Durability of Linear Small-Intestinal Growth Following Treatment Discontinuation of Long-Acting Glucagon-Like Peptide 2 (GLP-2) Analogues.

BACKGROUND: Short-bowel syndrome is the leading cause of pediatric intestinal failure, resulting in dependency on long-term parenteral nutrition (PN). To promote enteral autonomy in neonates, a key outcome may be intestinal growth in length. The purpose of this study was to determine if intestinal lengthening persists following discontinuation of treatment with 1 of 2 GLP-2 analogues with different pharmacokinetic profiles. METHODS: Neonatal short-bowel piglets were assigned to saline control (S), 7-day treatment with teduglutide (T) (0.05 mg/kg twice daily), or 7-day treatment with apraglutide (A) (5 mg/kg twice weekly). Comparisons were made between day 7 and day 14 endpoints using analysis of variance. Data included small-intestine length, weight, histology, and quantitative polymerase chain reaction analysis of mucosal transcripts for peptide growth factors and their receptors, nutrient transporters, and tight-junction proteins. RESULTS: Compared with control, 7 days of GLP-2 analogue treatment induced mucosal adaptation based on villus hyperplasia (P = .003), which was not durable 7 days after treatment cessation (day 14; P = .081). Treatment increased intestinal growth in length by day 7 (P = .005), which was maintained (by T) or further increased (by A) at day 14 (P < .001). No significant differences in mucosal transcripts were detected. CONCLUSION: Unlike mucosal adaptation, intestinal growth appears to be a lasting outcome of treatment with long-acting GLP-2 analogues in a neonatal piglet short-bowel model. This has significant clinical implications for neonates, given their potential for intestinal growth. Intestinal lengthening varies between analogues with different half-lives; however, molecular mechanisms require further elucidation.

Essential Role of Syntaxin-Binding Protein-1 in the Regulation of Glucagon-Like Peptide-1 Secretion.

Circadian secretion of the incretin, glucagon-like peptide-1 (GLP-1), correlates with expression of the core clock gene, Bmal1, in the intestinal L-cell. Several SNARE proteins known to be circadian in pancreatic α- and ß-cells are also necessary for GLP-1 secretion. However, the role of the accessory SNARE, Syntaxin binding protein-1 (Stxbp1; also known as Munc18-1) in the L-cell is unknown. The aim of this study was to determine whether Stxbp1 is under circadian regulation in the L-cell and its role in the control of GLP-1 secretion. Stxbp1 was highly-enriched in L-cells, and STXBP1 was expressed in a subpopulation of L-cells in mouse and human intestinal sections. Stxbp1 transcripts and protein displayed circadian patterns in mGLUTag L-cells line, while chromatin-immunoprecipitation revealed increased interaction between BMAL1 and Stxbp1 at the peak time-point of the circadian pattern. STXBP1 recruitment to the cytosol and plasma membrane within 30 minutes of L-cell stimulation was also observed at this time-point. Loss of Stxbp1 in vitro and in vivo led to reduced stimulated GLP-1 secretion at the peak time-point of circadian release, and impaired GLP-1 secretion ex vivo. In conclusion, Stxbp1 is a circadian regulated exocytotic protein in the intestinal L-cell that is an essential regulatory component of GLP-1 secretion.