A global perspective on the status of clinical metabolomics in laboratory medicine - a survey by the IFCC metabolomics working group.

OBJECTIVES: Metabolomics aims for comprehensive characterization and measurement of small molecule metabolites (<1700 Da) in complex biological matrices. This study sought to assess the current understanding and usage of metabolomics in laboratory medicine globally and evaluate the perception of its promise and future implementation. METHODS: A survey was conducted by the IFCC metabolomics working group that queried 400 professionals from 79 countries. Participants provided insights into their experience levels, knowledge, and usage of metabolomics approaches, along with detailing the applications and methodologies employed. RESULTS: Findings revealed a varying level of experience among respondents, with varying degrees of familiarity and utilization of metabolomics techniques. Targeted approaches dominated the field, particularly liquid chromatography coupled to a triple quadrupole mass spectrometer, with untargeted methods also receiving significant usage. Applications spanned clinical research, epidemiological studies, clinical diagnostics, patient monitoring, and prognostics across various medical domains, including metabolic diseases, endocrinology, oncology, cardiometabolic risk, neurodegeneration and clinical toxicology. CONCLUSIONS: Despite optimism for the future of clinical metabolomics, challenges such as technical complexity, standardization issues, and financial constraints remain significant hurdles. The study underscores the promising yet intricate landscape of metabolomics in clinical practice, emphasizing the need for continued efforts to overcome barriers and realize its full potential in patient care and precision medicine.

Multimarkers of metabolic malnutrition and inflammation and their association with mortality risk in cardiac catheterisation patients: a prospective, longitudinal, observational, cohort study.

BACKGROUND: Complex and incompletely understood metabolic dysfunction associated with inflammation and protein-energy wasting contribute to the increased mortality risk of older patients and those with chronic organ diseases affected by cachexia, sarcopenia, malnutrition, and frailty. However, these wasting syndromes have uncertain relevance for patients with cardiovascular disease or people at lower risk. Studies are hampered by imperfect objective clinical assessment tools for these intertwined metabolic malnutrition and inflammation syndromes. We aimed to assess, in two independent cohorts of patients who underwent cardiac catheterisation, the mortality risk associated with the metabolic vulnerability index (MVX), a multimarker derived from six simultaneously measured serum biomarkers plausibly linked to these dysmetabolic syndromes. METHODS: In this prospective, longitudinal, observational study, we included patients aged ≥18 years recruited into the CATHGEN biorepository (Jan 2, 2001, to Dec 30, 2011) and the Intermountain Heart Collaborative Study (Sept 12, 2000, to Sept 21, 2006) who underwent coronary angiography and had clinical nuclear magnetic resonance metabolomic profiling done on frozen plasma obtained at catheterisation. We aggregated six mortality risk biomarkers (GlycA, small HDL, valine, leucine, isoleucine, and citrate concentrations) into sex-specific MVX multimarker scores using coefficients from predictive models for all-cause mortality in the CATHGEN cohort. We assessed associations of biomarkers and MVX with mortality in both cohorts using Cox proportional hazards models adjusted for 15 clinical covariates. FINDINGS: We included 5876 participants from the CATHGEN biorepository and 2888 from the Intermountain Heart study. Median follow-up was 6·2 years (IQR 4·4-8·9) in CATHGEN and 8·2 years (6·9-9·2) in the Intermountain Heart study. The six nuclear magnetic resonance biomarkers and MVX made strong, independent contributions to 5-year mortality risk prediction in both cohorts (hazard ratio 2·18 [95% CI 2·03-2·34] in the CATHGEN cohort and 1·67 [1·50-1·87] in the Intermountain Heart cohort). CATHGEN subgroup analyses showed similar MVX associations in men and women, older and younger individuals, for death from cardiovascular or non-cardiovascular causes, and in patients with or without multiple comorbidities. INTERPRETATION: MVX made a dominant contribution to mortality prediction in patients with cardiovascular disease and in low-risk subgroups without pre-existing disease, suggesting that metabolic malnutrition-inflammation syndromes might have a more universal role in survival than previously thought. FUNDING: Labcorp.

Causal analysis identifies small HDL particles and physical activity as key determinants of longevity of older adults.

BACKGROUND: The hard endpoint of death is one of the most significant outcomes in both clinical practice and research settings. Our goal was to discover direct causes of longevity from medically accessible data. METHODS: Using a framework that combines local causal discovery algorithms with discovery of maximally predictive and compact feature sets (the "Markov boundaries" of the response) and equivalence classes, we examined 186 variables and their relationships with survival over 27 years in 1507 participants, aged ≥71 years, of the longitudinal, community-based D-EPESE study. FINDINGS: As few as 8-15 variables predicted longevity at 2-, 5- and 10-years with predictive performance (area under receiver operator characteristic curve) of 0·76 (95% CIs 0·69, 0·83), 0·76 (0·72, 0·81) and 0·66 (0·61, 0·71), respectively. Numbers of small high-density lipoprotein particles, younger age, and fewer pack years of cigarette smoking were the strongest determinants of longevity at 2-, 5- and 10-years, respectively. Physical function was a prominent predictor of longevity at all time horizons. Age and cognitive function contributed to predictions at 5 and 10 years. Age was not among the local 2-year prediction variables (although significant in univariable analysis), thus establishing that age is not a direct cause of 2-year longevity in the context of measured factors in our data that determine longevity. INTERPRETATION: The discoveries in this study proceed from causal data science analyses of deep clinical and molecular phenotyping data in a community-based cohort of older adults with known lifespan. FUNDING: NIH/NIA R01AG054840, R01AG12765, and P30-AG028716, NIH/NIA Contract N01-AG-12102 and NCRR 1UL1TR002494-01.

High-Density Lipoprotein and Long-Term Incidence and Progression of Aortic Valve Calcification: The Multi-Ethnic Study of Atherosclerosis.

BACKGROUND: Aortic valve calcification (AVC) shares pathological features with atherosclerosis. Lipoprotein components have been detected in aortic valve tissue, including HDL (high-density lipoprotein). HDL measures have inverse associations with cardiovascular disease, but relationships with long-term AVC progression are unclear. We investigated associations of HDL cholesterol, HDL-particle number and size, apoC3-defined HDL subtypes, and, secondarily, CETP (cholesteryl ester transfer protein) mass and activity, with long-term incidence and progression of AVC. METHODS: We used linear mixed-effects models to evaluate the associations of baseline HDL indices with AVC. AVC was quantified by Agatston scoring of up to 3 serial computed tomography scans over a median of 8.9 (maximum 11.2) years of follow-up in the Multi-Ethnic Study of Atherosclerosis (n=6784). RESULTS: After adjustment, higher concentrations of HDL-C (high-density lipoprotein cholesterol), HDL-P (HDL particles), large HDL-P, and apoC3-lacking HDL-C were significantly associated with lower incidence/progression of AVC. Neither small or medium HDL-P nor apoC3-containing HDL-C was significantly associated with AVC incidence/progression. When included together, a significant association was observed only for HDL-C, but not for HDL-P. Secondary analyses showed an inverse relationship between CETP mass, but not activity, and AVC incidence/progression. In exploratory assessments, inverse associations for HDL-C, HDL-P, large HDL-P, and apoC3-lacking HDL with AVC incidence/progression were more pronounced for older, male, and White participants. ApoC3-containing HDL-C only showed a positive association with AVC in these subgroups. CONCLUSIONS: In a multiethnic population, HDL-C, HDL-P, large HDL-P, and apoC3-lacking HDL-C were inversely associated with long-term incidence and progression of AVC. Further investigation of HDL composition and mechanisms could be useful in understanding pathways that slow AVC.

Higher Soluble CD163 in Blood Is Associated With Significant Depression Symptoms in Men With HIV.

BACKGROUND: People with HIV (PWH) are more likely to experience depression, a highly morbid disease. More evidence is needed to better understand mechanisms of depression in PWH. We evaluated a panel of blood biomarkers in relation to depression symptoms in the Multicenter AIDS Cohort Study (MACS). SETTING: Four sites in the United States. METHODS: A cross-sectional analysis was performed within the MACS, a prospective study of cisgender men with and without HIV. Depression was assessed with the Center for Epidemiological Studies-Depression Scale, and six blood biomarkers were measured: GlycA, high sensitivity C-reactive protein (CRP), interleukin-6, CCL2, soluble CD14 (sCD14), and soluble CD163 (sCD163). Using univariable and multivariable logistic regression, the biomarkers and other factors were evaluated in relation to significant depression symptoms (SDS) by Center for Epidemiological Studies-Depression score ≥16. RESULTS: 784 men were analyzed; most of whom (63%) were PWH. PWH were more likely to have SDS (32% vs. 21%). In univariable analysis, higher GlycA, CRP, and sCD163 concentrations were associated with SDS. In multivariable analysis, however, only higher sCD163 concentration was associated with SDS (odds ratio = 2.30, 95% CI = 1.11 to 4.76). This relationship was driven by the PWH group (odds ratio = 2.72, 95% CI = 1.12 to 6.58) and remained significant when controlling for antidepressant use. Lack of college education was also associated with SDS. CONCLUSIONS: Higher sCD163, a marker of macrophage activation, was significantly associated with significant depression symptoms in the MACS. Further research on this biomarker and macrophage activation in general is warranted to better understand and treat depression in PWH.

Association of beta-hydroxybutyrate with development of heart failure: Sex differences in a Dutch population cohort.

BACKGROUND: In the failing heart, energy metabolism is shifted towards increased ketone body oxidation. Nevertheless, the association of beta-hydroxybutyrate (ß-OHB) with development of heart failure (HF) remains unclear. We investigated the association between plasma ß-OHB and the risk of HF in a prospective population-based cohort. DESIGN: Plasma ß-OHB concentrations were measured in 6134 participants of the PREVEND study. Risk of incident HF with reduced (HFrEF) or preserved (HFpEF) ejection fraction was estimated using multivariable-adjusted Cox regression models. RESULTS: During median follow-up for 8.2 years, 227 subjects were diagnosed with HF (137 with HFrEF; 90 with HFpEF). Cox regression analyses revealed a significant association of higher ß-OHB concentrations with incident HF (HR per 1 standard deviation increase, 1.40 (95% CI: 1.21-1.63; P < .001), which was largely attributable to HFrEF. In women, the hazard ratio (HR) for HFrEF per 1 standard deviation increase in ß-OHB was 1.73 (95% confidence interval (CI): 1.17-2.56, P = .005) in age, BMI, type 2 diabetes, hypertension, myocardial infarction, smoking, alcohol consumption, total cholesterol, HDL-C, triglycerides, glucose, eGFR and UAE adjusted analysis. In men, in the same fully adjusted analysis, the HR was 1.14 (CI: 0.86-1.53, P = .36) (P < .01 for sex interaction). In N-terminal pro-brain natriuretic peptide (NT-proBNP)-stratified analysis, the age-adjusted association with HF was significant in women with higher NT-proBNP levels (P = .008). CONCLUSIONS: This prospective study suggests that high plasma concentrations of ß-OHB are associated with an increased risk of HFrEF, particularly in women. The mechanisms responsible for the sex differences of this association warrant further study.

Association of High-Density Lipoprotein Particles and High-Density Lipoprotein Apolipoprotein C-III Content With Cardiovascular Disease Risk According to Kidney Function: The Multi-Ethnic Study of Atherosclerosis.

Background Chronic kidney disease is associated with structural and compositional abnormalities in high-density lipoprotein particles (HDLp). We examined associations of HDLp size, particle subfractions, and apolipoprotein C-III content with incident cardiovascular disease (CVD) events across categories of estimated glomerular filtration rate (eGFR). Methods and Results Analyses included 6699 participants in MESA (Multi-Ethnic Study of Atherosclerosis) with measurements of HDLp and 5723 participants with measurements of HDL apolipoprotein C-III. Cox-regression methods were used to evaluate associations between HDLp and apolipoproteins with CVD events. Larger HDLp size was associated with lower CVD risk in participants with lower eGFR: hazard ratio (95% CI) per SD higher mean HDL size was 1.00 (0.90-1.11) in eGFR ≥60 mL/min per 1.73 m2, 0.65 (0.48-0.86) in eGFR 45 to 59 mL/min per 1.73 m2, and 0.48 (0.25-0.93) in eGFR <45 mL/min per 1.73 m2 (P for interaction=0.05). Associations of HDLp subfractions with CVD varied significantly by eGFR (P for interaction=0.04), with significant inverse associations between higher concentrations of large HDLp and CVD events across categories of kidney function, but nonsignificant results for small HDLp. Only HDLp without apolipoprotein C-III was associated with lower risk of CVD events, with seemingly (albeit not statistically significant) stronger associations among participants with lower eGFR (P for interaction=0.19). Conclusions HDL particles of larger size and higher concentrations of large HDL and of HDL without apolipoprotein C-III were associated with lower CVD risk, with risk estimates seemingly stronger among participants with lower eGFR. Future larger studies are needed to corroborate these findings.

A Pathophysiologic Approach Combining Genetics and Insulin Resistance to Predict the Severity of Nonalcoholic Fatty Liver Disease.

Nonalcoholic fatty liver disease (NAFLD) is a complex disease dictated by both genetic and environmental factors. While insulin resistance (IR) is a key pathogenic driver, two common genetic variants in patatin-like phospholipase domain containing 3 (PNPLA3) and transmembrane 6 superfamily member 2 (TM6SF2) also impart significant risk for disease progression. Traditional approaches to NAFLD risk stratification rely on biomarkers of fibrosis, an end result of disease progression. We hypothesized that by combining genetics and a novel measurement for IR we could predict disease progression by the NAFLD activity score (NAS) and histologic presence of significant fibrosis. A total of 177 patients with biopsy-proven NAFLD were enrolled in this cross-sectional study. PNPLA3 I148M and TM6SF2 E167K genotypes were determined by TaqMan assays. The enhanced lipoprotein IR index (eLP-IR) was calculated from serum biomarkers using nuclear magnetic resonance (NMR) spectroscopy. Multivariate regression models were used to study the relationships between genetics, IR, and histologic features of NAFLD. In the multivariate analysis, the eLP-IR was strongly associated with histologic features of NAFLD activity and hepatic fibrosis (P < 0.001 to 0.02) after adjustment for potential confounders. PNPLA3 148M and TM6SF2 E167K genotypes were significantly associated with steatosis (P = 0.003 and P = 0.02, respectively). A combination of the eLP-IR and genetic score was able to predict the presence of NAS ≥3 with an area under the receiver operating characteristic curve (AUROC) of 0.74. Adding age to this model predicted stages 3-4 liver fibrosis with an AUROC of 0.82. Conclusion: This proof-of-concept study supports the hypothesis that genetics and IR are major determinants of NAFLD severity and demonstrates the feasibility of a new risk stratification paradigm using exclusively pathogenic factors.

Associations of ideal cardiovascular health with GlycA, a novel inflammatory marker: The Multi-Ethnic Study of Atherosclerosis.

BACKGROUND: Unhealthy lifestyles and inflammation contribute to cardiovascular disease (CVD). GlycA is a novel biomarker of systemic inflammation representing post-translational glycosylation of acute phase reactants and associated with increased clinical CVD risk. HYPOTHESIS: We hypothesized that ideal cardiovascular health (CVH), as assessed by (higher) Life's Simple 7 (LS7) scores, would be associated with lower GlycA levels among individuals free of CVD in a multiethnic community-based population. METHODS: This was a cross-sectional study of 6479 Multi-Ethnic Study of Atherosclerosis participants [53% women; mean age 62 ± 10 years] with GlycA levels measured at baseline by nuclear magnetic resonance spectroscopy. The LS7 metrics (smoking, physical activity, diet, body mass index, blood pressure, cholesterol, and glucose) were each scored as ideal (2), moderate (1), or poor (0). Total scores were summed and categorized as optimal (12-14), average (8-11), and inadequate (0-7). Linear regression assessed percent difference in GlycA by LS7 scores, after adjusting for age, sex, ethnicity, education, income, family history of CVD, and other inflammatory biomarkers. RESULTS: GlycA levels were 403.4 ± 63.1, 374.4 ± 59.2, and 350.3 ± 56.2 micromoles per liter (µmol/L) for inadequate, average, and optimal CVH, respectively (P-trend <0.001). After multivariable adjustment, GlycA remained independently and inversely associated with CVH categories, with a lower mean GlycA level of 5 µmol/L (95% confidence interval 4.5-5.8) for each one unit increment in LS7 score. CONCLUSIONS: Among this group of ethnically diverse individuals without CVD, suboptimal CVH is associated with higher GlycA levels, independent of traditional inflammatory biomarkers. Strategies aimed at improving CVH might reduce GlycA, which could be a marker of reduced risk of future CVD events.

Association Between Smoking and Serum GlycA and High-Sensitivity C-Reactive Protein Levels: The Multi-Ethnic Study of Atherosclerosis (MESA) and Brazilian Longitudinal Study of Adult Health (ELSA-Brasil).

BACKGROUND: Inflammation is suggested to be a central feature of atherosclerosis, particularly among smokers. We studied whether inflammatory biomarkers GlycA and high-sensitivity C-reactive protein are associated with cigarette smoking. METHODS AND RESULTS: A total of 11 509 participants, 6774 from the MESA (Multi-Ethnic Study of Atherosclerosis) and 4735 from ELSA-Brasil (The Brazilian Longitudinal Study of Adult Health) were included. We evaluated the cross-sectional association between multiple measures of smoking behavior and the inflammatory biomarkers, GlycA and high-sensitivity C-reactive protein, using regression models adjusted for demographic, anthropometric, and clinical characteristics. Participants were 57.7±11.1 years old and 46.4% were men. Never, former, and current smokers comprised 51.7%, 34.0%, and 14.3% of the population, respectively. Multivariable-adjusted mean absolute difference in GlycA levels (µmol/L) with 95% confidence interval (CI) were higher for former (4.1, 95% CI, 1.7-6.6 µmol/L) and current smokers (19.9, 95% CI, 16.6-23.2 µmol/L), compared with never smokers. Each 5-unit increase in pack-years of smoking was associated with higher GlycA levels among former (0.7, 95% CI, 0.3-1.1 µmol/L) and current smokers (1.6, 95% CI, 0.8-2.4 µmol/L). Among former smokers, each 5-year increase in time since quitting smoking was associated with lower GlycA levels (-1.6, 95% CI, -2.4 to -0.8 µmol/L) and each 10-unit increase in number of cigarettes/day was associated with higher GlycA among current smokers (2.8, 95% CI, 0.5-5.2 µmol/L). There were similar significant associations between all measures of smoking behavior, and both log-transformed GlycA and high-sensitivity C-reactive protein. CONCLUSIONS: Acute and chronic exposure to tobacco smoking is associated with inflammation, as quantified by both GlycA and high-sensitivity C-reactive protein. These biomarkers may have utility for the study and regulation of novel and traditional tobacco products.

Inflammatory glycoproteins in cardiometabolic disorders, autoimmune diseases and cancer.

The physiological function initially attributed to the oligosaccharide moieties or glycans on inflammatory glycoproteins was to improve protein stability. However, it is now clear that glycans play a prominent role in glycoprotein structure and function and in some cases contribute to disease states. In fact, glycan processing contributes to pathogenicity not only in autoimmune disorders but also in atherosclerotic cardiovascular disease, diabetes and malignancy. While most clinical laboratory tests measure circulating levels of inflammatory proteins, newly developed diagnostic and prognostic tests are harvesting the information that can be gleaned by measuring the amount or structure of the attached glycans, which may be unique to individuals as well as various diseases. As such, these newer glycan-based tests may provide future means for more personalized approaches to patient stratification and improved patient care. Here we will discuss recent progress in high-throughput laboratory methods for glycomics (i.e. the study of glycan structures) and glycoprotein quantification by methods such as mass spectrometry and nuclear magnetic resonance spectroscopy. We will also review the clinical utility of glycoprotein and glycan measurements in the prediction of common low-grade inflammatory disorders including cardiovascular disease, diabetes and cancer, as well as for monitoring autoimmune disease activity.

Steatohepatitis and liver fibrosis are predicted by the characteristics of very low density lipoprotein in nonalcoholic fatty liver disease.

BACKGROUND & AIMS: A major challenge in the management of nonalcoholic fatty liver disease (NAFLD) is to identify patients with nonalcoholic steatohepatitis (NASH) and early liver fibrosis. The progression of NAFLD is accompanied by distinctive changes in very low density lipoprotein (VLDL), a lipoprotein particle produced exclusively in the liver. Herein, we sought to determine the characteristics of VLDL profiles associated with NASH and liver fibrosis. METHODS: We evaluated VLDL profiles of 128 patients from a single centre NAFLD registry, and examined VLDL size, total and subclass VLDL concentrations in relation to NAFLD activity score (NAS), steatohepatitis and liver fibrosis as determined by liver biopsy. RESULTS: A near linear relationship was observed between mean VLDL particle size and NAFLD activity score (NAS). In multivariate models, VLDL particle size was significantly associated with both NAS and NASH, after adjustment for BMI and diabetes. A decrease in small VLDL particle concentration was associated with more advanced liver fibrosis. In receiver operative characteristic analyses, mean VLDL size performed similarly to cytokeratin 18 in predicting NASH, whereas small VLDL particle concentration had similar performance to NAFLD fibrosis score in predicting stage 2 or above liver fibrosis. CONCLUSIONS: The increase in mean VLDL size in NASH and decrease in small VLDL particle concentration in liver fibrosis likely reflect changes in the number and state of hepatocytes associated with NASH and fibrosis. In addition to its value in risk stratification of cardiovascular diseases, circulating VLDL profile may provide information for the staging of NAFLD disease severity.

GlycA, a Pro-Inflammatory Glycoprotein Biomarker, and Incident Cardiovascular Disease: Relationship with C-Reactive Protein and Renal Function.

OBJECTIVE: GlycA is a novel nuclear magnetic resonance spectroscopy-measured biomarker of systemic inflammation. We determined whether GlycA is associated with incident cardiovascular disease (CVD) in men and women, examined whether this association with CVD is modified by renal function, and compared this association with high sensitivity C-reactive protein (hsCRP). RESEARCH DESIGN AND METHODS: A prospective cohort study was performed among 4,759 subjects (PREVEND study) without a history of CVD and cancer. Incident CVD was defined as the combined endpoint of cardiovascular morbidity and mortality. Cox regression analyses were used to examine associations of baseline GlycA and hsCRP with CVD. RESULTS: 298 first CVD events occurred during a median follow-up of 8.5 years. After adjustment for clinical and lipid measures the hazard ratio (HR) for CVD risk in the highest GlycA quartile was 1.58 (95% CI, 1.05-2.37, P for trend = 0.004). This association was similar after further adjustment for renal function (estimated glomerular filtration rate and urinary albumin excretion). After additional adjustment for hsCRP, GlycA was still associated with incident CVD (HR: 1.16 per SD change (95% CI, 1.01-1.33), P = 0.04). Similar results were obtained for hsCRP (HR per SD change after adjustment for GlycA: 1.17 (95% CI 1.17 (95% CI, 1.01-3.60), P = 0.04). CVD risk was highest in subjects with simultaneously higher GlycA and hsCRP (fully adjusted HR: 1.79 (95% CI, 1.31-2.46), P<0.001). CONCLUSION: GlycA is associated with CVD risk in men and women, independent of renal function. The association of GlycA with incident CVD is as strong as that of hsCRP.

Increase in the Inflammatory Marker GlycA over 13 Years in Young Adults Is Associated with Poorer Cognitive Function in Midlife.

BACKGROUND: Inflammatory markers are elevated in patients with dementia. Evidence for an association between inflammation and cognitive function in dementia-free individuals is sparse, inconsistent, and predominantly restricted to the elderly. Assessment of inflammatory markers in young adults as predictors of cognitive function in midlife, well before the onset of overt dementia, is lacking. Furthermore, rarely has the relation with longitudinal change in inflammatory markers been examined. OBJECTIVE: To examine the association of the inflammatory markers C-reactive protein (CRP), fibrinogen, white blood cell count (WBC) and GlycA, a novel NMR-determined biomarker of systemic inflammation, measured in young adulthood and of GlycA change over 13 years follow-up with cognitive function in midlife. METHODS: 507 participants of the Jerusalem Lipid Research Clinic (LRC) study were assessed at 3 time points over 18-22 years. First, the inflammatory variables GlycA, CRP, fibrinogen, and WBC were measured in blood samples drawn at ages 28-32. Then, in blood samples drawn a mean 13 years later (range, 12-16 years) at ages 41-46, GlycA was again measured (in 484 individuals). Subsequently at ages 48-52, on average 7 years later, global cognitive function and its five specific component domains were assessed with a NeuroTrax computerized test battery. Multiple regression and multivariable logistic models were applied. RESULTS: Inverse unadjusted associations were shown for baseline levels and longitudinal change in inflammatory markers and measures of cognition. Multiple regression models were adjusted for age at cognitive assessment, sex, socio-demographic characteristics, baseline measures of leisure-time vigorous activity, smoking status and body mass index (BMI) at ages 28-32, change in smoking status and BMI between ages 28-32 and 41-46, and depression assessed at the time of cognitive testing. The highest quintile of GlycA change, but not the baseline inflammation measures, was inversely related to global cognition (standardized ß = -.109, p = .011) as well as to the information processing speed and memory domains (standardized ß = -.124, p = .008 and-.117, p = .014, respectively). The multivariable-adjusted odds ratio for low ranked global cognitive function (lowest fifth) comparing the extreme quintiles of GlycA change was 4.8 (95%CI, 1.7-13.5, p = .003; p for trend = .031). CONCLUSIONS: In this longitudinal study of a novel systemic inflammatory marker in a population-based cohort of young adults, GlycA increase over 13 years, but not baseline measures of inflammation, was associated with poorer cognitive function in midlife.

A novel protein glycan biomarker and LCAT activity in metabolic syndrome.

BACKGROUND: The cholesterol-esterifying enzyme, lecithin:cholesterol acyltransferase (LCAT), is instrumental in high-density lipoprotein (HDL) remodelling. LCAT may also modify oxidative and inflammatory processes, as supported by an inverse relationship with HDL antioxidative functionality and a positive relationship with high-sensitivity C-reactive protein (hsCRP). GlycA is a recently developed proton nuclear magnetic resonance (NMR) spectroscopy-measured biomarker of inflammation whose signal originates from a subset of N-acetylglucosamine residues on the most abundant glycosylated acute-phase proteins. Plasma GlycA correlates positively with hsCRP and may predict cardiovascular disease even independent of hsCRP. Here, we tested the extent to which plasma GlycA is elevated in metabolic syndrome (MetS), and determined its relationship with LCAT activity. MATERIALS AND METHODS: Plasma GlycA, hsCRP, serum amyloid A (SAA), tumour necrosis factor-α (TNF-α) and LCAT activity were measured in 58 subjects with MetS (including 46 subjects with type 2 diabetes mellitus (T2DM)) and in 45 nondiabetic subjects without MetS. RESULTS: Plasma GlycA was higher in MetS coinciding with higher hsCRP and LCAT activity (P < 0.01 for each). In all subjects combined, GlycA was correlated positively with hsCRP, SAA and LCAT activity (P < 0.001 for each), but not with TNF-α. Age- and sex-adjusted multivariable linear regression analysis revealed that GlycA was positively associated with LCAT activity (P = 0.029), independent of the presence of MetS, T2DM, hsCRP and SAA. GlycA was unrelated to diabetes status. CONCLUSION: A pro-inflammatory glycoprotein biomarker, GlycA, is higher in MetS. Higher plasma levels of this glycoprotein biomarker relate to increased LCAT activity in the setting of MetS.

Lipoprotein particle size and concentration by nuclear magnetic resonance and incident type 2 diabetes in women.

OBJECTIVE: Diabetic dyslipoproteinemia is characterized by low HDL cholesterol and high triglycerides. We examined the association of lipoprotein particle size and concentration measured by nuclear magnetic resonance (NMR) spectroscopy with clinical type 2 diabetes. RESEARCH DESIGN AND METHODS: This was a prospective study of 26,836 initially healthy women followed for 13 years for incident type 2 diabetes (n = 1,687). Baseline lipids were measured directly and lipoprotein size and concentration by NMR. Cox regression models included nonlipid risk factors (age, race, smoking, exercise, education, menopause, blood pressure, BMI, family history, A1C, and C-reactive protein). NMR lipoproteins were also examined after further adjusting for standard lipids. RESULTS: Incident diabetes was significantly associated with baseline HDL cholesterol, triglycerides, and NMR-measured size and concentration of LDL, IDL, HDL, and VLDL particles. The associations of these particles differed substantially by size. Small LDL(NMR) and small HDL(NMR) were positively associated with diabetes (quintile 5 vs. 1 [adjusted hazard ratios and 95% CIs], 4.04 [3.21-5.09] and 1.84 [1.54-2.19], respectively). By contrast, large LDL(NMR) and large HDL(NMR) were inversely associated (quintile 1 vs. 5, 2.50 [2.12-2.95] and 4.51 [3.68-5.52], respectively). For VLDL(NMR), large particles imparted higher risk than small particles (quintile 5 vs. 1, 3.11 [2.35-4.11] and 1.31 [1.10-1.55], respectively). Lipoprotein particle size remained significant after adjusting for standard lipids and nonlipid factors. CONCLUSIONS: In this prospective study of women, NMR lipoprotein size and concentrations were associated with incident type 2 diabetes and remained significant after adjustment for established risk factors, including HDL cholesterol and triglycerides.

Effects of exercise on lipoprotein particles in women with polycystic ovary syndrome.

PURPOSE: Women with polycystic ovary syndrome (PCOS) commonly have insulin resistance. Insulin resistance is associated with marked abnormalities of lipoprotein size and subclass particle concentration. The purpose of this study was to examine the effects of a moderate-intensity exercise program without weight loss on lipoprotein profiles in women with PCOS. METHODS: Thirty-seven sedentary PCOS women were randomized to either an 8- to 12-wk ramp-up followed by a 12-wk moderate-intensity exercise program (16-24 wk total, approximately 228 min x wk at 40-60% peak V x O2, n = 21) or control (no change in lifestyle, n = 16). PCOS was defined as or=8). Fasting lipoprotein profiles were obtained before and after the intervention. Nuclear magnetic resonance spectroscopy was used to quantify the following: average particle size, total and subclass concentrations of HDL, LDL, and VLDL particles, and calculated HDL cholesterol, triglycerides, and VLDL triglycerides. Wilcoxon exact rank sums tests were used to compare changes in these parameters in the exercise group relative to controls. RESULTS: Twenty women (8 exercisers, 12 controls) completed the study. Comparing exercisers to controls, significant changes were seen in concentrations of the following lipoprotein parameters that are associated with decreased insulin resistance: decreased large VLDL (P = 0.007), calculated triglycerides (P = 0.003), VLDL triglycerides (P = 0.003), and medium/small HDL (P = 0.031) and increased large HDL (P = 0.002) and average HDL size (P = 0.001). CONCLUSIONS: In this trial, moderate-intensity exercise without significant weight loss improved several components of the lipoprotein profiles of women with PCOS. These findings support the beneficial role of moderate exercise in this high-risk population.

High-density lipoprotein particle size and concentration and coronary risk.

BACKGROUND: High-density lipoprotein (HDL) cholesterol levels are inversely related to risk for coronary artery disease (CAD). Because HDL particles are heterogeneous in size and composition, they may be differentially associated with other cardiovascular risk factors and with cardiovascular risk. OBJECTIVE: To study the independent relationships of HDL size and particle concentration to risk for future CAD. DESIGN: Nested case-control study within the EPIC (European Prospective Investigation into Cancer and Nutrition)-Norfolk cohort; baseline survey between 1993 and 1997, follow-up until November 2003. SETTING: Norfolk, United Kingdom. PARTICIPANTS: Case patients were 822 apparently healthy men and women who developed CAD during follow-up. Control participants were 1401 participants who remained without CAD and were matched to case patients by sex, age, and enrollment time. MEASUREMENTS: First CAD event leading to either hospitalization or death. RESULTS: Nuclear magnetic resonance spectroscopy-measured HDL particle concentration (mean, 33.9 micromol/L [SD, 5] vs. 32.9 micromol/L [SD, 6]; P < 0.001) and HDL size (mean, 8.9 nm [SD, 0.5] vs. 8.8 nm [SD, 0.5]; P < 0.001), as well as gradient gel electrophoresis-measured HDL size (mean, 8.9 nm [SD, 0.4] vs. 8.8 nm [SD, 0.4]; P = 0.005) were lower in case patients than in control participants. High-density lipoprotein size and HDL particle concentration were only weakly correlated (r = 0.08, for those measured with nuclear magnetic resonance spectroscopy; r = 0.10, for those measured with gradient gel electrophoresis). High-density lipoprotein size was strongly associated with risk factors characteristic of the metabolic syndrome, including waist-to-hip ratio, triglyceride level, and apolipoprotein B level, whereas HDL particle concentration was not. Both HDL size and HDL particle concentration were independently associated with CAD risk. The association between HDL size and CAD risk was abolished on adjustment for apolipoprotein B and triglyceride levels (adjusted odds ratio, 1.00 [95% CI, 0.71 to 1.39] for top vs. bottom quartile), whereas HDL particle concentration remained independently associated with CAD risk (adjusted odds ratio, 0.50 [CI, 0.37 to 0.66]). LIMITATION: Measurements were performed in nonfasting blood samples, and residual confounding cannot be excluded. CONCLUSION: Both HDL size and HDL particle concentration were independently associated with other cardiovascular risk factors and with the risk for CAD. The relationship between HDL size and CAD risk was explained by markers associated with the metabolic syndrome, indicating that part of the relationship between HDL cholesterol and CAD risk is merely a reflection of this metabolic risk.

Lipoprotein particle concentrations may explain the absence of coronary protection in the women's health initiative hormone trials.

OBJECTIVE: The Women's Health Initiative randomized hormone trials unexpectedly demonstrated an increase in early coronary events. In an effort to explain this finding, we examined lipoprotein particle concentrations and their interactions with hormone therapy in a case-control substudy. METHODS AND RESULTS: We randomized 16 608 postmenopausal women with intact uterus to conjugated estrogens 0.625 mg with medroxyprogesterone acetate 2.5 mg daily or to placebo, and 10 739 women with prior hysterectomy to conjugated estrogens 0.625 mg daily or placebo, and measured lipoprotein subclasses by nuclear magnetic resonance spectroscopy at baseline and year 1 in 354 women with early coronary events and matched controls. Postmenopausal hormone therapy raised high-density lipoprotein cholesterol and particle concentration and reduced low-density lipoprotein cholesterol (LDL-C; all P<0.001 versus placebo). In contrast, neither unopposed estrogen nor estrogen with progestin lowered low-density lipoprotein particle concentration (LDL-P). CONCLUSIONS: Postmenopausal hormone therapy-induced reductions in LDL-C were not paralleled by favorable effects on LDL-P. This finding may account for the absence of coronary protection conferred by estrogen in the randomized hormone trials.

Atherogenic lipoprotein particle size and concentrations and the effect of pravastatin in children with familial hypercholesterolemia.

OBJECTIVE: To determine lipoprotein particle concentrations and size in children with familial hypercholesterolemia (FH) and investigate the effect of pravastatin therapy on these measures. STUDY DESIGN: Lipoprotein particle concentrations and sizes were examined by nuclear magnetic resonance (NMR) spectroscopy in 144 children with FH and 45 unaffected siblings. The effect of pravastatin therapy (20 to 40 mg) on lipoprotein particle concentration and size were compared with placebo after 1 year of treatment, using analysis of covariance. RESULTS: Compared with the unaffected siblings, the children with FH had significantly higher concentrations of very-low-density lipoprotein (VLDL) particles (115.6 nmol/L vs 51.2 nmol/L; P < .001) and low-density lipoprotein (LDL) particles (1726.8 nmol/L vs 955.3 nmol/L; P < .001), and lower concentrations of high-density lipoprotein (HDL) particles (23.2 micromol/L vs 26.9 micromol/L; P < .001). Compared with placebo, pravastatin therapy decreased the concentration of VLDL particles by 35.9 nmol/L (P < .001), of total LDL particles by 342.7 nmol/L (P < .001), of large LDL particles by 189.5 nmol/L (P < .001), and of small LDL particles by 156.2 nmol/L (P = .152), but increased the concentration of total HDL particles by 2.2 micromol/L (P < .001), of large HDL particles by 1.0 micromol/L (P = .006), and of medium HDL particles by 1.1 micromol/L (P = .003). VLDL particle size increased by 1.0 nm (P = .032). CONCLUSIONS: Compared with their healthy siblings, children with FH have an atherogenic lipoprotein profile based on their lipoprotein distribution and lipoprotein particle diameter. Pravastatin therapy can improve, but not fully restore, these lipoprotein abnormalities toward normal levels in these children.