Aleksandra Stanković

Angiotensin II type 1 receptor gene polymorphism and essential hypertension in Serbian population

Essential hypertension is considered to be a multifactorial trait resulting from the combined influence of environmental and genetic determinants. Due to the controversial results about the role of the ATR1 gene locus in hypertension and understanding that ethnic origin should be carefully considered in studying the association between gene polymorphism and disease etiology, we investigated the role of A1166C polymorphism in Serbian hypertensives. A total of 298 subjects, 100 hypertensive and 198 normotensive, age- and sex-matched controls, were included in this study. All subjects were genotyped for the A1166C polymorphism in ATR1 gene using allele-specific PCR-based technique. There were significant differences in both allele and genotype frequencies between hypertensive and normotensive male subjects (p<0.05). There is significant association between hypertension and CC genotype (CC vs. AC+AA OR=2.56, p=0.04) in the males only. These results suggest that a genetic variant of the ATR1 gene locus influences the risk of essential hypertension in the sex-specific manner in the Serbian population.

Association of MMP-3 5A/6A gene polymorphism with susceptibility to carotid atherosclerosis

OBJECTIVES Stromelysin-1 (MMP-3) as a key member of metalloproteinase family could have an important role in atherogenesis. The 5A/6A polymorphism in the promoter of MMP-3 gene affects the level of MMP-3 gene expression. We assessed whether the MMP-3 promoter low- and high-activity genotypes are related to susceptibility for carotid atherosclerosis (CA) in Serbian population. DESIGN AND METHODS The study group of case-control design consisted of 515 participants. The 265 patients with ultrasonographic evidence of carotid plaque presence were recruited for the study. The 5A/6A polymorphism was typed by RFLP-PCR. RESULTS There was significantly higher prevalence of genotypes containing 6A allele in the patients with CA compared to controls (p<0.05). The model of inheritance with the dominant effect of 6A allele gave elevated and significant OR for carotid atherosclerosis (adjusted OR 2.35, CI=1.0-5.5, p=0.048). CONCLUSIONS Subjects carrying genotypes with 6A allele had significantly higher susceptibility to carotid atherosclerosis.

Dysfunctional telomeres in primary cells from Fanconi anemia FANCD2 patients

BackgroundFanconi anemia (FA) is characterized by sensitivity to DNA cross-linking agents, mild cellular, and marked clinical radio sensitivity. In this study we investigated telomeric abnormalities of non-immortalized primary cells (lymphocytes and fibroblasts) derived from FA patients of the FA-D2 complementation group, which provides a more accurate physiological assessment than is possible with transformed cells or animal models.ResultsWe analyzed telomere length, telomere dysfunction-induced foci (TIFs), sister chromatid exchanges (SCE), telomere sister chromatid exchanges (T-SCE), apoptosis and expression of shelterin components TRF1 and TRF2. FANCD2 lymphocytes exhibited multiple types of telomeric abnormalities, including premature telomere shortening, increase in telomeric recombination and aberrant telomeric structures ranging from fragile to long-string extended telomeres. The baseline incidence of SCE in FANCD2 lymphocytes was reduced when compared to control, but in response to diepoxybutane (DEB) the 2-fold higher rate of SCE was observed. In contrast, control lymphocytes showed decreased SCE incidence in response to DEB treatment. FANCD2 fibroblasts revealed a high percentage of TIFs, decreased expression of TRF1 and invariable expression of TRF2. The percentage of TIFs inversely correlated with telomere length, emphasizing that telomere shortening is the major reason for the loss of telomere capping function. Upon irradiation, a significant decrease of TIFs was observed at all recovery times. Surprisingly, a considerable percentage of TIF positive cells disappeared at the same time when incidence of γ-H2AX foci was maximal. Both FANCD2 leucocytes and fibroblasts appeared to die spontaneously at higher rate than control. This trend was more evident upon irradiation; the percentage of leucocytes underwent apoptosis was 2.59- fold higher than that in control, while fibroblasts exhibited a 2- h delay before entering apoptosis.ConclusionThe results of our study showed that primary cells originating from FA-D2 patients display shorten telomeres, elevated incidence of T-SCEs and high frequency of TIFs. Disappearance of TIFs in early response to irradiation represent distinctive feature of FANCD2 cells that should be examined further.

Association of polymorphisms in CTLA-4, IL-1ra and IL-1β genes with multiple sclerosis in Serbian population

We have investigated separate as well as combined influence of IL-1beta TaqI, IL-1ra VNTR and CTLA-4 + 49 A/G polymorphisms on susceptibility, clinical course and progression of MS in 162 Serbian patients. We found significant independent relative risk for MS susceptibility in noncarriers of IL-1ra allele 2 (OR = 2.2, CI = 1.3-3.7, p = 0.003) and CTLA-4 + 49 AA genotype (OR = 2.0, CI = 1.2-3.5, p = 0.01) as well as their combined effect (OR = 4.4, CI = 2.0-9.7, p = 0.0003). Our result supports the significant and combined effect of IL-1ra VNTR and CTLA-4 polymorphisms on MS justifying the need for further haplotype analysis in different populations.

Association of MMP-8 promoter gene polymorphisms with carotid atherosclerosis: Preliminary study

OBJECTIVE Matrix metalloproteinases (MMPs) are involved in the remodeling of the extracellular matrix in the arterial wall. Collagen I is associated with vascular smooth muscle cell (VSMC) migration and monocyte differentiation. MMP-8 is expressed in atherosclerotic plaque and preferentially cleaves collagen type I. The aim of this study was to investigate the associations of two MMP-8 promoter polymorphisms, rs11225395 (-799C/T) and rs1320632 (-381 A/G), with carotid plaque occurrence, and the influence of these polymorphisms on MMP-8 mRNA expression in plaque tissue. METHODS The study included a total of 766 participants: 277 controls and 489 patients with carotid atherosclerosis undergoing endarterectomy. The two investigated polymorphisms were genotyped by PCR-RFLP. The gene expression analysis was performed by real-time PCR. RESULTS In females only, a significantly higher frequency of the -381G allele was found in patients with carotid atherosclerosis compared to controls (OR, 1.7; 95% CI 1.1-2.9; p = 0.001). Significant up-regulation of MMP-8 gene expression was observed in patients carrying the -381G allele compared to those with the AA genotype (mean factor, 3.54; S.E. range, 0.643-19.551; p = 0.007). Carotid plaque tissue of the haplotype G(-381)T(-799) showed a significantly higher mRNA level compared with the reference A(-381)C(-799) haplotype (p = 0.003). CONCLUSION Our preliminary results indicate that MMP-8 -381A/G and -799C/T gene polymorphisms could be risk factors for carotid atherosclerosis. Further validation and functional studies are needed to establish the potential regulatory role of these polymorphisms and their impact on susceptibility to carotid atherosclerosis.

Plasma levels of matrix metalloproteinase-8 in patients with carotid atherosclerosis.

Matrix metalloproteinases (MMPs) are involved in the remodeling of the extracellular matrix (ECM) in the arterial wall during atherogenesis. Collagens are the most abundant proteins in the ECM. MMP‐8 is expressed by cells associated with the development of the atherosclerotic plaque. It cleaves collagen type I three times more potently than two other interstitial collagenases MMP‐1 and MMP‐13. The aim of this study was to investigate whether plasma MMP‐8 values are associated with occurrence of carotid plaque (CP) and possible correlations with clinical and biochemical parameters in carotid atherosclerosis (CA) patients. Total plasma MMP‐8 levels were quantified by ELISA in 63 patients with ultrasonographic evidence of CP presence and 12 controls. Plasma MMP‐8 values were significantly higher in patients with CA compared with controls (median 23.36 ng/ml vs. 13.02 ng/ml, P<0.001) but they did not differ significantly according to gender, smoking and hypertensive status, associated diseases, and use of statins. Statistically significant positive correlations were observed between MMP‐8 plasma values and C reactive protein (r=0.41, P=0.001), urea (r=0.50, P<0.001), aspartate transaminase (r=0.48, P=0.001), and creatinine levels (r=0.38, P=0.006). These results suggest association of MMP‐8 plasma levels with occurrence of CP and correlation with certain biochemical markers. J. Clin. Lab. Anal. 24:246–251, 2010.

Matrix metalloproteinase-9 -1562 C/T gene polymorphism in Serbian patients with multiple sclerosis.

Matrix metalloproteinase-9 (MMP-9) is suggested to play a role in MS by mediating T cell migration across subendothelial basement membrane and by contribution to myelin breakdown. We studied the association of MMP-9 -1562 C/T gene polymorphisms with MS susceptibility and severity in 187 patients from Serbia. The significant decrease in T allele carriership (p = 0.01), was found in female MS patients. In addition, a trend toward lower MSSS in T allele carriers was noticed (CC, mean 5.7 +/- 2.5 vs. CT+TT, mean 4.9 +/- 2.5). Further studies in different populations are needed to resolve the potential influence of MMP-9 gene polymorphism on MS.

Matrix metalloproteinase-1 promoter genotypes and haplotypes are associated with carotid plaque presence.

OBJECTIVES Matrix metalloproteinase (MMP)-1 degrades fibrillar collagens suggesting important role in vascular remodeling. Data about MMP-1 promoter polymorphisms and carotid atherosclerosis (CA) are scarce. The aim of this study was to evaluate association of MMP-1 genotypes/haplotypes with carotid plaque (CP) presence in Serbian population. DESIGN AND METHODS Study enrolled a total of 702 participants: 274 controls and 428 consecutive patients with CA who underwent carotid endarterectomy. MMP-1 polymorphisms -1607 1G/2G, -519 A/G and -340 T/C were genotyped by PCR and RFLP methods. RESULTS Individuals carrying MMP-1 -1607 2G allele had significantly increased allele dose-dependent risk for CP presence (1G1G vs. 1G2G vs. 2G2G; OR=1; OR=1.87 95% CI 1.29-2.07; OR=3.49 95% CI 1.67-7.30, p=0.0009, respectively). Compared to the referent haplotype 2G(-1607)-T(-340)-A(-519), the haplotypes 1G(-1607)-T(-340)-A(-519), 1G(-1607)-T(-340)-G(-519) and 2G(-1607)-C(-340)-A(-519) had statistically significant protective effect on CP presence (OR=0.41, 95% CI 0.29-0.81, p=0.01; OR=0.56, 95% CI 0.44-0.89, p=0.01; OR=0.43, 95% CI 0.27-0.86, p=0.02, respectively). CONCLUSIONS MMP-1 -1607 G/2G polymorphism solely and specific haplotypes of three analyzed promoter polymorphisms are significantly and independently associated with occurrence of CP. Replication studies in other populations are needed.

Expression profiling of the AT2R mRNA in affected tissue from children with CAKUT

OBJECTIVES Congenital anomalies of the kidney and urinary tract (CAKUT) are common causes of chronic renal failure in children. The angiotensin II receptor type 2 (AT2R) is one of proposed candidate genes for CAKUT, but the expression was never explored in humans. The aim was to establish the AT2R gene expression in human CAKUT concerning -1332A/G polymorphism, which might affect alternative splicing. DESIGN AND METHODS Forty-eight patients with CAKUT constitute the basis of this study. Genotyping for -1332A/G, RT-PCR for AT2R gene expression and confirmation sequencing were performed. RESULTS The expression of Ex 1/2/3 and Ex 1/3 transcript splice variants of the AT2R mRNA were detected in human CAKUT tissue. The pattern was observed independently of A to G transition. CONCLUSIONS The expression of AT2R mRNA in human CAKUT was established for the first time and was not affected by -1332A/G polymorphism in children with CAKUT.

Estradiol enhances effects of fructose rich diet on cardiac fatty acid transporter CD36 and triglycerides accumulation

Fructose rich diet increases hepatic triglycerides production and has deleterious cardiac effects. Estrogens are involved in regulation of lipid metabolism as well, but their effects are cardio beneficial. In order to study effects of fructose rich diet on the main heart fatty acid transporter CD36 and the role of estrogens, we subjected ovariectomized female rats to the standard diet or fructose rich diet, with or without estradiol (E2) replacement. The following parameters were analyzed: feeding behavior, visceral adipose tissue mass, plasma lipids, cardiac CD36 expression, localization and insulin regulation, as well as the profile of cardiac lipids. Results show that fructose rich diet significantly increased plasma triglycerides and decreased plasma free fatty acid (FFA) concentration, while E2 additionally emphasized FFA decrease. The fructose diet increased cardiac plasma membrane content of CD36 in the basal and insulin-stimulated states, and decreased its low density microsomes content. The E2 in fructose-fed rats raised the total cardiac protein content of CD36, its presence in plasma membranes and low density microsomes, and cardiac deposition of triglycerides, as well. Although E2 counteracts fructose in some aspects of lipid metabolism, and separately they have opposite cardiac effects, in combination with fructose rich diet, E2 additionally enhances CD36 presence in plasma membranes of cardiac cells and triglycerides accumulation, which paradoxically might promote deleterious effects of fructose diet on cardiac lipid metabolism. Taken together, the results presented in this work are of high importance for clinical administration of estrogens in females with a history of type 2 diabetes.