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Marked methylation changes of intestinal genes in the neonatal period of preterm neonates

ABSTRACT: We hypothesized that the immature pig intestine would be highly sensitive to gene methylation changes in the immediate prenatal and neonatal periods. We performed a Reduced Representation Bisulfite Sequencing (RRBS) to assess the DNA methylation differences occurring during the last 10 days prenatally (PN, 0d-term vs. 0d-preterm), neonatally after 4 days (NN, 4d-preterm vs. 0d-preterm) and after NEC development (4d-preterm-NEC vs. 4d-preterm) in pigs (each group n=2-3). Differentially methylated gene regions (DMRs) between the groups were identified, subjected to KEGG (Kyoto Encyclopedia of Genes and Genomes) pathway analysis and selected genes were chosen for further validation of gene expression levels by RT-PCR (n= 6 for each group). Consistent with the need to increase expression of many intestinal genes in the perinatal period, methylation levels of most genes decreased during the prenatal and neonatal periods. We identified four intestinal genes (CYP2W1, GPR146, TOP1MT, CEND1), related to intestinal metabolism, that were significantly hyper-methylated in their promoter CGIs, and transcriptionally down-regulated in the 4 d-old preterm pigs. This down-regulation of intestinal metabolism may predispose to intestinal dysfunction and NEC. The first enteral feeds and bacterial colonization are critical factors for NEC sensitivity and it remains to be investigated whether these factors affect intestinal gene methylation and thereby predispose to, or prevent from, disease more long term.

ORGANISM(S): Sus scrofa

PROVIDER: GSE53747 | GEO | 2014/12/31

SECONDARY ACCESSION(S): PRJNA232784

REPOSITORIES: GEO

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Project description:Chorioamnionitis (CA), resulting from intra-amniotic inflammation, is a frequent cause of preterm birth and exposes the immature intestine to bacterial toxins and/or inflammatory mediators before birth via fetal swallowing. This may affect intestinal immune development, interacting with the effects of enteral feeding and gut microbiota colonization just after birth. Using preterm pigs as model for preterm infants, we hypothesized that prenatal exposure to gram-negative endotoxin influences postnatal bacterial colonization and gut immune development. Pig fetuses were given intra-amniotic lipopolysaccharide (LPS) 3 d before preterm delivery by cesarean section, and were compared with litter-mate controls (CON) at birth and after 5 d of formula feeding and spontaneous bacterial colonization. Amniotic fluid was collected for analysis of leukocyte counts and cytokines, and the distal small intestine was analyzed for endotoxin level, morphology and immune cell counts. Intestinal gene expression and microbiota were analyzed by transcriptomics and metagenomics, respectively. At birth, LPS-exposed pigs showed higher intestinal endotoxin, neutrophil/macrophage density and shorter villi. About 1.0% of intestinal genes were affected at birth and DMBT1, a regulator of mucosal immune defense, was identified as the hub gene in the co-expression network. Genes related to innate immune response (TLR2, LBP, CD14, C3, SFTPD), neutrophil chemotaxis (C5AR1, CSF3R, CCL5) and antigen processing (MHC II, CD4) were also affected and expression levels correlated with intestinal neutrophil/macrophage density and amniotic fluid cytokine levels. On day 5, LPS and CON pigs showed similar necrotizing enterocolitis (NEC) lesions, endotoxin levels, morphology, immune cell counts, gene expressions and microbiota (except for difference in some low-abundant species). Our results show that CA markedly affects intestinal genes at preterm birth, including genes related to immune cell infiltration. However, a few days later, following the physiological adaptations to preterm birth, CA had limited effects on intestinal structure, function, gene expression, bacterial colonization and NEC sensitivity. We conclude that short-term, prenatal intra-amniotic inflammation is unlikely to exert marked effects on intestinal immune development in preterm neonates beyond the immediate neonatal period.

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Marked methylation changes of intestinal genes in the neonatal period of preterm neonates

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