Non-targeted metabolomics of intestinal contents of neonatal rats with necrotizing enterocolitis / 中国新生儿科杂志

ABSTRACT

Objective To study the change and characterization of metabolic profile of intestinal contents of the neonatal rats with necrotizing enterocolitis (NEC) using metabolomics approach,in order to figure out potential biomarkers of NEC.Method Twenty rats with three-postnatal day-old fed with special formula were assigned to control group (n =8) and NEC group (n =12) randomly.Experimental NEC of rats in NEC group were induced by exposing to cold stimulation at 4 degrees Celsius for 10 minutes and to hypoxia at 95％ nitrogen for 10 minutes,three times a day for three consecutive days.All the rats were sacrificed after model preparation.Segments of the ileum of all the rats were collected for hematoxylin-eosin staining and subsequent pathological damage evaluation.The intestinal contents of the ileum and colon were collected by perfusion,followed by lyophilization and analyzed by UHPLC-QE-MS in order to conduct the non-target metabolomic determination.The information of the metabolites determined was calculated by multivariable analysis using SIMCA software.Result The pathological damage scores of NEC group were higher than those of the control group [(3.13 ± 0.83) vs.(0.25 ± 0.46),P ＜ 0.001].The results of orthogonal partial least squares discriminant analysis (OPLS-DA) model showed that in the ESI + mode,R2(x) =0.604,R2(y) =0.583,Q2 =0.960,while in the ESI-mode,the OPLS-DA model R2(x) =0.828,R2(y) =0.999,and Q2 =0.713,indicating that there is a significant difference in the intestinal content metabolic profile between the control group and the NEC group.Forty-eight differential metabolites related to NEC were identified.In ESI-mode,there were 22 differential metabolites,including L-isoisoleucine (+ 221％) and D-phenylalanine (+ 230％),L-histidine (+ 284％),xanthine (+ 207％),glutamyl leucine (+ 246％),allose (-70％),myristic acid (-57％) and pentadecanoic acid (-35％).What is more,in the ESI + mode,26 other differential metabolites were identified,including ornithine (+ 268％),D-leucine (+ 176％),L-iso Leucine (+ 213％),acetylcholine (+ 195％),nicotinamide adenine dinucleotide (+ 199％),citrulline (+ 158％),cytosine (-58％),xanthoic acid (-64％).These metabolites were reflected to 33 different metabolic pathways in KEGG databases.The pathway enrichment analysis and pathway topology analysis with MetaboAnalyst indicated that the arginine and proline metabolic pathways,histidine metabolic pathways,and glutathione metabolic pathways were the top altered pathways in the condition of NEC.Conclusion The metabolic profile of intestinal contents in NEC rats was significantly different from that in normal rats,which was characterized by amino acid accumulation,mainly involving the metabolic pathways of arginine,proline,histidine and glutathione.The detection of intestinal contents metabolic profile,especially amino acid metabolize group may be of great significance for the diagnosis of NEC,and improving intestinal microenvironment may be the key strategy for the prevention and treatment of NEC.