Small-molecule antagonism of the interaction of the RAGE cytoplasmic domain with DIAPH1 reduces diabetic complications in mice

USP10 alleviates Nε-carboxymethyl-lysine-induced vascular calcification and atherogenesis in diabetes mellitus by promoting AMPK activation

Vascular calcification (VC) is a characteristic feature in patients with diabetes mellitus (DM) and is closely associated with the osteogenic differentiation of vascular smooth muscle cells (VSMCs). Ubiquitin-Specific Protease 10 (USP10) has been shown to regulate multiple cellular processes; however, its relationship with diabetic VC remains unclear. This study aims to elucidate the role of USP10 in VC development and the underlying regulatory mechanisms. Nε-carboxymethyl lysine (CML) was significantly increased in calcified ateries from diabetic atherosclerosis ApoE-/- mice fed with high-fat diets. CML downregulated USP10 expression in VSMCs and calcified mice coronary arteries, as assessd by Western blotting, RT-qPCR,immunofluorescence and immunohistochemistry. Loss-and gain-of-function experiments were conducted both in vitro and in vivo to verify the biological functions of USP10. Ectopic expression of USP10 mitigated the severity of VC. With regard to the mechanism, the interaction between USP10 and AMPKα was investigated through double-label immunofluorescence and Co-immunoprecipitation. In vitro ubiquitination assay revealed that USP10 was capable of mediating AMPKα ubiquitination and caused increased AMPKα phosphorylation level at Thr172. Moreover, the anticalcification effect of USP10 was reversed by pharmacological inhibition of AMPK signaling pathway. The current fundings suggest an important role of USP10 in diabetic VC progression, at least in part, via mediating the ubiquitination and activation of AMPKα. USP10 may serve as a novel therapeutic target for the treatment of diabetic VC.

Investigation of N-Glycan Functions in Receptor for Advanced Glycation End Products V Domain through Chemical Glycoprotein Synthesis

The receptor for advanced glycation end products (RAGE) plays a crucial role in inflammation-related pathways and various chronic diseases. Despite the recognized significance of N-glycosylation in the ligand-binding V domain (VD) of RAGE, a comprehensive understanding of the site-activity and structure-activity relationships is lacking due to the challenges in obtaining homogeneous glycoprotein samples through biological expression. Here, we combined chemical and chemoenzymatic approaches to synthesize RAGE-VD and its congeners with Asn3-glycosylation by incorporating precise N-glycan structures. Evaluation of these samples revealed that, in comparison to other RAGE-VD forms, α2,6-sialylated N-glycosylation at the Asn3 site results in more potent inhibition of HMGB1-induced nuclear factor-κB (NF-κB) expression in RAGE-overexpressing cells. Hydrogen/deuterium exchange-mass spectrum analysis revealed a sialylated RAGE-VD-induced interaction region within HMGB1. Conversely, Asn3 N-glycosylation in VD has negligible effects on RAGE-VD/S100B interactions. This study established an approach for accessing homogeneously glycosylated RAGE-VD and explored the modulatory effects of N-glycosylation on the interactions between RAGE-VD and its ligand proteins.

Extracellular NCOA4 is a mediator of septic death by activating the AGER-NFKB pathway

Sepsis, a life-threatening condition resulting from a dysregulated response to pathogen infection, poses a significant challenge in clinical management. Here, we report a novel role for the autophagy receptor NCOA4 in the pathogenesis of sepsis. Activated macrophages and monocytes secrete NCOA4, which acts as a mediator of septic death in mice. Mechanistically, lipopolysaccharide, a major component of the outer membrane of Gram-negative bacteria, induces NCOA4 secretion through autophagy-dependent lysosomal exocytosis mediated by ATG5 and MCOLN1. Moreover, bacterial infection with E. coli or S. enterica leads to passive release of NCOA4 during GSDMD-mediated pyroptosis. Upon release, extracellular NCOA4 triggers the activation of the proinflammatory transcription factor NFKB/NF-κB by promoting the degradation of NFKBIA/IκB molecules. This process is dependent on the pattern recognition receptor AGER, rather than TLR4. In vivo studies employing endotoxemia and polymicrobial sepsis mouse models reveal that a monoclonal neutralizing antibody targeting NCOA4 or AGER delays animal death, protects against organ damage, and attenuates systemic inflammation. Furthermore, elevated plasma NCOA4 levels in septic patients, particularly in non-survivors, correlate positively with the sequential organ failure assessment score and concentrations of lactate and proinflammatory mediators, such as TNF, IL1B, IL6, and HMGB1. These findings demonstrate a previously unrecognized role of extracellular NCOA4 in inflammation, suggesting it as a potential therapeutic target for severe infectious diseases. Abbreviation: BMDMs: bone marrow-derived macrophages; BUN: blood urea nitrogen; CLP: cecal ligation and puncture; ELISA: enzyme-linked immunosorbent assay; LPS: lipopolysaccharide; NO: nitric oxide; SOFA: sequential organ failure assessment.

Eugenol-loaded polyurethane gelatin dressing for efficient angiogenesis and antibacterial effects in refractory diabetic wound defect healing

The amelioration of refractory diabetic ulcers presents a formidable conundrum on a global scale, attributable to the elevated peril of contagion and protracted convalescence durations. Within the purlieus of this reparative epoch, the deployment of efficacious wound coverings endowed with both angiogenesis and antibacterial attributes is of paramount significance. Hydrogel wound dressings are distinguished by their elevated biocompatibility, adhesive tenacity, and innate regenerative capacity. Eugenol, a substance distilled from the blossoms of the lilac, serves as a precursor to metformin and is known to impede the genesis of reactive oxygen species. Although its antibacterial effects have been extensively chronicled, the angiogenic ramifications of eugenol within the context of wound remediation remain under-investigated. This research aimed to evaluate the effectiveness of eugenol-infused hydrogel as a wound dressing material. In this context, polyurethane gelatin (PG) was combined with eugenol at concentrations of 0.5% and 1%, creating PG-eugenol hydrogel mixtures with specific mass ratios for both in vivo and in vitro assessments. The in vivo studies indicated that hydrogels infused with eugenol expedited diabetic wound healing by fostering angiogenesis. Enhanced healing was noted, attributed to improved antibacterial and angiogenic properties, increased cell proliferation, tissue regeneration, and re-epithelialization. The in vitro analyses revealed that eugenol-enriched hydrogels stimulated the growth of fibroblasts (HFF-1) and human umbilical vein endothelial cells (HUVECs) and exhibited antibacterial characteristics. This investigation confirms the potential of eugenol-laden hydrogels in effectively treating diabetic wound defects.

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.

Novel insights into RAGE signaling pathways during the progression of amyotrophic lateral sclerosis in RAGE-deficient SOD1 G93A mice

Amyotrophic lateral sclerosis (ALS) is neurodegenerative disease characterized by a progressive loss of motor neurons resulting in paralysis and muscle atrophy. One of the most prospective hypothesis on the ALS pathogenesis suggests that excessive inflammation and advanced glycation end-products (AGEs) accumulation play a crucial role in the development of ALS in patients and SOD1 G93A mice. Hence, we may speculate that RAGE, receptor for advanced glycation end-products and its proinflammatory ligands such as: HMGB1, S100B and CML contribute to ALS pathogenesis. The aim of our studies was to decipher the role of RAGE as well as provide insight into RAGE signaling pathways during the progression of ALS in SOD1 G93A and RAGE-deficient SOD1 G93A mice. In our study, we observed alternations in molecular pattern of proinflammatory RAGE ligands during progression of disease in RAGE KO SOD1 G93A mice compared to SOD1 G93A mice. Moreover, we observed that the amount of beta actin (ACTB) as well as Glial fibrillary acidic protein (GFAP) was elevated in SOD1 G93A mice when compared to mice with deletion of RAGE. These data contributes to our understanding of implications of RAGE and its ligands in pathogenesis of ALS and highlight potential targeted therapeutic interventions at the early stage of this devastating disease. Moreover, inhibition of the molecular cross-talk between RAGE and its proinflammatory ligands may abolish neuroinflammation, gliosis and motor neuron damage in SOD1 G93A mice. Hence, we hypothesize that attenuated interaction of RAGE with its proinflammatory ligands may improve well-being and health status during ALS in SOD1 G93A mice. Therefore, we emphasize that the inhibition of RAGE signaling pathway may be a therapeutic target for neurodegenerative diseases.

Advances in secondary prevention mechanisms of macrovascular complications in type 2 diabetes mellitus patients: a comprehensive review

Type 2 diabetes mellitus (T2DM) poses a significant global health burden. This is particularly due to its macrovascular complications, such as coronary artery disease, peripheral vascular disease, and cerebrovascular disease, which have emerged as leading contributors to morbidity and mortality. This review comprehensively explores the pathophysiological mechanisms underlying these complications, protective strategies, and both existing and emerging secondary preventive measures. Furthermore, we delve into the applications of experimental models and methodologies in foundational research while also highlighting current research limitations and future directions. Specifically, we focus on the literature published post-2020 concerning the secondary prevention of macrovascular complications in patients with T2DM by conducting a targeted review of studies supported by robust evidence to offer a holistic perspective.

The RAGE/DIAPH1 axis: mediator of obesity and proposed biomarker of human cardiometabolic disease

Overweight and obesity are leading causes of cardiometabolic dysfunction. Despite extensive investigation, the mechanisms mediating the increase in these conditions are yet to be fully understood. Beyond the endogenous formation of advanced glycation endproducts (AGEs) in overweight and obesity, exogenous sources of AGEs accrue through the heating, production, and consumption of highly processed foods. Evidence from cellular and mouse model systems indicates that the interaction of AGEs with their central cell surface receptor for AGE (RAGE) in adipocytes suppresses energy expenditure and that AGE/RAGE contributes to increased adipose inflammation and processes linked to insulin resistance. In human subjects, the circulating soluble forms of RAGE, which are mutable, may serve as biomarkers of obesity and weight loss. Antagonists of RAGE signalling, through blockade of the interaction of the RAGE cytoplasmic domain with the formin, Diaphanous-1 (DIAPH1), target aberrant RAGE activities in metabolic tissues. This review focuses on the potential roles for AGEs and other RAGE ligands and RAGE/DIAPH1 in the pathogenesis of overweight and obesity and their metabolic consequences.

Tetrahedral Framework Nucleic Acids Based Small Interfering RNA Targeting Receptor for Advanced Glycation End Products for Diabetic Complications Treatment

Complications arising from diabetes can threaten multiple organs. Advanced glycation end products (AGEs) play a significant role in inducing these complications. Highly processed diets and hyperglycemia facilitate the accumulation of AGEs in the body. Interaction between AGEs and their main receptor (RAGE) initiates the transmission of intracellular inflammatory and cell death signals, which ultimately lead to complications. To counter AGEs-induced damage, we developed an siRNA-binding tetrahedral framework nucleic acids (TDN) system, termed Tsi, which combines the potent cell membrane penetrability and serum stability of TDN with the gene-targeting specificity of siRNA-RAGE. Tsi effectively and persistently downregulates the expression of RAGE, thereby suppressing inflammation by blocking the NF-κB pathway as well as exhibiting antioxidant functions. Furthermore, Tsi regulates the pyroptosis state of macrophages via the NLRP3/caspase-1 axis, which inhibits the spread of cell death signals and maintains homeostasis. This is of great significance for the synergistic treatment strategy for systemic complications in patients with refractory hyperglycemia. In summary, this study describes a nanomedicine that targets the RAGE and suppresses AGE-induced inflammation. This nucleic acid drug holds long-lasting efficacy and is independent of lowering hyperglycemia, which provides a strategy for the treatment of diabetic complications and age-related diseases.

Involvement of the Receptor for Advanced Glycation End Products (RAGE) in high fat-high sugar diet-induced anhedonia in rats

Clinical and basic science investigation indicates a link between insulin resistance and anhedonia. Previous results of this laboratory point to impaired nucleus accumbens (NAc) insulin signaling as an underpinning of diet-induced anhedonia, based on use of a glucose lick microstructure assay. The present study evaluated whether advanced glycation end products (AGEs) and their receptor (RAGE), known to mediate obesogenic diet-induced inflammation and pathological metabolic conditions, are involved in this behavioral change. Six weeks maintenance of male and female rats on a high fat-high sugar liquid diet (chocolate Ensure) increased body weight gain, and markedly increased circulating insulin and leptin, but induced anhedonia (decreased first minute lick rate and lick burst size) in males only. In these subjects, anhedonia correlated with plasma concentrations of insulin. Although the diet did not alter plasma or NAc AGEs, or the expression of RAGE in the NAc, marginally significant correlations were seen between anhedonia and plasma content of several AGEs and NAc RAGE. Importantly, a small molecule RAGE antagonist, RAGE229, administered twice daily by oral gavage, prevented diet-induced anhedonia. This beneficial effect was associated with improved adipose function, reflected in the adiponectin/leptin ratio, and increased pCREB/total CREB in the NAc, and a shift in the pCREB correlation with pThr34-DARPP-32 from near-zero to strongly positive, such that both phospho-proteins correlated with the rescued hedonic response. This set of findings suggests that the receptor/signaling pathway and cell type underlying the RAGE229-mediated increase in pCREB may mediate anhedonia and its prevention. The possible role of adipose tissue as a locus of diet-induced RAGE signaling, and source of circulating factors that target NAc to modify hedonic reactivity are discussed.

Effects of acute aerobic exercise on circulating sTLR and sRAGE profiles in normal- and abnormal-glucose-tolerant individuals

BMI-matched normal- (NGT, n = 10, 41 ± 4y, 35.6 ± 3.0 kg/m2 ) and abnormal-glucose-tolerant (AGT, n = 16, 51 ± 3y, 34.3 ± 1.5 kg/m2 ) participants were evaluated for body composition, metabolic health (oral glucose tolerance test [OGTT]), and VO2 max. Participants also completed a treadmill walking test at 65% VO2 max for 30 min. Total sRAGE, esRAGE, sTLR2, and sTLR4 were assessed via ELISA, and cRAGE was calculated. AGT exhibited greater (p < 0.05) body fat % (+24%), fasting plasma glucose (+37%), OGTT AUC (+59%), and HOMA-IR (+55%) and lower (p < 0.05) VO2 max (-24%). sTLR2 was 33% lower in AGT than NGT (main effect, p = 0.034). However, sTLR2 did not change (p > 0.05) following AE. sTLR4 tended to be 36% lower in AGT than NGT (main effect, p = 0.096) and did not change following AE (p > 0.05). Total sRAGE and isoforms were similar (p > 0.05) between groups and did not change following AE (p > 0.05). sTLR2 was correlated with (p < 0.05) basal BG (r = -0.505) and OGTT AUC (r = -0.687). sTLR4 was correlated with basal BG (p < 0.10, r = -0.374) and OGTT AUC (p < 0.05, r = -0.402). Linear regressions were predictive of sTLRs in the basal state (sTLR2: R2  = 0.641, p = 0.01; sTLR4: R2  = 0.566, p = 0.037) and after acute exercise state (sTLR2: R2  = 0.681, p = 0.004, sTLR4: R2  = 0.568, p = 0.036).These findings show circulating sTLR profiles are disrupted in AGT and acute AE minimally modulates their levels.

DIAPH1-MFN2 interaction regulates mitochondria-SR/ER contact and modulates ischemic/hypoxic stress

Inter-organelle contact and communication between mitochondria and sarco/endoplasmic reticulum (SR/ER) maintain cellular homeostasis and are profoundly disturbed during tissue ischemia. We tested the hypothesis that the formin Diaphanous-1 (DIAPH1), which regulates actin dynamics, signal transduction and metabolic functions, contributes to these processes. We demonstrate that DIAPH1 interacts directly with Mitofusin-2 (MFN2) to shorten mitochondria-SR/ER distance, thereby enhancing mitochondria-ER contact in cells including cardiomyocytes, endothelial cells and macrophages. Solution structure studies affirm the interaction between the Diaphanous Inhibitory Domain and the cytosolic GTPase domain of MFN2. In male rodent and human cardiomyocytes, DIAPH1-MFN2 interaction regulates mitochondrial turnover, mitophagy, and oxidative stress. Introduction of synthetic linker construct, which shorten the mitochondria-SR/ER distance, mitigated the molecular and functional benefits of DIAPH1 silencing in ischemia. This work establishes fundamental roles for DIAPH1-MFN2 interaction in the regulation of mitochondria-SR/ER contact networks. We propose that targeting pathways that regulate DIAPH1-MFN2 interactions may facilitate recovery from tissue ischemia.

Pharmacological antagonism of receptor for advanced glycation end products signaling promotes thermogenesis, healthful body mass and composition, and metabolism in mice

OBJECTIVE

Optimal body mass and composition as well as metabolic fitness require tightly regulated and interconnected mechanisms across tissues. Disturbances in these regulatory networks tip the balance between metabolic health versus overweight and obesity and their complications. The authors previously demonstrated roles for the receptor for advanced glycation end products (RAGE) in obesity, as global- or adipocyte-specific deletion of Ager (the gene encoding RAGE) protected mice from high-fat diet-induced obesity and metabolic dysfunction.

METHODS

To explore translational strategies evoked by these observations, a small molecule antagonist of RAGE signaling, RAGE229, was administered to lean mice and mice with obesity undergoing diet-induced weight loss. Body mass and composition and whole body and adipose tissue metabolism were examined.

RESULTS

This study demonstrates that antagonism of RAGE signaling reduced body mass and adiposity and improved glucose, insulin, and lipid metabolism in lean male and female mice and in male mice with obesity undergoing weight loss. In adipose tissue and in human and mouse adipocytes, RAGE229 enhanced phosphorylation of protein kinase A substrates, which augmented lipolysis, mitochondrial function, and thermogenic programs.

CONCLUSIONS

Pharmacological antagonism of RAGE signaling is a potent strategy to optimize healthful body mass and composition and metabolic fitness.

The AGE-RAGE Axis and the Pathophysiology of Multimorbidity in COPD

Chronic obstructive pulmonary disease (COPD) is a disease of the airways and lungs due to an enhanced inflammatory response, commonly caused by cigarette smoking. Patients with COPD are often multimorbid, as they commonly suffer from multiple chronic (inflammatory) conditions. This intensifies the burden of individual diseases, negatively affects quality of life, and complicates disease management. COPD and comorbidities share genetic and lifestyle-related risk factors and pathobiological mechanisms, including chronic inflammation and oxidative stress. The receptor for advanced glycation end products (RAGE) is an important driver of chronic inflammation. Advanced glycation end products (AGEs) are RAGE ligands that accumulate due to aging, inflammation, oxidative stress, and carbohydrate metabolism. AGEs cause further inflammation and oxidative stress through RAGE, but also through RAGE-independent mechanisms. This review describes the complexity of RAGE signaling and the causes of AGE accumulation, followed by a comprehensive overview of alterations reported on AGEs and RAGE in COPD and in important co-morbidities. Furthermore, it describes the mechanisms by which AGEs and RAGE contribute to the pathophysiology of individual disease conditions and how they execute crosstalk between organ systems. A section on therapeutic strategies that target AGEs and RAGE and could alleviate patients from multimorbid conditions using single therapeutics concludes this review.

Photothermal Controlled-Release Immunomodulatory Nanoplatform for Restoring Nerve Structure and Mechanical Nociception in Infectious Diabetic Ulcers

Infectious diabetic ulcers (IDU) require anti-infection, angiogenesis, and nerve regeneration therapy; however, the latter has received comparatively less research attention than the former two. In particular, there have been few reports on the recovery of mechanical nociception. In this study, a photothermal controlled-release immunomodulatory hydrogel nanoplatform is tailored for the treatment of IDU. Due to a thermal-sensitive interaction between polydopamine-reduced graphene oxide (pGO) and the antibiotic mupirocin, excellent antibacterial efficacy is achieved through customized release kinetics. In addition, Trem2⁺ macrophages recruited by pGO regulate collagen remodeling and restore skin adnexal structures to alter the fate of scar formation, promote angiogenesis, accompanied by the regeneration of neural networks, which ensures the recovery of mechanical nociception and may prevent the recurrence of IDU at the source. In all, a full-stage strategy from antibacterial, immune regulation, angiogenesis, and neurogenesis to the recovery of mechanical nociception, an indispensable neural function of skin, is introduced to IDU treatment, which opens up an effective and comprehensive therapy for refractory IDU.

RAGE pathways play an important role in regulation of organ fibrosis

Organ fibrosis is a pathological process of fibroblast activation and excessive deposition of extracellular matrix after persistent tissue injury and therefore is a common endpoint of many organ pathologies. Multiple cellular types and soluble mediators, including chemokines, cytokines and non-peptidic factors, are implicated in fibrogenesis and the remodeling of tissue architecture. The molecular basis of the fibrotic process is complex and consists of closely intertwined signaling networks. Research has strived for a better understanding of these pathological mechanisms to potentially reveal novel therapeutic targets for fibrotic diseases. In light of new knowledge, the receptor for advanced glycation end products (RAGE) emerged as an important candidate for the regulation of a wide variety of cellular functions related to fibrosis, including inflammation, cell proliferation, apoptosis, and angiogenesis. RAGE is a pattern recognition receptor that binds a broad range of ligands such as advanced glycation end products, high mobility group box-1, S-100 calcium-binding protein and amyloid beta protein. Although the link between RAGE and fibrosis has been established, the exact mechanisms need be investigated in further studies. The aim of this review is to collect all available information about the intricate function of RAGE and its signaling cascades in the pathogenesis of fibrotic diseases within different organs. In addition, to the major ligands and signaling pathways, we discuss potential strategies for targeting RAGE in fibrosis. We emphasize the functional links between RAGE, inflammation and fibrosis that may guide further studies and the development of improved therapeutic drugs.

RAGE Inhibitors in Neurodegenerative Diseases

Nonenzymatic reactions of reducing sugars with primary amino groups of amino acids, proteins, and nucleic acids, followed by oxidative degradations would lead to the formation of advanced glycation endproducts (AGEs). The AGEs exert multifactorial effects on cell damage leading to the onset of neurological disorders. The interaction of AGEs with the receptors for advanced glycation endproducts (RAGE) contribute to the activation of intracellular signaling and the expression of the pro-inflammatory transcription factors and various inflammatory cytokines. This inflammatory signaling cascade is associated with various neurological diseases, including Alzheimer's disease (AD), secondary effects of traumatic brain injury (TBI), amyotrophic lateral sclerosis (ALS), and diabetic neuropathy, and other AGE-related diseases, including diabetes and atherosclerosis. Furthermore, the imbalance of gut microbiota and intestinal inflammation are also associated with endothelial dysfunction, disrupted blood-brain barrier (BBB) and thereby the onset and progression of AD and other neurological diseases. AGEs and RAGE play an important role in altering the gut microbiota composition and thereby increase the gut permeability and affect the modulation of the immune-related cytokines. The inhibition of the AGE-RAGE interactions, through small molecule-based therapeutics, prevents the inflammatory cascade of events associated with AGE-RAGE interactions, and thereby attenuates the disease progression. Some of the RAGE antagonists, such as Azeliragon, are currently in clinical development for treating neurological diseases, including AD, although currently there have been no FDA-approved therapeutics based on the RAGE antagonists. This review outlines the AGE-RAGE interactions as a leading cause of the onset of neurological diseases and the current efforts on developing therapeutics for neurological diseases based on the RAGE antagonists.

DIAPH1 mediates progression of atherosclerosis and regulates hepatic lipid metabolism in mice

Atherosclerosis evolves through dysregulated lipid metabolism interwoven with exaggerated inflammation. Previous work implicating the receptor for advanced glycation end products (RAGE) in atherosclerosis prompted us to explore if Diaphanous 1 (DIAPH1), which binds to the RAGE cytoplasmic domain and is important for RAGE signaling, contributes to these processes. We intercrossed atherosclerosis-prone Ldlr-/- mice with mice devoid of Diaph1 and fed them Western diet for 16 weeks. Compared to male Ldlr-/- mice, male Ldlr-/- Diaph1-/- mice displayed significantly less atherosclerosis, in parallel with lower plasma concentrations of cholesterol and triglycerides. Female Ldlr-/- Diaph1-/- mice displayed significantly less atherosclerosis compared to Ldlr-/- mice and demonstrated lower plasma concentrations of cholesterol, but not plasma triglycerides. Deletion of Diaph1 attenuated expression of genes regulating hepatic lipid metabolism, Acaca, Acacb, Gpat2, Lpin1, Lpin2 and Fasn, without effect on mRNA expression of upstream transcription factors Srebf1, Srebf2 or Mxlipl in male mice. We traced DIAPH1-dependent mechanisms to nuclear translocation of SREBP1 in a manner independent of carbohydrate- or insulin-regulated cues but, at least in part, through the actin cytoskeleton. This work unveils new regulators of atherosclerosis and lipid metabolism through DIAPH1.

Obesity and Overweight: Probing Causes, Consequences, and Novel Therapeutic Approaches Through the American Heart Association's Strategically Focused Research Network

As the worldwide prevalence of overweight and obesity continues to rise, so too does the urgency to fully understand mediating mechanisms, to discover new targets for safe and effective therapeutic intervention, and to identify biomarkers to track obesity and the success of weight loss interventions. In 2016, the American Heart Association sought applications for a Strategically Focused Research Network (SFRN) on Obesity. In 2017, 4 centers were named, including Johns Hopkins University School of Medicine, New York University Grossman School of Medicine, University of Alabama at Birmingham, and Vanderbilt University Medical Center. These 4 centers were convened to study mechanisms and therapeutic targets in obesity, to train a talented cadre of American Heart Association SFRN-designated fellows, and to initiate and sustain effective and enduring collaborations within the individual centers and throughout the SFRN networks. This review summarizes the central themes, major findings, successful training of highly motivated and productive fellows, and the innovative collaborations and studies forged through this SFRN on Obesity. Leveraging expertise in in vitro and cellular model assays, animal models, and humans, the work of these 4 centers has made a significant impact in the field of obesity, opening doors to important discoveries, and the identification of a future generation of obesity-focused investigators and next-step clinical trials. The creation of the SFRN on Obesity for these 4 centers is but the beginning of innovative science and, importantly, the birth of new collaborations and research partnerships to propel the field forward.

Oral Nanocurcumin Alone or in Combination with Insulin Alleviates STZ-Induced Diabetic Neuropathy in Rats

Diabetes mellitus (DM), a multifaceted metabolic disorder if not managed properly leads to secondary complications. Diabetic peripheral neuropathy (DPN) is one such complication caused by nerve damage that cannot be reversed but can be delayed. Recently, diabetes patients are using dietary supplements, although there remains a general skepticism about this practice. Curcumin (CUR), one such supplement can help prevent underlying low-grade inflammation in diabetes, but it is plagued by poor oral bioavailability. To better understand the role of bioavailability in clinical outcomes, we have tested double-headed nanosystems containing curcumin (nCUR) on DPN. Because CUR does not influence glucose levels, we have also tested the effects of nCUR combined with long-acting subcutaneous insulin (INS). nCUR with or without INS alleviates DPN at two times lower dose than unformulated CUR, as indicated by qualitative and quantitative analysis of the hind paw, sciatic nerve, spleen, and L4-6 spinal cord. In addition, nCUR and nCUR+INS preserve hind paw nerve axons as evident by the Bielschowsky silver stain and intraepidermal nerve fibers (IENF) density measured by immunofluorescence. The mechanistic studies further corroborated the results, where nCUR or nCUR+INS showed a significant decrease in TUNEL positive cells, mRNA expression of NLRP3, IL-1β, and macrophage infiltration while preserving nestin and NF200 expression in the sciatic nerve. Together, the data confirms that CUR bioavailability is proportional to clinical outcomes and INS alone may not be one of the solutions for DM. This study highlights the potential of nCUR with or without INS in alleviating DPN and warrants further investigation.

Research Advances on the Damage Mechanism of Skin Glycation and Related Inhibitors

Our skin is an organ with the largest contact area between the human body and the external environment. Skin aging is affected directly by both endogenous factors and exogenous factors (e.g., UV exposure). Skin saccharification, a non-enzymatic reaction between proteins, e.g., dermal collagen and naturally occurring reducing sugars, is one of the basic root causes of endogenous skin aging. During the reaction, a series of complicated glycation products produced at different reaction stages and pathways are usually collectively referred to as advanced glycation end products (AGEs). AGEs cause cellular dysfunction through the modification of intracellular molecules and accumulate in tissues with aging. AGEs are also associated with a variety of age-related diseases, such as diabetes, cardiovascular disease, renal failure (uremia), and Alzheimer's disease. AGEs accumulate in the skin with age and are amplified through exogenous factors, e.g., ultraviolet radiation, resulting in wrinkles, loss of elasticity, dull yellowing, and other skin problems. This article focuses on the damage mechanism of glucose and its glycation products on the skin by summarizing the biochemical characteristics, compositions, as well as processes of the production and elimination of AGEs. One of the important parts of this article would be to summarize the current AGEs inhibitors to gain insight into the anti-glycation mechanism of the skin and the development of promising natural products with anti-glycation effects.

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.

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.

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

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

Pathophysiology of RAGE in inflammatory diseases

The receptor for advanced glycation end products (RAGE) is a non-specific multi-ligand pattern recognition receptor capable of binding to a range of structurally diverse ligands, expressed on a variety of cell types, and performing different functions. The ligand-RAGE axis can trigger a range of signaling events that are associated with diabetes and its complications, neurological disorders, cancer, inflammation and other diseases. Since RAGE is involved in the pathophysiological processes of many diseases, targeting RAGE may be an effective strategy to block RAGE signaling.

Glycation and a Spark of ALEs (Advanced Lipoxidation End Products) - Igniting RAGE/Diaphanous-1 and Cardiometabolic Disease

Obesity and non-alcoholic fatty liver disease (NAFLD) are on the rise world-wide; despite fervent advocacy for healthier diets and enhanced physical activity, these disorders persist unabated and, long-term, are major causes of morbidity and mortality. Numerous fundamental biochemical and molecular pathways participate in these events at incipient, mid- and advanced stages during atherogenesis and impaired regression of established atherosclerosis. It is proposed that upon the consumption of high fat/high sugar diets, the production of receptor for advanced glycation end products (RAGE) ligands, advanced glycation end products (AGEs) and advanced lipoxidation end products (ALEs), contribute to the development of foam cells, endothelial injury, vascular inflammation, and, ultimately, atherosclerosis and its consequences. RAGE/Diaphanous-1 (DIAPH1) increases macrophage foam cell formation; decreases cholesterol efflux and causes foam cells to produce and release damage associated molecular patterns (DAMPs) molecules, which are also ligands of RAGE. DAMPs stimulate upregulation of Interferon Regulatory Factor 7 (IRF7) in macrophages, which exacerbates vascular inflammation and further perturbs cholesterol metabolism. Obesity and NAFLD, characterized by the upregulation of AGEs, ALEs and DAMPs in the target tissues, contribute to insulin resistance, hyperglycemia and type two diabetes. Once in motion, a vicious cycle of RAGE ligand production and exacerbation of RAGE/DIAPH1 signaling ensues, which, if left unchecked, augments cardiometabolic disease and its consequences. This Review focuses on RAGE/DIAPH1 and its role in perturbation of metabolism and processes that converge to augur cardiovascular disease.

The RAGE/DIAPH1 Signaling Axis & Implications for the Pathogenesis of Diabetic Complications

Increasing evidence links the RAGE (receptor for advanced glycation end products)/DIAPH1 (Diaphanous 1) signaling axis to the pathogenesis of diabetic complications. RAGE is a multi-ligand receptor and through these ligand-receptor interactions, extensive maladaptive effects are exerted on cell types and tissues targeted for dysfunction in hyperglycemia observed in both type 1 and type 2 diabetes. Recent evidence indicates that RAGE ligands, acting as damage-associated molecular patterns molecules, or DAMPs, through RAGE may impact interferon signaling pathways, specifically through upregulation of IRF7 (interferon regulatory factor 7), thereby heralding and evoking pro-inflammatory effects on vulnerable tissues. Although successful targeting of RAGE in the clinical milieu has, to date, not been met with success, recent approaches to target RAGE intracellular signaling may hold promise to fill this critical gap. This review focuses on recent examples of highlights and updates to the pathobiology of RAGE and DIAPH1 in diabetic complications.

The Intestinal Microbiota and Metabolites in the Gut-Kidney-Heart Axis of Chronic Kidney Disease

Emerging evidences demonstrate the involvement of gut microbiota in the progression of chronic kidney disease (CKD) and CKD-associated complications including cardiovascular disease (CVD) and intestinal dysfunction. In this review, we discuss the interactions between the gut, kidney and heart in CKD state, and elucidate the significant role of intestinal microbiota in the gut-kidney-heart axis hypothesis for the pathophysiological mechanisms of these diseases, during which process mitochondria may serve as a potential therapeutic target. Dysregulation of this axis will lead to a vicious circle, contributing to CKD progression. Recent studies suggest novel therapies targeting gut microbiota in the gut-kidney-heart axis, including dietary intervention, probiotics, prebiotics, genetically engineered bacteria, fecal microbiota transplantation, bacterial metabolites modulation, antibiotics, conventional drugs and traditional Chinese medicine. Further, the identification of specific microbial communities and their corresponding pathophysiological metabolites and the illumination of the gut-kidney-heart axis may contribute to innovative basic research, clinical trials and therapeutic strategies against CKD progression and uremic complications in CKD patients.