Fecal expression of human β-defensin-2 following birth.

BACKGROUND

Newborns display high intestinal permeability and a naive adaptive immune system, but infections are rare, indicating strong innate defense mechanisms.

OBJECTIVE

To measure the kinetics of fecal β-defensin-2 (HBD2), an inducible endogenous antimicrobial peptide produced by intestinal epithelial cells, in full-term and preterm infants.

METHODS

As a first step of this bicentric study, we enrolled 30 healthy full-term infants and 20 healthy preterm infants, with fecal samples collected at days 3, 7, 12 and 30 in full-term infants and at days 15, 30 and 60 in preterm infants. As a second step, we enrolled 10 preterm infants with intestinal distress, either necrotizing enterocolitis (NEC) Bell's stage III (n = 3) or isolated rectal bleeding (n = 7) and 20 controls, cross-matched for gestational age and age at sampling.

RESULTS

HBD2 decreased significantly from day 3 to day 7 (227 ng/g; 14-440 vs. 117 ng/g; 30-470, p = 0.01) then moderately until day 30 (84 ng/g; 10-500) in healthy full-term infants. Healthy preterm infants showed similar high levels between days 15 and 60 (82 ng/g; 30-154 and 85 ng/g; 26-390, respectively). No significant variation of fecal HBD2 levels was observed between infants with clinical features of intestinal distress (77 ng/g, 2-1,271) and cross-matched controls (56 ng/g, 31-164). However, 2/3 infants with NEC and 1/7 infants with isolated rectal bleeding had HBD2 levels above the maximal level observed in controls.

CONCLUSIONS

The kinetics of fecal HBD2 in the neonatal period indicate that this inducible defensin can be detected at high level in the feces of full-term and preterm infants, independently of gestational age or mode of feeding. The potential role of fecal HBD2 in detecting NEC is suggested.