Beneficial impact of MTGase-modified fish gelatin on collagen supplementation in rats: Insights from serum metabolomics and gut microbiota.

Sustained release technology facilitates precise regulation of active ingredient delivery, attenuating enzymatic degradation while optimizing bioavailability in malabsorptive conditions. Microbial transglutaminase (MTGase) catalyzes isopeptide bond formation via acyl transfer reactions, conferring resistance to gastrointestinal digestion. However, the in vivo sustained release potential of MTGase-modified fish gelatin (MTGase-modified-FG) remains uncertain. In this study, enzymatic modification was performed using MTGase at graded concentrations (0.00 % (Nor), 0.06 % (LD), 0.12 % (MD), and 0.21 % (HD)), with sustained release of collagen evaluated through pharmacokinetic analysis. The results indicated that the MTGase-modified-FG supplementation exhibited a dose-dependent sustained release, extending Tmax from 2.00 ± 0.00 h (Nor) to 5.33 ± 1.15 h (HD). Notably, suboptimal crosslinking (LD/MD) enhanced skin collagen deposition, whereas excessive modification (HD) induced malabsorptive phenomena that may be attributed to the presence of excessive isopeptide bonds. Metabolomic analysis identified MTGase-modified-FG modulated the serum metabolome in collagen-related metabolites (LysoPC, Lysine, succinate), mechanistically linked to choline metabolism in cancer and lysine catabolism. Additionally, the gut microbiota remodeling was modulated by the suppression of Ruminococcus and Blautia, as well as by the expansion of Faecalibaculum and Bifidobacterium at the genus level. RT-qPCR analysis indicated that MTGase-modified-FG enhanced collagen deposition via the TGF-β/Smads and MAPK/AP-1/MMP pathways in human dermal fibroblast cells. These findings suggest that MTGase-modified confers the sustained release properties to fish gelatin, and provides a new collagen supplementation strategy for individuals with malabsorption syndromes.