Association study of polymorphisms in the receptor for advanced glycation end-products (RAGE) gene with susceptibility and prognosis of heart failure

The role of miRNA-339-5p in the function of vascular endothelial progenitor cells in patients with PCOS

RESEARCH QUESTION

miRNA-339 participates in diseases with endothelial progenitor cell (EPC) dysfunction. What is the role of miRNA-339-5p in EPC of polycystic ovary syndrome (PCOS)?

DESIGN

Clinical data were collected from 76 controls and 84 PCOS patients. Noradrenaline, asymmetric dimethylarginine (ADMA), advanced glycation end products (AGE) and silent information regulator 1 (SIRT1) in the serum were measured. The functions of EPC and the expressions of PI3K, AKT, SIRT1 and PGC-1α in EPC before and after transfection with miRNA-339-5p mimic or miRNA-339-5p inhibitor were compared.

RESULTS

Serum concentrations of noradrenaline, ADMA and AGE were significantly higher (P = 0.009, P = 0.044, P < 0.001) and the SIRT1 concentration was significantly lower (P < 0.001) in PCOS patients, especially obese ones (P = 0.034, P = 0.032, P < 0.001, P = 0.023) than in the control group. When compared with the controls, proliferation of the EPC was slightly lower (without a significant difference), the migration and tubular formation were significantly decreased (P = 0.037, P = 0.011), the expression of miRNA-339-5p in EPC was significantly higher (P = 0.035) and the expressions of PI3K, AKT, SIRT1 and PGC-1α were significantly lower in the PCOS group (mRNA: P = 0.033, P = 0.027, P = 0.027, P = 0.032; protein: P = 0.036, P = 0.028, P = 0.039, P = 0.023). After transfection, the functions of EPC from PCOS patients were best in the miRNA-339-5p inhibitor group, and weakest in the miRNA-339-5p mimic group. The miRNA-339-5p inhibitor group had higher protein expressions of PI3K, AKT and SIRT1 but lower expression of PGC-1α in PCOS patients (P < 0.001, P = 0.030, P = 0.047, P = 0.003). Similar results were obtained from the controls after transfection.

CONCLUSION

Increased sympathetic excitation and damage to EPC were observed in PCOS patients, especially obese ones. Up-regulated miRNA-339-5p could inhibit the function of EPC by inhibiting the PI3K/AKT and SIRT1/PGC-1α signalling pathways.

Receptor for advanced glycation end products gene polymorphisms in cardiac syndrome X

Endothelial and microvascular dysfunction serve important roles in the formation and pathogenesis of cardiac syndrome X (CSX). Expression of receptor for advanced glycation end products (RAGE) is suggested to be increased in several conditions, including diabetes, inflammation and vascular diseases. In the present study, RAGE gene polymorphisms in patients with CSX and healthy controls were investigated. A total of 114 patients, diagnosed with CSX using coronary angiography results following complaints of angina and objective ischemia, and 103 healthy controls participated in the study. Whether there was a difference in genotype distributions of RAGE gene -374T/A, -429T/C and Glys82Ser polymorphisms between patients with CSX and healthy controls was investigated. Following DNA isolation from blood samples of the participants, the polymorphic regions were examined by quantitative polymerase chain reaction, and the genotyping results were statistically analyzed. When the genotypic distributions of -374T/A, -429T/C and Gly82Ser polymorphisms were investigated in patients with CSX and healthy controls, no statistically significant differences were identified between the two groups (P>0.05). Likewise, no statistically significant differences were observed in the allelic distributions of all 3 polymorphic regions (P>0.05). To the best of our knowledge, the present study also investigated the association between CSX and RAGE gene polymorphisms for the first time. No statistically significant differences in RAGE gene polymorphisms between the CSX and control groups were observed. We hypothesized that significant results may be obtained by increasing the numbers of patients and healthy controls in future studies.

Pathological Implications of Receptor for Advanced Glycation End-Product (AGER) Gene Polymorphism

The receptor for advanced glycation end-products (RAGE) is a cell surface transmembrane multiligand receptor, encoded by the AGER gene. RAGE presents many transcripts, is expressed mainly in the lung, and involves multiple pathways (such as NFκB, Akt, p38, and MAP kinases) that initiate and perpetuate an unfavorable proinflammatory state. Due to these numerous functional activities, RAGE is implicated in multiple diseases. AGER is a highly polymorphic gene, with polymorphisms or SNP (single-nucleotide polymorphism) that could be responsible or co-responsible for disease development. This review was designed to shed light on the pathological implications of AGER polymorphisms. Five polymorphisms are described: rs2070600, rs1800624, rs1800625, rs184003, and a 63 bp deletion. The rs2070600 SNP may be associated with the development of human autoimmune disease, diabetes complications, cancer, and lung diseases such as chronic obstructive pulmonary disease and acute respiratory distress syndrome. The rs1800624 SNP involves AGER gene regulation and may be related to reduced risk of heart disease, cancer, Crohn's disease, and type 1 diabetes complications. The rs1800625 SNP may be associated with the development of diabetic retinopathy, cancer, and lupus but may be protective against cardiovascular risk. The rs184003 SNP seems related to coronary artery disease, breast cancer, and diabetes. The 63 bp deletion may be associated with reduced survival from heart diseases during diabetic nephropathy. Here, these potential associations between AGER polymorphisms and the development of diseases are discussed, as there have been conflicting findings on the pathological impact of AGER SNPs in the literature. These contradictory results might be explained by distinct AGER SNP frequencies depending on ethnicity.

Impact of advanced glycation end products (AGEs) signaling in coronary artery disease

Coronary artery disease remains the leading cause of mortality in adult diabetic population with however, a high predominance also in non-diabetic subjects. In search of common molecular mechanisms and metabolic by-products with potential pathogenic role, increased advanced glycation end products (AGEs) present a critical biomarker for CAD development in both cases. Interaction of AGEs with their transmembrane cell receptor, RAGE in endothelial and smooth muscle cells as well as in platelets, activates intracellular signaling that leads to endothelial injury, modulation of vascular smooth muscle cell function and altered platelet activity. Furthermore, tissue accumulation of AGEs affects current treatment approaches being involved in stent restenosis. The present review provides an update of AGE-induced molecular mechanisms involved in CAD pathophysiology while it discusses emerging therapeutic interventions targeting AGE reduction and AGE-RAGE signaling with beneficial clinical outcome.

The Association Between Variants of Receptor for Advanced Glycation End Products (RAGE) Gene Polymorphisms and Age-Related Macular Degeneration

Background

Age-related macular degeneration (AMD) is the leading cause of blindness in people aged 65 years and older in developed countries. The pathogenesis of AMD has been linked to mechanisms involving inflammation, oxidative stress, and basal laminar deposit formation between retinal pigment epithelium (RPE) cells and the basal membrane, caused by advanced glycation end products (AGEs). AGEs are implicated in the pathogenesis of AMD through the AGE-and receptor for AGE (RAGE) interaction, which can be altered by polymorphisms of the RAGE gene. We examined RAGE rs1800624 and rs1800625 gene polymorphisms contributing to AMD development.

Material/Methods

The study enrolled 300 patients with early AMD, 300 patients with exudative AMD, and 800 healthy controls. The genotyping was carried out using the RT-PCR method.

Results

The analysis of two single nucleotide polymorphisms (SNPs) in the RAGE gene showed that rs1800624 was associated with a 1.6-fold decreased risk for exudative AMD under the dominant model after adjustment for age (OR=0.616; 95% CI: 0.394–0.963; p=0.034) and each copy of allele T at rs1800624 was associated with a 1.4-fold decreased risk for exudative AMD development under the additive model after adjustment for age (OR=0.701; 95% CI: 0.510–0.962; p=0.028). Analysis revealed that the rs1800625 allele G at rs1800625 was associated with a 1.5-fold increased risk for exudative AMD after adjustment for age (OR=1.545; 95% CI: 1.003–2.379; p=0.048). These results suggested that the allele G at rs1800625 was a risk-allele for exudative AMD development. In haplotype analysis, A-G haplotype was significantly more frequently observed in exudative AMD patients compared to healthy controls (3.3% versus 1.4%, p=0.035).

Conclusions

We revealed a significant association between RAGE gene rs1800624 and rs1800625 polymorphisms and AMD risk. We considered T allele at rs1800624 to be protective against AMD development, while allele G at rs1800625 was considered to be a marker of poor prognosis in AMD development.

Genetic Variants of the Receptor for Advanced Glycation End-products in Susceptibility to Type 2 Diabetes Mellitus in Primary Hypertensive Patients

Diabetes mellitus is frequently comorbid with hypertension, which is approximately twice as common as diabetes mellitus in China. We designed a case-control association study to inspect the susceptibility of the receptor for advanced glycation end-products (RAGE) gene 6 variants to type 2 diabetes mellitus (T2DM) in 2199 patients with primary hypertension (1252 diabetic cases and 947 nondiabetic controls). The genotypes/alleles of −429T > C and 82Gly > Ser variants differed significantly between the two groups, and their associations with T2DM were significant after Bonferroni correction. Two variants, −374T > A and I/D, showed only marginal associations with T2DM. Haplotype analysis of above 4 significant variants indicated that a low-penetrance haplotype simultaneously bearing −429C and 82Ser alleles was overrepresented in cases relative to controls (4.75% vs. 1.72%, P < 0.001). Moreover, the predictive capability of 6 variants was significantly superior to available risk factors, with better goodness-of-fit. A predictive nomogram of 4 baseline risk factors and 2 variants of statistical significance was structured, with a good predictive accuracy (C-index = 0.761, P < 0.001). Taken together, our findings highlighted a contributory role of the RAGE gene, especially its two functional variants −429T > C and 82Gly > Ser, in susceptibility to T2DM in primary hypertensive patients, which may aid early detection and risk assessment for high-risk individuals.

Relationship between RAGE gene polymorphisms and cardiovascular disease prognosis in the Chinese Han population

Cardiovascular disease (CVD) is the leading cause of death in China. This study aimed to investigate whether RAGE gene polymorphisms are associated with the prognosis of various cardiovascular diseases in the Chinese Han population. This study was conducted from July 2004 to December 2005 and a total of 425 subjects from Guangdong province were enrolled. Genotyping of the three polymorphisms (-429T/C, 1704G/T, and G82S) in the RAGE gene was performed with polymerase chain reaction/restriction fragment length polymorphism (PCR-RFLP). Patients were followed for 6.5 years to watch for the development of cardiovascular events and mortality. Subjects with the S mutation of the G82S polymorphism had a significantly higher risk of all-cause mortality and acute myocardial infarction (AMI) than did those with wild-type homozygosity. Logistic regression analysis and Kaplan-Meier analysis all revealed that the G82S polymorphism of the RAGE gene was associated with a significantly increased risk of all-cause mortality and AMI. However, the -429T/C and 1704G/T polymorphisms were not shown to have any effect on prognosis. In conclusion, the G82S variant of the RAGE gene was significantly associated with an increased risk of all-cause mortality and AMI in the Chinese Han population.

Clinical use of high mobility group box 1 and the receptor for advanced glycation end products in the prognosis and risk stratification of heart failure: a literature review

Heart failure (HF) is a clinical syndrome that represents the end stage of heart disease and remains the leading cause of morbidity and mortality worldwide. As heart failure mortality rates remain elevated, additional biomarkers that facilitate early detection or risk stratification in HF is of particularly great interest. High mobility group box 1 (HMGB1) and receptor for advanced glycation end products (RAGE) cause the activation of intracellular signaling, gene expression, and production of inflammatory cytokines and have been linked to many inflammatory disease states such as diabetes mellitus and atherosclerosis. Few studies have investigated their role in the pathophysiology of HF and any significant correlation remains uncertain. Review of the available literature discussing HMGB1 and RAGE clinical values as independent prognostic variables in HF resulted in the inclusion of 11 studies, which enrolled a total of 2025 heart failure patients. Overall, the data suggests a statistically significant positive correlation between RAGE and HF, with increasing RAGE levels associated with increasing New York Heart Association (NYHA) functional class of heart failure. HMGB1 correlations were not as extensively studied, but there is evidence that both HMGB1 and RAGE have a definite potential as biomarkers for the prognosis and risk stratification of HF patients.

Functional promoter polymorphisms of the receptor for advanced glycation end products in children and adolescents with type 1 diabetes

RAGE promoter polymorphisms are associated with increases in RAGE expression. A case-control association study was conducted involving a Euro-Brazilian population of children and adolescents with type 1 diabetes (n = 90) and healthy controls (n = 105), which were matched by sex and age. Genotyping by PCR-RFLP the -429T>C (rs1800625), -374T>A (rs1800624), and 63 bp deletion/insertion (-407 to -345 bp) showed no significant differences (P > 0.05) between the groups.