Notch signalling pathways mediate synovial angiogenesis in response to vascular endothelial growth factor and angiopoietin 2

Melatonin inhibits 17β-estradiol-induced migration, invasion and epithelial-mesenchymal transition in normal and endometriotic endometrial epithelial cells

BACKGROUND

Melatonin is a potential therapeutic agent for endometriosis, but its molecular mechanism is unclear. Here, we investigated the effect of melatonin on the epithelial-mesenchymal transition (EMT) in endometriotic endometrial epithelial cells and explored the pathway that might be involved.

METHODS

This hospital-based study included 60 women of reproductive age using the endometrium for immunohistochemistry, 6 women of reproductive age undergoing bilateral tubal ligation and 6 patients with endometriosis for isolation of endometrial epithelial cells or subsequent analysis, respectively. We examined the expression of Notch1/Numb signaling and EMT markers by immunohistochemistry analysis and western blot analysis, the invasion and migration of endometrial epithelial cells by transwell assays, and the cell proliferation by CCK8 assays.

RESULTS

Compared with normal endometrium, the endometriotic eutopic endometrium showed increased expression of Notch1, Slug, Snail, and N-cadherin, and decreased expression of E-cadherin and Numb. Melatonin or Notch inhibition by specific inhibitor blocked 17β-estradiol-induced cell proliferation, invasion, migration and EMT-related markers in both normal and endometriotic epithelial cells.

CONCLUSIONS

Our data suggest that aberrant expression of Notch1/Numb signaling and the EMT is present in endometriotic endometrium. Melatonin may block 17β-estradiol-induced migration, invasion and EMT in normal and endometriotic epithelial cells by upregulating Numb expression and decreasing the activity of the Notch signaling pathway.

The pathogenesis of psoriatic arthritis

Psoriatic arthritis is a chronic, immune-mediated, inflammatory arthropathy that presents with inflammation of the joints and entheses, including those of the axial skeleton, and is associated with increased mortality from cardiovascular disease. Diagnosis is primarily based on clinical phenotype because of the diversity of the associated features, which can include skin and nail disease, dactylitis, uveitis, and osteitis. Improved understanding of the pathogenesis of psoriatic arthritis has led to the development of effective biologics and small-molecular drugs targeting specific cytokines and signalling pathways, which can prevent disease progression and improve quality of life. However, at least 40% of patients with psoriatic arthritis have only a partial response or fail to respond to such treatments. Cytokine inhibitors, mainly those specific for tumour necrosis factor and, more recently, the interleukin 23-T-helper-17 cell pathway, have been highly successful in the treatment of disease manifestations in several different tissues, although targeting the interleukin 23-T-helper-17 cell pathway might be more effective in psoriasis than in arthritis. However, the precise mechanisms underlying the pathogenesis of psoriatic arthritis-which include genetics, environmental factors, and immune-mediated inflammation-are complex, and the relationship between disease of the joint and that of other domains is poorly understood. Improving our understanding of psoriatic arthritis pathogenesis could help to establish validated biomarkers for diagnosis, predict therapeutic response and remission, develop precision medicines, and predict which patients will respond to which therapy. We discuss advances in pathogenetic translational research that could inform these issues.

Combined bioinformatics analysis reveals gene expression and DNA methylation patterns in osteoarthritis

Osteoarthritis (OA) is a common type of arthritis, which may cause pain and disability. Alterations in gene expression and DNA methylation have been proven to be associated with the development of OA. The aim of the present study was to identify potential therapeutic targets and associated processes for OA via the combined analysis of gene expression and DNA methylation datasets. The gene expression and DNA methylation profiles were obtained from the Gene Expression Omnibus, and differentially expressed genes (DEGs) and differentially methylated sites (DMSs) were identified in the present study, using R programming software. The enriched functions of DEGs and DMSs were obtained via the Database for Annotation, Visualization and Integrated Discovery. Finally, cross analysis of DEGs and DMSs was performed to identify genes that exhibited differential expression and methylation simultaneously. The protein‑protein interaction (PPI) network of overlaps between DEGs and DMSs was obtained using the Human Protein Reference Database; the topological properties of PPI network overlaps were additionally obtained. Hub genes in the PPI network were further confirmed via reverse transcription‑quantitative polymerase chain reaction (RT‑qPCR). The results of the present study revealed that the majority of DEGs and DMSs were upregulated and hypomethylated in patients with OA, respectively. DEGs and DMSs were primarily involved in inflammatory, immune and gene expression regulation‑associated processes and pathways. Cross analysis revealed 30 genes that exhibited differential expression and methylation in OA simultaneously. Topological analysis of the PPI network revealed that numerous genes, including G protein subunit α1 (GNAI1), runt related transcription factor 2 (RUNX2) and integrin subunit β2 (ITGB2), may be involved in the development of OA. Additionally, RT‑qPCR analysis of GNAI1, RUNX2 and ITGB2 provided further confirmation. Numerous known and novel therapeutic targets were obtained via network analysis. The results of the present study may be beneficial for the diagnosis and treatment of OA.

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.

Excessive angiogenesis associated with psoriasis as a cause for cardiovascular ischaemia

Psoriasis, a common disease affecting 2%-3% of the UK population, produces significant impairment of quality of life and is an immense burden on sufferers and their families. Psoriasis is associated with significant cardiovascular comorbidity and the metabolic syndrome. Angiogenesis, a relatively under-researched component of psoriasis, is a key factor in pathogenesis of psoriasis and also contributes to the development of atherosclerosis. Vascular endothelial growth factor (VEGF) is a well-established mediator of pathological angiogenesis which is upregulated in psoriasis. It is possible that, in patients with psoriasis, cutaneous angiogenesis may be both a marker for systemic vascular pathology and a novel therapeutic target. In this viewpoint study, the role of VEGF-mediated angiogenesis as a cause for cardiovascular events in patients with psoriasis is explored.

Is macrophage polarization important in rheumatoid arthritis?

Macrophages are myeloid immune cells which are strategically positioned throughout the body, where they engulf and degrade debris, dead cells, and foreign substances, and coordinating the inflammatory processes. Macrophages can be divided into two extreme subsets, classical activation (M1), and alternatively activation (M2). The symptoms and signs of rheumatoid arthritis (RA) would exacerbate with the increase in pro-inflammatory cytokines, whereas anti-inflammatory cytokines will alleviate the symptoms and signs of RA. This review, mainly discusses the effects of Notch, JNK and ERK signaling pathways on the regulation of macrophage polarization, and the effects of pro-inflammatory factors and/or anti-inflammatory cytokines produced by polarized macrophages in RA. Also, we will make an attempt to find out the importance of macrophage polarization in RA treatment as a drug target.

Small molecule therapeutics for inflammation-associated chronic musculoskeletal degenerative diseases: Past, present and future

Inflammation-associated chronic musculoskeletal degenerative diseases (ICMDDs) like osteoarthritis and tendinopathy often results in morbidity and disability, with consequent heavy socio-economic burden. Current available therapies such as NSAIDs and glucocorticoid are palliative rather than disease-modifying. Insufficient systematic research data on disease molecular mechanism also makes it difficult to exploit valid therapeutic targets. Small molecules are designed to act on specific signaling pathways and/or mechanisms of cellular physiology and function, and have gradually shown potential for treating ICMDDs. In this review, we would examine and analyze recent developments in small molecule drugs for ICMDDs, suggest possible feasible improvements in treatment modalities, and discuss future research directions.

Angiogenesis Dysregulation in Psoriatic Arthritis: Molecular Mechanisms

There is evidence that psoriatic arthritis is closely linked to angiogenesis. Morphological changes described in blood vessels of psoriatic arthritis joints suggest the presence of a dysregulated angiogenesis resulting in the formation of immature vessels. Even if the reason of this inefficient angiogenesis is still unclear, an imbalance between angiogenic and antiangiogenic factors is probably responsible for inducing a dysregulated angiogenesis in psoriatic arthritis, which seems to be involved in its pathogenesis and clinical features. Nevertheless, among chronic arthritides, while angiogenesis in rheumatoid arthritis has been largely studied with a great amount of literature data, limited data on angiogenesis role in psoriatic arthritis are available. This review article is focused on current knowledge on the mechanisms responsible for dysregulated angiogenesis in psoriatic arthritis.

Targeting Notch-Activated M1 Macrophages Attenuates Joint Tissue Damage in a Mouse Model of Inflammatory Arthritis

Expression levels of Notch signaling molecules are increased in synovium from patients with rheumatoid arthritis (RA). However, it is not known which cell type(s) in RA synovium have Notch activation or if they play a pathogenetic role in RA. Here, we used Hes1-GFP/TNF-transgenic (TNF-Tg) mice to investigate the role of cells with active Notch signaling (GFP+) in RA. The number of GFP+ cells was significantly increased in synovium in Hes1-GFP/TNF-Tg mice and about 60% of them were F4/80+ macrophages expressing the inflammatory macrophage (M1) marker. TNF-Tg mice transplanted with Hes1-GFP/TNF-Tg bone marrow (BM) had significantly more GFP+ cells in their synovium than in BM. Intraarticular injection of Hes1-GFP/TNF-Tg or Hes1-GFP+ BM macrophages into WT and TNF-Tg mice showed the highest synovial GFP+ cells in the TNF-Tg mice that received Hes1-GFP/TNF-Tg cells. Thapsigargin (THAP), a Notch inhibitor, decreased TNF-induced M1 and increased M2 numbers and reduced joint lesion, synovial M1s, and GFP+ cells in Hes1-GFP/TNF-Tg mice. THAP did not affect M1s from mice carrying a constitutively active Notch1. Thus, the main cells with activated Notch signaling in the inflamed synovium of TNF-Tg mice are M1s derived from BM and targeting them may represent a new therapeutic approach for patients with inflammatory arthritis. © 2017 American Society for Bone and Mineral Research.

MicroRNA-29a Counteracts Synovitis in Knee Osteoarthritis Pathogenesis by Targeting VEGF

Synovitis contributes to the development of osteoarthritis (OA) of the knee. MicroRNAs regulate joint microenvironment homeostasis and deterioration. This study was undertaken to characterize the actions of microRNA-29a (miR-29a) to synovial remodeling in OA joints. Synovial specimens isolated from patients with end-stage OA knees showed abundant fibrotic matrix and vessel histopathology concomitant with weak miR-29a expression. In vitro, miR-29a knockdown caused synovial fibroblasts to exhibit high expressions of collagen III, TGF-β1, MMP9, MMP13, and ADAMTS5, whereas miR-29a overexpression diminished these joint-deleterious factors. In collagenase-mediated OA pathogenesis, miR-29a-overexpressing transgenic mice showed minor responses to hyperplasia, macrophage infiltration, fibrosis, hyperangiogenesis, and VEGF expression in synovial lesions. These effects mitigated articular cartilage loss and gait aberrance of injured joints. Intra-articular administration of miR-29a precursor lessened the collagenase aggravation of excessive synovial remodeling reactions and thereby sustained joint tissue integrity. miR-29a lowered VEGF production and angiogenic activities in synovial fibroblasts through targeting the 3′-UTR of VEGF. Taken together, miR-29a deficiency exacerbated synovitis pathogenesis in the end-stage OA knees. miR-29a signaling fends off excessive synovial angiogenesis and fibrosis, which delays joint destruction. This study sheds new light on the protective effects against synovial deterioration and the therapeutic advantage of miR-29a in OA knees.

Angiopoietin-2 Enhances Osteogenic Differentiation of Bone Marrow Stem Cells

Our previous studies revealed that co-transplantation of bone marrow stem cells (BMSCs) and adipose-derived stem cells (ADSCs) can enhance bone regeneration and angiogenesis. However, it is unclear which genes are involved in the regulation of osteogenesis and/or angiogenesis during the co-culturing of BMSCs and ADSCs. The expression patterns of genes associated with osteogenesis and/or angiogenesis were analyzed in osteogenesis-induced BMSCs and ADSCs using an oligonucleotide microarray. Significant difference in the expression patterns of several genes were identified from hierarchical clustering and analyzed on co-cultured BMSCs and ADSCs. Angiopoietin-2 (ANGPT2) and activin receptor-like kinase-1 were significantly down-regulated in co-culture than culture of either BMSCs or ADSCs, while fibroblast growth factor-9 was significantly up-regulated in co-culture. The effect of ANGPT2 in osteogenesis-induced BMSCs was validated using recombinant protein and siRNA of ANGPT2. Treatment of the ANGPT2 protein significantly increased the expressions of osteogenic makers and the intensity of Alizarin red-S staining in BMSCs. Down-regulation of ANGPT2 significantly decreased the expression of osteogenic makers. The treatment of ANGPT2 protein to BMSCs induced significantly increased tube formation in Transwell-co-cultured human umbilical vein endothelial cells (HUVECs) compared with untreated control. ANGPT2 siRNA transfection showed the opposite effects. These results suggest that the treatment of ANGPT2 in BMSCs increase osteogenesis and angiogenesis in vitro, and that the enhancement of osteogenesis and angiogenesis in the co-cultured BMSCs and ADSCs seems to be mediated by a mechanism that makes the activation of ANGPT2 unnecessary. These observations provide the first evidence for positive regulation of osteogenesis by ANGPT2 in vitro. J. Cell. Biochem. 118: 2896-2908, 2017. © 2017 Wiley Periodicals, Inc.

Resolution of TLR2-induced inflammation through manipulation of metabolic pathways in Rheumatoid Arthritis

During inflammation, immune cells activated by toll-like receptors (TLRs) have the ability to undergo a bioenergetic switch towards glycolysis in a manner similar to that observed in tumour cells. While TLRs have been implicated in the pathogenesis of rheumatoid arthritis (RA), their role in regulating cellular metabolism in synovial cells, however, is still unknown. In this study, we investigated the effect of TLR2-activation on mitochondrial function and bioenergetics in primary RA-synovial fibroblast cells (RASFC), and further determined the role of glycolytic blockade on TLR2-induced inflammation in RASFC using glycolytic inhibitor 3-(3-pyridinyl)-1-(4-pyridinyl)-2-propen-1-one (3PO). We observed an increase in mitochondrial mutations, ROS and lipid peroxidation, paralleled by a decrease in the mitochondrial membrane potential in TLR2-stimulated RASFC. This was mirrored by differential regulation of key mitochondrial genes, coupled with alteration in mitochondrial morphology. TLR2-activation also regulated changes in the bioenergetic profile of RASFC, inducing PKM2 nuclear translocation, decreased mitochondrial respiration and ATP synthesis and increased glycolysis:respiration ratio, suggesting a metabolic switch. Finally, using 3PO, we demonstrated that glycolytic blockade reversed TLR2-induced pro-inflammatory mechanisms including invasion, migration, cytokine/chemokine secretion and signalling pathways. These findings support the concept of complex interplay between innate immunity, oxidative damage and oxygen metabolism in RA pathogenesis.

Xiaotan Sanjie decoction inhibits angiogenesis in gastric cancer through Interleukin-8-linked regulation of the vascular endothelial growth factor pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Interleukin-8 (IL-8) as a pro-angiogenic factor is strongly associated with gastric cancer metastasis. Xiaotan Sanjie (XTSJ) decoction is an empirical compound prescription based on the phlegm theory of traditional Chinese medicine. Previous studies have shown that XTSJ decoction decreases IL-8 level and formation of vasculogenic mimicry of gastric cancer.

AIM OF THE STUDY

To investigate the link between Xiaotan Sanjie (XTSJ) decoction and IL-8 regulation in the angiogenesis of gastric cancer.

MATERIALS AND METHODS

Human umbilical vein endothelial cells (HUVECs) were co-cultured with SGC-7901 human gastric cancer cells and exposed to serum samples containing XTSJ decoction and/or IL-8 (1.0ng/mL). The canalization and migration capacities were evaluated by tube formation and transwell migration assay. Protein (immunofluorescence and Western blot) and mRNA (qPCR) expressions were measured in 24-h-cultured HUVECs for vascular endothelial growth factor-A (VEGF-A), vascular endothelial growth factor receptor (VEGFR)-1, and VEGFR-2.

RESULTS

IL-8 significantly promoted and XTSJ decoction inhibited HUVEC tube formation and migration. Links between IL-8 regulation and XTSJ decoction were found in tube formation and migration assays. IL-8 upregulated and XTSJ decoction downregulated VEGF-A, VEGFR-1, and VEGFR-2 protein levels. XTSJ decoction inhibited IL-8-induced VEGF-A and VEGFR-1 protein expressions. Similarly, IL-8 promoted VEGF-A, VEGFR-1, and VEGFR-2 mRNA levels; however, XTSJ decoction inhibited only VEGF-A mRNA. Interestingly, XTSJ decoction inhibited IL-8-induced VEGFR-1 and VEGFR-2 mRNA expression.

CONCLUSION

XTSJ decoction might inhibit angiogenesis in gastric cancer through IL-8-linked regulation of the VEGF pathway.

Microvesicles in Autoimmune Diseases

During apoptosis or activation, cells can release a subcellular structure, called a membrane microvesicle (also known as microparticle) into the extracellular environment. Microvesicles bud-off as a portion of cell membrane with its associated proteins and lipids surrounding a cytosolic core that contains intracellular proteins, lipids, and nucleic acids (DNA, RNA, siRNA, microRNA, lncRNA). Biologically active molecules on the microvesicle surface and encapsulated within can act on recipient cells as a novel mode of intercellular communication. Apoptosis has long been known to be involved in the development of diseases of autoimmunity. Abnormally persistent microvesicles, particularly apoptotic microvesicles, can accelerate autoimmune responses locally in specific organs and tissues as well as systemically. In this review, we focus on studies implicating microvesicles in the pathogenesis of autoimmune diseases and their complications.

The role of the AMOP domain in MUC4/Y-promoted tumour angiogenesis and metastasis in pancreatic cancer

BACKGROUND

MUC4 is a high molecular weight membrane protein that is overexpressed in pancreatic cancer (PC) and is associated with the development and progression of this disease. However, the exact mechanisms through which MUC4 domains promote these biological processes have rarely been studied, partly because of its high molecular weight, difficulty to overexpress it. Here, we use MUC4/Y, one of the MUC4 transcript variants, as a model molecule to investigate the AMOP-domain of MUC4(MUC/Y).

METHODS

We used cell proliferation, migration, invasion and tube formation assays in vitro to explore the abilities of AMOP domain in PC. In vivo, the matrigel plug assay, orthotopic implantation and Kaplan-Meier survival curves were used to check the results we observed in vitro. Finally, we discovered the underlying mechanism through western blot and immunofluorescence.

RESULTS

We found that MUC4/Y overexpression could enhance the angiogenic and metastatic properties of PC cells, both in vitro and in vivo. However, the deletion of AMOP domain could cutback these phenomena. Additionally, Kaplan-Meier survival curves showed that mice injected with MUC4/Y overexpressed cells had shorter survival time, compared with empty-vector-transfected cells (MUC4/Y-EV), or cells expressing MUC4/Y without the AMOP domain (MUC4/Y-AMOP(△)). Our data also showed that overexpression of MUC4/Y could activate NOTCH3 signaling, increasing the expression of downstream genes: VEGF-A, MMP-9 and ANG-2.

CONCLUSIONS

The AMOP domain had an important role in MUC4/Y (MUC4)-mediated tumour angiogenesis and metastasis of PC cells; and the NOTCH3 signaling was involved. These findings provided new insights into PC therapies. Our study also supplies a new method to study other high molecular membrane proteins.

Photoactivatable Caged Prodrugs of VEGFR-2 Kinase Inhibitors

In this study, we report on the design, synthesis, photokinetic properties and in vitro evaluation of photoactivatable caged prodrugs for the receptor tyrosine kinase VEGFR-2. Highly potent VEGFR-2 inhibitors 1 and 3 were caged by introduction of a photoremovable protecting group (PPG) to yield the caged prodrugs 4 and 5. As expected, enzymatic and cellular proliferation assays showed dramatically diminished efficacy of caged prodrugs in vitro. Upon ultraviolet (UV) irradiation of the prodrugs original inhibitory activity was completely restored and even distinctly reinforced, as was the case for the prodrug 4. The presented results are a further evidence for caging technique being an interesting approach in the protein kinase field. It could enable spatial and temporal control for the inhibition of VEGFR-2. The described photoactivatable prodrugs might be highly useful as biological probes for studying the VEGFR-2 signal transduction.

Utilization of nanoparticle technology in rheumatoid arthritis treatment

Rheumatoid arthritis (RA) is one of the common and severe autoimmune diseases related to joints. This chronic autoimmune inflammatory disease, leads to functional limitation and reduced quality of life, since as there is bone and cartilage destruction, joint swelling and pain. Current advances and new treatment approaches have considerably postponed disease progression and improved the quality of life for many patients. In spite of major advances in therapeutic options, restrictions on the routes of administration and the necessity for frequent and long-term dosing often result in systemic adverse effects and patient non-compliance. Unlike usual drugs, nanoparticle systems are planned to deliver therapeutic agents especially to inflamed synovium, so avoiding systemic and unpleasant effects. The present review discusses about some of the most successful drugs in RA therapy and their side effects and also focuses on key design parameters of RA-targeted nanotechnology-based strategies for improving RA therapies.

Targeting of proangiogenic signalling pathways in chronic inflammation

Angiogenesis is de novo capillary outgrowth from pre-existing blood vessels. This process not only is crucial for normal development, but also has an important role in supplying oxygen and nutrients to inflamed tissues, as well as in facilitating the migration of inflammatory cells to the synovium in rheumatoid arthritis, spondyloarthritis and other systemic autoimmune diseases. Neovascularization is dependent on the balance of proangiogenic and antiangiogenic mediators, including growth factors, cytokines, chemokines, cell adhesion molecules and matrix metalloproteinases. This Review describes the various intracellular signalling pathways that govern these angiogenic processes and discusses potential approaches to interfere with pathological angiogenesis, and thereby ameliorate inflammatory disease, by targeting these pathways.

Pristimerin inhibits angiogenesis in adjuvant-induced arthritic rats by suppressing VEGFR2 signaling pathways

Rheumatoid arthritis (RA) is a progressive, inflammatory autoimmune disease. As RA progresses, the hyperplastic synovial pannus creates a hypoxic, inflammatory environment that induces angiogenesis. Further vascularization of the synovial tissue promotes pannus growth and continued infiltration of inflammatory leukocytes, thus perpetuating the disease. Pristimerin inhibits inflammation and tumor angiogenesis. The present study focused on the inhibition of angiogenesis by Pristimerin in adjuvant-induced arthritic rats and the underlying molecular mechanisms. Our results clearly demonstrate for the first time that Pristimerin significantly reduces vessel density in synovial membrane tissues of inflamed joints and reduces the expression of pro-angiogenic factors in sera, including TNF-α, Ang-1, and MMP-9. Pristimerin also decreased the expression of VEGF and p-VEGFR2 in the synovial membrane, whereas the total amount of VEGFR2 remained unchanged. Pristimerin suppressed the sprouting vessels of the aortic ring and inhibited VEGF-induced HFLS-RA migration in vitro. Pristimerin also inhibited VEGF-induced proliferation, migration and tube formation by HUVECs, blocked the autophosphorylation of VEGF-induced VEGFR2 and consequently downregulated the signaling pathways of activated PI3K, AKT, mTOR, ERK1/2, JNK, and p38 in VEGF-induced HUVECs. Our results indicate that Pristimerin suppressed synovial angiogenesis in our rat model and in vitro by interrupting the targeting of VEGFR2 activation. Therefore, Pristimerin has potential as an angiogenesis inhibitor in the treatment of rheumatoid arthritis.

Acute serum amyloid A is an endogenous TLR2 ligand that mediates inflammatory and angiogenic mechanisms

INTRODUCTION

Acute-phase serum amyloid A (A-SAA) has cytokine-like properties and is expressed at sites of inflammation. We examined whether A-SAA-induced pro-inflammatory mechanisms are mediated through Toll-like receptor 2 (TLR2) in rheumatoid arthritis (RA).

METHODS

The effect of A-SAA on human embryonic kidney (HEK), TLR2 or TLR4 cells was quantified by nuclear factor (NF)-κB luciferase reporter assays. A-SAA-induced RASFC and dHMVEC function were performed in the presence of a specific neutralising anti-TLR2 mAb (OPN301) (1 μg/mL) and matched IgG isotype control Ab (1 μg/mL). Cell surface expression of intracellular adhesion molecule (ICAM)-1, chemokine expression, cell migration, invasion and angiogenesis were assessed by flow cytometry, ELISA, Matrigel invasion chambers and tube formation assays. MyD88 expression was assessed by real-time PCR and western blot.

RESULTS

A-SAA induced TLR2 activation through induction of NF-κB (p<0.05), but failed to induce NF-κB in HEK-TLR4 cells, confirming specificity for TLR2. A-SAA-induced proliferation, invasion and migration were significantly inhibited in the presence of anti-TLR2 (all p<0.05), with no significant effect observed for tumour necrosis factor-α-induced events. Additionally, A-SAA-induced ICAM-1, interleukin-8, monocyte chemoattractant protein-1, RANTES and GRO-α expression were significantly reduced in the presence of anti-TLR2 (all p<0.05), as was A-SAA induced angiogenesis (p<0.05). Finally, A-SAA induced MyD88 signalling in RASFC and dHMVEC (p<0.05).

CONCLUSIONS

A-SAA is an endogenous ligand for TLR2, inducing pro-inflammatory effects in RA. Blocking the A-SAA/TLR2 interaction may be a potential therapeutic intervention in RA.

Bioinformatics analysis of potential essential genes that response to the high intraocular pressure on astrocyte due to glaucoma

AIM

To study the gene expression response and predict the network in cell due to pressure effects on optic nerve injury of glaucoma.

METHODS

We used glaucoma related microarray data in public database [Gene Expression Omnibus (GEO)] to explore the potential gene expression changes as well as correspondent biological process alterations due to increased pressure in astrocytes during glaucoma development.

RESULTS

A total of six genes were identified to be related with pressure increasing. Through the annotation and network analysis, we found these genes might be involved in cell morphological remodeling, angiogenesis, mismatch repair.

CONCLUSION

Increasing pressure in glaucoma on astrocytes might cause gene expression alterations, which might induce some cellular responses changes.

Update on implications and mechanisms of angiogenesis in liver fibrosis

Liver fibrosis occurs as a compensatory response to the process of tissue repair in a wide range of chronic liver injures. It is characterized by excessive deposition of extracellular matrix in liver tissues. As the pathogenesis progresses without effective management, it will lead to formation of liver fiber nodules and disruption of normal liver structure and function, finally culminating in cirrhosis and hepatocellular carcinoma. A new discovery shows that liver angiogenesis is strictly associated with, and may even favor fibrogenic progression of chronic liver diseases. Recent basic and clinical investigations also demonstrate that liver fibrogenesis is accompanied by pathological angiogenesis and sinusoidal remodeling, which critically determine the pathogenesis and prognosis of liver fibrosis. Inhibition of pathological angiogenesis is considered to be a new strategy for the treatment of liver fibrosis. This review summarizes current knowledge on the process of angiogenesis, the relationships between angiogenesis and liver fibrosis, and on the molecular mechanisms of liver angiogenesis. On the other hand, it also presents the different strategies that have been used in experimental models to counteract excessive angiogenesis and the role of angiogenesis in the prevention and treatment of liver fibrosis.

Matrigel: from discovery and ECM mimicry to assays and models for cancer research

The basement membrane is an important extracellular matrix that is found in all epithelial and endothelial tissues. It maintains tissue integrity, serves as a barrier to cells and to molecules, separates different tissue types, transduces mechanical signals, and has many biological functions that help to maintain tissue specificity. A well-defined soluble basement membrane extract, termed BME/Matrigel, prepared from an epithelial tumor is similar in content to authentic basement membrane, and forms a hydrogel at 24-37°C. It is used in vitro as a substrate for 3D cell culture, in suspension for spheroid culture, and for various assays, such as angiogenesis, invasion, and dormancy. In vivo, BME/Matrigel is used for angiogenesis assays and to promote xenograft and patient-derived biopsy take and growth. Studies have shown that both the stiffness of the BME/Matrigel and its components (i.e. chemical signals) are responsible for its activity with so many different cell types. BME/Matrigel has widespread use in assays and in models that improve our understanding of tumor biology and help define therapeutic approaches.

Hyaluronan nanoparticles bearing γ-secretase inhibitor: in vivo therapeutic effects on rheumatoid arthritis

γ-Secretase inhibitors which prevent Notch activation are emerging as potent therapeutics for various inflammatory diseases, including ischemic stroke and rheumatoid arthritis. However, their indiscriminate distribution in the body causes serious side effects after systemic administration, since Notch proteins are ubiquitous receptors that play an important role in cellular functions such as differentiation, proliferation, and apoptosis. In this study, hyaluronan nanoparticles (HA-NPs) bearing a γ-secretase inhibitor (DAPT) were prepared as potential therapeutics for rheumatoid arthritis. In vivo biodistribution of the DAPT-loaded HA-NPs (DNPs), labeled with near-infrared dye, were observed using a non-invasive optical imaging system after systemic administration to a collagen-induced arthritis (CIA) mouse model. The results demonstrated that DNPs were effectively accumulated at the inflamed joint of the CIA mice. From the in vivo therapeutic efficacy tests, DNPs (1mg DAPT/kg) significantly attenuated the severity of RA induction compared to DAPT alone (2mg/kg), which was judged from clinical scores, tissue damage, and neutrophil infiltration. In addition, DNPs dramatically reduced the production of pro-inflammatory cytokines (TNF-α, IFN-γ, MCP-1, and IL-6, -12, -17) and collagen-specific auto-antibodies (IgG1 and IgG2a) in the serum of the CIA mice. These results suggest that DNPs have potential as therapeutics for rheumatoid arthritis.

Angiogenic cytokine expression profiles in plasma and synovial fluid of primary knee osteoarthritis

PURPOSE

The aim of this study was to compare angiogenic cytokine levels in knee osteoarthritis (OA) patients and healthy controls and to investigate the relationships between angiogenic cytokines and the OA severity.

METHODS

Thirty-one knee OA patients and 15 healthy controls were recruited. Nine angiogenic cytokines (angiopoietin-2, follistatin, granulocyte-colony stimulating factor (G-CSF), hepatocyte growth factor (HGF), interleukin (IL)-8, leptin, platelet-derived growth factor-BB (PDGF-BB), platelet endothelial cell adhesion molecule (PECAM)-1, and vascular endothelial growth factor (VEGF)) in plasma and synovial fluid were measured using a multiplex immunoassay.

RESULTS

PECAM-1, HGF, VEGF, angiopoietin-2, follistatin, G-CSF, and IL-8 concentrations in plasma were significantly higher in OA patients than those in controls. Plasma angiopoietin-2 was significantly greater in advanced OA than in early OA. Synovial fluid VEGF was positively correlated with the severity (r = 0.367, P = 0.04). Plasma follistatin was significantly lower in advanced knee OA than in early OA and was negatively correlated with the severity (r = -0.374, P < 0.05).

CONCLUSIONS

Angiogenic cytokine concentrations in plasma can distinguish between controls and OA patients. Local and circulating levels of angiogenic cytokines could give an insight into the pathophysiology of OA. Follistatin, angiopoietin-2, and VEGF may have potential as biochemical markers for the assessment of OA severity.

Targeting the synovial angiogenesis as a novel treatment approach to osteoarthritis

Synovitis is a key feature in osteoarthritis and is associated with symptom severity. Synovial membrane inflammation is secondary to cartilage degradation which occurs in the early stage and is located adjacent to cartilage damage. This inflammation is characterized by the invasion and activation of macrophages and lymphocytes, the release in the joint cavity of large amounts of pro-inflammatory and procatabolic mediators, and by a local increase of synovial membrane vascularity. This latter process plays an important role in the chronicity of the inflammatory reaction by facilitating the invasion of the synovium by immune cells. Therefore, synovial membrane angiogenesis represents a key target for the treatment of osteoarthritis. This paper is a narrative review of the literature referenced in PubMed during the past 5 years. It addresses in particular three questions. What are the mechanisms involved in synovium blood vessels invasion? Are current medications effective in controlling blood vessels formation and invasion? What are the perspectives of research in this area?

A network-based kernel machine test for the identification of risk pathways in genome-wide association studies

Biological pathways provide rich information and biological context on the genetic causes of complex diseases. The logistic kernel machine test integrates prior knowledge on pathways in order to analyze data from genome-wide association studies (GWAS). In this study, the kernel converts the genomic information of 2 individuals into a quantitative value reflecting their genetic similarity. With the selection of the kernel, one implicitly chooses a genetic effect model. Like many other pathway methods, none of the available kernels accounts for the topological structure of the pathway or gene-gene interaction types. However, evidence indicates that connectivity and neighborhood of genes are crucial in the context of GWAS, because genes associated with a disease often interact. Thus, we propose a novel kernel that incorporates the topology of pathways and information on interactions. Using simulation studies, we demonstrate that the proposed method maintains the type I error correctly and can be more effective in the identification of pathways associated with a disease than non-network-based methods. We apply our approach to genome-wide association case-control data on lung cancer and rheumatoid arthritis. We identify some promising new pathways associated with these diseases, which may improve our current understanding of the genetic mechanisms.

Inhibition of notch signalling ameliorates experimental inflammatory arthritis

OBJECTIVE

To test the hypothesis that Notch signalling plays a role in the pathogenesis of rheumatoid arthritis (RA) and to determine whether pharmacological inhibition of Notch signalling with γ-secretase inhibitors can ameliorate the RA disease process in an animal model.

METHODS

Collagen-induced arthritis was induced in C57BL/6 or Notch antisense transgenic mice by immunisation with chicken type II collagen (CII). C57BL/6 mice were administered with different doses of inhibitors of γ-secretase, an enzyme required for Notch activation, at disease onset or after onset of symptoms. Severity of arthritis was monitored by clinical and histological scores, and in vivo non-invasive near-infrared fluorescence (NIRF) images. Micro-CT was used to confirm joint destruction. The levels of CII antibodies and cytokines in serum were determined by ELISA and bead-based cytokine assay. The expression levels of cytokines were studied by quantitative PCR in rheumatoid synovial fibroblasts.

RESULTS

The data show that Notch signalling stimulates synoviocytes and accelerates their production of proinflammatory cytokines and immune responses involving the upregulation of IgG1 and IgG2a. Pharmacological inhibition of γ-secretase and antisense-mediated knockdown of Notch attenuates the severity of inflammatory arthritis, including arthritis indices, paw thickness, tissue damage and neutrophil infiltration, and reduces the levels of active NF-κB, ICAM-1, proinflammatory cytokines and matrix metalloproteinase-3 activity in the mouse model of RA.

CONCLUSIONS

These results suggest that Notch is involved in the pathogenesis of RA and that inhibition of Notch signalling is a novel approach for treating RA.

Hypoxia: how does the monocyte-macrophage system respond to changes in oxygen availability?

Hypoxia is an important feature of inflamed tissue, such as the RA joint. Activated monocytes/macrophages and endothelial cells play a pivotal role in the pathogenesis of RA, implicated in the mechanism of inflammation and erosion. During development, myeloid progenitor cells sequentially give rise to monoblasts, promonocytes, and monocytes that are released from the bone marrow into the bloodstream. After extravasation, monocytes differentiate into long-lived, tissue-specific macrophages or DCs. The effect of different oxygen concentrations experienced by these cells during maturation represents a novel aspect of this developmental process. In inflamed joint tissue, the microvascular architecture is highly dysregulated; thus, efficiency of oxygen supply to the synovium is poor. Therefore, invading cells must adapt instantaneously to changes in the oxygen level of the microenvironment. Angiogenesis is an early event in the inflammatory joint, which is important in enabling activated monocytes to enter via endothelial cells by active recruitment to expand the synovium into a "pannus", resulting in cartilage degradation and bone destruction. The increased metabolic turnover of the expanding synovial pannus outpaces the dysfunctional vascular supply, resulting in hypoxia. The abnormal bioenergetics of the microenvironment further promotes synovial cell invasiveness. In RA, joint hypoxia represents a potential threat to cell function and survival. Notably, oxygen availability is a crucial parameter in the cellular energy metabolism, itself an important factor in determining the function of immune cells.

Angiogenic and inflammatory properties of psoriatic arthritis

Psoriatic arthritis (PsA) is a chronic inflammatory arthropathy associated with psoriasis and included in seronegative spondyloarthropathy. PsA has several unique characteristics different from rheumatoid arthritis (RA), such as enthesopathy, dactylitis, and abnormal bone remodeling. As compared with synovitis of RA (pannus), proliferation of PsA synovium is mild and characterized by hypervascularity and increased infiltration of polymorphonuclear leukocytes in the synovial tissues. Angiogenesis plays a crucial role in cutaneous psoriasis, and several angiogenic factors such as vascular endothelial growth factor, interleukin-8, angiopoietin, tumor necrosis factor- α and transforming growth factor-β, are suggested to play an important role also in the pathophysiology of PsA. Further, IL-17 has various functions such as upregulation of proinflammatory cytokines, attraction of neutrophils, stimulation of keratinocytes, endothelial cell migration, and osteoclast formation via RANKL from activated synovial fibroblasts. Thus, IL-17 may be important in angiogenesis, fibrogenesis, and osteoclastogenesis in PsA. In this paper, roles of angiogenesis in the psoriatic synovium are discussed, which may strengthen the understanding of the pathogenesis of PsA.

Psoriatic arthritis: recent progress in pathophysiology and drug development

Psoriatic arthritis (PsA) is the second most common inflammatory arthropathy, after rheumatoid arthritis diagnosis, in early arthritis clinics. Most patients have established psoriasis, often for years, prior to the onset of joint pain and swelling; in addition, associated features of nail disease, dactylitis, enthesitis, spondylitis or uveitis may be present. Psoriasis may not be immediately apparent, as small or patchy lesions may occur in the scalp or perineum. PsA presents as a symmetrical polyarthritis, similar to rheumatoid arthritis, or an asymmetrical oligoarthritis with a predilection for the distal interphalangeal joints. Spinal involvement is similar, although not identical, to ankylosing spondylitis. Joint damage occurs early; up to 50% of PsA patients have an 11% annual erosion rate in the first 2 years of disease duration, suggesting it is not a benign condition. There have been significant advances in our understanding of PsA pathogenesis in recent years, in the areas of genetics and molecular biology, implicating both the innate and the adaptive immune systems. This has lead to the introduction of evidence-based targeted therapy, primarily with tumour necrosis factor inhibitor (TNFi) agents. Therapy with disease-modifying anti-rheumatic drugs, such as methotrexate and leflunomide, remains the first-choice therapeutic intervention, even though there are few randomised controlled trials with these agents. In contrast, a number of successful studies of TNFi agents demonstrate excellent efficacy, in combination with methotrexate, and several novel agents are currently in development for the treatment of PsA.