Advanced glycation end products in gastric cancer:A promising future

In this editorial,we delve into the article and offer valuable insights into a crucial aspect of gastric cancer aetiology.Gastric cancer is a malignancy emanating from the epithelial lining of the gastric mucosa and one of the most prevalent forms of cancer worldwide.The development of gastric cancer is associated with multiple risk factors,including Helicobacter pylori infection,advanced age,a diet rich in salt,and suboptimal eating patterns.Despite notable reductions in morbidity and mortality rates,gastric cancer remains a formidable public health concern,impacting patients’lives.Advanced glycation end products(AGEs)are complex compounds arising from nonenzymatic reactions within living organisms,the accumulation of which is implicated in cellular and tissue damage;thus,the levels are AGEs are correlated with the risk of diverse diseases.The investigation of AGEs is of paramount importance for the treatment of gastric cancer and can provide pivotal insights into disease pathogenesis and preventive and therapeutic strategies.The reduction of AGEs levels and suppression of their accumulation are promising avenues for mitigating the risk of gastric cancer.This approach underscores the need for further research aimed at identifying innovative interventions that can effectively lower the incidence and mortality rates of this malignancy.

Nε-(carboxymethyl)lysine promotes lipid uptake of macrophage via cluster of differentiation 36 and receptor for advanced glycation end products

BACKGROUND Advanced glycation end products(AGEs)are diabetic metabolic toxic products that cannot be ignored.Nε-(carboxymethyl)lysine(CML),a component of AGEs,could increase macrophage lipid uptake,promote foam cell formation,and thereby accelerate atherosclerosis.The receptor for AGEs(RAGE)and cluster of differentiation 36(CD36)were the receptors of CML.However,it is still unknown whether RAGE and CD36 play key roles in CML-promoted lipid uptake.AIM Our study aimed to explore the role of RAGE and CD36 in CML-induced macrophage lipid uptake.METHODS In this study,we examined the effect of CML on lipid uptake by Raw264.7 macrophages.After adding 10 mmol/L CML,the lipid accumulation in macrophages was confirmed by oil red O staining.Expression changes of CD36 and RAGE were detected with immunoblotting and quantitative real-time polymerase chain reaction.The interaction between CML with CD36 and RAGE was verified by immunoprecipitation.We synthesized a novel N-succinimidyl-4-18Ffluorobenzoate-CML radioactive probe.Radioactive receptor-ligand binding assays were performed to test the binding affinity between CML with CD36 and RAGE.The effects of blocking CD36 or RAGE on CML-promoting lipid uptake were also detected.RESULTS The study revealed that CML significantly promoted lipid uptake by macrophages.Immunoprecipitation and radioactive receptor-ligand binding assays indicated that CML could specifically bind to both CD36 and RAGE.CML had a higher affinity for CD36 than RAGE.ARG82,ASN71,and THR70 were the potential interacting amino acids that CD36 binds to CML Anti-CD36 and anti-RAGE could block the uptake of CML by macrophages.The lipid uptake promotion effect of CML was significantly attenuated after blocking CD36 or RAGE.CONCLUSION Our results suggest that the binding of CML with CD36 and RAGE promotes macrophage lipid uptake.

Implications of receptor for advanced glycation end products for progression from obesity to diabetes and from diabetes to cancer

Obesity and type 2 diabetes mellitus(T2DM)are chronic pathologies with a high incidence worldwide.They share some pathological mechanisms,including hyperinsulinemia,the production and release of hormones,and hyperglycemia.The above,over time,affects other systems of the human body by causing tissue hypoxia,low-grade inflammation,and oxidative stress,which lay the pathophysiological groundwork for cancer.The leading causes of death globally are T2DM and cancer.Other main alterations of this pathological triad include the accumulation of advanced glycation end products and the release of endogenous alarmins due to cell death(i.e.,damage-associated molecular patterns)such as the intracellular proteins high-mobility group box protein 1 and protein S100 that bind to the receptor for advanced glycation products(RAGE)-a multiligand receptor involved in inflammatory and metabolic and neoplastic processes.This review analyzes the latest advanced reports on the role of RAGE in the development of obesity,T2DM,and cancer,with an aim to understand the intracellular signaling mechanisms linked with cancer initiation.This review also explores inflammation,oxidative stress,hypoxia,cellular senescence,RAGE ligands,tumor microenvironment changes,and the“cancer hallmarks”of the leading tumors associated with T2DM.The assimilation of this information could aid in the development of diagnostic and therapeutic approaches to lower the morbidity and mortality associated with these diseases.

Advanced glycation end products:Key mediator and therapeutic target of cardiovascular complications in diabetes

The incidence of type 2 diabetes mellitus is growing in epidemic proportions and has become one of the most critical public health concerns.Cardiovascular complications associated with diabetes are the leading cause of morbidity and mortality.The cardiovascular diseases that accompany diabetes include angina,myocardial infarction,stroke,peripheral artery disease,and congestive heart failure.Among the various risk factors generated secondary to hyperglycemic situations,advanced glycation end products(AGEs)are one of the important targets for future diagnosis and prevention of diabetes.In the last decade,AGEs have drawn a lot of attention due to their involvement in diabetic pathophysiology.AGEs can be derived exogenously and endogenously through various pathways.These are a nonhomogeneous,chemically diverse group of compounds formed nonenzymatically by condensation between carbonyl groups of reducing sugars and free amino groups of protein,lipids,and nucleic acid.AGEs mediate their pathological effects at the cellular and extracellular levels by multiple pathways.At the cellular level,they activate signaling cascades via the receptor for AGEs and initiate a complex series of intracellular signaling resulting in reactive oxygen species generation,inflammation,cellular proliferation,and fibrosis that may possibly exacerbate the damaging effects on cardiac functions in diabetics.AGEs also cause covalent modifications and cross-linking of serum and extracellular matrix proteins;altering their structure,stability,and functions.Early diagnosis of diabetes may prevent its progression to complications and decrease its associated comorbidities.In the present review,we recapitulate the role of AGEs as a crucial mediator of hyperglycemia-mediated detrimental effects in diabetes-associated complications.Furthermore,this review presents an overview of future perspectives for new therapeutic interventions to ameliorate cardiovascular complications in diabetes.

Advanced glycation end product signaling and metabolic complications:Dietary approach

Advanced glycation end products(AGEs)are a heterogeneous collection of compounds formed during industrial processing and home cooking through a sequence of nonenzymatic glycation reactions.The modern western diet is full of heat-treated foods that contribute to AGE intake.Foods high in AGEs in the contemporary diet include processed cereal products.Due to industrialization and marketing strategies,restaurant meals are modified rather than being traditionally or conventionally cooked.Fried,grilled,baked,and boiled foods have the greatest AGE levels.Higher AGE-content foods include dry nuts,roasted walnuts,sunflower seeds,fried chicken,bacon,and beef.Animal proteins and processed plant foods contain furosine,acrylamide,heterocyclic amines,and 5-hydroxymethylfurfural.Furosine(2-furoil-methyl-lysine)is an amino acid found in cooked meat products and other processed foods.High concentrations of carboxymethyl-lysine,carboxyethyl-lysine,and methylglyoxal-O are found in heat-treated nonvegetarian foods,peanut butter,and cereal items.Increased plasma levels of AGEs,which are harmful chemicals that lead to age-related diseases and physiological aging,diabetes,and autoimmune/inflammatory rheumatic diseases such as systemic lupus erythematosus and rheumatoid arthritis.AGEs in the pathophysiology of metabolic diseases have been linked to individuals with diabetes mellitus who have peripheral nerves with high amounts of AGEs and diabetes has been linked to increased myelin glycation.Insulin resistance and hyperglycemia can impact numerous human tissues and organs,leading to long-term difficulties in a number of systems and organs,including the cardiovascular system.Plasma AGE levels are linked to all-cause mortality in individuals with diabetes who have fatal or nonfatal coronary artery disease,such as ventricular dysfunction.High levels of tissue AGEs are independently associated with cardiac systolic dysfunction in diabetic patients with heart failure compared with diabetic patients without heart failure.It is widely recognized that AGEs and oxidative stress play a key role in the cardiovascular complications of diabetes because they both influence and are impacted by oxidative stress.All chronic illnesses involve protein,lipid,or nucleic acid modifications including crosslinked and nondegradable aggregates known as AGEs.Endogenous AGE formation or dietary AGE uptake can result in additional protein modifications and stimulation of several inflammatory signaling pathways.Many of these systems,however,require additional explanation because they are not entirely obvious.This review summarizes the current evidence regarding dietary sources of AGEs and metabolism-related complications associated with AGEs.

Role of the receptor for advanced glycation end products in hepatic fibrosis

AIM： To study the role of advanced glycation end products （AGE） and their specific receptor （RAGE） in the pathogenesis of liver fibrogenesis. METHODS： In vitro RAGE expression and extracellular matrix-related gene expression in both rat and human hepatic stellate cells （HSC） were measured after stimulation with the two RAGE ligands, advanced glycation end product-bovine serum albumin （AGE- BSA） and N＇-（carboxymethyl） lysine （CML）-BSA, or with tumor necrosis factor-α （TNF-α）. In vivo RAGE expression was examined in models of hepatic fibrosis induced by bile duct ligation or thioacetamide. The effects of AGE-BSA and CML-BSA on HSC proliferation, signal transduction and profibrogenic gene expression were studied in vitro. RESULTS： In hepatic fibrosis, RAGE expression was enhanced in activated HSC, and also in endothelial cells, inflammatory cells and activated bile duct epithelia. HSC expressed RAGE which was upregulated after stimulation with AGE-BSA, CML-BSA, and TNF-α.RAGE stimulation with AGE-BSA and CML-BSA did not alter HSC proliferation, apoptosis, fibrogenic signal transduction and fibrosis- or fibrolysis-related gene expression, except for marginal upregulation of procollagen α1（ I ） mRNA by AGE-BSA. CONCLUSION： Despite upregulation of RAGE in activated HSC, RAGE stimulation by AGE does not alter their fibrogenic activation. Therefore, RAGE does not contribute directly to hepatic fibrogenesis.

Role of the advanced glycation end products receptor in Crohn's disease inflammation

AIM:To investigate the level of mucosal expression and the involvement of the receptor for the advanced glycation end products(RAGE)in delayed apoptosis and tumor necrosis factor(TNF)-αproduction in Crohn’s disease(CD).METHODS:Surgical and endoscopic specimens from both inflamed and non-inflamed areas of the ileum and/or colon were collected from 20 and 14 adult CD patients,respectively,and used for the assessment of RAGE expression by means of immunohistochemistry and western blotting analysis.Normal tissues from 21 control subjects were used for comparison.The same polyclonal anti-human RAGE antibody(R and D System)was used in all experimental conditions.RAGE staining was quantized by a score including both the amount of positive cells and intensity of immunoreactivity;cellular pattern was also described.The effects of RAGE blocking on apoptotic rate and TNF-αproduction were investigated on immune cells freshly isolated from CD mucosa and incubated both with and without the muramyl dipeptide used as antigenic stimulus.Statistical analysis was performed via the test for trend,with regression models to account for intra-patient correlations.A 2-sided P<0.05 was considered significant.RESULTS:In inflamed areas,RAGE expression in both the epithelial and lamina propria compartments was higher than control tissues(P=0.001 and 0.021,respectively),and a cluster of positive cells were usually found in proximity of ulcerative lesions.Similar results were obtained in the lamina propria compartment of non-inflamed areas(P=0.025).The pattern of staining was membranous and granular cytosolic at the epithelial level,while in the lamina propria it was diffuse cytosolic.When evaluating the amount of protein expression by immunoblotting,a significant increase of both surface area and band intensity(P<0.0001 for both)was observed in CD inflamed areas compared to control tissue,while in non-inflamed areas a significant increase was found only for band intensity(P<0.005).Moreover,a significantly lower expression in noninflamed areas in comparison with inflamed areas was found for both surface area and band intensity(P<0.0006 for both).Finally,RAGE blocking largely affects both the apoptotic rate of mucosal cells(towards an increase in both non-inflamed and inflamed areas of P<0.001 and<0.0001,respectively)and TNF-αsecretion(towards a decrease in both non-inflamed and inflamed areas of P<0.05 and<0.01,respectively),mainly in the presence of antigenic stimulation.CONCLUSION:RAGE is up-regulated in CD,especially in inflamed areas,and it appears to play a role in the mechanisms involved in chronic inflammation.

Association of vascular endothelial growth factor-634G/C and receptor for advanced glycation end products G82S gene polymorphisms with diabetic retinopathy

AIMTo investigate the association of receptor for advanced glycation end products (RAGE) G82S and vascular endothelial growth factor (VEGF) -634 G/C gene polymorphisms with diabetic retinopathy (DR).METHODSOur cross-sectional study included 61 diabetic patients, 12 of them had proliferative diabetic retinopathy (PDR), 15 had non proliferative diabetic retinopathy (NPDR), 34 had no diabetic retinopathy (NDR) and 61 healthy controls. Participants were tested for RAGE G82S and VEGF -634 G/C polymorphisms by polymerase chain reaction-restriction fragment length polymorphism.RESULTSWe found a significant association between VEGF -634 G/C polymorphism and PDR as PDR patients had increased incidence of VEGF -634 CC genotype compared to NDR patients [odds ratio for CC vs (GC+GG)=6.5, 95% CI=1.5-27.8, P=0.021]. Also VEGF -634 CC genotype and C allele were significantly higher in the PDR than in NPDR patients, which is a novel finding in our study (P=0.024, 0.009 respectively). The mean triglycerides level was significantly higher in diabetic patients with CC genotype (P=0.01) as compared to patients with other genotypes. All cases and control subjects were of the same heterozygous RAGE 82G/S genotype.CONCLUSIONPatients carrying VEGF -634 C polymorphism have a higher risk of PDR development, so VEGF -634 G/C polymorphism could be used as a predictive marker for PDR in diabetic patients. We could not find a significant association between RAGE G82S polymorphism and DR.

Correlation between soluble receptor for advanced glycation end products levels and coronary artery disease in postmenopausal nondiabetic women

BACKGROUND The established cardiovascular risk factors cannot explain the overall risk of coronary artery disease(CAD),especially in women.Therefore,there is a growing need for the assessment of novel biomarkers to identify women at risk.The receptor for advanced glycation end products(RAGE)and its interaction with the advanced glycation end product(AGE)ligand have been associated with atherogenesis.The soluble fraction of RAGE(sRAGE)antagonizes RAGE signaling and exerts an antiatherogenic effect.AIM The study aim was to explore the association between plasma levels of sRAGE and CAD in nondiabetic postmenopausal women.METHODS This case-control study included 110 nondiabetic postmenopausal women who were enrolled in two groups.Group I included 55 angiographically proven CAD subjects with>50%stenosis in at least one of the major coronary arteries and Group II included 55 healthy control women who did not have CAD or had<50%stenosis of the coronary arteries.Stenosis was confirmed by invasive angiography.Plasma sRAGE was determined by an enzyme-linked immunosorbent assay.RESULTS We observed significantly lower plasma sRAGE concentrations in subjects with CAD vs healthy controls(P<0.05).Univariate and multivariate logistic regression analysis also revealed a significant correlation between plasma sRAGE levels and CAD(P=0.01).Multivariate odds ratios for CAD revealed that subjects with sRAGE concentrations below 225 pg/mL(lowest quartile)had a 6-fold increase in CAD prevalence independent of other risk factors.CONCLUSION Our findings indicated that low sRAGE levels were independently associated with CAD in nondiabetic postmenopausal women.Risk assessment of CAD in postmenopausal women can be improved by including sRAGE along with other risk factors.

Novel Inhibitory Effects of Glycyrrhizic Acid on the Accumulation of Advanced Glycation End Product and Its Receptor Expression

Beneficial effects of glycyrrhizic acid(GA),a bioactive extract of licorice root,in the prevention of metabolic syndrome have been consistently reported while advanced glycation end products(AGE)and receptor for advanced glycation end product(RAGE)are the leading factors in the development of diabetes mellitus.The aim of this study was to investigate the effects of GA on the AGE-RAGE axis using high-fat/high-sucrose(HF/HS)diet-induced metabolic syndrome rat models.Twenty four male Sprague–Dawley rats were randomly assigned into three groups for 4 weeks:(1)Group A,normal diet with standard rat chow;(2)Group B,HF/HS diet;(3)Group C,HF/HS diet and oral administration of 100 mg/kg GA per day.The results showed that HF/HS diet elevated the fasting blood glucose level and insulin resistance index which was prevented by GA supplementation.GA treatment significantly lowered the circulating AGE independent of its glucose-lowering effect.HF/HS diet also triggered RAGE upregulation in the abdominal muscles while GA administration downregulated RAGE expression in the abdominal muscles,aorta and subcutaneous adipose tissues.In conclusion,HF/HS diet could cause glucose intolerance,insulin resistance and upregulation of RAGE expression while GA ameliorated the metabolic dysregulation besides exhibiting inhibitory effects on the AGE-RAGE axis.

Increased expression of receptor for advanced glycation end-products worsens focal brain ischemia in diabetic rats

A rat model of diabetes mellitus was induced by a high fat diet, followed by focal brain ischemia induced using the thread method after 0.5 month. Immunohistochemistry showed that expression of receptor for advanced glycation end-products was higher in the ischemic cortex of diabetic rats compared with non-diabetic rats with brain ischemia. Western blot assay revealed increased phosphorylated c-Jun N-terminal kinase expression, and unchanged phosphorylated extracellular signal-regulated protein kinase protein expression in the ischemic cortex of diabetic rats compared with non-diabetic rats with brain ischemia. Additionally, phosphorylated p38 mitogen-activated protein kinase protein was not detected in any rats in the two groups. Severity of limb hemiplegia was worse in diabetic rats with brain ischemia compared with ischemia alone rats. The results suggest that increased expression of receptor for advanced glycation end-products can further activate the c-Jun N-terminal kinase pathway in mitogen-activated protein kinase, thereby worsening brain injury associated with focal brain ischemia in diabetic rats.

Advanced glycation end-product expression is upregulated in the gastrointestinal tract of type 2 diabetic rats

AIM:To investigate changes in advanced glycation end products(AGEs) and their receptor(RAGE) expression in the gastrointestinal(GI) tract in type 2 diabetic rats.METHODS:Eight inherited type 2 diabetic rats GotoKakizak(GK) and ten age-matched normal rats were used in the study.From 18 wk of age,the body weight and blood glucose were measured every week and 2 wk respectively.When the rats reached 32 wk,twocentimeter segments of esophagus,duodenum,jejunum,ileum,and colon were excised and the wet weight was measured.The segments were fixed in 10% formalin,embedded in paraffin and five micron sections were cut.The layer thickness was measured in Hematoxylin and Eosin-stained slides.AGE [N epsilon-(carboxymethyl) lysine and N epsilon-(carboxyethyl)lysine] and RAGE were detected by immunohistochemistry staining and image analysis was done using Sigmascan Pro 4.0 image analysis software.RESULTS:The blood glucose concentration(mmol/L) at 18 wk age was highest in the GK group(8.88 ± 1.87 vs 6.90 ± 0.43,P < 0.001),a difference that continued to exist until the end of the experiment.The wet weight per unit length(mg/cm) increased in esophagus,jejunum and colon from the normal to the GK group(60.64 ± 9.96 vs 68.56 ± 11.69,P < 0.05 for esophagus; 87.01 ± 9.35 vs 105.29 ± 15.45,P < 0.01 for jejunum; 91.37 ± 7.25 vs 97.28 ± 10.90,P < 0.05 for colon).Histologically,the layer thickness of the GItract was higher for esophagus,jejunum and colon in the GK group [full thickness(μm):575.37 ± 69.22 vs 753.20 ± 150.41,P < 0.01 for esophagus; 813.51 ± 44.44 vs 884.81 ± 45.31,P < 0.05 for jejunum; 467.12 ± 65.92 vs 572.26 ± 93.60,P < 0.05 for colon].In esophagus,the AGE and RAGE mainly distributed in striated muscle cells and squamous epithelial cells.The AGE distribution was much stronger in the GK group compared to the normal group both in the striated muscle layer and mucosa layer(immuno-positive area/ total measuring area %:4.52 ± 0.89 vs 10.96 ± 1.34,P < 0.01 for muscle; 8.90 ± 2.62 vs 22.45 ± 1.26,P < 0.01 for mucosa).No visible difference was found for RAGE distribution between the two groups.In the intestine AGE and RAGE distributed in epithelial cells of villi and crypt.RAGE was also found in neurons in the myenteric and submucosal plexus.The intensity of AGE staining in mucosa of all segments and RAGE staining in neurons in all segments were strongest in the diabetes group.Significant difference for AGE was found in the epithelial cells of villi and crypt in duodenum(immunopositive area/total measuring area %:13.37 ± 3.51 vs 37.48 ± 8.43,P < 0.05 for villi; 0.38 ± 0.12 vs 1.87 ± 0.53,P < 0.05 for crypt) and for RAGE in neurons of all segments(e.g.,for jejunum:no staining neurons% 0 vs 0,mild 36.0 ± 5.2 vs 28.7 ± 3.5,moderate 53.2 ± 4.8 vs 55.8 ± 5.4,strong 10.7 ± 1.1 vs 15.4 ± 2.0,P < 0.05).In the colon,RAGE was primarily found in neurons in the myenteric and submucosal plexus.It was stronger in the diabetes group than in the normal group(no staining neurons% 6.2 ± 0.2 vs 0.3 ± 0.04,mild 14.9 ± 2.1 vs 17.6 ± 1.5,moderate 53.1 ± 4.6 vs 44.7 ± 4.4,strong 25.6 ± 18 vs 43.6 ± 4.0,P < 0.05).In the rectum,RAGE was primarily found in the mucosa epithelial cells.CONCLUSION:The AGE and RAGE expression was upregulated in the GI tract of GK diabetic rats and may contribute to GI dysfunction in type 2 diabetic patients.

Injury of cortical neurons is caused by the advanced glycation end products-mediated pathway

Advanced glycation end products lead to cell apoptosis, and cause cell death by increasing endoplasmic reticulum stress. Advanced glycation end products alone may also directly cause damage to tissues and cells, but the precise mechanism remains unknown. This study used primary cultures of rat cerebral cortex neurons, and treated cells with different concentrations of glycation end products （50, 100, 200, 400 mg/L）, and with an antibody for the receptor of advanced glycation end products before and after treatment with advanced glycation end products. The results showed that with increasing concentrations of glycation end products, free radical content increased in neurons, and the number of apoptotic cells increased in a dose-dependent manner. Before and after treatment of advanced glycation end products, the addition of the antibody against advanced glycation end-products markedly reduced hydroxyl free radicals, malondialdehyde levels, and inhibited cell apoptosis. This result indicated that the antibody for receptor of advanced glycation end-products in neurons from the rat cerebral cortex can reduce glycation end product-induced oxidative stress damage by suppressing glycation end product receptors. Overall, our study confirms that the advanced glycation end products-advanced glycation end products receptor pathway may be the main signaling pathway leading to neuronal damage.

The role of advanced glycation end products and their mechanism in DN

Advanced glycation end products(AGEs), which are macromolecular material such as proteins, lipids, and nucleic acids free amino and reducing sugar on the reaction of aldehyde group under the condition of the enzyme, generate the stable compounds. AGEs formation is enhanced in diabetes and is associated with the development of diabetic complications. AGEs, as an important marker of chronic complications of diabetes mellitus, plays an important role in the development and progression of diabetic nephropathy. In the current review, we discuss mechanisms and the role of AGEs in diabetic nephropathy.

六味地黄丸介导RAGE抑制MMP-2/MMP-9对Aβ_(1-40)损伤bEnd.3细胞紧密连接蛋白的影响

目的探讨六味地黄丸对β淀粉样蛋白1-40(Aβ_(1-40))损伤的小鼠脑微血管内皮细胞(bEnd.3)的保护作用及其机制。方法采用CCK8法检测Aβ_(1-40)和六味地黄丸含药血清(MSLDP)对细胞活性的影响,筛选合适的作用浓度。将bEnd.3细胞分为对照组、Aβ_(1-40)组、MSLDP+Aβ_(1-40)组和MSLDP组,采用Western blot检测低密度脂蛋白相关蛋白1(LRP1)、晚期糖基化终末产物受体(RAGE)、基质金属蛋白酶2(MMP-2)、MMP-9、闭锁小带蛋白-1(ZO-1)、脑源性神经营养因子(BDNF)蛋白表达,免疫荧光检测LRP1、RAGE、ZO-1表达;再将bEnd.3细胞分为对照组、Aβ_(1-40)组、FPS-ZM1(RAGE抑制剂)+Aβ_(1-40)组和FPS-ZM1+Aβ_(1-40)+MSLDP组,Western blot检测RAGE、MMP-9、MMP-2、ZO-1蛋白表达。结果Aβ_(1-40)呈剂量依赖性降低bEnd.3细胞活性(P<0.01),MSLDP对Aβ_(1-40)损伤的细胞活性具有保护作用(P<0.05,P<0.01),因此选择10μmol/L Aβ_(1-40)和10%MSLDP进行后续实验。与对照组比较,Aβ_(1-40)组RAGE、MMP-2、MMP-9蛋白表达升高(P<0.01),LRP1、ZO-1、BDNF蛋白表达降低(P<0.05,P<0.01),并且LRP1、ZO-1荧光强度降低(P<0.01),RAGE荧光增强(P<0.01);与Aβ_(1-40)组比较,MSLDP组RAGE、MMP-2、MMP-9蛋白表达和RAGE荧光强度降低(P<0.05,P<0.01),而LRP1、ZO-1、BDNF蛋白表达和LRP1、ZO-1荧光强度升高(P<0.05,P<0.01)。与Aβ_(1-40)组比较,Aβ_(1-40)+FPS-ZM1组MMP-2、MMP9、RAGE蛋白表达降低(P<0.05,P<0.01),ZO-1蛋白表达升高(P<0.05);Aβ_(1-40)+FPS-ZM1+MSLDP组MMP-2、MMP9、RAGE蛋白表达降低(P<0.01),ZO-1蛋白表达升高(P<0.01),FPS-ZM1和MSLDP联合使用的效果更佳。结论六味地黄丸能够保护Aβ_(1-40)损伤的脑微血管内皮的细胞紧密连接,减轻血脑屏障障碍,保护神经血管单元防治阿尔茨海默病,可能通过调节RAGE途径抑制MMP-2/MMP-9途径实现。

High glucose reduces Nrf2-dependent cRAGE release and enhances inflammasome-dependent IL-1βproduction in monocytes:the modulatory effects of EGCG

Soluble receptor for advanced glycation end products(sRAGE)acts as a decoy sequestering of RAGE ligands,thus preventing the activation of the ligand-RAGE axis linking human diseases.However,the molecular mechanisms underlying sRAGE remain unclear.In this study,THP-1 monocytes were cultured in normal glucose(NG,5.5 mmol/L)and high glucose(HG,15 mmol/L)to investigate the effects of diabetesrelevant glucose concentrations on sRAGE and interleukin-1β(IL-1β)secretion.The modulatory effects of epigallocatechin gallate(EGCG)in response to HG challenge were also evaluated.HG enhanced intracellular reactive oxygen species(ROS)generation and RAGE expression.The secretion of sRAGE,including esRAGE and cRAGE,was reduced under HG conditions,together with the downregulation of a disintegrin and metallopeptidase 10(ADAM10)and nuclear factor erythroid 2-related factor 2(Nrf2)nuclear translocation.Mechanistically,the HG effects were counteracted by siRAGE and exacerbated by siNrf2.Chromatin immunoprecipitation results showed that Nrf2 binding to the ADAM10 promoter and HG interfered with this binding.Our data reinforce the notion that RAGE and Nrf2 might be sRAGE-regulating factors.Under HG conditions,the treatment of EGCG reduced ROS generation and RAGE activation.EGCG-stimulated cRAGE release was likely caused by the upregulation of the Nrf2-ADAM10 pathway.EGCG inhibited HG-mediated NLRP3 inflammasome activation at least partly by stimulating sRAGE,thereby reducing IL-1βrelease.

Intra-coronary administration of soluble receptor for advanced glycation end-products attenuates cardiac remodeling with decreased myocardial transforming growth factor-pl expression and fibrosis in minipigs with ischemia-reperfusion injury

Background The cardioprotective effects of soluble receptor for advanced glycation end-products （sRAGE） have not been evaluated in large animals and the underlying mechanisms are not fully understood. This study aimed to evaluate the effects of intra-coronary administration of sRAGE on left ventricular function and myocardial remodeling in a porcine model of ischemia-reperfusion （I/R） injury. Methods Ten male minipigs with I/R injury were randomly allocated to receive intra-coronary administration of sRAGE （sRAGE group, n=5） or saline （control group, n=5）. Echocardiography was performed before and 2 months after infarction. Myocardial expression of transforming growth factor （TGF）-β1 was determined by immunohistochemistry and fibrosis was evaluated by Sirius red staining. Results As compared with the baseline values in the control animals, left ventricular end-diastolic volume （from （19.5±5.1） to （32.3±5.6） ml, P 〈0.05） and end-systolic volume （from （8.3±3.2） to （15.2±4.1） ml, P 〈0.05） were significantly increased, whereas ejection fraction was decreased （from （61.6±13.3）% to （50.2±11.9）%, P 〈0.05）. No obvious change in these parameters was observed in the sRAGE group. Myocardial expression of TGF-β1 was significantly elevated in the infarct and non-infarct regions in the control group, as compared with sRAGE group （both P 〈0.01）. Fibrotic lesions were consistently more prominent in the infarct region of the myocardium in the control animals （P〈0.05）. Conclusion Intra-coronary sRAGE administration attenuates RAGE-mediated myocardial fibrosis and I/R injury through a TGF-β1-dependent mechanism, suggesting a clinical potential in treating RAGE/ligand-associated cardiovascular diseases.

Intrafollicular Soluble RAGE Benefits Embryo Development and Predicts Clinical Pregnancy in Infertile Patients of Advanced Maternal Age Undergoing In Vitro Fertilization

Soluble receptor for advanced glycation end products（s RAGE） can decoy the toxic AGEs and is considered to be a protective factor.This study aimed to evaluate the correlation between intrafollicular s RAGE levels and clinical outcomes in infertile women of young or advanced maternal age（AMA） undergoing in vitro fertilization（IVF）.A total of 62 young women and 62 AMA women who would undergo IVF were included in this prospective study.The intrafollicular s RAGE concentration was measured to determine its association with the number of retrieved oocytes,fertilized oocytes,high-quality embryos or achievement of clinical pregnancy in young and AMA women,respectively.Besides,correlations between sR AGE and age or follicle-stimulating hormone（FSH） were examined.We found that the intrafollicular s RAGE levels were higher in young patients than those in AMA patients,suggesting that the s RAGE levels were inversely correlated with age.In young patients,sR AGE showed no correlation with the number of retrieved oocytes,fertilized oocytes,high-quality embryos or achievement of clinical pregnancy.But it was found that AMA patients with more retrieved oocytes,fertilized oocytes and high-quality embryos demonstrated higher sR AGE levels,which were a prognostic factor for getting clinical pregnancy independent of age or FSH level.In conclusion,the s RAGE levels decrease with age.Elevated intrafollicular s RAGE levels indicate good follicular growth,fertilization and embryonic development,and successful clinical pregnancy in AMA women,while in young women,the role of s RAGE may not be so predominant.

氧化苦参碱对脑梗死后血-脑脊液屏障保护作用的研究

目的 探讨缺血性脑卒中(CI)损伤后RAGE/NF-κB通路的动态变化及氧化苦参碱保护CI后血-脑脊液屏障(BCFB)通透性增加的具体机制。方法 应用线栓法制备大脑中动脉闭塞模型,并将大鼠随机分为4组:假手术组、缺血组和干预组分别为氧化苦参碱(OMT) 60 mg·kg^(-1),OMT120mg·kg^(-1)。在脑缺血24 h时应用干湿重法测定脑水肿、伊文思蓝渗出评估BCFB的完整性,并从组织学、蛋白和mRNA水平检测IS脑组织中晚期糖基化终末产物受体(RAGE)、核因子-κB (NF-κB)、肿瘤坏死因子α (TNF-α)及基质金属蛋白酶-9 (MMP-9)的变化;以及OMT干预对其表达的影响。结果 OMT 120mg·kg-1组可明显降低脑含水量,减少伊文思蓝的渗出;高剂量OMT可降低RAGE、TNF-α、MMP-9的表达,并抑制NF-κB核转位。结论 OMT能够抑制IS后炎症反应,保护BCFB完整性,其作用可能通过RAGE/NF-κB信号通路介导。

晚期糖基化终末产物受体在波动性高糖致人冠状动脉内皮细胞凋亡中的作用

目的研究持续性高糖(CHG)和波动性高糖(IHG)环境下,人冠状动脉内皮细胞(HCAECs)的细胞凋亡情况,并探索HCAECs细胞凋亡是否由晚期糖基化终末产物受体(RAGE)介导发生。方法取对数生长期的HCAECs分为4组:①正常血糖组(CNG组,5 mmol/L葡萄糖);②持续性高糖组(CHG组,20 mmol/L葡萄糖);③波动性高糖组(IHG组,5 mmol/L和20 mmol/L葡萄糖每8 h波动1次);④波动性甘露醇对照组(IM组,5 mmol/L和20 mmol/L甘露醇每8小时波动1次,保持与波动性高糖相同的波动性渗透压环境)。不同条件处理后的HCAECs,采用噻唑蓝(MTT)法测定细胞活力,流式细胞术检测HCAECs细胞凋亡情况,Westernblot检测Caspase-3、RAGE的蛋白表达水平变化,qRT-PCR检测RAGE的转录水平变化情况。用靶向RAGE的shRNA慢病毒敲低HCAECs中RAGE的表达量,观察IHG中Caspase-3的活化表达情况。结果与CNG组相比,CHG组和IHG组细胞活力均降低(P<0.05),但IHG组细胞活力更低(P=0.035);IHG组细胞凋亡率增加(P=0.028),Caspase-3活化状态(P=0.037)和RAGE表达量显著增加(P<0.05)。用靶向RAGE的shRNA慢病毒敲低RAGE表达水平,发现波动性高糖导致的细胞凋亡情况得到明显改善(P<0.05)。结论波动性高糖可通过增强RAGE表达,促进细胞凋亡,引起HCAECs损伤。