Aims Helicobacter pylori infection is the major cause of peptic ulceration and gastric cancer, and an important virulence determinant is its vacuolating cytotoxin vacA. Previously, we have described allelic variation in vacA which determines toxin activity and disease risk. Here we aimed to quantify vacA mRNA expression in the human stomach, define its genetic determinants and assess how well it predicts gastric pathology.
Methods Gastric biopsies were donated by 39 patients with H. pylori infection attending for endoscopy at Queen's Medical Centre, Nottingham, UK. Total RNA was extracted, and vacA mRNA quantified by reverse transcriptase quantitative PCR. Separate biopsies were histologically scored for inflammation and atrophy using the updated Sydney system. H. pylori strains were isolated from further biopsies, and the nucleotide sequence upstream of vacA determined.
Results vacA mRNA levels in human stomachs varied by two orders of magnitude independently of vacA allelic type. Among vacA i1-type (toxic) strains, increased vacA expression was strongly associated with higher grade gastric inflammation (p<0.02), neutrophil infiltration (p<0.005) and the presence of atrophy (p<0.01). A polymorphism at nucleotide +28 near the base of a potential stem-loop structure within the 5′ untranslated region was significantly associated with vacA transcript level and inflammation.
Conclusions Increased gastric vacA expression during H. pylori infection is associated with inflammation and premalignant pathology. The +28 nucleotide within the vacA 5′ stem-loop stratifies disease risk among toxic vacA i1-type strains.
- MICROBIAL PATHOGENIC
- HELICOBACTER PYLORI
- GASTRIC PATHOLOGY
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CGS and DPL contributed equally.
Handling editor Slade Jensen
Contributors JCA, DPL and CGS conceived and planned the study. CGS, GLN, SRP, NRH and AMZ carried out the experimental work. CGS, DPL, KR and JCA analysed the data. DPL, CGS, KR and JCA wrote the manuscript.
Funding This work was supported by Cancer Research UK (C8968A/A11204); Nottingham University Hospitals Charities, and the National Institute for Health Research (NIHR), through the NIHR Biomedical Research Unit in Gastrointestinal and Liver Diseases at Nottingham University Hospitals NHS Trust and the University of Nottingham; and a Wellcome Trust VIP Award to DPL. The views expressed are those of the authors and not necessarily those of the NHS, the NIHR or the Department of Health.
Competing interests None declared.
Ethics approval Nottingham Research Ethics Committee 2 (08/H0408/195).
Provenance and peer review Not commissioned; externally peer reviewed.
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