Relationship between de novo lipogenesis and serum sex hormone binding globulin in humans

Objective Obesity and liver fat are associated with decreased levels of serum sex hormone binding globulin (SHBG). Laboratory studies suggest that hepatic de novo lipogenesis (DNL) is involved in the downregulation of SHBG synthesis. The aim of the present study was to address the role of DNL on serum SHBG in humans. Design A cross-sectional study examining the association between DNL, measured by stable isotopes, and serum SHBG, stratified by sex. Participants Healthy men (n = 34) and women (n = 21) were combined from two cross-sectional studies. Forty-two per cent of participants had hepatic steatosis, and the majority were overweight (62%) or obese (27%). Results DNL was inversely associated with SHBG in women (beta: -0.015, 95% CI: -0.030; 0.000), but not in men (beta: 0.007, 95% CI: -0.005; 0.019) (p for interaction = .068). Adjustment for study population, age and body mass index did not materially change these results, although statistical significance was lost after adjustment for serum insulin. Conclusions An inverse association between DNL and SHBG may explain the decreased SHBG levels that are observed in obesity, at least in women.Peer reviewe

Association between de novo lipogenesis susceptibility genes and coronary artery disease

BACKGROUND AND AIMS: Coronary artery disease (CAD) is the principal cause of death in individuals with non-alcoholic fatty liver disease (NAFLD). The aim of this study was to use genetic epidemiology to study the association between de novo lipogenesis (DNL), one of the major pathways leading to NAFLD, and CAD risk. METHODS AND RESULTS: DNL susceptibility genes were used as instruments and selected using three approaches: 1) genes that are associated with both high serum triglycerides and low sex hormone-binding globulin, both downstream consequences of DNL (unbiased approach), 2) genes that have a known role in DNL (biased approach), and 3) genes that have been associated with serum fatty acids, used as a proxy of DNL. Gene-CAD effect estimates were retrieved from the meta-analysis of CARDIoGRAM and the UK Biobank (∼76014 cases and ∼264785 controls). Effect estimates were clustered using a fixed-effects meta-analysis. Twenty-two DNL susceptibility genes were identified by the unbiased approach, nine genes by the biased approach and seven genes were associated with plasma fatty acids. Clustering of genes selected in the unbiased and biased approach showed a statistically significant association with CAD (OR:1.016, 95%CI:1.012; 1.020 and OR:1.013, 95%CI:1.007; 1.020, respectively), while clustering of fatty acid genes did not (OR:1.004, 95%CI:0.996-1.011). Subsequent exclusion of potential influential outliers did reveal a statistically significant association (OR:1.009, 95%CI:1.000; 1.018). CONCLUSIONS: DNL susceptibility genes are associated with an increased risk of CAD. These findings suggest that DNL may be involved in the pathogenesis of CAD and favor further development of strategies that target NAFLD through DNL

Association of common gene variants in glucokinase regulatory protein with cardiorenal disease: A systematic review and meta-analysis

<div><p>Background</p><p>Small-molecules that disrupt the binding between glucokinase and glucokinase regulatory protein (GKRP) in the liver represent a potential new class of glucose-lowering drugs. It will, however, take years before their effects on clinically relevant cardiovascular endpoints are known. The purpose of this study was to estimate the effects of these drugs on cardiorenal outcomes by studying variants in the GKRP gene (<i>GCKR</i>) that mimic glucokinase-GKRP disruptors.</p><p>Methods</p><p>The MEDLINE and EMBASE databases were searched for studies reporting on the association between <i>GCKR</i> variants (rs1260326, rs780094, and rs780093) and coronary artery disease (CAD), estimated glomerular filtration rate (eGFR), and chronic kidney disease (CKD).</p><p>Results</p><p>In total 5 CAD studies (n = 274,625 individuals), 7 eGFR studies (n = 195,195 individuals), and 4 CKD studies (n = 31,642 cases and n = 408,432 controls) were included. Meta-analysis revealed a significant association between <i>GCKR</i> variants and CAD (OR:1.02 per risk allele, 95%CI:1.00–1.04, p = 0.01). Sensitivity analyses showed that replacement of one large, influential CAD study by two other, partly overlapping studies resulted in similar point estimates, albeit less precise (OR:1.02; 95%CI:0.98–1.06 and OR: 1.02; 95%CI: 0.99–1.04). <i>GCKR</i> was associated with an improved eGFR (+0.49 ml/min, 95%CI:0.10–0.89, p = 0.01) and a trend towards protection from CKD (OR:0.98, 95%CI:0.95–1.01, p = 0.13).</p><p>Conclusion</p><p>This study suggests that increased glucokinase-GKRP disruption has beneficial effects on eGFR, but these may be offset by a disadvantageous effect on coronary artery disease risk. Further studies are warranted to elucidate the mechanistic link between hepatic glucose metabolism and eGFR.</p></div

Relationship between NAFLD and coronary artery disease: A Mendelian randomization study

BACKGROUND & AIMS: There is an ongoing debate on whether non-alcoholic fatty liver disease (NAFLD) is an active contributor or an innocent bystander in the pathogenesis of coronary artery disease (CAD). The aim of the present study was to assess the causal relationship between NAFLD and CAD. APPROACH & RESULTS: We performed two-sample Mendelian randomization (MR) analyses using summary-level data to assess the association between genetically predicted NAFLD (i.e. chronically-elevated serum alanine aminotransferase levels [cALT], imaging-based and biopsy-confirmed NAFLD) and risk of CAD. Analyses were repeated after exclusion of NAFLD susceptibility genes that are associated with impaired VLDL secretion. Inverse-variance weighted (IVW) MR analyses showed a statistically significant association between genetically predicted cALT and risk of CAD (odds ratio [OR]:1.116, 95% confidence interval [CI]:1.039,1.199), but not for the other NAFLD-related traits (OR:1.046, 95%CI:0.764,1.433 and OR:1.014, 95%CI:0.968,1.062 for imaging-based and biopsy-confirmed NAFLD, respectively). MR Egger regression revealed a statistically significant intercept, indicative of directional pleiotropy, for all traits. Repeat analyses after exclusion of genes associated with impaired VLDL secretion, showed consistent associations between genetically predicted NAFLD and CAD for all traits, i.e. cALT (OR:1.203, 95%CI:1.113,1.300), imaging-based (OR:2.149, 95%CI:1.276,3.620) and biopsy-confirmed NAFLD (OR:1.113, 95%CI:1.041,1.189), which persisted when more stringent biopsy-confirmed NAFLD criteria were used (OR:1.154, 95%CI:1.043,1.278) or when more stringent MR methods were applied. MR Egger regression did not show a statistically significant intercept. CONCLUSION: The two-sample MR analyses showed a robust association between genetically predicted NAFLD and CAD after exclusion of genetic variants that are implicated in impaired VLDL secretion

The relationships of sex hormone-binding globulin, total testosterone, androstenedione and free testosterone with metabolic and reproductive features of polycystic ovary syndrome

OBJECTIVE: A recent Mendelian randomization study has suggested a causal role for sex hormone‐binding globulin (SHBG), total testosterone and free testosterone in the pathogenesis of polycystic ovary syndrome (PCOS). The aim of this study was to assess the relationships of SHBG, androstenedione, total and free testosterone with the individual metabolic and reproductive features of PCOS. DESIGN: Cross‐sectional data in PCOS patients (n=96) prospectively collected in a secondary/tertiary clinic for menstrual cycle disorders. METHODS: Multivariable regression analyses were conducted to study the associations between SHBG, androstenedione, total and free testosterone with metabolic (BMI, waist circumference, systolic and diastolic blood pressure, total cholesterol, LDL cholesterol, HDL cholesterol, triglycerides and homeostatic model assessment for insulin resistance [HOMA2‐IR]) and reproductive features (menstrual cycle length, antral follicle count, anti‐Müllerian hormone, luteinizing hormone, follicle‐stimulating hormone and Ferriman‐Gallwey score) of PCOS. RESULTS: Serum SHBG and free testosterone, but not total testosterone or androstenedione, were significantly associated with BMI, waist circumference, serum triglycerides, HDL cholesterol, LDL cholesterol and HOMA2‐IR. The strength of the associations with serum lipids was reduced after adjustment for BMI, but not for HOMA2‐IR. Total testosterone was significantly associated with antral follicle count. SHBG, total testosterone and androstenedione were significantly associated with serum AMH. Only the strength of the association for SHBG was reduced after adjustment for BMI. CONCLUSIONS: Serum SHBG is associated with primarily metabolic features, whereas total testosterone and androstenedione are associated with reproductive features of PCOS. These results suggest a differential underlying pathophysiology for the metabolic and reproductive features of PCOS

The relationships of sex hormone-binding globulin, total testosterone, androstenedione and free testosterone with metabolic and reproductive features of polycystic ovary syndrome

Objective A recent Mendelian randomization study has suggested a causal role for sex hormone-binding globulin (SHBG), total testosterone and free testosterone in the pathogenesis of polycystic ovary syndrome (PCOS). The aim of this study was to assess the relationships of SHBG, androstenedione, total and free testosterone with the individual metabolic and reproductive features of PCOS. Design Cross-sectional data in PCOS patients (n=96) prospectively collected in a secondary/tertiary clinic for menstrual cycle disorders. Methods Multivariable regression analyses were conducted to study the associations between SHBG, androstenedione, total and free testosterone with metabolic (BMI, waist circumference, systolic and diastolic blood pressure, total cholesterol, LDL cholesterol, HDL cholesterol, triglycerides and homeostatic model assessment for insulin resistance [HOMA2-IR]) and reproductive features (menstrual cycle length, antral follicle count, anti-Mullerian hormone, luteinizing hormone, follicle-stimulating hormone and Ferriman-Gallwey score) of PCOS. Results Serum SHBG and free testosterone, but not total testosterone or androstenedione, were significantly associated with BMI, waist circumference, serum triglycerides, HDL cholesterol, LDL cholesterol and HOMA2-IR. The strength of the associations with serum lipids was reduced after adjustment for BMI, but not for HOMA2-IR. Total testosterone was significantly associated with antral follicle count. SHBG, total testosterone and androstenedione were significantly associated with serum AMH. Only the strength of the association for SHBG was reduced after adjustment for BMI. Conclusions Serum SHBG is associated with primarily metabolic features, whereas total testosterone and androstenedione are associated with reproductive features of PCOS. These results suggest a differential underlying pathophysiology for the metabolic and reproductive features of PCOS

Effects of fructose restriction on blood pressure: Secondary analysis of a double-blind randomized controlled trial

BACKGROUND: Despite convincing animal data, there is an ongoing debate on whether and how fructose affects blood pressure in humans. The aim of this study was to investigate the effects of fructose restriction on blood pressure, and the role of endothelial function herein. METHODS: forty-four overweight individuals were asked to follow a fructose-restricted diet (<7.5 g/meal and <10 g/day) for 6 weeks. They were randomly assigned to double-blind supplementation with glucose (=intervention group) or fructose (=control group) powder three times daily. Office blood pressure was measured with an automated device, and endothelial function was assessed by reactive hyperemia peripheral arterial tonometry, skin laser doppler flowmetry, and serum sE-selectin. RESULTS: Thirty-seven participants completed the study. Systolic blood pressure decreased significantly in the intervention group (change from baseline: -3.3 mmHg; 95%CI:-8.8,- 0.3), but this change was not statistically different from the control group. In contrast, diastolic blood pressure decreased significantly in the intervention group in comparison to controls (difference: -4.0 mmHg; 95%CI:-9.5,-0.5). Furthermore, the change in fructose intake was associated with the change in diastolic blood pressure (beta: 0.085 mmHg; 95% CI: 0.032;0.138). The endothelial markers were not affected by the intervention. Finally, the effects of the intervention on diastolic blood pressure appeared to be higher in individuals consuming high amounts of salt at baseline (difference: -9.0 mmHg; 95%CI:-14.5,-2.5). CONCLUSIONS: Six-week fructose restriction per se results in a dose-dependent decrease in diastolic blood pressure. Further studies are warranted to elucidate the effects of fructose restriction on salt-sensitive hypertension in humans. TRIAL REGISTRATION: www. CLINICALTRIALS: gov; NCT03067428

Effects of fructose restriction on blood pressure:Secondary analysis of a double-blind randomized controlled trial

Background: Despite convincing animal data, there is an ongoing debate on whether and how fructose affects blood pressure in humans. The aim of this study was to investigate the effects of fructose restriction on blood pressure, and the role of endothelial function herein. Methods: forty-four overweight individuals were asked to follow a fructose-restricted diet (<7.5 g/meal and <10 g/day) for 6 weeks. They were randomly assigned to double-blind supplementation with glucose (=intervention group) or fructose (=control group) powder three times daily. Office blood pressure was measured with an automated device, and endothelial function was assessed by reactive hyperemia peripheral arterial tonometry, skin laser doppler flowmetry, and serum sE-selectin. Results: Thirty-seven participants completed the study. Systolic blood pressure decreased significantly in the intervention group (change from baseline: −3.3 mmHg; 95%CI:-8.8,– 0.3), but this change was not statistically different from the control group. In contrast, diastolic blood pressure decreased significantly in the intervention group in comparison to controls (difference: −4.0 mmHg; 95%CI:-9.5,-0.5). Furthermore, the change in fructose intake was associated with the change in diastolic blood pressure (beta: 0.085 mmHg; 95% CI: 0.032;0.138). The endothelial markers were not affected by the intervention. Finally, the effects of the intervention on diastolic blood pressure appeared to be higher in individuals consuming high amounts of salt at baseline (difference: −9.0 mmHg; 95%CI:-14.5,-2.5). Conclusions: Six-week fructose restriction per se results in a dose-dependent decrease in diastolic blood pressure. Further studies are warranted to elucidate the effects of fructose restriction on salt-sensitive hypertension in humans. Trial registration: www.clinicaltrials.gov; NCT03067428

Serum sex hormone-binding globulin is a mediator of the association between intrahepatic lipid content and type 2 diabetes: the Maastricht Study

AIMS/HYPOTHESIS: Serum sex hormone-binding globulin (SHBG) has been proposed to act as a hepatokine that contributes to the extrahepatic complications observed in non-alcoholic fatty liver disease (NAFLD). However, it remains uncertain whether serum SHBG mediates the association between intrahepatic lipids (IHL) and type 2 diabetes. Therefore, we studied whether, and to what extent, serum SHBG mediates the association between IHL content and type 2 diabetes. METHODS: We used cross-sectional data from the Maastricht Study (n=1554), a population-based cohort study with oversampling of individuals with type 2 diabetes. Type 2 diabetes status was assessed by oral glucose tolerance test, and IHL content was measured using 3T Dixon MRI. Mediation analyses were performed to assess the role of serum SHBG in mediating the association between IHL content and type 2 diabetes. RESULTS: IHL content was significantly associated with type 2 diabetes in women and men (OR 1.08 [95% CI 1.04, 1.14] and OR 1.12 [95% CI 1.08, 1.17], respectively). Serum SHBG significantly mediated the association between IHL content and type 2 diabetes. The contribution of serum SHBG was higher in women (OR 1.04 [95% CI 1.02, 1.07]; proportion mediated 50.9% [95% CI 26.7, 81.3]) than in men (OR 1.02 [95% CI 1.01, 1.03]; proportion mediated 17.2% [95% CI 9.6, 27.6]). Repeat analyses with proxies of type 2 diabetes and adjustment for covariates did not substantially affect the results. CONCLUSIONS/INTERPRETATION: In this large-scale population-based cohort study, serum SHBG was found to be a mediator of the association between IHL content and type 2 diabetes. These findings extend our understanding of the potential mechanisms by which NAFLD is a risk factor for type 2 diabetes, and further elaborate on the role of SHBG as a hepatokine