RAGE Gene Polymorphisms in Patients with Multiple Sclerosis

Rare and low-frequency coding genetic variants contribute to pediatric-onset multiple sclerosis

BACKGROUND

Rare genetic variants are emerging as important contributors to the heritability of multiple sclerosis (MS). Whether rare variants also contribute to pediatric-onset multiple sclerosis (POMS) is unknown.

OBJECTIVE

To test whether genes harboring rare variants associated with adult-onset MS risk (PRF1, PRKRA, NLRP8, and HDAC7) and 52 major histocompatibility complex (MHC) genes are associated with POMS.

METHODS

We analyzed DNA samples from 330 POMS cases and 306 controls from the US Network of Pediatric MS Centers and Kaiser Permanente Northern California for which Illumina ExomeChip genotypes were available. Using the gene-based method "SKAT-O," we tested the association between candidate genes and POMS risk.

RESULTS

After correction for multiple comparisons, one adult-onset MS gene (PRF1, p = 2.70 × 10^-3) and two MHC genes (BRD2, p = 5.89 × 10^-5 and AGER, p = 7.96 × 10^-5) were significantly associated with POMS. Results suggest these are independent of HLA-DRB1*1501.

CONCLUSION

Findings support a role for rare coding variants in POMS susceptibility. In particular, rare minor alleles within PRF1 were more common among individuals with POMS compared to controls while the opposite was true for rare variants within significant MHC genes, BRD2 and AGER. These genes would not have been identified by common variant studies, emphasizing the merits of investigating rare genetic variation in complex diseases.

Pathophysiology of RAGE in inflammatory diseases

The receptor for advanced glycation end products (RAGE) is a non-specific multi-ligand pattern recognition receptor capable of binding to a range of structurally diverse ligands, expressed on a variety of cell types, and performing different functions. The ligand-RAGE axis can trigger a range of signaling events that are associated with diabetes and its complications, neurological disorders, cancer, inflammation and other diseases. Since RAGE is involved in the pathophysiological processes of many diseases, targeting RAGE may be an effective strategy to block RAGE signaling.

Receptor of advanced glycation end product (RAGE) polymorphism and oxidative status in Hashimoto’s thyroiditis in Egyptian female patients: case control study

Background

Hashimoto's thyroiditis is the most widespread autoimmune illness targeting a specific organ. "Redox homeostasis" is achieved when the production of Reactive Oxygen Species and their elimination are in balance. Advanced glycation end products (AGEs) are formed when glucose and/or α-oxaloaldehydes react non-enzymatically with the amino groups of lipids, proteins, and DNA. Nowadays, many studies are concerned with AGEs, the polymorphisms of their receptors, and their association with increased risk of HT. However, few studies investigated the role of receptors of advanced glycation end product (RAGE) SNP in Egyptian females.

Objective

The goals of this investigation were to ascertain whether oxidative stress plasma malondialdehyde (MDA) and total antioxidant capacity (TAC) were associated with HT, in addition, to assess the association of RAGE polymorphisms (− 374 T > A and the − 429 T > C and Gly82Ser) with HT.

Subject and methods.

Our case–control study has 80 patients enrolled who have newly been diagnosed with HT and 80 age and sex-matched healthy female controls. Each participant underwent a thorough medical history, physical examination, and laboratory investigations, which included Genotyping of RAGE Gly82Ser, − 374 T > A and − 429 T > C using polymerase chain reaction-restriction fragment length polymorphisms (PCR–RFLP).

Results

Chi-square revealed a significant association regarding the distribution of RAGE (− 374 T < C) genotypes TT and CC between patients and control (P = 0.04). Non-significant associations regarding the distribution of Gly82Ser genotypes Gly/Gly, Gly/Ser, Ser/Ser were found between patients and control (P = 0.5), and non-significant associations related to − 429 T > C gene polymorphism were revealed. In addition, patients with HT had higher MDA and lower TCA compared with controls.

Conclusion

The elevated MDA and decreased TAC as an antioxidant may be one of several risk factors associated with the prevalence of HT in individuals with the − 429 T > C RAGE mutation polymorphism that is associated with an increased risk of HT in Egyptian females.

Association of RAGE rs1800624 and rs1800625 gene polymorphisms with predisposition to optic neuritis and optic neuritis together with multiple sclerosis

Optic neuritis (ON) is demyelinating acute inflammatory disease which affects the optic nerve. ON is classified as a typical (demyelinating) or an atypical (idiopathic). Patients often complain having a periocular pain or a visual loss. The main factor causing the optic neuritis is still unknown. It is believed that it might be a combination of genetic and environmental factors. As the optic neuritis is an inflammation disease, the RAGE gene was selected as it is a part of the inflammation process.

AIM

to determine the relation between RAGE rs1800624 and rs1800625 genotypes of patients who have a manifestation of optic neuritis and optic neuritis with multiple sclerosis together in Lithuanian population and visual acuity recovery.

OBJECTIVES

patients with optic neuritis and healthy controls individuals were examined. Genotyping was carried out by using the instrument of real-time polymerase chain reaction called StepOnePlus (AppliedBiosystems). Statistical analysis was performed using IBM SPSS Statistics 20.0 software and free PLINK software (version 1.07).

RESULTS

Results indicate that rs1800624 polymorphism is not statistically significant in optic neuritis manifestation (p = .392), while rs1800625 GG genotype is associated with 7.5-fold increased odds of ON development under the codominant model (OR = 7.5; 95% CI:1.796-31.313; p = .006) and with 6.9-fold increased odds under the recessive model OR = 6.862; 95% CI:1.665-28.288; p = .008); and each allele G is associated with 1.9-fold increased odds of ON development under the additive model (OR = 1.879; 95% CI:1.149-3.072; p = .012). The haplotype containing A-G alleles in rs1800624 and rs1800625 was statistically significantly associated with increased risk for ON development (χ2 = 13.23; p < .001). Both polymorphisms do not have statistically significant importance in relation to visual acuity recovery.

CONCLUSIONS

RAGE rs1800625 AA genotype decreases the risk of optic neuritis. The single nucleotide polymorphisms RAGE rs1800624 and rs1800625 do not have a statistically significant importance in relation with visual acuity recovery.

Genetic and Molecular Biology of Multiple Sclerosis Among Iranian Patients: An Overview

Multiple sclerosis (MS) is one if the common types of autoimmune disorders in developed countries. Various environmental and genetic factors are associated with initiation and progression of MS. It is believed that the life style changes can be one of the main environmental risk factors. The environmental factors are widely studied and reported, whereas minority of reports have considered the role of genetic factors in biology of MS. Although Iran is a low-risk country in the case of MS prevalence, it has been shown that there was a dramatically rising trend of MS prevalence among Iranian population during recent decades. Therefore, it is required to assess the probable MS risk factors in Iran. In the present study, we summarized all of the reported genes until now which have been associated with MS susceptibility among Iranian patients. To clarify the probable molecular biology of MS progression, we categorized these reported genes based on their cellular functions. This review paves the way of introducing a specific population-based diagnostic panel of genetic markers among the Iranian population for the first time in the world.

RAGE polymorphisms and oxidative stress levels in Hashimoto's thyroiditis

BACKGROUND

Polymorphisms of the receptor for advanced glycation end products (RAGE) gene have been studied in various autoimmune disorders, but not in Hashimoto's thyroiditis. Also, increased oxidative stress has been described in patients with Hashimoto's thyroiditis. The aim of this study was to investigate the possible role of two common RAGE polymorphisms (-429T>C, -374T>A) in Hashimoto's thyroiditis; in parallel, we studied oxidative stress levels.

MATERIALS AND METHODS

A total of 300 consecutive euthyroid women were examined and classified into three groups: Hashimoto's thyroiditis with treatment (n = 96), Hashimoto's thyroiditis without treatment (n = 109) and controls (n = 95). For a rough evaluation of oxidative stress, total lipid peroxide levels in serum were measured. The -429T>C AluI and -374T>A MfeI polymorphisms of RAGE were studied in genomic DNA.

RESULTS

Significant association of the RAGE system with Hashimoto's thyroiditis was found only with regard to the prevalence of the -429T>C, but not with -374T>A polymorphism. The levels of oxidative stress were significantly elevated in Hashimoto's thyroiditis patients under treatment. Further analysis demonstrated that an oxidative stress cut-off value of 590 μmol/L is associated with an increased risk of progression of Hashimoto's thyroiditis from euthyroidism to hypothyroidism; this risk is further increased in carriers of the RAGE -429T>C polymorphism.

CONCLUSIONS

Our findings indicate that both examined risk factors may be implicated in the occurrence of Hashimoto's thyroiditis, but this covers only a fraction of the pathophysiology of the disease.

Association of rs1738074 polymorphism of TAGAP gene with susceptibility to multiple sclerosis in the Iranian population

Multiple sclerosis (MS) is one of the most common diseases of the central nervous system (CNS) in the Iranian population. To date, association of many genes with the prevalence and progression of the disease have been investigated. In the present study, the impact of rs1738074 single nucleotide polymorphism (SNP) in the TAGAP gene (TAGAP rs1738074) on the risk of MS was evaluated in a sample of the Iranian population. In a case control study, genotyping was performed on 300 patients and normal individuals. The data were analyzed using Pearson's chi-square test. The results showed a significant difference in the SNP frequency between case and control groups (p-value=0.049). The genotype frequencies of TT, TC and CC in patients were 10.67%, 51.33% and 38%, respectively, and in normal individuals were 20.66%, 42.67% and 36.67%, respectively. The results showed a significant difference in the genotype frequency of T/T between the patient and control groups (p<0.05). Interestingly, individuals with T/T genotype were estimated to be less susceptible to MS ((p-value=0.025), Fisher's exact test), odd ratio was 2.18 (controls versus MS patients) with 95% CI: 1.137-4.187. The results suggested that TAGAP rs1738074 polymorphism could be considered as a risk factor in the prevalence of MS in the Iranian population.

Methylglyoxal-Derived Advanced Glycation Endproducts in Multiple Sclerosis

Multiple sclerosis (MS) is a demyelinating disease of the central nervous system (CNS). The activation of inflammatory cells is crucial for the development of MS and is shown to induce intracellular glycolytic metabolism in pro-inflammatory microglia and macrophages, as well as CNS-resident astrocytes. Advanced glycation endproducts (AGEs) are stable endproducts formed by a reaction of the dicarbonyl compounds methylglyoxal (MGO) and glyoxal (GO) with amino acids in proteins, during glycolysis. This suggests that, in MS, MGO-derived AGEs are formed in glycolysis-driven cells. MGO and MGO-derived AGEs can further activate inflammatory cells by binding to the receptor for advanced glycation endproducts (RAGE). Recent studies have revealed that AGEs are increased in the plasma and brain of MS patients. Therefore, AGEs might contribute to the inflammatory status in MS. Moreover, the main detoxification system of dicarbonyl compounds, the glyoxalase system, seems to be affected in MS patients, which may contribute to high MGO-derived AGE levels. Altogether, evidence is emerging for a contributing role of AGEs in the pathology of MS. In this review, we provide an overview of the current knowledge on the involvement of AGEs in MS.

The immunobiology of the receptor of advanced glycation end-products: trends and challenges

Pattern-recognition receptors have been highly conserved in evolution. They recognize danger signals including both pathogen- and damage-associated molecular patterns, also known as alarmins. Several signaling pathways leading to an inflammatory reaction as part of an effective defensive response, are thus triggered. RAGE, a receptor initially considered for advanced glycation end-products, is also known to be activated by several danger signals, thus functioning as a pattern-recognition receptor. As a new member of this family, attempts to unraveling its functioning show that RAGE activation not only results in innate immune response but also contributes to promote and shape the acquired immune reaction. As reported for other members of the family, RAGE presents many polymorphic variants and additional studies are needed to elucidate its significance in immune response and disease susceptibility. Here we describe recent advances unraveling RAGE functions, as well as its significance and challenges in immunobiology.

A functional p.82G>S polymorphism in the RAGE gene is associated with multiple sclerosis in the Chinese population

BACKGROUND

The receptor for advanced glycation end products (RAGE) and its proinflammatory ligand, S100-calgranulins, are critically implicated in the pathological progression of multiple sclerosis (MS). A functional polymorphism within the V-type immunoglobulin domain of RAGE gene, p.82G>S (c.557G>A), has been shown to affect ligand binding affinity and thus may affect susceptibility to MS.

METHODS

The RAGE p.82G>S polymorphism was genotyped in 144 MS patients and 156 healthy controls using polymerase chain reaction - restriction fragment length polymorphism. A replication study was performed on a second cohort comprising 138 patients and 150 controls. The relationship between the RAGE p.82G>S polymorphism and circulating levels of soluble RAGE (sRAGE), a secreted decoy receptor against RAGE signaling, was also investigated.

RESULTS

In both initial and replication cohorts, an increased MS risk was detected in RAGE p.82G>S variant allele carriers (odds ratio [OR] = 1.786, p = 0.0134 and OR = 1.732, p = 0.0210, respectively). This association signal persisted in subgroups of women and patients with relapsing-remitting MS. Moreover, compared with the wild-type 82GG carriers, carriers of the variant allele presented a faster progression of disability and a reduced serum sRAGE level.

CONCLUSIONS

The present study provides preliminary evidence that the gain-of-function p.82G>S polymorphism in the RAGE gene is associated with an increased risk of MS in the Chinese population.