The Role of Lactoferrin in Intestinal Health.

The intestine represents one of the first barriers where microorganisms and environmental antigens come into tight contact with the host immune system. A healthy intestine is essential for the well-being of humans and animals. The period after birth is a very important phase of development, as the infant moves from a protected environment in the uterus to one with many of unknown antigens and pathogens. In that period, mother's milk plays an important role, as it contains an abundance of biologically active components. Among these components, the iron-binding glycoprotein, lactoferrin (LF), has demonstrated a variety of important benefits in infants and adults, including the promotion of intestinal health. This review article aims to provide a compilation of all the information related to LF and intestinal health, in infants and adults.

Early weaning causes small intestinal atrophy by inhibiting the activity of intestinal stem cells: involvement of Wnt/ß-catenin signaling.

BACKGROUND: Early weaning and shorter breastfeeding duration are applied by a proportion of young mothers, especially in the social spheres of poverty-stricken areas. Early childhood is a critical period for intestinal development, which is driven by intestinal stem cells (ISCs). However, how early weaning practice affects the function of ISCs to mediate intestinal development remains unclear. METHODS: We established an excellent early weaning mice model that has significant intestinal atrophy and growth arrest symptoms to explore the responses of ISCs to early weaning. The primary and passaged intestinal organoids from the suckling or early weaning mice were cultured to explore the underlying mechanism of early weaning affecting the ISCs. RESULTS: Early weaning depressed the self-renewal of ISCs and attenuated the activity of ISCs-driven intestinal epithelial regeneration and crypt expansion in vivo and ex-vivo. Further results showed that early weaning retarded the differentiation of ISCs into transit-amplifying cells and Paneth cells, and accelerated the apoptosis of villous epithelial cells, jointly leading to intestinal epithelial atrophy. Mechanistically, early weaning inhibited Wnt signaling in ISCs, while an exogenous Wnt amplifier restored ISCs' function in ex-vivo. CONCLUSION: Our findings indicate that early weaning depresses the activity of ISCs via attenuating Wnt/ß-catenin signaling and triggers the proinflammatory cytokines TNF-α, IL-1ß, IL-6, and IL-17 in jejunum, thereby impeding ISCs-driven epithelial regeneration and intestinal growth, which may provide a basal theory for the development of infant nutrients targeting stem cells to alleviate early weaning-induced intestinal problems.

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.

Effects of floor- and net-rearing systems on intestinal growth and microbial diversity in the ceca of ducks.

BACKGROUND: Rearing systems can affect livestock production directly, but whether they have effects on intestinal growth states and ceca microorganisms in ducks is largely unclear. The current study used Nonghua ducks to estimate the effects of rearing systems on the intestines by evaluating differences in intestinal growth indices and cecal microorganisms between ducks in the floor-rearing system (FRS) and net-rearing system (NRS). RESULTS: The values of relative weight (RW), relative length (RL) and RW/RL of the duodenum, jejunum, ileum and ceca in the FRS were significantly higher than those in the NRS during weeks 4, 8 and 13 (p < 0.05). A total of 157 genera were identified from ducks under the two systems, and the dominant microorganisms in both treatments were Firmicutes, Bacteroidetes, Actinobacteria and Proteobacteria at the phylum level. The distribution of microorganisms in the ceca of the two treatments showed significant separation during the three time periods, and the value of the Simpson index in the FRS was significantly higher than that in the NRS at 13 weeks (p < 0.05). Five differential microorganisms and 25 differential metabolic pathways were found in the ceca at week 4, seven differential microorganisms and 25 differential metabolic pathways were found in the ceca at week 8, and four differential microorganisms and two differential metabolic pathways were found in the ceca at week 13. CONCLUSIONS: The rearing system influences duck intestinal development and microorganisms. The FRS group had higher intestinal RL, RW and RW/RL and obviously separated ceca microorganisms compared to those of the NRS group. The differential metabolic pathways of cecal microorganisms decreased with increasing age, and the abundance of translation pathways was higher in the NRS group at week 13, while cofactor and vitamin metabolism were more abundant in the FRS group.

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.

Intestinal Growth in Glucagon Receptor Knockout Mice Is Not Associated With the Formation of AOM/DSS-Induced Tumors.

Treatment with exogenous GLP-2 has been shown to accelerate the growth of intestinal adenomas and adenocarcinomas in experimental models of colonic neoplasia, however, the role of endogenous GLP-2 in tumor promotion is less well known. Mice with a global deletion of the glucagon receptor (Gcgr-/-) display an increase in circulating GLP-1 and GLP-2. Due to the intestinotrophic nature of GLP-2, we hypothesized that Gcgr-/- mice would be more susceptible to colonic dysplasia in a model of inflammation-induced colonic carcinogenesis. Female Gcgr-/- mice were first characterized for GLP-2 secretion and in a subsequent study they were given a single injection with the carcinogen azoxymethane (7.5 mg/kg) and treated with dextran sodium sulfate (DSS) (3%) for six days (n=19 and 9). A cohort of animals (n=4) received a colonoscopy 12 days following DSS treatment and all animals were sacrificed after six weeks. Disruption of glucagon receptor signaling led to increased GLP-2 secretion (p<0.0001) and an increased concentration of GLP-2 in the pancreas of Gcgr-/- mice, coinciding with an increase in small intestinal (p<0.0001) and colonic (p<0.05) weight. Increased villus height was recorded in the duodenum (p<0.001) and crypt depth was increased in the duodenum and jejunum (p<0.05 and p<0.05). Disruption of glucagon receptor signaling did not affect body weight during AOM/DSS treatment, neither did it affect the inflammatory score assessed during colonoscopy or the number of large and small adenomas present at the end of the study period. In conclusion, despite the increased endogenous GLP-2 secretion Gcgr-/- mice were not more susceptible to AOM/DSS-induced tumors.

The safety of available treatment options for short bowel syndrome and unmet needs.

INTRODUCTION: Short bowel syndrome (SBS) is a rare, highly disabling, life-threatening condition due to extensive intestinal resections, characterized by diarrhea, malabsorption, and malnutrition. SBS is the main cause of intestinal failure (SBS-IF). The primary therapy for SBS-IF is intravenous supplementation (IVS) of nutrients. The pharmacological therapy aims to improve the remnant bowel function, leading to the decrease of IVS requirement. AREAS COVERED: This review provides a safety perspective and discusses unmet clinical needs on pharmacotherapy for SBS, ranging from symptomatic agents traditionally used off-label to manage hypersecretion and diarrhea, to curative drugs with selective intestinotrophic properties. Real-world evidence on symptomatic drugs is lacking. Data on teduglutide - the first-in-class glucagon-like peptide-2 (GLP-2) receptor agonist approved in SBS - are mainly derived from clinical trials, with several unsettled safety issues, including the risk of malignancies. EXPERT OPINION: Defining the long-term safety of drugs used for SBS is a priority; a unified list of commonly used drugs with consolidated proof of effectiveness is needed to harmonize the symptomatic pharmacological approach to SBS. GLP-2 receptor agonists are a promising curative pharmaco-therapeutic approach, although long-term safety and effectiveness deserve further real-world assessment. Pharmacovigilance and global data sharing are crucial to support safe prescribing in SBS.

Short communication: Effect of delaying the first colostrum feeding on small intestinal histomorphology and serum insulin-like growth factor-1 concentrations in neonatal male Holstein calves.

The primary objective of this study was to determine the effect of delaying the first colostrum feeding on small intestinal histomorphology and serum insulin-like growth factor-1 (IGF-1) concentrations, and the secondary objective was to characterize the ultrastructure of the small intestine of neonatal calves at 51 h of life. Twenty-seven male Holstein calves were fed pooled, pasteurized colostrum (7.5% of birth body weight; 62 g of IgG/L) at 45 min (0H, n = 9), 6 h (6H, n = 9), or 12 h (12H, n = 9) after birth. At 12 h after their respective colostrum feeding, calves were fed milk replacer at 2.5% of birth body weight per meal and every 6 h thereafter. Blood samples were collected every 6 h using a jugular catheter and analyzed for serum IGF-1 concentrations using an automated solid-phase chemiluminescent immunoassay. At 51 h of life, calves were euthanized to facilitate collection of the duodenum, proximal and distal jejunum, and ileum. All segments of the small intestine were assessed for histomorphology, whereas scanning electron and transmission electron microscopy analyses were conducted only for the proximal jejunum and ileum. The results revealed that there was no overall effect of colostrum feeding time on serum IGF-1 concentrations; however, serum IGF-1 concentrations were influenced by time. Specifically, concentrations of serum IGF-1 at 48 h were 29% greater than concentrations at 0 h of life (312.8 ± 14.85 vs. 241.9 ± 14.06 ng/mL). Although there was no overall effect of colostrum feeding time on all histomorphological measures assessed, treatment × segment interactions were observed. Villi height was 1.4 times greater in the distal jejunum of 0H calves than in 6H and 12H calves, and 0H calves tended to have 1.2 times greater ileal villus height than 12H calves. In addition, 0H calves had 1.2 and 1.3 times greater ileal crypt depth than 6H and 12H calves, respectively, and 1.3 times greater surface area index than 12H calves in the distal jejunum. Qualitative ultrastructural evaluation of small intestinal enterocytes conducted irrespective of colostrum treatment revealed the presence of large vacuoles of electron-dense material, apical mitochondria, and apical canalicular systems in the jejunum and ileum. These results indicate that the calf intestine at 51 h of life contains unique enterocyte characteristics similar to fetal enterocytes and that delaying colostrum feeding may negatively influence intestinal growth and development.

Translational Advances in Pediatric Nutrition and Gastroenterology: New Insights from Pig Models.

Pigs are increasingly important animals for modeling human pediatric nutrition and gastroenterology and complementing mechanistic studies in rodents. The comparative advantages in size and physiology of the neonatal pig have led to new translational and clinically relevant models of important diseases of the gastrointestinal tract and liver in premature infants. Studies in pigs have established the essential roles of prematurity, microbial colonization, and enteral nutrition in the pathogenesis of necrotizing enterocolitis. Studies in neonatal pigs have demonstrated the intestinal trophic effects of akey gut hormone, glucagon-like peptide 2 (GLP-2), and its role in the intestinal adaptation process and efficacy in the treatment of short bowel syndrome. Further, pigs have been instrumental in elucidating the physiology of parenteral nutrition-associated liver disease and the means by which phytosterols, fibroblast growth factor 19, and a new generation of lipid emulsions may modify disease. The premature pig will continue to be a valuable model in the development of optimal infant diets (donor human milk, colostrum), specific milk bioactives (arginine, growth factors), gut microbiota modifiers (pre-, pro-, and antibiotics), pharmaceutical drugs (GLP-2 analogs, FXR agonists), and novel diagnostic tools (near-infrared spectroscopy) to prevent and treat these pediatric diseases.

Nonmicrobial Activation of TLRs Controls Intestinal Growth, Wound Repair, and Radioprotection.

TLRs, key components of the innate immune system, recognize microbial molecules. However, TLRs also recognize some nonmicrobial molecules. In particular, TLR2 and TLR4 recognize hyaluronic acid, a glycosaminoglycan in the extracellular matrix. In neonatal mice endogenous hyaluronic acid binding to TLR4 drives normal intestinal growth. Hyaluronic acid binding to TLR4 in pericryptal macrophages results in cyclooxygenase2- dependent PGE2 production, which transactivates EGFR in LGR5+ crypt epithelial stem cells leading to increased proliferation. The expanded population of LGR5+ stem cells leads to crypt fission and lengthening of the intestine and colon. Blocking this pathway at any point (TLR4 activation, PGE2 production, EGFR transactivation) results in diminished intestinal and colonic growth. A similar pathway leads to epithelial proliferation in wound repair. The repair phase of dextran sodium sulfate colitis is marked by increased epithelial proliferation. In this model, TLR2 and TLR4 in pericryptal macrophages are activated by microbial products or by host hyaluronic acid, resulting in production of CXCL12, a chemokine. CXCL12 induces the migration of cyclooxygenase2-expressing mesenchymal stem cells from the lamina propria of the upper colonic crypts to a site adjacent to LGR5+ epithelial stem cells. PGE2 released by these mesenchymal stem cells transactivates EGFR in LGR5+ epithelial stem cells leading to increased proliferation. Several TLR2 and TLR4 agonists, including hyaluronic acid, are radioprotective in the intestine through the inhibition of radiation-induced apoptosis in LGR5+ epithelial stem cells. Administration of exogenous TLR2 or TLR4 agonists activates TLR2/TLR4 on pericryptal macrophages inducing CXCL12 production with migration of cyclooxygenase2-expressing mesenchymal stem cells from the lamina propria of the villi to a site adjacent to LGR5+ epithelial stem cells. PGE2 produced by these mesenchymal stem cells, blocks radiation-induced apoptosis in LGR5+ epithelial stem cells by an EGFR mediated pathway.

Effects of ad libitum milk replacer feeding and butyrate supplementation on the epithelial growth and development of the gastrointestinal tract in Holstein calves.

Intensive milk feeding and butyrate supplementation in calves stimulate body growth and affect gastrointestinal development. The aim of the present study was to investigate the synergistic effects of ad libitum milk replacer (MR) feeding and butyrate supplementation of MR on rumen and small intestinal growth and on gene expression in the small intestine related to growth and energy metabolism at weaning. Male Holstein calves (n = 32) received colostrum from birth to d 3 of age and MR either ad libitum (Adl) or restrictively (Res; 6 L of MR/d; 12.5% solids) with (AdlB+, ResB+) or without (AdlB-, ResB-) 0.24% butyrate from d 4 until wk 8 of age. From wk 9 to 10, all calves were weaned and were fed 2 L/d until the end of the trial. Concentrate, hay, and water were freely available. At d 80, calves were slaughtered, volatile fatty acids were measured in rumen fluid, and rumen and small intestine samples were taken for histomorphometric measurements. The expression of mRNA associated with the local insulin-like growth factor (IGF) system and glucose metabolism as well as lactase and maltase activities were measured in the intestinal mucosa. The small intestine was 3 m longer in Adl than in Res. In the atrium ruminis, papilla width was greater in Res than in Adl. Villus circumference, cut surface, and height in the duodenum, proximal jejunum, and ileum were greater in Adl than in Res and in the proximal, mid, and distal jejunum and ileum were greater in calves treated with butyrate. Crypt depth in the duodenum and proximal jejunum was greater in Adl than in Res and in the ileum was smaller in calves treated with butyrate. The villus height:crypt depth ratio was greatest in AdlB+ calves. In the proximal and mid jejunum, IGF1 mRNA abundance was lower in calves treated with butyrate. In the proximal jejunum, INSR mRNA abundance was greater in Res than in Adl. The abundance of PCK2 mRNA was greater in Res than in Adl in the duodenum and was greatest in ResB- in the mid jejunum. Lactase activity tended to be greater in Res than in Adl and after butyrate treatment in the proximal jejunum. The results indicated an elevated growth of the small intestinal mucosa at weaning due to intensive milk feeding and butyrate supplementation, and the local IGF system was involved in intestinal growth regulation. Rumen development was not affected by butyrate supplementation of MR and was slightly delayed due to ad libitum MR feeding.

Gastric infusion of short-chain fatty acids can improve intestinal barrier function in weaned piglets.

BACKGROUND: The present study was conducted to investigate the effects of gastric infusion of short-chain fatty acids (SCFA) on gut barrier function in a pig model. In this study, 21 DLY barrows with an average initial body weight of (8.31 ± 0.72) kg were randomly allotted into three treatments: (1) control, (2) infusing low SCFA, S1, (3) infusing high SCFA, S2. The experimental period lasted for 7 days. RESULTS: Gastric infusion of SCFA increased the concentrations of SCFA in serum and digesta, and enhanced the mRNA and protein abundances of SCFA receptors in pig intestine (P < 0.05). Moreover, gastric infusion of SCFA led to alteration of intestinal morphology, elevation of intestinal development-related gene abundances, and decrease of apoptotic cell percentage, as well as reduction of pro-apoptosis gene and protein abundances (P < 0.05). Besides, the jejunal SLC7A1 and ileal DMT1 mRNA abundances in the SCFA infusion groups were higher than those in the control group (P < 0.05). Additionally, gastric infusion of SCFA increased the mRNA abundances of Occludin and Claudin-1 in the duodenum and ileum, enhanced Lactobacillus spp counts in the ileal digesta, decreased the mRNA and protein abundances of IL-1ß in the colon, and reduced Escherichia coli count in the ileal digesta (P < 0.05). CONCLUSIONS: These data indicated that gastric infusion of SCFA, especially high SCFA concentration, may be beneficial to gut development of piglets via improving gut morphology, decreasing apoptotic cell percentage, and maintaining intestinal barrier function.

Active ß-Catenin Signaling in the Small Intestine of Humans During Infancy.

BACKGROUND: Wnt-ß-catenin signaling is essential for homeostasis of intestinal stem cells in mice and is thought to promote intestinal crypt fission. AIMS: The aim of this study was to investigate Wnt-ß-catenin signaling in intestinal crypts of human infants. METHODS: Duodenal biopsies from nine infants (mean, range 0.9 years, 0.3-2 years) and 11 adults (mean, range 43 years, 34-71 years) were collected endoscopically. Active ß-catenin signaling was assessed by cytoplasmic and nuclear ß-catenin, nuclear c-Myc, and cytoplasmic Axin-2 expression in the base of crypts. Tissues were stained by an immunoperoxidase staining technique and quantified as pixel energy using cumulative signal analysis. Data were expressed as mean ± SD and significance assessed by Student's t test. RESULTS: Crypt fission was significantly higher in infants compared to adults (16 ± 8.6% versus 0.7 ± 0.6%, respectively, p < 0.0001). Expression of cytoplasmic and nuclear ß-catenin was 1.8-fold (p < 0.0001) and 2.9-fold (p < 0.0001) higher in infants, respectively, while cytoplasmic Axin-2 was 3.1-fold (p < 0.0001) increased in infants. c-Myc expression was not significantly different between infants and adults. Expression was absent in Paneth cells but present in the transit amplifying zone of crypts. Crypt base columnar cells, which were intercalated between Paneth cells, expressed c-Myc. CONCLUSIONS: Wnt-ß-catenin signaling was active in crypt base columnar cells (i.e., intestinal stem cells) in human infants. This signaling could promote crypt fission during infancy. Wnt-ß-catenin signaling likely acts in concert with other pathways to promote postnatal growth.

Novel GLP-1/GLP-2 co-agonists display marked effects on gut volume and improves glycemic control in mice.

AIM: Analogues of several gastrointestinal peptide hormones have been developed into effective medicines for treatment of diseases such as type 2 diabetes mellitus (T2DM), obesity and short bowel syndrome (SBS). In this study, we aimed to explore whether the combination of glucagon-like peptide-1 (GLP-1) and glucagon-like peptide-2 (GLP-2) into a potent co-agonist could provide additional benefits compared to existing monotherapies. METHODS: A short-acting (GUB09-123) and a half-life extended (GUB09-145) GLP-1/GLP-2 co-agonist were generated using solid-phase peptide synthesis and tested for effects on food intake, body weight, glucose homeostasis, and gut proliferation in lean mice and in diabetic db/db mice. RESULTS: Sub-chronic administration of GUB09-123 to lean mice significantly reduced food intake, improved glucose tolerance, and increased gut volume, superior to monotherapy with the GLP-2 analogue teduglutide. Chronic administration of GUB09-123 to diabetic mice significantly improved glycemic control and showed persistent effects on gastric emptying, superior to monotherapy with the GLP-1 analogue liraglutide. Due to the short-acting nature of the molecule, no effects on body weight were observed, whereas a marked and robust intestinotrophic effect on mainly the small intestine volume and surface area was obtained. In contrast to GUB09-123, sub-chronic administration of a half-life extended GUB09-145 to lean mice caused marked dose-dependent effects on body weight while maintaining its potent intestinotrophic effect. CONCLUSION: Our data demonstrate that the GLP-1/GLP-2 co-agonists have effects on gut morphometry, showing a marked increase in intestinal volume and mucosal surface area. Furthermore, effects on glucose tolerance and long-term glycemic control are evident. Effects on body weight and gastric emptying are also observed depending on the pharmacokinetic properties of the molecule. We suggest that this novel co-agonistic approach could exemplify a novel concept for treatment of T2DM or SBS.

Synergy of glucagon-like peptide-2 and epidermal growth factor coadministration on intestinal adaptation in neonatal piglets with short bowel syndrome.

Glucagon-like peptide-2 (GLP-2) and epidermal growth factor (EGF) treatment enhance intestinal adaptation. To determine whether these growth factors exert synergistic effects on intestinal growth and function, GLP-2 and EGF-containing media (EGF-cm) were administered, alone and in combination, in neonatal piglet models of short bowel syndrome (SBS). Neonatal Landrace-Large White piglets were block randomized to 75% midintestinal [jejunoileal (JI) group] or distal intestinal [jejunocolic (JC) group] resection or sham control, with 7-day infusion of saline (control), intravenous human GLP-2 (11 nmol·kg-1·day-1) alone, enteral EGF-cm (80 µg·kg-1·day-1) alone, or GLP-2 and EGF-cm in combination. Adaptation was assessed by intestinal length, histopathology, Üssing chamber analysis, and real-time quantitative PCR of intestinal growth factors. Combined EGF-cm and GLP-2 treatment increased intestinal length in all three surgical models (P < 0.01). EGF-cm alone selectively increased bowel weight per length and jejunal villus height in the JI group only. The JC group demonstrated increased intestinal weight and villus height (P < 0.01) when given either GLP-2 alone or in combination with EGF-cm, with no effect of EGF-cm alone. Jejunal permeability of mannitol and polyethylene glycol decreased with combination therapy in both SBS groups (P < 0.05). No difference was observed in fat absorption or body weight gain. IGF-1 mRNA was differentially expressed in JI vs. JC piglets with treatment. Combined treatment with GLP-2 and EGF-cm induced intestinal lengthening and decreased permeability, in addition to the trophic effects of GLP-2 alone. Our findings demonstrate the benefits of novel combination GLP-2 and EGF treatment for neonatal SBS, especially in the JC model representing most human infants with SBS.NEW & NOTEWORTHY Glucagon-like peptide-2 (GLP-2) and epidermal growth factor (EGF) are intestinotrophic, with demonstrated benefit in both animal models and human studies of short bowel syndrome (SBS). The current research shows that over and above known trophic effects, the combination of GLP-2 and EGF synergistically lengthens the bowel in neonatal piglet models of SBS. Most notable benefit occurred with resection of the terminal ileum, the common clinical anatomy seen in neonatal SBS and associated with least de novo lengthening postsurgery.

CD44 and TLR4 mediate hyaluronic acid regulation of Lgr5+ stem cell proliferation, crypt fission, and intestinal growth in postnatal and adult mice.

Hyaluronic acid, a glycosaminoglycan in the extracellular matrix, binds to CD44 and Toll-like receptor 4 (TLR4). We previously addressed the role of hyaluronic acid in small intestinal and colonic growth in mice. We addressed the role of exogenous hyaluronic acid by giving hyaluronic acid intraperitoneally and the role of endogenous hyaluronic acid by giving PEP-1, a peptide that blocks hyaluronic acid binding to its receptors. Exogenous hyaluronic acid increased epithelial proliferation but had no effect on intestinal length. PEP-1 resulted in a shortened small intestine and colon and diminished epithelial proliferation. In the current study, we sought to determine whether the effects of hyaluronic acid on growth were mediated by signaling through CD44 or TLR4 by giving exogenous hyaluronic acid or PEP-1 twice a week from 3-8 wk of age to wild-type, CD44(-/-), and TLR4(-/-) mice. These studies demonstrated that signaling through both CD44 and TLR4 were important in mediating the effects of hyaluronic acid on growth in the small intestine and colon. Extending our studies to early postnatal life, we assessed the effects of exogenous hyaluronic acid and PEP-1 on Lgr5(+) stem cell proliferation and crypt fission. Administration of PEP-1 to Lgr5(+) reporter mice from postnatal day 7 to day 14 decreased Lgr5(+) cell proliferation and decreased crypt fission. These studies indicate that endogenous hyaluronic acid increases Lgr5(+) stem cell proliferation, crypt fission, and intestinal lengthening and that these effects are dependent on signaling through CD44 and TLR4.

Impacts of maternal selenium supply and nutritional plane on visceral tissues and intestinal biology in 180-day-old offspring in sheep.

Objectives were to investigate the effects of maternal Se supply and nutritional plane during gestation on offspring visceral tissues and indices of intestinal growth, vascularity, and function at 180 d of age. Rambouillet ewe lambs (n = 82, approximately 240 d of age; 52 ± 0.8 kg BW at breeding) were allocated to a 2 × 3 factorial arrangement of treatments. Treatments included dietary Se [adequate Se (ASe, 9.5 µg/kg BW) or high Se (HSe, 81.8 µg/kg BW)] initiated at breeding and nutritional plane [60% (restricted, RES), 100% (control, CON), and 140% (high, HI) of requirements] initiated at d 50 of gestation. Ewes were fed pelleted diets and housed individually indoors. At parturition, lambs were immediately removed and fed artificial colostrum for the first 20 h followed by ad libitum access to milk replacer. At 180 ± 2 d of age, lambs were euthanized and tissues were harvested. Birth weight was affected by nutritional treatments (P < 0.001), with decreased birth weight in RES and HI compared with CON. Offspring from RES and HI ewes had decreased (P = 0.07) blood volume compared with CON, and those born to HSe ewes had increased (P < 0.04) total visceral adiposity. Within offspring from CON ewes, those from HSe ewes had greater (P < 0.02) intestinal mass compared with ASe ewes. Within offspring from HSe ewes, both RES and HI had reduced (P ≤ 0.05) intestinal mass compared with CON. Jejunal capillary area density was greater (P = 0.08) in offspring from ewes fed HSe compared with ASe. In addition, area per capillary was greater (P ≤ 0.09) in CON compared with RES. Maternal nutritional plane tended (P ≤ 0.11) to alter total small intestinal vascularity, with lambs from CON being greater than RES. Expression of most mRNA for measured angiogenic factors and receptors was not altered (P ≤ 0.13) by maternal treatments; however, expression of glucagon-like peptide-2 (GLP-2) was decreased (P = 0.07) in offspring from RES compared with CON ewes. Offspring from ewes fed HI diets had increased (P = 0.08) jejunal mucosal maltase activity. In conclusion, maternal Se supply and nutritional plane during gestation resulted in measurable changes in offspring visceral tissues and intestinal biology, including perirenal fat, blood volume, intestinal mass, total jejunal crypt cell proliferation, area per capillary in jejunal villi, GLP-2 mRNA expression, and maltase activity at 180 d. Additional work is needed to determine impacts on intestinal function and nutrient uptake.