Glucagon-like Peptide-2 Treatment Research Articles

Associations between feeding and glucagon-like peptide-2 in healthy ponies.

Gastrointestinal peptides, such as glucagon-like peptide-2 (GLP-2), could play a direct role in the development of equine hyperinsulinaemia. To describe the secretory pattern of endogenous GLP-2 over 24 h in healthy ponies and determine whether oral administration of a synthetic GLP-2 peptide increases blood glucose or insulin responses to feeding. A cohort study followed by a randomised, controlled, cross-over study. In the cohort study, blood samples were collected every 2 h for 24 h in seven healthy ponies and plasma [GLP-2] was measured. In the cross-over study, 75 μg/kg bodyweight of synthetic GLP-2, or carrier only, was orally administered to 10 ponies twice daily for 10 days. The area under the curve (AUC0-3h ) of post-prandial blood glucose and insulin were determined before and after each treatment. Endogenous [GLP-2] ranged from <0.55 to 1.95 ± 0.29 [CI 0.27] ng/mL with similar peak concentrations in response to meals containing 88-180 g of non-structural carbohydrate, that were ~4-fold higher (P < 0.001) than the overnight nadir. After GLP-2 treatment peak plasma [GLP-2] increased from 1.1 [0.63-1.37] ng/mL to 1.54 [1.1-2.31] ng/mL (28.6%; P = 0.002), and AUC0-3h was larger (P = 0.01) than before treatment. The peptide decreased (7%; P = 0.003) peak blood glucose responses to feeding from 5.33 ± 0.45 mmol/L to 5.0 ± 0.21 mmol/L, but not AUC0-3h (P = 0.07). There was no effect on insulin secretion. The study only included healthy ponies and administration of a single dose of GLP-2. The diurnal pattern of GLP-2 secretion in ponies was similar to other species with no apparent effect of daylight. Although GLP-2 treatment did not increase post-prandial glucose or insulin responses to eating, studies using alternative dosing strategies for GLP-2 are required.

Pathophysiology of gastrointestinal acute graft-versus-host disease and the potential role of glucagon-like peptide 2.

Acute graft-versus-host disease (aGVHD) is a life-threatening complication after allogeneic haematopoietic cell transplantation, with gastrointestinal (GI) tract involvement (GI aGVHD) being one of the leading causes of morbidity and mortality. Whilst systemic steroids are the standard first-line treatment for aGVHD, approximately 50% of patients become steroid refractory (SR), which is associated with poor outcomes. Existing options for SR-GVHD are limited, and there is a significant unmet need for new non-immunosuppressive treatment approaches in patients with GI aGVHD. Here, we review newer concepts in the pathogenesis of GI aGVHD and present the evidence for the role of glucagon-like peptide 2 (GLP-2) in maintaining and protecting GI epithelial cells, including the enterocytes, intestinal stem cells and Paneth cells, which are direct targets of aGVHD. Finally, we discuss the therapeutic rationale for GLP-2 treatment as a tissue regeneration approach and the potential use of the novel GLP-2 analogue apraglutide as an adjunctive treatment for GI aGVHD.

Glucagon-Like Peptide-2 Ameliorates Age-Associated Bone Loss and Gut Barrier Dysfunction in Senescence-Accelerated Mouse Prone 6 Mice

Introduction: Senile osteoporosis is one of the most common age-related diseases worldwide. Glucagon like peptide-2 (GLP-2), a naturally occurring gastrointestinal peptide, possesses therapeutic effects on bone loss in postmenopausal women and ovariectomized rats. However, the role of GLP-2 in senile osteoporosis and underlying mechanisms has not been explored. Methods: GLP-2 was subcutaneously injected into the 6-month-old male senile osteoporosis model of senescence-accelerated mouse prone 6 (SAMP6) mice for 6 weeks. SAMP6 subjected to normal saline and senescence-accelerated mouse resistant 1 served as control groups. Micro-computed tomography was performed to evaluate the bone mass and microarchitecture of the mice. Osteoblastic and osteoclastic activities were determined by biochemical, quantitative real-time PCR, histological, and histomorphometric analyses combined with hematoxylin-eosin, toluidine blue, and tartrate-resistant acid phosphatase staining. We also examined the proteins and structure of intestinal tight junction using immunohistochemical assay as well as a transmission electron microscope. Serum inflammation marker levels were measured using ELISA. Additionally, anti-oxidative enzymes GPX-4 and SOD-2 and receptors of GLP-2 and vitamin D expression in the ileum and colon were detected under immunofluorescence staining. Results: Six-week GLP-2 treatment attenuated bone loss in SAMP6 mice, as evidenced by increased bone mineral density, improved microarchitecture in femora, and enhanced osteogenic activities. In contrast, the activity of osteoclastic activity was not obviously inhibited. Moreover, GLP-2 ameliorated tight junction structure and protein expression in the intestinal barrier, which was accompanied by the reduction of TNF-α level. The expression of receptors of intestinal GLP-2 and vitamin D in the ileum was elevated. Furthermore, the oxidative stress in the intestines was improved by increasing the GPX-4 and SOD-2 signaling. Conclusion: Our findings suggest that GLP-2 could ameliorate age-associated bone loss, tight junction structure, and improved antioxidant enzyme activity in the gut in SAMP6 mice. Amelioration of gut barrier dysfunction may potentially contribute to improving bone formation and provide evidence for targeting the entero-bone axis in the treatment of senile osteoporosis.

Short- versus long-term, gender and species differences in the intestinotrophic effects of long-acting glucagon-like peptide 2 analog.

Glucagon-like-peptide 2 (GLP-2) is an endogenous enteroendocrine physiological trophic peptide. Glepaglutide is a novel long-acting GLP-2 analog under development for the treatment of patients with Short Bowel Syndrome (SBS). The objective of this work was to compare the small intestinal trophic effects in both genders following short (1 week) versus long-term (26-39 weeks) GLP-2 treatment in Wistar rats and Beagle dogs. Following both short- and long-term treatment with glepaglutide, a significant dose-dependent intestinotrophic effect was seen in both genders and species. At all doses increased length and weight of the small intestine as well as macroscopic thickening and villous hypertrophy were noted in all segments of the small intestine, without any differences between genders. The findings were still present following a 6-week recovery period, indicating long-acting intestinotrophic effects of glepaglutide. These studies demonstrate that a long-acting GLP-2 analogue (glepaglutide) has a fast onset and long duration of intestinotrophic action with similar profile in both genders and species (rat and dog).

GLP-2 Regulation of Dietary Fat Absorption and Intestinal Chylomicron Production via Neuronal Nitric Oxide Synthase (nNOS) Signaling.

Postprandial dyslipidemia is a metabolic condition commonly associated with insulin-resistant states, such as obesity and type 2 diabetes. It is characterized by the overproduction of intestinal chylomicron particles and excess atherogenic chylomicron remnants in circulation. We have previously shown that glucagon-like peptide 2 (GLP-2) augments dietary fat uptake and chylomicron production in insulin-resistant states; however, the underlying mechanisms remain unclear. Previous studies have implicated nitric oxide (NO) in the absorptive actions of GLP-2. In this study, we report a novel role for neuronal NO synthase (nNOS)-mediated NO generation in lipid uptake and chylomicron formation based on studies in C57BL/6J mice, nNOS-/- mice, and Syrian golden hamsters after intraduodenal and oral fat administration. GLP-2 treatment in wild-type (WT) mice significantly increased postprandial lipid accumulation and circulating apolipoprotein B48 protein levels, while these effects were abolished in nNOS-/- mice. nNOS inhibition in Syrian golden hamsters and protein kinase G (PKG) inhibition in WT mice also abrogated the effect of GLP-2 on postprandial lipid accumulation. These studies demonstrate a novel mechanism in which nNOS-generated NO is crucial for GLP-2-mediated lipid absorption and chylomicron production in both mouse and hamster models. Overall, our data implicate an nNOS-PKG-mediated pathway in GLP-2-mediated stimulation of dietary fat absorption and intestinal chylomicron production.

Therapeutic potential of an intestinotrophic hormone, glucagon-like peptide 2, for treatment of type 2 short bowel syndrome rats with intestinal bacterial and fungal dysbiosis

BackgroundPrevious studies showed that type 2 short bowel syndrome (SBS) rats were accompanied by severe intestinal bacterial dysbiosis. Limited data are available for intestinal fungal dysbiosis. Moreover, no effective therapeutic drugs are available for these microbiota dysbiosis. The aims of our study were to investigate the therapeutic potential of glucagon-like peptide 2 (GLP-2) for these microbiota dysbiosis in type 2 SBS rats.Methods8-week-old male SD rats which underwent 80% small bowel resection, ileocecum resection, partial colon resection and jejunocolostomy, were treated with saline (SBS group, n = 5) or GLP-2 (GLP2.SBS group, n = 5). The Sham group rats which underwent transection and re-anastomosis were given a saline placebo (Sham group, n = 5). 16S rRNA and ITS sequencing were applied to evaluate the colonic bacterial and fungal composition at 22 days after surgery, respectively.ResultsThe relative abundance of Actinobacteria, Firmicutes and proinflammatory Proteobacteria increased significantly in SBS group rats, while the relative abundance of Bacteroidetes, Verrucomicrobia and Tenericutes decreased remarkably. GLP-2 treatment significantly decreased Proteus and increased Clostridium relative to the saline treated SBS rats. The diversity of intestinal fungi was significantly increased in SBS rats, accompanied with some fungi abnormally increased and some resident fungi (e.g., Penicillium) significantly decreased. GLP-2 treatment significantly decreased Debaryomyces and Meyerozyma, and increased Penicillium. Moreover, GLP-2 partially restored the bacteria-fungi interkingdom interaction network of SBS rats.ConclusionOur study confirms the bacterial and fungal dysbiosis in type 2 SBS rats, and GLP-2 partially ameliorated these microbiota dysbiosis.

Neuroprotective Effects of a GLP-2 Analogue in the MPTP Parkinson's Disease Mouse Model.

Glucagon-like peptide 2 (GLP-2) is a peptide hormone derived from the proglucagon gene expressed in the intestines, pancreas and brain. Some previous studies showed that GLP-2 improved aging and Alzheimer's disease related memory impairments. Parkinson's disease (PD) is a progressive neurodegenerative disorder, and to date, there is no particular medicine reversed PD symptoms effectively. The aim of this study was to evaluate neuroprotective effects of a GLP-2 analogue in the 1-Methyl-4-phenyl-1, 2, 3, 6-tetrahydropyridine (MPTP) PD mouse model. In the present study, the protease resistant Gly(2)-GLP-2 (50 nmol/kg ip.) analogue has been tested for 14 days by behavioral assessment, transmission electron microscope, immunofluorescence histochemistry, enzyme-linked immunosorbent assay and western blot in an acute PD mouse model induced by MPTP. For comparison, the incretin receptor dual agonist DA5-CH was tested in a separate group. The GLP-2 analogue treatment improved the locomotor and exploratory activity of mice, and improved bradykinesia and movement imbalance of mice. Gly(2)-GLP-2 treatment also protected dopaminergic neurons and restored tyrosine hydroxylase expression levels in the substantia nigra. Gly(2)-GLP-2 furthermore reduced the inflammation response as seen in lower microglia activation, and decreased NLRP3 and interleukin-1β pro-inflammatory cytokine expression levels. In addition, the GLP-2 analogue improved MPTP-induced mitochondrial dysfunction in the substantia nigra. The protective effects were comparable to those of the dual agonist DA5-CH. The present results demonstrate that Gly(2)-GLP-2 can attenuate NLRP3 inflammasome-mediated inflammation and mitochondrial damage in the substantia nigra induced by MPTP, and Gly(2)-GLP-2 shows neuroprotective effects in this PD animal model.

Glucagon-like Peptide-2 (GLP-2) Treatment Reduces Gvhd-Related Mortality in a Pre-Clinical Transplant Model Via Expansion of Macrophages with Tolerogenic Potential

The gastrointestinal (GI) tract is a major target in GVHD. Conditioning-induced damage and mucosal barrier disruption are important factors in GVHD, however therapies targeting these processes have not been identified. Glucagon-like-peptide 2 (GLP-2) is an enterocyte-specific growth factor produced by L cells that has regenerative potential in models of GI damage. Its impact on the mucosal immune system has not been elucidated. We sought to examine the therapeutic and immunologic effect of GLP-2 in murine GVHD. We employed a major MHC-mismatched GVHD model (C57BL/6J → BALB/cJ). Mice were treated with 800nmol/kg/day of Elsiglutide (a GLP-2 analogue, provided by Helsinn) or vehicle beginning on D+1 for 30 days. Treatment with GLP-2 significantly improved survival and GVHD scores (Fig. 1A), while increasing small intestine mass and villi length (Fig 1B). GLP-2 also reduced T-cell infiltration into the jejunum (Fig. 1C). Analysis of intestinal immune cells by 28-color flow cytometry revealed dramatic differences between treatment groups in both myeloid- and T-cells. On D+14, GLP-2 led to an increased proportion of donor CSF-1R+ macrophages in the lamina propria (LP) (Fig. 2A) - cells that support the maintenance of the intestinal stem cell niche (Sehgal, Nat Commun, 2018). On D+21 the LP donor myeloid compartment was further altered, especially in MHC IIlow F4/80+ CD64+ macrophages (Fig. 2B, C). Here GLP-2 treatment expanded macrophages with lower expression of the co-stimulatory molecules CD80 and CD86 as well as the phagocytic marker CD206, whilst increasing the inhibitory molecule SIRPα, consistent with a tolerogenic phenotype. GLP-2 treatment also increased CX3CR1 expression on MHC IIlow macrophages with reduced Ly6C - a phenotype associated with physiologic macrophage maturation and linked to the resolution of colitis (Zigmond, Immunity, 2012). Vehicle-treated mice, conversely, had predominance of Ly6Chigh MHC IIlow LP macrophages reminiscent of an early infiltrating phenotype and near absence of mature macrophages, suggesting an impaired monocyte-macrophage transition that was restored by GLP-2. In addition, GLP-2 treatment led to significant changes in donor intraepithelial lymphocytes on D+21 (Fig. 2D), where CD8 T cells exhibited decreased CD27, CD103 and CXCR3 expression but higher PD-1, suggesting less activation. To assess potential mechanisms for the differences in macrophage and T-cell phenotype, we examined the impact of GLP-2 on the intestinal microbiota. A syngeneic BALB/cJ model was used to explore the effects of GLP-2 independent of GVHD. Stool samples from D+0, D+14, and D+28 were subjected to 16S rRNA sequencing. Vehicle-treated mice had distinct β-diversity clusters at all time-points, showing a transplant effect on the microbiota (Fig. 3A). GLP-2-treated mice had near-complete cluster overlap between D+0 and D+14, suggesting attenuation of the impact of conditioning. GLP-2 treated mice were significantly enriched for Akkermansia muciniphila and Bacteroidales S24-7 family at D+14 and D+28 (Fig. 3B). These taxa have been associated with anti-inflammatory properties and A. muciniphila abundance is linked to epithelial mucin production, which is increased by GLP-2. We then assessed the role of microbial communities in the protective effect of GLP-2 by conducting an allogeneic transplant with 3 caging conditions; 1) vehicle and GLP-2 treated mice caged together, 2) caged separately, or 3) caged separately plus oral antibiotics. We observed a clear cage effect where co-housing the treatment groups improved the survival of vehicle treated mice (Fig. 3C), suggesting transferal of the therapeutic effect via the microbiome. Antibiotic administration also dampened the beneficial effect of GLP-2. Finally, we conducted a GvL experiment by co-transplanting Luc-A20 and monitoring tumor progression via bioluminescence imaging. Both GLP-2 and vehicle-treated mice eliminated the tumor, whereas mice receiving T-cell depleted bone marrow showed tumor progression (Fig. 3D). In summary, our results demonstrate high therapeutic potential of GLP-2 in GVHD. GLP-2 administration led to reduced mortality, modified the microbiome and altered the intestinal immune response to a more tolerogenic state. This novel mechanism sheds light on the role of the enteroendocrine system in maintaining gut homeostasis and sets the stage for therapeutic clinical trials. Figure 1 Disclosures Uhlemann: Allergan: Research Funding; GSK: Research Funding; Merck: Research Funding. Reshef:Gilead: Consultancy; Magenta: Consultancy; Novartis: Consultancy; Monsato: Consultancy; Atara: Consultancy; BMS: Consultancy.

Glucagon-like peptide 2 attenuates intestinal mucosal barrier injury through the MLCK/pMLC signaling pathway in a piglet model.

Glucagon-like peptide-2 (GLP-2), an intestinotrophic hormone, has drawn considerable attention worldwide due to its potential to promote intestinal development. We investigated the effects and mechanisms of GLP-2 against lipopolysaccharide (LPS)-induced intestinal inflammation and injury both in vitro and in vivo. Forty healthy piglets weaned at the age of 28 days with similar body weight (BW) were assigned to four in vivo treatments with ten piglets each: (i) nonchallenged control; (ii) LPS-challenged control; (iii) LPS + low dose GLP-2; and (iv) LPS + high dose GLP-2. Piglets were subcutaneously injected with phosphate-buffered saline supplemented with GLP-2 at doses of 0, 0, 2, and 10 nmol/kg BW per day for seven consecutive days. The piglets were challenged with an intraperitoneal injection with 100 μg/kg LPS on day 14 to induce intestinal damage. After that, the gene and protein expression levels of representative tight junction proteins and myosin light-chain kinase (MLCK)/phosphorylated myosin light chain (pMLC), as well as proinflammatory cytokine levels were determined using quantitative reverse transcription polymerase chain reaction, western blot, and enzyme-linked immunosorbent assay methods. A high dose of GLP-2 pretreatment increased intestinal permeability by downregulating and redistributing tight junction proteins (p < .05), for example, zona occluden-1 (ZO-1) and occludin. GLP-2 decreased the transcription of proinflammatory cytokines genes including interleukin-1β (IL-1β), IL-6, IL-8, and tumor necrosis factor-α in small intestines (p < .05). GLP-2 prevented the LPS-induced increase in the expression of MLCK dose-dependently and the increase in pMLC levels in the duodenum, jejunum, and ileum. To assess further the protective effect of GLP-2 on LPS-induced intestinal barrier injury after weaning and its possible mechanism, an in vitro intestinal epithelial barrier model was established with IPEC-J2 monolayers and treated with 100 μg/ml LPS with or without 1 × 10-8 mol/L GLP-2 pretreatment. The in vitro analysis included control, LPS, and GLP-2 + LPS treatments. GLP-2 treatment alleviated the destructive effect of LPS on barrier permeability by restoring the expression and ultrastructure of ZO-1 and occludin (p < .05). In addition, GLP-2 reversed the LPS-induced MLCK hyperexpression and pMLC hyperphosphorylation (p < .05). Taken together, our findings revealed a mechanism by which GLP-2 alleviated LPS-challenged intestinal barrier injury and inflammation in weaned piglets and IPEC-J2 cells via the MLCK/pMLC signaling pathway.

GLP-2 Acutely Prevents Endotoxin-Related Increased Intestinal Paracellular Permeability in Rats.

Circulating endotoxin (lipopolysaccharide, LPS) increases the gut paracellular permeability. We hypothesized that glucagon-like peptide-2 (GLP-2) acutely reduces LPS-related increased intestinal paracellular permeability by a mechanism unrelated to its intestinotrophic effect. We assessed small intestinal paracellular permeability in vivo by measuring the appearance of intraduodenally perfused FITC-dextran 4000 (FD4) into the portal vein (PV) in rats 1-24h after LPS treatment (5mg/kg, ip). We also examined the effect of a stable GLP-2 analog teduglutide (TDG) on FD4 permeability. FD4 movement into the PV was increased 6h, but not 1 or 3h after LPS treatment, with increased PV GLP-2 levels and increased mRNA expressions of proinflammatory cytokines and proglucagon in the ileal mucosa. Co-treatment with a GLP-2 receptor antagonist enhanced PV FD4 concentrations. PV FD4 concentrations 24h after LPS were higher than FD4 concentrations 6h after LPS, reduced by exogenous GLP-2 treatment given 6 or 12h after LPS treatment. FD4 uptake measured 6h after LPS was reduced by TDG 3 or 6h after LPS treatment. TDG-associated reduced FD4 uptake was reversed by the VPAC1 antagonist PG97-269 or L-NAME, not by EGF or IGF1 receptor inhibitors. Systemic LPS releases endogenous GLP-2, reducing LPS-related increased permeability. The therapeutic window of exogenous GLP-2 administration is at minimum within 6-12h after LPS treatment. Exogenous GLP-2 treatment is of value in the prevention of increased paracellular permeability associated with endotoxemia.

Exosomes-mediated Transfer of miR-125a/b in Cell-to-cell Communication: A Novel Mechanism of Genetic Exchange in the Intestinal Microenvironment.

Glucagon-like peptide-2 (GLP-2), a key factor in intestinal rehabilitation therapy of short bowel syndrome (SBS), may require cell-to-cell communication to exert its biological functions. However, understanding of the mechanism remains elusive. Here, we report participation of exosomal miR-125a/b in GLP-2 mediated intestinal epithelial cells-myofibroblasts cross-talk in intestinal microenvironment.Methods: The effects of GLP-2 on the proliferation and apoptosis of intestinal epithelial cells in SBS rat models were evaluated. Exosomes were extracted from residual jejunum tissue of GLP-2 or vehicle treated SBS rats using ultracentrifugation method, and identified by nanoparticle trafficking analysis (NTA), transmission electron microscopy and western blotting. miRNA sequencing combined with qRT-PCR validation were used to identify differentially expressed miRNAs. miRNAs, which might be involved in proliferation and apoptosis of intestinal epithelial cells, were screened and further verified by miRNA functional experiments. Moreover, the proliferation-promoting and anti-apoptosis effects of GLP-2 on intestinal myofibroblasts, which expressing GLP-2 receptor, and whether GLP-2 could influence the content of miRNAs in the derived exosomes were studied. The downstream pathways were explored by miRNA function recovery experiment, luciferase reporter assay, pull down experiment, knockdown and overexpression of target gene and other experiments based on the bioinformatics prediction of miRNA target gene.Results: GLP-2 significantly promoted intestinal growth, facilitated the proliferation of intestinal crypt epithelial cells and inhibited the apoptosis of intestinal villi epithelial cells in type II SBS rats. GLP-2 significantly down-regulated exosomal miR-125a/b both in residual jejunums derived exosomes and in exosomes secreted by GLP-2R positive cells. Exosomal miR-125a/b was responsible for GLP-2 mediated intestinal epithelial cells proliferation promotion and apoptosis attenuation. miR-125a/b inhibited the proliferation and promotes apoptosis of intestinal epithelial cells by suppressing the myeloid cell leukemia-1 (MCL1).Conclusions: miR-125a/b shuttled by intestinal myofibroblasts derived exosomes regulate the proliferation and apoptosis of intestinal epithelial cells. GLP-2 treatment significantly decreases the level of miR-125a/b in the exosomes of intestinal myofibroblasts. miR-125a/b modulates the proliferation and apoptosis of intestinal epithelial cells by targeting the 3'UTR region of MCL1. Hence, this study indicates a novel mechanism of genetic exchange between cells in intestinal microenvironment.

Glucagon-like peptide-2 rescues memory impairments and neuropathological changes in a mouse model of dementia induced by the intracerebroventricular administration of streptozotocin

Glucagon-like peptide 2 (GLP-2) is derived from the proglucagon gene expressed in the intestines, pancreas and brain. Our previous study showed that GLP-2 improved lipopolysaccharide-induced memory impairments. The current study was designed to further investigated the potential of GLP-2 in memory impairment induced by intracerebroventricular administration of streptozotocin (ICV-STZ) in mice, which have been used as an animal model of sporadic Alzheimer’s disease (AD). STZ was administered on alternate days (Day-1 and Day-3) in order to induce dementia in male ddY mice. ICV-STZ-treated mice were administered GLP-2 (0.6 μg/mouse, ICV) for 5 days from 14 days after the first ICV administration of STZ. In these mice, we examined spatial working memory, the biochemical parameters of oxidative stress, or neurogenesis. The GLP-2 treatment restored spatial working memory in ICV-STZ-treated mice. ICV-STZ-treated mice showed markedly increased thiobarbituric acid reactive species (TBARS) and decreased glutathione (GSH) levels, and GLP-2 significantly restored these ICV-STZ-induced changes. GLP-2 also significantly restored neurogenesis in the subgranular zone of the dentate gyrus in ICV-STZ-treated mice. We herein demonstrated that GLP-2 significantly restored ICV-STZ-induced memory impairments as well as biochemical and histopathological alterations, and accordingly, propose that the memory restorative ability of GLP-2 is due to its potential to reduce oxidative stress.

The roles of glucagon-like peptide-2 and the intestinal epithelial insulin-like growth factor-1 receptor in regulating microvillus length

Microvilli are tiny projections on the apical end of enterocytes, aiding in the digestion and absorption of nutrients. One of their key features is uniform length, but how this is regulated is poorly understood. Glucagon-like peptide-2 (GLP-2) has been shown to increase microvillus length but, the requirement of its downstream mediator, the intestinal epithelial insulin-like growth factor-1 receptor (IE-IGF-1R), and the microvillus proteins acted upon by GLP-2, remain unknown. Using IE-IGF-1R knockout (KO) mice, treated with either long-acting human (h) (GLY2)GLP-2 or vehicle for 11d, it was found that the h(GLY2)GLP-2-induced increase in microvillus length required the IE-IGF-1R. Furthermore, IE-IGF-1R KO alone resulted in a significant decrease in microvillus length. Examination of the brush border membrane proteome as well as of whole jejunal mucosa demonstrated that villin was increased with h(GLY2)GLP-2 treatment in an IE-IGF-1R-dependent manner. Under both basal conditions and with h(GLY2)GLP-2 treatment of the IE-IGF-1R KO mice, changes in villin, IRTKS-1, harmonin, β-actin, and myosin-1a did not explain the decrease in microvillus length, in either the brush border or jejunal mucosa of KO animals. Collectively, these studies define a new role for the IE-IGF-1R within the microvillus, in both the signaling cascade induced by GLP-2, as well as endogenously.

Aspartame supplementation in starter accelerates small intestinal epithelial cell cycle and stimulates secretion of glucagon-like peptide-2 in pre-weaned lambs.

The objective of this study was to test the hypothesis that aspartame supplementation in starter diet accelerates small intestinal cell cycle by stimulating secretion and expression of glucagon-like peptide -2 (GLP-2) in pre-weaned lambs using animal and cell culture experiments. In vivo, twelve 14-day-old lambs were selected and allocated randomly to two groups; one was treated with plain starter diet (Con, n=6) and the other was treated with starter supplemented with 200mg of aspartame/kg starter (APM, n=6). Results showed that the lambs received APM treatment for 35 d had higher (p<.05) GLP-2 concentration in the plasma and greater jejunum weight/live body weight (BW) and jejunal crypt depth. Furthermore, APM treatment significantly upregulated (p<.05) the mRNA expression of cyclin D1 in duodenum; and cyclin A2, cyclin D1, cyclin-dependent kinases 6 (CDK6) in jejunum; and cyclin A2, cyclin D1, CDK4 in ileum. Moreover, APM treatment increased (p<.05) the mRNA expression of glucagon (GCG), insulin-like growth factor 1 (IGF-1) in the jejunum and ileum and mRNA expression of GLP-2 receptor (GLP-2R) in the jejunum. In vitro, when jejunal cells were treated with GLP-2 for 2hr, the 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide (MTT) OD, IGF-1 concentration, and the mRNA expression of IGF-1, cyclin D1 and CDK6 were increased (p<.05). Furthermore, IGF-1 receptor (IGF-1R) inhibitor decreased (p<.05) the mRNA expression of IGF-1, cyclin A2, cyclin D1 and CDK6 in GLP-2 treatment jejunal cells. These results suggest that aspartame supplementation in starter accelerates small intestinal cell cycle that may, in part, be related to stimulate secretion and expression of GLP-2 in pre-weaning lambs. Furthermore, GLP-2 can indirectly promote the proliferation of jejunal cells mainly through the IGF-1 pathway. These findings provide new insights into nutritional interventions that promote the development of small intestines in young ruminants.

Glucose and GLP-2 (Glucagon-Like Peptide-2) Mobilize Intestinal Triglyceride by Distinct Mechanisms.

Dietary triglycerides are partially retained in the intestine within intracellular or extracellular compartments, which can be rapidly mobilized in response to several stimuli, including glucose and GLP-2 (glucagon-like peptide-2). To elucidate the mechanism of intestinal lipid mobilization, this study examined the patterns and time course of lymph flow and triglycerides after glucose and GLP-2 treatment in rats. Approach and Results: Lymph flow, triglyceride concentration, and triglyceride output were assessed in mesenteric lymph duct-cannulated rats in response to an intraduodenal (i.d.) lipid bolus followed 5 hours later by either (1) i.d. saline+intraperitoneal (i.p.) saline (placebo), (2) i.d. glucose plus i.p. saline, (3) i.d. saline+i.p. GLP-2, or (4) i.d. glucose+i.p. GLP-2. GLP-2 and glucose administered alone or in combination stimulated total triglyceride output to a similar extent, but the timing and pattern of stimulation differed markedly. Whereas GLP-2 rapidly increased lymph flow with no effect on lymph triglyceride concentration or triglyceride:apoB48 (apolipoprotein B48) ratio (a surrogate marker of chylomicron size) compared with placebo, glucose transiently decreased lymph flow followed by delayed stimulation of lymph flow and increased lymph triglyceride concentration and triglyceride:apoB48 ratio. Glucose and GLP-2 robustly enhanced intestinal triglyceride output in rats but with different effects on lymph flow, lymph triglyceride concentration, and chylomicron size. GLP-2 stimulated triglyceride output primarily by enhancing lymph flow with no effect on chylomicron size, whereas glucose mobilized intestinal triglycerides, stimulating secretion of larger chylomicrons. This suggests that these 2 stimuli mobilize intestinal lipid by different mechanisms.

Glucagon-like peptide-2 reduces the obesity-associated inflammation in the brain

Growing evidence suggests a link between obesity and neurodegeneration. The purpose of the present study was to explore the neuroprotective potential of glucagon-like peptide-2 (GLP-2) in the brain of high fat diet (HFD)-fed mice. Markers of inflammation and oxidative stress were analysed in the brains of obese mice chronically treated with [Gly2]-GLP-2 (teduglutide), the stable analogue of the GLP-2, and they were compared to age-matched untreated obese and lean animals. Neurodegeneration was examined by TUNEL assay. HFD feeding increased the expression of pro-inflammatory mediators (NF-kB, IL-8, TNF-α, IL-1β and IL-6), glial fibrillary acidic protein (GFAP), index of gliosis and neurodegeneration, stress marker proteins (p-ERK, Hsp60 and i-NOS), amyloid-β precursor protein (APP). [Gly2]-GLP-2 treatment significantly attenuated the HFD-induced increased expression of the various markers, as well as the higher levels of reactive oxygen species found in brains of untreated-HFD mice. Immunofluorescence confirmed that the increase of GFAP or APP in the brain cortex of HFD mice were less prominent in the [Gly2]-GLP-2 treated group. TUNEL-positive cell number in brain sections of [Gly2]-GLP-2-treated HFD-fed mice was significantly lesser in comparison with untreated-HFD animals and similar to STD fed mice. In conclusion, the results of the present study suggest that GLP-2 stable analogue improves the obesity-associated neuroinflammation and the central stress conditions, it reduces the neuronal apoptotic death, providing evidence for a neuroprotective role of the peptide.

The Intestinotrophic Effects of Glucagon-Like Peptide-2 in Relation to Intestinal Neoplasia.

Glucagon-like peptide-2 (GLP-2) is a gastrointestinal hormone with intestinotrophic and antiapoptotic effects. The hormone's therapeutic potential in intestinal diseases and relation to intestinal neoplasia has raised great interest among researchers. This article reviews and discusses published experimental and clinical studies concerning the growth-stimulating and antiapoptotic effects of GLP-2 in relation to intestinal neoplasia. The data used in this narrative review were collected through literature research in PubMed using English keywords. All studies to date examining GLP-2's relation to intestinal neoplasms have been reviewed in this article, as the studies on the matter are sparse. GLP-2 has been found to stimulate intestinal growth through secondary mediators and through the involvement of Akt phosphorylation. Studies on rodents have shown that exogenously administered GLP-2 increases the growth and incidence of adenomas in the colon, suggesting that GLP-2 may play an important role in the progression of intestinal tumors. Clinical studies have found that exogenous GLP-2 treatment is well tolerated for up to 30 months, but the tolerability for even longer periods of treatment has not been examined. Exogenous GLP-2 is currently available as teduglutide for the treatment of short bowel syndrome. However, the association between exogenous GLP-2 treatment and intestinal neoplasia in humans has not been fully identified. This leads to a cause for concern regarding the later risk of the development or progression of intestinal tumors with long-term GLP-2 treatment. Therefore, further research regarding GLP-2's potential relation to intestinal cancers is needed.

Effect of Aging and Glucagon-like Peptide 2 on Intestinal Microbiota in SD Rats.

Recent research suggests that intestinal microbiota affect the aging process. Glucagon-like peptide 2 (GLP-2), a growth factor found in the intestinal mucosal epithelium, reduces intestinal permeability and affects intestinal microbiota. The relationship between aging, GLP-2, and intestinal microbiota are still not well understood. The current study examined the influence of aging and GLP-2 on the intestinal microbiota of rats. Twelve 3-month old male SD rats were randomly divided into two groups: a young control group (group C) and a young GLP-2 treatment group (group G). Twelve 26-month old male SD rats were randomly divided into two groups: an aged control group (group L) and an aged GLP-2 treatment group (group T). GLP-2 was intraperitoneally injected into rats from group G and group T for 14 days. Plasma GLP-2 concentration was evaluated by ELISA tests. Fresh intestinal stool samples were collected from each group and total fecal bacterial genomic DNA was extracted from the associated rats. The bacterial composition of fecal samples was analyzed by Miseq high-throughput sequencing and comparison with SRA databases. Overall, the diversity of intestinal microbiota significantly decreases with age in SD rats, while GLP-2 has no significant effect on the diversity of intestinal microbiota. Upon aging, there is a reduction in probiotic bacteria and a concomitant increase in pathogenic bacteria in rats. Treatment with GLP-2 results in a significant reduction in the prevalence of pathogenic bacterial genera and an increase in some potential benefit bacteria in aged rats. In addition, treatment with GLP-2 results in an increase in several probiotics and a reduction in the prevalence of pathogenic bacterial genera in young rats.

Glucagon-like peptide-2 improves intestinal immune function and diminishes bacterial translocation in a mouse model of parenteral nutrition

Parenteral nutrition (PN) is associated with increased infectious risks due to impaired intestinal immunity. Although glucagon-like peptide-2 (GLP-2) enhances the gut barrier function, it is uncertain whether it improves mucosal immunologic barrier function. We hypothesized that injecting the PN mouse model with GLP-2 improved innate and acquired immunity, and prevented bacterial translocation. Forty-eight hours after venous cannulation, male Institute of Cancer Research mice were randomly divided into 3 groups based on their diet: chow with saline (n = 10), PN (n = 9), or PN + GLP-2 (30 μg bid per mouse, n = 10) provided for 5 days. Compared with chow, PN reduced interleukin (IL)-4 and IL-13 levels (P < .05, respectively), whereas, compared with PN alone, GLP-2 injection increased IL-4 and IL-13 levels (P < .05, respectively). Compared with chow, PN considerably suppressed, whereas GLP-2 improved, secretory phospholipase A2 and cryptdin-4 expression. PN, compared with chow, considerably decreased lysozyme and polymeric immunoglobulin receptor levels, whereas, compared with PN, GLP-2 significantly increased these protein levels (P < .01, respectively). In tissue and luminal samples, compared with chow, PN reduced secretory immunoglobulin A levels (P < .05), whereas, compared with PN alone, GLP-2 increased secretory immunoglobulin A levels (P < .05). Functionally, more bacterial translocation was observed in the PN group compared with the chow group (P < .001), and GLP-2 injection decreased bacterial translocation to chow levels (P < .05). In summary, GLP-2 treatment may improve intestinal innate and acquired immunity, and prevent bacterial translocation in mice on total parenteral nutrition.

Reducing gut effects from Cryptosporidium parvum infection in dairy calves through prophylactic glucagon-like peptide 2 therapy or feeding of an artificial sweetener

Glucagon-like peptide 2 (GLP-2) therapy was shown previously to reduce inflammation-related gut damage from coccidiosis in dairy calves, and feeding of artificial sweetener stimulates GLP-2 secretion from intestinal L cells. The purpose of this study was to determine whether GLP-2 treatment or artificial sweetener feeding beginning 1 wk before an experimental inoculation with the coccidian parasite Cryptosporidium parvum can reduce infection-related intestinal damage in Holstein bull calves. Newborn calves were assigned to 1 of 4 treatment groups of 6 calves each, including noninfected control calves injected s.c. every 12 h with control buffer (CON), infected control calves injected s.c. every 12 h with control buffer (INF), infected calves injected s.c. every 12 h with 50 µg/kg of body weight of GLP-2 (GLP2), and infected calves injected s.c. every 12 h with control buffer and supplemented in the diet with Sucram (Pancosma, Geneva, Switzerland) at 400 mg/kg of dry matter of milk replacer (SUC). Treatments were initiated on d 1, and calves in INF, GLP2, and SUC were orally dosed on d 8 with 12,500 C. parvum oocysts. Fecal scores were recorded daily, plasma was collected on d 1, 8, 12, 15, and 18 to evaluate markers of inflammation, and fecal samples were collected on d 1, 8, and every other day thereafter to determine the presence of oocysts. Calves were euthanized on d 18 for collection of intestinal tissues and histological and gene expression analyses. Relative to CON, calves in INF exhibited an increase in diarrhea severity, increased plasma serum amyloid A concentration on d 15 and 18, reduced intestinal villus height, increased villus apoptosis and crypt cell proliferation, and increased intestinal mRNA expression of MARVELD2 and GPX2. However, calves in SUC and GLP2 had reduced diarrhea severity and fecal C. parvum oocyst shedding, reduced plasma serum amyloid A concentration on d 15 and 18, and, depending on the intestinal segment, increased villus height, reduced crypt cell proliferation, and reduced mRNA expression of MARVELD2, GPX2, and other tight junction proteins relative to INF. Lastly, GLP2 and SUC exhibited increased intestinal mass-to-length ratio and decreased length-to-empty body weight ratio relative to INF. Our findings suggest that GLP-2 and Sucram treatments administered before a low-level C. parvum exposure may contribute to fewer effects on intestinal integrity, morphology, and inflammation in response to infection, and shorter, denser intestines.