Short communication: Tryptic β-casein hydrolysate modulates enteric nervous system development in primary culture

Abstract

The intestinal tract of the newborn is particularly sensitive to gastrointestinal disorders, such as infantile diarrhea or necrotizing colitis. Perinatal development of the gut also encompasses the maturation of the enteric nervous system (ENS), a main regulator of intestinal motility and barrier functions. It was recently shown that ENS maturation can be enhanced by nutritional factors to improve intestinal maturation. Bioactivity of milk proteins is often latent, requiring the release of bioactive peptides from inactive native proteins. Several casein-derived hydrolysates presenting immunomodulatory properties have been described recently. Furthermore, accumulating data indicate that milk-derived hydrolysate can enhance gut maturation and enrichment of milk formula with such hydrolysates has recently been proposed. However, the capability of milk-derived bioactive hydrolysate to target ENS maturation has not been analyzed so far. We, therefore, investigated the potential of a recently described tryptic β-casein hydrolysate to modulate ENS growth parameters in an in vitro model of rat primary culture of ENS. Rat primary cultures of ENS were incubated with a bioactive tryptic β-casein hydrolysate and compared with untreated controls or to cultures treated with native β-casein or a Prolyve β-casein hydrolysate (Lyven, Colombelles, France). Differentiation of enteric neurons and enteric glial cells, and establishment of enteric neural network were analyzed using immunohistochemistry and quantitative PCR. Effect of tryptic β-casein hydrolysate on bone morphogenetic proteins (BMP)/Smad pathway, an essential regulator of ENS development, was further assessed using quantitative PCR and immunochemistry. Tryptic β-casein hydrolysate stimulated neurite outgrowth and simultaneously modulated the formation of enteric ganglia-like structures, whereas native β-casein or Prolyve β-casein hydrolysate did not. Additionally, treatment with tryptic bioactive β-casein hydrolysate increased the expression of the glial marker glial fibrillary acidic protein and induced profound modifications of enteric glial cells morphology. Finally, expression of BMP2 and BMP4 and activation of Smad1/5 was altered after treatment with tryptic bioactive β-casein hydrolysate. Our data suggests that this milk-derived bioactive hydrolysate modulates ENS maturation through the regulation of BMP/Smad-signaling pathway. This study supports the need for further investigation on the influence of milk-derived bioactive peptides on ENS and intestinal maturation in vivo.

Hypolipidemic Roles of Casein-Derived Peptides by Regulation of Trans-Intestinal Cholesterol Excretion and Bile Acid Synthesis

“…In this study, we suggested the sequences of two peptides demonstrating bioactivity. Reportedly, peptide 9 is detected in casein hydrolysates involved in nervous system development and antioxidant effects [ 36 , 37 ]. Peptide 12 is present in casein hydrolysates known to have antioxidant, anti-hypertension, and osteoblast proliferation/differentiation effects [ 38 , 39 , 40 ].…”

Gastrointestinal Digestion of Food Proteins under the Effects of Released Bioactive Peptides on Digestive Health

“…Interestingly, it has been recently shown the ability of a tryptic β‐casein hydrolyzate to enhance the maturation of the rat primary enteric nervous system, main regulator involved in intestinal motility and barrier functions. [ 70 ] Concerning the whey fraction of milk, it has been found in the isolated rat distal colon assay that whey proteins concentrates decreased motility, while increased frequency of contractions was found for whey proteins hydrolyzates. [ 71 ] These authors hypothesized that differences between abundance of bioactive peptides in the dairy preparations might explain the opposite effects, as the maximum degree of protein hydrolysis was associated to the highest motility in the tissue.…”

Recent advances in understanding the roles of the enteric nervous system

“…demonstrated that dissociated myenteric neurons from post-natal rats generated longer lengths of neurite outgrowth and displayed higher neuronal survival when cultured in a medium enriched with breast milk protein extracts, in comparison with the control medium 21 . In similar experiments, other milk-derived bioactive peptides such as tryptic β-casein hydrolysate were also found to modulate ENS maturation by stimulating neurite outgrowth and forming enteric ganglia-like structures 23 .…”