Fish myofibrillar protein glycated with uronic acid-type reducing sugar via Maillard reaction attenuates toll-like receptor 4 signalling pathway activation and suppresses lipopolysaccharide-stimulated inflammation in RAW 264.7 macrophages

Our previous study found that glycation with uronic acid-type reducing sugar enhanced the anti-inflammatory effect of fish myofibrillar protein (Mf) via the Maillard reaction, and the molecular mechanism of enhanced anti-inflammatory effect was investigated in this study. Mf was glycated with various reducing sugars at 60 degree celsius and 35% relative humidity. After pepsin-trypsin digestion, the anti-inflammatory effects were evaluated by assessing secretions of pro-inflammatory cytokines and expressions of LPS-stimulated signalling pathway-related genes in RAW 264.7 macrophages. Mf glycated with uronic acid-type reducing sugars: glucuronic acid, galacturonic acid and alginate oligosaccharide, suppressed expression of cd14 and further suppressed expressions of tlr4 and myd88 comparing with intact and glycated Mf with glucose and galactose. Furthermore, uronic acid-glycated Mf significantly suppressed expressions and secretions of pro-inflammatory cytokines. The results indicate that uronic acid-type glycation enhances anti-inflammatory effect of Mf by attenuating expression of cd14 and enhancing the Mf-induced suppression in TLR4-MyD88-dependent inflammatory signalling pathway.