Pyropia yezoensis-derived porphyran attenuates acute and chronic colitis by suppressing dendritic cells.

Porphyran is known to inhibit immune cell function. Previously, porphyran was shown to prevent lipopolysaccharide-induced sepsis in mice. However, studies on the inhibitory effects of porphyran during colitis are currently lacking. In this study, we evaluated the effects of Pyropia yezoensis- derived porphyran on dextran sodium sulfate (DSS)-induced acute and chronic colitis. The oral or intraperitoneal administration of porphyran inhibited the progression of DSS-induced colitis in mice, with the former also preventing immune cell infiltration in the colon. The levels of intracellular interferon-γ and interleukin-17 in T cells decreased when porphyran was administered orally. Porphyran inhibited T cell activation by suppressing dendritic cells (DCs) and macrophages. Porphyran prevented pathogen-associated molecular pattern and damage-associated molecular pattern-dependent DC and macrophage activation. Finally, porphyran attenuated chronic colitis caused via the long-term administration of DSS. These findings indicate that the oral administration of porphyran can inhibit DSS-induced colitis by suppressing DC and macrophage activation. • Porphyran administered orally alleviated DSS-induced murine colitis. • Porphyran prevented immune cell infiltration during DSS-induced colitis. • Porphyran inhibited DAMP and PAMP-dependent activation of DCs. • DSS-induced chronic inflammation in the colon was inhibited by porphyrin. [ABSTRACT FROM AUTHOR]