Prophylactic and Gastroprotective Potential of Bacillus amyloliquefaciens NPKE6-Fermented Metabolites in an HCl/Ethanol-Induced Acute Gastritis Model in ICR Mice

Gastric mucosal injury is associated with acute epithelial damage, inflammatory cytokine release, and disruption of the protective mucus barrier. NPKE6-FM is a fermented metabolite preparation produced from puffed soybean and rice inoculated with Bacillus amyloliquefaciens NPKE6, a strain isolated from Korean water kimchi. Although NPKE6-FM has shown antioxidant and anti-inflammatory potential in previous in vitro and in vivo studies, its gastroprotective efficacy against acute gastric injury has not been fully evaluated. This study investigated the protective effects of NPKE6-FM in an HCl/ethanol-induced acute gastritis model in ICR mice. Male ICR mice were randomly assigned to six groups after weight measurement (n = 5 per group): normal control (distilled water only), model group (HCl/ethanol plus distilled water), positive control (HCl/ethanol plus rebamipide, 50 mg/kg), and NPKE6-FM treatment groups receiving 10, 50, or 100 mg/kg. Test substances or vehicle were orally administered for 14 consecutive days. Following an approximately 18 h fast on Day 15, acute gastric mucosal injury was induced by oral administration of 200 mM HCl in 80% ethanol. Gastric tissues were collected approximately 1 h after injury induction for macroscopic lesion assessment, histopathological examination, cytokine analysis, and quantitative real-time PCR analysis of inflammation- and mucin-related genes. HCl/ethanol administration induced marked hemorrhagic and erosive gastric lesions, histopathological mucosal damage, and increased levels of TNF-α and IL-6. NPKE6-FM treatment reduced gross gastric lesion scores in a dose-dependent manner, with the 100 mg/kg group showing the greatest protective effect. Histological evaluation further indicated improved preservation of gastric mucosal architecture in NPKE6-FM-treated mice. In addition, NPKE6-FM significantly suppressed TNF-α and IL-6 levels and downregulated the mRNA expression of inflammatory mediators, including COX-2, iNOS, TNF-α, and IL-6. Conversely, the HCl/ethanol-induced reduction in Muc5ac expression was substantially restored by NPKE6-FM treatment. These findings demonstrate that NPKE6-FM protects against HCl/ethanol-induced acute gastric mucosal injury through anti-inflammatory activity and reinforcement of the gastric mucus barrier. NPKE6-FM may therefore represent a promising functional food ingredient or nutraceutical candidate for the prevention or attenuation of gastric mucosal injury.