Potential immunomodulatory activity of bovine casein hydrolysates produced after digestion with proteinases of lactic acid bacteria

During hydrolysis of bovine milk caseins, cell envelope-associated proteinases (CEPs) of lactic acid bacteria (LAB) may be able to produce hydrolysates that possess immunomodulatory activity. In this study, the selection of LAB by screening for bacterial CEP genes as well as by testing the proteolytic activity on bovine milk caseins was performed. Diverse hydrolytic ability against αS1- and β-casein fractions was observed. Our experiments demonstrated that immunomodulatory activity of obtained casein hydrolysates (CHs) cannot be attributed to casein-derived bioactive peptides only and underlined the necessity to thoroughly remove bacterial components before assessing bioactivity of CHs. On this basis, this study established that 3 kDa-ultrafiltered CHs, produced after digestion with proteinases of Lactobacillus acidophilus ATCC 4356 and Lactococcus lactis subsp. lactis GR5, significantly decreased the basal nuclear factor (NF)-κB activity in Caco-2 cells, demonstrating immunomodulatory activity.