Metabolic syndrome (MS) as a constellation of risk factors of cardiovascular disease, has received increased attention in the last years, because growing prevalence of MS has been notice in epidemiological and clinical observations (1, 2). MS development is strongly related to improper diet and low physical activity, therefore obesity is one of the important features of MS. However, there is no doubts that different metabolic and genetic factors may influence both metabolic syndrome development and the level of associated cardiovascular risk (3, 4). A role for inflammation in cardiovascular diseases development has become well established over the past decade (5). It has been also accepted that low grade inflammatory process is a key feature of metabolic syndrome strongly influencing associated cardiovascular risk (6, 7). There is no doubts that the intensity of inflammation dependents on many factors (7, 8). Plasma concentrations of fibrinogen have been found to be associated with cardiovascular risk (9). However, it is uncertain whether this association is causal or reflects residual confounding of other risk factors. Genetic variants that influence lifelong differences in plasma fibrinogen levels have not been found to be strongly associated with CVD risk, but there is a lack of data describing potential effect of such variants on inflammatory process development. Therefore, the aim of the presented study was to assess the relationship between occurrence of -455G/A genetic variants in beta-fibrinogen gene and serum levels of C-reactive protein and adhesion molecules in patients with metabolic syndrome.

Patients with metabolic syndrome were recruited for the study among these referred to the Outpatient Clinic of Metabolic Diseases of National Food and Nutrition Institute, who underwent a complete physical examination. Metabolic syndrome was defined according to the Third Report of the National Cholesterol Education Program’s Adult Treatment Panel. MS was recognized when any three or more of following criteria were found: waist circumference > 102 cm in men and > 88 cm in women, serum triglycerides ≥ 150 mg/dl, blood pressure ≥ 130/85 mmHg, HDL-cholesterol < 40 mg/dl in men and < 50 mg/dl in women, serum glucose ≥ 110 mg/dl

Venous blood was collected from each individual after fasting. Plasma total and high-density lipoprotein, triglycerides and glucose were measured by routine methods. CRP concentrations were determined by ultra sensitive assay from Randox. Enzyme immunoassays were used to determine serum levels of ICAM-1 and VCAM-1 (Endogen). Fibrinogen levels were assayed by immunoturbidimetric method based on reagents from DAKO. The plasma levels of adiponectin and leptin were measured by ELISA using reagent kits from Linco Research and Bio Vendor, respectively. DNA was extracted from whole blood with a DNA Blood Mini Kit (A&A biotechnology). The -455G/A polymorphism in the promoter region of the beta-fibrinogen gene was genotyped by PCR amplification of genomic DNA, followed by restriction enzyme digestion (HaeIII) and agarose gel electrophoresis according to procedure described by Thomas et al (10). Data were analyzed using InStat computer package (GraphPad Software,USA).

The study group consisted of 61 men with newly diagnosed metabolic syndrome. Recruited subjects were referred to the Outpatient Clinic for proper diagnosis and treatment, and they did not use lipid lowering and antihypertensive drugs. Patients with diabetes or under any treatment were not recruited for the study. Among participant 21% of smokers, 35% of ex-smokers (stopped to smoke at least 5 years before the study) and 44% of non-smokers were recognized according to self-reporting. The basic characteristic of study participants is presented in table 1.

Most of the study subjects were homozygotes for the G variant in the -455G/A polymorphism in the promoter region of the beta-fibrinogen gene (fig. 1). Only 7% of AA homozygotes were found. Therefore, for further analyses the group was divided in two subgroups: one consisted of GG homozygotes and second consisted of carriers of A allele (AA + GA). No differences in basic characteristic between GG homozygotes and A-allele carriers were found. In both subgroups were notice similar levels of BMI (34.6 ± 3.7 vs 34.2 ± .9, respectively), cholesterol (236 ± 29 vs 228 ± 25 mg/dl), HDL-cholesterol (36 ± 10 vs 37 ± 8 mg/dl), triglycerides (226 ± 18 vs 231 ± 27 mg/dl), glucose (105 ± 18 vs 104 ± 22 mg/dl). insulin (13.2 ± 4.6 vs 12.7 ± 5.3 μU/ml), adiponectin (14.4 ± 3.5 vs 14.0 ± 2.8 ng/ml) and leptin (26.8 ± 4.7 vs 24.9 ± 5.1 ng/ml).

In A-allel carriers (AA + GA genotype) significantly higher levels of plasma fibrinogen than in GG-homozygotes were found (3.58 ± 1.4g/l vs 3.21 ± 1.9 g/l, p < 0.02). The percentage of smokers and non-smokers was similar in both groups, therefore smoking habits did not influence the observed differences. In addition in patients with A-allele the mean serum levels of C-reactive protein (fig. 2) and adhesion molecules VCAM-1 and ICAM-1 (fig. 3) were found to be enhanced as compared to GG-homozygotes (5.4 ± 2.5 g/l vs 4.8 ± 2.3 g/l,919 ± 84 ng/ml vs 860 ± 72 ng/ml, 517 ± 47 ng/ml vs 411 ± 34 ng/ml, respectively). However, only differences in ICAM-1 levels have reached statistical significance (p < 0.01).

The prevalence of obesity not only in adults but also in adolescents and children is dramatically increasing (11). Obesity is the key cause of insulin resistance and significantly increased the risk of development of metabolic disturbances defined as metabolic syndrome (1,3,8). MS as a cluster of major cardiovascular risk factors significantly increases myocardial infarction risk (12-14). In Poland the prevalence of MS among adults is approximately 20% according to NATPOL PLUS survey (15). MS development and its relation to cardiovascular risk results from interactions between genes and life style factors (16). In CVD risk assessment different markers are used and among them inflammatory markers, especially CRP hasbeen recognized to be useful. Patients with metabolic syndrome are characterized by enhanced CRP levels (12-16). The observed CRP levels described intensity of inflammatory process, which results from the action of many factors. Among them polymorphisms of genes related directly and/or indirectly to inflammation may play an important role. In the presented study the potential influence of genetic variants of -455G/A polymorphism in beta-fibrinogen gene on the fibrinogen, CRP and adhesion molecules VCAM-1 and ICAM-1 concentrations in patients with metabolic syndrome was assessed by comparing the levels of these parameters in carriers of different genotypes, who did not differ in basic clinical characteristics. In carriers of A-allele as compared to GG-homozygotes enhanced levels of fibrinogen, CRP, VCAM-1 and ICAM were found. The observed association between studied genetic variants and inflammatory markers was independent on BMI, blood pressure, serum lipids as well as leptin and adiponectin concentrations, because the levels of these factors were very similar in carriers of different genotypes. It may be, therefore, suggested that -455G/A polymorphism by influencing fibrinogen concentration modulate inflammatory process development. However, further studies are needed to confirm this association. Data of the role of polymorphisms in other genes and interactions between different genetic and environmental factors are also awaited to explain the role of genetic factors in cardiovascular disease risk in patients with metabolic syndrome.