Serum concentrations of insulin-like growth factor-I, insulin-like growth factor binding protein-3 and cardiovascular risk factors in adolescents

IGF-1 and IGFBP3 as indirect markers of hepatic insulin resistance and their relation to metabolic syndrome parameters in liver steatosis patients

Objective. The aim of the present study was to assess insulin-like growth factor 1 (IGF-1) and IGF-binding protein 3 (IGFBP3) as markers of insulin resistance in patients with prediabetes and type 2 diabetes mellitus (TDM2). Patients and Methods. This observational clinical study included 76 obese/overweight patients at the age of 45-75 years with T2DM on oral diabetic medication and ultrasonographically or by a computerized tomography (CT) diagnosed liver steatosis. Correlation analysis was performed between plasma levels of insulin, C-peptide, IGF-1, IGFBP3 and HOMA indexes on the one hand and between plasma levels of ALT, AST, triglyceride, cholesterol, and HDL cholesterol and body mass index (BMI) of patients on the other hand. In case of significant partial correlation coefficients, a multiple linear regression model with IGF-1 and IGFBP3 used as outcome variables adjusted for age and sex groups was calculated. According to these regression models, ROC curves were prepared with HOMA index=3 used as a classificator of insulin resistance. Results. Significant correlation was found between C-peptide and IGF-1 (r=0.24, p≤0.05), C-peptide and IGFBP3 (r=0.24, p≤0.05), IGFBP3 and cholesterol (r=0.22, p≤0.05) IGFBP3 and ALT (r=0.19, p≤0.05), HOMA index and triglycerides (r=0.22, p≤0.05), and HOMA index and ALT (r=0.23, p≤0.05). Significant correlation adjusted for age and gender was found between C-peptide and IGF-1 plasma levels (R2=0.20, p<0.05) with AUROC 0.685 (p≤0.01) and C-peptide and IGFBP3 plasma levels (R2=0.28, p<0.05) with AUROC 0.684 (p≤0.01). Significant correlation adjusted for age and gender was found between triglyceride and IGFBP3 plasma levels (R2=0.28, p<0.05) with AUROC 0.616 (p≤0.01). After the distribution of patients according to their IGFBP3 levels, we found a difference between the 1st and the 4th quartiles in terms of triglyceride levels. Conclusion. Our results demonstrate a fundamental role of IGF-1 and IGFBP3 in the patho-physiology of hepatic insulin resistance and suggest them as indirect indicators of the hepatic insulin resistance.

Protein Intake from Birth to 2 Years and Obesity Outcomes in Later Childhood and Adolescence: A Systematic Review of Prospective Cohort Studies

Emerging evidence shows an association between protein intake during infancy and later obesity risk, and that association may differ by protein sources. This systematic review summarized and evaluated prospective cohort studies assessing the long-term association of total protein intake and protein sources during infancy (from birth to 2 y) with subsequent obesity outcomes in childhood or adolescence. Literature searches were conducted in Embase, Medline, Scopus, and Web of Science. Sixteen studies that reported associations between total protein intake and/or protein intake from different sources from birth to 2 y and ≥1 obesity outcomes in childhood or adolescence from 9 cohorts were identified. Most studies (11/16) were rated as high quality. The most frequently reported association was total protein intake and BMI (up to 10 y) with 6 out of 7 cohorts showing significant positive associations. Similar associations were found for animal protein, but not for plant protein. Limited studies examined the association between protein intake (both total and sources) and body composition (body fat, fat mass, and fat-free mass) and revealed inconsistent findings. Overall, higher intakes of total and animal protein during infancy were associated with higher BMI in childhood and adolescence. Future studies investigating the contribution of protein sources in long-term obesity development are needed. This review was registered at PROSPERO as CRD42020166540.

Insulin-Like Growth Factor 1 in the Cardiovascular System

Non-communicable diseases, such as cardiovascular diseases, are the leading cause of mortality worldwide. For this reason, a tremendous effort is being made worldwide to effectively circumvent these afflictions, where insulin-like growth factor 1 (IGF1) is being proposed both as a marker and as a central cornerstone in these diseases, making it an interesting molecule to focus on. Firstly, at the initiation of metabolic deregulation by overfeeding, IGF1 is decreased/inhibited. Secondly, such deficiency seems to be intimately related to the onset of MetS and establishment of vascular derangements leading to atherosclerosis and finally playing a definitive part in cerebrovascular and myocardial accidents, where IGF1 deficiency seems to render these organs vulnerable to oxidative and apoptotic/necrotic damage. Several human cohort correlations together with basic/translational experimental data seem to confirm deep IGF1 implication, albeit with controversy, which might, in part, be given by experimental design leading to blurred result interpretation.

Aging and sex affect soluble alpha klotho levels in bonobos and chimpanzees

BACKGROUND

Throughout life, physiological homeostasis is challenged and the capacity to cope with such challenges declines with increasing age. In many species, sex differences exist in life expectancy. Sex-specific differences have been related to extrinsic factors like mate competition and/or intrinsic proximate mechanisms such as hormonal changes. In humans, an intrinsic factor related to aging is soluble alpha klotho (α-Kl). Both sexes show an age-related decline in α-Kl, but throughout life women have higher levels than men of the same age. Sex differences in α-Kl have been linked to a shorter lifespan, as well as to specific morbidity factors such as atherosclerosis and arteries calcifications. In non-human animals, information on α-Kl levels is rare and restricted to experimental work. Our cross-sectional study is the first on α-Kl levels in two long-lived species: bonobos (Pan paniscus) and chimpanzees (Pan troglodytes). As in most mammals, female bonobos and chimpanzees have longer life expectancy than males.

METHODS

We measured serum α-Kl levels of 140 subjects from 16 zoos with an ELISA to examine if α-Kl levels reflect this difference in life expectancy.

RESULTS

In both species and in both sexes, α-Kl levels declined with age suggesting that this marker has potential for aging studies beyond humans. We also found species-specific differences. Adult female bonobos had higher α-Kl levels than males, a difference that corresponds to the pattern found in humans. In chimpanzees, we found the opposite: males had higher α-Kl levels than females.

CONCLUSION

We suggest that contrasting sex differences in adult α-Kl levels mirror the dominance relations between females and males of the two Pan species; and that this might be related to corresponding sex differences in their exposure to stress. In humans, higher cortisol levels were found to be related to lower α-Kl levels. We conclude that there is great potential for studying aging processes in hominoids, and perhaps also in other non-human primates, by measuring α-Kl levels. To better understand the causes for sex differences in this aging marker, consideration of behavioural parameters such as competition and stress exposure will be required as well as other physiological markers.

SERUM INSULIN-LIKE GROWTH FACTOR 1 IN LEBANESE SCHOOLCHILDREN AND ITS RELATION TO VITAMIN D AND FERRITIN LEVELS

OBJECTIVE

The aims of our study were to establish reference values for insulin-like growth factor 1 (IGF-1) in Lebanese schoolchildren and to evaluate the relationship between IGF-1 and age, sex, body mass index (BMI), vitamin D, and ferritin.

METHODS

This cross-sectional study included 952 Lebanese schoolchildren (495 boys and 457 girls) aged 8 to 18 years. Blood samples were taken from children attending 10 schools with different socio-economic status (SES). Chemiluminescent immunoassays were used for IGF-1, 25 hydroxyvitamin D (25(OH)D), testosterone, and ferritin measurements.

RESULTS

The mean age was 13.46 ± 2.80 with no significant difference according to sex. IGF-1 was correlated with age in both sexes (P<.0001); it was higher in girls compared to boys (P = .007) and peaked at the ages of 14 and 12 for boys and girls, respectively. For each age group, the median IGF-1 value was higher compared to the values provided by the kit. IGF-1 was significantly correlated with BMI in boys (r = 0.16, P<.0001) but not girls. In both sexes, IGF-1 was inversely correlated with 25(OH)D and ferritin values. After adjustment for age, BMI, and height, the correlation between IGF-1 and 25(OH)D disappeared, whereas the relationship with ferritin persisted (P<.001 for boys, P = .002 for girls). For both sexes, multivariate regression analysis revealed independent associations between IGF-1 and height, Tanner stage, and ferritin. An association was also noted in boys for BMI and testosterone.

CONCLUSION

Our results showed higher and earlier peak IGF-1 values in the pediatric Lebanese population compared to western populations. In addition, an independent inverse relationship was observed between IGF-1 and ferritin. Further studies are needed to identify the reason(s) underlying these results.

ABBREVIATIONS

BMI = body mass index CRP = C-reactive protein CV = coefficient of variation GH = growth hormone IGF-1 = insulin-like growth factor 1 25(OH)D = 25 hydroxyvitamin D SES = socio-economic status TSH = thyroid-stimulating hormone.

Insulin-like growth factor-I and insulin-like growth factor binding protein-1 are related to cardiovascular disease biomarkers in obese adolescents

CONTEXT

Insulin-like growth factor (IGF)-I and IGF binding protein (IGFBP)-1 have been linked to cardiovascular disease (CVD) risk and pathophysiology in adults, but there are limited data in youth.

OBJECTIVE

The aim of the study was to examine the relationship between IGF and IGFBP-1 with traditional and non-traditional CVD risk factors including inflammatory markers and body composition in an obese pediatric cohort.

DESIGN

A cross-sectional study.

SETTING

The study was carried out at a university children's hospital.

SUBJECTS

Sixty-one obese non-diabetic adolescents.

OUTCOMES

Fasting IGF-I, IGFBP-1, lipoprotein profiles, high-sensitivity C-reactive protein (hsCRP), and total adiponectin as well as insulin sensitivity measures, blood pressure (BP), and anthropometrics.

RESULTS

IGFBP-1 was negatively associated with insulin sensitivity measures, body mass index (BMI), and diastolic BP in males. IGF-I was negatively associated with hsCRP (r = -0.479, p < 0.0005), and IGFBP-1 was positively associated with adiponectin (r = 0.545, p < 0.0005). The IGF-I/CRP and IGFBP-1/adiponectin associations remained significant when controlling for both BMI and insulin sensitivity index (SI ). Both IGF-I and IGFBP-1 were negatively associated with waist circumference (r = -0.327 and r = -0.275, respectively) and sagittal abdominal diameter (r = -0.333 and r = -0.371, respectively), while IGFBP-1 was negatively associated with fat mass (r = -0.347, p = 0.01) as well as neck circumference and fat-free mass in males. Controlling for BMI z-score and SI , IGFBP-1 remained negatively associated with diastolic blood pressure (r = 0.706, p = 0.001 and neck circumference (r = -0.548, p = 0.15) in males.

CONCLUSIONS

IGF-I and IGFBP-1 associate with CVD risk markers and may add to clinical assessments of cardiometabolic dysfunction in youth.

Metformin treatment to reduce central adiposity after prenatal growth restraint: a placebo-controlled pilot study in prepubertal children

BACKGROUND

Children born small-for-gestational-age (SGA) who experience rapid postnatal catch-up in weight are at risk for central adiposity and hyperinsulinemia.

OBJECTIVES

To study the effects of prepubertal metformin intervention over 24 months on the body composition and endocrine-metabolic profile of catch-up SGA children.

METHODS

Double-blind, placebo-controlled, pilot study including 23 post-catch-up non-obese prepubertal SGA children [age, 7.7 yr; body mass index standard deviation score (BMI SDS) >50th and <97th centile for age] with increased visceral fat [by magnetic resonance imaging (MRI) and insulin-like growth factor-I (IGF-I) both p > 75th for age]. Patients were randomized to receive either placebo or metformin (425 mg/d) for 24 months. Clinical, biochemical [IGF-I, glucose, insulin, lipids, androgens, sex-hormone-binding globulin (SHBG) and high-molecular-weight (HMW)-adiponectin] and imaging [body composition (absorptiometry and MRI; carotid intima-media thickness (ultrasonography)] variables were assessed at baseline, and at 6, 12, and 24 months.

RESULTS

After 24 months, metformin-treated children were leaner, had higher SHBG levels, and less total and abdominal fat than placebo-treated children (all p ≤ 0.05). Longitudinal analyses showed that metformin had a significant effect on anthropometric (weight, BMI, and waist) and biochemical variables [glucose, homeostasis model assessment-insulin resistance (HOMA-IR), and triglycerides] (all p ≤ 0.05); and in total and abdominal fat (p = 0.01 and p = 0.02).

CONCLUSIONS

Prepubertal intervention with metformin reduces central adiposity and improves insulin sensitivity in non-obese catch-up SGA children.

The Insulin-Like Growth Factor System in Obesity, Insulin Resistance and Type 2 Diabetes Mellitus

The insulin-like growth factor (IGF) system, acting in concert with other hormone axes, is important in normal metabolism. In obesity, the hyperinsulinaemia that accompanies peripheral insulin resistance leads to reduced growth hormone (GH) secretion, while total IGF-I levels are relatively unchanged due to increased hepatic GH sensitivity. IGF-binding protein (IGFBP)-1 levels are suppressed in relation to the increase in insulin levels in obesity and low levels predict the development of type 2 diabetes several years later. Visceral adiposity and hepatic steatosis, along with a chronic inflammation, contribute to the IGF system phenotype in individuals with metabolic syndrome and type 2 diabetes mellitus, including changes in the normal inverse relationship between IGFBP-1 and insulin, with IGFBP-1 concentrations that are inappropriately normal or elevated. The IGF system is implicated in the vascular and other complications of these disorders and is therefore a potential therapeutic target.

Association between insulin-like growth factor-1, measures of overnutrition and undernutrition and insulin resistance in black adolescents living in the North-West Province, South Africa

OBJECTIVE

To determine if insulin-like growth factor-1 (IGF-1) is a significant predictor of body fat percentage (%BF), lean body mass, and insulin resistance (IR) in black adolescents presenting with overnutrition and undernutrition.

METHODS

A cross-sectional study was undertaken in 181 adolescents (111 girls, 70 boys, 13-20 years old) from a low socio-economic population in the North-West Province, South Africa. Anthropometric measurements were performed, and %BF and lean mass were assessed by air displacement plethysmography. Serum glucose, leptin, insulin, IGF-1 and IGF-binding protein-3 (IGFBP-3) were measured and homeostasis model assessment of IR (HOMA-IR) was calculated. Predictors of body composition and HOMA-IR were determined in multivariate linear regressions.

RESULTS

Of the boys, 31% had a %BF >20%, whereas 42% of girls had a %BF >30%. Furthermore, 17.1% male and 18.9% female adolescents were stunted, indicating overnutrition and undernutrition in the same group. IGF-1 showed a negative association with %BF in both sexes, and a positive correlation with height-for-age z-score (HAZ) and lean mass, respectively, in the boys. IGF-1 correlated positively and physical activity correlated negatively with fasting insulin and HOMA-IR in the girls. In both sexes, leptin had the strongest association with %BF in multiple regressions. Leptin and Tanner stage were significant predictors of HOMA-IR in girls, but not in boys.

CONCLUSIONS

IGF-1 was positively associated with lean mass and HAZ in boys, indicating a beneficial relationship with linear growth, but with IR in the girls, indicating possible adverse metabolic effects in the presence of high %BF and physical inactivity.

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.

The maternal womb: a novel target for cancer prevention in the era of the obesity pandemic?

The dramatic rise in worldwide prevalence of obesity has necessitated the search for more efficacious antiobesity strategies to counter the increased cancer risks in overweight and obese individuals. The mechanistic pathways linking obesity status with adult chronic diseases such as cancer remain incompletely understood. A growing body of evidence suggests that novel approaches and interventional agents to disrupt the feed-forward cycle of maternal to offspring obesity transfer that is initiated in utero will be important for stemming both the obesity pandemic and the associated increase in cancer incidence. The convergence of multiple research areas including those encompassing the insulin and insulin-like growth factor systems, epigenetics, and stem cell biology is providing insights into the potential for cancer prevention in adult offspring previously exposed to the intrauterine environment of overweight/obese mothers. Here, we review the current state of this nascent research field, with a focus on three major cancers, namely breast, colorectal, and liver, and suggest some possible future directions to optimize its impact for the health of future generations.