José Manuel Fragoso

Tumor necrosis factor-alpha promoter polymorphisms in Mexican patients with rheumatic heart disease

The major histocompatibility genes (MHC) have been associated with the genetic susceptibility to rheumatic heart disease (RHD). Results have been inconsistent and new genes located on the MHC region such as tumor necrosis factor (TNF-alpha) need to be analyzed. TNF-alpha polymorphisms (positions -238 and -308) were determined in 87 RHD Mexican Mestizo patients and 101 healthy controls. Patients were classified into mitral valve damage (MVD) and multivalvular lesion (MVL) categories. TNF-238 G allele and GG genotype were increased in patients when compared to healthy controls (pC=0.001, OR=14.1 and pC=0.003, OR=14.1, respectively). Also, decreased frequencies of TNF-238 A allele (pC=0.001) and AG genotype (pC=0.003) were found. TNF-308 polymorphism analysis showed increased frequencies of T2 (A) allele (pC<10(-3), OR=10.8) and T1T2 (AG) genotype (pC<10(-3), OR=9.85) and decreased frequencies of T1 (G) allele and T1T1 (GG) genotype (pC<10(-3)). When comparing valvular damage to healthy controls, patients with MVD showed increased frequencies of -238 GG (pC=0.03, OR=ND), -308 T1T2 (AG) (pC<10(-3), OR=14) and -308 T2 (A) (pC<10(-3), OR=11.7). Also, this group showed decreased frequencies of T1 (G) allele and T1T1 (GG) genotype (pC<10(-3)). Patients with MVL presented increased frequency of -308 T2 (A) allele (pC=0.0003, OR=8.65) and decreased frequencies of -308 T1 (G) allele and -308 T1T1 (GG) genotype (pC=0.0003 and pC=0.006, respectively). Distribution of -238 and -308 polymorphisms were similar between MVD and MVL. The data demonstrate that RHD is associated with TNF-alpha polymorphisms in the Mexican population; however, these polymorphisms do not have relation with the valve damage.

Angiotensin-Converting Enzyme Gene (ACE) Insertion/Deletion Polymorphism in Mexican Populations

The angiotensin-converting enzyme gene (ACE) insertion/deletion polymorphism was determined in 211 Mexican healthy individuals belonging to different Mexican ethnic groups (98 Mestizos, 64 Teenek, and 49 Nahuas). ACE polymorphism differed among Mexicans with a high frequency of the D allele and the D/D genotype in Mexican Mestizos. The D/D genotype was absent in Teenek and present in only one Nahua individual (2.0%). When comparisons were made, we observed that Caucasian, African, and Asian populations presented the highest frequencies of the D allele, whereas Amerindian (Teenek and Pima) and Australian Aboriginals showed the highest frequencies of the I allele. The distribution of I/D genotype was heterogeneous in all populations: Australian Aboriginals presented the lowest frequency (4.9%), whereas Nahuas presented the highest (73.4%). The present study shows the frequencies of a polymorphism not analyzed previously in Mexican populations and establishes that this polymorphism distinguishes the Amerindian populations of other groups. On the other hand, since ACE alleles have been associated with genetic susceptibility to developing cardiovascular diseases and hypertension, knowledge of the distribution of these alleles could help to define the true significance of ACE polymorphism as a genetic susceptibility marker in the Amerindian populations.

Interleukin 1 β (IL-1B) and IL-1 antagonist receptor (IL-1RN) gene polymorphisms are associated with the genetic susceptibility and steroid dependence in patients with ulcerative colitis.

Background Ulcerative colitis (UC) is an inflammatory bowel disease of unknown etiology. Among cytokines induced in UC, interleukin 1 antagonist (IL-1ra) and interleukin 1 &bgr; (IL-1&bgr;) seems to have a central role because of its immunoregulatory and proinflammatory activities. Goal To determine the association between IL-1RA and IL-1B gene polymorphisms and the clinical features of UC in the Mexican Mestizo population. Study Five polymorphisms in the IL-1 gene cluster members IL-1B (rs16944), IL1F10 (rs3811058), and IL-1RN (rs419598, rs315952, and rs315951) were genotyped by 5′ exonuclease TaqMan genotyping assays in a group of 200 Mexican patients with UC and 248 ethnically matched unrelated healthy controls. Results We found a significant increased frequencies of IL-1RN6/1 TC (rs315952) and RN6/2 CC (rs315951) and decreased frequency of IL-1B-511 TC (rs16944) genotypes in UC patients as compared with healthy controls. In the subgroup analysis, we found a significant association between the RN6/2 GG (rs315951) and IL-1B-511 CC (rs16944) genotypes and the presence of steroid-dependence in UC patients (pC=00001, OR=15.6 and pC=0.008, OR=4.09, respectively). Patients with UC showed increased frequencies of IL-1RN “CTC” and “TCG” haplotypes when compared with healthy controls (P=0.019, OR=1.43 and P<10−7, OR=2.63, respectively). Two haplotypes (TTG and CTG) showed decreased frequency in patients when compared with healthy controls (P=9×10−7, OR=0.11 and P=8×10−6, OR=0.11, respectively). Conclusions IL-1 RN and IL-1B polymorphisms were associated with the genetic susceptibility to develop UC and might be associated with the presence of steroid-dependence in UC patients.

Effects of ovariectomy and estradiol injection on nuclear structures of endometrial epithelial cells

The changes of the rate of RNA synthesis produced by castration and estradiol injection on the surface endometrial cells of the rat are profited to study the variations in the number and size of nuclear ribonucleoprotein structures and in the disposition of chromatin. Two-dimensional measurements on sections contrasted with preferential procedures were employed to estimate the fraction of nuclear volume occupied by each element. Young adult rats in estrus are used as controls. 3 weeks after ovariectomy, the area fraction occupied by the nucleolus is reduced almost to a third of the control value, while the number of perichromatin granules per unit area of nucleus has significantly increased. A single injection of 20 microgram of estradiol produces a rapid decrease of the number of perichromatin granules to a fourth of the value of castrate animals, in 15-30 min, followed by a slow increase. Nucleolar area fraction begins to increase 2 h after estrogen administration and at 24 h it is higher than in controls. It is concluded that the changes of the nucleolar volume are due to the effects of estradiol on the synthesis of nucleolar RNA, while the variations of perichromatin granules are produced by the combination of the effect on extranucleolar RNA synthesis and on its processing and/or transporting to the cytoplasm. Both effects are independent and undergo different temporal courses.

The Srb1+1050T Allele Is Associated with Metabolic Syndrome in Children but Not with Cholesteryl Ester Plasma Concentrations of High-Density Lipoprotein Subclasses

BACKGROUND Low cholesterol and phospholipid plasma levels of some high-density lipoprotein (HDL) subclasses have been described in children with metabolic syndrome. Scavenger receptor class B type I (SR-BI) has been proposed to be at the origin of such HDL alterations because of its key role on cholesteryl esters-HDL metabolism. However, the possible contribution of SR-BI has not been specifically explored in this kind of patients. METHODS Plasma lipid concentrations of HDL subclasses, i.e., triglycerides (TG), phosphatidylcholine (Ph), free cholesterol (FC), and total cholesterol (TC), were determined by enzymatic staining on polyacrylamide gradient gels (PAGE) in 39 pediatric patients with metabolic syndrome and 65 children as controls. Cholesteryl esters were estimated by the difference between TC and FC. Proteins of HDL subclasses were also stained for the assessment of the relative size distribution of HDL. For statistical analysis, the study population was grouped by Srb1 +1050C-->T polymorphism (rs5888) as carriers or noncarriers of the T allele, and data were corrected by metabolic syndrome status. RESULTS The Srb1 +1050T allele was associated with metabolic syndrome [odds ratio (OR)=2.18 (1.12-4.22), P=0.02]. Plasma TG corresponding to HDL3a, as well as the relative proportion of this HDL subclass, were slightly higher in carriers of the T allele as compared to CC homozygous subjects. Cholesteryl esters plasma concentrations of all HDL subclasses were comparable between T allele carriers and noncarriers after correction by metabolic syndrome status. CONCLUSIONS Srb1 +1050T was associated with metabolic syndrome, but T carrier subjects did not show important differences concerning HDL subclasses as compared to noncarriers.

β 1 Adrenergic Receptor Polymorphisms Arg389Gly and Ser49Gly in the Amerindian and Mestizo Populations of Mexico

The β1 adrenergic receptor genotypes (Ser49Gly and Arg389Gly) were determined in 190 individuals from 3 Mexican populations. Mestizos and Teenek present the highest frequencies for the *Arg allele and the lowest frequencies for the *Gly allele (Arg389Gly) compared to European, Asian, and African populations. Mayos present the highest frequency for the *Gly allele. The knowledge of the distribution of these alleles could help define the significance of these polymorphisms as genetic susceptibility markers in Amerindian populations.

Interleukin-17A gene haplotypes are associated with risk of premature coronary artery disease in Mexican patients from the Genetics of Atherosclerotic Disease (GEA) study.

Aim The role of interleukin 17A (IL-17A) in the inflammatory process has caused interest in the potential significance of IL-17A as a biomarker for coronary artery disease (CAD). The aim of the present study was to evaluate the role of IL-17A gene polymorphisms as susceptibility markers for CAD in the Mexican population. Methods Four IL-17A gene polymorphisms (rs8193036, rs3819024, rs2275913 and rs8193037) were genotyped by 5’ exonuclease TaqMan assays in a group of 900 patients with premature CAD and 667 healthy controls (with negative calcium score by computed tomography), seeking associations with CAD and other metabolic and cardiovascular risk factors using logistic regression analyses. Results No single IL-17A polymorphism was associated with premature CAD, however two haplotypes (CAGG and TAGA) were significantly associated with increased risk of premature CAD (OR = 1.35, 95% CI: 1.00–1.84, P = 0.018 and OR = 2.09, 95% CI: 1.16–3.76, P = 0.003, respectively). Moreover, rs3819024 was associated with increased levels of visceral abdominal fat (P = 0.002) and rs8193036 was significantly associated with risk of central obesity (P = 0.020), hypertriglyceridemia (P = 0.027), and metabolic syndrome (P = 0.027) in the premature CAD group, under dominant models adjusted by age, gender, BMI, smoking history, alcohol consumption, and treatment. Conclusion The results suggest that IL-17A haplotypes are involved in the risk of developing premature CAD and some IL-17A polymorphisms are associated with cardiovascular risk factors in Mexican individuals with premature CAD.

C3435T polymorphism of the ABCB1 gene is associated with poor clopidogrel responsiveness in a Mexican population undergoing percutaneous coronary intervention

BACKGROUND Clopidogrel is a pro-drug and its intestinal absorption is limited by the P-glycoprotein encoded by the ABCB1 gene. It is metabolized hepatically by cytochrome P450 enzymes encoded by CYP genes to produce an active metabolite that antagonizes the P2Y12 platelet receptor. Some patients exhibit poor clopidogrel responsiveness due to polymorphisms, resulting in thrombotic events. The aim of this study was to determine the relationship between poor clopidogrel responsiveness and the ABCB1, CYP and P2RY12 gene polymorphisms among patients undergoing percutaneous coronary intervention (PCI). METHODS AND RESULTS Two hundred seventy-six patients who underwent PCI were included in this study. Clopidogrel responsiveness was determined via optical aggregometry in platelet-rich plasma using 10 μM ADP. Patients exhibiting a platelet aggregation response higher than 70% were classified as poor responders. The genetic polymorphisms were analyzed via real-time PCR. Poor responsiveness to clopidogrel was noted in 22.1% of the patients. The TT genotype of the C3435T polymorphism of the ABCB1 gene and omeprazole usage were each associated with poor clopidogrel responsiveness (Exp (β) 2.73, p=0.009 and Exp (β) 3.86, p=0.04, respectively). CONCLUSION Poor clopidogrel responsiveness is associated with the TT genotype of the C3435T polymorphism of the ABCB1 gene.

Interleukin 35 Polymorphisms Are Associated with Decreased Risk of Premature Coronary Artery Disease, Metabolic Parameters, and IL-35 Levels: The Genetics of Atherosclerotic Disease (GEA) Study

Interleukin 35 (IL-35) is a heterodimeric cytokine involved in the development of atherosclerosis. The aim of the present study was to establish if the polymorphisms of IL-12A and EBI3 genes that encode the IL-35 subunits are associated with the development of premature coronary artery disease (CAD) in Mexican individuals. The IL-12A and EBI3 polymorphisms were determined in 1162 patients with premature CAD and 873 controls. Under different models, the EBI3 rs428253 (OR = 0.831, Padd = 0.036; OR = 0.614, Prec = 0.033; OR = 0.591, Pcod2 = 0.027) and IL-12A rs2243115 (OR = 0.674, Padd = 0.010; OR = 0.676, Pdom = 0.014; OR = 0.698, Phet = 0.027; OR = 0.694, Pcod1 = 0.024) polymorphisms were associated with decreased risk of developing premature CAD. Some polymorphisms were associated with clinical and metabolic parameters. Significant different levels of IL-35 were observed in EBI3 rs4740 and rs4905 genotypes only in the group of healthy controls. In summary, our study suggests that the EBI3 and IL-12A polymorphisms play an important role in decreasing the risk of developing premature CAD; it also demonstrates the relationship of the EBI3 rs4740 and rs4905 genotypes with IL-35 levels in healthy individuals.

HDL-sphingomyelin reduction after weight loss by an energy-restricted diet is associated with the improvement of lipid profile, blood pressure, and decrease of insulin resistance in overweight/obese patients.

BACKGROUND Sphingomyelin (SM) diminishes the fluidity of the surface monolayer of high-density lipoproteins (HDL), affecting their intravascular metabolism and antiatherogenic properties. Since overweight is associated with an altered HDL structure, weight loss may result in changes in HDL subclasses, particularly in their SM content. Therefore, we determined the plasma SM concentrations associated to both total HDL and HDL subclasses after weight loss in obese patients. METHODS Fifty overweight patients, 40 women and 10 men, aged 38.6±6.4 y, were given an energy-restricted diet according to their sex, age, and height. No physical activity was prescribed. Plasma SM concentrations of HDL subclasses were determined by a gel surface method developed for this study. Cholesterol of HDL subclasses was also determined by enzymatic methods performed on a gel surface. RESULTS Mean weight lost was 3.5±0.4 kg after 6 weeks of dietary intervention. As expected, insulin resistance and blood pressure decreased whereas lipid profile improved, except for HDL-cholesterol. SM in plasma and in all HDL subclasses significantly decreased after intervention. The magnitude of HDL-SM reduction was statistically associated with the amelioration of the components of the metabolic syndrome; the reduction of BMI explained the decrement of HDL-SM in a multivariate analysis. CONCLUSION HDL-SM decreased after weight loss by an energy-restricted diet. Further, the association of this decrement with the improvement of blood pressure, lipid profile and the decrease of insulin resistance, was statistically significant; all HDL subclasses were similarly affected. Whether a reduction in HDL-SM contributes to the cardiovascular benefits of weight loss remains to be elucidated.