Lactobacillus paragasseri OLL2716 Promotes Ghrelin Expression in Gastric Cells

Yogurt containing Lactobacillus paragasseri OLL2716 (LG21 yogurt) has been reported to improve delayed gastric emptying and modulate autonomic nervous system (ANS) activity. Ghrelin, a peptide hormone produced in the stomach, enhances gastric motility and acid secretion and modulates autonomic function. This study examined whether LG21 yogurt affects ghrelin-related responses in gastric cells. MKN45 cells, a human gastric adenocarcinoma-derived cell line, were treated with LG21 cells (live or heat-treated) or LG21 culture supernatant, and ghrelin messenger RNA (mRNA) expression was quantified. Both LG21 cells and the culture supernatant significantly increased ghrelin mRNA expression, suggesting contributions from bacterial cells and metabolites. To support the transcript data, secreted ghrelin was additionally measured by enzyme-linked immunosorbent assay after treatment with LG21 cells, and LG21 cells significantly increased ghrelin secretion. LG21 yogurt induced an earlier increase in ghrelin mRNA than did yogurt prepared with the starter strains Lactobacillus delbrueckii subsp. bulgaricus OLL1255 and Streptococcus thermophilus OLS3294 but without LG21 (LG21-free yogurt). The effect also varied by strain: LG21 increased ghrelin mRNA expression, whereas the L. paragasseri type strain showed no significant effect. Additional pharmacological experiments in MKN45 cells further supported the possibility that prostaglandin E2-EP4 signaling contributes to the ghrelin response in this model. These findings indicate that, in the exploratory in vitro MKN45 model used here, LG21 yogurt modulates ghrelin-related readouts in a strain-dependent manner, with contributions from both LG21 and the starter strains.