Genetic differences between Helicobacter pylori strains isolated from patients with chronic mild and severe gastritis

Background. Helicobacter pylori-associated chronic gastritis (CG), being a very heterogeneous group, still does not have a divisin based on Helicobacter pylori (Hp) genotyping data, which could predict the clinical form of CG.The aim of the study is to search for the prevalence of the cagA gene or any allelic combination of the vacA gene, or stable combinations of cagA and any allelic combination of vacA genes in Hp isolates from patients with mild and severe CG, as well as patients with peptic ulcer disease (PUD).Methods. Hp isolates from gastrobiopsy specimens were genotyped for cagA and vacA allelic combinations (s1m1, s2m1, s1m2, s2m2). The difference in the occurrence of vacA allelic combinations was assessed by Mann–Whitney U test; the conjunction of cagA and vacA allelic combinations was assessed by the Spearman's rank correlation coefficient (rs).Results. The cagA gene was found in more than half of all cases, both in patients with ulcer and in patients with CG (mild and severe). The incidence of vacAs1m1 (the most virulent allelic combination) showed no significant differences in all forms of gastritis and in PUD; the correlation between cagA and vacAs1m1 was significant in all groups of patients, rs ranged from 0.57 to 0.72. In patients with mild CG, an abundance of non-virulent allelic combination vacAs2m2 was observed, which was significantly different from its occurrence both in patients with severe CG and in patients with ulcer; the joint occurrence of vacAs2m2 and cagA in patients with mild CG was chaotic (rs=-0.13; P=0.40).Conclusion. In mild CG, despite the absence of significant differences in cagA and vacAs1m1 (when compared with severe CG and ulcer disease), strains with a non-virulent allelic combination vacAs2m2 were significantly dominant; therefore, the detection of this particular allelic combination of vacA speaks in favor of a mild course of CG.

HELICOBACTER PYLORI cagA VIRULENCE GENE AND SEVERE ESOGASTRODUODENAL DISEASES: IS THERE AN ASSOCIATION?

ABSTRACT BACKGROUND: Helicobacter pylori colonizes approximately half of the world’s human population. Its presence in the gastric mucosa is associated with an increased risk of gastric adenocarcinoma, gastric lymphoma, and peptic ulcer disease. In Brazil, the high prevalence of H. pylori infection is a serious health problem. H. pylori virulence factors are associated with an increased risk of serious gastrointestinal disorders. The cagA gene encodes a cytotoxin-A-associated antigen (CagA) that is involved in bacterial pathogenicity. H. pylori strains carrying the cag pathogenicity island (cag-PAI) are significantly associated with severe clinical outcomes and histopathological changes. OBJECTIVE: The present study aims to investigate the prevalence of the cagA gene among H. pylori isolates from patients with different gastric pathologies. Further, the study hopes to verify its association with clinical outcomes. In addition, phylogenetic analysis was performed on cagA-positive H. pylori strains from patients with severe and non-severe diseases. METHODS: Gastric specimens were collected through a biopsy from 117 patients with different esogastroduodenal diseases. DNA was extracted from these gastric specimens and the polymerase chain reaction was performed to amplify the gene fragments corresponding to the 16S ribosomal RNA and cagA genes using specific primers. The polymerase chain reaction products of selected samples positive for cagA were sequenced. The sequences were aligned with reference sequences from the National Center for Biotechnology Information (NCBI) (Bethesda/USA), and a phylogenetic tree was constructed. RESULTS: H. pylori was detected in 65.9% (77/117) of Brazilian patients with different gastroduodenal disorders. Overall, 80.5% (62/77) of the strains were cagA-positive. The ages of patients with cagA-positive strains (15 males and 47 females) ranged from 18 to 74 years. The lesions were categorized as non-severe and severe according to the endoscopic and histopathological reports the most prevalent non-severe esogastroduodenal lesion was gastritis 54/77 (70.12%), followed by esophagitis 12/77 (15.58%) and duodenitis 12/77 (15.58%). In contrast, the most prevalent severe lesions were atrophy 7/77 (9.09%), followed by metaplasia 3/77 (3.86%) and gastric adenocarcinoma 2/77 (2.59%). Phylogenetic analyses performed with the partial sequences of the cagA gene obtained from local strains were grouped in the same clade. No differences in phylogenetic distribution was detected between severe and non-severe diseases. CONCLUSION: The cagA gene is highly prevalent among H. pylori isolates from gastric lesions in Brazilian patients. The presence of the cagA gene was not considered a marker of the severity of esogastroduodenal lesions in the present study. This is the first study to investigate the phylogenetic population structure of H. pylori strains in a Brazilian capital, which may improve our understanding of the clinical outcome of H. pylori infection.

Determine the Prevalence of cagA and Baba of Helicobacter Pylori Isolated from Gastric Atrophic Patients

Objective: The aim of this study is to determine the prevalence of cagA and babA of helicobacter pylori isolated from gastric atrophic patients. Study Design: Descriptive/Analytical Place and Duration: The study was conducted at Medicine/Gastroenterology department of Khyber Teaching Hospital and Peshawar Institute of Medical Sciences, Peshawar for six months duration from March 2020 to August 2020. Methods: Total one hundred and twenty patients of both genders were presented in this study. Patients were aged between 20-80 years of age. Patients detailed demographics age, sex and body mass index were recorded after taking informed written consent. All patients of gastroduodenal disorders were undergone for isolation of bacteria by using standard techniques. Complete data was analyzed by SPSS 22.0 version. Results: Total 50 (41.7%) patients were males and 70 (58.3%) patients were females. Mean age of the patients were 41.96 ± 16 years with mean BMI 25.24 ± 4.8 kg/m2. Frequency of H pylori was isolated in 30 (25%) patients in which 13 patients had atrophic gastritis, 9 patients had gastric ulcer and 8 patients had acute gastritis. Prevalence of cagA gene was 16 (53.33%) and babA was 10 (33.33%) in H. pylori isolated patients. Significantly difference with p value <0.05 was observed between cagA positive strains and patients of gastric atrophic. The involvement of gastric atrophic patients was not correlated to the babA gene. Conclusion: We concluded in this study that different cagA positive H. pylori can be retrieved from gastric atrophy patients. Keywords: Gastric atrophy, Gastric cancer, cagA, babA, Helicobacter pylori

Helicobacter Pylori Variants with ABC-Type Tyrosine Phosphorylation Motif in Gastric Biopsies of Ghanaian Patients

Background. Helicobacter pylori pathogenicity and disease severity are determined by the tyrosine phosphorylation motifs of CagA protein. This study is aimed at detecting the presence of H. pylori and identifying the CagA tyrosine phosphorylation motifs in Ghanaian patients. Material and Methods. A total of 94 archival genomic DNA samples from gastric biopsies were used for the study, and H. pylori was detected by amplifying the 16S rRNA gene. The 3 ′ -end variable region of the cagA gene was amplified, and the entire 3 ′ -end was sequenced and translated into amino acids. Results. H. pylori was detected in 53.2% (50/94) of the samples, and all the detected bacteria harboured the cagA gene. Two variants of the bacteria were identified based on the size of the amplified cagA gene: 207 bp and 285 bp. The 207 bp and 285 bp variants accounted for 74% and 22%, respectively, and 4% showed both fragments. Translated amino acid sequence of the cagA gene showed EPIYA-A, EPIYA-B, and EPIYA-C (ABC type) motifs, indicating the Western variant. The CagA protein C-terminal showed insertion of amino acids in the sequence flanking the EPIYA-A motif at the N-terminal and a complete deletion of the EPIYA-CC and EPIYA-CCC motifs together with the flanking sequences. Conclusions. H. pylori identified were Western variant (ABC type) with unique amino acid insertions, suggesting unique variants in Ghanaian patients. Further investigation is however required to understand the role of the molecular diversity of the variant in gastric disease outcome.

Effect of Helicobacter pylori on Tight Junctions in Gastric Epithelia

Molecular complexes grouped under the names of tight, adherent or gap junction regulate the flow of water, ions and macromolecules through epithelium paracellular spaces. The main constituents of tight junctions are claudins, a family of 26 different proteins whose expression and distribution are tissue specific but varies in tumors. A change in claudin 1, 3, 4, 5, 6, 7, 9 and 18 expression, that contributes to lose epithelial cohesion, has been associated to enhanced cell proliferation, migration, and invasiveness in gastric neoplastic tissue. Chronic inflammation process induced by H. pylori infection, a major risk factor for gastric cancer development, disrupts tight junctions via CagA gene, Cag pathogenicity island, and VacA, but the effect upon the epithelial barrier of H. pylori lipopolysaccharides or H. pylori-induced up-regulation of mTOR and ERK signaling pathways by microRNA-100 establishes new concepts of proof.

Association of cagA, cagC, virB2, and vacA Subtypes of Helicobacter pylori with Adenocarcinoma Development in Iranian Patients

Background: Gastric cancer has been introduced as the second cause of cancer death worldwide. Helicobacter pylori infection is considered one of the main risk factors for this type of cancer, so that it has been classified as group I carcinogens. Objectives: The present research intended to examine the prevalence of cagA, cagC, virB2, vacA, and genotype distribution in H. pylori-infected biopsies and adenocarcinoma cases. Methods: Thirty-four H. pylori gastric biopsies taken from Western Iranian patients that were diagnosed as gastritis, gastric ulcers, and adenocarcinoma were used in this study. Two samples were taken from each patient. These samples were selected based on endoscopic observations and histological examinations. The presence of H. pylori was confirmed by the Rapid Urease test (RUT) and the ureC gene by the polymerase chain reaction (PCR) technique. Then, specific primers for vacA and cagPAI were used for genotyping H. pylori by PCR-typing. Results: The obtained results showed that 86.8% of the samples were H. pylori-positive. Moreover, the cagA gene prevalence was 51.50% in the samples. In addition, the adenocarcinoma outcome was significantly related to all selected genes. Likewise, some gastric diseases such as gastric ulcers, duodenal ulcer (DU), gastritis, lymphoid, and gastroesophageal reflux disease (GERD) were observed in adenocarcinoma cases. It was also found that the vacAs1m1i1 genotype plays an important role in gastric malignancies. The most frequent vacA genotype in the H. pylori-infected isolates was s1m1i1, and the observed frequency of vacA and cagA genes in adenocarcinoma was statistically significant. Conclusions: The findings showed that H. pylori vacA and cagA gene virulence factors are associated with adenocarcinoma in Western Iranian patients.

A DNA Sequence Analysis of Helicobacter pylori in Jeddah City, Western Saudi Arabia

Helicobacter pylori are the type of Gram-negative bacteria which colonize the mucous lining of the human stomach. These bacteria have two major virulence factors: (vacuolating cytotoxin A gene) and (cytotoxin-associated A gene). This study aimed to provide data to determine the prevalent virulence factors (vacA and cagA genes) in Jeddah city, western Saudi Arabia, by sequence analysis. This study included 60 patients with symptoms similar to H. pylori infection. H. pylori were identified by using the 16s rRNA sequence. Then, the screening for specific genes in H. pylori (vacA and cagA) was done by using automated DNA sequencing analysis, and the DNA sequences were compared by BLAST and sequence alignment of the vacA nucleotides that are present in all H. pylori strains using those already reported in GeneBank from various studies. Results indicated that H. pylori infection was detected in 13.3%, while 86.7% were negative samples in our study patients. Interestingly, the vacA gene was found in 8.3%, while the cagA gene was not appear in patient. Also, the female prevalence rate was higher than males (11.7% female versus 1.7% males), and the highest infection was between age 40-49 by 6.7%. In conclusion, this study revealed that the vacA gene was spread in the patients infected with H. pylori in Jeddah, while the cagA gene was not appear in any isolate.

Risk assessment of pathological conditions caused by circulating H. pylori strains

In recent years, there has been an increase in the prevalence of inflammatory and destructive diseases of the gastroduodenal zone, which is primarily explained by Helicobacter pylori (H. pylori) infection. One of the main factors of H. pylori pathogenicity is presence of cytotoxin-associated gene — CagA. It is known that CagA-positive H. pylori strains are associated with the development of atrophy, tumor invasion and rapid metastasis. A number of recently published studies have revealed that CagA is a polymorphic gene which contains a different number of repetitive sequences located in the 3’ region. Each repetitive region of CagA contains Glu-Pro-Ile-Tyr-Ala (EPIYA) profiles including tyrosine phosphorylation. Depending on the sequence of the EPIYA profile, there are 4 segments: EPIYA-A, EPIYA-B, EPIYA-C, EPIYA-D, each containing a repetitive region. Geographical features of the prevalence of H. pylori strains depending on the sequence of EPIYA have been revealed: EPIYA-A region of the western isolates of this bacterium is associated with EPIYA-A, EPIYA-B, EPIYA-C segments, while the eastern CagA-positive H. pylori isolates are characterized by the A-B-D type of the CagA gene. Data illustrating the strong correlation between the western CagA-positive H. pylori strains, which have a repeating EPIYA-C segment, and the development of precancerous states, as well as gastric cancer, are presented. H. pylori strains containing simultaneously A-B motives of EPIYA or one C-type of the CagA gene are associated with a 7-fold increase of risk of gastric cancer compared to CagA-negative strains; presence of two or more EPIYA-C motives is associated with a 30-fold increase of this risk.