Sex-specific metabolic profiles of androgens and its main binding protein SHBG in a middle aged population without diabetes

Longitudinal non-targeted metabolomic profiling of urine samples for monitoring of kidney transplantation patients

The assessment of kidney function within the first year following transplantation is crucial for predicting long-term graft survival. This study aimed to develop a robust and accurate model using metabolite profiles to predict early long-term outcomes in patient groups at the highest risk of early graft loss. A group of 61 kidney transplant recipients underwent thorough monitoring during a one-year follow-up period, which included a one-week hospital stay and follow-up assessments at three and six months. Based on their 12-month follow-up serum creatinine levels: Group 2 had levels exceeding 1.5 mg/dl, while Group 1 had levels below 1.5 mg/dl. Metabolites were detected by mass spectrometer and first pre-processed. Univariate and multivariate statistical analyses were employed to identify significant differences between the two groups. Nineteen metabolites were found to differ significantly in the 1st week, and seventeen metabolites in the 3rd month (adjusted p-value < 0.05, quality control (QC) < 30, a fold change (FC) > 1.1 or a FC < 0.91, Variable Influence on Projection (VIP) > 1). However, no significant differences were observed in the 6th month. These distinctive metabolites mainly belonged to lipid, fatty acid, and amino acid categories. Ten models were constructed using a backward conditional approach, with the best performance seen in model 5 for Group 2 at the 1st-week mark (AUC 0.900) and model 3 at the 3rd-month mark (AUC 0.924). In conclusion, the models developed in the early stages may offer potential benefits in the management of kidney transplant patients.

Novel Lipidomic Signature Associated With Metabolic Risk in Women With and Without Polycystic Ovary Syndrome

CONTEXT

Dyslipidemia is a feature of polycystic ovary syndrome (PCOS) and may augment metabolic dysfunction in this population.

OBJECTIVE

Using comprehensive lipidomic profiling and gold-standard metabolic measures, we examined whether distinct lipid biomarkers were associated with metabolic risk in women with and without PCOS.

METHODS

Using preexisting data and biobanked samples from 76 women (n = 42 with PCOS), we profiled > 700 lipid species by mass spectrometry. Lipids were compared between women with and without PCOS and correlated with direct measures of adiposity (dual x-ray absorptiometry and computed tomography) and insulin sensitivity (hyperinsulinemic-euglycemic clamp), as well as fasting insulin, HbA1c, and hormonal parameters (luteinizing and follicle-stimulating hormones; total and free testosterone; sex hormone-binding globulin [SHBG]; and free androgen index [FAI]). Multivariable linear regression was used with correction for multiple testing.

RESULTS

Despite finding no differences by PCOS status, lysophosphatidylinositol (LPI) species esterified with an 18:0 fatty acid were the strongest lipid species associated with all the metabolic risk factors measured in women with and without PCOS. Across the cohort, higher concentrations of LPI(18:0) and lower concentrations of lipids containing docosahexaenoic acid (DHA, 22:6) n-3 polyunsaturated fatty acids were associated with higher adiposity, insulin resistance, fasting insulin, HbA1c and FAI, and lower SHBG.

CONCLUSION

Our data indicate that a distinct lipidomic signature comprising high LPI(18:0) and low DHA-containing lipids are associated with key metabolic risk factors that cluster in PCOS, independent of PCOS status. Prospective studies are needed to corroborate these findings in larger cohorts of women with varying PCOS phenotypes.

Cardiovascular Disease Risk Factors and Metabolic Morbidity in a Longitudinal Study of Congenital Adrenal Hyperplasia

CONTEXT

Patients with congenital adrenal hyperplasia (CAH) are exposed to hyperandrogenism and supraphysiologic glucocorticoids, both of which can increase risk of metabolic morbidity.

OBJECTIVE

Our aim was to evaluate cardiovascular and metabolic morbidity risk in a longitudinal study of patients with CAH spanning both childhood and adulthood.

DESIGN AND SETTING

Patients with classic CAH followed for a minimum of 5 years during both childhood and adulthood (n = 57) at the National Institutes of Health were included and compared with the US general population using NHANES data.

MAIN OUTCOME MEASURES

Obesity, hypertension, insulin resistance, fasting hyperglycemia, and dyslipidemia.

RESULTS

Compared to the US population, patients with CAH had higher (P < 0.001) prevalence of obesity, hypertension, insulin resistance, fasting hyperglycemia, and low high-density lipoprotein (HDL) during childhood and obesity (P = 0.024), hypertension (P<0.001), and insulin resistance (P < 0.001) during adulthood. In our cohort, obesity, hypertension, fasting hyperglycemia, and hypertriglyceridemia began prior to age 10. During childhood, increased mineralocorticoid dose was associated with hypertension (P = 0.0015) and low HDL (P = 0.0021). During adulthood, suppressed androstenedione was associated with hypertension (P = 0.002), and high low-density lipoprotein (P = 0.0039) whereas suppressed testosterone (P = 0.003) was associated with insulin resistance. Elevated 17-hydroxyprogesterone, possibly reflecting poor disease control, was protective against high cholesterol (P = 0.0049) in children. Children whose mothers were obese (maternal obesity) had increased risk of obesity during adulthood (P = 0.0021). Obesity, in turn, contributed to the development of hypertension, insulin resistance, and hypertriglyceridemia in adulthood.

CONCLUSION

Patients with CAH develop metabolic morbidity at a young age associated with treatment-related and familial factors. Judicious use of glucocorticoid and mineralocorticoid is warranted.

Safety Aspects of the Use of Isolated Piperine Ingested as a Bolus

Piperine is a natural ingredient of Piper nigrum (black pepper) and some other Piper species. Compared to the use of pepper for food seasoning, piperine is used in food supplements in an isolated, concentrated form and ingested as a bolus. The present review focuses on the assessment of the possible critical health effects regarding the use of isolated piperine as a single ingredient in food supplements. In human and animal studies with single or short-term bolus application of isolated piperine, interactions with several drugs, in most cases resulting in increased drug bioavailability, were observed. Depending on the drug and extent of the interaction, such interactions may carry the risk of unintended deleteriously increased or adverse drug effects. Animal studies with higher daily piperine bolus doses than in human interaction studies provide indications of disturbance of spermatogenesis and of maternal reproductive and embryotoxic effects. Although the available human studies rarely reported effects that were regarded as being adverse, their suitability for detailed risk assessment is limited due to an insufficient focus on safety parameters apart from drug interactions, as well as due to the lack of investigation of the potentially adverse effects observed in animal studies and/or combined administration of piperine with other substances. Taken together, it appears advisable to consider the potential health risks related to intake of isolated piperine in bolus form, e.g., when using certain food supplements.

Vitamin D equilibrium affects sex-specific changes in lipid concentrations during Christian Orthodox fasting

We aimed to evaluate sex differences in changes of lipid profiles in a cohort of metabolically healthy adults following Orthodox fasting (OF), as well as to assess a potential role of vitamin D status in mediating these variations. 45 individuals (24 premenopausal females, 53.3 %) with mean age 48.3 ± 9.1 years and mean Body Mass Index 28.7 ± 5.8 kg/m² were prospectively followed for 12 weeks. Anthropometry, dietary and biochemical data regarding serum lipids, and vitamin D status were collected at baseline, 7 weeks after the implementation of OF, and 5 weeks after fasters returned to their standard dietary habits (12 weeks from baseline). According to 25-hydroxy-vitamin D [25(OH)D] measurements, participants were divided into two groups: those with concentrations above and below the median of values. Females with 25(OH)D concentrations below the median manifested a non-significant reduction by approximately 15 % in total and low-density lipoprotein cholesterol during the fasting period, followed by a significant increase 5 weeks after OF cessation (170.7 vs. 197.5 and 99.6 vs. 121.0 mg/dl respectively, p < 0.001). In contrast, males with 25(OH)D levels below the median demonstrated an inverse, non-significant trend of increase in lipid concentrations during the whole study period. Our findings suggest strikingly different inter-gender lipid responses to a dietary model of low-fat, mediated by vitamin D status. Further studies are necessary to reveal the underlying mechanisms and assess the importance of these differences with respect to cardiovascular health and the benefit of vitamin D supplementation strategies.

Pepper Alkaloids and Processed Meat Intake: Results from a Randomized Trial and the European Prospective Investigation into Cancer and Nutrition (EPIC) Cohort

SCOPE

Processed meat intake has been associated with adverse health outcomes. However, little is known about the type of processed meat more particularly responsible for these effects. This study aims to identify novel biomarkers for processed meat intake.

METHODS AND RESULTS

In a controlled randomized cross-over dietary intervention study, 12 healthy volunteers consume different processed and non-processed meats for 3 consecutive days each. Metabolomics analyses are applied on post-intervention fasting blood and urine samples to identify discriminating molecular features of processed meat intake. Nine and five pepper alkaloid metabolites, including piperine, are identified as major discriminants of salami intake in urine and plasma, respectively. The associations with processed meat intake are tested for replication in a cross-sectional study (n = 418) embedded within the European Prospective Investigation into Cancer and Nutrition (EPIC) cohort. Three of the serum metabolites including piperine are associated with habitual intake of sausages and to a lesser extent of total processed meat.

CONCLUSION

Pepper alkaloids are major discriminants of intake for sausages that contain high levels of pepper used as ingredient. Further work is needed to assess if pepper alkaloids in combination with other metabolites may serve as biomarkers of processed meat intake.

Associations between smoking, sex hormone levels and late-onset hypogonadism in men differ depending on age

Few studies have investigated whether associations between smoking, sex hormone levels, and symptoms of late-onset hypogonadism (LOH) in men are affected by age. This multi-center, cross-sectional study involving 6,296 men aged 40-79 years was conducted between June 1, 2013 and August 31, 2016 in 6 provinces of China. Total testosterone, free testosterone, and Aging Males’ Symptoms scale (AMS) scores were compared depending on smoking status and the number of cigarettes smoked. Total testosterone was higher in smokers than in non-smokers in all except the 70-79 year old subgroup. Free testosterone was higher in smokers than non-smokers for the 40-49 and 50-59 year old subgroups, but not the 60-69 and 70-79 year old subgroups. Total testosterone was positively associated with number of cigarettes consumed in smokers aged 40-49 and 50-59 years. Sexual and somatic AMS scores were higher in current and ex-smokers than in non-smokers in all age subgroups from 40 to 79 years and were negatively associated with cigarette consumption in smokers aged 40-49 years. These results indicate that, as men age, the positive association between smoking and testosterone weakens, while the positive association between smoking and LOH symptoms becomes stronger.

Associations between adipose tissue volume and small molecules in plasma and urine among asymptomatic subjects from the general population

Obesity is one of the major risk factor for cardiovascular and metabolic diseases. A disproportional accumulation of fat at visceral (VAT) compared to subcutaneous sites (SAT) has been suspected as a key detrimental event. We used non-targeted metabolomics profiling to reveal metabolic pathways associated with higher VAT or SAT amount among subjects free of metabolic diseases to identify possible contributing metabolic pathways. The study population comprised 491 subjects [mean (standard deviation): age 44.6 yrs (13.0), body mass index 25.4 kg/m² (3.6), 60.1% females] without diabetes, hypertension, dyslipidemia, the metabolic syndrome or impaired renal function. We associated MRI-derived fat amounts with mass spectrometry-derived metabolites in plasma and urine using linear regression models adjusting for major confounders. We tested for sex-specific effects using interactions terms and performed sensitivity analyses for the influence of insulin resistance on the results. VAT and SAT were significantly associated with 155 (101 urine) and 49 (29 urine) metabolites, respectively, of which 45 (27 urine) were common to both. Major metabolic pathways were branched-chain amino acid metabolism (partially independent of insulin resistance), surrogate markers of oxidative stress and gut microbial diversity, and cortisol metabolism. We observed a novel positive association between VAT and plasma levels of the potential pharmacological agent piperine. Sex-specific effects were only a few, e.g. the female-specific association between VAT and O-methylascorbate. In brief, higher VAT was associated with an unfavorable metabolite profile in a sample of healthy, mostly non-obese individuals from the general population and only few sex-specific associations became apparent.

Genetic studies of urinary metabolites illuminate mechanisms of detoxification and excretion in humans

The kidneys integrate information from continuous systemic processes related to the absorption, distribution, metabolism and excretion (ADME) of metabolites. To identify underlying molecular mechanisms, we performed genome-wide association studies of the urinary concentrations of 1,172 metabolites among 1,627 patients with reduced kidney function. The 240 unique metabolite-locus associations (metabolite quantitative trait loci, mQTLs) that were identified and replicated highlight novel candidate substrates for transport proteins. The identified genes are enriched in ADME-relevant tissues and cell types, and they reveal novel candidates for biotransformation and detoxification reactions. Fine mapping of mQTLs and integration with single-cell gene expression permitted the prioritization of causal genes, functional variants and target cell types. The combination of mQTLs with genetic and health information from 450,000 UK Biobank participants illuminated metabolic mediators, and hence, novel urinary biomarkers of disease risk. This comprehensive resource of genetic targets and their substrates is informative for ADME processes in humans and is relevant to basic science, clinical medicine and pharmaceutical research.

Understanding the association of polycystic ovary syndrome and non-alcoholic fatty liver disease

Polycystic ovary syndrome (PCOS) is the most common endocrine disorder among reproductive-age women. Patients with non-alcoholic fatty liver disease (NAFLD) often suffer from metabolic syndrome, atherosclerosis, ischemic heart disease, and extrahepatic tumors, conferring a lower survival than the general population; therefore it is crucial to study the association between NAFLD and PCOS since it remains poorly understood. Insulin resistance (IR) plays a central role in the pathogenesis of NAFLD and PCOS; also, hyperandrogenism enhances IR in these patients. IR, present in the NAFLD-PCOS association could decrease the hepatic production of sex hormone-binding globulin through a possible regulation mediated by hepatocyte nuclear factor 4 alpha. On the other hand, apoptotic processes initiated by androgens actively contribute to the progression of NAFLD. Considering the association between the two conditions, the screening of women with PCOS for the presence of NAFLD appears reasonable. The pathophysiological mechanisms of PCOS-NAFLD association and the initial approach will be reviewed here.

Sex-specific metabolic and functional differences in human umbilical vein endothelial cells from twin pairs

BACKGROUND AND AIMS

Gonadal hormones are mainly thought to account for sex and gender differences in the incidence, clinical manifestation and therapy of many cardiovascular diseases. However, intrinsic sex differences at the cellular level are mostly overlooked. Here, we assessed sex-specific metabolic and functional differences between male and female human umbilical vein endothelial cells (HUVECs).

METHODS

Cellular metabolism was investigated by bioenergetic studies (Seahorse Analyser) and a metabolomic approach. Protein levels were determined by Western blots and proteome analysis. Vascular endothelial growth factor (VEGF)-stimulated cellular migration was assessed by gap closure. HUVECs from dizygotic twin pairs were used for most experiments.

RESULTS

No sex differences were observed in untreated cells. However, sexual dimorphisms appeared after stressing the cells by serum starvation and treatment with VEGF. Under both conditions, female cells had higher intracellular ATP and metabolite levels. A significant decline in ATP levels was observed in male cells after serum starvation. After VEGF, the ratio of glycolysis/mitochondrial respiration was higher in female cells and migration was more pronounced.

CONCLUSIONS

These results point to an increased stress tolerance of female cells. We therefore propose that female cells have an energetic advantage over male cells under conditions of diminished nutrient supply. A more favourable energy balance of female HUVECs after serum starvation and VEGF could potentially explain their stronger migratory capacity.

Comprehensive Metabolic Profiling Reveals a Lipid-Rich Fingerprint of Free Thyroxine Far Beyond Classic Parameters

OBJECTIVE

Thyroid hormones are ubiquitously involved in human metabolism. However, the precise molecular patterns associated with alterations in thyroid hormones levels remain to be explored in detail. A number of recent studies took great advantage of metabolomics profiling to outline the metabolic actions of thyroid hormones in humans.

METHODS

Among 952 participants in the Study of Health in Pomerania, data on serum free thyroxine (FT4) and thyrotropin and comprehensive nontargeted metabolomics data from plasma and urine samples were available. Linear regression analyses were performed to assess the association between FT4 or thyrotropin and metabolite levels.

RESULTS AND CONCLUSION

After accounting for major confounders, 106 of 613 plasma metabolites were significantly associated with FT4. The associations in urine were minor (12 of 587). Most of the plasma metabolites consisted of lipid species, and subsequent analysis of highly resolved lipoprotein subclasses measured by proton nuclear magnetic resonance spectroscopy revealed a consistent decrease in several of these species (e.g., phospholipids) and large low-density lipoprotein and small high-density lipoprotein particles. The latter was unique to men. Several polyunsaturated and saturated fatty acids displayed an association with FT4 in women only. A random forest-based variable selection approach using phenotypic characteristics revealed higher alcohol intake in men and an adverse thyroid state and menopause in women as the putative mediating factors. In general, our observations have confirmed the lipolytic and lipogenic effect of thyroid hormones even in the physiological range and revealed different phenotypic characteristics (e.g., lifestyle differences) as possible confounders for sex-specific findings.