The action of VEGF (vascular endothelial growth factor) is essential to maintain proper endothelial and vascular function. VEGF stimulates virtually all aspects of endothelial function, namely proliferation, migration, permeability and nitric oxide production and release. In addition, the action of VEGF makes the endothelium anti-apoptotic. In turn, the inhibition of VEGF action is associated with endothelial dysfunction. Likewise, endothelial dysfunction can be found in the presence of several cardiovascular risk factors, including diabetes mellitus, hypercholesterolaemia and smoking. As circulating monocytes express functionally active VEGFR-1 (VEGF receptor 1) on their surface, monocytes and the related VEGFR-1-mediated signal transduction cascades have come into focus. The function of monocytes is negatively affected by diabetes mellitus, resulting in monocyte dysfunction. More specifically, a VEGF-related signal transduction defect can be detected in monocytes isolated from diabetic individuals. This reduced monocyte response to VEGF, demonstrated by a reduced chemotactic response, can be regarded as VEGF resistance. It is based on the pre-activation of certain intracellular pathways secondary to the diabetes mellitus-related RAGE (receptor for advanced glycation end-products) activation, ROS (reactive oxygen species) activation and inhibition of PTPs (protein tyrosine phosphatases). This unspecific pre-activation of intracellular pathways represents the molecular basis of VEGF resistance in diabetes mellitus.

Evidence provided by both clinical and pre-clinical studies regarding a central involvement of the receptor for advanced glycation endproducts (RAGE) in vascular disease continues to mount. RAGE is upregulated as a consequence of activation of the ubiquitous pro-inflammatory transcription factor NF-kappaB which is activated in response to diverse inflammatory stimuli including hyperglycaemia, oxidised low density lipoprotein (oxLDL) and reduced shear stress. RAGE may maintain and amplify inflammatory responses in the vasculature if ligand for the receptor is present. RAGE binding by circulating advanced glycation endproducts (AGEs) or S100 protein released by activated leukocytes results in the generation of reactive oxygen species (ROS) and further activation of NF-kappaB. This leads to upregulation of adhesion molecules for circulating monocytes as well as further upregulation of RAGE itself. In addition, these ROS may scavenge and reduce bioavailability of the labile vasodilator nitric oxide (NO), reducing its anti-inflammatory effects and possibly compromising control of vascular tone directly. In addition to atherosclerosis and vascular diseases associated with diabetes, recent data from studies in transgenic mice overexpressing the RAGE ligand S100A4/MTS1 suggest a role for RAGE in the pathogenesis of pulmonary arterial hypertension (PAH). RAGE antagonism also prevents proliferation and migration of pulmonary arterial smooth muscle cells in response to 5-HT, suggesting that S100-RAGE signalling may be of key importance in pulmonary vascular homeostasis and/or disease. Further study of the role of RAGE in inflammation seems likely to yield, not only promising therapeutics but key insights into the pathophysiology of vascular disease as well.

Synovial fibroblasts (SF) play a central role in the inflammatory and destructive process in rheumatoid arthritis (RA). High-mobility group box chromosomal protein 1 (HMGB1) or lipopolysaccharide (LPS) alone failed to induce significant changes in proliferation of cultured SF from RA patients, but premixed HMGB1 with LPS (HMGB1-LPS) significantly facilitated SF proliferation. HMGB1 alone failed to induce IL-6, MMP-3, and MMP-13 production in cultured SF but greatly enhanced LPS-induced expression of IL-6, MMP-3, and MMP-13 at both mRNA and protein levels. HMGB1-LPS synergistically upregulated TLR4 and receptor for advanced glycation endproducts (RAGE) expression on the surface of SF. Both blockers of TLR4 and RAGE significantly inhibited the synergistic effects of HMGB1-LPS on the production of IL-6 and MMPs, but blocking antibodies to TLR2 failed. HMGB1-LPS synergistically increased intracellular levels of phosphorylated p38 and phosphorylated I κ B. Furthermore, both NF- κ B inhibitor Bay11-7085 and p38 inhibitor SB203580 significantly suppressed the enhanced production of IL-6 and MMPs induced by HMGB1-LPS. In conclusion, HMGB1 acts in synergy with LPS to upregulate TLR4 and RAGE expression on the surface of SF in RA and then to augment IL-6, MMP-3, and MMP-13 production, which depends on p38 MAPK and NF-κB activation.

Advanced glycation end products (AGEs) have long been considered as potent molecules promoting neuronal cell death and contributing to neurodegenerative disorders such as Alzheimer's disease (AD). In this study, we demonstrate that AGE-albumin, the most abundant AGE product in human AD brains, is synthesized in activated microglial cells and secreted into the extracellular space. The rate of AGE-albumin synthesis in human microglial cells is markedly increased by amyloid-β exposure and oxidative stress. Exogenous AGE-albumin upregulates the receptor protein for AGE (RAGE) and augments calcium influx, leading to apoptosis of human primary neurons. In animal experiments, soluble RAGE (sRAGE), pyridoxamine or ALT-711 prevented Aβ-induced neuronal death in rat brains. Collectively, these results provide evidence for a new mechanism by which microglial cells promote death of neuronal cells through synthesis and secretion of AGE-albumin, thereby likely contributing to neurodegenerative diseases such as AD.

Disorders of glucose metabolism are associated with increased risk for cardiovascular disease (CVD) complications, including coronary, peripheral and cerebral arterial disease, that account for the majority of morbidity and mortality among patients with diabetes mellitus (DM). These associations between glucose and CVD risk extend continuously well below the glycaemic thresholds established for the diagnosis of diabetes, including significantly increased risk associated with impaired fasting glucose, impaired glucose tolerance, and even high normal glucose concentrations. While these epidemiological observations have established a clear association between cardiovascular disease and dysglycaemia and suggest a direct causal link, the mechanisms by which hyperglycaemia may contribute to the development, progression and instability of atherosclerosis remain unclear. A number of recent advances in the realm of vascular biology have identified several novel, plausible pathways that might link hyperglycaemia with atherosclerosis, individually or in aggregate. Key among them are the interaction between advanced glycation end-products (AGEs) and the receptor for AGEs (RAGE), which exists as a trans-membrane signalling receptor and as a circulating form, soluble RAGE (sRAGE). The purpose of this review is to provide an overview of the present understanding of RAGE and sRAGE, their plausible role linking perturbed glucose metabolism with the development, progression and instability of atherosclerosis, and the potential therapeutic implications of modulation of this biological system.

OBJECTIVE

Advanced glycation end products (AGEs) and vascular adventitial fibroblasts (AFs) are involved in diabetes-related vascular complications. However, the effect of AGEs on AFs remains unclear. The aim of this study was to observe the impact of AGEs on cell migration capacity and associated inflammatory responses of AFs.

RESULTS

Isolated vascular AFs of Sprague-Dawley rats were cultured, harvested after 24h synchronization and challenged with AGE-HSA. AGE-HSA upregulated the expression of receptor for advanced glycation end products (RAGE), significantly increased the migration capacity and inflammatory mediators MCP-1, IL-6, VCAM-1 expressions on AFs. These effects could be significantly attenuated by anti-RAGE neutralizing antibody, p38, ERK1/2 and JNK MAPK inhibitors as well as by candesartan. AGE-HAS also upregulated NF-kappaB transcriptional activity and I-kappaB-alpha phosphorylation, effect that was significantly inhibited by candesartan.

CONCLUSIONS

AGE-HSA increased the migration capacity and inflammatory responses of rat AFs via RAGE-MAPK-NF-kappaB pathways. Candesartan effectively inhibited these effects which might be a novel vascular protection mechanism of candesartan.

BACKGROUND

Nonenzymatic advanced glycation and oxidation end-products, advanced glycation end-products (AGEs), impart a potent impact on vessels and other tissues in diabetic state and in euglycaemic conditions with increased oxidative stress. Insulin resistant (IR) polycystic ovary syndrome (PCOS) women, have elevated serum AGEs, increased receptor (RAGE) expression, and increased deposition with differential localization in the polycystic ovarian tissue (theca and granulosa) compared to normal.

OBJECTIVE

To determine whether the raised AGE levels in noninsulin resistant women with PCOS is a distinct finding compared with those presenting the isolated components of the syndrome and among PCOS subphenotypes. Noninsulin resistant women were selected in order to show that serum AGEs are elevated in PCOS independently of the presence of IR.

METHODS

Clinical trial.

METHODS

One hundred and ninety-three age- and BMI-matched young lean noninsulin resistant women were studied. Among them, 100 women were diagnosed with PCOS according to Rotterdam criteria, and divided to subphenotypes (hyperandrogenaemia with or without PCO morphology and with or without anovulation). Sixty-eight women with the isolated components of the PCOS phenotype were also studied along with 25 healthy women.

METHODS

Serum AGE levels, metabolic, hormonal profiles and intravaginal ultrasound were determined in all subjects.

RESULTS

The studied population did not differ in BMI, fasting insulin concentration, waist : hip and glucose : insulin ratios. PCOS women exhibited statistically higher AGEs levels (7.96 +/- 1.87 U/ml, P < 0.001) compared with those with isolated hyperandrogenaemia (5.61 +/- 0.61 U/ml), anovulation (5.53 +/- 1.06 U/ml), US-PCO morphology (5.26 +/- 0.25 U/ml) and controls (5.86 +/- 0.89 U/ml).

CONCLUSIONS

In PCOS, serum AGEs are distinctly elevated compared with women having the isolated characteristics of the syndrome. No difference was observed between PCOS subphenotypes. As chronic inflammation and increased oxidant stress have been incriminated in the pathophysiology of PCOS, the role of AGEs as inflammatory and oxidant mediators, may be linked with the metabolic and reproductive abnormalities of the syndrome.

Receptor for advanced glycation endproducts (RAGE) is a multi-ligand receptor that is able to bind several different ligands, including advanced glycation endproducts, high-mobility group protein (B)1 (HMGB1), S-100 calcium-binding protein, amyloid-β-protein, Mac-1, and phosphatidylserine. Its interaction is engaged in critical cellular processes, such as inflammation, proliferation, apoptosis, autophagy, and migration, and dysregulation of RAGE and its ligands leads to the development of numerous human diseases. In this review, we summarize the signaling pathways regulated by RAGE and its ligands identified up to date and demonstrate the effects of hyper-activation of RAGE signals on human diseases, focused mainly on renal disorders. Finally, we propose that RAGE and its ligands are the potential targets for the diagnosis, monitoring, and treatment of numerous renal diseases.

BACKGROUND

Recent studies suggest that the chemotactic G-protein-coupled-receptor (GPCR) formyl-peptide-receptor-like-1 (FPRL1) and the receptor-for-advanced-glycation-end-products (RAGE) play an important role in the inflammatory response involved in neurodegenerative disorders such as Alzheimer's disease (AD).Therefore, the expression and co-localisation of mouse formyl peptide receptor (mFPR) 1 and 2 as well as RAGE in an APP/PS1 transgenic mouse model using immunofluorescence and real-time RT-PCR were analysed. The involvement of rat or human FPR1/FPRL1 (corresponds to mFPR1/2) and RAGE in amyloid-β 1-42 (Aβ1-42)-induced signalling were investigated by extracellular signal regulated kinase 1/2 (ERK1/2) phosphorylation. Furthermore, the cAMP level in primary rat glial cells (microglia and astrocytes) and transfected HEK 293 cells was measured. Formyl peptide receptors and RAGE were inhibited by a small synthetic antagonist WRW4 and an inactive receptor variant delta-RAGE, lacking the intracytoplasmatic domains.

RESULTS

We demonstrated a strong increase of mFPR1/2 and RAGE expression in the cortex and hippocampus of APP/PS1 transgenic mice co-localised to the glial cells. In addition, the Aβ1-42-induced signal transduction is dependant on FPRL1, but also on FPR1. For the first time, we have shown a functional interaction between FPRL1/FPR1 and RAGE in RAGE ligands S100B- or AGE-mediated signalling by ERK1/2 phosphorylation and cAMP level measurement. In addition a possible physical interaction between FPRL1 as well as FPR1 and RAGE was shown with co-immunoprecipitation and fluorescence microscopy.

CONCLUSIONS

The results suggest that both formyl peptide receptors play an essential role in Aβ1-42-induced signal transduction in glial cells. The interaction with RAGE could explain the broad ligand spectrum of formyl peptide receptors and their important role for inflammation and the host defence against infections.

The receptor for advanced glycation end products (RAGE) has been reported to have a pivotal role in the pathogenesis of Alzheimer's disease (AD). This study investigated RAGE levels in the hippocampus and cortex of a triple transgenic mouse model of AD (3xTg-AD) using western blotting and immunohistochemical double-labeling to assess cellular localization. Analysis of western blots showed that there were no differences in the hippocampal and cortical RAGE levels in 10-month-old adult 3xTg-AD mice, but significant increases in RAGE expression were found in the 22- to 24-month-old aged 3xTg-AD mice compared with those of age-matched controls. RAGE-positive immunoreactivity was observed primarily in neurons of aged 3xTg-AD mice with very little labeling in non-neuronal cells, with the notable exception of RAGE presence in astrocytes in the hippocampal area CA1. In addition, RAGE signals were co-localized with the intracellular amyloid precursor protein (APP)/amyloid beta (Aβ) but not with the extracellular APP/Aβ. In aged 3xTg-AD mice, expression of human tau was observed in the hippocampal area CA1 and co-localized with RAGE signals. The increased presence of RAGE in the 3xTg-AD animal model showing critical aspects of AD neuropathology indicates that RAGE may contribute to cellular dysfunction in the AD brain.

Oxidative and carbonyl stress leads to generation of N(epsilon)-carboxymethyllysine-modified proteins (CML-mps), which are known to bind the receptor for advanced glycation end products (RAGE) and induce nuclear factor (NF)-kappaB-dependent proinflammatory gene expression. To determine the impact of CML-mps in vivo, RAGE-dependent sustained NF-kappaB activation was studied in resection gut specimens from patients with inflammatory bowel disease. Inflamed gut biopsy tissue demonstrated a significant up-regulation of RAGE and increased NF-kappaB activation. Protein extracts from the inflamed zones, but not from noninflamed resection borders, caused perpetuated NF-kappaB activation in cultured endothelial cells, which was mediated by CML-mps including CML-modified S100 proteins. The resulting NF-kappaB activation, lasting 5 days, was primarily inhibited by either depletion of CML-mps or by the addition of sRAGE, p44/42 and p38 MAPKinase-specific inhibitors. Consistently, CML-mps isolated from inflamed gut areas and rectally applied into mice caused NF-kappaB activation, increased proinflammatory gene expression, and histologically detectable inflammation in wild-type mice, but not in RAGE-/- mice. A comparable up-regulation of NF-kappaB and inflammation on rectal application of CML-mps was observed in IL-10-/- mice. Thus, CML-mps generated in inflammatory lesions have the capacity to elicit a RAGE-dependent intestinal inflammatory response.

BACKGROUND

Pulmonary arterial hypertension (PAH) is a vasculopathy characterized by enhanced pulmonary artery smooth muscle cell (PASMC) proliferation and suppressed apoptosis. This results in both increase in pulmonary arterial pressure and pulmonary vascular resistance. Recent studies have shown the implication of the signal transducer and activator of transcription 3 (STAT3)/bone morphogenetic protein receptor 2 (BMPR2)/peroxisome proliferator-activated receptor gamma (PPARγ) in PAH. STAT3 activation induces BMPR2 downregulation, decreasing PPARγ, which both contribute to the proproliferative and antiapoptotic phenotype seen in PAH. In chondrocytes, activation of this axis has been attributed to the advanced glycation end-products receptor (RAGE). As RAGE is one of the most upregulated proteins in PAH patients' lungs and a strong STAT3 activator, we hypothesized that by activating STAT3, RAGE induces BMPR2 and PPARγ downregulation, promoting PAH-PASMC proliferation and resistance to apoptosis.

RESULTS

In vitro, using PASMCs isolated from PAH and healthy patients, we demonstrated that RAGE is overexpressed in PAH-PASMC (6-fold increase), thus inducing STAT3 activation (from 10% to 40% positive cells) and decrease in BMPR2 and PPARγ levels (>50% decrease). Pharmacological activation of RAGE in control cells by S100A4 recapitulates the PAH phenotype (increasing RAGE by 6-fold, thus activating STAT3 and decreasing BMPR2 and PPARγ). In both conditions, this phenotype is totally reversed on RAGE inhibition. In vivo, RAGE inhibition in monocrotaline- and Sugen-induced PAH demonstrates therapeutic effects characterized by PA pressure and right ventricular hypertrophy decrease (control rats have an mPAP around 15 mm Hg, PAH rats have an mPAP >40 mm Hg, and with RAGE inhibition, mPAP decreases to 20 and 28 mm Hg, respectively, in MCT and Sugen models). This was associated with significant improvement in lung perfusion and vascular remodeling due to decrease in proliferation (>50% decrease) and BMPR2/PPARγ axis restoration (increased by ≥60%).

CONCLUSIONS

We have demonstrated the implications of RAGE in PAH etiology. Thus, RAGE constitutes a new attractive therapeutic target for PAH.

Advanced glycation end products (AGEs) and their receptor (RAGE) play a role in diabetic nephropathy. We have recently found that linagliptin, an inhibitor of dipeptidyl peptidase-4 (DPP-4) suppresses the AGE-induced oxidative stress generation and intercellular adhesion molecule-1 (ICAM-1) gene expression in endothelial cells. However, whether linagliptin could have beneficial effects on experimental diabetic nephropathy in a glucose-lowering independent manner remains unknown. To address the issue, this study examined the effects of linagliptin on renal damage in streptozotocin-induced diabetic rats. Serum levels of DPP-4 were significantly elevated in diabetic rats compared with control rats. Although linagliptin treatment for 2 weeks did not improve hyperglycemia in diabetic rats, linagliptin significantly reduced AGEs levels, RAGE gene expression, and 8-hydroxy-2'-deoxyguanosine, a marker of oxidative stress in the kidney of diabetic rats. Furthermore, linagliptin significantly reduced albuminuria, renal ICAM-1 mRNA levels, and lymphocyte infiltration into the glomeruli of diabetic rats. Our present study suggests that linagliptin could exert beneficial effects on diabetic nephropathy partly by blocking the AGE-RAGE-evoked oxidative stress generation in the kidney of streptozotocin-induced diabetic rats. Inhibition of DPP-4 by linagliptin might be a promising strategy for the treatment of diabetic nephropathy.

OBJECTIVE

The receptor for advanced glycation end products (RAGE)-ligand interaction has been linked to vascular complications. The family of soluble forms of RAGE (sRAGE) consists of splice variants and proteolytically cleaved and shed forms of RAGE. sRAGE may be a reflection of cell-bound RAGE. Because genetic variation in the RAGE gene may be associated with individual differences in sRAGE concentration and outcome, we investigated whether RAGE single-nucleotide polymorphisms (SNPs) were associated with circulating levels of sRAGE.

METHODS

Nine SNPs, covering the common RAGE gene variation, were genotyped in a Dutch cohort of subjects with normal glucose metabolism (n = 301), impaired glucose metabolism (n = 127), and type 2 diabetes mellitus (n = 146). We used linear regression analyses adjusted for age, sex, and glucose metabolism status to compare sRAGE levels across genotypes.

RESULTS

SNP rs2060700 (Gly82Ser) showed an association with sRAGE levels. Specifically, after adjustments for age, sex, and glucose metabolism, subjects with CT genotype had -527 pg/ml (95% confidence interval -724 to -330, P < 0.001) lower sRAGE levels compared with the CC genotype (age, sex, and glucose metabolism adjusted mean +/- SE values of 836 +/- 99 and 1369 +/- 26 pg/ml, respectively, P < 0.001). These results were confirmed in a subsample of a second cohort study of subjects with CT (n = 37) and CC genotype (n = 37). Immunoblotting using antibodies against amino acids 39-55 and 100-116 of RAGE also showed a similar decrease of sRAGE levels in the CT genotypes. No other SNPs showed an association with sRAGE levels. In addition, no associations between SNPs and the advanced glycation end products N(epsilon)-(carboxymethyl)lysine and N(epsilon)-(carboxyethyl)lysine were found.

CONCLUSIONS

The CC genotype of SNP rs2070600 (Gly82Ser) was strongly associated with higher sRAGE levels in a Dutch population. The mechanism by which Gly82Ser polymorphism alters the sRAGE levels remains to be elucidated.

Hyperglycemia associated with inflammation and oxidative stress is a major cause of vascular dysfunction and cardiovascular disease in diabetes. Recent data reports that a selective sodium-glucose co-transporter 2 inhibitor (SGLT2i), empagliflozin (Jardiance®), ameliorates glucotoxicity via excretion of excess glucose in urine (glucosuria) and significantly improves cardiovascular mortality in type 2 diabetes mellitus (T2DM). The overarching hypothesis is that hyperglycemia and glucotoxicity are upstream of all other complications seen in diabetes. The aim of this study was to investigate effects of empagliflozin on glucotoxicity, β-cell function, inflammation, oxidative stress and endothelial dysfunction in Zucker diabetic fatty (ZDF) rats. Male ZDF rats were used as a model of T2DM (35 diabetic ZDF-Leprfa/fa and 16 ZDF-Lepr+/+ controls). Empagliflozin (10 and 30mg/kg/d) was administered via drinking water for 6 weeks. Treatment with empagliflozin restored glycemic control. Empagliflozin improved endothelial function (thoracic aorta) and reduced oxidative stress in the aorta and in blood of diabetic rats. Inflammation and glucotoxicity (AGE/RAGE signaling) were epigenetically prevented by SGLT2i treatment (ChIP). Linear regression analysis revealed a significant inverse correlation of endothelial function with HbA1c, whereas leukocyte-dependent oxidative burst and C-reactive protein (CRP) were positively correlated with HbA1c. Viability of hyperglycemic endothelial cells was pleiotropically improved by SGLT2i. Empagliflozin reduces glucotoxicity and thereby prevents the development of endothelial dysfunction, reduces oxidative stress and exhibits anti-inflammatory effects in ZDF rats, despite persisting hyperlipidemia and hyperinsulinemia. Our preclinical observations provide insights into the mechanisms by which empagliflozin reduces cardiovascular mortality in humans (EMPA-REG trial).

Alzheimer's disease (AD) is the major age-dependent disease of the brain, but what instigates late-onset AD is not yet clear. Epidemiological, animal model, and cell biology findings suggest links between AD and diabetes. Although AD pathology is accelerated by diabetes in mice engineered to accumulate human-sequence amyloid-β (Aβ) peptides, they do not adequately model non-inherited AD. We investigated AD-type pathology induced solely by diabetes in genetically unmodified rabbits which generate human-sequence Aβ peptides. After 15 weeks, alloxan-treated diabetic rabbits with expected high blood glucose showed ~5-fold increase in Aβ40/Aβ42 in cortex and hippocampus, and significantly, generated Aβ-derived assemblies found in human AD. Deposits of these putative pathogenic toxins were detected by Aβ/Aβ oligomer antibodies in brain parenchyma and surrounding vasculature, also co-localizing with markedly elevated levels of RAGE. Soluble brain extracts showed diabetes-induced buildup of Aβ oligomers on dot-blots. Phospho-tau also was clearly elevated, overlapping with βIII-tubulin along neuronal tracts. Indications of retina involvement in AD led to examination of AD-type pathology in diabetic retinas and showed Aβ accumulation in ganglion and inner nuclear cell layers using Aβ/oligomer antibodies, and RAGE again was elevated. Our study identifies emergence of AD pathology in brain and retina as a major consequence of diabetes; implicating dysfunctional insulin signaling in late-onset AD, and a potential relationship between Aβ-derived neurotoxins and retinal degeneration in aging and diabetes, as well as AD. AD-type pathology demonstrated in genetically unmodified rabbits calls attention to the considerable potential of the model for investigation of AD pathogenesis, diagnostics, and therapeutics.

OBJECTIVE

The receptor for advanced glycation end-products (RAGE) has been implicated in diabetic microvascular complications, but several lines of evidence suggest that the soluble isoform of RAGE (sRAGE) may protect against AGE-mediated vessel damage. The characterized AGE Nepsilon-carboxymethyllysine (CML) is associated with diabetic microvascular complications. In the present study, we measured blood levels of sRAGE and CML-protein in diabetic patients with and without microvascular complications.

METHODS

Thirty patients with type-2 diabetes were recruited into the study, comprising 20 who had no microvascular complications, and 10 who had both retinal and renal complications. sRAGE was measured in serum by ELISA, and CML by competitive ELISA.

RESULTS

sRAGE blood levels were similar in both the controls and diabetic patients without microvascular complications. In patients with complications, the mean sRAGE blood level was significantly decreased (1068+/-231pg/mL) compared with diabetic patients without complications (P=0.028). CML-protein was increased in all diabetic patients, but to a higher extent in those who had microvascular complications.

CONCLUSIONS

The association of low sRAGE with high CML-protein levels in diabetic patients who developed severe diabetic complications supports the hypothesis that sRAGE protects vessels against AGE-mediated diabetic microvascular damage.

OBJECTIVE

To describe the histopathologic features of Descemet's membrane (DM) obtained from Fuchs' endothelial corneal dystrophy (FECD) corneas undergoing Descemet's stripping with endothelial keratoplasty (DSEK) and to assess the presence of advanced glycation end products (AGEs) and their receptors in FECD endothelium and DM.

METHODS

Prospective observational case series.

METHODS

Five eyes of 5 patients undergoing DSEK for FECD and 4 normal control eyebank corneas.

METHODS

Descemet's membrane and corneal endothelium from FECD patients undergoing DSEK were assessed with hematoxylin-eosin staining and immunohistochemistry for AGEs, receptor of AGEs (RAGE), and galectin 3 (AGE-R3).

METHODS

Histopathologic abnormalities and presence of AGEs, RAGE, and AGE-R3 in DSEK specimens.

RESULTS

Histopathologic assessment of DSEK specimens from FECD patients disclosed thickening and nodularity of DM and loss of endothelial cells. Immunohistochemical staining of FECD DM for AGE, RAGE, and AGE-R3 showed an abundance of AGEs in the anterior portion of DM, mild positivity for RAGE, and moderate positivity for AGE-R3.

CONCLUSIONS

Tissue quality after DSEK is sufficient to allow detailed histopathologic analysis. The presence of AGEs, RAGE, and AGE-R3 in DM and corneal endothelium of FECD patients supports a link between accumulation of AGEs, oxidative stress, and corneal endothelial cell apoptosis in the pathogenesis of FECD.

Cigarette smoking, obesity, type 2 diabetes, and, to a lesser extent, meat cooked at high temperatures are associated with pancreatic cancer. Cigarette smoke and foods cooked at higher temperatures are major environmental sources of advanced glycation end products (AGE). AGEs accumulate during hyperglycemia and elicit oxidative stress and inflammation through interaction with the receptor for AGEs (RAGE). Soluble RAGE (sRAGE) acts as an anti-inflammatory factor to neutralize AGEs and block the effects mediated by RAGE. In this study, we investigated the associations of prediagnostic measures of N(ε)-(carboxymethyl)-lysine (CML)-AGE and sRAGE with pancreatic cancer in a case-cohort study within a cohort of 29,133 Finnish male smokers. Serum samples and exposure information were collected at baseline (1985-1988). We measured CML-AGE, sRAGE, glucose, and insulin concentrations in fasting serum from 255 incident pancreatic cancer cases that arose through April 2005 and from 485 randomly sampled subcohort participants. Weighted Cox proportional hazard regression models were used to calculate relative risks (RR) and 95% CI, adjusted for age, years of smoking, and body mass index. CML-AGE and sRAGE were mutually adjusted. CML-AGE levels were not associated with pancreatic cancer [fifth compared with first quintile, RR (95% CI): 0.68 (0.38-1.22), P(trend) = 0.27]. In contrast, sRAGE levels were inversely associated with pancreatic cancer [fifth compared with first quintile, RR (95% CI): 0.46 (0.23-0.73), P(trend) = 0.002]. Further adjustment for glucose or insulin levels did not change the observed associations. Our findings suggest that sRAGE is inversely associated with pancreatic cancer risk among Finnish male smokers.

The role of tumor cells in synthesizing pro-inflammatory molecules is still controversial. Here we report that hypoxic treatment of the MCF-7 human mammary adenocarcinoma cell line induced activation of hypoxia-inducible factor 1alpha (HIF-1alpha) and nuclear factor-kappa B (NF-kappaB). Importantly, hypoxia regulated expression of alarmin receptors such as the receptor for advanced glycation end products (RAGE) and the purinoreceptor (P2X7R), and up-regulated inflammatory response (IR) genes such as the inducible enzymes nitric oxide synthase (NOS2), cycloxygenase (COX2), and the acute-phase protein pentraxin-3 (PTX3). Hypoxia also stimulated chemokine (C-X-C motif) receptor 4 (CXCR4) mRNA synthesis. In fact, the CXCR4 ligand stromal-derived factor-1alpha (SDF-1alpha) increased invasion and migration of hypoxic MCF-7 cells. Inhibition of HIF-1alpha by chetomin and NF-kappaB by parthenolide reduced mRNA and protein expression of the studied molecules and prevented invasion of hypoxic MCF-7 cells. Moreover, solid invasive mammary tumor microenvironment was analyzed after laser-capture microdissection (LCMD) comparing tumor versus host normal tissue. Nuclear translocation of HIF-1alpha and NF-kappaB and up-regulation of IR, CXCR4, estrogen receptor alpha (ERalpha), and epithelial growth factor receptor (EGFR) was observed in tumor but not in host normal tissue in the absence of a local inflammatory leukocyte infiltrate. We conclude that under hypoxic conditions MCF-7 cells acquire a pro-inflammatory phenotype, and that solid human mammary carcinoma evidenced a similar activation of HIF-1alpha, NF-kappaB, and IR genes in malignant tumor cells as compared to the normal host tissues. We suggest a role for IR activation in the malignant progression of transformed cells.

Advanced glycation endproducts (AGEs) are a group of modified molecular species formed by nonenzymatic reactions between the aldehydic group of reducing sugars with proteins, lipids, or nucleic acids. Formation and accumulation of AGEs are related to the aging process and are accelerated in diabetes. AGEs are generated in hyperglycemia, but their production also occurs in settings characterized by oxidative stress and inflammation. These species promote vascular damage and acceleration of atherosclerotic plaque progression mainly through two mechanisms: directly, altering the functional properties of vessel wall extracellular matrix molecules, or indirectly, through activation of cell receptor-dependent signaling. Interaction between AGEs and the key receptor for AGEs (RAGE), a transmembrane signaling receptor which is present in all cells relevant to atherosclerosis, alters cellular function, promotes gene expression, and enhances the release of proinflammatory molecules. The importance of the AGE-RAGE interaction and downstream pathways, leading to vessel wall injury and plaque development, has been amply established in animal studies. Moreover, the deleterious link of AGEs with diabetic vascular complications has been suggested in many human studies. Blocking the vicious cycle of AGE-RAGE axis signaling may be essential in controlling and preventing cardiovascular complications. In this article, we review the pathogenetic role of AGEs in the development, progression and instability of atherosclerosis, and the potential targets of this biological system for the prevention and treatment of cardiovascular disease.

Experimental and epidemiological studies have revealed that chronic inflammation contributes to cancer progression and even predisposes to cellular transformation. Inflammatory infiltrates in papillary thyroid cancer include lymphocytes, macrophages and cytokines. High-mobility group box 1 protein (HMGB1) is a late inflammatory cytokine that signals danger to the immune system through the receptor for advanced glycation end-products (RAGE) and Toll-like receptor. The activation of the above receptors results in the secretion of growth, chemotactic and angiogenic factors that contribute to chronic inflammation. In this study, we suggest that apart from the activation of signal transduction pathways by the activation of RAGE, the indirect inhibition of cell cycle regulators [such as phosphatase and tensin homolog (PTEN)] may also cause an increase in cell growth and motility. MicroRNAs (miRNAs) have increasingly been implicated in regulating the malignant progression of cancer. MiR-221 and miR-222 have been found to be deregulated in human papillary thyroid carcinomas. They are involved in cell proliferation through the inhibition of the cell cycle regulator, p27kip1, in human papillary carcinomas. In this study, we show that HMGB1 increases the expression of miR-221 and miR-222 in primary cultures of excised papillary lesions and in an established papillary cancer cell line (BC PAP). The overexpression of oncogenic miR-221 and miR-222 caused by HMGB1 is associated with an increase in malignancy scores, namely cell growth and motility.

OBJECTIVE

Rage attacks have been documented in youth with varied psychiatric disorders, but few data have been reported on the clinical characteristics and correlates of rage attacks among children with obsessive-compulsive disorder (OCD).

METHODS

Participants were 86 children (ages 6-16 years) with a primary diagnosis of OCD. Patients and their primary caregiver were administered clinician-rated measures of obsessive-compulsive severity and rage severity. Children completed the Center for Epidemiologic Studies Depression Scale and the Child Sheehan Disability Scale-Child, whereas parents completed the Rage Attacks Questionnaire, Aberrant Behavior Checklist-Irritability Scale, Children's Affective Lability Scale, and Child Sheehan Disability Scale-Parent.

RESULTS

Rage was common among youth with OCD and was associated with varied clinical characteristics. Rage severity accounted for functional impairment beyond the influence of obsessive-compulsive symptom severity; however, these relations were explained by the impact of family accommodation.

CONCLUSIONS

These data suggest that rage attacks are relatively common, have a negative impact on illness presentation, and contribute to functional impairment above and beyond obsessive-compulsive symptom severity. Rage may contribute to family accommodation of symptoms, which may further affect obsessive-compulsive symptom severity and impairment.