gastric pathology

Background

The cagA gene is one of the important virulence factors of Helicobacter pylori. The diversity of cagA 5′ conserved region is thought to reflect the phylogenetic relationships between different H. pylori isolates and their association with peptic ulceration. Significant geographical differences among isolates have been reported. The aim of this study is to compare Turkish H. pylori isolates with isolates from different geographical locations and to correlate the association with peptic ulceration.

Methods

Total of 52 isolates of which 19 were Turkish and 33 from other geographic locations were studied. Gastric antral biopsies collected from 19 Turkish patients (Gastritis = 12, ulcer = 7) were used to amplify the cagA 5′ region by PCR then followed by DNA sequencing.

Results

The phylogenetic tree displayed 3 groups: A) a mix of 2 sub-groups “Asian” and “African/Anatolian/Asian/European”, B) “Anatolian/European” and C) “American-Indian”. Turkish H. pylori isolates clustered in the mixed sub-group A were mostly from gastritis patients while those clustered in group B were from peptic ulcer patients. A phylogenetic tree constructed for our Turkish isolates detected distinctive features among those from gastritis and ulcer patients. We have found that 2/3 of the gastritis isolates were clustered alone while 1/3 was clustered together with the ulcer isolates. Several amino acids were found to be shared between the later groups but not with the first group of gastritis.

Conclusions

This study provided an additional insight into the profile of our cagA gene which implies a relationship in geographic locations of the isolates.