Assessment of the mosaic structure in the Helicobacter pylori cagA gene 3′-region using an improved polymerase chain reaction–based assay

CONTEXT AND OBJECTIVE: The virulence of Helicobacter pylori (HP) in gastroduodenal disease is related to pathogenicity islands (cagPAI) present in some strains. Infection with cagPAI induces IL-8 secretion, increases epithelial cell proliferation and may be important in carcinogenesis. Our objective was to detect HP and the cagA gene (cagPAI marker) by polymerase chain reaction (PCR) and to correlate these results to histological findings, epithelial cell proliferation and apoptosis. DESIGN AND SETTING: Retrospective, at the Surgical and Molecular Pathology Laboratory, Hospital Sírio-Libanês. METHODS: DNA samples isolated from 164 gastric biopsies were used for HP detection by PCR. cagPAI+ was identified in HP+ cases by cagA gene amplification. All cases were submitted to immunohistochemistry to evaluate cell proliferation, and TUNEL to detect apoptosis. Statistical analysis was performed to compare results. RESULTS: HP was detected in 67.7% of the patients, with good correlation between HP infection and moderate to severe gastritis, gastric ulcer and MALT lymphoma. There was a correlation between cagPAI+ strains and severe gastric diseases including cancer. The risk of gastric ulcer, adenocarcinoma and MALT lymphoma was 8.8 times higher for cagPAI+ patients. cagPAI+ infection was related to higher proliferation rates. The proliferation/apoptosis index was significantly higher for cagPAI+ patients. CONCLUSION: Cell growth deregulation in cagPAI+ patients could be demonstrated by the difference in the proliferation index. We believe that this explains the carcinogenic role of Helicobacter pylori.

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Direct detection and analysis of vacA genotypes and cagA gene of Helicobacter pylori from gastric biopsies by a novel multiplex polymerase chain reaction assay

Diagnostic Microbiology and Infectious Disease ◽

10.1016/j.diagmicrobio.2008.07.014 ◽

2008 ◽

Vol 62 (4) ◽

pp. 366-373 ◽

Cited By ~ 8

Author(s):

Sushil Kumar ◽

Ashok Kumar ◽

Vinod Kumar Dixit

Keyword(s):

Polymerase Chain Reaction ◽

Helicobacter Pylori ◽

Polymerase Chain Reaction Assay ◽

Multiplex Polymerase Chain Reaction ◽

Direct Detection ◽

Caga Gene ◽

Chain Reaction ◽

Gastric Biopsies ◽

Polymerase Chain

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

Arquivos de Gastroenterologia ◽

10.1590/s0004-2803.202100000-85 ◽

2021 ◽

Vol 58 (4) ◽

pp. 468-475

Author(s):

Ana Karoline Silva OLIVEIRA ◽

Lucas Luiz de Lima SILVA ◽

Marina Pacheco MIGUEL ◽

Angel José Vieira BLANCO ◽

Lilian Carla CARNEIRO ◽

...

Keyword(s):

Polymerase Chain Reaction ◽

Helicobacter Pylori ◽

Clinical Outcomes ◽

Gastric Adenocarcinoma ◽

Gastric Lymphoma ◽

Caga Gene ◽

Chain Reaction ◽

Increased Risk ◽

Polymerase Chain ◽

H Pylori

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.

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