Detection of Helicobacter pylori CagA EPIYA in gastric biopsy specimens and its relation to gastric diseases

Amino acid deletions at positions 893 and 894 of cytotoxin-associated gene A protein affect Helicobacter pylori gastric epithelial cell interactions

BACKGROUND

Helicobacter pylori (H. pylori) persistently colonizes the human gastric mucosa in more than 50% of the global population, leading to various gastroduodenal diseases ranging from chronic gastritis to gastric carcinoma. Cytotoxin-associated gene A (CagA) protein, an important oncoprotein, has highly polymorphic Glu-Pro-Ile-Tyr-Ala segments at the carboxyl terminus, which play crucial roles in pathogenesis. Our previous study revealed a significant association between amino acid deletions at positions 893 and 894 and gastric cancer.

AIM

To investigate the impact of amino acid deletions at positions 893 and 894 on CagA function.

METHODS

We selected a representative HZT strain from a gastric cancer patient with amino acid deletions at positions 893 and 894. The cagA gene was amplified and mutated into cagA-NT and cagA-NE (sequence characteristics of strains from nongastric cancer patients), cloned and inserted into pAdtrack-CMV, and then transfected into AGS cells. The expression of cagA and its mutants was examined using real-time polymerase chain reaction and Western blotting, cell elongation via cell counting, F-actin cytoskeleton visualization using fluorescence staining, and interleukin-8 (IL-8) secretion via enzyme-linked immunosorbent assay.

RESULTS

The results revealed that pAdtrack/cagA induced a more pronounced hummingbird phenotype than pAdtrack/cagA-NT and pAdtrack/cagA-NE (40.88 ± 3.10 vs 32.50 ± 3.17, P < 0.001 and 40.88 ± 3.10 vs 32.17 ± 3.00, P < 0.001) at 12 hours after transfection. At 24 hours, pAdtrack/cagA-NE induced significantly fewer hummingbird phenotypes than pAdtrack/cagA and pAdtrack/cagA-NT (46.02 ± 2.12 vs 53.90 ± 2.10, P < 0.001 and 46.02 ± 2.12 vs 51.15 ± 3.74, P < 0.001). The total amount of F-actin caused by pAdtrack/cagA was significantly lower than that caused by pAdtrack/cagA-NT and pAdtrack/cagA-NE (27.54 ± 17.37 vs 41.51 ± 11.90, P < 0.001 and 27.54 ± 17.37 vs 41.39 ± 14.22, P < 0.001) at 12 hours after transfection. Additionally, pAdtrack/cagA induced higher IL-8 secretion than pAdtrack/cagA-NT and pAdtrack/cagA-NE at different times after transfection.

CONCLUSION

Amino acid deletions at positions 893 and 894 enhance CagA pathogenicity, which is crucial for revealing the pathogenic mechanism of CagA and identifying biomarkers of highly pathogenic H. pylori.

Virulence gene polymorphisms in Shandong Helicobacter pylori strains and their relevance to gastric cancer

BACKGROUND

Helicobacter pylori (H. pylori) virulence factors, particularly the cagA and vacA genotypes, play important roles in the pathogenic process of gastrointestinal disease.

METHODS

The cagA and vacA genotypes of 87 H. pylori strains were determined by PCR and sequencing. The EPIYA and CM motif patterns were analyzed and related to clinical outcomes. We examined the associations between the virulence genes of H. pylori and gastrointestinal diseases in Shandong, and the results were analyzed via the chi-square test and logistic regression model.

RESULTS

Overall, 76 (87.36%) of the strains carried the East Asian-type CagA, with the ABD types being the most prevalent (90.79%). However, no significant differences were observed among the different clinical outcomes. The analysis of CagA sequence types revealed 8 distinct types, encompassing 250 EPIYA motifs, including 4 types of EPIYA or EPIYA-like sequences. Additionally, 28 CM motifs were identified, with the most prevalent patterns being E (66.67%), D (16.09%), and W-W (5.75%). Notably, a significant association was discovered between strains with GC and the CM motif pattern D (P < 0.01). With respect to the vacA genotypes, the strains were identified as s1, s2, m1, m2, i1, i2, d1, d2, c1, and c2 in 87 (100%), 0 (0), 26 (29.89%), 61 (70.11%), 73 (83.91%), 14 (16.09%), 76 (87.36%), 11 (12.64%), 18 (20.69%), and 69 (79.31%), respectively. Specifically, the vacA m1 and c1 genotypes presented a significantly greater prevalence in strains from GC compared to CG (P < 0.05). Following adjustment for age and sex, the vacA c1 genotype demonstrated a notable association with GC (OR = 5.174; 95% CI, 1.402-20.810; P = 0.012). This association was both independent of and more pronounced than the correlations between vacA m1 and GC.

CONCLUSIONS

CagA proteins possessing CM motif pattern D were more frequently observed in patients with GC (P < 0.01), implying a potentially higher virulence of CM motif pattern D than the other CM motif patterns. Moreover, a strong positive association was identified between the vacA c1 genotype and GC, indicating that the vacA c1 genotype is a robust risk indicator for GC among male patients aged ≥55 years in Shandong.

Helicobacter pylori cagA, vacA, iceA and babA Genotypes from Peruvian Patients with Gastric Intestinal Metaplasia

We explored the clinical-stage association of gastric intestinal metaplasia (IM) compared to cases of chronic non-atrophic gastritis (CNAG) and its relationship with virulence genotypes of Helicobacter pylori (H. pylori) clinical isolates from patients with dyspepsia in Peru. This study was cross-sectional and included 158 H. pylori clinical isolates; each isolate corresponded to a different Peruvian patient, genotyped by polymerase chain reaction to detect cagA gene and EPIYA motifs, the vacA gene (alleles s1, s2, i1, i2, d1, d2, m1, m2 and subtypes s1a, s1b and s1c), the iceA gene (alleles 1 and 2), and the babA gene (allele 2). We observed that 38.6% presented with IM and that all clinical isolates were CagA positive. The EPIYA-ABC motif was predominant (68.4%), and we observed a high frequency for the vacA gene alleles s1 (94.9%), m1 (81.7%), i1 (63.9%), and d1 (70.9%). Strains with both iceA alleles were also detected (69.6%) and 52.2% were babA2 positive. In addition, it was observed that the cagA+/vacAs1m1 (PR: 2.42, 1.14 to 5.13, p < 0.05) and cagA+/vacAs1am1 (PR: 1.67, 1.13 to 2.45, p < 0.01) genotypes were associated with IM. Our findings revealed the cagA and vacA risk genotypes predominance, and we provided clinically relevant associations between Peruvian patients with H. pylori infection and IM clinical stage.

An Overview of Autophagy in Helicobacter pylori Infection and Related Gastric Cancer

Helicobacter pylori (H. pylori) infection is considered a class I carcinogen in the pathogenesis of gastric cancer. In recent years, the interaction relationship between H. pylori infection and autophagy has attracted increasing attention. Most investigators believe that the pathogenesis of gastric cancer is closely related to the formation of an autophagosome-mediated downstream signaling pathway by H. pylori infection-induced cells. Autophagy is involved in H. pylori infection and affects the occurrence and development of gastric cancer. In this paper, the possible mechanism by which H. pylori infection affects autophagy and the progression of related gastric cancer signaling pathways are reviewed.

Determination of CagA EPIYA motif in Helicobacter pylori strains isolated from patients with digestive disorder

This study was conducted to identify patterns of cagA EPIYA motifs in H. pylori strains isolated from patients with gastrointestinal diseases in Hospitals of Shahrekord, and investigate the association between these biomarkers and clinical outcomes of gastrointestinal diseases due to H. pylori. In this study, 253 patients with gastrointestinal diseases were studied within 1395-1396. Histopathological investigations and urease test showed that 207 isolates were H. pylori-positive. Then, screening using a molecular technique, PCR, confirmed that 159 isolates had cagA. Finally, the pattern and prevalence of the motifs were determined by PCR and identified a number of motifs were sequenced. Results of this study showed that the pattern of motifs was as follows: ABC (140 isolates) (93/7%), ABCC (6 isolates) (3/77%), ABCCC (4 isolates) (2/5%), AB (7 isolates) (4/4%), AC (1 isolate) (0/6%), and BC (1 isolate) (0/6%). Sequencing results showed the presence of changed EPIYA motif in some isolates. CM motif sequence was also seen in all isolates. In this study, no significant association was seen between the prevalence rate of different patterns and clinical symptoms (p = 0.71). There is a slight association between the presence of ABC motifs and the type of digestive disorder (p = 0.056). Results indicated that ABC was the most frequently seen pattern however, in such that positive cases of ABC motifs were more common in gastritis. All isolates had kinase phosphorylation region, and the observed pattern in this region was a generally western type (ABC).

Genetic diversity and virulence characteristics of Helicobacter pylori isolates in different human ethnic groups

Helicobacter pylori is the most predominant bacterium in almost 50% of the world's population and colonization causes a persistent inflammatory response leading to chronic gastritis. It shows high genetic diversity and individuals generally harbour a distinct bacterial population. With the advancement of whole-genome sequencing technology, new H. pylori subpopulations have been identified that show admixture between various H. pylori strains. Genotypic variation of H. pylori may be related to the presence of virulence factors among strains and is associated with different outcomes of infection in different individuals. This review summarizes the genetic diversity in H. pylori strain populations and its virulence characteristics responsible for variable outcomes in different ethnic groups.

The interplay between mutations in cagA, 23S rRNA, gyrA and drug resistance in Helicobacter pylori

In this study, we evaluated the mutations of Helicobacter pylori associated with resistance to clarithromycin and levofloxacin. Furthermore, based on the proposed interaction between antimicrobial resistance and pathogenicity, we correlated the mutation profiles of the strains with the presence of the pathogenicity gene cagA. We analyzed 80 gastric biopsy specimens from H. pylori-infected patients for point mutations in the 23S rRNA gene region and in the gyrA gene, which are related to clarithromycin and levofloxacin resistance, respectively, and investigated the presence of the cagA gene in these strains. We observed that in the assayed biopsies, 8.7% (7/80) had mutations in the 23S rRNA gene region at positions 2143 and 2142, while 22.5% (18/80) had mutations in gyrA at codons 87 and 91. Moreover, absence of the CagA-EPIYA pathogenicity factor was observed in 68% (17/25) of resistant samples. The knowledge of the local profile of antimicrobial resistance and the complex interplay involving resistance and pathogenicity can contribute to an appropriate clinical approach.

New insights of Helicobacter pylori host-pathogen interactions: The triangle of virulence factors, epigenetic modifications and non-coding RNAs

Helicobacter pylori (H. pylori) is a model organism for understanding host-pathogen interactions and infection-mediated carcinogenesis. Gastric cancer and H. pylori colonization indicates the strong correlation. The progression and exacerbation of H. pylori infection are influenced by some factors of pathogen and host. Several virulence factors involved in the proper adherence and attenuation of immune defense to contribute the risk of emerging gastric cancer, therefore analysis of them is very important. H. pylori also modulates inflammatory and autophagy process to intensify its pathogenicity. From the host regard, different genetic factors particularly affect the development of gastric cancer. Indeed, epigenetic modifications, MicroRNA and long non-coding RNA received more attention. Generally, various factors related to pathogen and host that modulate gastric cancer development in response to H. pylori need more attention due to develop an efficacious therapeutic intervention. Therefore, this paper will present a brief overview of host-pathogen interaction especially emphases on bacterial virulence factors, interruption of host cellular signaling, the role of epigenetic modifications and non-coding RNAs.

Association of CagA EPIYA-D or EPIYA-C phosphorylation sites with peptic ulcer and gastric cancer risks: A meta-analysis

BACKGROUND

Increasingly, studies have focused on the relationship between Helicobacter pylori (H pylori) cytotoxin associated gene A protein (CagA) Glu-Pro-Ile-Tyr-Ala (EPIYA)-D motifs or multiple EPIYA-C phosphorylation sites and peptic ulcer disease (PUD) or gastric cancer (GC) risk. However, the conclusions have been inconsistent. The aim of this meta-analysis was to evaluate whether 1 CagA EPIYA-D motif or multiple EPIYA-C phosphorylation sites were associated with PUD or GC risk.

MATERIALS AND METHODS

A literature search was performed in PubMed, Web of Science, Wanfang Data, Excerpt Medica Database, and the Chinese National Knowledge Infrastructure database to identify eligible research. We analyzed the odds ratios (OR) and 95% confidence intervals (CI) to assess the strength of association.

RESULTS

Compared with 1 EPIYA-C motif in Asian populations, 1 EPIYA-D site was associated with an increased GC risk (OR=1.91, 95% CI=1.19-3.07, P = .008). However, 1 EPIYA-D motif was not significantly associated with PUD (OR = 0.90, 95% CI = 0.46-1.76, P = .764), gastric ulcer (GU) (OR = 0.85, 95% CI = 0.27-2.63, P = .771), or duodenal ulcer (DU) (OR = 0.89, 95% CI = 0.25-3.16, P = .859) risk. Compared with no more than 1 EPIYA-C motif, multiple motifs were associated with increased PUD (OR = 2.33, 95% CI = 1.29-4.20, P = .005) and DU (OR = 2.32, 95% CI = 1.08-5.00, P = .031) risk in Asia and GC risk in the United States and Europe (OR = 3.28, 95% CI = 2.32-4.64, P < .001). Multiple EPIYA-C sites were not associated with GU risk (OR = 4.54, 95% CI = 0.95-21.83, P = .059). There was no publication bias identified in these comparisons.

CONCLUSIONS

In Asia, 1 EPIYA-D motif was significantly associated with increased GC risk. Multiple EPIYA-C motifs were associated with increased PUD and DU risk, particularly in Asia. In the United States and Europe, multiple EPIYA-C motifs were associated with increased GC risk. Therefore, detection of polymorphic CagA EPIYA motifs may improve clinical prediction of disease risk.