Insulin-like growth factor (IGF)-I, IGF-II and IGF-binding protein (IGFBP)-3 levels in Arab subjects with coronary heart disease

Profiling of Insulin-Like Growth Factor Binding Proteins (IGFBPs) in Obesity and Their Association With Ox-LDL and Hs-CRP in Adolescents

Insulin-like growth factor binding proteins (IGFBPs) are critical modulators of metabolism. In adults, IGFBPs are associated with obesity and insulin resistance. However, the association of IGFBPs with metabolic homeostasis in children and adolescents is not yet fully characterized. In this study we investigated the association of plasma IGFBPs (IGFBP-1, 3 and 7) with weight, central adiposity and cardiovascular disease markers Hs-CRP and Ox-LDL. A total of 420 adolescents (age 11-14 years) were recruited from public middle schools in Kuwait. IGFBPs were measured using bead-based multiplexing while Hs-CRP and Ox-LDL were measured using ELISA. Results showed that levels of IGFBP-1 were significantly lower in obese and overweight children when compared to normal weight children. Correlation analysis showed negative association between the level of IGFBP-1 and waist circumference to height (WC/Ht) ratio. IGFBP-1 level was also negatively associated with Hs-CRP. It was also observed that the levels of IGFBP-3 and IGFBP-7 were negatively correlated with Ox-LDL. Our data demonstrate a strong negative association of IGFBP-1 with overweight/obesity, and the inflammatory marker Hs-CRP. This was not seen with the levels of IGFBP-3 and 7. The association of IGFBP-1 with central adiposity (WC/Ht ratio) was stronger than its association with BMI-for-age z-score. Therefore we suggest that IGFBP-1 could potentially be used as a sensitive biomarker for obesity and its subsequent effects in screening and monitoring of obesity-related metabolic complications in adolescents.

Marcadores de riesgo cardiovascular en niños menores de 10 años y su relación con niveles séricos de IGF-1, IGFBP-1, IGFBP-2 e IGFBP-3

Introducción. Los desequilibrios nutricionales en la infancia afectan la salud tanto en la niñez como en la adultez. Estudios previos demuestran la asociación de marcadores endocrinos y lipídicos con riesgo cardiovascular (RCV) desde edades tempranas.Objetivo. Establecer la relación entre estado nutricional (niveles séricos de IGF-1 y sus proteínas enlazantes IGFBP-1, IGFBP-2 e IGFBP-3) y marcadores de RCV en estudiantes de 7 a 9 años.Materiales y métodos. Estudio observacional comparativo transversal realizado en 84 niños de 2 colegios de Bogotá D.C. y Soacha, Colombia, para identificar la relación entre posibles variaciones de marcadores de RCV y estado nutricional. Se midieron los niveles de glucemia y niveles séricos de IGF-1 e IGFBP, el nivel de desarrollo sexual, el perfil lipídico y los valores antropométricos. Para el análisis estadístico se utilizaron el coeficiente de correlación de Pearson, un análisis de varianza (ANOVA) y las pruebas de Kruskal Wallis, Games-Howell y Dunnett. El intervalo de confianza fue del 95% y la significancia estadística, de p<0.05.Resultados. La reducción en los niveles de IGFB-1 e IGFBP-2 fue directamente proporcional al aumento de peso. Por otra parte, se observó una correlación inversa entre ambas proteínas y concentraciones de triglicéridos, y una directa con los niveles colesterol HDL.Conclusiones. Las alteraciones de marcadores de RCV se pueden identificar en la infancia. Si estas son detectadas a tiempo es posible adoptar medidas preventivas y terapéuticas como la promoción de políticas públicas dirigidas prevenir el sobrepeso infantil, lo que a su vez reducirá el riesgo de padecer enfermedades cardiovasculares en edades adultas.

Current IGFBP-Related Biomarker Research in Cardiovascular Disease-We Need More Structural and Functional Information in Clinical Studies

Cardiovascular diseases are the leading cause of death around the world and the insulin-like growth factor (IGF)-system has multiple functions for the pathological conditions of atherosclerosis. IGF binding proteins (IGFBPs) are widely investigated as biomarkers for pathological disorders, including those of the heart. At the tissue level, IGFBP-1 to -6 decrease bioactivity of IGF-I and -II due to their high affinity IGF-binding sites. By contrast, in the circulation, the IGFBPs increase biological half-life of the IGFs and may therefore be regarded as positive regulators of IGF-effects. The IGFBPs may also exert IGF-independent functions inside or outside the cell. Importantly, the circulating IGFBP-concentrations are regulated by trophic, metabolic, and reproductive hormones. In a multitude of studies of healthy subjects and patients with coronary heart diseases, various significant associations between circulating IGFBP-levels and defined parameters have been reported. However, the complex hormonal and conditional control of IGFBPs may explain the lack of clear associations between IGFBPs and parameters of cardiac failure in broader studies including larger populations. Furthermore, the IGFBPs are subject to posttranslational modifications and proteolytic degradation by proteases, upon which the IGFs are released. In this review, we emphasize that, with the exception of IGFBP-4 and in sharp contrast to the preclinical studies, virtually all clinical studies do not have structural or functional information on their biomarker. The use of analytical systems with no discriminatory potential toward intact vs. fragmented IGFBPs represents a major issue in IGFBP-related biomarker research and an important focus point for the future. Overall, measurements of selected IGFBPs or more complex IGFBP-signatures of the family of IGFBPs have potential to identify pathophysiological alterations in the heart or patients with high cardiovascular risk, particularly if defined cohorts are to be assessed. However, a more thorough understanding of the dynamic IGF-IGFBP system as well as its proteases and protease inhibitors in both normal physiology and in cardiovascular diseases is necessary.

Sirtuins and Their Roles in Brain Aging and Neurodegenerative Disorders

Sirtuins (SIRT1-SIRT7) are unique histone deacetylases (HDACs) whose activity depends on NAD⁺ levels and thus on the cellular metabolic status. SIRTs regulate energy metabolism and mitochondrial function. They orchestrate the stress response and damage repair. Through these functions sirtuins modulate the course of aging and affect neurodegenerative diseases. SIRTSs interact with multiple signaling proteins, transcription factors (TFs) and poly(ADP-ribose) polymerases (PARPs) another class of NAD⁺-dependent post-translational protein modifiers. The cross-talk between SIRTs TFs and PARPs is a highly promising research target in a number of brain pathologies. This review describes updated results on sirtuins in brain aging/neurodegeneration. It focuses on SIRT1 but also on the roles of mitochondrial SIRTs (SIRT3, 4, 5) and on SIRT6 and SIRT2 localized in the nucleus and in cytosol, respectively. The involvement of SIRTs in regulation of insulin-like growth factor signaling in the brain during aging and in Alzheimer's disease was also focused. Moreover, we analyze the mechanism(s) and potential significance of interactions between SIRTs and several TFs in the regulation of cell survival and death. A critical view is given on the application of SIRT activators/modulators in therapy of neurodegenerative diseases.

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.

M3 subtype of muscarinic acetylcholine receptor promotes cardioprotection via the suppression of miR-376b-5p

The M₃ subtype of muscarinic acetylcholine receptors (M₃-mAChR) plays a protective role in myocardial ischemia and microRNAs (miRNAs) participate in many cardiac pathophysiological processes, including ischemia-induced cardiac injury. However, the role of miRNAs in M₃-mAChR mediated cardioprotection remains unexplored. The present study was designed to identify miRNAs that are involved in cardioprotective effects of M₃-mAChR against myocardial ischemia and elucidate the underlying mechanisms. We established rat model of myocardial ischemia and performed miRNA microarray analysis to identify miRNAs involved in the cardioprotection of M₃-mAChR. In H9c2 cells, the viability, intracellular free Ca²⁺ concentration ([Ca²⁺]i), intracellular reactive oxygen species (ROS), miR-376b-5p expression level, brain derived neurophic factor (BDNF) and nuclear factor kappa-B (NF-κB) levels were measured. Our results demonstrated that M₃-mAChR protected myocardial ischemia injury. Microarray analysis and qRT-PCR revealed that miR-376b-5p was significantly up-regulated in ischemic heart tissue and the M₃-mAChRs agonist choline reversed its up-regulation. In vitro, miR-376b-5p promoted H₂O₂-induced H9c2 cell injuries measured by cells viability, [Ca²⁺]i and ROS. Western blot and luciferase assay identified BDNF as a direct target of miR-376b-5p. M₃-mAChR activated NF-κB and thereby inhibited miR-376b-5p expression. Our data show that a novel M₃-mAChR/NF-κB/miR-376b-5p/BDNF axis plays an important role in modulating cardioprotection. MiR-376b-5p promotes myocardial ischemia injury possibly by inhibiting BDNF expression and M₃-mAChR provides cardioprotection at least partially mediated by the downregulation of miR-376b-5p through NF-κB. These findings provide new insight into the potential mechanism by which M₃-mAChR provides cardioprotection against myocardial ischemia injury.

The insulin-like growth factor system, metabolic syndrome, and cardiovascular disease risk

The metabolic syndrome is a combination of metabolic and clinical features that aggregate in individuals and increase cardiovascular disease (CVD) risk considerably. It is believed, although sometimes controversially, that the underlying basis for this syndrome is insulin resistance (IR) and accompanying compensatory hyperinsulinemia. Insulin and insulin-like growth factors (IGFs) have significant homology and interact with differing affinity with the same receptors. Therefore, their actions can be complementary, and this becomes particularly significant clinico-pathologically when their circulating levels are altered. This review of currently available information attempts to answer the following questions: (1) Is there any evidence for changes in the components of the IGF system in individuals with established CVD or with increased CVD risk as with the metabolic syndrome? (2) What are the underlying mechanisms for interactions, if any, between insulin and the IGF system, in the genesis of CVD? (3) Can knowledge of the pathophysiological changes in the IGF system observed in macrosomic newborn infants and growth hormone (GH)-treated children and adults explain some of the observations in relation to the IGF system and the metabolic syndrome? (4) Can the experimental and clinical evidence adduced from the foregoing be useful in designing novel therapies for the prevention, treatment, and assignment of prognosis in metabolic syndrome-associated disease, particularly ischemic heart disease? To answer these questions, we have performed a literature review using bibliographies from PubMed, Medline, and Google Scholar published within the last 10 years. We suggest that IGF-1 levels are reduced consistently in individuals with the metabolic syndrome and its components and in those with ischemic CVD. Such changes are also seen with GH deficiency in which these changes are partially reversible with GH treatment. Furthermore, changes are seen in levels and interactions of IGF-binding proteins in these disorders, and some of these changes appear to be independent of IGF-binding capability and could potentially impact on risk for the metabolic syndrome and CVD. The promising therapeutic implications of these observations are also discussed.

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

BACKGROUND

The risk association between the insulin like growth factor-I (IGF-I) system and cardiovascular risk is inconclusive in adults and under-explored in adolescents. We aimed to investigate the associations between serum concentrations of IGF-I and IGF binding protein-3 (IGFBP-3) and cardiovascular risk factors in adolescents.

METHODS

This was a cross-sectional, population-based, observational study in a school setting with 2102 Hong Kong Chinese adolescents aged 12-19 years. Serum IGF-I and IGFBP-3 concentrations were measured by chemiluminescence immunoassays. Anthropometric indices and traditional cardiovascular risk factors were assessed.

RESULTS

After excluding participants with abnormal thyroid and liver test results, 765 boys and 877 girls, mean (±SD) age of 15.3 (±2.0) and 15.7 (±2.0) years, respectively, were included in the analysis. Multivariable regression analyses revealed that both IGF-I and IGFBP-3 concentrations were independently associated with waist circumference, fasting insulin and haemoglobin concentrations in boys (all P < 0.05), systolic blood pressure, serum creatinine, fasting insulin and haemoglobin concentrations in girls (all P < 0.05). In girls, IGF-I was also associated with C-reactive protein concentration (P < 0.001) and IGFBP-3 was associated with fasting triglyceride concentration (P < 0.001). Compared with adolescents with the lowest tertile, the top tertile of both IGF-I and IGFBP-3 concentrations were associated with increased odds of having overweight/obesity, top tertiles of insulin and haemoglobin in both boys and girls (P for trend, all <0.05).

CONCLUSIONS

The associations between serum IGF-I, IGFBP-3, obesity, cardiovascular risk factors, insulin and haemoglobin suggest that dysregulation of the IGF system may play a linking role for the clustering of cardiovascular risk factors.

Predictors of variation in serum IGF1 and IGFBP3 levels in healthy African American and white men

BACKGROUND

Individual variation in circulating insulinlike growth factor-1 (IGF1) and its major binding protein, insulinlike growth factor binding protein-3 (IGFBP3), have been etiologically linked to several chronic diseases, including some cancers. Factors associated with variation in circulating levels of these peptide hormones remain unclear.

METHODS

Multiple linear regression models were used to determine the extent to which sociodemographic characteristics, lifestyle factors, personal and family history of chronic disease, and common genetic variants, the (CA)n repeat polymorphism in the IGF1 promoter and the IGFBP3-202 A/C polymorphism (rs2854744) predict variation in IGF1 or IGFBP3 serum levels in 33 otherwise healthy African American and 37 white males recruited from Durham Veterans Administration Medical Center.

RESULTS

Predictors of serum IGF1, IGFBP3, and the IGF1:IGFBP3 molar ratio varied by race. In African Americans, 17% and 28% of the variation in serum IGF1 and the IGF1:IGFBP3 molar ratio, were explained by cigarette smoking and carrying the IGF1 (CA)19 repeat allele, respectively. Not carrying at least 1 IGF1 (CA)19 repeat allele and a high body mass index explained 8% and 14%, respectively, of the variation IGFBP3 levels. These factors did not predict variation of these peptides in whites.

CONCLUSION

If successfully replicated in larger studies, these findings would add to recent evidence, suggesting known genetic and lifestyle chronic disease risk factors influence IGF1 and IGFBP3 circulating levels differently in African Americans and whites.

IGF-I/IGFBP-3 ratio: a mechanistic insight into the metabolic syndrome

Recent reports suggest that IGF (insulin-like growth factor)-I and IGFBP-3 (IGF-binding protein-3) have independent and opposing mechanistic effects on insulin. The aim of the present study was to assess the relationship between the IGF-I/IGFBP-3 ratio and the metabolic syndrome. We examined 3281 subjects (1463 men and 1818 women, aged 20-49 years), otherwise healthy adults, who participated in NHANES III (Third National Health and Nutrition Examination Survey), which has released measurements of IGF-I and IGFBP-3. Insulin resistance was estimated using the computer HOMA2 (homoeostatic model assessment 2) model. The updated ATP-III (Adult Treatment Panel III) definition of the metabolic syndrome was used. We applied adjusted logistic and linear regression models. After adjusting for age and race, men and women in the lowest quartile of the IGF-I/IGFBP-3 ratio were 3-fold more likely to meet the ATP-III definition of the metabolic syndrome and twice as likely to be insulin-resistant. Mean values of the IGF-I/IGFBP-3 ratio decreased significantly as the number of metabolic syndrome components increased (P<0.0001, as determined by ANOVA). The area under the ROC (receiver operating characteristic) curve for detecting insulin resistance using the IGF-I/IGFBP-3 ratio was 0.760, significantly improving upon either protein alone (P=0.01). In conclusion, the IGF-I/IGFBP-3 ratio is significantly associated with the metabolic syndrome. Calculating the ratio of these two proteins may provide insight into the metabolic syndrome clustering phenomenon.

Adult height and the risks of cardiovascular disease and major causes of death in the Asia-Pacific region: 21,000 deaths in 510,000 men and women

BACKGROUND

In Caucasian populations, adult height is inversely associated with cardiovascular disease (CVD) risk and positively related to some cancers. However, there are few data from Asian populations and from women. We sought to determine the sex- and region-specific associations between height and cardiovascular outcomes, and deaths due to cancer, respiratory and injury in populations from the Asia-Pacific region.

METHODS

Thirty-nine studies from the Asia Pacific Cohort Studies Collaboration database were included. We used Cox proportional hazard regression models to estimate the associations between height and pre-specified outcomes.

RESULTS

A total of 510,800 participants with 21,623 deaths were included. Amongst men, inverse linear associations were observed between height and coronary heart disease (CHD), stroke, CVD, injury and total mortality. The hazard ratios [95% confidence intervals, (CI)] for a 1-SD (= 6 cm) increment in height ranged from 0.85 (0.80-0.91) for injury to 0.97 (0.95-0.98) for total mortality. Similar trends were found between height and CHD, haemorrhagic stroke and CVD in women. A positive linear association was observed between height and cancer mortality. For each standard deviation greater height, the risk of cancer was increased by 5% (2-8%) and 9% (5-14%) in men and women, respectively. No regional difference was observed between Asian and Australasian cohorts. Adjusting for markers of education did not alter the results.

CONCLUSIONS

The opposing relationships of height with CVD and cancer suggest that care is required in setting national policies on childhood nutrition lest they have unintended consequences on the incidence of major non-communicable diseases.