Bifidobacterium breve enhances transforming growth factor β1 signaling by regulating Smad7 expression in preterm infants

Objectives: Transforming growth factor (TGF) beta 1 displays a broad spectrum of activities in mucosal regulation, including induction of oral tolerance, potent anti-inflammatory effects, mucosal IgA expression and effects on epithelial cell proliferation and differentiation. The present study examined the effect of probiotics on the immunologic system of preterm infants in relation to TGF-beta signaling. Methods: Subjects comprised 19 preterm infants divided into 2 groups: receiving Bifidobacterium breve supplementation (B. breve group) and without supplementation (controls). Blood samples were collected from both groups on days 0, 14 and 28 after birth. Serum cytokine levels were measured using enzyme-linked immunosorbent assay, and expression levels of the TGF-beta signaling molecule, Smad, were examined using semiquantitative reverse transcriptase-polymerase chain reaction. Results: Serum TGF-beta 1 level was elevated on day 14 and remained elevated on day 28 in the B. breve group. Level of messenger RNA expression was enhanced for Smad3 and reduced for Smad7 (antagonistic Smad) after B. breve administration relative to levels in controls on day 28. Conclusions: These results demonstrated that the administration of B. breve to preterm infants can up-regulate TGF-beta 1 signaling and may possibly be beneficial in attenuating inflammatory and allergic reactions in these infants.