BACKGROUND: Necrotizing enterocolitis (NEC) is associated with changes in the luminal gut microbiota. It is not known whether the mucosa-associated microbiota is affected by NEC and stimulates inflammatory lesions.

OBJECTIVE: We hypothesized that the density of the mucosa-associated microbiota correlates with NEC severity in preterm pigs and that in vitro infection with increasing densities of Clostridium perfringens, which has been associated with NEC in preterm infants, would lead to a transcriptional response related to the inflammatory conditions of NEC.

METHODS: First, we determined the density of total bacteria and C. perfringens in the distal small intestinal mucosa of 58 NEC and healthy preterm pigs using quantitative PCR. Next, we analyzed in IPEC-J2 cells the effect of different infection densities of C. perfringens type A on the expression of genes related to intestinal function and immune response.

RESULTS: Total bacterial and C. perfringens densities were higher in NEC versus healthy pigs and correlated positively with NEC severity. In IPEC-J2 cells expression levels of inflammation-related genes (CCL5, NFKBIA, IL8, IL1RN, and TNFAIP3) increased, while the expression of the sodium/glucose co-transporter (SLC5A1) decreased, with increasing density of C. perfringens.

CONCLUSIONS: Total bacterial and C. perfringens densities were higher in NEC versus healthy pigs and correlated positively with NEC severity. In IPEC-J2 cells expression levels of inflammation-related genes (CCL5, NFKBIA, IL8, IL1RN, and TNFAIP3) increased, while the expression of the sodium/glucose co-transporter (SLC5A1) decreased, with increasing density of C. perfringens.