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

Assessing causal associations of blood counts and biochemical indicators with pulmonary arterial hypertension: a Mendelian randomization study and results from national health and nutrition examination survey 2003-2018

Background

Blood counts and biochemical markers are among the most common tests performed in hospitals and most readily accepted by patients, and are widely regarded as reliable biomarkers in the literature. The aim of this study was to assess the causal relationship between blood counts, biochemical indicators and pulmonary arterial hypertension (PAH).

Methods

A two-sample Mendelian randomization (MR) analysis was performed to assess the causal relationship between blood counts and biochemical indicators with PAH. The genome-wide association study (GWAS) for blood counts and biochemical indicators were obtained from the UK Biobank (UKBB), while the GWAS for PAH were sourced from the FinnGen Biobank. Inverse variance weighting (IVW) was used as the primary analysis method, supplemented by three sensitivity analyses to assess the robustness of the results. And we conducted an observational study using data from National Health and Nutrition Examination Survey (NHANES) 2003-2018 to verify the relationship.

Results

The MR analysis primarily using the IVW method revealed genetic variants of platelet count (OR=2.51, 95% CI 1.56-4.22, P<0.001), platelet crit(OR=1.87, 95% CI1.17-7.65, P=0.022), direct bilirubin (DBIL)(OR=1.71, 95%CI 1.18-2.47,P=0.004), insulin-like growth factor (IGF-1)(OR=0.51, 95% CI 0.27-0.96, P=0.038), Lipoprotein A (Lp(a))(OR=0.66, 95% CI 0.45-0.98, P=0.037) and total bilirubin (TBIL)(OR=0.51, 95% CI 0.27-0.96, P=0.038) were significantly associated with PAH. In NHANES, multivariate logistic regression analyses revealed a significant positive correlation between platelet count and volume and the risk of PAH, and a significant negative correlation between total bilirubin and PAH.

Conclusion

Our study reveals a causal relationship between blood counts, biochemical indicators and pulmonary arterial hypertension. These findings offer novel insights into the etiology and pathological mechanisms of PAH, and emphasizes the important value of these markers as potential targets for the prevention and treatment of PAH.

Importance of 24 h ambulatory blood pressure monitoring in patients with acromegaly and correlation with cardiac magnetic resonance findings

INTRODUCTION

Arterial hypertension (AH) is prevalent in acromegaly, but few studies using 24-h ambulatory blood pressure monitoring (24 h-ABPM) suggest that its frequency may be different from office blood pressure (OBP). Left ventricular hypertrophy (LVH) is one of the most frequent cardiac abnormalities. Cardiac magnetic resonance (CMR) is considered the gold standard to evaluate the heart.

OBJECTIVES

To compare the frequency of AH when measured by 24 h-ABPM and by OBP and to correlate BP with cardiac mass.

METHODS

Patients over 18 years of age with acromegaly underwent OBP evaluation and were later referred to the 24 h-ABPM. Treatment-naïve patients were submitted to CMR.

RESULTS

We evaluated 96 patients. From 29 non hypertensive patients by OBP, 9 had AH on 24 h-ABPM. In the group of patients with a previous diagnosis of AH by OBP, 25 had controlled BP and 42 had abnormal BP on 24 h-ABPM, when analyzed by OBP there were 28 with controlled BP. We observed a positive correlation between diastolic BP measured in 24 h-ABPM and IGF-I levels, but we did not observe the same correlation with age, sex, body mass index and GH levels. The CMR was performed in 11 patients. We found a positive correlation of left ventricular mass (LVM) and BP of 24 h-ABPM. In contrast, there was no correlation of OBP with CMR parameters.

CONCLUSIONS

We observed, that 24 h-ABPM in acromegaly allows the diagnosis of AH in some patients with normal BP in OBP and also to allow a better treatment. 24 h-ABPM shows a better correlation with VM by CMR.

Cyclic Glycine-Proline (cGP) Normalises Insulin-Like Growth Factor-1 (IGF-1) Function: Clinical Significance in the Ageing Brain and in Age-Related Neurological Conditions

Insulin-like growth factor-1 (IGF-1) function declines with age and is associated with brain ageing and the progression of age-related neurological conditions. The reversible binding of IGF-1 to IGF binding protein (IGFBP)-3 regulates the amount of bioavailable, functional IGF-1 in circulation. Cyclic glycine-proline (cGP), a metabolite from the binding site of IGF-1, retains its affinity for IGFBP-3 and competes against IGF-1 for IGFBP-3 binding. Thus, cGP and IGFBP-3 collectively regulate the bioavailability of IGF-1. The molar ratio of cGP/IGF-1 represents the amount of bioavailable and functional IGF-1 in circulation. The cGP/IGF-1 molar ratio is low in patients with age-related conditions, including hypertension, stroke, and neurological disorders with cognitive impairment. Stroke patients with a higher cGP/IGF-1 molar ratio have more favourable clinical outcomes. The elderly with more cGP have better memory retention. An increase in the cGP/IGF-1 molar ratio with age is associated with normal cognition, whereas a decrease in this ratio with age is associated with dementia in Parkinson disease. In addition, cGP administration reduces systolic blood pressure, improves memory, and aids in stroke recovery. These clinical and experimental observations demonstrate the role of cGP in regulating IGF-1 function and its potential clinical applications in age-related brain diseases as a plasma biomarker for-and an intervention to improve-IGF-1 function.

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.

A Review of Vascular Traits and Assessment Techniques, and Their Heritability

Various tools are available to assess atherosclerosis, arterial stiffening, and endothelial function. They offer utility in the assessment of hypertensive phenotypes, in cardiovascular risk prediction, and as surrogate endpoints in clinical trials. We explore the relative influence of participant genetics, with reference to large-scale genomic studies, population-based cohorts, and candidate gene studies. We find heritability estimates highest for carotid intima-media thickness (CIMT 35–65%), followed by pulse wave velocity as a measure of arterial stiffness (26–43%), and flow mediated dilatation as a surrogate for endothelial function (14–39%); data were lacking for peripheral artery tonometry. We furthermore examine genes and polymorphisms relevant to each technique. We conclude that CIMT and pulse wave velocity dominate the existing evidence base, with fewer published genomic linkages for measures of endothelial function. We finally make recommendations regarding planning and reporting of data relating to vascular assessment techniques, particularly when genomic data are also available, to facilitate integration of these tools into cardiovascular disease research.

Relationship between circulating insulin-like growth factor-1 and blood pressure in adults: A systematic review and meta-analysis of observational studies

OBJECTIVE

Insulin-like growth factor 1 (IGF-1) is an important factor related to cardiovascular disease. In recent years, studies have shown the involvement of IGF-1 and blood pressure (BP). Nevertheless, the results were inconsistent. Thus, the purpose of this study was to systematically evaluate the associations of circulating IGF-1 levels with BP in adults.

METHODS

Two reviewers independently searched and screened articles from the Pubmed, EMBASE, Cochrane Library, CNKI, and WANFANG databases up to May 2020. A total of 12 studies that reported the correlation coefficients between IGF-1, systolic blood pressure (SBP), and diastolic blood pressure (DBP) were included.

RESULTS

IGF-1 was significantly correlated with SBP [r = -0.15; 95% CI = -0.21, -0.08; P < 0.0001] and DBP [r = -0.10; 95% CI = -0.16, -0.05; P = 0.0004]. Subgroup analysis further revealed that the relationship between IGF-1 and BP was influenced by race and age.

CONCLUSION

Circulating IGF-1 was negatively correlated with SBP and DBP. Further researches are necessary to explore the pathogenesis of this relationship and to evaluate the role of IGF-1 in the treatment of hypertension.

Association between polymorphism at IGF-1 rs35767 gene locus and long-term decline in renal function: a Japanese retrospective longitudinal cohort study

BACKGROUND

Insulin-like growth factor-1 (IGF-1) acts on glucose and protein metabolism and human growth and also influences blood pressure and renal function. This study investigated whether the single-nucleotide polymorphism of IGF-1, rs35767, plays a role in metabolic syndrome indicators, including blood pressure, glucose metabolism, uric acid levels, and renal function.

METHODS

In this retrospective longitudinal cohort study, blood samples from 1506 Japanese individuals were collected and used for genotyping for variant rs35767: T > C in the IGF-1 upstream promoter. Data were analyzed to identify associations between IGF-1 genotypes and patient biochemical parameters, including the components of metabolic syndrome and the long-term change in renal function.

RESULTS

The cohort rs35767 genotypes included 650 CC carriers (43.2%), 687 TC carriers (45.6%), and 169 TT carriers (11.2%). Multiple regression analysis revealed no association between IGF-1 genotype and blood pressure, glycated hemoglobin level, and serum uric acid level. However, in females, blood pressure was negatively correlated with the TT genotype. Longitudinal observation revealed that the decline in eGFR over 10 years was greater in TT (- 18.51 ± 1.04 mL/min/1.73m²) than in CC carriers (- 16.38 ± 0.52 mL/min/1.73m²; P < 0.05).

CONCLUSION

The present study suggests that renal function declines faster in individuals with the TT genotype at the IGF-1 rs35767 locus than in those with the CC genotype, suggesting that the TT genotype is associated with the long-term chronological decline in renal function.

Prevalence of IGFBP3, NOS3 and TCF7L2 polymorphisms and their association with hypertension: a population-based study with Brazilian women of African descent

Objective

African ancestry seems to be a risk factor for hypertension; however, few genetic studies have addressed this issue. This study aimed to investigate the prevalence of polymorphisms NOS3; rs1799983, IGFBP3; rs11977526 and TCF7L2; rs7903146 in Brazilian women of African descent and their association with hypertension.

Results

The prevalences of the less frequent genotypes were 26.5% TT genotype of NOS3; rs1799983, 16.7% AA genotype of IGFBP3; rs11977526, and 18.3% TT genotype of TCF7L2; rs7903146. For these conditions, the prevalence of hypertension and PR (adjusted) relatively to the ancestral genotype were, respectively: 52.0% vs 24.5% (PR = 1.54; p < 0.001), 62.0% vs 24.1% (PR = 1.59; p < 0.001), and 38.9% vs 27.9% (PR = 0.86; p = 0.166). Associations with hypertension were statistically significant, except for the TCF7L2; rs7903146 polymorphism, after adjusted analysis. Brazilian Afro-descendant women with the TT genotype for the NOS3 gene and the AA genotype for the IGFBP3 gene are more susceptible to hypertension. The understanding of underlying mechanisms involving the pathogenesis of hypertension can motivate research for the development of new therapeutic targets related to nitric oxide metabolism and the management of oxidative stress.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13104-021-05598-5.

Advances in Research on the Cardiovascular Complications of Acromegaly

Cardiovascular-related complications are one of the most common complications in patients with acromegaly, and can lead to an increased risk of death. Hypertension and cardiomyopathy are the main cardiovascular complications. The characteristics of acromegalic cardiomyopathy are concentric biventricular hypertrophy and diastolic dysfunction. In addition, arrhythmia and heart valve disease are common cardiac complications in acromegaly. Although the underlying pathophysiology has not been fully elucidated, the spontaneous overproduction of GH and IGF-1, increasing age, prolonged duration of disease and the coexistence of other cardiovascular risk factors are crucial to cardiac complications in patients with acromegaly. Early diagnosis and appropriate treatment of acromegaly might be beneficial for the prevention of cardiomyopathy and premature death.

Association between insulin-like growth factor-1 and systolic blood pressure in children and adolescents with short stature

The relationship between insulin‐like growth factor‐1 (IGF‐1) and systolic blood pressure (SBP) is controversial in adults and children. The purpose of this study was to investigate the relationship between the IGF‐1 standard deviation score (IGF‐1 SDS) and SBP in children with short stature. A cross‐sectional analysis including 1315 children with short stature was conducted from March 2013 to October 2020. We estimated IGF‐1, blood pressure and other laboratory tests, and anthropometric indicators were also evaluated. Subgroup analyses of the pubertal stage, sex, growth hormone levels, thyroid hormone levels, fasting blood glucose levels, and triglyceride levels were performed. A positive association between the IGF‐1 SDS and SBP was observed by univariate analysis (p < .001). We further found a nonlinear association between the IGF‐1 SDS and SBP. The inflection point for the curve was found at an IGF‐1 SDS level of −2.91. In multivariate piecewise linear regression, there was a positive association between the IGF‐1 SDS and SBP when the IGF‐1 SDS was greater than −2.91 (β 1.56, 95% CI: 0.91, 2.22; p < .001). However, we did not observe a significant relationship between the IGF‐1 SDS and SBP when the IGF‐1 SDS level was less than −2.91 (β −0.95, 95% CI −3.17, 1.28; p = .379). This association was consistent across subgroup analyses. The present study demonstrated that there is a nonlinear relationship between the IGF‐1 SDS and SBP in children with short stature. Increased serum IGF‐1 levels were associated with elevated SBP when the IGF‐1 levels reached the inflection point.

Relationship between insulin-like growth factor-1, insulin resistance and metabolic profile with pre-obesity and obesity in children

OBJECTIVES

Childhood obesity is a serious medical condition with alarmingly high rates worldwide. There is controversy regarding the relationship between insulin-like growth factor-1 (IGF-1) and pediatric obesity. We investigated the relationship between IGF-1, insulin resistance and metabolic profile with childhood pre-obesity/obesity.

METHODS

The study involved 201 children aged 7-15 years, divided in three groups according to their nutritional status (International Obesity Task Force criteria): normal-weight (n=84), pre-obese (n=82), obese (n=35). Laboratory IGF-1, insulin, fasting blood glucose (FBG), lipid profile, alanine-aminotransferase (ALT), uric acid (UA), anthropometric and body composition parameters were analyzed. Body mass index and IGF-1 standard deviation score (SDS), waist-to-height ratio (WtHR) and Homeostatic Model Assessment for Insulin Resistance (HOMA-IR) score were calculated.

RESULTS

Pre-obese/obese children had significantly higher IGF-1 SDS, FBG, insulin, HOMA-IR, UA, ALT, triglycerides, and lower high-density lipoprotein cholesterol (HDL-c); obese group had higher WtHR and low-density lipoprotein cholesterol (LDL-c) compared to controls (p<0.05). In obese group, IGF-1 SDS was positively correlated with fat free/muscle mass, total body water (p<0.05) and negatively correlated with LDL-c (p<0.05). In pre-obese/obese HOMA-IR and insulin were positively correlated with age, total body fat (TBF) (p<0.05) and negatively correlated with HDL-c (pre-obese) (p<0.05). Multivariate ordinal logistic regression analyses showed that IGF-1 SDS (OR=1.94; 95%CI: 1.21-3.11), TBF (OR=1.37; 95%CI: 1.21-1.54) were predictors of nutritional status (p<0.001). FBG (OR=42.39; 95%CI: 2.31-77.2) and UA (OR=1.03; 95%CI: 1.01-1.05) were predictors of IR (p<0.001).

CONCLUSIONS

IGF-1 SDS and TBF were predictors of nutritional status. Further studies are required to clarify the role of IGF-1 in pathophysiology of obesity and its comorbidities.

Acromegaly, inflammation and cardiovascular disease: a review

Acromegaly is characterized by Growth Hormone (GH) and Insulin-like Growth Factor 1 (IGF-1) excess. Uncontrolled acromegaly is associated with a strongly increased risk of cardiovascular disease (CVD), and numerous cardiovascular risk factors remain present after remission. GH and IGF-1 have numerous effects on the immune and cardiovascular system. Since endothelial damage and systemic inflammation are strongly linked to the development of CVD, and have been suggested to be present in both controlled as uncontrolled acromegaly, they may explain the presence of both micro- and macrovascular dysfunction in these patients. In addition, these changes seem to be only partially reversible after remission, as illustrated by the often reported presence of endothelial dysfunction and microvascular damage in controlled acromegaly. Previous studies suggest that insulin resistance, oxidative stress, and endothelial dysfunction are involved in the development of CVD in acromegaly. Not surprisingly, these processes are associated with systemic inflammation and respond to GH/IGF-1 normalizing treatment.

Cancer and Cardiovascular Risk in Women With Hypertensive Disorders of Pregnancy Carrying a Common IGF1R Variant

OBJECTIVE

To evaluate the impact of insulin-like growth factor 1 receptor variant rs2016347 on the risk for breast and nonbreast cancers and cardiovascular disease in women with a history of hypertensive disorders of pregnancy (HDP).

PATIENTS AND METHODS

This retrospective cohort study included all parous women in the UK Biobank with prior rs2016347 genotyping (N=204,155), with enrollment taking place from March 2006 to July 2010. History of HDP was self-reported, and outcomes included breast and all nonbreast cancers, hospital diagnoses of hypertension and cardiovascular disease, and direct blood pressure measurements.

RESULTS

Women with previous HDP had a higher risk for future hypertension and cardiovascular diagnoses, increased blood pressures, and lower risk for breast cancer compared with women without HDP, consistent with prior studies. Hazard ratios for all nonbreast cancers were unchanged. However, when taking genotype into account, HDP-positive women carrying at least 1 thymine (T) allele of rs2016347 had a lower risk for nonbreast cancer (hazard ratio, 0.59; 95% CI, 0.37 to 0.92; P=.02) and lower systolic blood pressure (-2.08±0.98 mm Hg; P=.03) compared with women with the guanine/guanine (GG) genotype with positive evidence of interaction (HDP:T allele) for both outcomes; P=.04 and P=.03, respectively.

CONCLUSION

Women who experience HDP and carry a T allele of rs2016347 have 41% lower risk for developing nonbreast cancer and a lower systolic blood pressure of 2.08 mm Hg when compared with those with the GG genotype, suggesting a possible role of the insulin-like growth factor 1 axis for both cardiovascular and cancer risk in women with HDP.

Immune dyscrasia in adult growth hormone deficiency: Evaluation of hemolytic complement activity (CH50) and IgG subclasses

CH50 is a screening assay for the activation of the classical complement pathway, the immunoglobulins-mediated one, activated in several inflammatory diseases. Adult growth hormone deficiency (aGHD) is recognized as a chronic inflammatory condition, although poorly evaluated under the profile of inflammatory biomarkers. The aim of this case-control observational study is to analyze CH50 and immunoglobulins G (IgG) subclasses production in aGHD, comparing this condition to healthy controls. 38 subjects were included and divided as follows: aGHD (n = 18, 6 females and 12 males); healthy controls (n = 20, 10 females and 10 males). GHD was diagnosed with dynamic test using Growth Hormone-Releasing Hormone (GHRH 50 μg i.v. + arginine 0,5 g/Kg), with a peak GH response < 9 μg/L when BMI was <30 kg/m² or < 4 μg/L when BMI was >30 kg/m². The two groups were evaluated for hormonal and metabolic parameters, CH50 and IgG subtypes. IgG1 and IgG2 were significantly higher in controls than in aGHD, while IgG3 and IgG4 showed a trend to higher levels in controls, although not significant. Furthermore, CH50 levels were significantly higher in aGHD. These data substantiate the hypothesis of a dyscrasia in IgG subclasses production in aGHD. As IgG levels decrease, CH50 levels do not.

Circulating IGF-1 Independently Predicts Blood Pressure in Children With Higher Calcium-Phosphorus Product Levels

OBJECTIVE

To study the association between insulin-like growth factor 1 (IGF-1) and blood pressure in children, in particular, the potential interaction with the serum calcium-phosphorus product (Ca*P).

METHODS

A longitudinal study included 521 children (age 8.8 ± 0.1) from northeastern Spain, of whom 158 were followed-up after 5 years. IGF-1, insulin-like growth factor-binding protein 3 (IGFBP-3), and serum calcium and phosphorus were measured at baseline. Anthropometric (body-mass index [BMI] and waist) and cardiometabolic variables (systolic [SBP] and diastolic blood pressure), pulse pressure, insulin, homeostatic model assessment of insulin resistance [HOMA-IR], high-density lipoprotein [HDL]-cholesterol, and triglycerides) were assessed at baseline and at the end of follow-up. Statistical analysis included Pearson correlations followed by multivariable linear regression analyses.

RESULTS

Baseline IGF-1 and IGF-1/IGFBP-3 molar ratio positively correlated with baseline and follow-up BMI, waist, SBP, pulse pressure, insulin, HOMA-IR and triglycerides (r 0.138-0.603; all P < 0.05). The associations with SBP were stronger with increasing Ca*P (r 0.261-0.625 for IGF-1; and r 0.174-0.583 for IGF-1/IGFBP-3). After adjusting for confounding variables, baseline IGF-1 and IGF-1/IGFBP-3 remained independently associated with both baseline and follow-up SBP in children in the highest Ca*P tertile (β = 0.245-0.381; P < 0.01; model R2 = 0.246-0.566).

CONCLUSIONS

Our results suggest that IGF-1 in childhood is an independent predictor of SBP in apparently healthy children, especially in those with high Ca*P levels.

Hypertension and Acromegaly

Hypertension is one of the most frequent complications in acromegaly, with a median frequency of 33.6% (range, 11%-54.7%). Although the pathogenesis has not been fully elucidated, it probably results from concomitant factors leading to expansion of extracellular fluid volume, increase of peripheral vascular resistance, and development of sleep apnea syndrome. Because the effect of normalization of growth hormone and insulinlike growth factor 1 excess on blood pressure levels is unclear, an early diagnosis of hypertension and prompt antihypertensive treatment are eagerly recommended, regardless of the specific treatment of the acromegalic disease and the level of biochemical control attained.

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.

Effects of somatostatin analog treatment on cardiovascular parameters in patients with acromegaly: A systematic review

Background:

There is a belief that in patients with acromegaly, first-generation somatostatin analogs (SSAs) might improve cardiovascular (CV) structure and function. However, most published clinical trials involved only a few patients and their results are rather variable. We aimed to conduct a systematic review on available studies on the impact of these drugs on CV parameters.

Materials and Methods:

A literature search was conducted in MEDLINE (OVID), EMBase, Cochrane, and ISI Web of Science for citations published until April 30 2018 to identify studies on our objective that considered changes in CV parameters. For this search, we established a Boolean search strategy using keywords related to “acromegaly,” “Somatostatin analog,” and “cardiovascular diseases and parameters.” All study types except for case reports or conference abstracts were included. Twenty-four studies (n = 558) fulfilled the inclusion criteria and were selected for final analysis.

Results:

In 12 studies (n = 350), decrease in heart rate (HR) and in 4 studies (n = 128), decrease in blood pressure (BP) was significant. In 15 studies (n = 320), left ventricular mass index (LVMi) changes were significant. In 9 studies (n = 202), the early diastole to peak velocity flow in late diastole (E/A ratio) was evaluated, and in 5 of them (n = 141), the improvement was significant. Eighteen studies (n = 366) examined changes in left ventricular ejection fraction (LVEF), 5 of which (n = 171) reported that these changes were significant. Decrease of left ventricular end-diastolic diameter was reported in only 2 studies (n = 27).

Conclusion:

We found that first-generation SSAs have a beneficial effect on cardiac parameters such as HR and LVMi. For other parameters such as LVEF, BP, LV diameter, and E/A ratio, we were not able to draw a firm conclusion.

The Prospective Association Between Plasma Concentrations of Cellular Growth Factors and Risk of Heart Failure Mortality in Japanese Population

Background

Limited evidence is available on the association of insulin-like growth factors (IGFs) and risk of heart failure in population-based samples. We investigated whether serum IGFs concentrations can predict mortality from heart failure.

Methods

We conducted a nested case-control study of 39,242 subjects aged 40–79 years who participated in the JACC study, a large Japanese prospective cohort study; participants provided serum samples and were followed up for 9 years. In heart failure cases and age-, sex-, community-, and year of blood withdrawal-matched controls, we measured serum concentrations of IGF-I, IGF-II, and IGF binding protein 3 (IGFBP3) and transforming growth factor (TGF-β1).

Results

During the follow-up, there were 88 heart failure deaths (44 men and 44 women). Each increment of 1 standard deviation [SD] of IGF-II (120.0 ng/mL in women and 143.7 ng/mL in men) was associated with a 47% reduced risk of mortality from heart failure; multivariable odds ratio was 0.53 (95% confidence interval [CI], 0.30–0.94, P-trend = 0.03). The multivariable odds ratio in the highest quartile of IGFBP3 serum concentrations (≥3.29 µg/mL in women and ≥3.31 µg/mL in men) compared with the lowest (<2.11 µg/mL in women and <2.56 µg/mL in men) was 0.24 (95% CI, 0.05–1.11; P-trend = 0.12). No association was found between serum concentrations of IGF-I or TGF-β1 and risk of heart failure.

Conclusions

Higher serum concentrations of IGF-II were associated with lower mortality from heart failure, which might suggest a possible role of IGF-II in the occurrence or prognosis of heart failure.

Changes in metabolic parameters and cardiovascular risk factors after therapeutic control of acromegaly vary with the treatment modality. Data from the Bicêtre cohort, and review of the literature

CONTEXT

Untreated acromegaly is associated with increased morbidity and mortality due to malignant, cardiovascular, and cerebrovascular disorders. Effective treatment of acromegaly reduces excess mortality, but its impact on cardiovascular risk factors and metabolic parameters are poorly documented.

AIM

We analyzed changes in cardiovascular risk factors and metabolic parameters in patients receiving various treatment modalities.

PATIENTS AND METHODS

We retrospectively studied 96 patients with acromegaly, both at diagnosis and after IGF-I normalization following surgery alone (n = 51) or medical therapy with first generation somatostatin analogues (SSA, n = 23), or pegvisomant (n = 22). Duration of follow-up was 77 (42-161) months, 75 (42-112) months, and 62 (31-93) months, in patients treated with surgery alone, SSA, and pegvisomant, respectively. In all the cases except four, patients treated medically had underwent previous unsuccessful surgery.

RESULTS

IGF-I normalization was associated with increased body weight, decreased systolic blood pressure (SBP) in hypertensive patients, decreased fasting plasma glucose (FPG) and HOMA-IR and HOMA-B levels, increased HDL cholesterol (HDLc); whereas, LDL cholesterol (LDLc) was not significantly different. Plasma PCSK9 levels were unchanged in patients with available values. Cardiovascular and metabolic changes varied with the treatment modality: surgery, but not pegvisomant, had a beneficial effect on SBP; FPG decreased after surgery but increased after SSA; the decline in HOMA-IR was only significant after surgery; pegvisomant significantly increased LDLc and total cholesterol; whereas SA increased HDLc and had no effect on LDLc levels.

CONCLUSION

Treatments used to normalize IGF-I levels in patients with acromegaly could have differential effects on cardiovascular risk factors and metabolic parameters.

Bringing Cardiovascular Comorbidities in Acromegaly to an Update. How Should We Diagnose and Manage Them?

Patients with acromegaly frequently develop cardiovascular comorbidities, which significantly affect their morbidity and contribute to an increased all-cause mortality. In this regard, the most frequent complications that these patients may encounter include hypertension, cardiomyopathy, heart valve disease, arrhythmias, atherosclerosis, and coronary artery disease. The specific underlying mechanisms involved in the pathophysiology of these comorbidities are not always fully understood, but uncontrolled GH/IGF-I excess, age, prolonged disease duration, and coexistence of other cardio-vascular risk factors have been identified as significant influencing predisposing factors. It is important that clinicians bear in mind the potential development of cardiovascular comorbidities in acromegalic patients, in order to promptly tackle them, and avoid the progression of cardiac abnormalities. In many cases, this approach may be performed using straightforward screening tools, which will guide us for further diagnosis and management of cardiovascular complications. This article focuses on those cardiovascular comorbidities that are most frequently encountered in acromegalic patients, describes their pathophysiology, and suggests some recommendations for an early and optimal diagnosis, management and treatment.

Plasmatic free light chains as inflammatory marker in insulin resistance: comparison of metabolic syndrome with adult growth hormone deficiency

Biological functions of immunoglobulin-free light chains (FLCs), other than in chronic inflammatory diseases, are still poorly defined; the field of insulin resistance (IR) has not been investigated, despite the strict relationships with oxidative stress (OS) and inflammation. Therefore, we evaluated FLCs levels and their relationships with metabolic parameters in adult growth hormone deficiency (GHD) and metabolic syndrome (MetS), both characterized by IR. One hundred subjects were enrolled: group A, patients with GHD [n =31, 24-69 years, mean ± SEM body mass index (BMI) 26.8 ± 1.5 kg/m² ]; group B, patients with MetS (n = 29, 21-70 years, BMI 31.9 ± 1.3); group C, controls (N = 40, 21-62 years, BMI 21.6 ± 1.1). Groups were matched by age range and, for patients, by BMI. Morning blood sample was collected for metabolic parameters and FLCs, assessed by turbidimetric assay. GHD patients show levels of FLCs significantly higher than MetS and controls (mean ± SEM κ 37.21 ± 6.97, 15.27 ± 0.86, 12.34 ± 0.85 mg/l; λ 19.44 ± 2.61, 11.78 ± 0.72 and 11.67 ± 0.77 mg/l; κ/λ ratio 1.77 ± 0.13, 1.38 ± 0.09; and 1.10 ± 0.06, respectively); only κ were higher in MetS versus controls. Therefore, the ratio showed progressive declining values in GHD versus MetS versus controls. Our data show increased FLCs levels in GHD and MetS, with the highest values in the former. Both conditions show OS, but with different molecular patterns. FLCs may contribute to chronic inflammation, leading to OS, and cardiovascular complications of GHD. Prognostic and therapeutic implications require further investigation. © 2018 BioFactors, 44(5):480-484, 2018.

Bioavailable IGF-1 is beneficially associated with biomarkers of endothelial function in young healthy adults: The African-PREDICT study

INTRODUCTION

Low circulating levels of insulin-like growth factor-1 (IGF-1) are associated with endothelial dysfunction, subsequently leading to the development of cardiovascular disease.

OBJECTIVE

To better understand the early phases of vascular deterioration in a young, healthy population, we investigated, cross-sectionally, whether biomarkers of endothelial function (intercellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1) and von Willebrand factor antigen (vWF_ag)) are associated with IGF-1 in a healthy study population forming part of the larger African Prospective study on the Early Detection and Identification of Cardiovascular diseases and Hypertension (African-PREDICT).

METHOD

We included 825 black and white men and women (aged 20-30 years) and determined IGF-1, IGF binding protein-3 (IGFBP-3), ICAM-1, VCAM-1 and vWF_ag from blood samples. We also measured 24-h blood pressure and health behaviours namely waist circumference, accelerometery, cotinine and gamma glutamyl transferase. We used the IGF-1/IGFBP-3 M ratio as an estimate of bioavailable IGF-1.

RESULTS

In multivariable-adjusted regression analyses performed in the total group, VCAM-1 associated positively with IGFBP-3 (β = 0.21; p < .001) and negatively with IGF-1/IGFBP-3 (β = -0.18; p < .001). ICAM-1 showed a borderline negative association with IGF-1 (β = -0.09; p = .054) and IGF-1/IGFBP-3 (β = -0.08; p = .057). vWF_ag was not associated with IGF-1, IGFBP-3 or bioavailable IGF-1.

CONCLUSION

VCAM-1 is beneficially associated with IGF-1 in a young healthy cohort, independent of sex, ethnicity, blood pressure and health behaviours - thereby confirming the potential importance of bioavailable IGF-1 in early vascular endothelial protection.

Insulin-Like Growth Factor-1 and Receptor Contribute Genetic Susceptibility to Hypertension in a Han Chinese Population

BACKGROUND

Insulin-like growth factor 1 (IGF-1) and IGF-1 receptor (IGF-1R) have been suggested to mediate the pathophysiological response to elevated blood pressure. This study aims to evaluate the association of IGF-1 and IGF-1R with hypertension.

METHODS

Overall, 2,012 hypertensive cases and 2,210 controls were included in a case-control study, and 10 tagging single nucleotide polymorphisms (tagSNPs) were selected. The association of these SNPs with hypertension was further evaluated in a follow-up analysis and in an adolescent population.

RESULTS

A case-control study indicated that rs1815009 and rs2654981 in IGF-1R were significantly associated with hypertension, with odds ratios of 0.89 (P = 0.009) and 1.19 (P = 0.034), respectively, after adjusting for covariates. Stratification analyses revealed significant associations with hypertension (P < 0.05) for rs35767 in normal weight and obese populations; for rs2229765 in individuals <55 years of age and in overweight and nondrinking populations; and for rs2002880 in overweight and drinking populations. In a follow-up study, rs13379905 in IGF-1R was associated with hypertension incidence (hazard ratio, HR = 1.24, P = 0.042). This association was more significant in individuals with a hypertensive family history (HR = 2.10, P = 0.001). The association of rs13379905 with prehypertension and hypertension was further replicated in adolescent males (P = 0.005). Significant associations with hypertension incidence (P < 0.05) were observed for rs6219 in individuals <55 years of age and among those with obesity and a hypertensive family history as well as rs2002880 in obese individuals.

CONCLUSIONS

Our findings suggest that IGF-1R may contribute to the genetic susceptibility to hypertension, with BMI, age, and family history of hypertension all potentially modulating the genetic effects of IGF-1 on hypertension.

Inflammation and oxidative stress markers in diabetes and hypertension

Background

Inflammation and oxidative stress are important factors associated with chronic disease such as essential hypertension (HTN) and type 2 diabetes mellitus (T2DM). However, the association of inflammation and oxidative stress in HTN with T2DM as a comorbidity is inconclusive due to the multifactorial nature of these cardiometabolic diseases.

Methodology

The influence of pathophysiological factors include genetics, age of patient, and disease progression change throughout the lifespan and require further investigation. The study population included 256 participants attending a rural health screening program who were tested for markers of inflammation, oxidative stress, and coagulation/fibrinolysis. Demographic and clinical variables included, age, gender, systolic and diastolic blood pressures, blood glucose, hemoglobin A1c, estimated glomerular filtration rate, and cholesterol profile. Data were tested for normality, and nonparametric statistics were applied to analyze the sample with significance set at p<0.05.

Results

Of the inflammatory markers, interleukin-1β (IL-1β) and IL-10 were significantly different between the control and hypertensive group (p<0.03) and between the HTN+T2DM compared to the HTN group (p<0.05). Significant results for oxidative stress were observed for urinary 8-iso-PGF₂α and insulin-like growth factor 1 (IGF-1) between the control and the HTN+T2DM group (p<0.01). Glutathione (GSH) was also significant between the HTN and HTN+T2DM group (p<0.05). Investigation of the progression of HTN also found significant changes in the inflammatory markers IGF-1, monocyte chemoattractant protein 1 (MCP-1), and (MCP-1/IGF-1)*IL-6 (p<0.05).

Conclusion

This study demonstrated that 8-iso-PGF₂α and erythrocyte GSH may be clinically useful for assessing HTN and HTN with T2DM as a comorbidity, while significant changes in the inflammatory profile were also observed with HTN progression.

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.

Cardiovascular comorbidities in acromegaly: an update on their diagnosis and management

Comorbidities related to the cardiovascular system are one of the most prevalent in patients with acromegaly, and contribute to an increased risk of morbidity and all-cause mortality. Specifically, hypertension, cardiomyopathy, heart valve disease, arrhythmias, atherosclerosis, coronary artery disease, and cardiac dysfunction may be frequent findings. Although the underlying physiopathology for each comorbidity may not be fully elucidated, uncontrolled growth hormone/insulin-like growth factor 1 excess, age, prolonged disease duration, and coexistence of other cardio-vascular risk factors are significant influencing variables. A simple diagnostic approach to screen for the presence of these comorbidities may allow prompt treatment and arrest the progression of cardiac abnormalities. In this article, we revise the most prevalent cardiovascular comorbidities and their pathophysiology in acromegalic patients, and we address some recommendations for their prompt diagnosis, management and treatment. Strengths and pitfalls of different diagnostic techniques that are currently being used and how different treatments can affect these complications will be further discussed.

IGF-1 and NT-proBNP in a black and white population: The SABPA study

BACKGROUND

Black populations exhibit lower concentrations of the cardioprotective peptide, insulin-like growth factor-1 (IGF-1), and are more prone to develop hypertensive heart disease than whites. We therefore determined whether lower IGF-1 in black individuals relates to a marker of cardiac overload and systolic dysfunction, namely N-terminal prohormone B-type natriuretic peptide (NT-proBNP).

MATERIALS AND METHODS

We included 160 black and 195 white nondiabetic South African men and women (aged 44·4 ± 9·81 years) and measured ambulatory blood pressure, NT-proBNP, IGF-1 and insulin-like growth factor-binding protein-3 (IGFBP-3).

RESULTS

Although the black group presented elevated ambulatory blood pressure accompanied by lower IGF-1 compared to the white group (all P < 0·001), we found similar NT-proBNP concentrations (P = 0·72). Furthermore, in blacks we found a link between NT-proBNP and systolic blood pressure (SBP) (R(2) = 0·37; β = 0·28; P < 0·001), but not with IGF-1. In the white group, NT-proBNP was inversely associated with IGF-1 (R(2) = 0·39; β = -0·22; P < 0·001) after adjusting for covariates and potential confounders. As IGF-1 is attenuated in diabetes, we added the initially excluded patients with diabetes (n = 38), and the aforementioned associations remained robust.

CONCLUSION

Contrary to the white group, we found no association between NT-proBNP and IGF-1 in black adults. Our findings suggest that SBP and other factors may play a greater contributory role in cardiac pathology in blacks.

Attenuated IGF-1 predicts all-cause and cardiovascular mortality in a Black population: A five-year prospective study

BACKGROUND

Inconsistent findings are reported on whether insulin-like growth factor-1 (IGF-1) is protective or harmful in predicting hypertension, carotid wall thickness and mortality. We determined the five-year prognostic value of IGF-1 for these outcomes in a large Black population prone to hypertension and cardiovascular disease.

DESIGN

A longitudinal study as part of the PURE (Prospective Urban and Rural Epidemiology) study, North West Province, South Africa.

METHODS

We measured IGF-1 and IGF binding protein-3 (IGFBP-3) in 1038 HIV-uninfected participants (age range 32-94 years) and assessed blood pressure, carotid intima-media thickness and mortality.

RESULTS

Over five years 116 deaths occurred. Baseline IGF-1 was similar in survivors and non-survivors (p = 0.50), but tended to be higher in survivors upon adjustment for IGFBP-3 and covariates (p = 0.061). Normotensives and hypertensives (p = 0.072), and those with carotid intima-media thickness < 0.9 mm and ≥ 0.9 mm also displayed similar baseline IGF-1 (p = 0.55). Multivariable-adjusted Cox-regression indicated high IGF-1 predicting lower risk for all-cause mortality (hazard ratio 0.45; 0.23-0.88) and cardiovascular mortality (hazard ratio 0.26; 0.08-0.83) when also adjusting for IGFBP-3. When including normo- and hypertensives at baseline, high IGF-1 was related to normotension at follow-up (hazard ratio 0.68; 0.49-0.95). We found no association with carotid intima-media thickness (hazard ratio 0.59; 0.31-1.14).

CONCLUSION

In a Black South African population with low socio-economic status and harmful health behaviours, we found a protective independent association between IGF-1 and hypertension, cardiovascular and all-cause mortality, with no association with carotid wall thickness.

Arterial properties in acromegaly: relation to disease activity and associated cardiovascular risk factors

PURPOSE

Acromegaly is associated with increased cardiovascular morbidity and mortality when inadequately treated, which may be secondary to associated comorbidities or to direct IGF-1 effects on the cardiovascular system. By using a control group carefully matched for traditional cardiovascular risk factors, we aimed to assess the direct contribution of disease activity and IGF-1 levels to arterial damage as assessed by measurements of arterial stiffness and endothelial function.

METHODS

Twenty-nine subjects with acromegaly (11 males, 52 ± 14 year; 15 active acromegaly) and 24 matched controls underwent evaluation of large and small artery compliance using applanation tonometry, pulse wave velocity (PWV), augmentation index (Alx), carotid ultrasonography intima-media thickness, (IMT) and flow-mediated dilatation (FMD).

RESULTS

IGF-1 expressed as times the upper limit of the normal range (x ULN) was 2.2 ± 1.1 in patients with active disease versus 0.7 ± 0.2 in patients in remission. Irrespective of disease activity, FMD was lower in patients with acromegaly than in control subjects, (3.4 ± 2.7 % in active acromegaly, 4.4 ± 3.3 % in controlled acromegaly and 7.5 ± 3.8 % in controls; p = 0.004). There were no significant differences in PWV, Alx, and IMT between groups. A positive correlation was found between IGF-1× ULN and IMT (r = 0.4; P = 0.02). Asymmetric dimethylarginine (ADMA), a novel cardiovascular risk factor, was positively correlated to arterial stiffness (r = 0.46; p = 0.017) and negatively with small vessel compliance (r = -0.44, p = 0.02).

CONCLUSIONS

Patients with acromegaly have significantly impaired endothelial function as assessed by FMD, but other tested vascular parameters were similar to a control group that was adequately matched for cardiovascular risk factors.

Blood pressure in relation to contamination by polychlorobiphenyls and organochlorine pesticides: Results from a population-based study in the Canary Islands (Spain)

BACKGROUND

Epidemiological studies have reported significant associations between exposure to persistent organic pollutants (POPs) and increased blood pressure (BP). Environmental exposure to POPs, mainly organochlorine pesticides, is of concern to the population of the Canary Islands, who display a high prevalence of diseases associated with hypertension such as metabolic syndrome, obesity and cardiovascular disease.

OBJECTIVE

We performed this population-based study in a representative population sample from this archipelago to evaluate whether serum levels of selected POPs could be considered as hypertension risk factors.

METHODS

BP and several other well-known factors related to hypertension (gender, age, smoking, BMI, and total lipids) were recorded in 428 adult participants from the Canary Islands Nutritional Survey. In total, 28 POPs (including 18 polychlorinated biphenyl (PCB) congeners and 10 organochlorine pesticides and metabolites) were measured in the serum of the population enrolled in this survey.

RESULTS

In total, 167 subjects (39%) demonstrated hypertension or used antihypertensive medication. We observed a positive association between systolic and diastolic BP and p,p'-DDE (r=0.222; p<0.001, and r=0.123; p=0.015, respectively). Conversely, an inverse association between systolic BP and aldrin was observed (r=-0.120; p=0.017). After adjusting for known confounders, only aldrin was inversely related to hypertension risk [OR: 0.28 (95% CI: 0.09-0.92); p=0.037]. After excluding subjects undergoing anti-hypertensive treatment, we also observed that aldrin was inversely associated with systolic BP in multivariate analyses, especially in men [OR: 0.126 (95% CI: 0.021-0.763); p=0.024].

CONCLUSION

Although it has been postulated that background POPs exposure may play a relevant role on elevated BP, we did not observed increased hypertension risk in relation to serum POPs in this cross-sectional study. Conversely, the cyclodiene pesticide aldrin was negatively associated with hypertension, suggesting that cyclodienes could exert an effect opposite of the DDT metabolites. These findings agree with other previous works indicating that POPs may induce divergent actions on BP and suggest that the direction of the association between BP and POPs could be dependent on the chemical structure as well as concentration of the evaluated POP. Prospective studies are needed to clarify the effect exerted by POPs on BP.

Exogenous estrogen as mediator of racial differences in bioactive insulin-like growth factor-I levels among postmenopausal women

BACKGROUND

The role of exogenous estrogen use in racial differences in insulin-like growth factor-I (IGF-I) levels which affect cancer risk is unclear. We investigated whether the relationship between race and circulating bioactive IGF-I proteins was mediated by exogenous estrogen and the extent to which exogenous estrogen influenced the race-IGF-I relationship in postmenopausal women.

METHODS

This cross-sectional study included 636 white and 133 African American postmenopausal women enrolled in an ancillary study of the Women's Health Initiative Observational Study. To assess exogenous estrogen use (nonusers [n = 262] vs users [n = 507]) as a mediator of the race-IGF-I relationship, we used the Baron-Kenny method and an estimation of the proportional change in the odd ratios for IGF-I levels on race plus a bootstrapping test for the significance of the mediation effect.

RESULTS

Compared with white women, African American women were more likely to have high IGF-I levels and less likely to use exogenous estrogen. After accounting for race, estrogen nonusers had higher IGF-I levels than estrogen users did. Among oral contraceptive ever users, exogenous estrogen had a strong mediation effect (67%; p = .018) in the race-IGF-I relationship. In the women with a history of hypertension, exogenous estrogen explained racial differences in IGF-I levels to a modest degree (23%; p = .029).

CONCLUSIONS

Exogenous estrogen use has a potentially important role in disparities in IGF-I bioactivity between postmenopausal African American and white women. A history of oral contraceptive use and hypertension may be part of the interconnected hormonal pathways related to racial differences in IGF-I levels.

Novel mechanism of blood pressure regulation by forkhead box class O1-mediated transcriptional control of hepatic angiotensinogen

The renin-angiotensin system is a major determinant of blood pressure regulation. It consists of a cascade of enzymatic reactions involving 3 components: angiotensinogen, renin, and angiotensin-converting enzyme, which generate angiotensin II as a biologically active product. Angiotensinogen is largely produced in the liver, acting as a major determinant of the circulating renin-angiotensin system, which exerts acute hemodynamic effects on blood pressure regulation. How the expression of angiotensinogen is regulated is not completely understood. Here, we hypothesize that angiotensinogen is regulated by forkhead transcription factor forkhead box class O1 (Foxo1), an insulin-suppressed transcription factor, and thereby controls blood pressure in mice. We generated liver-specific Foxo1 knockout mice, which exhibited a reduction in plasma angiotensinogen and angiotensin II levels and a significant decrease in blood pressure. Using hepatocyte cultures, we demonstrated that overexpression of Foxo1 increased angiotensinogen expression, whereas hepatocytes lacking Foxo1 demonstrated a reduction of angiotensinogen gene expression and partially impaired insulin inhibition on angiotensinogen gene expression. Furthermore, mouse angiotensinogen prompter analysis demonstrated that the angiotensinogen promoter region contains a functional Foxo1-binding site, which is responsible for both Foxo1 stimulation and insulin suppression on the promoter activity. Together, these data demonstrate that Foxo1 regulates hepatic angiotensinogen gene expression and controls plasma angiotensinogen and angiotensin II levels, modulating blood pressure control in mice.