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. 2014 Sep 19;9(9):e106888.
doi: 10.1371/journal.pone.0106888. eCollection 2014.

Delayed initiation but not gradual advancement of enteral formula feeding reduces the incidence of necrotizing enterocolitis (NEC) in preterm pigs

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Delayed initiation but not gradual advancement of enteral formula feeding reduces the incidence of necrotizing enterocolitis (NEC) in preterm pigs

Nada Ghoneim et al. PLoS One. .

Abstract

Enteral formula feeding is a risk factor for necrotizing enterocolitis (NEC) in premature infants, yet studies are conflicting regarding the safest timing for introduction and advancement of feeds. Our aim was to test the effects of early vs. late initiation and abrupt vs. gradual advancement of enteral feeding of an intact vs. hydrolyzed protein formula on NEC incidence and severity in preterm pigs. In Experiment 1, preterm pigs received total parenteral nutrition (TPN) at birth with abrupt initiation of enteral formula feeds (50% full intake) on d of life (DOL) 2 (EA) or 5 (LA) while PN continued. Pigs were also fed formula containing either intact or hydrolyzed protein. In Experiment 2, preterm pigs received TPN at birth with enteral, hydrolyzed-protein formula feeds introduced on DOL 2 either abruptly (EA; 50% full feeds) or gradually (EG; 10-50% full feeds over 5 d) while PN continued. NEC incidence and severity were assessed based on macroscopic and histological scoring. In Experiment 1, NEC incidence (41% vs. 70%, P<0.05) and severity were reduced in LA vs. EA groups and LA was associated with a higher survival rate, daily weight gain and jejunum villus height. Piglets fed hydrolyzed vs. intact protein formula had lower stomach content weights and similar NEC incidence. In Experiment 2, NEC incidence and severity were not different between pigs the EG vs. EA group. Proinflammatory gene expression (IL-1β, IL-6 and S100A9) in the ileum was lower in both LA and EG vs. EA groups. In conclusion, delayed initiation but not gradual advancement of enteral feeding is protective against NEC in preterm pigs. Feeding hydrolyzed vs. intact protein formula improved gastric transit without affecting the NEC incidence.

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Conflict of interest statement

Competing Interests: The authors also want to confirm that the fact that some authors of the manuscript are employees of Mead Johnson Pediatric Nutrition Institute which partially supported the research reported in the article, does not alter the adherence to PLOS ONE policies on sharing data and materials.

Figures

Figure 1
Figure 1. Study design of Experiment 1, EA vs. LA, and Experiment 2, EA vs. EG.
At DOL 0, pigs were delivered 12-d preterm via C-section and were surgically implanted with orogastric and jugular catheters. (A) In Experiment 1, enteral formula (IG feeding with intact or hydrolyzed protein) was introduced abruptly at 50% of their total feeding intake either on DOL 3 after 2 days of TPN (EA group), or on DOL 6 after 5 days of TPN (LA group). (B) In Experiment 2, enteral formula (IG feeding with hydrolyzed casein) was introduced either abruptly (EA group) at 50% of their total feeding intake on DOL 3 after 2 days of TPN, or advanced gradually (EG group) starting at 10% of their total feeding intake on DOL 3 up to 50% on DOL 7 with a 10%-daily increase. Pigs were weighed every other day and their intake adjusted accordingly. Signs of NEC were monitored at each feed. Pigs were euthanized at signs of NEC or 5 d after start of IG feeding and tissues were collected. EA, early abrupt; LA, late abrupt. EG, early gradual.
Figure 2
Figure 2. Clinical NEC incidence, NEC severity scores, and stomach content weights in Experiment 1.
(A) Clinical NEC incidence values are the sum of all clinical NEC cases and expressed as percentage. Clinical NEC incidence was the same as histological NEC incidence. Combined, n = 22 (LA)-40 (EA); Hydrolyzed protein, n = 11 (LA)-27 (EA); Intact protein, n = 11 (LA)-13 (EA); *P<0.05, **P<0.01 EA vs. LA. (B) Clinical NEC severity scores determined in the stomach (Stom), jejunum (Jej), ileum (Ile), colon (Col) and all those 4 tissues combined (Tot). For each tissue, grades 1–2 represent “No NEC” and grades 3–6 represent “NEC”. For combined tissues, the maximum clinical NEC severity score is 24. EA, n = 40; LA, n = 22; *P<0.05, **P<0.01 EA vs. LA. (C) Histological NEC severity scores determined in the jejunum (Jej), ileum (Ile), colon (Col) and all those 3 tissues combined (Tot). For each tissue, grades 0–1 represent” No NEC” and grades 2–4 represent “NEC”. For combined tissues, the maximum histological NEC severity score is 12. EA, n = 40; LA, n = 22; *P<0.05, **P<0.01 EA vs. LA. (D) Stomach content weight values are expressed as g/kg of body weight (BW). Intact protein, n = 8 (EA)-10 (LA); Hydrolyzed protein, n = 10 (LA)-22 (EA); *P<0.05, **P<0.01 EA vs. LA. EA, early abrupt; LA, late abrupt.
Figure 3
Figure 3. Intestinal cross sections from Experiment 1.
Histological cross sections stained with H&E of the ileum from pigs fed either an intact or hydrolyzed protein formula without NEC (No NEC) or that had developed NEC (NEC). All images are presented at 10X magnification. EA, early abrupt; LA, late abrupt.
Figure 4
Figure 4. Survival analysis and linear regression analysis of NEC severity scores vs. survival in Experiment 1.
(A) Kaplan-Meier survival estimates determined after the first IG feeding and expressed as percentage. Results were not significant. EA, n = 40; LA, n = 22. (B) Linear regression analysis of clinical NEC severity scores vs. survival after the first IG feeding performed on combined EA and LA groups. For each pig, the clinical NEC severity score represents the sum of clinical NEC severity scores (total score) in stomach, jejunum, ileum and colon. Clinical NEC severity scores were negatively correlated with survival (n = 62; P<0.001, R = 0.773). (C) Linear regression analysis of histological NEC severity scores vs. survival after the first IG feeding performed on combined EA and LA groups. For each pig, the histological NEC severity score represents the sum of clinical NEC severity scores (total score) in jejunum, ileum and colon. Histological NEC severity scores were negatively correlated with survival (n = 62; P<0.001, R = 0.780). EA, early abrupt; LA, late abrupt.
Figure 5
Figure 5. Proinflammatory gene expression in the ileum of pigs in Experiment 1.
Gene expression values are expressed as fold change vs. the EA–Intact protein group (No NEC + NEC). β-actin was used as internal control. n = 19–39; *P<0.05 EA vs. LA. EA, early abrupt; LA, late abrupt.
Figure 6
Figure 6. Clinical and histological NEC incidence and NEC severity scores in Experiment 2.
(A) NEC incidence values are the sum of all clinical or histological NEC cases and expressed as percentage. Results were not significant. EA, n = 27; EG, n = 16. (B) Clinical NEC severity scores determined in the stomach (Stom), jejunum (Jej), ileum (Ile), colon (Col) and all those 4 tissues combined (Tot). For each tissue, grades 1–2 represent “No NEC” and grades 3–6 represent “NEC”. For combined tissues, the maximum clinical NEC severity score is 24. EA, n = 27; EG, n = 16. (C) Histological NEC severity scores determined in the jejunum (Jej), ileum (Ile), colon (Col) and all those 3 tissues combined (Tot). For each tissue, grades 0–1 represent “No NEC” and grades 2–4 represent “NEC”. For combined tissues, the maximum histological NEC severity score is 12. EA, n = 27; EG, n = 16; *P<0.05 EA vs. EG. EA, early abrupt; EG, early gradual.
Figure 7
Figure 7. Intestinal cross sections from Experiment 2.
Histological cross sections stained with H&E of the ileum in pigs without NEC (No NEC) or that had developed NEC (NEC). All Images are presented at 10X magnification. EA, early abrupt; EG, early gradual.
Figure 8
Figure 8. Survival analysis and linear regression analysis of NEC severity scores vs. survival in Experiment 2.
(A) Kaplan-Meier survival estimates determined after the first IG feeding and expressed as percentage. Results were not significant. EA, n = 27; EG, n = 16. (B) Linear regression analysis of clinical NEC severity scores vs. survival after the first IG feeding performed on combined EA and EG groups. For each pig, the clinical NEC severity score represents the sum of clinical NEC severity scores (total score) in stomach, jejunum, ileum and colon. Clinical NEC severity scores were negatively correlated with survival (n = 43; P<0.001, R = 0.685). (C) Linear regression analysis of histological NEC severity scores vs. survival after the first IG feeding performed on combined EA and EG groups. For each pig, the histological NEC severity score represents the sum of clinical NEC severity scores (total score) in jejunum, ileum and colon. Histological NEC severity scores were negatively correlated with survival (n = 43; P<0.001, R = 0.732). EA, early abrupt; EG, early gradual.
Figure 9
Figure 9. Proinflammatory gene expression in the ileum of pigs in Experiment 2.
Gene expression values are expressed as fold change vs. the EA–Hydrolyzed protein group (No NEC + NEC). β-actin was used as internal control. n = 12–27; *P<0.05 EA vs. EG. EA, early abrupt; EG, early gradual.

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References

    1. Tudehope DI (2005) The epidemiology and pathogenesis of neonatal necrotizing enterocolitis. J Paediatr Child Health 41: 167–168. - PubMed
    1. Henry MC, Moss RL (2009) Necrotizing enterocolitis. Annu Rev Med 60: 111–124. - PubMed
    1. Lin PW, Stoll BJ (2006) Necrotising enterocolitis. Lancet 368: 1271–1283. - PubMed
    1. Young C, Sharma R, Handfield M, Mai V, Neu J (2009) Biomarkers for infants at risk for necrotizing enterocolitis: clues to prevention? Pediatr Res 65: 91R–97R. - PMC - PubMed
    1. Cilieborg MS, Boye M, Sangild PT (2012) Bacterial colonization and gut development in preterm neonates. Early Hum Dev 88 Suppl 1 S41–S49. - PubMed

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