Serum glucagon-like peptide-2 levels in neonates: comparison between extremely low-birthweight infants and normal-term infants

Advances in glucagon like peptide-2 therapy. physiology, current indications and future directions

The treatment paradigm for pediatric patients with short bowel syndrome (SBS) and intestinal failure (IF) has changed significantly over recent years; the development of dedicated IF teams, refinements in PN and surgical treatments have greatly improved survival. The majority of SBS patients undergo intestinal adaptation such that nutrient absorption from enteral feeds increases and the child can come off of PN. This "adaptation" or upregulation in nutrient absorptive capacity is still poorly understood; the enteric hormone Glucagon like peptide 2 (GLP-2) appears to be a key regulator in this process. The development of Teduglutide, a long acting GLP-2 ligand as a therapy to specifically enhance adaptation has been anticipated as a further shift in the paradigm. This article reviews the physiology of GLP-2 with an emphasis on the known or potential roles in infants and children with SBS and IF. The results and implications of the present studies and approved indications for GLP-2 and its ligands are discussed. Finally, the potential future uses of GLP-2 ligands in the pediatric population are considered.

The glucagon like peptide-2 'axis': Capacity for production and response following intestinal resection or repair of gastroschisis in infants

PURPOSE

This study investigates the relationship between the enteric hormone glucagon-like peptide 2 (GLP-2) production, sensitivity, and intestinal adaptation in infants following resection or repair of gastroschisis.

METHODS

With IRB approval (UCalgary #10656), consent was obtained from families of infants undergoing surgery for prospective monitoring of nutritional status, GLP-2 levels, and where possible, tissue sampling.

RESULTS

Infants who adapted and weaned from parenteral nutrition (PN) had increased GLP-2 (86±32) n=24 vs. controls: 45±20 n=10 and vs. patients on prolonged PN: 42±6 pM, n=10). This was maintained to one year: weaned patients: 72±49 vs. non-weaned: 35±15 pM (p<0.05). Infants with gastroschisis (n=33) had decreased GLP-2 levels until enteral function was achieved and then became elevated: (21±15 with first feeding vs. 102±60 at full feeds and 60±19 pM at one year). There were no changes in the density or distribution of GLP-2 producing L-cells related to gestational age, nor in the expression of the GLP-2 receptor.

CONCLUSION

GLP-2 levels correlate with intestinal adaptation in infants, and with recovery of intestinal function in gastroschisis. GLP-2 productive capacity (L-cell expression) and GLP-2 receptor expression do not vary with maturity. The findings support a role for GLP-2 in regulating intestinal function. Further study is suggested.

Teduglutide-Stimulated Intestinal Adaptation Is Complemented and Synergistically Enhanced by Partial Enteral Nutrition in a Neonatal Piglet Model of Short Bowel Syndrome

BACKGROUND

Teduglutide, a glucagon-like peptide-2 (GLP-2) analogue, is available for long-term use by parenteral nutrition (PN)-dependent adults to promote intestinal adaptation but is not approved for use in pediatric patients. The objective of this study was to assess teduglutide-stimulated induced intestinal adaptation, potential synergies with partial enteral nutrition (PEN), and distinct temporal markers of adaptation in a neonatal piglet model of short bowel syndrome (SBS).

MATERIALS AND METHODS

Neonatal piglets (48 hours old; n = 72) underwent an 80% jejunoileal resection and were randomized to 1 of 4 treatment groups, in a 2 × 2 factorial design, with PN or PEN (80% standard PN/20% standard enteral nutrition) and teduglutide (0.1 mg/kg/d) or control. Piglets received nutrient infusions for 4 hours, 48 hours, or 7 days.

RESULTS

Teduglutide improved ( P < .05) mucosal surface area (villus height: duodenum, jejunum, ileum; crypt depth: ileum, colon; proliferation: duodenum, jejunum, ileum; colon; apoptosis: jejunum, ileum, colon) and acute nutrient processing capacity (glucose: duodenum, jejunum, ileum; glutamine: duodenum, jejunum). These effects were complemented and synergistically enhanced by PEN in both site and timing of action. Structural adaptations preceded functional adaptations, but crypt depth remained a strong indicator of adaptation, regardless of time.

CONCLUSIONS

The combination of teduglutide and PEN enhances intestinal adaptation beyond that of either therapy alone.

The assessment, and glucagon-like peptide-2 modulation, of intestinal absorption and function

The treatment of patients with short bowel syndrome is hampered by a lack of treatment and measurement methods. This article reviews our evolving understanding of the role of glucagon-like peptide 2 (GLP-2) in controlling the adaptive process. The ability of the remnant intestine to produce GLP-2 appears to be predictive of the adaptive process; exogenous GLP-2 may be a therapy to augment adaptation. Strategies for monitoring patients, including conventional means, such as anthropomorphic measurements, plasma levels of specific nutrients, and vitamins and radiological contrast studies are reviewed. Investigational methods, such as nutrient balance studies, plasma citrulline levels, and the absorption of inert sugars (3-0 methyl glucose, mannitol, and lactulose) are discussed with the evidence to support their use.

Functional ontogeny of the proglucagon-derived peptide axis in the premature human neonate

BACKGROUND

The regulation of intestinal growth and development in human neonates is incompletely understood, which hinders the provision of nutrients enterally. The "hindgut" hormones glucagon-like peptides 1 and 2 have been shown to play an important role in the regulation of nutrient assimilation, intestinal growth, and function.

OBJECTIVE

Our goal was to investigate the production of glucagon-like peptides 1 and 2 in premature human infants and examine the effects of prematurity and feeding on hormone release.

PATIENTS AND METHODS

With informed consent, premature infants who were admitted to a tertiary neonatal intensive care nursery (gestational age: 28-32 weeks) were monitored with weekly determinations of postprandial glucagon-like peptide 1 and 2 levels. Comparison studies with groups of normal infants and adults were performed. Hormone levels were obtained by using specific radioimmunoassay for glucagon-like peptide 1 (1-36) and glucagon-like peptide 2 (1-33), modified for small sample volumes; accurate monitoring of enteral intake was performed at all of the sampling time points.

RESULTS

Forty-five infants with a mean gestational age of 29.6 +/- 1.9 weeks were studied; fasting levels of both glucagon-like peptides 1 and 2 were elevated. There was no correlation between gestational age and glucagon-like peptide 2 output. However, both glucagon-like peptide 1 and 2 levels were correlated with the caloric value of feeds.

CONCLUSIONS

The premature human neonate has significantly higher fasting levels of glucagon-like peptides 1 and 2 compared with adults; feeding increases these levels further. These findings suggest that the proglucagon-derived peptides may have a role in normal intestinal development and nutrient handling.