ESPE Abstracts

The gastrointestinal (GI) tract is the body's largest endocrine organ producing hormones that have important sensing and signaling roles in the regulation of energy homeostasis and immune mechanisms.

Objectives and Methods: We performed electronic literature systematic review using PubMed, Google Scholar, and Web of Sciences with the aim of providing an update on the changes occurring in gut hormones (Ghrelin, GLP-1 and PYY, insulin, and Zonulin) in malnourished infants and children as well as lab animals. We reviewed 20 studies (2007-2022) fitting the search criteria.

Results: Ghrelin is a multifaceted gut hormone that regulates glucose hemostasis. One study reported hyper-ghrelinemia in undernourished children. The high Ghrelin stimulates GH secretion which promotes lipolysis and maintains blood glucose through stimulating hepatic gluconeogenesis. GLP-1 is secreted in the small intestine in response to nutrients. It promotes glucose-dependent insulin secretion and decelerates gastric emptying. Intraluminal nutrients, particularly fats stimulate the secretion of PYY by enteroendocrine cells. Levels of GLP-1 and PYY were found to be considerably higher in undernourished infants compared to normal infants. The significant increase of these GI hormones during malnutrition help to delay gastric emptying and give a longer time for nutrient absorption. Many undernourished children suffer from subclinical enteropathy (EED) characterized by mucosal inflammation and villus blunting mediated by T cell activation. Zonulin is a hormone secreted mainly from the liver and enterocytes. It is a master modulator of the intercellular tight junctions (TJ) and is a key player in the regulation of the mucosal immune response. Serum zonulin levels are correlated with stunted growth in EED patients. Vitamin D deficiency, a common association in undernourished children, could lead to a significant upregulation in mRNA expression of the intestinal zonulin that increases the serum level of zonulin. In a meta-analysis review of 16 studies severely undernourished children had a high prevalence of hypoglycemia. Impaired insulin responses to oral glucose and to a meal occur in both kwashiorkor and marasmus, with low glucose clearance. A low insulin state decreases tissue and fat anabolism and permits the catabolic activity of other hormones to ensure energy supply for vital organs. Insulin is important in shaping the immune response during infection, therefore, low insulin status in severely undernourished children may adversely affect their immune response during an infection.

Conclusion: Changes in gut hormones play an important role in the adaptation process during malnutrition however these changes may adversely affect local and systemic immune mechanisms.