糖基化终产物对人单核细胞源树突状细胞糖基化终产物受体表达的研究

目的：探讨糖基化终产物 (AGEs）)对人单核细胞源树突状细胞（MDCs）糖基化终产物受体（RAGE） 表达的影响。 方法： 用免疫磁珠分离人外周血CD14+单核细胞，经含rhGM-CSF（100 μg/L）和rhIL-4（50 μg/L）的RPMI-1640培养，使其分化为MDCs，采用RT-PCR和Western blotting法，观察糖基化-白蛋白（AGE-BSA）对MDCs RAGE mRNA和蛋白表达的影响，同时检测培养液上清中IFN-γ和IL-12的浓度。 结果： AGE-BSA诱导DCs RAGE mRNA和蛋白的表达（P＜0.05），高于空白对照组，并且明显促进了DCs IFN-γ和IL-12的分泌（P＜0.05）。BSA干预组与空白对照组相比差异无显著（P＞0.05）。 结论： AGEs能够上调DCs RAGE的表达，并且促进了DCs IFN-γ和IL-12的分泌，这可能是糖尿病通过DCs促进动脉粥样硬化发生的重要机制之一。     

Understanding RAGE, the receptor for advanced glycation end products

Advanced glycation end products (AGEs), S100/calgranulins, HMGB1-proteins, amyloid- peptides, and the family of -sheet fibrils have been shown to contribute to a number of chronic diseases such as diabetes, amyloidoses, inflammatory conditions, and tumors by promoting cellular dysfunction via binding to cellular surface receptors. The receptor for AGEs (RAGE) is a multiligand receptor of the immunoglobulin superfamily of cell surface molecules acting as counter-receptor for these diverse molecules. Engagement of RAGE converts a brief pulse of cellular activation to sustained cellular dysfunction and tissue destruction. The involvement of RAGE in pathophysiologic processes has been demonstrated in murine models of chronic disease using either a receptor decoy such as soluble RAGE (sRAGE), RAGE neutralizing antibodies, or a dominant-negative form of the receptor. Studies with RAGE^–/– mice confirmed that RAGE contributes, at least in part, to the development of late diabetic complications, such as neuropathy and nephropathy, macrovascular disease, and chronic inflammation. Furthermore, deletion of RAGE provided protection from the lethal effects of septic shock caused by cecal ligation and puncture (CLP). In contrast, deletion of RAGE had no effect on the host response in delayed-type hypersensitivity (DTH). Despite the lack of effect seen in adaptive immunity by the deletion of RAGE, administration of the receptor decoy, sRAGE, still afforded a protective effect in RAGE^–/– mice. Thus, sRAGE is likely to sequester ligands, thereby preventing their interaction with other receptors in addition to RAGE. These data suggest that, just as RAGE is a multiligand receptor, its ligands are also likely to recognize several receptors in mediating their biologic effects.     

Activation of the receptor for advanced glycation end products (RAGE) exacerbates experimental autoimmune myasthenia gravis symptoms

RAGE belongs to immunoglobulin superfamily and serves as a ligand for various immunoregulatory molecules including S100B that has been demonstrated important to T cell mediated autoimmune diseases. In this context, we hypothesized that RAGE could also impact B cell mediated, T cell-dependent autoimmune diseases. This was tested using myasthenia gravis (MG) animal model, EAMG. We show that expression of both RAGE and S100B are increased during EAMG and the interaction between RAGE and S100B affected the Th1/Th2/Th17/Treg cell equilibrium, up-regulate AChR-specific T cell proliferation. Furthermore, addition of S100B in vitro stimulated splenocyte activity linked to COX-2 up-regulation. NS-398, a selective COX-2 inhibitor, effectively diminished S100B mediated activity of AChR-specific antibody secreting splenocytes. These findings suggested that a reciprocal relationship between RAGE and S100B promoted the development of EAMG, highlighting the importance of understanding the mechanisms of EAMG disease as a means of developing new therapies for the treatment of MG.     

Expression of a novel secreted splice variant of the receptor for advanced glycation end products (RAGE) in human brain astrocytes and peripheral blood mononuclear cells

The engagement of the receptor for advanced glycation end products (RAGE) on the cell surface induces cellular dysfunction in a number of pathophysiological situations of vascular dysfunction, tumor cell invasion, inflammatory response, and T cell infiltration. The administration of truncated, soluble RAGE can modulate RAGE-mediated perturbations. Here, we report a novel splice variant (delta8-RAGE) of RAGE mRNA, which lacks exon 8 of the genomic RAGE gene and contains an early stop codon in exon 10 due to a frame shift mutation. delta8-RAGE mRNA was found in human primary astrocytes and peripheral blood mononuclear cells (PBMCs). Transient transfection experiments demonstrated that delta8-RAGE mRNA was translated into a secretory protein as deduced. Moreover, two different segments of the spliced variant were identified in PBMCs by RT-PCR. The findings of this study suggest that the diverse splicing variants of RAGE are possible in many tissues and their products may influence the RAGE-mediated pathogenesis and immune modulation.     

糖基化终产物通过其受体诱导人肾小球系膜细胞表达CTGF和FN

目的： 探讨体外培养条件下糖基化终产物（AGEs）对人肾小球系膜细胞(HRMCs）中结缔组织生长因子（CTGF）及纤维连接蛋白（FN）基因表达的影响及其可能的作用机制。方法: 将HRMCs与不同浓度的糖化牛血清白蛋白（AGE-BSA）和牛血清白蛋白（BSA）共同培养,或与同一质量浓度的AGE-BSA和BSA共同培养不同时间,以中和性抗RAGE抗体封闭细胞膜上糖基化终末产物受体（RAGE）;采用免疫印迹法（Western blotting）观察AGEs对HRMCs中RAGE表达的影响,半定量逆转录-聚合酶链反应（RT-PCR）法检测CTGF、FN mRNA的表达。结果: 在HRMCs中存在少量RAGE的表达,AGE-BSA能够诱导HRMCs中RAGE的表达增加,并以时间和剂量依赖方式促进HRMCs中CTGF和FN的表达上调;CTGF、FN的表达水平在加入不同浓度（50、100、200、400 mg/L）的AGE-BSA 作用48 h后以及加入质量浓度为200 mg/L的 AGE-BSA 作用不同时间（12、24、48、72h）后,较相应质量浓度或时间的BSA组和空白对照组均明显升高（P＜0.05）;抗RAGE抗体干预后能够部分抑制AGE-BSA诱导CTGF及FN的表达,而人IgG没有这种作用。结论: AGEs可能通过RAGE诱导CTGF及FN的表达上调,是糖尿病肾病肾脏纤维化的可能机制。     

Polymorphisms of the promoter and exon 3 of the receptor for advanced glycation end products (RAGE) in Euro- and Afro-Brazilians

The receptor for advanced glycation end products (RAGE or AGER), a member of the immunoglobulin superfamily, is involved in pathologies such as atherosclerosis and diabetes. Over 50 SNPs were reported for RAGE, among which were the promoter region polymorphisms -429T>C (rs1800625), -374T>A (rs1800624) and a 63-bp deletion (-407 to -345 bp), all related to increased RAGE expression. Additionally, in the exon 3, a putative site of binding ligands, the missense variation G82S (rs2070600) was associated with skin disorders in patients with diabetes. We have determined allele, genotype and haplotype frequencies of RAGE polymorphisms -429T>C, -374T>A, 63-bp deletion and G82S in Euro-Brazilians (n = 108) and Afro-Brazilians (n = 91), characterized according to the predominant ancestry of the individuals. The allele frequencies for Euro- and Afro-Brazilians were as follows: -429C, 12.5% vs. 12.1% (P = 0.90); -374A, 31.5% vs. 26.2% (P = 0.25); 63del, 0.0% vs. 3.8% (P = 0.004); and 82S, 1.9% vs. 0.6% (P = 0.24). Absolute linkage disequilibrium was found between the promoter polymorphisms -429T>C and -374T>A plus the 63-bp deletion (D'=1.000; P < 0.0001). The haplotype frequencies differed (P = 0.003) between Euro- and Afro-Brazilians. Our results showed that the frequencies of the 63-bp deletion were higher in Afro-Brazilians, while the other analysed polymorphisms were similarly distributed in the studied populations. The -374T>A plus 63-bp deletion polymorphism captures more than 80% of the haplotypic variation in the studied population.     

Receptor for advanced glycation end products (RAGE) is important in the prediction of recurrence in human oral squamous cell carcinoma

AIMS: Receptor for advanced glycation end products (RAGE) has recently been recognized as a cancer-associated protein responsible for cancer progression and metastasis in gastrointestinal cancers. The aim was to examine the role of RAGE in oral squamous cell carcinoma (OSCC). METHODS AND RESULTS: RAGE expression was examined by immunohistochemistry in 74 OSCC patients and evaluated with a grading based on Allred's score. RAGE expression was compared with clinicopathological parameters including clinical stage, invasive depth, nodal metastasis, disease recurrence and disease-free survival. High-grade expression of RAGE (RAGE-H) was observed in 30 (40.5%) of 74 OSCCs. RAGE-H was associated with depth of invasion (P < 0.0001) and local recurrence (P < 0.0001), but not with histological differentiation, clinical stage or nodal metastasis. Disease-free survival in patients with RAGE-H was significantly worse than in those with low-level RAGE expression. Multivariate analysis showed RAGE-H to be an independent prognostic factor for disease-free survival in OSCC patients (P = 0.0022). CONCLUSION: RAGE is a relevant factor in predicting disease recurrence and patients' prognosis in OSCC.     

Implication of receptor for advanced glycation end product (RAGE) in pulmonary health and pathophysiology

Receptor for advanced glycation end products (RAGE) is a membrane bound receptor and member of the immunoglobulin super family and is normally present in a highly abundant basal level expression in lung. This high expression of RAGE in lung alveolar epithelial type I (ATI) cells is presumably involved in the proliferation and differentiation of pulmonary epithelial cells. However, typically higher than basal level expression of RAGE may indicate the existence of severe pathophysiological condition in lung, e.g. acute lung injury (ALI) and acute respiratory distress syndrome (ARDS). During pulmonary tissue injury an endogenous secretory isoform of RAGE called EsRAGE is noticed at high levels in broncho-alveolar lavage (BAL) and plasma. Recently, a soluble form of RAGE (sRAGE) produced by recombinant gene technology was shown to exhibit a therapeutic potential in experimental animal models. Detailed study of RAGE in the pulmonary tissues will facilitate the understanding of the importance of RAGE signaling in the pulmonary health and pathophysiology.     

Possible participation of receptor for advanced glycation end products (RAGE) in the origin of cancer stem cells in diabetic patients with colon cancer

The association between diabetes and the associated increased risk of several solid malignancies has been the subject of investigation for many years, while potential biologic links between the two diseases are incompletely understood. The receptor for advanced glycation end-products (RAGE) signal transduction may represent a focal point in their respective contributions to malignant transformation associated diabetes. While the physiopathology of RAGE axis in promoting malignancies cannot be explained completely by the available mechanism as perpetuating inflammation at tumor microenvironment. In addition, experimental researches revealed a crucial role for upstreams of RAGE signaling pathway in maintaining the stemness properties and tumorigenicity of cancer stem cells. Hence, we hypothesized that RAGE inducing cancer stem cells may be a key determinant in the origin and progression of colon malignant tumors concomitant diabetes. Such an opinion not only bands together the seemingly disparate various complications in diabetes and colon cancers, but also has future implications for risk assessment and biopharmaceutical treatment.     

糖基化终产物与糖尿病血管并发症关系的研究进展

糖尿病是临床上一种常见病和多发病 ,血管并发症是糖尿病的主要致残及致死原因。流行病学调查资料表明 ,糖尿病患者发生动脉粥样硬化及危及生命的心血管并发症的危险性较常人增加 3- 4倍 ,而高血糖状态下蛋白质发生的非酶糖基化对糖尿病血管并发症起了重要作用。大量的资料已证明 ,糖尿病患者体内存在着一种重要的毒性产物———糖基化终产物 (ａｄｖａｎｃｅｄｇｌｙｃｏｓｙｌａｔｉｏｎｅｎｄｐｒｏｄ ｕｃｔｓ,ＡＧＥｓ)。本文对有关ＡＧＥｓ在糖尿病血管病变中致病作用的研究进展综述如下 :一、ＡＧＥｓ的生物化学特性及结构早在 1 91 …     

Receptor for advanced glycation end products (RAGE) gene polymorphism and cardiovascular disease in end-stage renal disease patients

Background/objectivesReceptor for advanced glycation end products (RAGE) contributes to the pathogenesis of vascular and inflammatory diseases. We investigated whether the functional polymorphism in the promoter region of the RAGE gene (−374 T/A) influences development of cardiovascular disease in the end-stage renal disease (ESRD) patients.MethodsThe cohorts of 1866 ESRD patients and 1143 healthy subjects were genotyped by polymerase chain reaction (PCR) for the RAGE variant rs1800624.ResultsThe genotype and allele frequencies did not differ significantly between ESRD patients and controls. There was no significant difference in the genotype distribution when patients with CVD were compared to those without it (p for A allele = 0.62). After stratifying CVD patients according to CVD clinical phenotype, the ESRD patients with stroke had a lower frequency of A allele than patients without CVD (0.12 vs. 0.21, p = 0.027). To confirm this finding, we genotyped 163 patients with ischemic stroke but without renal disease. In this group, the AA/TA genotypes were also significantly associated with lower risk of stroke (OR 0.46, p = 0.0002).ConclusionOur data suggest that the presence of the A allele of −374 T/A polymorphism in the RAGE gene has a protective effect against stroke.     

Characterization of antibodies to advanced glycosylation end products on protein

Antibodies directed against advanced glycosylation end products (AGEs) formed during a Maillard reaction have been generated and characterized. Since protein-bound AGEs recognized by the antibodies were labile to acid hydrolysis, the antibodies were further characterized by using the AGE-alpha-acetyl-L-lysine methyl ester (AGE-ALME) with a brown and fluorescent property as well as the AGE-proteins. The antibodies reacted with fluorescent compounds, rather than brown pigment compounds, in the AGE-ALME. The fluorescent compounds in the AGE-ALME were separated into four fluorescent compounds by reversed-phase thin layer chromatography (TLC). Of the fluorescent compounds tested, compound 3 (Rf = 0.63), as designated on a TLC plate, showed the highest affinity for the antibodies. In addition, the antibody recognition to the cross-linked oligomers with fluorescence in the AGE-protein was investigated by using bovine pancreatic ribonuclease A (RNase), which is known as a model protein for studying AGE-induced cross-linking. Fluorescence in the AGE-RNase existed in both of the oligomers and the monomer. The cross-linked oligomers exhibited higher affinity to the antibodies than did the monomer, which has a similar degree of fluorescent intensity. These results indicate that our antibodies against cross-linked protein-bound AGEs may serve as a useful tool to elucidate pathophysiological roles of advanced Maillard reaction in diabetic complications and aging processes.     

Targeting receptors of advanced glycation end products (RAGE): Preventing diabetes induced cancer and diabetic complications

Cancer and diabetes are the two major disorders that affect a large proportion of the world’s population. Results from multiple epidemiological studies have concluded that diabetes and cancer are linked, and diabetic patients live at much higher risks of developing cancer and diabetic complications at the later phase of disease. Inflammation is the central pathway that mediates both diabetic complications as well as cancer. Receptor of advanced glycation end products (RAGE) is a non-specific multi-ligand pattern recognition receptor that induces the inflammatory responses by binding with multiple ligands. RAGE and its ligands are upregulated in diabetes, inflammation and cancer. Advanced glycation end products (AGEs), high mobility group box protein-1 (HMGB1) and S100 proteins are the major RAGE ligands that contribute to these consequences and an increased release of RAGE ligands during diabetic conditions can be a possible mechanism leading to diabetic complications and cancer. Moreover, further release of RAGE ligands from cancer cells can be a possible mechanism behind the worsening of diabetic complications in diabetic cancer patients. Inhibition of RAGE signaling can prevent diabetic complications and cancer in diabetic patients and can be helpful in the management of worsening diabetic complications and cancer in diabetic cancer patients. Curcumin, Quercetin and Withaferin A are known to inhibit multiple molecular pathways that are involved in RAGE signaling. The combined effects of these molecules can be explored to achieve the complete inhibition of RAGE signaling in diabetic patients.     

晚期糖基化终产物对人脂肪间充质干细胞功能影响的体外研究*

 目的：探讨晚期糖基化终产物（AGEs）对人脂肪来源的间充质干细胞（hADSCs）促进创伤修复功能的影响。方法：体外培养hADSCs,实验分为牛血清白蛋白（BSA）对照组、低浓度糖基化修饰的牛血清白蛋白（AGE-BSA）效应组和高浓度AGE-BSA效应组。采用WST法和Transwell迁移实验检测各组细胞增殖和迁移情况。应用实时定量PCR和ELISA检测各组细胞分泌血管内皮生长因子（VEGF）、肝细胞生长因子（HGF）和胰岛素样生长因子1（IGF-1）的表达。结果：与对照组相比, AGE-BSA组增殖能力和迁移能力明显下降（P<0.05）,VEGF、HGF和IGF-1 mRNA及蛋白表达水平显著降低（P<0.05）。结论：AGEs能损伤hADSCs的促进创伤修复功能,因而能够影响hADSCs治疗糖尿病皮肤溃疡病的治疗效果。     

Expression profiling of endogenous secretory receptor for advanced glycation end products in human organs.

The receptor for advanced glycation end products (RAGE) is a cell surface multiligand receptor of the immunoglobulin superfamily, which participates in physiological and pathological processes such as neuronal development, diabetes, inflammation, neurodegenerative disorders, and cancer. A novel splice variant of RAGE-endogenous secretory decoy form (esRAGE) was recently identified and is thought to be a prospective candidate to modify these RAGE-associated conditions. Here, we investigated the expression and distribution of esRAGE and RAGE proteins with domain-specific antibodies. We studied a wide variety of adult normal human preparations obtained from surgical and autopsy specimens using a tissue microarray technique. The results revealed that esRAGE was widely distributed and we classified its expression into four patterns. In pattern A, the cytoplasm is stained diffusely in neurons, vascular endothelium, pneumocytes, mesothelium, pancreatic beta cells, and macrophages/monocytes. In pattern B, dot-like granules are stained in the supranuclear regions facing the luminal surface of the bile ducts, salivary glands, digestive tracts, renal tubules, prostate, skin, thyroid, and bronchioles. Pattern C is represented by diffuse staining in the stromal area of the arterial walls. Pattern D shows diffuse and strong staining of secreted materials such as thyroidal colloid, crystals in renal tubular lumen, and glandular lumen in prostate. This study provides, for the first time, a histopathological basis for understanding the physiological roles of esRAGE in humans, and will contribute to elucidating the participation of esRAGE in pathological processes and to exploring novel diagnostic and therapeutic concepts.     

Advanced glycation end products (AGEs) and their receptor (RAGE) induce apoptosis of periodontal ligament fibroblasts

Diabetics have an increased prevalence of periodontitis, and diabetes is one of thecausative factors of severe periodontitis. Apoptosis is thought to be involved inthis pathogenic relationship. The aim of this study was to investigate apoptosis inhuman periodontal ligament (PDL) fibroblasts induced by advanced glycation endproducts (AGEs) and their receptor (RAGE). We examined the roles of apoptosis, AGEs,and RAGE during periodontitis in diabetes mellitus using cultured PDL fibroblaststhat were treated by AGE-modified bovine serum albumin (AGE-BSA), bovine serumalbumin (BSA) alone, or given no treatment (control). Microscopy and real-timequantitative PCR indicated that PDL fibroblasts treated with AGE-BSA were deformedand expressed higher levels of RAGE and caspase 3. Cell viability assays and flowcytometry indicated that AGE-BSA reduced cell viability (69.80±5.50%, P<0.01) andincreased apoptosis (11.31±1.73%, P<0.05). Hoechst 33258 staining andterminal-deoxynucleotidyl transferase-mediated nick-end labeling revealed thatAGE-BSA significantly increased apoptosis of PDL fibroblasts. The results showed thatthe changes in PDL fibroblasts induced by AGE-BSA may explain how AGE-RAGEparticipates in and exacerbates periodontium destruction.     

Immunohistochemical distribution of advanced glycation end products (AGEs) in human osteoarthritic cartilage

Advanced glycation end products (AGEs) may be associated with osteoarthritis (OA), because the accumulation of AGEs in articular cartilage are among the most striking age-related changes. AGEs modify the tissue protein structure and function and stimulate the cellular responses mediated by a specific receptor for AGEs (RAGE). This study investigated the localization of AGEs in degenerated cartilage using newly identified epitope-specific antibodies to determine the linkage between the distribution of AGEs and the development and progression of OA. Osteochondral specimens of the tibial plateau from OA patients were immunostained by specific antibodies against N^?-(carboxymethyl)lysine (CML), N^?-(carboxyethyl)lysine (CEL), pentosidine, GA-pyridine, and RAGE. The immunohistochemical distribution of these epitopes was evaluated during cartilage degeneration. The immunoreactivity (IR) of AGEs and RAGE was stronger in cells rather than in the extracellular matrix. Higher IR of cellular CML and CEL was observed in both mild and severe OA cartilage in comparison to macroscopically intact cartilage. There was a strong association between GA-pyridine and RAGE in the pattern of increasing IR with the OA grade. These IR patterns of AGEs varying with cartilage degeneration indicate that AGE modified proteins are associated with cartilage degeneration. The coincidental up-regulation of GA-pyridine and RAGE suggests that GA-pyridine is the most significant AGE for cartilage degeneration via the RAGE pathway.