Helicobacter pylori-specific genes in gastric biopsies of patients with autoimmune gastritis with and without gastric cancer

Object Autoimmune gastritis(AIG), at increased gastric cancer(GC) risk, may be purely autoimmune or H.pylori -triggered. GC-risk in AIG may be H. pylori -related, but cannot be excluded in pure AIG. Distinguishing pure AIG( H.pylori- naïve) from that H.pylori- triggered is challenging. H.pylori -specific genes in AIG patients’ gastric tissue have not yet been assessed. This study aimed to assess H.pylori -specific genes on DNA extracted from gastric biopsies in AIG patients with and without GC. Methods This single-center study included 63 histologically-diagnosed AIG patients (median age 63 years; F88.7%) with parietal cell(100%) and/or intrinsic factor autoantibodies(42.6%) positivity, of whom ten were complicated with GC. DNA was extracted from formalin-fixed, paraffin-embedded(FFPE) tissue sections of gastric biopsies and RT-PCR was performed to test for H.pylori -specific gene probes: ureA , ureC , cagA . 16sRNA and β2-microglobulin probes were used as amplification-control of bacterial and human DNA. Previous history of H.pylori infection and histopathology were negative in all 63 AIG patients. Results Among AIG patients without GC, the H.pylori -specific ureC gene was detected in four(7.5%), three of whom were also ureA -positive, and one was also cagA -positive. All four ureC -positive patients had positive H.pylori serology. H.pylori -related genes were not detected in any of the ten AIG patients with GC. All available sera of AIG patients with GC were H.pylori seronegative(6/6100%). Bacterial 16 S rRNA and human-β2-microglobulin genes were similar in ureC- positive and ureC -negative AIG patients. Conclusion Assessment of H.pylori -related genes helps confirm patients with the pure H.pylori -naïve AIG type. This latter group also comprises AIG patients with GC, supporting the development of GC in AIG through H. pylori -independent mechanisms.