Role of adhesion molecules in synovial inflammation

Identification of FOXO1 as a geroprotector in human synovium through single-nucleus transcriptomic profiling

The synovium, a thin layer of tissue that is adjacent to the joints and secretes synovial fluid, undergoes changes in aging that contribute to intense shoulder pain and other joint diseases. However, the mechanism underlying human synovial aging remains poorly characterized. Here, we generated a comprehensive transcriptomic profile of synovial cells present in the subacromial synovium from young and aged individuals. By delineating aging-related transcriptomic changes across different cell types and their associated regulatory networks, we identified two subsets of mesenchymal stromal cells (MSCs) in human synovium, which are lining and sublining MSCs, and found that angiogenesis and fibrosis-associated genes were upregulated whereas genes associated with cell adhesion and cartilage development were downregulated in aged MSCs. Moreover, the specific cell-cell communications in aged synovium mirrors that of aging-related inflammation and tissue remodeling, including vascular hyperplasia and tissue fibrosis. In particular, we identified forkhead box O1 (FOXO1) as one of the major regulons for aging differentially expressed genes (DEGs) in synovial MSCs, and validated its downregulation in both lining and sublining MSC populations of the aged synovium. In human FOXO1-depleted MSCs derived from human embryonic stem cells, we recapitulated the senescent phenotype observed in the subacromial synovium of aged donors. These data indicate an important role of FOXO1 in the regulation of human synovial aging. Overall, our study improves our understanding of synovial aging during joint degeneration, thereby informing the development of novel intervention strategies aimed at rejuvenating the aged joint.

ITGA2 protein is associated with rheumatoid arthritis in Chinese and affects cellular function of T cells

BACKGROUND

We identified proteins significant for rheumatoid arthritis (RA) in peripheral blood mononuclear cells (PBMCs), and to clarify mechanisms mediated by underlying proteins that may involve in the pathogenesis of RA.

METHODS

Proteome-wide protein expressions were profiled by employing label-free quantitative proteomics methodology (Easy-nLC1000 and Q-exactive). The t-test was applied to identify differentially expressed proteins (DEP, p ≤ 0.05) between RA case and control samples. Gene Ontology enrichment analyses and Protein-Protein Interaction analyses were performed to annotate functions of DEPs. The selected DEP was validated in independent samples using Simple Western assay. Plasma protein level of α2 component of integrin (ITGA2) was measured by using ELISA. The DEP, ITGA2, was assessed for its effects on T cell proliferation, cell cycle, apoptosis, and inflammatory cytokine expression.

RESULTS

Sixty-four DEPs (p < 0.05) were identified in PBMCs. The selected ITGA2 (Fold Change, FC = 2.20, p = 1.49E-02) was validated to be up-regulated (FC = 12.33, p = 4.90E-2) with RA, and plasma ITGA2 protein level significantly elevated in RA patients vs. controls. Over-expression of ITGA2 could promote proliferation and inhibit apoptosis of Jurkat T cell, and induce IL-8, IFN-γ and TNF-α expression in Jurkat T cells.

CONCLUSIONS

ITGA2 protein was significantly over-expressed in PBMCs in RA patients, and affects T cell growth and pro-inflammatory cytokine expression in T cells.

Functional disability is related to serum chemerin levels in rheumatoid arthritis

Adipokines, especially chemerin, can interact with cytokines and other molecules in inflammation. To date, there is insufficient information regarding a possible correlation between functional disability and chemerin and other pro-inflammatory molecules in rheumatoid arthritis (RA). To identify the association of functional disability with serum chemerin and other pro-inflammatory molecules, including other adipokines, cytokines and E-selectin, in patients with RA. Cross-sectional study. Assessment: disease activity (DAS28-ESR) and functional disability (HAQ-DI). We compared the adipokines (chemerin, leptin, adiponectin, resistin, and visfatin), cytokines (TNF-α, IL-6, IL-1β, and IL-18) and E-selectin levels between RA with functional disability and RA non-disabled patients. Of 82 patients with RA, 43 (52%) had functional disability. The RA with functional disability group had higher chemerin (140 vs. 112 ng/mL, p = 0.007) than the non-disabled RA group. Chemerin correlated with the HAQ-DI (rho = 0.27, p = 0.02) and DAS28-ESR (rho = 0.21, p = 0.05). Severe activity correlated with IL-6 (rho = 0.33, p = 0.003) and E-selectin (rho = 0.23, p = 0.03) but not with disability. No other pro-inflammatory molecules correlated with HAQ-DI. High chemerin levels were associated with functional disability in RA, whereas no other molecules correlated with loss of function. These results encourage further studies assessing new roles of chemerin as a marker of impairment in RA.

Soluble neuropilin-1 in gingival crevicular fluid is associated with rheumatoid arthritis: An exploratory case-control study

Background

To explore the soluble Neuropilin-1 (sNRP-1) concentrations in gingival crevicular fluid (GCF) and the periodontal clinical status of patients with Rheumatoid Arthritis (RA).

Materials and methods

We conducted an exploratory study with 40 study participants, 20 with RA, and 20 healthy controls. Clinical and periodontal data were recorded, and GCF samples were obtained. sNRP-1 levels in GCF were determined by ELISA assay. Descriptive statistics, Mann-Whitney U test, Unpaired t-test, logistic regression model, and Area Under Receiver Operating Characteristic Curve (AUC-ROC) were made to explore the diagnostic performance accuracy.

Results

RA patients had significantly higher levels of sNRP-1 in GCF (p ​= ​0.0447). The median levels of GCF-sNRP-1 were 208.85 ​pg/μl (IQR 131.03) in the RA group compared to 81.46 ​pg/μl (IQR 163.73) in the control group. We observed an association between the GCF-sNRP-1 concentrations and the RA diagnosis (OR:1.009; CI 1.00-1.001; p ​= ​0.047). The diagnosis of chronic periodontitis was also associated with RA (OR: 6.9; CI 1.52-31.37; p ​= ​0.012). Moreover, the AUC-ROC of GCF-sNRP-1 concentrations combined with periodontal clinical parameters such as periodontal probing depth and periodontal inflamed surface area was 0.80.

Conclusion

This exploratory case-control study shows that RA patients had significantly higher levels of sNRP-1 in GCF. New longitudinal studies are necessary to evaluate the role of NRP-1 in periodontal tissues and consider it an oral biomarker with clinical value in RA.

Increased Mesenchymal Stem Cell Functionalization in Three-Dimensional Manufacturing Settings for Enhanced Therapeutic Applications

Mesenchymal stem/stromal cell (MSC) exist within their in vivo niches as part of heterogeneous cell populations, exhibiting variable stemness potential and supportive functionalities. Conventional extensive 2D in vitro MSC expansion, aimed at obtaining clinically relevant therapeutic cell numbers, results in detrimental effects on both cellular characteristics (e.g., phenotypic changes and senescence) and functions (e.g., differentiation capacity and immunomodulatory effects). These deleterious effects, added to the inherent inter-donor variability, negatively affect the standardization and reproducibility of MSC therapeutic potential. The resulting manufacturing challenges that drive the qualitative variability of MSC-based products is evident in various clinical trials where MSC therapeutic efficacy is moderate or, in some cases, totally insufficient. To circumvent these limitations, various in vitro/ex vivo techniques have been applied to manufacturing protocols to induce specific features, attributes, and functions in expanding cells. Exposure to inflammatory cues (cell priming) is one of them, however, with untoward effects such as transient expression of HLA-DR preventing allogeneic therapeutic schemes. MSC functionalization can be also achieved by in vitro 3D culturing techniques, in an effort to more closely recapitulate the in vivo MSC niche. The resulting spheroid structures provide spatial cell organization with increased cell–cell interactions, stable, or even enhanced phenotypic profiles, and increased trophic and immunomodulatory functionalities. In that context, MSC 3D spheroids have shown enhanced “medicinal signaling” activities and increased homing and survival capacities upon transplantation in vivo. Importantly, MSC spheroids have been applied in various preclinical animal models including wound healing, bone and osteochondral defects, and cardiovascular diseases showing safety and efficacy in vivo. Therefore, the incorporation of 3D MSC culturing approach into cell-based therapy would significantly impact the field, as more reproducible clinical outcomes may be achieved without requiring ex vivo stimulatory regimes. In the present review, we discuss the MSC functionalization in 3D settings and how this strategy can contribute to an improved MSC-based product for safer and more effective therapeutic applications.

Adipokines and Inflammation Alter the Interaction Between Rheumatoid Arthritis Synovial Fibroblasts and Endothelial Cells

Objective: The long-distance migration of rheumatoid arthritis synovial fibroblasts (RASFs) in the severe combined immunodeficiency (SCID) mouse model of rheumatoid arthritis (RA) suggests that an interaction between RASFs and endothelial cells (EC) is critical in this process. Our objective was to assess whether immunomodulatory factors such as adipokines and antirheumatic drugs affect the adhesion of RASFs to ECs or the expression of surface molecules.

Methods: Primary ECs or human umbilical vein endothelial cell (HUVEC) and primary RASFs were stimulated with adiponectin (10 μg/mL), visfatin (100 ng/mL), and resistin (20 ng/mL) or treated with methotrexate (1.5 and 1,000 μM) and the glucocorticoids prednisolone (1 μM) and dexamethasone (1 μM), respectively. The expression of adhesion molecules was analyzed by real-time polymerase chain reaction. The interaction of both cell types was analyzed under static (cell-to-cell binding assay) and dynamic conditions (flow-adhesion assay).

Results: Under static conditions, adipokines increased mostly binding of RASFs to EC (adiponectin: 40%, visfatin: 28%, tumor necrosis factor α: 49%). Under flow conditions, visfatin increased RASF adhesion to HUVEC (e.g., 0.5 dyn/cm²: 75.2%). Reduced adhesion of RASFs to E-selectin was observed after treatment with dexamethasone (e.g., 0.9 dyn/cm²: −40%). In ECs, tumor necrosis factor α (TNF-α) increased expression of intercellular adhesion molecule 1 (20-fold) and vascular cell adhesion molecule 1 (77-fold), whereas P-selectin was downregulated after stimulation with TNF-α (−6-fold).

Conclusion: The adhesion of RASFs to EC was increased by visfatin under static and flow conditions, whereas glucocorticoids were able to decrease adhesion to E-selectin. The process of migration and adhesion of RASFs to ECs could be enhanced by adipokines via adhesion molecules and seems to be targeted by therapeutic intervention with glucocorticoids.

Aminoacyl-tRNA synthetase inhibition activates a pathway that branches from the canonical amino acid response in mammalian cells

Signaling pathways that sense amino acid abundance are integral to tissue homeostasis and cellular defense. Our laboratory has previously shown that halofuginone (HF) inhibits the prolyl-tRNA synthetase catalytic activity of glutamyl-prolyl-tRNA synthetase (EPRS), thereby activating the amino acid response (AAR). We now show that HF treatment selectively inhibits inflammatory responses in diverse cell types and that these therapeutic benefits occur in cells that lack GCN2, the signature effector of the AAR. Depletion of arginine, histidine, or lysine from cultured fibroblast-like synoviocytes recapitulates key aspects of HF treatment, without utilizing GCN2 or mammalian target of rapamycin complex 1 pathway signaling. Like HF, the threonyl-tRNA synthetase inhibitor borrelidin suppresses the induction of tissue remodeling and inflammatory mediators in cytokine-stimulated fibroblast-like synoviocytes without GCN2, but both aminoacyl-tRNA synthetase (aaRS) inhibitors are sensitive to the removal of GCN1. GCN1, an upstream component of the AAR pathway, binds to ribosomes and is required for GCN2 activation. These observations indicate that aaRS inhibitors, like HF, can modulate inflammatory response without the AAR/GCN2 signaling cassette, and that GCN1 has a role that is distinct from its activation of GCN2. We propose that GCN1 participates in a previously unrecognized amino acid sensor pathway that branches from the canonical AAR.

Activation of GPR43 suppresses TNF-α-induced inflammatory response in human fibroblast-like synoviocytes

Although rheumatoid arthritis (RA) has long posed a major threat to global health, the mechanisms driving the development and progression of RA remain incompletely understood. In the present study, we investigated the effects of G protein-coupled receptor 43 (GPR43/FFAR2) in various aspects of the pathogenesis of RA. To our knowledge, this is the first study to demonstrate that GPR43 is expressed on human fibroblast-like synoviocytes (FLS). Furthermore, we show that GPR43 is upregulated in FLS exposed to tumor necrosis factor-α (TNF-α). Importantly, our findings demonstrate that activation of GPR43 using its specific agonist significantly suppressed expression of the following key factors of RA: cytokines, such as interleukin-6 (IL-6), IL-8, high mobility group protein 1 (HMG-1); chemokines, such as monocyte chemoattractant protein 1 (MCP-1), intercellular adhesion molecule 1 (ICAM-1), and vascular cellular adhesion molecule 1 (VCAM-1); markers of oxidative stress, such as production of reactive oxygen species (ROS) and 4-hydroxynoneal (4-HNE); degradative enzymes, such as matrix metalloproteinase-3 (MMP-3) and MMP-13; and activation of the nuclear factor-κB (NF-κB) inflammatory signaling pathway. These results suggest a promising potential role for GPR43 as a specific target in the treatment and prevention of RA.

Myeloid Krüppel-Like Factor 2 Critically Regulates K/BxN Serum-Induced Arthritis

Rheumatoid arthritis (RA) is an immune-mediated inflammatory disease, and Krüppel-like factor 2 (KLF2) regulates immune cell activation and function. Herein, we show that in our experiments 50% global deficiency of KLF2 significantly elevated arthritic inflammation and pathogenesis, osteoclastic differentiation, matrix metalloproteinases (MMPs), and inflammatory cytokines in K/BxN serum-induced mice. The severities of RA pathogenesis, as well as the causative and resultant cellular and molecular factors, were further confirmed in monocyte-specific KLF2 deficient mice. In addition, induction of RA resulted in a decreased level of KLF2 in monocytes isolated from both mice and humans along with higher migration of activated monocytes to the RA sites in humans. Mechanistically, overexpression of KLF2 decreased the level of MMP9; conversely, knockdown of KLF2 increased MMP9 in monocytes along with enrichment of active histone marks and histone acetyltransferases on the MMP9 promoter region. These findings define the critical regulatory role of myeloid KLF2 in RA pathogenesis.

How many cadherins do human endothelial cells express?

The vasculature is the paradigm of a compartment generated by parallel cellular barriers that aims to transport oxygen, nutrients and immune cells in complex organisms. Vascular barrier dysfunction leads to fatal acute and chronic inflammatory diseases. The endothelial barrier lines the inner side of vessels and is the main regulator of vascular permeability. Cadherins comprise a superfamily of 114 calcium-dependent adhesion proteins that contain conserved cadherin motifs and form cell-cell junctions in metazoans. In mature human endothelial cells, only VE (vascular endothelial)-cadherin and N (neural)-cadherin have been investigated in detail. Although both cadherins are essential for regulating endothelial permeability, no comprehensive expression studies to identify which other family members could play a relevant role in endothelial cells has so far been performed. Here, we have reviewed gene and protein expression databases to analyze cadherin expression in mature human endothelium and found that at least 24 cadherin superfamily members are significantly expressed. Based on data obtained from other cell types, organisms and experimental models, we discuss their potential functions, many of them unrelated to the formation of endothelial cell-cell junctions. The expression of this new set of endothelial cadherins highlights the important but still poorly defined roles of planar cell polarity, the Hippo pathway and mitochondria metabolism in human vascular homeostasis.

Induction of Krüppel-like factor 2 reduces K/BxN serum-induced arthritis

Krüppel-like factor 2 (KLF2) critically regulates activation and function of monocyte, which plays important pathogenic role in progressive joint destruction in rheumatoid arthritis (RA). It is yet to be established the molecular basis of KLF2-mediated regulation of monocytes in RA pathogenesis. Herein, we show that a class of compound, HDAC inhibitors (HDACi) induced KLF2 expression in monocytes both in vitro and in vivo. KLF2 level was also elevated in tissues, such as bone marrow, spleen and thymus in mice after infusion of HDACi. Importantly, HDACi significantly reduced osteoclastic differentiation of monocytes with the up-regulation of KLF2 and concomitant down-regulation of matrixmetalloproteinases both in the expression level as well as in the protein level. In addition, HDACi reduced K/BxN serum-induced arthritic inflammation and joint destruction in mice in a dose-dependent manner. Finally, co-immunoprecipitation and overexpression studies confirmed that KLF2 directly interacts with HDAC4 molecule in cells. These findings provide mechanistic evidence of KLF2-mediated regulation of K/BxN serum-induced arthritic inflammation.

KIAA1199 Biomarker and Ultrasonographic Findings in Rheumatoid Arthritis Patients and their Correlation with Disease Activity

Introduction Rheumatoid arthritis (RA) is an autoimmune disease that affects multiple joints causing joint destruction. KIAA1199 is a novel angiogenic biomarker derived from fibroblast-like synoviocytes (FLS) it has a role in acceleration and proliferation of FLS and activation of angiogenic signaling pathways leading to erosion of cartilage and bone. Musculoskeletal ultrasound (MUSU) and Power Doppler (PDUS) directly visualizing the synovial membrane vessels, which is important in providing very early information on the changes in synovitis activity during the course of the inflammatory joint disease

Objective To assess the serum level of angiogenic biomarker KIAA1199 in RA patients and its correlation with MSUS, PDUS findings, and the disease activity Patients and methods: Fifty RA patients and 40 healthy control persons age and sex-matched were recruited in this study, KIAA1199 was assessed in the serum of patients and controls, MSUS and PDUS were done for the wrist, elbow, and knee joints for all RA patients

Results Serum KIAA1199 level was significantly higher among RA patients 4.36±1.22 ng/dl compared to control group 2.87±0.51 ng/dl (p<0.001). There was a highly significant correlation between KIAA1199 level and DAS28 (p=0.004), and there was a significant correlation between the PDUS with KIAA1199 level and DAS28 (p=0.001, 0.002 respectively) in wrist joints

Conclusion KIAA1199 is a new pathway that enhancing cell proliferation and angiogenesis. Serum KIAA1199 level may be a useful biomarker for RA activity, and therapeutic target in RA. PDUS correlates significantly with clinical findings and novel angiogenic biomarker in RA patients.

Interleukin-1β induces intercellular adhesion molecule-1 expression, thus enhancing the adhesion between mesenchymal stem cells and endothelial progenitor cells via the p38 MAPK signaling pathway

Endothelial progenitor cells (EPCs) are an important component of stem-cell niches, which are able to promote the self-renewal and pluripotency of mesenchymal stem cells (MSCs). The biological functions of these two cell types is dependent on adhesion, and the adhesion between MSCs and EPCs is important due to their critical role in neovascularization and bone regeneration in tissue engineering. Intercellular adhesion molecule-1 (ICAM-1, also known as cluster of differentiation 54), is a member of the immunoglobulin supergene family, which functions in cell-cell and cell-matrix adhesive interactions. Compared with other adhesion molecules, ICAM-1 is expressed in hematopoietic and nonhematopoietic cells, and can mediate adhesive interactions. The present study aimed to investigate the importance of ICAM-1 in the adhesion of MSCs and EPCs, and demonstrated that adhesion between these cells could be regulated by interleukin (IL)-1β via the p38 mitogen-activated protein kinase pathway. In addition, the results confirmed that ICAM-1 served a critical role in regulation of adhesion between MSCs and EPCs. ELISA, cell immunofluorescence, western blot analysis and adhesion assay were used to confirm our theory from phenomenon to essence. The present study provided evidence to support and explain the adhesion between MSCs and EPCs. Furthermore, the present findings provide a theoretical basis for further stem-cell niche transplantation to increase understanding of the function of MSCs and the crosstalk between MSCs and EPCs in the stem-cell niche.

Fibroblast-like synoviocyte metabolism in the pathogenesis of rheumatoid arthritis

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

KCa1.1 channels regulate β1-integrin function and cell adhesion in rheumatoid arthritis fibroblast-like synoviocytes

Large-conductance calcium-activated potassium channel (KCa1.1; BK, Slo1, MaxiK, KCNMA1) is the predominant potassium channel expressed at the plasma membrane of rheumatoid arthritis fibroblast-like synoviocytes (RA-FLSs) isolated from the synovium of patients with RA. It is a critical regulator of RA-FLS migration and invasion and therefore represents an attractive target for the therapy of RA. However, the molecular mechanisms by which KCa1.1 regulates RA-FLS invasiveness have remained largely unknown. Here, we demonstrate that KCa1.1 regulates RA-FLS adhesion through controlling the plasma membrane expression and activation of β₁ integrins, but not α₄, α₅, or α₆ integrins. Blocking KCa1.1 disturbs calcium homeostasis, leading to the sustained phosphorylation of Akt and the recruitment of talin to β₁ integrins. Interestingly, the pore-forming α subunit of KCa1.1 coimmunoprecipitates with β₁ integrins, suggesting that this physical association underlies the functional interaction between these molecules. Together, these data outline a new signaling mechanism by which KCa1.1 regulates β₁-integrin function and therefore invasiveness of RA-FLSs.-Tanner, M. R., Pennington, M. W., Laragione, T., Gulko, P. S., Beeton, C. KCa1.1 channels regulate β₁-integrin function and cell adhesion in rheumatoid arthritis fibroblast-like synoviocytes.

Characterization of a polysaccharide from Rosa davurica and inhibitory activity against neutrophil migration

The rapid recruitment of neutrophils from peripheral blood into infected sites is critical step for inflammatory responses; however, the excessive and improper recruitment can lead to serious tissue damages. Thus, it is a promising strategy to inhibit their excessive recruitment for treating inflammation-related disease. Here, we isolated a polysaccharide (RDPA1) from Rosa davurica, to evaluate its physicochemical property and inhibitory effects on neutrophil migration. RDPA1 was obtained by hot-water extraction, ethanol precipitation, and fractionated by DEAE-cellulose and Sepharose CL-6B columns. RDPA1 significantly inhibited in vitro migration of human neutrophils evaluated by transwell chamber and impacted the migratory behavior observed by time-lapsed microscopy, we found the migrated distance and average velocity of RDPA1-treated cells were greatly reduced. In addition, RDPA1 treatment impaired in vivo neutrophil infiltration in the peritonitis mice. RDPA1 exhibited significant blocking capacity of the interaction between β2 integrins and ICAM-1 evaluated by flow cytometry and in vitro protein binding assay. Together, these results suggest RDPA1 could be considered as a potential candidate for developing a novel anti-inflammatory agent.

CDH2 and CDH11 act as regulators of stem cell fate decisions

Accumulating evidence suggests that the mechanical and biochemical signals originating from cell-cell adhesion are critical for stem cell lineage specification. In this review, we focus on the role of cadherin mediated signaling in development and stem cell differentiation, with emphasis on two well-known cadherins, cadherin-2 (CDH2) (N-cadherin) and cadherin-11 (CDH11) (OB-cadherin). We summarize the existing knowledge regarding the role of CDH2 and CDH11 during development and differentiation in vivo and in vitro. We also discuss engineering strategies to control stem cell fate decisions by fine-tuning the extent of cell-cell adhesion through surface chemistry and microtopology. These studies may be greatly facilitated by novel strategies that enable monitoring of stem cell specification in real time. We expect that better understanding of how intercellular adhesion signaling affects lineage specification may impact biomaterial and scaffold design to control stem cell fate decisions in three-dimensional context with potential implications for tissue engineering and regenerative medicine.

Davallia bilabiata Inhibits TNF-α-Induced Adhesion Molecules and Chemokines by Suppressing IKK/NF-kappa B Pathway in Vascular Endothelial Cells

Davallia bilabiata (D. bilabiata) is also called GuSuiBu in Taiwan and is used as a substitute for Drynaria fortunei J. Sm. It is often used for trauma and bone repair. The inhibitory effect of D. bilabiata on inflammatory activity has not been reported. In the present study, we aimed to study the mechanism of anti-inflammation of D. bilabiata on the adhesion of leukocytes to vascular endothelial cells. The results showed that D. bilabiata, at concentrations without cytotoxic effect, inhibited the adhesion of monocytes (THP-1) to the TNF-α-stimulated human umbilical vascular endothelial cells (HUVECs). D. bilabiata suppressed the expression of the adhesion molecules ICAM, VCAM, and E-selectin at both the mRNA and protein level. In addition, both of the TNF-α-induced mRNA and protein expression of chemokines including fractalkine/CX3CL1, MCP-1 and RANTES as well as the level of secreted soluble fractalkine were decreased by D. bilabiata. We also verified that D. bilabiata inhibited the TNF-α-induced nuclear translocation of NF-κB through the inhibitory process on the TNF-α-activated phosphorylation of IKKα, IKKβ, IκB and NF-κB. All together, we concluded that the D. bilabiata affected the canonical pathway of TNF-α-induced NF-κB activation and down-regulated cell adhesion molecules and chemokine expression through inhibition of the NF-κB/IκBα/IKK signaling pathway. These findings strongly indicated that D. bilabiata might be a promising alternative/adjunct treatment for inflammatory diseases, such as rheumatoid arthritis and osteoarthritis.

Therapeutic effect of dimethyl dimethoxy biphenyl dicarboxylate on collagen-induced arthritis in rats

OBJECTIVE

To study the effect of oral administration of dimethyl dimethoxy biphenyl dicarboxylate (DDB) on adjusting angiogeneic/inflammatory mediators and ameliorating the pathology of bones in rats with collagen-induced arthritis (CIA).

METHODS

Wistar rat model of CIA was set up using bovine collagen type II. Fifty rats were divided into five groups randomly: normal, CIA model, DDB treatment, methotrexate (MTX) treatment, and combined DDB+MTX treatment. Ankle joints of rats were imaged with digital X-ray machine to show the destruction of joints. Fore and hind paw and knee joints were removed above the ankle joint then processed for haematoxylin and eosin staining. Plasma levels of vascular endothelial growth factor (VEGF), platelet derived growth factor, interleukin-8 (IL-8), IL-4, tumor necrosis factor α (TNF-α), and cyclooxygenase-2 (COX-2) were quantified by enzyme-linked immunosorbent assay. Nitric oxide levels were detected by Griess reagent.

RESULTS

Compared with the CIA model group, a remarkable reduction in various angiogenic (VEGF and IL-8) and inflammatory mediators (TNF-α, IL-4 and COX-2) after treatment with DDB either alone or combined with MTX P<0.05 or P<0.01). Histopathological and X-ray findings were confirmatory to the observed DDB anti-arthritic effect. The DDB-treated group showed amelioration in signs of arthritis which appeared essentially similar to normal.

CONCLUSION

Our data shed light on the therapeutic efficacy of DDB in experimental rheumatoid arthritis (RA) compared with a choice drug (MTX) and it may be offered as a second-line drug in the treatment of RA.

Interaction of mesenchymal stem cells with fibroblast-like synoviocytes via cadherin-11 promotes angiogenesis by enhanced secretion of placental growth factor

Bone marrow-derived mesenchymal stem cells (MSC) exist in the synovium of patients with rheumatoid arthritis (RA), yet the role of MSC in RA is elusive. Placental growth factor (PlGF) expression is increased in RA synovial fluids, and blocking of PlGF attenuates progression of arthritis in mice. In this study, we observed that PlGF induced chemotaxis of MSC in a dose-dependent manner, which was blocked by anti-vascular endothelial growth factor receptor-1 peptide. MSC exposed to PlGF elicited increased phosphorylation of Akt and p38 MAPK. PlGF-mediated chemotaxis was inhibited by PI3K inhibitor (LY294002) and p38 MAPK inhibitor (SB203580), but not by ERK1/2 inhibitor (PD98059). Fibroblast-like synoviocytes (FLS) constitutively produced PlGF, but MSC released negligible amounts of PlGF. Of note, when FLS of RA patients and MSC were cocultured, PlGF production by FLS was significantly increased; such an increase was dependent on the number of added MSC. Moreover, coculture conditioned medium promoted chemotaxis of MSC and increased angiogenesis in Matrigel plugs assay, and these were suppressed by preincubation of the medium with anti-PlGF Ab. Transwell experiments revealed that MSC to FLS contact was required for the increase in PlGF production by coculture. Cadherin-11 was expressed both in FLS and MSC, and small interfering RNA knockdown of cadherin-11 in FLS significantly abrogated the enhanced PlGF production under coculture conditions. These data indicate that increased levels of PlGF in RA joints could induce the migration of MSC to the synovium, and interaction of migrated MSC with FLS via cadherin-11 may contribute to angiogenesis and chronic synovitis by enhancing the secretion of PlGF.

Proteomic analysis of human osteoarthritis synovial fluid

Background

Osteoarthritis is a chronic musculoskeletal disorder characterized mainly by progressive degradation of the hyaline cartilage. Patients with osteoarthritis often postpone seeking medical help, which results in the diagnosis being made at an advanced stage of cartilage destruction. Sustained efforts are needed to identify specific markers that might help in early diagnosis, monitoring disease progression and in improving therapeutic outcomes. We employed a multipronged proteomic approach, which included multiple fractionation strategies followed by high resolution mass spectrometry analysis to explore the proteome of synovial fluid obtained from osteoarthritis patients. In addition to the total proteome, we also enriched glycoproteins from synovial fluid using lectin affinity chromatography.

Results

We identified 677 proteins from synovial fluid of patients with osteoarthritis of which 545 proteins have not been previously reported. These novel proteins included ADAM-like decysin 1 (ADAMDEC1), alanyl (membrane) aminopeptidase (ANPEP), CD84, fibulin 1 (FBLN1), matrix remodelling associated 5 (MXRA5), secreted phosphoprotein 2 (SPP2) and spondin 2 (SPON2). We identified 300 proteins using lectin affinity chromatography, including the glycoproteins afamin (AFM), attractin (ATRN), fibrillin 1 (FBN1), transferrin (TF), tissue inhibitor of metalloproteinase 1 (TIMP1) and vasorin (VSN). Gene ontology analysis confirmed that a majority of the identified proteins were extracellular and are mostly involved in cell communication and signaling. We also confirmed the expression of ANPEP, dickkopf WNT signaling pathway inhibitor 3 (DKK3) and osteoglycin (OGN) by multiple reaction monitoring (MRM) analysis of osteoarthritis synovial fluid samples.

Conclusions

We present an in-depth analysis of the synovial fluid proteome from patients with osteoarthritis. We believe that the catalog of proteins generated in this study will further enhance our knowledge regarding the pathophysiology of osteoarthritis and should assist in identifying better biomarkers for early diagnosis.

Wen Luo Yin inhibits angiogenesis in collagen-induced arthritis rat model and in vitro

ETHNOPHARMACOLOGICAL RELEVANCE AND AIM OF THE STUDY

Wen Luo Yin (WLY) is a traditional Chinese formula, which has the traditional use of scattering cold pathogen, draining dampness, freeing the flow of network vessels and relieving pains. It is extensively used in the treatment of rheumatoid arthritis (RA) patients for more than 2000 years, but its actions on angiogenesis of RA have not been clarified. The present study aims to determine the anti-angiogenic activity of WLY on collagen-induced arthritis (CIA) rat model and in human fibroblast-like synoviocytes of RA (HFLS-RA) and human umbilical vein endothelial cells (HUVEC).

MATERIALS AND METHODS

For in vivo experiment, arthritis was induced by immunization with bovine II collagen in DA rats. Treatment with WLY (3.45, 6.9, 13.8 g/kg, p.o., daily), or vehicle began from day 1 to day 28 of first immunization. The arthritis score, arthritis incidence, microfocal computed tomography analysis and histopathology evaluation of inflamed joints were assessed. Angiogenesis was measured by synovial vessel density with immunohistochemistry and histomorphometric analysis in synovial membrane tissues of joints. For in vitro experiments, HFLS-RA and HUVEC were used. Assays to determine HFLS-RA migration and adhesion were performed in the presence of vascular endothelial growth factor (VEGF)165 or interleukin (IL)-1β and/or the WLY (8, 16, 32 mg/ml). Angiogenesis was assessed by measuring the migration, adhesion, and tube formation of HUVEC. Further the effect of treatment with WLY on expression levels of angiogenic activators in sera of CIA rats and in IL-1β-induced HFLS-RA were evaluated by enzyme linked immunosorbent assay.

RESULTS

WLY significantly decreased the arthritis score and arthritis incidence, and inhibited inflammation, pannus formation, cartilage and bone destruction of inflamed joints in CIA rats. More interestingly, doses of 3.45-13.8 g/kg WLY could markedly reduce the capillaries, small, medium and large vessel density in synovial membrane tissues of inflamed joints. Moreover, WLY suppressed the VEGF-induced chemotactic migration of HFLS-RA and HUVEC, and inhibited matrigel-induced cell adhesion of them. It also disrupted tube formation of HUVEC on matrigel. Furthermore, WLY significantly reduced the expression of angiogenic activators including tumor necrosis factor-α, IL-1β, IL-17, VEGF, VEGFR, angiopoietin (Ang)-1, Ang-2 and Ang-2 receptor in sera of CIA rats and/or in IL-1β-induced HFLS-RA/HUVEC.

CONCLUSIONS

Our data suggest for the first time that WLY posses the anti-angiogenic effect in RA both in vivo and in vitro by downregulating angiogenic activators.

Role of cadherin-11 in synovial joint formation and rheumatoid arthritis pathology

Cadherin-11 is a classic cadherin adhesion molecule that mediates homophilic cell-to-cell adhesion. Cadherin-11 is involved in the function of embryonic development, tissue morphogenesis, tumor invasion and metastasis, and signal transduction. This review summarizes the function of cadherin-11 in synovial joint formation and rheumatoid arthritis (RA), including its relative function with bone and cartilage development and growth plate, synovial, and tendon formation. The role of cadherin-11 in RA is also discussed, both in fibroblasts inflammation and fibroblast-like synoviocyte (FLSs) migration and invasion. The potential of anti-cadherin-11 therapy for RA is introduced in comparison with the other current RA therapies.

The loss of α2β1 integrin suppresses joint inflammation and cartilage destruction in mouse models of rheumatoid arthritis

OBJECTIVE

Integrin α2β1 functions as a major receptor for type I collagen on different cell types, including fibroblasts and inflammatory cells. Although in vitro data suggest a role for α2β1 integrin in regulating both cell attachment and expression of matrix-degrading enzymes such as matrix metalloproteinases (MMPs), mice that lack the α2 integrin subunit (Itga2(-/-) mice) develop normally and are fertile. We undertook this study to investigate the effect of Itga2 deficiency in 2 different mouse models of destructive arthritis: the antigen-induced arthritis (AIA) mouse model and the human tumor necrosis factor α (TNFα)-transgenic mouse model.

METHODS

AIA was induced in the knee joints of Itga2(-/-) mice and wild-type controls. Human TNF-transgenic mice were crossed with Itga2(-/-) mice and were assessed clinically and histopathologically for signs of arthritis, inflammation, bone erosion, and cartilage damage. MMP expression, proliferation, fibroblast attachment, and ERK activation were determined.

RESULTS

Under arthritic conditions, Itga2 deficiency led to decreased severity of joint pathology. Specifically, Itga2(-/-) mice showed less severe clinical symptoms and dramatically reduced pannus formation and cartilage erosion. Mice lacking α2β1 integrin exhibited reduced MMP-3 expression, both in their sera and in fibroblast-like synoviocytes (FLS), due to impaired ERK activation. Further, both the proliferation and attachment of FLS to cartilage were partially dependent on α2β1 integrin in vitro and in vivo.

CONCLUSION

Our findings suggest that α2β1 integrin contributes significantly to inflammatory cartilage destruction by promoting fibroblast proliferation and attachment and MMP expression.

Kruppel-like factor 2 (KLF2) regulates monocyte differentiation and functions in mBSA and IL-1β-induced arthritis

Kruppel-like factor 2 (KLF2) plays an important role in the regulation of a variety of immune cells, including monocytes. We have previously shown that KLF2 inhibits proinflammatory activation of monocytes. However, the role of KLF2 in arthritis is yet to be investigated. In the current study, we show that recruitment of significantly greater numbers of inflammatory subset of CD11b(+)F4/80(+)Ly6C+ monocytes to the inflammatory sites in KLF2 hemizygous mice compared to the wild type littermate controls. In parallel, inflammatory mediators, MCP-1, Cox-2 and PAI-1 were significantly up-regulated in bone marrow-derived monocytes isolated from KLF2 hemizygous mice, in comparison to wild-type controls. Methylated-BSA and IL-1β-induced arthritis was more severe in KLF2 hemizygous mice as compared to the littermate wild type controls. Consistent with this observation, monocytes isolated from KLF2 hemizygous mice showed an increased number of cells matured and differentiated towards osteoclastic lineage, potentially contributing to the severity of cartilage and bone damage in induced arthritic mice. The severity of arthritis was associated with the higher expression of proteins such as HSP60, HSP90 and MMP13 and attenuated levels of pPTEN, p21, p38 and HSP25/27 molecules in bone marrow cells of arthritic KLF2 hemizygous mice compared to littermate wild type controls. The data provide new insights and evidences of KLF2-mediated transcriptional regulation of arthritis via modulation of monocyte differentiation and function.

CD146+ T lymphocytes are increased in both the peripheral circulation and in the synovial effusions of patients with various musculoskeletal diseases and display pro-inflammatory gene profiles

Twenty-eight synovial effusions (SE) were obtained from 24 patients, paired samples of peripheral blood (PB) from 10 of these patients, and PB from 36 healthy individuals for analysis of CD146 on T-lymphocytes by flow cytometry. CD146+ or CD146- T-lymphocytes were sorted from three SE to study gene expression profiles and selected genes revalidated using QPCR assays. We found more CD3+CD146+ and CD4+CD146+ T-lymphocytes in PB from patients compared with PB of healthy individuals (4.71% +/- 2.48% vs. 2.53% +/- 1.08%, P = 0.028) and (6.29% +/- 2.74% vs. 2.41% +/- 0.96%, P = 0.0017), respectively, whereas CD8+CD146+ T-lymphocytes were not significantly different (2.55% +/- 1.65% vs. 3.18% +/- 2.59%, P = 0.5008). SE displayed CD146 staining on 16.32% +/- 6.06% of CD3+ cells. This expression was skewed toward CD4+ T-lymphocytes, with CD146 present on 24.06% +/- 8.20% of the CD4+ T-lymphocytes compared with 6.19% +/- 5.22% of the CD8+ T-lymphocytes. CD146 on CD3+, CD4+ and CD8+ T-lymphocytes in SE was significantly higher compared with PB in patients (P < 0.0001, P < 0.0001 and P = 0.0036, respectively). Gene expression profiles of sorted CD146+CD4+CD3+ vs. CD146-CD4+CD3+ T-lymphocytes (n = 2) and CD2+CD146+ vs. CD2+CD 146- (n = 1) from SE, displayed increased CD146, LAIR2, CXCL13, CD109, IL6ST, IL6R, TNFRsf18, and TNFRsf4 genes, whereas decreased CCR7, CCL5, and cytotoxicity-associated genes including granzymes b, h, and k, perforin were found with the CD146- T-lymphocytes. By QPCR higher mRNA expression of CXCL13, CD146 and CD109 was also noted in the CD146+ subset, compared with the CD146- subset, in PB of healthy individuals and in PB and SE from patients. Our study establishes increased CD146+ T-lymphocytes in diseases with joint effusions, and demonstrates pro-inflammatory gene profiles in these cells.

Phagocytosis of apoptotic cells modulates mesenchymal stem cells osteogenic differentiation to enhance IL-17 and RANKL expression on CD4+ T cells

Osteogenic differentiation of mesenchymal stem cells (MSC) is important to homeostatic bone remodeling. Infiltration of mesenchymal progenitor cells to inflamed joints has been reported in collagen-induced arthritis murine model and in patients with rheumatoid arthritis (RA). Therapeutic application of MSC in RA has been suggested and under investigation. However, the underlying mechanisms on what triggers the migration of MSC from bone marrow (BM) to inflamed joints and how MSC acts in the joints remains elusive. As hemopoietic stem cells and MSC act reciprocally and excessive apoptotic cells (AC) are observed in the BM of patients with RA, we hypothesize that AC may alter MSC osteogenic differentiation resulting in bone erosion in RA. In this study, we demonstrated for the first time that MSC were able to phagocytose AC and this phagocytosis enhanced MSC osteogenic differentiation. AC-treated MSC under osteogenic differentiation expressed CXC-chemokine receptor (CXCR)-4 and CXCR5, which might enable them to migrate toward the inflamed joints. In addition, AC-treated MSC secreted interleukin (IL)-8, monocyte chemoattractant protein-1, and RANTES, which might induce chemotaxis of CD4+ T cells to the inflamed joints. Interestingly, by coculturing AC-treated MSC under osteogenic differentiation with CD4+ T cells, T helper (Th) 17 cells development was significantly enhanced and these Th17 cells promoted osteoclasts formation and bone resorption. Furthermore, the induction of Th17 cells was dependent on increased IL-6 production from major histocompatibility complex class II-expressing AC-treated MSC under osteogenic differentiation. This data provide a novel insight on the role of AC in modulating MSC osteogenic differentiation and function in inflammatory bone diseases.

Shedding of large functionally active CD11/CD18 Integrin complexes from leukocyte membranes during synovial inflammation distinguishes three types of arthritis through differential epitope exposure

CD18 integrins are adhesion molecules expressed on the cell surface of leukocytes and play a central role in the molecular mechanisms supporting leukocyte migration to zones of inflammation. Recently, it was discovered that CD11a/CD18 is shed from the leukocyte surface in models of inflammation. In this study, we show that shedding of human CD11/CD18 complexes is a part of synovial inflammation in rheumatoid arthritis and spondyloarthritis but not in osteoarthritis. In vivo and in vitro data suggest that the shedding is driven by TNF-α, which links the process to central events in the inflammatory response. The shed complexes contain multiple heterodimers of CD11/CD18, are variable in size, and differ according to the type of synovial inflammation. Furthermore, the differential structures determine the avidity of binding of the complexes to the ICAM-1. With the estimated concentrations of CD11/CD18 in plasma and synovial fluid a significant coverage of binding sites in ICAM-1 for CD18 integrins is expected. Based on cell adhesion experiments in vitro, we hypothesize that the large soluble complexes of CD11/CD18 act in vivo to buffer leukocyte adhesion by competing with the membrane-bound receptors for ICAM-1 binding sites. As reported here for synovial inflammation changes in the concentration or structure of these complexes should be considered as likely contributors to disease activity.

Effects of inflammatory cytokine IL-27 on the activation of fibroblast-like synoviocytes in rheumatoid arthritis

Introduction

Interleukin (IL)-27 is a novel member of the IL-6/IL-12 family cytokines that are produced early by antigen-presenting cells in T helper (Th)1-mediated inflammation. Elevated expression of IL-27 has been detected in the synovial membranes and fluid of rheumatoid arthritis (RA).

Methods

We investigated the in vitro effects of IL-27, alone or in combination with inflammatory cytokine tumor necrosis factor (TNF)-α or IL-1 β on the pro-inflammatory activation of human primary fibroblast-like synoviocytes (FLS) from RA patients and normal control subjects, and the underlying intracellular signaling molecules were determined by intracellular staining using flow cytometry.

Results

Significantly higher plasma concentration of IL-27 was found in RA patients (n = 112) than control subjects (n = 46). Both control and RA-FLS constitutively express functional IL-27 receptor heterodimer, gp130 and WSX-1, with more potent IL-27-mediated activation of signal transducers and activators of transcription (STAT)1 in RA-FLS. IL-27 was found to induce significantly higher cell surface expression of intercellular adhesion molecule (ICAM)-1 and vascular cell adhesion molecule (VCAM)-1 and release of inflammatory chemokine IL-6, CCL2, CXCL9, CXCL10 and matrix metalloproteinase-1 of RA-FLS than that of control FLS (all P < 0.05). Moreover, an additive or synergistic effect was observed in the combined treatment of IL-27 and TNF-α or IL-1 β on the surface expression of ICAM-1 and VCAM-1 and the release of CXCL9 and CXCL10 of RA-FLS. Further investigations showed that the expression of ICAM-1, VCAM-1 and chemokines stimulated by IL-27 was differentially regulated by intracellular activation of phosphatidylinositol 3-OH kinase-AKT, c-Jun amino-terminal kinase and Janus kinase pathways.

Conclusions

Our results therefore provide a new insight into the IL-27-activated immunopathological mechanisms mediated by distinct intracellular signal transductions in joint inflammation of RA.

Anti-neuropilin-1 peptide inhibition of synoviocyte survival, angiogenesis, and experimental arthritis

OBJECTIVE

To delineate the role of neuropilin-1 (NP-1), a vascular endothelial growth factor receptor (VEGFR), in rheumatoid inflammation and to determine whether blockade of NP-1 could suppress synoviocyte survival and angiogenesis.

METHODS

VEGF(111-165) peptide, which encompasses the NP-1 binding domain of VEGF(165), was generated by cleaving VEGF(165) with plasmin. The effect of this peptide on the interaction between VEGF(165) and its receptor was determined by (125)I-VEGFR binding assay. Assays to determine synoviocyte apoptosis, adhesion, and migration were performed in the presence of VEGF(165) and/or the peptide. VEGF(165)-induced angiogenesis was assessed by measuring the proliferation, tube formation, and wounding migration of endothelial cells (ECs). Mice were immunized with type II collagen to induce experimental arthritis.

RESULTS

VEGF(111-165) peptide specifically inhibited the binding of (125)I-VEGF(165) to NP-1 on rheumatoid synoviocytes and ECs. The peptide eliminated the VEGF(165)-mediated increase in synoviocyte survival and activation of p-ERK and Bcl-2. The peptide also completely inhibited a VEGF(165)-induced increase in synoviocyte adhesion and migration. In addition, the anti-NP-1 peptide blocked VEGF(165)-stimulated proliferation, capillary tube formation, and wounding migration of ECs in vitro. VEGF(165)-induced neovascularization in a Matrigel plug in mice was also blocked by treatment with the peptide. Finally, subcutaneous injection of anti-NP-1 peptide suppressed arthritis severity and autoantibody formation in mice with experimental arthritis and inhibited synoviocyte hyperplasia and angiogenesis in arthritic joints.

CONCLUSION

Anti-NP-1 peptide suppressed VEGF(165)-induced increases in synoviocyte survival and angiogenesis, and thereby blocked experimental arthritis. Our findings suggest that anti-NP-1 peptide could be useful in alleviating chronic arthritis.

An LFA-1 (alphaLbeta2) small-molecule antagonist reduces inflammation and joint destruction in murine models of arthritis

LFA-1 appears to play a central role in normal immune responses to foreign Ags. In autoimmune or inflammatory diseases, there is increased expression of LFA-1 and/or its counterligand, ICAM-1. Others have demonstrated that the targeted disruption of LFA-1:ICAM interactions, either by gene deletion or Ab treatment in mice, results in reduced leukocyte trafficking, inflammatory responses, and inhibition of inflammatory arthritis in the K/BxN serum transfer model. However, there has been little success in finding a small-molecule LFA-1 antagonist that can similarly impact rodent models of arthritis. In this paper, we present the first reported example of an LFA-1 small-molecule antagonist, BMS-587101, that is efficacious in preclinical disease models. In vitro, BMS-587101 inhibited LFA-1-mediated adhesion of T cells to endothelial cells, T cell proliferation, and Th1 cytokine production. Because BMS-587101 exhibits in vitro potency, cross-reactivity, and oral bioavailability in rodents, we evaluated the impact of oral administration of this compound in two different models of arthritis: Ab-induced arthritis and collagen-induced arthritis. Significant impact of BMS-587101 on clinical score in both models was observed, with inhibition comparable or better than anti-mouse LFA-1 Ab. In addition, BMS-587101 significantly reduced cytokine mRNA levels in the joints of Ab-induced arthritis animals as compared with those receiving vehicle alone. In paws taken from the collagen-induced arthritis study, the bones of vehicle-treated mice had extensive inflammation and bone destruction, whereas treatment with BMS-587101 resulted in marked protection. These findings support the potential use of an LFA-1 small-molecule antagonist in rheumatoid arthritis, with the capacity for disease modification.

Angiogenesis in rheumatoid arthritis

Angiogenesis is the formation of new capillaries from pre-existing vessels. A number of soluble and cell-bound factors may stimulate neovascularization. The perpetuation of angiogenesis involving numerous soluble and cell surface-bound mediators has been associated with rheumatoid arthritis (RA). These angiogenic mediators, among others, include growth factors, primarily vascular endothelial growth factor (VEGF) and hypoxia-inducible factors (HIFs), as well as pro-inflammatory cytokines, various chemokines, matrix components, cell adhesion molecules, proteases and others. Among the several potential angiogenesis inhibitors, targeting of VEGF, HIF-1, angiogenic chemokines, tumor necrosis factor-alpha and the alpha(V)beta(3) integrin may attenuate the action of angiogenic mediators and thus synovial angiogenesis. In addition, some naturally produced or synthetic compounds including angiostatin, endostatin, paclitaxel, fumagillin analogues, 2-methoxyestradiol and thalidomide may be included in the management of RA.

New insights in synovial angiogenesis

Angiogenesis is the formation of new capillaries from pre-existing vessels. A number of soluble and cell-bound factors may stimulate neovascularization. The perpetuation of angiogenesis involving numerous soluble and cell surface-bound mediators has been associated with rheumatoid arthritis (RA). These angiogenic mediators, among others, include growth factors, primarily vascular endothelial growth factor (VEGF) and hypoxia-inducible factors (HIFs), as well as pro-inflammatory cytokines, various chemokines, cell adhesion molecules, proteases and others. Among the several potential angiogenesis inhibitors, targeting of VEGF, HIF-1, angiopoietin and the alpha(V)beta(3) integrin, as well as some endogenous or synthetic compounds including angiostatin, endostatin, paclitaxel, fumagillin analogues, 2-methoxyestradiol and thalidomide seems to be promising for the management of synovial inflammation and angiogenesis. A complete review of antiangiogenic drugs used in animal models of arthritis or human RA is available in a table.

Molecular MR imaging for visualizing ICAM-1 expression in the inflamed synovium of collagen-induced arthritic mice

Objective

To determine the utility of intercellular adhesion molecule (ICAM)-1 antibody-conjugated gadolinium diethylenetriaminepentaacetic acid (Gd-DTPA-anti-ICAM-1) as a targeted contrast agent for the molecular magnetic resonance imaging (MRI) in collagen-induced arthritis (CIA).

Materials and Methods

Three groups of mice were used: non-arthritic normal, CIA mice in both the early inflammatory and chronic destructive phases. The MR images of knee joints were obtained before and after injection of Gd-DTPA-anti-ICAM-1, Gd-DTPA, and Gd-DTPA-Immunoglobulin G (Ig G) and were analyzed quantitatively. The patterns of enhancement on the MR images were compared with the histological and immunohistochemical ICAM-1 staining.

Results

The images obtained after injection of Gd-DTPA-anti-ICAM-1 displayed gradually increasing signal enhancement from the moment following injection (mean ± standard deviation [SD]: 424.3 ± 35.2, n = 3) to 24 hours (532 ± 11.3), rather than on pre-enhanced images (293 ± 37.6) in the early inflammatory phase of CIA mice. However, signal enhancement by Gd-DTPA and Gd-DTPA-IgG disappeared after 80 minutes and 24 hours, respectively. In addition, no significant enhancement was seen in the chronic destructive phase of CIA mice, even though they also showed inflammatory changes on T2-weighted MR images. ICAM-1 expression was demonstrated in the endothelium and proliferating synovium of the early inflammatory phase of CIA mice, but not in the chronic destructive phase.

Conclusion

Molecular MRI with Gd-DTPA-anti-ICAM-1 displays specific images targeted to ICAM-1 that is expressed in the inflamed synovium of CIA. This novel tool may be useful for the early diagnosis and differentiation of the various stages of rheumatoid arthritis.

Expression of Brachyury in mesenchymal progenitor cells leads to cartilage-like tissue that is resistant to the destructive effect of rheumatoid arthritis synovial fibroblasts

Our objectives were to determine the chondrogenic potential of a murine Brachyury-transformed mesenchymal progenitor cell line in the presence of rheumatoid arthritis-activated synovial fibroblasts (RASFs). Brachyury-transformed mesenchymal progenitor cells were implanted alone or combined with RASFs isolated from diseased human joints in each of six immunodeficient SCID mice. De novo tissue formation was analysed by histology and immunohistochemistry after 60 days. Spheroid nodules resembling cartilage morphologically and by the expression of proteoglycans and collagen II developed in four of six implants in the absence and in five of six implants in the presence of RASFs. No evidence for hypertrophic differentiation could be observed. Mesenchymal progenitor cells transformed with Brachyury are able to produce a cartilage like tissue in vivo over an extended period of time that is resistant to the destructive effect of RASF. This observation may provide opportunities for a cell-based reconstructive treatment in joint disease.

The investigation of synovial genomic targets of bucillamine with microarray technique

OBJECTIVE

To identify the molecular mechanisms of bucillamine activity, global gene expression analysis and pathway analysis were conducted using IL-1 beta-stimulated human fibroblast-like synovial cells (FLS).

METHODS

Normal human FLS were treated with IL-1 beta in the presence or absence of 10 and 100 microM bucillamine for 6 h. Total RNA was extracted and global gene expression levels were detected using a 44 k human whole genome array. Data were analyzed using Ingenuity pathway analysis.

RESULTS

Numerous pathways were activated by IL-1 beta stimulation. At both concentrations, bucillamine suppressed nine signal pathways stimulated by IL-1 beta.

CONCLUSIONS

Bucillamine effectively inhibited fibroblast growth factor (FGF) signaling and tight junction signaling activated by IL-1 beta in FLS. Suppression of these signal pathways may correlate with the pharmacologic mechanisms of bucillamine. In particular, the suppression of FGF signaling by bucillamine is remarkable because the activation of FGF signaling may be involved in rheumatoid arthritis pathology.

Intra-articular depot formulation principles: role in the management of postoperative pain and arthritic disorders

The joint cavity constitutes a discrete anatomical compartment that allows for local drug action after intra-articular injection. Drug delivery systems providing local prolonged drug action are warranted in the management of postoperative pain and not least arthritic disorders such as osteoarthritis. The present review surveys various themes related to the accomplishment of the correct timing of the events leading to optimal drug action in the joint space over a desired time period. This includes a brief account on (patho)physiological conditions and novel potential drug targets (and their location within the synovial space). Particular emphasis is paid to (i) the potential feasibility of various depot formulation principles for the intra-articular route of administration including their manufacture, drug release characteristics and in vivo fate, and (ii) how release, mass transfer and equilibrium processes may affect the intra-articular residence time and concentration of the active species at the ultimate receptor site.

Cyclosporin A inhibits CD11a/CD18 adhesion molecules due to inhibition of TNFalpha and IL-1 beta levels in the mouse model of pleurisy induced by carrageenan

The mouse model of pleurisy induced by carrageenan is characterized by a significant enhancement of cell migration due to neutrophils 4 h after pleurisy induction. Forty-eight hours after pleurisy induction, a significant increase in cell migration due to mononuclear cells occurs. Recently, studies in our laboratory have demonstrated that cyclosporine A (CsA) inhibits leukocyte migration in the pleural cavity and lungs in the mouse model of pleurisy induced by carrageenan. In the present work we evaluated whether CsA was able to downregulate CD11a/CD18 adhesion molecule in the lungs, as well as TNFalpha and IL-1 beta levels in the fluid leakage of the pleural cavity in this model. Our results showed that CsA significantly decreased CD11a/CD18 in the lungs, as well as TNFalpha and IL-1 beta levels in the fluid leakage of the pleural cavity 4 h and 48 h after pleurisy induction. It is our hypothesis that the inhibitory effect elicited by CsA upon these adhesion molecules may be also be attributed to the downregulation of TNFalpha and IL-1 beta cytokines.

Vascular involvement in rheumatic diseases: 'vascular rheumatology'

The vasculature plays a crucial role in inflammation, angiogenesis, and atherosclerosis associated with the pathogenesis of inflammatory rheumatic diseases, hence the term 'vascular rheumatology'. The endothelium lining the blood vessels becomes activated during the inflammatory process, resulting in the production of several mediators, the expression of endothelial adhesion molecules, and increased vascular permeability (leakage). All of this enables the extravasation of inflammatory cells into the interstitial matrix. The endothelial adhesion and transendothelial migration of leukocytes is a well-regulated sequence of events that involves many adhesion molecules and chemokines. Primarily selectins, integrins, and members of the immunoglobulin family of adhesion receptors are involved in leukocyte 'tethering', 'rolling', activation, and transmigration. There is a perpetuation of angiogenesis, the formation of new capillaries from pre-existing vessels, as well as that of vasculogenesis, the generation of new blood vessels in arthritis and connective tissue diseases. Several soluble and cell-bound angiogenic mediators produced mainly by monocytes/macrophages and endothelial cells stimulate neovascularization. On the other hand, endogenous angiogenesis inhibitors and exogenously administered angiostatic compounds may downregulate the process of capillary formation. Rheumatoid arthritis as well as systemic lupus erythematosus, scleroderma, the antiphospholipid syndrome, and systemic vasculitides have been associated with accelerated atherosclerosis and high cardiovascular risk leading to increased mortality. Apart from traditional risk factors such as smoking, obesity, hypertension, dyslipidemia, and diabetes, inflammatory risk factors, including C-reactive protein, homocysteine, folate deficiency, lipoprotein (a), anti-phospholipid antibodies, antibodies to oxidized low-density lipoprotein, and heat shock proteins, are all involved in atherosclerosis underlying inflammatory rheumatic diseases. Targeting of adhesion molecules, chemokines, and angiogenesis by administering nonspecific immunosuppressive drugs as well as monoclonal antibodies or small molecular compounds inhibiting the action of a single mediator may control inflammation and prevent tissue destruction. Vasoprotective agents may help to prevent premature atherosclerosis and cardiovascular disease.

Synoviocyte stimulation by the LFA-1-intercellular adhesion molecule-2-Ezrin-Akt pathway in rheumatoid arthritis

In rheumatoid arthritis (RA), the synovium is infiltrated by mononuclear cells that influence the proliferation and activation of fibroblast-like synoviocytes (FLS) through soluble mediators as well as cell-to-cell contact. To identify receptor-ligand pairs involved in this cross-talk, we cocultured T cells with FLS lines isolated from synovial tissues from RA patients. Coculture with T cells induced phosphorylation of Akt (Ser(473)) and its downstream mediators, GSK-3alpha/GSK-beta, FoxO1/3a, and mouse double minute-2, and enhanced FLS proliferation. T cell-mediated phospho-Akt up-regulation was unique for FLS as no such effect was observed upon interaction of T cells with dendritic cells and B cells. Akt activation was induced by all functional T cell subsets independent of MHC/Ag recognition and was also found with other leukocyte populations, suggesting the involvement of a common leukocyte cell surface molecule. Akt phosphorylation, enhanced in vitro FLS proliferation, and enhanced FLS IL-6 production was inhibited by blocking Abs to CD11a and ICAM-2 whereas Abs to ICAM-1 had a lesser effect. Selective involvement of the LFA-1-ICAM-2 pathway was confirmed by the finding of increased ezrin phosphorylation at Tyr(353) that is known to be downstream of ICAM-2 and supports cell survival through Akt activation. CD28(-) T cells, which are overrepresented in RA patients, have high CD11a cell surface expression and induce Akt phosphorylation in FLS more potently than their CD28(+) counterparts. These findings identify ICAM-2 as a potential therapeutic target to inhibit FLS activation in RA, allowing for a more selective intervention than broad LFA-1 inhibition.