Collagen-derived peptides enhance resistance to Pseudomonas aeruginosa infection in silkworms

Collagen-derived peptides are widely used as food ingredients and dietary supplements, but their effects on host defense against bacterial infection remain poorly understood. Here, we examined whether GFG-01, a granulated preparation of a fish-derived collagen hydrolysate produced using ginger protease, enhances resistance to Pseudomonas aeruginosa PAO1 infection in the silkworm (Bombyx mori). Oral administration of GFG-01 by mixing the preparation into the diet improved the post-infection outcome of larvae compared with vehicle-treated controls. Western blot analysis suggested that intrahemocoelic administration of GFG-01 induced accumulation of Cecropin B, an antimicrobial peptide, in the hemolymph. RNA-seq-based Gene Ontology enrichment analysis of samples collected after oral administration further showed tissue-dependent immune-related gene expression patterns: immune-related categories were enriched among downregulated genes in the fat body and among upregulated genes in hemocytes. These findings indicate that orally administered GFG-01 can improve the outcome of bacterial infection in silkworms and that GFG-01 is associated with modulation of host innate immune responses under the tested conditions.