Following preterm birth, bacterial colonization and enteral formula feeding predispose neonates to gut dysfunction and necrotizing enterocolitis (NEC), a serious gastrointestinal inflammatory disease. We hypothesized that administration of probiotics would beneficially influence early bacterial colonization, thereby reducing the susceptibility to formula-induced gut atrophy, dysfunction, and NEC. Caesarean-delivered preterm pigs were provided total parenteral nutrition (1.5 d) followed by enteral feeding (2 d) with porcine colostrum (COLOS; n = 5), formula (FORM; n = 9), or formula with probiotics (FORM-P; Bifidobacterium animalis and Lactobacillus: L. acidophilus, L. casei, L. pentosus, L. plantarum; n = 13). Clinical NEC scores were reduced (P < 0.05) in FORM-P (2.0 +/- 0.2) and COLOS groups (1.7 +/- 0.5) compared with FORM pigs (3.4 +/- 0.6). Lower NEC scores were associated with elevated intestinal weight, mucosa proportion, villus height, RNA integrity, and brush border aminopeptidase A and N activities, and lower gastric organic acid concentration in the FORM-P and COLOS groups (P < 0.05). Diversity of the mucosa-associated bacteria in the distal small intestine was similar among formula-fed pigs, yet the abundance of specific bacterial groups differed between FORM-P and FORM pigs. FORM-P pigs had lower colonization density of a potential pathogen, Clostridium perfringens, and had commensal Lactobacillus bacteria more closely associated with enterocytes along the villus-crypt axis relative to FORM pigs. These results suggest that probiotic administration immediately after birth promotes the colonization of a beneficial commensal microbiota capable of limiting the formula-induced mucosal atrophy, dysfunction, and pathogen load in preterm neonates, thereby reducing the incidence and severity of NEC.

No abstract

Preterm neonates are susceptible to gastrointestinal disorders such as necrotizing enterocolitis (NEC). Maternal milk and colostrum protects against NEC via growth promoting, immunomodulatory, and antimicrobial factors. The fetal enteral diet amniotic fluid (AF), contains similar components, and we hypothesized that postnatal AF administration reduces inflammatory responses and NEC in preterm neonates. Preterm pigs (92% gestation) were delivered by caesarean section and fed parental nutrition (2 days) followed by enteral (2 days) porcine colostrum (COLOS, n = 7), infant formula (FORM, n = 13), or AF supplied before and after introduction of formula (AF, n = 10) in experiment 1, and supplied only during the enteral feeding period in experiment 2 (FORM, n = 16; AF, n = 14). The NEC score was reduced in both AF and COLOS pigs, relative to FORM, when AF was provided prior to full enteral feeding (9.9 and 7.7 compared with 17.3, P < 0.05). There was no effect of AF when provided only during enteral feeding. AF pigs showed decreased bacterial abundance in colon and intestinal inflammation-related genes (e.g., TNF-α, IL-1α, IL-6, NOS) were downregulated, relative to FORM pigs with NEC. Anti-inflammatory properties of AF were supported by delayed maturation and decreased TNF-α production in murine dendritic cells, as well as increased proliferation and migration, and downregulation of IL-6 expression in intestinal cells (IEC-6, IPEC-J2). Like colostrum, AF may reduce NEC development in preterm neonates by suppressing the proinflammatory responses to enteral formula feeding and gut colonization when provided before the onset of NEC.

Necrotizing enterocolitis (NEC) is the most common gastrointestinal emergency in newborn premature infants. Clinical studies show increased incidence of NEC in premature infants with enteral formula feeding; however, pathogenesis remains unclear. To identify the NEC-related proteins for molecular mechanisms, we applied proteomics analysis to characterize changes in the protein expression profile of newborn premature piglet intestines with NEC developed after enteral formula feeding for 24 h. Changes in protein expression were identified using 2-dimensional gel electrophoresis and peptide mass fingerprinting with MS as well as western blotting analysis. Nineteen differentially expressed proteins were identified and these have roles in oxidative stress, chaperone, signal transduction, protein folding and degradation, oxygen transport, signal transduction, and energy metabolism. Proteins with increased levels include manganese-containing superoxide dismutase and hemoglobin subunit and proteins with decreased expression include sorbitol dehydrogenase, mitochondrial aldehyde dehydrogenase 2, glucose-regulated protein 75, CRY protein, snail homolog 3, thyroid hormone-binding protein precursor, and DJ1 (Parkinson's disease 7) etc. The data provided novel mechanistic insights into the pathogenesis of NEC and the insults of a formulated diet to the premature gut.

Necrotizing enterocolitis (NEC) in preterm infants develops very rapidly from a mild intolerance to enteral feeding into intestinal mucosal hemorrhage, inflammation, and necrosis. We hypothesized that immediate feeding-induced gut responses precede later clinical NEC symptoms in preterm pigs. Fifty-six preterm pigs were fed total parenteral nutrition (TPN) for 48 h followed by enteral feeding for 0, 8, 17, or 34 h with either colostrum (Colos, n = 20) or formula (Form, n = 31). Macroscopic NEC lesions were detected in Form pigs throughout the enteral feeding period (20/31, 65%), whereas most Colos pigs remained protected (1/20, 5%). Just 8 h of formula feeding induced histopathological lesions, as evidenced by capillary stasis and necrosis, epithelial degeneration, edema, and mucosal hemorrhage. These immediate formula-induced changes were paralleled by decreased digestive enzyme activities (lactase and dipeptidylpeptidase IV), increased nutrient fermentation, and altered expression of innate immune defense genes such as interleukins (IL-1α, IL-6, IL-18), nitric oxide synthetase, tight junction proteins (claudins), Toll-like receptors (TLR-4), and TNF-α. In contrast, the first hours of colostrum feeding induced no histopathological lesions, increased maltase activity, and induced changes in gene expressions related to tissue development. Total bacterial density was high after 2 days of parenteral feeding and was not significantly affected by diet (colostrum, formula) or length of enteral feeding (8-34 h), except that a few bacterial groups (Clostridium, Enterococcus, Streptococcus species) increased with time. We conclude that a switch from parenteral to enteral nutrition rapidly induces diet-dependent histopathological, functional, and proinflammatory insults to the immature intestine. Great care is required when introducing enteral feeds to TPN-fed preterm infants, particularly when using formula, because early feeding-induced insults may predispose to NEC lesions that are difficult to revert by later dietary or medical interventions.

Necrotizing enterocolitis (NEC), a serious gastrointestinal inflammatory disease, frequently occurs in preterm neonates that fail to adapt to enteral nutrition. A temporal gel-based proteomics study was performed on porcine intestine with NEC lesions induced by enteral formula feeding. Functional assignment of the differentially expressed proteins revealed that important cellular functions, such as the heat shock response, protein processing; and purine, nitrogen, energy metabolism, were possible involved in the early progression of NEC.

No abstract

No abstract