Glucose-6-Phosphate Isomerase (G6PI) Mediates Hypoxia-Induced Angiogenesis in Rheumatoid Arthritis

Metabolic changes in fibroblast-like synoviocytes in rheumatoid arthritis: state of the art review

Fibroblast-like synoviocytes (FLS) are important components of the synovial membrane. They can contribute to joint damage through crosstalk with inflammatory cells and direct actions on tissue damage pathways in rheumatoid arthritis (RA). Recent evidence suggests that, compared with FLS in normal synovial tissue, FLS in RA synovial tissue exhibits significant differences in metabolism. Recent metabolomic studies have demonstrated that metabolic changes, including those in glucose, lipid, and amino acid metabolism, exist before synovitis onset. These changes may be a result of increased biosynthesis and energy requirements during the early phases of the disease. Activated T cells and some cytokines contribute to the conversion of FLS into cells with metabolic abnormalities and pro-inflammatory phenotypes. This conversion may be one of the potential mechanisms behind altered FLS metabolism. Targeting metabolism can inhibit FLS proliferation, providing relief to patients with RA. In this review, we aimed to summarize the evidence of metabolic changes in FLS in RA, analyze the mechanisms of these metabolic alterations, and assess their effect on RA phenotype. Finally, we aimed to summarize the advances and challenges faced in targeting FLS metabolism as a promising therapeutic strategy for RA in the future.

The HIF-1/ BNIP3 pathway mediates mitophagy to inhibit the pyroptosis of fibroblast-like synoviocytes in rheumatoid arthritis

BACKGROUND

Synovial hypoxia, a critical pathological characteristic of rheumatoid arthritis (RA), significantly contributes to synovitis and synovial hyperplasia. In response to hypoxic conditions, fibroblast-like synoviocytes (FLS) undergo adaptive changes involving gene expression modulation, with hypoxia-inducible factors (HIF) playing a pivotal role. The regulation of BCL2/adenovirus e1B 19 kDa protein interacting protein 3 (BNIP3) and nucleotide-binding oligomerization segment-like receptor family 3 (NLRP3) expression has been demonstrated to be regulated by HIF-1. The objective of this study was to examine the molecular mechanism that contributes to the aberrant activation of FLS in response to hypoxia. Specifically, the interaction between BNIP3-mediated mitophagy and NLRP3-mediated pyroptosis was conjointly highlighted.

METHODS

The research methodology employed Western blot and immunohistochemistry techniques to identify the occurrence of mitophagy in synovial tissue affected by RA. Additionally, the levels of mitophagy under hypoxic conditions were assessed using Western blot, immunofluorescence, quantitative polymerase chain reaction (qPCR), and CUT&Tag assays. Pyroptosis was observed through electron microscopy, fluorescence microscopy, and Western blot analysis. Furthermore, the quantity of reactive oxygen species (ROS) was measured. The silencing of HIF-1α and BNIP3 was achieved through the transfection of short hairpin RNA (shRNA) into cells.

RESULTS

In the present study, a noteworthy increase in the expression of BNIP3 and LC3B was observed in the synovial tissue of patients with RA. Upon exposure to hypoxia, FLS of RA exhibited BNIP3-mediated mitophagy and NLRP3 inflammasome-mediated pyroptosis. It appears that hypoxia regulates the expression of BNIP3 and NLRP3 through the transcription factor HIF-1. Additionally, the activation of mitophagy has been observed to effectively inhibit hypoxia-induced pyroptosis by reducing the intracellular levels of ROS.

CONCLUSION

In summary, the activation of FLS in RA patients under hypoxic conditions involves both BNIP3-mediated mitophagy and NLRP3 inflammasome-mediated pyroptosis. Additionally, mitophagy can suppress hypoxia-induced FLS pyroptosis by eliminating ROS and inhibiting the HIF-1α/NLRP3 pathway.

Targeting glycolytic pathway in fibroblast-like synoviocytes for rheumatoid arthritis therapy: challenges and opportunities

INTRODUCTION

Rheumatoid arthritis (RA) is a chronic autoimmune disorder characterized by hyperplastic synovium, pannus formation, immune cell infiltration, and potential articular cartilage damage. Notably, fibroblast-like synoviocytes (FLS), especially rheumatoid arthritis fibroblast-like synoviocytes (RAFLS), exhibit specific overexpression of glycolytic enzymes, resulting in heightened glycolysis. This elevated glycolysis serves to generate ATP and plays a pivotal role in immune regulation, angiogenesis, and adaptation to hypoxia. Key glycolytic enzymes, such as hexokinase 2 (HK2), phosphofructose-2-kinase/fructose-2,6-bisphosphatase 3 (PFKFB3), and pyruvate kinase M2 (PKM2), significantly contribute to the pathogenic behavior of RAFLS. This increased glycolysis activity is regulated by various signaling pathways.

MATERIALS AND METHODS

A comprehensive literature search was conducted to retrieve relevant studies published from January 1, 2010, to the present, focusing on RAFLS glycolysis, RA pathogenesis, glycolytic regulation pathways, and small-molecule drugs targeting glycolysis.

CONCLUSION

This review provides a thorough exploration of the pathological and physiological characteristics of three crucial glycolytic enzymes in RA. It delves into their putative regulatory mechanisms, shedding light on their significance in RAFLS. Furthermore, the review offers an up-to-date overview of emerging small-molecule candidate drugs designed to target these glycolytic enzymes and the upstream signaling pathways that regulate them. By enhancing our understanding of the pathogenic mechanisms of RA and highlighting the pivotal role of glycolytic enzymes, this study contributes to the development of innovative anti-rheumatic therapies.

Role of mitochondrial dysfunction in the pathogenesis of rheumatoid arthritis: Looking closely at fibroblast- like synoviocytes

Rheumatoid arthritis (RA) is a chronic, autoimmune, and inflammatory disease that primarily targets the joints, leading to cartilage and bone destruction.Fibroblast-like synoviocytes (FLS) are specialized cells of the synovial lining in the joint that plays a fundamental role in the development of RA. Particularly, FLS of RA patients (RA-FLS) in the joint exhibit specific characteristics like higher invading and immunogenic properties, hyperproliferation, and reduced apoptotic capacity, suggesting a dysfunctional mitochondrial pool in these cells. Mitochondria are emerging as a potential organelle that can decide cellular immunometabolism, invasion properties, and cell death. Accordingly, multiplestudies established that mitochondria are crucial in establishing RA. However, the underlying mechanism of impaired mitochondrial function in RA remains poorly understood. This review will provide an overview of the mitochondrial role in the progression of RA, specifically in the context of FLS biology. We will also outline how mitochondria-centric therapeutics can be achieved that would yield novel avenues of research in pathological mediation and prevention.

Spatiotemporal Investigation of Intercellular Heterogeneity via Multiple Photocaged Probes

Intercellular heterogeneity occurs widely under both normal physiological environments and abnormal disease-causing conditions. Several attempts to couple spatiotemporal information to cell states in a microenvironment were performed to decipher the cause and effect of heterogeneity. Furthermore, spatiotemporal manipulation can be achieved with the use of photocaged/photoactivatable molecules. Here, we provide a platform to spatiotemporally analyze differential protein expression in neighboring cells by multiple photocaged probes coupled with homemade photomasks. We successfully established intercellular heterogeneity (photoactivable ROS trigger) and mapped the targets (directly ROS-affected cells) and bystanders (surrounding cells), which were further characterized by total proteomic and cysteinomic analysis. Different protein profiles were shown between bystanders and target cells in both total proteome and cysteinome. Our strategy should expand the toolkit of spatiotemporal mapping for elucidating intercellular heterogeneity.

Preparation of mesoporous silica nanocarriers targeting glucose-6-phosphate isomerase inhibition and application in the treatment of rheumatoid arthritis

Glucose 6-phosphate isomerase (G6PI) is an indicator to assist in diagnosis of rheumatoid arthritis (RA) and monitor the disease. It also plays a key role in proliferating RA synovial tissues, pannus formation, and invasion and destruction of articular cartilage. In this study, we synthesized nanoparticles targeting G6PI (siG6PI-MSN) using mesoporous silica nanocarriers (MSN) and small interfering RNA (siRNA), followed by identifying the characteristics and functions, and preliminarily exploring their application in the treatment of RA in vivo with a type II collagen-induced arthritis (CIA) rat model. It showed that the synthetic functionalized carrier had a regular pore structure and a specific volume and surface area. No obvious hemolysis or toxicity of the carrier was found when its concentration was below 100 µg/ml. Cytological results in vitro suggested that siG6PI-MSN significantly inhibited G6PI expression and reduced the ability of proliferation, migration, and invasion of FLSs, compared with the siNC-MSN group. In vivo results in the CIA rat model showed that the arthritis index and degree of joint swelling among rats in the siG6PI-MSN-treatment group were significantly lower than those in the control group. Moreover, the number of FLSs in Synovium and the levels of TNF α and IL-1 β were also significantly decreased in the siG6PI-MSN group. Histopathology of the synovial tissue and cartilage revealed siG6PI-MSN treatment significantly reduced the pathological manifestations of arthritis. In conclusion, siG6PI-MSN effectively suppresses the proliferation and invasive growth of synovial tissue and improve joint swelling and inflammatory infiltration, thereby preventing joint damage in RA. This carrier may be a new therapeutic measure for RA, with potential social and economic benefits.

Role of reactive oxygen species and mitochondrial damage in rheumatoid arthritis and targeted drugs

Rheumatoid arthritis (RA) is an autoimmune disease characterized by synovial inflammation, pannus formation, and bone and cartilage damage. It has a high disability rate. The hypoxic microenvironment of RA joints can cause reactive oxygen species (ROS) accumulation and mitochondrial damage, which not only affect the metabolic processes of immune cells and pathological changes in fibroblastic synovial cells but also upregulate the expression of several inflammatory pathways, ultimately promoting inflammation. Additionally, ROS and mitochondrial damage are involved in angiogenesis and bone destruction, thereby accelerating RA progression. In this review, we highlighted the effects of ROS accumulation and mitochondrial damage on inflammatory response, angiogenesis, bone and cartilage damage in RA. Additionally, we summarized therapies that target ROS or mitochondria to relieve RA symptoms and discuss the gaps in research and existing controversies, hoping to provide new ideas for research in this area and insights for targeted drug development in RA.

Advances in experimental models of rheumatoid arthritis

Rheumatoid arthritis (RA) is a chronic systemic autoimmune disease characterized by persistent articular inflammation and joint damage. RA was first described over 200 years ago; however, its etiology and pathophysiology remain insufficiently understood. The current treatment of RA is mainly empirical or based on the current understanding of etiology with limited efficacy and/or substantial side effects. Thus, the development of safer and more potent therapeutics, validated and optimized in experimental models, is urgently required. To improve the transition from bench to bedside, researchers must carefully select the appropriate experimental models as well as draw the right conclusions. Here, we summarize the establishment, pathological features, potential mechanisms, advantages, and limitations of the currently available RA models. The aim of the review is to help researchers better understand available RA models; discuss future trends in RA model development, which can help highlight new translational and human-based avenues in RA research.

The Role of Reactive Oxygen Species in the Rheumatoid Arthritis-Associated Synovial Microenvironment

Rheumatoid arthritis (RA) is an inflammatory disease that begins with a loss of tolerance to modified self-antigens and immune system abnormalities, eventually leading to synovitis and bone and cartilage degradation. Reactive oxygen species (ROS) are commonly used as destructive or modifying agents of cellular components or they act as signaling molecules in the immune system. During the development of RA, a hypoxic and inflammatory situation in the synovium maintains ROS generation, which can be sustained by increased DNA damage and malfunctioning mitochondria in a feedback loop. Oxidative stress caused by abundant ROS production has also been shown to be associated with synovitis in RA. The goal of this review is to examine the functions of ROS and related molecular mechanisms in diverse cells in the synovial microenvironment of RA. The strategies relying on regulating ROS to treat RA are also reviewed.

Cellular metabolic adaptations in rheumatoid arthritis and their therapeutic implications

Activation of endothelium and immune cells is fundamental to the initiation of autoimmune diseases such as rheumatoid arthritis (RA), and it results in trans-endothelial cell migration and synovial fibroblast proliferation, leading to joint destruction. In RA, the synovial microvasculature is highly dysregulated, resulting in inefficient oxygen perfusion to the synovium, which, along with the high metabolic demands of activated immune and stromal cells, leads to a profoundly hypoxic microenvironment. In inflamed joints, infiltrating immune cells and synovial resident cells have great requirements for energy and nutrients, and they adapt their metabolic profiles to generate sufficient energy to support their highly activated inflammatory states. This shift in metabolic capacity of synovial cells enables them to produce the essential building blocks to support their proliferation, activation and invasiveness. Furthermore, it results in the accumulation of metabolic intermediates and alteration of redox-sensitive pathways, affecting signalling pathways that further potentiate the inflammatory response. Importantly, the inflamed synovium is a multicellular tissue, with cells differing in their metabolic requirements depending on complex cell-cell interactions, nutrient supply, metabolic intermediates and transcriptional regulation. Therefore, understanding the complex interplay between metabolic and inflammatory pathways in synovial cells in RA will provide insight into the underlying mechanisms of disease pathogenesis.

Metabolites as drivers and targets in Rheumatoid Arthritis

Rheumatoid arthritis (RA) is a chronic autoimmune disease characterized by neovascularization, immune cell infiltration, and synovial hyperplasia, which leads to degradation of articular cartilage and bone, and subsequent functional disability. Dysregulated angiogenesis, synovial hypoxia, and immune cell infiltration result in a ‘bioenergetic crisis’ in the inflamed joint which further exacerbates synovial invasiveness. Several studies have examined this vicious cycle between metabolism, immunity, and inflammation and the role metabolites play in these interactions. To add to this complexity, the inflamed synovium is a multicellular tissue with many cellular subsets having different metabolic requirements. Metabolites can shape the inflammatory phenotype of immune cell subsets during disease and act as central signalling hubs. In the RA joint, the increased energy demand of stromal and immune cells leads to the accumulation of metabolites such as lactate, citrate, and succinate as well as adipocytokines which can regulate downstream signalling pathways. Transcription factors such as HIF1ɑ and mTOR can act as metabolic sensors to activate synovial cells and drive pro-inflammatory effector function, thus perpetuating chronic inflammation further. These metabolic intermediates may be potential therapeutic targets and so understanding the complex interplay between metabolites and synovial cells in RA may allow for identification of novel therapeutic strategies but also may provide significant insight into the underlying mechanisms of disease pathogenesis.

Glycolysis Rate-Limiting Enzymes: Novel Potential Regulators of Rheumatoid Arthritis Pathogenesis

Rheumatoid arthritis (RA) is a classic autoimmune disease characterized by uncontrolled synovial proliferation, pannus formation, cartilage injury, and bone destruction. The specific pathogenesis of RA, a chronic inflammatory disease, remains unclear. However, both key glycolysis rate-limiting enzymes, hexokinase-II (HK-II), phosphofructokinase-1 (PFK-1), and pyruvate kinase M2 (PKM2), as well as indirect rate-limiting enzymes, 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase 3 (PFKFB3), are thought to participate in the pathogenesis of RA. In here, we review the latest literature on the pathogenesis of RA, introduce the pathophysiological characteristics of HK-II, PFK-1/PFKFB3, and PKM2 and their expression characteristics in this autoimmune disease, and systematically assess the association between the glycolytic rate-limiting enzymes and RA from a molecular level. Moreover, we highlight HK-II, PFK-1/PFKFB3, and PKM2 as potential targets for the clinical treatment of RA. There is great potential to develop new anti-rheumatic therapies through safe inhibition or overexpression of glycolysis rate-limiting enzymes.

Matrine inhibits synovial angiogenesis in collagen-induced arthritis rats by regulating HIF-VEGF-Ang and inhibiting the PI3K/Akt signaling pathway

Matrine (Mat) is an alkaloid of tetracycline quinazine, and previous studies have demonstrated its specific effect on relieving rheumatoid arthritis (RA). However, the effect of Mat on joint synovial angiogenesis in the pathogenesis of RA has not been elucidated. In this study, body weight, joint swelling, arthritis index (AI) score, histopathological changes, immunohistochemical, and western blot- were used in collagen-induced arthritis (CIA) rats to detect pro-inflammatory factors and, - expression levels of key cytokines and proteins along the hypoxia-inducible factor (HIF)-endothelial growth factor (VEGF)-angiopoietin (Ang) axis and VEGF-phosphoinositide 3-kinase (PI3K) / protein kinase B (Akt) pathway. In vitro experiments were conducted to observe the effect of Mat on the proliferation, migration and lumen formation of RA-fibroblast-like synovial cells (FLS) and human umbilical vein endothelial cells (HUVECs). Results showed that Mat reduced the degree of paw swelling and AI score in CIA rats, joint synovial tissue proliferation, inflammatory cell infiltration, and neovascularization; moreover, it down-regulated the expression levels of inflammatory factors interleukin-1β, interferon-γ, and pro-angiogenic factors VEGF, placental growth factor, HIF-α, Ang-1, Ang-2, Tie-2, and phosphorylation-Akt in the ankle joint of CIA rats. In addition, the in vitro experiments showed that Mat inhibited the proliferation and migration of RA-FLS and inhibited the proliferation and lumen formation of HUVECs. Therefore, Mat exerts an anti-angiogenesis effect by regulating the HIF-VEGF-Ang axis and inhibiting the PI3K/Akt signaling pathway. This inhibits the pathogenesis and improve the symptoms of RA, and may be offered as a candidate drug for the treatment of RA.

The Protective Effect of Quercetin on Endothelial Cells Injured by Hypoxia and Reoxygenation

Background: Cerebral small vessel disease (CSVD) is a group of clinical syndromes covering all pathological processes of small vessels in the brain, which can cause stroke and serious dementia. However, as the pathogenesis of CSVD is not clear, so the treatment is limited. Endothelial cell dysfunction is earlier than clinical symptoms, such as hypertension and leukosis. Therefore, the treatment of endothelial cells is expected to be a new breakthrough. Quercetin, a flavonoid present in a variety of plants, has the function of anti-inflammation and anti-oxidation. This study aimed to investigate the protective effect of quercetin on endothelial cell injury and provide a basic theory for subsequent application in the clinic. Methods: Human brain microvascular endothelial cells (HBMECs) were cultured in vitro, and the injury model of endothelial cells was established by hypoxia and reoxygenation (H/R). The protective effects of quercetin on HBMECs were studied from the perspectives of cell viability, cell migration, angiogenesis and apoptosis. In order to further study the mechanism of quercetin, oxidative stress and endoplasmic reticulum stress were analyzed. What's more, blood-brain barrier (BBB) integrity was also studied. Results: Quercetin can promote the viability, migration and angiogenesis of HBMECs, and inhibit the apoptosis. In addition, quercetin can also activate Keap1/Nrf2 signaling pathway, reduce ATF6/GRP78 protein expression. Further study showed that quercetin could increase the expression of Claudin-5 and Zonula occludens-1. Conclusions: Our experiments show that quercetin can protect HBMECs from H/R, which contains promoting cell proliferation, cell migration and angiogenesis, reducing mitochondrial membrane potential damage and inhibiting cell apoptosis. This may be related to its antioxidation and inhibition of endoplasmic reticulum stress. At the same time, quercetin can increase the level of BBB connexin, suggesting that quercetin can maintain BBB integrity.

Footprints of microRNAs in Cancer Biology

MicroRNAs (miRNAs) are short non-coding RNAs involved in post-transcriptional gene regulation. Over the past years, various studies have demonstrated the role of aberrant miRNA expression in the onset of cancer. The mechanisms by which miRNA exerts its cancer-promoting or inhibitory effects are apparent through the various cancer hallmarks, which include selective proliferative advantage, altered stress response, vascularization, invasion and metastasis, metabolic rewiring, the tumor microenvironment and immune modulation; therefore, this review aims to highlight the association between miRNAs and the various cancer hallmarks by dissecting the mechanisms of miRNA regulation in each hallmark separately. It is hoped that the information presented herein will provide further insights regarding the role of cancer and serve as a guideline to evaluate the potential of microRNAs to be utilized as biomarkers and therapeutic targets on a larger scale in cancer research.

SARS-CoV-2 Infection Remodels the Phenotype and Promotes Angiogenesis of Primary Human Lung Endothelial Cells

SARS-CoV-2-associated acute respiratory distress syndrome (ARDS) and acute lung injury are life-threatening manifestations of severe viral infection. The pathogenic mechanisms that lead to respiratory complications, such as endothelialitis, intussusceptive angiogenesis, and vascular leakage remain unclear. In this study, by using an immunofluorescence assay and in situ RNA-hybridization, we demonstrate the capability of SARS-CoV-2 to infect human primary lung microvascular endothelial cells (HL-mECs) in the absence of cytopathic effects and release of infectious particles. Preliminary data point to the role of integrins in SARS-CoV-2 entry into HL-mECs in the absence of detectable ACE2 expression. Following infection, HL-mECs were found to release a plethora of pro-inflammatory and pro-angiogenic molecules, as assessed by microarray analyses. This conditioned microenvironment stimulated HL-mECs to acquire an angiogenic phenotype. Proteome analysis confirmed a remodeling of SARS-CoV-2-infected HL-mECs to inflammatory and angiogenic responses and highlighted the expression of antiviral molecules as annexin A6 and MX1. These results support the hypothesis of a direct role of SARS-CoV-2-infected HL-mECs in sustaining vascular dysfunction during the early phases of infection. The construction of virus-host interactomes will be instrumental to identify potential therapeutic targets for COVID-19 aimed to inhibit HL-mEC-sustained inflammation and angiogenesis upon SARS-CoV-2 infection.

Metabolomic Alteration of Oral Keratinocytes and Fibroblasts in Hypoxia

The oxygen concentration in normal human tissue under physiologic conditions is lower than the atmospheric oxygen concentration. The more hypoxic condition has been observed in the cells with wound healing and cancer. Somatic stem cells reside in a hypoxic microenvironment in vivo and prefer hypoxic culture conditions in vitro. Oral mucosa contains tissue-specific stem cells, which is an excellent tissue source for regenerative medicine. For clinical usage, maintaining the stem cell in cultured cells is important. We previously reported that hypoxic culture conditions maintained primary oral keratinocytes in an undifferentiated and quiescent state and enhanced their clonogenicity. However, the metabolic mechanism of these cells is unclear. Stem cell biological and pathological findings have shown that metabolic reprogramming is important in hypoxic culture conditions, but there has been no report on oral mucosal keratinocytes and fibroblasts. Herein, we conducted metabolomic analyses of oral mucosal keratinocytes and fibroblasts under hypoxic conditions. Hypoxic oral keratinocytes and fibroblasts showed a drastic change of metabolite concentrations in urea cycle metabolites and polyamine pathways. The changes of metabolic profiles in glycolysis and the pentose phosphate pathway under hypoxic conditions in the oral keratinocytes were consistent with those of other somatic stem cells. The metabolic profiles in oral fibroblasts showed only little changes in any pathway under hypoxia except for a significant increase in the antioxidant 2-oxoglutaric acid. This report firstly provides the holistic changes of various metabolic pathways of hypoxic cultured oral keratinocytes and fibroblasts.

Transformation of fibroblast-like synoviocytes in rheumatoid arthritis; from a friend to foe

Swelling and the progressive destruction of articular cartilage are major characteristics of rheumatoid arthritis (RA), a systemic autoimmune disease that directly affects the synovial joints and often causes severe disability in the affected positions. Recent studies have shown that type B synoviocytes, which are also called fibroblast-like synoviocytes (FLSs), as the most commonly and chiefly resident cells, play a crucial role in early-onset and disease progression by producing various mediators. During the pathogenesis of RA, the FLSs' phenotype is altered, and represent invasive behavior similar to that observed in tumor conditions. Modified and stressful microenvironment by FLSs leads to the recruitment of other immune cells and, eventually, pannus formation. The origins of this cancerous phenotype stem fundamentally from the significant metabolic changes in glucose, lipids, and oxygen metabolism pathways. Moreover, the genetic abnormalities and epigenetic alterations have recently been implicated in cancer-like behaviors of RA FLSs. In this review, we will focus on the mechanisms underlying the transformation of FLSs to a cancer-like phenotype during RA. A comprehensive understanding of these mechanisms may lead to devising more effective and targeted treatment strategies.

Computational Prediction of Antiangiogenesis Synergistic Mechanisms of Total Saponins of Panax japonicus Against Rheumatoid Arthritis

Objective: To investigate the anti-angiogenesis mechanisms and key targets of total saponins of Panax japonicus (TSPJ) in the treatment of rheumatoid arthritis (RA). Methods: RStudio3.6.1 software was used to obtain differentially expressed genes (DEGs) by analyzing the differences in gene expression in the synovial tissue of RA and to predict the potential targets of active compounds from TSPJ by the PharmMapper and SwissTargetPrediction databases. We evaluated the overlapping genes by intersectional analysis of DEGs and drug targets. Based on the overlapping genes, we used Cytoscape 3.7.2 software to construct a protein-protein interactions (PPI) network and applied Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis to determine the mechanisms of the treatment. Finally, the correlations with angiogenesis-related genes were explored. Collagen-induced arthritis (CIA) model was established and treated with different doses of TSPJ. The manifestations of CIA were determined by evaluation of arthritis index and histology score. Serum levels of vascular endothelial growth factor (VEGF) and the hypoxia-inducible factor 1 (HIF-1) were tested by ELISA. The mRNA levels of IL-1β and IL-17A were detected by real time-quantitative PCR. Results: Altogether, 2670 DEGs were obtained by differential analysis, and 371 drug targets were predicted for four active components (Araloside A, Chikusetsusaponin IVa, Ginsenoside Rg2, and Ginsenoside Ro). A total of 52 overlapping genes were included in the PPI network and the KEGG analysis. However, only 41 genes in the PPI network had protein interactions. The results of the KEGG enrichment analysis were all related to angiogenesis, including VEGF and HIF-1 signaling pathways. Seven genes with negative correlations and 16 genes with positive correlations were obtained by correlational analysis of DEGs in the VEGF and HIF-1 signaling pathways. SRC proto-oncogene, nonreceptor tyrosine kinase (SRC), and the signal transducer and activator of transcription 3 (STAT 3) had a higher value of degree and showed a significant correlation in the pathways; they were regarded as key targets. Compared with the model group, TSPJ significantly relieved the symptoms and decreased the expression of VEGFA, HIF-1α, IL-1β, and IL-17A in serum or spleens of CIA mice. Conclusion: In the current study, we found that antiangiogenesis is one of the effective strategies of TSPJ against RA; SRC and STAT 3 may be the key targets of TSPJ acting on the VEGF and HIF-1 signaling pathways, which will provide new insight into the treatment of RA by inhibiting inflammation and angiogenesis.

Post-translational protein deimination signatures and extracellular vesicles (EVs) in the Atlantic horseshoe crab (Limulus polyphemus)

The horseshoe crab is a living fossil and a species of marine arthropod with unusual immune system properties which are also exploited commercially. Given its ancient status dating to the Ordovician period (450 million years ago), its standing in phylogeny and unusual immunological characteristics, the horseshoe crab may hold valuable information for comparative immunology studies. Peptidylarginine deiminases (PADs) are calcium dependent enzymes that are phylogenetically conserved and cause protein deimination via conversion of arginine to citrulline. This post-translational modification can lead to structural and functional protein changes contributing to protein moonlighting in health and disease. PAD-mediated regulation of extracellular vesicle (EV) release, a critical component of cellular communication, has furthermore been identified to be a phylogenetically conserved mechanism. PADs, protein deimination and EVs have hitherto not been studied in the horseshoe crab and were assessed in the current study. Horseshoe crab haemolymph serum-EVs were found to be a poly-dispersed population in the 20-400 nm size range, with the majority of EVs falling within 40-123 nm. Key immune proteins were identified to be post-translationally deiminated in horseshoe crab haemolymph serum, providing insights into protein moonlighting function of Limulus and phylogenetically conserved immune proteins. KEGG (Kyoto encyclopaedia of genes and genomes) and GO (gene ontology) enrichment analysis of deiminated proteins identified in Limulus revealed KEGG pathways relating to complement and coagulation pathways, Staphylococcus aureus infection, glycolysis/gluconeogenesis and carbon metabolism, while GO pathways of biological and molecular pathways related to a range of immune and metabolic functions, as well as developmental processes. The characterisation of EVs, and post-translational deimination signatures, revealed here in horseshoe crab, contributes to current understanding of protein moonlighting functions and EV-mediated communication in this ancient arthropod and throughout phylogeny.

<p>In vivo Screening of Natural Products Against Angiogenesis and Mechanisms of Anti-Angiogenic Activity of Deoxysappanone B 7,4ʹ-Dimethyl Ether</p>

Introduction

The aim of this study was to screen the leading compounds of natural origin with anti-angiogenic potential and to investigate their anti-angiogenic mechanism preliminarily.

Materials and Methods

An initial screening of 240 compounds from the Natural Products Collection of MicroSource was performed using the transgenic zebrafish strain Tg [fli1a: enhanced green fluorescent protein (EGFP)]^y1. The zebrafish embryos at 24 h post-fertilization were exposed to the natural compounds for an additional 24 h; then, morphological changes in the intersegmental vessels (ISVs) were observed and quantified under a fluorescence microscope. The expression profiles of angiogenesis-related genes in the zebrafish embryos were detected using quantitative real-time PCR.

Results

Five compounds were identified with potential anti-angiogenic activity on the zebrafish embryogenesis. Among them, deoxysappanone B 7.4ʹ-dimethyl ether (Deox B 7,4) showed anti-angiogenic activity on the formation of ISVs in a dose-dependent manner. The inhibition of ISV formation reached up to 99.64% at 5 μM Deox B 7,4. The expression of delta-like ligand 4 (dll4), hes-related family basic helix-loop-helix transcription factor with YRPW motif 2, ephrin B2, fibroblast growth factor receptor (fgfr) 3, cyclooxygenase-2, protein tyrosine phosphatase, receptor type B (ptp-rb), phosphoinositide-3-kinase regulatory subunit 2, slit guidance ligand (slit) 2, slit3, roundabout guidance receptor (robo) 1, robo2, and robo4 were down-regulated, while vascular endothelial growth factor receptor-2, fgfr 1, and matrix metallopeptidase 9 were up-regulated in the zebrafish embryos treated with Deox B 7,4.

Conclusion

Deox B 7,4 has a therapeutic potential for the treatment of angiogenesis-dependent diseases and may exert anti-angiogenic activities by suppressing the slit2/robo1/2, slit3/robo4, cox2/ptp-rb/pik3r2, and dll4/hey2/efnb2a signaling pathways as well as activation of vegfr-2/fgfr1/mmp9.

Metabolic Checkpoints in Rheumatoid Arthritis

Several studies have highlighted the interplay between metabolism, immunity and inflammation. Both tissue resident and infiltrating immune cells play a major role in the inflammatory process of rheumatoid arthritis (RA) via the production of cytokines, adipo-cytokines and metabolic intermediates. These functions are metabolically demanding and require the most efficient use of bioenergetic pathways. The synovial membrane is the primary site of inflammation in RA and exhibits distinctive histological patterns characterized by different metabolism, prognosis and response to treatment. In the RA synovium, the high energy demand by stromal and infiltrating immune cells, causes the accumulation of metabolites, and adipo-cytokines, which carry out signaling functions, as well as activating transcription factors which act as metabolic sensors. These events drive immune and joint-resident cells to acquire pro-inflammatory effector functions which in turn perpetuate chronic inflammation. Whether metabolic changes are a consequence of the disease or one of the causes of RA pathogenesis is still under investigation. This review covers our current knowledge of cell metabolism in RA. Understanding the intricate interactions between metabolic pathways and the inflammatory and immune responses will provide more awareness of the mechanisms underlying RA pathogenesis and will identify novel therapeutic options to treat this disease.

Recent Advances in Nanotheranostics for Treat-to-Target of Rheumatoid Arthritis

Early diagnosis, standardized treatment, and regular monitoring are the clinical treatment principle of rheumatoid arthritis (RA). The overarching principles and recommendations of treat-to-target (T2T) in RA advocate remission as the optimum aim, especially for patients with very early disease who are initiating therapy with anti-RA medications. However, traditional anti-RA drugs cannot selectively target the inflammatory areas and may cause serious side effects due to its short biological half-life and poor bioavailability. These limitations have significantly driven the research and application of nanomaterial-based drugs in theranostics of RA. Nanomedicines have appropriate sizes and easily modified surfaces which can enhance their biological compatibility and prolong circulation time of drug-loading systems in vivo. Traditional T2T regimens cannot evaluate the efficacy of drugs in real time, while clinical drug nanosizing can realize the integration of diagnosis and treatment of RA. This review bridges clinically proposed T2T concepts and nanomedicine in an integrated system for RA early-stage diagnosis and treatment. The most advanced progress in various nanodrug delivery systems for theranostics of RA is summarized, establishing a clear path and a new perspective for further optimization of T2T. Finally, the key facing challenges are discussed and prospects are addressed.

Downregulation of Hypoxia-Inducible Factor-1α by RNA Interference Alleviates the Development of Collagen-Induced Arthritis in Rats

Rheumatoid arthritis (RA) is the most common type of autoimmune arthritis. Hypoxia-inducible factor-1α (HIF-1α) as a transcription factor in response to hypoxia suggests that it could be a potential therapeutic target for the treatment of RA. In this study, we assessed whether the HIF pathway blockade attenuates the manifestations of RA in the collagen-induced arthritis (CIA) rat model. We constructed a short hairpin RNA (shRNA) lentiviral expression vector targeting HIF-1α (pLVX-shRNA-HIF-1α) and to achieve HIF-1α RNA interference. Quantitative RT-PCR, immunofluorescence staining, and western blot were used to detect the expressions of HIF-1α, vascular endothelial growth factor (VEGF), phsopho (p)-p65, and p-IКBɑ mRNA and protein, respectively. Micro-computed tomography was used to investigate joint morphology at different time points after CIA induction. Moreover, enzyme-linked immunosorbent assay (ELISA) was used to monitor the expression of inflammatory cytokines. In vitro analyses revealed that pLVX-shRNA-HIF-1α effectively inhibited the expression of HIF-1α and VEGF and led to the activation of p-65 and p-IКBɑ, as well as decreased proinflammatory cytokine expression in cell culture. Inhibition of HIF-1α in rats decreased signs of a systemic inflammatory condition, together with decreased pathological changes of RA. Moreover, downregulation of HIF-1α expression markedly reduced the synovitis and angiogenesis. In conclusion, we have shown that pharmacological inhibition of HIF-1 may improve the clinical manifestations of RA.

Enhanced angiogenic function in response to fibroblasts from psoriatic arthritis synovium compared to rheumatoid arthritis

Introduction

Angiogenesis is an early event in the pathogenesis of both psoriatic arthritis (PsA) and rheumatoid arthritis (RA); however, there are striking differences in blood vessel morphology and activation between the two arthropathies. The aim of this study was to assess if the PsA and RA joint microenvironments differentially regulate endothelial cell function.

Methods

PsA and RA primary synovial fibroblasts (SFC) were isolated from synovial biopsies, grown to confluence, and supernatants harvested and termed ‘conditioned media’ (CM). Human umbilical vein endothelial cells (HUVEC) were cultured with PsA SFC or RA SFC-CM (20%). HUVEC tube formation, migration, and PBMC adhesion were assessed by matrigel tube formation, wound repair, and PBMC adhesion assays. HUVEC cell surface expression of ICAM, VCAM, and E-Selectin was assessed by flow cytometry. Transcriptome analysis of genes promoting angiogenesis was performed by real-time PCR. Finally, a MSD multiplex angiogenic assay was performed on PsA SFC and RA SFC supernatants.

Results

Macroscopic synovitis and vascularity were similar in PsA and RA patients; however, significant differences in vascular morphological pattern were recorded with tortuous, elongated vessels observed in PsA compared to straight regular branching vessels observed in RA. Transcriptome analysis showed strong upregulation of the pro-angiogenic signature in HUVEC primed with PsA SFC-CM compared to RA SFC-CM and basal control. In parallel, paired PsA SFC-CM significantly induced HUVEC tube formation compared to that of RA SFC-CM. Furthermore, PsA SFC-CM induced HUVEC migration was paralleled by a significant induction in VEGFA, PFKFB3, ICAM-1, and MMP3 mRNA expression. A significant increase in PBMC adhesion and cell surface expression of VCAM-1, ICAM-1, and E-Selectin expression was also demonstrated in PsA SFC-CM-primed HUVEC compared to RA SFC-CM. Finally, VEGF, TSLP, Flt-1, and Tie-2 expression was elevated in PsA SFC-CM compared to RA SFC-CM, with no significant difference in other pro-angiogenic mediators including MIP-3, bFGF, PIGF, and MCP-1.

Conclusion

PsA SFC and RA SFC secreted factors differentially regulate endothelial cell function, with soluble mediators in the PsA joint microenvironment inducing a more pro-angiogenic phenotype compared to the RA.

Potential role of exercise-induced glucose-6-phosphate isomerase in skeletal muscle function

[Purpose]

Recent studies have shown that glucose-6-phosphate isomerase (GPI)—which is a glycolysis interconversion enzyme—reduces oxidative stress. However, these studies are limited to tumors such as fibrosarcoma, and there are no studies that have examined the effects of exercise on GPI expression in mice skeletal muscle. Furthermore, GPI acts in an autocrine manner thorough its receptor, autocrine motility factor receptor (AMFR); therefore, we investigated expression level changes of secreted GPI from skeletal muscle in in vitro study to examine the potential role of GPI on skeletal muscle.

[Methods]

First, we performed an in vitro study, to identify the condition that upregulates GPI levels in skeletal muscle cells; we treated C2C12 muscle cells with an exercise-mimicking chemical, AICAR. AICAR treatment upregulated GPI expression level in C2C12 cell and its secretomes. To confirm the direct effect of GPI on skeletal muscle cells, we treated C2C12 cells with GPI recombinant protein.

[Results]

We found that GPI improved the viability of C2C12 cells. In the in vivo study, the exercise-treated mice group showed upregulated GPI expression in skeletal muscle. Based on the in vitro study results, we speculated that expression level of GPI in skeletal muscle might be associated with muscle function. We analyzed the association between GPI expression level and the grip strength of the all mice group. The mice group’s grip strengths were upregulated after 2 weeks of treadmill exercise, and GPI expression level positively correlated with the grip strength.

[Conclusion]

These results suggested that the exercise-induced GPI expression in skeletal muscle might have a positive effect on skeletal muscle function.

Value of serum glucose-6-phosphate isomerase in patients with rheumatoid arthritis and correlation with disease activity: A case-control study

BACKGROUND

Rheumatoid arthritis (RA) is a common multisystemic autoimmune disease with peripheral joint involvement. Many autoantibodies have been introduced in the course of RA; some of them have diagnostic and prognostic value. In this study, our aim is to determine the value of serum glucose-6-phosphate isomerase (G6PI) antigen (Ag) as a diagnostic and prognostic marker in RA.

MATERIALS AND METHODS

Eighty-seven known cases of RA who referred to an outpatient clinic of Shiraz University of Medical Sciences and 76 healthy controls were selected. Serum G6PI Ag was measured using sandwich enzyme-linked immunosorbent assay method, and the enzyme level was compared in the patient and control group, we also compared the enzyme level of patient group with disease activity, disease duration, erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), rheumatoid factor (RF), and anti-cyclic citrullinated peptide (anti-CCP) antibody (Ab). The data were analyzed using SPSS V 16 software.

RESULTS

Positivity for G6PI was detected in 34.5% (30/87) of RA patients and 9.2% (7/76) of control group (P < 0.001). There was no significant correlation between enzyme level and disease activity, disease duration, ESR, CRP, RF, and anti-CCP Ab.

CONCLUSIONS

Overall, in our study, although there was a significant difference in serum G6PI Ag between patient and control group, no significant correlation was detected between serum G6PI level and disease activity score, ESR, CRP, and anti-CCP Ab, but relative correlation with ESR and disease duration could be challenging. G6PI Ag could be introduced as a diagnostic marker in RA, but its role as a prognostic marker is controversial.

Hypoxia-induced miR-191-C/EBPβ signaling regulates cell proliferation and apoptosis of fibroblast-like synoviocytes from patients with rheumatoid arthritis

BACKGROUND

Hypoxia plays an important role in the proliferation of rheumatoid arthritis fibroblast-like synoviocytes (RA-FLS), leading to pathology of RA. This study was conducted to evaluate hypoxia-induced microRNAs (hypoxamiR) in RA-FLS and its role in the function of RA-FLS.

METHODS

RA-FLS were cultured under normoxia (21% O₂) or hypoxia (3% O₂) condition, followed by a microRNA (miRNA) array analysis. The upregulation of miR-191 by hypoxia was confirmed in RA-FLS and FLS from osteoarthritis (OA) patients by quantitative real-time polymerase chain reaction (RT-PCR). Transfection of miR-191 mimic and inhibitor was used to investigate the function of miR-191 in RA-FLS. The functional targets of miR-191 were predicted by bioinfomatics and then validated by reporter gene assay.

RESULTS

A subset of miRNAs was identified to be induced by hypoxia including miR-191. The upregulation of miR-191 was found to be specific in hypoxic RA-FLS, compared to hypoxic OA-FLS. We observed that miR-191 in RA-FLS increased cellular proliferation via promoting G₁/S transition of the cell cycle and suppressed cell apoptosis induced by cell starvation. Bioinformatical analysis and experimental assays identified CCAAT/enhancer binding protein β (C/EBPβ) as a target gene of miR-191 in RA-FLS. Enforced expression of C/EBPβ rescued the cellular phenotypes induced by miR-191. In addition, an inverse correlation between the C/EBPβ level and hypoxia stimulation was found in RA-FLS, and overexpression of C/EBPβ could partly rescue the hypoxia-induced cell proliferation.

CONCLUSION

We demonstrated the miR-191-C/EBPβ signaling pathway mediating the hypoxia-induced cell proliferation in RA.

Styryl-cinnamate hybrid inhibits glioma by alleviating translation, bioenergetics and other key cellular responses leading to apoptosis

Gliomas are lethal and aggressive form of brain tumors with resistance to conventional radiation and cytotoxic chemotherapies; inviting continuous efforts for drug discovery and drug delivery. Interestingly, small molecule hybrids are one such pharmacophore that continues to capture interest owing to their pluripotent medicinal effects. Accordingly, we earlier reported synthesis of potent Styryl-cinnamate hybrids (analogues of Salvianolic acid F) along with its plausible mode of action (MOA). We explored iTRAQ-LC/MS-MS technique to deduce differentially expressed landscape of native & phospho-proteins in treated glioma cells. Based on this, Protein-Protein Interactome (PPI) was looked into by employing computational tools and further validated in vitro. We hereby report that the Styryl-cinnamate hybrid, an analogue of natural Salvianolic acid F, alters key regulatory proteins involved in translation, cytoskeleton development, bioenergetics, DNA repair, angiogenesis and ubiquitination. Cell cycle analysis dictates arrest at G0/G1 stage along with reduced levels of cyclin D; involved in G1 progression. We discovered that Styryl-cinnamate hybrid targets glioma by intrinsically triggering metabolite-mediated stress. Various oncological circuits alleviated by the potential drug candidate strongly supports the role of such pharmacophores as anticancer drugs. Although, further analysis of SC hybrid in treating xenografts or solid tumors is yet to be explored but their candidature has gained huge impetus through this study. This study equips us better in understanding the shift in proteomic landscape after treating glioma cells with SC hybrid. It also allows us to elicit molecular targets of this potential drug before progressing to preclinical studies.

Altered metabolic pathways regulate synovial inflammation in rheumatoid arthritis

Rheumatoid arthritis is characterized by synovial proliferation, neovascularization and leucocyte extravasation leading to joint destruction and functional disability. The blood vessels in the inflamed synovium are highly dysregulated, resulting in poor delivery of oxygen; this, along with the increased metabolic demand of infiltrating immune cells and inflamed resident cells, results in the lack of key nutrients at the site of inflammation. In these adverse conditions synovial cells must adapt to generate sufficient energy to support their proliferation and activation status, and thus switch their cell metabolism from a resting regulatory state to a highly metabolically active state. This alters redox-sensitive signalling pathways and also results in the accumulation of metabolic intermediates which, in turn, can act as signalling molecules that further exacerbate the inflammatory response. The RA synovium is a multi-cellular tissue, and while many cell types interact to promote the inflammatory response, their metabolic requirements differ. Thus, understanding the complex interplay between hypoxia-induced signalling pathways, metabolic pathways and the inflammatory response will provide better insight into the underlying mechanisms of disease pathogenesis.

Promoted Angiogenesis and Osteogenesis by Dexamethasone-loaded Calcium Phosphate Nanoparticles/Collagen Composite Scaffolds with Microgroove Networks

Reconstruction of large bone defects remains a clinical challenge because current approaches involving surgery and bone grafting often do not yield satisfactory outcomes. For artificial bone substitutes, angiogenesis plays a pivotal role to achieve the final success of newly regenerated bone. In this study, dexamethasone-loaded biphasic calcium phosphate nanoparticles/collagen composite scaffolds with several types of concave microgrooves were prepared for simultaneous promotion of angiogenesis and osteogenesis. Microgrooves in the scaffolds were supposed to guide the assembly of human umbilical vascular endothelial cells (HUVECs) into well aligned tubular structures, thus promoting rapid angiogenesis. The scaffolds were used for co-culture of HUVECs and human bone marrow-derived mesenchymal stem cells. Subcutaneous implantation in mice showed that more blood vessels and newly formed bone were observed in the microgrooved composite scaffolds than in the control scaffold. Scaffold bearing parallel microgrooves with a concave width of 290 µm and a convex ridge width of 352 µm showed the highest promotion effect on angiogenesis and osteogenesis among the parallelly microgrooved composite scaffolds. The scaffolds bearing a grid network had further superior promotion effect to the scaffolds bearing parallel microgrooves. The results indicated that microgrooves in the composite scaffolds facilitated angiogenesis and stimulated new bone formation. The microgrooved composite scaffolds should be useful for repairing of large bone defects.

Identification of mundoserone by zebrafish in vivo screening as a natural product with anti-angiogenic activity

The present study aimed to screen natural products with anti-angiogenic potential from the Natural Products Collection of MicroSource. The anti-angiogenic activity of 240 natural products was assessed using the zebrafish line Tg(fli1a: EGFP)^y1. At 24 h post-fertilization, the embryos were treated with the library compounds for 24 h and, the morphology of the intersegmental vessels (ISVs) was then assessed using a fluorescence microscope, followed by counting of ISVs and calculation of the inhibition ratio. The expression of angiogenesis-associated genes was determined by quantitative polymerase chain reaction. The results indicated that mundoserone inhibited ISV formation in zebrafish embryos in a dose-dependent manner, with a significant anti-angiogenic activity observed at a concentration of 10 µM, leading to an ISV inhibition ratio of 73.6±1.3%. Mundoserone significantly reduced the expression of slit guidance ligand 3 (SLIT3), roundabout guidance receptor 1 (ROBO1) and -2, fibroblast growth factor receptor (FGFR)2 and -3, as well as protein tyrosine phosphatase, receptor type B (PTP-RB), but increased the expression of NOTCH1A. Accordingly, mundoserone may be an effective angiogenic inhibitor, which acts via downregulation of SLIT/ROBO1 and FGFR/PTP-RB, and upregulation of NOTCH1A signaling.

Oxidation Resistance 1 Modulates Glycolytic Pathways in the Cerebellum via an Interaction with Glucose-6-Phosphate Isomerase

Glucose metabolism is essential for the brain: it not only provides the required energy for cellular function and communication but also participates in balancing the levels of oxidative stress in neurons. Defects in glucose metabolism have been described in neurodegenerative disease; however, it remains unclear how this fundamental process contributes to neuronal cell death in these disorders. Here, we investigated the molecular mechanisms driving the selective neurodegeneration in an ataxic mouse model lacking oxidation resistance 1 (Oxr1) and discovered an unexpected function for this protein as a regulator of the glycolytic enzyme, glucose-6-phosphate isomerase (GPI/Gpi1). Initially, we present a dysregulation of metabolites of glucose metabolism at the pre-symptomatic stage in the Oxr1 knockout cerebellum. We then demonstrate that Oxr1 and Gpi1 physically and functionally interact and that the level of Gpi1 oligomerisation is disrupted when Oxr1 is deleted in vivo. Furthermore, we show that Oxr1 modulates the additional and less well-understood roles of Gpi1 as a cytokine and neuroprotective factor. Overall, our data identify a new molecular function for Oxr1, establishing this protein as important player in neuronal survival, regulating both oxidative stress and glucose metabolism in the brain.

Oxidative stress impairs energy metabolism in primary cells and synovial tissue of patients with rheumatoid arthritis

Background

In this study, we examined the effect of oxidative stress on cellular energy metabolism and pro-angiogenic/pro-inflammatory mechanisms of primary rheumatoid arthritis synovial fibroblast cells (RASFC) and human umbilical vein endothelial cells (HUVEC).

Methods

Primary RASFC and HUVEC were cultured with the oxidative stress inducer 4-hydroxy-2-nonenal (4-HNE), and extracellular acidification rate, oxygen consumption rate, mitochondrial function and pro-angiogenic/pro-inflammatory mechanisms were assessed using the Seahorse analyser, complex I–V activity assays, random mutation mitochondrial capture assays, enzyme-linked immunosorbent assays and functional assays, including angiogenic tube formation, migration and invasion. Expression of angiogenic growth factors in synovial tissue (ST) was assessed by IHC in patients with rheumatoid arthritis (RA) undergoing arthroscopy before and after administration of tumour necrosis factor inhibitors (TNFi).

Results

In RASFC and HUVEC, 4-HNE-induced oxidative stress reprogrammed energy metabolism by inhibiting mitochondrial basal, maximal and adenosine triphosphate-linked respiration and reserve capacity, coupled with the reduced enzymatic activity of oxidative phosphorylation complexes III and IV. In contrast, 4-HNE elevated basal glycolysis, glycolytic capacity and glycolytic reserve, paralleled by an increase in mitochondrial DNA mutations and reactive oxygen species. 4-HNE activated pro-angiogenic responses of RASFC, which subsequently altered HUVEC invasion and migration, angiogenic tube formation and the release of pro-angiogenic mediators. In vivo markers of angiogenesis (vascular endothelial growth factor, angiopoietin 2 [Ang2], tyrosine kinase receptor [Tie2]) were significantly associated with oxidative damage and oxygen metabolism in the inflamed synovium. Significant reduction in ST vascularity and Ang2/Tie2 expression was demonstrated in patients with RA before and after administration of TNFi.

Conclusions

Oxidative stress promotes metabolism in favour of glycolysis, an effect that may contribute to acceleration of inflammatory mechanisms and subsequent dysfunctional angiogenesis in RA.

Electronic supplementary material

The online version of this article (10.1186/s13075-018-1592-1) contains supplementary material, which is available to authorized users.

Wu-Tou Decoction Inhibits Angiogenesis in Experimental Arthritis by Targeting VEGFR2 Signaling Pathway

Wu-tou decoction (WTD) is a classic traditional Chinese medicine formula and has been extensively used for the treatment of rheumatoid arthritis (RA). Previous reports indicate that WTD possesses anti-inflammatory and antinociceptive activities, and inhibits the development of arthritic joints and disease severity of collagen-induced arthritis (CIA) or adjuvant-induced rats; however, its action on angiogenesis of RA has not been clarified. This study aims to determine the anti-angiogenic activity of WTD in CIA rats and in various angiogenesis models. Our data showed that WTD (0.95, 1.9, and 3.8 g/kg) markedly reduced the immature blood vessels in synovial membrane tissues of inflamed joints from CIA rats. It also inhibited in vivo angiogenesis in chick embryo and VEGF₁₆₅-induced microvessel sprout formation ex vivo. Meanwhile, WTD suppressed VEGF₁₆₅-/MH7A-induced migration, invasion, adhesion, and tube formation of human umbilical vein endothelial cells (HUVECs). Moreover, WTD significantly reduced the expression of angiogenic activators, including vascular endothelial growth factor (VEGF), VEGFR2, interleukin (IL)-1β, IL-17, transforming growth factor-β, platelet-derived growth factor, placenta growth factor, angiopoietin (Ang) I and Ang II in synovium of CIA rats, and/or in HUVECs. More interestingly, WTD blocked the autophosphorylation of VEGF₁₆₅-induced VEGFR2 and consequently downregulated the signaling pathways of activated AKT, ERK1/2, JNK, and p38 in VEGF₁₆₅-induced HUVECs. These findings suggest for the first time that WTD possesses the anti-angiogenic effect in RA in vivo, ex vivo, and in vitro by interrupting the targeting of VEGFR2 activation.

Pharmacological characterisation of CR6086, a potent prostaglandin E2 receptor 4 antagonist, as a new potential disease-modifying anti-rheumatic drug

Background

Prostaglandin E₂ (PGE₂) acts via its EP4 receptor as a cytokine amplifier (e.g., interleukin [IL]-6) and induces the differentiation and expansion of inflammatory T-helper (Th) lymphocytes. These mechanisms play a key role in the onset and progression of rheumatoid arthritis (RA). We present the pharmacological characterisation of CR6086, a novel EP4 receptor antagonist, and provide evidence for its potential as a disease-modifying anti-rheumatic drug (DMARD).

Methods

CR6086 affinity and pharmacodynamics were studied in EP4-expressing HEK293 cells by radioligand binding and cyclic adenosine monophosphate (cAMP) production, respectively. In immune cells, IL-6 and vascular endothelial growth factor (VEGF) expression were analysed by RT-PCR, and IL-23 and IL-17 release were measured by enzyme-linked immunosorbent assay (ELISA). In collagen-induced arthritis (CIA) models, rats or mice were immunised with bovine collagen type II. Drugs were administered orally (etanercept and methotrexate intraperitoneally) starting at disease onset. Arthritis progression was evaluated by oedema, clinical score and histopathology. Anti-collagen II immunoglobulin G antibodies were measured by ELISA.

Results

CR6086 showed selectivity and high affinity for the human EP4 receptor (K_i = 16.6 nM) and functioned as a pure antagonist (half-maximal inhibitory concentration, 22 nM) on PGE₂-stimulated cAMP production. In models of human immune cells in culture, CR6086 reduced key cytokine players of RA (IL-6 and VEGF expression in macrophages, IL-23 release from dendritic cells, IL-17 release from Th17 cells). In the CIA model of RA in rats and mice, CR6086 significantly improved all features of arthritis: severity, histology, inflammation and pain. In rats, CR6086 was better than the selective cyclooxygenase-2 inhibitor rofecoxib and at least as effective as the Janus kinase inhibitor tofacitinib. In mice, CR6086 and the biologic DMARD etanercept were highly effective, whereas the non-steroidal anti-inflammatory drug naproxen was ineffective. Importantly, in a study of CR6086/methotrexate, combined treatment greatly improved the effect of a fully immunosuppressive dose of methotrexate.

Conclusions

CR6086 is a novel, potent EP4 antagonist showing favourable immunomodulatory properties, striking DMARD effects in rodents, and anti-inflammatory activity targeted to immune-mediated inflammatory diseases and distinct from the general effects of cyclooxygenase inhibitors. These results support the clinical development of CR6086, both as a stand-alone DMARD and as a combination therapy with methotrexate. The proof-of-concept trial in patients with RA is ongoing.

Electronic supplementary material

The online version of this article (10.1186/s13075-018-1537-8) contains supplementary material, which is available to authorized users.

SIRT1 promotes tumor-like invasion of fibroblast-like synoviocytes in rheumatoid arthritis via targeting TIMP1

Suppression of tissue inhibitor of matrix metalloproteinase (TIMP) is associated with the tumor-like invasion of fibroblast-like synoviocytes (FLSs) that occurs during rheumatoid arthritis-related cartilage destruction. Silent information regulator 2 homolog1 (SIRT1), a histone deacetylase, is widely involved in transcriptional regulation, genomic stability, metabolism and DNA repair. Recent studies suggest that SIRT1 may also impact inflammatory response and the proliferation of FLSs in rheumatoid arthritis (RA). However, it is unknown whether SIRT1 has a role in the tumor-like invasion of FLSs in rheumatoid arthritis. Herein we report that SIRT1 contributes to FLS invasion and cartilage destruction via a TIMP1-dependent mechanism. Elevated SIRT1 in RA synovia suppresses TIMP1 expression via deacetylation of TIMP1-associated histones, thereby disrupting the binding of the transcription factor specificity protein 1 (Sp1) to the TIMP1 promoter. In rats with collagen-induced arthritis, depletion of SIRT1 remarkably promoted TIMP1 expression in synovial tissues and ameliorated cartilage destruction. These results describe a new role for SIRT1 and demonstrate its potential value as a therapeutic target for rheumatoid arthritis.

The Role of Tumor Microenvironment in Chemoresistance: To Survive, Keep Your Enemies Closer

Chemoresistance is a leading cause of morbidity and mortality in cancer and it continues to be a challenge in cancer treatment. Chemoresistance is influenced by genetic and epigenetic alterations which affect drug uptake, metabolism and export of drugs at the cellular levels. While most research has focused on tumor cell autonomous mechanisms of chemoresistance, the tumor microenvironment has emerged as a key player in the development of chemoresistance and in malignant progression, thereby influencing the development of novel therapies in clinical oncology. It is not surprising that the study of the tumor microenvironment is now considered to be as important as the study of tumor cells. Recent advances in technological and analytical methods, especially ‘omics’ technologies, has made it possible to identify specific targets in tumor cells and within the tumor microenvironment to eradicate cancer. Tumors need constant support from previously ‘unsupportive’ microenvironments. Novel therapeutic strategies that inhibit such microenvironmental support to tumor cells would reduce chemoresistance and tumor relapse. Such strategies can target stromal cells, proteins released by stromal cells and non-cellular components such as the extracellular matrix (ECM) within the tumor microenvironment. Novel in vitro tumor biology models that recapitulate the in vivo tumor microenvironment such as multicellular tumor spheroids, biomimetic scaffolds and tumor organoids are being developed and are increasing our understanding of cancer cell-microenvironment interactions. This review offers an analysis of recent developments on the role of the tumor microenvironment in the development of chemoresistance and the strategies to overcome microenvironment-mediated chemoresistance. We propose a systematic analysis of the relationship between tumor cells and their respective tumor microenvironments and our data show that, to survive, cancer cells interact closely with tumor microenvironment components such as mesenchymal stem cells and the extracellular matrix.

Fibroblast-like synoviocyte metabolism in the pathogenesis of rheumatoid arthritis

An increasing number of studies show how changes in intracellular metabolic pathways alter tumor and immune cell function. However, little information about metabolic changes in other cell types, including synovial fibroblasts, is available. In rheumatoid arthritis (RA), fibroblast-like synoviocytes (FLS) are the most common cell type at the pannus–cartilage junction and contribute to joint destruction through their production of cytokines, chemokines, and matrix-degrading molecules and by migrating and invading joint cartilage. In this review, we show that these cells differ from healthy synovial fibroblasts, not only in their marker expression, proto-oncogene expression, or their epigenetic changes, but also in their intracellular metabolism. These metabolic changes must occur due to the stressful microenvironment of inflamed tissues, where concentrations of crucial nutrients such as glucose, glutamine, and oxygen are spatially and temporally heterogeneous. In addition, these metabolic changes will increase metabolite exchange between fibroblast and other synovial cells, which can potentially be activated. Glucose and phospholipid metabolism as well as bioactive lipids, including sphingosine-1-phosphate and lysophosphatidic acid, among others, are involved in FLS activation. These metabolic changes likely contribute to FLS involvement in aspects of immune response initiation or abnormal immune responses and strongly contribute to joint destruction.