Inappropriate chronic inflammation associated with progressive, chronic kidney disease (CKD) reflects sustained activation of immunocompetent cells, like monocytes/macrophages. Advanced glycation end products (AGE) accumulate in CKD, but it is unclear if they stimulate monocytes by binding with the receptor for AGE (RAGE). Posited was the notion that RAGE plays a contributory role to monocyte-mediated systemic inflammation of progressive CKD. Peripheral blood monocytes were isolated from 102 patients without diabetes with varying severity of CKD. RAGE expression on peripheral blood monocytes increased with worsening CKD (r2 = 0.73) and was strongly correlated with plasma levels of pentosidine, a marker for AGE (r = 0.71). Strongly positive statistical correlations were observed in patients with CKD between monocyte RAGE and plasma levels of tumor necrosis factor alpha (TNF-alpha) (r = 0.61), the monocyte activation marker, neopterin (r = 0.65), and the systemic acute phase reactant, C-reactive protein (r = 0.44). Monocytes obtained from patients with CKD showed a monotonic increase in the number and affinity of specific AGE binding sites and increased production of TNF-alpha under stimulation of AGE. All these upregulatory responses in uremic monocytes could be largely blocked by an anti-RAGE antibody. It was concluded that RAGE expression was upregulated on monocytes from patients with CKD. Enhanced RAGE may amplify AGE-induced monocytes perturbation and contribute to monocyte-mediated systemic inflammation in progressive CKD.

BACKGROUND

Advanced glycation end-products (AGEs) have been implicated in diverse pathological settings including diabetes, inflammation and acute ischemia/reperfusion injury in the heart. AGEs interact with the receptor for AGEs (RAGE) and transduce signals through activation of MAPKs and proapoptotic pathways. In the current study, adult cardiomyocytes were studied in an in vitro ischemia/reperfusion (I/R) injury model to delineate the molecular mechanisms underlying RAGE-mediated injury due to hypoxia/reoxygenation (H/R).

RESULTS

Cardiomyocytes isolated from adult wild-type (WT), homozygous RAGE-null (RKO), and WT mice treated with soluble RAGE (sRAGE) were subjected to hypoxia for 30 minutes alone or followed by reoxygenation for 1 hour. In specific experiments, RAGE ligand carboxymethyllysine (CML)-AGE (termed "CML" in this manuscript) was evaluated in vitro. LDH, a marker of cellular injury, was assayed in the supernatant in the presence or absence of signaling inhibitor-treated cardiomyocytes. Cardiomyocyte levels of heterogeneous AGEs were measured using ELISA. A pronounced increase in RAGE expression along with AGEs was observed in H/R vs. normoxia in WT cardiomyocytes. WT cardiomyocytes after H/R displayed increased LDH release compared to RKO or sRAGE-treated cardiomyocytes. Our results revealed significant increases in phospho-JNK in WT cardiomyocytes after H/R. In contrast, neither RKO nor sRAGE-treated cardiomyocytes exhibited increased phosphorylation of JNK after H/R stress. The impact of RAGE deletion on GSK-3beta phosphorylation in the cardiomyocytes subjected to H/R revealed significantly higher levels of phospho-GSK-3beta/total GSK-3beta in RKO, as well as in sRAGE-treated cardiomyocytes versus WT cardiomyocytes after H/R. Further investigation established a key role for Akt, which functions upstream of GSK-3beta, in modulating H/R injury in adult cardiomyocytes.

CONCLUSIONS

These data illustrate key roles for RAGE-ligand interaction in the pathogenesis of cardiomyocyte injury induced by hypoxia/reoxygenation and indicate that the effects of RAGE are mediated by JNK activation and dephosphorylation of GSK-3beta. The outcome in this study lends further support to the potential use of RAGE blockade as an adjunctive therapy for protection of the ischemic heart.

Many physicians and health care leaders express concern about the amount of time available for clinical practice. While debates rage on about how much time is truly available, the perception that time is inadequate is now pervasive. This perception has ethical significance, because it may cause clinicians to forego activities and behaviors that promote important aspects of the patient-physician relationship, to shortcut shared decision making, and to fall short of obligations to act as patient advocates. Furthermore, perceived time constraints can hinder the just distribution of physician time. Although creating more time in the clinical encounter would certainly address these ethical concerns, specific strategies-many of which do not take significantly more time-can effectively change the perception that time is inadequate. These approaches are critical for clinicians and health systems to maintain their ethical commitments and simultaneously deal with the realities of time.

Several epidemiological studies have reported moderately increased risks of Alzheimer's disease (AD) in diabetic patients compared with general population. In diabetes mellitus, the formation and accumulation of advanced glycation end products (AGEs) progress more rapidly. Recent understanding of this process has confirmed that interactions between AGEs and their receptor (RAGE) may play a role in the pathogenesis of diabetic complications and AD. The authors have recently found that glyceraldehyde-derived AGEs (AGE-2), which is predominantly the structure of toxic AGEs (TAGE), show significant toxicity on cortical neuronal cells and that the neurotoxic effect of diabetic serum is completely blocked by neutralizing antibody against the AGE-2 epitope. Moreover, in human AD brains, AGE-2 is distributed in the cytosol of neurons in the hippocampus and parahippocampal gyrus. These results suggest that TAGE is involved in the pathogenesis of AD as well as other age-related diseases. In this review, the authors discuss the molecular mechanisms of AD, especially focusing on TAGE-RAGE system.

Molecules differentially expressed in blood vessels among organs or between damaged and normal tissues, are attractive therapy targets; however, their identification within the human vasculature is challenging. Here we screened a peptide library in cancer patients to uncover ligand-receptors common or specific to certain vascular beds. Surveying ~2.35 x 10(6) motifs recovered from biopsies yielded a nonrandom distribution, indicating that systemic tissue targeting is feasible. High-throughput analysis by similarity search, protein arrays, and affinity chromatography revealed four native ligand-receptors, three of which were previously unrecognized. Two are shared among multiple tissues (integrin α4/annexin A4 and cathepsin B/apolipoprotein E3) and the other two have a restricted and specific distribution in normal tissue (prohibitin/annexin A2 in white adipose tissue) or cancer (RAGE/leukocyte proteinase-3 in bone metastases). These findings provide vascular molecular markers for biotechnology and medical applications.

BACKGROUND

The expression of the receptor for advanced glycation end products (RAGE) has an impact on the mechanisms giving rise to characteristic features of various cancer cells. The purpose of this study was to elucidate the clinicopathological relevance of the level of RAGE expression in patients with hepatocellular carcinoma (HCC) and to explore the effect of RAGE expression on the characteristic features of HCC.

METHODS

The expression of RAGE was assessed in paired cancer and noncancerous tissues with HCC, using reverse-transcription polymerase chain reaction (RT-PCR), and immunohistochemistry. The quantitative RT-PCR data were analyzed in association with the clinicopathological factors of the patients with HCC. In in vitro experiments, the survival of RAGE-transfected Cos7 and mock-transfected Cos7 cells was compared under hypoxic conditions. In addition, after reducing RAGE levels in RAGE-transfected Cos7 cells by siRNA, similar experiments were performed.

RESULTS

The expression of RAGE mRNA was lower in normal liver than in hepatitis and highest in HCC. Furthermore, in HCC, it was high in well- and moderately differentiated tumors but declined as tumors dedifferentiated to poorly differentiated HCC. Furthermore, HCC lines resistant to hypoxia were found to have higher levels of RAGE expression, and RAGE transfectant also showed significantly prolonged survival under hypoxia.

CONCLUSIONS

Our results suggest that HCC during the early stage of tumorigenesis with less blood supply may acquire resistance to stringent hypoxic milieu by hypoxia-induced RAGE expression.

Ebola continues to rage in West Africa. In the absence of an approved vaccine or treatment, the priority in controlling this epidemic is to promptly identify and isolate infected individuals. To this end, a rapid, highly sensitive, and easy-to-use test for Ebola diagnosis is urgently needed. Here, by using Fe3O4 magnetic nanoparticle (MNP) as a nanozyme probe, we developed a MNP-based immunochromatographic strip (Nanozyme-strip), which detects the glycoprotein of Ebola virus (EBOV) as low as 1 ng/mL, which is 100-fold more sensitive than the standard strip method. The sensitivity of the Nanozyme-strip for EBOV detection and diagnostic accuracy for New Bunyavirus clinical samples is comparable with ELISA, but is much faster (within 30 min) and simpler (without need of specialist facilities). The results demonstrate that the Nanozyme-strip test can rapidly and sensitively detect EBOV, providing a valuable simple screening tool for diagnosis of infection in Ebola-stricken areas.

Platelets play a critical role in atherogenesis and thrombosis-mediated myocardial ischemia, processes that are accelerated in diabetes. Whether hyperglycemia promotes platelet production and whether enhanced platelet production contributes to enhanced atherothrombosis remains unknown. Here we found that in response to hyperglycemia, neutrophil-derived S100 calcium-binding proteins A8/A9 (S100A8/A9) interact with the receptor for advanced glycation end products (RAGE) on hepatic Kupffer cells, resulting in increased production of IL-6, a pleiotropic cytokine that is implicated in inflammatory thrombocytosis. IL-6 acts on hepatocytes to enhance the production of thrombopoietin, which in turn interacts with its cognate receptor c-MPL on megakaryocytes and bone marrow progenitor cells to promote their expansion and proliferation, resulting in reticulated thrombocytosis. Lowering blood glucose using a sodium-glucose cotransporter 2 inhibitor (dapagliflozin), depleting neutrophils or Kupffer cells, or inhibiting S100A8/A9 binding to RAGE (using paquinimod), all reduced diabetes-induced thrombocytosis. Inhibiting S100A8/A9 also decreased atherogenesis in diabetic mice. Finally, we found that patients with type 2 diabetes have reticulated thrombocytosis that correlates with glycated hemoglobin as well as increased plasma S100A8/A9 levels. These studies provide insights into the mechanisms that regulate platelet production and may aid in the development of strategies to improve on current antiplatelet therapies and to reduce cardiovascular disease risk in diabetes.

OBJECTIVE

The receptor for advanced glycation end products (RAGE) has been proposed to participate in the innate and adaptive immune responses. RAGE can induce production of pro-inflammatory cytokines and chemokines, as well as neutrophil chemotaxis in a manner that may be suppressed or stimulated by soluble, truncated forms of RAGE including the soluble form of RAGE (sRAGE) and endogenous secretory RAGE (esRAGE). The objective of this study was to determine whether intra-amniotic infection/inflammation (IAI) is associated with changes in the amniotic fluid concentration of sRAGE and esRAGE.

METHODS

Amniotic fluid (AF) was retrieved from patients in the following groups: 1) mid-trimester (14-18 weeks of gestation; n=68); 2) term not in labor (n=24); 3) term in labor (n=51); 4) preterm labor and intact membranes (n=124); and 5) preterm PROM (n=80). Intra-amniotic infection and inflammation were defined as the presence of a positive amniotic fluid culture for microorganisms and an AF interleukin-6 concentration>>or=2.6 ng/mL, respectively. The AF concentration of sRAGE and esRAGE were determined using specific and sensitive ELISAs which measured total immunoreactive sRAGE and esRAGE, respectively. Patients were matched for gestational age at amniocentesis to compare the AF concentration of sRAGE and esRAGE in patients with and without IAI. Non-parametric statistics were used for analysis and a P<0.05 was considered significant.

RESULTS

1) Patients at term not in labor had higher median AF concentrations of sRAGE and esRAGE than those in the mid-trimester (P<0.001 for both comparisons) and those at term in labor (P=0.03 and P=0.04, respectively); 2) patients with preterm labor and intact membranes with intra-amniotic infection/inflammation (IAI) had higher median AF concentrations of sRAGE and esRAGE than those without IAI (P=0.02 and P=0.005, respectively); 3) similarly, patients with preterm PROM with IAI had higher median AF concentrations of sRAGE and esRAGE than those without IAI (P=0.03 and P=0.02, respectively).

CONCLUSIONS

Intra-amniotic infection/inflammation is associated with increased amniotic fluid concentrations of sRAGE and esRAGE. Changes in the amniotic fluid concentration of sRAGE and esRAGE may represent part of the immune response to intra-amniotic infection/inflammation.

Receptor for advanced glycation end products (RAGE) is a receptor of the immunoglobulin super family that plays various important roles under physiological and pathological conditions. Compelling evidence suggests that RAGE acts as both an inflammatory intermediary and a critical inducer of oxidative stress, underlying RAGE-induced Alzheimer-like pathophysiological changes that drive the process of Alzheimer's disease (AD). A critical role of RAGE in AD includes beta-amyloid (Aβ) production and accumulation, the formation of neurofibrillary tangles, failure of synaptic transmission, and neuronal degeneration. The steady-state level of Aβ depends on the balance between production and clearance. RAGE plays an important role in the Aβ clearance. RAGE acts as an important transporter via regulating influx of circulating Aβ into brain, whereas the efflux of brain-derived Aβ into the circulation via BBB is implemented by LRP1. RAGE could be an important contributor to Aβ generation via enhancing the activity of β- and/or γ-secretases and activating inflammatory response and oxidative stress. However, sRAGE-Aβ interactions could inhibit Aβ neurotoxicity and promote Aβ clearance from brain. Meanwhile, RAGE could be a promoting factor for the synaptic dysfunction and neuronal circuit dysfunction which are both the material structure of cognition, and the physiological and pathological basis of cognition. In addition, RAGE could be a trigger for the pathogenesis of Aβ and tau hyper-phosphorylation which both participate in the process of cognitive impairment. Preclinical and clinical studies have supported that RAGE inhibitors could be useful in the treatment of AD. Thus, an effective measure to inhibit RAGE may be a novel drug target in AD.

OBJECTIVE

To evaluate interscan reproducibility of both vessel morphology and tissue composition measurements of carotid atherosclerosis using a fast, optimized, 3T multicontrast protocol.

METHODS

A total of 20 patients with carotid stenosis >15% identified by duplex ultrasound were recruited for two independent 3T MRI (Philips) scans within one month. A multicontrast protocol including five MR sequences was applied: TOF, T1-/T2-/PD-weighted and magnetization-prepared rapid acquisition gradient-echo (MP-RAGE). Carotid artery morphology (wall volume, lumen volume, total vessel volume, normalized wall index, and mean/maximum wall thickness) and plaque component size (lipid rich/necrotic core, calcification, and hemorrhage) were measured over two time points.

RESULTS

After exclusion of images with poor image quality, 257 matched locations from 18 subjects were available for analysis. For the quantitative carotid morphology measurements, coefficient of variation (CV) ranged from 2% to 15% and intraclass correlation coefficient (ICC) ranged from 0.87 to 0.99. Except for maximum wall thickness (ICC = 0.87), all ICC were larger than 0.90. For the quantitative plaque composition measurements, the ICC of the volume and relative content of lipid rich/necrotic core and calcification were larger than 0.90 with CV ranging from 22% to 32%.

CONCLUSIONS

The results from the multicontrast high-resolution 3T MR study show high reliability for carotid morphology and plaque component measurements. 3T MRI is a reliable tool for longitudinal clinical trials, with shorter scan time compared to 1.5T.

Interaction of advanced glycation endproducts (AGE) with AGE receptors induces several cellular phenomena relating potentially to diabetic complications. Five AGE receptors identified so far are receptor for AGE (RAGE), 80 K-H, OST-48, galectin-3, and macrophage scavenger receptor, types I and II (SR-A) [Eur. J. Biochem. 230 (1995) 408; Nature 386 (1997) 292.]. Since SR-A is known to belong to the class A scavenger receptor family and the scavenger receptor collectively represents a family of multiligand lipoprotein receptors, it is possible that CD36 belonging to class B scavenger receptor family (SR-B) can recognize AGE proteins as a ligand. This was tested in the present study at the cellular level by using Chinese hamster ovary (CHO) cells overexpressing human CD36 (CHO-CD36 cells). 125I-AGE-bovine serum albumin (BSA) was endocytosed in a dose-dependent fashion and underwent lysosomal degradation by CHO-CD36, but not wild-type CHO cells. Endocytic uptake of 125I-AGE-BSA by these cells was inhibited 50% by oxidized low-density lipoprotein (Ox-LDL) and 60% by FA6-152, an anti-CD36 antibody inhibiting cellular binding of Ox-LDL. Our results indicate that CD36 expressed by these cells mediates endocytic uptake and subsequent intracellular degradation of AGE proteins. Since CD36 is one of the major Ox-LDL receptors and is up-regulated in macrophage- and smooth muscle cell-derived foam cells in human atherosclerotic lesions, the present results suggest that, like Ox-LDL, AGE proteins generated in situ are recognized by CD36, which might contribute to the pathogenesis of diabetic macrovascular complications.

OBJECTIVE

We previously showed that blockade of RAGE significantly attenuates hepatic ischemia/reperfusion (I/R) injury in mice. Here, we identify that early growth response-1 (Egr-1) is a downstream target of RAGE in hepatic I/R injury.

METHODS

Hepatic I/R was induced in male mice. Liver remnants were analyzed for induction of Egr-1 and cytokines, as well as regulation of apoptotic pathways after reperfusion.

RESULTS

Egr-1 was upregulated in the liver remnants after hepatic I/R injury and was suppressed by administration of soluble RAGE or deletion of the RAGE gene. RAGE-mediated increased expression of Egr-1 upregulates a central downstream gene, MIP2. In contrast, RAGE-stimulated Egr-1-independent pathways regulate TNF-alpha production and apoptosis in response to I/R. Consistent with these findings, phospho-p44/42 and phospho-JNK MAPK and c-Jun were strikingly suppressed in RAGE(-/-) versus WT mice, but not in Egr-1(-/-) mice. RAGE ligand HMGB1 was upregulated after I/R in the liver remnants. In vitro, incubation of RAGE-expressing liver dendritic cells (DCs) with recombinant HMGB-1 resulted in increased Egr-1 transcripts, in a manner suppressed by RAGE gene deletion, soluble RAGE and inhibitors of p44/p42 or JNK MAP kinase.

CONCLUSIONS

Suppression of Egr-1 may contribute to the protective mechanisms underlying the beneficial impact of RAGE blockade or deletion.

OBJECTIVE

To achieve consensus among researchers, pharmaceutical industry representatives, federal regulatory agency staff, and family advocates on a template for clinical trials of acute mania/bipolar disorder in children and adolescents.

METHODS

The American Academy of Child and Adolescent Psychiatry, in collaboration with Best Practice, convened a group of experts from the key stakeholder communities (including adult psychiatrists with expertise in bipolar disorder) and assigned them to workgroups to examine core methodological issues surrounding the design of clinical trials and, ultimately, to generate a consensus statement encompassing: (1) inclusion/exclusion criteria, (2) investigator training needs and site selection, (3) assessment and outcome measures, (4) protocol design and ethical issues unique to trials involving children/adolescents, and (5) regulatory agency perspectives on these deliberations.

RESULTS

Conference participants reached agreement on 18 broad methodological questions. Key points of consensus were to assign priority to placebo-controlled studies of acute manic episodes in children and adolescents aged 10-17 years, who may or may not be hospitalized, and who may or may not suffer from common comorbid psychiatric disorders; to require that specialist diagnostic "gatekeepers" screen youths' eligibility to participate in trials; to monitor interviewer and rater competency over the course of the trial using agreed upon standards; and to develop new tools for assessment, including scales to measure aggression/rage and cognitive function, while using the best available instruments (e.g., Young Mania Rating Scale) in the interim.

CONCLUSIONS

Methodologically rigorous, large-scale clinical trials of treatment of acute mania are urgently needed to provide information regarding the safety and efficacy, in youth, of diverse agents with potential mood-stabilizing properties.

Advanced glycation end products (AGEs) form non-enzymatically from reactions of proteins with reducing sugars. In the skin, AGEs were reported to accumulate in dermal elastin and collagens and to interact nonspecifically with the cell membrane of dermal fibroblasts. Therefore, AGEs may influence the process of skin aging. We investigated the presence of the AGE receptor RAGE in skin and the influence of AGEs on receptor expression and the formation of extracellular matrix (ECM). Sections of sun-protected and sun-exposed skin were analyzed with monoclonal antibodies against (RAGE), heat-shock protein 47, factor XIIIa, CD31, and CD45. RAGE was mainly expressed in fibroblasts, dendrocytes, and keratinocytes and to a minor extent in endothelial and mononuclear cells. Human foreskin fibroblasts (HFFs) highly expressed RAGE on the protein and mRNA level when analyzed by quantitative Western blotting and real-time PCR. Incubation of HFFs with the specific RAGE ligand Nepsilon-(carboxymethyl)lysine-modified BSA (CML-BSA) and tumor necrosis factor-alpha resulted in significant upregulation of RAGE expression. CML-BSA induced a mildly profibrogenic pattern, increasing connective tissue growth factor, transforming growth factor-beta (TGF-beta) 1, and procollagen-alpha1(I) mRNA, whereas expression of matrix metalloproteinase (MMP)-1, -2, -3, and -12 was unaffected. We conclude that in HFFs, AGE-RAGE interactions may influence the process of skin aging through mild stimulation of ECM gene expression.

The receptor for advanced glycation end-products (RAGE) is a member of the immunoglobin superfamily of multiligand receptors. Following ligand binding, mechanisms associated with host defense, tissue remodeling, and inflammation are activated. RAGE is highly expressed in pulmonary epithelium transitioning from alveolar type (AT) II to ATI cells and is upregulated in the presence of ligand; however, the regulation and function of RAGE during development are less clear. Herein, immunohistochemistry demonstrated a temporal-spatial pattern of RAGE expression in pulmonary epithelial cells from embryonic day 17.5 to postnatal day 10. Cotransfection experiments revealed that the mouse RAGE promoter was activated by early growth response gene 1 (Egr-1) and inhibited by thyroid transcription factor-1 (TTF-1) via interaction with specific regulatory elements. A rat ATI cell line (R3/1) with endogenous RAGE expression also differentially regulated RAGE when transfected with TTF-1 or Egr-1. Because Egr-1 is markedly induced in pulmonary epithelial cells exposed to cigarette smoke extract (CSE; Reynolds PR, Hoidal JR. Am J Respir Cell Mol Biol 35: 314-319, 2006.), we sought to investigate RAGE induction by CSE. Employing RT-PCR and Western blotting, RAGE and common ligands (amphoterin and S100A12) were upregulated in epithelial (R3/1 and A549) and macrophage (RAW) cell lines following exposure to CSE. Immunostaining for RAGE in cells similarly exposed and in lungs from mice exposed to cigarette smoke for 6 mo revealed elevated RAGE expression in pulmonary epithelium. After the addition of glyoxylated BSA, an advanced glycation end-product that binds RAGE, real-time RT-PCR detected a 200-fold increase in Egr-1. These results indicate that Egr-1 regulates RAGE expression during development and the likelihood of positive feedback involving Egr-1 and RAGE in cigarette smoke-related disease.

OBJECTIVE

The purpose of the experiment reported here was to assess the involvement of high-mobility group box-1 (HMGB1), receptor for advanced glycation end products (RAGE) and nuclear factor (NF)-κB signaling pathway in the development of rat diabetic nephropathy.

METHODS

Diabetes was induced by intraperitoneal streptozotocin injection in 7-week-old male rats. At 20 weeks of age, renal expression of HMGB1 was detected by immunohistochemistry. The expression of RAGE and NF-κB activity was studied by Western blot and electrophoretic mobility shift assay in renal tissues of normoglycemic and diabetic rats, respectively.

RESULTS

HMGB1 was highly expressed in both the cytoplasmic and nuclear patterns in diabetic renal glomerular cells and tubular epithelial cells, although in normal rats, HMGB1 was expressed only in the cell nuclei. The expression of RAGE, a potential receptor for HMGB1, and NF-κB activity were also greater in diabetic than in normal rats. Moreover, diabetes increased the binding of NF-κB to the RAGE promoter.

CONCLUSIONS

These findings suggest that hyperglycemia-induced HMGB1 release may induce the renal injury in diabetic rats, and that the pathogenic role of HMGB1 might be dependent on RAGE and through activation of NF-κB.

Thiamine, known as vitamin B(1), plays an essential role in energy metabolism. Benfotiamine (S-benzoylthiamine O-monophoshate) is a synthetic S-acyl derivative of thiamine. Once absorbed, benfotiamine is dephosphorylated by ecto-alkaline phosphatase to lipid-soluble S-benzoylthiamine. Transketolase is an enzyme that directs the precursors of advanced glycation end products (AGEs) to pentose phosphate pathway. Benfotiamine administration increases the levels of intracellular thiamine diphosphate, a cofactor necessary for the activation transketolase, resulting in the reduction of tissue level of AGEs. The elevated level of AGEs has been implicated in the induction and progression of diabetes-associated complications. Chronic hyperglycemia accelerates the reaction between glucose and proteins leading to the formation of AGEs, which form irreversible cross-links with many macromolecules such as collagen. In diabetes, AGEs accumulate in tissues at an accelerated rate. Experimental studies have elucidated that binding of AGEs to their specific receptors (RAGE) activates mainly monocytes and endothelial cells and consequently induces various inflammatory events. Moreover, AGEs exaggerate the status of oxidative stress in diabetes that may additionally contribute to functional changes in vascular tone control observed in diabetes. The anti-AGE property of benfotiamine certainly makes it effective for the treatment of diabetic neuropathy, nephropathy and retinopathy. Interestingly, few recent studies demonstrated additional non-AGE-dependent pharmacological actions of benfotiamine. The present review critically analyzed the multifaceted therapeutic potential of benfotiamine.

The receptor for advanced glycation end products (RAGE) is associated with cancer progression in several human cancers. In this study, we examined the roles of RAGE in the angiogenesis of oral squamous cell carcinoma (OSCC). RAGE concentration was examined in 20 OSCC tumors by enzyme-linked immunosorbent assay (ELISA). The microvessel density (MVD) and lymph vessel density (LVD) were examined by immunostaining. Concentrations of vascular endothelial growth factor (VEGF) and VEGF-C were examined in tumor tissues by ELISA. Tumoral RAGE concentration was associated with higher tumor MVD (P = 0.0123) and tumor VEGF concentration (P = 0.0344), but not with LVD and VEGF-C concentration. Treatment with RAGE ligand, high-mobility group box (HMGB)-1 increased the secretion of VEGF but not that of VEGF-C in human OSCC cell lines, HSC-3 and HSC-4. The effect of HMGB-1 was abrogated by RAGE down-regulation by antisense S-oligodeoxynucleic acid. These results suggest that RAGE expression is closely associated to angiogenesis in OSCC.

We previously demonstrated up-regulation of the receptor for advanced glycation end-products (RAGE) and its ligands by cigarette smoke extract (CSE) in rat R3/1 cells, a type I-like alveolar epithelial cell line. However, RAGE-mediated intracellular signaling pathways that lead to pulmonary inflammation remained unclear. Using ELISAs, we demonstrate that alveolar epithelial cell lines exposed to 25% CSE for 2 hours induce the activation of Ras, a small GTPase that functions as a molecular switch in the control of several intracellular signaling networks. Conversely, cells treated with siRNA for RAGE (siRAGE) resulted in decreased Ras activation. Furthermore, Ras was significantly diminished in lungs from RAGE null mice exposed to chronic tobacco smoke when compared with smoke-exposed wild-type mice. The use of a luciferase reporter containing NF-κB binding sites also demonstrated elevated NF-κB activation in R3/1 cells after CSE stimulation and decreased NF-κB activation in cells transfected with siRAGE before CSE exposure. ELISA revealed an increase in the secretion of IL-1β and CCL5 by R3/1 cells, two cytokines induced by NF-κB and associated with leukocyte chemotaxis. Furthermore, real-time RT-PCR and ELISAs revealed decreased cytokine secretion in RAGE null mouse lung exposed to tobacco smoke compared with lungs from smoke-exposed wild-type animals. These results support the conclusion that CSE-induced RAGE expression functions in pathways that involve Ras-mediated NF-κB activation and cytokine elaboration. This RAGE-Ras-NF-κB axis likely contributes to inflammation associated with several smoking-related inflammatory lung diseases.

Melanoma inhibitory activity (MIA) is an 11-kDa secretory protein isolated from malignant melanoma cells that is correlated with invasion and metastasis in various human malignancies. We examined MIA expression in 62 oral squamous cell carcinomas (OSCC) by immunohistochemistry. MIA expression was significantly associated with nodal metastasis (P = 0.00018). MIA expression was also associated with expression of high mobility group box-1 (HMGB1) (P < 0.0001) and lymph vessel density (P < 0.0001). Expression levels of MIA, HMGB1, nuclear factor kB (NFkB) p65 and HMGB1-NFkB p65 binding were significantly higher in a metastatic human OSCC cell line (HSC3) than those in a non-metastatic OSCC cell line (HSC4). Treatment with receptor for advanced glycation end products (RAGE) antisense or small interfering RNA and human recombinant HMGB1 (hrHMGB1) did not affect MIA expression, whereas HMGB1 antisense or siRNA treatment decreased MIA expression in HSC3 cells. Then HMGB1 enhanced MIA expression as an NFkB cofactor but not as a RAGE ligand. MIA neutralization by MIA antibodies increased extracellular signal-related kinase 1/2 phosphorylation, but decreased p38 phosphorylation and the expression of vascular epithelial growth factor (VEGF)-C and -D. Treatment with p38 inihibitor decreased VEGF-C and -D expression in HSC3 cells. These results suggest that MIA expression is enhanced by the interaction of intracellular HMGB1 and NFkBp65 and MIA is closely involved in tumor progression and nodal metastasis by the increments of VEGF-C and VEGF-D in OSCC.

The aim of the present study was to investigate whether dietary advanced glycation end-products (AGEs) can be detected in the ovarian tissue of normal female rats and whether they can affect their metabolic or hormonal profile. Sixty normal rats (20 animals in each group) were randomly assigned to regular diet, either high (H-AGE) or low (L-AGE) in AGE content for 6 months. H-AGE rats demonstrated higher levels of fasting glucose (P < 0.001), insulin (P < 0.069), and serum AGEs (P < 0.001) than control and L-AGE rats. Additionally, the H-AGE group showed increased AGE localization in the theca interna cells of the ovarian tissue compared to control/L-AGE rats (P = 0.003). Furthermore, increased receptor for AGE (RAGE) staining was also observed in granulosa cells compared to control/L-AGE samples (P = 0.038). In the H-AGE group, plasma testosterone was higher than in control rats (P < 0.001) and in the L-AGE group (P < 0.001). However, H-AGE rats did not exhibit higher body weight compared with normal (P = 0.118) and L-AGE-fed rats (P = 0.35). These results demonstrate for the first time that administration of high AGE diet in female rats for a prolonged period is associated with increased deposition of AGEs in the theca cells and of RAGE in the granulosa and theca interna cells of the ovarian tissue compared with the corresponding ovarian compartments of the control and L-AGE-fed animals. The metabolic alterations in conjuction with the increased deposition in ovarian tissues of dietary glycotoxins and elevated levels of testosterone in H-AGE-fed animals compared to the controls suggest an impact of environmental factors on ovarian tissue and these findings need further exploration.

Vildagliptin is a stable inhibitor of dipeptidyl peptidase-IV, a responsible enzyme that mainly inactivates glucagon-like peptide-1, and now one of the widely used agents for the treatment of diabetes. However, effects of vildagliptin on vascular injury in diabetes are largely unknown. Since advanced glycation end products (AGEs) and their receptor RAGE axis are reported to contribute to vascular complications in diabetes, we investigated here whether vildagliptin inhibits vascular damage in thoracic aorta of Otsuka Long-Evans Tokushima Fatty rats (OLETF rats), an animal model of type 2 diabetes with obesity, by blocking the AGEs-RAGE axis. OLETF and control LETO rats at 22 weeks old were given vehicle or 3 mg/kg of vildagliptin for another 12 weeks. Vildagliptin treatment decreased fasting plasma glucose and heart rate in OLETF rats. Compared with control LETO rats, levels of AGEs, RAGE mRNA and protein, an oxidative stress marker, 8-hydroxydeoxyguanosine, two membrane components of NADPH oxidase, p22 and gp91phox mRNAs, and phospho-NF-κB p65 in thoracic aorta were significantly enhanced in OLETF rats, all of which were inhibited by the treatment with vildagliptin. Vildagliptin significantly reduced both mRNA and protein levels of monocyte chemoattractant protein-1, vascular cell adhesion molecule-1 and plasminogen activator inhibitor-1 in thoracic aorta of OLETF rats. Enhanced expression of transforming growth factor-β in the aorta of diabetic rats was also suppressed by vildagliptin. Our present data suggest that vildagliptin could play a protective role against vascular injury in diabetes partly by attenuating the deleterious effects of AGEs-RAGE-oxidative stress axis.

1. There is suggestive evidence that the septo-hippocampal system and the amygdala are involved in risk assessment behavior, a response to potential threat possibly related to anxiety. In addition, experimental results have been reported implicating the medial hypothalamus in coordinated escape, while the periaqueductal gray matter (PAG) and the median raphe nucleus serotonergic projection to the hippocampus seem to mediate freezing. The latter defensive behaviors are evoked by distal danger stimuli and may be viewed as manifestations of fear. Finally, there is a sound body of evidence indicating that the PAG commands primitive fight or flight reactions elicited by proximal threat, acute pain or asphyxia. These defense reactions may be related to rage and panic, respectively. In contrast, the lateral septal area and the bed nucleus of the stria terminalis have been shown to exert tonic inhibitory influence on defense. 2. Experimental evidence indicates that gamma-aminobutyric acid (GABA) tonically inhibits defensive behavior in the amygdala, hypothalamus and the PAG, an effect opposed by excitatory amino acids. Among monoamines, serotonin (5-HT) has been suggested to facilitate anxiety in the amygdala while inhibiting panic in the PAG. The role of noradrenaline in defense is less clear, although hypotheses implicating the locus coeruleus in anxiety and panic have been suggested. Among peptides, corticotropin-releasing factor (CRF) acting as a central neurotransmitter is thought to mediate behavioral and physiological effects of acute stress, while opioid peptides have been shown to inhibit defense in the amygdala and in the dorsal PAG. Finally, acetylcholine seems to facilitate defensive behavior in the hypothalamus and the PAG.