Reduction in Pappalysin-2 Levels and Lower IGF-I Bioavailability in Female Adolescents With Anorexia Nervosa.

CONTEXT: Anorexia nervosa (AN) can cause severe undernutrition associated with alterations in the IGF axis. Pappalysins (PAPP-A, PAPP-A2) and stanniocalcins (STC-1, STC-2) modulate IGF binding-protein (IGFBP) cleavage and IGF bioavailability, but their implications in AN are unknown. OBJECTIVE: We determined serum levels of PAPP-As and STCs in relationship with classical IGF axis parameters in female adolescents with AN and their association with nutritional status and secondary amenorrhea. METHODS: Parameters of the IGF axis were determined in fasting serum samples of 68 female adolescents with AN at diagnosis and 62 sex- and age-matched controls. Standardized body mass index (BMI) and bone mineral density (BMD) were calculated. RESULTS: Patients with AN had lower concentrations of total and free IGF-I, total IGFBP-3, acid-labile subunit (ALS), insulin, PAPP-A2, STC-1, and STC-2 and higher levels of IGF-II and IGFBP-2. Their free/total IGF-I ratio was decreased and the intact/total IGFBP-3 and -4 ratios increased. BMI was directly related to total IGF-I and intact IGFBP-3 and inversely with IGFBP-2 and intact IGFBP-4. Weight loss was directly correlated with intact IGFBP-4 and negatively with intact IGFBP-3, ALS, STC-2, and PAPP-A2 concentrations. BMD was directly related to intact IGFBP-3 and inversely with intact IGFBP-4 and PAPP-A2 levels. Patients with amenorrhea had lower levels of total IGF-I and IGFBP-3 than those with menses. CONCLUSION: The reduction of PAPP-A2 in patients with AN may be involved in a decline in IGFBP cleavage, which could underlie the decrease in IGF-I bioavailability that is influenced by nutritional status and amenorrhea.

Increased IGFBP proteolysis, IGF-I bioavailability and pappalysin levels in children with Prader-Willi syndrome.

CONTEXT: Prader-Willi syndrome (PWS) is associated with impaired growth hormone (GH) secretion and decreased insulin-like growth factor (IGF)-I levels. Pappalysins (PAPP-A, PAPP-A2) and stanniocalcins (STC-1, STC-2) regulate IGF binding-protein (IGFBP) cleavage and IGF bioavailability, but their implication in PWS is unknown. OBJECTIVE: We determined serum levels of PAPP-As and STCs in association with IGF axis components in pre- and pubertal patients with PWS, also analyzing the effect of GH treatment. METHODS: Forty children and adolescents with PWS and 120 sex- and age-matched controls were included. The effect of GH was evaluated at six months of treatment in 11 children. RESULTS: Children with PWS had lower levels of total IGF-I, total and intact IGFBP-3, acid-labile subunit, intact IGFBP-4, and STC-1, and higher concentrations of free IGF-I, IGFBP-5 and PAPP-A. Patients with PWS after pubertal onset had decreased total IGF-I, total and intact IGFBP-3, and intact IGFBP-4 levels, and increased total IGFBP-4, and STCs concentrations. GH treatment increased total IGF-I, total and intact IGFBP-3, and intact IGFBP-4, with no changes in PAPP-As, STCs and free IGF-I levels. Standardized height correlated directly with intact IGFBP-3 and inversely with PAPP-As and the free/total IGF-I ratio. CONCLUSION: The increase in PAPP-A could be involved in increased IGFBP proteolysis, promoting IGF-I bioavailability in children with PWS. Further studies are needed to establish the relationship between growth, GH resistance, and changes in the IGF axis during development and after GH treatment in these patients.

Differential basal and exercise-induced IGF-I system responses to resistance vs. calisthenic-based military readiness training programs.

OBJECTIVE: The purpose of this study was to: 1) evaluate differential responses of the IGF-I system to either a calisthenic- or resistance exercise-based program and 2) determine if this chronic training altered the IGF-I system during an acute resistance exercise protocol. DESIGN: Thirty-two volunteers were randomly assigned into a resistance exercise-based training (RT) group (n=15, 27±5y, 174±6cm, 81±12kg) or a calisthenic-based training group (CT) (n=17, 29±5y, 179±8cm, 85±10kg) and all underwent 8weeks of exercise training (1.5h/d, 5d/wk). Basal blood was sampled pre- (Week 0), mid- (Week 4) and post-training (Week 8) and assayed for IGF-I system analytes. An acute resistance exercise protocol (AREP) was conducted preand post-training consisting of 6 sets of 10 repetitions in the squat with two minutes of rest in between sets and the IGF-I system analytes measured. A repeated measures ANOVA (p≤0.05) was used for statistical analysis. RESULTS: No interaction or within-subject effects were observed for basal total IGF-I, free IGF-I, or IGFBP-1. IGFBP-2 (pre; 578.6±295.7post-training; 14.3±1.9µg/mL; p=0.01). An interaction was observed for the RT group as IGFBP-3 increased from pre to mid (3462.4±216.4 vs. 3962.2±227.9ng/mL), but was not significant at the post-training time point (3770.3±228.7ng/mL). AREP caused all analytes except free IGF-I (40% decrease) to increase (17-27%; p=0.001) during exercise, returning to baseline concentration into recovery. CONCLUSION: Post-training, bioavailable IGF-I recovered more rapidly post-exercise. 8wks of chronic physical training resulted in increased basal IGFBP-2 and IGFBP-3, decreased ALS, increased pre-AREP free IGF-I and a more rapid free IGF-I recovery post-AREP. While total IGF-I was insensitive to chronic physical training, changes were observed with circulating IGFBPs and bioavailable IGF-I. To glean the most robust information on the effects of exercise training, studies must move beyond relying solely on total IGF-I measures and should consider IGFBPs and bioavailable IGF-I as these components of the circulating IGF-I system are essential determinants of IGF-I physiological action.

Circulating IGF-axis protein levels and their relation with levels of plasma adipocytokines and macronutrient consumption in women.

OBJECTIVE: Circulating free insulin-like growth factor (IGF)-I and its binding proteins, most notably, IGFBP-1 and IGFBP-2, have been prospectively associated with incident type 2 diabetes in women. However, little is known regarding the factors that may influence these IGF-axis protein levels. The aim is to study the relation of IGF-axis protein levels with adipcytokines, macronutrient consumption, and other factors related to diabetes. DESIGN: Fasting plasma from 558 controls enrolled in a nested case-control study within the Nurses' Health Study of incident type 2 diabetes in women was tested for: IGF-axis proteins (free and total IGF-I, IGFBP-1, IGFBP-2, IGFBP-3), adipocytokines (leptin, adiponectin, resistin), soluble leptin receptor (sOB-R), inflammatory factors (IL-18 and C-reactive protein (CRP)), insulin, and glycated hemoglobin (HbA1C). RESULTS: In multivariate models, each 1% increase in sOB-R (mean 34.9ng/mL, standard deviation (SD) ±11.3) was associated with -0.20% total IGF-I (P=0.0003) and -0.42% free IGF-I (P=0.002), as well as 0.73% higher IGFBP-1 (P<0.0001) and 0.27% IGFBP-2 (P=0.003). For example, a one SD change from the mean sOB-R level was associated with 11% lower free IGF-I. Insulin levels (mean 6.8µU/mL±5.3) were inversely and adiponectin (mean 18.3µg/mL±7.4) positively associated with IGFBP-1 and IGFBP-2 (all P<0.01). Consumption of dairy protein, monounsaturated fats, and saturated fats, was also correlated with IGF-axis protein levels (all P<0.05). CONCLUSIONS: Several molecular factors and macronutrients were independently associated with plasma IGF-axis protein levels. Which of these, if any, reflect biologic relationships that can be intervened upon to influence IGF-axis protein concentrations warrants further investigation.

The Effect of Obesity on Serum Growth Factors, and Insulin-like Growth Factor Binding Protein-3 Proteolysis in Children with Simple Obesity / 대한소아내분비학회지

PURPOSE: In children with simple obesity, spontaneous and stimulated growth hormone (GH) secretion are diminished, but their heights usually are normal or even taller for their age and sex. The exact mechanism to explain the discrepancy between impaired GH secretion and normal height velocity has not been elucidated. In this study, we aimed to determine the level of serum growth factors, and the degree of insulin-like growth factor binding protein (IGFBP)-3 proteolysis, and to assess the alteration of the IGF system associated with accelerated or normal growth in simple obesity. METHODS: We evaluated serum growth factors, and IGFBP-3 proteolysis in 27 obese, 25 obesity risk group, and 28 age-matched control group. We measured serum levels of insulin-like growth factor (IGF)-I, IGFBP-1, -3, and free IGF-I by immuno-radiometric assay and IGFBP-3 fragment by Western immunoblotting. RESULTS: The height was taller in obese children than in lean control group. The results showed no significant difference in the level of serum total IGF-1 and IGFBP-3 between obese and normal control group. Although there was no significant difference in other components, serum free IGF-I levels were significantly increased (P<0.05) and showed positive correlation with their height in obese children (r=0.25, P<0.05). The degree of IGFBP-3 proteolysis was increased in obesity and obesity risk group compared to control group. The densities of the IGFBP-3 proteolytic fragment approximate 18 kDa also showed positive correlation with levels of free IGF-I (r=0.23, P<0.05) and height (r=0.19, P<0.05). CONCLUSION: These findings may suggest that elevated levels of serum IGFBP-3 proteolytic fragments showing decreased affinity to IGF-I result in the increase of biologically active free IGF-I, thereby maintain normal growth in the obese children.

Serum IGF-I, Free IGF-I, IGFBP-1, IGFBP-3 Levels in Children with Intrauterine Growth Retardation / 대한소아내분비학회지

PURPOSE:Most but not all intrauterine growth retardation(IUGR) children has catch-up growth postnatally. However, nothing is known about the predictive parameters on the catch-up growth. The aim of this study was to describe serum IGF-I, free IGF-I, IGFBP-1, and IGFBP-3 levels in IUGR children and to correlate these hormone values with auxologic parameters to investigate their value on the postnatal growth pattern. METHODS:Among children with IUGR born at Ewha Womans University from Jan. 1995 to Aug. 1998, 16 children with IUGR at 3 years of age and 12 age-matched normal controls were studied for auxologic and biologic parameters. We measured height, weight, and serum levels of insulin-like growth factor(IGF)-I, free IGF-I, IGF binding protein(BP)-1, IGFBP-3 using immunoradiometric kits. RESULTS: 1)Among 16 children with IUGR at 3 years of age, 13 children had catch-up growth(81.3%), but 3 children remained short stature(18.7%). The height standard deviation score(SDS) in children with IUGR and control were -0.3+/-0.8 and 0.8+/-0.7, respectively(P0.05). 2)Serum IGF-I levels in children with IUGR at 3 years of age and normal control were 90.9+/-35.4ng/mL and 68.4+/-24.4ng/mL, respectively(p>0.05) and free IGF-I were 0.9+/-0.5ng/mL and 0.6+/-0.3ng/mL(p>0.05), IGFBP-1 were 50.5+/-30.5ng/ mL and 52.3+/-23.2ng/mL(p>0.05), IGFBP-3 were 4,116.7+/-1,062.2ng/mL and 4,058.4+/-808.5ng/mL(p>0.05), respectively. 3)In children with IUGR at 3 years of age, height SDS in IUGR children with catch-up growth and those without catch-up growth were 0.002+/-0.6 and -1.5+/-0.7, respectively(P<0.001), but there were no differences in weight SDS, body mass index, IGF-I, free IGF-I, IGFBP-1 and IGFBP-3. 4)There were no significant correlations between height gain and any growth factors. CONCLUSION: The results show that there is no difference in the levels of IGF-I, free IGF-I, IGFBP-1 and IGFBP-3 in IUGR children at 3 years of age compared to age-matched normal control, suggesting that other factors rather than IGF-I, free IGF-I, IGFBP-1, IGFBP-3 may cause short stature in IUGR.

Growth Status and Levels of Growth Factors in Children with Insulin-dependent Diabetes Mellitus

PURPOSE: It is well known that the linear growth velocity in children with insulin-dependent diabetes mellitus (type 1 DM) is closely related to metabolic control and onset age of the disease. Many studies have demonstrated growth impairment in children with type 1 DM, regardless of the degree of metabolic control, whereas other studies have found no growth retardation. Therefore, we examined the growth status and the level of growth factors in children with type 1 DM, and compared them with healthy children. METHODS: Thirty-six patients with type 1 DM (21 female, 15 male; mean age, 10.8 years : range, 5-15 years)were studied. The mean duration of type 1 DM in these patients was 2.7 years (range, 0.1-7.0 years). Their growth status in height standard deviation score (HTSDS) and levels of insulin-like growth factor (IGF)-I, free IGF-I, IGF-II and IGF-binding protein (IGFBP)-3 were compared with age and sex matched normal children (21 female, 15 male; mean age, 10.3 years; range, 5-15 years). RESULTS: As HTSDS in type 1 DM, children were 0.4 +/- 1.1, no prominent growth impairment was observed in type 1 DM children. IGF-I and IGF-II levels decreased significantly in type 1 DM, but no significant differences in free IGF-I and IGFBP-3 levels compared to normal. Height in type 1 DM children was in direct correlation with free IGF-I (r=0.35, P<0.05) and IGFBP-3 (r= 0.45, P<0.01), respectively. CONCLUSION: This study reveals that the levels of IGF-I and -II are decreased in children with type 1 DM, whereas free IGF-I levels are not. These findings may be related to the decreased IGFBP-3 levels in diabetic children, and may explain no growth impairment, except in cases of extremely poor metabolic control.

Growth Status and Levels of Growth Factors in Children with Insulin-dependent Diabetes Mellitus

PURPOSE: It is well known that the linear growth velocity in children with insulin-dependent diabetes mellitus (type 1 DM) is closely related to metabolic control and onset age of the disease. Many studies have demonstrated growth impairment in children with type 1 DM, regardless of the degree of metabolic control, whereas other studies have found no growth retardation. Therefore, we examined the growth status and the level of growth factors in children with type 1 DM, and compared them with healthy children. METHODS: Thirty-six patients with type 1 DM (21 female, 15 male; mean age, 10.8 years : range, 5-15 years)were studied. The mean duration of type 1 DM in these patients was 2.7 years (range, 0.1-7.0 years). Their growth status in height standard deviation score (HTSDS) and levels of insulin-like growth factor (IGF)-I, free IGF-I, IGF-II and IGF-binding protein (IGFBP)-3 were compared with age and sex matched normal children (21 female, 15 male; mean age, 10.3 years; range, 5-15 years). RESULTS: As HTSDS in type 1 DM, children were 0.4 +/- 1.1, no prominent growth impairment was observed in type 1 DM children. IGF-I and IGF-II levels decreased significantly in type 1 DM, but no significant differences in free IGF-I and IGFBP-3 levels compared to normal. Height in type 1 DM children was in direct correlation with free IGF-I (r=0.35, P<0.05) and IGFBP-3 (r= 0.45, P<0.01), respectively. CONCLUSION: This study reveals that the levels of IGF-I and -II are decreased in children with type 1 DM, whereas free IGF-I levels are not. These findings may be related to the decreased IGFBP-3 levels in diabetic children, and may explain no growth impairment, except in cases of extremely poor metabolic control.

Characteristics of Serum Insulin-like Growth Factor ( IGF ) and IGF-Bindign Protein-3 during Pregnancy / 대한내분비학회지

BACKGROUND: Pregnancy in human and rodents is associated with dramatic matemal metabolic changes. Insulin-like growth factors (IGFs) are mitogenic peptides that are essential for fetal and maternal tissue growth during pregnancy. They circulate complexed primarily with a serum IGF-binding protein (IGFBP-3) which regulates the availability of the IGFs to their specific target tissues. METHODS: To examine the changes of IGFs and IGFB-3 during pregnancy, we measured serum total IGF-I, free IGF-I, IGF-II and IGFBP-3 by using specific radioimmunoassay, immunoradio-metric assay, western ligand blot and western immunoblot. Blood samples were obtained from 88 pregnant women between 6-40 weeks gestation. RESULTS: While serum IGF-I levels increased up to 50% in late pregnancy, serum IGF-II levels remained unchanged. However, serum free IGF-I levels were significantly higher during pregnancy than in nonpregnancy. Western ligand blot analysis revealed that IGFBP-3 in pregnancy serum was significantly decreased at 6 weeks of gestation, continued decreased level until term, and returned to a nonpregnant level by postpartum 10 day. Serum IGFBP-3 profiles in Western immunoblot analysis revealed that 30 kDa fragments of IGFBP-3 were detectable in pregnancy serum but not in nonpregnancy serum. In contrast, serum IGFBP-3 levels using radioimmunoassay was significantly increased in late pregnancy. CONCLUSIONS: 1) serum IGF-I was significantly elevated in late pregnancy 2) serum IGF-II was not significantly changed 3) free IGF-I significantly elevated throughout gestation 4) intact IGFBP-3 was markedly reduced after 6 weeks of gestation.