Growth Hormone as Biomarker in Heart Failure

IGF Signaling in the Heart in Health and Disease

One of the most vital processes of the body is the cardiovascular system's proper operation. Physiological processes in the heart are regulated by the balance of cardioprotective and pathological mechanisms. The insulin-like growth factor system (IGF system, IGF signaling pathway) plays a pivotal role in regulating growth and development of various cells and tissues. In myocardium, the IGF system provides cardioprotective effects as well as participates in pathological processes. This review summarizes recent data on the role of IGF signaling in cardioprotection and pathogenesis of various cardiovascular diseases, as well as analyzes severity of these effects in various scenarios.

Differential biomarker expression in heart failure patients with and without mitral regurgitation: Insights from BIOSTAT-CHF

BACKGROUND

Mitral regurgitation (MR) frequently coexists with heart failure (HF).

OBJECTIVES

To better understand potential pathophysiological differences between patients with HF with or without moderate-severe MR, we compared differentially expressed circulating biomarkers between these two groups.

METHODS

The Olink Proteomics® Multiplex Cardiovascular (CVD) -II, CVD-III, Immune Response and Oncology-II panels of 363 unique proteins from different pathophysiological domains were used to investigate the biomarker profiles of HF patients from index and validation cohorts of the BIOSTAT-CHF study stratified according to the presence of moderate-to-severe MR or no-mild MR.

RESULTS

The index cohort included 888 patients (46%) with moderate-to-severe MR and 1029 (54%) with no-mild MR at baseline. The validation cohort included 522 patients (33%) with moderate-to-severe MR and 1076 (66%) with no-mild MR at baseline. Compared to patients with no-mild MR, those with moderate-to-severe MR had lower body mass index, higher comorbidity burden, signs and symptoms of more severe HF, lower systolic blood pressure, and larger left atrial and ventricular dimensions, in both cohorts. NT-proBNP, CA125, fibroblast growth factor 23 (FGF23) and growth hormone 1 (GH1) were up-regulated, whereas leptin (LEP) was down-regulated in patients with moderate-severe MR versus no-mild MR, in both index and validation cohorts.

CONCLUSION

Circulating biomarkers differently expressed in HF patients with moderate-severe MR versus no-mild MR were related to congestion, lipid and mineral metabolism and oxidative stress. These findings may be of value for the development of novel treatment targets in HF patients with MR.

Muscle Wasting and Sarcopenia in Heart Failure-The Current State of Science

Sarcopenia is primarily characterized by skeletal muscle disturbances such as loss of muscle mass, quality, strength, and physical performance. It is commonly seen in elderly patients with chronic diseases. The prevalence of sarcopenia in chronic heart failure (HF) patients amounts to up to 20% and may progress into cardiac cachexia. Muscle wasting is a strong predictor of frailty and reduced survival in HF patients. Despite many different techniques and clinical tests, there is still no broadly available gold standard for the diagnosis of sarcopenia. Resistance exercise and nutritional supplementation represent the currently most used strategies against wasting disorders. Ongoing research is investigating skeletal muscle mitochondrial dysfunction as a new possible target for pharmacological compounds. Novel agents such as synthetic ghrelin and selective androgen receptor modulators (SARMs) seem promising in counteracting muscle abnormalities but their effectiveness in HF patients has not been assessed yet. In the last decades, many advances have been accomplished but sarcopenia remains an underdiagnosed pathology and more efforts are needed to find an efficacious therapeutic plan. The purpose of this review is to illustrate the current knowledge in terms of pathogenesis, diagnosis, and treatment of sarcopenia in order to provide a better understanding of wasting disorders occurring in chronic heart failure.

A novel mutation associated with Type III Bartter syndrome: A report of five cases

The clinical, biochemical and mutation spectra of Chinese patients with Type III Bartter syndrome (type III BS), a rare autosomal recessive disorder, were investigated. A total of five unrelated Chinese patients aged 8 months to 24 years were diagnosed with type III BS via analysis of biochemical markers, including chloride, potassium and calcium, and genetic sequencing. The levels of insulin‑like growth factor‑1 (IGF‑1) were evaluated via ELISA and a mutation study of cultured amniocytes was conducted for prenatal diagnosis. The child patients were admitted for polydipsia, polyuria, myasthenia and developmental delay, whereas the adult patients were hospitalized for limb numbness, polydipsia and polyuria. Nine variants in the chloride voltage‑gated channel Kb (CLCNKB) gene were detected, including eight sequence variants and one whole CLCNKB gene deletion. One sequence variant (c.1967T>C) was novel, whereas the remaining variants (c.595G>T, c.908A>C, c.1004T>C, c.1312C>T, c.1334_1335delCT and c.1718C>A) and the whole gene deletion had been previously reported. The whole gene deletion was frequently observed in patients with early‑onset type III BS in the present study. Two patients showed IGF‑1 deficiency with normal growth hormone level. All patients were treated with potassium supplementation and indometacin. The mother of one patient underwent amniocentesis during her second pregnancy; the fetus was not affected by type III BS based on screening for sequence variants, and normal development and blood electrolyte analysis following birth confirmed the diagnosis. In conclusion, five cases of type III BS in patients from mainland China were reported. Large deletions were frequently detected, particularly in early‑onset patients; isolated IGF‑1 deficiency was found, one novel sequence variant was identified. Prenatal diagnosis was successfully established using genetic analysis of cultured amniocytes, and may facilitate the prevention of congenital defect of type III BS in the next pregnancy.

Hormonal Replacement Therapy in Heart Failure: Focus on Growth Hormone and Testosterone

A growing body of evidence led to the hypothesis that heart failure (HF) could be considered a multiple hormone deficiency syndrome. Deficiencies in the main anabolic axes cannot be considered as mere epiphenomena, are very common in HF, and are clearly associated with poor cardiovascular performance and outcomes. Growth hormone deficiency and testosterone deficiency play a pivotal role and the replacement treatment is an innovative therapy that should be considered. This article appraises the current evidence regarding growth hormone and testosterone deficiencies in HF and reviews novel findings about the treatment of these conditions in HF.

Metabolic Syndrome in Heart Failure: Friend or Foe?

The interplay between metabolic syndrome (MetS) and heart failure (HF) is intricate. Population studies show that MetS confers an increased risk to develop HF and this effect is mediated by insulin resistance (IR). However, obesity, a key component in MetS and common partner of IR, is protective in patients with established HF, although IR confers an increased risk of dying by HF. Such phenomenon, known as "obesity paradox," accounts for the complexity of the HF-MetS relationship. Because IR impacts more on outcomes than MetS itself, the former may be considered the actual target for MetS in HF patients.

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.

Multiple hormonal and metabolic deficiency syndrome in chronic heart failure: rationale, design, and demographic characteristics of the T.O.S.CA. Registry

Recent evidence supports the concept that progression of chronic heart failure (CHF) depends upon an imbalance of catabolic forces over the anabolic drive. In this regard, multiple hormonal deficiency syndrome (MHDS) significantly has impacts upon CHF progression, and is associated with a worse clinical status and increased mortality. The T.O.S.CA. (Trattamento Ormonale nello Scompenso CArdiaco; Hormone Therapy in Heart Failure) Registry (clinicaltrial.gov = NCT02335801) tests the hypothesis that anabolic deficiencies reduce survival in a large population of mild-to-moderate CHF patients. The T.O.S.CA. Registry is a prospective multicenter observational study coordinated by "Federico II" University of Naples, and involves 19 centers situated throughout Italy. Thyroid hormones, insulin-like growth factor-1, total testosterone, dehydroepiandrosterone , and insulin are measured at baseline and every year for a patient-average follow-up of 3 years. Subjects with CHF are divided into two groups: patients with one or no anabolic deficiency, and patients with two or more anabolic deficiencies at baseline. The primary endpoint is the composite of all-cause mortality and cardiovascular hospitalization. Secondary endpoints include the composite of all-cause mortality and hospitalization, the composite of cardiovascular mortality and cardiovascular hospitalization, and change of VO₂ peak. Patient enrollment started in April 2013, and was completed in July 2017. Demographics and main clinical characteristics of enrolled patients are provided in this article. Detailed cross-sectional results will be available in late 2018. The T.O.S.CA. Registry represents the most robust prospective observational trial on MHDS in the field of CHF. The study findings will advance our knowledge with regard to the intimate mechanisms of CHF progression and hopefully pave the way for future randomized clinical trials of single or multiple hormonal replacement therapies in CHF.

Growth Hormone (GH) and Cardiovascular System

This review describes the positive effects of growth hormone (GH) on the cardiovascular system. We analyze why the vascular endothelium is a real internal secretion gland, whose inflammation is the first step for developing atherosclerosis, as well as the mechanisms by which GH acts on vessels improving oxidative stress imbalance and endothelial dysfunction. We also report how GH acts on coronary arterial disease and heart failure, and on peripheral arterial disease, inducing a neovascularization process that finally increases flow in ischemic tissues. We include some preliminary data from a trial in which GH or placebo is given to elderly people suffering from critical limb ischemia, showing some of the benefits of the hormone on plasma markers of inflammation, and the safety of GH administration during short periods of time, even in diabetic patients. We also analyze how Klotho is strongly related to GH, inducing, after being released from the damaged vascular endothelium, the pituitary secretion of GH, most likely to repair the injury in the ischemic tissues. We also show how GH can help during wound healing by increasing the blood flow and some neurotrophic and growth factors. In summary, we postulate that short-term GH administration could be useful to treat cardiovascular diseases.

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.