Enhanced growth of small bowel in transgenic mice overexpressing bovine growth hormone

Effects of hormones on intestinal stem cells

The maintenance of intestinal renewal and repair mainly depends on intestinal stem cells (ISCs), which can also contribute to the growth of intestinal tumours. Hormones, which are vital signalling agents in the body, have various effects on the growth and replacement of intestinal stem cells. This review summarises recent progress in the identification of hormones associated with intestinal stem cells. Several hormones, including thyroid hormone, glucagon-like peptide-2, androgens, insulin, leptin, growth hormone, corticotropin-releasing hormone and progastrin, promote the development of intestinal stem cells. However, somatostatin and melatonin are two hormones that prevent the proliferation of intestinal stem cells. Therefore, new therapeutic targets for the diagnosis and treatment of intestinal illnesses can be identified by examining the impact of hormones on intestinal stem cells.

Growth hormone alters gross anatomy and morphology of the small and large intestines in age- and sex-dependent manners

PURPOSE

Growth hormone (GH) has an important role in intestinal barrier function, and abnormalities in GH action have been associated with intestinal complications. Yet, the impact of altered GH on intestinal gross anatomy and morphology remains unclear.

METHODS

This study investigated the influence of GH signaling on gross anatomy, morphology, and fibrosis by characterizing the small and large intestines in male and female bovine growth hormone transgenic (bGH) mice and GH receptor gene-disrupted (GHR-/-) mice at multiple timepoints.

RESULTS

The length, weight, and circumference of the small and large intestines were increased in bGH mice and decreased in GHR-/- mice across all ages. Colon circumference was significantly increased in bGH mice in a sex-dependent manner while significantly decreased in male GHR-/- mice. Villus height, crypt depth, and muscle thickness of the small intestine were generally increased in bGH mice and decreased in GHR-/- mice compared to controls with age- and sex-dependent exceptions. Colonic crypt depth and muscle thickness in bGH and GHR-/- mice were significantly altered in an age- and sex-dependent manner. Fibrosis was increased in the small intestine of bGH males at 4 months of age, but no significant differences were seen between genotypes at other timepoints.

CONCLUSION

This study observed notable opposing findings in the intestinal phenotype between mouse lines with GH action positively associated with intestinal gross anatomy (i.e. length, weight, and circumference). Moreover, GH action appears to alter morphology of the small and large intestines in an age- and sex-dependent manner.

Growth Hormone Overexpression Induces Hyperphagia and Intestinal Morphophysiological Adaptations to Improve Nutrient Uptake in Zebrafish

The excess of circulating growth hormone (GH) in most transgenic animals implies mandatory growth resulting in higher metabolic demand. Considering that the intestine is the main organ responsible for the digestion, absorption, and direction of dietary nutrients to other tissues, this study aimed to investigate the mechanisms by which gh overexpression modulates the intestine to support higher growth. For this purpose, we designed an 8-weeks feeding trial to evaluate growth parameters, feed intake, and intestinal morphometric indices in the adult gh-transgenic zebrafish (Danio rerio) model. To access the sensitivity of the intestine to the excess of circulating GH, the messenger RNA (mRNA) expression of intestine GH receptors (GHRs) (ghra and ghrb) was analyzed. In addition, the expression of insulin-like growth factor 1a (igf1a) and genes encoding for di and tripeptide transporters (pept1a and pept1b) were assessed. Gh-transgenic zebrafish had better growth performance and higher feed intake compared to non-transgenic sibling controls. Chronic excess of GH upregulates the expression of its cognate receptor (ghrb) and the main growth factor related to trophic effects in the intestine (igf1a). Moreover, transgenic zebrafish showed an increased intestinal absorptive area and higher expression of crucial genes related to the absorption of products from meal protein degradation. These results reinforce the ability of GH to modulate intestinal morphology and the mechanisms of assimilation of nutrients to sustain the energy demand for the continuous growth induced by the excess of circulating GH.

Bovine Colostrum: Its Constituents and Uses

Colostrum is the milk produced during the first few days after birth and contains high levels of immunoglobulins, antimicrobial peptides, and growth factors. Colostrum is important for supporting the growth, development, and immunologic defence of neonates. Colostrum is naturally packaged in a combination that helps prevent its destruction and maintain bioactivity until it reaches more distal gut regions and enables synergistic responses between protective and reparative agents present within it. Bovine colostrum been used for hundreds of years as a traditional or complementary therapy for a wide variety of ailments and in veterinary practice. Partly due to concerns about the side effects of standard Western medicines, there is interest in the use of natural-based products of which colostrum is a prime example. Numerous preclinical and clinical studies have demonstrated therapeutic benefits of bovine colostrum for a wide range of indications, including maintenance of wellbeing, treatment of medical conditions and for animal husbandry. Articles within this Special Issue of Nutrients cover the effects and use bovine colostrum and in this introductory article, we describe the main constituents, quality control and an overview of the use of bovine colostrum in health and disease.

Site-Specific and Temporal Effects of Apraglutide, a Novel Long-Acting Glucagon-Like Peptide-2 Receptor Agonist, on Intestinal Growth in Mice

Long-acting glucagon-like peptide-2 receptor (GLP-2R) agonists are well-established to increase intestinal growth in rodents and, most notably, humans with short bowel syndrome. Most of the trophic effects of GLP-2R agonists are reported to be mediated through increased growth of the crypt-villus axis, resulting in enhanced mucosal mass and improved intestinal function. The present study examined the effects of apraglutide, a novel GLP-2R agonist, on the growth of the small intestine and colon after 3, 7, and 10 weeks of treatment in male and female mice. Apraglutide (3 mg/kg; three times per week) significantly increased small intestinal weight (P < 0.001) and length (P < 0.001) after 3 weeks of administration, with a further increase in effectiveness after 10 weeks (P < 0.01). Crypt depth and villus height were both markedly increased after 3 weeks of apraglutide administration (P < 0.001) but did not show any further increase with duration of treatment, whereas crypt number and intestinal circumference were increased after 7 and 10 weeks (P < 0.01) but not after 3 weeks of apraglutide treatment. Both the weight and the length of the colon were also enhanced by apraglutide treatment for 3 weeks (P < 0.001), and these effects were maintained but did not improve further with continued apraglutide administration. The results of this study demonstrate that the novel, long-acting GLP-2R agonist, apraglutide, demonstrates an unexpected marked ability to increase intestinal length as well as exert time- and location-dependent specificity in its intestinotrophic actions. SIGNIFICANCE STATEMENT: The novel long-acting glucagon-like peptide 2 receptor agonist, apraglutide, enhances intestinal weight as well as intestinal length in a time- and site-dependent fashion.

Dietary milk fat globule membrane supplementation during late gestation increased the growth of neonatal piglets by improving their plasma parameters, intestinal barriers, and fecal microbiota

Maternal supplementation of MFGM transgenerationally improves the intestinal microecology and growth performance of their neonatal piglets.

Influence of Growth Hormone and Glutamine on Intestinal Stem Cells: A Narrative Review

Growth hormone (GH) and glutamine (Gln) stimulate the growth of the intestinal mucosa. GH activates the proliferation of intestinal stem cells (ISCs), enhances the formation of crypt organoids, increases ISC stemness markers in the intestinal organoids, and drives the differentiation of ISCs into Paneth cells and enterocytes. Gln enhances the proliferation of ISCs and increases crypt organoid formation; however, it mainly acts on the post-proliferation activity of ISCs to maintain the stability of crypt organoids and the intestinal mucosa, as well as to stimulate the differentiation of ISCs into goblet cells and possibly Paneth cells and enteroendocrine cells. Since GH and Gln have differential effects on ISCs. Their use in combination may have synergistic effects on ISCs. In this review, we summarize the evidence of the actions of GH and/or Gln on crypt cells and ISCs in the literature. Overall, most studies demonstrated that GH and Gln in combination exerted synergistic effects to activate the proliferation of crypt cells and ISCs and enhance crypt organoid formation and mucosal growth. This treatment influenced the proliferation of ISCs to a similar degree as GH treatment alone and the differentiation of ISCs to a similar degree as Gln treatment alone.

Characterization of an intestine-specific GH receptor knockout (IntGHRKO) mouse

OBJECTIVE

Growth hormone (GH) has been reported to enhance the intestinal barrier; as such, recombinant GH has been administered for several intestinal diseases. However, excess GH action has been implicated in increasing the risk of intestinal dysfunction. The goal of this study was to examine the direct effects of GH on the small and large intestines to clarify the role GH plays in intestinal function through the use of a mouse model.

DESIGN

An intestinal epithelial-specific GH receptor (GHR) knockout (IntGHRKO) mouse line was generated using Cre-lox with the villin promoter driving Cre expression. The generated mice were characterized with respect to growth and intestinal phenotypes.

RESULTS

IntGHRKO mice showed no significant changes in body length, weight, or composition compared to floxed controls. Male IntGHRKO mice had significantly shorter large intestines at 4 and 12 months of age. Intestinal barrier function was assessed by measuring the expression of tight junction related genes, as well as levels of serum endotoxin and fecal albumin. Results showed sex differences as males had an increase in occludin levels but normal serum endotoxin and fecal albumin; while, females had changes in fecal albumin levels with normal occludin and serum endotoxin. Evaluation of glucose tolerance and fat absorption also showed sex differences as females were glucose intolerant, while males had impaired fat absorption. Histopathology revealed a trend towards decreased villus height in males, which could explain the sex difference in glucose homeostasis.

CONCLUSIONS

Overall, the data demonstrate that disruption of GH on the intestinal epithelial cells modestly affects the intestinal gross anatomy, morphology, and function in a sex-specific manner.

Distinct Effects of Growth Hormone and Glutamine on Activation of Intestinal Stem Cells

BACKGROUND

For patients with short bowel syndrome under parenteral nutrition support, growth hormone (GH) and glutamine (GLN) have been found to help the growth of intestinal mucosa. In this research, we studied the effects of GH and GLN on intestinal stem cells (ISCs).

METHODS

The in vitro and in vivo effects of GH and/or GLN on ISCs were evaluated by observing the ability of ISCs to form organoids in a Matrigel culture system. The expression levels of stemness and differentiation markers in ISCs and organoids were assessed using quantitative real-time polymerase chain reaction, immunofluorescence assay, and immunohistochemistry staining.

RESULTS

In vitro administration of GH activated the stemness of ISCs, whereas GLN enhanced the expression of chromogranin A and Muc2, which are differentiation markers in enteroendocrine and goblet cells, respectively. Administration of GH or GLN in mice showed that GH, but not GLN, upregulated the proliferative activity of ISCs with increased formation of crypt organoids. In addition, GH increased the expression of Lgr5 and GLN enhanced expression of Muc2 in the crypt fractions of the intestines in mice.

CONCLUSION

These results suggest that GH mainly enhances proliferative activities, whereas GLN promotes the differentiation potential of ISCs.

Transcriptome analysis of food habit transition from carnivory to herbivory in a typical vertebrate herbivore, grass carp Ctenopharyngodon idella

BACKGROUND

Although feeding behavior and food habit are ecologically and economically important properties, little is known about formation and evolution of herbivory. Grass carp (Ctenopharyngodon idella) is an ecologically appealing model of vertebrate herbivore, widely cultivated in the world as edible fish or as biological control agents for aquatic weeds. Grass carp exhibits food habit transition from carnivory to herbivory during development. However, currently little is known about the genes regulating the unique food habit transition and the formation of herbivory, and how they could achieve higher growth rates on plant materials, which have a relatively poor nutritional quality.

RESULTS

We showed that grass carp fed with duckweed (modeling fish after food habit transition) had significantly higher relative length of gut than fish before food habit transition or those fed with chironomid larvae (fish without transition). Using transcriptome sequencing, we identified 10,184 differentially expressed genes between grass carp before and after transition in brain, liver and gut. By eliminating genes potentially involved in development (via comparing fish with or without food habit transition), we identified changes in expression of genes involved in cell proliferation and differentiation, appetite control, circadian rhythm, and digestion and metabolism between fish before and after food habit transition. Up-regulation of GHRb, Egfr, Fgf, Fgfbp1, Insra, Irs2, Jak, STAT, PKC, PI3K expression in fish fed with duckweed, consistent with faster gut growth, could promote the food habit transition. Grass carp after food habit transition had increased appetite signal in brain. Altered expressions of Per, Cry, Clock, Bmal2, Pdp, Dec and Fbxl3 might reset circadian phase of fish after food habit transition. Expression of genes involved in digestion and metabolism were significantly different between fish before and after the transition.

CONCLUSIONS

We suggest that the food habit transition from carnivory to herbivory in grass carp might be due to enhanced gut growth, increased appetite, resetting of circadian phase and enhanced digestion and metabolism. We also found extensive alternative splicing and novel transcript accompanying food habit transition. These differences together might account for the food habit transition and the formation of herbivory in grass carp.

Growth hormone for intestinal adaptation in patients with short bowel syndrome: systematic review and meta-analysis of randomized controlled trials

OBJECTIVES

The purpose of this systematic review was to assess the efficacy of growth hormone (GH) treatment in patients with short bowel syndrome (SBS).

METHODS

Electronic searches were performed to identify all publications describing randomized controlled trials (RCTs) on the use of GH with or without glutamine for the treatment of patients with SBS. The outcomes of interest were body weight, lean body mass, and intestinal absorption function.

RESULTS

Four trials involving 70 patients were included in the review. A meta-analysis of these trials suggested that GH had a positive effect in terms of increased weight (mean difference [MD] = 1.66; 95% CI, 0.69-2.63, P < 0.001), lean body mass (MD = 1.93; 95% CI, 0.97-2.90; P < 0.001), energy absorption (MD = 4.42; 95% CI, 0.26-8.58; P = 0.04), nitrogen absorption (MD = 4.85; 95% CI, 0.20-9.49; P = 0.04), and fat absorption (MD = 5.02; 95% CI, 0.21-9.82; P = 0.04) for patients with SBS. Adverse effects occurred during active treatment in all trials. Only 1 trial included a 12-week follow-up study.

CONCLUSIONS

The results suggest a possible short-term benefit in terms of body weight, lean body mass, and absorptive capacities; however, no conclusion of long-term efficacy of GH could be obtained. Large-scale, long-term follow-up RCTs are needed to confirm the efficacy and tolerability of GH in the future.

CANDIDATE GENES FOR LIMITING CHOLESTATIC INTESTINAL INJURY IDENTIFIED BY GENE EXPRESSION PROFILING

The lack of bile flow from the liver into the intestine can have devastating complications including hepatic failure, sepsis and even death. This pathologic condition known as cholestasis can result from etiologies as diverse as total parenteral nutrition (TPN), hepatitis and pancreatic cancer. The intestinal injury associated with cholestasis has been shown to result in decreased intestinal resistance, increased bacterial translocation and increased endotoxemia. Anecdotal clinical evidence suggests a genetic predisposition to exaggerated injury. Recent animal research on two different strains of inbred mice demonstrating different rates of bacterial translocation with different mortality rates supports this premise. In this study, a microarray analysis of intestinal tissue following common bile duct ligation (CBDL) performed under general anesthesia on these same two strains of inbred mice was done with the goal of identifying the potential molecular mechanistic pathways responsible. Over 500 genes were increased more than 2.0 fold following CBDL. The most promising candidate genes included MUPs, Serpina1a and LCN-2. RT-PCR validated the microarray results for these candidate genes. In an in vitro experiment using differentiated intestinal epithelial cells, inhibition of MUP-1 by siRNA resulted in increased intestinal epithelial cell permeability. Diverse novel mechanisms involving the growth hormone pathway, the acute phase response and the innate immune response are thus potential avenues for limiting cholestatic intestinal injury. Changes in gene expression were at times found to be not only due to the CBDL but also due to the murine strain. Should further studies in cholestatic patients demonstrate inter-individual variability similar to what we have shown in mice, then a "personalized medicine" approach to cholestatic patients may become possible.

Mice overexpressing CD97 in intestinal epithelial cells provide a unique model for mammalian postnatal intestinal cylindrical growth

Postnatal enlargement of the mammalian intestine comprises cylindrical and luminal growth, associated with crypt fission and crypt/villus hyperplasia, respectively, which subsequently predominate before and after weaning. The bipartite adhesion G protein-coupled receptor CD97 shows an expression gradient along the crypt-villus axis in the normal human intestine. We here report that transgenic mice overexpressing CD97 in intestinal epithelial cells develop an upper megaintestine. Intestinal enlargement involves an increase in length and diameter but does not affect microscopic morphology, as typical for cylindrical growth. The megaintestine is acquired after birth and before weaning, independent of the genotype of the mother, excluding altered availability of milk constituents as driving factor. CD97 overexpression does not regulate intestinal growth factors, stem cell markers, and Wnt signaling, which contribute to epithelial differentiation and renewal, nor does it affect suckling-to-weaning transition. Consistent with augmented cylindrical growth, suckling but not adult transgenic mice show enlarged crypts and thus more crypt fissions caused by a transient increase of the crypt transit-amplifying zone. Intestinal enlargement by CD97 requires its seven-span transmembrane/cytoplasmic C-terminal fragment but not the N-terminal fragment binding partner CD55. In summary, ectopic expression of CD97 in intestinal epithelial cells provides a unique model for intestinal cylindrical growth occurring in breast-fed infants.

The role of growth factors in intestinal regeneration and repair in necrotizing enterocolitis

Necrotizing enterocolitis (NEC) is a devastating intestinal disease resulting in major neonatal morbidity and mortality. The pathology is poorly understood, and the means of preventing and treating NEC are limited. Several endogenous growth factors have been identified as having important roles in intestinal growth as well as aiding intestinal repair from injury or inflammation. In this review, we will discuss several growth factors as mediators of intestinal regeneration and repair as well as potential therapeutic agents for NEC.

Insulin-like growth factors in the gastrointestinal tract and liver

The liver is a major source of insulin-like growth factors (IGFs) and IGF binding proteins (IGFBPs) that are present in the circulation and have important endocrine activities relating to energy metabolism, body size, carcinogenesis, and various organ-specific functions. Although IGFs have only minor effects on the normal liver itself, production of IGFs and IGFBPs in a tissue-specific manner in the gastrointestinal tract exert important regulatory effects on cellular proliferation, survival, and apoptosis. IGFs and IGFBPs play important regulatory roles in the response of both the liver and the gastrointestinal tract to inflammation and in the development of neoplasia.

Growth hormone to improve short bowel syndrome intestinal autonomy: a pediatric randomized open-label clinical trial

BACKGROUND

The ability of growth hormone (GH) to promote the weaning-off of parenteral nutrition (PN) in short bowel syndrome (SBS) is unclear. No randomized controlled study is available in children. This study was undertaken to determine if GH could enhance the weaning off of PN in PN-dependent children with SBS.

METHODS

A prospective randomized open-label multicenter study was performed in 14 patients (mean age, 9 ± 1.4 years) with SBS (average small bowel length, 33 cm) and long-term PN dependency (8 years) on an unrestricted diet. A standardized PN decrease with and without GH (0.14 mg/kg/d) was conducted. The patients were randomized to either a GH group (4 months of GH) or a control (CTR) group (4 months without GH, followed by 4 months with GH). Blood tests and a nutrition assessment of enteral and parenteral intakes were performed. Groups were compared with the Wilcoxon test.

RESULTS

Treatment with GH did not improve the weaning off of PN (decrease in PN caloric intake of 32.5% ± 9.6% in the GH group vs 35.2% ± 8.7% in the CTR group, nonsignificant). In the CTR group, GH treatment induced an additional but not statistically significant decrease of 8.8% ± 12.4% in daily calories. Parenteral needs returned to near basal rates 6 months after GH discontinuation (GH: 77.6% ± 10.6% vs CTR: 73.2% ± 7.4%). Weight decreased slightly in both groups. No biological parameters varied significantly.

CONCLUSIONS

GH did not improve the weaning off of PN in PN-dependent children with SBS.

Growth hormone upregulates intestinal trefoil factor expression in the ileum of rats after γ-radiation

Growth hormone (GH) and intestinal trefoil factor (ITF) have been involved in intestinal protection and repair. This study investigates the effects of GH administration on ITF expression and histological changes associated with tissue injury in an intestinal rat model of radiation. Adult male rats were divided into four groups: control, GH, radiation and radiation + GH (GHyRAD). Ileum samples were obtained at 2 or 72 h after radiation and processed to determine ITF levels (mRNA and protein) by quantitative polymerase chain reaction, Western blot and immunohistochemistry. In addition, goblet ITF-positive cells were identified by immunohistochemistry at 72 h. Our results showed an upregulation of mRNA and protein production of ITF in ileum samples after GH and radiation + GH compared with control and irradiated samples. Irradiation alone affected ITF protein expression. However, irradiation after GH pretreatment produced the highest ITF mRNA and protein levels at both the tested time points. ITF-producing goblet cells were identified in intestinal villi (apical location). GH treatment increased the number of ITF-producing goblet cells, and radiation after GH treatment displayed further increase in the number of ITF-positive goblet cells. GH upregulates ITF in normal intestinal tissue. This upregulation is higher when radiation is given after GH treatment. Nevertheless, the mechanism by which GH regulates ITF expression remains unclear and is still under investigation. These results could open up new avenues in the therapeutic reparative and protective effects of GH during radiotherapy and chemotherapy.

Effect of recombinant human growth hormone on intestinal absorption and body composition in children with short bowel syndrome

This prospective study aimed to establish the effect of recombinant human growth hormone (rhGH) on intestinal function in children with short bowel syndrome (SBS). Eight children with neonatal SBS were included. All were dependent on parenteral nutrition (PN) for >3 years (range, 3.8-11.6 years), with PN providing >50% of recommended dietary allowance for age (range, 50%-65%). The subjects received rhGH (Humatrope) 0.13 mg/kg/d subcutaneously over a 12-week period. The follow-up was continued over a 12-month period after rhGH discontinuation. Clinical and biological assessments were performed at baseline, at the end of the treatment period, and 12 months after the end of treatment. No side effects related to rhGH were observed. PN requirements were decreased in all children during the course of rhGH treatment. Between baseline and the end of treatment, significant increases were observed in concentrations (mean ± standard deviation) of serum insulin-like growth factor 1 (103.1 ± 49.9 µg/L vs 153.5 ± 82.2 µg/L; P < .01), serum insulin-like growth factor-binding protein 3 (1.7 ± 0.6 mg/L vs 2.5 ± 0.9 mg/L; P < .001), and plasma citrulline (16.5 ± 14.8 µmol/L vs 25.2 ± 18.3 µmol/L; P < .05). A median 54% increase in enteral intake (range, 10%-244%) was observed (P < .001) and net energy balance improved significantly (P < .002). It was necessary for 6 children to be maintained on PN or restarted after discontinuation of rhGH treatment, and they remained on PN until the end of the follow-up period. A 12-week high-dose rhGH treatment allowed patients to decrease PN, but only 2 patients could be definitively weaned from PN. Indications and cost-effectiveness of rhGH treatment for SBS pediatric patients need further evaluation.

Can we protect the gut in critical illness? The role of growth factors and other novel approaches

The intestine plays a central role in the pathophysiology of critical illness and is frequently called the "motor" of the systemic inflammatory response. Perturbations to the intestinal barrier can lead to distant organ damage and multiple organ failure. Therefore, identifying ways to preserve intestinal integrity may be of paramount importance. Growth factors and other peptides have emerged as potential tools for modulation of intestinal inflammation and repair due to their roles in cellular proliferation, differentiation, migration, and survival. This review examines the involvement of growth factors and other peptides in intestinal epithelial repair during critical illness and their potential use as therapeutic targets.

Human milk proteins: an interactomics and updated functional overview

Milk and milk fractions are characterized by a wide array of proteins, whose concentration spans across several orders of magnitude. By exploiting a combined approach based on functional gene ontology enrichment (FatiGO/Babelomics), hierarchical clustering, and pathway and network analyses, we merged data from literature dealing with protein-oriented studies on human milk. A total of 285 entries defined a nonredundant list upon comparison with the Ingenuity Knowledge Base from the Ingenuity Pathway Analysis software. Results were compared with an inventory of bovine milk proteins gathered from dedicated proteomic studies. A protein core of 106 proteins was found, with most of the entries associated to three main biological functions, namely nutrient transport/lipid metabolism, concretization of the immune system response and cellular proliferation processes. Our analyses confirm and emphasize that the biological role of the human milk proteins is not only limited to the provision of external nutrients and defense molecules against pathogens to the suckling but also to the direct stimulation of the growth of neonate tissues/organs and to the development of a proper independent immune system, both through the induction of a number of molecular cascades associated with cell proliferation/differentiation. The latter aspects were previously investigated by single-molecule dedicated studies, missing the holistic view that results from our analysis.

Human growth hormone and glutamine for patients with short bowel syndrome

BACKGROUND

There has been clinical enthusiasm for treating short bowel patients with human recombinant growth hormone and/or glutamine in hopes of reducing parenteral nutrition dependency. It has been more than a decade since Byrne and colleagues reported enhanced absorption of nutrients, improved weight gain, and reduction in parenteral nutrition requirements with the administration of a combination of human growth hormone (HGH) and glutamine in patients with short bowel syndrome. Other studies have reported inconsistent results.

OBJECTIVES

The purpose of this systematic review was to evaluate the efficacy of growth hormone with or without glutamine supplementation for adult patients with short bowel syndrome.

SEARCH STRATEGY

Electronic searches were performed to identify all publications describing randomised controlled trials of the use of human growth hormone with or without glutamine for the treatment of patients with short bowel syndrome.

SELECTION CRITERIA

Randomised controlled trials of human growth hormone with or without glutamine for patients with short bowel syndrome were considered for inclusion.

DATA COLLECTION AND ANALYSIS

Two authors independently extracted data from the published studies. The statistical analyses were performed using RevMan 5 software. Follmann's method was used for cross-over studies.

MAIN RESULTS

Five studies were included in the review. Human growth hormone with or without glutamine appears to provide benefit in terms of increased weight (MD 1.66 Kg; 95% CI 0.69 to 2.63;P = 0.0008), lean body mass (MD 1.93 Kg; 95% CI 0.97 to 2.90; P = 0.0001) energy absorption (MD 4.42 Kcal; 95% CI 0.26 to 8.58; P = 0.04) and nitrogen absorption (MD 44.85 g; 95%CI 0.20 to 9.49; P = 0.04) for patients with short bowel syndrome. The single RCT that focused on parenteral nutrition (PN) requirements demonstrated decreased PN volume and calories and number of infusions in patients who received HGH with or without glutamine supplementation. Only patients who received HGH with glutamine maintained statistically significant PN reductions at 3 month follow-up.

AUTHORS' CONCLUSIONS

The results suggest a positive effect of human growth hormone on weight gain and energy absorption. However, in the majority of trials, the effects are short-lived returning to baseline shortly after cessation of therapy. The temporary benefit calls into question the clinical utility of this treatment. To date, the evidence is inconclusive to recommend this therapy. Consideration should be made to studying patients during the active phase of intestinal adaptation rather than in the setting of chronic intestinal failure. The role of HGH in paediatric short bowel syndrome remains unknown.

The influence of nutrients, biliary-pancreatic secretions, and systemic trophic hormones on intestinal adaptation in a Roux-en-Y bypass model

PURPOSE

The signals that govern the upregulation of nutrient absorption (adaptation) after intestinal resection are not well understood. A Gastric Roux-en-Y bypass (GRYB) model was used to isolate the relative contributions of direct mucosal stimulation by nutrients, biliary-pancreatic secretions, and systemic enteric hormones on intestinal adaptation in short bowel syndrome.

METHODS

Male rats (350-400 g; n = 8/group) underwent sham or GRYB with pair feeding and were observed for 14 days. Weight and serum hormonal levels (glucagon-like peptide-2 [GLP-2], PYY) were quantified. Adaptation was assessed by intestinal morphology and crypt cell kinetics in each intestinal limb of the bypass and the equivalent points in the sham intestine. Mucosal growth factors and expression of transporter proteins were measured in each limb of the model.

RESULTS

The GRYB animals lost weight compared to controls and exhibited significant adaptive changes with increased bowel width, villus height, crypt depth, and proliferation indices in the alimentary and common intestinal limbs. Although the biliary limb did not adapt at the mucosa, it did show an increased bowel width and crypt cell proliferation rate. The bypass animals had elevated levels of systemic PYY and GLP-2. At the mucosal level, insulin-like growth factor-1 (IGF-1) and basic fibroblast growth factor (bFGF) increased in all limbs of the bypass animals, whereas keratinocyte growth factor (KGF) and epidermal growth factor (EGF) had variable responses. The expression of the passive transporter of glucose, GLUT-2, expression was increased, whereas GLUT-5 was unchanged in all limbs of the bypass groups. Expression of the active mucosal transporter of glucose, SGLT-1 was decreased in the alimentary limb.

CONCLUSIONS

Adaptation occurred maximally in intestinal segments stimulated by nutrients. Partial adaptation in the biliary limb may reflect the effects of systemic hormones. Mucosal content of IGF-1, bFGF, and EGF appear to be stimulated by systemic hormones, potentially GLP-2, whereas KGF may be locally regulated. Further studies to examine the relationships between the factors controlling nutrient-induced adaptation are suggested. Direct contact with nutrients appears to be the most potent factor in inducing mucosal adaptation.

Reduced colonic apoptosis in mice overexpressing bovine growth hormone occurs through changes in several kinase pathways

OBJECTIVE

Growth hormone (GH) has antiapoptotic effects in several cell lines, including human colonic adenocarcinoma cells. In addition, it has been reported that patients with acromegaly have reduced apoptosis in colonic mucosa. The aim of the study was to investigate colonic apoptosis and underlying molecular mechanisms in transgenic mice overexpressing bovine GH (Acro) aged 3 months (young) or 9 months (elder).

DESIGN AND METHODS

Apoptosis in colonic epithelial cells was evaluated by TUNEL and Annexin V; expression of pro- and anti-apoptotic proteins was assessed by Western blot. GH action was blocked treating Acro with a selective GH receptor antagonist.

RESULTS

Young and elder Acro had lower colonic apoptosis [driven by GH through p38, p44/42 and PI3 kinase pathways], than littermate controls; changes were abolished by treating Acro with a selective GH receptor antagonist. The effects of GH were consistent with an anti-apoptotic phenotype (reduced cytosolic cytochrome-c, Bad and Bax and increased Bcl-2, and Bcl-XL level) leading to lower activation of caspase-9 and caspase-3. Changes in apoptotic proteins reversed after treatment with a GH receptor antagonist, suggesting a direct effect of GH. In addition, antiapoptotic phenotype of Acro had a protective role against doxorubicin-induced apoptosis.

CONCLUSIONS

Our results suggest that GH leads to increased and reduced levels of anti- and pro-apoptotic proteins, respectively, lowering apoptosis in either young or elder transgenic animals through activation of several kinase pathways.

Management strategies for infants with total intestinal aganglionosis

PURPOSE

This study investigated appropriate management strategies for infants with total intestinal aganglionosis (TIA), focusing on surgical and medical managements.

METHODS

Six infants with TIA or near TIA treated in our institution between 1980 and 2007 were reviewed retrospectively. Surgery was performed as a simple jejunostomy, 65 to 70 cm below the ligament of Treitz (LOT) in 2 infants, and 30 cm below LOT in 1 without extended myectomy-myotomy (EMM). Jejunostomy with EMM 30 to 35 cm below LOT were performed in 3.

RESULTS

Two infants with jejunostomy 65 cm or 70 cm distal from LOT died of sepsis at 7 months and 8 months of age, respectively. One infant with jejunostomy 30 cm from LOT without EMM died of cholestatic liver failure at the age of 1 year and 8 months. To date, the remaining 3 infants with jejunostomy 30 cm or 35 cm distal from LOT in addition to EMM have survived 10 years, 3 years and 10 months, and 2 years of age, respectively. Nutritional managements such as parenteral nutrition with 80 to 100 kcal/kg/day and oral feeding with elemental diet (ED) were preferable to reduce the occurrence of enteritis, sepsis, and cholestatic liver dysfunction.

CONCLUSION

A good combination of cyclic parenteral nutrition and oral intake with elemental diet after short proximal jejunostomy with EMM may be a key for the survival of infants with TIA. In addition, in infants whose absorptive function was not ameliorated by EMM, medical management such as GH administration might be worth trying.

Changes in the expression of suppressor of cytokine signalling (SOCS) 2 in the colonic mucosa of acromegalic patients are associated with hyperplastic polyps

BACKGROUND

Acromegalic patients have increased prevalence of colonic polyps. Development of hyperplastic polyps was related to suppressor of cytokine signalling (SOCS) 2 haploinsufficiency in animal models of acromegaly.

OBJECTIVE AND PATIENTS

To evaluate whether variations in SOCS2 expression in the colonic mucosa of acromegalic patients might be associated to hyperplastic polyps, patients with active acromegaly or disease in remission with or without hyperplastic polyps were studied; controls were non-acromegalic subjects age- and sex- matched with or without polyps.

MEASUREMENTS

Expression of SOCS1-3 was evaluated by RT-PCR, immunofluorescence and Western blot in the colonic mucosa. Coimmunoprecipatiton was used to evaluate multimeric protein complexes.

RESULTS

Acromegalic patients with active disease and hyperplastic polyps had higher levels of SOCS2 transcripts; on the contrary, SOCS1 and SOCS3 transcripts did not differ among the study groups. While the expression of SOCS2 and SOCS3 protein was indistinguishable with that of the corresponding transcripts, SOCS1 protein expression was reduced in active acromegalic patients with polyps. SOCS1 protein was reduced owing to its increased proteasome degradation mediated by SOCS2. The increased SOCS2 and reduced SOCS1 led to increased STAT5b expression, suggesting a higher GH signalling transduction.

CONCLUSIONS

Acromegalic patients with active disease and hyperplastic polyps have high levels of SOCS2 and increased SOCS1 degradation, leading to reduced negative feedback on GH signalling, likely favouring a hyperplastic polyps phenotype.

Morphological, kinetic, membrane biochemical and genetic aspects of intestinal enteroplasticity

The process of intestinal adaptation (“enteroplasticity”) is complex and multifaceted. Although a number of trophic nutrients and non-nutritive factors have been identified in animal studies, successful, reproducible clinical trials in humans are awaited. Understanding mechanisms underlying this adaptive process may direct research toward strategies that maximize intestinal function and impart a true clinical benefit to patients with short bowel syndrome, or to persons in whom nutrient absorption needs to be maximized. In this review, we consider the morphological, kinetic and membrane biochemical aspects of enteroplasticity, focus on the importance of nutritional factors, provide an overview of the many hormones that may alter the adaptive process, and consider some of the possible molecular profiles. While most of the data is derived from rodent studies, wherever possible, the results of human studies of intestinal enteroplasticity are provided.

Acromegaly: re-thinking the cancer risk

Acromegaly is characterized by sustained elevation of circulating growth hormone (GH) and insulin-like growth factor I (IGF-I), and is clearly associated with increased morbidity and overall mortality mainly due to cardiovascular, metabolic, and respiratory diseases. Although cancer-related mortality varies widely amongst retroperspective studies, it appears to be consistently elevated mainly in patients with uncontrolled disease. We review individual tumor types including neoplasms of the colon, breast, prostate, and thyroid where in vitro, animal studies, and studies in non-acromegalic cancer patients have established a role for the GH/IGF-I axis in tumor progression and possibly initiation. We highlight deficiencies in data in acromegalic patients where the evidence is less convincing. Instead, we explore the hypothesis that acromegaly, independent of hormone secretion, is a disease that heralds genetic and/or epigenetic alterations predisposing to cancer risk elsewhere.

Glucagon-like peptide-2 activates beta-catenin signaling in the mouse intestinal crypt: role of insulin-like growth factor-I

Chronic administration of glucagon-like peptide-2 (GLP-2) induces intestinal growth and crypt cell proliferation through an indirect mechanism requiring IGF-I. However, the intracellular pathways through which IGF-I mediates GLP-2-induced epithelial tropic signaling remain undefined. Because beta-catenin and Akt are important regulators of crypt cell proliferation, we hypothesized that GLP-2 activates these signaling pathways through an IGF-I-dependent mechanism. In this study, fasted mice were administered Gly(2)-GLP-2 or LR(3)-IGF-I (positive control) for 0.5-4 h. Nuclear translocation of beta-catenin in non-Paneth crypt cells was assessed by immunohistochemistry and expression of its downstream proliferative markers, c-myc and Sox9, by quantitative RT-PCR. Akt phosphorylation and activation of its targets, glycogen synthase kinase-3beta and caspase-3, were determined by Western blot. IGF-I receptor (IGF-IR) and IGF-I signaling were blocked by preadministration of NVP-AEW541 and through the use of IGF-I knockout mice, respectively. We found that GLP-2 increased beta-catenin nuclear translocation in non-Paneth crypt cells by 72 +/- 17% (P < 0.05) and increased mucosal c-myc and Sox9 mRNA expression by 90 +/- 20 and 376 +/- 170%, respectively (P < 0.05-0.01), with similar results observed with IGF-I. This effect of GLP-2 was prevented by blocking the IGF-IR as well as ablation of IGF-I signaling. GLP-2 also produced a time- and dose-dependent activation of Akt in the intestinal mucosa (P < 0.01), most notably in the epithelium. This action was reduced by IGF-IR inhibition but not IGF-I knockout. We concluded that acute administration of GLP-2 activates beta-catenin and proliferative signaling in non-Paneth murine intestinal crypt cells as well as Akt signaling in the mucosa. However, IGF-I is required only for the GLP-2-induced alterations in beta-catenin.

Cell-specific effects of insulin receptor substrate-1 deficiency on normal and IGF-I-mediated colon growth

Insulin-like growth factor I (IGF-I) potently stimulates intestinal growth. Insulin receptor substrate-1 (IRS-1) mediates proliferative and antiapoptotic actions of IGF-I in cell lines, but its in vivo relevance in intestine is not defined. This study tested the hypothesis that there is cell type-specific dependence on IRS-1 as a mediator of IGF-I action. Length, mass, crypt cell proliferation, and apoptosis were measured in small intestine and colon of IRS-1-null mice and wild-type (WT) littermates and in colon of IRS-1-null or WT mice expressing IGF-I transgenes. Expression of IGF-I receptor and signaling intermediates was examined in intestine of WT and IRS-1-null mice, cultured intestinal epithelial cells, and myofibroblasts. Absolute IRS-1 deficiency reduced mucosal mass in jejunum and colon, but effects were more pronounced in colon. Muscularis mass was decreased in both segments. In IGF-I transgenics, IRS-1 deficiency significantly attenuated IGF-I-stimulated growth of colonic mucosa and abolished antiapoptotic but not mitogenic effects of IGF-I transgene on crypt cells. IGF-I-induced muscularis growth was unaffected by IRS-1 deficiency. In intestinal epithelial cells, IRS-1 was expressed at higher levels than IRS-2 and was preferentially activated by IGF-I. In contrast, IGF-I activated both IRS-1 and IRS-2 in intestinal myofibroblasts and IRS-2 activation was upregulated in IRS-1-null myofibroblasts. We conclude that the intestinal epithelium but not the muscularis requires IRS-1 for normal trophic actions of IGF-I and that IRS-1 is required for antiapoptotic but not mitogenic effects of IGF-I in the intestinal crypts in vivo.

Suppressor of cytokine signaling 3 (SOCS3) limits damage-induced crypt hyper-proliferation and inflammation-associated tumorigenesis in the colon

Intestinal injury or chronic inflammation induce cytokines that promote crypt regeneration and mucosal repair. If excessive or prolonged, such mechanisms may increase colon cancer risk. Factors that terminate or limit cytokine action in intestinal epithelial cells (IEC) may protect against crypt hyperplasia and neoplasia. We hypothesized that suppressor of cytokine signaling-3 (SOCS3) is such a factor. Mice with Vilin-promoter/Cre-recombinase (VC)-mediated IEC-specific SOCS3 gene disruption (VC/HO), WT/HO littermates with floxed but intact SOCS3 genes and VC/WT mice were studied. Colon was examined after acute dextran sodium sulfate (DSS)-induced mucosal injury or after azoxymethane (AOM) and chronic DSS. Signaling pathways were examined in colon, cultured IEC or colon cancer cell lines. VC/HO mice showed no basal phenotype. After acute DSS, VC/HO exhibited enhanced crypt proliferation and crypt hyperplasia and reduced transforming growth factor (TGF) beta expression in colon. Inflammation and mucosal damage were similar across genotypes. Following AOM/DSS, VC/HO mice had increased size, number and load of colonic tumors and increased STAT3 and nuclear factor-kappa B (NF-kappaB) activation in colon. In vitro, SOCS3 overexpression reduced proliferation, IL-6-mediated STAT3 activation and tumor necrosis factor (TNF) alpha-mediated NF-kappaB activation. We conclude that cytokine induction of SOCS3 normally provides an intrinsic mechanism to limit injury-induced crypt hyperproliferation and inflammation-associated colon cancer by regulating both STAT3 and NF-kappaB pathways.

Suppressor of cytokine signaling-2 limits intestinal growth and enterotrophic actions of IGF-I in vivo

Suppressors of cytokine signaling (SOCS) typically limit cytokine receptor signaling via the JAK-STAT pathway. Considerable evidence demonstrates that SOCS2 limits growth hormone (GH) action on body and organ growth. Biochemical evidence that SOCS2 binds to the IGF-I receptor (IGF-IR) supports the novel possibility that SOCS2 limits IGF-I action. The current study tested the hypothesis that SOCS2 normally limits basal or IGF-I-induced intestinal growth and limits IGF-IR signaling in intestinal epithelial cells. Intestinal growth was assessed in mice homozygous for SOCS2 gene deletion (SOCS2 null) and wild-type (WT) littermates at different ages and in response to infused IGF-I or vehicle or EGF and vehicle. The effects of SOCS2 on IGF-IR signaling were examined in ex vivo cultures of SOCS2 null and WT intestine and Caco-2 cells. Compared with WT, SOCS2 null mice showed significantly enhanced small intestine and colon growth, mucosal mass, and crypt cell proliferation and decreases in radiation-induced crypt apoptosis in jejunum. SOCS2 null mice showed significantly greater growth responses to IGF-I in small intestine and colon. IGF-I-stimulated activation of IGF-IR and downstream signaling intermediates were enhanced in the intestine of SOCS2 null mice and were decreased by SOCS2 overexpression in Caco-2 cells. SOCS2 bound directly to the endogenous IGF-IR in Caco-2 cells. The intestine of SOCS2 null mice also showed enhanced growth responses to infused EGF. We conclude that SOCS2 normally limits basal and IGF-I- and EGF-induced intestinal growth in vivo and has novel inhibitory effects on the IGF-IR tyrosine kinase pathway in intestinal epithelial cells.

Intestinal mucosal adaptation

Intestinal failure is a condition characterized by malnutrition and/or dehydration as a result of the inadequate digestion and absorption of nutrients. The most common cause of intestinal failure is short bowel syndrome, which occurs when the functional gut mass is reduced below the level necessary for adequate nutrient and water absorption. This condition may be congenital, or may be acquired as a result of a massive resection of the small bowel. Following resection, the intestine is capable of adaptation in response to enteral nutrients as well as other trophic stimuli. Identifying factors that may enhance the process of intestinal adaptation is an exciting area of research with important potential clinical applications.

The essential role of insulin-like growth factor-1 in the intestinal tropic effects of glucagon-like peptide-2 in mice

BACKGROUND & AIMS

Glucagon-like peptide-2 (GLP-2) is an intestinal hormone that acts through unknown pathways to induce intestinal growth. We investigated the role of the insulin-like growth factors (IGF-1 and IGF-2) as mediators of GLP-2-enhanced growth in the murine intestine.

METHODS

IGF-1 expression and secretion were determined in GLP-2-responsive primary intestinal cultures treated with GLP-2. Parameters of intestinal growth were assessed in wild-type (CD1, Igf1(+/+) and Igf2+), heterozygous (Igf1(+/-)), and null (Igf1(-/-) and Igf2(-P)) mice treated chronically with saline, GLP-2, IGF-1, or R-Spondin1.

RESULTS

GLP-2 increased IGF-1 messenger RNA expression and IGF-1 secretion in intestinal cultures and increased expression of IGF-1 messenger RNA in mouse small intestine in vivo. Igf1(+/+) and Igf2+ mice responded to .1 microg/g(-1) per day(-1) GLP-2 with increased intestinal weights, morphometric parameters, and proliferative indices. In contrast, Igf1(-/-) mice were unresponsive to the same dose of GLP-2, failing to demonstrate changes in intestinal weight, morphometry, or proliferation. However, a significant effect of 1 microg/g(-1) per day(-1) GLP-2 was observed in Igf1(-/-) mice, but only in terms of small intestinal weight when normalized for body weight. Furthermore, Igf2(-P) mice demonstrated a partially impaired response in terms of small intestinal growth. Both Igf1(-/-) and Igf2(-P) mice exhibited normal-enhanced intestinal growth in response to IGF-1 and/or R-Spondin1.

CONCLUSIONS

GLP-2 enhances intestinal IGF-1 expression and secretion, and IGF-1 is required for small and large intestinal growth in response to GLP-2. These findings identify IGF-1 as an essential mediator of the intestinotropic actions of GLP-2.

Strategies for parenteral nutrition weaning in adult patients with short bowel syndrome

The development of parenteral nutrition (PN) was an important, life-saving advance in the care of patients with short bowel syndrome (SBS). Nevertheless, its long-term use is often associated with complications. Therefore, it is desirable, when possible, to wean SBS patients to an oral diet. Given the complexity of PN weaning and the lack of published guidelines, the purpose of this article is to describe strategies of PN weaning and illustrate important clinical considerations during the weaning process. Patient education and motivation are key factors in successful PN weaning. The patient should have clearly defined care protocols and understand the importance of each aspect of the weaning program. Other factors likely to influence weaning success include the length and health of the remnant bowel, the presence of a colon, and the degree to which bowel adaptation has occurred. It is imperative that daily oral fluid and caloric intake goals are met prior to initiating PN weaning and that the patient receives an optimized dietary and medication plan. During weaning, the most practical measures for assessing adequate hydration and nutritional status are oral intake, stool and urine output, serum electrolytes and visceral proteins, and body weight. PN reductions can be made by either decreasing the days of PN infusion per week or decreasing the PN infusion volume equally across all days of the week. Use of recombinant human growth hormone, with or without glutamine, may play a role in facilitating the PN weaning process.

Haplotype insufficiency for suppressor of cytokine signaling-2 enhances intestinal growth and promotes polyp formation in growth hormone-transgenic mice

GH may improve intestinal growth or function in patients with short bowel syndrome. Excessive trophic effects of GH or IGF-I may contribute to neoplastic growth or increased colorectal cancer risk in acromegaly. Identification of mechanisms that limit the tumorigenic potential of GH and IGF-I is desirable. Suppressor of cytokine signaling-2 (SOCS2) limits GH action on body and organ growth, but its role in GH action on intestine is unknown. We tested the hypothesis that SOCS2 limits GH-induced intestinal growth or neoplasia in vivo. GH-transgenic (GH-TG) mice were crossed with SOCS2 null mice to generate wild-type (WT) or transgenic (TG) mice with zero (HO-WT; HO-TG), one (HT-WT; HT-TG), or two (WT-WT; WT-TG) functional SOCS2 genes. No HO-TG mice were derived from crossbreeding. WT-WT, HT-WT, WT-TG, and HT-TG were compared. Body weight, small intestine and colon growth, and levels of jejunal IGF-I and sucrase-isomaltase mRNAs were assessed. Colon was analyzed for abnormal lesions. HT-WT did not differ from WT-WT. Compared with WT-TG, HT-TG had significantly increased body weight, small intestine growth, and local IGF-I expression and decreased sucrase-isomaltase expression. HT-TG colon spontaneously developed multiple hyperplastic and lymphoid polyps. GH-induced activation of STAT5 DNA binding activity was enhanced in intestine of SOCS2 null mice compared with WT control. Haplotype insufficiency for SOCS2 promotes trophic actions of GH in small intestine and promotes preneoplastic growth in colon during excess GH. Small variations in SOCS2 expression levels may significantly influence the outcome of therapeutic GH or acromegaly in intestine.

Epidermal growth factor and/or growth hormone induce differential, side-specific signal transduction protein phosphorylation in enterocytes

BACKGROUND

Epidermal growth factor (EGF) plus growth hormone (GH) enhances luminal glutamine transport into rabbit and human intestinal cells. Our objective was to screen for activation status of signal proteins in C2(BBe)1 cells (enterocyte-like cell line) in response to side-specific EGF or GH treatment and to investigate the dependence of EGF receptor (EGFR) phosphorylation status on its tyrosine kinase.

METHODS

C2(BBe)1 cells on Transwells were treated for 15 minutes on either the basolateral or apical-side with EGF or GH. Lysates underwent Kinetworks phospho site-screen-2.1 analysis (duplicate experiments). In addition, lysates from cells treated as above with or without tyrphostin AG1478 (a specific EGFR tyrosine kinase inhibitor) underwent Western blot analysis for total EGFR and EGFR phosphorylated on tyrosine 1173, 1086 or 1068 (4-7 experiments).

RESULTS

Kinetworks phospho-screening demonstrated a broad range of interactions dependent on both side of exposure and protein studied. From this screen, it appears that ErbB2, Met, and insulin receptor (R)/insulin-like growth factor 1 R are not involved in the growth factors signals. For EGFR phosphorylation, basolateral, but not apical, EGF was a strong activator. Synergism was seen, but only with apical EGF plus basolateral GH. All EGFR phosphorylations were EGFR tyrosine kinase dependent. In contradistinction, apical EGF phosphorylated FAK and MAPKs.

CONCLUSIONS

Kinetworks phosphoprotein screens can suggest pathways involved in side-specific and synergistic interaction between EGF and GH. For EGFR, synergism by EGF + GH was noticed only with Ap EGF plus Bl GH and was EGFR tyrosine kinase dependent. Adaptive intestinal responses due to enterally administrated EGF might be accelerated by the availability of parenteral GH.

[Example of safety measures for antineoplastic agents immediately after market launch--a case of TS-1 capsule all example use result investigation that executes safety monitoring--]

As a measure to ensure safe use of TS-1 during the early marketing period, a drug use investigation was conducted on an all-case basis. Extra safety monitoring,rarely included in the use investigation,was also planned for patients who began therapy with this agent. Of the 4,177 subjects registered during the year beginning in March 1999, 3,882 started TS-1 therapy. Aside from 74 dropouts, 3,808 cases were evaluable for safety. The overall incidence of adverse reactions, with high frequencies of myelosuppression and gastrointestinal disorders, was 74.3%: a result similar to an incidence of 77.5% (100/129) found in the early phase II trial with gastric cancer patients. Safety monitoring made it possible to check if a given patients was eligible for proper use before treatment is begun. During TS-1 administration,collaboration was formed between physicians and medical representatives to ensure regular laboratory testing and to check the test findings. Measures were considered necessary to secure the safe use of drugs with manifest risk of serious adverse reactions, such as antineoplastic agents, during the initial period of market introduction. Our present approach proved effective as one of such measures.

Growth hormone, glutamine, and an optimal diet reduces parenteral nutrition in patients with short bowel syndrome: a prospective, randomized, placebo-controlled, double-blind clinical trial

OBJECTIVE

To determine if growth hormone (GH) and glutamine (Gln) might allow for a reduction in parenteral nutrition (PN) in individuals with short bowel syndrome.

BACKGROUND DATA

Following massive intestinal resection, patients frequently sustain severe nutrient malabsorption and are dependent on PN for life. GH treatment with or without Gln might allow for a reduction in PN.

METHODS

A prospective, double-blind, randomized, placebo-controlled clinical trial performed in 41 adults dependent on PN. Following screening, patients were admitted to an in-house facility for 6 weeks. After 2 weeks of stabilization and dietary optimization, patients were randomized to one of 3 treatment arms (1:2:2 ratio): oral Gln (30 g/day) + GH placebo (control group, n = 9), Gln placebo + GH (0.1 mg/kg per day, n = 16), or Gln + GH (n = 16). Standard criteria based on clinical and laboratory measurements were followed to determine PN volume and content. After 4 weeks of treatment, patients were discharged and monitored; GH and GH placebo were discontinued, but the diet with Gln or Gln placebo was continued for 3 months.

RESULTS

Patients receiving GH + Gln placebo + diet showed greater reductions in PN volume (5.9 +/- 3.8 L/wk, mean +/- SD), PN calories (4338 +/- 1858 calories/wk), and PN infusions (3 +/- 2 infusions/wk) than corresponding reductions in the Gln + diet group (3.8 +/- 2.4 L/wk; 2633 +/- 1341 calories/wk; 2 +/- 1 infusions/wk, P < 0.05). Patients who received GH + Gln + diet showed the greatest reductions (7.7 +/- 3.2 L/wk; 5751 +/- 2082 calories/wk; 4 +/- 1 infusions/wk, P < 0.001 versus Gln + diet). At the 3-month follow-up, only patients who had received GH + Gln + diet maintained significant reductions in PN (P < 0.005) compared with the Gln + diet.

CONCLUSIONS

Treatment with GH + diet or GH + Gln + diet initially permitted significantly more weaning from PN than Gln + diet. Only subjects receiving GH + Gln + diet maintained this effect for at least 3 months.

Growth hormone inhibits signal transducer and activator of transcription 3 activation and reduces disease activity in murine colitis

BACKGROUND & AIMS

Constitutive signal transducer and activator of transcription (STAT) 3 activation promotes chronic inflammation and epithelial proliferation in murine colitis and human inflammatory bowel disease. SHP-2, through binding to the glycoprotein 130 signaling receptor, negatively regulates STAT3 activation. Growth hormone reduces disease activity and promotes mucosal healing in colitis and can activate SHP-2.

METHODS

We hypothesized that growth hormone administration would reduce disease activity in experimental colitis and that this would involve modulation of SHP-2/glycoprotein 130 association and STAT3 activation.

RESULTS

Growth hormone administration improved weight gain and colon histology in interleukin 10-null mice with colitis. Growth hormone reduced apoptosis and increased proliferation of crypt epithelial cells while increasing apoptosis of lamina propria mononuclear cells. Growth hormone increased SHP-2/glycoprotein 130 association and reduced colonic STAT3 activation in interleukin 10-null mice and in biopsy samples from patients with Crohn's colitis. Expression of the antiapoptotic protein bcl-2 was increased in crypt epithelial cells after growth hormone treatment. Growth hormone increased SHP-2/glycoprotein 130 binding and reduced interleukin 6-dependent STAT3 activation in the T84 human colon carcinoma and Jurkat human T-cell leukemia lines.

CONCLUSIONS

Growth hormone administration improves weight gain and reduces disease activity in interleukin 10-null mice with colitis. The improvement in disease activity is associated with increased SHP-2/glycoprotein 130 binding and reduced STAT3 activation in both murine and Crohn's colitis. Growth hormone may be a useful therapy in inflammatory bowel disease, in terms of both improving anabolic metabolism and enhancing mucosal healing.

The effect of growth hormone on gut mucosal homeostasis and cellular mediators after severe trauma

BACKGROUND

Gut mucosal integrity and function is impaired after severe trauma with associated increases in small bowel epithelial cell apoptosis and decreases in cell proliferation. Growth hormone improves gastrointestinal function during chemotherapy and has anabolic effects on protein synthesis. The purpose of this study was to determine whether growth hormone can improve small bowel homeostasis after injury and by which cellular mechanisms these changes occur.

MATERIALS AND METHODS

Rats were pair-fed, given a thermal trauma, and received saline (n = 28) or GH (2.5 mg/kg every 24 h, n = 28). Small intestine and serum were taken at 1, 2, 5, and 7 days after injury. Measures were mucosal apoptosis, proliferation, villous morphology, apoptotic, and proliferative mediators, such as Caspases-3, -8, Fas and Fas-Ligand, Bcl-2, and Bcl-x. In addition serum cytokines were determined.

RESULTS

Gut epithelial cell apoptosis and proliferation were increased in both groups after the thermal injury (P < 0.05). GH had neither an effect on small bowel epithelial cell apoptosis or proliferation, nor dependent cellular mediators after thermal injury. However, GH significantly improved villous morphology (height and cell number) when compared with controls (P < 0.05). RhGH was found to significantly increase serum TNF-alpha compared to controls (P < 0.05).

CONCLUSION

Growth hormone improves small bowel homeostasis after severe trauma independent from small bowel epithelial cell apoptosis or proliferation, probably by increasing the life span.

Relative expression and localization of the insulin-like growth factor system components in the fetal, child and adult intestine

BACKGROUND

The insulin-like growth factors (IGFs) are important in the development and maintenance of the gastrointestinal tract.

OBJECTIVES

To compare the expression of IGFs and their receptors in the stomach and duodenum of the fetus, the child and the adult. To identify the cells mainly responsible for the production of the members of the IGF system.

METHODS

Tissue was obtained from fetus after abortion and from children and adults during diagnostic endoscopy and biopsy. The expression of the IGFs and their receptors was estimated by an RNAse protection assay and sections were stained with antisera to the components of IGF system.

RESULTS

The tissues from the stomach and the duodenum expressed the two IGFs and their receptors at all stages of life. The fetal IGF receptors I and II, were approximately ten times higher than in the child and IGF-II was five times higher. Immunohistochemical staining showed the components of the IGF system to be localized to the gastric glands and to the basotlateral border of the gastric epithelial cells. In the duodenum, they were concentrated at the apical portion of the epithelial tissue. They could also be identified in ganglion cells and nerves.

CONCLUSIONS

The IGFs and their receptors in the stomach and duodenum are expressed in all age groups and mostly are highest in the fetus. The IGF system proteins were located in the gastric glands and epithelium and in the apical portion of the villous epithelium of the duodenum.

Growth factors in inflammatory bowel disease: the actions and interactions of growth hormone and insulin-like growth factor-I

Multiple growth hormones (GHs) and factors are relevant to inflammatory bowel disease (IBD) due to their trophic effects on epithelial cells to promote mucosal integrity, renewal, and repair, on mesenchymal cells to promote wound healing, and on intestinal immune cells to modulate inflammation. The anabolic effects of GHs and factors outside the intestine are relevant to minimizing nutritional insufficiency, catabolic state, and the inability to maintain body weight due to inflammation-induced malabsorption. GHs and factors can, however, have a dual role, whereby trophic effects can be beneficial but, if excessive, can promote complications including the increased risk of intestinal tumors/adenocarcinoma and fibrosis. This review focuses on GH and insulin-like growth factor (IGF-I), for which evidence suggests such a dual role may exist. The actions of GH and IGF-I on the healthy intestine are compared with effects during intestinal inflammation or associated complications. Interactions between these growth factors and others relevant to IBD are considered. The role of the newly discovered suppressors of cytokine signaling proteins, which may dictate the balance between beneficial and excessive actions of GH and IGF-I, is also addressed.

Suppressor of cytokine signaling-2: a growth hormone-inducible inhibitor of intestinal epithelial cell proliferation

BACKGROUND & AIMS

Growth hormone (GH) and insulin-like growth factor-I (IGF-I) increase intestinal growth. GH is thought to act indirectly via IGF-I. In several models, including rats given total parenteral nutrition (TPN), IGF-I more potently stimulates mucosal growth than GH, even when GH induces similar circulating IGF-I levels. These studies test the hypothesis that GH induces a suppressor of cytokine signaling (SOCS), which inhibits intestinal epithelial cell (IEC) proliferation.

METHODS

Rats on TPN received vehicle, GH, or IGF-I. Jejunal SOCS (SOCS-1, -2, -3, and cytokine-inducible SH2-domain-containing protein [CIS]) and IGF-I messenger RNA (mRNA) were quantified. Caco-2, IEC-6 cells, and SOCS-2 null and wild-type (WT) mice were used to examine the expression and functional role of SOCS-2.

RESULTS

As reported previously, IGF-I, but not GH, prevented mucosal atrophy during TPN, although GH elevated plasma IGF-I and increased body weight. GH, but not IGF-I, induced jejunal SOCS-2 mRNA. SOCS-2 mRNA levels in GH and IGF-I-treated rats inversely correlated with mucosal weight. SOCS-2 is expressed in Caco-2 cells, and elevated SOCS-2 expression in postconfluent cells is associated with reduced proliferative rates. SOCS-2 overexpression in Caco-2 cells inhibited cell proliferation and promoted differentiation. In IEC-6 cells, GH induced SOCS-2 and reduced basal or IGF-I-induced proliferation. GH also reduced proliferative activity in isolated crypts from WT but not SOCS-2 null mice, and SOCS-2 null crypts showed enhanced proliferative responses to GH and IGF-I. SOCS-2 null mice have increased intestinal weight and length.

CONCLUSIONS

SOCS-2 is a GH-inducible, novel inhibitor of intestinal epithelial cell proliferation and intestinal growth.

Growth hormone inhibits apoptosis in human colonic cancer cell lines: antagonistic effects of peroxisome proliferator activated receptor-gamma ligands

GH has antiapoptotic effects on several cells. However, the antiapoptotic mechanisms of GH on colonic mucosa cells are not completely understood. Peroxisome proliferator activated receptor-gamma (PPARgamma) activation enhances apoptosis, and a link between GH and PPARgamma in the colonic epithelium of acromegalic patients has been suggested. We investigated the effects of GH and of PPARgamma ligands on apoptosis in colonic cancer cell lines. Colonic cells showed specific binding sites for GH, and after exposure to 0.05-50 nm GH, their apoptosis reduced by 45%. The antiapoptotic effect was due to either GH directly or GH-dependent local production of IGF-1. A 55-85% reduction of PPARgamma expression was observed in GH-treated cells, compared with controls (P < 0.05). However, treatment of the cells with 1-50 microm ciglitazone (cig), induced apoptosis and reverted the antiapoptotic effects of GH by increasing the programmed cell death up to 3.5-fold at 30 min and up to 1.7-fold at 24 h. Expression of Bcl-2 and TNF-related apoptosis-induced ligand was not affected by either GH or cig treatment, whereas GH reduced the expression of Bax, which was increased by cig treatment. In addition, GH increased the expression of signal transducer and activator of transcription 5b, which might be involved in the down-regulation of PPARgamma expression. In conclusion, GH may exert a direct antiapoptotic effect on colonic cells, through an increased expression of signal transducer and activator of transcription 5b and a reduction of Bax and PPARgamma. The reduced GH-dependent apoptosis can be overcome by PPARgamma ligands, which might be useful chemopreventive agents in acromegalic patients, who have an increased colonic polyps prevalence.

Irreversible intestinal failure

Intestinal failure (IF) can be defined as the reduction of functional gut mass below the minimal amount necessary for digestion and absorption adequate to satisfy the nutrient and fluid requirements for maintenance in adults or growth in children. In developed countries, IF mainly includes individuals with the congenital or early onset of conditions requiring protracted or indefinite parenteral nutrition (PN). Short bowel syndrome was the first commonly recognized cause of protracted IF. The normal physiologic process of intestinal adaptation after extensive resection usually allows for recovery of sufficient intestinal function within weeks to months. During this time, patients can be sustained on parenteral nutrition. Only a few children have permanent intestinal insufficiency and life-long dependency on PN. Non-transplant surgery including small bowel tapering and lengthening may allow weaning from PN in some cases. Hormonal therapy with recombinant human growth hormone has produced poor results while therapy with glucagon-like peptide-2 holds promise. Congenital diseases of enterocyte development such as microvillus inclusion disease or intestinal epithelial dysplasia cause permanent IF for which no curative medical treatment is currently available. Severe and extensive motility disorders such as total or subtotal intestinal aganglionosis (long segment Hirschsprung disease) or chronic intestinal pseudo-obstruction syndrome may also cause permanent IF. PN and home-PN remain are the mainstays of therapy regardless of the cause of IF. Some patients develop complications while receiving long-term PN for IF especially catheter related complications (thrombosis, sepsis) and liver disease. These patients may be candidates for intestinal transplantation. This review discusses the causes of irreversible IF and emphasizes the specific medico-surgical strategies for prevention and treatment of these conditions at several stages of IF.

Postreceptor resistance to exogenous growth hormone exists in the jejunal mucosa of parenterally fed rats

Our objective was to determine whether the intestinal mucosa is resistant to the mitogenic effects of exogenous growth hormone (GH) but sensitive to exogenous insulin-like growth factor-I (IGF-I) during total parenteral nutrition (TPN) because of decreased GH receptor (GHR) binding or postreceptor responsiveness to GH. First, only continuous i.v. administration of IGF-I, but neither pulsatile subcutaneous nor continuous i.v. GH, stimulated jejunal mucosal hyperplasia; however, both GH and IGF-I increased serum IGF-I and promoted similar whole-body growth after 8 d of exclusive TPN and 6 d of growth factor treatment in rats. This suggests a tissue-specific resistance to GH action in the intestinal mucosa during TPN. Second, exogenous GH during TPN did not reduce GH-specific binding in jejunum, suggesting that the inability of GH to stimulate mucosal hyperplasia is not due to low levels of the GHR. Third, IGF-I, but not GH, induced acute expression of c-fos (P < 0.009) and c-jun (P = 0.053) mRNAs in jejunum based on Northern analysis and in situ hybridization histochemistry 60 min after a single i.v. bolus of GH or IGF-I. This suggests that IGF-I, but not GH, activates early postreceptor growth-related signaling pathways in jejunum. In summary, the lack of early c-fos and c-jun induction in response to GH in TPN rats indicates that the jejunal mucosa is resistant to exogenous GH between GHR activation and induction of immediate early genes. This may contribute to the inability of mucosal cells to respond to the trophic effects of GH.

Adaptation following intestinal resection: mechanisms and signals

The intestine has an inherent ability to adapt morphologically and functionally in response to internal and external environmental changes. The functional adaptations encompass modifications of the brush border membrane fluidity and permeability, as well as up- or down-regulation of carrier-mediated transport. Intestinal adaptation improves the nutritional status following the loss of a major portion of the small intestine, following chronic ingestion of ethanol, following sublethal doses of abdominal irradiation, in diabetes, in pregnancy and lactation, with ageing, and with fasting and malnutrition. Following intestinal resection, morphological and functional changes occur depending upon the extent of the intestine removed, the site studied, and the lipid content of the diet. Therefore, intestinal adaptation has important implications in the survival potential and welfare of the host. An understanding of the mechanisms of, and signals for, intestinal adaptation in the experimental setting forms the basis for the use of management strategies in humans with the short-bowel syndrome.

Indications for specific therapy in the rehabilitation of patients with the short-bowel syndrome

Diarrhoea, malabsorption and malnutrition characterize the short-bowel syndrome. Following the initial intestinal resection, complications such as fistulas and intra-abdominal abscesses may occur, but these usually resolve with appropriate surgical care. All residual intestine should be placed in continuity before serious attempts at rehabilitation with oral feedings are initiated. Small hourly oral feedings composed of food items high in complex carbohydrate and low in fat are started when appropriate and the diet is gradually increased as intestinal adaptation occurs. The goal during this process is to prevent diarrhoea and allow the formation of semiformed stools. With time, parenteral nutrition (PN) can be reduced, and the time required depends on both length of residual bowel and the particular anatomy involved-for example, the presence or absence of the colon. A programme of optimal diet plus growth hormone (0.1 mg/kg) and oral glutamine (30 g/day) enhances the adaptive process and allows many patients independence from PN. However, those with extremely short segments of jejuno-ileum (<50 cm) and no colon have excessive fluid and electrolyte losses, and intestinal transplantation may be the only therapy which allows such patients to be independent of PN.