Fasting levels of high-sensitivity growth hormone predict cardiovascular morbidity and mortality: the Malmö Diet and Cancer study

Deficiency of Peptidylglycine-alpha-amidating Monooxygenase, a Cause of Sarcopenic Diabetes Mellitus

CONTEXT

Peptidylglycine-α-amidating monooxygenase (PAM) is a critical enzyme in the endocrine system responsible for activation, by amidation, of bioactive peptides.

OBJECTIVE

To define the clinical phenotype of carriers of genetic mutations associated with impaired PAM-amidating activity (PAM-AMA).

DESIGN

We used genetic and phenotypic data from cohort studies: the Malmö Diet and Cancer (MDC; 1991-1996; reexamination in 2002-2012), the Malmö Preventive Project (MPP; 2002-2006), and the UK Biobank (UKB; 2012).

SETTING

Exome-wide association analysis was used to identify loss-of-function (LoF) variants associated with reduced PAM-AMA and subsequently used for association with the outcomes.

PATIENTS OR OTHER PARTICIPANTS

This study included n∼4500 participants from a subcohort of the MDC (MDC-Cardiovascular cohort), n∼4500 from MPP, and n∼300,000 from UKB.

MAIN OUTCOME MEASURES

Endocrine-metabolic traits suggested by prior literature, muscle mass, muscle function, and sarcopenia.

RESULTS

Two LoF variants in the PAM gene, Ser539Trp (minor allele frequency: 0.7%) and Asp563Gly (5%), independently contributed to a decrease of 2.33 [95% confidence interval (CI): 2.52/2.15; P = 2.5E-140] and 0.98 (1.04/0.92; P = 1.12E-225) SD units of PAM-AMA, respectively. The cumulative effect of the LoF was associated with diabetes, reduced insulin secretion, and higher levels of GH and IGF-1. Moreover, carriers had reduced muscle mass and function, followed by a higher risk of sarcopenia. Indeed, the Ser539Trp mutation increased the risk of sarcopenia by 30% (odds ratio 1.31; 95% CI: 1.16/1.47; P = 9.8E-06), independently of age and diabetes.

CONCLUSION

PAM-AMA genetic deficiency results in a prediabetic sarcopenic phenotype. Early identification of PAM LoF carriers would allow targeted exercise interventions and calls for novel therapies that restore enzymatic activity.

Longitudinal lipidomic signatures of all-cause and CVD mortality in American Indians: findings from the Strong Heart Study

Dyslipidemia is an independent and modifiable risk factor for aging and age-related disorders. Routine lipid panel cannot capture all individual lipid species in blood (i.e., blood lipidome). To date, a comprehensive assessment of the blood lipidome associated with mortality is lacking in large-scale community-dwelling individuals, especially in a longitudinal setting. Using liquid chromatograph-mass spectrometry, we repeatedly measured individual lipid species in 3,821 plasma samples collected at two visits (~ 5.5 years apart) from 1,930 unique American Indians in the Strong Heart Family Study. We first identified baseline lipids associated with risks for all-cause mortality and CVD mortality (mean follow-up period: 17.8 years) in American Indians, followed by replication of top hits in European Caucasians in the Malmö Diet and Cancer-Cardiovascular Cohort (n = 3,943, mean follow-up period: 23.7 years). The model adjusted age, sex, BMI, smoking, hypertension, diabetes, and LDL-c at baseline. We then examined the associations between changes in lipid species and risk of mortality. Multiple testing was controlled by false discovery rate (FDR). We found that baseline levels and longitudinal changes of multiple lipid species, e.g., cholesterol esters, glycerophospholipids, sphingomyelins, and triacylglycerols, were significantly associated with risks of all-cause or CVD mortality. Many lipids identified in American Indians could be replicated in European Caucasians. Network analysis identified differential lipid networks associated with risk of mortality. Our findings provide novel insight into the role of dyslipidemia in disease mortality and offer potential biomarkers for early prediction and risk reduction in American Indians and other ethnic groups.

Growth hormone concentration and risk of all-cause and cardiovascular mortality: The REasons for Geographic And Racial Disparities in Stroke (REGARDS) study

BACKGROUND AND AIMS

Identifying individuals at elevated risk for mortality, especially from cardiovascular disease, may help guide testing and treatment. Risk factors for mortality differ by sex and race. We investigated the association of growth hormone (GH) with all-cause and cardiovascular mortality in a racially diverse cohort in the United States.

METHODS

Among an age, sex and race stratified subgroup of 1046 Black and White participants from the REasons for Geographic And Racial Disparities in Stroke (REGARDS) study, 881 had GH available; values were log₂ transformed. Associations with all-cause and cardiovascular mortality were assessed in the whole subgroup, and by sex and race, using multivariable Cox-proportional hazard models and C-index.

RESULTS

The mean age was 67.4 years, 51.1% were women, and 50.2% were Black participants. The median GH was 280 (interquartile range 79-838) ng/L. There were 237 deaths and 74 cardiovascular deaths over a mean of 8.0 years. In multivariable Cox analysis, GH was associated with higher risk of all-cause mortality per doubling (hazard ratio [HR] 1.17, 95% confidence interval [CI] 1.09-1.25) and cardiovascular mortality (HR 1.21, 95% CI 1.06-1.37). The association did not differ by sex or race (interaction p > 0.05). The addition of GH to a model of clinical variables significantly improved the C-index compared to clinical model alone for all-cause and cardiovascular death.

CONCLUSIONS

Higher fasting GH was associated with higher risk of all-cause and cardiovascular mortality and improved risk prediction, regardless of sex or race.

An appetite for growth: The role of the hypothalamic - pituitary - growth hormone axis in energy balance

Links between the regulation of growth and energy balance are clear; to fuel growth, there must be consumption of energy. Therefore, it is perhaps intuitive that interactions between the hypothalamic - pituitary - growth hormone axis (growth axis) and pathways that drive metabolic processes exist. Overproduction of growth hormone has been associated with diabetes and metabolic disease for decades and the opposing effects of growth hormone and insulin have been studied since early experiments almost a century ago. The relationship between neuroendocrine axes can be complex and the growth axis is no exception, interacting with energy balance in several organ systems, both in the periphery and centrally in hypothalamic nuclei. Much is known about peripheral interactions between growth axis hormones and processes such as glucose homeostasis and adipogenesis. More is still being learned about the molecular actions of growth axis hormones in adipose and other metabolically active tissues, and recent findings are discussed in this perspective. However, less is known about interactions with central energy balance pathways in the hypothalamus. This perspective aims to summarise what is known about these interactions, taking lessons from human studies and animal genetic and seasonal models, and discusses what this may mean in an evolving landscape of personalised medicine.

Circulating levels of growth hormone in postural orthostatic tachycardia syndrome

Postural orthostatic tachycardia syndrome (POTS) is a cardiovascular autonomic disorder with poorly understood etiology and underlying pathophysiology. Since cardiovascular morbidity has been linked to growth hormone (GH), we studied GH levels in patients with POTS. We conducted an age-sex-matched case-control study in patients with POTS (age 31 ± 9 years; n = 42) and healthy controls (32 ± 9 years; n = 46). Plasma GH levels were measured using high-sensitivity chemiluminescence sandwich immunoassay. The burden of orthostatic intolerance symptoms was assessed by the Orthostatic Hypotension Questionnaire (OHQ), consisting of a symptom assessment scale (OHSA) and a daily activity scale (OHDAS). POTS patients had significantly higher composite OHQ score than controls, more symptoms and less activity. Supine heart rate and diastolic blood pressure (BP), but not systolic BP, were significantly higher in POTS. Median plasma GH levels were significantly lower in POTS (0.53 ng/mL) than controls (2.33 ng/mL, p = 0.04). GH levels were inversely related to OHDAS in POTS and supine systolic BP in POTS and controls, but not heart rate neither group. POTS is associated with lower GH levels. Impairment of daily life activities is inversely related with GH in POTS. A higher supine diastolic BP is inversely associated with GH levels in POTS and healthy individuals.

Methodological considerations for identifying multiple plasma proteins associated with all-cause mortality in a population-based prospective cohort

Novel methods to characterize the plasma proteome has made it possible to examine a wide range of proteins in large longitudinal cohort studies, but the complexity of the human proteome makes it difficult to identify robust protein-disease associations. Nevertheless, identification of individuals at high risk of early mortality is a central issue in clinical decision making and novel biomarkers may be useful to improve risk stratification. With adjustment for established risk factors, we examined the associations between 138 plasma proteins measured using two proximity extension assays and long-term risk of all-cause mortality in 3,918 participants of the population-based Malmö Diet and Cancer Study. To examine the reproducibility of protein-mortality associations we used a two-step random-split approach to simulate a discovery and replication cohort and conducted analyses using four different methods: Cox regression, stepwise Cox regression, Lasso-Cox regression, and random survival forest (RSF). In the total study population, we identified eight proteins that associated with all-cause mortality after adjustment for established risk factors and with Bonferroni correction for multiple testing. In the two-step analyses, the number of proteins selected for model inclusion in both random samples ranged from 6 to 21 depending on the method used. However, only three proteins were consistently included in both samples across all four methods (growth/differentiation factor-15 (GDF-15), N-terminal pro-B-type natriuretic peptide, and epididymal secretory protein E4). Using the total study population, the C-statistic for a model including established risk factors was 0.7222 and increased to 0.7284 with inclusion of the most predictive protein (GDF-15; P < 0.0001). All multiple protein models showed additional improvement in the C-statistic compared to the single protein model (all P < 0.0001). We identified several plasma proteins associated with increased risk of all-cause mortality independently of established risk factors. Further investigation into the putatively causal role of these proteins for longevity is needed. In addition, the examined methods for identifying multiple proteins showed tendencies for overfitting by including several putatively false positive findings. Thus, the reproducibility of findings using such approaches may be limited.

Association of Childhood Growth Hormone Treatment With Long-term Cardiovascular Morbidity

IMPORTANCE

Concerns about the cardiovascular safety of recombinant human growth hormone (rhGH) treatment in childhood have recently been raised; however, long-term studies are limited.

OBJECTIVE

To investigate the long-term risk of overall and severe cardiovascular events in patients previously treated with rhGH in childhood and whether there is an association with treatment duration or dose.

DESIGN, SETTING, AND PARTICIPANTS

This nationwide population-based cohort study included patients treated with rhGH during childhood from January 1, 1985, to December 31, 2010, in Sweden, with follow-up through December 31, 2014. Included patients were treated with rhGH owing to isolated growth hormone deficiency (GHD), small for gestational age (SGA), and idiopathic short stature (ISS). For each patient, 15 age-, sex-, and region-based matched control individuals were randomly selected from the general population as a comparison group. Data on cardiovascular outcomes and covariates including gestational age, birth weight, birth length, socioeconomic status, and height were obtained through linkage with several health care and population-based registers. Data were analyzed from January 1, 1985, to December 31, 2014.

EXPOSURES

Treatment with rhGH during childhood and adolescence (aged 0-18 years).

MAIN OUTCOMES AND MEASURES

The primary outcome was the first cardiovascular event recorded after the start of follow-up, and the secondary outcome was the first severe cardiovascular event.

RESULTS

A total of 53 444 individuals (3408 patients and 50 036 controls; 67.7% men; mean [SD] age at study end, 25.1 [8.2] years) were followed up for as long as 25 years (median follow-up, 14.9 [range, 0-25] years; total, 795 125 person-years). Among 1809 recorded cardiovascular events, the crude incidence rates were 25.6 events per 10 000 person-years for patients and 22.6 events per 10 000 person-years for controls. The adjusted hazard ratio (HR) for all cardiovascular events was higher in patients compared with controls (HR, 1.69; 95% CI, 1.30-2.19), especially for women (HR, 2.05; 95% CI, 1.31-3.20) compared with men (HR, 1.55; 95% CI, 1.12-2.13). All subgroups had increased HRs (SGA, 1.97 [95% CI, 1.28-3.04]; GHD, 1.66 [95% CI, 1.21-2.26]; and ISS, 1.55 [95% CI, 1.01-2.37]). Longer duration of rhGH treatment (HR, 2.08; 95% CI, 1.35-3.20) and total cumulative dose (HR, 2.05; 95% CI, 1.18-3.55) were associated with higher risk for overall cardiovascular disease. The adjusted HR for severe cardiovascular disease was 2.27 (95% CI, 1.01-5.12).

CONCLUSIONS AND RELEVANCE

In this cohort study, treatment with rhGH during childhood due to GHD, SGA, or ISS was associated with increased risks of cardiovascular events in early adulthood, particularly in women; however, conclusions of causality are still limited and the absolute risk remains low.

Cardiovascular effects of growth hormone (GH) treatment on GH-deficient adults: a meta-analysis update

BACKGROUND

It is still unclear whether growth hormone (GH) replacement is able to improve cardiovascular parameters in adults with GH deficiency (AGHD) from the updated clinical trials reported to date.

METHODS AND RESULTS

We systematically reviewed clinical trials of GH treatment on AGHD patients in recent decade, and evaluated the effects of GH on cardiovascular parameters assessed by echocardiography. 11 clinical trials were identified in 3 bibliographic databases. We conducted a combined analysis of effects on four aspects: General indicators: baseline heart rate (BHR), peak heart rate (PHR), systolic blood pressure (SBP), diastolic blood pressure (DBP); Cardiac structure: left ventricular end diastolic volume (LVEDV), left ventricular end systolic volume (LVESV), left ventricular interventricular septum (LVIS), left ventricular mass (LVM), left ventricular posterior wall (LVPW); Cardiovascular function: deceleration time of E wave (DT), E/A ratio (E/A), ejection fraction (EF), NT-BNP; Life quality: peak VO₂, VE/VCO₂ slope. Overall effect size was used to evaluate significance, and weighted mean difference after GH treatment was given to appreciate size of the effect. GH treatment was associated with a significant increase in BHR (3.03[2.00, 4.06]), LVIS (0.50[0.43, 0.57]), LVPW (0.50[0.43, 0.57]), and EF (2.12[1.34, 2.90]). Overall effect sizes were negative significant for DBP (- 1.19[- 2.33, - 0.05]), LVEDV (- 9.84[- 16.53, - 3.15]), NT-BNP (- 206.34[- 308.95, - 103.72]), and VE/VCO2 slope (- 2.31[- 2.92, - 1.71]).

CONCLUSIONS

As assessed by echocardiography, GH administration may improve the general vital signs and life quality of AGHD patients, based on the positive effect on BHR and negative effects on DBP and VE/VCO₂ slope. Also, GH treatment would influence the structure of heart with positive effects on LVIS, LVPW and negative effect on LVEDV, which together with the increase of EF and decrease of NT-BNP, then resulting in improving the systolic function of AGHD patients.

Proteomic analysis reveals sex-specific biomarker signature in postural orthostatic tachycardia syndrome

Background

Postural orthostatic tachycardia syndrome (POTS) is a variant of cardiovascular (CV) autonomic disorder of unknown etiology characterized by an excessive heart rate increase on standing and orthostatic intolerance. In this study we sought to identify novel CV biomarkers potentially implicated in POTS pathophysiology.

Methods

We conducted a nested case-control study within the Syncope Study of Unselected Population in Malmö (SYSTEMA) cohort including 396 patients (age range, 15–50 years) with either POTS (n = 113) or normal hemodynamic response during passive head-up-tilt test (n = 283). We used a targeted approach to explore changes in cardiovascular proteomics associated with POTS through a sequential two-stage process including supervised principal component analysis and univariate ANOVA with Bonferroni correction.

Results

POTS patients were younger (26 vs. 31 years; p < 0.001) and had lower BMI than controls. The discovery algorithm identified growth hormone (GH) and myoglobin (MB) as the most specific biomarker fingerprint for POTS. Plasma level of GH was higher (9.37 vs 8.37 of normalised protein expression units (NPX); p = 0.002), whereas MB was lower (4.86 vs 5.14 NPX; p = 0.002) in POTS compared with controls. In multivariate regression analysis, adjusted for age and BMI, and stratified by sex, lower MB level in men and higher GH level in women remained independently associated with POTS.

Conclusions

Cardiovascular proteomics analysis revealed sex-specific biomarker signature in POTS featured by higher plasma level of GH in women and lower plasma level of MB in men. These findings point to sex-specific immune-neuroendocrine dysregulation and deconditioning as potentially key pathophysiological traits underlying POTS.

Detection of early breast cancer beyond mammographic screening: a promising biomarker panel

Aim: We assessed the suitability of a biomarker panel to improve early detection and individual risk assessment in breast cancer (BC) patients. Materials & methods: PENK, pro-SP, hGH and CA15-3 of 204 BC patients and 68 healthy controls were measured. Results: PENK and human growth hormone concentrations were significantly lower and pro-SP values higher in BC patients compared with controls. C-index increased from 0.628 for CA15-3 alone to 0.754 when all three biomarkers were added to the model. Conclusion: This biomarker panel may improve early detection of BC and influence the assessment of breast imaging. It might be useful for a risk-adapted cancer surveillance or primary prevention program by a more precise determination of an individualized BC risk.

Sex-Specific Cut-Offs for High-Sensitivity Cardiac Troponin: Is Less More?

Management of patients presenting to the Emergency Department with chest pain is continuously evolving. In the setting of acute coronary syndrome, the availability of high-sensitivity cardiac troponin assays (hs-cTn) has allowed for the development of algorithms aimed at rapidly assessing the risk of an ongoing myocardial infarction. However, concerns were raised about the massive application of such a simplified approach to heterogeneous real-world populations. As a result, there is a potential risk of underdiagnosis in several clusters of patients, including women, for whom a lower threshold for hs-cTn was suggested to be more appropriate. Implementation in clinical practice of sex-tailored cut-off values for hs-cTn represents a hot topic due to the need to reduce inequality and improve diagnostic performance in females. The aim of this review is to summarize current evidence on sex-specific cut-off values of hs-cTn and their application and usefulness in clinical practice. We also offer an extensive overview of thresholds reported in literature and of the mechanisms underlying such differences among sexes, suggesting possible explanations about debated issues.

Towards frailty biomarkers: Candidates from genes and pathways regulated in aging and age-related diseases

OBJECTIVE

Use of the frailty index to measure an accumulation of deficits has been proven a valuable method for identifying elderly people at risk for increased vulnerability, disease, injury, and mortality. However, complementary molecular frailty biomarkers or ideally biomarker panels have not yet been identified. We conducted a systematic search to identify biomarker candidates for a frailty biomarker panel.

METHODS

Gene expression databases were searched (http://genomics.senescence.info/genes including GenAge, AnAge, LongevityMap, CellAge, DrugAge, Digital Aging Atlas) to identify genes regulated in aging, longevity, and age-related diseases with a focus on secreted factors or molecules detectable in body fluids as potential frailty biomarkers. Factors broadly expressed, related to several "hallmark of aging" pathways as well as used or predicted as biomarkers in other disease settings, particularly age-related pathologies, were identified. This set of biomarkers was further expanded according to the expertise and experience of the authors. In the next step, biomarkers were assigned to six "hallmark of aging" pathways, namely (1) inflammation, (2) mitochondria and apoptosis, (3) calcium homeostasis, (4) fibrosis, (5) NMJ (neuromuscular junction) and neurons, (6) cytoskeleton and hormones, or (7) other principles and an extensive literature search was performed for each candidate to explore their potential and priority as frailty biomarkers.

RESULTS

A total of 44 markers were evaluated in the seven categories listed above, and 19 were awarded a high priority score, 22 identified as medium priority and three were low priority. In each category high and medium priority markers were identified.

CONCLUSION

Biomarker panels for frailty would be of high value and better than single markers. Based on our search we would propose a core panel of frailty biomarkers consisting of (1) CXCL10 (C-X-C motif chemokine ligand 10), IL-6 (interleukin 6), CX3CL1 (C-X3-C motif chemokine ligand 1), (2) GDF15 (growth differentiation factor 15), FNDC5 (fibronectin type III domain containing 5), vimentin (VIM), (3) regucalcin (RGN/SMP30), calreticulin, (4) PLAU (plasminogen activator, urokinase), AGT (angiotensinogen), (5) BDNF (brain derived neurotrophic factor), progranulin (PGRN), (6) α-klotho (KL), FGF23 (fibroblast growth factor 23), FGF21, leptin (LEP), (7) miRNA (micro Ribonucleic acid) panel (to be further defined), AHCY (adenosylhomocysteinase) and KRT18 (keratin 18). An expanded panel would also include (1) pentraxin (PTX3), sVCAM/ICAM (soluble vascular cell adhesion molecule 1/Intercellular adhesion molecule 1), defensin α, (2) APP (amyloid beta precursor protein), LDH (lactate dehydrogenase), (3) S100B (S100 calcium binding protein B), (4) TGFβ (transforming growth factor beta), PAI-1 (plasminogen activator inhibitor 1), TGM2 (transglutaminase 2), (5) sRAGE (soluble receptor for advanced glycosylation end products), HMGB1 (high mobility group box 1), C3/C1Q (complement factor 3/1Q), ST2 (Interleukin 1 receptor like 1), agrin (AGRN), (6) IGF-1 (insulin-like growth factor 1), resistin (RETN), adiponectin (ADIPOQ), ghrelin (GHRL), growth hormone (GH), (7) microparticle panel (to be further defined), GpnmB (glycoprotein nonmetastatic melanoma protein B) and lactoferrin (LTF). We believe that these predicted panels need to be experimentally explored in animal models and frail cohorts in order to ascertain their diagnostic, prognostic and therapeutic potential.

Renal sulfate reabsorption in healthy individuals and renal transplant recipients

Inorganic sulfate is essential for normal cellular function and its homeostasis is primarily regulated in the kidneys. However, little is known about renal sulfate handling in humans and particularly in populations with impaired kidney function such as renal transplant recipients (RTR). Hence, we aimed to assess sulfate reabsorption in kidney donors and RTR. Plasma and urinary sulfate were determined in 671 RTR and in 251 kidney donors. Tubular sulfate reabsorption (TSR) was defined as filtered load minus sulfate excretion and fractional sulfate reabsorption (FSR) was defined as 1-fractional excretion. Linear regression analyses were employed to explore associations of FSR with baseline parameters and to identify the determinants of FSR in RTR. Compared to kidney donors, RTR had significantly lower TSR (15.2 [11.2-19.5] vs. 20.3 [16.7-26.3] μmol/min), and lower FSR (0.56 [0.48-0.64] vs. 0.64 [0.57-0.69]) (all P < 0.001). Kidney donation reduced both TSR and FSR by circa 50% and 25% respectively (both P < 0.001). In RTR and donors, both TSR and FSR associated positively with renal function. In RTR, FSR was independently associated with urinary thiosulfate (β = -0.18; P = 0.002), growth hormone (β = 0.12; P = 0.007), the intakes of alcohol (β = -0.14; P = 0.002), methionine (β = -0.34; P < 0.001), cysteine (β = -0.41; P < 0.001), and vitamin D (β = -0.14; P = 0.009). In conclusion, TSR and FSR are lower in RTR compared to kidney donors and both associated with renal function. Additionally, FSR is determined by various dietary and metabolic factors. Future research should determine the mechanisms behind sulfate handling in humans and the prognostic value of renal sulfate reabsorption in RTR.

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.

Genetic determinants of growth hormone and GH-related phenotypes

Background

Higher fasting Growth Hormone (GH) has been associated with increased cardiovascular morbidity and mortality. Our objective was to find genetic determinants of fasting GH in order to facilitate future efforts of analyzing the association between fasting growth hormone and cardiovascular disease. A genome-wide association study (GWAS) was performed in a discovery cohort of 4134 persons (58% females; age 46–68 yrs), linking SNPs to fasting hs-GH. Fifteen SNPs were replicated in an independent cohort of 5262 persons (28.9% females; age 56–85 yrs). The best performing SNP was analyzed vs GH-related variables in a third independent cohort (n = 24,047; 61% females; age 44–73 yrs). A candidate gene approach searched for significant SNPs in the genes GH1 and GHR in the discovery cohort and was replicated as previously described.

Results

In the GWAS, the minor allele of rs7208736 was associated with lower GH in the discovery cohort (p = 5.15*10^-6) and the replication cohort (p = 0.005). The GH reducing allele was associated with lower BMI (P = 0.026) and waist (P = 0.021) in males only. In the candidate gene approach rs13153388 in the GHR-gene was associated with elevated GH-levels (P = 0.003) in the discovery cohort only and reduced height (P = 0.003).

Conclusion

In the first GWAS ever for GH, we identify a novel locus on chromosome 17 associated with fasting GH levels, suggesting novel biological mechanisms behind GH secretion and GH-related traits. The candidate gene approach identified a genetic variant in the GHR, which was associated with an elevation of fasting hs-GH and lower height suggesting reduced GHR ligand sensitivity. Our findings need further replication.

Electronic supplementary material

The online version of this article (10.1186/s12864-017-4219-z) contains supplementary material, which is available to authorized users.

A Functional Interplay between IGF-1 and Adiponectin

A functional relationship is suggested between two well-known protein hormones, insulin-like growth factor 1 (IGF-1) and adiponectin. In the last two decades in fact, different experimental evidence has indicated a non-random link between them. Here, we describe briefly the IGF-1 and adiponectin systems, and we then focus on their putative interplay in relation to several pathological conditions, including obesity, diabetes, insulin resistance, cardiovascular disease, and cancer. Although the existing studies are hardly comparable, they definitely indicate a functional connection between these two protein hormones. In conclusion, the current knowledge strongly encourages further research into the common, as well as novel, mechanisms through which IGF-1 and adiponectin exert their concerted action.

Fasting levels of growth hormone are associated with carotid intima media thickness but are not affected by fluvastatin treatment

Background

Growth hormone (GH) has been linked to cardiovascular disease but the exact mechanism of this association is still unclear. We here test if the fasting levels of GH are cross-sectionally associated with carotid intima media thickness (IMT) and whether treatment with fluvastatin affects the fasting level of GH.

Methods

We examined the association between GH and IMT in 4425 individuals (aged 46–68 years) included in the baseline examination (1991–1994) of the Malmö Diet and Cancer cardiovascular cohort (MDC-CC). From that cohort we then studied 472 individuals (aged 50-70 years) who also participated (1994–1999) in the β-Blocker Cholesterol-Lowering Asymptomatic Plaque Study (BCAPS), a randomized, double blind, placebo-controlled, single-center clinical trial. Using multivariate linear regression models we related the change in GH-levels at 12 months compared with baseline to treatment with 40 mg fluvastatin once daily.

Results

In MDC-CC fasting values of GH exhibited a positive cross-sectional relation to the IMT at the carotid bulb independent of traditional cardiovascular risk factors (p = 0.002). In a gender-stratified analysis the correlation were significant for males (p = 0.005), but not for females (p = 0.09). Treatment with fluvastatin was associated with a minor reduction in the fasting levels of hs-GH in males (p = 0.05) and a minor rise in the same levels among females (p = 0.05).

Conclusions

We here demonstrate that higher fasting levels of GH are associated with thicker IMT in the carotid bulb in males. Treatment with fluvastatin for 12 months only had a minor, and probably not clinically relevant, effect on the fasting levels of hs-GH.

Electronic supplementary material

The online version of this article (doi:10.1186/s12872-017-0563-9) contains supplementary material, which is available to authorized users.

Metabolic alterations in paediatric GH deficiency

Growth hormone (GH) has a large number of metabolic effects, involving lipid and glucose homoeostasis, lean and fat mass. Growth hormone deficiency (GHD) is associated with a metabolic profile similar to the Metabolic Syndrome which is characterized by dyslipidemia, insulin resistance, haemostatic alterations, oxidative stress, and chronic inflammation. GH replacement treatment in GHD children improves these cardiovascular risk factors, while cessation of GH is associated with a deterioration of most of these risk factors. However, it is unclear whether the changes of these risk factors are associated with an increased risk of cardiovascular diseases especially after discontinuing GH treatment. GH treatment itself can lead to insulin resistance, which probably also influences the cardiovascular health status. Therefore, longitudinal studies with the primary outcome cardiovascular diseases are needed in GHD children. Furthermore, new approaches such as metabolomic studies might be helpful to understand the relationship between GHD, GH treatment, and cardiovascular diseases.

Plasma N-terminal Prosomatostatin and Risk of Incident Cardiovascular Disease and All-Cause Mortality in a Prospective Observational Cohort: the PREVEND Study

BACKGROUND

Somatostatin is a component of the well-known insulin-like growth factor-1/growth hormone (GH) longevity axis. There is observational evidence that increased GH is associated with an increased risk of cardiovascular disease (CVD). We aimed to investigate the potential association of plasma N-terminal fragment prosomatostatin (NT-proSST) with incident CVD and all-cause mortality in apparently healthy adults.

METHODS

We studied 8134 participants without history of CVD (aged 28-75 years; women, 52.6%) from the Prevention of Renal and Vascular End-stage Disease (PREVEND) study in Groningen, the Netherlands. Plasma NT-proSST was measured in baseline samples. Outcomes were incidence of CVD and all-cause mortality.

RESULTS

In cross-sectional analyses, NT-proSST [mean (SD), 384.0 (169.3) pmol/L] was positively associated with male sex and age (both P < 0.001). During a median follow-up of 10.5 (Q1-Q3: 9.9-10.8) years, 708 (8.7%) participants developed CVD and 517 (6.4%) participants died. In univariable analyses, NT-proSST was associated with an increased risk of incident CVD and all-cause mortality (both P < 0.001). In multivariable analyses, these associations were independent of the Framingham risk factors, with hazard ratios (95% CI) per doubling of NT-proSST of 1.17 (1.03-1.34; P = 0.02) for incident CVD and of 1.28 (1.09-1.49; P = 0.002) for all-cause mortality. Addition of NT-proSST to the updated Framingham Risk Score improved reclassification (integrated discrimination improvement (P < 0.001); net reclassification improvement was 2.5% (P = 0.04)).

CONCLUSIONS

Plasma NT-proSST is positively associated with increased risk of future CVD and all-cause mortality, partly independent of traditional CVD risk factors. Further research is needed to address the nature of associations.

N-Terminal Prosomatostatin as a Risk Marker for Cardiovascular Disease and Diabetes in a General Population

CONTEXT

Somatostatin inhibits a range of hormones, including GH, insulin, and glucagon, but little is known about its role in the development of cardiometabolic disease.

OBJECTIVE

The objective of the study was to investigate whether fasting plasma concentration of N-terminal prosomatostatin (NT-proSST) is associated with the development of diabetes, coronary artery disease (CAD), and mortality.

DESIGN, SETTING, AND PARTICIPANTS

NT-proSST was measured in plasma from 5389 fasting participants of the population-based study Malmö Preventive Project, with a mean baseline age of 69.4 ± 6.2 years. Cox proportional hazards models adjusted for traditional cardiovascular risk factors were used to investigate the relationships between baseline NT-proSST and end points, with a mean follow-up of 5.6 ± 1.4 years.

MAIN OUTCOME MEASURES

CAD, diabetes, and mortality were measured.

RESULTS

Overall, NT-proSST (hazard ratio [HR] per SD increment of log transformed NT-proSST) was unrelated to the risk of incident diabetes (220 events; HR 1.05; 95% confidence interval [CI] 0.91-1.20; P = .531) but was related to the risk of incident CAD (370 events; HR 1.17; 95% CI 1.06-1.30; P = .003), all-cause mortality (756 events; HR 1.24; 95% CI 1.15-1.33; P < .001), and cardiovascular mortality (283 events; HR 1.33; 95% CI 1.19-1.43; P < .001). The relationships were not linear, with most of the excess risk observed in subjects with high values of NT-proSST. Subjects in the top vs bottom decile had a severely increased risk of incident CAD (HR 2.41; 95% CI 1.45-4.01; P < .001), all-cause mortality (HR 1.84; 95% CI 1.33-2.53; P < .001), and cardiovascular mortality (HR 2.44; 95% CI 1.39-4.27; P < .001).

CONCLUSION

NT-proSST was significantly and independently associated with the development of CAD, all-cause mortality, and cardiovascular mortality.

Associations Between the Serum Metabolome and All-Cause Mortality Among African Americans in the Atherosclerosis Risk in Communities (ARIC) Study

Early and accurate identification of people at high risk of premature death may assist in the targeting of preventive therapies in order to improve overall health. To identify novel biomarkers for all-cause mortality, we performed untargeted metabolomics in the Atherosclerosis Risk in Communities (ARIC) Study. We included 1,887 eligible ARIC African Americans, and 671 deaths occurred during a median follow-up period of 22.5 years (1987-2011). Chromatography and mass spectroscopy identified and quantitated 204 serum metabolites, and Cox proportional hazards models were used to analyze the longitudinal associations with all-cause and cardiovascular mortality. Nine metabolites, including cotinine, mannose, glycocholate, pregnendiol disulfate, α-hydroxyisovalerate, N-acetylalanine, andro-steroid monosulfate 2, uridine, and γ-glutamyl-leucine, showed independent associations with all-cause mortality, with an average risk change of 18% per standard-deviation increase in metabolite level (P < 1.23 × 10(-4)). A metabolite risk score, created on the basis of the weighted levels of the identified metabolites, improved the predictive ability of all-cause mortality over traditional risk factors (bias-corrected Harrell's C statistic 0.752 vs. 0.730). Mannose and glycocholate were associated with cardiovascular mortality (P < 1.23 × 10(-4)), but predictive ability was not improved beyond the traditional risk factors. This metabolomic analysis revealed potential novel biomarkers for all-cause mortality beyond the traditional risk factors.

Growth hormone for risk stratification and effects of therapy in acute myocardial infarction

CONTEXT

Excess growth hormone (GH) is associated with early mortality.

OBJECTIVES

We assessed the association of GH with prognosis after acute myocardial infarction (AMI), and the effects of secondary prevention therapies.

METHODS

GH was measured using a high-sensitivity assay in 953 AMI patients (687 males, mean age 66.1 ± 12.8 years).

RESULTS

During 2 years follow-up, there were 281 major adverse cardiac events (MACE). Patients with MACE had higher GH levels (median [range], 0.91 [0.04-26.28] μg/L) compared to event-free survivors (0.59 [0.02-21.6], p < 0.0005). In multivariate Cox survival analysis, GH was a significant predictor of MACE (hazard ratios 1.43, p = 0.026 and 1.49, p = 0.01, respectively) with significant interactions with beta blocker therapy (p = 0.047) and angiotensin converting enzyme inhibitor or angiotensin receptor blocker (ACE/ARB) therapy (p = 0.016).

CONCLUSIONS

GH levels post-AMI are prognostic for MACE and may indicate those patients who benefit from beta blocker and ACE/ARB therapy.

Cardiovascular biomarkers and sex: the case for women

Measurement of biomarkers is a critical component of cardiovascular care. Women and men differ in their cardiac physiology and manifestations of cardiovascular disease. Although most cardiovascular biomarkers are used by clinicians without taking sex into account, sex-specific differences in biomarkers clearly exist. Baseline concentrations of many biomarkers (including cardiac troponin, natriuretic peptides, galectin-3, and soluble ST2) differ in men versus women, but these sex-specific differences do not generally translate into a need for differential sex-based cut-off points. Furthermore, most biomarkers are similarly diagnostic and prognostic, regardless of sex. Two potential exceptions are cardiac troponins measured by high-sensitivity assay, and proneurotensin. Troponin levels are lower in women than in men and, with the use of high-sensitivity assays, sex-specific cut-off points might improve the diagnosis of myocardial infarction. Proneurotensin is a novel biomarker that was found to be predictive of incident cardiovascular disease in women, but not men, and was also predictive of incident breast cancer. If confirmed, proneurotensin might be a unique biomarker of disease risk in women. With any biomarker, an understanding of sex-specific differences might improve its use and might also lead to an enhanced understanding of the physiological differences between the hearts of men and women.

Analysis of Low Frequency Protein Truncating Stop-Codon Variants and Fasting Concentration of Growth Hormone

Background

The genetic background of Growth Hormone (GH) secretion is not well understood. Mutations giving rise to a stop codon have a high likelihood of affecting protein function.

Objectives

To analyze likely functional stop codon mutations that are associated with fasting plasma concentration of Growth Hormone.

Methods

We analyzed stop codon mutations in 5451 individuals in the Malmö Diet and Cancer study by genotyping the Illumina Exome Chip. To enrich for stop codon mutations with likely functional effects on protein function, we focused on those disrupting >80% of the predicted amino acid sequence, which were carried by ≥10 individuals. Such mutations were related to GH concentration, measured with a high sensitivity assay (hs-GH) and, if nominally significant, to GH related phenotypes, using linear regression analysis.

Results

Two stop codon mutations were associated with the fasting concentration of hs-GH. rs121909305 (NP_005370.1:p.R93*) [Minor Allele Frequency (MAF) = 0.8%] in the Myosin 1A gene (MYO1A) was associated with a 0.36 (95%CI, 0.04 to 0.54; p=0.02) increment of the standardized value of the natural logarithm of hs-GH per 1 minor allele and rs35699176 (NP_067040.1:p.Q100*) in the Zink Finger protein 77 gene (ZNF77) (MAF = 4.8%) was associated with a 0.12 (95%CI, 0.02 to 0.22; p = 0.02) increase of hs-GH. The mutated high hs-GH associated allele of MYO1A was related to lower BMI (β-coefficient, -0.22; p = 0.05), waist (β-coefficient, -0.22; p = 0.04), body fat percentage (β-coefficient, -0.23; p = 0.03) and with higher HDL (β-coefficient, 0.23; p = 0.04). The ZNF77 stop codon was associated with height (β-coefficient, 0.11; p = 0.02) but not with cardiometabolic risk factors.

Conclusion

We here suggest that a stop codon of MYO1A, disrupting 91% of the predicted amino acid sequence, is associated with higher hs-GH and GH-related traits suggesting that MYO1A is involved in GH metabolism and possibly body fat distribution. However, our results are preliminary and need replication in independent populations.

Molecular effects of supraphysiological doses of doping agents on health

Supraphysiological doses of doping agents, such as T/DHT and GH/IGF-1, affect cellular pathways associated with apoptosis and inflammation.