Serum concentrations and tissue expression of a novel endocrine regulator fibroblast growth factor-21 in patients with type 2 diabetes and obesity.

OBJECTIVE: Fibroblast growth factor-21 (FGF21) is a novel endocrine and paracrine regulator of metabolic homeostasis. The aim of our study was to measure its serum concentrations in patients with obesity, obesity and type 2 diabetes mellitus (T2DM) and healthy subjects (C), and to assess the changes of its circulating levels and mRNA expression after dietary and pharmacological interventions. DESIGN: We measured biochemical parameters, serum FGF21, adiponectin, leptin and insulin levels by commercial ELISA and RIA kits, and mRNA expression in the liver, subcutaneous and visceral fat by RT PCR in 26 obese patients, 11 T2DM patients and 32 control subjects. The interventions were acute hyperinsulinaemia during isoglycaemic-hyperinsulinaemic clamp, very low calorie diet (VLCD) and 3 months treatment with PPAR-alpha agonist fenofibrate. RESULTS: Baseline serum FGF21 levels were significantly higher in both obese and T2DM patients relative to healthy controls. FGF21 levels in obesity did not significantly differ from T2DM group. Both 3 weeks of VLCD and 3 months of fenofibrate treatment significantly increased FGF21 levels. FGF21 mRNA expression in visceral fat was twofold higher in obesity relative to C group, while it did not differ in subcutaneous fat. VLCD significantly increased FGF21 mRNA expression in subcutaneous fat of obesity. 3-h hyperinsulinaemia during the clamp increased FGF21 levels in T2DM but not in C group. CONCLUSION: An increase in FGF21 levels after VLCD and fenofibrate treatment may contribute to positive metabolic effect of these interventions and suggests the possibility of direct positive metabolic effects of FGF21 in humans.

Lipocalin-2: development, analytical characterization, and clinical testing of a new ELISA.

Lipocalin-2 (also known as neutrophil gelatinase-associated lipocalin [NGAL]) has been described as a promising marker of metabolic syndrome associated with inflammation. The aim of our work was to develop an assay for the determination of lipocalin-2 in human serum and to investigate its levels in healthy volunteers and donors suffering from metabolic syndrome. We also conducted a pilot study on individuals with metabolic syndrome and on healthy probands and measured lipocalin-2 in these individuals. We developed and evaluated the sandwich ELISA method for the quantitative determination of human lipocalin-2 in serum samples. We measured blood pressure, waist circumference, serum cholesterol, triglycerides, HDL cholesterol, LDL cholesterol, insulin, glucose, creatinine, hs-CRP, and adiponectin and calculated the BMI and Quicki insulin sensitivity index. In the study on 153 healthy volunteers, we showed that sex and age are not determinative for lipocalin-2 serum values. Furthermore, we tested 45 individuals with metabolic syndrome; values of lipocalin-2 did not differ (78.8 vs. 80.0 microg/l, p =0.56) from the data of healthy individuals from the first study. Neither group differed with regard to sex or age. Lipocalin-2 correlated with alanine aminotransferase (ALT) (r=-0.3, p<0.01) aspartate aminotransferase (AST) (r=-0.3, p<0.01), cholesterol (r=-0.21, p=0.047), creatinine (r=0.19, p=0.05), and high-sensitivity C-reactive protein (hs-CRP) (r=0.22, p=0.036). No significant correlation was found between serum lipocalin-2 and BMI, waist circumference, blood pressure, triglycerides, HDL, Quicki, or the number of metabolic syndrome components. When study patients with metabolic syndrome were further stratified according to the number of components of metabolic syndrome, serum concentrations of lipocalin-2 did not differ. The results presented demonstrate the analytical competence of the lipocalin-2 assay. However, we assumed that lipocalin-2 is not a routinely usable marker of metabolic syndrome or obesity. The association between serum lipocalin-2 and obesity or metabolic syndrome was not validated in our study.

Angiopoietin-like protein 4: development, analytical characterization, and clinical testing of a new ELISA.

The aim of our work was to develop an assay for the determination of angiopoietin-like protein 4 (Angplt4) in human blood, and to investigate its levels in healthy volunteers and donors suffer from metabolic syndrome. We developed and evaluated the sandwich ELISA method for the quantitative determination of human Angplt4 in serum samples. We conducted also the pilot study on individuals with metabolic syndrome or familiar hypercholesterolemia and healthy probands and measured blood pressure, waist circumference, Angplt4 serum levels, serum cholesterol, triglycerides, HDL-cholesterol, LDL-cholesterol, insulin, glucose, A-FABP and calculate BMI and QUICKI insulin sensitivity index. In the study on 30 healthy volunteers we demonstrated that sex or age is not the determinant for Angplt4 serum values. Furthermore, we tested 115 individuals with metabolic syndrome and found that probands with metabolic syndrome did not differ in Angplt4 values than healthy individuals from the first study (medians 8.7 vs. 8.1 ng/ml, p = 0.6). Individuals with metabolic syndrome did not differ in sex or age from healthy. Angplt4 values correlated with the HDL-cholesterol (r = -0.25; p < 0.01), FGF-21 (r = 0.23, p < 0.01), glucose (r = 0.17; p = 0.03), uric acid (r = 0.17; p = 0.49), lipocalin-2 (r = 0.23, p < 0.01), triacylglycerols (r = 0.25; p < 0.01) and number or characters of metabolic syndrome (r = 0.21; p < 0.01). No significant correlation was found between serum Angplt4 and BMI, WC or QUICKI. However, we performed stepwise regression and we found that Angplt4 was not an independent marker for metabolic syndrome. The patients from the metabolic syndrome group suffering diabetes mellitus (n = 83) did not differ in serum Angplt4 from the group of healthy patients, too. The pilot study supports the hypothesis about the role of Angplt4 as a new class of lipid metabolism modulator. Their values could be a new key predictors of metabolic syndrome. Further research is necessary to confirm our findings in individuals with dyslipidemia, obesity, coronary artery diseases and different medication in order to assess Angplt4 value as a risk predictor of accelerated atherosclerosis.

Angiopoietin-like protein 3: development, analytical characterization, and clinical testing of a new ELISA.

The aim of our work was to develop an assay for the determination of angiopoietin-like protein 3 (Angptl3) in human blood, and investigate its levels in healthy volunteers and donors suffer from metabolic syndrome and familiar hypercholesterolemia. We developed and evaluated the sandwich ELISA method for the quantitative determination of human Angptl3 in serum samples. We conducted also the pilot study on individuals with metabolic syndrome or familiar hypercholesterolemia and healthy probands. The following parameters were measured: blood pressure, waist circumference, Angptl3 serum levels, serum cholesterol, triglycerides, HDL-cholesterol, LDL-cholesterol, insulin, glucose, A-FABP, and BMI and Quicki insulin sensitivity index was calculated. In the study on 93 healthy volunteers we demonstrated that sex or age is not the determinant for Angptl3 serum values. Futhermore, 118 individuals with metabolic syndrome and 200 patients with familiar hypercholesterolemia were tested and it was found that probands with metabolic syndrome or familiar hypercholesterolemia had higher Angptl3 values than healthy individuals from the first study (medians 289.5 vs. 277.1 vs. 224.8 ng/ml, p < 0.01). All of groups did not differ in sex or age. Angptl3 values correlated with the systolic blood pressure, LDL and A-FABP (p < 0.05). No connection of Angptl3 with triglycerides was found (presumably influences of statins, fibrates via PPARs, etc). However, we performed stepwise regression and found A-FABP and Angptl3 serum values as the independent markers for metabolic syndrome presence only (F ratio 29, p < 0.01). Then we adjusted Angptl3 to A-FABP (reputable metabolic syndrome marker) and recognised that Angptl3 is the A-FABP-independent marker. The pilot study supports the hypothesis about the role of Angptl3 as a new class of lipid metabolism modulator. Their values could be a new key predictors of metabolic syndrome. Further research is necessary to confirm our findings in individuals with dyslipidemia, obesity, CAD and different medication in order to assess Angptl3 value as a risk predictor of accelerated atherosclerosis.

Proguanylin: development, analytical characterization, and clinical testing of a new ELISA.

The aim of our work was to develop an assay for the determination of proguanylin in human blood, and investigate its levels in healthy volunteers and donors suffer from hypertension often accompanied by body sodium accumulation and plasma volume expansion. We developed and evaluated the sandwich ELISA method for the quantitative determination of human proguanylin in serum samples. We conducted also the pilot study on individuals with hypertension and oh healthy probands and measured proguanylin serum levels, serum and urine sodium and creatinine levels. In the study on 256 healthy volunteers we demonstrated that women have significantly higher values of proguanylin than men (medians 12.7 vs. 9.6 ng/ml, p < 0.01) and proguanylin values increased with age of individuals (p < 0.01). Futhermore, we tested 17 individuals with hypertension and found that probands with anamnesi of hypertension had higher proguanylin values than healthy individuals from the first study (medians 16.2 vs. 11.3 ng/ml, p < 0.01). Both of groups did not differ in sex or age. Proguanylin values correlated with the systolic blood pressure (r = 0.41, p < 0.01), sodium fraction excretion (r = 0.72, p < 0.01) and serum sodium (r = -0.39, p < 0.01). No significant correlation we found with serum proguanylin and creatinine. In the group of 9 healthy probands we demonstrated the existence of a diurnal rhythm of proguanylin with its maximum in the evening hours (between 6-10 p.m.). The pilot study supports the hypothesis about the role of proguanylin in sodium metabolism and its possible importance for hypertension disorder. Further research is necessary to confirm our findings in individuals with hypertension with different medication in order to assess proguanylin value as a risk predictor of accelerated hypertension, and to classify individuals with hypertension for variuos types of diuretic therapy.