Da-yuan-yin decoction alleviates ulcerative colitis by inhibiting complement activation, LPS-TLR4/NF-κB signaling pathway and NET formation.

Ethnopharmacological Relevance: Da-yuan-yin decoction (DYY) is a classical traditional Chinese medicine prescription for ulcerative colitis (UC).

Aim Of Study: This study explored the protective effects and mechanisms of DYY on UC.

Materials And Methods: The mice were fed 2.5% dextran sulfate sodium (DSS) for 7 days to establish UC. On the second day, DYY (0.4 g/kg, 0.8 g/kg, 1.6 g/kg) was orally administered daily for 7 consecutive days. The colon tissues and serum were measured by histopathological examination and biochemical analysis.

Results: DYY significantly reduced the disease activity index (DAI) and severity of colon shortening and alleviated pathological changes in the colon tissue. DYY restored the protein expression of intestinal tight junction (TJ) protein (ZO-1, occludin and claudin-3). DYY remarkably decreased the level of lipopolysaccharide (LPS), Lactic acid (LA), circulating free DNA (cfDNA), complement (C3, C3a, C3c, C3aR1, C5a and C5aR1) and regulated the levels of inflammatory cytokines in serum. DYY significantly inhibited the expressions of nuclear factor kappa-B p65 (NF-κB p65) and Toll-like receptor 4 (TLR4), citrullinated histone H3 (CitH3) and myeloperoxidase (MPO), reactive oxygen species (ROS) peptidylarginine deiminase 4 (PAD4) and CD 11b, the mRNA levels of PADI4, MPO and ELANE in colon tissues.

Conclusions: DYY significantly attenuated DSS-induced UC, which was related with regulating the inflammatory response by the inhibition of complement activation, the LPS-TLR4/NF-κB signaling pathway and neutrophil extracellular traps (NETs) formation. DYY is a potential therapeutic agent for UC.