Trophic effects of biosynthetic growth hormone on normal and defunctioned left colon in rats

GH-IGF-1 Axis in Children with Cystic Fibrosis

OBJECTIVE

To verify whether growth hormone receptor (GHR) gene expression plays a role in growth of children with cystic fibrosis (CF), as a consequence of the chronic inflammatory condition and malnutrition.

DESIGN

We enrolled 49 prepubertal patients (24 males and 25 females) affected by CF in a stable clinical condition, 19 of whom had been diagnosed through newborn screening and 30 following presentation of symptoms. Patients had no significant comorbidity affecting growth or cystic fibrosis transmembrane conductance regulator (CFTR)-related diabetes requiring insulin therapy. Blood was collected during two follow-up visits to measure insulin-like growth factor (IGF-I), growth hormone-binding protein (GHBP), and GHR gene expression. Recruited as a control group were 52 healthy children, sex- and age-matched, were recruited as a control group.

METHODS

We compared body mass index (BMI), height, weight, IGF-I, GHBP, and GHR gene expression values (evaluated by Chemiluminescent Immunometric assay; ELISA and real-time PCR, respectively) in CF patients diagnosed through newborn screening (NBS) or by symptoms (late diagnosis [LD]) and in healthy controls.

RESULTS

BMI increased significantly in patients between the time of diagnosis and check-up (P<0.001), particularly in the LD group; median value was lower at diagnosis and significantly higher (P<0.001) at follow-up visits compared to controls. At initial evaluation, higher levels of IGF-I (not statistically significant) were found in both the NBS group and the LD group compared to the control group. At the second evaluation, significantly higher levels of IGF-I (P=0.003) were found in both the NBS and LD groups compared to controls; GHR mRNA expression had significantly increased (P=0.013) in LD patients compared with the first evaluation and was significantly higher in the NBS and LD groups than in controls. GHBP values had significantly increased (P=0.047) in the NBS group after one year of therapy compared to first visit levels and were significantly higher (P<0,0001) in the NBS and LD groups compared to controls.

CONCLUSION

In our LD patients during childhood, we observed good auxological values and a GH/IGF-I axis function within normal range for the factor evaluated. However, earlier diagnosis through NBS might further minimize and prevent growth retardation, by reducing the duration of symptoms before treatment.

Growth Hormone Receptor Gene Expression Increase Reflects Nutritional Status Improvement in Patients Affected by Crohn's Disease

Background: We proposed to verify the role of growth hormone receptor gene expression in growth failure of children with Crohn's disease (CD). Methods: We measured serum levels of growth hormone binding protein (GHBP) and insulin-like growth factor-I (IGF-I), and growth hormone receptor (GHR) gene expression in peripheral blood mononuclear cells of 21 patients with CD (before and after therapy) and in 27 age-sex-matched controls. Results: At diagnosis, significantly lower insulin-like growth factor-I and growth hormone binding protein levels were found in the CD group compared to the controls. Growth hormone receptor mRNA expression was lower in patients at diagnosis compared to the controls, even though the difference did not reach statistical significance, and significantly increased in patients in the following year. Insulin-like growth factor-I levels showed significant improvements 1 year after diagnosis compared to basal levels. On the contrary, growth hormone binding protein values had not significantly changed after 1 year of therapy. Conclusion: Our study raises the hypothesis of another mechanism through which cytokines interact with the growth hormone/insulin-like growth factor-I (GH/IGF-I) axis.

Analysis of growth hormone receptor gene expression in tall and short stature children

BACKGROUND

The majority of children who present for evaluation of tall stature fall under the diagnosis of constitutional tall stature (CTS).

METHODS

To investigate mechanisms of tall stature, we evaluated serum IGF-I values and the expression of the GHR gene in the peripheral blood cells of 46 subjects with normal height, 38 with tall stature and 30 healthy children with short stature.

RESULTS

Our results showed significantly lower IGF-I levels in children with short stature (-0.57±0.18 SDS) compared to control children (0.056±0.19 SDS; p<0.0001) and to subjects with tall stature (0.594±0.17; p=0.00067). Furthermore, we found significantly higher GHR gene expression levels in tall children (321.84±90.04 agGHR/5×105agGAPDH) compared with other groups of subjects (short children: 30.13±7.5 agGHR/5×105agGAPDH, p<0.0001; controls: 86.81ag±19.5 GHR/5×105agGAPDH, p=0.035). The GHR gene expression level in short children was significantly lower compared with control subjects (p=0.0068).

CONCLUSIONS

Significantly higher GHR gene expression levels in tall subjects suggests a sensitization of the GHR-IGF system leading to overgrowth in CTS.

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.

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

The limited efficacy of standard medical therapies for inflammatory bowel diseases has resulted in a continuing search for alternative treatments. Growth hormone (GH) has shown to have mutagenic and proliferative effects on intestinal cells. This study was designed to identify the effect of growth hormone on trinitrobenzene slfonic acid-induced colitis (TNBSIC) in rats. This study was carried out on 30 rats, divided in 3 groups: group 1: TNBSIC+ GH, group 2: TNBSIC, group 3: saline enema. Colitis was induced in male Sprague-Dawley rats (200 g-250 g) by intracolonic installation of 2, 4, 6-trinitrobenzene sulphonic acid in 50% ethanol. GH treatment has been started and continued throughout the study after inducing colitis. All rats were killed after 5 weeks and colonic segments were examined histopathologically. Microscopic and macroscopic damage scores were caulculated. Intestinal damage scores were found higher in Goups II when compared with treatment group (P < 0.05). There was no damage in group 3 as expected. Both macroscopic and microscopic scores were highest in group 2 (P < 0.05). The myloperoxidase activity was found lower comparing to group 2 (P < 0.05). In conclusion, growth hormone replacement had protective effects against colonic inflammation while reducing intestinal damage on TNB-induced colitis.

Growth hormone treatment increases transmural colonic growth in GH-deficient dwarf rats

Growth hormone (GH) has been implicated as an important factor in the growth regulation of several visceral organs including the gastrointestinal tract. Our aim was to study the effects of GH administration on colonic growth in dwarf rats with an isolated GH deficiency. Dwarf rats were treated with recombinant human growth hormone (rhGH; 2.0 mg/kg/day) for four weeks and compared with saline treated dwarf rats and rats with normal pituitary function. The colonic wall composition was measured by means of stereological techniques. RhGH treatment of the dwarf rats increased body weight by 80% and proximal and distal colon weight by 63% and 90%, when compared with placebo treated dwarf rats (P< 0.01). The weight of the proximal colonic mucosa increased by 83% (P< 0.01), submucosa by 78% (P< 0.05), and the muscularis propria by 51% (P< 0.001) in rhGH treated dwarf rats compared with dwarf controls. The weight of the distal colonic mucosa increased by 88% (P< 0.01), submucosa by 88% (P< 0.05) and the muscularis propria by 58% (P< 0.05) compared with dwarf controls. The growth of mucosa involved all mucosal layers, with a 73 and 92% increase in the proximal and distal colon luminal surface area respectively (P< 0.001, P< 0.01). The food consumption, expressed as g/day/100 g BW was 13% higher in dwarf rats receiving rhGH than in placebo treated rats (P< 0.05) and normal control rats (P< 0.05). When weights of the GI tract compartments are corrected for the increase in body weight the effects of GH treatment were small or non-significant. RhGH administration in GH deficient dwarf rats induces visceral growth with a pronounced increase in colonic luminal surface area and growth of all layers of the colonic wall. These findings confirm the important role of GH in the regulation of intestinal growth.

Recombinant growth hormone's effects on the strength and thickness of radiation-injured ileal anastomoses: a rat model

BACKGROUND

Small bowel resections following radiotherapy for gynecologic cancers have resulted in significant rates of morbidity and mortality. The objective of this study was to evaluate the effect of rGH on the breaking strength and thickness of radiation-injured ileal anastomoses in an animal model.

MATERIALS AND METHODS

Sprague-Dawley rats were treated with 1800 cGy of pelvic irradiation in a single fractionation. Seventeen weeks following pelvic teletherapy an ileo-ileostomy was performed. The rats were randomized to receive 2.0 mg/kg/day of rGH for 7 days or placebo. On the seventh postoperative day a segment of ileum surrounding the anastomosis was resected. The segments were tested for breaking strength or were histologically measured for anastomotic thickness.

RESULTS

The ileal anastomotic breaking strength in the rGH group was 181 +/- 8.4 g (mean +/- standard error). The breaking strength of ileal anastomoses in the placebo group was 133 +/- 6.9 g (P < 0.05). The rGH group demonstrated a greater anastomotic thickness (1.65 +/- 0.116 mm) than the placebo group (1.17 +/- 0.113 mm, P < 0.05). Of placebo rats 14.7% developed anastomotic leaks compared to 0% of rGH-treated animals (P < 0.05).

CONCLUSIONS

RGH increased the ileal anastomotic breaking strength by 36% in radiated rats. The anastomotic leak rate was reduced from 14.7% in the placebo group to 0% in the rGH group. These findings correlated with a 41% increase in the thickness of the anastomotic connective tissue in the rGH group. Clinical investigation in selected patients is warranted.

Nutrient pharmacotherapy for gut mucosal diseases

The use of nutrients for pharmacotherapy is a recent advance in the treatment of gastrointestinal disorders or alterations of gut function and structure. Nutrients may have a direct effect on the gut, or may enhance the response to medications. Alternatively, pharmacologic agents may improve the absorption of nutrients. Potentially, pharmacotherapy may be an adjunct to the traditional approach used in the treatment of compromised patients.