Clustering of cardiovascular risk factors associated with the insulin resistance syndrome: assessment by principal component analysis in young hyperandrogenic women

Determining independence and associations among various cardiovascular disease risk factors in 9-12 years old school-children: a cross sectional study

Background

Cardiovascular disease (CVD) risk assessment of children typically includes evaluating multiple CVD risk factors some of which tend to correlate each other. However, in older children and young adolescents, there are little data on the level of independence of CVD risk factors. The purpose of this study was to examine the relationships among various CVD risk factors to determine the level of independence of each risk factor in a sample of 5^th-grade public school students.

Method

A cross-sectional analysis of 1525 children (856 girls and 669 boys; age: 9-12 years) who participated in baseline CVD risk assessment for the (S)Partners for Heart Health program from 2010 - 2018. Thirteen CVD risk factor variables were used in the analysis and included blood lipids [low-density lipoprotein (LDL), high-density lipoprotein (HDL), total cholesterol (TC), and triglycerides], resting systolic and diastolic blood pressure (BP); anthropometrics [height, weight, body mass index (BMI), % body fat, waist circumference (WC)]. Additionally, acanthosis nigricans (a marker insulin resistance and diabetes), and cardiorespiratory fitness (VO2 ml/kg) was estimated using the PACER. Descriptive statistics, bivariate Pearson correlations, and principal component analysis were used to determine the relationships among these variables and the independence.

Results

Parallel analysis indicated two components should be extracted. Among the two components extracted, WC, % body fat, and BMI loaded highest on component 1, which explained 34% of the total variance. Systolic BP and diastolic BP loaded predominantly on component 2 and accounted for 17% of the variance. Cardiorespiratory fitness, acanthosis nigricans, HDL, and triglycerides loaded highest on the first component (loadings between 0.42 and 0.57) but still suggest some non-shared variance with this component. Low-density lipoprotein had low loadings on each component. Factor loadings were stable across sex.

Conclusion

Among the various CVD risk indicators, measures of adiposity loaded highest on the component that explained the largest proportion of variability in the data reinforcing the importance of assessing adiposity in CVD risk assessment. In addition, blood pressure loaded highest on the second component, suggesting their relative independence when assessing CVD risk. The data also provide support and rationale for determining what CVD risk factors to include- based on resource needs. For example, researchers or public health programs may choose to assess WC instead of lipid profile for cardiovascular related problems if ease of assessment and cost are considerations.

Downregulation of aromatase plays a dual role in preeclampsia

Preeclampsia (PE) is a gestational disease, which seriously impairs maternal and infant health. However, the pathogenesis of PE remains unclear. The aromatase (CYP19A1) in placenta converts androgens from maternal and fetal adrenal glands to estrogen. Therefore, this change in the aromatase expression or function and the subsequent change of steroids in the placenta could be related to the pathophysiology of PE. In this study, we first analyzed the expression of CYP19A1 in clinical placental tissues as well as the level of sex hormones in corresponding serum samples. The results showed that the expression of aromatase in the placenta of PE patients was relatively low and accompanied by a sex hormone imbalance. Subsequently, animal experiments showed that ischemia and hypoxia lead to a low expression of CYP19A1, and that PE-like symptoms appear in pregnant mice following decreased or inhibited CYP19A1 expression. It was also found that, with the downregulation of CYP19A1 expression, the invasion and migration abilities of trophoblast cells were enhanced, which benefited placental implantation. However, alongside this, apoptosis and the inflammatory response were also increased, which was detrimental to placental development. Phosphoproteomic analyses revealed that the activation of the PI3K/AKT signaling pathway may play a key role in these processes. In conclusion, the downregulation of aromatase has a dual role in PE, among which the induction of the disease is the main role. Our study provides a potential novel method for the early prediction and treatment of PE.

Racial and ethnic differences in the prevalence of metabolic syndrome and its components of metabolic syndrome in women with polycystic ovary syndrome: a regional cross-sectional study

BACKGROUND

Polycystic ovary syndrome is a heterogeneous disorder and its presentation varies with race and ethnicity. Reproductive-age women with polycystic ovary syndrome are at increased risk of metabolic syndrome; however, it is not clear if prevalence of metabolic syndrome and clustering of its components differs based on race and ethnicity. Moreover, the majority of these women do not undergo routine screening for metabolic syndrome.

OBJECTIVE

We sought to compare the prevalence of metabolic syndrome and clustering of its components in women with polycystic ovary syndrome in the United States with women in India, Brazil, Finland, and Norway.

STUDY DESIGN

This is a cross-sectional study performed in 1089 women with polycystic ovary syndrome from 1999 through 2016 in 5 outpatient clinics in the United States, India, Brazil, Finland, and Norway. Polycystic ovary syndrome was defined by the Rotterdam criteria. Main outcome measures were: metabolic syndrome prevalence, blood pressure, body mass index, fasting high-density lipoprotein cholesterol, fasting triglycerides, and fasting glucose. Data from all sites were reevaluated for appropriate application of diagnostic criteria for polycystic ovary syndrome, identification of polycystic ovary syndrome phenotype, and complete metabolic workup. The US White women with polycystic ovary syndrome were used as the referent group. Logistic regression models were used to evaluate associations between race and metabolic syndrome prevalence and its components and to adjust for potential confounders, including age and body mass index.

RESULTS

The median age of the entire cohort was 28 years. Women from India had the highest mean Ferriman-Gallwey score for clinical hyperandrogenism (15.6 ± 6.5, P < .001). The age-adjusted odds ratio for metabolic syndrome was highest in US Black women at 4.52 (95% confidence interval, 2.46-8.35) compared with US White women. When adjusted for age and body mass index, the prevalence was similar in the 2 groups. Significantly more Black women met body mass index and blood pressure criteria (P < .001), and fewer met fasting triglycerides criteria (P < .05). The age- and body mass index-adjusted prevalence of metabolic syndrome was highest in Indian women (odds ratio, 6.53; 95% confidence interval, 3.47-12.30) with abnormalities in glucose and fasting high-density lipoprotein cholesterol criterion and in Norwegian women (odds ratio, 2.16; 95% confidence interval, 1.17-3.98) with abnormalities in blood pressure, glucose, and fasting high-density lipoprotein cholesterol criterion. The Brazilian and Finnish cohorts had similar prevalence of metabolic syndrome and its components compared to US White women.

CONCLUSION

Despite a unifying diagnosis of polycystic ovary syndrome, there are significant differences in the prevalence of metabolic syndrome and clustering of its components based on race and ethnicity, which may reflect contributions from both racial and environmental factors. Our findings indicate the prevalence of metabolic syndrome components varies in women with polycystic ovary syndrome, such that compared to White women from the United States, Black US women had the highest prevalence, whereas women from India and Norway had a higher prevalence of metabolic syndrome independent of obesity. The differences in clustering of components of metabolic syndrome based on ethnicity highlight the need to routinely perform complete metabolic screening to identify specific targets for cardiovascular risk reduction strategies in these reproductive-age women.

Ursolic acid plays a protective role in obesity-induced cardiovascular diseases

The metabolic disturbance of obesity is one of the most common risk factors of atherosclerosis. Resistin, an obesity-induced adipokine, can induce the expression of cell adhesion molecules and the attachment of monocytes to endothelial cells, which play an important role in the development of atherosclerosis. Ursolic acid, a pentacyclic triterpenoid found in fruits and many herbs, exhibits an array of biological effects such as anti-inflammatory and antioxidative properties. The aim of this study was to investigate the potential underlying mechanisms of the effect of ursolic acid on resistin-induced adhesion of U937 cells to human umbilical vein endothelial cells (HUVECs). Our data indicated that ursolic acid suppressed the adhesion of U937 to HUVECs and downregulated the expression of adhesion molecules, vascular cell adhesion molecule-1 (VCAM-1), intracellular cell adhesion molecule-1 (ICAM-1), and E-selectin, in resistin-induced HUVECs by decreasing the production of intracellular reaction oxygen species (ROS) and attenuating the nuclear translocation of NFκB. Ursolic acid appeared to inhibit resistin-induced atherosclerosis, suggesting that ursolic acid may play a protective role in obesity-induced cardiovascular diseases.

Biochemical hyperandrogenism is associated with metabolic syndrome independently of adiposity and insulin resistance in Romanian polycystic ovary syndrome patients

The aim of the study was to determine whether Romanian polycystic ovary syndrome (PCOS) patients have an increased prevalence of metabolic syndrome (MetS) and to study the involvement of adiposity, insulin resistance and hyperandrogenism in the pathogenesis of MetS in PCOS. A total of 398 PCOS patients and 126 controls were evaluated between January 2006 and December 2012. MetS was defined by National Cholesterol Education Program, Adult Treatment Panel III criteria. Principal component analysis (PCA) was used to analyze the correlations among variables of interest by grouping them in few components, and principal component (PCs) scores were saved and used as independent variables in logistic regression. The prevalence of MetS was higher among patients with PCOS (20.4 %) than in controls (11.1 %, p < 0.05). In PCOS patients, PCA extracted three PCs from the analyzed variables. First PC aggregated variables related to adiposity and insulin resistance, with factor loadings showing strong relationship between these parameters. The second PC included markers of hyperandrogenemia and was best represented by free androgen index (FAI) which correlated strongly and exclusively with this PC. The third component was best represented by hirsutism. Logistic regression analysis revealed that in PCOS patients, the first and the second PCs were independently associated with MetS, whereas the third component was not. Romanian PCOS patients have an increased risk for MetS; adiposity, insulin resistance and hyperandrogenemia, but not hirsutism, are independent predictors of MetS presence. Our data also suggest that insulin resistance is only secondary to increased adiposity and FAI is a good marker of biochemical hyperandrogenism with little influences from the metabolic component.

Clustering of metabolic and cardiovascular risk factors in the polycystic ovary syndrome: a principal component analysis

CONTEXT

Polycystic ovary syndrome (PCOS) is a prevalent condition with heterogeneity of clinical features and cardiovascular risk factors that implies multiple aetiological factors and possible outcomes.

OBJECTIVE

To reduce a set of correlated variables to a smaller number of uncorrelated and interpretable factors that may delineate subgroups within PCOS or suggest pathogenetic mechanisms.

MATERIALS AND METHODS

We used principal component analysis (PCA) to examine the endocrine and cardiometabolic variables associated with PCOS defined by the National Institutes of Health (NIH) criteria. Data were retrieved from the database of a single clinical endocrinologist. We included women with PCOS (N = 378) who were not taking the oral contraceptive pill or other sex hormones, lipid lowering medication, metformin or other medication that could influence the variables of interest. PCA was performed retaining those factors with eigenvalues of at least 1.0. Varimax rotation was used to produce interpretable factors.

RESULTS

We identified three principal components. In component 1, the dominant variables were homeostatic model assessment (HOMA) index, body mass index (BMI), high density lipoprotein (HDL) cholesterol and sex hormone binding globulin (SHBG); in component 2, systolic blood pressure, low density lipoprotein (LDL) cholesterol and triglycerides; in component 3, total testosterone and LH/FSH ratio. These components explained 37%, 13% and 11% of the variance in the PCOS cohort respectively.

CONCLUSIONS

Multiple correlated variables from patients with PCOS can be reduced to three uncorrelated components characterised by insulin resistance, dyslipidaemia/hypertension or hyperandrogenaemia. Clustering of risk factors is consistent with different pathogenetic pathways within PCOS and/or differing cardiometabolic outcomes.

Hyperandrogenemia is implicated in both the metabolic and reproductive morbidities of polycystic ovary syndrome

OBJECTIVE

To determine the features of polycystic ovary syndrome (PCOS) that are implicated in the associated reproductive and metabolic morbidities.

DESIGN

Cross-sectional case-control study.

SETTING

Academic medical setting.

PATIENT(S)

A total of 1,062 women with PCOS and 1,887 women without PCOS.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Physical examination including hirsutism scoring, biochemical and hormone measurements, ovarian ultrasound, and a 75-g oral glucose tolerance test to measure glucose and insulin levels.

RESULT(S)

A factor analysis identified four dominant factors in women with PCOS. These factors were interpreted as follows: [1] metabolic and hyperandrogenemia factor, [2] oligomenorrhea and hyperandrogenemia factor, [3] blood pressure factor, and [4] ovarian morphology factor. In women with PCOS, hyperandrogenemia was a significant predictor of metabolic syndrome after adjusting for age, body mass index, and insulin resistance in the regression analysis.

CONCLUSION(S)

A factor analysis identified multiple factors that are responsible for the abnormalities associated with PCOS. Hyperandrogenemia was a common underlying feature of the metabolic and reproductive abnormalities in women with PCOS but not in women without PCOS.

Testosterone and metabolic syndrome: The link

Metabolic syndrome (MetS) or "Syndrome X" which is a constellation of insulin resistance, hyperglycemia, hypertension, low high-density lipoprotein cholesterol (HDL-C), and increased very-low-density lipoprotein (VLDL) and triglyceride (TG) levels. It is one of the main threats for public health in the 21st century with its associated risk of cardiovascular disease. This condition affects a major chunk of mankind. International Diabetes Federation (IDF) estimated that around 20-25% of the adult population of the world has MetS. Several definitions have been put forward by different expert bodies leading to confusion. To overcome this, joint new statement of many expert group have been issued. Serum testosterone (T) has been shown to be associated with MetS. Several studies have shown a higher prevalence of MetS in subjects with low testosterone. There are also several studies showing a significant difference in serum T between those with MetS and those without. Serum T has also been shown to be associated with components of MetS and testosterone replacement therapy (TRT) improves various metabolic and anthropometric parameters in MetS. Patients with androgen deprivation for treatment of various cancers have also been reported to have higher prevalence of MetS. But the evidence of association is not sufficient evidence for the causation of MetS by low testosterone and long-term studies are needed to confirm whether T deficiency is the cause or is a feature of MetS.

Abnormal serum alanine aminotransferase levels are associated with impaired insulin sensitivity in young women with polycystic ovary syndrome

BACKGROUND AND AIM

Non-alcoholic fatty liver disease (NAFLD) and polycystic ovary syndrome (PCOS) are both associated with insulin resistance.We assessed whether NAFLD is associated with impaired insulin sensitivity in PCOS women independently of age and total adiposity.

SUBJECTS AND METHODS

We enrolled 14 young PCOS women with NAFLD, 14 women with PCOS alone and 14 healthy controls, who were matched for age, body mass index, and total body fat (by bio-impedance analyzer). NAFLD was diagnosed by the surrogate measure of abnormal serum alanine aminotransferase (ALT) concentrations (defined as ALT>19 U/l) after excluding other secondary causes of liver disease (alcohol, virus, and medications). Insulin sensitivity was measured by euglycemic hyperinsulinemic clamp.

RESULTS

Insulin sensitivity was markedly decreased (p<0.001) in PCOS women with abnormal ALT levels, whereas it was similar between PCOS women with normal ALT levels andmatched healthy controls (8.3+/-2.5 vs 12.1+/-1.7 vs 13.2+/-1.8 mg/min x kg of fat-free mass, respectively). PCOS women with abnormal ALT levels also had higher plasma triglycerides and lower HDLcholesterol concentrations than those with PCOS alone. There was a strong inverse association between serum ALT levels and insulin sensitivity in the whole group of PCOS women (r=-0.59, p=0.0013).

CONCLUSIONS

Abnormal serum ALT levels, as surrogate measure of NAFLD, are closely associated with impaired insulin sensitivity in young PCOS women in a manner that is independent from the contribution of age and total adiposity. Early recognition of NAFLD by radiological imaging tests in this group of young patients is warranted.

Abnormal serum alanine aminotransferase levels are associated with impaired insulin sensitivity in young women with polycystic ovary syndrome

BACKGROUND AND AIM

Non-alcoholic fatty liver disease (NAFLD) and polycystic ovary syndrome (PCOS) are both associated with insulin resistance.We assessed whether NAFLD is associated with impaired insulin sensitivity in PCOS women independently of age and total adiposity.

SUBJECTS AND METHODS

We enrolled 14 young PCOS women with NAFLD, 14 women with PCOS alone and 14 healthy controls, who were matched for age, body mass index, and total body fat (by bio-impedance analyzer). NAFLD was diagnosed by the surrogate measure of abnormal serum alanine aminotransferase (ALT) concentrations (defined as ALT>19 U/l) after excluding other secondary causes of liver disease (alcohol, virus, and medications). Insulin sensitivity was measured by euglycemic hyperinsulinemic clamp.

RESULTS

Insulin sensitivity was markedly decreased (p<0.001) in PCOS women with abnormal ALT levels, whereas it was similar between PCOS women with normal ALT levels andmatched healthy controls (8.3+/-2.5 vs 12.1+/-1.7 vs 13.2+/-1.8 mg/min x kg of fat-free mass, respectively). PCOS women with abnormal ALT levels also had higher plasma triglycerides and lower HDLcholesterol concentrations than those with PCOS alone. There was a strong inverse association between serum ALT levels and insulin sensitivity in the whole group of PCOS women (r=-0.59, p=0.0013).

CONCLUSIONS

Abnormal serum ALT levels, as surrogate measure of NAFLD, are closely associated with impaired insulin sensitivity in young PCOS women in a manner that is independent from the contribution of age and total adiposity. Early recognition of NAFLD by radiological imaging tests in this group of young patients is warranted.

The importance of the (TAAAA)n alleles at the SHBG gene promoter for the severity of coronary artery disease in postmenopausal women

OBJECTIVE

Androgen may be detrimental in the development of coronary artery disease (CAD) in women. We investigated possible associations between the (TAAAA)n polymorphism of sex hormone-binding globulin (SHBG) gene promoter, which influences transcriptional efficiency of the SHBG gene and the severity of CAD in women.

DESIGN

In this prospective clinical study, 146 postmenopausal women (46-88 y) undergoing coronary angiography were studied. CAD severity, history of angina and myocardial infarction, and reproductive history were recorded and hormonal parameters measured. According to the number of SHBG gene promoter repeat polymorphisms, participants were classified into short (seven or fewer), medium length (eight), and long repeat (nine or more) allele groups.

RESULTS

Significant CAD was more prevalent in the long repeat allele carrier group: 65% of the participants with three vessels with severe stenosis belonged to the long repeat allele group, whereas only 37% of participants with mild CAD belonged to this group (P=0.01). A history of angina and prevalence of hyperlipidemia was more frequent in the long repeat allele group (P<0.05). Calculated free testosterone levels were higher in the long repeat allele groups (P<0.05), whereas SHBG levels tended to be lower (P=0.06). SHBG levels correlated inversely with body mass index and waist circumference (P<0.05).

CONCLUSIONS

Longer (TAAAA)n repeats in the SHBG gene promoter are associated with more severe CAD in women undergoing coronary angiography, a finding not previously reported. This association may reflect the lifelong tissue exposure to higher free androgens and supports the adverse cardiovascular effect of androgenic exposure in this highly selected group of women.

Factor analysis of metabolic syndrome components in obese women

BACKGROUND AND AIM

Factor analysis is a multivariate correlation technique that is frequently employed to characterise the clustering of intercorrelated abnormalities, which underlie the metabolic syndrome in cohorts of individuals with different characteristics. To our knowledge, it has never been used to identify the components of this syndrome in obese subjects. The purpose of this study was to use factor analysis to investigate the clustering of features, which characterise the metabolic syndrome, in a cohort of 552 obese women aged 18-83 years (mean body mass index: 43.0 kg/m(2)+/-5.7 SD).

METHODS AND RESULTS

Principal component analysis reduced ten correlated physiological variables, to four uncorrelated factors that explained 72.2% of the variance in the original parameters. These factors were interpreted as: (1) an insulin resistance factor, with positive loading of fasting serum insulin and homeostatic model assessment of insulin resistance; (2) a metabolic glucose/lipid factor, with positive loading of fasting plasma glucose, triglycerides, waist-to-hip ratio, and inverse loading of high density lipoprotein cholesterol; (3) a body mass factor, with positive loading of body mass and waist circumference; and (4) a blood pressure factor, with positive loading of systolic and diastolic blood pressure.

CONCLUSION

The identification of four independent factors is consistent with previous findings among samples of different populations and may also support, in obese women, the hypothesis that multiple physiological determinants are responsible for the abnormalities underlying the metabolic syndrome. Nonetheless, findings in this cohort of obese women suggest that the absolute degree of adiposity is not correlated with any tested component of the metabolic syndrome, but that the relative fat distribution is highly correlated with the development of hyperglycaemic and dyslipidaemic phenomena. Furthermore, insulin resistance appears to be a major factor in obese individuals, independent of other metabolic and anthropometic abnormalities.

Severity of metabolic syndrome unfavorably influences oxidative stress and fatty acid metabolism in men

Metabolic syndrome (MS) is defined by the clustering of several components (MSC), which include abdominal fat accumulation, impaired glucose homeostasis, hypertriglyceridemia, lowered high-density lipoprotein cholesterol, increased blood pressure, and hyperuricemia. Metabolic syndrome is also accompanied by increased oxidative stress and inflammation as well as by altered composition of esterified fatty acids (FA). Therefore, we have investigated 210 men (categorized into six groups with increasing number of MSC) to find trends in the extent of oxidative stress, FA pattern and frequency of pathological alleles of the selected candidate genes for lipid metabolism. Increasing number of MSC was connected with the raised serum glucose and insulin, increased concentrations of conjugated dienes in low-density lipoprotein (all p < 0.0001), and high frequency of e2 and e4 alleles of the apolipoprotein E gene (p < 0.005). However, the last significance was lost after the adjustment for age. The incidence of 54Thr allele for intestinal isoform of the fatty acid-binding protein (FABP-2) gene was comparable in all groups. The most important findings were the raised content of saturated FA and the increased activities of Delta9 and Delta6 desaturases (all p < 0.0001), and the decreased content of polyunsaturated FA n-6 family and the decreased activity of Delta5 desaturase (both p < 0.001) in connection with increasing number of MSC. In conclusion, the severity of MS is connected with the progression of oxidative stress and the unfavorable changes in the FA composition. These changes are independent of the studied gene polymorphisms.

Plasma uric acid level and risk for incident hypertension among men

Several studies have found that uric acid (UA) level is associated with an increased risk for hypertension, but the association could be confounded by metabolic factors that were not included in these previous studies. UA level and risk for incident hypertension was examined prospectively among men who participated in the Health Professionals' Follow-up Study. From among men without hypertension at the time blood was collected, 750 participants who developed hypertension during the subsequent 8 yr and 750 age-matched controls were selected. In addition to adjustment for standard hypertension risk factors and renal function, adjustments controlled for fasting insulin, triglyceride, and cholesterol levels. The mean age of participants was 61 yr, and mean plasma UA level was 6.0 mg/dl (SD 1.25 mg/dl). The multivariable relative risk (RR) for a 1-SD increase in UA was 1.02 (95% confidence interval [CI]0.87 to 1.18); the RR comparing the highest with lowest quartile of UA was 1.08 (95% CI 0.71 to 1.63). The multivariable RR associated with a 1-SD increase in UA was 1.38 (95% CI 1.05 to 1.81) for men aged <60 yr and 0.90 (95% CI 0.74 to 1.10) for men >or=60 yr (P = 0.04 for interaction). However, further adjustment for fasting insulin, triglyceride, and cholesterol levels attenuated the results (RR for men <60 yr 1.24; 95% CI 0.93 to 1.66). In conclusion, no independent association between UA level and risk for incident hypertension was found among older men.

Assessment of metabolic profile in a clinical setting

PURPOSE OF REVIEW

The metabolic syndrome, a clustering of abnormalities such as hyperglycemia, insulin resistance, hypertension, dyslipidemia, and central obesity, is a principal risk factor for cardiovascular disease, the leading cause of morbidity and mortality in the Western world. There are several definitions of the metabolic syndrome, all aiming at including as many persons at risk as possible. The assessment and, hence, the identification of such persons in a clinical setting is of utmost importance.

RECENT FINDINGS

Clinicians should document the presence of central obesity, assessed by waist circumference measurement or determination of body composition using dual X-ray absorptiometry or measurement of visceral fat using computed tomography or magnetic resonance imaging. The presence of dyslipidemia, insulin resistance, and arterial hypertension constitutes the full profile of the metabolic syndrome. Nevertheless, elevated uric acid levels or presence of nonalcoholic fatty liver, or the diagnosis of the polycystic ovary syndrome in women of reproductive age, all are reflected in high risk of later occurrence of the full metabolic syndrome and atherosclerotic cardiovascular disease.

SUMMARY

Although no unified definition for the metabolic syndrome exists, it is important to identify persons at risk, in order to reduce the resultant high morbidity and mortality rates.