RAGE Inhibition Research Articles

Receptor of Advanced Glycation End Products Deficiency Attenuates Cisplatin-Induced Acute Nephrotoxicity by Inhibiting Apoptosis, Inflammation and Restoring Fatty Acid Oxidation.

Cisplatin is a widely used and potent anti-neoplastic agent, but severe and inescapable side effects in multiple normal tissues and organs limit its application, especially nephrotoxicity. Molecular mechanisms of cisplatin nephrotoxicity involve mitochondrial damage, oxidative stress, endoplasmic reticulum stress, inflammation, apoptosis, necroptosis, etc. Receptor of advanced glycation end products (RAGE) is a multiligand pattern recognition receptor, engaged in inflammatory signaling and mitochondrial homeostasis. Whether inhibition of RAGE alleviates cisplatin-induced nephropathy has not been investigated. Here, we revealed that RAGE deficiency attenuates cisplatin-induced acute nephrotoxicity, as evidenced by reduced apoptosis, inflammation, lipid accumulation, restored mitochondrial homeostasis and fatty acid oxidation in renal tubular epithelial cells (TECs). In vitro studies showed that, the RAGE-specific inhibitor FPS-ZM1 attenuated the cisplatin-induced decrease of cell viability and fatty acid oxidation in the normal rat renal TEC line NRK-52E cells. Taken together, RAGE knockout mitigated cisplatin-induced acute nephrotoxicity by inhibiting apoptosis, inflammation, and restoring fatty acid oxidation in TECs, suggesting that RAGE inhibition could be a therapeutic option for cisplatin-induced acute nephrotoxicity.

Abstract 136: Vascular Impairment From Acute Exposure To E-cigarette Aerosol Is Rescued By Inhibition Of The Receptor For Advanced Glycation End Products (RAGE)

Introduction: E-cigarette use is known to induce vascular impairment by altering vasomotor and cellular functions of the vascular wall, but the molecular mechanism of e-cigarette-induced vascular impairment is largely unexplored. We investigated whether inhibition of RAGE prevents impairment of vasomotor function from acute e-cigarette exposure Hypothesis: Impairment of endothelial vasodilatory function requires the activation of RAGE. Methods: Anesthetized rats (n=8/group) were exposed to aerosols from flavorless tank style e-cigarettes with and without freebase nicotine (12 mg/ml) or air in a single session of 10 cycles of pulsatile 5s exposure over 5 minutes. For each exposure condition, groups received either 1 mg/kg of RAGE inhibitor FPS-ZM1 or vehicle i.p. 1 hour before exposure (i.e., total of 6 groups). Femoral artery flow-mediated dilation (FMD) was measured using micro-ultrasound before and after exposure. Results: Exposure to e-cigarette aerosol with and without nicotine impaired FMD in vehicle groups (8.3±2.7% pre-exposure vs 4.7±2.4% post-exposure, p=0.01; 9.3±4.6% pre- vs 4.8±2.7% post-, p=0.03, respectively), with no change in air control (9.7±3.2% pre- vs 9.3±3.5% post-, p=0.81). Post-exposure FMD in both aerosol groups with vehicle was lower than that in the air group with vehicle (p=0.01 for each aerosol vs air). However, FPS-ZM1 prevented the FMD impairment by aerosol exposure (with nicotine 9.1±3.5% pre- vs 8.9±2.1% post-, p=0.90; without nicotine 9.5±4.3% pre- vs 7.1±2.0% post-, p=0.17), with no change in air control (7.6±2.7% pre- vs 7.4±3.1% post-, p=0.86). Post-exposure FMD values in both aerosol groups receiving FPS-ZM1 were comparable to the air control (p=0.4 and 0.8, respectively). There were no significant difference in post-exposure FMD in the air groups receiving FPS-ZM1 or vehicle (p>0.99). Conclusions: RAGE mediates e-cigarette-induced acute impairment of endothelial vasodilatory function.

RAGE Regulating Vascular Remodeling in Diabetes by Regulating Mitochondrial Dynamics with JAK2/STAT3 Pathway.

In this research, we will explore the role and modulation of mitochondrial dynamics in diabetes vascular remodeling. Only a few cell types express the pattern recognition receptor, also known as the AGE receptor (RAGE). However, it is triggered in almost all of the cells that have been investigated thus far by events that are known to cause inflammation. Here, Type 2 diabetes was studied in both cellular and animal models. Elevated Receptor for advanced glycation end products (RAGE), phosphorylated JAK2 (p-JAK2), phosphorylated STAT3 (p-STAT3), transient receptor potential ion channels (TRPM), and phosphorylated dynamin-related protein 1 (p-DRP1) were observed in the context of diabetes. In addition, we found that inhibition of RAGE was followed by a remarkable decrease in the expression of the above proteins. It has also been demonstrated by western blotting and immunofluorescence results in vivo and in vitro. Suppressing STAT3 and DRP1 phosphorylation produced effects similar to those of RAGE inhibition on the proliferation, cell cycle, migration, invasion, and expression of TRPM in VSMCs and vascular tissues obtained from diabetic animals. These findings indicate that RAGE regulates vascular remodeling via mitochondrial dynamics through modulating the JAK2/STAT3 axis in diabetes. The findings could be crucial in gaining a better understanding of diabetes-related vascular remodeling. It also contributes to a better cytopathological understanding of diabetic vascular disease and provides a theoretical foundation for novel targets that aid in the prevention and treatment of diabetes-related cardiovascular problems.

RAGE Inhibitors as Alternatives to Dexamethasone for Managing Cerebral Edema Following Brain Tumor Surgery.

Resection of brain tumors frequently causes injury to the surrounding brain tissue that exacerbates cerebral edema by activating an inflammatory cascade. Although corticosteroids are often utilized peri-operatively to alleviate the symptoms associated with brain edema, they increase operative morbidities and suppress the efficacy of immunotherapy. Thus, novel approaches to minimize cerebral edema caused by neurosurgical procedures will have significant utility in the management of patients with brain tumors.We have studied the role of the receptor for advanced glycation end products (RAGE) and its ligands on inflammatory responses to neurosurgical injury in mice and humans. Blood-brain barrier (BBB) integrity and neuroinflammation were characterized by Nanostring, flow cytometry, qPCR, and immunoblotting of WT and RAGE knockout mice brains subjected to surgical brain injury (SBI). Human tumor tissue and fluid collected from the resection cavity of patients undergoing craniotomy were also analyzed by single-cell RNA sequencing and ELISA.Genetic ablation of RAGE significantly abrogated neuroinflammation and BBB disruption in the murine SBI model. The inflammatory responses to SBI were associated with infiltration of S100A9-expressing myeloid-derived cells into the brain. Local release of pro-inflammatory S100A9 was confirmed in patients following tumor resection. RAGE and S100A9 inhibitors were as effective as dexamethasone in attenuating neuroinflammation. However, unlike dexamethasone and S100A9 inhibitor, RAGE inhibition did not diminish the efficacy of anti-PD-1 immunotherapy in glioma-bearing mice. These observations confirm the role of the RAGE axis in surgically induced neuroinflammation and provide an alternative therapeutic option to dexamethasone in managing post-operative cerebral edema.

Abstract P4-04-13: S100a7/rage signaling promotes breast tumorigenesis through modulating tumor-associated macrophages

Abstract S100A7 has been shown to be associated with breast cancer growth and metastasis. However, the molecular mechanism through which S100A7 promotes breast tumorigenesis is not completely understood. In this study, we revealed that S100A7 enhanced Stat3-mediated secretion of Serpin-E1 in triple negative breast cancer (TNBC) cell lines. Serpin-E1 has been shown to promote recruitment and polarization toward a pro-tumorigenic phenotype of tumor-associated macrophages through activating the Stat3 pathway. Importantly, we reported that the inhibition of Stat3 led to reduction of S100A7-mediated invasiness of TNBC cells and also significantly decreased the secretion of Serpin-E1 by cancer cells. We also revealed that Stat3 inhibition in TNBC cells or Serpin-E1 neutralization significantly reduced the migration of human monocytes/macrophages by transwell migration assay. We further demonstrate that murine ortholog of S100A7, mS100a7a15 enhanced mammary hyperplasia, tumor growth and metastasis through Stat3 activation. Previously, we reported that S100A7 mediated its tumorigenic effects through RAGE in breast cancer cells. Therefore, we also discovered that combinatorial treatment of Stat3 and RAGE inhibitors in mammary tumor bearing mS100a7a15 overexpression mouse model strongly decreased the tumor burden and enhanced the recruitment of tumor-suppressing M1-macrophages. We also found that combined inhibition of RAGE and Stat3 significantly increased the infiltration of CD4 T cells in the tumor microenvironment (TME). Collectively, these findings suggest S100A7/RAGE signaling pathway could be used as a novel therapeutic target to inhibit breast cancer growth and metastasis through modulating the TME. Citation Format: Ajeet K Verma, Tasha Wilkie, Sanjay Mishra, Manish Charan, Ramesh K Ganju. S100a7/rage signaling promotes breast tumorigenesis through modulating tumor-associated macrophages [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P4-04-13.

Abstract 9929: Inhibition of Receptor for Advanced Glycation End Products (RAGE) Reduces E-Cigarette-Induced Increase in Endothelial Permeability

Introduction: A growing body of research has linked e-cigarette (e-cig) use and vascular dysfunction. However, the molecular mechanism of endothelial function impairment from e-cig use is relatively unknown. We investigated how e-cig use affects endothelial permeability and its regulation by the receptor for advanced glycation end products (RAGE) pathway. Hypothesis: E-cig use increases endothelial permeability compared to both cigarette users and non-users via increasing ligands of RAGE. Methods: We recruited 120 healthy participants who either chronically use e-cigs (n=42), cigarettes (n=28), or no products (n=50), with no dual users. Serum levels of the RAGE ligand subunit S100A8 and the complete RAGE ligand calprotectin were quantified by Luminex and ELISA. Endothelial permeability was measured in cultured human lung microvascular endothelial cells (HMVEC-Ls) that were incubated in all participants’ sera individually by using electric cell-substrate impedance sensing (ECIS). 1 ug/mL of FPS-ZM1 (RAGE inhibitor) and TAK-242 (TLR4 inhibitor) diluted in DMSO were administered to HMVEC-Ls with individual sera. 200 pg/mL of calprotectin and DMSO were administered as positive and negative controls. Results: Incubation of HMVEC-Ls with e-cig users’ sera significantly increased endothelial permeability compared to sera from cigarette smokers and non-users. There was no significant difference in calprotectin serum levels, but S100A8 level was significantly and substantially higher in e-cig users’ sera than in smokers’ and non-user’s sera. Inhibition of RAGE, but not of TLR4, significantly reduced permeability only in e-cig users’ sera compared to vehicle. Conclusions: Endothelial permeability resulting from e-cig use relies on activation of the RAGE pathway and can be partially prevented by inhibition of RAGE.

Induction of RAGE-NFkB signalling axis enhances SHP-2 tyrosine phosphatase expression resulting in deviant activation of diabetic monocytes

Abstract Purpose Aberrant activation of Type 2 Diabetes mellitus (T2DM) monocytes is an important pathomechanism leading to restricted arteriogenesis and augmented atherosclerosis, hereby, accelerating CAD and PAD. Tyrosine phosphatase SHP-2 was found to be upregulated in T2DM-monocytes. This study aimed to identify the pathways regulating SHP-2 expression in T2DM-monocytes. Methods Primary human monocytes were isolated from the peripheral blood of T2DM patients and healthy individuals. Monocytes were incubated with Methylglyoxal (MG), a highly reactive side product of glycolysis, Receptor for advanced glycation end product (RAGE) ligand AGE-bovine serum (AGE-BSA) or TNFα for 24 hours. Transwell migration assays were used to analyse the migratory potential of monocytes. Western Blot, RT-qPCR and FACS were performed to quantify the expression of relevant molecules. Pharmacological inhibitors were used to study functional relevance of the RAGE-NFκB-SHP-2 signalling axis. Results Significantly enhanced SHP-2 expression was detected in monocytes, which were incubated with TNFα, MG or AGE-BSA, respectively. Co-incubation of these molecules with NFκB-inhibitor blocked SHP-2 upregulation. Pharmacological inhibition of RAGE reversed the MG or AGE-BSA induced SHP-2 expression and activity in monocytes. RAGE expression on monocytes was upregulated after the incubation with MG or AGE-BSA, consistent with enhanced RAGE mRNA levels in T2DM monocytes. Besides, we also detected elevated SHP-2 transcripts in monocytes of T2DM patients which was more pronounced in monocytes with augmented TNFα expression. Furthermore, MG and AGE-BSA provoked the enhanced migration of monocytes which could be significantly reduced after the application of an allosteric SHP-2 inhibitor. Interestingly, pharmacological inhibition of RAGE in these conditions alone was sufficient to block the elevated monocyte migration. Moreover, monocytes isolated from T2DM patients revealed a comparable pro-migratory phenotype, which was completely restored after the pharmacological inhibition of SHP-2. Conclusions This study identified the upstream signalling mediators that contribute to SHP-2 dependent monocyte activation in T2DM conditions. Glucose metabolite (MG) or RAGE ligand (AGE-BSA) alone were sufficient to induce a pro-migratory phenotype in monocytes by upregulating SHP-2. Of note, an inflammatory state seems to accelerate this effect since enhanced TNFα levels were found to be positively correlated with the augmented SHP-2 expression. Moreover, we identified the RAGE-NFκB signalling axis through which the SHP-2 upregulation is conveyed when augmented accumulation of glucose metabolites occur. These findings reveal a basis for potential new therapeutic approaches to prevent accelerated CAD and PAD in diabetic patients since independent pharmacological inhibition of every step in the RAGE-NFκB-SHP-2 axis was sufficient to reset the aberrant monocyte activation. Funding Acknowledgement Type of funding sources: Other. Main funding source(s): Interdisciplinary Center for Clinical Research of the Medical Faculty of the University of Münster

Glyoxal-Lysine Dimer, an Advanced Glycation End Product, Induces Oxidative Damage and Inflammatory Response by Interacting with RAGE.

The glyoxal-lysine dimer (GOLD), which is a glyoxal (GO)-derived advanced glycation end product (AGE), is produced by the glycation reaction. In this study, we evaluated the effect of GOLD on the oxidative damage and inflammatory response in SV40 MES 13 mesangial cells. GOLD significantly increased the linkage with the V-type immunoglobulin domain of RAGE, a specific receptor of AGE. We found that GOLD treatment increased RAGE expression and reactive oxygen species (ROS) production in mesangial cells. GOLD remarkably regulated the protein and mRNA expression of nuclear factor erythroid 2-related factor 2 (NRF2) and glyoxalase 1 (GLO1). In addition, mitochondrial deterioration and inflammation occurred via GOLD-induced oxidative stress in mesangial cells. GOLD regulated the mitogen-activated protein kinase (MAPK) and the release of proinflammatory cytokines associated with the inflammatory mechanism of mesangial cells. Furthermore, oxidative stress and inflammatory responses triggered by GOLD were suppressed through RAGE inhibition using RAGE siRNA. These results demonstrate that the interaction of GOLD and RAGE plays an important role in the function of mesangial cells.

S100B/RAGE/Ceramide signaling pathway is involved in sepsis-associated encephalopathy

AimsSepsis-associated encephalopathy (SAE) is one of the most common complications of sepsis, and it might lead to long-term cognitive dysfunction and disability. This study aimed to explore the role of S100 calcium binding protein B (S100B)/RAGE/ceramide signaling pathway in SAE. Main methodsFPS-ZM1 (an inhibitor of RAGE), myriocin and GW4869 (an inhibitor of ceramide) were used to explore the role of S100B/RAGE/ceramide in acute brain injury and long-term cognitive impairment in sepsis. In addition, Mdivi-1 (inhibitor of Drp1) and Drp1 siRNA were utilized to assess the effects of C2-ceramide on neuronal mitochondria, and to explore the specific underlying mechanism in C2 ceramide-induced death of HT22 mouse hippocampal neuronal cells. Key findingsWestern blot analysis showed that sepsis significantly up-regulated S100B and RAGE. Nissl staining and Morris water maze (MWM) test revealed that inhibition of RAGE with FPS-ZM1 markedly attenuated cecal ligation and puncture (CLP)-induced brain damage and cognitive dysfunction. Furthermore, FPS-ZM1 relieved sepsis-induced C2-ceramide accumulation and abnormal mitochondrial dynamics. Moreover, inhibition of ceramide also showed similar protective effects both in vivo and in vitro. Furthermore, Mdivi-1 and Drp1 siRNA significantly reduced C2-ceramide-induced neuronal mitochondrial fragmentation and cell apoptosis in vitro. SignificanceThis study confirmed that S100B regulates mitochondrial dynamics through RAGE/ceramide pathway, in addition to the role of this pathway in acute brain injury and long-term cognitive impairment during sepsis.

Inhibition of the Receptor for Advanced Glycation End Products Enhances the Cytotoxic Effect of Gemcitabine in Murine Pancreatic Tumors.

Pancreatic ductal adenocarcinoma (PDAC) remains a very difficult cancer to treat. Recent in vitro and in vivo studies suggest that the activation of the receptor for advanced glycation end products (RAGE) by its ligands stimulates pancreatic cancer cell proliferation and tumor growth. Additional studies show that, in the RAGE ligand, the high mobility group box 1 (HMGB1) protein plays an important role in chemoresistance against the cytotoxic agent gemcitabine by promoting cell survival through increased autophagy. We hypothesized that blocking the RAGE/HMGB1 interaction would enhance the cytotoxic effect of gemcitabine by reducing cell survival and autophagy. Using a preclinical mouse model of PDAC and a monoclonal antibody (IgG 2A11) as a RAGE inhibitor, we demonstrate that RAGE inhibition concurrent with gemcitabine treatment enhanced the cytotoxic effect of gemcitabine. The combination of IgG 2A11 and gemcitabine resulted in decreased autophagy compared to treatment with gemcitabine combined with control antibodies. Notably, we also observed that RAGE inhibition protected against excessive weight loss during treatment with gemcitabine. Our data suggest that the combination of gemcitabine with a RAGE inhibitor could be a promising therapeutic approach for the treatment of pancreatic cancer and needs to be further investigated.

Deficiency of Mitochondrial Glycerol 3-Phosphate Dehydrogenase Exacerbates Podocyte Injury and the Progression of Diabetic Kidney Disease.

Mitochondrial function is essential for bioenergetics, metabolism, and signaling and is compromised in diseases such as proteinuric kidney diseases, contributing to the global burden of kidney failure, cardiovascular morbidity, and death. The key cell type that prevents proteinuria is the terminally differentiated glomerular podocyte. In this study, we characterized the importance of mitochondrial glycerol 3-phosphate dehydrogenase (mGPDH), located on the inner mitochondrial membrane, in regulating podocyte function and glomerular disease. Specifically, podocyte-dominated mGPDH expression was downregulated in the glomeruli of patients and mice with diabetic kidney disease and adriamycin nephropathy. Podocyte-specific depletion of mGPDH in mice exacerbated diabetes- or adriamycin-induced proteinuria, podocyte injury, and glomerular pathology. RNA sequencing revealed that mGPDH regulated the receptor for the advanced glycation end product (RAGE) signaling pathway, and inhibition of RAGE or its ligand, S100A10, protected against the impaired mitochondrial bioenergetics and increased reactive oxygen species generation caused by mGPDH knockdown in cultured podocytes. Moreover, RAGE deletion in podocytes attenuated nephropathy progression in mGPDH-deficient diabetic mice. Rescue of podocyte mGPDH expression in mice with established glomerular injury significantly improved their renal function. In summary, our study proposes that activation of mGPDH induces mitochondrial biogenesis and reinforces mitochondrial function, which may provide a potential therapeutic target for preventing podocyte injury and proteinuria in diabetic kidney disease.

The receptor for advanced glycation end products mediates dysfunction of airway epithelial barrier in a lipopolysaccharides-induced murine acute lung injury model

BackgroundAirway epithelial cells (AECs) act as the first barrier protecting against invasion of environment agents and maintain integrity of lung structure and function. Dysfunction of airway epithelial barrier has been shown to be involved in ALI/ARDS pathogenesis. Yet, the exact mechanism is still obscure. Our study evaluated whether the receptor for advanced glycation end products (RAGE) mediates impaired airway epithelial barrier in LPS-induced murine ALI model. MethodsMale BALB/c mice were subjected to intratracheal instillation of LPS to generate an ALI model. Inhibitors of RAGE, FPS-ZM1 and Azeliragon were respectively given to the mice through intraperitoneal injection. Bronchoalveolar lavage fluid (BALF) and lung tissues were collected for further analysis. ResultsLPS exposure led to markedly increased expression of RAGE and its ligands HMGB1, HSP70, S100b. Treatment of FPS-ZM1 or Azeliragon not only effectively descended the expression of RAGE and its ligands but also attenuated LPS-induced neutrophil-predominant airway inflammation and injury, decreased levels of IL-6, IL-1β and TNF-α in BALF, alleviated increased alveolar-capillary permeability and pulmonary edema. LPS stimulation significantly impaired the integrity of airway epithelium, paralleled with dislocation of adheren junction (AJ) protein E-cadherin at cell-cell contacts and down-expression of both AJ and tight junction (TJ) proteins Claudin-2 and occludin, all of which were dramatically rescued by RAGE inhibition. ConclusionRAGE signaling mediates airway epithelial barrier dysfunction in a LPS-induced ALI murine model.

Targeting of the receptor for advanced glycation end products regulates neutrophil infiltration and extravascular recruitment in mice acute pancreatitis.

Infiltration of leukocytes and pancreatic acinar cell damaging are good indicators of extreme Acute Pancreatitis (AP). The signaling pathways for inflammation and tissue damage of the pancreas not been elucidated yet. In this study, we evaluated the role of targeting of the Receptor for Advanced Glycation End products (RAGE) signaling in AP. Moreover, we investigated the role of signaling RAGE in AP. C57BL/6 mice were injected with a RAGE inhibitor (anti-RAGE) (500 μg/kg) before induction of taurocholate into the pancreatic duct to induce pancreatitis. Treatment anti-RAGE decreased blood amylase concentration, neutrophil recruitment in the pancreas, hemorrhage and edema formation in pancreatitis decreased by taurocholate. Additionally, anti-RAGE administration decreased the MPO activity in the pancreas and lung induced by taurocholate. Intraperitoneal (IP) injection of anti-RAGE significantly decreased concentrations of CXCL2 and IL-6 in the pancreas and plasma respectively in response to challenges of taurocholate. Finally, RAGE inhibition did not have a direct impact on secretagogue-induced trypsinogen activation in pancreatic acinar cells in vitro. Thus, these findings show new signaling pathways in AP and suggest that RAGE targeting may be an efficient way to improve extreme AP.

Inhibitory effects of RAGE-aptamer on development of monocrotaline-induced pulmonary arterial hypertension in rats

BackgroundThe receptor for advanced glycation end products (RAGE), a transmembrane receptor belonging to the immunoglobulin superfamily, is overexpressed in pulmonary artery smooth muscle cells (PASMCs) in patients with pulmonary arterial hypertension (PAH) and is implicated in the etiology of PAH. Recently, we reported that RAGE-aptamer, a short and single-stranded DNA directed against RAGE, inhibited an inappropriate increase in cultured PASMCs in PAH. The aim of this study was to determine the efficacy of RAGE-aptamer in monocrotaline-induced PAH in rats. Methods and ResultsRats were assigned to either an untreated control group, a group that received continuous subcutaneous administration of RAGE-aptamer immediately after monocrotaline injection, or a group that received control-aptamer immediately after monocrotaline injection. All rats survived 21 days after injection of monocrotaline and control-aptamer or RAGE-aptamer. Injection of monocrotaline with continuous subcutaneous delivery of control-aptamer resulted in higher right ventricular systolic pressure compared with controls. This increase was attenuated by continuous subcutaneous delivery of RAGE-aptamer. The proportion of small pulmonary arteries with full muscularization was greater in the monocrotaline and control-aptamer group than in the control group. Continuous subcutaneous delivery of RAGE-aptamer significantly reduced the percentage of small pulmonary arteries with full muscularization. ConclusionsContinuous subcutaneous delivery of RAGE-aptamer suppresses development of monocrotaline-induced PAH in rats. Inhibition of RAGE ameliorates muscularization of small pulmonary arteries. Treatment with RAGE-aptamer might be a new therapeutic option for PAH.

RAGE and TLR4 differentially regulate airway hyperresponsiveness: Implications for COPD.

The receptor for advanced glycation end products (RAGE) and Toll-like receptor 4 (TLR4) is implicated in COPD. Although these receptors share common ligands and signalling pathways, it is not known whether they act in concert to drive pathological processes in COPD. We examined the impact of RAGE and/or TLR4 gene deficiency in a mouse model of COPD and also determined whether expression of these receptors correlates with airway neutrophilia and airway hyperresponsiveness (AHR) in COPD patients. We measured airway inflammation and AHR in wild-type, RAGE-/- , TLR4-/- and TLR4-/- RAGE-/- mice following acute exposure to cigarette smoke (CS). We also examined the impact of smoking status on AGER (encodes RAGE) and TLR4 bronchial gene expression in patients with and without COPD. Finally, we determined whether expression of these receptors correlates with airway neutrophilia and AHR in COPD patients. RAGE-/- mice were protected against CS-induced neutrophilia and AHR. In contrast, TLR4-/- mice were not protected against CS-induced neutrophilia and had more severe CS-induced AHR. TLR4-/- RAGE-/- mice were not protected against CS-induced neutrophilia but were partially protected against CS-induced mediator release and AHR. Current smoking was associated with significantly lower AGER and TLR4 expression irrespective of COPD status, possibly reflecting negative feedback regulation. However, consistent with preclinical findings, AGER expression correlated with higher sputum neutrophil counts and more severe AHR in COPD patients. TLR4 expression did not correlate with neutrophilic inflammation or AHR. Inhibition of RAGE but not TLR4 signalling may protect against airway neutrophilia and AHR in COPD.

Receptor for Advanced Glycation End Products (RAGE) Mediates Cognitive Impairment Triggered by Pneumococcal Meningitis.

Pneumococcal meningitis is a life-threatening infection of the central nervous system (CNS), and half of the survivors of meningitis suffer from neurological sequelae. We hypothesized that pneumococcal meningitis causes CNS inflammation via the disruption of the blood-brain barrier (BBB) and by increasing the receptor for advanced glycation end product (RAGE) expression in the brain, which causes glial cell activation, leading to cognitive impairment. To test our hypothesis, 60-day-old Wistar rats were subjected to meningitis by receiving an intracisternal injection of Streptococcus pneumoniae or artificial cerebrospinal fluid as a control group and were treated with a RAGE-specific inhibitor (FPS-ZM1) in saline. The rats also received ceftriaxone 100mg/kg intraperitoneally, bid, and fluid replacements. Experimental pneumococcal meningitis triggered BBB disruption after meningitis induction, and FPS-ZM1 treatment significantly suppressed BBB disruption. Ten days after meningitis induction, surviving animals were free from infection, but they presented increased levels of TNF-α and IL-1β in the prefrontal cortex (PFC); high expression levels of RAGE, amyloid-β (Aβ1-42), and microglial cell activation in the PFC and hippocampus; and memory impairment, as evaluated by the open-field, novel object recognition task and Morris water maze behavioral tasks. Targeted RAGE inhibition was able to reduce cytokine levels, decrease the expression of RAGE and Aβ1-42, inhibit microglial cell activation, and improve cognitive deficits in meningitis survivor rats. The sequence of events generated by pneumococcal meningitis can persist long after recovery, triggering neurocognitive decline; however, RAGE blocker attenuated the development of brain inflammation and cognitive impairment in experimental meningitis.

Effects of RAGE inhibition on the progression of the disease in hSOD1G93A ALS mice.

Astrocytes play a key role in the progression of amyotrophic lateral sclerosis (ALS) by actively inducing the degeneration of motor neurons. Motor neurons isolated from receptor for advanced glycation end products (RAGE)‐knockout mice are resistant to the neurotoxic signal derived from ALS‐astrocytes. Here, we confirmed that in a co‐culture model, the neuronal death induced by astrocytes over‐expressing the ALS‐linked mutant hSOD1G93A is prevented by the addition of the RAGE inhibitors FPS‐ZM1 or RAP. These inhibitors also prevented the motor neuron death induced by spinal cord extracts from symptomatic hSOD1G93A mice. To evaluate the relevance of this neurotoxic mechanism in ALS pathology, we assessed the therapeutic potential of FPS‐ZM1 in hSOD1G93A mice. FPS‐ZM1 treatment significantly improved hind‐limb grip strength in hSOD1G93A mice during the progression of the disease, reduced the expression of atrophy markers in the gastrocnemius muscle, improved the survival of large motor neurons, and reduced gliosis in the ventral horn of the spinal cord. However, we did not observe a statistically significant effect of the drug in symptoms onset nor in the survival of hSOD1G93A mice. Maintenance of hind‐limb grip strength was also observed in hSOD1G93A mice with RAGE haploinsufficiency [hSOD1G93A;RAGE(+/‐)], further supporting the beneficial effect of RAGE inhibition on muscle function. However, no benefits were observed after complete RAGE ablation. Moreover, genetic RAGE ablation significantly shortened the median survival of hSOD1G93A mice. These results indicate that the advance of new therapies targeting RAGE in ALS demands a better understanding of its physiological role in a cell type/tissue‐specific context.

RAGE modulatory effects on cytokines network and histopathological conditions in malarial mice

This study was aimed at investigating the involvement of Receptor for Advanced Glycation End Products (RAGE) during malaria infection and the effects of modulating RAGE on the inflammatory cytokines release and histopathological conditions of affected organs in malarial animal model. Plasmodium berghei (P. berghei) ANKA-infected ICR mice were treated with mRAGE/pAb and rmRAGE/Fc Chimera drugs from day 1 to day 4 post infection. Survival and parasitaemia levels were monitored daily. On day 5 post infection, mice were sacrificed, blood were drawn for cytokines analysis and major organs including kidney, spleen, liver, brain and lungs were extracted for histopathological analysis. RAGE levels were increased systemically during malaria infection. Positive correlation between RAGE plasma concentration and parasitaemia development was observed. Treatment with RAGE related drugs did not improve survival of malaria-infected mice. However, significant reduction on the parasitaemia levels were recorded. On the other hand, inhibition and neutralization of RAGE production during the infection significantly increased the plasma levels of interleukin (IL-4, IL-17A, IL-10 and IL-2) and reduced interferon (IFN)-γ secretion. Histopathological analysis revealed that all treated malarial mice showed a better outcome in histological assessment of affected organs (brain, liver, spleen, lungs and kidney). RAGE is involved in malaria pathogenesis and targeting RAGE could be beneficial in malaria infected host in which RAGE inhibition or neutralization increased the release of anti-inflammatory cytokines (IL-10 and IL-4) and reduce pro-inflammatory cytokine (IFNγ) which may help alleviate tissue injury and improve histopathological conditions of affected organs during the infection.

Inhibition of RAGE by FPS-ZM1 alleviates renal injury in spontaneously hypertensive rats

The current study was designed to examine the protection of RAGE-specific inhibitor FPS-ZM1 against renal injury in spontaneously hypertensive rats (SHR) and investigate the underlying mechanism. The adult male SHR were treated with FPS-ZM1 via oral gavages for 12 weeks, and age-matched male Wistar-Kyoto rats (WKY) were used as control. Treatment of SHR with FPS-ZM1 slightly reduced blood pressure, and significantly improved baroreflex sensitivity in SHR. Treatment of SHR with FPS-ZM1 improved renal function, evidenced by increased glomerular filtration rate and renal blood flow, and reduced plasma creatinine, blood urea nitrogen and urine albumin excretion rate. Histology results revealed that treatment of SHR with FPS-ZM1 alleviated renal injury and reduced tubulointerstitial fibrosis. Treatment of SHR with FPS-ZM1 suppressed activation of NF-κB and reduced expression of pro-inflammatory cytokines including Tnf, Il6, and Il1b. Treatment of SHR with FPS-ZM1 abated oxidative stress and downregulated mRNA levels of components of NADPH oxidase (Nox) including Cyba, Nox1, Nox2, Nox4 and Ncf1 in kidneys. In addition, treatment of SHR with FPS-ZM1 reduced renal AngII levels, downregulated mRNA expression of Ace and upregulated expression of Agtr2. In conclusion, treatment with FPS-ZM1 alleviated hypertension-related renal dysfunction, possibly by suppressing NF-κB-mediated inflammation, abating Nox-mediated oxidative stress, and improving local renal renin-angiotensin system (RAS).

Role and Mechanisms of RAGE-Ligand Complexes and RAGE-Inhibitors in Cancer Progression.

Interactions of the receptor for advanced glycation end product (RAGE) and its ligands in the context of their role in diabetes mellitus, inflammation, and carcinogenesis have been extensively investigated. This review focuses on the role of RAGE-ligands and anti-RAGE drugs capable of controlling cancer progression. Different studies have demonstrated interaction of RAGE with a diverse range of acidic (negatively charged) ligands such as advanced glycation end products (AGEs), high-mobility group box1 (HMGB1), and S100s, and their importance to cancer progression. Some RAGE-ligands displayed effects on anti- and pro-apoptotic proteins through upregulation of the phosphatidylinositide 3-kinase (PI3K)/protein kinase B (Akt)/mammalian target of rapamycin (mTOR), mitogen-activated protein kinases (MAPKs), matrix metalloproteinases (MMPs), vascular endothelial growth factor (VEGF), and nuclear factor kappa B (NF-κB) pathways, while downregulating p53 in cancer progression. In addition, RAGE may undergo ligand-driven multimodal dimerization or oligomerization mediated through self-association of some of its subunits. We conclude our review by proposing possible future lines of study that could result in control of cancer progression through RAGE inhibition.