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.