Enteral nutrients potentiate glucagon-like peptide-2 action and reduce dependence on parenteral nutrition in a rat model of human intestinal failure

Glucagon-Like Peptide-2 Modulates Enteric Paneth Cells Immune Response and Alleviates Gut Inflammation During Intravenous Fluid Infusion in Mice With a Central Catheter

Background: Glucagon-like peptide-2 (GLP-2) has protective effects on gastrointestinal functions. Our previous study found that GLP-2 could significantly reduce intestinal permeability and bacterial translocation in total parenteral nutrition (TPN) animal model. However, the effects of GLP-2 on the impairment of the intestinal Paneth cells immune function and gut inflammation during intravenous fluid infusion mainly consisted of nutritional materials is currently scattered.

Objective: The current study was aimed to investigate the efficacy of the GLP-2 in alleviating gut inflammation and modulating enteric Paneth cells immune response in parenterally fed mice and its underlying mechanisms.

Methods: Thirty-six male ICR mice underwent venous catheterization were divided into 3 groups: Chow, TPN, and TPN+GLP-2 groups. GLP-2 was administered intravenously at 60 μg/day for 5 days. The small intestine tissue and serum samples were collected on the 7th day.

Results: Compared with the TPN group, the expression of tight junction proteins occludin and claudin-1 were significantly increased in the TPN+GLP-2 group. In addition, the expression of lysozyme, sPLA2, insulin-like growth factor-1, and epithelial protection and repair genes were improved in the TPN+GLP-2 group. The levels of IL-6 and TNF-α proteins and mRNAs in the ileum tissues were remarkably reduced in the TPN+GLP-2 group, while IL-10 protein and mRNA level were elevated in the TPN+GLP-2 group (all p < 0.05). Moreover, the TPN+GLP-2 group has higher levels of serum endotoxin, D-lactic acid, and MPO than those of the TPN group.

Conclusions: GLP-2 alleviated gut inflammation and improved enteric Paneth cells immune responses through intravenous fluid infusion, possibly by improving the functioning of epithelial protection and repair, and reducing mucosal inflammatory responses.

Short Bowel Syndrome: A Paradigm for Intestinal Adaptation to Nutrition?

Short bowel syndrome (SBS) is a rare disease that results from extensive resection of the intestine. When the remaining absorption surface of the intestine cannot absorb enough macronutrients, micronutrients, and water, SBS results in intestinal failure (IF). Patients with SBS who suffer from IF require parenteral nutrition for survival, but long-term parenteral nutrition may lead to complications such as catheter sepsis and metabolic diseases. Spontaneous intestinal adaptation occurs weeks to months after resection, resulting in hyperplasia of the remnant gut, modification of gut hormone levels, dysbiosis, and hyperphagia. Oral nutrition and presence of the colon are two major positive drivers for this adaptation. This review aims to summarize the current knowledge of the mechanisms underlying spontaneous intestinal adaptation, particularly in response to modifications of luminal content, including nutrients. In the future, dietary manipulations could be used to treat SBS.

The Misshapen subfamily of Ste20 kinases regulate proliferation in the aging mammalian intestinal epithelium

The intestinal epithelium has a high rate of cell turn over and is an excellent system to study stem cell-mediated tissue homeostasis. The Misshapen subfamily of the Ste20 kinases in mammals consists of misshapen like kinase 1 (MINK1), mitogen-activated protein kinase kinase kinase kinase 4 (MAP4K4), and TRAF2 and NCK interacting kinase (TNIK). Recent reports suggest that this subfamily has a novel function equal to the Hippo/MST subfamily as upstream kinases for Warts/Large tumor suppressor kinase (LATS) to suppress tissue growth. To study the in vivo functions of Mink1, Map4k4, and Tnik, we generated a compound knockout of these three genes in the mouse intestinal epithelium. The intestinal epithelia of the mutant animals were phenotypically normal up to approximately 12 months. The older animals then exhibited mildly increased proliferation throughout the lower GI tract. We also observed that the normally spatially organized Paneth cells in the crypt base became dispersed. The expression of one of the YAP pathway target genes Sox9 was increased while other target genes including CTGF did not show a significant change. Therefore, the Misshapen and Hippo subfamilies may have highly redundant functions to regulate growth in the intestinal epithelium, as illustrated in recent tissue culture models.

Ingestion of Food Particles Regulates the Mechanosensing Misshapen-Yorkie Pathway in Drosophila Intestinal Growth

The intestinal epithelium has a high cell turnover rate and is an excellent system to study stem cell-mediated adaptive growth. In the Drosophila midgut, the Ste20 kinase Misshapen, which is distally related to Hippo, has a niche function to restrict intestinal stem cell activity. We show here that, under low growth conditions, Misshapen is localized near the cytoplasmic membrane, is phosphorylated at the threonine 194 by the upstream kinase Tao, and is more active toward Warts, which in turn inhibits Yorkie. Ingestion of yeast particles causes a midgut distention and a reduction of Misshapen membrane association and activity. Moreover, Misshapen phosphorylation is regulated by the stiffness of cell culture substrate, changing of actin cytoskeleton, and ingestion of inert particles. These results together suggest that dynamic membrane association and Tao phosphorylation of Misshapen are steps that link the mechanosensing of intestinal stretching after food particle ingestion to control adaptive growth.

Choline Protects Against Intestinal Failure-Associated Liver Disease in Parenteral Nutrition-Fed Immature Rats

BACKGROUND

Deficiency of choline, a required nutrient, is related to intestinal failure-associated liver disease (IFALD). Therefore, we aimed to investigate the effects of choline supplementation on IFALD and the underlying mechanisms.

METHODS

Male Sprague-Dawley rats (4 weeks old) were fed AIN-93G chow and administered intravenous 0.9% saline (control), parenteral nutrition (PN), or PN plus intravenous choline (600 mg/kg) for 7 days. We evaluated body weight, hepatic histology, biochemical indicators, triglycerides, oxidative status, methylation levels of peroxisomal proliferator-activated receptor alpha (PPARα) gene promoter, expression of PPARα and carnitine palmitoyltransferase 1 (CPT1), and levels of choline metabolites.

RESULTS

The PN + choline group exhibited improved body weight compared with the PN group. PN impaired hepatic function, increased hepatic triglycerides, induced dyslipidemia, enhanced reactive oxygen species and malondialdehyde, and reduced total antioxidant capacity. The PN group had higher pathologic scores than the control group. These results were prevented by choline administration. Compared with the control group, PN increased PPARα promoter methylation and hepatic betaine concentration, reduced hepatic choline and phosphatidylcholine (PC) levels, decreased plasma choline and betaine concentrations, and downregulated PPARα and CPT1 mRNA and protein expression. Choline supplementation elevated hepatic choline and PC levels and enhanced plasma choline, betaine, and PC concentrations but reduced hepatic betaine level, reversed PPARα promoter hypermethylation, and upregulated PPARα and CPT1 mRNA and protein expression in PN-fed rats, compared with rats receiving PN alone.

CONCLUSION

Choline addition to PN may prevent IFALD by reducing oxidative stress, enhancing hepatic fat export, and promoting fatty acid catabolism in immature rats receiving PN.

Interdependency of EGF and GLP-2 Signaling in Attenuating Mucosal Atrophy in a Mouse Model of Parenteral Nutrition

BACKGROUND & AIMS

Total parenteral nutrition (TPN), a crucial treatment for patients who cannot receive enteral nutrition, is associated with mucosal atrophy, barrier dysfunction, and infectious complications. Glucagon-like peptide-2 (GLP-2) and epidermal growth factor (EGF) improve intestinal epithelial cell (IEC) responses and attenuate mucosal atrophy in several TPN models. However, it remains unclear whether these 2 factors use distinct or overlapping signaling pathways to improve IEC responses. We investigated the interaction of GLP-2 and EGF signaling in a mouse TPN model and in patients deprived of enteral nutrition.

METHODS

Adult C57BL/6J, IEC-Egfr^{knock out (KO)} and IEC-pik3r1^KO mice receiving TPN or enteral nutrition were treated with EGF or GLP-2 alone or in combination with reciprocal receptor inhibitors, GLP-2(3-33) or gefitinib. Jejunum was collected and mucosal atrophy and IEC responses were assessed by histologic, gene, and protein expression analyses. In patients undergoing planned looped ileostomies, fed and unfed ileum was analyzed.

RESULTS

Enteral nutrient deprivation reduced endogenous EGF and GLP-2 signaling in mice and human beings. In the mouse TPN model, exogenous EGF or GLP-2 attenuated mucosal atrophy and restored IEC proliferation. The beneficial effects of EGF and GLP-2 were decreased upon Gefitinib treatment and in TPN-treated IEC-Egfr^KO mice, showing epidermal growth factor-receptor dependency for these IEC responses. By contrast, in TPN-treated IEC-pi3kr1^KO mice, the beneficial actions of EGF were lost, although GLP-2 still attenuated mucosal atrophy.

CONCLUSIONS

Upon enteral nutrient deprivation, exogenous GLP-2 and EGF show strong interdependency for improving IEC responses. Understanding the differential requirements for phosphatidylinositol 3-kinase/phosphoAKT (Ser473) signaling may help improve future therapies to prevent mucosal atrophy.

Inducible and neuronal nitric oxide synthases exert contrasting effects during rat intestinal recovery following fasting

We investigated the effects of endogenous inducible (iNOS) and neuronal nitric oxide synthase on recovery from intestinal mucosal atrophy caused by fasting-induced apoptosis and decreased cell proliferation during refeeding in rats. Rats were divided into five groups, one of which was fed ad libitum, and four of which underwent 72 h of fasting, followed by refeeding for 0, 6, 24, and 48 h, respectively. iNOS and neuronal nitric oxide synthase mRNA and protein levels in jejunal tissues were measured, and mucosal height was histologically evaluated. Apoptotic indices, interferon-γ (IFN-γ) transcription levels, nitrite levels (as a measure of nitric oxide [NO] production),8-hydroxydeoxyguanosine formation (indicating reactive oxygen species [ROS] levels), crypt cell proliferation, and the motility indices (MI) were also estimated. Associations between mucosal height and NOS protein levels were determined using Spearman's rank correlation test. Notably, we observed significant increases in mucosal height and in neuronal nitric oxide synthase mRNA and protein expression as refeeding time increased. Indeed, there was a significant positive correlation between neuronal nitric oxide synthase protein level and mucosal height during the 48-h refeeding period ( r = 0.725, P < 0.01). Conversely, iNOS mRNA and protein expression decreased according to refeeding time, with a significant negative correlation between iNOS protein level and mucosal height being recorded during the 48-h refeeding period ( r = -0.898, P < 0.01). We also noted a significant negative correlation between jejunal neuronal nitric oxide synthase and iNOS protein concentrations over this same period ( r = -0.734, P < 0.01). Refeeding also restored the decreased jejunal MI caused by fasting. Our finding suggests that refeeding likely repairs fasting-induced jejunal atrophy by suppressing iNOS expression and subsequently inhibiting NO, ROS, and IFN-γ as apoptosis mediators, and by promoting neuronal nitric oxide synthase production and inducing crypt cell proliferation via mechanical stimulation. Impact statement Besides providing new data confirming the involvement of iNOS and nNOS in intestinal mucosal atrophy caused by fasting, this study details their expression and function during recovery from this condition following refeeding. We demonstrate a significant negative correlation between iNOS and nNOS levels during refeeding, and associate this with cell proliferation and apoptosis in crypts and villi. These novel findings elucidate the relationship between these NOS isoforms and its impact on recovery from intestinal injury. A mechanism is proposed comprising the up-regulation of nNOS activity by mechanical stimulation due to the presence of food in the intestine, restricting iNOS-associated apoptosis and promoting cell proliferation and gut motility. Our investigation sheds light on the molecular basis behind the repercussions of total parenteral nutrition on intestinal mucosal integrity, and more importantly, the beneficial effects of early enteral feeding.

Nutritional strategies to enhance adaptation in intestinal failure

PURPOSE OF REVIEW

This article summarizes the current and potential future nutritional approaches to stimulate adaptation in intestinal failure. Adaptation in this context usually refers to intestinal adaptation but also involves changes in whole body physiology as well as in eating/drinking behavior.

RECENT FINDINGS

Adaptation largely depends on residual functional anatomy. Luminal exposure to complex nutrients is the most important trigger for intestinal adaptation. Enteral fat as well as enteral or parenteral short chain fatty acids have a specific stimulatory effect. Zinc and vitamin A status need to be optimized for adaptation to proceed and be maintained. In the context of maintaining sodium and water homeostasis, flushing the remnant intestine because of uncontrolled thirst/drinking must be avoided. Complications of nutritional care such as malnutrition, intestinal failure-associated liver disease, and recurrent line sepsis also need optimal management.

SUMMARY

Stimulation by luminal nutrients as well as prophylaxis against and treatment of (nutritional) complications are the cornerstones of adaptation to the short bowel situation. Based on ample data from animal studies but only limited evidence in humans specific nutritional stimulators need to be studied more rigorously. As long as such data are missing they can be tried on an individual basis.

Nutrient-intake-level-dependent regulation of intestinal development in newborn intrauterine growth-restricted piglets via glucagon-like peptide-2

The objective of the present study was to investigate the intestinal development of newborn intrauterine growth-restricted (IUGR) piglets subjected to normal nutrient intake (NNI) or restricted nutrient intake (RNI). Newborn normal birth weight (NBW) and IUGR piglets were allotted to NNI or RNI levels for 4 weeks from day 8 postnatal. IUGR piglets receiving NNI had similar growth performance compared with that of NBW piglets. Small intestine length and villous height were greater in IUGR piglets fed the NNI than that of piglets fed the RNI. Lactase activity was increased in piglets fed the NNI compared with piglets fed the RNI. Absorptive function, represented by active glucose transport by the Ussing chamber method and messenger RNA (mRNA) expressions of two main intestinal glucose transporters, Na+-dependent glucose transporter 1 (SGLT1) and glucose transporter 2 (GLUT2), were greater in IUGR piglets fed the NNI compared with piglets fed the RNI regimen. The apoptotic process, characterized by caspase-3 activity (a sign of activated apoptotic cells) and mRNA expressions of p53 (pro-apoptotic), bcl-2-like protein 4 (Bax) (pro-apoptotic) and B-cell lymphoma-2 (Bcl-2) (anti-apoptotic), were improved in IUGR piglets fed the NNI regimen. To test the hypothesis that improvements in intestinal development of IUGR piglets fed NNI might be mediated through circulating glucagon-like peptide-2 (GLP-2), GLP-2 was injected subcutaneously to IUGR piglets fed the RNI from day 8 to day 15 postnatal. Although the intestinal development of IUGR piglets fed the RNI regimen was suppressed compared with those fed the NNI regimen, an exogenous injection of GLP-2 was able to bring intestinal development to similar levels as NNI-fed IUGR piglets. Collectively, our results demonstrate that IUGR neonates that have NNI levels could improve intestinal function via the regulation of GLP-2.

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.

Enteral feeding and its impact on the gut immune system and intestinal mucosal barrier

Enteral feeding is the preferred method of nutritional therapy. Mucosal lack of contact with nutrients leads do lymphoid tissue atrophy, immune system functional decline, and intensification in bacterial translocation. Currently, it is assumed that microbiome is one of the body organs that has a significant impact on health. The composition of microbiome is not affected by age, sex, or place of residence, although it changes rapidly after diet modification. The composition of the microbiome is determined by enterotype, which is specific for each organism. It has a significant impact on the risk of diabetes, cancer, atherosclerosis, and other diseases. This review gathers data on interaction between gut-associated lymphoid tissue, mucosa-associated lymphoid tissue, microbiome, and the intestinal mucosal barrier. Usually, the information on the aforementioned is scattered in specialist-subject magazines such as gastroenterology, microbiology, genetics, biochemistry, and others.

Animal models of gastrointestinal and liver diseases. Animal models of infant short bowel syndrome: translational relevance and challenges

Intestinal failure (IF), due to short bowel syndrome (SBS), results from surgical resection of a major portion of the intestine, leading to reduced nutrient absorption and need for parenteral nutrition (PN). The incidence is highest in infants and relates to preterm birth, necrotizing enterocolitis, atresia, gastroschisis, volvulus, and aganglionosis. Patient outcomes have improved, but there is a need to develop new therapies for SBS and to understand intestinal adaptation after different diseases, resection types, and nutritional and pharmacological interventions. Animal studies are needed to carefully evaluate the cellular mechanisms, safety, and translational relevance of new procedures. Distal intestinal resection, without a functioning colon, results in the most severe complications and adaptation may depend on the age at resection (preterm, term, young, adult). Clinically relevant therapies have recently been suggested from studies in preterm and term PN-dependent SBS piglets, with or without a functional colon. Studies in rats and mice have specifically addressed the fundamental physiological processes underlying adaptation at the cellular level, such as regulation of mucosal proliferation, apoptosis, transport, and digestive enzyme expression, and easily allow exogenous or genetic manipulation of growth factors and their receptors (e.g., glucagon-like peptide 2, growth hormone, insulin-like growth factor 1, epidermal growth factor, keratinocyte growth factor). The greater size of rats, and especially young pigs, is an advantage for testing surgical procedures and nutritional interventions (e.g., PN, milk diets, long-/short-chain lipids, pre- and probiotics). Conversely, newborn pigs (preterm or term) and weanling rats provide better insights into the developmental aspects of treatment for SBS in infants owing to their immature intestines. The review shows that a balance among practical, economical, experimental, and ethical constraints will determine the choice of SBS model for each clinical or basic research question.

Stimulation of intestinal growth and function with DPP4 inhibition in a mouse short bowel syndrome model

Glucagon-like peptide-2 (GLP-2) has been shown to be effective in patients with short bowel syndrome (SBS), but it is rapidly inactivated by dipeptidyl peptidase IV (DPP4). We used an orally active DPP4 inhibitor (DPP4-I), MK-0626, to determine the efficacy of this approach to promote adaptation after SBS, determined optimal dosing, and identified further functional actions in a mouse model of SBS. Ten-week-old mice underwent a 50% proximal small bowel resection. Dose optimization was determined over a 3-day post-small bowel resection period. The established optimal dose was given for 7, 30, and 90 days and for 7 days followed by a 23-day washout period. Adaptive response was assessed by morphology, intestinal epithelial cell (IEC) proliferation (proliferating cell nuclear antigen), epithelial barrier function (transepithelial resistance), RT-PCR for intestinal transport proteins and GLP-2 receptor, IGF type 1 receptor, and GLP-2 plasma levels. Glucose-stimulated sodium transport was assessed for intestinal absorptive function. Seven days of DPP4-I treatment facilitated an increase in GLP-2 receptor levels, intestinal growth, and IEC proliferation. Treatment led to differential effects over time, with greater absorptive function at early time points and enhanced proliferation at later time points. Interestingly, adaptation continued in the group treated for 7 days followed by a 23-day washout. DPP4-I enhanced IEC proliferative action up to 90 days postresection, but this action seemed to peak by 30 days, as did GLP-2 plasma levels. Thus DPP4-I treatment may prove to be a viable option for accelerating intestinal adaptation with SBS.

Acute effects of the glucagon-like peptide 2 analogue, teduglutide, on intestinal adaptation in short bowel syndrome

Neonatal short bowel syndrome following massive gut resection is associated with malabsorption of nutrients. The intestinotrophic factor glucagon-like peptide 2 (GLP-2) improves gut function in adult patients with short bowel syndrome, but its effect in pediatric patients remains unknown. Our objective was to test the efficacy of the long-acting synthetic human GLP-2 analogue, teduglutide (ALX-0600), in a neonatal piglet jejunostomy model. Two-day-old pigs were subjected to resection of 50% of the small intestine (distal part), and the remnant intestine was exteriorized on the abdominal wall as a jejunostomy. All pigs were given total parenteral nutrition for 7 days and a single daily injection of the following doses of teduglutide: 0.01 (n = 6), 0.02 (n = 6), 0.1 (n = 5), or 0.2 mg · kg · day (n = 6), and compared with placebo (n = 9). Body weight increment was similar for all 4 teduglutide groups but higher than placebo (P < 0.05). There was a dose-dependent increase in weight per length of the remnant intestine (P < 0.01) and fractional protein synthesis rate in the intestine was increased in the 0.2 mg · kg · day group versus placebo (P < 0.001); however, functional and structural endpoints including activity of digestive enzymes, absorption of enteral nutrients, and immunohistochemistry (Ki67, villin, FABP2, ChgA, and GLP-2R) were not affected by the treatment. Teduglutide induces trophicity on the remnant intestine but has limited acute effects on functional endpoints. Significant effects of teduglutide on gut function may require a longer adaptation period and/or a more frequent administration of the peptide. In perspective, GLP-2 or its analogues may be relevant to improve intestinal adaptation in pediatric patients with short bowel syndrome.

Glycyrrhizin represses total parenteral nutrition-associated acute liver injury in rats by suppressing endoplasmic reticulum stress

Total parenteral nutrition (TPN) is an artificial way to support daily nutritional requirements by bypassing the digestive system, but long-term TPN administration may cause severe liver dysfunction. Glycyrrhizin is an active component of licorice root that has been widely used to treat chronic hepatitis. The aim of this study is to investigate the hepatoprotective effect of glycyrrhizin on TPN-associated acute liver injury in vivo. Liver dysfunction was induced by intravenous infusion of TPN at a flow rate of 20 mL/kg/h for three h in Sprague Dawley rats. The rats were pretreated with Glycyrrhizin (1, 3 and 10 mg/kg intravenously). After receiving TPN or saline (control group) for three h, the rats were sacrificed, blood samples were collected for biochemical analyses and liver tissue was removed for histopathological and immunohistochemical examination. We found that aspartate aminotransferase (AST), alanine aminotransferase (ALT), total bilirubin (TB) and triglyceride (TG) levels were significantly increased in the TPN group without glycyrrhizin pretreatment and decreased in the glycyrrhizin-pretreated TPN group in a dose-dependent manner. The stained liver sections showed that glycyrrhizin relieved acute liver injury. The upregulation of serum protein biomarkers of reactive nitrogen species, including nitrotyrosine and inducible NO synthase (iNOS), were attenuated by glycyrrhizin pretreatment. Levels of endoplasmic reticulum (ER) stress factors, such as phosphorylation of JNK1/2, p38 MAPK and CHOP, were decreased by glycyrrhizin pretreatment. In summary, our results suggest that glycyrrhizin decreases TPN-associated acute liver injury factors by suppressing endoplasmic reticulum stress and reactive nitrogen stress.

Glucagon-like peptide 2 increases efficacy of distraction enterogenesis

BACKGROUND

Application of distractive forces to small bowel induces intestinal growth, or enterogenesis. This emerging area of research may provide treatment for short bowel syndrome. Glucagon-like peptide 2(GLP-2) has also been reported to induce small bowel growth after bowel resection. We hypothesized that exogenous GLP-2 will result in enhanced distraction-induced enterogenesis.

METHODS

Distraction-induced model was performed in 10-wk-old C57BL/6 mice using osmotic forces with high molecular weight polyethylene glycol (PEG)-stretch. Four groups were studied: Control group (PEG-/GLP-2-); PEG-stretch (PEG+/GLP-2-); GLP-2 control (PEG-/GLP-2+); and GLP-2 stretch (PEG+/GLP-2+). GLP-2 was given via subcutaneous osmotic pump over the 5 d of experiment. Morphology was measured by histomicrography. Epithelial cell (EC) proliferation was measured with proliferating cell nuclear antigen immunofluorescent staining. Total intestinal growth and blood vessel volume was assessed with Micro computed tomography volumetry. Vascular endothelial growth factor, fibroblast growth factor 1 and 2, and platelet-derived growth factor were measured by reverse-transcriptase polymerase chain reaction.

RESULTS

EC proliferation increased significantly in all groups compared with controls, but was greatest in the GLP-2 stretch group. Diameter and length significantly increased in the PEG-stretch and GLP-2 stretch groups. Moreover, there was statistically greater diameter, crypt depth and EC proliferation in the GLP-2 stretch versus PEG-stretch groups. GLP-2 stretch vessel volume was greater than all other groups and was significantly increased compared with controls. The relative expression of platelet-derived growth factor increased significantly in the PEG-stretch group versus the Control group.

CONCLUSIONS

GLP-2 had an additive effect on EC proliferation, tissue growth, histomorphology, and vascularization. We also demonstrated a unique action of GLP-2, the enhancement of intestinal vascularization. The combination of enterogenesis and GLP-2 may yield an improved approach to treat short bowel syndrome.