Receptor For Advanced Glycation End Products Research Articles

Deciphering the impact and mechanism of Trikatu, a spices-based formulation on alcoholic liver disease employing network pharmacology analysis and in vivo validation.

Trikatu Churna (TC) comprising Zingiber officinale rhizome, Piper longum, and Piper nigrum fruit, is effective in treating liver diseases and has high nutraceutical values. However, the efficacy of TC in treating alcoholic liver disease (ALD) and its mechanism remain largely unknown. This study evaluated the hepatoprotective effects of different doses of TC as well as to identify the bioactive components and determine their mechanism of action against ethanol-induced ALD. A compound-target network analysis model of TC was established to identify its potential bioactive compounds and pathways that might regulate its hepatoprotective effects. Further, in-vivo studies were performed to validate the potential of TC (200 mg/kg and 400 mg/kg b.w.) in the treatment and management of ALD. The study revealed that both the dosages of TC demonstrate significant (p > 0.0001) hepatoprotective effects by improving body weight, total bilirubin, serum glutamic oxaloacetic transaminase (SGOT), serum glutamic pyruvic transaminase (SGPT), serum alkaline phosphate (ALP), total cholesterol, total protein, globulin, albumin, and liver morphology. The High-performance thin-layer chromatography (HPTLC) fingerprinting of TC showed the presence of piperine. Network pharmacology identifies the role of TC in regulating various signaling processes including Advanced glycation end products-receptor for advanced glycation end products (AGE-RAGE), Hypoxia-inducible factors (HIF-1), Nuclear factor kappa-light-chain-enhancer of activated B cells (NF-Kappa B), and Phosphatidylinositol 3-kinase/protein kinase B (PI3K/Akt) signaling to exert its anti-inflammatory, antioxidant and anti-apoptotic role in managing ALD. Based on the bioinformatics analysis, some of the key targets of TC were found to be Prostaglandin-Endoperoxide Synthase 2 (PTGS2) or Cyclooxygenase-2 (COX-2), Sirtuin 1 (SRT1), and caspase-3. These effects may serve as a novel therapeutic option for the treatment of ALD. These preclinical validation studies for the ethnopharmacological potential of TC in ALD treatment further paved the way for researchers to perform next-level translational and clinical studies. Further, in-depth experimental studies for the validation of these bioinformatics-based results will give a clearer picture of mechanisms.

Male-selective effects of oxytocin agonism on alcohol intake: behavioral assessment in socially housed prairie voles and involvement of RAGE

Targeting the oxytocin (OXT) peptide system has emerged as a promising new approach for the treatment of alcohol use disorder (AUD). However, further advancements in this development depend on properly modeling various complex social aspects of AUD and its treatment. Here we examined behavioral and molecular underpinnings of OXT receptor (OXTR) agonism in prairie voles, a rodent species with demonstrated translational validity for neurobiological mechanisms regulating social affiliations. To further improve translational validity of these studies, we examined effects of intranasal (IN) OXT administration in male and female prairie voles socially housed in the presence of untreated cagemates. IN OXT selectively inhibited alcohol drinking in male, but not female, animals. Further, we confirmed that exogenously administered OXT penetrates the prairie vole brain and showed that Receptor for Advanced Glycation End-products assists this penetration after IN, but not intraperitoneal (IP), OXT administration. Finally, we demonstrated that IP administration of LIT-001, a small-molecule OXTR agonist, inhibits alcohol intake in male, but not female, prairie voles socially housed in the presence of untreated cagemates. Taken together, results of this study support the promise of selectively targeting OXTR for individualized treatment of AUD.

Extracellular histones as damage-associated molecular patterns in neuroinflammatory responses.

The four core histones H2A, H2B, H3, H4, and the linker histone H1 primarily bind DNA and regulate gene expression within the nucleus. Evidence collected mainly from the peripheral tissues illustrates that histones can be released into the extracellular space by activated or damaged cells. In this article, we first summarize the innate immune-modulatory properties of extracellular histones and histone-containing complexes, such as nucleosomes, and neutrophil extracellular traps (NETs), described inperipheral tissues. There, histones act as damage-associated molecular patterns (DAMPs), which are a class of endogenous molecules that trigger immune responses by interacting directly with the cellular membranes andactivating pattern recognition receptors (PRRs), suchas toll-like receptors (TLR) 2, 4, 9 and the receptor foradvanced glycation end-products (RAGE). We then focuson the available evidence implicating extracellular histones as DAMPs of the central nervous system (CNS). It is becoming evident that histones are present in the brain parenchyma after crossing the blood-brain barrier (BBB) or being released by several types of brain cells, including neurons, microglia, and astrocytes. However, studies on the DAMP-like effects of histones on CNS cells are limited. For example, TLR4 is the only known molecular target of CNS extracellular histones and their interactions with other PRRs expressed by brain cells have not been observed. Nevertheless, extracellular histones are implicated in thepathogenesis of a variety of neurological disorders characterized by sterile neuroinflammation; therefore, detailed studies on the role these proteins and their complexes play in these pathologies could identify novel therapeutic targets.

Glucagon-like peptide-1 receptor regulates receptor of advanced glycation end products in high glucose-treated rat mesangial cells.

Hyperglycemia-induced advanced glycation end products (AGEs) and receptor for AGEs (RAGEs) play major roles in diabetic nephropathy progression. In previous study, both glucagon-like peptide-1 (GLP-1) and peroxisome proliferator-activated receptors delta (PPARδ) agonists were shown to have anti-inflammatory effect on AGE-treated rat mesangial cells (RMCs). The interaction among PPARδ agonists, GLP-1, and AGE-RAGE axis is, however, still unclear. In this study, the individual and synergic effect of PPARδ agonist (L-165 041) and siRNA of GLP-1 receptor (GLP-1R) on the expression of GLP-1, GLP-1R, RAGE, and cell viability in AGE-treated RMCs were investigated. L-165 041 enhanced GLP-1R mRNA and protein expression only in the presence of AGE. The expression of RAGE mRNA and protein was enhanced by AGE, attenuated by L-165 041, and siRNA of GLP-1R reversed L-165 041-induced inhibition. Cell viability was also inhibited by AGE. L-165 041 attenuated AGE-induced inhibition and siRNA GLP-1R diminished L-165 041 effect. PPARδ agonists increase GLP-1R expression on RMC in the presence of AGE. PPARδ agonists also attenuate AGE-induced upregulated RAGE expression and downregulated cell viability. The effect of PPARδ agonists needs the cooperation of GLP-1R activation.

Abstract 14919: EN-RAGE is Associated With Improved Outcomes in Hospitalized COVID-19 Patients

Background: Inflammation has been implicated in the pathogenesis, severity, and outcomes of COVID-19. Extracellular newly identified receptor for advanced glycation end-product (EN-RAGE), a soluble EF-hand calcium-binding protein, causes integrin activation, activates inflammation, and upregulates the synthesis of vascular cell adhesion molecule-1 and intracellular adhesion molecule-1. While it is positively associated with atherosclerosis, high EN-RAGE levels have been shown to predict remission of auto-immune diseases. The role of EN-RAGE as a biomarker in COVID-19 is unknown. Methods: Serum EN-RAGE levels were measured from blood samples of 146 COVID-19 in-patients using Myriad® Cytokine MAP and compared between the subgroups based on race and outcomes. T-test, Chi-square, and multivariable regression analysis were performed to identify the correlation of EN-RAGE with race and outcomes. Results: Of 146 patients (mean age=59 years), 60% were female, 35% were White, and 60% were African Americans. 21 of the 146 (14%) patients died. Mortality was higher in Whites compared to African Americans (21% vs 10%) consistent with CDC data showing higher mortality in Whites compared to non-Whites. Surprisingly, African Americans had significantly higher EN-RAGE levels compared to Whites. (574.6 vs 360.9 respectively, p=0.002). Congruently, EN-RAGE levels were significantly higher in the patients who survived compared to the patients who died. (514.82 vs 336.29, p=0.039) suggesting that increased serum EN-RAGE levels may be associated with improved outcomes in hospitalized COVID-19 patients. Conclusion: Our study reveals a negative association of EN-RAGE levels with in-patient mortality associated with COVID-19 and could possibly be used as a biomarker of survival in hospitalized COVID-19 patients. EN-RAGE levels could partly explain mortality differences based on race. Further studies are required to confirm this association.

Expression of advanced glycation end products and receptors in gingival tissues of patients with noninsulin-dependent diabetes mellitus-associated periodontitis

Background/purposeAdvanced glycation end products (AGEs) are known to accumulate in the periodontal tissues of patients with diabetes mellitus (DM). Through this study, we aimed to investigate the distribution of AGEs and the receptor of AGEs (RAGE) in the gingival tissues of patients with chronic periodontitis with and without non-insulin-dependent diabetes mellitus (NIDDM). Materials and methodsGingival biopsy samples from 13 patients with both NIDDM and periodontitis and 6 patients with both non-DM (NDM) and periodontitis were collected. The tissue sections were processed using immunohistochemical (IHC) staining to detect the distributions of AGEs and RAGE. Spearman correlation coefficients of all samples were calculated (P < 0.05) for the AGE and RAGE rankings of the following clinical parameters: plaque score (PI), probing depth (PD), bleeding on probing (BOP), and tooth loss (TL). ResultsIHC analysis revealed that AGEs among patients with NIDDM had a significantly higher ranking than those of the NDM group (P < 0.05). Positive staining for RAGE was observed in both groups but was not significantly different (P > 0.05). A positive correlation between AGE ranking and TL was observed in the NIDDM group, but not between AGE ranking and PI, PD, or BOP. The distribution of RAGE was not correlated with PI, PD, BOP, or TL. ConclusionAGEs were particularly distributed in the highly inflamed gingiva of patients with NIDDM-associated periodontitis and was statistically correlated with the long-term parameter TL.

Methylglyoxal - an advanced glycation end products (AGEs) precursor - Inhibits differentiation of human MSC-derived osteoblasts in vitro independently of receptor for AGEs (RAGE).

A major precursor of advanced glycation end-products (AGEs) - methylglyoxal (MG) - is a reactive carbonyl metabolite that originates from glycolytic pathways. MG formation and accumulation has been implicated in the pathogenesis of diabetes and age-related chronic musculoskeletal disorders. Human bone marrow-derived stromal cells (BMSCs) are multipotent cells that have the potential to differentiate into cells of mesenchymal origin including osteoblasts, but the role of MG on their differentiation is unclear. We therefore evaluated the effect of MG on proliferation and differentiation of BMSC-derived osteoblasts. Cells were treated with different concentrations of MG (600, 800 and 1000μM). Cell viability was assessed using a Cell Counting Kit-8 assay. Alkaline phosphatase (ALP) activity and calcium deposition assays were performed to evaluate osteoblast differentiation and mineralization. Gene expression was measured using qRT-PCR, whereas AGE specific receptor (RAGE) and collagen 1 were examined by immunocytochemistry and Western blotting. RAGE knockdown was performed by transducing RAGE specific short hairpin RNAs (shRNAs) using lentivirus. During osteogenic differentiation, MG treatment resulted in reduction of cell viability (27.7%), ALP activity (45.5%) and mineralization (82.3%) compared to untreated cells. MG significantly decreased expression of genes involved in osteogenic differentiation - RUNX2 (2.8 fold), ALPL (3.2 fold), MG detoxification through glyoxalase - GLO1 (3 fold) and collagen metabolism - COL1A1 (4.9 fold), COL1A2 (6.8 fold), LOX (5.4 fold) and PLOD1 (1.7 fold). MG significantly reduced expression of collagen 1 (53.3%) and RAGE (43.1%) at protein levels. Co-treatment with a MG scavenger - aminoguanidine - prevented all negative effects of MG. RAGE-specific knockdown during MG treatment did not reverse the effects on cell viability, osteogenic differentiation or collagen metabolism. In conclusion, MG treatment can negatively influence the collagen metabolism and differentiation of BMSCs-derived osteoblasts through a RAGE independent mechanism.

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.

The Decrease in Serum sRAGE Levels Upon Smoking is Associated with Activated Neutrophils

The serum level of the soluble Receptor for Advanced Glycation End-products (sRAGE) is a promising blood biomarker for the development, severity, and progression of chronic obstructive pulmonary disease (COPD). However, cigarette smoking causes a nearly instant drop in circulating sRAGE levels, strongly impacting on the variability in sRAGE levels. In the current study, we investigated the possible mechanism behind the sudden drop in sRAGE upon smoking. We showed that the number of activated neutrophils in blood significantly increases within two hours upon smoking three cigarettes within one hour. Furthermore, an increased expression of the leukocyte activation marker CD11b, which is a known ligand for RAGE, was observed upon smoking. Additionally, the in vitro activation of neutrophils increased their capacity to bind sRAGE. Together, these data indicate that smoking activates neutrophils in the circulation with concomitant upregulation of the RAGE ligand CD11b, leading to reduced levels of sRAGE in serum.

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

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

Serial Measurements of Protein Biomarkers in Sepsis-Induced Acute Respiratory Distress Syndrome.

IMPORTANCE:The role of early, serial measurements of protein biomarkers in sepsis-induced acute respiratory distress syndrome (ARDS) is not clear.OBJECTIVES:To determine the differences in soluble receptor for advanced glycation end-products (sRAGEs), angiopoietin-2, and surfactant protein-D (SP-D) levels and their changes over time between sepsis patients with and without ARDS.DESIGN, SETTING, AND PARTICIPANTS:Prospective observational cohort study of adult patients admitted to the medical ICU at Grady Memorial Hospital within 72 hours of sepsis diagnosis.MAIN OUTCOMES AND MEASURES:Plasma sRAGE, angiopoietin-2, and SP-D levels were measured for 3 consecutive days after enrollment. The primary outcome was ARDS development, and the secondary outcome of 28-day mortality. The biomarker levels and their changes over time were compared between ARDS and non-ARDS patients and between nonsurvivors and survivors.RESULTS:We enrolled 111 patients, and 21 patients (18.9%) developed ARDS. The three biomarker levels were not significantly different between ARDS and non-ARDS patients on all 3 days of measurement. Nonsurvivors had higher levels of all three biomarkers than did survivors on multiple days. The changes of the biomarker levels over time were not different between the outcome groups. Logistic regression analyses showed association between day 1 SP-D level and mortality (odds ratio, 1.52; 95% CI, 1.03–2.24; p = 0.03), and generalized estimating equation analyses showed association between angiopoietin-2 levels and mortality (estimate 0.0002; se 0.0001; p = 0.04).CONCLUSIONS AND RELEVANCE:Among critically ill patients with sepsis, sRAGE, angiopoietin-2, and SP-D levels were not significantly different between ARDS and non-ARDS patients but were higher in nonsurvivors compared with survivors. The trend toward higher levels of sRAGE and SP-D, but not of angiopoietin-2, in ARDS patients may indicate the importance of epithelial injury in sepsis-induced ARDS. Changes of the biomarker levels over time were not different between the outcome groups.

Natural Biologics Accelerate Healing of Diabetic Foot Ulcers by Regulating Oxidative Stress.

Difficult or even non-healing diabetic foot ulcers (DFU) are a global medical challenge. Although current treatments such as debridement, offloading, and infection control have resulted in partial improvement in DFU, the incidence, amputation, and mortality rates of DFU remain high. Therefore, there is an urgent need to find new or more effective drugs. Numerous studies have shown that oxidative stress plays an important role in the pathophysiology of DFU. The nuclear factor erythroid 2-related factor (Nrf2) signaling pathway and the advanced glycated end products (AGEs)-receptor for advanced glycation endproducts (RAGE), protein kinase C (PKC), polyol and hexosamine biochemical pathways play critical roles in the regulation of oxidative stress in the body. Targeting these pathways to restore redox balance can control and alleviate the occurrence and development of DFU. Natural biologics are a major source of potential drugs for these relevant targets, and their antioxidant potential has been extensively demonstrated. Here, we discussed the pathophysiological mechanism of oxidative stress in DFU, and identifiled natural biologics targeting these pathways to accelerate DFU healing, in order to provide a new or potential direction for clinical treatment, nursing and related basic research of DFU.

RAGE antagonism with azeliragon improves xenograft rejection by T cells in humanized mice.

The receptor for advanced glycation endproducts (RAGE) is involved in multiple inflammatory processes. RAGE participates in adaptive and innate immune responses but its role in human immune cell responses has not been directly tested in vivo. We treated humanized mice (NSG) with the small molecule antagonist of RAGE, azeliragon, (AZ), and measured effects on xenogeneic (B6) skin graft rejection. AZ delayed the median time to xenograft rejection (22 vs 56 days, P = 0.0001). PD-1 expression on CD4+ and CD8+ T cells was lower following AZ therapy. Transcriptome studies showed inhibition of pathways in splenocytes with AZ including IL-23, IL-17A and IL-1β signaling. The serum levels of IL-1β and IL-17A in AZ treated mice were reduced in mice that did not reject skin grafts. The RAGE antagonist prevented xenograft rejection by human immune cells in a murine model. A RAGE antagonist may be a useful inhibitor of adaptive human immune responses.

Receptor for Advanced Glycation End-Products Promotes Activation of Alveolar Macrophages through the NLRP3 Inflammasome/TXNIP Axis in Acute Lung Injury.

The roles of thioredoxin-interacting protein (TXNIP) and receptor for advanced glycation end-products (RAGE)-dependent mechanisms of NOD-like receptor family, pyrin domain containing 3 (NLRP3) inflammasome-driven macrophage activation during acute lung injury are underinvestigated. Cultured THP-1 macrophages were treated with a RAGE agonist (S100A12), with or without a RAGE antagonist; cytokine release and intracytoplasmic production of reactive oxygen species (ROS) were assessed in response to small interfering RNA knockdowns of TXNIP and NLRP3. Lung expressions of TXNIP and NLRP3 and alveolar levels of IL-1β and S100A12 were measured in mice after acid-induced lung injury, with or without administration of RAGE inhibitors. Alveolar macrophages from patients with acute respiratory distress syndrome and from mechanically ventilated controls were analyzed using fluorescence-activated cell sorting. In vitro, RAGE promoted cytokine release and ROS production in macrophages and upregulated NLRP3 and TXNIP mRNA expression in response to S100A12. TXNIP inhibition downregulated NLRP3 gene expression and RAGE-mediated release of IL-1β by macrophages in vitro. In vivo, RAGE, NLRP3 and TXNIP lung expressions were upregulated during experimental acute lung injury, a phenomenon being reversed by RAGE inhibition. The numbers of cells expressing RAGE, NLRP3 and TXNIP among a specific subpopulation of CD16+CD14+CD206- (“pro-inflammatory”) alveolar macrophages were higher in patients with lung injury. This study provides a novel proof-of-concept of complex RAGE–TXNIP–NLRP3 interactions during macrophage activation in acute lung injury.

Selecting Multitarget Peptides for Alzheimer's Disease.

Alzheimer’s disease (AD) is a multifactorial disease with a complex pathogenesis. Developing multitarget drugs could be a powerful strategy to impact the progressive loss of cognitive functions in this disease. The purpose of this study is to select a multitarget lead peptide candidate among a series of peptide variants derived from the neutrophil granule protein cathepsin G. We screened eight peptide candidates using the following criteria: (1) Inhibition and reversion of amyloid beta (Aβ) oligomers, quantified using an enzyme-linked immunosorbent assay (ELISA); (2) direct binding of peptide candidates to the human receptor for advanced glycation end-products (RAGE), the Toll-like receptor 4 (TLR4) and the S100 calcium-binding protein A9 (S100A9), quantified by ELISA; (3) protection against Aβ oligomer-induced neuronal cell death, using trypan blue to measure cell death in a murine neuronal cell line; (4) inhibition of TLR4 activation by S100A9, using a human TLR4 reporter cell line. We selected a 27-mer lead peptide that fulfilled these four criteria. This lead peptide is a privileged structure that displays inherent multitarget activity. This peptide is expected to significantly impact cognitive decline in mouse models of Alzheimer’s disease, by targeting both neuroinflammation and neurodegeneration.

Plasma protein biomarkers for primary graft dysfunction after lung transplantation: a single-center cohort analysis

The clinical use of circulating biomarkers for primary graft dysfunction (PGD) after lung transplantation has been limited. In a prospective single-center cohort, we examined the use of plasma protein biomarkers as indicators of PGD severity and duration after lung transplantation. The study comprised 40 consecutive lung transplant patients who consented to blood sample collection immediately pretransplant and at 6, 24, 48, and 72 h after lung transplant. An expert grader determined the severity and duration of PGD and scored PGD at T0 (6 h after reperfusion), T24, T48, and T72 h post-reperfusion using the 2016 ISHLT consensus guidelines. A bead-based multiplex assay was used to measure 27 plasma proteins including cytokines, growth factors, and chemokines. Enzyme-linked immunoassay was used to measure cell injury markers including M30, M65, soluble receptor of advanced glycation end-products (sRAGE), and plasminogen activator inhibitor-1 (PAI-1). A pairwise comparisons analysis was used to assess differences in protein levels between PGD severity scores (1, 2, and 3) at T0, T24, T48, and T72 h. Sensitivity and temporal analyses were used to explore the association of protein expression patterns and PGD3 at T48–72 h (the most severe, persistent form of PGD). We used the Benjamini–Hochberg method to adjust for multiple testing. Of the 40 patients, 22 (55%) had PGD3 at some point post-transplant from T0 to T72 h; 12 (30%) had PGD3 at T48–72 h. In the pairwise comparison, we identified a robust plasma protein expression signature for PGD severity. In the sensitivity analysis, using a linear model for microarray data, we found that differential perioperative expression of IP-10, MIP1B, RANTES, IL-8, IL-1Ra, G-CSF, and PDGF-BB correlated with PGD3 development at T48–72 h (FDR < 0.1 and p < 0.05). In the temporal analysis, using linear mixed modeling with overlap weighting, we identified unique protein patterns in patients who did or did not develop PGD3 at T48–72 h. Our findings suggest that unique inflammatory protein expression patterns may be informative of PGD severity and duration. PGD biomarker panels may improve early detection of PGD, predict its clinical course, and help monitor treatment efficacy in the current era of lung transplantation.

Circulating Myeloid Cell-derived Extracellular Vesicles as Mediators of Indirect Acute Lung Injury.

Blood-borne myeloid cells, neutrophils and monocytes, play a central role in the development of indirect acute lung injury (ALI) during sepsis and noninfectious systemic inflammatory response syndrome. By contrast, the contribution of circulating myeloid cell-derived extracellular vesicles (EVs) to ALI is unknown, despite acute increases in their numbers during sepsis and systemic inflammatory response syndrome. Here, we investigated the direct role of circulating myeloid-EVs in ALI using a mouse isolated perfused lung system and a human cell coculture model of pulmonary vascular inflammation consisting of lung microvascular endothelial cells and peripheral blood mononuclear cells. Total and immunoaffinity-isolated myeloid (CD11b+) and platelet (CD41+) EVs were prepared from the plasma of intravenous LPS-injected endotoxemic donor mice and transferred directly into recipient lungs. Two-hour perfusion of lungs with unfractionated EVs from a single donor induced pulmonary edema formation and increased perfusate concentrations of RAGE (receptor for advanced glycation end products), consistent with lung injury. These responses were abolished in the lungs of monocyte-depleted mice. The isolated myeloid- but not platelet-EVs produced a similar injury response and the acute intravascular release of proinflammatory cytokines and endothelial injury markers. In the invitro human coculture model, human myeloid- (CD11b+) but not platelet- (CD61+) EVs isolated from LPS-stimulated whole blood induced acute proinflammatory cytokine production and endothelial activation. These findings implicate circulating myeloid-EVs as acute mediators of pulmonary vascular inflammation and edema, suggesting an alternative therapeutic target for attenuation of indirect ALI.

Silymarin reduces retinal microvascular damage in streptozotocin-induced diabetic rats

Diabetic retinopathy is a severe microvascular problem in diabetes mellitus. Silymarin is a flavonoid compound, and according to previous studies, it is a bioactive compound with potent antioxidant and anti-inflammatory properties. This investigation aims to peruse the impact of silymarin against diabetic retinopathy in streptozotocin (STZ)-provoked rats. Thirty-two adult male Wistar rats were randomly allocated into the control group, STZ group, STZ + silymarin (50 mg/kg), and STZ + silymarin (100 mg/kg). STZ rats received silymarin every day until 2 months after diabetes induction. The serum and retinal tissues were collected 2 months after silymarin treatment to determine biochemical and molecular analyses. Silymarin markedly lowered the serum glucose concentration in diabetic rats. Silymarin reduced the increased levels of advanced glycosylated end products (AGEs), the receptors for AGEs (RAGE), and reactive oxygen species (ROS) in diabetic rats. Silymarin also attenuated the phosphorylation of p38 MAP kinase and nuclear factor (NF)-κB p65 and diminished diabetes-induced overexpression of inflammatory cytokines, vascular endothelial growth factor (VEGF), adhesion molecules, and extracellular matrix proteins in STZ rats. Our data suggested that silymarin has protective effects against diabetic retinopathy, which might be related to the inhibition of the AGEs/RAGE axis and its antioxidant and anti-inflammatory activities.

Effects of RAGE Deletion on the Cardiac Transcriptome during Aging.

Cardiac aging is characterized by increased cardiomyocyte hypertrophy, myocardial stiffness, and fibrosis, which enhance cardiovascular risk. The receptor for advanced glycation end-products (RAGE) is involved in several age-related diseases. RAGE knockout (Rage−/−) mice show an acceleration of cardiac dimension changes and interstitial fibrosis with aging. This study identifies the age-associated cardiac gene expression signature induced by RAGE deletion. We analyzed the left ventricle transcriptome of 2.5-(Young), 12-(Middle age, MA), and 21-(Old) months-old female Rage−/− and C57BL/6N (WT) mice. By comparing Young, MA, and Old Rage−/− versus age-matched WT mice, we identified 122, 192, and 12 differently expressed genes, respectively. Functional inference analysis showed that RAGE deletion is associated with: (i) down-regulation of genes involved in antigen processing and presentation of exogenous antigen, adaptive immune response, and cellular responses to interferon beta and gamma in Young animals; (ii) up-regulation of genes related to fatty acid oxidation, cardiac structure remodeling and cellular response to hypoxia in MA mice; (iii) up-regulation of few genes belonging to complement activation and triglyceride biosynthetic process in Old animals. Our findings show that the age-dependent cardiac phenotype of Rage−/− mice is associated with alterations of genes related to adaptive immunity and cardiac stress pathways.

Distinct roles of HMGB1 in the regulation of P‑glycoprotein expression in the liver and kidney of mice with lipopolysaccharide‑induced inflammation

The role of high mobility group box 1 (HMGB1) in the regulation of efflux transporters in the liver and kidney remains unclear, although it has been reported that HMGB1 can increase P‑glycoprotein (P‑gp) expression in the brain. The present study aimed to clarify the involvement of HMGB1 in the regulation of P‑gp expression in the liver and kidney of mice with lipopolysaccharide (LPS)‑induced inflammation. Mice were treated with LPS or LPS + glycyrrhizin (GL); GL is as an HMGB1 inhibitor. Subsequently, the expression levels of transporters, such as P‑gp, and HMGB1 receptors, such as toll‑like receptor (TLR)4 and receptor for advanced glycation end‑products (RAGE), were determined by quantitative PCR and LC‑MS/MS‑based targeted proteomics. For the invitro study, HepG2 and KMRC‑1 cells were used, as was a co‑culture of KMRC‑1 and differentiated THP‑1 cells. The mRNA and protein expression levels of Mdr1a and Tlr4 in the kidneys of LPS + GL‑treated mice were significantly decreased compared with those in LPS mice. The results indicated that HMGB1 had little effect on the expression of Mdr1a and Tlr4 in the liver, since there was little change in of Mdr1a and Mdr1b expression between the LPS and LPS + GL‑treated mice. Notably, regarding MDR1 mRNA expression, KMRC‑1 cells were more responsive to LPS than HepG2 cells, and KMRC‑1 cells treated with LPS exhibited increased levels compared with control KMRC‑1 cells. In differentiated THP‑1 cells, LPS treatment decreased the mRNA expression levels of TLR4, whereas they were restored to control levels by HMGB1. In conclusion, HMGB1 in the plasma and TLR4 in macrophages may be involved in the regulation of P‑gp expression in the kidneys of inflamed mice.