Receptor For Advanced Glycation Endproducts Ligands Research Articles

The Gly82Ser polymorphism in the receptor for advanced glycation endproducts increases the risk for coronary events in the general population

The receptor for advanced glycation endproducts (RAGE) has pro-inflammatory and pro-atherogenic effects. Low plasma levels of soluble RAGE (sRAGE), a decoy receptor for RAGE ligands, have been associated with increased risk for major adverse coronary events (MACE) in the general population. We performed a genome-wide association study to identify genetic determinants of plasma sRAGE in 4338 individuals from the cardiovascular arm of the Malmö Diet and Cancer study (MDC-CV). Further, we explored the associations between these genetic variants, incident first-time MACE and mortality in 24,640 unrelated individuals of European ancestry from the MDC cohort. The minor alleles of four single nucleotide polymorphisms (SNPs): rs2070600, rs204993, rs116653040, and rs7306778 were independently associated with lower plasma sRAGE. The minor T (vs. C) allele of rs2070600 was associated with increased risk for MACE [HR 1.13 95% CI (1.02–1.25), P = 0.016]. Neither SNP was associated with mortality. This is the largest study to demonstrate a link between a genetic sRAGE determinant and CV risk. Only rs2070600, which enhances RAGE function by inducing a Gly82Ser polymorphism in the ligand-binding domain, was associated with MACE. The lack of associations with incident MACE for the other sRAGE-lowering SNPs suggests that this functional RAGE modification is central for the observed relationship.

S100b treatment overcomes RAGE signaling deficits in myoblasts on advanced glycation end-product cross-linked collagen and promotes myogenic differentiation.

Advanced glycation end-products (AGEs) stochastically accrue in skeletal muscle and on collagen over an individual's lifespan, stiffening the muscle and modifying the stem cell (MuSC) microenvironment while promoting proinflammatory, antiregenerative signaling via the receptor for advanced glycation end-products (RAGEs). In the present study, a novel in vitro model was developed of this phenomenon by cross linking a 3-D collagen scaffold with AGEs and investigating how myoblasts responded to such an environment. Briefly, collagen scaffolds were incubated with d-ribose (0, 25, 40, 100, or 250 mM) for 5 days at 37°C. C2C12 immortalized mouse myoblasts were grown on the scaffolds for 6 days in growth conditions for proliferation, and 12 days for differentiation and fusion. Human primary myoblasts were also used to confirm the C2C12 data. AGEs aberrantly extended the DNA production stage of C2C12s (but not in human primary myoblasts) which is known to delay differentiation in myogenesis, and this effect was prevented by RAGE inhibition. Furthermore, the differentiation and fusion of myoblasts were disrupted by AGEs, which were associated with reductions in integrins and suppression of RAGE. The addition of S100b (RAGE agonist) recovered the differentiation and fusion of myoblasts, and the addition of RAGE inhibitors (FPS-ZM1 and Azeliragon) inhibited the differentiation and fusion of myoblasts. Our results provide novel insights into the role of the AGE-RAGE axis in skeletal muscle aging, and future work is warranted on the potential application of S100b as a proregenerative factor in aged skeletal muscle.NEW & NOTEWORTHY Collagen cross-linked by advanced glycation end-products (AGEs) induced myoblast proliferation but prevented differentiation, myotube formation, and RAGE upregulation. RAGE inhibition occluded AGE-induced myoblast proliferation, while the delivery of S100b, a RAGE ligand, recovered fusion deficits.

Abstract PR06: Uncovering nuclear expulsion: chromatin-bound signals from dying cancer cells accelerate metastatic outgrowth through S100A4-RAGE pathway

Abstract Tumor cells are highly heterogeneous, exhibiting diverse responses when exposed to different environments. We have recently observed this heterogeneity in tumor cell apoptosis by which some tumor cell die for the benefits of the population’s survival. Majority of tumor cells undergo apoptosis in response to immune surveillance, various treatments, and a hostile microenvironment, both in circulation and at metastatic organ sites. However, the full range of apoptotic signals, or "last words," that dying cells communicate to the surviving cancer cell community remains incompletely understood. While apoptotic cell death is often perceived as a favorable therapeutic outcome, tumor cells can exploit it to enhance their metastatic capabilities, leading to poor prognoses in certain cancers. Here, we present a remarkable discovery of an altered apoptotic program in tumor cells characterized by nuclear expulsion and citrullinated chromatin, promoting metastatic outgrowth in the lungs in a Padi4-dependent manner. We further identified a calcium spike during apoptosis as the trigger for Padi4 activation, resulting in rapid chromatin de-condensation, nuclear content expulsion, followed by the generation of nuclear expulsion products (NEPs). This process was observed in various types of human cancer tissues. Profiling of proteins bound to the NEP complex unveiled an enrichment of receptor for advanced glycation end-products (RAGE) pathway proteins, such as S100a4 in mouse NEPs and high-mobility group-binding (HMGB) proteins in human NEPs. These chromatin-bound RAGE ligands activated RAGE receptors in neighboring surviving tumor cells, leading to Erk pathway activation. This, in turn, promotes proliferation through the RAGE-MAPK pathway. A nuclear expulsion signature was associated with worse prognoses in cancer patients, underscoring the clinical efficacy in the context of apoptosis-inducing treatments. As we continue our investigations, we are particularly interested in understanding how dying tumor cell-derived NEPs from chemotherapy may affect therapy outcomes. Taken together, our studies uncover a novel mechanism by which tumor cells come together as a community and that the apoptotic tumor cells help live tumor cells metastasize. This insight is likely a step forward to understand the mechanisms of metastatic spread, treatment resistance and relapse. Citation Format: Wooyong Park, Justin M Gray, Ronald J Holewinski, Thorkell Andresson, Jae Young So, Carmelo M Carmona-Rivera, Mariana J Kaplan, Steven D Cappell, Li Yang. Uncovering nuclear expulsion: chromatin-bound signals from dying cancer cells accelerate metastatic outgrowth through S100A4-RAGE pathway [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Advances in Breast Cancer Research; 2023 Oct 19-22; San Diego, California. Philadelphia (PA): AACR; Cancer Res 2024;84(3 Suppl_1):Abstract nr PR06.

A Potential Role for the Receptor for Advanced Glycation End-Products (RAGE) in the Development of Secondhand Smoke-Induced Chronic Sinusitis.

Chronic sinusitis (CS) is characterized by sinonasal inflammation, mucus overproduction, and edematous mucosal tissue. CS impacts one in seven adults and estimates suggest up to 15% of the general U.S. population may be affected. This research sought to assess a potential role for receptors for advanced glycation end-products (RAGE), an inflammatory receptor expressed in tissues exposed to secondhand smoke (SHS). Human sinus tissue sections were stained for RAGE and S100s, common RAGE ligands. Wild-type mice and mice that over-express RAGE in sinonasal epithelium (RAGE TG) were maintained in room air (RA) or exposed to secondhand smoke (SHS) via a nose-only delivery system five days a week for 6 weeks. Mouse sections were stained for RAGE and tissue lysates were assayed for cleaved caspase 3, cytokines, or matrix metalloproteases. We discovered increased RAGE expression in sinus tissue following SHS exposure and in sinuses from RAGE TG mice in the absence of SHS. Cleaved caspase-3, cytokines (IL-1β, IL-3, and TNF-α), and MMPs (-9 and -13) were induced by SHS and in tissues from RAGE TG mice. These results expand the inflammatory role of RAGE signaling, a key axis in disease progression observed in smokers. In this relatively unexplored area, enhanced understanding of RAGE signaling during voluntary and involuntary smoking may help to elucidate potential therapeutic targets that may attenuate the progression of smoke-related CS.

Biological and clinical significance of the AGE-RAGE axis in the aggressiveness and prognosis of prostate cancer.

Dietary factors and chronic hyperglycemia are linked to the formation of advanced glycation end products (AGEs) and prostate cancer (PCa) risk. The activation of the receptor for AGEs (RAGE) acts as a bridge between various RAGE ligands and certain malignancies. This study showed that the interaction of AGEs and RAGE promoted PCa cell proliferation, invasion, and autophagy-mediated survival in response to chemotherapeutic agents. RAGE-overexpressed PCa cells underwent epithelial-mesenchymal transition and showed increased cancer stem cell-like properties. In mouse xenograft models, RAGE-overexpressed cells showed more substantial tumorigenic capacity than parental cells, whereas RAGE knockdown decreased tumorigenicity. The clinical data validated a positive correlation between high AGE and RAGE expressions with poor clinical outcomes. Our findings suggest that the AGE-RAGE axis facilitates PCa progression and aggressiveness. Prostatic AGEs and RAGE expression levels are associated with PCa prognosis. Adherence to a reduced-AGE diet and targeting RAGE are potential approaches to complement and synergize with the current PCa therapies.

Modulating the RAGE-Induced Inflammatory Response: Peptoids as RAGE Antagonists.

While the primary pathology of Alzheimer's disease (AD) is defined by brain deposition of amyloid-β (Aβ) plaques and tau neurofibrillary tangles, chronic inflammation has emerged as an important factor in AD etiology. Upregulated cell surface expression of the receptor for advanced glycation end-products (RAGE), a key receptor of innate immune response, is reported in AD. In parallel, RAGE ligands, including Aβ aggregates, HMGB1, and S100B, are elevated in AD brain. Activation of RAGE by these ligands triggers release of inflammatory cytokines and upregulates cell surface RAGE. Despite such observation, there are currently no therapeutics that target RAGE for treatment of AD-associated neuroinflammation. Peptoids, a novel class of potential AD therapeutics, display low toxicity, facile blood-brain barrier permeability, and resistance to proteolytic degradation. In the current study, peptoids were designed to mimic Aβ, a ligand that binds the V-domain of RAGE, and curtail RAGE inflammatory activation. We reveal the nanomolar binding capability of peptoids JPT1 and JPT1a to RAGE and demonstrate their ability to attenuate lipopolysaccharide-induced pro-inflammatory cytokine production as well as upregulation of RAGE cell surface expression. These results support RAGE antagonist peptoid-based mimics as a prospective therapeutic strategy to counter neuroinflammation in AD and other neurodegenerative diseases.

Soluble RAGE and skeletal muscle tissue RAGE expression profiles in lean and obese young adults across differential aerobic exercise intensities.

Nearly 40% of Americans have obesity and are at increased risk for developing type 2 diabetes. Skeletal muscle is responsible for >80% of insulin-stimulated glucose uptake that is attenuated by the inflammatory milieu of obesity and augmented by aerobic exercise. The receptor for advanced glycation endproducts (RAGE) is an inflammatory receptor directly linking metabolic dysfunction with inflammation. Circulating soluble isoforms of RAGE (sRAGE) formed either by proteolytic cleavage (cRAGE) or alternative splicing (esRAGE) act as decoys for RAGE ligands, thereby counteracting RAGE-mediated inflammation. We aimed to determine if RAGE expression or alternative splicing of RAGE is altered by obesity in muscle, and whether acute aerobic exercise (AE) modifies RAGE and sRAGE. Young (20-34 yr) participants without [n = 17; body mass index (BMI): 22.6 ± 2.6 kg/m2] and with obesity (n = 7; BMI: 32.8 ± 2.9 kg/m2) performed acute aerobic exercise (AE) at 40%, 65%, or 80% of maximal aerobic capacity (V̇o2max; mL/kg/min) on separate visits. Blood was taken before and 30 min after each AE bout. Muscle biopsy samples were taken before, 30 min, and 3 h after the 80% V̇o2max AE bout. Individuals with obesity had higher total RAGE and esRAGE mRNA and RAGE protein (P < 0.0001). In addition, RAGE and esRAGE transcripts correlated to transcripts of the NF-κB subunit P65 (P < 0.05). There was no effect of AE on total RAGE or esRAGE transcripts, or RAGE protein (P > 0.05), and AE tended to decrease circulating sRAGE in particular at lower intensities of exercise. RAGE expression is exacerbated in skeletal muscle with obesity, which may contribute to muscle inflammation via NF-κB. Future work should investigate the consequences of increased skeletal muscle RAGE on the development of obesity-related metabolic dysfunction and potential mitigating strategies.NEW & NOTEWORTHY This study is the first to investigate the effects of aerobic exercise intensity on circulating sRAGE isoforms, muscle RAGE protein, and muscle RAGE splicing. sRAGE isoforms tended to diminish with exercise, although this effect was attenuated with increasing exercise intensity. Muscle RAGE protein and gene expression were unaffected by exercise. However, individuals with obesity displayed nearly twofold higher muscle RAGE protein and gene expression, which positively correlated with expression of the P65 subunit of NF-κB.

A preclinical study to evaluate the combination of azeliragon, an inhibitor of the receptor for advanced glycation endproducts (RAGE), with radiation therapy as a potential treatment of glioblastoma.

e14056 Background: Systemic lymphopenia, which is independently associated with poor overall survival, is observed in approximately 30-50% of patients with glioblastoma (GBM) after chemoradiotherapy. We recently found that cranial irradiation of GBM tumors increases circulating myeloid-derived suppressor cells (MDSC) contributing to systemic lymphopenia. Additionally, we found that cranial radiation increases circulating levels of the RAGE ligands S100A8/9 and HMGB1, which have been reported to increase MDSC and their immunosuppressive effects through binding RAGE. We, therefore, hypothesized that targeting RAGE receptors on MDSC could prevent immunosuppression and improve survival in preclinical GBM models. Methods: We orthotopically implanted GBM cells (GL261 and CT2A) into immunocompetent C57BL6 mice. The GBM tumor-bearing mice were treated with five doses of fractionated radiation therapy (RT, 2 Gy/day for 5 consecutive days) to the whole head in combination with RAGE inhibitor azeliragon (0.1mg/mice/day i.p starting one day before RT for up to 10 days). We evaluated the immune cells in the tumor microenvironment (TME) and spleen at 14 days post-tumor implantation. We also evaluated the circulating immune cells and RAGE ligands (HMGB1 and S100A8/A9) in the plasma at 7, 14, and 21 days post-tumor implantation and monitored the mice for survival up to 60 days. Results: GBM tumor-bearing mice (GL261 &amp; CT2A) treated with RT plus azeliragon had significantly improved survival when compared to RT alone or azeliragon alone. RT plus azeliragon significantly reduced the accumulation of granulocytic-MDSC (G-MDSC), monocytic-MDSC (M-MDSC), tumor-associated macrophages (TAM), and regulatory T cells (Treg), while increasing infiltrating CD8 T cells in the TME as compared to RT alone. RT alone significantly increased the accumulation of G-MDSC and M-MDSC in the spleen, which was significantly reduced with concurrent azeliragon. Concurrent administration of azeliragon with RT did not significantly affect the radiation-induced increase of circulating M-MDSC as well as plasma HMGB1 and S100A8/A9 concentration, though there was a modest reduction of circulating G-MDSC. Conclusions: Our study indicates that azeliragon, by blocking RAGE interaction with its ligands, helps to overcome the MDSC-mediated immunosuppression that occurs after RT. The combination of azeliragon with RT enhances survival in preclinical models. Clinical trials evaluating the safety and efficacy of azeliragon in combination with RT for newly diagnosed GBM are currently under development.

Social Isolation Activates Dormant Mammary Tumors, and Modifies Inflammatory and Mitochondrial Metabolic Pathways in the Rat Mammary Gland.

Although multifactorial in origin, one of the most impactful consequences of social isolation is an increase in breast cancer mortality. How this happens is unknown, but many studies have shown that social isolation increases circulating inflammatory cytokines and impairs mitochondrial metabolism. Using a preclinical Sprague Dawley rat model of estrogen receptor-positive breast cancer, we investigated whether social isolation impairs the response to tamoxifen therapy and increases the risk of tumors emerging from dormancy, and thus their recurrence. We also studied which signaling pathways in the mammary glands may be affected by social isolation in tamoxifen treated rats, and whether an anti-inflammatory herbal mixture blocks the effects of social isolation. Social isolation increased the risk of dormant mammary tumor recurrence after tamoxifen therapy. The elevated recurrence risk was associated with changes in multiple signaling pathways including an upregulation of IL6/JAK/STAT3 signaling in the mammary glands and tumors and suppression of the mitochondrial oxidative phosphorylation (OXPHOS) pathway. In addition, social isolation increased the expression of receptor for advanced glycation end-products (RAGE), consistent with impaired insulin sensitivity and weight gain linked to social isolation. In socially isolated animals, the herbal product inhibited IL6/JAK/STAT3 signaling, upregulated OXPHOS signaling, suppressed the expression of RAGE ligands S100a8 and S100a9, and prevented the increase in recurrence of dormant mammary tumors. Increased breast cancer mortality among socially isolated survivors may be most effectively prevented by focusing on the period following the completion of hormone therapy using interventions that simultaneously target several different pathways including inflammatory and mitochondrial metabolism pathways.

Apoptosis-induced nuclear expulsion in tumor cells drives S100a4-mediated metastatic outgrowth through the RAGE pathway

Most tumor cells undergo apoptosis in circulation and at the metastatic organ sites due to host immune surveillance and a hostile microenvironment. It remains to be elucidated whether dying tumor cells have a direct effect on live tumor cells during the metastatic process and what the underlying mechanisms are. Here we report that apoptotic cancer cells enhance the metastatic outgrowth of surviving cells through Padi4-mediated nuclear expulsion. Tumor cell nuclear expulsion results in an extracellular DNA–protein complex that is enriched with receptor for advanced glycation endproducts (RAGE) ligands. The chromatin-bound RAGE ligand S100a4 activates RAGE receptors in neighboring surviving tumor cells, leading to Erk activation. In addition, we identified nuclear expulsion products in human patients with breast, bladder and lung cancer and a nuclear expulsion signature correlated with poor prognosis. Collectively, our study demonstrates how apoptotic cell death can enhance the metastatic outgrowth of neighboring live tumor cells.

Peptoids as potential therapeutics to reduce S100B-induced RAGE-associatedneuroinflammation in Alzheimer's disease.

Receptor for advanced glycation end-products (RAGE)-associated chronic neuroinflammation has been linked with Alzheimer's disease (AD) pathology. RAGE ligand S100B, which is elevated in AD brain, can induce release of inflammatory cytokines and upregulate RAGE. Consequently, targeting RAGE to reduce chronic inflammation represents a novel therapeutic strategy for AD. Peptoids are ideal potential AD therapeutics as they resist proteolytic degradation by repositioning side-chains from the α-carbon to the amide nitrogen and exhibit facile blood-brain barrier permeability. Peptoids designed to mimic RAGE ligands demonstrated strong binding affinity to RAGE in our previous studies. We hypothesize that these peptoids can attenuate S100B-induced activation of RAGE, thus reducing pro-inflammatory cytokine release associated with chronic neuroinflammation. Differentiated THP-1 macrophages were exposed to chronic low-levels of S100B to confirm upregulation of cytokine release. Macrophages were then treated with 0-50-μM peptoids (JPT1 or JPT1a) in the presence of S100B. To observe peptoid modulation of S100B-induced inflammation, cytokine analysis via immunoassay was performed using cell culture supernatants. Additionally, RAGE was incubated in the presence of 0-500-nM peptoid to achieve equilibrium. Unbound RAGE was quantified via modified ELISA to determine the binding affinity. S100B-treated THP-1 macrophages elicited anticipated inflammatory response evidenced by dose-dependent upregulation of cytokines. When THP-1 macrophages were incubated with peptoids and S100B, peptoids attenuated these S100B-induced inflammatory responses. Moreover, the peptoids demonstrated nanomolar binding affinity for RAGE. Peptoids modulate inflammatory responses induced by RAGE ligand S100B, including inflammatory cytokine release. These results implicate peptoids as a potential therapeutic agent for not only AD but also other inflammation-related illnesses. Because these peptoids have additionally exhibited the ability to modulate Aβ aggregation and transform the morphology of the aggregates formed, they may function as dual-target therapeutics for AD.

Role of advanced glycation end products on vascular smooth muscle cells under diabetic atherosclerosis.

Atherosclerosis (AS) is a chronic inflammatory disease and leading cause of cardiovascular diseases. The progression of AS is a multi-step process leading to high morbidity and mortality. Hyperglycemia, dyslipidemia, advanced glycation end products (AGEs), inflammation and insulin resistance which strictly involved in diabetes are closely related to the pathogenesis of AS. A growing number of studies have linked AGEs to AS. As one of the risk factors of cardiac metabolic diseases, dysfunction of VSMCs plays an important role in AS pathogenesis. AGEs are increased in diabetes, participate in the occurrence and progression of AS through multiple molecular mechanisms of vascular cell injury. As the main functional cells of vascular, vascular smooth muscle cells (VSMCs) play different roles in each stage of atherosclerotic lesions. The interaction between AGEs and receptor for AGEs (RAGE) accelerates AS by affecting the proliferation and migration of VSMCs. In addition, increasing researches have reported that AGEs promote osteogenic transformation and macrophage-like transformation of VSMCs, and affect the progression of AS through other aspects such as autophagy and cell cycle. In this review, we summarize the effect of AGEs on VSMCs in atherosclerotic plaque development and progression. We also discuss the AGEs that link AS and diabetes mellitus, including oxidative stress, inflammation, RAGE ligands, small noncoding RNAs.

Receptor for advanced glycation end-products (RAGE) mediates phagocytosis in nonprofessional phagocytes

In mammals, both professional phagocytes and nonprofessional phagocytes (NPPs) can perform phagocytosis. However, limited targets are phagocytosed by NPPs, and thus, the mechanism remains unclear. We find that spores of the yeast Saccharomyces cerevisiae are internalized efficiently by NPPs. Analyses of this phenomenon reveals that RNA fragments derived from cytosolic RNA species are attached to the spore wall, and these fragments serve as ligands to induce spore internalization. Furthermore, we show that a multiligand receptor, RAGE (receptor for advanced glycation end-products), mediates phagocytosis in NPPs. RAGE-mediated phagocytosis is not uniquely induced by spores but is an intrinsic mechanism by which NPPs internalize macromolecules containing RAGE ligands. In fact, artificial particles labeled with polynucleotides, HMGB1, or histone (but not bovine serum albumin) are internalized in NPPs. Our findings provide insight into the molecular basis of phagocytosis by NPPs, a process by which a variety of macromolecules are targeted for internalization.

RAGE pathway activation and function in chronic kidney disease and COVID-19.

The multi-ligand receptor for advanced glycation end-products (RAGE) and its ligands are contributing factors in autoimmunity, cancers, and infectious disease. RAGE activation is increased in chronic kidney disease (CKD) and coronavirus disease 2019 (COVID-19). CKD may increase the risk of COVID-19 severity and may also develop in the form of long COVID. RAGE is expressed in essentially all kidney cell types. Increased production of RAGE isoforms and RAGE ligands during CKD and COVID-19 promotes RAGE activity. The downstream effects include cellular dysfunction, tissue injury, fibrosis, and inflammation, which in turn contribute to a decline in kidney function, hypertension, thrombotic disorders, and cognitive impairment. In this review, we discuss the forms and mechanisms of RAGE and RAGE ligands in the kidney and COVID-19. Because various small molecules antagonize RAGE activity in animal models, targeting RAGE, its co-receptors, or its ligands may offer novel therapeutic approaches to slowing or halting progressive kidney disease, for which current therapies are often inadequate.

Renal denervation reduces atrial remodeling in hypertensive rats with metabolic syndrome

Atrial fibrillation (AF) is highly prevalent in hypertensive patients with metabolic syndrome and is related to inflammation and activation of the sympathoadrenergic system. The multi-ligand Receptor-for-Advanced-Glycation-End-products (RAGE) activates inflammation-associated tissue remodeling and is regulated by the sympathetic nervous system. Its counterpart, soluble RAGE (sRAGE), serves as anti-inflammatory decoy receptor with protective properties. We investigated the effect of sympathetic modulation by renal denervation (RDN) on atrial remodeling, RAGE/sRAGE and RAGE ligands in metabolic syndrome. RDN was performed in spontaneously hypertensive obese rats (SHRob) with metabolic syndrome compared with lean spontaneously hypertensive rats (SHR) and with normotensive non-obese control rats. Blood pressure and heart rate were measured by telemetry. The animals were killed 12 weeks after RDN. Left atrial (LA) and right atrial (RA) remodeling was assessed by histological analysis and collagen types. Sympathetic innervation was measured by tyrosine hydroxylase staining of atrial nerve fibers, RAGE/sRAGE, RAGE ligands, cytokine expressions and inflammatory infiltrates were analyzed by Western blot and immunofluorescence staining. LA sympathetic nerve fiber density was higher in SHRob (+44%) versus controls and reduced after RDN (-64% versus SHRob). RAGE was increased (+718%) and sRAGE decreased (− 62%) in SHRob as compared with controls. RDN reduced RAGE expression (− 61% versus SHRob), significantly increased sRAGE levels (+162%) and induced a significant decrease in RAGE ligand levels in SHRob (− 57% CML and − 51% HMGB1) with reduced pro-inflammatory NFkB activation (− 96%), IL-6 production (− 55%) and reduced inflammatory infiltrates. This led to a reduction in atrial fibrosis (− 33%), collagen type I content (− 72%), accompanied by reduced LA myocyte hypertrophy (− 21%). Transfection experiments on H9C2 cardiomyoblasts demonstrated that RAGE is directly involved in fibrosis formation by influencing cellular production of collagen type I. In conclusion, suppression of renal sympathetic nerve activity by RDN prevents atrial remodeling in metabolic syndrome by reducing atrial sympathetic innervation and by modulating RAGE/sRAGE balance and reducing pro-inflammatory and pro-fibrotic RAGE ligands, which provides a potential therapeutic mechanism to reduce the development of AF.

Role of High Mobility Group Box 1 and Receptor for Advanced Glycation End Products in the Periodontal Disease Pathogenesis- A Review

Periodontitis is a multifactorial chronic inflammatory disease associated with increased secretion of several proinflammatory mediators such as Interleukin-1β (IL-1β), Interleukin-6 (IL-6), Interleukin-17 (IL-17), Tumour Necrosis Factor-α (TNF-α), Prostaglandins (PGs) in response to increased bacterial load on the tooth surface and within the gingival sulcus leading to the destruction of both hard and soft tissue of the periodontium. The Receptor for Advanced Glycation End-products (RAGE) binds multiple ligands, has a transmembrane configuration and is a part of the immunoglobulin receptor family. In healthy individuals RAGE is expressed at lower levels when compared to those with periodontitis and diabetes mellitus. Binding of RAGE to its ligands plays a key role in the inflammatory reactions that lead to disruption of a multitude of cellular processes. One such RAGE ligand involved in inducing hyperinflammatory phenotype is High Mobility Group Box 1 (HMGB1). HMGB1 is a chromatin binding protein predominantly localised in the nucleus and is associated with multiple functions such as Deoxyribonucleic Acid (DNA) repair, nuclear homeostasis, genome stability. In the presence of stressors, it migrates extracellularly and behaves like a Damage Associated Molecular Pattern (DAMP), has chemokine and cytokine activity. Extracellular HMGB1 binds to Toll Like Receptors (TLR)- 2,4 and RAGE, the HMGB1-RAGE interaction in particular has been associated with hyper inflammatory responses and currently hypothesised to be a bigger player in the pathogenesis of periodontitis as well as diabetes associated periodontitis. Therefore, understanding thoroughly the molecular mechanisms driving the tissue destruction in periodontal disease will effectively enable novel therapeutic drug based interventions based on interrupting the HMGB1-RAGE axis which in turn could mitigate the inflammation mediated tissue destruction.

LL-37 and HMGB1 induce alveolar damage and reduce lung tissue regeneration via RAGE.

The receptor for advanced glycation end-products (RAGE) has been implicated in the pathophysiology of chronic obstructive pulmonary disease (COPD). However, it is still unknown whether RAGE directly contributes to alveolar epithelial damage and abnormal repair responses. We hypothesize that RAGE activation not only induces lung tissue damage but also hampers alveolar epithelial repair responses. The effects of the RAGE ligands LL-37 and HMGB1 were examined on airway inflammation and alveolar tissue damage in wild-type and RAGE-deficient mice and on lung damage and repair responses using murine precision cut lung slices (PCLS) and organoids. In addition, their effects were studied on the repair response of human alveolar epithelial A549 cells, using siRNA knockdown of RAGE and treatment with the RAGE inhibitor FPS-ZM1. We observed that intranasal installation of LL-37 and HMGB1 induces RAGE-dependent inflammation and severe alveolar tissue damage in mice within 6 h, with stronger effects in a mouse strain susceptible for emphysema compared with a nonsusceptible strain. In PCLS, RAGE inhibition reduced the recovery from elastase-induced alveolar tissue damage. In organoids, RAGE ligands reduced the organoid-forming efficiency and epithelial differentiation into pneumocyte-organoids. Finally, in A549 cells, we confirmed the role of RAGE in impaired repair responses upon exposure to LL-37. Together, our data indicate that activation of RAGE by its ligands LL-37 and HMGB1 induces acute lung tissue damage and that this impedes alveolar epithelial repair, illustrating the therapeutic potential of RAGE inhibitors for lung tissue repair in emphysema.

Cigarette Smoke Condensate Exposure Induces Receptor for Advanced Glycation End-Products (RAGE)-Dependent Sterile Inflammation in Amniotic Epithelial Cells.

Maternal smoking is a risk factor of preterm prelabor rupture of the fetal membranes (pPROM), which is responsible for 30% of preterm births worldwide. Cigarettes induce oxidative stress and inflammation, mechanisms both implicated in fetal membranes (FM) weakening. We hypothesized that the receptor for advanced glycation end-products (RAGE) and its ligands can result in cigarette-dependent inflammation. FM explants and amniotic epithelial cells (AECs) were treated with cigarette smoke condensate (CSC), combined or not with RAGE antagonist peptide (RAP), an inhibitor of RAGE. Cell suffering was evaluated by measuring lactate dehydrogenase (LDH) medium-release. Extracellular HMGB1 (a RAGE ligand) release by amnion and choriodecidua explants were checked by western blot. NF-κB pathway induction was determined by a luciferase gene reporter assay, and inflammation was evaluated by cytokine RT-qPCR and protein quantification. Gelatinase activity was assessed using a specific assay. CSC induced cell suffering and HMGB1 secretion only in the amnion, which is directly associated with a RAGE-dependent response. CSC also affected AECs by inducing inflammation (cytokine release and NFκB activation) and gelatinase activity through RAGE engagement, which was linked to an increase in extracellular matrix degradation. This RAGE dependent CSC-induced inflammation associated with an increase of gelatinase activity could explain a pathological FM weakening directly linked to pPROM.

Increased Levels of Soluble RAGE in CLL Patient Plasma Has a Protective Effect on CLL Disease Progression

Background: Receptor for advanced glycation end-products (RAGE) is the primary receptor for the inflammatory molecule HMGB1. We previously demonstrated that HMGB1 differentiates nurse like cells (NLC), and that increased levels HMGB1 in the plasma of CLL patients and overexpression of RAGE in CLL lymph nodes is associated with a poorer clinical outcome. Moreover, we have shown that HMGB1 induced activation of NF-κB in primary CLL cells in vitro . Soluble RAGE (sRAGE) is a reported antagonistic decoy receptor of plasma HMGB1, and limits chronic inflammation. The pool of plasma sRAGE originates from 2 main sources - alternative splicing to produce endogenous secreted RAGE (esRAGE), or from surface RAGE ectodomain shedding catalyzed by ADAM10. In a healthy setting, HMGB1 and sRAGE plasma levels are inversely correlated, with increased levels of sRAGE limiting inflammatory responses. RAGE shedding in response to saturating levels of ligand (i.e. HMGB1) establishes a negative feedback loop, dampening inflammatory signaling by sequestering RAGE ligands. In chronic disease, the HMGB1-sRAGE inverse relationship is frequently reversed. The functional impact of sRAGE is poorly documented in cancer, and its role in CLL is currently unknown.We hypothesize that sRAGE could have a protective effect in CLL and could dampen HMGB1-mediated disease progression. The aim of this study is to characterise the clinical significance of sRAGE in CLL and investigate whether RAGE undergoes membrane shedding to confer a protective effect in CLL.Methods: sRAGE plasma levels were measured by ELISA in 54 CLL patients and 15 healthy controls. sRAGE protein mass was assessed by Western blotting and compared to matched patient ADAM10 whole cell expression. ADAM10 inhibitor studies and HMGB1-induced RAGE shedding was performed in RAGE-transfected HEK293 cell line and primary CLL cells; sRAGE production was analyzed by ELISA and surface RAGE expression determined by flow cytometry. sRAGE containing media was produced by HEK293 cell line transfected with esRAGE isoform gene sequence; sRAGE containing media (2ng/ml) was used to assess the effect on primary CLL NLC differentiation.Results: sRAGE plasma levels were significantly higher in CLL patients compared to healthy controls (median 60.0pg/ml ± 79.5 interquartile range and 31.0pg/ml ±46.9, respectively; P <0.01), but fell below levels capable of full HMGB1 inhibition for the same patient cohort (72.2ng/ml ±111.4). Absence of a negative correlation between HMGB1 and sRAGE suggested a breakdown in the negative feedback loop in CLL, compared to the classical inverse trend observed for the healthy controls. Patients with high levels of plasma sRAGE had an increased time to first treatment (P=0.0134; n=26) and sRAGE levels were increased in patients who had reached remission following treatment compared to pre-treatment samples, suggesting that sRAGE provides a protective effect on CLL disease progression.CLL plasma sRAGE is of shorter length than cellular full-length RAGE and esRAGE from primary CLL cells, suggesting sRAGE originates from ectodomain shedding. ADAM10 expression, the main RAGE sheddase, is independent of sRAGE plasma levels assessed by Western blotting. ADAM10 stimulation with ionomycin induced RAGE ectodomain shedding into cell culture medium in RAGE-transfected HEK293 cell line (2270.0ng/ml) compared to untreated cells, without altering surface RAGE or ADAM10 expression. Ionomycin-induced RAGE shedding was abrogated by pre-treatment with ADAM10 inhibitor, GI254023X (45.5ng/ml). Ionomycin induced apoptosis in primary CLL cells, so could not be investigated for RAGE shedding, but our data demonstrates that saturating HMGB1 levels induces RAGE shedding in CLL. Finally, sRAGE-containing media did not reduce primary CLL NLC differentiation in vitro after 1-2 weeks culture.Conclusions: Our data demonstrates for the first time that plasma sRAGE limits CLL disease progression by prolonging time to first treatment and sustaining stable disease following treatment. sRAGE originates from ectodomain shedding, is dependent on ADAM10 and inducible by HMGB1. Although sRAGE failed to block NLC differentiation in vitro, it contributes to the extracellular mileu ‘cocktail’ shaping the CLL microenvironment. We therefore propose that HMGB1 and sRAGE levels could be useful plasma markers for inflammatory microenvironment and therapy monitoring. DisclosuresGribben:Acerta: Honoraria; Pharmacyclics: Honoraria; Celgene: Honoraria; TG Therapeutics: Honoraria; Karyopharm: Honoraria; Janssen: Honoraria; Kite: Honoraria; Abbvie: Honoraria; Genentech/Roche: Honoraria.

RAGE-MEDIATED CELLULAR SIGNALING IS TRIGGERED BY THE ALLOSTERIC ACTIVATION OF THE AT1 RECEPTOR

Objective: We recently identified the physical interaction of a pattern recognition receptor (PRR), lectin-like oxidized LDL receptor with the GPCR, angiotensin II type 1 receptor (AT1) whereby oxLDL allosterically activates AT1. In this study, we investigated if AT1 physically interacts with another PRR, the receptor for AGE (RAGE), and ligands of RAGE could allosterically activate AT1. Design and method: We used normal rat kidney epithelial cells (NRK52E) to investigate the interaction of the endogenous receptors. We also generated five different genetically-engineered CHO cells to individually analyze the G protein and β-arrestin pathways of AT1 activation; CHO cells expressing human RAGE (CHO-RAGE), CHO cells expressing both hRAGE and hAT1 (CHO-RAGE-AT1), CHO cells expressing both hRAGE and mutated hAT1 with impaired ability to activate G protein, and CHO cells expressing both hLOX-1 and mutated hAT1 with impaired ability to activate β-arrestin Results: In NRK52E, AGE-BSA provoked the activation of MAP kinase (ERK) that was inhibited by ARB or siRNA of AT1 or RAGE. Activation of NfκB and Epithelial mesanchmal transition induced by AGE-BSA was inhibited by ARBs as well as RAGE inhibitor. In genetically engineered CHO-cells, in situ PLA assay and immunoprecipitation confirmed the physical interaction of AT1 and RAGE on cellular membrane. HMGB1, a RAGE ligand induced Gαi-dependent inhibition of cAMP production only in the presence of both RAGE and AT1 with intact G protein binding. The effect of HMGB1 on cAMP content was abolished by ARB as well as RAGE inhibitor. HMGB1 did not induce the accumulation of IP1, a downstream of Gαq signaling, in CHO cells expressing both AT1 and RAGE. Real-time imaging of cellular membrane revealed that RAGE induced endocytosis of LOX-1 that depends on the intact β-arrestin pathway of AT1, and the phenomenon was not inhibited by ARB. Conclusions: RAGE ligands mediates cellular signaling via a physical interaction between RAGE and AT1. The activation of AT1 by RAGE ligands is distinct from that by angiotensin II in terms of selective G protein activation and the effect of ARB on G protein pathway but not on β-arrestin pathway.