Genetic polymorphisms of eNOS (-786T/C, Intron 4b/4a & 894G/T) and its association with asymptomatic first degree relatives of coronary heart disease patients

Influence of endothelial nitric oxide synthase haplotypes on nitric oxide and peroxynitrite productions

The impact of four clinically significant genetic variants of endothelial nitric oxide synthase (eNOS) polymorphisms on the concentrations of nitric oxide [NO] and peroxynitrite [ONOO-] has been given scant consideration. This study utilized a [NO]/[ONOO-] ratio to determine the extent of endothelial dysfunction caused by these variations in the eNOS gene. The single nucleotide polymorphisms (T-786C, C-665T, and Glu298Asp) and a variable number of tandem repeats (intron 4 a/b/c) were genotyped in human umbilical vein endothelial cells (HUVEC), using sanger sequencing and DNA electrophoresis, respectively. Nanosensors were used to determine the maximal [NO] and [ONOO-], while traditional and low-temperature SDS-PAGE were used to evaluate the expression of eNOS and the eNOS dimer-to-monomer ratio, respectively. The study results indicate that the eNOS haplotype H3 (G T/C C 4a/c allele) may have a protective effect against cardiovascular disease (CVD) with the [NO]/[ONOO-] ratio higher than 2. However, the eNOS haplotypes H2 (G T/C C 4a/b) and H5 (T T/C C 4b) increase the susceptibility to CVD with [NO]/[ONOO-] ratio lower than 1. The results suggest that certain eNOS genetic variants may influence susceptibility to cardiovascular disease (CVD) while other variants may have a protective effect.

A protective erythropoietin evolutionary landscape, NLRP3 inflammasome regulation, and multisystem inflammatory syndrome in children

The low incidence of pediatric severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection and the associated multisystem inflammatory syndrome (MIS-C) lack a unifying pathophysiological explanation, impeding effective prevention and therapy. Activation of the NACHT, LRR, and PYD domains-containing protein (NLRP) 3 inflammasome in SARS-CoV-2 with perturbed regulation in MIS-C, has been reported. We posit that, early age physiological states and genetic determinants, such as certain polymorphisms of renin-angiotensin aldosterone system (RAAS) molecules, promote a controlled RAAS hyperactive state, and form an evolutionary landscape involving an age-dependent erythropoietin (EPO) elevation, mediating ancestral innate immune defenses that, through appropriate NLRP3 regulation, mitigate tissue injury and pathogen invasion. SARS-CoV-2-induced downregulation of angiotensin-converting enzyme (ACE)2 expression in endothelial cells (EC), impairment of endothelial nitric oxide (NO) synthase (eNOS) activity and downstream NO bioavailability, may promote a hyperactive RAAS with elevated angiotensin II and aldosterone that, can trigger, and accelerate NLRP3 inflammasome activation, while EPO-eNOS/NO abrogate it. Young age and a protective EPO evolutionary landscape may successfully inhibit SARS-CoV-2 and contain NLRP3 inflammasome activation. By contrast, increasing age and falling EPO levels, in genetically susceptible children with adverse genetic variants and co-morbidities, may lead to unopposed RAAS hyperactivity, NLRP3 inflammasome dysregulation, severe endotheliitis with pyroptotic cytokine storm, and development of autoantibodies, as already described in MIS-C. Our haplotype estimates, predicted from allele frequencies in population databases, are in concordance with MIS-C incidence reports in Europeans but indicate lower risks for Asians and African Americans. Targeted Mendelian approaches dissecting the influence of relevant genetic variants are needed.

The association of Intron 4 VNTR and Glu298Asp polymorphisms of the nitric oxide synthetase 3 gene and vasculogenic erectile dysfunction in Turkish men

Several studies have focused on the impaired role of endothelial nitric oxide synthase (NOS3) gene polymorphism and its association to erectile dysfunction (ED). However, currently controversial results have been reported due to their significant heterogeneity. The present study aimed to assess the genotypic distribution and the allelic frequency of Intron 4 VNTR and Glu298Asp gene polymorphisms in vasculogenic ED patients compared to healthy controls of a specific region of Turkey. A total of 75 patients with ED (median age: 56, IQR:10.5) and 75 healthy controls (median age: 56, IQR:10.5) were prospectively analyzed. All subjects were equally evaluated by the same physician with detailed history-taking, physical examination, International Index of Erectile Function (IIEF) questionnaire, and blood tests (incl. glucose, testosterone, triglyceride and total cholesterol level). Those with an IIEF score under 26 were considered to have ED, by classifying them according to their scores as mild (22-25), moderate (11-21) and severe (1-10) ED. Color doppler ultrasonography was carried out in patients with an IIEF score <22. Hypertension, diabetes mellitus, coronary artery disease, and smoking status were significantly associated with the ED group compared to control subjects with p values of <0.001, <0.001, 0.002 and <0.001, respectively. Overall genotype frequencies was 47 (31%) a/a, 22 (15%) a/b, 82 (55%) b/b for Intron 4 VNTR and 56 (37%) GG, 78 (52%) GT, 16 (11%) TT for the Glu298Asp polymorphism. The frequencies of Intron 4 VNTR a/a allele and Glu298Asp GT allele were associated with severe ED, while a/b and TT were associated with moderate or mild, and b/b and GG were associated with no ED. In contrast to Glu298Asp, statistically significant differences in genotypic frequencies of Intron 4 VNTR gene polymorphism between ED and control subjects was established. Abbreviations: NO: nitric oxide, NOS: nitric oxide synthase, NOS3: endothelial nitric oxide synthase, NOS2: inducible nitric oxide synthase, NOS1: neuronal nitric oxide synthase, HT: hypertension, DM: diabetes mellitus, CAD: coronary artery disease, ED: erectile dysfunction, IIEF: international index of erectile function, VNTR: variable number of tandem repeats, CDU: color doppler ultrasonography, PCR: polymerase chain reaction.

The association between an endothelial nitric oxide synthase gene polymorphism and coronary heart disease in young people and the underlying mechanism

With the development of molecular biological technology, the association between genes and diseases has drawn increasing attention of researchers; the endothelial nitric oxide synthase (eNOS) gene has been reported to be a candidate gene for cardiovascular disease (CHD). The present study aimed to investigate the association between a polymorphism of eNOS and the risk of CHD in young people (≤40 years old), in addition to the underlying mechanism. A total of 234 cases of CHD in young individuals were collected as the CHD group and 228 cases of healthy individuals as the control group. Peripheral blood was collected and the genotype of the eNOS G894T polymorphism was identified by polymerase chain reaction-restriction fragment length polymorphism, the gene frequency was calculated and the distributions of genotype and allele frequency between the two groups were compared. Bioinformatics tools were employed to analyze the differences in the local protein structures of the eNOS G894T polymorphism and the biological mechanism was preliminary discussed. The results demonstrated that there were significant differences in the distribution of genotype frequency and allele frequency of the eNOS G894T gene polymorphism between the CHD group and control group (P<0.05). The risk of CHD in GT and TT genotypes were higher compared with the GG genotype (P<0.05). The G894T polymorphism led to Glu298Asp mutation of encoded protein, which is within the active site of eNOS, and partial structures of the protein were converted from random coil to α‑helix. In conclusion, the eNOS G894T gene polymorphism was associated with the occurrence and development of CHD in young people. The potential mechanism is that the G894T polymorphism leads to altered protein structure, which affects the function of eNOS in generating nitric oxide and cardiovascular diastole. The results of the present study suggested a potential target gene for the prevention and treatment of CHD in young people (≤40 years old).