RAGE splicing variants in mammals. Methods Mol Biol. 2013;963:265-276. [PMID: 23296616 DOI: 10.1007/978-1-62703-230-8_16]

Receptor for advanced glycation end-products: Biological significance and imaging applications

The receptor for advanced glycation end-products (RAGE or AGER) is a transmembrane, immunoglobulin-like receptor that, due to its multiple isoform structures, binds to a diverse range of endo- and exogenous ligands. RAGE activation caused by the ligand binding initiates a cascade of complex pathways associated with producing free radicals, such as reactive nitric oxide and oxygen species, cell proliferation, and immunoinflammatory processes. The involvement of RAGE in the pathogenesis of disorders such as diabetes, inflammation, tumor progression, and endothelial dysfunction is dictated by the accumulation of advanced glycation end-products (AGEs) at pathologic states leading to sustained RAGE upregulation. The involvement of RAGE and its ligands in numerous pathologies and diseases makes RAGE an interesting target for therapy focused on the modulation of both RAGE expression or activation and the production or exogenous administration of AGEs. Despite the known role that the RAGE/AGE axis plays in multiple disease states, there remains an urgent need to develop noninvasive, molecular imaging approaches that can accurately quantify RAGE levels in vivo that will aid in the validation of RAGE and its ligands as biomarkers and therapeutic targets. This article is categorized under: Diagnostic Tools > In Vivo Nanodiagnostics and Imaging Diagnostic Tools > Biosensing.

Pathomechanisms of Diabetic Kidney Disease

The worldwide occurrence of diabetic kidney disease (DKD) is swiftly rising, primarily attributed to the growing population of individuals affected by type 2 diabetes. This surge has been transformed into a substantial global concern, placing additional strain on healthcare systems already grappling with significant demands. The pathogenesis of DKD is intricate, originating with hyperglycemia, which triggers various mechanisms and pathways: metabolic, hemodynamic, inflammatory, and fibrotic which ultimately lead to renal damage. Within each pathway, several mediators contribute to the development of renal structural and functional changes. Some of these mediators, such as inflammatory cytokines, reactive oxygen species, and transforming growth factor β are shared among the different pathways, leading to significant overlap and interaction between them. While current treatment options for DKD have shown advancement over previous strategies, their effectiveness remains somewhat constrained as patients still experience residual risk of disease progression. Therefore, a comprehensive grasp of the molecular mechanisms underlying the onset and progression of DKD is imperative for the continued creation of novel and groundbreaking therapies for this condition. In this review, we discuss the current achievements in fundamental research, with a particular emphasis on individual factors and recent developments in DKD treatment.

Do advanced glycation end products contribute to food allergy?

Sugars can bind non-enzymatically to proteins, nucleic acids or lipids and form compounds called Advanced Glycation End Products (AGEs). Although AGEs can form in vivo, factors in the Western diet such as high amounts of added sugars, processing methods such as dehydration of proteins, high temperature sterilisation to extend shelf life, and cooking methods such as frying and microwaving (and reheating), can lead to inordinate levels of dietary AGEs. Dietary AGEs (dAGEs) have the capacity to bind to the Receptor for Advanced Glycation End Products (RAGE) which is part of the endogenous threat detection network. There are persuasive epidemiological and biochemical arguments that correlate the rise in food allergy in several Western countries with increases in dAGEs. The increased consumption of dAGEs is enmeshed in current theories of the aetiology of food allergy which will be discussed.

Advanced Glycation End Products and Diabetes Mellitus: Mechanisms and Perspectives

Persistent hyperglycemic state in type 2 diabetes mellitus leads to the initiation and progression of non-enzymatic glycation reaction with proteins and lipids and nucleic acids. Glycation reaction leads to the generation of a heterogeneous group of chemical moieties known as advanced glycated end products (AGEs), which play a central role in the pathophysiology of diabetic complications. The engagement of AGEs with its chief cellular receptor, RAGE, activates a myriad of signaling pathways such as MAPK/ERK, TGF-β, JNK, and NF-κB, leading to enhanced oxidative stress and inflammation. The downstream consequences of the AGEs/RAGE axis involve compromised insulin signaling, perturbation of metabolic homeostasis, RAGE-induced pancreatic beta cell toxicity, and epigenetic modifications. The AGEs/RAGE signaling instigated modulation of gene transcription is profoundly associated with the progression of type 2 diabetes mellitus and pathogenesis of diabetic complications. In this review, we will summarize the exogenous and endogenous sources of AGEs, their role in metabolic dysfunction, and current understandings of AGEs/RAGE signaling cascade. The focus of this review is to recapitulate the role of the AGEs/RAGE axis in the pathogenesis of type 2 diabetes mellitus and its associated complications. Furthermore, we present an overview of future perspectives to offer new therapeutic interventions to intervene with the AGEs/RAGE signaling pathway and to slow down the progression of diabetes-related complications.

Implication of RAGE Polymorphic Variants in COPD Complication and Anti-COPD Therapeutic Potential of sRAGE

Chronic obstructive pulmonary disease (COPD) is a slowly progressive and poorly reversible airway obstruction disease. It is caused either alone or in combination of emphysema, chronic bronchitis (CB), and small airways disease. COPD is thought to be a multi-factorial disorder in which genetic susceptibility, environmental factors and tobacco exposure could be doubly or simultaneously implicated. Available medicines against COPD include anti-inflammatory drugs, such as β2-agonists and anticholinergics, which efficiently reduce airflow limitation but are unable to avert disease progression and mortality. Advanced glycation end products (AGE) and their receptors i.e. receptor for advanced glycation end products (RAGE) are some molecules that have been implicated in the complication of COPD. Several RAGE single nucleotide polymorphic (SNP) variants are produced by the mammalian cells. Based on the ethnicity some SNPs aggravate the COPD severity. Mammalian cells produce several alternative RAGE splice variants including a soluble RAGE (sRAGE) and an endogenous soluble RAGE (esRAGE). Both of these act as decoy receptor and thus may help to arrest the COPD complications. Several lines of evidences indicate a decreased level of sRAGE in the COPD subjects. One of the new strategies to reduce COPD complication may be sRAGE therapeutic administration to the COPD subjects. This comprehensive discussion sheds light on the role of RAGE and its polymorphic variants in the COPD complication along with sRAGE therapeutic significance in the COPD prevention.

Elevated Expression of the RAGE Variant-V in SCLC Mitigates the Effect of Chemotherapeutic Drugs

Simple Summary

Radiomimetic drugs induce extensive genotoxic insults to their target cells. Irreparable DNA damage leaves cells with the choice between a program leading to cell death or senescence, but not DNA repair. Among the challenges of an advanced stage of small cell lung carcinoma (SCLC), the resistance to radiomimetic drugs is the most prominent one. In SCLC, the initial chemotherapeutic treatment primes cell to modify their DNA repair and cell cycle regulatory systems, using alternative but highly efficient forms of DNA repair and auxiliary factors. This modulated system now bypasses several regulatory controls. Thus, at this stage, cells become resistant to any beneficial effects of chemotherapeutic drugs. In the present study, we observed that variant-V of the receptor for advanced glycation end-products (RAGE) is abundantly expressed in advancing and metastasizing SCLC. Therefore, it may serve as a potential target for specific therapeutic interventions directed to SCLC.

Abstract

Small cell lung carcinoma (SCLC) is a highly aggressive malignancy with a very high mortality rate. A prominent part of this is because these carcinomas are refractory to chemotherapies, such as etoposide or cisplatin, making effective treatment almost impossible. Here, we report that elevated expression of the RAGE variant-V in SCLC promotes homology-directed DNA DSBs repair when challenged with anti-cancer drugs. This variant exclusively localizes to the nucleus, interacts with members of the double-strand break (DSB) repair machinery and thus promotes the recruitment of DSBs repair factors at the site of damage. Increased expression of this variant thus, promotes timely DNA repair. Congruently, the tumor cells expressing high levels of variant-V can tolerate chemotherapeutic drug treatment better than the RAGE depleted cells. Our findings reveal a yet undisclosed role of the RAGE variant-V in the homology-directed DNA repair. This variant thus can be a potential target to be considered for future therapeutic approaches in advanced SSLC.

Identification of novel advanced glycation end products receptor gene variants associated with colorectal cancer in Tunisians: A case-control study

A central role for advanced glycation end products (AGE) and their receptor (RAGE) in the pathogenesis of multiple cancer types, including colorectal cancer (CRC) was reported. We investigated the association between CRC and rs2853807, rs77170610, rs184003, rs1035798, rs2070600, rs1800684, rs1800624, and rs1800625 RAGE gene (AGER) polymorphic variants. Study subjects comprised 293 CRC patients [186 colon cancer (CC) and 107 rectal cancer (RC)] patients), and 264 age-, gender-, BMI-, and ethnicity-matched controls. Minor allele frequency (MAF) of rs77170610 and rs1800625 were significantly lower, while MAF of rs1035798 was significantly higher in CRC patients compared to control subjects, which was associated with reduced and increased risk of CRC, respectively; MAF of the remaining variants was comparable between CRC patients and controls. Significant difference in the distribution of rs2853807 and rs77170610 genotypes was seen between CRC patients and controls, with both variants associated with decreased risk of CRC. Comparison of the distribution of minor allele-carrying genotypes in CC and RC patient subgroups revealed lack of significant difference in the distribution of these genotypes between the patient subgroups. In view of the lack of LD between rs2853807 and rs77170610 with other variants, six-locus (rs184003, rs1035798, rs2070600, rs1800684, rs1800624, rs1800625) haplotypes were constructed. Haplotype analysis did not identify any specific 6-locus AGER haplotype associated with CRC. In conclusion, AGER gene rs2853807 and rs77170610 variants rs77170610 are associated with altered risk of CRC in Tunisians, but with no discrimination between CC and RC types.

miR-21-3p regulates AGE/RAGE signalling and improves diabetic atherosclerosis

To explore the effects of miR-21-3p on diabetic atherosclerosis. Using enzyme-linked immunosorbent assay (ELISA), we also detected the levels of soluble receptor for advanced glycation endproducts RAGE (sRAGE) in the cellular supernatant of vascular endothelial cells after transfecting them with adenovirus vector having miR-21-3p mimic or inhibitor. We found decrease in the expression levels of miR-21-3p in vascular endothelial cells (VECs) induced by high-concentration glucose. We also observed that the introduction of miR-21-3p mimic significantly increased the expression of ADAM10 in the VECs. Similarly, significantly higher levels of sRAGE were found in the cultured supernatant after administration of miR-21-3p mimic in human vein endothelial cells. The production of reactive oxygen species and expression of inflammatory cytokines in VECs induced by LPS and high-concentration glucose were significantly decreased after administration of miR-21-3p. in vivo studies revealed that intravenous injection of miR-21-3p at regular intervals would reduce the area of atherosclerotic lesion and elevate the serum levels of sRAGE in atherosclerotic diabetic mice. miR-21-3p may be beneficial in diabetic atherosclerosis by promoting the cleaved form of sRAGE and inhibition of RAGE/NADPH oxidase signalling depending on the increased expression of ADAM10. SIGNIFICANCE OF THE STUDY: We identified a novel microRNA, miR-21-3p, which is characteristically at elevated levels in serum derived from diabetic patients and responsible for target degradation of ADAM10 mRNA. Further, we show that miR-21-3p aggravates the atherosclerotic lesion via dysfunction of the ectodomain shedding of molecular binding RAGE in the diabetic atherosclerotic mice.

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.

The Astrocytic S100B Protein with Its Receptor RAGE Is Aberrantly Expressed in SOD1G93A Models, and Its Inhibition Decreases the Expression of Proinflammatory Genes

Neuroinflammation is one of the major players in amyotrophic lateral sclerosis (ALS) pathogenesis, and astrocytes are significantly involved in this process. The astrocytic protein S100B can be released in pathological states activating the receptor for advanced glycation end products (RAGE). Different indications point to an aberrant expression of S100B and RAGE in ALS. In this work, we observed that S100B and RAGE are progressively and selectively upregulated in astrocytes of diseased rats with a tissue-specific timing pattern, correlated to the level of neurodegeneration. The expression of the full-length and soluble RAGE isoforms could also be linked to the degree of tissue damage. The mere presence of mutant SOD1 is able to increase the intracellular levels and release S100B from astrocytes, suggesting the possibility that an increased astrocytic S100B expression might be an early occurring event in the disease. Finally, our findings indicate that the protein may exert a proinflammatory role in ALS, since its inhibition in astrocytes derived from SOD1^G93A mice limits the expression of reactivity-linked/proinflammatory genes. Thus, our results propose the S100B-RAGE axis as an effective contributor to the pathogenesis of the disease, suggesting its blockade as a rational target for a therapeutic intervention in ALS.

Garlic decreases liver and kidney receptor for advanced glycation end products expression in experimental diabetes

The up-regulation of the receptor for advanced glycation end products (RAGE) has been implicated as a major mediator in the development and progression of diabetic nephropathy and hepatic fibrogenesis. The present study was designed to investigate the potential of garlic (Allium sativum L.) to modulate the level of expression of RAGE in renal and hepatic tissues of diabetic rats. Three groups of rats were studied after 8 weeks following diabetes induction: normal, streptozotocin-induced diabetic (control diabetic), and garlic-treated diabetic rats. A polyclonal antibody of proven specificity to RAGE indicated in immunohistochemical assays that RAGE labeling was significantly increased in renal and hepatic tissues of control diabetic rats compared to the normal group. The increased RAGE labeling involved mesangial cells in glomeruli exhibiting signs of mesangial expansion, mesangial nodule formation and glomerulosclerosis. In the liver, a significant up-regulation of RAGE was observed in hepatocytes and bile ducts and vessels in portal tracts. In 2-dimensional Western blots, RAGE expression in both tissues was dominated by heterogeneous charge variants, represented by 46-50kDa isoforms with more basic pIs compared to their counterparts in normal rats. Compared to control diabetic rats, RAGE labeling in the garlic-treated diabetic group was significantly reduced throughout renal and hepatic regions and was marked by the expression of 43-50kDa acidic charge variants comparable to those observed in normal rats. The capacity of garlic to modulate diabetes-induced up-regulation of selective RAGE polymorphic variants may be implicated in attenuating the detrimental consequences of excessive RAGE signaling manifested by diabetes-associated disorders.

Effects of RAGE Gene Polymorphisms on the Risk and Progression of Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is a common malignancy of the liver, whose heterogeneous incidence reflects genetic variations among individuals in the main risk factors. The receptor for advanced glycosylation endproducts (RAGE) is a multiligand receptor and known to be implicated in various pathogenic conditions, such as diabetes, inflammatory disorder, Alzheimer disease, and cancer. In this study, the impact of RAGE gene polymorphisms on the susceptibility to hepatocarcinogenesis was explored. Four single-nucleotide polymorphisms (SNPs), rs184003 (1704G > T), rs1800624 (-374T > A), rs1800625 (-429T > C), and rs2070600 (Gly82Ser), as well as 1 gene polymorphism of RAGE gene, a 63 bp deletion allele (-407 to -345) were analyzed between 300 cancer-free subjects and 265 HCC cases. We detected a significant association of rs1800625 with the increased risk of HCC (odds ratio [OR], 2.565; 95% confidence interval [CI], 1.492-4.409 and adjusted odds ratio [AOR], 2.568; 95% CI, 1.418-4.653). However, patients who possess at least 1 polymorphic allele of rs1800625 are less prone to develop late-stage (stage III/IV, OR, 0.502; 95% CI, 0.243-1.037; P = 0.059 and AOR, 0.461; 95% CI, 0.219-0.970; P = 0.041) and large-size tumors (OR, 0.398; 95% CI, 0.183-0.864; P = 0.017 and AOR, 0.351; 95% CI, 0.157-0.781; P = 0.010). Furthermore, individuals bearing specific haplotypes of 4 RAGE SNPs tested are more inclined to have HCC. In conclusion, our data suggest a correlation of RAGE gene polymorphism rs1800625 with the early stage of liver tumorigenesis and implicate its protective role in the progression of HCC.

RAGE gene polymorphism and environmental factor in the risk of oral cancer

Oral squamous cell carcinoma is a common neoplasm that is known to be causally associated with genetic factors and environmental carcinogens. The receptor for advanced glycosylation endproducts (RAGE) is a transmembrane protein of the immunoglobulin superfamily with broad specificity for multiple ligands, and it has been shown to play vital roles in several pathophysiologic processes, including diabetes, Alzheimer disease, renal disease, cardiovascular disease, and cancer. The present study aimed to assess the influences of RAGE gene polymorphisms, combined with environmental carcinogens on the predisposition to oral tumorigenesis. Five polymorphisms of the RAGE gene-including -374T>A (rs1800624), -429T>C (rs1800625), 1704G>T (rs184003), Gly82Ser (rs2070600), and a 63-bp deletion allele (-407 to -345)-were examined from 592 controls and 618 patients with oral cancer. We found that individuals carrying the polymorphic allele of rs1800625 are more susceptible to oral cancer (odds ratio [OR], 1.899; 95% confidence interval [CI], 1.355 to 2.661; adjusted OR [AOR], 2.053; 95% CI, 1.269 to 3.345) after adjustment for age, sex, betel nut chewing, and tobacco consumption. Moreover, we observed a significant association of rs1800625 variants with late-stage tumors (stage III/IV, OR, 1.736; 95% CI, 1.126 to 2.677; AOR, 1.771; 95% CI, 1.101 to 2.851) and large-size tumors (>2 cm in the greatest dimension; OR, 1.644; 95% CI, 1.083 to 2.493; AOR, 1.728; 95% CI, 1.089 to 2.741). Based on behavioral exposure of environmental carcinogens, the presence of 4 RAGE single-nucleotide polymorphisms (SNPs), combined with betel quid chewing and/or tobacco use, greatly augmented the risk of oral cancer. In addition, carriers of particular haplotypes of the 4 RAGE SNPs examined are more prone to develop oral cancer. These results indicate an involvement of RAGE SNP rs1800625 in the development of oral squamous cell carcinoma and implicate the interaction between RAGE gene polymorphisms and environmental mutagens as a predisposing factor of oral carcinogenesis.

Complex tissue-specific patterns and distribution of multiple RAGE splice variants in different mammals

The receptor for advanced glycosylation end products (RAGE) is a multiligand receptor involved in diverse cell signaling pathways. Previous studies show that this gene expresses several splice variants in human, mouse, and dog. Alternative splicing (AS) plays an important role in expanding transcriptomic and proteomic diversity, and it has been related to disease. AS is also one of the main evolutionary mechanisms in mammalian genomes. However, limited information is available regarding the AS of RAGE in a wide context of mammalian tissues. In this study, we examined in detail the different RAGE mRNAs generated by AS from six mammals, including two primates (human and monkey), two artiodactyla (cow and pig), and two rodentia (mouse and rat) in 6–18 different tissues including fetal, adult, and tumor. By nested reverse transcription-polymerase chain reaction (RT-PCR) we identified a high number of splice variants including noncoding transcripts and predicted coding ones with different potential protein modifications affecting mainly the transmembrane and ligand-binding domains that could influence their biological function. However, analysis of RNA-seq data enabled detecting only the most abundant splice variants. More than 80% of the detected RT-PCR variants (87 of 101 transcripts) are novel (different exon/intron structure to the previously described ones), and interestingly, 20–60% of the total transcripts (depending on the species) are noncoding ones that present tissue specificity. Our results suggest that RAGE undergoes extensive AS in mammals, with different expression patterns among adult, fetal, and tumor tissues. Moreover, most splice variants seem to be species specific, especially the noncoding variants, with only two (canonical human Tv1-RAGE, and human N-truncated or Tv10-RAGE) conserved among the six different species. This could indicate a special evolution pattern of this gene at mRNA level.

Curcumin eliminates the effect of advanced glycation end-products (AGEs) on the divergent regulation of gene expression of receptors of AGEs by interrupting leptin signaling

Non-alcoholic steatohepatitis (NASH) is a major risk factor for hepatic fibrogenesis. NASH is often found in diabetic patients with hyperglycemia. Hyperglycemia induces non-enzymatic glycation of proteins, yielding advanced glycation end-products (AGEs). Effects of AGEs are mainly mediated by two categories of cytoplasmic membrane receptors. Receptor for AGEs (RAGE) is associated with increased oxidative stress and inflammation, whereas AGE receptor-1 (AGE-R1) is involved in detoxification and clearance of AGEs. Activation of hepatic stellate cells (HSC) is crucial to the development of hepatic fibrosis. We recently reported that AGEs stimulated HSC activation likely by inhibiting gene expression of AGE-R1 and inducing gene expression of RAGE in HSC, which were eliminated by the antioxidant curcumin. This study is to test our hypothesis that curcumin eliminates the effects of AGEs on the divergent regulation of the two receptors of AGEs in HSC by interrupting the AGE-caused activation of leptin signaling, leading to the inhibition of HSC activation. We observed herein that AGEs activated leptin signaling by inducing gene expression of leptin and its receptor in HSC. Like AGEs, leptin differentially regulated gene expression of RAGE and AGE-R1. Curcumin eliminated the effects of AGEs in HSC by interrupting leptin signaling and activating transcription factor NF-E2 p45-related factor 2 (Nrf2), leading to the elevation of cellular glutathione and the attenuation of oxidative stress. In conclusions, curcumin eliminated the effects of AGEs on the divergent regulation of gene expression of RAGE and AGE-R1 in HSC by interrupting the AGE-caused activation of leptin signaling, leading to the inhibition of HSC activation.

RAGE gene three polymorphisms with Crohn's disease susceptibility in Chinese Han population

AIM: To investigate the association of three polymorphisms in the receptor for advanced glycation end product (RAGE) gene with Crohn’s disease (CD) risk in a Chinese population.

METHODS: A hospital-based case-control association study involving 312 CD patients and 479 healthy controls was conducted. Peripheral blood samples were collected from 791 study subjects, and genomic DNA was extracted. Genotyping was performed using polymerase chain reaction-ligase detection reaction method. The association between polymorphic genotype and CD predisposition was determined using odds ratio and 95% confidence interval (CI). Data were analyzed using Haplo.stats program.

RESULTS: Significant differences were observed between patients and controls in allele/genotype distributions of rs1800624 (P_allele=0.012; P_genotype=0.005) and in allele distributions of rs2070600 (P=0.02). The risk for CD associated with the rs1800624-A mutant allele decreased by 36% (95%CI: 0.47-0.88, P = 0.005) under the additive model and by 35% (95%CI: 0.46-0.91, P=0.013) under the dominant model. Carriers of rs2070600-A mutant allele showed a 37% (95%CI: 1.02-1.83, P=0.036) increased risk of developing CD relative to the GG genotype carriers. In haplotype analysis, haplotype T-A-G (in the order rs1800625, rs1800624, and rs2070600) decreased the odds of CD by 33% (95%CI: 0.49-0.94, P=0.018).

CONCLUSION: CD is an immune-related disease with genetic predisposition. Genetic defects in the RAGE gene are strongly associated with CD in Chinese population.

Receptor for advanced glycation end products and its involvement in inflammatory diseases

The receptor for advanced glycation end products (RAGE) is a transmembrane receptor of the immunoglobulin superfamily, capable of binding a broad repertoire of ligands. RAGE-ligands interaction induces a series of signal transduction cascades and lead to the activation of transcription factor NF-κB as well as increased expression of cytokines, chemokines, and adhesion molecules. These effects endow RAGE with the role in the signal transduction from pathogen substrates to cell activation during the onset and perpetuation of inflammation. RAGE signaling and downstream pathways have been implicated in a wide spectrum of inflammatory-related pathologic conditions such as arteriosclerosis, Alzheimer's disease, arthritis, acute respiratory failure, and sepsis. Despite the significant progress in other RAGE studies, the functional importance of the receptor in clinical situations and inflammatory diseases still remains to be fully realized. In this review, we will summarize current understandings and lines of evidence on the molecular mechanisms through which RAGE signaling contributes to the pathogenesis of the aforementioned inflammation-associated conditions.

Plasma levels of soluble receptor for advanced glycation end products and coronary atherosclerosis: possible correlation with clinical presentation

Receptor for Advanced Glycation End-products (RAGE) is a multi-ligand receptor ubiquitous present on epithelial, neuronal, vascular and inflammatory cells, usually expressed at low levels in homeostasis and to increased degrees at sites of stress or injury. The aim of the present study was to evaluate sRAGE plasma levels in patients with Acute Coronary Syndrome (ACS) and to assess its diagnostic efficacy in identification of patients with acute events. Plasma levels of sRAGE were determined in 860 patients with Coronary Artery Disease (CAD): 530 patients presented stable angina and 330 were observed during acute ischemic event (147 with unstable angina and 183 with myocardial infarction). sRAGE plasma levels were significantly lower in patients with ACS than in patients with stable angina: [median 584 pg/mL (IQR: 266–851 pg/mL) in MI patients, median 769 pg/mL (IQR: 394–987 pg/mL) in patients with unstable angina, median 834 pg/mL (IQR 630–1005 pg/mL) in patients with stable angina; P < 0.001]. sRAGE levels did not differ among ACS patients stratified by the extent of coronary artery disease. In conclusion, this study confirm the role of sRAGE in activation and progression of inflammatory process and suggests the possibility that sRAGE can be considered an indicator of destabilization of vulnerable plaque.