Characterisation of bifidobacteria with immunomodulatory properties isolated from human breast milk

Bifidobacteria are the predominant components of the intestinal flora in breast-fed infants. Growing research has revealed that breast milk provides a continuous supply of probiotic bacteria to the infants' gastrointestinal tract. These bacterial groups play a vital role in maintaining the gut health. Furthermore, they could also protect the infants from pathogen infections and contribute to the development and maturation of the systemic immunity. In this study, in addition to conventional probiotic screening criteria, eighteen Bifidobacterium strains isolated from breast milk were screened for their ability to induce cytokine production of human peripheral blood mononuclear cells with an attempt to select the potentially immunomodulatory strains. The results indicated that not only different species but also different strains have different effects on stimulation of cytokine production. Among all the probiotics isolated from human breast milk, Bifidobacterium adolescentis DB-2458 and Bifidobacterium longum subsp. infantis GB-1496 exhibited stronger immunomodulatory ability in comparison with other strains as evidenced by higher Th1-associated cytokine induction and lower Th2-associated cytokines production, the action which switches the immune response from Th2 toward Th1 polarization. Therefore, the two Bifidobacterium strains have great potential for development of functional foods, especially for infants' nutritional supplements.