GlycA, a marker of acute phase glycoproteins, and the risk of incident type 2 diabetes mellitus: PREVEND study

Genetic Support for a Causal Role of Insulin Resistance on Circulating Branched-Chain Amino Acids and Inflammation

OBJECTIVE

Insulin resistance has deleterious effects on cardiometabolic disease. We used Mendelian randomization analyses to clarify the causal relationships of insulin resistance (IR) on circulating blood-based metabolites to shed light on potential mediators of the IR to cardiometabolic disease relationship.

RESEARCH DESIGN AND METHODS

We used 53 single nucleotide polymorphisms associated with IR from a recent genome-wide association study (GWAS) to explore their effects on circulating lipids and metabolites. We used published summary-level data from two GWASs of European individuals; data on the exposure (IR) were obtained from meta-GWASs of 188,577 individuals, and data on the outcomes (58 metabolic measures assessed by nuclear magnetic resonance) were taken from a GWAS of 24,925 individuals.

RESULTS

One-SD genetically elevated IR (equivalent to 55% higher geometric mean of fasting insulin, 0.89 mmol/L higher triglycerides, and 0.46 mmol/L lower HDL cholesterol) was associated with higher concentrations of all branched-chain amino acids (BCAAs)-isoleucine (0.56 SD; 95% CI 0.43, 0.70), leucine (0.42 SD; 95% CI 0.28, 0.55), and valine (0.26 SD; 95% CI 0.12, 0.39)-as well as with higher glycoprotein acetyls (an inflammation marker) (0.47 SD; 95% CI 0.32, 0.62) (P < 0.0003 for each). Results were broadly consistent when using multiple sensitivity analyses to account for potential genetic pleiotropy.

CONCLUSIONS

We provide robust evidence that IR causally affects each individual BCAA and inflammation. Taken together with existing studies, this implies that BCAA metabolism lies on a causal pathway from adiposity and IR to type 2 diabetes.

Adiposity and Genetic Factors in Relation to Triglycerides and Triglyceride-Rich Lipoproteins in the Women's Genome Health Study

BACKGROUND

Previous results from Scandinavian cohorts have shown that obesity accentuates the effects of common genetic susceptibility variants on increased triglycerides (TG). Whether such interactions are present in the US population and further selective for particular TG-rich lipoprotein subfractions is unknown.

METHODS

We examined these questions using body mass index (BMI) and waist circumference (WC) among women of European ancestry from the Women's Genome Health Study (WGHS) (n = 21840 for BMI; n = 19313 for WC). A weighted genetic risk score (TG-wGRS) based on 40 published TG-associated single-nucleotide polymorphisms was calculated using published effect estimates.

RESULTS

Comparing overweight (BMI ≥ 25 kg/m²) and normal weight (BMI < 25 kg/m²) WGHS women, each unit increase of TG-wGRS was associated with TG increases of 1.013% and 1.011%, respectively, and this differential association was significant (P_interaction = 0.014). Metaanalyses combining results for WGHS BMI with the 4 Scandinavian cohorts (INTER99, HEALTH2006, GLACIER, MDC) (total n = 40026) yielded a more significant interaction (P_interaction = 0.001). Similarly, we observed differential association of the TG-wGRS with TG (P_interaction = 0.006) in strata of WC (<80 cm vs ≥80 cm). Metaanalysis with 2 additional cohorts reporting WC (INTER99 and HEALTH2006) (total n = 27834) was significant with consistent effects (P_interaction = 0.006). We also observed highly significant interactions of the TG-wGRS across the strata of BMI with very large, medium, and small TG-rich lipoprotein subfractions measured by nuclear magnetic resonance spectroscopy (all P_interactions < 0.0001). The differential effects were strongest for very large TG-rich lipoprotein.

CONCLUSIONS

Our results support the original findings and suggest that obese individuals may be more susceptible to aggregated genetic risk associated with common TG-raising alleles, with effects accentuated in the large TG-rich lipoprotein subfraction.

GlycA, a novel biomarker of systemic inflammation and cardiovascular disease risk

Background

GlycA is a novel spectroscopic marker of systemic inflammation with low intra-individual variability and other attributes favoring its clinical use in patients with chronic inflammatory and autoimmune diseases. GlycA is unique in its composite nature, reflecting both increased glycan complexity and circulating acute phase protein levels during local and systemic inflammation. Recent studies of GlycA from cross-sectional, observational and interventional studies have been highly informative, demonstrating that GlycA is elevated in acute and chronic inflammation, predicts death in healthy individuals and is associated with disease severity in patients with chronic inflammatory diseases such as rheumatoid arthritis, psoriasis and lupus. Moreover, following treatment with biological therapy in psoriasis, reduction in skin disease severity was accompanied by a decrease in GlycA levels and improvement in vascular inflammation.

Conclusions

Collectively, these findings suggest GlycA is a marker that tracks systemic inflammation and subclinical vascular inflammation. However, larger prospective studies and randomized trials are necessary in order to assess the impact of novel therapies on GlycA in patients with chronic inflammatory conditions, which may be concomitant with cardiovascular benefits.

Palestinian Arab ethnicity is associated with an adverse metabolic phenotype

Urban-dwelling Palestinians have been shown to have higher cardiovascular morbidity and mortality and prevalence of diabetes than urban Israelis. Inflammation is implicated in the etiology of these conditions. We hypothesized that increased inflammatory activation, manifested as increased GlycA, a novel biomarker of global inflammation, would be evident in Palestinians. We compared GlycA concentrations between Palestinians and Israelis and assessed the associations of GlycA with anthropometric, health behavioral and clinical variables in a sample of 1674 Palestinians and Israelis aged 25-74, residing in Jerusalem. The main outcome measure was GlycA concentration. GlycA was higher in Palestinians than Israelis (p<0.001). This finding persisted in young Palestinians with normal glucose tolerance. GlycA, total white blood cell count, the triglyceride to HDL-cholesterol ratio and small LDL-cholesterol particles were all significantly higher in Palestinians compared to Israelis across obesity and glucose tolerance categories. Palestinian women had greater GlycA compared to Israeli women and men of both ethnicities. GlycA as well as adverse cardiovascular biomarkers are all higher in Palestinian Arabs than Israeli Jews, even in young healthy adults. This propensity to inflammation may be a driver of the higher risk of cardiovascular disease, insulin resistance and diabetes observed in this population.

Metabolic profiling of gestational diabetes in obese women during pregnancy

AIMS/HYPOTHESIS

Antenatal obesity and associated gestational diabetes (GDM) are increasing worldwide. While pre-existing insulin resistance is implicated in GDM in obese women, the responsible metabolic pathways remain poorly described. Our aim was to compare metabolic profiles in blood of obese pregnant women with and without GDM 10 weeks prior to and at the time of diagnosis by OGTT.

METHODS

We investigated 646 women, of whom 198 developed GDM, in this prospective cohort study, a secondary analysis of UK Pregnancies Better Eating and Activity Trial (UPBEAT), a multicentre randomised controlled trial of a complex lifestyle intervention in obese pregnant women. Multivariate regression analyses adjusted for multiple testing, and accounting for appropriate confounders including study intervention, were performed to compare obese women with GDM with obese non-GDM women. We measured 163 analytes in serum, plasma or whole blood, including 147 from a targeted NMR metabolome, at time point 1 (mean gestational age 17 weeks 0 days) and time point 2 (mean gestational age 27 weeks 5 days, at time of OGTT) and compared them between groups.

RESULTS

Multiple significant differences were observed in women who developed GDM compared with women without GDM (false discovery rate corrected p values <0.05). Most were evident prior to diagnosis. Women with GDM demonstrated raised lipids and lipoprotein constituents in VLDL subclasses, greater triacylglycerol enrichment across lipoprotein particles, higher branched-chain and aromatic amino acids and different fatty acid, ketone body, adipokine, liver and inflammatory marker profiles compared with those without GDM.

CONCLUSIONS/INTERPRETATION

Among obese pregnant women, differences in metabolic profile, including exaggerated dyslipidaemia, are evident at least 10 weeks prior to a diagnosis of GDM in the late second trimester.

Dietary intake of fat and fibre according to reference values relates to higher gut microbiota richness in overweight pregnant women

The diet-microbiota-metabolism relationships during pregnancy are mostly unknown. We explored the effect of the habitual diet and adherence to the dietary reference values on gut microbiota composition and diversity. Further, the association of gut microbiota with serum lipidomics and low-grade inflammation was evaluated. Overweight and obese women (BMI 30·7 (sd 4·4) kg/m2, n 100) were studied at early pregnancy (≤17 weeks). Intakes of nutrients were calculated from 3-d food diaries. Faecal microbiota composition was analysed using 16S rRNA gene sequencing. Fasting serum lipidomic profiles were determined by NMR. High-sensitivity C-reactive protein, glycoprotein acetylation (GlycA) and lipopolysaccharide activity were used as markers for low-grade inflammation. The recommended dietary intake of fibre and fat was related to higher gut microbiota richness and lower abundance of Bacteroidaceae. Correlations were observed between gut microbiota richness and GlycA and between a few microbiota genera and serum lipoprotein particles. As a conclusion, adherence to the dietary reference intake of fat and fibre was associated with beneficial gut microbiota composition, which again contributed to lipidomic profile. Higher gut microbiota richness and nutrient intakes were linked to a lower level of low-grade inflammation marker GlycA. This finding offers novel insights and opportunities for dietary modification during pregnancy with potential of improving the health of the mother and the child.

Differential Associations of Inflammatory Markers With Insulin Sensitivity and Secretion: The Prospective METSIM Study

Context

Low-grade inflammation is involved in the development of type 2 diabetes and cardiovascular disease (CVD); however, prospective studies evaluating inflammatory markers as predictors of changes in insulin secretion and insulin sensitivity are lacking.

Objective

We investigated the associations of glycoprotein acetyls (GlycA), interleukin-1 receptor antagonist (IL-1RA), and high-sensitivity C-reactive protein (hs-CRP) with insulin secretion, insulin sensitivity, incident type 2 diabetes, hypertension, CVD events, and total mortality in the prospective Metabolic Syndrome in Men (METSIM) study.

Design

A prospective study.

Participants

The cross-sectional METSIM study included 8749 nondiabetic Finnish men aged 45 to 73 years, who had been randomly selected from the population register of Kuopio, Finland. A total of 5401 men participated in the 6.8-year follow-up study.

Main Outcome Measures

Changes in insulin secretion, insulin sensitivity, and cardiometabolic traits during the follow-up period and the incidence of type 2 diabetes, hypertension, CVD events, and total mortality.

Results

During the follow-up period, GlycA was associated with impaired insulin secretion, hyperglycemia, incident type 2 diabetes (hazard ratio, 1.37; 95% confidence interval, 1.29 to 1.46) and CVD (hazard ratio, 1.21; 95% confidence interval, 1.12 to 1.32). IL-1RA and hs-CRP were associated with adverse changes in insulin sensitivity and obesity-related traits and with total mortality (hazard ratio, 1.13; 95% confidence interval, 1.07 to 1.20; and hazard ratio, 1.08; 95% confidence interval, 1.04 to 1.11, respectively).

Conclusions

Inflammatory markers differentially predicted changes in insulin secretion and insulin sensitivity. GlycA predicted impaired insulin secretion, and IL-1RA and hs-CRP predicted changes in insulin sensitivity. Combining the three markers improved the prediction of disease outcomes, suggesting that they capture different aspects of low-grade inflammation.

Association of the Composite Inflammatory Biomarker GlycA, with Exercise-Induced Changes in Body Habitus in Men and Women with Prediabetes

GlycA is a new composite measure of systemic inflammation and a predictor of many inflammatory diseases. GlycA is the nuclear magnetic resonance spectroscopy-derived signal arising from glucosamine residues on acute-phase proteins. This study aimed to evaluate how exercise-based lifestyle interventions modulate GlycA in persons at risk for type 2 diabetes. GlycA, fitness, and body habitus were measured in 169 sedentary adults (45–75 years) with prediabetes randomly assigned to one of four six-month exercise-based lifestyle interventions. Interventions included exercise prescription based on the amount (energy expenditure (kcal/kg weight/week (KKW)) and intensity (%VO_2peak). The groups were (1) low-amount/moderate-intensity (10KKW/50%) exercise; (2) high-amount/moderate-intensity (16KKW/50%) exercise; (3) high-amount/vigorous-intensity (16KKW/75%) exercise; and (4) a Clinical Lifestyle (combined diet plus low-amount/moderate-intensity exercise) intervention. Six months of exercise training and/or diet-reduced GlycA (mean Δ: −6.8 ± 29.2 μmol/L; p = 0.006) and increased VO_2peak (mean Δ: 1.98 ± 2.6 mL/kg/min; p < 0.001). Further, visceral (mean Δ: −21.1 ± 36.6 cm²) and subcutaneous fat (mean Δ: −24.3 ± 41.0 cm²) were reduced, while liver density (mean Δ: +2.3 ± 6.5HU) increased, all p < 0.001. When including individuals in all four interventions, GlycA reductions were associated with reductions in visceral adiposity (p < 0.03). Exercise-based lifestyle interventions reduced GlycA concentrations through mechanisms related to exercise-induced modulations of visceral adiposity. This trial is registered with Clinical Trial Registration Number NCT00962962.

Increased intestinal permeability, measured by serum zonulin, is associated with metabolic risk markers in overweight pregnant women

BACKGROUND

Increased intestinal permeability with subsequent metabolic endotoxemia, i.e., elevated circulating levels of bacterial lipopolysaccharide, LPS, has been introduced as a novel initiator of obesity related metabolic disturbances in non-pregnant individuals. The objective was to investigate the extent to which intestinal permeability, measured by serum zonulin concentration, is related to metabolic endotoxemia and metabolic risk markers in overweight pregnant women.

METHODS

This was a cross-sectional study including 100 pregnant overweight women in early pregnancy. Serum zonulin was analyzed using ELISA, and markers for metabolic endotoxemia (LPS), inflammation (high-sensitive C-reactive protein and glycoprotein acetylation GlyA), glucose metabolism (fasting glucose and insulin), and lipid metabolism were measured.

RESULTS

Higher serum zonulin concentration associated positively with LPS (P=0.02), inflammatory markers (P<0.001), insulin (P<0.001), insulin resistance (P<0.001), and triglycerides (P=0.001), and negatively with insulin sensitivity (P=0.001) (ANOVA with Tukey's corrections or Kruskal-Wallis nonparametric test with Bonferroni correction for zonulin quartiles). All the observed associations were confirmed (P<0.015) in a linear regression model adjusted with potential confounding factors. Both LPS and GlycA showed positive relationship with insulin resistance, serum insulin, triglycerides, total and LDL-cholesterol and negative relationship with insulin sensitivity (P≤0.03) in the univariate linear regression. Positive relationship was also found between LPS and HDL-cholesterol (P=0.03).

CONCLUSIONS

Our findings suggest that increased serum zonulin concentration, i.e., increased intestinal permeability, contributes to metabolic endotoxemia, systemic inflammation, and insulin resistance in overweight pregnant women. By reinforcing intestinal barrier, it may be possible to manipulate maternal metabolism during pregnancy with subsequent health benefits.

Novel Protein Glycan-Derived Markers of Systemic Inflammation and C-Reactive Protein in Relation to Glycemia, Insulin Resistance, and Insulin Secretion

OBJECTIVE

N-acetylglucosamine/galactosamine (GlycA) and sialic acid (GlycB) moieties of glycosylated serum proteins are nonspecific measures of inflammation, but conclusive data on their relationship with insulin resistance or insulin secretion are missing. Therefore, we aimed to examine the relation of GlycA, GlycB, and C-reactive protein (CRP) to direct measures of insulin sensitivity (insulin sensitivity index [S_I]) and insulin secretion (acute insulin response [AIR]).

RESEARCH DESIGN AND METHODS

This study used cross-sectional analyses and included 1,225 participants with and without type 2 diabetes in the Insulin Resistance Atherosclerosis Study (IRAS). S_I and AIR were measured using the frequently sampled intravenous glucose tolerance test, and GlycA and GlycB were measured using nuclear magnetic resonance spectroscopy.

RESULTS

GlycA and GlycB had a strong correlation with CRP (r = 0.60 [P < 0.001] and r = 0.46 [P < 0.001], respectively). In a linear regression model with both GlycA and CRP as independent variables, GlycA (β × 1 SD, -0.04 ± 0.02; P < 0.01) and CRP (-0.06 ± 0.02; P < 0.001) were independently associated with S_I even after adjusting for demographics, smoking, physical activity, plasma glucose, and BMI. However, neither CRP nor GlycA had an independent relationship with AIR.

CONCLUSIONS

GlycA may complement CRP in evaluating the relationship between inflammation, glucose tolerance, and insulin resistance.

GlycA Is a Novel Biomarker of Inflammation and Subclinical Cardiovascular Disease in Psoriasis

RATIONALE

GlycA, an emerging inflammatory biomarker, predicted cardiovascular events in population-based studies. Psoriasis, an inflammatory disease associated with increased cardiovascular risk, provides a model to study inflammatory biomarkers in cardiovascular disease (CVD). Whether GlycA associates with psoriasis and how it predicts subclinical CVD beyond high-sensitivity C-reactive protein in psoriasis is unknown.

OBJECTIVE

To investigate the relationships between GlycA and psoriasis and between GlycA and subclinical CVD.

METHODS AND RESULTS

Patients with psoriasis and controls (n=412) participated in a 2-stage study. We measured GlycA by nuclear magnetic resonance spectroscopy. National Institutes of Health (NIH) participants underwent 18-F Fluorodeoxyglucose Positron Emission Tomography Computed Tomography (18-FDG PET/CT) scans to assess vascular inflammation (VI) and coronary computed tomographic angiography to quantify coronary artery disease burden. Psoriasis cohorts were young (mean age=47.9), with low cardiovascular risk and moderate skin disease. high-sensitivity C-reactive protein and GlycA were increased in psoriasis compared with controls (GlycA: [PENN: 408.8±75.4 versus 289.4±60.2, P<0.0001; NIH: 415.8±63.2 versus 346.2±46, P<0.0001]) and demonstrated a dose-response with psoriasis severity. In stage 2, VI (β=0.36, P<0.001) and coronary artery disease (β=0.29, P=0.004) associated with GlycA beyond CV risk factors in psoriasis. In receiver operating characteristic analysis, GlycA added value in predicting VI (P=0.01) and coronary artery disease (P<0.01). Finally, initiating anti-tumor necrosis factor therapy (n=16) reduced psoriasis severity (P<0.001), GlycA (463.7±92.5 versus 370.1±78.5, P<0.001) and VI (1.93±0.36 versus 1.76±0.19, P<0.001), whereas GlycA remained associated with VI (β=0.56, P<0.001) post treatment.

CONCLUSIONS

GlycA associated with psoriasis severity and subclinical CVD beyond traditional CV risk and high-sensitivity C-reactive protein. Moreover, psoriasis treatment reduced GlycA and VI. These findings support the potential use of GlycA in subclinical CVD risk assessment in psoriasis and potentially other inflammatory diseases.

Differences in GlycA and lipoprotein particle parameters may help distinguish acute kawasaki disease from other febrile illnesses in children

Background

Glycosylation patterns of serum proteins, such as α1-acid glycoprotein, are modified during an acute phase reaction. The response of acute Kawasaki disease (KD) patients to IVIG treatment has been linked to sialic acid levels on native IgG, suggesting that protein glycosylation patterns vary during the immune response in acute KD. Additionally, the distribution and function of lipoprotein particles are altered during inflammation. Therefore, the aim of this study was to explore the potential for GlycA, a marker of protein glycosylation, and the lipoprotein particle profile to distinguish pediatric patients with acute KD from those with other febrile illnesses.

Methods

Nuclear magnetic resonance was used to quantify GlycA and lipoprotein particle classes and subclasses in pediatric subjects with acute KD (n = 75), post-treatment subacute (n = 36) and convalescent (n = 63) KD, as well as febrile controls (n = 48), and age-similar healthy controls (n = 48).

Results

GlycA was elevated in acute KD subjects compared to febrile controls with bacterial or viral infections, IVIG-treated subacute and convalescent KD subjects, and healthy children (P <0.0001). Acute KD subjects had increased total and small low density lipoprotein particle numbers (LDL-P) (P <0.0001) and decreased total high density lipoprotein particle number (HDL-P) (P <0.0001) compared to febrile controls. Consequently, the ratio of LDL-P to HDL-P was higher in acute KD subjects than all groups tested (P <0.0001). While GlycA, CRP, erythrocyte sedimentation rate, LDL-P and LDL-P/HDL-P ratio were able to distinguish patients with KD from those with other febrile illnesses (AUC = 0.789–0.884), the combinations of GlycA and LDL-P (AUC = 0.909) or GlycA and the LDL-P/HDL-P ratio (AUC = 0.910) were best at discerning KD in patients 6–10 days after illness onset.

Conclusions

High levels of GlycA confirm enhanced protein glycosylation as part of the acute phase response in KD patients. When combined with common laboratory tests and clinical characteristics, GlycA and NMR-measured lipoprotein particle parameters may be useful for distinguishing acute KD from bacterial or viral illnesses in pediatric patients.

Electronic supplementary material

The online version of this article (doi:10.1186/s12887-016-0688-5) contains supplementary material, which is available to authorized users.

GlycA, a novel proinflammatory glycoprotein biomarker, and high-sensitivity C-reactive protein are inversely associated with sodium intake after controlling for adiposity: the Prevention of Renal and Vascular End-Stage Disease study

BACKGROUND

The extent to which dietary sodium intake may confer alterations in the inflammatory status is unclear. GlycA is a novel proton nuclear magnetic resonance spectroscopy-measured biomarker of systemic inflammation, which is associated with the development of cardiovascular disease and diabetes.

OBJECTIVE

We determined associations of the inflammatory markers GlycA and high-sensitivity C-reactive protein (hsCRP) with 24-h sodium excretion.

DESIGN

A cross-sectional, population-based study was performed in 3935 subjects who were not using an antihypertensive medication, lipid-lowering drugs, or a glucose-lowering treatment. Urinary sodium excretion was calculated as the mean of two 24-h urine excretions. Linear regression models were used, with 24-h sodium excretion as an independent variable and GlycA or ln hsCRP as a dependent variable.

RESULTS

The mean ± SD sodium excretion was 143.0 ± 53.4 mmol/24 h. The GlycA concentration was 343.6 ± 58.7 μmol/L, and the geometric mean of the hsCRP concentration was 1.20 mg/L (95% CI: 1.16, 1.25 mg/L). In age- and sex-adjusted analyses, GlycA and ln hsCRP were not significantly associated with 24-h sodium excretion [B: 1.23 (95% CI: -0.67, 3.13; P = 0.21) and 0.03 (95% CI: -0.004, 0.07; P = 0.08), respectively, per 1-SD increase]. After additional adjustment for body mass index (BMI), both GlycA (B: -2.76; 95% CI: -4.65, -0.86; P = 0.004) and ln hsCRP (B: -0.07; 95% CI: -0.11, -0.04; P < 0.001) were inversely associated with 24-h sodium excretion. These associations were similar if adjustment was performed for waist circumference instead of BMI or if additional adjustment was performed for relevant clinical and laboratory variables and were particularly present in men.

CONCLUSIONS

The proinflammatory biomarkers GlycA and hsCRP are inversely related to higher 24-h sodium excretion when taking into account the variation in adiposity. These inverse relations remain present after taking into account other covariates.

High-density lipoprotein and inflammation in cardiovascular disease

Great advances are being made at the mechanistic level in the understanding of the structural and functional diversity of high-density lipoprotein (HDL). HDL particle subspecies of different sizes are now known to differ in the protein and lipid cargo they transport, conferring on them the ability to perform different functions that in aggregate would be expected to provide protection against the development of atherosclerosis and its downstream clinical consequences. Exacerbating what is already a very complex system is the finding that inflammation, via alteration of the proteomic and lipidomic composition of HDL subspecies, can modulate at least some of their functional activities. In contrast to the progress being made at the mechanistic level, HDL epidemiologic research has lagged behind, largely because the simple HDL biomarkers used (mainly just HDL cholesterol) lack the needed complexity. To address this deficiency, analyses will need to use multiple HDL subspecies and be conducted in such a way as to eliminate potential sources of confounding. To help account for the modulating influence of inflammation, effective use must also be made of inflammatory biomarkers including searching systematically for HDL-inflammation interactions. Using nuclear magnetic resonance (NMR)-measured HDL subclass data and a novel NMR-derived inflammatory biomarker, GlycA, we offer a case study example of the type of analytic approach considered necessary to advance HDL epidemiologic understanding.

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.

Novel measures of inflammation and insulin resistance are related to obesity and fitness in a diverse sample of 11-14 year olds: The HEALTHY Study

Background

GlycA is a novel serum marker of systemic inflammation. There is no information on GlycA in pediatric populations, how it differs by gender or its association with body mass index (BMI) or fitness. LP-IR is a serum measure of insulin resistance which is related to changes in BMI group in adolescents, but its relationship with fitness is unknown. The current study examined the independent associations between fitness and BMI with GlycA and LP-IR among US adolescents.

Methods

Participants were 1664 US adolescents from the HEALTHY study with complete 6^th and 8^th grade BMI, fitness and blood data. GlycA and LP-IR were measured by NMR spectroscopy. Three BMI groups and three fitness groups were created. Linear mixed models examined associations between GlycA, LP-IR, fitness and BMI.

Results

LP-IR decreased between 6^th and 8^th grade. GlycA increased among girls but decreased among boys. At 8^th grade, median GlycA values were 27 (7.6%) μmol/L higher (381 versus 354) for girls than boys. Median GlycA 6^th grade values were 9% higher in obese girls than healthy weight girls. Overall there was strong evidence (p<0.001) that GlycA was higher in higher BMI groups. Fitness was negatively associated with GlycA (r = −0.37 and −0.35) and LP-IR (r = −0.34 and − 0.18) at the 6^th and 8^th grade assessments. As BMI category increased and fitness category decreased, GlycA and LP-IR levels increased. Lowest GlycA was found in the low BMI/high fitness group.

Conclusions

GlycA was associated with BMI and fitness among in US adolescents. These findings suggest that there are independent effects for BMI and fitness group with both GlycA and LP-IR. Future studies should validate the role of GlycA and LP-IR to evaluate the effects of interventions to modify obesity and fitness in order to improve systemic inflammation and insulin resistance.

A novel inflammatory biomarker, GlycA, associates with disease activity in rheumatoid arthritis and cardio-metabolic risk in BMI-matched controls

Background

RA and CVD both have inflammation as part of the underlying biology. Our objective was to explore the relationships of GlycA, a measure of glycosylated acute phase proteins, with inflammation and cardiometabolic risk in RA, and explore whether these relationships were similar to those for persons without RA.

Methods

Plasma GlycA was determined for 50 individuals with mild-moderate RA disease activity and 39 controls matched for age, gender, and body mass index (BMI). Regression analyses were performed to assess relationships between GlycA and important markers of traditional inflammation and cardio-metabolic health: inflammatory cytokines, disease activity, measures of adiposity and insulin resistance.

Results

On average, RA activity was low (DAS-28 = 3.0 ± 1.4). Traditional inflammatory markers, ESR, hsCRP, IL-1β, IL-6, IL-18 and TNF-α were greater in RA versus controls (P < 0.05 for all). GlycA concentrations were significantly elevated in RA versus controls (P = 0.036). In RA, greater GlycA associated with disease activity (DAS-28; R_DAS-28 = 0.5) and inflammation (R_ESR = 0.7, R_hsCRP = 0.7, R_IL-6 = 0.3: P < 0.05 for all); in BMI-matched controls, these inflammatory associations were absent or weaker (hsCRP), but GlycA was related to IL-18 (R_hsCRP = 0.3, R_IL-18 = 0.4: P < 0.05). In RA, greater GlycA associated with more total abdominal adiposity and less muscle density (R_{abdominal-adiposity} = 0.3, R_{muscle-density} = −0.3, P < 0.05 for both). In BMI-matched controls, GlycA associated with more cardio-metabolic markers: BMI, waist circumference, adiposity measures and insulin resistance (R = 0.3-0.6, P < 0.05 for all).

Conclusions

GlycA provides an integrated measure of inflammation with contributions from traditional inflammatory markers and cardio-metabolic sources, dominated by inflammatory markers in persons with RA and cardio-metabolic factors in those without.