Positive association between plasma IGF1 and high-density lipoprotein cholesterol levels in adult nondiabetic subjects

Identification of genetic drivers of plasma lipoprotein size in the Diversity Outbred mouse population

Despite great progress in understanding lipoprotein physiology, there is still much to be learned about the genetic drivers of lipoprotein abundance, composition, and function. We used ion mobility spectrometry to survey 16 plasma lipoprotein subfractions in 500 Diversity Outbred mice maintained on a Western-style diet. We identified 21 quantitative trait loci (QTL) affecting lipoprotein abundance. To refine the QTL and link them to disease risk in humans, we asked if the human homologs of genes located at each QTL were associated with lipid traits in human genome-wide association studies. Integration of mouse QTL with human genome-wide association studies yielded candidate gene drivers for 18 of the 21 QTL. This approach enabled us to nominate the gene encoding the neutral ceramidase, Asah2, as a novel candidate driver at a QTL on chromosome 19 for large HDL particles (HDL-2b). To experimentally validate Asah2, we surveyed lipoproteins in Asah2-/- mice. Compared to wild-type mice, female Asah2-/- mice showed an increase in several lipoproteins, including HDL. Our results provide insights into the genetic regulation of circulating lipoproteins, as well as mechanisms by which lipoprotein subfractions may affect cardiovascular disease risk in humans.

Relationship between circulating insulin-like growth factor-1 and blood pressure in adults: A systematic review and meta-analysis of observational studies

OBJECTIVE

Insulin-like growth factor 1 (IGF-1) is an important factor related to cardiovascular disease. In recent years, studies have shown the involvement of IGF-1 and blood pressure (BP). Nevertheless, the results were inconsistent. Thus, the purpose of this study was to systematically evaluate the associations of circulating IGF-1 levels with BP in adults.

METHODS

Two reviewers independently searched and screened articles from the Pubmed, EMBASE, Cochrane Library, CNKI, and WANFANG databases up to May 2020. A total of 12 studies that reported the correlation coefficients between IGF-1, systolic blood pressure (SBP), and diastolic blood pressure (DBP) were included.

RESULTS

IGF-1 was significantly correlated with SBP [r = -0.15; 95% CI = -0.21, -0.08; P < 0.0001] and DBP [r = -0.10; 95% CI = -0.16, -0.05; P = 0.0004]. Subgroup analysis further revealed that the relationship between IGF-1 and BP was influenced by race and age.

CONCLUSION

Circulating IGF-1 was negatively correlated with SBP and DBP. Further researches are necessary to explore the pathogenesis of this relationship and to evaluate the role of IGF-1 in the treatment of hypertension.

Hepatic Igf1-Deficiency Protects Against Atherosclerosis in Female Mice

Atherosclerosis is the leading cause of cardiovascular disease (CVD), with distinct sex-specific pathogenic mechanisms that are poorly understood. Aging, a major independent risk factor for atherosclerosis, correlates with a decline in circulating insulin-like growth factor-1 (IGF-1). However, the precise effects of Igf1 on atherosclerosis remain unclear. In the present study, we assessed the essential role of hepatic Igf1, the major source of circulating IGF-1, in atherogenesis. We generated hepatic Igf1-deficient atherosclerosis-prone apolipoprotein E (ApoE)-null mice (L-Igf1-/-ApoE-/-) using the Cre-loxP system driven by the Albumin promoter. Starting at 6 weeks of age, these mice and their littermate controls, separated into male and female groups, were placed on an atherogenic diet for 18 to 19 weeks. We show that hepatic Igf1-deficiency led to atheroprotection with reduced plaque macrophages in females, without significant effects in males. This protection from atherosclerosis in females was associated with increased subcutaneous adiposity and with impaired lipolysis. Moreover, this impaired lipid homeostasis was associated with disrupted adipokine secretion with reduced circulating interleukin-6 (IL-6) levels. Together, our data show that endogenous hepatic Igf1 plays a sex-specific regulatory role in atherogenesis, potentially through athero-promoting effects of adipose tissue-derived IL-6 secretion. These data provide potential novel sex-specific mechanisms in the pathogenesis of atherosclerosis.

Cardiometabolic Changes in Response to a Calorie-Restricted DASH Diet in Obese Older Adults

Objective: To examine the response of a calorie-restricted Dietary Approaches to Stop Hypertension diet on indicators of cardiometabolic health in a cohort of sedentary obese older adults. Design: This was a controlled-feeding trial with a parallel design. Each participant consumed either 3 oz (85 g; n = 15) or 6 oz (170.1 g; n = 13) of lean fresh beef within a standardized calorie-restricted DASH-like diet for 12-weeks. Fasted blood samples were collected and used to measure conventional biomarkers of cardiovascular, metabolic and inflammatory health. Participants: Caucasian older (70.8 years), obese (BMI: 32 ± 6.9 kg/m²; WC: 101 ± 16.4 cm) females (n = 17) and males (n = 11) from the rural community of Brookings, South Dakota. Results: 28 participants completed the 12-week feeding trial, with no differences (p > 0.05) among the biomarkers of cardiometabolic health between the 3 and 6 oz beef intake groups. However, when the beef intake groups were combined, all biomarkers changed concentration in response to the intervention diet. Total cholesterol (p < 0.001), LDL-C (p = 0.004), HDL-C (p < 0.0001), insulin (p = 0.014), glucose (p = 0.008), HOMA-IR (p < 0.05), IL-12 (p < 0.001), and CRP (p = 0.006) all decreased in response to the study diet. IGF-1 (p < 0.001) and IL-8 (p = 0.005) increased in response to the intervention. Correlations among cardiometabolic biomarkers and body composition measures were observed. By study end, the decrease in insulin (R ² = 0.22; P = 0.012) and HOMA-IR (R ² = 0.22; P = 0.01) was positively correlated with the decrease in waist circumference. The increase in IGF-1 was significantly correlated with the decrease in waist circumference (R ² = 0.21; p = 0.014). The increase in IGF-1 was significantly correlated with the increase in sit-to-stand (R ² = 0.21; p = 0.016). The increase in IL-8 was significantly correlated with decreases in total cholesterol (R ² = 0.24; P = 0.008), LDL-C (R ² = 0.17; P = 0.031) and glucose (R ² = 0.44; P = 0.0001). Conclusions: These findings suggest that a DASH-like diet with restricted calories may potentially improve biomarkers of cardiometabolic health in sedentary obese older adults. These results also point to interrelationships between body composition changes and changes in cardiometabolic biomarkers. Lastly, regardless of meat intake amount, positive impacts on cardiometabolic biomarkers were observed in this cohort of older adults with an obese phenotype.

Skipping Breakfast Is Associated with an Atherogenic Lipid Profile in Overweight and Obese Prepubertal Children

BACKGROUND

Skipping breakfast has been associated with a higher risk of obesity and cardiovascular (CV) risk factors. However, it is not known if skipping breakfast is also correlated with CV risk factors independently from obesity. The mechanisms explaining the role of skipping breakfast on promoting fat accumulation as well as CV risk are not known. Hormones, in particular, insulin-like growth factor-1 (IGF-1), may potentially play a role in the metabolic profile of breakfast skippers.

AIM

This cross-sectional study aims to test, in a sample of overweight/obese children, the hypotheses that skipping breakfast is associated with a worse metabolic profile and that IGF-1 levels are associated with this unfavorable metabolic profile.

METHODS AND RESULTS

We enrolled 112 overweight/obese prepubertal children (3-12 years). Anthropometric characteristics (height SDS, weight SDS, and body mass index (BMI) z-score) were measured. Blood samples were collected to evaluate glucose and lipid metabolisms and hormone profile (growth hormone (GH), IGF-1, insulin, and cortisol). The triglycerides/high-density lipoprotein (HDL) cholesterol ratio was calculated as a predictor of cardiovascular risk. Children were divided into two groups according to breakfast habits: consumers (≥5 weekly; N = 76) and skippers (≤4 weekly; N = 36). Glycaemia, total and low-density lipoprotein (LDL) cholesterol, triglycerides (p < 0.05), and triglycerides/HDL cholesterol ratio (p < 0.001) were higher, while HDL cholesterol was lower (p < 0.01) in skippers as compared to consumers. IGF-1 concentrations were inversely correlated with LDL cholesterol (r = -0.279, p=0.013) and directly correlated with HDL cholesterol (r = 0.226, p=0.047). IGF-1 correlated positively with HDL cholesterol (r = 0.266, p=0.045) in consumers and correlated negatively with LDL cholesterol (r = -0.442, p=0.024) in skippers. Breakfast consumption among prepubertal overweight/obese children showed a better lipid profile in comparison with those who skipped breakfast [OR: 0.165 (95% CI: 0.053-0.518), p=0.001]; these latter odds of the increased triglycerides/HDL cholesterol ratio was 6.1-fold higher.

CONCLUSIONS

Breakfast skippers show a worse lipid profile when compared to breakfast consumers. IGF-1 might play a role as an independent modulator of lipid metabolism.

Role of Hedgehog Signaling in Breast Cancer: Pathogenesis and Therapeutics

Breast cancer (BC) is the leading cause of cancer-related mortality in women, only followed by lung cancer. Given the importance of BC in public health, it is essential to identify biomarkers to predict prognosis, predetermine drug resistance and provide treatment guidelines that include personalized targeted therapies. The Hedgehog (Hh) signaling pathway plays an essential role in embryonic development, tissue regeneration, and stem cell renewal. Several lines of evidence endorse the important role of canonical and non-canonical Hh signaling in BC. In this comprehensive review we discuss the role of Hh signaling in breast development and homeostasis and its contribution to tumorigenesis and progression of different subtypes of BC. We also examine the efficacy of agents targeting different components of the Hh pathway both in preclinical models and in clinical trials. The contribution of the Hh pathway in BC tumorigenesis and progression, its prognostic role, and its value as a therapeutic target vary according to the molecular, clinical, and histopathological characteristics of the BC patients. The evidence presented here highlights the relevance of the Hh signaling in BC, and suggest that this pathway is key for BC progression and metastasis.

Serum levels of insulin-like growth factor 1 are negatively associated with log transformation of thyroid-stimulating hormone in Graves' disease patients with hyperthyroidism or subjects with euthyroidism: A prospective observational study

Insulin-like growth factor 1 (IGF-1) has a molecular structure similar to that of insulin. As an essential mediator of growth hormone, IGF-1 plays a vital role in growth of children and anabolic effects of adults. We evaluated the serum levels of IGF-1 in patients with hyperthyroidism or euthyroidism.In this study, 30 patients each of Graves' disease with hyperthyroidism (HY group) and euthyroid individuals (EU group) were recruited. The HY patients were treated with antithyroid regimens as clinically indicated. No medications were given to EU patients. The demographic characteristics and anthropometric and laboratory data of both groups at baseline and 6 months were compared. Associations between levels of IGF-1 and free thyroxine (fT4), thyroid-stimulating hormone (TSH), or log transformation of TSH (logTSH) were analyzed.At baseline, the HY patients had significantly higher serum IGF-1 levels than EU patients (median [Q1, Q3]: 305.4 [257.4, 368.1] vs. 236.7 [184.6, 318.8] ng/mL, P = .007). At 6 months, the HY patients still had higher serum levels of IGF-1 than EU patients (299.5 [249.9, 397.9] vs 222.1 [190.2, 305.4] ng/mL, P = .003). At baseline, the serum levels of IGF-1 in the HY and EU patients were positively associated with fT4 (β = 29.02, P = .002) and negatively associated with TSH (β = -31.46, P = .042) and logTSH (β = -29.04, P = .007). The associations between serum levels of IGF-1 with fT4 or TSH became insignificant at 6 months. However, the serum IGF-1 levels had persistent negative associations with logTSH at 6 months (β = -26.65, P = .021). The negative associations between IGF-1 and logTSH at baseline and 6 months remained significant even after adjustment with sex and age (β = -20.22, P = .023 and β = -20.51, P = .024, respectively).The HY patients had higher serum IGF-1 levels than EU patients. The serum IGF-1 concentrations were negatively associated with logTSH in patients with hyperthyroidism or euthyroidism.

The association of insulin-like growth factor-1 standard deviation score and height in Chinese children with type 1 diabetes mellitus

Assessing the relationship between IGF-1 and height in type 1 diabetes children. Seventy-two type 1 diabetes children and 190 controls were recruited. The height standard deviation score of type 1 diabetes children was significantly higher than controls. The height standard deviation score was higher than the target height standard deviation score in both type 1 diabetes and controls. Serum IGF-1 levels and the IGF-1 standard deviation score were significantly lower in type 1 diabetes patients compared with controls. There was a significant difference in IGF-1 standard deviation score between the good glycemic control group and control group. The height standard deviation score was significantly correlated with C-peptide and IGF-1 levels. Furthermore, the IGF-1 standard deviation score was significantly correlated with glycemic control and C-peptide. The growth hormone/IGF-1 axis is impaired in type 1 diabetes, but height with good or poor glycemic control is not impaired.

Two intrauterine programming mechanisms of adult hypercholesterolemia induced by prenatal nicotine exposure in male offspring rats

Epidemiologic studies showed that low birth weight is associated with high cholesterol and an increased risk of cardiovascular diseases in adulthood. This study aimed to elucidate the intrauterine programming mechanisms of adult hypercholesterolemia. The results showed that prenatal nicotine exposure (PNE) caused intrauterine growth retardation and hypercholesterolemia in male adult offspring rats. Hepatic cholesterol synthesis and output were deceased in utero but increased in adults; hepatic reverse cholesterol transport (RCT) persistently deceased before and after birth. Meanwhile, PNE elevated serum corticosterone level and decreased hepatic IGF1 pathway activity in male fetuses, whereas converse changes were observed in male adults. The chronic stress model and cortisol-treated HepG2 cells verified that excessive glucocorticoid (GC)-induced GC-IGF1 axis programming enhanced hepatic cholesterol synthesis and output. In addition, PNE decreased the expression of specific protein 1 and P300 enrichment and H3K27 acetylation at the promoter region of genes responsible for RCT both in fetal and adult, male livers and reduced expression of those genes, similar alterations were also confirmed in cortisol-treated HepG2 cells, suggesting that excessive GC-related programming induced continuous RCT reduction by epigenetic modification. Taken together, the "2-programming" approach discussed above may ultimately contribute to the development of hypercholesterolemia in male adult offspring.-Zhou, J., Zhu, C., Luo, H., Shen, L., Gong, J., Wu, Y., Magdalou, J., Chen, L., Guo, Y., Wang, H. Two intrauterine programming mechanisms of adult hypercholesterolemia induced by prenatal nicotine exposure in male offspring rats.

Positive correlation between serum IGF-1 and HDL-C in type 2 diabetes mellitus

OBJECTIVE

Dyslipidemia and low levels of high density lipoprotein cholesterol (HDL-C) can increase the risk of atherosclerosis development in people with type 2 diabetes mellitus (T2DM). This study aimed to investigate the correlation between serum HDL-C and insulin-like growth factor-1 (IGF-1), which are crucially involved inT2DM.

METHODS

Serum concentrations of IGF-1, total cholesterol, triglyceride, low density lipoprotein cholesterol, and HDL-C were measured in 498 participants with T2DM without any lipid-modifying medicine prior to study. Participants were divided into three groups according to the 25th and 75th percentile of IGF-1 levels: low IGF-1 group (G1), middle IGF-1 group (G2), and high IGF-1 group (G3), respectively. Serum levels of HDL-C were compared among the three groups.

RESULTS

G1 presented a higher body mass index and higher fasting plasma insulin (FINS) than G2 (P<0.05), yet a lower HDL-C than G2 (P<0.05). Moreover, HDL-C, postprandial blood glucose, FINS, postprandial plasma insulin (PINS), hip circumference ratio, glycated hemoglobin A1c were significantly lower in G3 than in G2 (P<0.05). After adjusting for age and gender, serum levels of IGF-1 were negatively correlated with age, duration of disease, waist circumference, FINS, PINS, and insulin resistance, but positively correlated with HDL-C. Each increase of 2.71ng/dl in IGF-I concentration was associated with an increase of 1.34mg/dl in HDL level.

CONCLUSIONS

IGF-1 serum level in people with T2DM is correlated positively with HDL-C.

Low insulin-like growth factor 1 is associated with low high-density lipoprotein cholesterol and metabolic syndrome in Chinese nondiabetic obese children and adolescents: a cross-sectional study

Background

Low serum high-density lipoprotein cholesterol (HDL-C) is an independent risk factor for developing cardiovascular disease. Insulin-like growth factor 1(IGF-1) levels have been proven to be positively associated with HDL-C, but few studies were based on the dataset of children or adolescents. The aim of this study is to investigate the relationship among IGF-1, HDL-C and the metabolic syndrome in Chinese nondiabetic obese children and adolescents.

Methods

As a cross-sectional study, this study includes 120 obese Chinese children and adolescents and 120 healthy ones. The obese subjects were divided into two groups based on using 1.03 mmol/L as a threshold value for HDL-C. Clinical examination and laboratory examinations were assessed for all participants.

Results

Obese subjects had significantly lower IGF-1SDS and higher Height SDS than those in the control group. Among 120 obese children and adolescents, 22 (18.3 %) subjects had an HDL-C level <1.03 mmol/L. IGF-1SDS was significantly lower (P = 0.001) in obese subjects with low HDL-C. According to the results of multivariate logistic regression analysis, IGF-1 SDS is significantly associated with low HDL-C(OR 0.518, 95 % CI 0.292–0.916; P = 0.024), after being adjusted for age, gender, pubertal status, BMI SDS, SBP, DBP, HOMR-IR, total cholesterol, low density lipoprotein-cholesterol, triglycerides, ALT and uric acid. In addition, IGF-1 SDS is significantly correlated with the level of serum HDL-C in study population (r = 0.19, P = 0.003). Based on logistic regression analysis with adjustment for age, gender and pubertal status, the increased IGF-1 SDS was associated with a decreased probability of metabolic syndrome (OR 0.555, 95 % CI 0.385–0.801; P = 0.002) and hypertriglyceridemia (OR 0.582, 95 % CI 0.395–0.856; P = 0.006), but no significant correlation with hypertension.

Conclusion

Obese children had lower IGF-1SDS and taller stature compared with the control group. Low levels of IGF-1 SDS were associated with low levels of HDL-C in chinese nondiabetic obese children and adolescents, independent of insulin resistance, as well as other traditional cardiovascular disease risk markers.

Insulin-Like Growth Factor-1 Receptor Deficiency in Macrophages Accelerates Atherosclerosis and Induces an Unstable Plaque Phenotype in Apolipoprotein E-Deficient Mice

BACKGROUND

We have previously shown that systemic infusion of insulin-like growth factor-1 (IGF-1) exerts anti-inflammatory and antioxidant effects and reduces atherosclerotic burden in apolipoprotein E (Apoe)-deficient mice. Monocytes/macrophages express high levels of IGF-1 receptor (IGF1R) and play a pivotal role in atherogenesis, but the potential effects of IGF-1 on their function are unknown.

METHODS AND RESULTS

To determine mechanisms whereby IGF-1 reduces atherosclerosis and to explore the potential involvement of monocytes/macrophages, we created monocyte/macrophage-specific IGF1R knockout (MΦ-IGF1R-KO) mice on an Apoe(-/-) background. We assessed atherosclerotic burden, plaque features of stability, and monocyte recruitment to atherosclerotic lesions. Phenotypic changes of IGF1R-deficient macrophages were investigated in culture. MΦ-IGF1R-KO significantly increased atherosclerotic lesion formation, as assessed by Oil Red O staining of en face aortas and aortic root cross-sections, and changed plaque composition to a less stable phenotype, characterized by increased macrophage and decreased α-smooth muscle actin-positive cell population, fibrous cap thinning, and decreased collagen content. Brachiocephalic artery lesions of MΦ-IGF1R-KO mice had histological features implying plaque vulnerability. Macrophages isolated from MΦ-IGF1R-KO mice showed enhanced proinflammatory responses on stimulation by interferon-γ and oxidized low-density lipoprotein and elevated antioxidant gene expression levels. Moreover, IGF1R-deficient macrophages had decreased expression of ABCA1 and ABCG1 and reduced lipid efflux.

CONCLUSIONS

Our data indicate that macrophage IGF1R signaling suppresses macrophage and foam cell accumulation in lesions and reduces plaque vulnerability, providing a novel mechanism whereby IGF-1 exerts antiatherogenic effects.

The Effect of Atorvastatin on Breast Cancer Biomarkers in High-Risk Women

Statins have the potential to reduce breast cancer incidence and recurrence as shown in both epidemiologic and laboratory studies. The purpose of this study was to evaluate the effect of a lipophilic statin, atorvastatin, on breast cancer biomarkers of risk [mammographic density (MD) and insulin growth factor 1 (IGF-1)] in high-risk premenopausal women.Premenopausal women at increased risk for breast cancer received either 40 mg of atorvastatin or placebo for 1 year. Biomarker assessment was performed prior to initiation and at completion of study medication. MD was determined using both Breast Imaging Reporting and Data System and the visual analogue scale. Serum IGF-1 was determined by ELISA assay at the end of the study.Sixty-three women were enrolled between December 2005 and May 2010. Sixteen (25%) women withdrew. The mean age of participants was 43 (range, 35-50), 100% were white, and the average body mass index (BMI) was 26.4. The statin group demonstrated a significant decrease in cholesterol and low-density lipoprotein (LDL), suggesting compliance with study medication. After accounting for BMI, there was no difference in change in MD between groups. There was a significant increase in serum IGF-1 in the statin group.In this multi-institutional randomized prospective clinical trial of premenopausal women at increased risk for breast cancer, we did not see an effect of atorvastatin on MD. Further investigation of statins may be warranted; however, design of prior trials and potential mechanism of action of the agent need to be considered in the design of future trials. Cancer Prev Res; 9(5); 379-84. ©2016 AACR.

Altered liver expression of genes involved in lipid and glucose metabolism in mice with partial IGF-1 deficiency: an experimental approach to metabolic syndrome

Background

Insulin growth factor 1 (IGF-1) has multiple effects on metabolism. Much evidence suggests that the deficiency of this hormone increases insulin resistance, impairs lipid metabolism, augments oxidative damage and deregulates the neuro-hormonal axis. An inverse relationship between IGF-1 levels and the prevalence of Metabolic Syndrome (MetS) with its cardiovascular complications has been identified. However, the underlying mechanisms linking IGF-1 and MetS are still poorly understood. In order to elucidate such mechanisms, the aim of this work was to study, in mice with partial IGF-1 deficiency, liver expression of genes involved in glucose and lipid metabolism as well as serum levels of glucose, triglycerides and cholesterol, as well as liver malondialdehyde (MDA) levels, as a marker for oxidative damage.

Methods

Three experimental groups were studied in parallel: Controls (CO), wild type mice (igf-1^+/+); untreated heterozygous mice (Hz, igf-1^+/−) and Hz (igf-1^+/−) mice treated with low doses of IGF-1 for 10 days (Hz + IGF-1).

Results

A reduction of IGF-1 serum levels in the Hz group was found, which was normalized by IGF-1 therapy. Serum levels of glucose, triglycerides and cholesterol were significantly increased in the untreated Hz group as compared to both controls and Hz + IGF-1 groups. The expression of genes involved in gluconeogenesis, glycogenolysis, lipid synthesis and transport, and catabolism were altered in untreated Hz animals and the expression of most of them was normalized by IGF-1 therapy; MDA was also significantly increased in the Hz untreated group.

Conclusions

The mere partial IGF-1 deficiency is responsible for the reduction in the expression of genes involved in glucose and lipid metabolism, resulting in dyslipidemia and hyperglycemia. Such genetic alterations may seriously contribute to the establishment of MetS.

No association between genetic or epigenetic variation in insulin growth factors and antipsychotic-induced metabolic disturbances in a cross-sectional sample

AIM

Second-generation antipsychotics (SGA) are known to induce metabolic disturbances. Genetic pathways, such as the IGF pathway could be associated with increased metabolic syndrome (MetS). Additionally, IGF2 methylation varies as a function of environmental influences and is associated with schizophrenia and MetS. The current study aims to evaluate whether genetic and epigenetic variation in genes of the IGF pathway are associated with metabolic disturbances in patients under treatment with SGAs.

METHODS

Cross-sectional metabolic data from 438 patients with schizophrenia spectrum disorder was analyzed. Using the Sequenom MassARRAY iPLEX(TM) platform, 27 SNPs of the IGF1 and IGF2 genes and the IGF receptors IGF1R and IGF2R were genotyped. Methylation status of seven IGF2 CpG dinucleotides was evaluated using a Sequenom MALDI-TOF spectrometer.

RESULTS & CONCLUSION

There was a significant association between IGF2 methylation and genotype, but no significant association between genetic or epigenetic variability and metabolic parameters in the present study.

Insulin-like growth factor-1 and lipoprotein profile in cord blood of preterm small for gestational age infants

Low birth weight was associated with cardiometabolic diseases in adult age. Insulin-like growth factor-1 (IGF-1) has a crucial role in fetal growth and also associates with cardiometabolic risks in adults. Therefore, we elucidated the association between IGF-1 level and serum lipids in cord blood of preterm infants. The subjects were 41 consecutive, healthy preterm neonates (27 male, 14 female) born at <37-week gestational age, including 10 small for gestational age (SGA) infants (<10th percentile). IGF-1 levels and serum lipids were measured in cord blood, and high-density lipoprotein cholesterol (HDLC), low-density lipoprotein cholesterol (LDLC) and very low-density lipoprotein triglyceride (VLDLTG) levels were determined by HPLC method. SGA infants had lower IGF-1 (13.1 ± 5.3 ng/ml), total cholesterol (TC) (55.0 ± 14.8), LDLC (21.6 ± 8.3) and HDLC (26.3 ± 11.3) levels, and higher VLDLTG levels (19.0 ± 12.7 mg/dl) than in appropriate for gestational age (AGA) infants (53.6 ± 25.6, 83.4 ± 18.9, 36.6 ± 11.1, 38.5 ± 11.6, 8.1 ± 7.0, respectively). In simple regression analyses, log IGF-1 correlated positively with birth weight (r = 0.721, P < 0.001), TC (r = 0.636, P < 0.001), LDLC (r = 0.453, P = 0.006), and HDLC levels (r = 0.648, P < 0.001), and negatively with log TG (r = -0.484, P = 0.002) and log VLDL-TG (r = -0.393, P = 0.018). Multiple regression analyses demonstrated that IGF-1 was an independent predictor of TC, HDLC and TG levels after the gestational age and birth weight were taken into account. In preterm SGA infants, cord blood lipids profile altered with the concomitant decrease in IGF-1 level.

Influence of exercise on the metabolic profile caused by 28 days of bed rest with energy deficit and amino acid supplementation in healthy men

OBJECTIVE

Muscle loss and metabolic changes occur with disuse [i.e. bed rest (BR)]. We hypothesized that BR would lead to a metabolically unhealthy profile defined by: increased circulating tumor necrosis factor (TNF)-α, decreased circulating insulin-like-growth-factor (IGF)-1, decreased HDL-cholesterol, and decreased muscle density (MD; measured by mid-thigh computerized tomography).

METHODS

We investigated the metabolic profile after 28 days of BR with 8 ± 6% energy deficit in male individuals (30-55 years) randomized to resistance exercise with amino acid supplementation (RT, n=24) or amino acid supplementation alone (EAA, n=7). Upper and lower body exercises were performed in the horizontal position. Blood samples were taken at baseline, after 28 days of BR and 14 days of recovery.

RESULTS

We found a shift toward a metabolically unfavourable profile after BR [compared to baseline (BLN)] in both groups as shown by decreased HDL-cholesterol levels (EAA: BLN: 39 ± 4 vs. BR: 32 ± 2 mg/dL, RT: BLN: 39 ± 1 vs. BR: 32 ± 1 mg/dL; p<0.001) and Low MD (EAA: BLN: 27 ± 4 vs. BR: 22 ± 3 cm(2), RT: BLN: 28 ± 2 vs. BR: 23 ± 2 cm(2); p<0.001). A healthier metabolic profile was maintained with exercise, including NormalMD (EAA: BLN: 124 ± 6 vs. BR: 110 ± 5 cm(2), RT: BLN: 132 ± 3 vs. BR: 131 ± 4 cm(2); p<0.001, time-by-group); although, exercise did not completely alleviate the unfavourable metabolic changes seen with BR. Interestingly, both groups had increased plasma IGF-1 levels (EAA: BLN:168 ± 22 vs. BR 213 ± 20 ng/mL, RT: BLN:180 ± 10 vs. BR: 219 ± 13 ng/mL; p<0.001) and neither group showed TNFα changes (p>0.05).

CONCLUSIONS

We conclude that RT can be incorporated to potentially offset the metabolic complications of BR.

A polymorphism at IGF1 locus is associated with carotid intima media thickness and endothelium-dependent vasodilatation

OBJECTIVE

Whether IGF-1 has a protective or a detrimental role in vascular homeostasis remains unsettled. There is evidence that the C/T polymorphism rs35767 near the promoter region of the IGF1 gene located in chromosome 12 is associated with plasma IGF-1 levels. We investigated the effects of this polymorphism on circulating IGF-1 levels, carotid intima media thickness (cIMT) and endothelial-dependent vasodilation.

METHODS

Two samples of adult nondiabetic Whites were studied. Sample 1 comprised 1124 individuals in whom cIMT was measured by ultrasonography. Sample 2 included 162 drug-naïve hypertensive individuals in whom endothelium-dependent and endothelium-independent vasodilation were assessed by intra-arterial infusion of acetylcholine (ACh), and sodium nitroprusside (SNP), respectively. IGF-1 was determined by chemiluminescent immunoassay. rs35767 polymorphism was screened using a TaqMan allelic discrimination assay.

RESULTS

In sample 1, IGF-1 levels were higher in subjects carrying the T allele compared with CC carriers (178 ± 78 vs. 166 ± 60 ng/mL, respectively; P = 0.007 adjusted for age, gender, and BMI). cIMT was lower in subjects carrying the T allele compared with CC carriers (0.71 ± 0.20 vs. 0.76 ± 0.22 mm, respectively; P < 0.0001 adjusted for age, gender, and BMI). In sample 2, maximally ACh-stimulated forearm blood flow was higher in subjects carrying the T allele compared with CC carriers (343 ± 191 vs. 281 ± 125%, respectively; P = 0.02 adjusted for age, gender, and BMI).

CONCLUSION

Subjects carrying the T allele exhibited significantly higher levels of circulating IGF-1, lower values of cIMT, and higher endothelium-dependent vasodilatation compared with CC carriers. These findings support the idea that IGF-1 plays a role in the pathogenesis of atherosclerosis.

Serum IGF1, metabolic syndrome, and incident cardiovascular disease in older people: a population-based study

OBJECTIVE

High as well as low levels of IGF1 have been associated with cardiovascular diseases (CVD). The relationship of IGF1 with (components of) the metabolic syndrome could help to clarify this controversy. The aims of this study were: i) to investigate the association of IGF1 concentration with prevalent (components of) the metabolic syndrome; and ii) to examine the role of (components of) the metabolic syndrome in the relationship between IGF1 and incident CVD during 11 years of follow-up.

METHODS

Data were used from the Longitudinal Aging Study Amsterdam, a cohort study in a representative sample of the Dutch older population (≥65 years). Data were available in 1258 subjects. Metabolic syndrome was determined using the definition of the US National Cholesterol Education Program Adult Treatment Panel III. CVD were ascertained by self-reports and mortality data.

RESULTS

Levels of IGF1 in the fourth quintile were associated with prevalent metabolic syndrome compared with the lowest quintile (odds ratio: 1.59, 95% confidence interval (CI) 1.09-2.33). The middle up to the highest quintile of IGF1 was positively associated with high triglycerides in women. Metabolic syndrome was not a mediator in the U-shaped relationship of IGF1 with CVD. Both subjects without the metabolic syndrome and low IGF1 levels (hazard ratio (HR) 1.75, 95% CI 1.12-2.71) and subjects with the metabolic syndrome and high IGF1 levels (HR 2.28, 95% CI 1.21-4.28) demonstrated increased risks of CVD.

CONCLUSIONS

In older people, high-normal IGF1 levels are associated with prevalent metabolic syndrome and high triglycerides. Furthermore, this study suggests the presence of different pathomechanisms for both low and high IGF1 levels and incident CVD.

Association of IGF1 with glycemic control and occurrence of severe hypoglycemia in patients with type 1 diabetes mellitus

OBJECTIVE

GH is implicated in the counter-regulatory response to hypoglycemia. We tested whether IGF1 levels are associated with occurrence of severe hypoglycemic events in patients with type 1 diabetes and whether the IGF1 concentration is influenced by glycemic control.

METHODS

A total of 228 outpatients with type 1 diabetes were included in a post hoc analysis of a 1-year observational study on severe hypoglycemia. Serum total IGF1 was measured at entry into the study. The occurrence of severe episodes of hypoglycemia, mild symptomatic, and biochemical as well as hypoglycemia awareness status was assessed. Also patients were included in a multiple regression analysis to investigate the role of HbA1c in the IGF1 concentration.

RESULTS

IGF1 levels were associated with neither severe hypoglycemia in the entire cohort (P=0.30) nor in any gender nor when confining the analysis to those with long-standing diabetes (>20 years) (n=112, P=0.68) and those with both long-standing diabetes and undetectable C-peptide (n=51, P=0.067). Levels of IGF1 were associated with neither mild symptomatic hypoglycemia (P=0.24) nor biochemical hypoglycemia (0.089) nor hypoglycemia awareness (P=0.16). At a multiple regression analysis, HbA1c was negatively associated with IGF1 (P=0.001).

CONCLUSION

In type 1 diabetes, circulating IGF1 levels are negatively associated with glycemic control. However, IGF1 levels were not associated with occurrence of hypoglycemia or hypoglycemia awareness in these patients.

The relationship between dioxin-like polychlorobiphenyls and IGF-I serum levels in healthy adults: evidence from a cross-sectional study

OBJECTIVE

Insulin-like growth factor I (IGF-I) and dioxin-like polychlorobiphenyls (DL-PCBs) have been associated with the pathogenesis of several diseases like cancer, diabetes and growth disorders. Because it has been suggested that organohalogenated contaminants could influence IGF-I levels in adults, the potential relationship between DL-PCBs and IGF-I serum levels was studied in 456 healthy adults from a representative sample of the general population of the Canary Islands (Spain).

DESIGN

Free circulating serum levels of IGF-I and IGFBP-3 were measured through an ELISA methodology, while the serum levels of the 12 DL-PCBs congeners (IUPAC numbers # 77, 81, 105, 114, 118, 123, 126, 156, 157, 167, 169, and 189) were measured by gas chromatography/mass spectrometry (GC-MS).

RESULTS

DL-PCBs 156 and 167, Total DL-PCBs body burden (∑PCBs: sum over the 12 measured DL-PCBs), and Total toxic burden (in terms of toxic equivalence to dioxins: ∑TEQs) showed a trend of inverse association with IGF-I serum levels in the whole studied population. After adjusting for potential confounders, including gender, body mass index (BMI), age, and IGF-binding protein-3 (IGFBP-3), younger (18-45 years) women with lower BMI (<27 kg/m(2)) and detectable levels of DL-PCB-156 showed significantly lower IGF-I levels than those in the same age and BMI subgroup with non-detectable levels of DL-PCB-156 (p<0.001). Similarly, ∑PCBs and ∑TEQs showed a tendency to an inverse association with IGF-I levels in the same group of women (p=0.017 and p=0.019 respectively).

CONCLUSIONS

These findings suggest that DL-PCBs could be involved in the regulation of the IGF-system in a way possibly influenced by gender, age and BMI. Although these results should be interpreted with caution, such circumstances could contribute to explain the development of diseases associated to the IGF system.

Dyslipidaemia and undernutrition in children from impoverished areas of Maceió, state of Alagoas, Brazil

Chronic undernutrition causes reduced growth and endocrine adaptations in order to maintain basic life processes. In the present study, the biochemical profiles of chronically undernourished children were determined in order to test the hypothesis that chronic undernutrition also causes changes in lipid profile in pre-school children. The study population comprised 80 children aged between 12 and 71 months, including 60 with moderate undernutrition [height-for-age Z (HAZ) scores ≤ -2 and > -3] and 20 with severe undernutrition (HAZ scores ≤ -3). Socioeconomic, demographic and environmental data were obtained by application of a questionnaire, and anthropometric measurements and information relating to sex, age and feeding habits were collected by a trained nutritionist. Blood samples were analysed for haemoglobin, vitamin A, insulin-like growth factor 1 (IGF-1) and serum lipids, while cortisol was assayed in the saliva. Faecal samples were submitted to parasitological investigation. Analysis of variance and χ² methods were employed in order to select the variables that participated in the multivariate logistic regression analysis. The study population was socioeconomically homogeneous, while the lack of a treated water supply was clearly associated with the degree of malnutrition. Most children were parasitised and anaemia was significantly more prevalent among the severely undernourished. Levels of IGF-1 decreased significantly with increasing severity of undernutrition. Lipid analysis revealed that almost all of the children had dyslipidemia, while low levels of high-density lipoprotein were associated with the degree of undernutrition. It is concluded that chronic malnutrition causes endocrine changes that give rise to alterations in the metabolic profile of pre-school children.