Sheep (Ovis aries)\nMilk Exosomal miRNAs Attenuate Dextran Sulfate Sodium-Induced Colitis\nin Mice via TLR4 and TRAF‑1 Inhibition

Mammalian milk exosomal miRNAs play an important role\nin maintaining\nintestinal immune homeostasis and protecting epithelial barrier function,\nbut the specific miRNAs and whether miRNA-mediated mechanisms are\nresponsible for these benefits remain a matter of investigation. This\nstudy isolated sheep milk-derived exosomes (sheep MDEs), identifying\nthe enriched miRNAs in sheep MDEs, oar-miR-148a, and oar-let-7b as\nkey components targeting TLR4 and TRAF1, which was validated by a\ndual-luciferase reporter assay. In dextran sulfate sodium-induced\ncolitis mice, administration of sheep MDEs alleviated colitis symptoms,\nreduced colonic inflammation, and systemic oxidative stress, as well\nas significantly increased colonic oar-miR-148a and oar-let-7b while\nreducing toll-like receptor 4 (TLR4) and TNF-receptor-associated factor\n1 (TRAF1) level. Further characterization in TNF-α-challenged\nCaco-2 cells showed that overexpression of these miRNAs suppressed\nthe TLR4/TRAF1-IκBα-p65 pathway and reduced IL-6 and IL-12\nproduction. These findings indicate that sheep MDEs exert gastrointestinal\nanti-inflammatory effects through the miRNA-mediated modulation of\nTLR4 and TRAF1, highlighting their potential in managing colitis.