Gastric Microbiota Associated with Gastric Precancerous Lesions in Helicobacter pylori-Negative Patients

Studies on the gastric microbiota associated with gastric precancerous lesions remain limited. This study aimed to profile the gastric mucosal microbiota in patients with Helicobacter pylori-negative precancerous lesions. Gastric mucosal samples were obtained from 67 H. pylori-negative patients, including those with chronic gastritis (CG), intestinal metaplasia (IM), and dysplasia. The V3–V4 region of the 16S rRNA gene was sequenced and analyzed. No significant difference was observed in the alpha or beta diversity of the gastric microbiota among the groups. However, a taxonomic analysis revealed a significant enrichment of Lautropia mirabilis and the depletion of Limosilactobacillus reuteri, Solobacxterium moorei, Haemophilus haemolyticus, and Duncaniella dubosii in the IM and dysplasia groups compared to those in the CG group. Prevotella jejuni and the genus Parvimonas were enriched in the IM group. A predictive functional analysis revealed enrichment of the ornithine degradation pathway in the IM and dysplasia groups, suggesting its role in persistent gastric mucosal inflammation associated with gastric precancerous lesions. The gastric microbiota associated with H. pylori-negative gastric precancerous lesions showed an increased abundance of oral microbes linked to gastric cancer and a reduction in anti-inflammatory bacteria. These alterations might contribute to chronic gastric mucosal inflammation, promoting carcinogenesis in the absence of H. pylori infection.