Protein hydrolysate from canned sardine and brewing by-products improves TNF-α-induced inflammation in an intestinal-endothelial co-culture cell model.

Purpose: The anti-inflammatory activity of sardine protein hydrolysates (SPH) obtained by hydrolysis with proteases from brewing yeast surplus was ascertained.

Methods: For this purpose, a digested and desalted SPH fraction with molecular weight lower than 10 kDa was investigated using an endothelial cell line (EA.hy926) as such and in a co-culture model with an intestinal cell line (Caco-2). Effects of SPH <10 kDa on nitric oxide (NO) production, reactive oxygen species (ROS) inhibition and secretion of monocyte chemoattractant protein 1 (MCP-1), vascular endothelial growth factor (VEGF), chemokine IL-8 (IL-8) and intercellular adhesion molecule-1 (ICAM-1) were evaluated in TNF-α-treated and untreated cells.

Results: Upon TNF-α treatment, levels of NO, MCP-1, VEGF, IL-8, ICAM-1 and endothelial ROS were significantly increased in both mono- and co-culture models. Treatment with SPH <10 kDa (2.0 mg peptides/mL) significantly decreased all the inflammation markers when compared to TNF-α-treated control. This protective effect was more pronounced in the co-culture model, suggesting that SPH <10 kDa Caco-2 cells metabolites produced in the course of intestinal absorption may provide a more relevant protective effect against endothelial dysfunction. Additionally, indirect cross-talk between two cell types was established, suggesting that SPH <10 kDa may also bind to receptors on the Caco-2 cells, thereby triggering a pathway to secrete the pro-inflammatory compounds.

Conclusion: Overall, these in vitro screening results, in which intestinal digestion, absorption and endothelial bioactivity are simulated, show the potential of SPH to be used as a functional food with anti-inflammatory properties.