Insulin-like growth factor I correlates with lean body mass in cystic fibrosis patients

Recombinant growth hormone therapy for cystic fibrosis in children and young adults

BACKGROUND

Cystic fibrosis (CF) is an inherited condition causing disease most noticeably in the lungs, digestive tract and pancreas. People with CF often have malnutrition and growth delay. Adequate nutritional supplementation does not improve growth optimally and hence an anabolic agent, recombinant human growth hormone (rhGH), has been proposed as a potential intervention. This is an update of a previously published review.

OBJECTIVES

To evaluate the effectiveness and safety of rhGH therapy in improving lung function, quality of life and clinical status of children and young adults with CF.

SEARCH METHODS

We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group's Trials Register comprising references identified from comprehensive electronic database searches and handsearches of relevant journals and abstract books of conference proceedings. Date of latest search: 12 January 2021. We also searched ongoing trials registers: clinicaltrials.gov from the United States - date of latest search 19 Jun 2021; WHO International Clinical Trials Registry Platform (ICTRP) - date of latest search 05 March 2018 (not available in 2021).  We conducted a search of relevant endocrine journals and proceedings of the Endocrinology Society meetings using Web of Science, Scopus and Proceedings First. Date of latest search: 21 Jun 2021.  SELECTION CRITERIA: Randomised and quasi-randomised controlled trials of all preparations of rhGH compared to either no treatment, or placebo, or each other at any dose (high-dose and low-dose) or route and for any duration, in children or young adults (aged up to 25 years) diagnosed with CF (by sweat test or genetic testing).

DATA COLLECTION AND ANALYSIS

Two authors independently screened papers, extracted trial details and assessed their risk of bias. We assessed the quality of the evidence using the GRADE system.

MAIN RESULTS

We included eight trials (291 participants, aged between five and 23 years) in the current version of the review. Seven trials compared standard-dose rhGH (approximately 0.3 mg/kg/week) to no treatment and one three-arm trial (63 participants) compared placebo, standard-dose rhGH (0.3 mg/kg/week) and high-dose rhGH (0.5 mg/kg/week). Six trials lasted for one year and two trials for six months. We found that rhGH treatment may improve some of the pulmonary function outcomes, but there was no difference between standard and high-dose levels (low-certainty evidence, limited by inconsistency across the trials, small number of participants and short duration of therapy). The trials show evidence of improvement in the anthropometric parameters (height, weight and lean body mass) with rhGH therapy, again no differences between dose levels. We found improvement in height for all comparisons (very low- to low-certainty evidence), but improvements in weight and lean body mass were only reported for standard-dose rhGH versus no treatment (very low-certainty evidence). There is some evidence indicating a change in the level of fasting blood glucose with rhGH therapy, however, it did not cross the clinical threshold for diagnosis of diabetes in the trials of short duration (low-certainty evidence). There is low- to very low-certainty evidence for improvement of pulmonary exacerbations with no further significant adverse effects, but this is limited by the short duration of trials and the small number of participants. One small trial provided inconsistent evidence on improvement in quality of life (very low-certainty evidence). There is limited evidence from three trials in improvements in exercise capacity (low-certainty evidence). None of the trials have systematically compared the expense of therapy on overall healthcare costs.

AUTHORS' CONCLUSIONS

When compared with no treatment, rhGH therapy is effective in improving the intermediate outcomes in height, weight and lean body mass. Some measures of pulmonary function showed moderate improvement, but no consistent benefit was seen across all trials. The significant change in blood glucose levels, although not causing diabetes, emphasizes the need for careful monitoring of this adverse effect with therapy in a population predisposed to CF-related diabetes. No significant changes in quality of life, clinical status or side-effects were observed in this review due to the small number of participants. Long-term, well-designed randomised controlled trials of rhGH in individuals with CF are required prior to routine clinical use of rhGH in CF.

Lumacaftor/ivacaftor-associated health stabilisation in adults with severe cystic fibrosis

Introduction

Lumacaftor/ivacaftor (LUM/IVA) has been shown to improve clinical outcomes in cystic fibrosis (CF) patients homozygous for Phe508del with forced expiratory volume in 1 s (FEV₁) % pred >40%. We assessed the clinical utility of LUM/IVA in all eligible adult CF patients with FEV₁ % pred <40% treated for at least 1 year under a single-centre managed access programme.

Methods

Following clinical optimisation, eligible patients (n=40) with FEV₁ % pred <40% were commenced on LUM/IVA and monitored for tolerance and clinical outcomes, including health service utilisation, pulmonary function, weight and body composition. 24 patients reached 1 year of treatment by the time of evaluation. Six patients discontinued due to adverse events (five for increased airways reactivity) and three underwent lung transplantation.

Results

In comparison with the year prior to LUM/IVA commencement, significant reductions (median per year) were observed in the treatment year in the number of pulmonary exacerbations requiring hospitalisation (from 3 to 1.5; p=0.0002), hospitalisation days (from 27 to 17; p=0.0002) and intravenous antibiotic (IVAB) usage days (from 45 to 27; p=0.0007). Mean±sd change in FEV₁ % pred was −2.10±1.18% per year in the year prior, with the decline reversed in the year following (+1.45±1.13% per year; p=0.035), although there was significant heterogeneity in individual responses. Mean±sd weight gain at 1 year was 2.5±4.1 kg (p=0.0007), comprising mainly fat mass (mean 2.2 kg). The proportion of patients severely underweight (body mass index <18.5 kg·m⁻²) decreased from 33% at baseline to 13% at 1 year (p=0.003).

Conclusion

This real-world evaluation study demonstrated benefits over several clinical domains (infective exacerbations requiring hospitalisation, IVABs, pulmonary function decline and nutritional parameters) in CF patients with severe lung disease.

In adults with severe cystic fibrosis lung disease, 1 year of treatment with lumacaftor/ivacaftor was associated with reduced infective exacerbations, days of intravenous antibiotics and rate of pulmonary function decline, and improved nutritional statushttps://bit.ly/2I07suR

Body composition and weight changes after ivacaftor treatment in adults with cystic fibrosis carrying the G551 D cystic fibrosis transmembrane conductance regulator mutation: A double-blind, placebo-controlled, randomized, crossover study with open-label extension

OBJECTIVES

In patients with cystic fibrosis (CF) who carry the G551D mutation, treatment with ivacaftor improves lung function and weight; however, short- and long-term impacts on body composition have not been well studied.

METHODS

Twenty adults with CF carrying the G551D mutation (mean ± standard deviation body mass index [BMI] 23.3 ± 4.3 kg/m²) were recruited for a single-center, double-blind, placebo-controlled, 28-d, crossover study of ivacaftor, followed by an open-label extension (OLE) for 5 mo. Eleven patients underwent measurements 2 y later. The study variables included weight, BMI, and body composition (including fat-free mass [FFM] and fat mass).

RESULTS

After 28 d of treatment with ivacaftor, weight increased by 1.1 ± 1.3 kg, BMI by 0.4 ± 0.5 kg/m², and FFM by 1.1 ± 1.2 kg (all P < .005) with no change in fat mass. Differences between 28-d changes on ivacaftor and placebo were not statistically significant. In the following 5 mo of the OLE, there were significant increases in weight (1.2 ± 1.9 kg; P < .05) and fat mass (1.5 ± 1.9 kg; P < .01), but not in FFM. Between baseline and the end of the OLE, the total weight gain was 2.5 ± 2.4 kg (P < .005), comprised of 0.9 ± 1.5 kg FFM (P < .05) and 1.6 ± 1.8 kg fat mass (P < .005). For the 11 participants who were followed for a further 2 y, no further changes in mean weight, BMI, or body composition parameters between 6 mo and 2 y later were observed.

CONCLUSIONS

Small gains were seen in FFM in the first month of ivacaftor treatment. Weight, BMI, and fat-mass gains in the first 6 mo on ivacaftor plateaued by 2.5 y. The metabolic and clinical consequences of weight and fat-mass gains remain to be determined.

Deficits in Bone Geometry in Growth Hormone-Deficient Prepubertal Boys Revealed by High-Resolution Peripheral Quantitative Computed Tomography

INTRODUCTION

Although growth hormone (GH) is essential for attainment of peak bone mass, bone health in prepubertal children with GH deficiency is not routinely evaluated. The objective of this study was to evaluate bone microarchitecture in GH-deficient (GHD) boys using high-resolution peripheral quantitative computed tomography (HR-pQCT).

METHODS

Fifteen control and fifteen GHD, GH naïve pre-pubertal boys were recruited for a case-control study at a major academic center. Subjects with panhypopituitarism, chromosomal pathology, chronic steroids, or stimulant use were excluded. Volumetric bone mineral density (vBMD; total, cortical, and trabecular), bone geometry (total, cortical and trabecular cross-sectional area, cortical perimeter), bone microarchitecture, and estimated bone strength of the distal radius and tibia were assessed by HR-pQCT. Areal BMD and body composition were assessed by DXA. Insulin-like growth factor 1 (IGF-1), osteocalcin, C telopeptide, and P1NP levels were measured.

RESULTS

GHD subjects had a significantly smaller cortical perimeter of the distal radius compared to controls (p < 0.001), with the difference in cortical perimeter persisting after adjusting for height z score, age, lean mass, and 25-hydroxyvitamin D level (p < 0.05).No significant differences were found in vBMD. No significant differences were found in microarchitecture, estimated strength, areal BMD, body composition, or bone turnover markers. Analysis showed significant positive correlations between IGF-1 levels and cortical parameters.

DISCUSSION/CONCLUSIONS

Prepubertal GHD boys had deficits in bone geometry not evident with DXA. Larger prospective/longitudinal HR-pQCT studies are needed to determine the extent of these deficits, the need for routine bone evaluation, and the timing of GH replacement for prevention or restoration of these deficits.

Recombinant growth hormone therapy for cystic fibrosis in children and young adults

BACKGROUND

Cystic fibrosis (CF) is an inherited condition causing disease most noticeably in the lungs, digestive tract and pancreas. People with CF often have malnutrition and growth delay. Adequate nutritional supplementation does not improve growth optimally and hence an anabolic agent, recombinant human growth hormone (rhGH), has been proposed as a potential intervention. This is an update of a previously published review.

OBJECTIVES

To evaluate the effectiveness and safety of rhGH therapy in improving lung function, quality of life and clinical status of children and young adults with CF.

SEARCH METHODS

We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group's Trials Register comprising references identified from comprehensive electronic database searches and handsearches of relevant journals and abstract books of conference proceedings. Date of latest search: 22 October 2018.We also searched ongoing trials registers in clinicaltrials.gov from the United States and WHO International Clinical Trials Registry Platform (ICTRP). Date of latest search: 05 March 2018.We conducted a search of relevant endocrine journals and proceedings of the Endocrinology Society meetings using Web of Science, Scopus and Proceedings First. Date of latest search: 04 March 2018.

SELECTION CRITERIA

Randomised and quasi-randomised controlled trials of all preparations of rhGH compared to either no treatment, or placebo, or each other at any dose (high-dose and low-dose) or route and for any duration, in children or young adults (aged up to 25 years) diagnosed with CF (by sweat test or genetic testing).

DATA COLLECTION AND ANALYSIS

Two authors independently screened papers, extracted trial details and assessed their risk of bias. We assessed the quality of the evidence using the GRADE system.

MAIN RESULTS

We included eight trials (291 participants, aged between five and 23 years) in this revision of the review. Seven trials compared standard-dose rhGH (approximately 0.3 mg/kg/week) to no treatment and one three-arm trial (63 participants) compared placebo, standard-dose rhGH (0.3 mg/kg/week) and high-dose rhGH (0.5 mg/kg/week). Six trials lasted for one year and two trials for six months. We found that rhGH treatment may improve some of the pulmonary function outcomes but there was no difference between standard and high-dose levels (low-quality evidence, limited by inconsistency across the trials, small number of participants and short duration of therapy). The trials show evidence of improvement in the anthropometric parameters (height, weight and lean body mass) with rhGH therapy, again no differences between dose levels. We found improvement in height for all comparisons (very low- to low quality evidence), but improvements in weight and lean body mass were only reported for standard-dose rhGH versus no treatment (very low-quality evidence). There is some evidence indicating a change in the level of fasting blood glucose with rhGH therapy, however, it did not cross the clinical threshold for diagnosis of diabetes in the trials of short duration (low-quality evidence). There is low- to very low-quality evidence for improvement of pulmonary exacerbations with no further significant adverse effects, but this is limited by the short duration of trials and the small number of participants. One small trial provided inconsistent evidence on improvement in quality of life (very low-quality evidence). There is limited evidence from three trials in improvements in exercise capacity (low-quality evidence). None of the trials have systematically compared the expense of therapy on overall healthcare costs.

AUTHORS' CONCLUSIONS

When compared with no treatment, rhGH therapy is effective in improving the intermediate outcomes in height, weight and lean body mass. Some measures of pulmonary function showed moderate improvement, but no consistent benefit was seen across all trials. The significant change in blood glucose levels, although not causing diabetes, emphasizes the need for careful monitoring of this adverse effect with therapy in a population predisposed to CF-related diabetes. No significant changes in quality of life, clinical status or side-effects were observed in this review due to the small number of participants. Long-term, well-designed randomised controlled trials of rhGH in individuals with CF are required prior to routine clinical use of rhGH in CF.

Diet and Anthropometrics of Children With Inflammatory Bowel Disease: A Comparison With the General Population

BACKGROUND

There is a lack of knowledge regarding the diet of children with inflammatory bowel disease (IBD). Therefore, we investigated dietary intake in pediatric IBD compared to the general population and assessed anthropometrics and food avoidance.

METHODS

In this cross-sectional cohort study, patients younger than 18 years with IBD were included (2014-2017). Dietary intake (total energy, macro nutrients, food types) was assessed using a Food Frequency Questionnaire (FFQ) and compared with a matched reference population (n = 306).

RESULTS

There were 102 patients included (55% male, median age 15.0 years). Median height Z-score was -0.39 (interquartile range [IQR]: -1.17 to 0.26). Growth failure (height Z-scores<-1.64) was present in 11% of patients. Median BMI Z-score was 0.36 (IQR: -0.70 to 0.96). Acute malnutrition (weight-for-height Z-score<-2) was present in 3% of patients. Energy intake was lower in pediatric IBD compared to the reference population (mean kilojoule/day: 8286 vs 9794, P < 0.001). Protein intake did not differ, while fat intake was higher in pediatric IBD (mean gram/day: 101 vs 91, P < 0.001), with higher intake of vegetable oils/fats. Carbohydrate intake was lower in pediatric IBD (mean gram/day: 267 vs 305, P < 0.001), with lower intake of food types high in sugar. Food avoidance was reported in 53% of patients, with frequent avoidance of spicy (46%), high-fat food (30%), and dairy (30%).

CONCLUSIONS

The diet of children with IBD differs from the general pediatric population, with lower energy intake and high rates of food avoidance. Evaluation of the dietary intake alongside anthropometrics may be important to prevent nutrition deficiencies and promote health.

Deregulation of the growth hormone/insulin-like growth factor-1 axis in adults with cystic fibrosis

PURPOSE

Patients with cystic fibrosis (CF) present with signs and symptoms that overlap with those of adult growth hormone deficiency (GHD) syndrome: loss of muscle mass, bone fragility and lower stress tolerance. In literature, the prevalence of GHD in pediatric CF patients is higher than general population, but these studies have been performed on children with growth delay. To our knowledge, there are no studies on adult patients. The aim of this paper is to evaluate GH-IGF1 axis in an adult CF population.

METHODS

Fifty clinically stable adult patients, 30 males; age 36 ± 2 years; BMI 21.39 ± 0.22 kg/m² and FEV₁ 67 ± 4% were studied. Data regarding glycometabolic status and results of pituitary, thyroid, parathyroid, gonadal and adrenal function tests were recorded. All patients underwent a GH releasing hormone (GHRH) + Arginine stimulation test to confirm a GHD.

RESULTS

GHRH + Arginine test revealed the presence of GHD in 16 patients (32%); specifically 7 patients had a severe deficiency and 9 a partial deficiency.

CONCLUSIONS

Adult patients with CF may show GHD. These patients should be followed over time to assess if the GHD could impact the clinical progression of CF.

The relationship between energy intake and body-growth in children with cystic fibrosis

BACKGROUND & AIMS

Body-growth, expressed as weight- and height gain, is a strong predictor of morbidity and mortality in patients with cystic fibrosis (CF). Whether current historically based recommendations on a high-energy diet are sufficient for optimal growth is questionable. We therefore assessed the longitudinal relation between body-growth and routine energy intake in paediatric CF patients.

METHODS

Included were patients with CF, aged 2-10 years of whom we obtained 969 measurements of weight and height along with dietary records, and 786 coefficient of fat absorption measurements (CFA). We described body-growth, energy intake, macronutrient intake and the long-term effect of energy intake and coefficient of fat absorption on body-growth during the 8-year follow-up period.

RESULTS

Enrolled were 191 children with CF who had a compromised growth when compared to healthy children. The dietary intake was ≥110% estimated average requirement (EAR) in 47% of the measurements (457/969) and did not (fully) achieve the recommended high-energy level (110-200% EAR). Further, the intake expressed as EAR decreased with increasing age. Cross-sectionally, boys and girls with higher caloric intakes had higher weight-for-age (WFA). The caloric intake explained 18 and 6% of the variation. Further, boys with higher caloric intakes had also higher height-for-age-adjusted-for-target-height (HFA/TH) or BMI. The caloric intake explained 6 or 7% of the variation. Longitudinally, caloric intake was associated with both WFA in boys and girls, and with BMI in boys. Each 100 calories increased intake would result in a 0.01 (girls)-0.02 increase in z-score WFA and 0.03 increase in z-score BMI. We found no significant association between CFA and WFA, HFA/TH or BMI. The contribution of protein, fat and carbohydrates was not associated with WFA, nor with HFA/TH or BMI.

CONCLUSION

Even at this relatively early age, a compromised growth in children with CF was found when compared to healthy children. The energy intake was below 110% EAR in 47% of the measurements, and appeared to be insufficient to prevent suboptimal body-growth over the 8-years of follow-up.

Endocrine Disorders in Cystic Fibrosis

Cystic fibrosis is frequently complicated by endocrine disorders. Diabetes can be expected to affect most with CF and pancreatic insufficiency and varies widely in age of onset, but early identification and treatment improve morbidity and mortality. Short stature can be exacerbated by relative delay of puberty and by use of inhaled corticosteroids. Bone disease in CF causes fragility fractures and should be assessed by monitoring bone mineral density and optimizing vitamin D status. Detecting and managing endocrine complications in CF can reduce morbidity and mortality in CF. These complications can be expected to become more common as the CF population ages.

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.

Early Life Growth Trajectories in Cystic Fibrosis are Associated with Pulmonary Function at Age 6 Years

OBJECTIVE

To determine whether severity of lung disease at age 6 years is associated with changes in nutritional status before age 6 within individual children with cystic fibrosis (CF).

STUDY DESIGN

Children with CF born between 1994 and 2005 and followed in the CF Foundation Patient Registry from age ≤2 through 7 years were assessed according to changes in annualized weight-for-length (WFL) percentiles between ages 0 and 2 years and body mass index (BMI) percentiles between ages 2 and 6 years. The association between growth trajectories before age 6 and forced expiratory volume in 1 second (FEV1)% predicted at age 6-7 years was evaluated using multivariable linear regression.

RESULTS

A total of 6805 subjects met inclusion criteria. Children with annualized WFL-BMI always >50th percentile (N = 1323 [19%]) had the highest adjusted mean (95% CI) FEV1 at 6-7 years (101.8 [100.1, 103.5]). FEV1 at 6-7 years for children whose WFL-BMI increased >10 percentile points by age 6 years was 98.3 (96.6, 100.0). This was statistically significantly higher than FEV1 for children whose WFL-BMI was stable (94.4 [92.6, 96.2]) or decreased >10 percentile points (92.9 [91.1, 94.8]). Among children whose WFL-BMI increased >10 percentile points, achieving and maintaining WFL-BMI >50th percentile at younger ages was associated with significantly higher FEV1 at 6-7 years.

CONCLUSIONS

Within-patient changes in nutritional status in the first 6 years of life are significantly associated with FEV1 at age 6-7 years. The establishment of a clear relationship between early childhood growth measurements and later lung function suggests that early nutritional interventions may impact on eventual lung health.

Anabolic agent use in adults with cystic fibrosis

The use of non-prescribed anabolic agents amongst non-athletes is increasing with young, adult males with cystic fibrosis (CF) in the highest risk demographic. There is evidence that anabolic agents increase weight and muscle mass in adults with a variety of catabolic conditions but there is no evidence for their use in hormone sufficient adults with CF. We report a case of anabolic agent use in a male adult with CF and review the clinical features of anabolic agent use with a focus on adults with CF.

Recombinant growth hormone therapy for cystic fibrosis in children and young adults

BACKGROUND

Cystic fibrosis is an inherited condition causing disease most noticeably in the lungs, digestive tract and pancreas. People with cystic fibrosis often have malnutrition and growth delay. Adequate nutritional supplementation does not improve growth optimally and hence an anabolic agent, recombinant growth hormone, has been proposed as a potential intervention.

OBJECTIVES

To evaluate the effectiveness and safety of recombinant human growth hormone therapy in improving lung function, quality of life and clinical status of children and young adults with cystic fibrosis.

SEARCH METHODS

We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group's Trials Register comprising references identified from comprehensive electronic database searches and handsearches of relevant journals and abstract books of conference proceedings. Date of latest search: 11 February 2015.We conducted a search of relevant endocrine journals and proceedings of the Endocrinology Society meetings using Scopus and Proceedings First. Date of latest search: 04 March 2015.

SELECTION CRITERIA

Randomised and quasi-randomised controlled trials of all preparations of recombinant growth hormone compared to either no treatment, or placebo, or each other at any dose (high-dose and low-dose) or route and for any duration, in children or young adults aged up to 25 years diagnosed with cystic fibrosis (by sweat test or genetic testing).

DATA COLLECTION AND ANALYSIS

Two authors independently screened papers, extracted trial details and assessed their risk of bias.

MAIN RESULTS

Four controlled trials were included in this review (with 161 participants in total), each with an unclear risk of bias. Analysis of data obtained from these trials shows improvement in height for all comparisons, but improvements in weight and lean tissue mass were only reported in the comparison of standard dose recombinant growth hormone versus no treatment. One study showed moderate improvement at one time point in one parameter of pulmonary function tests, forced vital capacity (per cent predicted) when comparing standard dose recombinant growth hormone and no treatment, but there was no consistent benefit in lung function across all studies. Little evidence was found for improvement in quality of life. An improvement in fasting blood glucose levels was reported when comparing rhGH to placebo only. Exercise capacity improved in participants receiving standard dose recombinant growth hormone versus no treatment, but not for any other comparison. There is insufficient evidence to conclude any changes in hospitalisations, antibiotic use or significant adverse effects.

AUTHORS' CONCLUSIONS

Recombinant growth hormone therapy is effective in improving the intermediate outcomes in height, weight and lean tissue mass when compared with no treatment. One measure of pulmonary function test showed moderate improvement at a single time point, but no consistent benefit was seen across all studies. No significant changes in quality of life, clinical status or side-effects were observed in this review. Long-term, well-designed randomised controlled trials of recombinant growth hormone therapy in people with cystic fibrosis are required prior to evaluation of human growth hormone treatment for routine use.

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.

Insulin-like growth factor-I (IGF-I) and clinical nutrition

IGF-I (insulin-like growth factor-I) is a peptide hormone, produced predominantly by the liver in response to pituitary GH (growth hormone), which is involved in a wide variety of physiological processes. It acts in an endocrine, paracrine and autocrine manner to promote growth. The production of IGF-I signals the availability of nutrients needed for its anabolic actions. Recently, there has been growing interest in its role in health and disease. IGF-I has long been known to be regulated by nutrition and dysregulated in states of under- and over-nutrition, its serum concentrations falling in malnutrition and responding promptly to refeeding. This has led to interest in its utility as a nutritional biomarker. A considerable evidence base supports utility for measurement of IGF-I in nutritional contexts. Its concentration may be valuable in providing information on nutritional status, prognosis and in monitoring nutritional support. However, it is insufficiently specific for use as a screening test for under nutrition as its serum concentration is influenced by many factors other than nutritional status, notably the APR (acute-phase response) and endocrine conditions. Concentrations should be interpreted along with clinical findings and the results of other investigations such as CRP (C-reactive protein). More recently, there has been interest in free IGF-I which holds promise as a nutritional marker. The present review covers nutritional regulation of IGF-I and its dysregulation in disease, then goes on to review recent studies supporting its utility as a nutritional marker in clinical contexts. Although not currently recommended by clinical guidelines, it is likely that, in time, measurement of IGF-I will become a routine part of nutritional assessment in a number of these contexts.

Recombinant growth hormone therapy for cystic fibrosis in children and young adults

BACKGROUND

Cystic fibrosis is an inherited condition causing disease most noticeably in the lungs, digestive tract and pancreas. People with cystic fibrosis often have malnutrition and growth delay. Adequate nutritional supplementation does not improve growth optimally and hence an anabolic agent, recombinant growth hormone, has been proposed as a potential intervention.

OBJECTIVES

To evaluate the effectiveness and safety of recombinant human growth hormone therapy in improving lung function, quality of life and clinical status of children and young adults with cystic fibrosis.

SEARCH METHODS

We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group's Trials Register comprising references identified from comprehensive electronic database searches and handsearches of relevant journals and abstract books of conference proceedings. Date of latest search: 15 May 2013.We conducted a search of relevant endocrine journals and proceedings of the Endocrinology Society meetings using Scopus and Proceedings First. Date of latest search: 15 March 2012.

SELECTION CRITERIA

Randomised and quasi-randomised controlled trials of all preparations of recombinant growth hormone compared to either no treatment, or placebo, or each other at any dose (high-dose and low-dose) or route and for any duration, in children or young adults aged up to 25 years diagnosed with cystic fibrosis (by sweat test or genetic testing).

DATA COLLECTION AND ANALYSIS

Two authors independently screened papers, extracted trial details and assessed their risk of bias.

MAIN RESULTS

Four controlled trials were included in this review (with 161 participants in total), each with an unclear risk of bias. Analysis of data obtained from these trials shows improvement in height for all comparisons, but improvements in weight and lean tissue mass were only reported in the comparison of standard dose recombinant growth hormone versus no treatment. There is moderate improvement in one parameter of pulmonary function tests, functional vital capacity (per cent predicted) when comparing standard dose recombinant growth hormone and no treatment. Little evidence was found for improvement in quality of life. An improvement in fasting blood glucose levels was reported when comparing rhGH to placebo only. Exercise capacity improved in participants receiving standard dose recombinant growth hormone versus no treatment, but not for any other comparison. There is insufficient evidence to conclude any changes in hospitalisations, antibiotic use or significant adverse effects.

AUTHORS' CONCLUSIONS

Recombinant growth hormone therapy is effective in improving the intermediate outcomes in height, weight and lean tissue mass when compared with no treatment. One measure of pulmonary function test showed moderate improvement. No significant changes in quality of life, clinical status or side-effects were observed in this review. Long-term, well-designed randomised controlled trials of recombinant growth hormone therapy in patients with cystic fibrosis are required prior to evaluation of human growth hormone treatment for routine use in patients.

Loss of fat-free mass over four years in adult cystic fibrosis is associated with high serum interleukin-6 levels but not tumour necrosis factor-alpha

BACKGROUND & AIMS

Malnutrition is associated with poorer outcome in cystic fibrosis (CF). This follow-up study aimed to document nutritional status changes, including fat-free mass (FFM), in adults with CF; and to identify predictors of FFM loss.

METHODS

Fifty-eight non-transplanted CF adults (mean ± SD forced expiratory volume in one second (FEV1) 63.7 ± 21.4%predicted; mean ± SD age 30.3 ± 7.7years at baseline) were studied at baseline and 3.6 ± 0.4 years later. Body composition was measured using dual-energy X-ray absorptiometry. At follow-up, blood was analysed for interleukin-6 and tumour necrosis factor-α (TNF-α) on three occasions over six months and averaged for each participant. Associations with annual percentage change in FFM (ann%ΔFFM), including cytokines, CF genotype and annual change in FEV1%predicted (annΔFEV1%), were determined.

RESULTS

Mean FFM was 49.5 ± 8.8 kg at baseline and 49.6 ± 8.9 kg at follow-up (p = 0.66). Ann%ΔFFM ranged from -2.0 to +3.6%. FEV1%predicted declined by 1.2 ± 2.4% per year. Forty percent of participants had elevated average interleukin-6 levels. Ann%ΔFFM was negatively correlated with interleukin-6 levels (rho -0.34, p = 0.008), but not TNF-α or annΔFEV1%. F508DEL homozygote or heterozygote participants had greater FFM loss than those carrying no F508DEL allele (p = 0.01).

CONCLUSION

Higher serum interleukin-6 and presence of the F508DEL mutation, but not TNF-α, were associated with FFM loss in adults with CF.

Dietary essential amino acids are highly anabolic in pediatric patients with cystic fibrosis

BACKGROUND

Current nutritional approaches have been partially successful in Cystic Fibrosis (CF). Essential amino acids mixtures with high Leucine levels (EAA) have anabolic properties in catabolic conditions, however data in CF are lacking.

METHODS

On two days according a randomized crossover design, 15 pediatric CF patients ingested 6.7 g EAA versus mixture of total amino acids as present in whey. Whole body protein and Arginine metabolism (as EAA lack Arginine) were assessed by stable isotope methodology.

RESULTS

Protein synthesis (P<0.05) but not protein breakdown was higher after EAA and 70% higher values for net anabolism (P<0.001)were found both in patients with and without nutritional failure. Arginine turnover was lower (P<0.001) and de novo Arginine synthesis tended lower (P=0.09) after EAA. Nitric oxide synthesis was not different.

CONCLUSIONS

CF patients are highly responsive to EAA intake independent of their nutritional status. Addition of Arginine to the EAA mixture may be warranted in CF.

The insulin like growth factor system in cirrhosis. Relation to changes in body composition following adrenoreceptor blockade

OBJECTIVE

Circulating levels of IGF-I and IGFBP-3 are low in cirrhosis and are related to liver dysfunction. Metabolic disturbances include malnutrition with altered body composition and osteopenia. Since the effects of IGF-I may be associated to changes in body composition and bone mineral content (BMC) in cirrhotic patients, we investigated the relations between changes in the IGF-system and body composition and the effects of long-term alpha- and beta-blockade.

DESIGN

The study was designed as a combined cross-sectional and prospective randomised controlled study of 62 patients with cirrhosis. Twenty-three of these patients were randomised to treatment with beta- or combined alpha/beta-blocker for 3 months. Haemodynamics, body composition, and systemic and hepatic IGF-I and IGFBP-3 levels were determined in all patients. In the subgroup changes in body composition and IGF-I/IGFBP-3 levels after 3 months of beta- or combined alpha/beta-blockade were additionally examined.

RESULTS

Both the hepatic and the systemic IGF systems were suppressed and correlated with liver dysfunction and anthropometrics (p<0.05-0.001). Multivariate analyses revealed that changes in the IGF-system were determined by metabolic liver dysfunction as well as anthropometrics. In the follow-up study, hepatic venous IGF-I (p=0.05) and IGFBP-3 (p=0.02) increased after 3 months only in the group who received beta-blocker. In both groups, fat body mass increased significantly after 3 months (p=0.05-0.001).

CONCLUSIONS

In cirrhosis, the IGF-system is associated with both anthropometrics and synthetic capacity of the liver. Changes in IGF-I relate to changes in anthropometrics and there seems to be a differential effect depending on the type of adrenoreceptor blockade. Future longitudinal studies are needed to unravel these mechanisms in cirrhosis.

Human conditions of insulin-like growth factor-I (IGF-I) deficiency

Insulin-like growth factor I (IGF-I) is a polypeptide hormone produced mainly by the liver in response to the endocrine GH stimulus, but it is also secreted by multiple tissues for autocrine/paracrine purposes. IGF-I is partly responsible for systemic GH activities although it possesses a wide number of own properties (anabolic, antioxidant, anti-inflammatory and cytoprotective actions). IGF-I is a closely regulated hormone. Consequently, its logical therapeutical applications seems to be limited to restore physiological circulating levels in order to recover the clinical consequences of IGF-I deficiency, conditions where, despite continuous discrepancies, IGF-I treatment has never been related to oncogenesis. Currently the best characterized conditions of IGF-I deficiency are Laron Syndrome, in children; liver cirrhosis, in adults; aging including age-related-cardiovascular and neurological diseases; and more recently, intrauterine growth restriction. The aim of this review is to summarize the increasing list of roles of IGF-I, both in physiological and pathological conditions, underlying that its potential therapeutical options seem to be limited to those proven states of local or systemic IGF-I deficiency as a replacement treatment, rather than increasing its level upper the normal range.

The insulin-like growth factor system and nutritional assessment

Over recent years there has been considerable interest in the role of the insulin-like growth factor (IGF) system in health and disease. It has long been known to be dysregulated in states of under- and overnutrition, serum IGF-I levels falling in malnourished patients and responding promptly to nutritional support. More recently, other proteins in this system have been observed to be dysregulated in both malnutrition and obesity. Currently no biochemical marker is sufficiently specific for use in screening for malnutrition, but levels may be valuable in providing information on nutritional status and in monitoring of nutritional support. All have limitations as nutritional markers in that their serum levels are influenced by factors other than nutritional status, most importantly the acute phase response (APR). Levels should be interpreted along with clinical findings and the results of other investigations such as C-reactive protein (CRP). This paper reviews data supporting the use of proteins of the IGF system as nutritional markers.

Successful prolonged use of recombinant human insulin-like growth factor-1 in a child with cystic fibrosis

Growth failure is a common and complicated process in children with cystic fibrosis (CF). Growth hormone, which is becoming a more commonly used agent in such patients, has demonstrated beneficial effects aside from increased growth velocity. Recently, insulin-like growth factor-1 has gained significant attention in the understanding of growth failure in children with CF. We report the successful prolonged use of recombinant human insulin-like growth factor-1 in an adolescent boy with CF, who demonstrated significant clinical benefits from the therapy.

Molecular genetic studies of gene identification for sarcopenia

Sarcopenia, which is characterized by a progressive decrease of skeletal muscle mass and function with aging, is closely related to several common diseases (such as cardiovascular and airway diseases) and functional impairment/disability. Strong genetic determination has been reported for muscle mass and muscle strength, two most commonly recognized and studied risk phenotypes for sarcopenia, with heritability ranging from 30 to 85% for muscle strength and 45-90% for muscle mass. Sarcopenia has been the subject of increasing genetic research over the past decade. This review is designed to comprehensively summarize the most important and representative molecular genetic studies designed to identify genetic factors associated with sarcopenia. We have methodically reviewed whole-genome linkage studies in humans, quantitative trait loci mapping in animal models, candidate gene association studies, newly reported genome-wide association studies, DNA microarrays and microRNA studies of sarcopenia or related skeletal muscle phenotypes. The major results of each study are tabulated for easy comparison and reference. The findings of representative studies are discussed with respect to their influence on our present understanding of the genetics of sarcopenia. This is a comprehensive review of molecular genetic studies of gene identification for sarcopenia, and an overarching theme for this review is that the currently accumulating results are tentative and occasionally inconsistent and should be interpreted with caution pending further investigation. Consequently, this overview should enhance recognition of the need to validate/replicate the genetic variants underlying sarcopenia in large human cohorts and animal. We believe that further progress in understanding the genetic etiology of sarcopenia will provide valuable insights into important fundamental biological mechanisms underlying muscle physiology that will ultimately lead to improved ability to recognize individuals at risk for developing sarcopenia and our ability to treat this debilitating condition.

Body composition assessed by the 4-component model and association with lung function in 6-12-y-old children with cystic fibrosis

BACKGROUND

Malnutrition is an indicator of a poor prognosis in patients with cystic fibrosis (CF). Previous body-composition (BC) studies in children with CF used 2-component models (2CMs) to assess fat mass (FM) and fat-free mass (FFM), but to our knowledge no study has used the gold-standard 4-component model (4CM), which allows for a more accurate evaluation of the nature of both elements.

OBJECTIVE

We measured BC by using the 4CM in 6-12-y-old children with CF to 1) compare findings with those of healthy, matched control children and reference data; 2) relate BC to lung spirometry [forced expired volume in 1 s (FEV₁)]; and 3) compare findings with those from more commonly used 2CM techniques.

DESIGN

One hundred clinically stable children with CF (57% girls) aged 6-12 y were measured by using the 4CM. Children with CF underwent spirometry (FEV₁).

RESULTS

Girls with CF had significantly less FM than did healthy girls, even after adjustment for height and pubertal status; boys with CF had higher body mass index SD scores than did healthy boys. FM in girls was positively associated with the FEV₁ percentage predicted. The 2CM FM was significantly different from the 4CM FM, with differences dependent on sex and condition, although most techniques identified a relation between FM and FEV₁ in girls.

CONCLUSIONS

Although shorter than healthy children, boys with CF were heavier and had a BC within the normal range; however, girls with CF had lower FM than did healthy girls, and this was associated with poorer lung function. Given the worse prognosis in girls, this finding merits more attention. The reliability of 2CM techniques varied with sex and health status.

Percent true calcium absorption, mineral metabolism, and bone mineralization in children with cystic fibrosis: effect of supplementation with vitamin D and calcium

OBJECTIVE

To assess whether percent true calcium absorption (alpha) is normal in children with cystic fibrosis (CF) and to assess whether supplementation with 2,000 IU vitamin D(3), 1 g calcium, or both will alter alpha, mineral metabolism, and/or bone mass in children with CF.

STUDY DESIGN

Fifteen children ages 7-13 were randomly assigned to one of four different orders to receive all four 6-month treatments including placebos. Change in 25-hydroxyvitamin D (25-OHD), 1,25-dihydroxyvitamin D (1,25(OH)(2)D), PTH, bone turnover markers, and minerals after 6 months, and bone mineral content (Hologic 1000W) after 9 months was measured. alpha was measured by a dual stable isotope method using (48)Ca intravenously and (46)Ca orally and measuring (48)Ca, (46)Ca, and (42)Ca in a 24-hr urine using High Resolution Inductively Coupled Mass Spectroscopy (HR-ICP-MS). Analysis used Wilcoxon Sign Ranks.

RESULTS

alpha was in the normal range and did not differ by treatment (P 35 +/- 10%, Ca 38 +/- 23%, D 36 +/- 11%, D + Ca 46 +/- 21%). One gram calcium did not increase serum or urine calcium. Two thousand IU D(3) did not increase 25-OHD or change 1,25(OH)(2)D. Serum and urine minerals, markers of bone turnover and bone mineral gains did not differ by treatment.

CONCLUSIONS

alpha is normal in children with CF. One gram calcium and/or 2,000 IU D(3) does not change alpha or increase 25-OHD, serum calcium, or mineralization. Longer trials of a significantly higher dose of vitamin D(3) shown to increase serum 25-OHD are needed to assess effects on mineral metabolism and bone mass accrual. However, study of therapeutic options other than calcium and vitamin D should be encouraged.

Growth retardation in pediatric Crohn's disease: pathogenesis and interventions

Growth retardation (GR) may pose a significant challenge to the quality of life and the proper management of children and adolescents with Crohn's disease (CD). It can occur in a significant proportion of patients, and may precede clinical evidence of bowel disease. Current evidence suggests that GR is a complex interaction between nutritional status, inflammation, disease severity, and genotype, which causes resistance to the effects of growth hormone. Recent research has identified a key role for the inflammatory cytokines TNF alpha, IL-6, and IL1 beta. This review summarizes current knowledge as well as gaps in our understanding of the mechanisms involved and the usefulness of the different treatment modalities in promoting growth in CD patients.

Serum phospholipid fatty acid pattern is associated with bone mineral density in children, but not adults, with cystic fibrosis

Essential fatty acids (EFA) have proved to be important for normal bone mineral density (BMD) and bone growth in animal studies. Patients with cystic fibrosis often have low serum EFA levels, and low BMD has also been reported in patients with normal anthropometry. The aim of the present study was to analyse if BMD during a 2-year period was related to fatty acid status in patients with cystic fibrosis. Fifty-four patients, aged 6–33 years, were studied prospectively. BMD was measured with dual X-ray absorptiometry, and fatty acid concentrations in serum phospholipids were determined with capillary GLC. The cystic fibrosis patients showed low linoleic acid concentration and a high arachidonic acid (AA):DHA ratio in serum. The high eicosatrienoic acid:AA ratio, an indicator of EFA deficiency, increased further over 2 years, as did the total concentration of saturated fatty acids. In the adults there were no significant changes in fatty acids during the study. In the children, positive correlations were found between palmitic acid and bone mineral content in the lumbar spine and femoral neck. The lumbar spine BMDZscore correlated negatively with the AA:DHA ratio. No correlation was seen in adults except for a positive correlation between EFA deficiency index and the areas of lumbar spine and femoral neck. The present results imply that fatty-acid status influenced BMD in cystic fibrosis children, but not in adults, indicating that fatty-acid status wouldbe important for bone growth.

Low bone mineral density in young children with cystic fibrosis

RATIONALE

Low bone mineral density (BMD) is a frequent problem for adult patients with cystic fibrosis (CF). Only limited information is available for young patients.

OBJECTIVES

The aim of this study was to evaluate BMD of children with CF younger than 6 years.

METHODS

BMD was measured at the lumbar spine (LS) after adjustment for height, sex, and pubertal status in 25 children with CF younger than 6 years, 53 prepubertal children aged 6 to 10 years, and 36 adolescents aged 11 to 18 years. Nutritional status, body composition, pulmonary disease severity, corticosteroid usage, dietary calcium, caloric intake, and vitamin D status were evaluated as potential correlates of BMD.

MEASUREMENTS AND MAIN RESULTS

The mean LS z score in the youngest group was significantly lower than normal (-0.96; SEM, 0.3). It did not differ significantly from that of children aged 6 to 10 years (-0.91; SEM, 0.2) or adolescents (-1.4; SEM, 0.2). LS z score was positively correlated with fat-free mass in multiple regression analysis. LS z score was less than -1 in 34% of the patients with mild pulmonary disease and normal nutritional status.

CONCLUSIONS

These data suggest that the origin of CF bone disease in early childhood may be independent of nutritional status or disease severity.

Insulin-like growth factor-1, leptin, body composition, and clinical status interactions in children with cystic fibrosis

BACKGROUND/AIMS

Children with cystic fibrosis (CF) are of increased risk of reduced fat body mass (FBM) and lean body mass (LBM). Serum concentrations of insulin-like growth factor-1 (IGF-1)and leptin could be markers of LBM and/or FBM depletion. To evaluate the relationships between disease activity, body composition, IGF-1 and leptin concentrations in CF children.

METHODS

A cross-sectional study with 26 CF children aged 5.0-15.5 years and 33 healthy controls, mean age 9.4 years. Body composition was evaluated by dual-energy X-ray absorptiometry. Fasting blood samples were analyzed for leptin, IGF-1 and IGFBP-3.

RESULTS

FBM standard deviation score (SDS; CF boys -0.02 +/- 0.88 vs. 0.78 +/- 0.65, p < 0.01; CF girls -0.37 +/- 1.15 vs. 0.70 +/- 0.97, p < 0.05), leptin concentration (CF boys 2.07 +/- 0.79 vs. 3.07 +/- 1.28 ng/ml, p < 0.05; CF girls 2.71 +/- 0.86 vs. 5.00 +/- 2.95 ng/ml, p < 0.05) and IGF-1SDS (CF boys -1.43 +/- 1.50 vs. -0.32 +/- 0.88, p < 0.05; CF girls -0.66 +/- 1.66 vs. 0.64 +/- 0.57, p < 0.01) were lower in CF children compared to controls. Shwachman score was the strongest predictor of lean body mass (R = 0.63). Leptin levels explain 60% of the variability in FBM.

CONCLUSION

Serum concentrations of IGF-1 and leptin are decreased in children with CF and are associated with clinical conditions and body composition.

Clinical utility of measurements of insulin-like growth factor 1

Plasma insulin-like growth factor 1 (IGF-I) concentrations are regulated by genetic factors, nutrient intake, growth hormone (GH) and other hormones such as T4, cortisol and sex steroids. The accuracy of IGF-I measurement in diagnosing GH deficiency or excess depends, in part, on the relative contributions of each of these variables. Since their respective influence may vary widely between individuals, the establishment of well-defined normal ranges is necessary, which requires adequate numbers of normal individuals, in order for IGF-I measurements to have maximum utility. In states of GH deficiency, the influence of these non-GH-related factors predominates. Although IGF-I levels have utility as a screening test in children and young adults, they cannot be used as a stand-alone test for the diagnosis of GH deficiency. By contrast, in acromegaly, GH is the predominant determinant of IGF-I levels and, therefore, measurement of IGF-I is a very useful diagnostic test. In acromegaly, IGF-I levels are useful for assessing the relative degree of GH excess, because changes in IGF-I correlate with changes in symptoms and soft-tissue growth. IGF-I is also very useful in monitoring the symptomatic response to therapy.

Relationship between insulin-like growth factor I, dehydroepiandrosterone sulfate and proresorptive cytokines and bone density in cystic fibrosis

INTRODUCTION

Patients with cystic fibrosis (CF) are known to be at risk for early osteoporosis, and the mechanisms that mediate bone loss are still being delineated. The aim of the present investigation was to investigate if a correlation exists in these patients between skeletal measurements by dual-energy x-ray absorptiometry (DXA) and two anabolic factors, dehydroepiandrosterone (DHEA) and insulin-like growth factor I (IGF-I), and proresorptive factors such as the cytokines interleukin-1beta, tumor necrosis factor alpha, and interleukin-6.

METHODS

We studied 32 outpatients (18 females; mean age: 26.2+/-7.9 years) at a tertiary care medical center. The subjects had venous samples obtained, underwent anthropometric and bone mineral density (BMD) measurements, and completed a health survey. Serum IGF-I concentrations were below the age-adjusted mean in 78% of the participants, and DHEA sulfate (DHEAS) concentrations were low in 72%. Serum concentrations of all cytokines were on the low side of normal; nonetheless, there was a modest inverse correlation between IL-1beta and BMD at all sites.

RESULTS

In univariate analyses, IGF-I and DHEAS were significant correlates of BMD or bone mineral content. In final multivariate models controlling for anthropometric and other variables of relevance to bone density, only IGF-I was identified as a significant independent skeletal predictor. While alterations in DHEAS, IGF-I, and specific cytokines may contribute to skeletal deficits in patients with CF, of these factors a low IGF-I concentration appears to be most strongly correlated with BMD.

CONCLUSIONS

These findings may have therapeutic implications for enhancing bone density in these patients.

Deficiency in type 1 insulin-like growth factor receptor in mice protects against oxygen-induced lung injury

Background

Cellular responses to aging and oxidative stress are regulated by type 1 insulin-like growth factor receptor (IGF-1R). Oxidant injury, which is implicated in the pathophysiology of a number of respiratory diseases, acutely upregulates IGF-1R expression in the lung. This led us to suspect that reduction of IGF-1R levels in lung tissue could prevent deleterious effects of oxygen exposure.

Methods

Since IGF-1R null mutant mice die at birth from respiratory failure, we generated compound heterozygous mice harboring a hypomorphic (Igf-1r^neo) and a knockout (Igf-1r^-) receptor allele. These IGF-1R^neo/- mice, strongly deficient in IGF-1R, were subjected to hyperoxia and analyzed for survival time, ventilatory control, pulmonary histopathology, morphometry, lung edema and vascular permeability.

Results

Strikingly, after 72 h of exposure to 90% O₂, IGF-1R^neo/- mice had a significantly better survival rate during recovery than IGF-1R^+/+ mice (77% versus 53%, P < 0.05). The pulmonary injury was consistently, and significantly, milder in IGF-1R^neo/- mice which developed conspicuously less edema and vascular extravasation than controls. Also, hyperoxia-induced abnormal pattern of breathing which precipitated respiratory failure was elicited less frequently in the IGF-1R^neo/- mice.

Conclusion

Together, these data demonstrate that a decrease in IGF-1R signaling in mice protects against oxidant-induced lung injury.