The effect of recombinant human growth hormone (rhGH) on trinitrobenzene sulfonic acid-induced colitis in rats: an experimental study

Composition of the microbiota in patients with growth hormone deficiency before and after treatment with growth hormone

INTRODUCTION

Growth hormone (GH) and insulin-like growth factor-1 (IGF-1) have modulatory effects on bowel function and its microbiota. Our aim was to investigate whether low levels of GH and IGF-1 in patients with GH deficiency are associated with changes in gut physiology/integrity as well as in the composition of the gut microbiota.

MATERIALS AND METHODS

We conducted a case-control study in 21 patients with GH deficiency, at baseline and after 6 months of GH treatment, and in 20 healthy controls. We analysed changes in anthropometric and laboratory characteristics and bacterial translocation and studied the composition of the microbiome by means of massive 16S rRNA gene sequencing.

RESULTS

Growth hormone deficiency was accompanied by a significant increase in serum levels of sCD14, a marker of bacterial translocation (P < .01). This increase was reversed by GH treatment. We did not find any differences in the composition or α- or β-diversity of the gut microbiota after treatment or between cases and controls.

CONCLUSIONS

Our work is the first to demonstrate that the presence of GH deficiency is not associated with differences in gut microbiota composition in comparison with healthy controls, and changes in microbiota composition are also not found after 6 months of treatment. However, GH deficiency and low IGF-1 levels were associated with an increase in bacterial translocation, which had reversed after treatment.

A Masking Effect: A Case of Initial Presentation of Ulcerative Colitis After Discontinuing Growth Hormone Therapy

Background

The inflammation and repair of the intestinal mucosa in inflammatory bowel disease (IBD) involve a complex interplay between innate, adaptive immune responses, and hormones. This may explain the relapsing clinical course of the disease.

Methods

We present the first reported case of a patient presenting their initial flare of ulcerative colitis immediately after discontinuing growth hormone (GH) therapy, suggesting treatment with GH or growth factors may prevent the development of IBD.

Results

This is a case of a 13-year-old female with a history of GH deficiency, presenting with an 8-week history of abdominal pain, blood-stained diarrhea, and fecal calprotectin greater than 8000 mcg/g, 2 weeks after discontinuing GH therapy. The patient subsequently underwent an esophagoduodenoscopy and colonoscopy with biopsies showing histological features consistent with ulcerative colitis.

Conclusions

The finding of withdrawing GH or growth factors therapy potentially unmasking IBD in this patient raises a question of whether growth factors can inhibit the development of IBD and suggests beneficial effects of treatment with GH or growth factors as adjuvant therapy for IBD.

Deletion of SOCS2 Reduces Post-Colitis Fibrosis via Alteration of the TGFβ Pathway

Inflammatory bowel disease (IBD) is an immunologically mediated chronic intestinal disorder. Growth hormone (GH) administration enhances mucosal repair and decreases intestinal fibrosis in patients with IBD. In the present study, we investigated the effect of cellular sensitivity to GH via suppressor of cytokine signaling 2 (SOCS2) deletion on colitis and recovery. To induce colitis, wild type and SOCS2 knockout (SOCS2−/−) mice were treated with 3% dextran sodium sulphate (DSS), followed by a recovery period. SOCS2−/− mice showed higher disease activity during colitis with increased mRNA expression of the pro-inflammatory cytokines nitric oxide synthase 2 (NOS2) and interleukin 1 β (IL1-β). At recovery time point, SOCS2−/− showed better recovery with less fibrosis measured by levels of α-SMA and collagen deposition. Protein and mRNA expressions of transforming growth factor beta β1 (TGF-β1) receptors were significantly lower in SOCS2−/− mice compared to wild-type littermates. Using an in vivo bromodeoxyuridine (BrdU) proliferation assay, SOCS2−/− mice showed higher intestinal epithelial proliferation compared to wild-type mice. Our results demonstrated that deletion of the SOCS2 protein results in higher growth hormone sensitivity associated with higher pro-inflammatory signaling; however, it resulted in less tissue damage with less fibrotic lesions and higher epithelial proliferation, which are markers of GH-protective effects in IBD. This suggests a pleiotropic effect of SOCS2 and multiple cellular targets. Further study is required to study role of SOCS2 in regulation of TGFβ-mothers against the decapentaplegic homolog (Smad) pathway.

Growth Hormone Resistance-Special Focus on Inflammatory Bowel Disease

Growth hormone (GH) plays major anabolic and catabolic roles in the body and is important for regulating several aspects of growth. During an inflammatory process, cells may develop a state of GH resistance during which their response to GH stimulation is limited. In this review, we will emphasize specific mechanisms governing the formation of GH resistance in the active phase of inflammatory bowel disease. The specific molecular effects mediated through individual inflammatory mediators and processes will be highlighted to provide an overview of the transcriptional, translational and post-translational inflammation-mediated impacts on the GH receptor (GHR) along with the impacts on GH-induced intracellular signaling. We also will review GH’s effects on mucosal healing and immune cells in the context of experimental colitis, human inflammatory bowel disease and in patients with short bowel syndrome.

Growth and the Growth Hormone-Insulin Like Growth Factor 1 Axis in Children With Chronic Inflammation: Current Evidence, Gaps in Knowledge, and Future Directions

Growth failure is frequently encountered in children with chronic inflammatory conditions like juvenile idiopathic arthritis, inflammatory bowel disease, and cystic fibrosis. Delayed puberty and attenuated pubertal growth spurt are often seen during adolescence. The underlying inflammatory state mediated by proinflammatory cytokines, prolonged use of glucocorticoid, and suboptimal nutrition contribute to growth failure and pubertal abnormalities. These factors can impair growth by their effects on the GH-IGF axis and also directly at the level of the growth plate via alterations in chondrogenesis and local growth factor signaling. Recent studies on the impact of cytokines and glucocorticoid on the growth plate further advanced our understanding of growth failure in chronic disease and provided a biological rationale of growth promotion. Targeting cytokines using biological therapy may lead to improvement of growth in some of these children, but approximately one-third continue to grow slowly. There is increasing evidence that the use of relatively high-dose recombinant human GH may lead to partial catch-up growth in chronic inflammatory conditions, although long-term follow-up data are currently limited. In this review, we comprehensively review the growth abnormalities in children with juvenile idiopathic arthritis, inflammatory bowel disease, and cystic fibrosis, systemic abnormalities of the GH-IGF axis, and growth plate perturbations. We also systematically reviewed all the current published studies of recombinant human GH in these conditions and discussed the role of recombinant human IGF-1.

Endocrine therapy for growth retardation in paediatric inflammatory bowel disease

Inflammatory bowel disease, particularly Crohn's disease (CD), can potentially cause growth failure during childhood as well as a reduction in final adult height. The underlying mechanism is multifactorial and includes poor nutrition, chronic inflammation, and the prolonged use of steroids. Despite major advances in the treatment of CD, current cohorts of children continue to display a deficit in linear growth and may qualify for growth-promoting hormonal therapy. However, currently there is limited evidence to support the use of endocrine therapy directed primarily at improving growth. This review is aimed at summarising the current evidence for growth impairment in inflammatory bowel disease and discusses the rationale for using growth promoting therapy.

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.

The role of growth hormone and insulin-like growth factor-1 in Crohn's disease: implications for therapeutic use of human growth hormone in pediatric patients

PURPOSE OF REVIEW

This review evaluates the role of the growth hormone (GH) and insulin-like growth factor (IGF) in influencing linear growth in pediatric Crohn's disease. It also examines the current evidence concerning the use of recombinant human growth hormone (rhGH) as a potential therapy in achieving optimal growth and inducing mucosal healing for pediatric Crohn's disease.

RECENT FINDINGS

Current treatment strategies for Crohn's disease including antitumor necrosis factor-α (TNF-α) therapy have been demonstrated to improve growth velocity, but linear growth deficits persist despite optimization of therapy. By complex mechanisms, including the reduction of levels of IGF-1 and induction of systemic and hepatic GH resistance, cytokines such as TNF-α and interleukin-6 (IL-6), commonly elevated in active Crohn's disease, are important as mediators of linear growth delay. Recent evidence suggests that rhGH therapy is effective in improving short-term linear growth for a selected group of patients but of limited benefit as a therapy for improving mucosal disease and reducing clinical disease activity.

SUMMARY

Crohn's disease interacts with the GH-IGF-1 axis in important ways. Recent studies evaluating rhGH use in pediatric Crohn's disease have demonstrated some efficacy in reversing persistent linear growth delay but limited benefits in terms of improving mucosal disease and clinical disease activity. Larger studies of adequate power are needed to confirm a true benefit in terms of growth, to examine a potential benefit with regard to modification of disease activity, and to evaluate long-term risks.

A preliminary trial of the effect of recombinant human growth hormone on short-term linear growth and glucose homeostasis in children with Crohn's disease

BACKGROUND

It is unclear whether recombinant human growth hormone (rhGH) improves linear growth in children with Crohn's disease (CD).

AIMS

To investigate the effects of rhGH on height velocity (HV) and glucose homeostasis over a 6-month period.

DESIGN AND SETTING

Randomized controlled trial in two tertiary children's hospitals in 22 children with inflammatory bowel disease amongst whom 21 had CD. Duration of disease from diagnosis and number of acute relapses requiring either exclusive enteral nutrition or therapeutic dose of oral prednisolone were similar in the treatment and control groups.

INTERVENTION

Either rhGH (0·067 mg/kg per day) as daily subcutaneous injections (rhGH group; n, 11) or no rhGH, (Ctrl; n, 11) for 6 months.

MAIN OUTCOME MEASURE

Percentage change in HV after 6 months in the two groups. Auxology, puberty, skeletal age, disease factors, treatment and glucose homeostasis were also assessed.

RESULTS

Median HV increased from 4·5 (range, 0·6, 8·9) at baseline to 10·8 (6·1, 15·0) cm/year at 6 month (P = 0·003) in the rhGH group, whereas in the Ctrl group, it was 3·8 (1·4, 6·7) and 3·5 cm/year (2·0, 9·6), respectively (P = 0·58). Median percentage increase in HV after 6 months in the rhGH group was 140% (16·7, 916·7) compared with 17·4% (-42·1%, 97·7%) in the Ctrl group (P < 0·001). There were no significant differences in disease activity and proinflammatory cytokines at baseline and 6 months in both groups and change in bone age for chronological age was also similar in the two groups. In the rhGH group, fasting insulin increased from 4·0 (2·0, 11·0) to 7·0 mU/l (2·0, 16·0) (P = 0·02), whereas in the Ctrl group, it was 3·0 (1·2, 12·7) and 3·8 mU/l (2·1, 7·0) (P = 0·72), respectively.

CONCLUSIONS

Although this pilot trial shows that rhGH can improve short-term linear growth in children with CD, the clinical efficacy of this therapy needs to be further studied in longer-term studies of growth, glucose homeostasis and disease status.

Intestinal growth factors: potential use in the treatment of inflammatory bowel disease and their role in mucosal healing

BACKGROUND

A key feature of inflammatory bowel disease (IBD) is impaired epithelial repair. Human growth factors comprise an array of signaling molecules that lead to ligand-specific signal transduction. Their downstream effects are associated with several cellular functions including epithelial healing in response to injury. Several studies have described specific growth factor deficiencies in patients with IBD, implicating their role in disease pathophysiology. The aim of this review was to describe currently known enterocyte-targeted growth factors, their mechanisms of action, and their potential therapeutic utility.

METHODS

The National Library of Medicine (http://www.pubmed.gov) and meeting abstracts were searched using the following terms: growth factor, intestine, colon, inflammatory bowel disease, Crohn's disease, ulcerative colitis, colitis, animal model, transforming growth factor, bone morphogenetic protein, activins, growth hormone, fibroblast growth factor, epidermal growth factor (EGF), keratinocyte growth factor (KGF), glucagon-like peptide II, granulocyte macrophage colony-stimulating factor (GM-CSF), granulocyte colony-stimulating factor (G-CSF), vascular endothelial growth factor (VEGF) inhibitors, and trefoil factors.

RESULTS

Several growth factors are therapeutic candidates in IBD. Growth hormone, KGF, EGF, teduglutide, GM-CSF/G-CSF have entered early clinical trials, whereas others are currently in preclinical evaluation.

CONCLUSIONS

There are several growth factors responsible for epithelial repair. Preliminary studies using recombinant growth factors seem promising in IBD preclinical and clinical trials.

Improving growth in children with inflammatory bowel disease

BACKGROUND

Growth in children with inflammatory bowel disease (IBD) is affected through a number of mechanisms; controlling disease activity and supporting poor nutritional status are paramount in these patients. Further understanding of the basic mechanisms by which cytokines influence growth will facilitate the development of therapeutic modalities to improve growth.

CONCLUSIONS

Clinical management that addresses growth and puberty in children with IBD should be a partnership between paediatric gastroenterologists and endocrinologists. Well-designed studies of growth-promoting hormonal treatment may answer questions regarding the efficacy and safety of treating growth retardation in the subgroup of patients who continue to fail to grow despite optimal management of their IBD.

Signal transducer and activator of transcription 5b promotes mucosal tolerance in pediatric Crohn's disease and murine colitis

Growth hormone (GH) regulates anabolic metabolism via activation of the STAT5b transcription factor and reduces mucosal inflammation in colitis. Peroxisome proliferator-activated receptor (PPAR) gamma suppresses mucosal inflammation and is regulated by GH through STAT5b. We hypothesized that the GH:STAT5b axis influences susceptibility to colitis via regulation of local PPARgamma abundance. Colon biopsies from children with newly diagnosed Crohn's disease (CD) and controls were exposed to GH in short-term organ culture. Trinitrobenzene sulfonic acid (TNBS) administration was used to induce colitis in STAT5b-deficient mice and wild-type controls, with and without rosiglitazone pretreatment. GH receptor, STAT5b, PPARgamma, and nuclear factor kappaB activation and expression were determined. Epithelial cell GH receptor expression and GH-dependent STAT5b activation and PPARgamma expression were reduced in CD colon. STAT5b-deficient mice exhibited reduced basal PPARgamma nuclear abundance and developed more severe proximal colitis after TNBS administration. This was associated with a significant increase in mucosal nuclear factor kappaB activation at baseline and after TNBS administration. Rosiglitazone ameliorated colitis in wild-type mice but not STAT5b-deficient mice. GH-dependent STAT5b activation is impaired in affected CD colon and contributes to chronic mucosal inflammation via down-regulation of local PPARgamma expression. Therapeutic activation of the GH:STAT5b axis therefore represents a novel target for restoring both normal anabolic metabolism and mucosal tolerance in CD.

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.

Growth hormone reduces the severity of fibrosis associated with chronic intestinal inflammation

BACKGROUND & AIMS

Growth hormone (GH) is used to treat growth delay in children with Crohn's disease and in patients with short-bowel syndrome. GH can increase collagen accumulation in intestinal mesenchymal cells, raising concern that GH therapy could exacerbate fibrosis in patients with Crohn's disease. We tested if GH treatment altered inflammation or fibrosis during chronic, experimental granulomatous enterocolitis.

METHODS

Ileum and cecum of Lewis rats were subserosally injected with peptidoglycan-polysaccharide (PG-APS) or control human serum albumin. At the onset of chronic PG-APS-induced inflammation, rats were administered recombinant human GH or vehicle for 14 days. Fibrosis and inflammation were quantified by gross gut disease scoring, histologic scoring, type I collagen, and cytokine expression in cecum. Abundance and localization of suppressor of cytokine signaling-3 (SOCS-3) messenger RNA and/or protein were determined in cecum. Effect of GH, cytokines, or PG-APS on SOCS-3 synthesis was measured in intestinal myofibroblasts. Myofibroblasts overexpressing SOCS-3 were used to test whether SOCS-3 inhibits collagen accumulation.

RESULTS

In PG-APS-injected rats, GH modestly reduced gross adhesions and mesenteric contractions, cecal fibrosis score, and collagen expression, but had no effect on intestinal inflammation. GH increased SOCS-3 messenger RNA and protein abundance in PG-APS rats and SOCS-3 messenger RNA was localized to the periphery of granulomas. GH in combination with cytokines or PG-APS, but not alone, induced SOCS-3 synthesis in intestinal myofibroblasts. Myofibroblasts overexpressing SOCS-3 showed reduced cytokine-induced collagen accumulation.

CONCLUSIONS

GH modestly reduces intestinal fibrosis associated with chronic experimental enterocolitis and stimulates expression of antifibrogenic SOCS-3, suggesting that GH therapy in inflammatory bowel disease should not exacerbate fibrosis.

Tumor necrosis factor alpha blockade restores growth hormone signaling in murine colitis

BACKGROUND & AIMS

Cytokines including tumor necrosis factor alpha (TNFalpha) may create a state of growth hormone (GH) resistance in Crohn's disease. Anabolic effects of GH are mediated via phosphorylation of the signal transducer and activator of transcription (STAT)5b transcription factor. Although GH resistance in other settings has been linked to a defect in janus kinase-STAT signaling, the molecular basis for GH resistance in colitis was not known. We hypothesized that the GH-induced phosphorylation of STAT5b would be impaired in colitis, and that TNFalpha blockade would restore GH signaling.

METHODS

Growth, body composition, and molecular regulators of GH signaling were determined in interleukin-10 null mice with chronic colitis and wild-type controls, +/- treatment with an anti-TNFalpha antibody.

RESULTS

Interleukin-10 null mice exhibited significant alterations in growth, body composition, and feed efficiency. Liver insulin-like growth factor 1 expression was reduced in colitic mice. This was associated with down-regulation of GH receptor (GHR) expression and impaired GH-dependent STAT5b activation. Down-regulation of GHR expression was associated with reduced nuclear abundance and DNA binding of the GHR gene-promoter transactivator, Sp3. TNFalpha down-regulated GHR abundance and prevented GH-induced tyrosine phosphorylation of STAT5 in rat hepatocytes in culture. TNFalpha neutralization up-regulated liver GHR abundance and restored GH activation of STAT5 and serum insulin-like growth factor 1 levels in colitic mice; this preceded improvements in weight gain and disease activity.

CONCLUSIONS

GH resistance in experimental colitis is caused by down-regulation of GHR expression, thereby reducing GH-dependent STAT5 activation. TNFalpha blockade restores liver GH signaling and improves anabolic metabolism in this setting.