BACKGROUND

RAGE (receptor for advanced glycation end products [AGEs]) plays a role in diabetic atherosclerosis. Recently, we have demonstrated enhanced expression of cyclooxygenase-2 and PGE synthase-1 (COX-2/mPGES-1) in human symptomatic plaques, and provided evidence that it is associated with metalloproteinase (MMP)-induced plaque rupture. However, the specific transmembrane signaling pathway(s) influencing plaque COX-2/mPGES-1 expression is unknown. The aim of this study was to characterize RAGE expression in human plaques and to correlate it with the inflammatory infiltration, COX-2/mPGES-1 and MMP expression, and with clinical evidence of diabetes.

RESULTS

Plaques obtained from 60 patients undergoing carotid endarterectomy were divided into diabetic and nondiabetic according to clinical evidence of type 2 diabetes. Plaques were subjected to analysis of RAGE, NF-kappaB, COX-2/mPGES-1, MMP-2 and MMP-9, lipid and oxidized LDL (oxLDL) content, and collagen content by immunohistochemistry and Western blot, whereas zymography was used to detect MMP activity. Immunohistochemistry was used to identify CD68+ macrophages, CD3+ T-lymphocytes, smooth muscle cells (SMCs), and HLA-DR+ inflammatory cells. Diabetic plaques had more (P<0.0001) macrophages, T-lymphocytes, and HLA-DR+ cells, more (P<0.0001) immunoreactivity for RAGE, activated NF-kappaB, COX-2/mPGES-1, and MMPs, increased (P<0.0001) gelatinolytic activity, reduced (P<0.0001) collagen content, and increased (P<0.0001) lipid and oxLDL content. Interestingly, RAGE, COX-2/mPGES-1, and MMP expression was linearly correlated with plasma level of HbA1c.

CONCLUSIONS

In conclusion, this study demonstrates in humans that RAGE overexpression is associated with enhanced inflammatory reaction and COX-2/mPGES-1 expression in diabetic plaque macrophages, and this effect may contribute to plaque destabilization by inducing culprit metalloproteinase expression.

Amphoterin (HMGB1) is a 30-kD heparin-binding protein involved in process extension and migration of cells by a mechanism involving the receptor for advanced glycation end products (RAGE). High levels of amphoterin are released to serum during septic shock. We have studied the expression of amphoterin in monocytes and the role of amphoterin and RAGE in monocyte transendothelial migration. Un-activated monocytes in suspension did not reveal amphoterin on their surface, but adherent monocytes exported amphoterin to the cell surface. Immunohistochemical staining of arterial thrombi in vivo revealed amphoterin in mononuclear cells and in surrounding extracellular matrix. Amphoterin was secreted from phorbol ester and interferon-gamma (IFN-gamma)-activated macrophages, and the secretion was inhibited by blocking the adenosine 5'-triphosphate (ATP)-binding cassette transporter-1, a member of the multidrug resistance protein family. Amphoterin was specifically adhesive for monocytes in peripheral blood leukocyte adhesion assay. Adhesion caused an extensive spreading of cells, which was inhibited by the dominant-negative RAGE receptor (soluble ectodomain of RAGE), and adhesion up-regulated chromogranin expression in monocytes, also suggesting a RAGE-dependent interaction. Monocyte transendothelial migration was efficiently inhibited by anti-amphoterin and anti-RAGE antibodies and by the soluble RAGE. We suggest that amphoterin is an autocrine/paracrine regulator of monocyte invasion through the endothelium.

BACKGROUND

Intestinal inflammation in Crohn's disease (CD) and ulcerative colitis (UC) is characterised by an influx of neutrophils into the intestinal mucosa. S100A12 is a calcium binding protein with proinflammatory properties. It is secreted by activated neutrophils and interacts with the multiligand receptor for advanced glycation end products (RAGE). Promising anti-inflammatory effects of blocking agents for RAGE have been reported in murine models of colitis.

OBJECTIVE

To investigate expression and serum concentrations of S100A12 in inflammatory bowel disease (IBD).

METHODS

We performed immunohistochemical studies and immunofluorescence microscopy in biopsies from patients with CD and UC. S100A12 serum concentrations were analysed using a sandwich ELISA.

RESULTS

Immunohistochemical studies revealed profound expression of S100A12 in inflamed intestinal tissue from IBD patients whereas no expression was found in tissue from healthy controls. Staining for S100A12 during chronic active CD and UC was restricted to infiltrating neutrophils. Serum S100A12 levels were significantly elevated in patients with active CD (470 (125) ng/ml; p<0.001, n=30) as well as those with active UC (400 (120) ng/ml; p<0.01, n=15) compared with healthy controls (75 (15) ng/ml; n=30). Even in inactive disease, elevated serum concentrations were found, at least in CD. S100A12 levels were well correlated with disease activity in CD and UC.

CONCLUSIONS

We demonstrated that neutrophil derived S100A12 is strongly upregulated during chronic active IBD, suggesting an important role during the pathogenesis of IBD. Serum S100A12 may serve as a useful marker for disease activity in patients with IBD.

The receptor for advanced glycation end products (RAGE) is a member of the immunoglobulin superfamily of cell surface molecules. As a pattern-recognition receptor capable of binding a diverse range of ligands, it is typically expressed at low levels under normal physiological conditions in the majority of tissues. In contrast, the lung exhibits high basal level expression of RAGE localised primarily in alveolar type I (ATI) cells, suggesting a potentially important role for the receptor in maintaining lung homeostasis. Indeed, disruption of RAGE levels has been implicated in the pathogenesis of a variety of pulmonary disorders including cancer and fibrosis. Furthermore, its soluble isoforms, sRAGE, which act as decoy receptors, have been shown to be a useful marker of ATI cell injury. Whilst RAGE undoubtedly plays an important role in the biology of the lung, it remains unclear as to the exact nature of this contribution under both physiological and pathological conditions.

Microglia are critical for amyloid-beta peptide (Abeta)-mediated neuronal perturbation relevant to Alzheimer's disease (AD) pathogenesis. We demonstrate that overexpression of receptor for advanced glycation end products (RAGE) in imbroglio exaggerates neuroinflammation, as evidenced by increased proinflammatory mediator production, Abeta accumulation, impaired learning/memory, and neurotoxicity in an Abeta-rich environment. Transgenic (Tg) mice expressing human mutant APP (mAPP) in neurons and RAGE in microglia displayed enhanced IL-1beta and TNF-alpha production, increased infiltration of microglia and astrocytes, accumulation of Abeta, reduced acetylcholine esterase (AChE) activity, and accelerated deterioration of spatial learning/memory. Notably, introduction of a signal transduction-defective mutant RAGE (DN-RAGE) to microglia attenuates deterioration induced by Abeta. These findings indicate that RAGE signaling in microglia contributes to the pathogenesis of an inflammatory response that ultimately impairs neuronal function and directly affects amyloid accumulation. We conclude that blockade of microglial RAGE may have a beneficial effect on Abeta-mediated neuronal perturbation relevant to AD pathogenesis.-Fang, F., Lue, L.-F., Yan, S., Xu, H., Luddy, J. S., Chen, D., Walker, D. G., Stern, D. M., Yan, S., Schmidt, A. M., Chen, J. X., Yan, S. S. RAGE-dependent signaling in microglia contributes to neuroinflammation, Abeta accumulation, and impaired learning/memory in a mouse model of Alzheimer's disease.

Immune dysfunction may contribute to tumor progression in gastric cancer (GC) patients. One mechanism of immune dysfunction is the suppression of T cell activation and impairment of the efficacy of cancer immunotherapy by myeloid-derived suppressor cells (MDSCs). We assessed the phenotype and immunosuppressive function of MDSCs in GC patients. We further investigated the role of S100A8/A9 in GC and the relationship between S100A8/A9 and MDSC function. Lastly, the effect of MDSCs on survival rates and its potential as a prognostic factor in GC patients were investigated. MDSCs from PBMCs of GC patients were identified by comparing the expression of specific surface markers with PBMCs from healthy individuals. The ability of MDSCs to suppress T lymphocyte response and the effect of S100A8/A9 and RAGE blocking were tested in vitro by (autologous) MLR. GC patients had significantly more MDSCs than healthy individuals. These MDSCs suppressed both T lymphocyte proliferation and IFN-γ production and had high arginase-I expression. Levels of S100A8/A9 in plasma were higher in GC patients compared with healthy individuals, and they correlated with MDSC levels in the blood. Blocking of S100A8/A9 itself and the S100A8/A9 receptor RAGE on MDSCs from GC patients abrogated T cell effector function. We found that high levels of MDSCs correlated with more advanced cancer stage and with reduced survival (p = 0.006). S100A8/A9 has been identified as a potential target to modulate antitumor immunity by reversing MDSC-mediated immunosuppression.

The receptor for advanced glycation endproducts (RAGE) is expressed under pathological conditions in many tissues and has been assigned many functions. We demonstrate, in normal human lung tissue, the preferential and highly abundant expression of RAGE by quantitative polymerase chain reaction. In addition, RAGE expression, as a specific differentiation marker of alveolar epithelial type I cells (AT I cells), and its localization to the basolateral plasma membrane have been confirmed by means of newly raised monoclonal antibodies. The physiological function of RAGE on AT I cells has previously remained elusive. By using HEK293 cells transfected with cDNA encoding for full-length RAGE, we show that RAGE enhances the adherence of epithelial cells to collagen-coated surfaces and has a striking capacity for inducing cell spreading. The preferential binding of RAGE to collagen has been confirmed by assaying the binding of soluble RAGE to various substrates. RAGE might thus assist AT I cells to acquire a spreading morphology, thereby ensuring effective gas exchange and alveolar stability.

Lung alveolar epithelial cells are comprised of type I (ATI) and type II (ATII) cells. ATI cells are polarized, although they have very flat morphology. The identification of marker proteins for apical and basolateral membranes of ATI cells is important to investigate into the differentiation of ATI cells. In this paper, we characterized receptor for advanced glycation end-products (RAGE) as a marker for ATI cells. RAGE was localized on basolateral membranes of ATI cells in the immunoelectron microscopy and its expression was enhanced in a parallel manner to the differentiation of ATI cells in vivo and in primary cultures of ATII cells. RAGE and T1 alpha, a well-known ATI marker protein, were targeted to basolateral and apical membranes, respectively, when expressed in polarized Madine Darby canine kidney cells. Moreover, RAGE was expressed in ATI cells after T1 alpha in vivo and in ex in vivo organ cultures. In conclusion, RAGE is a marker for basolateral membranes of well-differentiated ATI cells. ATI cells require some signal provided by the in vivo environment to express RAGE.

OBJECTIVE

Advanced glycation endproducts, AGEs, and its specific receptor, RAGE, are involved in diabetic vascular complications. Endogenous secretory RAGE, esRAGE, has been identified as an alternatively spliced form of RAGE, and shown to act as a decoy receptor for AGE. Here, we measured plasma esRAGE level with a recently developed enzyme-linked immunosorbent assay (ELISA) and examined its association with atherosclerosis in age- and gender-matched 203 type 2 diabetic and 134 nondiabetic subjects.

RESULTS

Plasma esRAGE was inversely associated with carotid or femoral atherosclerosis, as quantitatively measured as intimal-medial thickness (IMT) by arterial ultrasound. Stepwise regression analyses revealed that plasma esRAGE was the third strongest and independent factor associated with carotid IMT, following age and systolic blood pressure. Plasma esRAGE was significantly lower in diabetic patients (0.176+/-0.092 ng/mL) than nondiabetic controls (0.253+/-0.111). Of note, in all, diabetic or nondiabetic group, plasma esRAGE was significantly and inversely correlated with components of the metabolic syndrome including body mass index, blood pressure, triglyceride, HbA1c, or an insulin resistance index. Stepwise regression analyses showed that body mass index or insulin resistance index was the major factor determining plasma esRAGE in all, nondiabetic or diabetic population.

CONCLUSIONS

esRAGE is a novel and potential protective factor for the metabolic syndrome and atherosclerosis.

We have previously shown that diabetes significantly enhances apoptosis of osteoblastic cells in vivo and that the enhanced apoptosis contributes to diabetes impaired new bone formation. A potential mechanism is enhanced apoptosis stimulated by advanced glycation end products (AGEs). To investigate this further, an advanced glycation product, carboxymethyl lysine modified collagen (CML-collagen), was injected in vivo and stimulated a 5-fold increase in calvarial periosteal cell apoptosis compared to unmodified collagen. It also induced apoptosis in primary cultures of human or neonatal rat osteoblastic cells or MC3T3-E1 cells in vitro. Moreover, the apoptotic effect was largely mediated through RAGE receptor. CML-collagen increased p38 and JNK activity 3.2- and 4.4-fold, respectively. Inhibition of p38 and JNK reduced CML-collagen stimulated apoptosis by 45% and 59% and by 90% when used together (P<0.05). The predominant apoptotic pathway induced by CML-collagen involved caspase-8 activation of caspase-3 and was independent of NF-kappaB activation. When osteoblastic cells were exposed to a long-term low dose incubation with CML-collagen, there was a higher degree of apoptosis compared to short-term incubation. In more differentiated osteoblastic cultures, apoptosis was enhanced even further. These results indicate that advanced glycation end products, which accumulate in diabetic and aged individuals, may promote apoptosis of osteoblastic cells and contribute to deficient bone formation.

While it is thought that advanced glycation end products (AGEs) act by stimulating transforming growth factor (TGF)-beta to mediate diabetic injury, we report that AGEs can activate TGF-beta signaling, Smads, and mediate diabetic scarring directly and independently of TGF-beta. AGEs activate Smad2/3 in renal and vascular cells at 5 min, peaking over 15-30 min before TGF-beta synthesis at 24 h and occurs in TGF-beta receptor I and II mutant cells. This is mediated by RAGE and ERK/p38 mitogen-activated protein kinases (MAPKs). In addition, AGEs also activate Smads at 24 h via the classic TGF-beta-dependent pathway. A substantial inhibition of AGE-induced Smad activation and collagen synthesis by ERK/p38 MAPK inhibitors, but not by TGF-beta blockade, suggests that the MAPK-Smad signaling crosstalk pathway is a key mechanism in diabetic scarring. Prevention of AGE-induced Smad activation and collagen synthesis by overexpression of Smad7 indicates that Smad signaling may play a critical role in diabetic complications. This is further supported by the findings that activation of Smad2/3 in human diabetic nephropathy and vasculopathy is associated with local deposition of AGEs and up-regulation of RAGE. Thus, AGEs act by activating Smad signaling to mediate diabetic complications via both TGF-beta-dependent and -independent pathways, shedding new light on the pathogenesis of diabetic organ injury.

Diabetes is associated with increased prevalence, severity, and progression of periodontal disease. To test the hypothesis that activation of RAGE (Receptor for Advanced Glycation End products) contributes to the pathogenesis of diabetes-associated periodontitis, we treated diabetic mice, infected with the human periodontal pathogen Porphyromonas gingivalis, with soluble RAGE (sRAGE). sRAGE is the extracellular domain of the receptor, which binds ligand and blocks interaction with, and activation of, cell-surface RAGE. Blockade of RAGE diminished alveolar bone loss in a dose-dependent manner. Moreover, we noted decreased generation of the proinflammatory cytokines TNF-alpha and IL-6 in gingival tissue, as well as decreased levels of matrix metalloproteinases. Gingival AGEs were also reduced in mice treated with sRAGE, paralleling the observed suppression in alveolar bone loss. These findings link RAGE and exaggerated inflammatory responses to the pathogenesis of destructive periodontal disease in diabetes.

The receptor for advanced glycation end products (RAGE) is a member of the immunoglobulin superfamily of cell surface proteins that has been implicated as a progression factor in a number of pathologic conditions from chronic inflammation to cancer to Alzheimer's disease. In such conditions, RAGE acts to facilitate pathogenic processes. Its secreted isoform, soluble RAGE or sRAGE, has the ability to prevent RAGE signaling by acting as a decoy. sRAGE has been used successfully in animal models of a range of diseases to antagonize RAGE-mediated pathologic processes. In humans, sRAGE results from alternative splicing of RAGE mRNA. This study was aimed to determine whether the same holds true for mouse sRAGE and, in addition, to biochemically characterize mouse sRAGE. The biochemical characteristics examined include glycosylation and disulfide patterns. In addition, sRAGE was found to bind heparin, which may mediate its distribution in the extracellular matrix and cell surfaces of tissues. Finally, our data indicated that sRAGE in the mouse is likely produced by carboxyl-terminal truncation, in contrast to the alternative splicing mechanism reported in humans.

Chronic hyperglycemia and activation of receptor for advanced glycation end products (RAGE) are known risk factors for microvascular disease development in diabetic retinopathy. Thioredoxin-interacting protein (TXNIP), an endogenous inhibitor of antioxidant thioredoxin (TRX), plays a causative role in diabetes and its vascular complications. Herein we investigate whether HG and RAGE induce inflammation in rat retinal endothelial cells (EC) under diabetic conditions in culture through TXNIP activation and whether epigenetic mechanisms play a role in inflammatory gene expression. We show that RAGE activation by its ligand S100B or HG treatment of retinal EC induces the expression of TXNIP and inflammatory genes such as Cox2, VEGF-A, and ICAM1. TXNIP silencing by siRNA impedes RAGE and HG effects while stable over-expression of a cDNA for human TXNIP in EC elevates inflammation. p38 MAPK-NF-kappaB signaling pathway and histone H3 lysine (K) nine modifications are involved in TXNIP-induced inflammation. Chromatin immunoprecipitation (ChIP) assays reveal that TXNIP over-expression in EC abolishes H3K9 tri-methylation, a marker for gene inactivation, and increases H3K9 acetylation, an indicator of gene induction, at proximal Cox2 promoter bearing the NF-kappaB-binding site. These findings have important implications toward understanding the molecular mechanisms of ocular inflammation and endothelial dysfunction in diabetic retinopathy.

Hypoxia is often found in solid tumors and is associated with tumor progression and poor clinical outcomes. The exact mechanisms related to hypoxia-induced invasion and metastasis remain unclear. We elucidated the mechanism by which the nuclear-damage-associated molecular pattern molecule, high-mobility group box 1 (HMGB1), released under hypoxic stress, can induce an inflammatory response to promote invasion and metastasis in hepatocellular carcinoma (HCC) cells. Caspase-1 activation was found to occur in hypoxic HCC cells in a process that was dependent on the extracellular release of HMGB1 and subsequent activation of both Toll-like receptor 4 (TLR4)- and receptor for advanced glycation endproducts (RAGE)-signaling pathways. Downstream from hypoxia-induced caspase-1 activation, cleavage and release of proinflammatory cytokines interleukin (IL)-1β and -18 occurred. We further demonstrate that overexpression of HMGB1 or treatment with recombinant HMGB1 enhanced the invasiveness of HCC cells, whereas stable knockdown of HMGB1 remarkably reduced HCC invasion. Moreover, in a murine model of HCC pulmonary metastasis, stable knockdown of HMGB1 suppressed HCC invasion and metastasis.

CONCLUSIONS

These results suggest that in hypoxic HCC cells, HMGB1 activates TLR4- and RAGE-signaling pathways to induce caspase-1 activation with the subsequent production of multiple inflammatory mediators, which, in turn, promote cancer invasion and metastasis.

BACKGROUND

The general increase in reactive oxygen species generated from glucose-derived advanced glycation endproducts (AGEs) is among the key mechanisms implicated in tissue injury due to diabetes. AGE-rich foods could exacerbate diabetic injury, at least by raising the endogenous AGE.

METHODS

Herein, we tested whether, prior to ingestion, diet-derived AGEs contain species with cell activating (TNFalpha), chemical (cross-linking) or cell oxidative properties, similar to native AGEs. Glutathione (GSH) and GSH peroxidase (GPx) were assessed after exposure of human umbilical vein endothelial cell (HUVECs) to affinity-purified food-AGE extracts, each exposed to 250 degrees C, for 10 min, along with synthetic AGEs.

RESULTS

Animal product-derived AGE, like synthetic methylglyoxal-bovine serum albumin (MG-BSA), AGE-BSA, and AGE-low density lipoprotein (AGE-LDL), induced a dose- and time-dependent depletion of GSH (()60-75%, p, 0.01) and an increase in GPx activity (()500-600%, p < 0.01), consistent with marked TNFalpha and cross-link formation (p < 0.05); this contrasted with the low bioreactivity of starch/vegetable AGE-extracts, which was similar to that of control BSA and CML- BSA and BSA (p:NS). Anti-AGE-R1,2,3 and -RAGE IgG each inhibited cell-associated (125) I-dAGE by approximately 30-55%; GSH/GPx were effectively blocked by N-acetyl-cysteine (NAC, 800 uM, p < 0.01) and aminoguanidine-HCl (AG, 100 uM, p < 0.01).

CONCLUSIONS

Thus, food-derived AGE, prior to absorption, contain potent carbonyl species, that can induce oxidative stress and promote inflammatory signals.

Advanced glycation end product (AGE) activation of the signal-transducing receptor for AGE (RAGE) has been linked to a proinflammatory phenotypic change within cells. However, the precise intracellular signaling pathways involved have not been elucidated. We demonstrate here that human serum albumin modified with N(epsilon)-(carboxymethyl)lysine (CML), a major AGE adduct that progressively accumulates with aging, diabetes, and renal failure, induced nuclear factor (NF)-kappaB-driven reporter gene expression in human monocytic THP-1 cells. The NF-kappaB response was blocked with a synthetic peptide corresponding to the putative ligand-binding domain of RAGE, with anti-RAGE antiserum, and by coexpression of truncated receptors lacking the intracellular domain. Signal transduction from RAGE to NF-kappaB involved the generation of reactive oxygen species, since reporter gene expression was blocked with the antioxidant N-acetyl-L-cysteine. CML-modified albumin produced rapid transient activation of tyrosine phosphorylation, extracellular signal-regulated kinase 1 and 2, and p38 mitogen-activated protein kinase (MAPK), but not c-Jun NH(2)-terminal kinase. RAGE-mediated NF-kappaB activation was suppressed by the selective p38 MAPK inhibitor SB203580 and by coexpression of a kinase-dead p38 dominant-negative mutant. Activation of NF-kappaB by CML-modified albumin increased secretion of proinflammatory cytokines (tumor necrosis factor-alpha, interleukin-1beta, and monocyte chemoattractant protein-1) severalfold, and inhibition of p38 MAPK blocked these increases. These results indicate that p38 MAPK activation mediates RAGE-induced NF-kappaB-dependent secretion of proinflammatory cytokines and suggest that accelerated inflammation may be a consequence of cellular activation induced by this receptor.

Diabetic nephropathy is a major cause of morbidity and mortality in diabetic patients. Two key mechanisms implicated in the development of diabetic nephropathy include advanced glycation and oxidative stress. Advanced glycation is the irreversible attachment of reducing sugars onto amino groups of proteins to form advanced glycation end products (AGEs). AGE modification of proteins may lead to alterations in normal function by inducing cross-linking of extracellular matrices. Intracellular formation of AGEs also can cause generalized cellular dysfunction. Furthermore, AGEs can mediate their effects via specific receptors, such as the receptor for AGE (RAGE), activating diverse signal transduction cascades and downstream pathways, including generation of reactive oxygen species (ROS). Oxidative stress occurs as a result of the imbalance between ROS production and antioxidant defenses. Sources of ROS include the mitochondria, auto-oxidation of glucose, and enzymatic pathways including nicotinamide adenine dinucleotide phosphate reduced (NAD[P]H) oxidase. Beyond the current treatments to treat diabetic complications such as the optimization of blood pressure and glycemic control, it is predicted that new therapies designed to target AGEs, including AGE formation inhibitors and cross-link breakers, as well as targeting ROS using novel highly specific antioxidants, will become part of the treatment regimen for diabetic renal disease.

Soluble amyloid-beta (Abeta) peptide is likely to play a key role during early stages of Alzheimer's disease (AD) by perturbing synaptic function and cognitive processes. Receptor for advanced glycation end products (RAGE) has been identified as a receptor involved in Abeta-induced neuronal dysfunction. We investigated the role of neuronal RAGE in Abeta-induced synaptic dysfunction in the entorhinal cortex, an area of the brain important in memory processes that is affected early in AD. We found that soluble oligomeric Abeta peptide (Abeta42) blocked long-term potentiation (LTP), but did not affect long-term depression, paired-pulse facilitation, or basal synaptic transmission. In contrast, Abeta did not inhibit LTP in slices from RAGE-null mutant mice or in slices from wild-type mice treated with anti-RAGE IgG. Similarly, transgenic mice expressing a dominant-negative form of RAGE targeted to neurons showed normal LTP in the presence of Abeta, suggesting that neuronal RAGE functions as a signal transducer for Abeta-mediated LTP impairment. To investigate intracellular pathway transducing RAGE activation by Abeta, we used inhibitors of stress activated kinases. We found that inhibiting p38 mitogen-activated protein kinase (p38 MAPK), but not blocking c-Jun N-terminal kinase activation, was capable of maintaining LTP in Abeta-treated slices. Moreover, Abeta-mediated enhancement of p38 MAPK phosphorylation in cortical neurons was reduced by blocking antibodies to RAGE. Together, our results indicate that Abeta impairs LTP in the entorhinal cortex through neuronal RAGE-mediated activation of p38 MAPK.

We present an adaptive Bayesian method for dose-finding in phase I/II clinical trials based on trade-offs between the probabilities of treatment efficacy and toxicity. The method accommodates either trinary or bivariate binary outcomes, as well as efficacy probabilities that possibly are nonmonotone in dose. Doses are selected for successive patient cohorts based on a set of efficacy-toxicity trade-off contours that partition the two-dimensional outcome probability domain. Priors are established by solving for hyperparameters that optimize the fit of the model to elicited mean outcome probabilities. For trinary outcomes, the new algorithm is compared to the method of Thall and Russell (1998, Biometrics 54, 251-264) by application to a trial of rapid treatment for ischemic stroke. The bivariate binary outcome case is illustrated by a trial of graft-versus-host disease treatment in allogeneic bone marrow transplantation. Computer simulations show that, under a wide rage of dose-outcome scenarios, the new method has high probabilities of making correct decisions and treats most patients at doses with desirable efficacy-toxicity trade-offs.

Receptor for AGE (RAGE) is a member of the immunoglobulin superfamily that engages distinct classes of ligands. The biology of RAGE is driven by the settings in which these ligands accumulate, such as diabetes, inflammation, neurodegenerative disorders and tumors. In this review, we discuss the context of each of these classes of ligands, including advance glycation end-products, amyloid beta peptide and the family of beta sheet fibrils, S100/calgranulins and amphoterin. Implications for the role of these ligands interacting with RAGE in homeostasis and disease will be considered.

Alzheimer's disease (AD) brains are characterized by accumulation of amyloid beta protein (Abeta) and neuroinflammation. Increased blood-to-brain influx and decreased brain-to-blood efflux across the blood-brain barrier (BBB) have been proposed as mechanisms for Abeta accumulation. Epidemiological studies suggest that the nonsteroidal anti-inflammatory drug (NSAID) indomethacin slows the progression of AD. We hypothesized that inflammation alters BBB handling of Abeta. Mice treated with lipopolysaccharide (LPS) had increased brain influx and decreased brain efflux of Abeta, recapitulating the findings in AD. Neither influx nor efflux was mediated by LPS acting directly on BBB cells. Increased influx was mediated by a blood-borne factor, indomethacin-independent, blocked by the triglyceride triolein, and not related to expression of the blood-to-brain transporter of Abeta, RAGE. Serum levels of IL-6, IL-10, IL-13, and MCP-1 mirrored changes in Abeta influx. Decreased efflux was blocked by indomethacin and accompanied by decreased protein expression of the brain-to-blood transporter of Abeta, LRP-1. LPS paradoxically increased expression of neuronal LRP-1, a major source of Abeta. Thus, inflammation potentially increases brain levels of Abeta by three mechanisms: increased influx, decreased efflux, and increased neuronal production.

High mobility group box-1 (HMGB1) protein was originally characterized as a nuclear DNA-binding protein, and was described to have an extracellular role when involved in cellular activation and proinflammatory responses. In the present study, we have found that the proinflammatory activity of recombinant HMGB1 proteins is determined by the containing endotoxin level, and HMGB1 that contains few endotoxins fails to stimulate macrophages to secrete proinflammatory cytokines. HMGB1 acts as a ligand of receptor for advanced glycation end products (RAGE) and works in synergy with LPS in activating the macrophages in vitro. In vivo, intra-articular injections of HMGB1 act in synergy with LPS to induce experimental arthritis in mice. HMGB1 promotes the phosphorylation of MAPK p38 and the activation of NF-kappaB through RAGE, and then enhances the expression of proinflammatory cytokines. These results demonstrate that HMGB1 enhances the proinflammatory activity of LPS by promoting the phosphorylation of MAPK p38 and by the activation of NF-kappaB through RAGE.

Amphoterin has been suggested to regulate invasive process extension and cell migration in tumor cells and embryonic neurons through binding to receptor for advanced glycation end products (RAGE), a multiligand transmembrane receptor belonging to the immunoglobulin superfamily. In this study, we identify a COOH-terminal motif in amphoterin (amino acids 150-183) that is responsible for RAGE binding. We show that as a surface-bound ligand, this part of amphoterin is sufficient to induce RAGE-dependent process extension, suggesting a role in the regulation of cell motility. When applied in solution, the RAGE-binding COOH-terminal motif of amphoterin efficiently inhibits process extension and transendothelial migration of tumor cells. Furthermore, in an in vivo model, the corresponding synthetic peptide significantly suppresses formation of lung metastases. Taken together, these results suggest that amphoterin binds to RAGE through a COOH-terminal motif that can be used as an efficient inhibitor to block invasive migration of tumor cells.