The Assessment of Fecal Volatile Organic Compounds During Experimental Necrotizing Enterocolitis
Background: Necrotizing enterocolitis (NEC) remains a devastating disease that affects the gastrointestinal tract of the preterm infant. There is currently no biomarker that can diagnose NEC early with high sensitivity and specificity. Volatile organic compounds (VOCs) have emerged as a non-invasive biomarker in many diseases. We hypothesized that fecal VOC profiles would be significantly different between control and NEC pups in a mouse model of experimental necrotizing enterocolitis.
Methods: Experimental NEC was induced in five-day-old C57BL/6J mice by gavage feeding, hypoxia, and hypothermia. Breastfed and formula-fed control groups were also studied. Pups were monitored daily for weight gain and clinical sickness scores. After four days, pups were euthanized and intestines were H&E stained and blindly scored. Additional intestine was homogenized and assessed for TLR4 by western blot. Stool microbiome analysis was performed via 16s rRNA sequencing. After stool was heated to mimic internal temperature, VOC analysis was assessed by the Cyranose® 320 eNose device with thirty-two polymer nanocomposite sensors. Kruskal-Wallis and PERMAOVA test on Euclidean distances were used, and p<0.05 was significant.
Results: NEC pups had significantly worse weight gain and clinical sickness scores than both breastfed and formula-fed controls. Additionally, NEC pups had severe intestinal injury and elevation in TLR4 when compared to controls. Microbiome analysis showed that both control groups had significantly higher microbial diversity and relative abundance of Lactobacillaceae than NEC. Fecal VOC analysis showed that the overall VOC profile for NEC pups was significantly different from controls (p<0.0011), and nine of thirty-two individual sensors were significantly different.
Conclusion: Fecal VOC analysis by the Cyranose® 320 eNose device can discriminate NEC pups from both breastfed and formula-fed controls. Further research is warranted to establish whether fecal VOCs can be used as a biomarker or predictive algorithm to diagnose NEC.