RAGE signaling in inflammation and arterial aging

Extracellular vesicle encapsulated Homer1a as novel nanotherapeutics against intracerebral hemorrhage in a mouse model

Homer1a and A2 astrocytes are involved in the regulation of inflammation induced by intracerebral hemorrhage (ICH). However, there is no anticipated treatment strategy based on the anti-inflammatory effect of Homer1a and A2 astrocytes. Here, we successfully induced A2 astrocytes in vitro, and then we report an efficient method to prepare Homer1a+ EVs derived from A2 astrocytes which making it more stable, safe, and targetable to injured neurons. Homer1a+ EVs promotes the conversion of A1 to A2 astrocytes in ICH mice. Homer1a+ EVs inhibits activation and nuclear translocation of NF-κB, thereby regulating transcription of IL-17A in neurons. Homer1a+ EVs inhibits the RAGE/NF-κB/IL-17 signaling pathway and the binding ability of IL-17A: IL17-AR and RAGE: DIAPH1. In addition, Homer1a+ EVs ameliorates the pathology, behavior, and survival rate in GFAPCreHomer1fl/-Homer1a± and NestinCreRAGEfl/fl ICH mice. Our study provides a novel insight and potential for the clinical translation of Homer1a+ EVs in the treatment of ICH.

Effects of Hydrocodone Overdose and Ceftriaxone on Astrocytic Glutamate Transporters and Glutamate Receptors, and Associated Signaling in Nucleus Accumbens as well as Locomotor Activity in C57/BL Mice

Chronic opioid treatments dysregulate the glutamatergic system, inducing a hyperglutamatergic state in mesocorticolimbic brain regions. This study investigated the effects of exposure to hydrocodone overdose on locomotor activity, expression of target proteins related to the glutamatergic system, signaling kinases, and neuroinflammatory factors in the nucleus accumbens. The locomotor activity of mice was measured using the Comprehensive Laboratory Animal Monitoring System (CLAMS). CLAMS data showed that exposure to hydrocodone overdose increased locomotion activity in mice. This study tested ceftriaxone, known to upregulate major glutamate transporter 1 (GLT-1), in mice exposed to an overdose of hydrocodone. Thus, ceftriaxone normalized hydrocodone-induced hyperlocomotion activity in mice. Furthermore, exposure to hydrocodone overdose downregulated GLT-1, cystine/glutamate antiporter (xCT), and extracellular signal-regulated kinase activity (p-ERK/ERK) expression in the nucleus accumbens. However, exposure to an overdose of hydrocodone increased metabotropic glutamate receptor 5 (mGluR5), neuronal nitric oxide synthase activity (p-nNOS/nNOS), and receptor for advanced glycation end products (RAGE) expression in the nucleus accumbens. Importantly, ceftriaxone treatment attenuated hydrocodone-induced upregulation of mGluR5, p-nNOS/nNOS, and RAGE, as well as hydrocodone-induced downregulation of GLT-1, xCT, and p-ERK/ERK expression. These data demonstrated that exposure to hydrocodone overdose can cause dysregulation of the glutamatergic system, neuroinflammation, hyperlocomotion activity, and the potential therapeutic role of ceftriaxone in attenuating these effects.

Vitamin D supplementation modulates glycated hemoglobin (HBA1c) in diabetes mellitus

Diabetes is a metabolic illness that increases protein glycosylation in hyperglycemic conditions, which can have an impact on almost every organ system in the body. The role of vitamin D in the etiology of diabetes under RAGE (receptor for advanced glycation end products) stress has recently received some attention on a global scale. Vitamin D's other skeletal benefits have generated a great deal of research. Vitamin D's function in the development of type 1 and type 2 diabetes is supported by the discovery of 1,25 (OH)2D3 and 1-Alpha-Hydroylase expression in immune cells, pancreatic beta cells, and several other organs besides the bone system. A lower HBA1c level, metabolic syndrome, and diabetes mellitus all seems to be associated with vitamin D insufficiency. Most of the cross-sectional and prospective observational studies that were used to gather human evidence revealed an inverse relationship between vitamin D level and the prevalence or incidence of elevated HBA1c in type 2 diabetes. Several trials have reported on the impact of vitamin D supplementation for glycemia or incidence of type 2 diabetes, with varying degrees of success. The current paper examines the available data for a relationship between vitamin D supplementation and HBA1c level in diabetes and discusses the biological plausibility of such a relationship.

Molecular pathways of NF-ĸB and NLRP3 inflammasome as potential targets in the treatment of inflammation in diabetic wounds: A review

Diabetic wounds are slow healing wounds characterized by disordered healing processes and frequently take longer than three months to heal. One of the defining characteristics of impaired diabetic wound healing is an abnormal and unresolved inflammatory response, which is primarily brought on by abnormal macrophage innate immune signaling activation. The persistent inflammatory state in a diabetic wound may be attributed to inflammatory pathways such as nuclear factor kappa B (NF-ĸB) and nod-like receptor family pyrin domain-containing 3 (NLRP3) inflammasome, which have long been associated with inflammatory diseases. Despite the available treatments for diabetic foot ulcers (DFUs) that include debridement, growth factor therapy, and topical anti-bacterial agents, successful wound healing is still hampered. Further understanding of the molecular mechanism of these pathways could be useful in designing potential therapeutic targets for diabetic wound healing. This review provides an update and novel insights into the roles of NF-ĸB and NLRP3 pathways in the molecular mechanism of diabetic wound inflammation and their potential as therapeutic targets in diabetic wound healing.

Pharmacological modulation of vascular ageing: A review from VascAgeNet

Vascular ageing, characterized by structural and functional changes in blood vessels of which arterial stiffness and endothelial dysfunction are key components, is associated with increased risk of cardiovascular and other age-related diseases. As the global population continues to age, understanding the underlying mechanisms and developing effective therapeutic interventions to mitigate vascular ageing becomes crucial for improving cardiovascular health outcomes. Therefore, this review provides an overview of the current knowledge on pharmacological modulation of vascular ageing, highlighting key strategies and promising therapeutic targets. Several molecular pathways have been identified as central players in vascular ageing, including oxidative stress and inflammation, the renin-angiotensin-aldosterone system, cellular senescence, macroautophagy, extracellular matrix remodelling, calcification, and gasotransmitter-related signalling. Pharmacological and dietary interventions targeting these pathways have shown potential in ameliorating age-related vascular changes. Nevertheless, the development and application of drugs targeting vascular ageing is complicated by various inherent challenges and limitations, such as certain preclinical methodological considerations, interactions with exercise training and sex/gender-related differences, which should be taken into account. Overall, pharmacological modulation of endothelial dysfunction and arterial stiffness as hallmarks of vascular ageing, holds great promise for improving cardiovascular health in the ageing population. Nonetheless, further research is needed to fully elucidate the underlying mechanisms and optimize the efficacy and safety of these interventions for clinical translation.

Discovery of Potential RAGE inhibitors using Receptor-Based Pharmacophore Modeling, High Throughput Virtual Screening and Docking Studies

Receptor for Advanced Glycation End products (RAGE) is a transmembrane receptor that can bind to various endogenous and exogenous ligands and initiate the inflammatory downstream signaling pathways. So far RAGE has been involved in various disorders including cardiovascular and neurodegenerative diseases, cancer, and diabetes. Blocking the interactions between RAGE and its ligands is a therapeutic approach to treat these conditions. In this context, we effectively utilized the receptor-based-pharmacophore modeling to discover structurally diverse molecular compounds having potential to effectively bind with RAGE. Two pharmacophore models were developed on V-domain of RAGE using Phase application of Schrodinger suite. The developed pharmacophoric features were used for screening of 1.8 million drug-like molecules downloaded from ChEMBL database. The molecules were scrutinized according to their molecular weight as well as clogP values. Phase screening was performed to find out the molecules that matched the developed pharmacophoric features that were further selected to analyze their binding modes using high-throughput virtual screening, extra precision docking studies and MM-GBSA ΔG binding calculations. These analyses provided ten hit RAGE inhibitory molecules that can bind to two different shallow binding sites on the V-domain of RAGE. Among the obtained compounds two compounds ChEMBL501494 and ChEMBL4081874 were found with best binding free energies that proved their receptor-ligand complex stability within their respective binding cavity on RAGE. Therefore, these molecules could be utilized for further designing and optimizing the future class of potential RAGE inhibitors.

IL-34 exacerbates pathogenic features of Alzheimer's disease and calvaria osteolysis in triple transgenic (3x-Tg) female mice

Hallmark features of Alzheimer's disease (AD) include elevated accumulation of aggregated Aβ40 and Aβ42 peptides, hyperphosphorylated Tau (p-Tau), and neuroinflammation. Emerging evidence indicated that interleukin-34 (IL-34) contributes to AD and inflammatory osteolysis via the colony-stimulating factor-1 receptor (CSF-1r). In addition, CSF-1r is also activated by macrophage colony-stimulating factor-1 (M-CSF). While the role of M-CSF in bone physiology and pathology is well addressed, it remains controversial whether IL-34-mediated signaling promotes osteolysis, neurodegeneration, and neuroinflammation in relation to AD. In this study, we injected 3x-Tg mice with mouse recombinant IL-34 protein over the calvaria bone every other day for 42 days. Then, behavioral changes, brain pathology, and calvaria osteolysis were evaluated using various behavioral maze and histological assays. We demonstrated that IL-34 administration dramatically elevated AD-like anxiety and memory loss, pathogenic amyloidogenesis, p-Tau, and RAGE expression in female 3x-Tg mice. Furthermore, IL-34 delivery promoted calvaria inflammatory osteolysis compared to the control group. In addition, we also compared the effects of IL-34 and M-CSF on macrophages, microglia, and RANKL-mediated osteoclastogenesis in relation to AD pathology in vitro. We observed that IL-34-exposed SIM-A9 microglia and 3x-Tg bone marrow-derived macrophages released significantly elevated amounts of pro-inflammatory cytokines, TNF-α, IL-1β, and IL-6, compared to M-CSF treatment in vitro. Furthermore, IL-34, but not M-CSF, elevated RANKL-primed osteoclastogenesis in the presence of Aβ40 and Aβ42 peptides in bone marrow derived macrophages isolated from female 3x-Tg mice. Collectively, our data indicated that IL-34 elevates AD-like features, including behavioral changes and neuroinflammation, as well as osteoclastogenesis in female 3x-Tg mice.

Exploring the molecular interactions and binding affinity of resveratrol and calcitriol with RAGE and its intracellular proteins and kinases involved in colorectal cancer

Colorectal cancer (CRC) burden is progressively increasing in young population due to dietary and lifestyle pattern. Advanced glycation end products (AGEs), one of the dietary compounds, form complex aggregates with proteins, lipids, and nucleic acids distorting their structure and function. AGE's pro-tumorigenic role is mediated through the receptor for AGEs (RAGE) triggering an array of signaling pathways. The current study aimed to target AGE-RAGE axis signaling proteins and kinases at multiple levels with calcitriol (CAL) and trans-resveratrol (RES) through in silico analysis using molecular docking (MD), molecular dynamic simulation(MDS), MM-PBSA analysis, and in vitro study. In silico analysis of CAL and RES showed significant binding affinity toward RAGE and its signaling proteins such as NF-kB, PI3K/AKT, ERK1/2, and PKC compared to its reference inhibitors through better hydrogen, hydrophobic, pi-pi stacking interactions. MD and MDS studies have revealed stable and compact protein-ligand complexes. Binding free energies of protein-ligand complex were estimated using MM/PBSA analysis thatprovided an assessment of overall interacting free energies of complexes and revealed the presence of low binding energy within the active site. Furthermore, in the in vitro study, methylglyoxal (MG), an AGE-precursor showed a proliferative effect on HCT116, however, CAL and RES showed an inhibitory effect against MG induced effect with an IC50 value of 51 nM and 110 µM respectively. Thus, the study suggests the possible target binding sites of AGE-RAGE signaling proteins and kinases with CAL and RES, thereby exploiting it for developing CAL with RES as adjuvant therapy along with chemo drug for CRC.Communicated by Ramaswamy H. Sarma.

The Effect of Free and Protein-Bound Maillard Reaction Products N-ε-Carboxymethyllysine, N-ε-Fructosyllysine, and Pyrraline on Nrf2 and NFκB in HCT 116 Cells

SCOPE

Maillard reaction products (MRPs) are believed to interact with the receptor for advanced glycation endproducts (RAGE) and lead to a pro-inflammatory cellular response. The structural basis for this interaction is scarcely understood. This study investigates the effect of individual lysine modifications in free form or bound to casein on human colon cancer cells.

METHODS AND RESULTS

Selectively glycated casein containing either protein-bound N-ε-carboxymethyllysine (CML), N-ε-fructosyllysine (FL), or pyrraline is prepared and up to 94%, 97%, and 61% of lysine modification could be attributed to CML, FL, or pyrraline, respectively. HCT 116 cells are treated with free CML, pyrraline, FL, or modified casein for 24 h. Native casein is used as control. Intracellular MRP content is analyzed by UPLC-MS/MS. Microscopic analysis of the transcription factors shows no activation of NFκB by free or protein-bound FL or CML, whereas casein containing protein-bound pyrraline activates Nrf2. RAGE expression is not influenced by free or casein-bound MRPs. Activation of Nrf2 by pyrraline-modified casein is confirmed by analyzing Nrf2 target proteins NAD(P)H dehydrogenase (quinone 1) (NQO1) and heme oxygenase-1 (HO-1).

CONCLUSION

Studies on the biological effects of glycated proteins require an individual consideration of defined structures. General statements on the effect of "AGEs" in biological systems are scientifically unsound.

Soluble receptors for advanced glycation end-products prevent unilateral ureteral obstruction-induced renal fibrosis

Introduction: The receptor for advanced glycation end products (RAGE) and its ligands, such as high-mobility group protein box 1 (HMGB1), play an important role in the accumulation of extracellular matrix in chronic kidney diseases with tubulointerstitial fibrosis. Blocking RAGE signaling with soluble RAGE (sRAGE) is a therapeutic candidate for renal fibrosis. Methods: NRK-52E cells were stimulated with or without HMGB1 and incubated with sRAGE in vitro. Sprague-Dawley rats were intraperitoneally treated with sRAGE after unilateral ureteral obstruction (UUO) operation in vivo. Results: HMBG1-stimulated NRK-52E cells showed increased fibronectin expression, type I collagen, α-smooth muscle actin, and connective tissue growth factor, which were attenuated by sRAGE. The mitogen-activated protein kinase (MAPK) pathway and nuclear translocation of nuclear factor kappa B (NF-κB) were enhanced in NRK-52E cells exposed to HMBG1, and sRAGE treatment alleviated the activation of the MAPK and NF-κB pathways. In the UUO rat models, sRAGE significantly ameliorated the increased renal fibronectin, type I collagen, and α-smooth muscle actin expressions. Masson's trichrome staining confirmed the anti-fibrotic effect of sRAGE in the UUO rat model. RAGE also significantly attenuated the activation of the MAPK pathway and NF-κB, as well as the increased number of infiltrated macrophages within the tubulointerstitium in the kidney of the UUO rat models. Conclusion: These findings suggest that RAGE plays a pivotal role in the pathogenesis of renal fibrosis and that its inhibition by sRAGE may be a potential therapeutic approach for renal fibrosis.

The Potential Influence of Advanced Glycation End Products and (s)RAGE in Rheumatic Diseases

Advanced glycation end products (AGEs) are a class of compounds formed by nonenzymatic interactions between reducing sugars and proteins, lipids, or nucleic acids. AGEs can alter the protein structure and activate one of their receptors, specifically the receptor for advanced glycation end products (RAGE). These phenomena impair the functions of cells, extracellular matrix, and tissues. RAGE is expressed by a variety of cells and has been linked to chronic inflammatory autoimmune disorders such as rheumatoid arthritis, systemic lupus erythematosus, and Sjögren's syndrome. The soluble (s)RAGE cleavage product is a positively charged 48-kDa cleavage product that retains the ligand binding site but loses the transmembrane and signaling domains. By acting as a decoy, this soluble receptor inhibits the pro-inflammatory processes mediated by RAGE and its ligands. In the present review, we will give an overview of the role of AGEs, sRAGE, and RAGE polymorphisms in several rheumatic diseases. AGE overproduction may play a role in the pathogenesis and is linked to accelerated atherosclerosis. Low serum sRAGE concentrations are linked to an increased cardiovascular risk profile and a poor prognosis. Some RAGE polymorphisms may be associated with increased disease susceptibility. Finally, sRAGE levels can be used to track disease progression.

Differential gene expression analysis of RAGE-S100A6 complex for target selection and the design of novel inhibitors for anticancer drug discovery

Receptor for advanced glycation end products (RAGE), a member of the immunoglobulin family, interactions with its ligands trigger downstream signaling and induce an inflammatory response linked to diabetes, inflammation, carcinogenesis, cardiovascular disease, and a variety of other human disorders. The interaction of RAGE and S100A6 has been associated with a variety of malignancies. For the control of RAGE-related illnesses, there is a great demand for more specialized drug options. To identify the most effective target for combating human malignancies associated with RAGE-S100A6 complex, we conducted single and differential gene expression analyses of S100A6 and RAGE, comparing normal and malignant tissues. Further, a structure-based virtual screening was conducted using the ZINC15 database. The chosen compounds were then subjected to a molecular docking investigation on the RAGE active site region, recognized by the various cancer-related RAGE ligands. An optimized RAGE structure was screened against a library of drug-like molecules. The screening results suggested that three promising compounds were presented as the top acceptable drug-like molecules with a high binding affinity at the RAGE V-domain catalytic region. We depicted that these compounds may be potential RAGE inhibitors and could be used to produce a successful medication against human cancer and other RAGE-related diseases based on their various assorted parameters, binding energy, hydrogen bonding, ADMET characteristics, etc. MD simulation on a time scale of 50 ns was used to test the stability of the RAGE-inhibitor complexes. Therefore, targeting RAGE and its ligands using these drug-like molecules may be an effective therapeutic approach.

Endothelial dysfunction and atherosclerosis related miRNA-expression in patients with haemophilia

INTRODUCTION

Elevated markers of endothelial dysfunction and inflammation indicate worse endothelial function in the aging haemophilia population. MicroRNAs (miRNAs) regulate gene expression post-transcriptionally. Several miRNAs have been shown to be involved in the process of endothelial dysfunction and atherosclerosis.

AIM

The aim of this study was to determine the underlying molecular pathways of endothelial dysfunction and inflammation in haemophilia patients.

METHODS

A total of 25 patients with severe or moderate haemophilia A (20 patients) or B (5 patients), 14 controls and 18 patients with coronary artery disease (CAD) after myocardial infarction were included in this study. Expression of miRNA-126, -155, -222, -1, -let7a, -21 and -197 were analysed using a real time polymerase chain reaction. Network-based visualisation and analysis of the miRNA-target interactions were performed using the MicroRNA ENrichment TURned NETwork (MIENTURNET).

RESULTS

Expression of miRNA-126 (p < .05) and miRNA-let7a (p < .05) were significantly higher in CAD patients compared to haemophilia patients and controls. MiRNA-21 (p < .05) was significantly elevated in CAD patients compared to controls. MiRNA-155 (p < .05), miRNA-1 (p < .05) and miRNA-197 (p < .05) were significantly higher expressed in CAD and haemophilia patients compared to controls and showed a strong correlation with increased levels of interleukin-6 (IL-6) and soluble intercellular adhesion molecule-1 (sICAM-1). The network analysis revealed interactions in the cytokine signalling, focal adhesion and VEGFA-VEGFR2 pathway (Vascular endothelial growth factor, -receptor).

CONCLUSION

This study characterises miRNA expression in haemophilia patients in comparison to CAD patients and healthy controls. The results imply comparable biological processes in CAD and haemophilia patients.

Therapeutic Potential of Targeting the HMGB1/RAGE Axis in Inflammatory Diseases

High mobility group box 1 (HMGB1) is a nuclear protein that can interact with a receptor for advanced glycation end-products (RAGE; a multi-ligand immunoglobulin receptor) and mediates the inflammatory pathways that lead to various pathological conditions, such as cancer, diabetes, neurodegenerative disorders, and cardiovascular diseases. Blocking the HMGB1/RAGE axis could be an effective therapeutic approach to treat these inflammatory conditions, which has been successfully employed by various research groups recently. In this article, we critically review the structural insights and functional mechanism of HMGB1 and RAGE to mediate inflammatory processes. More importantly, current perspectives of recent therapeutic approaches utilized to inhibit the communication between HMGB1 and RAGE using small molecules are also summarized along with their clinical progression to treat various inflammatory disorders. Encouraging results are reported by investigators focusing on HMGB1/RAGE signaling leading to the identification of compounds that could be useful in further clinical studies. We highlight the current gaps in our knowledge and future directions for the therapeutic potential of targeting key molecules in HMGB1/RAGE signaling in the pathophysiology of inflammatory diseases.

Methylglyoxal and Its Adducts: Induction, Repair, and Association with Disease

Metabolism is an essential part of life that provides energy for cell growth. During metabolic flux, reactive electrophiles are produced that covalently modify macromolecules, leading to detrimental cellular effects. Methylglyoxal (MG) is an abundant electrophile formed from lipid, protein, and glucose metabolism at intracellular levels of 1-4 μM. MG covalently modifies DNA, RNA, and protein, forming advanced glycation end products (MG-AGEs). MG and MG-AGEs are associated with the onset and progression of many pathologies including diabetes, cancer, and liver and kidney disease. Regulating MG and MG-AGEs is a potential strategy to prevent disease, and they may also have utility as biomarkers to predict disease risk, onset, and progression. Here, we review recent advances and knowledge surrounding MG, including its production and elimination, mechanisms of MG-AGEs formation, the physiological impact of MG and MG-AGEs in disease onset and progression, and the latter in the context of its receptor RAGE. We also discuss methods for measuring MG and MG-AGEs and their clinical application as prognostic biomarkers to allow for early detection and intervention prior to disease onset. Finally, we consider relevant clinical applications and current therapeutic strategies aimed at targeting MG, MG-AGEs, and RAGE to ultimately improve patient outcomes.

Inhibition of advanced glycation end product formation and serum protein infiltration in bioprosthetic heart valve leaflets: Investigations of anti-glycation agents and anticalcification interactions with ethanol pretreatment

Bioprosthetic heart valves (BHV) fabricated from heterograft tissue, such as glutaraldehyde pretreated bovine pericardium (BP), are the most frequently used heart valve replacements. BHV durability is limited by structural valve degeneration (SVD), mechanistically associated with calcification, advanced glycation end products (AGE), and serum protein infiltration. We investigated the hypothesis that anti-AGE agents, Aminoguanidine, Pyridoxamine [PYR], and N-Acetylcysteine could mitigate AGE-serum protein SVD mechanisms in vitro and in vivo, and that these agents could mitigate calcification or demonstrate anti-calcification interactions with BP pretreatment with ethanol. In vitro, each of these agents significantly inhibited AGE-serum protein infiltration in BP. However, in 28-day rat subdermal BP implants only orally administered PYR demonstrated significant inhibition of AGE and serum protein uptake. Furthermore, BP PYR preincubation of BP mitigated AGE-serum protein SVD mechanisms in vitro, and demonstrated mitigation of both AGE-serum protein uptake and reduced calcification in vivo in 28-day rat subdermal BP explants. Inhibition of BP calcification as well as inhibition of AGE-serum protein infiltration was observed in 28-day rat subdermal BP explants pretreated with ethanol followed by PYR preincubation. In conclusion, AGE-serum protein and calcification SVD pathophysiology are significantly mitigated by both PYR oral therapy and PYR and ethanol pretreatment of BP.

Interaction of RAGE with α-synuclein fibrils mediates inflammatory response of microglia

Microglia-mediated neuroinflammation and α-synuclein (α-syn) aggregation, both as pathological hallmarks of Parkinson's disease (PD), crosstalk to exacerbate degeneration of dopaminergic neurons and PD progression. However, the mechanism underlying their interaction is poorly understood, which obstructs effective therapeutic inhibition of α-syn-induced neuroinflammation. Here, we initiate from structure-based interaction predictions and find that receptor for advanced glycation end products (RAGE) serves as a receptor of α-syn fibrils on microglia. Results of nuclear magnetic resonance (NMR) spectroscopy and mutagenesis validate that the V domain of RAGE that contains an alkaline surface can bind with acidic C-terminal residues of α-syn. Furthermore, the binding of α-syn fibrils with RAGE induces neuroinflammation, which is blocked by both genetic depletion of RAGE and inhibitor FPS-ZM1. Our work shows the important role, as well as the structural mechanism, of RAGE in mediating the inflammatory response of microglia to α-syn fibrils, which may help to establish effective therapeutic strategies to alleviate α-syn-induced neuroinflammation and neuronal damage.

Elevated IgG and IgM Autoantibodies to Advanced Glycation End Products of Vascular Elastin in Hypertensive Patients with Type 2 Diabetes: Relevance to Disease Initiation and Progression

The increased glycation of elastin is an important factor in vascular changes in diabetes. Using the ELISA method, we determined serum levels of IgM and IgG autoantibodies to advanced glycation end products of vascular elastin (anti-AGE EL IgM and anti-AGE EL IgG) in 59 hypertensive patients with type 2 diabetes (T2D) and 20 healthy controls. Serum levels of matrix metalloproteinases-2 and -9 (MMP-2 and MMP-9) and the C-reactive protein (CRP) were also determined. The levels of anti-AGE EL IgM antibodies in the T2D group were similar to those in the control group, while those of anti-AGE EL IgG antibodies were significantly higher (p = 0.017). Significant positive correlations were found between the levels of anti-AGE EL IgM antibodies and MMP-2 (r = 0.322; p = 0.013) and between the levels of anti-AGE EL IgG antibodies and CRP (r = 0.265; p = 0.042). Our study showed that elevated anti-AGE EL IgG antibody levels may be an indicator of the enhanced AGE-modification and inflammatory-mediated destruction of vascular elastin in hypertensive patients with T2D. Anti-AGE EL IgM antibodies may reflect changes in vascular MMP-2 activity, and their elevated levels may be a sign of early vascular damage.

Therapeutic potential of targeting the receptor for advanced glycation end products (RAGE) by small molecule inhibitors

Receptor for advanced glycation end products (RAGE) is a 45 kDa transmembrane receptor of immunoglobulin family that can bind to various endogenous and exogenous ligands and initiate the inflammatory downstream signaling pathways. RAGE is involved in various disorders including cardiovascular and neurodegenerative diseases, cancer, and diabetes. This review summarizes the structural features of RAGE and its various isoforms along with their pathological effects. Mainly, the article emphasized on the translational significance of antagonizing the interactions of RAGE with its ligands using small molecules reported in the last 5 years and discusses future approaches that could be employed to block the interactions in the treatment of chronic inflammatory ailments. The RAGE inhibitors described in this article could prove as a powerful approach in the management of immune‐inflammatory diseases. A critical review of the literature suggests that there is a dire need to dive deeper into the molecular mechanism of action to resolve critical issues that must be addressed to understand RAGE‐targeting therapy and long‐term blockade of RAGE in human diseases.

Association of the RAGE/RAGE-ligand axis with interstitial lung disease and its acute exacerbation

The receptor for advanced glycation end product (RAGE) is a transmembrane receptor highly expressed in type 1 pneumocytes of healthy lungs. RAGE is considered to play a homeostatic role in the lung, as RAGE knockout mice develop lung fibrosis as they age. In contrast, RAGE can bind numerous ligands, including high-mobility group box 1 (HMGB1). These interactions initiate pro-inflammatory signaling associated with the pathogenesis of lung injury and interstitial lung disease (ILD), including idiopathic pulmonary fibrosis (IPF). ILD is a broad category of diffuse parenchymal lung disease characterized by various extents of lung fibrosis and inflammation, and IPF is a common and progressive ILD of unknown cause. The prognosis of patients with IPF is poor, and acute exacerbation of IPF (AE-IPF) is one of the main causes of death. Recent reports indicate that acute exacerbations can occur in other ILDs (AE-ILD). Notably, ILD is frequently observed in patients with lung cancer, and AE-ILD after surgical procedures or the initiation of chemotherapy for concomitant lung cancer are clinically important due to their association with increased mortality. In this review, we summarize the associations of RAGE/soluble RAGE (sRAGE)/RAGE ligands with the pathogenesis and clinical course of ILD, including IPF and AE-IPF. Additionally, the potential use of sRAGE and RAGE ligands as predictive markers of AE-IPF and cancer treatment-triggered AE-ILD is also discussed.

Prediction of emergency cerclage outcomes in women with cervical insufficiency: The role of inflammatory, angiogenic, and extracellular matrix-related proteins in amniotic fluid

OBJECTIVE

We aimed to determine whether various novel inflammatory, angiogenic, and extracellular matrix-related mediators in amniotic fluid (AF) can independently predict emergency cerclage outcomes in women with acute cervical insufficiency (CI).

METHODS

This was a retrospective cohort study conducted among 50 singleton pregnant women (18-25 weeks) who underwent emergency cerclage for CI and were subjected to amniocentesis. The AF samples were assayed for endoglin, endostatin, haptoglobin, insulin-like growth factor-binding protein (IGFBP)-3, -4, kallistatin, lumican, macrophage colony-stimulating factor (M-CSF), pentraxin 3, p-selectin, receptor for advanced glycation end products (RAGE), resistin, transforming growth factor beta-induced (TGFBI), and vitamin D-binding protein (VDBP) levels. Interleukin (IL)-6 levels in the AF were also measured for comparison with potential biomarkers assessed in this study. The primary endpoint was spontaneous preterm delivery (SPTD) at <34 weeks following emergency cerclage.

RESULTS

The AF levels of pentraxin 3, RAGE, and resistin were significantly higher in women who had SPTD at <34 weeks after cerclage placement (pentraxin-3: P = 0.003; RAGE: P = 0.041; and resistin; P = 0.002). In multivariate analysis, elevated AF levels of pentraxin 3 (P = 0.007) and resistin (P = 0.006), but not those of RAGE (P = 0.069), were independently associated with the occurrence of SPTD at <34 weeks after cerclage, following adjustment for baseline clinical variables (e.g., cervical dilation). The area under the curve (AUC) values of AF pentraxin 3, RAGE, and resistin for the prediction of SPTD at <34 weeks were 0.749, 0.669, and 0.770, respectively, which were similar to those of AF IL-6. However, in univariate analyses, no differences in the AF levels of endoglin, endostatin, haptoglobin, IGFBP-3, IGFBP-4, kallistatin, lumican, p-selectin, TGFBI, and VDBP were found to be associated with SPTD at <34 weeks after cerclage placement.

CONCLUSIONS

In women with acute CI, the AF levels of pentraxin 3, RAGE, and resistin could be useful novel biomarkers for predicting SPTD following emergency cerclage. However, the clinical utility of these new biomarkers should be validated in larger multicenter studies.

The effect of resveratrol on advanced glycation end products in diabetes mellitus: a systematic review

Advanced glycation end products (AGEs) lead to chronic oxidative stress and inflammation, which in turn augment diabetes complications. Resveratrol plays a potential role in relation to diabetes due to improving of hyperglycemia, oxidative stress, and inflammation. The aim of this review was to evaluate the scientific literature to identify the impacts of resveratrol on the accumulation of AGEs. The literature was searched in the online databases, viz. PubMed, SCOPUS, Embase, ProQuest, and Google Scholar until May 2019. From a total of 338 retrieved articles, 10 papers were eligible for the present analysis. Except one clinical trial, all studies were conducted on animals. All the included studies, except one, showed inhibitory effects of resveratrol on the accumulation of AGE or receptor for AGEs. The findings indicate that resveratrol is a potential protective agent against the accumulation of AGEs. There is, however, the need for future studies to investigate this effect on human.

Comparative validation of three DNA methylation algorithms of ageing and a frailty index in relation to mortality: results from the ESTHER cohort study

Background

Three DNA methylation (DNAm) based algorithms, DNAm PhenoAge acceleration (AgeAccelPheno), DNAm GrimAge acceleration (AgeAccelGrim), and mortality risk score (MRscore), based on methylation in 513, 1030, and 10 CpGs, respectively, were established to predict health outcomes and mortality. We aimed to compare and validate the predictive ability of these scores and frailty in relation to mortality in a population-based cohort from Germany.

Methods

DNA methylation in whole blood was measured by the Infinium Methylation EPIC BeadChip kit (EPIC, Illumina, San Diego, CA, USA) in two random subsets of the ESTHER cohort study (n = 741 and n = 1030). AgeAccelPheno, AgeAccelGrim, and a revised MRscore to adapt EPIC, the MRscore with 8 CpGs (MRscore-8CpGs), were calculated. Frailty was assessed by a frailty index (FI).

Findings

During 17 years of follow-up, 458 deaths were observed. All DNAm algorithms and FI were positively correlated with each other. AgeAccelPheno, AgeAccelGrim, MRscore, and FI showed independent associations with all-cause mortality [hazard ratio (95% CI) per SD increase = 1·32 (1·19-1·46), 1·47 (1·32-1·64), 1·73 (1·49-2·01), and 1·31 (1·20-1·43), respectively]. Harrell's C-statistic was 0·710 for a model predicting mortality by age, sex, and leukocyte composition and increased to 0·759 in a model including MRscore-8CpGs and FI. The predictive performance was further improved (Harrell's C-statistic = 0·766) when additionally including AgeAccelPheno and AgeAccelGrim into the model.

Interpretation

The combination of a DNA methylation score based on 8 CpGs only and an easy to ascertain frailty index may strongly enhance mortality prediction beyond age and sex.

Funding

The ESTHER study was funded by grants from the Baden-Württemberg state Ministry of Science, Research and Arts (Stuttgart, Germany), the Federal Ministry of Education and Research (Berlin, Germany), the Federal Ministry of Family Affairs, Senior Citizens, Women and Youth (Berlin, Germany), and the Saarland State Ministry of Health, Social Affairs, Women and the Family (Saarbrücken, Germany). The work of Xiangwei Li was supported by a grant from Fondazione Cariplo (Bando Ricerca Malattie invecchiamento, #2017-0653).

Inflammasomes in the Pathophysiology of Aortic Disease

Aortic diseases comprise aneurysms, dissections, and several other pathologies. In general, aging is associated with a slow but progressive dilation of the aorta, along with increased stiffness and pulse pressure. The progression of aortic disease is characterized by subclinical development or acute presentation. Recent evidence suggests that inflammation participates causally in different clinical manifestations of aortic diseases. As of yet, diagnostic imaging and surveillance is mainly based on ultrasonography, computed tomography (CT), and magnetic resonance imaging (MRI). Little medical therapy is available so far to prevent or treat the majority of aortic diseases. Endovascular therapy by the introduction of covered stentgrafts provides the main treatment option, although open surgery and implantation of synthetic grafts remain necessary in many situations. Because of the risks associated with surgery, there is a need for identification of pharmaceutical targets interfering with the pathophysiology of aortic remodeling. The participation of innate immunity and inflammasome activation in different cell types is common in aortic diseases. This review will thus focus on inflammasome activities in vascular cells of different chronic and acute aortic diseases and discuss their role in development and progression. We will also identify research gaps and suggest promising therapeutic targets, which may be used for future medical interventions.

Effect of Advanced Glycation End-Products and Excessive Calorie Intake on Diet-Induced Chronic Low-Grade Inflammation Biomarkers in Murine Models

Chronic Low-Grade Inflammation (CLGI) is a non-overt inflammatory state characterized by a continuous activation of inflammation mediators associated with metabolic diseases. It has been linked to the overconsumption of Advanced Glycation End-Products (AGEs), and/or macronutrients which lead to an increase in local and systemic pro-inflammatory biomarkers in humans and animal models. This review provides a summary of research into biomarkers of diet-induced CLGI in murine models, with a focus on AGEs and obesogenic diets, and presents the physiological effects described in the literature. Diet-induced CLGI is associated with metabolic endotoxemia, and/or gut microbiota remodeling in rodents. The mechanisms identified so far are centered on pro-inflammatory axes such as the interaction between AGEs and their main receptor AGEs (RAGE) or increased levels of lipopolysaccharide. The use of murine models has helped to elucidate the local and systemic expression of CLGI mediators. These models have enabled significant advances in identification of diet-induced CLGI biomarkers and resultant physiological effects. Some limitations on the translational (murine → humans) use of biomarkers may arise, but murine models have greatly facilitated the testing of specific dietary components. However, there remains a lack of information at the whole-organism level of organization, as well as a lack of consensus on the best biomarker for use in CLGI studies and recommendations as to future research conclude this review.

Impact of Sodium-Glucose Co-Transporter 2 Inhibitors on Cardiac Protection

Sodium–glucose co-transporter 2 (SGLT2) inhibitors have been approved as a new class of anti-diabetic drugs for type 2 diabetes mellitus (T2DM). The SGLT2 inhibitors reduce glucose reabsorption through renal systems, thus improving glycemic control in all stages of diabetes mellitus, independent of insulin. This class of drugs has the advantages of no clinically relevant hypoglycemia and working in synergy when combined with currently available anti-diabetic drugs. While improving sugar level control in these patients, SGLT2 inhibitors also have the advantages of blood-pressure improvement and bodyweight reduction, with potential cardiac and renal protection. In randomized control trials for patients with diabetes, SGLT2 inhibitors not only improved cardiovascular and renal outcomes, but also hospitalization for heart failure, with this effect extending to those without diabetes mellitus. Recently, dynamic communication between autophagy and the innate immune system with Beclin 1-TLR9-SIRT3 complexes in response to SGLT2 inhibitors that may serve as a potential treatment strategy for heart failure was discovered. In this review, the background molecular pathways leading to the clinical benefits are examined in this new class of anti-diabetic drugs, the SGLT2 inhibitors.

Targeting RAGE to prevent SARS-CoV-2-mediated multiple organ failure: Hypotheses and perspectives

A novel infectious disease (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), was detected in December 2019 and declared as a global pandemic by the World Health. Approximately 15% of patients with COVID-19 progress to severe pneumonia and eventually develop acute respiratory distress syndrome (ARDS), septic shock and/or multiple organ failure with high morbidity and mortality. Evidence points towards a determinant pathogenic role of members of the renin-angiotensin system (RAS) in mediating the susceptibility, infection, inflammatory response and parenchymal injury in lungs and other organs of COVID-19 patients. The receptor for advanced glycation end-products (RAGE), a member of the immunoglobulin superfamily, has important roles in pulmonary pathological states, including fibrosis, pneumonia and ARDS. RAGE overexpression/hyperactivation is essential to the deleterious effects of RAS in several pathological processes, including hypertension, chronic kidney and cardiovascular diseases, and diabetes, all of which are major comorbidities of SARS-CoV-2 infection. We propose RAGE as an additional molecular target in COVID-19 patients for ameliorating the multi-organ pathology induced by the virus and improving survival, also in the perspective of future infections by other coronaviruses.

Coronary heart disease risk: Low-density lipoprotein and beyond

Coronary heart disease (CHD) is the leading cause of morbidity and mortality world-wide and has been characterized as a chronic immunoinflammatory, fibroproliferative disease fueled by lipids. Great advances have been made in elucidating the complex mechanistic interactions among risk factors associated with CHD, yielding abundant success towards preventive measures and the development of pharmaceuticals to prevent and treat CHD via attenuation of lipoprotein-mediated risk. However, significant residual risk remains. Several potentially modifiable CHD risk factors ostensibly contributing to this residual risk have since come to the fore, including systemic inflammation, diabetes mellitus, high-density lipoprotein, plasma triglycerides (TG) and remnant lipoproteins (RLP), lipoprotein(a) (Lp[a]), and vascular endothelial dysfunction (ED). Herein, we summarize the body of evidence implicating each of these risk factors in residual CHD risk.

Alteration of oxidative-stress and related marker levels in mouse colonic tissues and fecal microbiota structures with chronic ethanol administration: Implications for the pathogenesis of ethanol-related colorectal cancer

Chronic ethanol consumption is a risk factor for colorectal cancer, and ethanol-induced reactive oxygen species have been suggested to play important roles in the pathogenesis of ethanol-related colorectal cancer (ER-CRC). In this study, the effects of 10-week chronic administration of ethanol on the colonic levels of oxidative stress and advance glycation end product (AGE) levels, as well as fecal microbiota structures, were examined in a mouse model. Chronic oral administration of ethanol in mice (1.0 mL of 1.5% or 5.0% ethanol (v/v) per day per mouse, up to 10 weeks) resulted in the elevation of colonic levels of oxidative stress markers (such as 8-hydroxy-2'-deoxyguanosine and 4-hydroxynonenal) compared to control mice, and this was consistently accompanied by elevated levels of inflammation-associated cytokines and immune cells (Th17 and macrophages) and a decreased level of regulatory T (Treg) cells to produce colonic lesions. It also resulted in an alteration of mouse fecal microbiota structures, reminiscent of the alterations observed in human inflammatory bowel disease, and this appeared to be consistent with the proposed sustained generation of oxidative stress in the colonic environment during chronic ethanol consumption. Moreover, the first experimental evidence that chronic ethanol administration results in elevated levels of advanced glycation end products (AGEs) and their receptors (RAGE) in the colonic tissues in mice is also shown, implying enhanced RAGE-mediated signaling with chronic ethanol administration. The RAGE-mediated signaling pathway has thus far been implicated as a link between the accumulation of AGEs and the development of many types of chronic colitis and cancers. Thus, enhancement of this pathway likely exacerbates the ethanol-induced inflammatory states of colonic tissues and might at least partly contribute to the pathogenesis of ER-CRC.

Receptor for Advanced Glycation End Products Is Involved in LPA5-Mediated Brain Damage after a Transient Ischemic Stroke

Lysophosphatidic acid receptor 5 (LPA₅) has been recently identified as a novel pathogenic factor for brain ischemic stroke. However, its underlying mechanisms remain unclear. Here, we determined whether the receptor for advanced glycation end products (RAGE) could be involved in LPA₅-mediated brain injuries after ischemic challenge using a mouse model of transient middle cerebral artery occlusion (tMCAO). RAGE was upregulated in the penumbra and ischemic core regions after tMCAO challenge. RAGE upregulation was greater at 3 days than that at 1 day after tMCAO challenge. It was mostly observed in Iba1-immunopositive cells of a post-ischemic brain. Suppressing LPA₅ activity with its antagonist, TCLPA5, attenuated RAGE upregulation in the penumbra and ischemic core regions, particularly on Iba1-immunopositive cells, of injured brains after tMCAO challenge. It also attenuated blood–brain barrier disruption, one of the core pathogenesis upon RAGE activation, after tMCAO challenge. As an underlying signaling pathways, LPA₅ could contribute to the activation of ERK1/2 and NF-κB in injured brains after tMCAO challenge. Collectively, the current study suggests that RAGE is a possible mediator for LPA₅-dependent ischemic brain injury.

Effects of the age/rage axis in the platelet activation

Platelet activity is essential in cardiovascular diseases. Therefore our objective was to evaluate the main effects of activating RAGE in platelets which are still unknown. A search for RAGE expression in different databases showed poor or a nonexistent presence in platelets. We confirmed the expression in platelets and secreted variable of RAGE (sRAGE). Platelets from elderly adults expressed in resting showed 3.2 fold more RAGE from young individuals (p < 0.01) and 3.3 fold with TRAP-6 (p < 0.001). These results could indicate that the expression of RAGE is more inducible in older adults. Then we found that activating RAGE with AGE-BSA-derived from methylglyoxal and subthreshold TRAP-6, showed a considerable increase with respect to the control in platelet aggregation and expression of P-selectin (respectively, p < 0.01). This effect was almost completely blocked by using a specific RAGE inhibitor (FSP-ZM1), confirming that RAGE is important for the function and activation platelet. Finally, we predict the region stimulated by AGE-BSA is located in region V of RAGE and 13 amino acids are critical for its binding. In conclusion, the activation of RAGE affects platelet activation and 13 amino acids are critical for its stimulation, this information is crucial for future possible treatments for CVD.

Glycation reaction and the role of the receptor for advanced glycation end-products in immunity and social behavior

The receptor for advanced glycation end-products (receptor for AGEs, RAGE) is a pattern recognition receptor. The interaction of RAGE with its ligands, such as AGEs, S100 proteins, high mobility group box-1 (HMGB1), and lipopolysaccharides (LPS), is known to play a pivotal role in the propagation of immune responses and inflammatory reactions. The ligand-RAGE interaction elicits cellular responses, for example, in myeloid and lymphoid cells, through distinct pathways by activating NF-κB and Rac1/cdc42, which lead to cytokine production, cell migration, phagocytosis, maturation, and polarization. Recently, oxytocin, a peptide hormone and neuropeptide, was identified as a novel binding molecule for the RAGE; however, it cannot compete with the interaction of RAGE with other ligands or induce RAGE intracellular signaling. The RAGE transports oxytocin from the blood into the brain and regulates brain functions. In this review, we summarize the current understanding of glycation reaction, AGEs, and the RAGE-mediated biological responses as well as the physiological role of RAGE in immunity and social behaviors, particularly, maternal bonding.

I mmunosenescence and Inflammaging: Risk Factors of Severe COVID-19 in Older People

Old individuals are more susceptible to various infections due to immunological changes that occur during the aging process. These changes named collectively as "immunosenescence" include decreases in both the innate and adaptive immune responses in addition to the exacerbated production of inflammatory cytokines. This scenario of immunological dysfunction and its relationship with disease development in older people has been widely studied, especially in infections that can be fatal, such as influenza and, more recently, COVID-19. In the current scenario of SARS-CoV-2 infection, many mechanisms of disease pathogenesis in old individuals have been proposed. To better understand the dynamics of COVID-19 in this group, aspects related to immunological senescence must be well elucidated. In this article, we discuss the main mechanisms involved in immunosenescence and their possible correlations with the susceptibility of individuals of advanced age to SARS-CoV-2 infection and the more severe conditions of the disease.

Genome-wide transcriptome profiling reveals the mechanisms underlying muscle group-specific phenotypic changes under different raising systems in ducks

Although a number of nongenetic factors have been reported to be able to modulate skeletal muscle phenotypes in meat-type birds, neither the underlying mechanisms nor the muscle group–specific phenotypic and molecular responses have been fully understood. In the present study, a total of 240 broiler ducks were used to compare the effects of floor raising system (FRS) and net raising system (NRS) on the physicochemical properties and global gene expression profiles of both breast and thigh muscles at the posthatching week 4 (W4), W8, and W13. Our results showed that compared with FRS, NRS generally induced higher pH, lower lightness (L∗) and yellowness (b∗), lower drip loss and cooking loss, and lower shear force in either breast or thigh muscles during early posthatching stages but subsequently showed less pronounced or even reverse effects. Meanwhile, it was observed that the raising system differently changed the myofiber characteristics depending on the muscle group and the developmental stage. Genome-wide transcriptome analysis showed that compared with FRS, NRS induced the most extensive gene expression changes in breast muscle (BM) at W4 but in thigh muscle (TM) at W13, suggesting the asynchronous molecular responses of BM and TM to the raising system and period. Most of differentially expressed genes in either BM or TM between NRS and FRS were enriched in the Gene Ontology and Kyoto Encyclopedia of Genes and Genomes terms associated with regulation of muscle cellular functions, metabolic and contractile activities, and tissue remodeling, indicating similar molecular mechanisms principally responsible for the raising system-caused phenotypic changes in both muscle groups. Nevertheless, several crucial pathways (e.g., adipocytokine signaling, AGE-RAGE signaling, and apoptosis) and genes (e.g., ANO6, ACER2, UCP3, DTL, and TMEM120A) were tightly related to the muscle group–specific adaptive remodeling on different raising systems. These data could not only contribute to a better understanding of the molecular mechanisms behind meat quality but also provide novel insights into the molecular causes of the muscle group–specific adaptive remodeling in response to environmental stimuli.

Targeting mitochondrial fitness as a strategy for healthy vascular aging

Cardiovascular diseases (CVD) are the leading cause of death worldwide and aging is the primary risk factor for CVD. The development of vascular dysfunction, including endothelial dysfunction and stiffening of the large elastic arteries (i.e., the aorta and carotid arteries), contribute importantly to the age-related increase in CVD risk. Vascular aging is driven in large part by oxidative stress, which reduces bioavailability of nitric oxide and promotes alterations in the extracellular matrix. A key upstream driver of vascular oxidative stress is age-associated mitochondrial dysfunction. This review will focus on vascular mitochondria, mitochondrial dysregulation and mitochondrial reactive oxygen species (ROS) production and discuss current evidence for prevention and treatment of vascular aging via lifestyle and pharmacological strategies that improve mitochondrial health. We will also identify promising areas and important considerations ('research gaps') for future investigation.

Measuring Aging and Identifying Aging Phenotypes in Cancer Survivors

Observational data have shown that some cancer survivors develop chronic conditions like frailty, sarcopenia, cardiac dysfunction, and mild cognitive impairment earlier and/or at a greater burden than similarly aged individuals never diagnosed with cancer or exposed to systemic or targeted cancer therapies. In aggregate, cancer- and treatment-related physical, cognitive, and psychosocial late- and long-term morbidities experienced by cancer survivors are hypothesized to represent accelerated or accentuated aging trajectories. However, conceptual, measurement, and methodological challenges have constrained efforts to identify, predict, and mitigate aging-related consequences of cancer and cancer treatment. In July 2018, the National Cancer Institute convened basic, clinical, and translational science experts for a think tank titled "Measuring Aging and Identifying Aging Phenotypes in Cancer Survivors." Through the resulting deliberations, several research and resource needs were identified, including longitudinal studies to examine aging trajectories that include detailed data from before, during, and after cancer treatment; mechanistic studies to elucidate the pathways that lead to the emergence of aging phenotypes in cancer survivors; long-term clinical surveillance to monitor survivors for late-emerging effects; and tools to integrate multiple data sources to inform understanding of how cancer and its therapies contribute to the aging process. Addressing these needs will help expand the evidence base and inform strategies to optimize healthy aging of cancer survivors.

Reprogramming of Mesothelial-Mesenchymal Transition in Chronic Peritoneal Diseases by Estrogen Receptor Modulation and TGF-β1 Inhibition

In chronic peritoneal diseases, mesothelial-mesenchymal transition is determined by cues from the extracellular environment rather than just the cellular genome. The transformation of peritoneal mesothelial cells and other host cells into myofibroblasts is mediated by cell membrane receptors, Transforming Growth Factor β1 (TGF-β1), Src and Hypoxia-inducible factor (HIF). This article provides a narrative review of the reprogramming of mesothelial mesenchymal transition in chronic peritoneal diseases, drawing on the similarities in pathophysiology between encapsulating peritoneal sclerosis and peritoneal metastasis, with a particular focus on TGF-β1 signaling and estrogen receptor modulators. Estrogen receptors act at the cell membrane/cytosol as tyrosine kinases that can phosphorylate Src, in a similar way to other receptor tyrosine kinases; or can activate the estrogen response element via nuclear translocation. Tamoxifen can modulate estrogen membrane receptors, and has been shown to be a potent inhibitor of mesothelial-mesenchymal transition (MMT), peritoneal mesothelial cell migration, stromal fibrosis, and neoangiogenesis in the treatment of encapsulating peritoneal sclerosis, with a known side effect and safety profile. The ability of tamoxifen to inhibit the transduction pathways of TGF-β1 and HIF and achieve a quiescent peritoneal stroma makes it a potential candidate for use in cancer treatments. This is relevant to tumors that spread to the peritoneum, particularly those with mesenchymal phenotypes, such as colorectal CMS4 and MSS/EMT gastric cancers, and pancreatic cancer with its desmoplastic stroma. Morphological changes observed during mesothelial mesenchymal transition can be treated with estrogen receptor modulation and TGF-β1 inhibition, which may enable the regression of encapsulating peritoneal sclerosis and peritoneal metastasis.

Proteasomal degradation of glycated proteins depends on substrate unfolding: Preferred degradation of moderately modified myoglobin

The Maillard reaction generates protein modifications which can accumulate during hyperglycemia or aging and may have inflammatory consequences. The proteasome is one of the major intracellular systems involved in the proteolytic degradation of modified proteins but its role in the degradation of glycated proteins is scarcely studied. In this study, chemical and structural changes of glycated myoglobin were analyzed and its degradation by 20S proteasome was studied. Myoglobin was incubated with physiological (5-10 mM), moderate (50-100 mM) and severe levels (300 mM) of glucose or methylglyoxal (MGO, 50 mM). Glycation increased myoglobin's fluorescence and surface hydrophobicity. Severe glycation generated crosslinked proteins as shown by gel electrophoresis. The concentration of advanced glycation endproducts (AGEs) N-ε-carboxymethyl lysine (CML), N-ε-carboxyethyl lysine (CEL), methylglyoxal-derived hydroimidazolone-1 (MG-H1), pentosidine and pyrraline was analyzed after enzymatic hydrolysis followed by UPLC-MS/MS. Higher concentrations of glucose increased all analyzed AGEs and incubation with MGO led to a pronounced increase of CEL and MG-H1. The binding of the heme group to apo-myoglobin was decreased with increasing glycation indicating the loss of tertiary protein structure. Proteasomal degradation of modified myoglobin compared to native myoglobin depends on the degree of glycation: physiological conditions decreased proteasomal degradation whereas moderate glycation increased degradation. Severe glycation again decreased proteolytic cleavage which might be due to crosslinking of protein monomers. The activity of the proteasomal subunit β5 is influenced by the presence of glycated myoglobin. In conclusion, the role of the proteasome in the degradation of glycated proteins is highly dependent on the level of glycation and consequent protein unfolding.

RAGE Silencing Ameliorates Neuroinflammation by Inhibition of p38-NF-κB Signaling Pathway in Mouse Model of Parkinson's Disease

Accumulating evidence suggested that neuroinflammation played a crucial role in dopaminergic neuronal death in Parkinson's disease (PD). The receptor for advanced glycation end products (RAGE), a multi-ligand receptor of the immunoglobulin superfamily, has been proposed as a key molecule in the onset and sustainment of the inflammatory response. Engagement of RAGE contributed to neuroinflammation by upregulating nuclear factor-κB (NF-κB) as well as cytokines. The aim of the present study was to investigate the expression of RAGE in 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-treated mice and elucidate the RAGE signal pathway involved in the inflammation. Results showed that RAGE protein and pro-inflammatory cytokines cyclooxygenase type 2 (COX-2) were upregulated in MPTP-treated mice. Further experiments showed that RAGE ablation inhibited phosphorylation of IκB and p38 and protected nigral dopaminergic neurons against cell death in the substantia nigra (SN). These results suggested that RAGE participated in the pathogenesis of PD by neuroinflammation and p38MAPK-NFκB signal pathway may be involved in the process. Moreover, interfering with RAGE signaling pathway may be a reasonable therapeutic option in slowing PD development and progression.

Role of Advanced Glycation End Products in Carcinogenesis and their Therapeutic Implications

Aging is one of the biggest risk factors for the major prevalent diseases such as cardiovascular diseases, neurodegeneration and cancer, but due to the complex and multifactorial nature of the aging process, the molecular mechanisms underlying age-related diseases are not yet fully understood. Research has been intensive in the last years aiming to characterize the pathophysiology of aging and develop therapies to fight age-related diseases. In this context advanced glycation end products (AGEs) have received attention. AGEs, when accumulated in tissues, significantly increase the level of inflammation in the body which has long been associated with the development of cancer. Here we discuss the classical settings promoting AGE formation, as well as reduction strategies, occurrence and relevance of AGEs in cancer tissues and the role of AGE-interaction with the receptor for advanced glycation end products (RAGE) in cancer initiation and progression.

The receptor for advanced glycation end-products (RAGE) is an important pattern recognition receptor (PRR) for inflammaging

The receptor for advanced glycation end-products (RAGE) was initially characterized and named for its ability to bind to advanced glycation end-products (AGEs) that form upon the irreversible and non-enzymatic interaction between nucleophiles, such as lysine, and carbonyl compounds, such as reducing sugars. The concentrations of AGEs are known to increase in conditions such as diabetes, as well as during ageing. However, it is now widely accepted that RAGE binds with numerous ligands, many of which can be defined as pathogen-associated molecular patterns (PAMPs) or damage-associated molecular patterns (DAMPs). The interaction between RAGE and its ligands mainly results in a pro-inflammatory response, and can lead to stress events often favouring mitochondrial dysfunction or cellular senescence. Thus, RAGE should be considered as a pattern recognition receptor (PRR), similar to those that regulate innate immunity. Innate immunity itself plays a central role in inflammaging, the chronic low-grade and sterile inflammation that increases with age and is a potentially important contributory factor in ageing. Consequently, and in addition to the age-related accumulation of PAMPs and DAMPs and increases in pro-inflammatory cytokines from senescent cells and damaged cells, PRRs are therefore important in inflammaging. We suggest here that, through its interconnection with immunity, senescence, mitochondrial dysfunction and inflammasome activation, RAGE is a key contributor to inflammaging and that the pro-longevity effects seen upon blocking RAGE, or upon its deletion, are thus the result of reduced inflammaging.

Glycated proteins in nutrition: Friend or foe?

Advanced glycation end products (AGEs) are formed in in vivo, and accumulate in tissues and body fluids during ageing. Endogenous AGE-modified proteins show altered structure and function, and may interact with receptor for AGEs (RAGE) resulting in production of reactive oxygen species, inflammatory, atherogenic and diabetogenic responses. AGEs are also formed in thermally processed foods. Studies in rodents document that dietary AGEs are partially absorbed into circulation, and accumulate in different tissues. Knowledge on the health effects of high dietary intake of AGEs is incomplete and contradictory. In this overview we discuss the data from experimental and clinical studies, either those supporting the assumption that restriction of dietary AGEs associated with health benefits, or data suggesting that dietary intake of AGEs associates with positive health outcomes. We polemicize whether the effects of exaggerated intake or restriction of highly thermally processed foods might be straightforward interpreted as the effects of AGEs-rich vs. AGEs-restricted diets. We also underline the lack of studies, and thus a poor knowledge, on the effects of different single chemically defined AGEs administration, concurrent intake of different dietary AGEs, of load with dietary AGEs corresponding to the habitual diet in humans, and on those of dietary AGEs in vulnerable populations, such as infants and particularly elderly.

MitoQ supplementation prevent long-term impact of maternal smoking on renal development, oxidative stress and mitochondrial density in male mice offspring

To investigate the effect of maternal MitoQ treatment on renal disorders caused by maternal cigarette smoke exposure (SE). We have demonstrated that maternal SE during pregnancy increases the risk of developing chronic kidney disease (CKD) in adult offspring. Mitochondrial oxidative damage contributes to the adverse effects of maternal smoking on renal disorders. MitoQ is a mitochondria-targeted antioxidant that has been shown to protect against oxidative damage-related pathologies in many diseases. Female Balb/c mice (8 weeks) were divided into Sham (exposed to air), SE (exposed to cigarette smoke) and SEMQ (exposed to cigarette smoke with MitoQ supplemented from mating) groups. Kidneys from the mothers were collected when the pups weaned and those from the offspring were collected at 13 weeks. Maternal MitoQ supplementation during gestation and lactation significantly reversed the adverse impact of maternal SE on offspring’s body weight, kidney mass and renal pathology. MitoQ administration also significantly reversed the impact of SE on the renal cellular mitochondrial density and renal total reactive oxygen species in both the mothers and their offspring in adulthood. Our results suggested that MitoQ supplementation can mitigate the adverse impact of maternal SE on offspring’s renal pathology, renal oxidative stress and mitochondrial density in mice offspring.

Hypoxia, cytokines and stromal recruitment: parallels between pathophysiology of encapsulating peritoneal sclerosis, endometriosis and peritoneal metastasis

Peritoneal response to various kinds of injury involves loss of peritoneal mesothelial cells (PMC), danger signalling, epithelial-mesenchymal transition and mesothelial-mesenchymal transition (MMT). Encapsulating peritoneal sclerosis (EPS), endometriosis (EM) and peritoneal metastasis (PM) are all characterized by hypoxia and formation of a vascularized connective tissue stroma mediated by vascular endothelial growth factor (VEGF). Transforming growth factor-β1 (TGF-β1) is constitutively expressed by the PMC and plays a major role in the maintenance of a transformed, inflammatory micro-environment in PM, but also in EPS and EM. Persistently high levels of TGF-β1 or stimulation by inflammatory cytokines (interleukin-6 (IL-6)) induce peritoneal MMT, adhesion formation and fibrosis. TGF-β1 enhances hypoxia inducible factor-1α expression, which drives cell growth, extracellular matrix production and cell migration. Disruption of the peritoneal glycocalyx and exposure of the basement membrane release low molecular weight hyaluronan, which initiates a cascade of pro-inflammatory mediators, including peritoneal cytokines (TNF-α, IL-1, IL-6, prostaglandins), growth factors (TGF-α, TGF-β, platelet-derived growth factor, VEGF, epidermal growth factor) and the fibrin/coagulation cascade (thrombin, Tissue factor, plasminogen activator inhibitor [PAI]-1/2). Chronic inflammation and cellular transformation are mediated by damage-associated molecular patterns, pattern recognition receptors, AGE-RAGE, extracellular lactate, pro-inflammatory cytokines, reactive oxygen species, increased glycolysis, metabolomic reprogramming and cancer-associated fibroblasts. The pathogenesis of EPS, EM and PM shows similarities to the cellular transformation and stromal recruitment of wound healing.