O1110: Glucagon-like Peptide 1 Receptor Signalling Mediates the Protective Response of Remote Ischemic Conditioning in NEC

Background: Necrotizing enterocolitis (NEC) remains one of the most severe gastrointestinal emergencies affecting premature infants and is commonly associated with intestinal ischemia and necrosis. Experimentally, it has been shown that Remote Ischemic Conditioning (RIC) reduces the severity of NEC intestinal damage. Organ-protective signaling pathways initiated from the limb undergoing RIC remain incompletely understood. We hypothesize that peripheral vagal afferent/efferent neural pathways are activated by RIC within the gut-brain axis. Notably, the stimulation of the gastric branches of the vagal nerve recruit actions of an incretin hormone, glucagon like-peptide-1 (GLP-1) which has regulatory roles in metabolism, vascular dynamics, and regeneration maybe a likely humoral initiator of RIC’s protective response in the intestine. Herein, we aimed to understand the role of GLP1 as the neural and humoral mediator of RIC in NEC.

Methods: Post-natal development - Terminal ileum was harvested at p1 (premature intestine) and p9 (mature intestine) mice. To characterize GLP1 activity during normal post-natal development, we compared the gene expression (RT-qPCR) of GLP1 receptor (GLP1R) at p1 and p9.
Human NEC – Following ethical approval, ileal biopsy specimens were acquired from NEC patients undergoing surgery. Control tissue was acquired from age and sex matched patients who underwent surgery for other non-inflammatory colonic or small bowel surgery.
Mouse model of NEC – NEC was induced in postnatal day 5 (p5) mice using hypoxia, gavage feeding (hyperosmolar formula), and oral lipopolysaccharide (4mg/kg). On p6 and p8, RIC was applied on the right hind limb by 5 minutes of ischemia using a tourniquet followed by 5 minutes of reperfusion, and this cycle was repeated for 4 times. Breastfed pups at p9 served as control. We then compared the gene and protein expression (immunofluorescence) of GLP1R in control (p9), NEC, and NEC+RIC groups.

Results: In the neonatal mouse, during normal post-natal development, we observe that GLP1R is differentially expressed in early (p5) vs late (p9) post-natal period in the small bowel, which may increase susceptibility to NEC injury (Figure 9a). Our preliminary findings confirm that GLP1R (red) expression is reduced in intestinal epithelial cells in human NEC compared to aged-matched controls (Figure 9b). We subsequently found that RIC increased the gene and protein expression of GLP1R in the intestine during NEC (Figure 9c).

Conclusion: GLP1R signalling has a role in intestinal maturation during post-natal development. Downregulation of GLP1R signalling can increase susceptibility to NEC injury. Peripheral vagal neural signalling initiated by RIC activates GLP1R signalling in NEC, which can have a role in intestinal recovery.