691 - Flt-1 Is Increased in the Serum During the Development of Necrotizing Enterocolitis

Publication Number: 1668.691

Lorena Ostilla, Ann & Robert H. Lurie Children's Hospital of Chicago, Chicago, IL, United States; Xiaocai Yan, Lurie children hospital of Chicago, Chicago, IL, United States; Elizabeth Managlia, Lurie Children's Hospital, Chicago, IL, United States; Isabelle De Plaen, Ann & Robert H. Lurie Children's Hospital of Chicago, Chicago, IL, United States

Background: Necrotizing enterocolitis (NEC) is a disease affecting premature infants characterized by intestinal inflammation and necrosis that commonly evolves into sepsis and death. There is evidence that impaired intestinal VEGF/VEGFR2 signaling resulting in microvasculature maldevelopment contributes to NEC. We previously found that inhibiting monocyte activation preserves gut microvascular density and protects against experimental NEC. We have preliminary evidence that monocytes and pro-inflammatory macrophages express VEGFR1/Flt-1 in both mouse and human NEC tissues. When released, soluble Flt-1(sFlt-1) traps VEGF, reducing VEGFR2 signaling and angiogenesis. Whether sFlt-1 is increased in serum prior to NEC development in mice and humans remains unknown.

Objective: To determine if serum sFLT-1 levels are increased during the development of NEC.

Design/Methods: Neonatal mice were subjected to our NEC model (adult commensal bacteria, hypoxic and cold stresses twice a day and formula feeding) or left with the dams to be dam fed (DF)(controls). Mice were euthanized at 48 or 72 hours(h) and serum was collected and frozen at-80°C. Serum sFlt-1 was compared between DF and NEC by ELISA. To assess the stability of sFlt-1 at room temperature (RT), 3 NEC serum samples were divided into 4 aliquots that were either left at RT for 2, 8 or 24h or immediately frozen at -80°C. sFlt-1 concentration was compared amongst the conditions. To determine whether serum sFlt-1 can help predict evolving NEC in humans, leftover plasma, serum and cord blood were collected from < 34 weeks gestational age infants. These patients were followed prospectively throughout admission and sFLT-1 was compared between the infants that developed medical and surgical NEC to those who did not using ELISA.

Results: In mice subjected to our NEC protocol, serum sFlt-1 concentration (ng/ml) was higher at 48h (25.05 ± 3.008 vs 14.81 p< 0.05) and 72h (mean 36.77 ± 2.906 vs 20.47 p< 0.001) when compared to DF littermate controls. Compared to frozen controls, serum sFlt-1 levels remain unchanged when samples were left at RT for up to 24h. In neonates with a recent NEC diagnosis, sFLT-1 concentrations were higher(mean 7.93 ± vs 79.65, p< 0.0001) vs control.

Conclusion(s): In neonatal mice soluble sFlt-1 was increased in the serum during NEC development. In infants, sFLT-1 was significantly higher in the serum of recently established NEC diagnosis compared to control. Using our approved IRB (2025), next we plan to assess whether increased serum sFLT-1 predicts NEC onset in neonates by comparing sFLT-1 serum levels prior to NEC development (vs age matched controls).