Comprehensive analysis of advanced glycation end-products in commonly consumed foods:presenting a database for dietary AGEs and associated exposure assessment

Advanced glycation end-products(AGEs)are a group of heterogeneous compounds formed in heatprocessed foods and are proven to be detrimental to human health.Currently,there is no comprehensive database for AGEs in foods that covers the entire range of food categories,which limits the accurate risk assessment of dietary AGEs in human diseases.In this study,we first established an isotope dilution UHPLCQq Q-MS/MS-based method for simultaneous quantification of 10 major AGEs in foods.The contents of these AGEs were detected in 334 foods covering all main groups consumed in Western and Chinese populations.Nε-Carboxymethyllysine,methylglyoxal-derived hydroimidazolone isomers,and glyoxal-derived hydroimidazolone-1 are predominant AGEs found in most foodstuffs.Total amounts of AGEs were high in processed nuts,bakery products,and certain types of cereals and meats(>150 mg/kg),while low in dairy products,vegetables,fruits,and beverages(<40 mg/kg).Assessment of estimated daily intake implied that the contribution of food groups to daily AGE intake varied a lot under different eating patterns,and selection of high-AGE foods leads to up to a 2.7-fold higher intake of AGEs through daily meals.The presented AGE database allows accurate assessment of dietary exposure to these glycotoxins to explore their physiological impacts on human health.

Advanced glycation end-products change placental barrier function and tight junction in rats with gestational diabetes mellitus via the receptor for advanced glycation end products/nuclear factor-κB pathway

The placenta plays an important role in nutrient transport to maintain the growth and development of the embryo.Gestational diabetes mellitus(GDM),the most common complication during pregnancy,highly affects placental function in late gestation.Advanced glycation end-products(AGEs),a complex and heterogeneous group of compounds engaged by the receptor for AGEs(RAGE),are closely associated with diabetes-related complications.In this study,AGEs induced a decrease in the expression of tight junction(TJ)proteins in BeWo cells and increased the paracellular permeability of trophoblast cells by regulating RAGE/NF-κB.Sprague-Dawley(SD)rats injected with 100 mg/kg AGEs-rat serum albumin(RSA)via the tail vein from embryo day 2 were set as the placental barrier dysfunction model group(n=10).The effect of AGEs on placental permeability was determined using the Evans-Blue dye extravasation method.The ultrastructure of the placenta samples was observed by transmission electron microscopy.The effects of AGEs on the placenta were confirmed by treating rats with RAGE antagonist FPS-ZM1 and soluble forms of RAGE(sRAGE).AGEs treatment increased placental permeability and disrupted the tight junctions in pregnant rat placenta,but has no effect on blood glucose.The expression of TJ-related proteins,including ZO-1,Occludin,and Claudin 5,were downregulated after AGEs treatment.Further,AGEs treatment increased the expression of RAGE and nuclear factor-κB in the placenta of rats and upregulated the levels of vascular endothelial growth factor.The effects of AGEs on the placenta were blocked by RAGE antagonist FPS-ZM1 and sRAGE.This study demonstrates the mechanism underlying AGEs-induced disturbance in placental function in pregnant rats and highlights the potential of AGEs in the treatment of GDM.

Receptor for advanced glycation end-products axis and coronavirus disease 2019 in inflammatory bowel diseases:A dangerous liaison?

Compelling evidence supports the crucial role of the receptor for advanced glycation end-products(RAGE)axis activation in many clinical entities.Since the beginning of the coronavirus disease 2019 pandemic,there is an increasing concern about the risk and handling of severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)infection in inflammatory gastrointestinal disorders,such as inflammatory bowel diseases(IBD).However,clinical data raised during pandemic suggests that IBD patients do not have an increased risk of contracting SARS-CoV-2 infection or develop a more severe course of infection.In the present review,we intend to highlight how two potentially important contributors to the inflammatory response to SARS-CoV-2 infection in IBD patients,the RAGE axis activation as well as the cross-talk with the renin-angiotensin system,are dampened by the high expression of soluble forms of both RAGE and the angiotensin-converting enzyme(ACE)2.The soluble form of RAGE functions as a decoy for its ligands,and soluble ACE2 seems to be an additionally attenuating contributor to RAGE axis activation,particularly by avoiding the transactivation of the RAGE axis that can be produced by the virus-mediated imbalance of the ACE/angiotensin II/angiotensin II receptor type 1 pathway.

Receptor of advanced glycation end-products axis and gallbladder cancer:A forgotten connection that we should reconsider

Compelling evidence derived from clinical and experimental research has demonstrated the crucial contribution of chronic inflammation in the development of neoplasms,including gallbladder cancer.In this regard,data derived from clinical and experimental studies have demonstrated that the receptor of advanced glycation end-products(RAGE)/AGEs axis plays an important role in the onset of a crucial and long-lasting inflammatory milieu,thus supporting tumor growth and development.AGEs are formed in biological systems or foods,and food-derived AGEs,also known as dietary AGEs are known to contribute to the systemic pool of AGEs.Once they bind to RAGE,the activation of multiple and crucial signaling pathways are triggered,thus favoring the secretion of several proinflammatory cytokines also involved in the promotion of gallbladder cancer invasion and migration.In the present review,we aimed to highlight the relevance of the association between high dietary AGEs intakes and high risk for gallbladder cancer,and emerging data supporting that dietary intervention to reduce gallbladder cancer risk is a very attractive approach that deserves much more research efforts.

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.

Fluorescent advanced glycation end-products (ages) detected by spectro-photofluorimetry, as a screening tool to detect diabetic microvascular complications

BACKGROUND: Advanced glycation end-products (AGEs) are one of the mechanisms related to diabetic vascular complications. However, since AGEs are multiple and heterogeneous moieties, there is no universally accepted method to measure them for clinical purposes. The aim of this work was to study the utility of a simple fluorimetric assay as predictor of complications. METHODS: Blood samples from 102 type 2 diabetic patients were obtained to assess glucose, glycosylated haemoglobin, creatinine, lipoproteins and C Reactive Protein (CRP), fluorescent AGES by spectrophotofluorimetry and non-fluorescent AGEs by measurement of N(ε)-carboxymethyl-Lysine (CML) using an ELISA kit in a subsample of 82 patients. Urinary fluorescent AGEs, albumin and creatinine were also measured in a morning urine sample. Microvascular complications were studied by ophthalmologic examination, albuminuria and peripheral nerve conduction velocity. RESULTS: Patients without microvascular complications had significantly lower levels of both serum and urinary AGEs. CML was associated with retinopathy. Multiple regression analysis confirmed that AGEs, length of diabetes and glycosylated haemoglobin were all variables associated with diabetic complications, in this sample. CONCLUSIONS: A simple fluorimetric assay to measure low molecular weight fluorescent AGEs, and CML could be employed as screening tools to predict diabetic complications, at a primary care setting. AGEs should probably be considered as another therapeutic target in diabetes management.

Dietary advanced glycation end-products aggravate non-alcoholic fatty liver disease

AIM To determine if manipulation of dietary advanced glycation end product(AGE), intake affects nonalcoholic fatty liver disease(NAFLD) progression and whether these effects are mediated via RAGE. METHODS Male C57Bl6 mice were fed a high fat, high fructose, high cholesterol(HFHC) diet for 33 wk and compared with animals on normal chow. A third group were given a HFHC diet that was high in AGEs. Another group was given a HFHC diet that was marinated in vinegar to prevent the formation of AGEs. In a second experiment, RAGE KO animals were fed a HFHC diet or a high AGE HFHC diet and compared with wildtype controls. Hepatic biochemistry, histology, picrosirius red morphometry and hepatic mR NA were determined. RESULTS Long-term consumption of the HFHC diet generated significant steatohepatitis and fibrosis after 33 wk. In this model, hepatic 4-hydroxynonenal content(a marker of chronic oxidative stress), hepatocyte ballooning, picrosirius red staining, α-smooth muscle actin and collagen type 1A gene expression were all significantly increased. Increasing the AGE content of the HFHC diet by baking further increased these markers of liver damage, but this was abrogated by pre-marination in acetic acid. In response to the HFHC diet, RAGE-/-animals developed NASH of similar severity to RAGE+/+ animals but were protected from the additional harmful effects of the high AGE containing diet. Studies in isolated Kupffer cells showed that AGEs increase cell proliferation and oxidative stress, providing a likely mechanism through which these compounds contribute to liver injury. CONCLUSION In the HFHC model of NAFLD, manipulation of dietary AGEs modulates liver injury, inflammation, and liver fibrosis via a RAGE dependent pathway. This suggests that pharmacological and dietary strategies targeting the AGE/RAGE pathway could slow the progression of NAFLD.

Rosiglitazone inhibits expression of acyl-coenzyme A:cholesterol acyltransferase-1 in THP-1 macrophages induced by advanced glycation end-products

Objective:To investigate the effects of rosiglitazone,a synthetic ligand of peroxisome proliferators-activated receptor gamma(PPARγ),on the expression of acyl-coenzyme A:cholesterol acyltransferase-1(ACAT-1) in phorbol myristate acetate(PMA)-pretreated THP-1 cells after the inducement of advanced glycation end products(AGEs).Methods:After THP-1 cells were cultured in the presence of 0.1 μmol/L PMA for 72 h to induce phagocytic differentiation,the obtained THP-1 macrophages were treated with rosiglitazone for 4 h at different concentrations(1,5 or 10 μmol/L) and then exposed to AGEs-modified bovine serum albumin(AGEs-BSA) for 24 h at a concentration of 200 mg/L.Reverse transcription polymerase chain reaction(RT-PCR) and Western blot analysis were performed to detect the mRNA and protein expressions of ACAT-1 respectively.Results:Administration of AGEs-BSA(200 mg/L) into the THP-1 macrophages resulted in up-regulation of ACAT-1 at mRNA and protein levels when compared with the expressions in macrophages incubated with serum-free RPMI1640.Pretreatment of rosiglitazone inhibited significantly the increased expression of ACAT-1 induced by AGEs-BSA in a concentration-dependent manner.Conclusion:PPARγ activation by rosiglitazone down-regulates ACAT-1 expression induced by AGEs in THP-1 macrophages,which might provide a new way for treating atherogenesis in diabetic patients.

Generation of glyceraldehyde-derived advanced glycation end-products in pancreatic cancer cells and the potential of tumor promotion

AIM To determine the possibility that diabetes mellitus promotes pancreatic ductal adenocarcinoma via glyceraldehyde(GA)-derived advanced glycation-end products(GA-AGEs).METHODS PANC-1,a human pancreatic cancer cell line,was treated with 1-4 mmol/L GA for 24 h. The cell viability and intracellular GA-AGEs were measured by WST-8 assay and slot blotting. Moreover,immunostaining of PANC-1 cells with an anti-GA-AGE antibody was performed. Western blotting(WB) was used to analyze the molecular weight of GA-AGEs. Heat shock proteins 90α,90β,70,27 and cleaved caspase-3 were analyzed by WB. In addition,PANC-1 cells were treated with GA-AGEs-bovine serum albumin(GA-AGEs-BSA),as a model of extracellular GA-AGEs,and proliferation of PANC-1 cells was measured.RESULTS In PANC-1 cells,GA induced the production of GA-AGEs and cell death in a dose-dependent manner. PANC-1 cell viability was approximately 40% with a 2 mmol/L GA treatment and decreased to almost 0% with a 4 mmol/L GA treatment(each significant difference was P < 0.01). Cells treated with 2 and 4 mmol/L GA produced 6.4 and 21.2 μg/mg protein of GA-AGEs,respectively(P <0.05 and P < 0.01). The dose-dependent production of some high-molecular-weight(HMW) complexes of HSP90β,HSP70,and HSP27 was observed following administration of GA. We considered HMW complexes to be dimers and trimers with GA-AGEs-mediated aggregation. Cleaved caspase-3 could not be detected with WB. Furthermore,10 and 20 μg/m L GA-AGEs-BSA was 27% and 34% greater than that of control cells,respectively(P < 0.05 and P < 0.01).CONCLUSION Although intracellular GA-AGEs induce pancreatic cancer cell death,their secretion and release may promote the proliferation of other pancreatic cancer cells.

Regulatory role of peroxynitrite in advanced glycation end products mediated diabetic cardiovascular complications

The Advanced Glycation End Products(AGE)binding with its receptor can increase reactive oxygen species(ROS)generation through specific signaling mediators.The effect of superoxide(O2-)and O2-mediated ROS and reactive nitrogen species depends on their concentration and location of formation.Nitric oxide(NO)has anti-inflammatory and anticoagulant properties and a vasodilation effect,but NO can be deactivated by reacting with O_(2)^(-).This reaction between NO and O2-produces the potent oxidant ONOO−.Therefore,ONOO-'s regulatory role in AGEs in diabetic cardiovascular complications must considered as a regulator of cardiovascular complications in diabetes.

Contributions of the receptor for advanced glycation end products axis activation in gastric cancer

Compelling shreds of evidence derived from both clinical and experimental research have demonstrated the crucial contribution of receptor for advanced glycation end products(RAGE)axis activation in the development of neoplasms,including gastric cancer(GC).This new actor in tumor biology plays an important role in the onset of a crucial and long-lasting inflammatory milieu,not only by supporting phenotypic changes favoring growth and dissemination of tumor cells,but also by functioning as a pattern-recognition receptor in the inflammatory response to Helicobacter pylori infection.In the present review,we aim to highlight how the overexpression and activation of the RAGE axis contributes to the proliferation and survival of GC cells as and their acquisition of more invasive phenotypes that promote dissemination and metastasis.Finally,the contribution of some single nucleotide polymorphisms in the RAGE gene as susceptibility or poor prognosis factors is also discussed.

Inhibitory effect of eleven herbal extracts on advanced glycation end-products formation and aldose reductase activity

The formation of advanced glycation end-products （AGEs） and aldose reductase （AR） activity have been implicated in the development of diabetic complications. Our study sought to characterize the capacities of eleven herbal extracts against the formation of AGEs and the AR activity. An ultrahigh performance liquid chromatography and tandem mass spectrometry （UPLC-MS/MS） method was used for the detection of AR activity and the screening of AR inhibitors in this research. The amount of sorbitol from each analyte was directly detected using the multiple reaction monitoring mode and the sorbitol level could be reduced via the addition of an inhibitor. Moreover, the BSA/glucose （fructose） system was applied to investigate their inhibitory activities of AGEs formation in glycation model reactions. Compared with other screened herbs used in our study, Flos Sophorae lrnrnaturus and Radix Scutellariae seemed to be more effective on inhibiting the formation of AGEs and AR activity. The inhibiting capacities of herbal extracts against AR activity and AGEs formation may be correlated with the bioactive components of the herbal extracts. The differences were correlated with the amount of polyphenol and flavonoid components. In the study, we have investigated the potential anti-hyperglycemic bioactivity of eleven herbal extracts in vitro, which could provide a reference for further in vivo research in the prevention and treatment of diabetic complications.

Complications in the spine associated with type 2 diabetes:The role of advanced glycation end-products

Type 2 diabetes mellitus(T2D)is an increasingly prevalent disease with numerous comorbidities including many in the spine.T2D is strongly linked with vertebral fractures,intervertebral disc(IVD)degeneration,and severe chronic spinal pain.Yet the causative mechanism for these musculoskeletal impairments remains unclear.The chronic hyperglycemic state in T2D promotes the formation of advanced glycation end-products(AGEs)in tissues,and the accumulation of AGEs may play a role in musculoskeletal complications by modifying the extracellular matrix,impairing cellular homeostasis,and perpetuating an inflammatory cascade via its receptor(RAGE).The AGE and RAGE associated alterations in extracellular matrix composition and morphological features of the vertebral bodies and IVDs are likely contributors to the incidence and severity of spinal pathologies in T2D.This review will broadly examine the effects of AGEs on tissues in the spine in the context of T2D,with an emphasis on the changes in the vertebrae and the IVD.Along with the clinical and epidemiological findings,we will provide an overview of preclinical rodent models of T2D that exhibit deficits in the IVD and vertebral bone.Elucidating the role of AGEs and RAGE will be crucial for understanding the disease mechanisms and translation therapies of musculoskeletal pathologies in T2D.

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.

Advanced-glycation end-products axis:A contributor to the risk of severe illness from COVID-19 in diabetes patients

Compelling pieces of evidence derived from both clinical and experimental research has demonstrated the crucial role of the receptor for advanced-glycation end-products(RAGE)in orchestrating a plethora of proinflammatory cellular responses leading to many of the complications and end-organ damages reported in patients with diabetes mellitus(DM).During the coronavirus disease 2019(COVID-19)pandemic,many clinical reports have pointed out that DM increases the risk of COVID-19 complications,hospitalization requirements,as well as the overall severe acute respiratory syndrome coronavirus 2 case-fatality rate.In the present review,we intend to focus on how the basal activation state of the RAGE axis in common preexisting conditions in DM patients such as endothelial dysfunction and hyperglycemia-related prothrombotic phenotype,as well as the contribution of RAGE signaling in lung inflammation,may then lead to the increased mortality risk of COVID-19 in these patients.Additionally,the crosstalk between the RAGE axis with either another severe acute respiratory syndrome coronavirus 2 receptor molecule different of angiotensin-converting enzyme 2 or the renin-angiotensin system imbalance produced by viral infection,as well as the role of this multi-ligand receptor on the obesity-associated lowgrade inflammation in the higher risk for severe illness reported in diabetes patients with COVID-19,are also discussed.

The effect of protein oxidation on the formation of advanced glycation end products after chicken myofibrillar protein glycation

Investigation that protein oxidation to the formation of advanced glycation end products(AGEs)after chicken myofibrillar protein glycation is limited.Models of protein oxidation induced by different concentrations of hydroxyl radicals(·OH)were developed after the chicken myofibrillar protein mild glycation(MPG).Results exhibited that levels of AGEs and surface hydrophobicity(H_(0))steadily increased with the a ddition of h ydrogen peroxide(H_(2)O_(2))concentration.However,levels of s ulfhydryl group,free amino group,and particle size gradually decreased with the H_(2)O_(2)concentration.The protein carbonyl value increased in H_(2)O_(2)concentration until 10 mmol/L.Pearson's correlation indicated that MPG structure modification(unfolding and degradation)induced by protein oxidation were significantly positively correlated with AGEs concentration(P<0.05).Finally,a mechanism was proposed to hypothesize t he effect of protein oxidation on the formation of AGEs under MPG conditions.

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.

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.

Catalpol Prevents Glomerular Angiogenesis Induced by Advanced Glycation End Products via Inhibiting Galectin-3

Objective:The main characteristics of diabetic nephropathy(DN)at the early stage are abnormal angiogenesis of glomerular endothelial cells(GECs)and macrophage infiltration.Galectin-3 plays a pivotal role in the pathogenesis of DN via binding with its ligand,advanced glycation end products(AGEs).Catalpol,an iridoid glucoside extracted from Rehmannia glutinosa,has been found to ameliorate vascular inflammation,reduce endothelial permeability,and protect against endothelial damage in diabetic milieu.However,little is known about whether catalpol could exert an anti-angiogenesis and anti-inflammation effect induced by AGEs.Methods:Mouse GECs(mGECs)and RAW 264.7 macrophages were treated with different concentrations of AGEs(0,50,100,200 and 400μg/mL)for different time(0,6,12,24 and 48 h)to determine the optimal concentration of AGEs and treatment time.Cells were treated with catalpol(10μmol/L),GB1107(1μmol/L,galectin-3 inhibitor),PX-478(50μmol/L,HIF-1αinhibitor),adenovirus-green fluorescent protein(Ad-GFP)[3×10^(7)plaque-forming unit(PFU)/mL]or Ad-galectin-3-GFP(2×10^(8)PFU/mL),which was followed by incubation with 50μg/mL AGEs.The levels of galectin-3,vascular endothelial growth factor A(VEGFA)and pro-angiogenic factors angiopoietin-1(Ang-1),angiopoietin-2(Ang-2),tunica interna endothelial cell kinase-2(Tie-2)were detected by enzyme-linked immunosorbent assay(ELISA).Cell counting kit-8(CCK-8)assay was used to evaluate the proliferation of these cells.The expression levels of galectin-3,vascular endothelial growth factor receptor 1(VEGFR1),VEGFR2,and hypoxia-inducible factor-1α(HIF-1α)in mGECs and those of galectin-3 and HIF-1αin RAW 264.7 macrophages were detected by Western blotting and immunofluorescence(IF)staining.The rat DN model was established.Catalpol(100 mg/kg)or GB1107(10 mg/kg)was administered intragastrically once a day for 12 weeks.Ad-galectin-3-GFP(6×10^(7)PFU/mL,0.5 mL)or Ad-GFP(6×10^(6)PFU/mL,0.5 mL)was injected into the tail vein of rats 48 h before the sacrifice of the animals.The expression of galectin-3,VEGFR1,.VEGFR2,and HIF-1αin renal cortices was analyzed by Western blotting.The expression of galectin-3,F4/80(a macrophage biomarker),and CD34(an endothelium biomarker)in renal cortices was detected by IF staining,and collagen accumulation by Masson staining.Results:The expression levels of galectin-3 and VEGFA were significantly higher in mGECs and RAW 264.7 macrophages treated with 50μg/mL AGEs for 48 h than those in untreated cells.Catalpol and GB1107 could block the AGEs-induced proliferation of mGECs and RAW 264.7 macrophages.Over-expression of galectin-3 was found to reduce the inhibitory effect of catalpol on the proliferation of cells.Catalpol could significantly decrease the levels of Ang-1,Ang-2 and Tie-2 released by AGEs-treated mGECs,which could be reversed by over-expression of galectin-3.Catalpol could significantly inhibit AGEs-induced expression of galectin-3,HIF-1α,VEGFR1,and VEGFR2 in mGECs.The inhibitory effect of catalpol on galectin-3 in AGEs-treated mGECs was impaired by PX-478.Moreover,catalpol attenuated the AGEs-activated HIF-1α/galectin-3 pathway in RAW 264.7 macrophages,which was weakened by PX-478.Additionally,catalpol significantly inhibited the expression of galectin-3,macrophage infiltration,collagen accumulation,and angiogenesis in the kidney of diabetic rats.Over-expression of galectin-3 could antagonize these inhibitory effects of catalpol.Conclusion:Catalpol prevented the angiogenesis of mGECs and macrophage proliferation via inhibiting galectin-3.It could prevent the progression of diabetes-induced renal damage.

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.