Blood vessels, a potential therapeutic target in rheumatoid arthritis?

The protective effect of natural medicines in rheumatoid arthritis via inhibit angiogenesis

Rheumatoid arthritis is a chronic immunological disease leading to the progressive bone and joint destruction. Angiogenesis, accompanied by synovial hyperplasia and inflammation underlies joint destruction. Delaying or even blocking synovial angiogenesis has emerged as an important target of RA treatment. Natural medicines has a long history of treating RA, and numerous reports have suggested that natural medicines have a strong inhibitory activity on synovial angiogenesis, thereby improving the progression of RA. Natural medicines could regulate the following signaling pathways: HIF/VEGF/ANG, PI3K/Akt pathway, MAPKs pathway, NF-κB pathway, PPARγ pathway, JAK2/STAT3 pathway, etc., thereby inhibiting angiogenesis. Tripterygium wilfordii Hook. f. (TwHF), sinomenine, and total glucoside of Paeonia lactiflora Pall. Are currently the most representative of all natural products worthy of development and utilization. In this paper, the main factors affecting angiogenesis were discussed and different types of natural medicines that inhibit angiogenesis were systematically summarized. Their specific anti-angiogenesis mechanisms are also reviewed which aiming to provide new perspective and options for the management of RA by targeting angiogenesis.

CPD-002, a novel VEGFR2 inhibitor, relieves rheumatoid arthritis by reducing angiogenesis through the suppression of the VEGFR2/PI3K/AKT signaling pathway

Synovial angiogenesis is a key player in the development of rheumatoid arthritis (RA), and anti-angiogenic therapy is considered a promising approach for treating RA. CPD-002 has demonstrated efficacy in suppressing tumor angiogenesis as a VEGFR2 inhibitor, but its specific impacts on RA synovial angiogenesis and possible anti-RA effects need further study. We examined the influences of CPD-002 on the migration and invasion of human umbilical vein endothelial cells (HUVECs) and its impacts on HUVECs' tube formation and vessel sprouting ex vivo. The therapeutic potential of CPD-002 in adjuvant-induced arthritis (AIA) rats and its suppression of synovial angiogenesis were examined. The involvement of the VEGFR2/PI3K/AKT pathway was assessed both in HUVECs and AIA rat synovium. Here, CPD-002 inhibited the migration and invasion of VEGF-stimulated HUVECs, decreased their chemotactic response to RA fibroblast-like synoviocyte-released chemoattractants, and exhibited anti-angiogenic effects in vitro and ex vivo. CPD-002's targeting of VEGFR2 was confirmed with molecular docking and cellular thermal shift assays, supported by the abolishment of CPD-002's effects upon using VEGFR2 siRNA. CPD-002 relieved paw swelling, arthritis index, joint damage, and synovial angiogenesis, indicating its anti-arthritic and anti-angiogenic effects in AIA rats. Moreover, the anti-inflammatory effects in vivo and in vitro of CPD-002 contributed to its anti-angiogenic effects. Mechanistically, CPD-002 hindered the activation of VEGFR2/PI3K/AKT pathway in VEGF-induced HUVECs and AIA rat synovium, as evidenced by reduced p-VEGFR2, p-PI3K, and p-AKT protein levels alongside elevated PTEN protein levels. Totally, CPD-002 showed anti-rheumatoid effects via attenuating angiogenesis through the inhibition of the VEGFR2/PI3K/AKT pathway.

Exploring the chondroprotective effect of Chaenomeles speciosa on Glucose-6-Phosphate Isomerase model mice using an integrated approach of network pharmacology and experimental validation

ETHNOPHARMACOLOGICAL RELEVANCE

Traditional Chinese medicine (TCM) has been used in China for a long time and is gradually gaining more and more recognition worldwide. Chaenomeles speciosa (CSP) (Chinese Pinyin: mugua) is a medicinal and food herb that has long been used as a folk medicine for rheumatic diseases, yet its bioactive components and therapeutic mechanisms are not clear.

AIM OF THE STUDY

Exploring anti-inflammatory and chondroprotective effects of CSP on rheumatoid arthritis (RA) and its possible targets of action.

MATERIALS AND METHODS

In this study, we performed an integrated approach of network pharmacology, molecular docking and experimental studies to explore the potential mechanism of action of CSP in the treatment of cartilage damage in RA.

RESULTS

Studies have shown that Quercetin, ent-Epicatechin and Mairin may be the main active compounds of CSP in the treatment of RA, while AKT1, VEGFA, IL-1β, IL-6, MMP9 etc. are considered as core target proteins to which the main active compounds in CSP bind, as further confirmed by molecular docking. In addition, the potential molecular mechanism of CSP for the treatment of cartilage damage in RA predicted by network pharmacology analysis was validated by in vivo experiments. CSP was found to downregulate the expression of AKT1, VEGFA, IL-1β, IL-6, MMP9, ICAM1, VCAM1, MMP3, MMP13 and TNF-α and increase the expression of COL-2 in the joint tissue of Glucose-6-Phosphate Isomerase (G6PI) model mice. Thus CSP contributes to the treatment of rheumatoid arthritis cartilage destruction.

CONCLUSION

This study showed that CSP has multi-component, multi-target and multi-pathway characteristics in treating cartilage damage in RA, which can achieve the effect of treating RA by inhibiting the expression of inflammatory factors, reducing neovascularization and alleviating the damage to cartilage caused by the diffusion of synovial vascular opacities, and reducing the degradation of cartilage by MMPs to play a protective role in RA cartilage damage. In conclusion, this study indicates that CSP is a candidate Chinese medicine for further research in treating cartilage damage in RA.

Computational Fluid Dynamics (CFD) Model for Analysing the Role of Shear Stress in Angiogenesis in Rheumatoid Arthritis

Rheumatoid arthritis (RA) is an autoimmune disease characterised by an attack on healthy cells in the joints. Blood flow and wall shear stress are crucial in angiogenesis, contributing to RA's pathogenesis. Vascular endothelial growth factor (VEGF) regulates angiogenesis, and shear stress is a surrogate for VEGF in this study. Our objective was to determine how shear stress correlates with the location of new blood vessels and RA progression. To this end, two models were developed using computational fluid dynamics (CFD). The first model added new blood vessels based on shear stress thresholds, while the second model examined the entire blood vessel network. All the geometries were based on a micrograph of RA blood vessels. New blood vessel branches formed in low shear regions (0.840-1.260 Pa). This wall-shear-stress overlap region at the junctions was evident in all the models. The results were verified quantitatively and qualitatively. Our findings point to a relationship between the development of new blood vessels in RA, the magnitude of wall shear stress and the expression of VEGF.

An innovative immunotherapeutic strategy for rheumatoid arthritis: Selectively suppressing angiogenesis and osteoclast differentiation by fully human antibody targeting thymocyte antigen-1

Thymocyte antigen-1 (THY-1)is a potential target for rheumatoid arthritis (RA) treatment, and THY-1 positive fibroblast-like synoviocytes (FLS) are enriched in the synovium of RA patients and participate in angiogenesis to accelerate RA progression. In this study, we screened an antibody targeting THY-1 (THY-1 Ab) and explored its mechanism in alleviating RA progression. THY-1 Ab was screened from ScFv phage antibody library by phage display technology (PDT). THY-1 Ab-treated collagen induced arthritis (CIA) mice had lower degree of arthritis scores. We explore the mechanism of THY-1 Ab in alleviating RA progression. THY-1 Ab can remarkably inhibit the secretion of pro-inflammatory factors and promote the secretion of anti-inflammatory factors. Further experiments showed that THY1 Ab downregulated the expression of JUNB by the hsa_circ_0094342/miRNA-155-5P/SPI1 axis, inhibited RA angiogenesis and osteoclast differentiation, and relieved RA progression. These findings support that THY-1 Ab is a promising therapeutic antibody for RA treatment.

Activation of angiotensin II type 2 receptor attenuates lung injury of collagen-induced arthritis by alleviating endothelial cell injury and promoting Ly6Clo monocyte transition

As one of the most frequent extra-articular manifestations of rheumatoid arthritis (RA), interstitial lung disease (ILD) is still challenging due to unrevealed pathophysiological mechanism. To address this question, in the present study, we used the classical collagen-induced arthritis (CIA) mouse model to determine the related-immune mechanism of lung injury and possible pharmacological treatment for RA-ILD. At the peak of arthritis, we found CIA mice developed apparent lung injury, characterized by interstitial thickening, inflammatory cell infiltration, and lymphocyte follicle formation. Additionally, the endothelial injury occurred as the number of endothelial cells (ECs) and their CD31 expression decreased. Along with those, monocytes, predominantly Ly6C^hi monocytes with pro-inflammatory phenotype, were also increased. While in the remission period of arthritis, ECs gradually increased with retrieved CD31 expression, leading to decreased infiltrating monocytes, but boosted Ly6C^lo population. Ly6C^lo monocytes were prone to locate around damaged ECs, promoted ECs proliferation and vascular tube formation, and lessened the expression of adhesion molecules. In addition, we evaluated angiotensin II type 2 receptor (Agtr2), which has been demonstrated to be protective against lung injury, could be beneficial in RA-ILD. We found elevated Agtr2 in CIA lung tissue, and activation of Agtr2, within its specific agonist C21, alleviated the pulmonary inflammation in vivo, reduced ECs injury, and promoted monocytes conversion from Ly6C^hi to Ly6C^lo monocytes in vitro. Our data reveal a potential pathological mechanism of RA-ILD that involves ECs damage and inflammatory monocytes infiltration and provide a potential drug target, Agtr2, for RA-ILD treatment.

Macrophage: Key player in the pathogenesis of autoimmune diseases

The macrophage is an essential part of the innate immune system and also serves as the bridge between innate immunity and adaptive immune response. As the initiator and executor of the adaptive immune response, macrophage plays an important role in various physiological processes such as immune tolerance, fibrosis, inflammatory response, angiogenesis and phagocytosis of apoptotic cells. Consequently, macrophage dysfunction is a vital cause of the occurrence and development of autoimmune diseases. In this review, we mainly discuss the functions of macrophages in autoimmune diseases, especially in systemic lupus erythematosus (SLE), rheumatic arthritis (RA), systemic sclerosis (SSc) and type 1 diabetes (T1D), providing references for the treatment and prevention of autoimmune diseases.

A chinese medicine formula (kunbixiao granule) for female rheumatoid arthritis: Study protocol for a double-blind, randomized, placebo-controlled trial

Introduction: Rheumatoid arthritis (RA) is a chronic autoimmune disease affecting females more than males. Clinical symptoms, disease activity and comorbidities are more severe in females. Moreover, the choice of treatment for females is limited during childbearing age due to the side effects of current drugs. Therefore, developing novel and safer drugs for females is urgently needed. Kunbixiao granules (KBXG), a Chinese medicine formula, has been applied to treat female RA patients in our center as a complementary therapy. However, there is insufficient evidence for its effect. Therefore, we aim to conduct a randomized, controlled, double-blind clinical trial to confirm the efficacy and safety of KBXG for the treatment of female RA.

Methods: This study is a single-center, double-blind, randomized, parallel group, placebo-controlled clinical trial. A total of 90 female RA patients with Disease Activity Score for 28 joints (DAS28) > 3.2 will be enrolled. They will be randomly assigned to receive either KBXG or placebo for 12 weeks. The change in DAS28 based on C-reactive protein (DAS28-CRP) and the Clinical Disease Activity Index (CDAI) are the primary outcomes. The secondary outcomes include a rate of achieving 20%, 50% and 70% improvement in the American College Rheumatology criteria (ACR20, ACR50, ACR70), TCM syndrome score, visual analogue scale (VAS), average hands grip strength, the consumption of concomitant medication, Hospital Anxiety and Depression Scale (HADS), lumbar spine bone mineral density (L-BMD) and 7-joint ultrasound score (US7). Any adverse events will also be recorded.

Discussion: This trial will provide evidence of KBXG in reducing disease activity, and improving clinical symptoms and quality of life of female RA patients. The long-term effects of KBXG on female RA patients still needs a further follow-up.

Gender differences and pharmacological regulation of angiogenesis induced by synovial fluids in inflammatory arthritis

Several mediators including cytokines, growth factors and metalloproteinases (MMP) modulate pathological angiogenesis associated with inflammatory arthritis. The biological factors underlying sex disparities in the incidence and severity of rheumatic musculoskeletal diseases are only partially understood. We hypothesized that synovial fluids (SFs) from rheumatoid arthritis (RA) and psoriatic arthritis (PsA) patients would impact on endothelial biology in a sexually dimorphic fashion. Immune cell counts and levels of pro-angiogenic cytokines found in SFs from RA and PsA patients (n = 17) were higher than in osteoarthritis patients (n = 6). Synovial VEGF concentration was significantly higher in male than in female RA patients. Zymography revealed that SFs comprised solely MMP-9 and MMP-2, with significantly higher MMP-9 levels in male than female RA patients. Using in vitro approaches that mimic the major steps of the angiogenic process, SFs from RA and PsA patients induced endothelial migration and formation of capillary-like structures compared to control. Notably, endothelial cells from female donors displayed enhanced angiogenic response to SFs with respect to males. Treatment with the established anti-angiogenic agent digitoxin prevented activation of focal adhesion kinase and SF-induced in vitro angiogenesis. Thus, despite higher synovial VEGF and MMP-9 levels in male patients, the responsiveness of vascular endothelium to SF priming was higher in females, suggesting that gender differences in angiogenic responses were mainly related to the endothelial genotype. These findings may have implications for pathogenesis and targeted therapies of inflammatory arthritis.

A Three-Dimensional Co-Culture Model for Rheumatoid Arthritis Pannus Tissue

Three-dimensional (3D) co-culture models have closer physiological cell composition and behavior than traditional 2D culture. They exhibit pharmacological effects like in vivo responses, and therefore serve as a high-throughput drug screening model to evaluate drug efficacy and safety in vitro. In this study, we created a 3D co-culture environment to mimic pathological characteristics of rheumatoid arthritis (RA) pannus tissue. 3D scaffold was constructed by bioprinting technology with synovial fibroblasts (MH7A), vascular endothelial cells (EA.hy 926) and gelatin/alginate hydrogels. Cell viability was observed during 7-day culture and the proliferation rate of co-culture cells showed a stable increase stage. Cell-cell interactions were evaluated in the 3D printed scaffold and we found that spheroid size increased with time. TNF-α stimulated MH7A and EA.hy 926 in 3D pannus model showed higher vascular endothelial growth factor (VEGF) and angiopoietin (ANG) protein expression over time. For drug validation, methotrexate (MTX) was used to examine inhibition effects of angiogenesis in 3D pannus co-culture model. In conclusion, this 3D co-culture pannus model with biological characteristics may help the development of anti-RA drug research.

Ezrin regulates synovial angiogenesis in rheumatoid arthritis through YAP and Akt signalling

This study aimed to investigate the role and regulatory mechanisms of Ezrin in synovial vessels in rheumatoid arthritis (RA). Synovial tissues were obtained from people with osteoarthritis people and patients with RA patients. We also used an antigen-induced arthritis (AIA) mice model by using Freund's adjuvant injections. Ezrin expression was analysed by immunofluorescence and immunohistochemical staining in synovial vessels of patients with RA and AIA mice. We investigated the role of Ezrin on vascular endothelial cells and its regulatory mechanism in vivo and in vitro by adenoviral transfection technology. Our results suggest a role for the Ezrin protein in proliferation, migration and angiogenesis of vascular endothelial cells in RA. We also demonstrate that Ezrin plays an important role in vascular endothelial cell migration and tube formation through regulation of the Hippo-yes-associated protein 1 (YAP) pathway. YAP, as a key protein, can further regulate the activity of PI3K/Akt signalling pathway in vascular endothelial cells. In AIA mice experiments, we observed that the inhibition of Ezrin or of its downstream YAP pathway can affect synovial angiogenesis and may lead to progression of RA. In conclusion, Ezrin plays an important role in angiogenesis in the RA synovium by regulating YAP nuclear translocation and interacting with the PI3K/Akt signalling pathway.

CP-25 exerts anti-angiogenic effects on a rat model of adjuvant-induced arthritis by promoting GRK2-induced downregulation of CXCR4-ERK1/2 signaling in endothelial cells

Angiogenesis can produce an invasive and destructive front, also named a pannus, comprised of inflammatory vascular tissue that covers and erodes articular cartilage, subchondral bone and peri‑articular soft tissues in rheumatoid arthritis (RA). Paeoniflorin‑6'‑O‑benzene sulfonate (CP‑25) is a novel ester derivative of paeoniflorin. We previously demonstrated that CP‑25 exerts anti‑inflammatory and immunoregulatory effects. CP‑25 also exhibits a marked therapeutic effect on adjuvant‑induced arthritis (AA), and is able to inhibit synovial and immune cell function, according to our previous study. However, the effect of CP‑25 on angiogenesis remains unclear. In the present study, AA was initiated in Sprague‑Dawley rats via intradermal immunization in the right hind metatarsal footpad with heat‑killed Mycobacterium butyricum in liquid paraffin, and rats were divided into four groups: Normal, AA rat model, CP‑25 (50 mg/kg) and methotrexate (0.5 mg/kg) groups (n=10 rats/group). Subsequently, joint synovium in AA rats was pathologically evaluated by hematoxylin and eosin staining, synovial vascular proliferation was evaluated by immunofluorescence, the synovial expression levels of C‑X‑C motif chemokine ligand 12 (CXCL12) were detected by immunohistochemistry and ELISA, and synovial C‑X‑C chemokine receptor type 4 (CXCR4) was detected by western blotting. The results demonstrated that CP‑25 ameliorated clinical signs and pannus formation in the ankle joint in rats with AA. Furthermore, there was a positive correlation between pannus score and CXCL12 and CXCR4 expression. In addition, the effects of CP‑25 on endothelial cell function and CXCL12/CXCR4 signaling were studied in vitro using human umbilical vein endothelial cells (HUVECs). The results demonstrated that CXCL12 significantly promoted HUVEC proliferation, migration and tube formation, and that CP‑25 could reverse these abnormalities by inhibiting plasma membrane localization of G protein‑coupled receptor kinase 2 (GRK2) in HUVECs. These findings suggested that CP‑25 may markedly inhibit pannus formation in AA. This effect may be associated with a reduction in the plasma membrane localization of GRK2 in endothelial cells, an enhancement of the inhibitory effect of GRK2 on ERK1/2 in the cytoplasm, a reduction in the phosphorylation of ERK1/2 and in the function of HUVECs.

Effects of human cyclooxygenase-2 gene silencing on synovial cells of rheumatoid arthritis mediated by lentivirus

The aim of the study is to screen the effective shRNA sequence which can silence the human COX-2 expression level in synovial cells of rheumatoid arthritis (RA) patient transfected by the lentivirus. Four pairs of hCOX-2 shRNA were designed and inserted into lentivirus to form pGPHI/GFP/Neo-shRNA vector. The reconstructed virus was transfected into synovial cells derived from RA patients, and then the expression level of hCOX-2 mRNA and the protein of the inflammatory factors including prostaglandin E2 (PGE2), vascular endothelial growth factor (VEGF), interleukin-1β (IL-1β) and tumour necrosis factor alpha (TNF-α) in the supernatants were examined with real-time PCR and ELISA, respectively. There was no obvious negative influence on cell growth and morphology after hCOX-2 shRNA gene transfection mediated by lentivirus. The hCOX-2 mRNA expression level, as well as the concentration of PGE2, VEGF, IL-1β and TNF-α, decreased significantly (p < .05). RNAi mediated by lentivirus can significantly inhibit hCOX-2 mRNA expression level in synovial cells of RA patients, so as to reduce the expression of inflammatory cytokines.

The Effect of Puerarin on Carotid Intima-media Thickness in Patients With Active Rheumatoid Arthritis: ARandomized Controlled Trial

PURPOSE

Cardiovascular and diabetic complications are the main causes of death in patients with rheumatoid arthritis (RA). Puerarin has potential protective effects against subclinical atherosclerosis and insulin resistance, but the clinical evidence is still not sufficient to draw definitive conclusions. Therefore, we performed the clinical trial to assess the effect of puerarin on carotid intima-media thickness (CIMT) in RA.

METHODS

This is an open, controlled, randomized, and parallel-group comparison study of 119 patients with a definite diagnose of active RA. All 119 consecutive patients with RA receiving routine antirheumatic care were randomized to receive treatment with (n = 60; 16 males and 44 females; mean age, 52.97 years; 95% CI, 49.78-56.15 years) or without (n = 59; 17 males and 42 females; mean age, 54.05 years; 95% CI, 50.03-58.07 years) 400mg of puerarin. The effects of both interventions on CIMT, homeostasis model assessment of insulin resistance (HOMA-IR) value, and possible adverse events were assessed and compared at entry, 12 weeks, and 24 weeks. The collected data were processed and assessed using ANCOVA, paired t test, repeated-measure ANOVA, one-way ANOVA, Pearson's χ² test, Fisher exact test, Kaplan-Meier survival analysis, Pearson correlation, and LOESS (locally weighted smoothing) regression analysis.

FINDINGS

No significant adverse effects occurred concerning the use of puerarin, and both interventions were generally well tolerated in all the patients. A tiny but significant decrease of CIMT was observed in puerarin-treated patients at 24 weeks (-0.003 mm; 95% CI, -0.005 to -0.001vs 0.019 mm; 95% CI, -0.002 to 0.040; P < 0.001). At 24 weeks, insulin resistance was indicated with more pronounced improvement in the puerarin group versus the control group (homeostasis model assessment, -0.40; 95% CI, -0.47 to -0.33vs -0.05; 95% CI, -0.08 to -0.01; P < 0.001). Correlation analysis indicated an interaction between the parallel reductions in CIMT and insulin resistance in the puerarin group (r = 0.878, P < 0.001) but not in the control group.

IMPLICATIONS

In the study, 24 weeks of treatment with 400mg of puerarin exerted a significant effect against CIMT progression in patients with active RA, which may be associated with the improvement of insulin resistance. Puerarin holds promise as a drug candidate for the prevention and treatment of cardiometabolic comorbidities in patients with active RA. However, more strictly designed trials, such as double-blind and placebo-controlled trials, are still required. ClinicalTrials.gov identifier: NCT02254655.

Linking systemic angiogenic markers to synovial vascularization in rheumatoid arthritis

Background

Neoangiogenesis is a crucial event to promote the development of the hyperplasic proliferative pathologic synovium in Rheumatoid arthritis (RA). Ultrasound (US) is sensitive for detection of power Doppler (PD) vascularization.

Objective

To explore the associations between a set of complementary circulating angiogenic markers and a comprehensive US assessment in patients with RA.

Patients and methods

Serum levels of eight angiogenic markers were measured by quantitative ELISAs in a total of 125 patients with RA, who were all systematically assessed in parallel by PDUS, performed on 32 joints.

Results

Serum levels of soluble Vascular Cell Adhesion Molecule-1 (sVCAM-1) and Tie-2 were more likely to be increased in patients with synovial hyperemia detected on at least one joint (Power Doppler grade ≥1). sVCAM-1, Tie-2 and Angiostatin concentrations gradually increased together with the grade of the semiquantitative PDUS scale and concentrations of these three markers were markedly increased in patients with moderate to marked hyperemia (Power Doppler grade 2 and 3). Levels of sVCAM-1, Tie-2, and Angiostatin correlated with a global arthritis sum score, defined by the sum of the semiquantitative PDUS scores for all joints examined. Levels of Tie-2 and Placenta Growth Factor (PlGF) were associated with PDUS features indicating residual disease activity.

Conclusion

Our results support the relevance of measuring serum levels of vascular markers to evaluate the intensity and extent of synovial vascularization. Angiogenic markers, and particularly Tie-2, could be a valuable surrogate of active synovitis and their place in relation to PDUS in clinical practice deserve further investigation.

The efficacy and safety of the herbal medicine geonchildan for patients with active rheumatoid arthritis: study protocol for a randomized, double-blind, placebo-controlled, parallel pilot trial

Background

This study aims to assess the efficacy and safety of geonchildan, a Korean traditional herbal medicine, for patients with active rheumatoid arthritis (RA) and evaluate the feasibility of a large-scale confirmatory clinical trial.

Methods/design

This is a randomized, double-blind, placebo-controlled, parallel two-arm pilot trial in Seoul, Korea. Altogether, 30 patients diagnosed with RA for at least 3 months and with a Disease Activity Score for 28 joints (DAS28) ≥ 3.2 will be enrolled. Participants are randomly assigned to one of two groups, the experimental group or the placebo group, in a 1:1 ratio and will make four scheduled visits. The participants will be administered geonchildan or a placebo three times per day for 12 weeks. The change in DAS28 will be examined as the primary efficacy outcome. The secondary efficacy outcomes include the proportion of patients achieving ACR20, ACR50, ACR70, and EULAR responses; the DAS28 sub-items; the consumption of medication; Korean Health Assessment Questionnaire scores; inflammatory parameters; and the Korean medical diagnostic pattern indicator. Adverse events and laboratory test results will be recorded to evaluate safety. The process, resources used, and management of the study will also be assessed to determine the feasibility of a large-scale trial.

Discussion

This is the first clinical trial to explore the efficacy and safety of geonchildan in patients with active RA. If the superiority of geonchildan versus the placebo is demonstrated and the study design is feasible, this study could form the foundation for a large-scale clinical trial. The results will be published in a peer-reviewed journal.

Trial registration

Clinical Research Information Service, KCT0001943. Registered on 14 June 2016.

Electronic supplementary material

The online version of this article (10.1186/s13063-018-2849-3) contains supplementary material, which is available to authorized users.

GATA4 regulates angiogenesis and persistence of inflammation in rheumatoid arthritis

Rheumatoid arthritis (RA) is a chronic autoimmune disease characterized by abnormal inflammation, angiogenesis, and cartilage destruction. In RA, neoangiogenesis is an early and crucial event to promote the formation of pannus, causing further inflammatory cell infiltration. The transcription factor GATA4 is a critical regulator of cardiac differentiation-specific gene expression. We find that a higher level of GATA4 exists in synovium of rheumatoid arthritis (RA) patients, but the function of GATA4 in RA remains unclear. In the present study, IL-1β induces inflammation in fibroblast-like synoviocytes (FLS) MH7A, which is accompanied with the increased expression of GATA4 and VEGF production. Through application of GATA4 loss-of-function assays, we confirm the requirement of GATA4 expression for inflammation induced by IL-1β in FLS. In addition, we demonstrate for the first time that GATA4 plays key roles in regulating VEGF secretion from RA FLS to promote cellular proliferation, induce cell migration, and angiogenic tube formation of endothelial cells. GATA4 induces the angiogenic factors VEGFA and VEGFC, by directly binding to the promoter and enhancing transcription. The knockdown of GATA4 attenuates the development of collagen-induced arthritis (CIA) and prevents RA-augmented angiogenesis in vivo, which are accompanied with decreased VEGF level. These results reveal a previously unrecognized function for GATA4 as a regulator of RA angiogenesis and we provide experimental data validating the therapeutic target of GATA4 in RA mice.

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.

Arthritis models: usefulness and interpretation

Animal models of arthritis are used to better understand pathophysiology of a disease or to seek potential therapeutic targets or strategies. Focusing on models currently used for studying rheumatoid arthritis, we show here in which extent models were invaluable to enlighten different mechanisms such as the role of innate immunity, T and B cells, vessels, or microbiota. Moreover, models were the starting point of in vivo application of cytokine-blocking strategies such as anti-TNF or anti-IL-6 treatments. The most popular models are the different types of collagen-induced arthritis and arthritis in KBN mice. As spontaneous arthritides, human TNF-α transgenic mice are a reliable model. It is mandatory to use animal models in the respect of ethical procedure, particularly regarding the number of animals and the control of pain. Moreover, design of experiments should be of the highest level, animal models of arthritis being dedicated to exploration of well-based novelties, and never used for confirmation or replication of already proven concepts. The best interpretations of data in animal models of arthritis suppose integrated research, including translational studies from animals to humans.

Anti-angiogenic effect of total saponins of Rhizoma Dioscorea nipponica on collagen induced-arthritis in rats

Rheumatoid arthritis (RA) is a common chronic autoimmune and incurable disease. The aim of the present study was to investigate the therapeutic effect and mechanism of the total saponins of Rhizoma Dioscorea nipponica (TSRDN) in RA. A collagen induced-arthritis (CIA) rat model was established. CIA rats were randomly divided into three groups and lavaged with an equal volume of solvent (CIA group), TSRDN (25 mg/kg/day, RDN group) and tripterygium (TP; 12 mg/kg/day, TP group) for 21 days, respectively. Normal rats served as a control group. Hematoxylin-eosin (HE) staining was used to observe the histopathological injury of synovial tissues. The level of CD31, which used for marking and counting, micro vessel density (MVD) and the expression levels of vascular endothelial growth factor (VEGF) and signal transducer and activator of transcription 3 (STAT3) were detected by immunohistochemical analysis. Additionally, the DNA-binding activity of nuclear factor-κB (NF-κB) was determined using an ELISA kit. HE staining showed obvious synovial hyperplasia, inflammatory cell infiltration, pannus formation, cartilage and bone erosion in the CIA group rats. In addition, compared with control group, the level of MVD, the expression of VEGF and STAT3, and the DNA-binding activity of NF-κB were all increased in CIA group rat synovial tissue (all P<0.01); however, TSRDN or tripterygium were able to inhibit these changes (all P<0.01). It was speculated that TSRDN may prevent angiogenesis by inhibiting the expression of STAT3 and the DNA-binding activity of NF-κB p65, thereby potentially improving CIA.

Identification of novel mutations in CD2BP1 gene in clinically proven rheumatoid arthritis patients of south India

Pyogenic Arthritis, Pyoderma gangrenosum, and Acne (PAPA syndrome) is a rare autosomal dominant, auto-inflammatory disease that affects joints and skin. The disease results due to mutations in the cluster of differentiation 2 binding protein 1 (CD2BP1) gene on chromosome 15q24.3. Rheumatoid arthritis (RA) is a common, genetically complex disease that affects the joints with occasional skin manifestations. Studies related to the pathophysiology of inflammation in these two disorders show a certain degree of overlap at genetic level. The present study was done to confirm the existence of such a genetic overlap between PAPA syndrome and RA in south Indian population. In the present study 100 patients who were clinically diagnosed rheumatoid arthritis and 100 apparently healthy controls were chosen and the 15 exons of CD2BP1 gene were PCR-amplified and sequenced. The sequence analysis showed that in exon 3 thirty eight patients revealed presence of novel heterozygous missense mutations p.Glu51Asp, p.Leu57Arg and p.Ala64Thr. In exons 6, 10 and 14 eight patients showed 44 novel missense mutations and two patients showed novel frame shift mutations p.(Met123_Leu416delinsThr) and p.(Thr337Profs*52) leading to truncated protein formation. Such mutations were not seen in controls. Further, the in silico analysis revealed the mutant CD2BP1 structure showed deletion of Cdc15 and SH3 domains when superimposed with the wild type CD2BP1 structure with variable RMSD values. Therefore, these structural variations in CD2BP1 gene due to the mutations could be one of the strongest reasons to demonstrate the involvement of these gene variations in the patients with rheumatoid arthritis.

Novel Immunotherapeutic Avenues for Rheumatoid Arthritis

Rheumatoid arthritis (RA) is the most common inflammatory rheumatic disease. It leads to irreversible joint damage, physical handicap, and reduced life expectancy. The past two decades have seen considerable therapeutic advances with the development of biologic treatments to block proinflammatory cytokines or modulate lymphocyte function, followed by the development of small molecules to target intracellular signaling. Nevertheless, only a minority of patients can achieve disease remission, especially long term, warranting further investigation into newer therapeutic options. Targeting single proinflammatory pathways may not be sufficient, as suggested by variable results with T helper (Th)-17-related cytokine blockade. Multilevel information from 'omics' techniques along with data from mechanistic studies might facilitate the identification of pivotal checkpoints in RA disease pathogenesis and the subsequent development of new effective treatments.

VEGF Gene Polymorphisms Affect Serum Protein Levels and Alter Disease Activity and Synovial Lesions in Rheumatoid Arthritis

Background

Our study investigated 2 common single-nucleotide polymorphisms (SNPs) of vascular endothelial growth factor (VEGF) for their influences on serum VEGF levels, disease activity, and synovial lesions in rheumatoid arthritis (RA).

Material/Methods

Clinical information and venous blood samples were collected from 98 RA patients and 100 healthy controls. Genotyping on samples from the subjects was performed using matrix-assisted laser desorption ionization time of flight mass spectrometry (MALDI-TOF MS). Serum VEGF levels were determined using the enzyme-linked immunosorbent assay (ELISA). The synovial thickness and joint effusion of 28 joints were measured in RA patients, and total sharp score (TSS) and disease activity score (DAS) of 28 joints were recorded.

Results

The genotype and allele frequencies of VEGF rs833070 (G>A) and rs3025030 (G>C) were significantly different between RA group and control group (all P<0.05). VEGF rs833070 and rs3025030 polymorphisms were associated with increasing VEGF serum levels in the RA group (all P<0.01). Statistically significant difference was observed in DAS28 between the different genotypes of VEGF rs833070 in RA patients (P<0.05). Importantly, significant differences in synovial thickening, joint effusion and synovial angiogenesis were observed between the different genotypes of VEGF rs833070 and rs3025030 polymorphisms (all P<0.05).

Conclusions

Our study provides evidence that VEGF polymorphisms might be important indicators of disease activity and synovial lesions, and prognostic factors in evaluating the treatment effectiveness in RA.

Contribution of synovial lining cells to synovial vascularization of the rat temporomandibular joint

The lining layer of the synovial membrane in the temporomandibular joint (TMJ) contains two types of lining cells: macrophage-like type A and fibroblast-like type B cells. The type B cells are particularly heterogeneous in their morphology and immunoreactivity, so that details of their functions remain unclear. Some of the type B cells exhibit certain resemblances in their ultrastructure to those of an activated capillary pericyte at the initial stage of the angiogenesis. The articular surface, composed of cartilage and the disc in the TMJ, has few vasculatures, whereas the synovial lining layer is richly equipped with blood capillaries to produce the constituent of synovial fluid. The present study investigated at both the light and electron microscopic levels the immunocytochemical characteristics of the synovial lining cells in the adult rat TMJ, focusing on their contribution to the synovial vascularization. It also employed an intravascular perfusion with Lycopersicon esculentum (tomato) lectin to identify functional vessels in vivo. Results showed that several type B cells expressed desmin, a muscle-specific intermediate filament which is known as the earliest protein to appear during myogenesis as well as being a marker for the immature capillary pericyte. These desmin-positive type B cells showed immunoreactions for vimentin and pericyte markers (neuron-glial 2; NG2 and PDGFRβ) but not for the other markers of myogenic cells (MyoD and myogenin) or a contractile apparatus (αSMA and caldesmon). Immunoreactivity for RECA-1, an endothelial marker, was observed in the macrophage-like type A cells. The arterioles and venules inside the synovial folds extended numerous capillaries with RECA-1-positive endothelial cells and desmin-positive pericytes to distribute densely in the lining layer. The distal portion of these capillaries showing RECA-1-immunoreactivity lacked lectin-staining, indicating a loss of blood-circulation due to sprouting or termination in the lining layer. The desmin-positive type B and RECA-1-positive type A cells attached to this portion of the capillaries. Some capillaries in the lining layer also expressed ninein, a marker for sprouting endothelial cells, called tip cells. Since an activated pericyte, macrophage and tip cell are known to act together at the forefront of the vessel sprout during angiogenesis, the desmin-positive type B cell and RECA-1-positive type A cell might serve as these angiogenic cells in the synovial lining layer. Tomato lectin perfusion following decalcification would be a highly useful tool for research on the vasculature of the mineralized tissue. Use of this technique combined with immunohistochemistry should permit future extensive investigations on the presence of the physiological angiogenesis and on the function of the lining cells in the synovial membrane.

Targeting VEGF-A with a vaccine decreases inflammation and joint destruction in experimental arthritis

OBJECTIVES

Inflammation and angiogenesis are two tightly linked processes in arthritis, and therapeutic targeting of pro-angiogenic factors may contribute to control joint inflammation and synovitis progression. In this work, we explored whether vaccination against vascular endothelial growth factor (VEGF) ameliorates collagen-induced arthritis (CIA).

METHODS

Anti-VEGF vaccines were heterocomplexes consisting of the entire VEGF cytokine (or a VEGF-derived peptide) linked to the carrier protein keyhole limpet hemocyanin (KLH). Two kinds of vaccines were separately tested in two independent experiments of CIA. In the first, we tested a kinoid of the murine cytokine VEGF (VEGF-K), obtained by conjugating VEGF-A to KLH. For the second, we selected two VEGF-A-derived peptide sequences to produce heterocomplexes (Vpep1-K and Vpep2-K). DBA/1 mice were immunized with either VEGF-K, Vpep1-K, or Vpep2-K, before CIA induction. Clinical and histological scores of arthritis, anti-VEGF, anti-Vpep Ab titers, and anti-VEGF Abs neutralizing capacity were determined.

RESULTS

Both VEGF-K and Vpep1-K significantly ameliorated clinical arthritis scores and reduced synovial inflammation and joint destruction at histology. VEGF-K significantly reduced synovial vascularization. None of the vaccines reduced anti-collagen Ab response in mice. Both VEGF-K and Vpep1-K induced persistently high titers of anti-VEGF Abs capable of inhibiting VEGF-A bioactivity.

CONCLUSION

Vaccination against the pro-angiogenic factor VEGF-A leads to the production of anti-VEGF polyclonal Abs and has a significant anti-inflammatory effect in CIA. Restraining Ab response to a single peptide sequence (Vpep1) with a peptide vaccine effectively protects immunized mice from joint inflammation and destruction.

Semaphorin 4D Contributes to Rheumatoid Arthritis by Inducing Inflammatory Cytokine Production: Pathogenic and Therapeutic Implications

Objective

Semaphorin 4D (Sema4D)/CD100 has pleiotropic roles in immune activation, angiogenesis, bone metabolism, and neural development. We undertook this study to investigate the role of Sema4D in rheumatoid arthritis (RA).

Methods

Soluble Sema4D (sSema4D) levels in serum and synovial fluid were analyzed by enzyme‐linked immunosorbent assay. Cell surface expression and transcripts of Sema4D were analyzed in peripheral blood cells from RA patients, and immunohistochemical staining of Sema4D was performed in RA synovium. Generation of sSema4D was evaluated in an ADAMTS‐4–treated monocytic cell line (THP‐1 cells). The efficacy of anti‐Sema4D antibody was evaluated in mice with collagen‐induced arthritis (CIA).

Results

Levels of sSema4D were elevated in both serum and synovial fluid from RA patients, and disease activity markers were correlated with serum sSema4D levels. Sema4D‐expressing cells also accumulated in RA synovium. Cell surface levels of Sema4D on CD3+ and CD14+ cells from RA patients were reduced, although levels of Sema4D transcripts were unchanged. In addition, ADAMTS‐4 cleaved cell surface Sema4D to generate sSema4D in THP‐1 cells. Soluble Sema4D induced tumor necrosis factor α (TNFα) and interleukin‐6 (IL‐6) production from CD14+ monocytes. IL‐6 and TNFα induced ADAMTS‐4 expression in synovial cells. Treatment with an anti‐Sema4D antibody suppressed arthritis and reduced proinflammatory cytokine production in CIA.

Conclusion

A positive feedback loop involving sSema4D/IL‐6 and TNFα/ADAMTS‐4 may contribute to the pathogenesis of RA. The inhibition of arthritis by anti‐Sema4D antibody suggests that Sema4D represents a potential therapeutic target for RA.

Hyaluronan regulation of endothelial barrier function in cancer

Vascular integrity or the maintenance of blood vessel continuity is a fundamental process regulated by endothelial cell-cell junctions. Defects in endothelial barrier function are an initiating factor in several disease processes including tumor angiogenesis and metastasis. The glycosaminoglycan, hyaluronan (HA), maintains vascular integrity through specific mechanisms including HA-binding protein signaling in caveolin-enriched microdomains, a subset of lipid rafts. Certain disease states, including cancer, increase enzymatic hyaluronidase activity and reactive oxygen species generation, which break down high molecular weight HA (HMW-HA) to low molecular weight fragments (LMW-HA). LMW-HA can activate specific HA-binding proteins during tumor progression to promote disruption of endothelial cell-cell contacts. In contrast, exogenous administration of HMW-HA promotes enhancement of vascular integrity. This review focuses on the roles of HA in regulating angiogenic and metastatic processes based on its size and the HA-binding proteins present. Further, potential therapeutic applications of HMW-HA in treating cancer are discussed.

Transactivation of the receptor-tyrosine kinase ephrin receptor A2 is required for the low molecular weight hyaluronan-mediated angiogenesis that is implicated in tumor progression

Angiogenesis or the formation of new blood vessels is important in the growth and metastatic potential of various cancers. Therefore, understanding the mechanism(s) by which angiogenesis occurs can have important therapeutic implications in numerous malignancies. We and others have demonstrated that low molecular weight hyaluronan (LMW-HA, ∼2500 Da) promotes endothelial cell (EC) barrier disruption and angiogenesis. However, the mechanism(s) by which this occurs is poorly defined. Our data indicate that treatment of human EC with LMW-HA induced CD44v10 association with the receptor-tyrosine kinase, EphA2, transactivation (tyrosine phosphorylation) of EphA2, and recruitment of the PDZ domain scaffolding protein, PATJ, to the cell periphery. Silencing (siRNA) CD44, EphA2, PATJ, or Dbs (RhoGEF) expression blocked LMW-HA-mediated angiogenesis (EC proliferation, migration, and tubule formation). In addition, silencing EphA2, PATJ, Src, or Dbs expression blocked LMW-HA-mediated RhoA activation. To translate our in vitro findings, we utilized a novel anginex/liposomal targeting of murine angiogenic endothelium with either CD44 or EphA2 siRNA and observed inhibition of LMW-HA-induced angiogenesis in implanted Matrigel plugs. Taken together, these results indicate LMW-HA-mediated transactivation of EphA2 is required for PATJ and Dbs membrane recruitment and subsequent RhoA activation required for angiogenesis. These results suggest that targeting downstream effectors of LMW-HA could be a useful therapeutic intervention for angiogenesis-associated diseases including tumor progression.

Potential benefits of green tea polyphenol EGCG in the prevention and treatment of vascular inflammation in rheumatoid arthritis

Rheumatoid arthritis (RA) is a chronic inflammatory disease of the joints in which systemic overproduction of pro-inflammatory cytokines such as interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α) may accelerate cardiovascular (CV) complications. Synovial inflammation in RA spreads systemically and transforms silently into chronic inflammation manifested by increased cytokine release and abnormally high levels of acute reactive proteins (ARPs) such as C-reactive protein (CRP), suggesting inflammation as a connecting link between RA and CV dysfunction. While the treatment to improve CV function in RA patients is being validated, it is timely to propose and test two-pronged therapies that ameliorate arthritis concomitant to improving CV functions. In this review, we summarized the pre-clinical and clinical studies validating the cardiovascular and anti-rheumatic activities of epigallocatechin-3 gallate (EGCG), a potent anti-inflammatory molecule found in green tea. The review also draws many parallels that have emerged between the paradigm of cytokine-driven inflammation in the pathogenesis of RA and its CV complications. Finally, based on extensive clinical evidence of the 'synovial inflammation-systemic inflammation' link and the benefits of EGCG in regulating these two pathologies via common driving factors, authors put forward an argument that EGCG may be tested for its potential CV benefit along with anti-rheumatic activity in animal models of human RA.

Reduced heart rate and cardiac output differentially affect angiogenesis, growth, and development in early chicken embryos (Gallus domesticus)

An increase in both vascular circumferential tension and shear stress in the developing vasculature of the chicken embryo has been hypothesized to stimulate angiogenesis in the developing peripheral circulation chorioallantoic membrane (CAM). To test this hypothesis, angiogenesis in the CAM, development, and growth were measured in the early chicken embryo, following acute and chronic topical application of the purely bradycardic drug ZD7288. At hour 56, ZD7288 reduced heart rate (f(H)) by ~30% but had no significant effect on stroke volume (~0.19 ± 0.2 μL), collectively resulting in a significant fall in cardiac output (CO) from ~27 ± 3 to 18 ± 2 μL min(-1). Mean f(H) at 72 h of development was similarly significantly lowered by acute ZD7288 treatment (250 μM) to 128 ± 0.3 beats min(-1), compared with 174.5 ± 0.3 and 174.7 ± 0.8 beats min(-1) in control and Pannett-Compton (P-C) saline-treated embryos, respectively. Chronic dosing with ZD7288-and the attendant decreases in f(H) and CO-did not change eye diameter or cervical flexion (key indicators of development rate) at 120 h but significantly reduced overall growth (wet and dry body mass decreased by 20%). CAM vessel density index (reflecting angiogenesis) measured 200-400 μm from the umbilical stalk was not altered, but ZD7288 reduced vessel numbers-and therefore vessel density-by 13%-16% more distally (500-600 μm from umbilical stalk) in the CAM. In the ZD7288-treated embryos, a decrease in vessel length was found within the second branch order (~300-400 μm from the umbilical stock), while a decrease in vessel diameter was found closer to the umbilical stock, beginning in the first branch order (~200-300 μm). Paradoxically, chronic application of P-C saline also reduced peripheral CAM vessel density index at 500 and 600 μm by 13% and 7%, respectively, likely from washout of local angiogenic factors. In summary, decreased f(H) with reduced CO did not slow development rate but reduced embryonic growth rate and angiogenesis in the CAM periphery. This study demonstrates for the first time that different processes in the ontogeny of the early vertebrate embryo (i.e., hypertrophic growth vs. development) have differential sensitivities to altered convective blood flow.

Epidermal growth factor receptor (EGFR) as a therapeutic target in rheumatoid arthritis

The epidermal growth factor receptor (EGFR) has an important role in the hyperplastic growth of tumor. Similar to tumor growth, rheumatoid arthritis (RA) synovium is hyperplastic, invasive, and expresses EGFR and its ligands. Activation of EGFR signaling is responsible for synovial fibroblast proliferation in RA. Furthermore, in addition to its role in proliferation, EGFR and its ligands can induce cytokine production of synovial fibroblasts during the pathogenesis of RA. Agents that target EGFR have yielded promising results in animal experiments involving RA, pharmacologic modulations targeting EGFR, or its ligands may give rise to new therapeutic approaches for RA. In this review article, we will discuss the biological features of EGFR and summarize recent advances regarding the role of EGFR in the pathogenesis and treatment of RA.

Linking systemic angiogenic factors (VEGF, angiogenin, TIMP-2) and Doppler ultrasound to anti-inflammatory treatment in rheumatoid arthritis

OBJECTIVE

To evaluate an association between synovial Doppler flow and serum levels of vascular endothelial growth factor (VEGF), angiogenin and TIMP-2 in patients with rheumatoid arthritis during anti-inflammatory treatment with glucocorticoids and TNF-α inhibitors.

METHODS

Inflamed wrists of 15 patients with rheumatoid arthritis (RA) were examined by two independent ultrasound investigators prior to and at days 3, 7, 14 and 42 after the initiation of treatment with glucocorticoids in therapy-naïve patients or after the beginning of a therapy with a TNF-α inhibitor in patients with DMARD failure. Quantitative three-dimensional power Doppler ultrasonographic assessment of synovial vascularization was compared at each visit with serum levels of VEGF, angiogenin and TIMP-2.

RESULTS

In the glucocorticoid group, synovial Doppler signals decreased significantly at day 3 (-44%; P=0.003) in comparison to a delayed decrease in the TNF-α inhibitor group after 6 weeks (-46%; P=0.001). A significant reduction of serum VEGF levels could be determined with a delay of 1 week after the decrease of Doppler activity but no correlation was found between both parameters (rho: P=0.7; r=-0.03). Angiogenin concentrations decreased in the TNF group and increased in the GC group. Levels of TIMP-2 did not change significantly in both groups.

CONCLUSION

The decrease of serum VEGF levels under treatment with glucocorticoids or TNF-α inhibitors followed the reduction of the intra-articular synovial Doppler flow. This result supports the idea that the reduction of synovial perfusion due to anti-inflammatory treatment is not regulated by systemic VEGF, but that the inflamed joints are the source for circulating VEGF.

Norisoboldine, an alkaloid compound isolated from Radix Linderae, inhibits synovial angiogenesis in adjuvant-induced arthritis rats by moderating Notch1 pathway-related endothelial tip cell phenotype

Synovial angiogenesis is well recognized as participating in the pathogenesis of rheumatoid arthritis (RA) and has been regarded as a potential target for RA therapy. Previously, we have shown that norisoboldine (NOR) can protect joints from destruction in mice with collagen II-induced arthritis (CIA). Here, we investigate the effect of NOR on synovial angiogenesis in adjuvant-induced arthritis (AA) rats, and clarify the mechanisms in vitro. NOR, administered orally, significantly reduced the number of blood vessels and expression of growth factors in the synovium of AA rats. In vitro, it markedly prevented the migration and sprouting of endothelial cells. Notably, the endothelial tip cell phenotype, which is essential for the migration of endothelial cells and subsequent angiogenesis, was significantly inhibited by NOR. This inhibitory effect was attenuated by pretreatment with N-{N-[2-(3,5-difluorophenyl) acetyl]-(S)-alanyl}-(S)-phenylglycine tert-butyl ester, a Notch1 inhibitor, suggesting that the action of NOR was related to the Notch1 pathway. A molecular docking study further confirmed that NOR was able to promote Notch1 activation by binding the Notch1 transcription complex. In conclusion, NOR was able to prevent synovial angiogenesis in AA rats, which is a putatively new mechanism responsible for its anti-rheumatoid effect. The anti-angiogenesis action of NOR was likely achieved by moderating the Notch1 pathway-related endothelial tip cell phenotype with a potential action target of the Notch1 transcription complex.