Dietary management of urea cycle disorders: European practice

BACKGROUND

There is no published data comparing dietary management of urea cycle disorders (UCD) in different countries.

METHODS

Cross-sectional data from 41 European Inherited Metabolic Disorder (IMD) centres (17 UK, 6 France, 5 Germany, 4 Belgium, 4 Portugal, 2 Netherlands, 1 Denmark, 1 Italy, 1 Sweden) was collected by questionnaire describing management of patients with UCD on prescribed protein restricted diets.

RESULTS

Data for 464 patients: N-acetylglutamate synthase (NAGS) deficiency, n=10; carbamoyl phosphate synthetase (CPS1) deficiency, n=29; ornithine transcarbamoylase (OTC) deficiency, n=214; citrullinaemia, n=108; argininosuccinic aciduria (ASA), n=80; arginase deficiency, n=23 was reported. The majority of patients (70%; n=327) were aged 0-16y and 30% (n=137) >16y. Prescribed median protein intake/kg body weight decreased with age with little variation between disorders. The UK tended to give more total protein than other European countries particularly in infancy. Supplements of essential amino acids (EAA) were prescribed for 38% [n=174] of the patients overall, but were given more commonly in arginase deficiency (74%), CPS (48%) and citrullinaemia (46%). Patients in Germany (64%), Portugal (67%) and Sweden (100%) were the most frequent users of EAA. Only 18% [n=84] of patients were prescribed tube feeds, most commonly for CPS (41%); and 21% [n=97] were prescribed oral energy supplements.

CONCLUSIONS

Dietary treatment for UCD varies significantly between different conditions, and between and within European IMD centres. Further studies examining the outcome of treatment compared with the type of dietary therapy and nutritional support received are required.

Differential effects of endurance training and weight loss on plasma adiponectin multimers and adipose tissue macrophages in younger, moderately overweight men

Obese individuals are characterized by low circulating adiponectin concentrations and an increased number of macrophages in adipose tissue, which is believed to be causally associated with chronic low-grade inflammation and insulin resistance. Regular physical exercise decreases overall morbidity in obese subjects, which may be due to modulations of inflammatory pathways. In this randomized clinical trial we investigated the separate effects of endurance training-induced weight loss, diet-induced weight loss, and endurance training per se (without weight loss) on plasma adiponectin multimer composition (Western blotting) and adipose tissue macrophage content (immunohistochemistry) in young, moderately overweight men. Weight loss and endurance training per se decreased whole body fat percentage in an additive manner. No intervention-induced changes were observed for plasma total adiponectin. Surprisingly, endurance training, irrespectively of any associated weight loss, shifted the adiponectin multimer distribution toward a lower molecular weight (21% decrease in HMW/LMW, P = 0.015), whereas diet-induced weight loss shifted the distribution toward a higher molecular weight (42% increase in HMW/MMW, P < 0.001). Furthermore, endurance training per se increased the number of anti-inflammatory CD163+macrophages [from 12.7 ± 2.1 (means ± SE) to 16.1 ± 3.1 CD163+cells/100 adipocytes, P = 0.013], whereas diet-induced weight loss tended to decrease CD68+macrophages in subcutaneous abdominal adipose tissue. Thus regular physical exercise influences systemic and adipose tissue inflammatory pathways differently than diet-induced weight loss in younger, moderately overweight men. Our data suggest that some of the health benefits of a physically active lifestyle may occur through modulations of anti- rather than pro-inflammatory pathways in young, overweight men.

Intake of traditional Inuit diet vary in parallel with inflammation as estimated from YKL-40 and hsCRP in Inuit and non-Inuit in Greenland

BACKGROUND

Chronic low-grade inflammation is involved in the initiation and progression of atherosclerosis and ischemic heart disease. This was rare in pre-western Inuit who lived on a diet that consisted mainly of marine mammals rich in n-3 fatty acids.

OBJECTIVES

To assess the association between biomarkers of inflammation and the intake of traditional Inuit diet in addition to Inuit ethnicity.

METHODS

YKL-40 and hsCRP were measured in serum from 535 Inuit and non-Inuit living in the capital city Nuuk in West Greenland or in the main town or a settlement in rural East Greenland. Dietary habits were assessed by an interview-based food frequency questionnaire.

RESULTS

The participation rate was 95%. YKL-40 was higher in Inuit than in non-Inuit (p < 0.001), in Inuit with a higher intake of traditional Inuit diet (p < 0.001), and in Inuit from rural compared to urban areas (p < 0.001). It also rose with age (p < 0.001), alcohol intake (0.019) and smoking (p < 0.001). Inuit had higher hsCRP compared to non-Inuit (p = 0.003) and hsCRP increased in parallel with intake of traditional Inuit foods (p < 0.001). Alcohol associated with a decrease in hsCRP in Inuit (p = 0.004). YKL-40 and hsCRP increased with higher intakes of traditional Inuit diet after adjusting for ethnicity, gender, age, smoking, alcohol intake and BMI.

CONCLUSIONS

Biomarkers of inflammation vary in parallel with the intake of traditional Inuit diet. A diet based on marine mammals from the Arctic does not reduce inflammatory activity and it may be speculated that markers of inflammation reflect the disease rather than the cause of the disease.

Effects of Roux-en-Y gastric bypass on fasting and postprandial levels of the inflammatory markers YKL-40 and MCP-1 in patients with type 2 diabetes and glucose tolerant subjects

BACKGROUND

The inflammatory markers YKL-40 and monocyte chemoattractant protein-1 (MCP-1) are elevated in morbidly obese patients and decline after weight loss. The objective of our study was to investigate the possible changes of YKL-40 and MCP-1, in both the fasting and the postprandial states, following Roux-en-Y gastric bypass (RYGB) in subjects with type 2 diabetes (T2D) and normal glucose tolerance (NGT).

METHODS

Ten obese patients with T2D and 10 subjects with NGT were examined in the fasting state and after a standard meal prior to and after (1 week, 3 months, and 1 year) RYGB.

RESULTS

Fasting state MCP-1 levels decreased after RYGB in both groups (P values < 0.0001) whereas fasting YKL-40 levels were unchanged (P values ≥ 0.120). Postprandial MCP-1 levels showed a tendency towards a decrease on most study days; however, the changes were only significant at 1 week (P = 0.001) and 1 yr (P < 0.0001) in the T2D group and at 3 mo after RYGB in the NGT group (P = 0.009). YKL-40 levels showed a slight, postprandial suppression on all study days in the T2D group (all P values ≤ 0.021).

CONCLUSIONS

Fasting MCP-1 levels, but not YKL-40 levels, decrease after RYGB in subjects with T2D and NGT. Postprandial changes of inflammatory markers are discrete and inconsistent.

Glycated haemoglobin and the risk of cardiovascular disease, diabetes and all-cause mortality in the Copenhagen City Heart Study

OBJECTIVE

Individuals with diabetes mellitus (DM) have a considerably elevated risk of developing serious health problems including cardiovascular disease (CVD). Long-term elevated levels of blood glucose in nondiabetic individuals may also be associated with increased risk of CVD. The aim of this study was to investigate the relationships between glycated haemoglobin A(1c) (HbA(1c) ) and CVD, DM and all-cause mortality.

SUBJECTS AND DESIGN

The Copenhagen City Heart Study is a prospective study of individuals from the Danish general population. The cohort was followed for 10 years via national registers with respect to incident CVD, DM and all-cause mortality. Follow-up was 100% complete.

RESULTS

A total of 5127 subjects were included, of whom 597 had DM. In the nondiabetic population, HbA(1c) was significantly associated with incident CVD events in both univariate [hazard ratio (HR) 1.38, 95% CI 1.11-1.71] and multivariate analyses (HR 1.31, 95% CI 1.05-1.64). In the nondiabetic population, increased levels of HbA(1c) were correlated with developing DM. There was a threefold increase in risk of incident DM per unit increase in HbA(1c) with a univariate HR of 3.83 (95% CI 1.96-7.51). This relationship was essentially unchanged after multivariate adjustments (HR 4.19, 95% CI 2.01-8.71). Furthermore, we found that net reclassification improvement for diagnosed DM and CVD was significantly improved with the addition of HbA(1c) in the analyses. Although not statistically significant, we found a strong trend towards an association between HbA(1c) and all-cause mortality (HR 1.21, 95% CI 0.99-1.47). We did not find the same associations amongst the population with DM.

CONCLUSION

In the Danish general population, HbA(1c) was strongly associated with CVD in individuals without DM.

Increased levels of YKL-40 and interleukin 6 in patients with chronic pancreatitis and secondary diabetes

OBJECTIVES

Circulating levels of YKL-40 and interleukin 6 (IL-6) are elevated in patients with type 2 diabetes. We aimed to evaluate YKL-40 levels in patients with chronic pancreatitis (CP) with and without secondary diabetes mellitus (DM) to investigate whether elevated plasma YKL-40 could play a primary role in the pathogenesis of type 2 diabetes or rather represent a consequence of the diabetic state.

METHODS

Plasma levels of YKL-40 and IL-6 were measured during an oral glucose tolerance test in 8 patients with CP and secondary DM, 8 patients with CP and normal glucose tolerance (NGT), and 8 healthy control subjects (CTRLs).

RESULTS

Plasma YKL-40 and IL-6 were significantly higher in patients with CP and secondary DM (YKL-40, mean [95% confidence interval], 113 [60-215 ng/mL]; IL-6, 4.6 [2.3-9.1 pg/mL]) compared to patients with CP and NGT (YKL-40, 42 [28-63 ng/mL]; IL-6, 1.4 [0.8-2.4 pg/mL]) and healthy control subjects (YKL-40, 46 [31-69 ng/mL]; IL-6, 1.4 [0.8-2.4 pg/mL]).

CONCLUSIONS

Patients with CP and secondary DM have elevated levels of YKL-40 and IL-6 compared to CP patients with NGT and healthy subjects, suggesting that YKL-40 is not a primary mediator of DM but a consequence of the diabetic state.

The Association between genetic variations of CHI3L1, levels of the encoded glycoprotein YKL-40 and the lipid profile in a Danish population

Background

The inflammatory biomarker YKL-40 seems to play a role in atherosclerosis and is elevated in patients with obesity, cardiovascular disease and type 2 diabetes. Single nucleotide polymorphisms (SNPs) of the YKL-40 encoding gene, CHI3L1, are associated with inter-individual YKL-40 levels. One study has described an association between a promoter polymorphism of CHI3L1 and levels of low density lipoprotein. The objective of this study was to evaluate the influence of YKL-40 on lipid parameters by determining the association between polymorphisms of CHI3L1, serum YKL-40 and levels of the differentiated lipid profile in a Danish general population.

Methodology/Principle Findings

12 SNPs of CHI3L1 were genotyped, and serum YKL-40 and parameters of the lipid profile were measured in 2,656 Danes. Lipid profile and genotypes were available in another Danish population (n = 6,784) for replication. Cholesterol and triglyceride levels increased with increasing YKL-40 quartile (both p<0.0001), and YKL-40 correlated with triglyceride levels (β = 0.15, p<0.0001). Low density lipoprotein levels increased slightly from the 1^st to the 3^rd quartile (p = 0.006). The highest YKL-40 quartile was associated with a greater risk of hypercholesterolemia compared to the lowest YKL-40 quartile (odds ratio 1.36, p = 0.009). Minor homozygosity of rs12123883 was associated with higher triglyceride levels (p = 0.022) and a higher prevalence of low high density lipoprotein (p = 0.012), but these associations could not be confirmed in the replication population.

Conclusions/Significance

Serum YKL-40 correlates with triglyceride levels in a representative group of the general Danish population. No consistent associations between SNPs of CHI3L1 and lipid levels could be documented.

Short-term teriparatide treatment does not affect NT-proBNP, a marker of cardiac disease

BACKGROUND

Teriparatide (Parathyroid hormone (PTH) 1-34) has been shown to increase bone mineral density (BMD) and reduce the risk of vertebral fractures when given intermittently. In contrast primary hyperparathyroidism (PHPT) is associated with increased bone loss. Moreover an increased occurrence of cardiovascular disease (CVD) is seen in PHPT patients. The N-terminal fragment of the pro-peptide of Brain Natriuretic peptide (NT-proBNP), a risk marker of CVD, has been shown to be elevated in PHPT patients, indicating that continuously high concentrations of PTH affect the heart. Therefore the aim of this study was to investigate whether teriparatide treatment is associated with changes in plasma NT-proBNP.

METHODS

A total of 42 patients receiving teriparatide treatment were included in the study. Blood samples were taken at baseline, and after 1, 3 and 6 months of treatment. Plasma concentrations of NT-proBNP were measured. Plasma concentrations of ionized calcium, PTH and alkaline phosphatase (ALP) were also analyzed, and BMD for the lumbar spine and total hip was recorded at baseline and after 6 months.

RESULTS

Data from 10 men and 32 women, mean age 68 years, were included in the analysis. No effect of teriparatide on plasma concentrations of NT-proBNP was observed at any time points. Ionized calcium and ALP concentrations in the plasma increased after 6 months of treatment, whereas PTH concentrations decreased. Spine BMD T-score was significantly increased after 6 months of treatment.

CONCLUSION

After 6 months of treatment with teriparatide, it did not change the concentration of NT-proBNP in plasma, suggesting that intermittent exposure to therapeutic levels of teriparatide does not affect heart function.

High YKL-40 levels predict mortality in patients with type 2 diabetes

AIMS

We determined levels of the inflammatory marker YKL-40 in a population of patients with type 2 diabetes (T2D) and investigated the association with mortality.

METHODS

In a prospective observational follow-up study, 290 patients with T2D, normoalbuminuria (n=177), microalbuminuria (n=71) and macroalbuminuria (n=42) were followed for a median (range) of 17.2 (0.2-23.0) years. Serum YKL-40 concentration was determined at baseline.

RESULTS

Baseline median (IQR) YKL-40 level was 46ng/ml (36-67) in patients with normoalbuminuria, 61ng/ml (43-114) in microalbuminuric patients, and 81.5ng/ml (60-157) in patients with macroalbuminuria, p<0.001. During follow-up 189 patients (65.2%) died, 119 (41.0%) from cardiovascular causes. All-cause mortality was increased in patients with YKL-40 levels in the second and third tertile (hazard ratios (95% CI) compared with the first tertile, (1.50 (1.03-2.19), p=0.034, and 2.88 (2.01-4.12), p<0.001). This association persisted after adjustment for cardiovascular risk factors but was attenuated after additional adjustment for urinary albumin excretion rate and glomerular filtration rate. Cardiovascular mortality was increased with YKL-40 levels in the third tertile compared with the first tertile, (2.70 (1.78-4.08)), p<0.001. This association was diminished after adjustment for covariates.

CONCLUSIONS

In patients with T2D and increasing albuminuria high YKL-40 levels predict all-cause mortality.

YKL-40 levels are independently associated with albuminuria in type 2 diabetes

OBJECTIVE AND DESIGN

YKL-40 is involved in inflammation and endothelial dysfunction, and is increased in patients with type 1 diabetes, with an independent association between increasing YKL-40 levels and increasing levels of albuminuria. YKL-40 is associated with atherosclerosis and an increased cardiovascular mortality in the general population. In the present study YKL-40 levels were examined in patients with type 2 diabetes (T2D) with increasing levels of albuminuria, known to be associated with an increased risk of cardiovascular disease.

MATERIALS AND METHODS

One-hundred-five patients with T2D were examined: 49 with normoalbuminuria (N, U-albumin/creatinine < 2.5 mg/mmol), 35 with persistent microalbuminuria (MA, 2.5-25 mg/mmol) and 21 with persistent macroalbuminuria/diabetic nephropathy (DN, > 25 mg/mmol). The control group consisted of 20 healthy individuals (C). Groups were matched according to age, gender and known duration of diabetes.

RESULTS

Median levels (interquartile range) of serum YKL-40 were significantly higher in N and MA vs. C (86 (55-137) ng/ml and 84 (71-147) ng/ml, respectively vs. 41 (33-55) ng/ml, p < 0.01) and even higher in patients with DN (120 (83-220) ng/ml, p < 0.001 for all comparisons). YKL-40 levels correlated with urinary albumin/creatinine-ratio in the total group of participants (r = 0.41, p < 0.001). Significant intercorrelations of YKL-40 were found with age, duration of diabetes, systolic blood pressure, lipid levels, HbA1c and HOMA-IR. After adjustment for significant covariates, albuminuria was significantly associated with YKL-40 levels (r = 0.32, p = 0.006).

CONCLUSIONS

YKL-40 levels are elevated in patients with T2D with an independent association between increasing YKL-40 levels and increasing levels of albuminuria. The study suggests a role of YKL-40 in the progressing vascular complications in patients with T2D.

Impaired regulation of the incretin effect in patients with type 2 diabetes

OBJECTIVE

In healthy subjects, the incretin effect during an oral glucose tolerance test increases with the size of glucose load, resulting in similar glucose excursions independently of the glucose loads. Whether patients with type 2 diabetes mellitus (T2DM) are able to regulate their incretin effect is unknown.

RESEARCH DESIGN AND METHODS

Incretin effect was measured over 6 d by means of three 4-h oral glucose tolerance test with increasing glucose loads (25, 75, and 125 g) and three corresponding isoglycemic iv glucose infusions in eight patients with T2DM [fasting plasma glucose, mean 7.7 (range 7.0-8.9) mM; glycosylated hemoglobin, 7.0% (6.2-8.4%)] and eight matched healthy control subjects [fasting plasma glucose, 5.3 (4.8-5.7) mM; glycosylated hemoglobin, 5.4% (5.0-5.7%)].

RESULTS

Patients with T2DM exhibited higher peak plasma glucose in response to increasing oral glucose loads, whereas no differences in peak plasma glucose values among control subjects were observed. The incretin effect was significantly (P < 0.003) lower in patients with T2DM (0 ± 7, 11 ± 9, and 36 ± 5%) as compared with control subjects (36 ± 5, 53 ± 6, and 65 ± 6%). Equal and progressively delayed gastric emptying due to the increasing loads was found in both groups. Incretin hormone responses were similar.

CONCLUSIONS

Up-regulation of the incretin effect in response to increasing oral glucose loads seems to be crucial for controlling glucose excursions in healthy subjects. Patients with T2DM are characterized by an impaired capability to regulate their incretin effect, which may contribute to the exaggerated glucose excursions after oral ingestion of glucose in these patients.

Increased levels of the calcification marker matrix Gla Protein and the inflammatory markers YKL-40 and CRP in patients with type 2 diabetes and ischemic heart disease

OBJECTIVE AND DESIGN

Low grade inflammation is of pathogenic importance in atherosclerosis and in the development of cardiovascular disease (CVD) and type 2 diabetes (T2D). Matrix GLA protein (MGP), an inhibitor of medial calcification of arteries, is increased in patients with atherosclerosis. In the present study levels of markers of calcification (MGP) and inflammation (YKL-40, hsCRP) were evaluated in patients with T2 D and/or ischemic heart disease (IHD).

MATERIALS AND METHODS

The study population consisted of 1) patients with T2D (n = 45); 2) patients with IHD (n = 37); patients with both T2D and IHD (n = 20) and 4) healthy controls (n = 20). Biochemical parameters were measured in venous blood samples.

RESULTS

Levels of MGP, YKL-40 and hsCRP were increased in patients with IHD and/or T2D (p < 0.0001) and patients with T2D and IHD had higher MGP levels (p < 0.001). In multiple linear regression analyses MGP was associated with patient category (r = 0.36, p < 0.001), and HDL-cholesterol levels (r = 0.29, p < 0.001) adjusting for the significant covariates.

CONCLUSIONS

In patients with T2D and/or IHD we found increased levels of plasma MGP indicative of a progressing calcification process. This process is paralleled by increased levels of YKL-40 and hsCRP, which most likely reflect the concomitant low grade inflammatory state in these patients.

NT-proBNP and circulating inflammation markers in prediction of a normal myocardial scintigraphy in patients with symptoms of coronary artery disease

BACKGROUND

Myocardial perfusion imaging (MPI) can detect myocardial perfusion abnormalities but many examinations are without pathological findings. This study examines whether circulating biomarkers can be used as screening modality prior to MPI.

METHODOLOGY/PRINCIPAL FINDINGS

243 patients with an intermediate risk of CAD or with known CAD with renewed suspicion of ischemia were referred to MPI. Blood samples were analyzed for N-terminal fragment of the prohormone brain natriuretic peptide (NT-proBNP), YKL-40, IL-6, matrix metalloproteinase 9 (MMP-9) and high sensitive C-reactive protein (hsCRP). Patients with myocardial perfusion defects had elevated levels of NT-proBNP (p<0.0001), YKL-40 (p = 0.03) and IL-6 (p = 0.03) but not of hsCRP (p = 0.58) nor of MMP-9 (p = 0.14). The NT-proBNP increase was observed in both genders (p<0.0001), whereas YKL-40 (p = 0.005) and IL-6 (p = 0.02) were elevated only in men. A NT-proBNP cut off-concentration at 25 ng/l predicted a normal MPI with a negative predictive value >95% regardless of existing CAD.

CONCLUSIONS

20-25% of patients suspected of CAD could have been spared a MPI by using a NT-proBNP cut-off concentration at 25 ng/l with a negative predictive value >95%. NT-proBNP has the potential use of being a screening marker of CAD before referral of the patient to MPI.

Plasma YKL-40 levels are elevated in patients with chronic heart failure

OBJECTIVES

Congestive heart failure (CHF) has been associated with elevated biomarker levels reflecting chronic low-grade inflammation. YKL-40 is a biomarker with increasing levels in patients with cardiovascular disease (CVD) of increasing severity. Furthermore, YKL-40 is associated with all-cause and cardiovascular mortality. We investigated plasma YKL-40 levels in patients with CHF and evaluated the possible predictive value with respect to overall mortality and recurrent cardiovascular outcomes.

DESIGN

Plasma YKL-40 was measured in 194 CHF patients and in 117 age-matched individuals without CVD.

RESULTS

Median YKL-40 levels were approximately 77% higher in patients with CHF (106 (IQR, 66-184) ng/ml vs. 60 (IQR, 42-97) ng/ml, p < 0.0001). We found a trend towards an association of YKL-40 levels with urinary albumin/creatinine ratio (UACR) (beta = 0.12, p = 0.08). YKL-40 levels were not predictive of overall mortality (p = 0.59), major cardiovascular events (p = 0.23) or events of incompensation (p = 0.56).

CONCLUSIONS

Plasma YKL-40 levels are elevated in patients with CHF but show no association with other clinical or paraclinical variables. YKL-40 levels were not predictive of overall mortality or incident cardiovascular events. Most likely, elevated YKL-40 levels in CHF patients are explained by the presence of concomitant diseases but a role of YKL-40 in low-grade inflammation is not excluded.

Increased YKL-40 expression in patients with carotid atherosclerosis

OBJECTIVE

We hypothesized a role for the inflammatory protein YKL-40 in atherogenesis and plaque destabilization based on its role in macrophage activation, tissue remodeling, and angiogenesis.

METHODS

Serum YKL-40 levels were measured by enzyme immunoassay in 89 patients with carotid atherosclerosis and 20 healthy controls. Carotid expression of YKL-40 was examined by real time RT-PCR in 57 of the patients. Regulation and effect of YKL-40 were examined in THP-1 monocytes.

RESULTS

Our main findings were: (1) serum YKL-40 levels were significantly elevated in patients with carotid atherosclerosis, with particularly high levels in those with symptomatic disease; (2) patients with recent ischemic symptoms (within 2 months) had higher YKL-40 mRNA levels in carotid plaque than other patients; (3) in vitro, the beta-adrenergic receptor agonist isoproterenol, toll-like receptor (TLR) 2 and TLR4 agonists, and in particular releasate from activated platelets significantly increased the expression of YKL-40 in THP-1 monocytes and (4) in vitro, YKL-40 increased matrix metalloproteinase-9 expression and activity in THP-1 monocytes, involving activation of p38 mitogen-activated protein kinase.

CONCLUSIONS

Our findings suggest that YKL-40 might be a marker of plaque instability, potentially reflecting macrophage activation and matrix degradation within the atherosclerotic lesion.

[Polycystic ovary syndrome and comorbidity]

Polycystic ovary syndrome (PCOS) is the most frequent endocrinological disorder among women in the reproductive age. It is by its very nature a heterogeneous juxtaposition of clinical and biochemical features. In women with PCOS, the most common clinical manifestations - obesity, hirsutism and oligomenorrhoea - are associated with insulin resistance, dyslipidaemia, hypertension, vascular dysfunction involving chronic inflammation and also reduced cardiopulmonary function. The focus of this overview is therefore on PCOS comorbidity with the metabolic syndrome, type 2 diabetes and cardiovascular diseases.

YKL-40--an emerging biomarker in cardiovascular disease and diabetes

Several inflammatory cytokines are involved in vascular inflammation resulting in endothelial dysfunction which is the earliest event in the atherosclerotic process leading to manifest cardiovascular disease. YKL-40 is an inflammatory glycoprotein involved in endothelial dysfunction by promoting chemotaxis, cell attachment and migration, reorganization and tissue remodelling as a response to endothelial damage. YKL-40 protein expression is seen in macrophages and smooth muscle cells in atherosclerotic plaques with the highest expression seen in macrophages in the early lesion of atherosclerosis. Several studies demonstrate, that elevated serum YKL-levels are independently associated with the presence and extent of coronary artery disease and even higher YKL-40 levels are documented in patients with myocardial infarction. Moreover, elevated serum YKL-40 levels have also been found to be associated with all-cause as well as cardiovascular mortality. Finally, YKL-40 levels are elevated both in patients with type 1 and type 2 diabetes, known to be at high risk for the development of cardiovascular diseases, when compared to non-diabetic persons. A positive association between elevated circulating YKL-40 levels and increasing levels of albuminuria have been described in patients with type 1 diabetes indicating a role of YKL-40 in the progressing vascular damage resulting in microvascular disease.

This review describes the present knowledge about YKL-40 and discusses its relation to endothelial dysfunction, atherosclerosis, cardiovascular disease and diabetes and look ahead on future perspectives of YKL-40 research.

Association of polymorphisms of the CHI3L1 gene with asthma and atopy: a populations-based study of 6514 Danish adults

Background

YKL-40 is a chitinase-like glycoprotein encoded by the chitinase 3-like 1 gene, CHI3L1, localized at chromosome 1q32.1. Increased levels of serum YKL-40 have been reported to be a biomarker for asthma and a reduced lung function. Interestingly, the C-allele of the -131 C→G (rs4950928) polymorphism of CHI3L1 has been shown to associate with bronchial hyperresponsiveness and reduced lung function suggesting that variations in CHI3L1 may influence risk of asthma. The objective of the present study was to investigate the association of common variation in the CHI3L1 locus with asthma, atopy and lung function in a large population-based sample of adults.

Methods/Principal Findings

Eleven single nucleotide polymorphisms (SNPs) of CHI3L1 including rs4950928 were genotyped in 6514 individuals. Asthma was defined as self-reported history of physician-diagnosed asthma. Total IgE and specific IgE to inhalant allergens were measured on serum samples. Lung function was measured by spirometry. Homozygosity of the rs4950928 G allele as compared to homozygosity of the C allele was associated with self-reported physician diagnosed asthma (OR 1.5 (95% CI, 1.00–2.26)) and with prevalence of atopic asthma (OR 1.93 (95% CI, 1.21–3.07)) after adjustment for age, sex, smoking status, socio-economic class and BMI. Carriers of rs883125 G allele had a significantly lower prevalence of atopy (OR 0.82 (CI, 0.72; 0.94)) as compared to homozygosity of the C allele. None of the SNPs examined were significantly associated with FEV1. However, two SNPs (rs10399931and rs4950930) appeared to be significantly associated with FEV₁/FVC-ratio. Subgroup analyses of never-smokers did not consistently influence the associations in an either positively og negatively way.

Conclusions

In contrast to previous studies, the rs4950928 G allele, and not the C allele, was found to be associated with asthma. A few other SNPs of the CHI3L1 was found to be significantly associated with atopy and FEV1/FVC ratio, respectively. Thus, more studies seem warranted to establish the role of CHI3L1 gene in asthma and atopy.

Variation in CHI3LI in relation to type 2 diabetes and related quantitative traits

Background

CHI3LI encoding the inflammatory glycoprotein YKL-40 is located on chromosome 1q32.1. YKL-40 is involved in inflammatory processes and patients with Type 2 Diabetes (T2D) have elevated circulating YKL-40 levels which correlate with their level of insulin resistance. Interestingly, it has been reported that rs10399931 (−329 G/A) of CHI3LI contributes to the inter-individual plasma YKL-40 levels in patients with sarcoidosis, and that rs4950928 (−131 C/G) is a susceptibility polymorphism for asthma and a decline in lung function. We hypothesized that single nucleotide polymorphisms (SNPs) or haplotypes thereof the CHI3LI locus might influence risk of T2D. The aim of the present study was to investigate the putative association between SNPs and haplotype blocks of CHI3LI and T2D and T2D related quantitative traits.

Methods/Principal Findings

Eleven SNPs of CHI3LI were genotyped in 6514 individuals from the Inter99 cohort and 2924 individuals from the outpatient clinic at Steno Diabetes Center. In cas-control studies a total of 2345 T2D patients and 5302 individuals with a normal glucose tolerance test were examined.

We found no association between rs10399931 (OR, 0.98 (CI, 0.88–1.10), p = 0.76), rs4950928 (0.98 (0.87–1.10), p = 0.68) or any of the other SNPs with T2D. Similarly, we found no significant association between any of the 11 tgSNPs and T2D related quantitative traits, all p>0.14. None of the identified haplotype blocks of CHI3LI showed any association with T2D, all p>0.16.

Conclusions/Significance

None of the examined SNPs or haplotype blocks of CHI3LI showed any association with T2D or T2D related quantitative traits. Estimates of insulin resistance and dysregulated glucose homeostasis in T2D do not seem to be accounted for by the examined variations of CHI3LI.

Study rationale and design of the CIMT trial: the Copenhagen Insulin and Metformin Therapy trial

BACKGROUND

Patients with type 2 diabetes (T2DM) have an increased mortality rate primarily because of macrovascular disease. Where T2DM patients cannot be managed sufficiently through diet, exercise and peroral antidiabetic drugs, that is when haemoglobin A1c (HbA1c) is above 7.0%, it is yet unknown whether a combination of metformin and insulin analogues is superior to insulin analogues alone. Nor is it known which insulin analogue regimen is the optimal.

OBJECTIVE

The primary objective of this trial is to evaluate the effect of an 18-month treatment with metformin vs. placebo in combination with one of three insulin analogue regimens, the primary outcome measure being carotid intima-media thickness (CIMT) in T2DM patients.

DESIGN

A randomized, stratified, multicentre trial having a 2 x 3 factorial design. The metformin part is double masked and placebo controlled. The insulin treatment is open. The intervention period is 18 months.

PATIENT POPULATION

Nine hundred and fifty patients with T2DM and HbA1c > or = 7.5% on treatment with oral hypoglycaemic agents or on insulin treatment and deemed able, by the investigator, to manage once-daily insulin therapy with a long-acting insulin analogue.

RANDOMIZATION

Central randomization stratified for age (above 65 years), previous insulin treatment and treatment centre.

INTERVENTIONS

Metformin 1 g x two times daily vs. placebo (approximately 475 patients vs. 475 patients) in combination with insulin detemir before bedtime (approximately 315 patients) or biphasic insulin aspart 30 before dinner with the possibility to increase to two or three injections daily (approximately 315 patients) or insulin aspart before the main meals (three times daily) and insulin detemir before bedtime (approximately 315 patients). Intervention follows a treat-to-target principle in all six arms aiming for an HbA1c < or = 7.0%.

OUTCOME MEASURES

Primary outcome measure is the change in CIMT from baseline to 18 months. Secondary outcome measures comprises the composite outcome of death, acute myocardial infarction, stroke or amputation assessed by an adjudication committee blinded to intervention, other cardiovascular clinical outcomes, average postprandial glucose increment from 0 to 18 months, hypoglycaemia and any inadvertent medical episodes. In addition, change in plaque formation in the carotids, HbA1c, cardiovascular biomarkers, body composition, progression of microvascular complications and quality of life will be assessed as tertiary outcome measures. TIME SCHEDULE: Patient enrolment started May 2008. Follow-up is expected to finish in March 2011.

CONCLUSION

CIMT is designed to provide evidence as to whether metformin is advantageous even during insulin treatment and to provide evidence regarding which insulin analogue regimen is most advantageous with regard to cardiovascular disease.

Low grade inflammation as measured by levels of YKL-40: association with an increased overall and cardiovascular mortality rate in an elderly population

BACKGROUND

Low grade inflammation is of pathogenic importance in the development of cardiovascular disease (CVD) and type 2 diabetes. The inflammation marker YKL-40 correlates with insulin resistance and is highly expressed in atherosclerotic plaques. We aimed to investigate whether YKL-40 could predict overall and cardiovascular (CV) mortality in a 50+ years population without known CVD.

METHODS

A representative population sample of 639 individuals aged 50-89 years was recruited from general practices. Examination at baseline included echocardiography and blood and urine samples for CV risk factors and markers including lipids, high sensitive C-reactive protein (hsCRP), N-terminal fragment of pro-brain natriuretic peptide (NT-proBNP) and urinary albumin/creatinine-ratio (UACR). Median follow-up period was 5.0 (0.17-5.28) years.

RESULTS

In subjects without diabetes and CVD at baseline, increasing YKL-40 levels independently predicted overall and CV mortality rate with hazard ratios of 1.58 (95% confidence interval (CI), 1.12-2.23, p=0.009) and 1.57 (95% CI, 1.00-2.46, p=0.049) after adjustment for age, sex, smoking, total cholesterol, hsCRP, NT-proBNP and UACR. In combined Kaplan-Meier analyses, baseline values of both YKL-40 and UACR above median significantly predicted increased cumulative overall and CV mortality rates in subjects without diabetes or CVD at baseline (30.6% vs. <or=8%, respectively 10.6%<or=3%, p<0.0001).

CONCLUSIONS

YKL-40 seems to be an independent predictor of overall and CV mortality in an elderly part of the general population without diabetes and CVD. YKL-40 and UACR are both independent predictors, that seem to predict overall and CV mortality in a synergistic way.

YKL-40, a marker of inflammation and endothelial dysfunction, is elevated in patients with type 1 diabetes and increases with levels of albuminuria

OBJECTIVE

The inflammation marker YKL-40 is elevated in patients with type 2 diabetes and is associated with atherosclerosis and increased cardiovascular mortality. In the present study, YKL-40 levels were examined in patients with type 1 diabetes with increasing levels of albuminuria, known to be associated with an increased risk of cardiovascular disease.

RESEARCH DESIGN AND METHODS

A total of 149 patients with type 1 diabetes attending Steno Diabetes Center were examined: 58 had normoalbuminuria (urinary albumin excretion rate <30 mg/24 h), 46 had persistent microalbuminuria (urinary albumin excretion rate 30-300 mg/24 h), and 45 had persistent macroalbuminuria/diabetic nephropathy (urinary albumin excretion rate >300 mg/24 h). The control group consisted of 55 healthy individuals. Groups were matched according to sex and duration of diabetes (>30 years).

RESULTS

Median levels [interquartile range] of serum YKL-40 were significantly higher in normoalbuminuria versus control (37 [29-52] vs. 53 [32-105] ng/ml, P < 0.01) and were increasing with increasing levels of albuminuria (microalbuminuria 74 [45-160] ng/ml and diabetic nephropathy 117 [68-215] ng/ml; P < 0.001 for all comparisons). YKL-40 levels correlated with the urinary albumin-to-creatinine ratio in the total group of participants (r2 = 0.25, P < 0.001). Significant but weak intercorrelations of YKL-40 were found with age, diastolic blood pressure, A1C, and serum creatinine. After adjustment for significant covariates, albuminuria was significantly associated with YKL-40 levels (P < 0.001).

CONCLUSIONS

YKL-40 levels are elevated in patients with type 1 diabetes with an independent association between increasing YKL-40 levels and increasing levels of albuminuria. The present study is the first to suggest a role of YKL-40 in the gradually progressing vascular complications in patients with type 1 diabetes.