Anti-Inflammatory Effects of Hermetia illucens Fermented with Riboflavin-Producing Leuconostoc mesenteroides KCCM13067P in RAW 264.7 Cells and Colitis Mouse Model

Inflammatory bowel disease (IBD) threatens human and animal health. Black soldier fly (Hermetia illucens; Hi) larvae (BSFL) and Leuconostoc mesenteroides bacteria have potential anti-inflammatory effects; however, no studies have confirmed their impact on IBD. In this study, riboflavin-producing L. mesenteroides KCCM13067P was isolated from a fish farm tank and, in conjunction with hot water-extracted Hi (HeHi) (termed HeHi_Lm), was used to determine the optimal fermentation conditions to increase vitamin B2 concentration. The anti-inflammatory effects of the optimized HeHi_Lm material were then examined using lipopolysaccharide (LPS)-induced RAW 264.7 immune cells. Finally, the anti-inflammatory effects of HeHi_Lm were verified using a dextran sulfate sodium (DSS)-induced mouse model of IBD. The disease activity index (DAI) score, histological changes, inflammatory cytokine levels, and changes in gut microbial communities were also assessed. HeHi_Lm significantly reduced the DAI, spleen and liver weights, indicator factors (inducible nitric oxide synthase and cyclooxygenase-2), and inflammatory cytokine (interleukin IL-6 and IL-1β) levels, as well as increased body weight and colon length. Furthermore, HeHi_Lm administration significantly improved the gut microbiota composition. These results suggest that HeHi_Lm is an eco-friendly, novel, and potential therapeutic dietary strategy for preventing gut inflammation.