Plasma Levels Of sRAGE Research Articles

Lag-time in Alzheimer\u2019s disease patients: a potential plasmatic oxidative stress marker associated with ApoE4 isoform

In the brain, Oxidative Stress (OS) contribute to structural and functional changes associated with vascular aging, such as endothelial dysfunction, extracellular matrix degradation, resulting in age-related reduced vasodilatation in response to agonists. For this reason, OS is considered a key factor in Alzheimer’s Disease (AD) development and recent evidence correlated oxidative stress with vascular lesion in the pathogenesis of AD, but the mechanism still need to be fully clarified.The etiology of AD is still not completely understood and is influenced by several factors including Apolipoprotein E (ApoE) genotype. In particular, the Apo ε4 isoform is considered a risk factor for AD development.This study was aimed to evaluate the possible relationship between three plasmatic OS marker and Apo ε4 carrier status. Plasmatic soluble receptor for advanced glycation end products (sRAGE) levels, plasma antioxidant total defenses (by lag-time method) and plasmatic Reactive Oxygen species (ROS) levels were evaluated in 25 AD patients and in 30 matched controls. ROS were significantly higher while plasma antioxidant total defenses and sRAGE levels were significantly lower in AD patients compared to controls. In AD patients lag-time values show a significant positive linear correlation with sRAGE levels and a (even not significant) negative correlation with ROS levels. Lag-time is significantly lower in ε4 carrier (N = 13) than in ε4 non-carrier (N = 12). Our result confirms the substantial OS in AD. Lag-time levels showed a significant positive correlation with sRAGE levels and a significant association with ε4 carrier status suggesting that plasmatic lag-time evaluation can be considered as a potential useful OS risk marker in AD.

Role of Receptors for Advanced Glycation End Products and High-Mobility Group Box 1 in the Outcome of Human T Cell Lymphotropic Type 1 Infection

Human T cell lymphotropic type 1 (HTLV-1)-associated myelopathy/tropical spastic paraparesis (HAM/TSP) is a chronic viral neuroinflammatory disease, which leads to damage of the central nervous system. Inflammatory responses and mediators are both involved in the pathogenesis of the disease and in determining its outcome. High-Mobility Group Box 1 (HMGB1) is a chromatin-associated nuclear protein acting as a signaling molecule in cells after binding to its receptors. Receptor for advanced glycation end products (RAGE) is a transmembrane multiligand receptor that binds to HMGB1. HMGB1-RAGE signaling has an important role in inflammatory and infectious diseases. Inhibition of HMGB1 activity reduces the inflammation in immune-associated diseases. In the present study, we examined the gene expressions and plasma levels of HMGB1 and its receptor RAGE in HAM/TSP patients, HTLV-1-infected asymptomatic carriers (ACs), and healthy controls. Peripheral blood mononuclear cells were collected from all the groups and complementary DNA (cDNA) was synthesized. HMGB-1 messenger RNA (mRNA) expression was quantified by real-time polymerase chain reaction (PCR) TaqMan method, and plasma levels of HMGB1 and soluble RAGE (sRAGE) were measured by enzyme-linked immunosorbent assay (ELISA). The mRNA expression of HMGB1 was the same among the groups (p > 0.05). No significant difference in the plasma levels of HMGB1 was observed between the groups (p > 0.05). The plasma levels of sRAGE were higher in ACs than HAM/TSP patients, and a significant difference was observed between the two groups (p < 0.001). Our results showed that sRAGE could play a potential role in the control of inflammatory response in HTLV-1 carriers through the inhibition of HMGB1 signaling and potentially could be used as an indicator for evaluation of HAM/TSP developing in HTLV-1-infected individuals.

Influence of ADAM10 Polymorphisms on Plasma Level of Soluble Receptor for Advanced Glycation End Products and The Association With Alzheimer's Disease Risk.

To determine the role of A disintegrin and metalloproteinase 10 (ADAM10) in genetic susceptibility to Alzheimer’s disease (AD) in a representative Chinese sample, we genotyped 362 AD patients and 370 healthy controls for the rs514049A/C and rs653765C/T polymorphisms in the ADAM10 promoter using the SNaPshot technique. We also examined the potential impact of these polymorphisms on the plasma level of soluble receptor for advanced glycation end products (sRAGE), a decoy receptor whose reduction has been associated with a higher risk of AD. Additionally, a meta-analysis was performed using the present study and the largest GWAS from the International Genomics of Alzheimer’s Project (IGAP). No significant differences were found in the distributions of genotypes or alleles between AD patients and control subjects. However, age-at-onset stratification analysis revealed that there were significant differences in the genotypes (P = 0.015) and alleles (P = 0.006) of the rs653765 SNP. Furthermore, patients with the rs653765 CC genotype showed a lower ADAM10 level and a faster cognitive deterioration than those in patients with the CT/TT genotype in late-onset AD (LOAD), and the rs653765 CC polymorphism was able to regulate the production of the ADAM10 substrate sRAGE. In contrast, the rs514049 polymorphism was not statistically associated with AD. In the meta-analysis, we observed that both rs514049 (A allele vs. C allele, P = 0.002) and rs653765 (C allele vs. T allele, P = 0.004) were associated with AD risk. The present study indicated that the rs653765 polymorphism might be associated with the risk and development of LOAD; in particular, the risk genotype, CC, may decrease the expression of ADAM10, influencing the plasma levels of sRAGE, and thus may be correlated with the clinical progression of AD.

The Level of Plasma Amyloid-β40 Is Correlated with Peripheral Transport Proteins in Cognitively Normal Adults: A Population-Based Cross-Sectional Study.

Transport proteins, soluble low-density lipoprotein receptor-related protein-1 (sLRP1), and soluble receptor of advanced glycation end products (sRAGE), play an important role in the clearance of plasma amyloid-β (Aβ). However, their relationship is not clear. The aim was to explore the relationship between plasma levels of sLRP1, sRAGE, and Aβ in a cross-sectional study. A total of 1,185 cognitively normal participants (age above 40) from a village in the suburbs of Xi'an, China were enrolled from October 8, 2014 to March 30, 2015. Plasma Aβ40, Aβ42, sLRP1, and sRAGE were tested using a commercial ELISA. Apolipoprotein E (APOE) genotyping was conducted using PCR and sequencing. The relationship between plasma levels of sLRP1, sRAGE, and Aβ was analyzed using Pearson's correlation analysis and multiple linear regression. In the total population, Log sLRP1 and Log sRAGE were positively correlated with plasma Aβ40 (r= 0.103, p < 0.001; r= 0.064, p = 0.027, respectively), but neither were associated with plasma Aβ42. After multivariable adjustment in the regression model, Log sLRP1 and Log sRAGE were still positively related with plasma Aβ40 (β= 2.969, p < 0.001; β= 1.936, p = 0.017, respectively) but not Aβ42. Furthermore, the positive correlations between transport proteins and plasma Aβ40 remained significant only in APOEɛ4 non-carriers after Pearson's analysis and multiple regression analysis after stratification by gene status. The concentrations of plasma sLRP1 and sRAGE had a significant impact on the level of plasma Aβ40 in cognitively normal adults, especially in APOEɛ4 non-carriers. However, the mechanism by which the transport proteins are involved in peripheral Aβ clearance and the relationship between transporters and amyloid burden in the brain needs further validation.

Detection of the receptor for advanced glycation endproducts in neuronally-derived exosomes in plasma

Exosomes are nanovesicles that participate in cell-to-cell communication and are secreted by a variety of cells including neurons. Recent studies suggest that neuronally-derived exosomes are detectable in plasma and that their contents likely reflect expression of various biomarkers in brain tissues. The receptor for advanced glycation endproducts (RAGE) has been implicated in the pathophysiology of Alzheimer's disease (AD) and is increased in brain regions affected by AD. The goal of our project was to determine whether RAGE is present in plasma exosomes, and specifically exosomes derived from neurons. Exosomes were isolated from plasma samples (n = 8) by precipitation (ExoQuick) and ultracentrifugation methods. Neuronally-derived exosomes were isolated using a biotin-tagged L1 Cell Adhesion Molecule (L1CAM) specific antibody and streptavidin-tagged agarose resin. RAGE expression was measured by Western blots and ELISA. Western Blotting showed that RAGE is present in L1CAM-positive exosomes isolated using both methods. Mean (SD) exosomal RAGE levels were 164 (60) pg/ml by ExoQuick and were highly correlated with plasma sRAGE levels (r = 0.87, p = 0.005), which were approximately 7.5-fold higher than exosomal levels. Weak to moderate correlations were found between exosomal RAGE and age, BMI, and cognitive function. These results show for the first time that RAGE is present in neuronally-derived plasma exosomes, and suggest that exosomal RAGE may be a novel biomarker that reflects pathophysiological processes in the brain.

Glycaemic control in type 2 diabetic patients with chronic kidney disease: the impacts on enzymatic antioxidants and soluble RAGE.

BackgroundChronic kidney disease (CKD) is characterised by long-term kidney damage and renal function decline. Diabetic CKD is the principal subtype of kidney disease in Malaysia and is associated with oxidative stress which plays an important role in development and progression of the disease. Glycaemic control slows down the progression of diabetic complications, including diabetic CKD. However, the implication of glycaemic control on enzymatic antioxidants and soluble RAGE (sRAGE) in CKD patients remains elusive. The aim of this study was to investigate the effect of glycaemic control on the levels or activities of glutathione peroxidase (GPx), superoxide dismutase (SOD) and sRAGE in CKD patients.MethodsA total of 150 CKD patients and 64 non-CKD patients were enrolled. The type 2 diabetic patients in the recruited study participants were categorised based on their glycaemic control; poor glycaemic control (GC) with haemoglobin A1c (HbA1c) > 7% and good GC with HbA1c ≤ 7%. The levels or activities of GPx, SOD and sRAGE in plasma were measured. These biochemical parameters were analysed using Mann–Whitney U test and two-way analysis of variance (ANOVA).ResultsThe activities of GPx and SOD as well as plasma level of sRAGE were not significantly different among the CKD patients with varying glycaemic control status. Irrespective of diabetes status and glycaemic control status, CKD patients also exhibited lower plasma SOD activities compared with non-CKD patients. Among the non-CKD patients, SOD activities were significantly higher in diabetic patients with good GC than diabetic patients with poor GC. Two-way ANOVA revealed that both CKD status and glycaemic control had an interaction effect on SOD activities in diabetic subjects with and without CKD. Follow-up analysis showed that SOD activities were significantly higher in non-CKD patients with good GC. There were no overall significant differences in GPx activities among the study participants. Furthermore, plasma sRAGE levels were higher in diabetic patients with CKD than those without CKD, regardless of glycaemic control status. There were no interaction effects between CKD status and glycaemic control status on GPx and sRAGE. Instead, CKD status showed significant main effects on these parameters, indicating significant differences between diabetic subjects with CKD and diabetic subjects without CKD.ConclusionGlycaemic control did not quantitatively alter GPx, SOD and sRAGE in diabetic CKD patients. Despite the advantages of good glycaemic control, a well-controlled diabetes in CKD did not modulate the activities of enzymatic antioxidants and sRAGE levels, therefore may not be the primary mechanism to handle oxidative stress.

Diagnostic indicator of acute lung injury for pediatric critically ill patients at a tertiary pediatric hospital.

Early identification of acute lung injury (ALI) in pediatric patients at risk of mortality is important for improving outcome.Assessment of soluble form of receptor for advanced glycation end products (sRAGE) as a valid biomarker for diagnosis of ALI among critically ill, pediatric patients in addition to correlating levels of sRAGE and different outcomes of those patients.A Hospital-based case-control study was conducted in pediatric intensive care units (PICUs) at Cairo University Hospital, along a period of 6 months. Total of 68 pediatric patients following inclusion criteria were classified into: patients with ALI; with both ALI and sepsis; with sepsis and control patients. They were prospectively followed and their laboratory and immunological workup (at days 1 and 9) was done to measure serum sRAGE levels and detect (sRAGE) genotypes.The age of the included children ranged from 8 to 84 months. Plasma level of sRAGE was significantly higher in plasma from patients with ALI regardless of associated sepsis. Plasma sRAGE levels were positively correlated with lung injury score. When assessing sRAGE genotypes, TA and TT genotypes were significant in most of the ALI with and without sepsis patients.Monitoring levels of sRAGE and genotypes can significantly affect the survival of ALI children.

Decreased soluble RAGE in neutrophilic asthma is correlated with disease severity and RAGE G82S variants.

The advanced glycosylation end product-specific receptor (RAGE) has been demonstrated to be an important mediator of asthma pathogenesis. The soluble isoform of RAGE (sRAGE) acts as a 'decoy' to sequester RAGE ligands, and thus prevents their binding to the receptor. A number of reports have linked deficiency of sRAGE to the severity and outcomes of various human diseases, and association with RAGE G82S variants. However, whether sRAGE levels are increased or decreased in asthmatic patients is unclear. The aim of the present study was to determine plasma sRAGE levels in different asthma phenotypes and associations of plasma sRAGE levels with RAGE G82S variants. A total of 85 neutrophilic and 109 non‑neutrophilic newly diagnosed asthmatic patients, and 118 healthy controls, were recruited. Plasma sRAGE levels were measured by ELISA analysis. RAGE G82S genotypes were detected using the Sanger sequencing method. Plasma sRAGE levels were decreased in neutrophilic asthmatics (443.67±208.9pg/ml) and increased in non‑neutrophilic asthmatics (677.63±300.75pg/ml) compared with healthy controls (550.02±300.83pg/ml) (P<0.001). Plasma sRAGE levels were positively correlated with FEV1% predicted (FEV1% Pre) (rp=0.258; P=0.023) in neutrophilic asthmatics. The frequency of G82S genotypes was significantly different between neutrophilic and non‑neutrophilic asthmatics (P=0.009). Neutrophilic asthmatics with genotypes A/G or A/A (389.83±150.37 and 264.59±161.74pg/ml, respectively) had significantly decreased sRAGE levels compared with the G/G genotype (498.64±235.37pg/ml) (P=0.022). Those with the A/G and A/A genotype (60.14±22.36%) displayed a trend toward lower FEV1% Pre compared with those with the G/G genotype (64.51±27.37%). No significant difference in sRAGE levels or an association with FEV1% Pre was observed between the different genotypes in non‑neutrophilic asthmatics. In conclusion, the results of the present study indicated that plasma sRAGE levels are altered in different asthma inflammatory phenotypes. Plasma sRAGE may be a biomarker of asthma severity and may be associated with G82S gene variants in neutrophilic asthmatics.

Elevated Plasma Level of Soluble Form of RAGE in Ischemic Stroke Patients with Dementia

The receptor for advanced glycation end products (RAGE) and its downstream pathways are involved in various inflammatory and immune responses. Importantly, there is soluble RAGE (sRAGE) that forms either by alternative splicing of RAGE messenger ribonucleic acid as the endogenous soluble form of RAGE (esRAGE) or by proteolytic cleavage of full-length RAGE protein. This study aimed to investigate the associations of the plasma levels of sRAGE and esRAGE in ischemic stroke (IS) patients with and without dementia. This cross-sectional study recruited patients with IS at a university medical center. Vascular dementia was defined as the scale of Clinical Dementia Ranking (CDR) ≥ 1. Standard enzyme-linked immunosorbent assay was used to measure the plasma concentration of sRAGE and esRAGE. From November 2014 to October 2015, a total of 172 IS patients (mean age: 72.1 ± 7.5 years, 64.5% male) were recruited, including 73 with CDR = 0, 63 with CDR = 0.5, and 36 with CDR ≥ 1. In univariate analysis, IS patients with dementia were older and had more diabetes mellitus, less atrial fibrillation, and higher post-stroke modified Rankin Scale scores than those without dementia. Plasma levels of sRAGE and esRAGE were significantly higher in IS patients with than those without dementia (1.44 ± 1.29 vs. 1.03 ± 0.48 and 0.39 ± 0.40 vs. 0.24 ± 0.13 ng/mL, both p < 0.01). Importantly, both parameters remained independent after adjustment for clinical variables (OR 2.683, p = 0.013 and OR 39.192, p = 0.006, respectively). In summary, plasma sRAGE and esRAGE were elevated in those with dementia compared with those without dementia among IS patients.

Suppressed MMP-9 Activity in Myocardial Infarction-Related Cardiogenic Shock Implies Diminished Rage Degradation.

Receptor for advanced glycation end products (RAGE) and its cleavage fragment soluble RAGE (sRAGE) are opposite players in inflammation. Enhanced monocytic RAGE expression and decreased plasma sRAGE levels are associated with higher mortality in infarction-related cardiogenic shock. Active matrix metalloproteinase-9 (MMP-9) has been implied in RAGE ectodomain cleavage and subsequently sRAGE shedding in vitro. We investigated MMP-9 activity in myocardial infarction-induced cardiogenic shock with regard to RAGE/sRAGE regulation. We determined MMP-9 serum activity by zymography and tissue inhibitor of matrix metalloproteinases (TIMP-1) expression by Western blot and correlated it to RAGE/sRAGE data in patients with cardiogenic shock after acute myocardial infarction (CS, n = 30), in patients with acute myocardial infarction without shock (AMI, n = 20) and in healthy volunteers (n = 20).MMP-9 activity is increased in AMI (P = 0.02 versus controls), but significantly decreased in CS with lowest levels in non-survivors (n = 13, P = 0.02 versus AMI). In all patients, MMP-9 activity correlated inversely with RAGE expression on circulating monocytes (r = -0.57; P = 0.0001; n = 50).TIMP-1 levels showed an inverse regulation in comparison to active MMP-9 with significantly decreased levels in AMI as compared with controls (P = 0.02 versus controls) and highest levels in non-survivors of CS (P <0.001 versus AMI). Serum MMP-9 activity is increased in acute myocardial infarction, but markedly suppressed in cardiogenic shock. Maintaining MMP-9 activity could be a therapeutic target to limit RAGE-induced deleterious inflammation in cardiogenic shock.

Plasma levels of high-mobility group box 1 and soluble receptor for advanced glycation end products in primary antiphospholipid antibody syndrome patients.

IntroductionMany studies have demonstrated elevated circulating levels of high-mobility group box 1 (HMGB1) and decreased circulating levels of soluble receptor for advanced glycation end products (sRAGE) in patients with autoimmune diseases. In the present study, we investigated plasma levels of both HMGB1 and sRAGE in primary antiphospholipid syndrome (pAPS) patients.MethodsWe prospectively recruited 11 pAPS patients, 17 antiphospholipid antibody (APA)-positive SLE patients without APS manifestations (APA+SLE) and 12 SLE patients with secondary APS (APS+SLE). We also recruited 10 healthy controls (HCs). Plasma levels of HMGB1 and sRAGE were determined using sandwich ELISA kits. In addition, plasma levels of HMGB1 were also determined using Western blot in 6 pAPS patients and 6 HCs.ResultsThere was no significant difference in plasma levels of HMGB1 measured by ELISA among subgroups of the enrolled subjects. In addition, there was no significant difference in plasma levels of HMGB1 measured by Western blot between pAPS patients and HCs. On the other hand, we observed a trend toward lower plasma levels of sRAGE in APA+SLE or APS+SLE patients when compared with HCs. However, there was no significant difference in plasma levels of sRAGE between pAPS patients and HCs, or between APA+SLE patients and APS+SLE patients.ConclusionThere was no significant difference in plasma levels of sRAGE or HMGB1 between pAPS patients and HCs. Plasma levels of sRAGE/HMGB1 could not be utilized to differentiate between APA+SLE and APS+SLE patients.

Plasma Soluble Receptor for Advanced Glycation End Products in Idiopathic Pulmonary Fibrosis.

The receptor for advanced glycation end products (RAGE) is underexpressed in idiopathic pulmonary fibrosis (IPF) lung, but the role of RAGE in human lung fibrosis remains uncertain. To examine (1) the association between IPF risk and variation at rs2070600, a functional missense variant in AGER (the gene that codes for RAGE), and (2) the associations between plasma-soluble RAGE (sRAGE) levels with disease severity and time to death or lung transplant in IPF. We genotyped the rs2070600 single-nucleotide polymorphism in 108 adults with IPF and 324 race-/ethnicity-matched control subjects. We measured plasma sRAGE by ELISA in 103 adults with IPF. We used generalized linear and additive models as well as Cox models to control for potential confounders. We repeated our analyses in 168 (genetic analyses) and 177 (sRAGE analyses) adults with other forms of interstitial lung disease (ILD). There was no association between rs2070600 variation among adults with IPF (P = 0.31). Plasma sRAGE levels were lower among adults with IPF and other forms of ILD than in control subjects (P < 0.001). The rs2070600 allele A was associated with a 49% lower sRAGE level (95% confidence interval [CI], 11 to 71%; P = 0.02) among adults with IPF. In adjusted analyses, lower sRAGE levels were associated with greater disease severity (14% sRAGE decrement per 10% FVC decrement; 95% CI, 5 to 22%) and a higher rate of death or lung transplant at 1 year (adjusted hazard ratio, 1.9 per logarithmic unit of sRAGE decrement; 95% CI, 1.2-3.3) in IPF. Similar findings were observed in a heterogeneous group of adults with other forms of ILD. Lower plasma sRAGE levels may be a biological measure of disease severity in IPF. Variation at the rs2070600 single-nucleotide polymorphism was not associated with IPF risk.

Sleep Deprivation Induced Plasma Amyloid-β Transport Disturbance in Healthy Young Adults.

Sleep is an important physiological process and beneficial in the removal of brain metabolites and functional recovery. Prior studies have shown that sleep disorders are significant risk factors for Alzheimer's disease (AD). The present study was designed to characterize the effect of short-term total sleep deprivation (TSD) on plasma amyloid-β (Aβ) concentrations. A clinical trial was conducted between March 1, 2016, and April 1, 2016. Twenty volunteers (age 27.3±3.4 years) with normal cognitive function and sleeping habits were recruited from the local population. Participants underwent 24 h of TSD. Periprocedural blood samples were collected to compare the changes of plasma Aβ42, Aβ40, low-density lipoprotein receptor-related protein (sLRP-1), soluble receptors for advanced glycation end products (sRAGE), and serum superoxide dismutase (SOD) and malonaldehyde (MDA). TSD increased morning plasma Aβ40 levels by 32.6% (p < 0.001) and decreased the Aβ42/Aβ40 ratio by 19.3% (p < 0.001). A positive relationship was found between TSD duration and plasma Aβ40 level (r = 0.51, p < 0.001) and Aβ40/Aβ42 ratio (r = 0.25, p = 0.003). Plasma concentrations of sLRP1 (p = 0.018) and sRAGE (p = 0.001) decreased significantly after TSD. Aβ40 and Aβ42 plasma concentrations correlated with plasma levels of sLRP1 and sRAGE. Serum SOD decreased after TSD (p = 0.005), whereas serum MDA was increased (p = 0.001). Sleep deprivation can lead to an elevation of plasma Aβ40 and decrease of the Aβ42/Aβ40 ratio. The underlying mechanisms may be related to increased oxidative stress and impaired peripheral Aβ clearance as pathomechanisms of AD.

Abstract TP440: Elevated Plasma Level of Soluble Form of RAGE in Ischemic Stroke Patients With Vascular Cognitive Impairment

Background / Purpose: Little is known about the role of receptor for advanced glycation end products (RAGE) -mediated signaling in the development of vascular cognitive impairment (VCI). The study aimed to investigate the associations of various RAGE signaling related plasma biomarkers and the development of VCI in chronic ischemic stroke (IS) patients. Methods: This cross-sectional study recruited patients with IS at an university medical center stroke clinic. VCI was defined as the scale of Clinical Dementia Ranking (CDR) ≥1. Standard enzyme-linked immunosorbent assay was used to measure the plasma concentration of soluble form of RAGE (sRAGE), endogenous soluble form of RAGE (esRAGE), high mobility group box 1 (HMGB1) and matrix metallopeptidase 9 (MMP9) in IS patients with and without VCI. Results: Between November 2014 to October 2015, a total of 172 IS patients (mean age 72.1±7.5 years, 64.5% male) were recruited, including 73 with CDR=0, 63 with CDR=0.5 and 36 with CDR ≥1. In univariate analysis, IS patients with VCI were older, and had more diabetes mellitus, fewer atrial fibrillation, and higher post-stroke modified Rankin Scales than those without. Plasma levels of sRAGE and esRAGE, but not HMGB1 or MMP9 were significantly higher in IS patients with VCI than those without (1.44±1.29 versus 1.03±0.48 and 0.39±0.40 versus 0.24±0.13 ng/ml, both p&lt;0.01). Importantly, both parameters remained independent after adjustment for clinical variables (OR 2.683, p=0.013 and OR 39.192, p=0.006, respectively). Conclusion: Among IS patients, plasma levels of both sRAGE and esRAGE were elevated in those with VCI.

Increased Levels of sRAGE in Diabetic CKD-G5D Patients: A Potential Protective Mechanism against AGE-Related Upregulation of Fibroblast Growth Factor 23 and Inflammation.

Advanced glycation end products (AGEs) may induce cardiac remodeling in kidney disease by promoting fibroblast growth factor 23 (FGF-23) expression. Since AGEs are increased in diabetes mellitus (DM), our first aim was to evaluate the existence of any potential association between AGEs, FGF-23, inflammation, and increased cardiovascular risk in DM patients on dialysis (CKD-G5D). Secondarily, we explored the potential role of the soluble receptor for AGEs (sRAGE) as a marker of heart failure. Levels of glycated albumin (GA), sRAGE, c-terminal FGF-23 (cFGF-23), brain natriuretic peptide (BNP), and inflammatory mediators were compared between DM and non-DM CKD-G5D patients. The levels of sRAGE, cFGF-23, BNP, and proinflammatory markers were over the ranges of normality in both DM and non-DM groups. Only GA and sRAGE levels were increased in DM compared to non-DM patients. Plasma levels of sRAGE and CRP were the only independent predictors of BNP concentration. In conclusion, in DM CKD-G5D patients, sRAGE appeared to be a marker of cardiac remodeling. Indeed, its increase could be a potential protective mechanism against the increased risk of cardiovascular complications related to AGEs and inflammation. The causal relationship between sRAGE and cardiovascular risk in these patients needs to be further confirmed by mechanistic studies.

The Association Between Soluble Receptor for Advanced Glycation End-Products and Cardiovascular Dysfunction Explained by Non-Alcoholic Fatty Liver Disease; A 7-year Follow-up of the CODAM Study

Background. The risk for cardiovascular events and cardiovascular death in diabetic patients is twice as high compared to non-diabetic controls. Glucose-lowering therapy aimed at relieving these complications have led to minimally altered cardiovascular morbidity and mortality, implicating that other pathways may be involved in microand macrovascular diseases in diabetic patients. Experimental studies suggest that interaction of ligands and receptor for advanced glycation end products (RAGEs) play an important role in cardiovascular disease (CVD). Associations between non-alcoholic fatty liver disease (NAFLD) and CVD have been reported previously. Moreover, RAGE-dependent inflammation in steatotic livers may play a pivotal role in the pathogenesis of NAFLD. Thus, we hypothesize that signaling via RAGE contributes to the initiation and progression of cardiovascular dysfunction and disease, and this relation is partly the result of and effects of RAGE signaling on the development of NAFLD. Objective. We investigated the association between the soluble form of RAGE (sRAGE) and (incidence of) cardiovascular disease (CVD). Furthermore we investigated whether NAFLD may be an intermediate step to causing CVD. Methods. In the current analysis, we used data from 574 Caucasian participants from the Cohort on Diabetes and Atherosclerosis Maastricht (CODAM) study. Plasma biomarkers for endothelial dysfunction and liver enzyme markers were measured. These biomarkers were subsequently converted into averaged standardized scores, ultimately creating one integrated measure for the liver function, i.e the LE score and for endothelial dysfunction, i.e the ED score. Liver fat percentage was estimated using a validated equation. CVD and cardiovascular events (CVE) were also identified. Atherosclerosis was identified using measures of carotid intima media thickness (cIMT) and ankle-arm-index (AAIx). For continuous outcomes multiple linear regression was performed, whereas for dichotomous outcomes binomial logistic regression analysis was performed. All analysis included adjustments for age, gender, glucose metabolism status, smoking, energy intake, alcohol consumption, physical activity, use of medication, and waist circumference. Results. Higher plasma sRAGE levels were associated with a higher score for endothelial dysfunction, However, no cross-sectional association was found with markers of atherosclerosis (cIMT, AAIx) or prevalence of CVD. NAFLD was positively associated with endothelial dysfunction, atherosclerosis, and CVD [β: 0.338; 95% CI: 0.251; 0.424], [β: 0.017; 95% CI: 0.001; 0.033], and [OR: 1.442; 95% CI: 1.023; 2.032]. Mediation analysis suggests that FLD accounts for 2.4% of the coefficient in the association between sRAGE and endothelial dysfunction. Next, prospective analysis indicated no association between sRAGE and CVD, CVE, or endothelial function. Furthermore, the prospective analysis indicated a strong association between LE markers and changes in endothelial dysfunction [β: -0.079; 95% CI: -0.116; -0.043], but not with CVD or CVE. Conclusion. These data suggest that cross-sectionally sRAGE can potentially contribute to progression of CVD, through its action on endothelial function. Additionally, the mediating role of NAFLD between sRAGE and endothelial dysfunction is negligible. However, prospective analysis indicated that only NAFLD, but not sRAGE, contributes to cardiovascular complications after 7 year follow-up

The effects of n-3 long-chain polyunsaturated fatty acid supplementation on AGEs and sRAGE in type 2 diabetes mellitus.

In diabetes mellitus, chronic hyperglycemia leads to formation of advanced glycation end products (AGEs). Binding of AGEs to receptors of AGE (RAGE) causes deleterious effects. In populations with a high consumption of n-3 long-chain polyunsaturated fatty acids, a lower prevalence of diabetes mellitus has been reported. We aimed to investigate the effects of n-3 fatty acid (EPA and DHA) supplementation on the levels of AGEs (carboxymethyl lysine (CML) and pentosidine), sRAGE, and nuclear factor kappa B (NF-kB) in type 2 diabetes mellitus (T2DM). T2DM patients (n = 38) treated with oral hypoglycemic agents, without insulin were supplemented with n-3 fatty acids (1.2g/day) for 2months. Plasma CML, pentosidine, sRAGE, and NF-kB levels were measured by ELISA both before and after the supplementation. n-3 fatty acid supplementation significantly reduced fasting glucose (p < 0.01), glycated hemoglobin (HbA1c) (p < 0.05), and pentosidine (p < 0.05) levels. The supplementation induced percentage changes in pentosidine and HbA1c and in pentosidine and creatinine were observed to be correlated (r = 0.349, p < 0.05) and (r = 0.377, p < 0.05), respectively. Waist circumference and systolic and diastolic pressures were significantly decreased due to n-3 supplementation (p < 0.001, p < 0.01, p < 0.01), respectively. Our results show that supplementation with n-3 fatty acid has beneficial effects on waist circumference; systolic and diastolic blood pressures; and the levels of glucose, HbA1c, and pentosidine in T2DM patients. However, the supplementation failed to decrease these parameters to the reference ranges for healthy subjects. In addition, the supplementation did not appear to induce any significant differences in CML, sRAGE, or NF-kB.

Genetic variants in the receptor for advanced glycation end products (RAGE) gene were associated with circulating soluble RAGE level but not with renal function among Asians with type 2 diabetes: a genome-wide association study.

The soluble receptor for advanced glycation end products (sRAGE) has been shown to play an important role in diabetic complications. We conducted genome-wide association study (GWAS) of sRAGE in Asian type 2 diabetes mellitus (T2DM) patient and validated the association in an independent cohort of T2DM. GWAS for sRAGE was performed in 2058 T2DM patients. Associations between single-nucleotide polymorphisms (SNPs) and plasma sRAGE level were analyzed in an additive model using a linear mixed model. To validate the associations, we performed de novo genotyping in an independent cohort (n = 1984). We selected the top SNP for assessment with diabetic kidney disease (DKD). The strongest SNP, rs2070600C>T (P = 1.21 × 10-52), was a genotyped, missense SNP located on chromosome 6, corresponding to the RAGE (AGER) gene locus, the gene encoding RAGE. Conditioning analysis on rs2070600 revealed that rs2071288C>T was the top genotyped independent SNP (P = 8.36 × 10-10). Both SNPs were strongly and dose-dependently correlated with sRAGE level (TT = 399.6 pg/mL, CT = 737.0 pg/mL and CC = 967.0 pg/mL, P < 0.001 for rs2070600; TT = 687.9 pg/mL, CT = 737.6 pg/mL and CC = 904.7 pg/mL, P < 0.001 for rs2072188). Both SNPs were robustly replicated in the independent cohort, especially among Chinese patients (P = 9.02 × 10-72 for rs2070600; P = 1.13 × 10-9 for rs2071288). Log-transformed sRAGE was associated with DKD after adjustment for age, gender and ethnicity in pooled cohorts [odds ratio 2.536 (95% confidence interval 1.864-3.450), P < 0.001]. However, we did not observe any significant association between rs2070600 and DKD. Common variants in RAGE are strongly associated with plasma sRAGE level, which is associated with DKD. However, we did not find a causal link between sRAGE and renal function by Mendelian randomization.

Abstract 103: Circulating sRAGE is Elevated in Patients with Marfan Syndrome and Decreases After Surgical Replacement of Diseased Aortic Segments

Backgound: The Receptor for Advanced Glycation End products (RAGE) and its ligands are associated with vascular remodeling and trigger the release of a soluble receptor (sRAGE). We previously demonstrated that sRAGE levels are elevated in patients with bicuspid aortic valve and ascending aortic aneurysm. Circulating sRAGE in these patients correlates with the presence of a dysfunctional aortic structure but do not linearly correlate with an increase in the aortic diameter. Severe aortic disease occurs in more than 80% of Marfan Syndrome (MFS) patients. Aortic root and ascending aorta (AA) enlargement in MFS are associated with deficiency/destabilization of fibrillin-1, which leads to a generalized structural impairment of the aortic wall. We hypothesized that sRAGE may be elevated in the plasma of MFS patients and may decrease after surgical replacement of diseased aortic tissue. Methods: Plasma samples and clinical information (MFS=120, Control=37) were obtained from the GenTAC bioregistry and the Tissue Biobank at UPENN. Samples were collected either a few days prior to aortic surgery or at least one year post-surgery. sRAGE was tested using ELISA. Univariate and multivariate analysis were performed. Results: sRAGE levels are significantly higher in MFS patients compared to control (1404±64.35 vs 592±34.86 pg/ml, p&lt;0.001) and are associated with the presence of MFS, independent of age, gender and comorbidities (p&lt;0.001). sRAGE levels are significantly higher in MFS patients undergoing aortic surgery when compared to MFS patients monitored for aortic disease (1485±116.8 vs 1209±82.63 pg/ml, p=0.05). Circulating sRAGE is significantly lower in patients who have received aortic surgery (1185±63.31 pg/ml, p=0.02) and even lower in patients who received more extensive replacement (aortic valve/root and AA) versus those who underwent only aortic valve and root replacement (1313±81.83 vs 963.5±92.54 pg/ml, p=0.008). sRAGE levels do not linearly correlate with root and/or AA diameter. Conclusion: Plasma sRAGE levels are associated with the presence of ascending aortopathies independent of aortic diameter. Longitudinal studies evaluating sRAGE in MFS patients may unveil new markers for the diagnosis and risk stratification of this population.

Sputum–plasma ratio of soluble receptor for advanced glycation end-products in patients with chronic obstructive pulmonary disease

BackgroundChronic obstructive pulmonary disease (COPD) is associated with systemic inflammatory consequences. Receptor for advanced glycation end products (RAGE) acts as an important progression factor amplifying the immune and inflammatory responses in several pathophysiological conditions. The soluble form of RAGE (sRAGE) acts as a decoy for the receptor ligands and is thus thought to protect against excessive inflammation. Conflicting reports exist about sRAGE value in stable and exacerbating COPD. ObjectiveTo assess the sputum to plasma ratio of sRAGE in stable COPD patients. Subjects and methodsThe study included 44 adult patients of both sexes who were presented to Alexandria Main University Hospital between March and July 2015. Patients were categorized into three groups; 15 stable COPD patients (Group I), 15 smokers without COPD (Group II), and 14 healthy non-smokers (Group III). Measurement of sRAGE level in induced sputum and plasma was performed using ELISA technique. ResultsThe study included 38 male patients and 6 female patients, whose median ages were 50, 42 and 35.5years in Groups I, II, and III respectively (p<0.001). Median FEV1% predicted were 35, 96, and 105% in Groups I, II, and III respectively (p<0.001). No statistical significant difference was found among all groups regarding sRAGE level in induced sputum, plasma or sputum/plasma ratio (p=0.092, 0.372, 0.154, respectively). Although levels of sRAGE is apparently higher in induced sputum rather than in plasma, it lacked significance (r=0.27, p=0.08). Furthermore, no significant correlation was found between either plasma or sputum sRAGE level and predicted FEV1% (r=−0.11, p=0.48 and r=−0.12, p=0.28, respectively). ConclusionssRAGE level either in induced sputum, plasma or sputum plasma ratio is not significantly different between stable COPD patients, smokers and healthy controls. Thus, sRAGE cannot be considered as a marker of either diagnosis or severity of COPD.