The association of insulin-like-growth factor 1 (IGF-1) with incident coronary heart disease in women: findings from the prospective British Women's Heart and Health Study

New insights on the cardiovascular effects of IGF-1

INTRODUCTION

Cardiovascular (CV) disorders are steadily increasing, making them the world's most prevalent health issue. New research highlights the importance of insulin-like growth factor 1 (IGF-1) for maintaining CV health.

METHODS

We searched PubMed and MEDLINE for English and non-English articles with English abstracts published between 1957 (when the first report on IGF-1 identification was published) and 2022. The top search terms were: IGF-1, cardiovascular disease, IGF-1 receptors, IGF-1 and microRNAs, therapeutic interventions with IGF-1, IGF-1 and diabetes, IGF-1 and cardiovascular disease. The search retrieved original peer-reviewed articles, which were further analyzed, focusing on the role of IGF-1 in pathophysiological conditions. We specifically focused on including the most recent findings published in the past five years.

RESULTS

IGF-1, an anabolic growth factor, regulates cell division, proliferation, and survival. In addition to its well-known growth-promoting and metabolic effects, there is mounting evidence that IGF-1 plays a specialized role in the complex activities that underpin CV function. IGF-1 promotes cardiac development and improves cardiac output, stroke volume, contractility, and ejection fraction. Furthermore, IGF-1 mediates many growth hormones (GH) actions. IGF-1 stimulates contractility and tissue remodeling in humans to improve heart function after myocardial infarction. IGF-1 also improves the lipid profile, lowers insulin levels, increases insulin sensitivity, and promotes glucose metabolism. These findings point to the intriguing medicinal potential of IGF-1. Human studies associate low serum levels of free or total IGF-1 with an increased risk of CV and cerebrovascular illness. Extensive human trials are being conducted to investigate the therapeutic efficacy and outcomes of IGF-1-related therapy.

DISCUSSION

We anticipate the development of novel IGF-1-related therapy with minimal side effects. This review discusses recent findings on the role of IGF-1 in the cardiovascular (CVD) system, including both normal and pathological conditions. We also discuss progress in therapeutic interventions aimed at targeting the IGF axis and provide insights into the epigenetic regulation of IGF-1 mediated by microRNAs.

IGF-1 and cardiometabolic diseases: a Mendelian randomisation study

AIMS/HYPOTHESIS

Abnormal serum IGF-1 levels are associated with an increased risk of type 2 diabetes and cardiovascular disease. However, the causal role of IGF-1 levels within the normal range in cardiometabolic disease remains unclear. We employed Mendelian randomisation to explore the associations between genetically predicted serum IGF-1 levels and cardiometabolic diseases.

METHODS

Serum IGF-1 levels were predicted using 416 SNPs associated with IGF-1 levels among 358,072 individuals in UK Biobank. Genetic association estimates for the outcomes were obtained from consortia of type 2 diabetes (74,124 cases, 824,006 controls), coronary artery disease (60,801 cases, 123,504 controls), heart failure (47,309 cases, 930,014 controls), atrial fibrillation (65,446 cases, 522,744 controls), and ischaemic stroke (60,341 cases, 454,450 controls).

RESULTS

Genetic predisposition to elevated serum IGF-1 levels was associated with higher risk of type 2 diabetes and coronary artery disease. The OR (95% CI) per SD increment in IGF-1 level was 1.14 (1.05, 1.24) for type 2 diabetes and 1.09 (1.02, 1.16) for coronary artery disease. The association between IGF-1 and coronary artery disease was attenuated after adjustment for type 2 diabetes (OR 1.06 [95% CI 1.00, 1.13]), suggesting that the association may be partly mediated via type 2 diabetes. There was limited evidence of associations between IGF-1 levels and heart failure, atrial fibrillation and ischaemic stroke.

CONCLUSIONS/INTERPRETATION

This study found evidence that increased IGF-1 levels may be causally associated with higher risk of type 2 diabetes. Graphical abstract.

Low serum IGF1 is associated with hypertension and predicts early cardiovascular events in women with rheumatoid arthritis

OBJECTIVES

Since low insulin-like growth factor (IGF) 1 is often linked to inflammation, we analyze whether serum levels of IGF1 are associated with cardiovascular disease (CVD) in rheumatoid arthritis (RA) in a longitudinal observational study.

METHODS

A CVD risk was estimated (eCVR) in 184 female RA patients (mean age 52 years) and in 132 female patients after ischemic stroke (mean age 56 years) with no rheumatic disease, using the Framingham algorithm. The median level of IGF1 divided the cohorts in IGF1^high and IGF1^low groups. A 5-year prospective follow-up for new CVD events was completed in all RA patients. The Mantel-Cox analysis and event-free survival curves were prepared. Unsupervised clustering of proteins within the IGF1 signaling pathway was employed to identify their association with eCVR.

RESULTS

Low IGF1 resulted in a higher eCVR in RA patients (7.2% and 3.3%, p = 0.0063) and in stroke (9.3% and 7.1%, p = 0.033). RA had higher rate for new CVD events at prospective follow-up (OR 4.96, p = 0.028). Hypertension was the major risk factor associated with low IGF1 in RA and stroke. In hypertension, IGF1 was no longer responsible for intracellular activation and lost its correlation to IRS1/2 adaptor proteins. The clustering analysis confirmed that combination of low IGF1 and IRS1/2 with high IL6, insulin, and glucose predisposed to high eCVR and emphasized the functional role of serum IGF1.

CONCLUSIONS

Low serum IGF1 precedes and predicts development of early CVD events in female RA patients. Hypertension and aberrant IGF1 receptor signaling are highlighted as the important contributors to IGF1-related CVD events.

Relationships of insulin-like growth factor-1, its binding proteins, and cardiometabolic risk in hypertensive perimenopausal women

PURPOSE

During the transition from premenopause to postmenopause, many women experience weight gain and central fat deposition; therefore, we hypothesized that circulating growth factors can play a role in the pathogenesis of hypertension, metabolic syndrome, and subclinical organ damage in perimenopausal women.

BASIC PROCEDURES

The study included 192 women aged 40 to 60years; 152 had newly diagnosed essential hypertension that had never been treated, and 40 were normotensive age-matched controls. For all subjects, 24-h ambulatory blood pressure monitoring (ABPM), echocardiographic examination with assessment of left ventricular mass (LVM) and systolic and diastolic functions (GE Vivid 7.0, General Electric Vingmed Ultrasound, Horten, Norway), carotid ultrasound with measurement of intima-media thickness, and carotid-femoral pulse wave velocity (PWV) measurement (SphygmoCor, AtCor Medical, Sydney, Australia) were performed. Serum levels of insulin-like growth factor 1 (IGF-1), insulin-like growth factor-binding protein 2 (IGFBP-2), and insulin-like growth factor-binding protein 3 (IGFBP-3) were measured using an immunochemical assay.

MAIN FINDINGS

Hypertensive women had significantly lower IGFBP-2 levels than did normotensive controls (162.9±83.7 vs. 273.1±103.0μg/L, p<0.001); the groups did not differ regarding IGF and IGFBP-3 concentrations. After adjusting the covariates, multivariate analysis showed that IGFBP2 was significantly negatively correlated with 24-h systolic blood pressure (β=-0.31, p=0.02). The adjusted odds ratio for hypertension per standard deviation decrease in IGFBP-2 was 3.43 (95% confidence interval [CI] 1.65-7.13). IGFBP-2 showed a negative correlation with the number of metabolic syndrome components. Independent of body composition, IGFBP-2 was significantly related to left ventricular relative wall thickness and the ratio of mitral inflow velocities as parameter of diastolic function.

PRINCIPAL CONCLUSIONS

In perimenopausal women, decreased IGFBP-2 levels may play a role in blood pressure regulation and the development of subclinical left ventricular diastolic dysfunction. Whether IGFBP-2 is a marker or a mediator of cardiovascular disease in this population merits further investigation.

Associations of objective physical activity with insulin sensitivity and circulating adipokine profile: the Framingham Heart Study

The purpose of this study was to explore the relation of physical activity (PA) and sedentary time (SED) to insulin sensitivity and adipokines. We assessed PA and SED using Actical accelerometers and insulin resistance (HOMA-IR) in 2109 participants (free of type 1 and 2 diabetes mellitus) from Framingham Generation 3 and Omni 2 cohorts (mean age 46 years, 54% women). Systemic inflammation (C-reactive protein [CRP]) and circulating adipokines were measured 6 years earlier. Steps per day, moderate-to-vigorous PA (MVPA) and SED per wear time (%SED) were predictor variables in multivariable regression analyses, with HOMA-IR, CRP and circulating adipokines as outcome measures. We reported that higher MVPA and more steps per day were associated with lower HOMA-IR, adjusting for %SED (β = -0.036, P = 0.002; β = -0.041, P = 0.005). Steps were inversely associated with CRP, but were directly associated with insulin-like growth factor (IGF)-1 levels (β = -0.111, P = 0.002; β = 3.293, P = 0.007). %SED was positively associated with HOMA-IR (β = 0.033, P < 0.0001), but non-significant after adjusting for MVPA (P = 0.13). %SED was associated with higher ratio of leptin/leptin receptor (sOB-R) and higher adipocyte fatty acid-binding protein (FABP)4 (β = 0.096, P < 0.0001; β = 0.593, P = 0.002). Our findings suggest differential influences of PA vs. SED on metabolic pathways, with PA modulating insulin resistance and inflammation, whereas SED influences FABPs.

Role of insulin-like growth factor 1 in stent thrombosis under effective dual antiplatelet therapy

Introduction

Accumulating evidence now indicates that insulin-like growth factors (IGF) and their regulatory proteins are growth promoters for arterial cells and mediators of cardiovascular diseases.

Aim

We hypothetised that IGF-1 levels could play a role in the development of stent thrombosis (ST), and aimed to investigate the associations between stent thrombosis under effective dual antiplatelet therapy and IGF-1 levels and other related factors such as disease severity and LV ejection fraction in patients undergoing coronary stent placement.

Material and methods

A total of 128 patients undergoing coronary stent implantation were included in the analysis. Seventy-seven patients experiencing ST in the first year after stent implantation were defined as the ST group. Fifty-one patients without ST at least 1 year after stent implantation were defined as the no-thrombosis (NT) group. The IGF-1 levels, Gensini scores, and other related factors were measured.

Results

The IGF-1 levels were significantly higher in the stent thrombosis group than in the no-thrombosis group (122.22 ±50.61 ng/ml vs. 99.52 ±46.81 ng/ml, respectively, p < 0.039). The left ventricle ejection fraction (LVEF) values were significantly lower (44.13 ±9.25% vs. 55.81 ±8.77%, p < 0.0001) and Gensini scores were significantly higher (63.74 ±26.54 vs. 48.87 ±23.7, p < 0.004) in the ST group than in the NT group, respectively. In the linear regression analysis, IGF-1, Gensini score, LVEF, total cholesterol, and triglycerides were found to be independent risk factors for ST.

Conclusions

This study revealed that the plasma IGF-1 levels, disease severity, were significantly higher and LVEF was lower in patients with ST. High IGF-1 levels may identify patients who are at increased risk for ST. Future trials are necessary to confirm these results.

The role of insulin-like growth factor-1 in development of coronary no-reflow and severity of coronary artery disease in patients with acute myocardial infarction

INTRODUCTION

Insulin-like growth factor-1 (IGF-1) has atheroprotective effects via reduction in oxidative stress, cellular apoptosis, pro-inflammatory signaling, and endothelial dysfunction.

AIM

We hypothesized that low levels of IGF-1 may be associated with the severity and extent of coronary artery disease and development of the coronary no-reflow phenomenon in patients with acute ST-elevation myocardial infarction (STEMI) and investigated the role of the IGF-1 molecule in the coronary no-reflow phenomenon and severity of coronary artery disease (CAD) in patients with acute STEMI in a tertiary hospital.

MATERIAL AND METHODS

The study was conducted among 113 patients undergoing primary percutaneous coronary intervention (PPCI) for STEMI, of whom 49 patients developed the no-reflow phenomenon. Coronary no-reflow was defined as Thrombolysis In Myocardial Infarction (TIMI) flow grade 2 or less after intervention. Insulin-like growth factor-1 levels were measured in both groups. The severity and extent of CAD were evaluated according to the Gensini and Syntax scores.

RESULTS

Although IGF-1 levels were lower in the no-reflow group, there was not a statistically significant difference between the no-reflow group and the control group (116.65 ±51.72 vs. 130.82 ±48.76, p = 0.130). Gensini and Syntax scores were higher in the no-reflow group. There was no association between Gensini and Syntax scores and IGF-1 levels (r = -0.071, r = 0.479, r = -0.158, p = 0.113).

CONCLUSIONS

In this study, IGF-1 levels were not statistically different between patients developing the no-reflow phenomenon and controls. There was no association between development of the no-reflow phenomenon and severity of CAD or IGF-1 levels. Nevertheless, large scale studies are needed to verify these results.

Revisiting the relationship between blood pressure and insulin-like growth factor-1

Conflicting evidence exists on the relationship between blood pressure (BP) and insulin-like growth factor-1 (IGF-1). We reviewed available articles and pooled extrapolated regression coefficients for the association between BP and total IGF-1 as reported in the literature and included additional data from 912 individuals from the general population. We identified 20 studies including 11 704 subjects. We also measured total IGF-1, insulin-like binding protein-3, and BP in 912 black and white men and women from South Africa (aged 20-70 years). When plotting positive and negative weighed regression coefficients (29 data points) against IGF-1, we found a significant positive relationship (r=0.31; P<0.001; n=11 704) intercepting the 0 point at 191 ng/mL IGF-1, suggesting an inverse BP/IGF-1 relationship in low IGF-1 conditions, and a positive relationship in overtly high IGF-1 conditions. In conclusion, our findings suggest that the relationship between BP and IGF-1 is dependent on, or related to, IGF-1 concentrations, as an expression of direct or reverse causality. Low IGF-1 bioavailability (associated with aging and vascular deterioration), resistance to IGF-1, and the complex interplay between IGF-1 and other vasoactive hormones could mask the vasoprotective functions of IGF-1 in cross-sectional studies or could modify their functions in prospective studies.

Aging, atherosclerosis, and IGF-1

Insulin-like growth factor 1 (IGF-1) is an endocrine and autocrine/paracrine growth factor that circulates at high levels in the plasma and is expressed in most cell types. IGF-1 has major effects on development, cell growth and differentiation, and tissue repair. Recent evidence indicates that IGF-1 reduces atherosclerosis burden and improves features of atherosclerotic plaque stability in animal models. Potential mechanisms for this atheroprotective effect include IGF-1-induced reduction in oxidative stress, cell apoptosis, proinflammatory signaling, and endothelial dysfunction. Aging is associated with increased vascular oxidative stress and vascular disease, suggesting that IGF-1 may exert salutary effects on vascular aging processes. In this review, we will provide a comprehensive update on IGF-1's ability to modulate vascular oxidative stress and to limit atherogenesis and the vascular complications of aging.

Serum insulin-like growth factors and mortality in localised and advanced clinically detected prostate cancer

CONTEXT

Many studies have reported associations of insulin-like growth factors (IGFs) and IGF-binding proteins (IGFBPs) with prostate cancer development, but none have investigated their association with fatal progression of prostate cancer.

OBJECTIVE

We investigated associations of circulating IGF-I, IGF-II, IGFBP-2 and IGFBP-3 with all-cause and prostate cancer mortality in men with clinically identified prostate cancer, stratified by whether localised (stage T1 or T2) or advanced (T3, T4, N1 or M1) at diagnosis.

DESIGN, SETTING AND PARTICIPANTS

UK hospital-based cohort study of 396 men with prostate cancer, diagnosed between 1990 and 2008, with mean follow-up of 3.7 years.

MAIN OUTCOME MEASURES

All-cause and prostate cancer-specific mortality.

RESULTS

In men with advanced cancer, there was some evidence that IGF-I was positively associated (HR 1.20; 95% CI: 0.96, 1.49; p = 0.11) and IGFBP-3 was inversely associated (HR 0.84; 95% CI: 0.70, 1.01; p = 0.07) with all-cause mortality after controlling for age, treatment status, smoking, prostate-specific antigen and Gleason grade at diagnosis. There was some evidence that IGF-I was positively associated with prostate cancer mortality in advanced cases (HR 1.23; 95% CI: 0.94, 1.62; p = 0.13). In advanced cancers, associations of IGF-I with all-cause (HR 1.68; 95% CI: 1.28, 2.23; p < 0.001) and prostate cancer-specific (HR 1.59; 95% CI: 1.11, 2.28; p = 0.01) mortality strengthened (and were conventionally statistically significant) after further controlling for IGFBP-3.

CONCLUSIONS

Measures of IGF-I and IGFBP-3 may have potential as prognostic markers in predicting risk of death in men with advanced prostate cancer. Large, prospective studies with repeat IGFs and IGFBPs are now required.

Case report: low circulating IGF-I levels due to Acid-Labile Subunit deficiency in adulthood are not associated with early development of atherosclerosis and impaired heart function

OBJECTIVE

Decreased insulin-like growth factor-I (IGF-I) levels in adults have been associated with an increased risk of ischemic heart disease and heart failure. It is currently unknown whether patients with low circulating IGF-I levels due to a homozygous acid-labile subunit (IGFALS) gene mutation also have increased risk of cardiovascular disease. Therefore, we evaluated atherosclerotic burden in a 27 year old male patient who was diagnosed with a homozygous IGFALS mutation and consequently had extremely low circulating IGF-I levels.

METHODS

Ten year's cardiovascular risk was calculated using the Framingham risk score. Presence of (subclinical) atherosclerosis was assessed using a 64-slice CT scan of the coronary arteries. Cardiac performance was measured by conventional echocardiographic measurements, three dimensional (3D)-echocardiography, and tissue deformation imaging.

RESULTS

Despite his extremely low circulating IGF-I levels due to Acid-Labile Subunit (ALS) deficiency, our patient had a low Framingham risk score and no signs of coronary atherosclerosis. Adjusted for physical height, cardiac performance was not impaired compared with healthy subjects.

CONCLUSION

The present case report does not lend support to routine cardiovascular screening in patients with extremely low circulating IGF-I levels due to a homozygous IGFALS mutation, when cardiovascular risk is low.

IGF-1 and atherothrombosis: relevance to pathophysiology and therapy

IGF-1 (insulin-like growth factor-1) plays a unique role in the cell protection of multiple systems, where its fine-tuned signal transduction helps to preserve tissues from hypoxia, ischaemia and oxidative stress, thus mediating functional homoeostatic adjustments. In contrast, its deprivation results in apoptosis and dysfunction. Many prospective epidemiological surveys have associated low IGF-1 levels with late mortality, MI (myocardial infarction), HF (heart failure) and diabetes. Interventional studies suggest that IGF-1 has anti-atherogenic actions, owing to its multifaceted impact on cardiovascular risk factors and diseases. The metabolic ability of IGF-1 in coupling vasodilation with improved function plays a key role in these actions. The endothelial-protective, anti-platelet and anti-thrombotic activities of IGF-1 exert critical effects in preventing both vascular damage and mechanisms that lead to unstable coronary plaques and syndromes. The pro-survival and anti-inflammatory short-term properties of IGF-1 appear to reduce infarct size and improve LV (left ventricular) remodelling after MI. An immune-modulatory ability, which is able to suppress 'friendly fire' and autoreactivity, is a proposed important additional mechanism explaining the anti-thrombotic and anti-remodelling activities of IGF-1. The concern of cancer risk raised by long-term therapy with IGF-1, however, deserves further study. In the present review, we discuss the large body of published evidence and review data on rhIGF-1 (recombinant human IGF-1) administration in cardiovascular disease and diabetes, with a focus on dosage and safety issues. Perhaps the time has come for the regenerative properties of IGF-1 to be assessed as a new pharmacological tool in cardiovascular medicine.

IGF-1, oxidative stress and atheroprotection

Atherosclerosis is a chronic inflammatory disease in which early endothelial dysfunction and subintimal modified lipoprotein deposition progress to complex, advanced lesions that are predisposed to erosion, rupture and thrombosis. Oxidative stress plays a crucial role not only in initial lesion formation but also in lesion progression and destabilization. Although most growth factors are thought to promote vascular smooth muscle cell proliferation and migration, thereby increasing neointima, recent animal studies indicate that insulin-like growth factor (IGF)-1 exerts both pleiotropic anti-oxidant effects and anti-inflammatory effects, which together reduce atherosclerotic burden. This review discusses the effects of IGF-1 in models of vascular injury and atherosclerosis, emphasizing the relationship between oxidative stress and potential atheroprotective actions of IGF-1.