Release of Lipids Stored in the Intestine by Glucagon-Like Peptide-2 Involves a Gut-Brain Neural Pathway.

BACKGROUND: The gut hormone GLP-2 (glucagon-like peptide-2) plays important roles in lipid handling in the intestine. During postabsorptive stage, it releases preformed chylomicrons stored in the intestine, the underlying mechanisms of which are not well understood. Previous studies implicate the involvement of neural pathways in GLP-2's actions on lipid absorption in the intestine, but the role of such mechanisms in releasing postabsorptive lipid storage has not been established. METHODS: Here, in mesenteric lymph duct cannulated rats, we directly tested whether gut-brain neural communication mediates GLP-2's effects on postabsorptive lipid mobilization in the intestine. We performed total subdiaphragmatic vagotomy to disrupt the gut-brain neural communication and analyzed lipid output 5 hours after a lipid load in response to intraperitoneal GLP-2 or saline. RESULTS: Peripheral GLP-2 administration led to increased lymph lipid output and activation of proopiomelanocortin neurons in the arcuate nucleus of hypothalamus. Disruption of gut-brain neural communication via vagotomy blunted GLP-2's effects on promoting lipid release in the intestine. CONCLUSIONS: These results, for the first time, demonstrate a novel mechanism in which postabsorptive mobilization of intestinal lipid storage by GLP-2 enlists a gut-brain neural pathway.

Glucagon-Like Peptide-1 Is Involved in the Thermic Effects of Dietary Proteins in Male Rodents.

Protein intake potently increases body temperature and energy expenditure, but the underlying mechanism thereof remains incompletely understood. Simultaneously, protein intake potently stimulates glucagon-like peptide-1 (GLP-1) secretion. Here, we examined the involvement of GLP-1 in the thermic effects of dietary proteins in rodents by measuring rectal temperature and energy expenditure and modulating GLP-1 signaling. Rectal temperature of rats or mice fasted for 4 or 5 hours were measured using a thermocouple thermometer before and after an oral administration of nutrients. Oxygen consumption after oral protein administration was also measured in rats. Rectal temperature measurements in rats confirmed an increase in core body temperature after refeeding, and the thermic effect of the oral administration of protein was greater than that of a representative carbohydrate or lipid. Among the five dietary proteins examined (casein, whey, rice, egg, and soy), soy protein had the highest thermic effect. The thermic effect of soy protein was also demonstrated by increased oxygen consumption. Studies using a nonselective ß-adrenergic receptor antagonist and thermal camera suggested that brown adipose tissue did not contribute to soy protein-induced increase in rectal temperature. Furthermore, the thermic effect of soy protein was completely abolished by antagonism and knockout of the GLP-1 receptor, yet potentiated via augmentation of intact GLP-1 levels through inhibition of dipeptidyl peptidase-4 activity. These results indicate that GLP-1 signaling is essential for the thermic effects of dietary proteins in rats and mice, and extend the metabolic actions of GLP-1 ensuing from nutrient ingestion to encompass the thermic response to ingested protein.

Treatment of short bowel syndrome: Breaking the therapeutic ceiling?

Short bowel syndrome (SBS) is the most common cause of chronic intestinal failure, requiring home parenteral support (intravenous fluid, parenteral nutrition, or parenteral nutrition with intravenous fluid) to compensate for severe malabsorption. The loss of mucosal absorptive area after extensive intestinal resection is accompanied by an accelerated transit and hypersecretion. Changes in physiology and clinical outcomes differ between patients with SBS with or without the distal ileum and/or colon-in-continuity. This narrative review summarizes the treatments used in SBS, with a focus on novel approaches with intestinotrophic agents. During the early postoperative years, spontaneous adaptation occurs and can be induced or accelerated with conventional therapies, which include dietary and fluid modifications and antidiarrheal and antisecretory drugs. Based on the proadaptive role of enterohormones (eg, glucagon-like peptide [GLP]-2), analogues have been developed to allow enhanced or hyperadaptation after a period of stabilization. Teduglutide is the first GLP-2 analogue developed and commercialized with proadaptive effects resulting in reduced parenteral support needs; however, the potential for weaning of parenteral support is variable. Whether early treatment with enterohormones or accelerated hyperadaptation would further improve absorption and outcomes remains to be shown. Longer-acting GLP-2 analogues are currently being investigated. Encouraging reports with GLP-1 agonists require confirmation in randomized trials, and dual GLP-1 and GLP-2 analogues have yet to be clinically investigated. Future studies will prove whether the timing and/or combinations of different enterohormones will be able to break the ceiling of intestinal rehabilitation in SBS.

Long-acting agonists of human and rodent GLP-2 receptors for studies of the physiology and pharmacological potential of the GLP-2 system.

BACKGROUND AND PURPOSE: Glucagon-like peptide-2 (GLP-2) is secreted postprandially from enteroendocrine Lcells and has anabolic action on gut and bone. Short-acting teduglutide is the only approved GLP-2 analog for the treatment of short-bowel syndrome (SBS). To improve the therapeutic effect, we created a series of lipidated GLP-2R agonists. EXPERIMENTAL APPROACH: Six GLP-2 analogs were studied in vitro for cAMP accumulation, ß-arrestin 1 and 2 recruitment, affinity, and internalization. The trophic actions on intestine and bone were examined in vivo in rodents. KEY RESULTS: Lipidations at lysines introduced at position 12, 16, and 20 of hGLP-2(1-33) were well-tolerated with less than 2.2-fold impaired potency and full efficacy at the hGLP-2R in cAMP accumulation. In contrast, N- and C-terminal (His1 and Lys30) lipidations impaired potency by 4.2- and 45-fold and lowered efficacy to 77% and 85% of hGLP-2, respectively. All variants were similarly active on the rat and mouse GLP-2Rs and the three most active variants displayed increased selectivity for hGLP-2R over hGLP-1R activation, compared to native hGLP-2. Impact on arrestin recruitment and receptor internalization followed that of Gαs-coupling, except for lipidation in position 20, where internalization was more impaired, suggesting desensitization protection. A highly active variant (C16 at position 20) with low internalization and a half-life of 9.5 h in rats showed improved gut and bone tropism with increased weight of small intestine in mice and decreased CTX levels in rats. CONCLUSION AND IMPLICATION: We present novel hGLP-2 agonists suitable for in vivo studies of the GLP-2 system to uncover its pharmacological potential.

Biased GLP-2 agonist with strong G protein-coupling but impaired arrestin recruitment and receptor desensitization enhances intestinal growth in mice.

BACKGROUND AND PURPOSE: Glucagon-like peptide-2 (GLP-2) is secreted postprandially by enteroendocrine L-cells and stimulates growth of the gut and bone. One GLP-2 analogue is approved for short bowel syndrome (SBS). To improve therapeutic efficacy, we developed biased GLP-2 receptor (GLP-2R) agonists through N-terminal modifications. EXPERIMENTAL APPROACH: Variants with Ala and Trp substitutions of the first seven positions of GLP-2(1-33) were studied in vitro for affinity, G protein activation (cAMP accumulation), recruitment of ß-arrestin 1 and 2, and internalization of the human and mouse GLP-2R. The intestinotrophic actions of the most efficacious (cAMP) biased variant were examined in mice. KEY RESULTS: Ala substitutions had more profound effects than Trp substitutions. For both, alterations at positions 1, 3 and 6 most severely impaired activity. ß-arrestin recruitment was more affected than cAMP accumulation. Among Ala substitutions, [H1A], [D3A] and [F6A] impaired potency (EC50 ) for cAMP-accumulation >20-fold and efficacy (Emax ) to 48%-87%, and were unable to recruit arrestins. The Trp substitutions, [A2W], [D3W] and [G4W] were partial agonists (Emax of 46%-59%) with 1.7-12-fold decreased potencies in cAMP and diminished ß-arrestin recruitment. The biased variants, [F6A], [F6W] and [S7W] induced less GLP-2R internalization compared with GLP-2, which induced internalization in a partly arrestin-independent manner. In mice, [S7W] enhanced gut trophic actions with increased weight of the small intestine, increased villus height and crypt depth compared with GLP-2. CONCLUSION AND IMPLICATIONS: G protein-biased GLP-2R agonists with diminished receptor desensitization have superior intestinotrophic effects and may represent improved treatment of intestinal insufficiency including SBS.

HM15912, a Novel Long-Acting Glucagon-Like Peptide-2 Analog, Improves Intestinal Growth and Absorption Capacity in a Male Rat Model of Short Bowel Syndrome.

Extensive bowel resection caused by various diseases that affect the intestines, such as Crohn's disease, volvulus, and cancer, leads to short bowel syndrome (SBS). Teduglutide is the only approved glucagon-like peptide-2 (GLP-2) drug for SBS; however, it requires daily administration. A novel GLP-2 analog with a prolonged duration of action to reduce dosing frequency and promote a greater efficacy may provide patients with a better quality of life. In the present study, the sustained exposure of HM15912 was characterized in normal male rats. The efficacy of HM15912 on intestinal growth and absorption capacity was also evaluated in normal male mice, rats, and SBS rats. HM15912 exhibited a remarkably extended half-life (42.3 hours) compared with teduglutide (0.6 hours) in rats. Despite somewhat lower in vitro potency on GLP-2 receptor than human GLP-2 or teduglutide, this longer-lasting mode of action promotes HM15912 to be more effective in terms of small intestinal growth than existing GLP-2 analogs even with a less frequent dosing interval of as little as once a week in rodents, including SBS rats. Furthermore, the small intestinal weight was approximately doubled, and the D-xylose absorption was significantly increased after pre-treatment of existing GLP-2 analogs on the market or under clinical development followed by HM15912 in rodents. These results indicate that HM15912 possesses a significant small bowel trophic effect driven by continuously increased exposure, supporting that HM15912 may be a novel treatment option with greater efficacy and the longest dosing interval among existing GLP-2 analogs for SBS with intestinal failure. SIGNIFICANCE STATEMENT: HM15912, a novel long-acting glucagon-like peptide-2 (GLP-2) analog, has a significant small bowel hypertrophic effect in rodents with a reduced frequency of administration compared to the existing GLP-2 analogs on the market or currently under clinical development. This study supports the possibility that HM15912 could be administered much less frequently than other long-acting GLP-2 analogs for patients with short bowel syndrome.

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.

Glucagon-like Peptide-2 Acutely Enhances Chylomicron Secretion in Humans Without Mobilizing Cytoplasmic Lipid Droplets.

CONTEXT: A portion of ingested fats are retained in the intestine for many hours before they are mobilized and secreted in chylomicron (CM) particles. Factors such as glucagon-like peptide-2 (GLP-2) and glucose can mobilize these stored intestinal lipids and enhance CM secretion. We have recently demonstrated in rodents that GLP-2 acutely enhances CM secretion by mechanisms that do not involve the canonical CM synthetic assembly and secretory pathways. OBJECTIVE: To further investigate the mechanism of GLP-2's potent intestinal lipid mobilizing effect, we examined intracellular cytoplasmic lipid droplets (CLDs) in intestinal biopsies of humans administered GLP-2 or placebo. DESIGN, SETTING, PATIENTS, AND INTERVENTIONS: A single dose of placebo or GLP-2 was administered subcutaneously 5 hours after ingesting a high-fat bolus. In 1 subset of participants, plasma samples were collected to quantify lipid and lipoprotein concentrations for 3 hours after placebo or GLP-2. In another subset, a duodenal biopsy was obtained 1-hour after placebo or GLP-2 administration for transmission electron microscopy and proteomic analysis. RESULTS: GLP-2 significantly increased plasma triglycerides by 46% (P = 0.009), mainly in CM-sized particles by 133% (P = 0.003), without reducing duodenal CLD size or number. Several proteins of interest were identified that require further investigation to elucidate their potential role in GLP-2-mediated CM secretion. CONCLUSIONS: Unlike glucose that mobilizes enterocyte CLDs and enhances CM secretion, GLP-2 acutely increased plasma CMs without significant mobilization of CLDs, supporting our previous findings that GLP-2 does not act directly on enterocytes to enhance CM secretion and most likely mobilizes secreted CMs in the lamina propria and lymphatics.

Effects of glepaglutide, a long-acting glucagon-like peptide-2 analog, on intestinal morphology and perfusion in patients with short bowel syndrome: Findings from a randomized phase 2 trial.

BACKGROUND: The proadaptive effects of glucagon-like peptide-2 (GLP-2) include stimulation of intestinal mucosal growth as well as intestinal blood flow and angiogenesis. We have recently reported that daily subcutaneous injections of glepaglutide, a long-acting GLP-2 analog, improved intestinal absorptive function in patients with short bowel syndrome (SBS). As secondary and exploratory end points, the effects of glepaglutide on intestinal morphology and perfusion are reported. METHODS: The following assessments were done in 18 patients with SBS in a randomized, crossover, dose-finding, phase 2 trial before and after three weeks of treatment with glepaglutide: plasma citrulline and mucosa biopsies to assess changes in (1) intestinal morphology by immunohistochemistry and (2) gene expressions associated with absorption, proliferation, and markers of tight-junction integrity by quantitative polymerase chain reaction. Intestinal perfusion was assessed in stoma nipples by laser speckle contrast imaging and quantitative fluorescence angiography with indocyanine green. RESULTS: In the 1- and 10-mg dose groups, glepaglutide significantly increased plasma citrulline by 15.3 µmol/L (P = 0.001) and 15.6 µmol/L (P = 0.001), respectively. Trends toward an increase in villus height, crypt depth, and epithelium height were seen in the same groups. No significant changes were seen in gene expressions or intestinal perfusion. CONCLUSION: The increase in plasma citrulline and the morphological improvements may partly account for improvement in the intestinal absorptive function. However, the finding of a stability in perfusion after three weeks of treatment with glepaglutide may have been preceded by a more profound acute-phase increase in intestinal perfusion at treatment initiation.

The dual GLP-1 and GLP-2 receptor agonist dapiglutide promotes barrier function in murine short bowel.

Short bowel syndrome can occur after extensive intestinal resection, causing intestinal insufficiency or intestinal failure, which requires long-term parenteral nutrition. Glucagon-like peptide-2 (GLP-2) pharmacotherapy is now clinically used to reduce the disease burden of intestinal failure. However, many patients still cannot be weaned off from parenteral nutrition completely. The novel dual GLP-1 and GLP-2 receptor agonist dapiglutide has previously been shown to be highly effective in a preclinical murine short bowel model. Here, we studied the effects of dapiglutide on intestinal epithelial barrier function. In the jejunum, dapiglutide increased claudin-7 expression and tightened the paracellular tight junction leak pathway. At the same time, dapiglutide promoted paracellular tight junction cation size selectivity in the jejunum. This was paralleled by extension of the cation selective tight junction proteins claudin-2 and claudin-10b and preserved claudin-15 expression and localization along the crypt-villus axis in the jejunum. In the colon, no barrier effects from dapiglutide were observed. In the colon, dapiglutide attenuated the short bowel-associated, compensatorily increased epithelial sodium channel activity, likely secondary, by improved volume status. Future studies are needed to address the intestinal adaptation of the colon.

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.

A Protective Role for Glucagon-like Peptide-2 in Heat-stable Enterotoxin b (STb)-Induced L-Cell Toxicity.

Enterotoxigenic Escherichia coli (ETEC)-derived purified heat-stable enterotoxin b (STb) is responsible for secretory diarrhea in livestock and humans. STb disrupts intestinal fluid homeostasis, epithelial barrier function, and promotes cell death. Glucagon-like peptide-2 (GLP-2) is a potent intestinotrophic hormone secreted by enteroendocrine L cells. GLP-2 enhances crypt cell proliferation, epithelial barrier function, and inhibits enterocyte apoptosis. Whether STb can affect GLP-2 producing L cells remains to be elucidated. First, secreted-His-labeled STb from transformed E coli was collected and purified. When incubated with L-cell models (GLUTag, NCI-H716, and secretin tumor cell line [STC-1]), fluorescent immunocytochemistry revealed STb was internalized and was differentially localized in the cytoplasm and nucleus. Cell viability experiments with neutral red and resazurin revealed that STb was toxic in all but the GLUTag cells. STb stimulated 2-hour GLP-2 secretion in all cell models. Interestingly, GLUTag cells produced the highest amount of GLP-2 when treated with STb, demonstrating an inverse relationship in GLP-2 secretion and cell toxicity. To demonstrate a protective role for GLP-2, GLUTag-conditioned media (rich in GLP-2) blocked STb toxicity in STC-1 cells. Confirming a protective role of GLP-2, teduglutide was able to improve cell viability in cells treated with H2O2. In conclusion, STb interacts with the L cell, stimulates secretion, and may induce toxicity if GLP-2 is not produced at high levels. GLP-2 or receptor agonists have the ability to improve cell viability in response to toxins. These results suggest that GLP-2 secretion can play a protective role during STb intoxication. This work supports future investigation into the use of GLP-2 therapies in enterotoxigenic-related diseases.

Glucagon-Like Peptide-2 in the Control of Gastrointestinal Motility: Physiological Implications.

Glucagon-Like Peptide-2 (GLP-2) is a pleiotropic hormone that plays several roles in different organs and tissues, so being involved in many physiological processes. Among these, it regulates gastrointestinal (GI) tract function binding to a specific G-protein coupled receptor (GLP-2R). Of note, GLP-2R is widely expressed in different cells of the GI tract, including excitatory and inhibitory neurons of the enteric nervous system. In the gut, GLP-2 has been reported to play numerous actions, among which the modulation of motility. Nevertheless, most of the GLP-2 effects and its role in physiological processes are still debated. The aim of this minireview is to summarize the data present in the literature on the control of GI motility by GLP-2, the mechanism through which it occurs, and to discuss the physiological implications of such effects. A better understanding of the role of GLP-2 on GI motor responses may be of importance for the development of new therapeutic approaches in GI dysmotility.

Glucagon-Like Peptide-2 Stimulates S-Phase Entry of Intestinal Lgr5+ Stem Cells.

BACKGROUND & AIMS: Leucine-rich repeat-containing G-protein-coupled receptor-5 (Lgr5)+/olfactomedin-4 (Olfm4)+ intestinal stem cells (ISCs) in the crypt base are crucial for homeostatic maintenance of the epithelium. The gut hormone, glucagon-like peptide-21-33 (GLP-2), stimulates intestinal proliferation and growth; however, the actions of GLP-2 on the Lgr5+ ISCs remain unclear. The aim of this study was to determine whether and how GLP-2 regulates Lgr5+ ISC cell-cycle dynamics and numbers. METHODS: Lgr5-Enhanced green-fluorescent protein - internal ribosome entry site - Cre recombinase - estrogen receptor T2 (eGFP-IRES-creERT2) mice were acutely administered human Glycine2 (Gly2)-GLP-2, or the GLP-2-receptor antagonist, GLP-23-33. Intestinal epithelial insulin-like growth factor-1-receptor knockout and control mice were treated chronically with human Gly2 (hGly2)-GLP-2. Cell-cycle parameters were determined by 5-Ethynyl-2'-deoxyuridine (EdU), bromodeoxyuridine, antibody #Ki67, and phospho-histone 3 labeling and cell-cycle gene expression. RESULTS: Acute hGly2-GLP-2 treatment increased the proportion of eGFP+EdU+/OLFM4+EdU+ cells by 11% to 22% (P < .05), without affecting other cell-cycle markers. hGly2-GLP-2 treatment also increased the ratio of eGFP+ cells in early to late S-phase by 97% (P < .001), and increased the proportion of eGFP+ cells entering S-phase by 218% (P < .001). hGly2-GLP-2 treatment induced jejunal expression of genes involved in cell-cycle regulation (P < .05), and increased expression of Mcm3 in the Lgr5-expressing cells by 122% (P < .05). Conversely, GLP-23-33 reduced the proportion of eGFP+EdU+ cells by 27% (P < .05), as well as the expression of jejunal cell-cycle genes (P < .05). Finally, chronic hGly2-GLP-2 treatment increased the number of OLFM4+ cells/crypt (P < .05), in an intestinal epithelial insulin-like growth factor-1-receptor-dependent manner. CONCLUSIONS: These findings expand the actions of GLP-2 to encompass acute stimulation of Lgr5+ ISC S-phase entry through the GLP-2R, and chronic induction of Lgr5+ ISC expansion through downstream intestinal insulin-like growth factor-1 signaling.

GIP and GLP-2 together improve bone turnover in humans supporting GIPR-GLP-2R co-agonists as future osteoporosis treatment.

The intestinal hormones glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-2 (GLP-2) are key regulators of postprandial bone turnover in humans. We hypothesized that GIP and GLP-2 co-administration would provide stronger effect on bone turnover than administration of the hormones separately, and tested this using subcutaneous injections of GIP and GLP-2 alone or in combination in humans. Guided by these findings, we designed series of GIPR-GLP-2R co-agonists as template for new osteoporosis treatment. The clinical experiment was a randomized cross-over design including 10 healthy men administered subcutaneous injections of GIP and GLP-2 alone or in combination. The GIPR-GLP-2R co-agonists were characterized in terms of binding and activation profiles on human and rodent GIP and GLP-2 receptors, and their pharmacokinetic (PK) profiles were improved by dipeptidyl peptidase-4 protection and site-directed lipidation. Co-administration of GIP and GLP-2 in humans resulted in an additive reduction in bone resorption superior to each hormone individually. The GIPR-GLP-2R co-agonists, designed by combining regions of importance for cognate receptor activation, obtained similar efficacies as the two native hormones and nanomolar potencies on both human receptors. The PK-improved co-agonists maintained receptor activity along with their prolonged half-lives. Finally, we found that the GIPR-GLP-2R co-agonists optimized toward the human receptors for bone remodeling are not feasible for use in rodent models. The successful development of potent and efficacious GIPR-GLP-2R co-agonists, combined with the improved effect on bone metabolism in humans by co-administration, support these co-agonists as a future osteoporosis treatment.

Enterohormone therapy for short bowel syndrome.

PURPOSE OF REVIEW: Short bowel syndrome (SBS) patients are at risk to develop intestinal failure when the decreased absorption of macronutrients, water, and electrolytes necessitates parenteral support for survival. The adverse effects of SBS and parenteral support negatively affect the quality of life (QoL) of SBS-intestinal failure patients. However, spontaneous intestinal adaptation along with disease-modifying therapies allow reducing parenteral support, thereby improving QoL. RECENT FINDINGS: During the first years following extensive surgery, spontaneous structural and functional intestinal changes take place which stimulate a more efficient nutrient and fluid absorption in the remaining bowel. Given their potential role in the ileal braking mechanism, enterohormones, such as glucagon-like peptide (GLP)-2, GLP-1, and peptide YY (PYY), promote an accelerated adaptation or hyperadaptation. While the exact role of GLP-1 and PYY in SBS is still being explored, GLP-2 analogs have clearly shown to be effective in improving outcome in SBS. SUMMARY: Whereas spontaneous intestinal adaptation improves the nutritional status of SBS patients to a certain extent, GLP-2 analogs can further decrease parenteral support needs through hyperadaptation. There are, however, other promising candidates on the horizon that - alone or in combination - could possibly establish additional disease-modifying effects.

Dapiglutide, a novel dual GLP-1 and GLP-2 receptor agonist, attenuates intestinal insufficiency in a murine model of short bowel.

BACKGROUND: Extensive intestinal resection may lead to short bowel (SB) syndrome, resulting in intestinal insufficiency or intestinal failure (IF). Intestinal insufficiency and IF involve deficiency of the proglucagon-derived hormones glucagon-like peptide-1 (GLP-1) and GLP-2. Two major problems of SB are epithelial surface loss and accelerated transit. Standard treatment now targets intestinal adaptation with a GLP-2 analogue to enlarge absorptive surface area. It is possible that additional benefit can be gained from a combination of GLP-1 and GLP-2 activity, with the aim to enlarge intestinal surface area and slow intestinal transit. METHODS: The GLP-1- and GLP-2-specific effects of the novel dual GLP-1 receptor (GLP-1R) and GLP-2 receptor (GLP-2R) agonist dapiglutide (rINN) were characterized in rodents. Furthermore, in a murine SB model of intestinal insufficiency with 40% ileocecal resection, the influence of dapiglutide on intestinal growth, body weight, food intake, volume status, and stool water content was tested against vehicle and sham-operated male mice. RESULTS: Dapiglutide significantly improves oral glucose tolerance, reduces intestinal transit time, and promotes intestinal growth. In the SB mouse model, dapiglutide promotes body weight recovery, despite unchanged intake of liquid diet. Dapiglutide promotes significant intestinal growth, as indicated by significantly increased villus height as well as intestinal length. Furthermore, dapiglutide reduces stool water losses, resulting in reduced plasma aldosterone. CONCLUSION: Dapiglutide possesses specific and potent GLP-1R and GLP-2R agonist effects in rodents. In the murine SB model, combined unimolecular GLP-1R and GLP-2R stimulation with dapiglutide potently attenuates intestinal insufficiency and potentially also IF.

Bile acid-farnesoid X receptor-fibroblast growth factor 19 axis in patients with short bowel syndrome: The randomized, glepaglutide phase 2 trial.

BACKGROUND: The gut-liver axis and enterohepatic circulation have gained increasing attention lately. Patients with short bowel syndrome (SBS) are, in fact, human knock-out models that may assist in the understanding of bile acid synthesis and regulation. We evaluated effect of glepaglutide (a long-acting glucagon-like peptide-2 analog) on bile acid synthesis (the enterohepatic circulation of bile acids and liver biochemistry in patients with SBS). METHOD: In a single-center, double-blinded, dose-finding, crossover phase 2 trial, 18 patients with SBS were randomly assigned to 2 of 3 treatment arms (0.1, 1, and 10 mg) with daily subcutaneous injections of glepaglutide for 3 weeks. The washout period between the 2 treatment periods was 4-8 weeks. Measurements were performed at baseline and at the end of each treatment period and included postprandial plasma samples for fibroblast growth factor 19 (FGF19), 7α-hydroxy-4-cholesten-3-one (C4), total excretion of fecal bile acids, gene expression of farnesoid X receptor (FXR) in intestinal mucosal biopsies, total plasma bile acids, and liver biochemistry. RESULTS: Compared with baseline, the median (interquartile range) postprandial response (area under the curve 0-2h) of FGF19 increased by 150 h × ng/L (41, 195; P = 0.001) and C4 decreased by 82 h × µg/L (-169, -28; p = 0.010) in the 10-mg dose. FXR gene expression did not change in any of the groups. Alkaline phosphatase significantly decreased. CONCLUSION: Glepaglutide may stimulate the bile acid/FXR/FGF19 axis, leading to increased plasma concentrations of FGF19. Thereby, glepaglutide may ameliorate the accelerated de novo bile acid synthesis and play a role in the prevention and/or treatment of intestinal failure-associated liver disease.

Complementary and antagonistic effects of combined glucagon-like peptide-2 and glucagon-like peptide-1 receptor agonist administration on parameters relevant to short bowel syndrome.

BACKGROUND: Short bowel syndrome (SBS) is characterized by malabsorption requiring parenteral nutrition. The intestinotrophic glucagon-like peptide (GLP)-2 receptor agonist, h[Gly2]GLP2, is used to treat patients with SBS. Evidence suggests that GLP-1 receptor agonists such as exendin-4 (Ex4) may be beneficial in SBS given their ability to increase intestinal growth and delay gastric emptying (GE). METHODS: Intestinal growth, body weight (BW), food intake (FI), GE, gastrointestinal (GI) transit, intestinal permeability, and glucose tolerance were investigated in male and female C57/BL6 mice following vehicle, h[Gly2]GLP2, or Ex4 treatment, alone or in combination at "low," "medium," and "high" doses (0.1, 0.5, 1.0 and 0.01, 0.05, 0.1 µg/g, respectively). RESULTS: Only the h[Gly2]GLP2 low/Ex4 high-dose combination additively increased small intestinal (SI) weight compared with vehicle and both monoagonists (P < 0.01-0.001), via increased villus height (P < 0.01) and SI length (P < 0.05). This combination had no effects on BW; FI; and fat, liver, spleen, heart, and kidney weights but reduced GI transit (P < 0.001) versus low-dose h[Gly2]GLP2 monotreatment and abrogated the inhibitory effects of high-dose Ex4 on GE (P < 0.01) and of low-dose h[Gly2]GLP2 on intestinal permeability (P < 0.05). Ex4-induced improvements in glucose homeostasis were maintained upon combination with h[Gly2]GLP2 (P < 0.001). CONCLUSIONS: These findings suggest that combining specific doses of GLP-2- and GLP-1 receptor agonists additively improves SI growth and GI transit without detrimental effects on BW, FI, GE, and glucose homeostasis, and may be useful for the treatment of patients with SBS.