Insulin-like growth factor-1 in early-onset coronary artery disease: Insights into the pathophysiology of atherosclerosis

Cell non-autonomous regulation of cerebrovascular aging processes by the somatotropic axis

Age-related cerebrovascular pathologies, ranging from cerebromicrovascular functional and structural alterations to large vessel atherosclerosis, promote the genesis of vascular cognitive impairment and dementia (VCID) and exacerbate Alzheimer's disease. Recent advances in geroscience, including results from studies on heterochronic parabiosis models, reinforce the hypothesis that cell non-autonomous mechanisms play a key role in regulating cerebrovascular aging processes. Growth hormone (GH) and insulin-like growth factor 1 (IGF-1) exert multifaceted vasoprotective effects and production of both hormones is significantly reduced in aging. This brief overview focuses on the role of age-related GH/IGF-1 deficiency in the development of cerebrovascular pathologies and VCID. It explores the mechanistic links among alterations in the somatotropic axis, specific macrovascular and microvascular pathologies (including capillary rarefaction, microhemorrhages, impaired endothelial regulation of cerebral blood flow, disruption of the blood brain barrier, decreased neurovascular coupling, and atherogenesis) and cognitive impairment. Improved understanding of cell non-autonomous mechanisms of vascular aging is crucial to identify targets for intervention to promote cerebrovascular and brain health in older adults.

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.

Association between insulin-like growth factor-1 and cardiovascular events: a systematic review and dose-response meta-analysis of cohort studies

BACKGROUND

Insulin-like growth factor-1 (IGF-1) has increasingly been reported as linked to cardiovascular (CV) events; however, reported results have been inconsistent, and no meta-analysis has been undertaken to quantitatively assess this association.

METHODS

We searched PubMed, Embase, and Web of Science databases for cohort articles published up to December 1, 2020. Fixed or random-effects models were used to estimate the summary relative risks (RRs) and 95% confidence intervals (CIs) of CV events in relation to IGF-1. Restricted cubic splines were used to model the dose-response association.

RESULTS

We identified 11 articles (thirteen cohort studies) covering a total of 22,995 participants and 3040 CV events in this meta-analysis. The risk of overall CV events reduced by 16% from the highest to the lowest IGF-1 levels (RR 0.83, 95% CI 0.72-0.95), while the occurrence of CV events reduced by 28% (RR 0.72, 95% CI 0.56-0.92), but not for CV deaths, however (RR 1.00, 95% CI 0.65-1.55). We also found linear associations between IGF-1 levels and CV events. With each per 45 μg/mL IGF-1 increase, the pooled RRs were 0.91 (95% CI 0.86-0.96), 0.91 (95% CI 0.85-0.97) and 0.91 (95% CI 0.84-0.98) for overall CV events, for the occurrence of CV events, and for CV deaths, respectively.

CONCLUSIONS

Our findings based on cohort studies support the contention that any increase in IGF-1 is helpful in reducing the overall risk of CV events. As an important biomarker for assessing the likelihood of CV events, IGF-1 appears to offer a promising prognostic approach for aiding prevention.

IGF-1 and cardiovascular disease

Atherosclerosis is an inflammatory arterial pathogenic condition, which leads to ischemic cardiovascular diseases, such as coronary artery disease and myocardial infarction, stroke, and peripheral arterial disease. Atherosclerosis is a multifactorial disorder and its pathophysiology is highly complex. Changes in expression of multiple genes coupled with environmental and lifestyle factors initiate cascades of adverse events involving multiple types of cells (e.g. vascular endothelial cells, smooth muscle cells, and macrophages). IGF-1 is a pleiotropic factor, which is found in the circulation (endocrine IGF-1) and is also produced locally in arteries (endothelial cells and smooth muscle cells). IGF-1 exerts a variety of effects on these cell types in the context of the pathogenesis of atherosclerosis. In fact, there is an increasing body of evidence suggesting that IGF-1 has beneficial effects on the biology of atherosclerosis. This review will discuss recent findings relating to clinical investigations on the relation between IGF-1 and cardiovascular disease and basic research using animal models of atherosclerosis that have elucidated some of the mechanisms underlying atheroprotective effects of IGF-1.

Relation of IGF-1 and IGFBP-3 with prevalent and incident atrial fibrillation in a population-based study

BACKGROUND

Insulin-like growth factor 1 (IGF-1) and its main binding protein insulin-like growth factor binding protein 3 (IGFBP-3) have been related to several cardiovascular diseases. The relation with atrial fibrillation (AF) is largely unknown.

OBJECTIVE

The objective of this study was to investigate the association of IGF-1 and IGFBP-3 levels with prevalent and incident AF in a large population-based study.

METHODS

Data from the Study of Health in Pomerania (SHIP) were collected. At presentation, a medical examination, standardized electrocardiographic assessment, and measurements of serum IGF-1 and IGFBP-3 levels were performed. Incident AF was assessed in individuals without AF at baseline (SHIP-1) who developed AF during follow-up (SHIP-2; after a mean of 5.2 years).

RESULTS

Of 3160 participants, 66 (2.1%) exhibited AF at baseline. IGF-1 levels and IGF-1/IGFBP-3 ratios were significantly lower in individuals with AF than in those without AF (IGF-1: 104.2 ± 41.6 ng/mL vs 142.9 ± 53.5 ng/mL, P < .001 and IGF-1/IGFBP-3: 0.031 ± (0.009 ng/mL vs 0.036 ± 0.010 ng/mL, P = .006, respectively). Multivariable-adjusted logistic regression models showed that a low IGF-1/IGFBP-3 ratio was associated with prevalent AF (odds ratios 0.67; 95% confidence interval 0.48-0.94; P = .021). Of 1817 individuals without AF at baseline, 27 (1.5%) developed AF during follow-up. In these participants, IGF-1 levels, but not IGF-1/IGFBP-3 ratios, were significantly lower (IGF-1: 113.3 ± 38.6 ng/mL vs 147.2 ± 51.6 ng/mL, P = .013 and IGF-1/IGFBP-3: 0.033 ± 0.008 ng/mL vs 0.036 ± 0.010 ng/mL, P = .176).

CONCLUSION

Low IGF-1/IGFBP-3 ratios are associated with a higher prevalence of AF. There seems to be a similar impact in incident AF.

The relation between insulin-like growth factor 1 levels and risk of depression in ischemic stroke

BACKGROUND

The aim of this study is to evaluate whether lower serum levels of insulin-like growth factor 1 (IGF-1) in the acute phase of ischemic stroke are associated with higher risk of post-stroke depression (PSD) over a 1-year period.

METHODS

The subjects were first-ever acute ischemic stroke (AIS) patients who were hospitalized from July 1, 2014 to August 31, 2015. The study also included 120 age-matched and sex-matched healthy controls from the same geographical area. Fasting blood samples were collected within 24 hours of admission for IGF-I measurement. Neurological and neuropsychological evaluations were conducted at a 1-year follow-up.

RESULTS

Two-hundred twenty-five patients were observed for a 1-year follow-up, and 74 of these patients (32.9%, 95%CI: 26.8%-39.0%) were diagnosed with PSD. The depression distribution across the IGF-1 quartiles ranged between 61.4% (first quartile) and 8.9% (fourth quartile). In a multivariate model using the first quartiles of the IGF-1 versus quartiles 2 through 4, together with the significant clinical variables, the marker displayed prognostic information, and the odds ratio (OR) for first quartile was 3.35 [95% CI, 1.88-6.79; P = 0.001].

CONCLUSION

The data showed that low serum IGF-1 levels at admission are associated with a high risk of developing PSD, suggesting that these alterations might be involved in the pathophysiology of depression symptoms in stroke patients.