A pro-inflammatory glycoprotein biomarker is associated with lower bilirubin in metabolic syndrome

Serum Bilirubin and Markers of Oxidative Stress and Inflammation in a Healthy Population and in Patients with Various Forms of Atherosclerosis

Oxidative stress and inflammation contribute significantly to atherogenesis. We and others have demonstrated that mildly elevated serum bilirubin levels protect against coronary and peripheral atherosclerosis, most likely due to the antioxidant and anti-inflammatory activities of bilirubin. The aim of the present study was to assess serum bilirubin and the markers of oxidative stress and inflammation in both healthy subjects and patients with various forms of atherosclerosis. The study was performed in patients with premature myocardial infarction (n = 129), chronic ischemic heart disease (n = 43), peripheral artery disease (PAD, n = 69), and healthy subjects (n = 225). In all subjects, standard serum biochemistry, UGT1A1 genotypes, total antioxidant status (TAS), and concentrations of various pro- and anti-inflammatory chemokines were determined. Compared to controls, all atherosclerotic groups had significantly lower serum bilirubin and TAS, while having much higher serum high-sensitivity C-reactive protein (hsCRP) and most of the analyzed proinflammatory cytokines (p < 0.05 for all comparisons). Surprisingly, the highest inflammation, and the lowest antioxidant status, together with the lowest serum bilirubin, was observed in PAD patients, and not in premature atherosclerosis. In conclusion, elevated serum bilirubin is positively correlated with TAS, and negatively related to inflammatory markers. Compared to healthy subjects, patients with atherosclerosis have a much higher degree of oxidative stress and inflammation.

Glycoprotein Profile Measured by a 1H-Nuclear Magnetic Resonance Based on Approach in Patients with Diabetes: A New Robust Method to Assess Inflammation

Patients with type 2 diabetes mellitus (T2DM) and atherogenic dyslipidemia (AD) are at higher risk of developing cardiovascular diseases (CVDs), so an interest in discovering inflammation biomarkers as indicators of processes related to CVD progression is increasing. This study aims (a) to characterize the plasma glycoprotein profile of a cohort of 504 participants, including patients with and without T2DM and/or AD and controls, and (b) to study the associations between the glycoprotein profile and other lipid and clinical variables in these populations. We characterized the plasma glycoprotein profiles by using ¹H-NMR. We quantified the two peaks associated with the concentration of plasma glycoproteins (GlycA and GlycB) and their height/width ratios (H/W GlycA and H/W GlycB), as higher and narrower signals have been related to inflammation. We also quantified GlycF, the signal of which is proportional to the concentration of the acetyl groups of free N-acetylglucosamine, N-acetylgalactosamine, and N-acetylneuraminic in the samples. The lipoprotein profile was also determined (Liposcale^®). Standard clinical and anthropometric measurements were taken. Multivariate classification models were developed to study the differences between the study groups. Reduced HDL-C levels, increased small dense LDL and HDL particles, and elevated TG levels were significantly associated with glycoprotein variables. Glycoprotein values in the diagnostic groups were significantly different from those in the CT groups. AD and DM conditions together contribute to a positive and significant synergetic effect on the GlycA area (<0.05) and the H/W ratios of GlycA (<0.01) and GlycB (<0.05). By adding the new glycoprotein variables to the traditionally used marker of inflammation C-reactive protein (CRP), the AUC increased sharply for classification models between the CT group and the rest (0.68 to 0.84), patients with and without dyslipidemia (0.54 to 0.86), and between patients with and without diabetes (0.55 to 0.75). ¹H-NMR-derived glycoproteins can be used as possible markers of the degree of inflammation associated with T2DM and AD.

Bilirubin in metabolic syndrome and associated inflammatory diseases: New perspectives

Diabetes mellitus is one of the major global health issues, which is closely related to metabolic dysfunction and the chronic inflammatory diseases. Multiple studies have demonstrated that serum bilirubin is negatively correlated with metabolic syndrome and associated inflammatory diseases, including atherosclerosis, hypertension, etc. However, the roles of bilirubin in metabolic syndrome and associated inflammatory diseases still remain unclear. Here, we explain the role of bilirubin in metabolic syndrome and chronic inflammatory diseases and its therapeutic potential. Understanding the role of bilirubin activities in diabetes may serve as a therapeutic target for the treatment of chronic inflammatory diseases in diabetic patients.

Title: Human Serum/Plasma Glycoprotein Analysis by 1H-NMR, an Emerging Method of Inflammatory Assessment

Several studies suggest that variations in the concentration of plasma glycoproteins can influence cellular changes in a large number of diseases. In recent years, proton nuclear magnetic resonance (1H-NMR) has played a major role as an analytical tool for serum and plasma samples. In recent years, there is an increasing interest in the characterization of glycoproteins through 1H-NMR in order to search for reliable and robust biomarkers of disease. The objective of this review was to examine the existing studies in the literature related to the study of glycoproteins from an analytical and clinical point of view. There are currently several techniques to characterize circulating glycoproteins in serum or plasma, but in this review, we focus on 1H-NMR due to its great robustness and recent interest in its translation to the clinical setting. In fact, there is already a marker in H-NMR representing the acetyl groups of the glycoproteins, GlycA, which has been increasingly studied in clinical studies. A broad search of the literature was performed showing a general consensus that GlycA is a robust marker of systemic inflammation. The results also suggested that GlycA better captures systemic inflammation even more than C-reactive protein (CRP), a widely used classical inflammatory marker. The applications reviewed here demonstrated that GlycA was potentially a key biomarker in a wide range of diseases such as cancer, metabolic diseases, cardiovascular risk, and chronic inflammatory diseases among others. The profiling of glycoproteins through 1H-NMR launches an encouraging new paradigm for its future incorporation in clinical diagnosis.

Glycoprotein A and B Height-to-Width Ratios as Obesity-Independent Novel Biomarkers of Low-Grade Chronic Inflammation in Women with Polycystic Ovary Syndrome (PCOS)

The polycystic ovary syndrome (PCOS) is a common endocrine disorder affecting women in reproductive age. Obesity and low-grade chronic inflammation are frequently associated with PCOS. Recently, proton nuclear magnetic resonance (¹H-NMR)-derived glycoprotein profiles have emerged as potential biomarkers that reflect systemic inflammation in type 2 diabetes, obesity, and other pathological processes. The aim of this work is to study plasma glycoprotein profiles as metabolic/inflammatory biomarkers underlying PCOS and its association with inflammation and obesity. We used ¹H-NMR spectroscopy to study five glycoprotein variables, namely GlycA, GlycB, and GlycF and the height-to-width (H/W) ratio of GlycA and GlycB, in 17 women with PCOS (9 non-obese and 8 obese), 17 control women (9 non-obese and 8 obese), and 19 healthy men (10 non-obese and 9 obese). H/W ratios of GlycA and GlycB, but not glycoprotein areas, were specifically associated with PCOS independently of obesity. When considered as a whole, obese subjects presented higher GlycA, GlycB, and GlycF areas and higher H/W GlycA and GlycB ratios than their non-obese counterparts. All glycoprotein variables were associated with hsCRP, IL-6, and TNF-α, showing different correlations among PCOS, women, and men. Our present exploratory results suggest that ¹H-NMR-derived glycoprotein profiles might serve as novel diagnostic markers of low-grade chronic inflammation in women with PCOS.

Association between serum total bilirubin levels and the risk of type 2 diabetes mellitus

AIM

To confirm whether serum bilirubin is an independent risk factor of type 2 diabetes mellitus (T2DM) onset in patients with impaired fasting glycemia (IFG) and impaired glucose tolerance (IGT).

METHODS

This was a prospective cohort study carried out at the Diabetic Identification Center of Tianjin Metabolic Diseases Hospital. Serum total bilirubin (TBIL) was measured at baseline and the patients were grouped according to baseline bilirubin quartiles. The outcome was the confirmation of T2DM by oral glucose tolerance test (OGTT) during the 3-year follow-up. Logistic regression was used to determine the risk factors for T2DM development and whether bilirubin levels are independently associated with T2DM development.

RESULTS

Finally, 523 patients were analyzed. After 3 years, 310 participants were diagnosed with diabetes based on OGTT. Baseline quartiles of total bilirubin were inversely associated with diabetes risk, even after multivariable adjustment. The adjusted ORs for diabetes were 1.0 (reference), 0.83 (95% CI 0.74-0.96), 0.78 (95% CI 0.68-0.90), 0.74 (95% CI 0.64-0.87) for the 1st, 2nd, 3rd, and 4th quartiles of baseline serum total bilirubin, respectively (P < 0.001).

CONCLUSION

In patients with IFG or IGT, low levels of serum total bilirubin were associated with a significantly increased risk of T2DM.

Primary aldosteronism is associated with decreased low-density and high-density lipoprotein particle concentrations and increased GlycA, a pro-inflammatory glycoprotein biomarker

BACKGROUND

Primary aldosteronism (PA) may confer increased cardiovascular risk beyond effects on systemic blood pressure, but contributing mechanisms remain incompletely understood. We compared plasma (apo)lipoproteins and lipoprotein particle characteristics, GlycA, a pro-inflammatory glycoprotein biomarker of enhanced chronic inflammation, and plasma total branched-chain amino acids (BCAA), measured using nuclear magnetic resonance (NMR) spectroscopy, between patients with PA, control subjects without hypertension, subjects with untreated hypertension and subjects with treated hypertension.

METHODS

Twenty PA patients were individually matched with 2819 control subjects without hypertension, 501 subjects with untreated hypertension and 878 subjects with treated hypertension participating in the PREVEND (Prevention of Renal and Vascular End-Stage Disease) cohort study with respect to age, sex, body mass index, smoking and statin use. The Vantera® Clinical Analyzer was used to determine NMR-based laboratory parameters.

RESULTS

Total cholesterol, low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), apolipoprotein (apo) B, apolipoprotein A-I (apoA-I), LDL particle and HDL particle concentrations were all decreased in PA subjects vs control subjects and subjects with untreated hypertension (P < 0.016). Triglycerides (TG) and triglyceride-rich lipoprotein (TRL) concentrations were lower in PA subjects vs subjects with (untreated) hypertension. GlycA was increased in PA vs the three comparator groups (P < 0.016). Total BCAA concentrations were unaltered in PA.

CONCLUSIONS

Primary aldosteronism is associated with lower concentrations of LDL and HDL particles and to some extent also with lower TG and TRL particle concentrations. PA is also characterized by increased GlycA levels, indicating enhanced low-grade chronic inflammation. Low HDL particle concentrations and increased GlycA could contribute to accelerated cardiovascular disease development in PA.

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.

Bilirubin concentration is positively associated with haemoglobin concentration and inversely associated with albumin to creatinine ratio among Indigenous Australians: eGFR Study

Low serum bilirubin concentrations are reported to be strongly associated with cardio-metabolic disease, but this relationship has not been reported among Indigenous Australian people who are known to be at high risk for diabetes and chronic kidney disease (CKD).

HYPOTHESIS

serum bilirubin will be negatively associated with markers of chronic disease, including CKD and anaemia among Indigenous Australians.

METHOD

A cross-sectional analysis of 594 adult Aboriginal and Torres Strait Islander (TSI) people in good health or with diabetes and markers of CKD. Measures included urine albumin: creatinine ratio (ACR), estimated glomerular filtration rate (eGFR), haemoglobin (Hb) and glycated haemoglobin (HbA1c). Diabetes was defined by medical history, medications or HbA1c≥6.5% or ≥48mmol/mol. Anaemia was defined as Hb<130g/L or <120g/L in males and females respectively. A multivariate regression analysis examining factors independently associated with log-bilirubin was performed.

RESULTS

Participants mean (SD) age was 45.1 (14.5) years, and included 62.5% females, 71.7% Aboriginal, 41.1% with diabetes, 16.7% with anaemia, 41% with ACR>3mg/mmol and 18.2% with eGFR<60mL/min/1.73m². Median bilirubin concentration was lower in females than males (6 v 8μmol/L, p<0.001) and in Aboriginal than TSI participants (6 v 9.5μmol/L, p<0.001). Six factors explained 35% of the variance of log-bilirubin; Hb and cholesterol (both positively related) and ACR, triglycerides, Aboriginal ethnicity and female gender (all inversely related).

CONCLUSION

Serum bilirubin concentrations were positively associated with Hb and total cholesterol, and inversely associated with ACR. Further research to determine reasons explaining lower bilirubin concentrations among Aboriginal compared with TSI participants are needed.

Prevalence and determinants of non-alcoholic fatty liver disease in lifelines: A large Dutch population cohort

Background & aims

Non-alcoholic fatty liver disease is an increasing health issue that develops rather unnoticed with obesity, type 2 diabetes mellitus and metabolic syndrome. We investigated prevalence, determinants and associated metabolic abnormalities of non-alcoholic fatty liver disease in the largest population-based cohort to date.

Methods

Biochemical characteristics, type 2 diabetes mellitus and metabolic syndrome were determined in the Lifelines Cohort Study (N = 167,729), a population-based cohort in the North of the Netherlands. Non-alcoholic fatty liver disease was defined as Fatty Liver Index (FLI)≥60. Exclusion criteria were age <18 years, immigrants, missing data to assess FLI and metabolic syndrome, excessive alcohol use, previous-diagnosed hepatitis or cirrhosis and non-fasting blood sampling.

Results

Out of 37,496 included participants (median age 44 years, 62.1% female), 8,259 (22.0%) had a FLI≥60. Individuals with a FLI≥60 were more often male, older, obese, had higher levels of hemoglobinA1c, fasting glucose, liver enzymes, total cholesterol, low-density lipoprotein cholesterol, triglycerides, c-reactive protein and leucocytes and lower high-density lipoprotein cholesterol (all P<0.0001). Participants with a FLI≥60 showed higher prevalence of type 2 diabetes mellitus (9.3% vs. 1.4%), metabolic syndrome (54.2% vs. 6.2%), impaired renal function (20.1% vs. 8.7%) and cardiovascular disease (4.6% vs. 1.6%) (all P<0.0001). Multivariable logistic analysis showed that smoking, hemoglobin, leucocytes, c-reactive protein, platelets, alanine aminotransferase, alkaline phosphatase, albumin, impaired renal function (OR 1.27, 95%CI 1.15–1.41), metabolic syndrome (OR 11.89, 95%CI 11.03–12.82) and its individual components hyperglycemia (OR 2.53, 95%CI 2.34–2.72), hypertension (OR 1.89, 95%CI 1.77–2.01) and reduced high-density lipoprotein cholesterol (OR 3.44, 95%CI 3.22–3.68) were independently associated with suspected non-alcoholic fatty liver disease (all P<0.0001).

Conclusion

Twenty-two percent (22.0%) of the population in the North of the Netherlands is suspected to suffer from non-alcoholic fatty liver disease, coinciding with a significant increased risk of type 2 diabetes mellitus, metabolic syndrome, cardiovascular disease and impaired renal function.

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.

Higher hydrocortisone dose increases bilirubin in hypopituitary patients- results from an RCT

BACKGROUND

Bilirubin has anti-oxidative and anti-inflammatory properties, which may explain its proposed protective effects on the development of cardiometabolic disorders. Glucocorticoids affect heme oxygenase regulation in vitro, which plays a key role in bilirubin production. Effects of variations in glucocorticoid exposure on circulating bilirubin levels in humans are unknown. Here we tested whether a higher hydrocortisone replacement dose affects circulating bilirubin in hypopituitary patients.

MATERIALS AND METHODS

A randomized double-blind cross-over study (ClinicalTrials.gov, number NCT01546992) was performed in 47 patients with secondary adrenal failure [10-week exposure to a higher hydrocortisone dose (0·4-0·6 mg/kg body weight) vs. 10 weeks of a lower hydrocortisone dose (0·2-0·3 mg/kg body weight)].

RESULTS

Plasma total bilirubin was increased by 10% from 7 to 8 μM in response to the higher hydrocortisone dose (P = 0·033). This effect was inversely related to age (P = 0·042), but was unaffected by sex, obesity and (replacement for) other hormonal insufficiencies. The higher hydrocortisone dose also resulted in lower alkaline phosphatase (P = 0·006) and aspartate aminotransferase activities (P = 0·001).

CONCLUSION

Bilirubin is modestly increased in response to higher glucocorticoid exposure in humans, in conjunction with lower alkaline phosphatase and aspartate aminotransferase activities, which are supposed to represent biomarkers of a pro-inflammatory state and enhanced liver fat accumulation.

Higher circulating GlycA, a pro-inflammatory glycoprotein biomarker, relates to lipoprotein-associated phospholipase A2 mass in nondiabetic subjects but not in diabetic or metabolic syndrome subjects

BACKGROUND

Lipoprotein-associated phospholipase A2 (Lp-PLA2) is a cardiovascular risk marker, which is in part complexed to low-density lipoproteins, where it exerts pro-inflammatory properties. GlycA is a pro-inflammatory proton nuclear magnetic resonance spectroscopy biomarker whose signal originates from a subset of N-acetylglucosamine residues on the most abundant glycosylated acute-phase proteins.

OBJECTIVE

We compared plasma GlycA and Lp-PLA2 mass between subjects without type 2 diabetes mellitus (T2DM) or the metabolic syndrome (MetS) and subjects with T2DM and/or MetS. We also tested the relationship of GlycA with Lp-PLA2 in each group.

METHODS

Plasma GlycA, Lp-PLA2 mass, high-sensitivity C-reactivity protein (hsCRP) and lipids were measured in 40 subjects with neither T2DM nor MetS (group 1) and in 58 subjects with T2DM and/or MetS (group 2).

RESULTS

GlycA and hsCRP were higher (P < .01 for each), whereas Lp-PLA2 was lower in group 2 vs group 1 (P < .001). GlycA was positively related to hsCRP in each group (P < .001). In contrast, GlycA was correlated positively with Lp-PLA2 in group 1 (r = 0.384, P = .015), but not in group 2 (r = 0.045; P = .74; interaction term for difference: P = .059). Although Lp-PLA2 was correlated positively with non-high-density lipoprotein cholesterol and low-density lipoprotein cholesterol in each group (P ≤ .02), its inverse relationship with high-density lipoprotein cholesterol in group 1 (r = -0.381, P = .013) was absent in group 2 (r = -0.101, P = .42).

CONCLUSIONS

A pro-inflammatory glycoprotein biomarker, GlycA, is higher in subjects with either T2DM, MetS, or both. The normally present positive relationship of GlycA with Lp-PLA2 is blunted in subjects with T2DM and/or MetS.

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

BACKGROUND

GlycA is a recently developed glycoprotein biomarker of systemic inflammation that may be predictive of incident type 2 diabetes mellitus (T2DM).

METHODS

Analytical performance of the GlycA test, measured on the Vantera® Clinical Analyzer, was evaluated. To test its prospective association with T2DM, GlycA was measured in 4524 individuals from the PREVEND study and a survival analysis was performed with a mean follow-up period of 7.3y.

RESULTS

Imprecision for the GlycA test ranged from 1.3-2.3% and linearity was established between 150 and 1588μmol/l. During the follow-up period, 220 new T2DM cases were ascertained. In analyses adjusted for relevant covariates, GlycA was associated with incident T2DM; hazard ratio (HR) for the highest vs. lowest quartile 1.77 [95% Confidence Interval (CI): 1.10-2.86, P=0.01], whereas the association of high sensitivity C-reactive protein (hsCRP) with T2DM was not significant. GlycA remained associated with incident T2DM after additional adjustment for hsCRP; HR 1.71 [1.00-2.92, P=0.04]. A multivariable adjusted analysis of dichotomized subgroups showed that the hazard for incident T2DM was highest in the subgroup with high GlycA and low hsCRP (P=0.03).

CONCLUSIONS

The performance characteristics of the GlycA test reveal that it is suitable for clinical applications, including assessment of the risk of future T2DM.