Anti-Inflammatory Effects of Paraprobiotic Lactiplantibacillus plantarum KU15122 in LPS-Induced RAW 264.7 Cells.

Inflammation is a biodefense mechanism that provides protection against painful conditions such as inflammatory bowel disease, other gastrointestinal problems, and irritable bowel syndrome. Paraprobiotics have probiotic characteristics of intestinal modulation along with merits of safety and stability. In this study, heat-killed Lactiplantibacillus plantarum KU15122 (KU15122) was investigated for its anti-inflammatory properties. KU15122 was subjected to heat-killed treatment for enhancement of its safety, and its concentration was set at 8 log CFU/mL for conducting different experiments. Nitric oxide production was most remarkably reduced in the KU15122 group, whereas it was increased in the LPS-treated group. In RAW 264.7 cells, KU15122 inhibited the expression of inducible nitric oxide synthase, cyclooxygenase-2, interleukin (IL)-1β, IL-6, and tumor necrosis factor-α. ELISA revealed that among the tested strains, KU15122 exhibited the most significant reduction in PGE₂, IL-1β, and IL-6. Moreover, KU15122 inhibited various factors involved in the nuclear factor-kappa B, activator protein-1, and mitogen-activated protein kinase pathways. In addition, KU15122 reduced the generation of reactive oxygen species. The anti-inflammatory effect of KU15122 was likely attributable to the bacterial exopolysaccharides. Conclusively, KU15122 exhibits anti-inflammatory potential against inflammatory diseases.