Immunomodulatory Properties and Ameliorative Effects of Pediococcus inopinatus in an Animal Model of Inflammatory Bowel Disease

Abstract

Inflammatory bowel disease (IBD) is a chronic gastrointestinal disorder associated with dysregulated immune responses and gut inflammation. In this study, lactic acid bacteria were isolated from various types of skate kimchi, and 100 strains were screened for their anti-inflammatory activity. WiKim0108 demonstrated potent suppression of nitric oxide production and proinflammatory cytokines (IL-1β, IL-6, TNF-α) in lipopolysaccharide (LPS)-stimulated RAW 264.7 macrophages without cytotoxic effects. Phylogenetic analysis based on 16S rRNA sequences confirmed that the strain was Pediococcus inopinatus, which is closely related to other species of the genus widely used in food fermentation. WiKim0108 was susceptible to 14 clinically relevant antibiotics and exhibited γ-hemolysis, indicating its safety for use in food applications. Enzymatic profiling revealed functional activities beneficial for food fermentation, including β-galactosidase activity, but β-glucuronidase activity was absent. In vitro, WiKim0108 enhanced immune responses, such as the proliferation of RAW 264.7 cells, production of NO and reactive oxygen species, and expression of immune-related genes. These immunomodulatory effects were validated in vivo through an increased population of innate and adaptive immune cells and the upregulation of immune-related genes. In a DSS-induced IBD mouse model, oral administration of WiKim0108 ameliorated clinical and histological symptoms by restoring the immune cell population and suppressing excessive expression of immune cytokine. Collectively, these findings indicate that P. inopinatus WiKim0108 is a safe and functional lactic acid bacterium with dual anti-inflammatory and immunomodulatory effects, highlighting its potential as a functional starter culture and bioactive food ingredient for promoting gut health.