Anti‐inflammatory effects of a casein hydrolysate and its peptide‐enriched fractions on TNF α‐ challenged Caco‐2 cells and LPS‐challenged porcine colonic explants

Bioactive milk peptides are reported to illicit a range of physiological benefits and have been proposed as potential functional food ingredients. The objective of this study was to characterize the anti‐inflammatory properties of sodium caseinate ( NaCAS ), its enzyme hydrolysate ( EH ) and peptide‐enriched fractions (5 kDa retentate [R], 1 kDaR and 1 kDa permeate [P]), both in vitro using a Caco‐2 cell line, and also ex vivo using a porcine colonic tissue explant system. Caco‐2 cells were stimulated with tumour necrosis factor alpha ( TNF α ) and co‐treated with casein hydrolysates for 24 h. Following this, interleukin ( IL) ‐8 concentrations in the supernatant were measured using enzyme‐linked immunosorbent assay. Porcine colonic tissue was stimulated with lipopolysaccharide and co‐treated with casein hydrolysates for 3 h. The expression of a panel of inflammatory cytokines was measured using qPCR . While dexamethasone reduced the IL‐8 concentration by 41.6%, the 1 kDaR and 1 kDaP fractions reduced IL‐8 by 68.7% and 66.1%, respectively, relative to TNF α‐ stimulated Caco‐2 cells ( P <  0.05). In the ex vivo system, only the 1 kDaR fraction elicited a decrease in IL1‐α , IL1‐β , IL‐8 , TGF‐β and IL‐10 expression ( P  < 0.05). This study provides evidence that the bioactive peptides present in the 1 kDaR fraction of the NaCAS hydrolysate possess anti‐inflammatory properties in vitro and ex vivo. Further in vivo analysis of the anti‐inflammatory properties of the 1 kDaR is proposed.