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Relationship between Helicobacter pylori, gastric parietal cell antibodies and heat shock proteins
M A Asante1, M A Mendall, L Ballam
1Division of Gastroenterology, Endocrinology and Metabolism, St George's Hospital Medical School, London, UK.
Background:
The relationship between Helicobacter pylori and autoimmune (type A) gastritis is unclear. Infections may trigger autoimmune phenomena but the underlying mechanisms are unknown.
Aim:
To determine the relationships between H. pylori infection and gastric parietal cell antibodies (PCA), and PCA and heat shock protein (HSP) antibody.
Methods:
Fifty-five serum samples positive for PCA, 22 males and 33 females (median age 61 years, range 29-108 years) were compared with 60 control samples negative for PCA, 24 males and 36 females (median age, 48 years, range 11-91 years). H. pylori infection and HSP65K antibodies were determined by enzyme-linked immunosorbent assay. CagA and VacA status were determined by Western blotting.
Results:
The prevalence of H. pylori was higher in PCA-positives than controls, 29/55 [53%, 95% confidence interval (CI) 39-66%] versus 13/60 (22%, 95% CI 12-34); P= 0.0009. Age was not a confounding factor. Odds ratio for PCA seropositivity if H. pylori-positive was 4.0 (1.79-9.07), P= 0.003. There was an interaction between age and H. pylori, particularly in younger patients. CagA strains were less common in PCA-positives than controls, 10/29 (35%, 95% CI 19-54) versus 9/13 (69%, 39-91), P< 0.05. HSP65K antibodies were elevated in H. pylori infection but to a similar degree for both PCA-positives and controls.
Conclusion:
H. pylori, particularly CagA-negative strains, are associated with autoimmune gastritis and may be implicated in the pathogenesis of autoimmune (type A) gastritis, particularly in younger persons.