Immunomodulatory activity of casein hydrolysates produced after digestion with lactic acid bacterial cell envelope-associated proteinases

During hydrolysis of bovine milk caseins, lactic acid bacteria may be able to release peptides that possess immunomodulatory activity. The bacterial capability to digest caseins can be attributed to the presence of cell envelope-associated proteinases (CEPs). In this study, sodium caseinate from unprocessed bovine milk was submitted to the hydrolysis with CEPs of lactic acid bacterial strains. The hydrolysates were tested for their immunomodularoty activity in general, and for anti-inflammatory activity in particular. To evaluate the immunomodulatory activity of hydrolysates on human intestinal tissue, a human colorectal adenocarcinoma cell line Caco-2, transfected with nuclear factor kappa B (NF-kB)-inducible luciferase reporter plasmid, was used as a model system. Sodium caseinate hydrolysate, produced after digestion with CEP of Lactococcus lactis subsp. lactis GR5 did not show influence on basal NF-B activity, but its 3 kDa-separated fraction significantly decreased the basal NF-kB activity both, in the absence, and in the presence of pro-inflammatory stimulus of interleukin 1 beta, showing an anti-inflammatory activity in the latter case.