Normal Synovium Research Articles

VISTA deficiency attenuates antibody-induced arthritis and alters macrophage gene expression in response to simulated immune complexes

BackgroundIn addition to activated T cells, the immune checkpoint inhibitor “V domain-containing Ig suppressor of T-cell activation” (VISTA) is expressed by myeloid cell types, including macrophages and neutrophils. The importance of VISTA expression by myeloid cells to antibody-induced arthritis and its potential for relevance in human disease was evaluated.MethodsVISTA was immunolocalized in normal and arthritic human synovial tissue sections and synovial tissue lysates were subjected to western blot analysis. The collagen antibody-induced arthritis model (CAIA) was performed with DBA/1 J mice treated with antibodies against VISTA and with VISTA-deficient mice (V-KO). Total mRNA from arthritic joints, spleens, and cultured macrophages was analyzed with NanoString arrays. Cytokines secreted by splenic inflammatory macrophages were determined. In-vitro chemotaxis and signal transduction assays were performed with cultured macrophages.ResultsVISTA protein was localized to synovial membrane cells, neutrophils, and scattered cells in lymphocyte-rich foci and was detected by western blot analysis in normal synovium and synovium from rheumatoid arthritis patients. Deficiency of VISTA or treatment of mice with anti-VISTA monoclonal antibodies attenuated CAIA. Joint damage and MMP-3 expression were significantly reduced in V-KO mice. Surface expression of C5a receptor was reduced on monocytes, neutrophils, and cultured macrophages from V-KO. Upon Fc receptor engagement in vitro, gene expression by V-KO macrophages was altered profoundly compared to WT, including a significant induction of IL-1 receptor antagonist (IL1rn).ConclusionsVISTA expression supports immune-complex inflammation in CAIA and VISTA is expressed in human synovium. VISTA supports optimal responses to C5a and modulates macrophage responses to immune complexes.

Differential Effects of Activated Protein C on Synovial Fibroblasts in Response to Hypoxia and Normoxia

Rheumatoid arthritis (RA) is a chronic disease characterized by inflammation of the joints and their lining or synovium. Previous studies showed that the synovium in RA patients is more hypoxic than normal synovium. Activated protein C (APC) has anticoagulant and anti-inflammatory effects and is highly expressed in the joints of RA patients. We examined the effect of APC on RA and normal synovial fibroblasts under hypoxic conditions. Human synovial fibroblasts were isolated from the synovial tissues of RA patients and normal controls and cells were exposed to recombinant APC under normoxic (21% oxygen) or hypoxic (1% oxygen) conditions. Cell proliferation was measured using MTT assays. Cell lysates and conditioned media were collected and assayed for matrix metalloproteinase (MMP)-2, MMP-9 and p38 using zymography and western blots. Proliferation of both normal and RA synovial fibroblasts dose-dependently increased after APC treatment in normoxic conditions. Under hypoxia, APC enhanced RA cell proliferation but had no effect on normal fibroblasts. MMP-2 production and activation were significantly augmented by APC in both cell types under normoxia and hypoxia conditions. However, activated MMP-2 was more reduced in cells under hypoxia than normoxia. APC substantially reduced the phosphorylation of p38 in normal and RA synovial fibroblasts under hypoxia. No difference in p38 phosphorylation was observed under normoxia. The receptor for APC, endothelial protein C receptor (EPCR), was elevated in normal fibroblasts under hypoxic conditions whereas in RA cells, EPCR was highly expressed under both normoxic and hypoxic conditions. We found that hypoxia enhanced the effect of APC on RA synovial fibroblasts through activation of MMP2 and inhibition of p38 phosphorylation. Our results suggested that APC may suppress joint destruction and progression of inflammation in a hypoxic RA environment.

Contrast-enhanced MRI findings of the knee in healthy children; establishing normal values

ObjectivesTo define normative standards for the knee in healthy children using contrast-enhanced MRI, focusing on normal synovial membrane thickness. Secondly, presence of joint fluid and bone marrow oedema was evaluated.MethodsFor this study, children without disorders potentially resulting in (accompanying) arthritis were included. Patients underwent clinical assessments, followed by contrast-enhanced MRI. MRI features were evaluated in consensus using the Juvenile Arthritis MRI Scoring (JAMRIS) system. Additionally, the presence of joint fluid was evaluated. No cartilage lesions or bone abnormalities were observed.ResultsWe included 57 healthy children. The overall mean thickness of the normal synovial membrane was 0.4 mm (min–max; 0.0–1.8mm). The synovium was thickest around the cruciate ligaments and retropatellar and suprapatellar regions. The mean overall diameter of the largest pocket of joint fluid was 2.8 mm (min–max; 0.9–8.0mm). Bone marrow changes were observed in three children (all in the apex patellae).ConclusionsThe normal synovial membrane was maximally 1.8 mm thick, indicating that the JAMRIS cut-off value of 2 mm can be considered a valid measure for evaluating synovial hypertrophy. Some joint fluid and bone marrow changes suggestive of bone marrow oedema in the apex patellae can be seen in healthy children.Key Points• Knowledge on the normal synovial appearance using contrast-enhanced MR is lacking.• In healthy children, normal synovial membrane is maximally 1.8 mm thick.• Normal synovium is thickest around the cruciate ligaments, retropatellar and suprapatellar.• Bone marrow oedema in the apex patellae is seen in healthy children.

Triple DMARD treatment in early rheumatoid arthritis modulates synovial T cell activation and plasmablast/plasma cell differentiation pathways.

ObjectivesThis study sought to investigate the genome-wide transcriptional effects of a combination of disease modifying anti-rheumatic drugs (tDMARD; methotrexate, sulfasalazine and hydroxychloroquine) in synovial tissues obtained from early rheumatoid arthritis (RA) patients. While combination DMARD strategies have been investigated for clinical efficacy, very little data exists on the potential molecular mechanism of action. We hypothesized that tDMARD would impact multiple biological pathways, but the specific pathways were unknown.MethodsPaired synovial biopsy samples from early RA patients before and after 6 months of tDMARD therapy were collected by arthroscopy (n = 19). These biopsies as well as those from subjects with normal synovium (n = 28) were profiled by total RNA sequencing.ResultsLarge differences in gene expression between RA and control biopsies (over 5000 genes) were identified. Despite clinical efficacy, the expression of a restricted set of less than 300 genes was reversed after 6 months of treatment. Many genes remained elevated, even in patients who achieved low disease activity. Interestingly, tDMARD downregulated genes included those involved in T cell activation and signaling and plasmablast/plasma cell differentiation and function.ConclusionsWe have identified transcriptomic signatures that characterize synovial tissue from RA patients with early disease. Analysis after 6 months of tDMARD treatment highlight consistent alterations in expression of genes related to T cell activation and plasmablast/plasma cell differentiation. These results provide novel insight into the biology of early RA and the mechanism of tDMARD action and may help identify novel drug targets to improve rates of treatment-induced disease remission.

Protective Effect of Normal Synovium on Damaged Cartilage

Objectives:Traumatic joint injury results in an acute inflammatory response. If uncontrolled, this can progress to chronic inflammation, which can expedite the onset of post-traumatic osteoarthritis (PTOA). Normal synovium plays an important protective role for cartilage, while inflamed synovium can lead to degenerative changes. Previous studies have investigated the cartilage-synovium in limited conditions, but the effect of normal synovium on damaged cartilage remains unknown. The purpose of this study is to investigate the effect of normal synovium on two types of damaged cartilage: IL-1β or impaction-induced.Methods:Fresh human tali and distal femoral condyles were obtained from 7 human donors (mean age; 39 years-old, 4 male and 3 female) with no history of joint disease. Gross morphology was assessed using Collins grading 0-4 and only normal joints of grade 0-1 were used. Two damage models were introduced: 1) treatment with IL-1β (10ng/ml) at 48 hours before co-culture; or 2) controlled mechanical impaction (600 N within 2 ms). Cartilage explants (8mm) and grossly normal synovium (8 mm) from both joints were harvested and randomized to one of six treatment groups (n = 5 in each group): non-treated cartilage without or with synovium (Group 1 or 2), IL-1β-treated cartilage without or with synovium (Group 3 or 4), impacted cartilage without or with synovium (Group 5 or 6). Samples were collected at 0, 2, and 14 days and assessed for the percentage of live cells and histology with Safranin O staining. Cell survival was measured using calcein AM and ethidium bromide homodimer-1. Image analysis was performed on the superficial and middle/deep zone. Live cells were counted using Image J. Histological grading was based on modified Mankin score. The level of significance for all analysis was set at P < .05.Results:The percentage of live cells in Group 1 was mostly unchanged, 79.9 - 87.9% in the superficial layer and >90% in the middle/deep layer with no significant differences between Group 1 and 2 (Figure 1). All damaged cartilage displayed elevated cell death, especially in the superficial layer at all time points (Group 3; 56.4 ± 20.0%, 44.5 ± 11.5%, and 57.6 ± 16.3%, Group 5; 14.8 ± 5.3, 12.8 ± 13.2%, and 20.1 ± 4.1%, respectively). In the presence of synovium, chondrocyte survival significantly increased at 2 and 14 days (Group 4; 75.3 ± 4.7% and 77.8 ± 7.8%, P < 0.01 and 0.02, Group 6; 31.8 ± 13.7% and 33.4 ± 14.3%, P = 0.03 and 0.04, respectively). By contrast, the percentage of cells in the middle/deep layer remained unchanged for both damaged cartilage with or without synovium. For histological analysis, non-treated cartilage (Group 1 and 2) had a normal structure through 14 days. Mankin score progressively increased in damaged cartilage (Group 3; 1.0 ± 1.41, 2.2 ± 1.8, and 3.25 ± 1.64, Group 5; 3.0 ± 1.2, 3.6 ± 1.1, and 4.6 ± 0.5 at 0, 2, and 14 days). In the presence of synovium, Mankin score decreased at 2 and 14 days (Group 4; 0.8 ± 1.3, and 0.8 ± 0.8, P = 0.087 and < 0.01, Group 6; 1.0 ± 0.0 and 1.6 ± 0.5, P =0.02 and < 0.01, respectively).Conclusion:These results demonstrate that healthy synovium is protective of damaged cartilage as evidenced by increased cell viability, especially in the superficial layer. These findings suggested that the inhibition of inflammation by normal synovium may lead to both the recovery of damaged cartilage and prevention of PTOA. In the future, the underlying mechanism responsible for the interaction between the normal synovium and damaged cartilage needs to be addressed.

Enumeration and Localization of Mesenchymal Progenitor Cells and Macrophages in Synovium from Normal Individuals and Patients with Pre-Osteoarthritis or Clinically Diagnosed Osteoarthritis.

Osteoarthritis (OA) is a degenerative disorder characterized by chondrocyte apoptosis and degeneration of articular cartilage resulting in loss of mobility and pain. Inflammation plays a key role in the development and progression of OA both on the side of apoptosis and repair, while its exact role in pathogenesis has yet to be fully elucidated. Few studies have examined the cellular composition (inflammatory cells and/or progenitor cells) in the synovium of patients with pre-OA (asymptomatic with cartilage damage). Therefore, in the current study, mesenchymal progenitor cells (MPCs) and macrophages were enumerated within normal, pre-OA and OA synovium. No differences were observed between MPCs in normal vs. pre-OA, however, fewer macrophages were observed in pre-OA vs. normal synovium. Osteoarthritic synovium contained greater numbers of both MPCs and macrophages. Interestingly, the localization of MPCs and macrophages was affected by disease severity. In normal and pre-OA synovium, MPCs and macrophages co-localized, while in OA synovium, MPCs and macrophage populations were spatially distinct. Examining the cellular interactions between MPCs and macrophages in synovium may be essential for understanding the role of these cells in the onset and/or pathogenesis of the disease. This study has provided a first step by examining these cell types both spatially and temporally (e.g., disease severity). Further cellular and molecular studies will be needed to determine the functions of these cells in the context of disease and in relation to each other and the joint as a whole.

Collagen triple helix repeat containing 1 is a new promigratory marker of arthritic pannus.

BackgroundThe formation of destructive hypercellular pannus is critical to joint damage in rheumatoid arthritis (RA). The collagen triple helix repeat containing 1 (CTHRC1) protein expressed by activated stromal cells of diverse origin has previously been implicated in tissue remodeling and carcinogenesis. We recently discovered that the synovial Cthrc1 mRNA directly correlates with arthritis severity in mice. This study characterizes the role of CTHRC1 in arthritic pannus formation.MethodsSynovial joints of mice with collagen antibody-induced arthritis (CAIA) and human RA-fibroblast-like synoviocytes (FLS) were immunostained for CTHRC1, FLS and macrophage-specific markers. CTHRC1 levels in plasma from patients with RA were measured using sandwich ELISA. The migratory response of fibroblasts was studied with a transwell migration assay and time-lapse microscopy. Velocity and directness of cell migration was analyzed by recording the trajectories of cells treated with rhCTHRC1.ResultsImmunohistochemical analysis of normal and inflamed synovium revealed highly inducible expression of CTHRC1 in arthritis (10.9-fold). At the tissue level, CTHRC1-expressing cells occupied the same niche as large fibroblast-like cells positive for α-smooth muscle actin (α-SMA) and cadherin 11 (CDH11). CTHRC1 was produced by activated FLS predominantly located at the synovial intimal lining and at the bone-pannus interface. Cultured RA-FLS expressed CDH11, α-SMA, and CTHRC1. Upon treatment with exogenous rhCTHRC1, embryonic fibroblasts and RA-FLS significantly increased migration velocity, directness, and cell length along the front-tail axis (1.4-fold, p < 0.01).ConclusionCTHRC1 was established as a novel marker of activated synoviocytes in murine experimental arthritis and RA. The pro-migratory effect of CTHRC1 on synoviocytes is considered one of the mechanisms promoting hypercellularity of the arthritic pannus.Electronic supplementary materialThe online version of this article (doi:10.1186/s13075-016-1067-1) contains supplementary material, which is available to authorized users.

Bone marrow contribution to synovial hyperplasia following joint surface injury.

BackgroundJoint surface injury, a known risk factor for osteoarthritis, triggers synovial hyperplasia, which involves proliferation of mesenchymal stromal/stem cells (MSCs). Whether these proliferative MSCs are resident synovial cells or move into the tissue from elsewhere is not known. The aim of this study was to determine the contribution of bone marrow-derived cells to synovial hyperplasia following joint surface injury.MethodsLethally irradiated mice were transplanted with green fluorescent protein (GFP)-labelled bone marrow, and MSC chimerism was determined by the colony-forming unit fibroblast (CFU-F) assay and phenotypic analysis. To label host slow-cycling cells prior to bone marrow transplant, mice received iododeoxyuridine for 3 weeks. Mice then were subjected to GFP+ bone marrow transplant, underwent joint surface injury and received chlorodeoxyuridine (CldU) for 7 days to label cells proliferating after injury. GFP- and nucleoside-labelled cells in normal and injured knee joint synovium were quantified in situ by immunofluorescence staining of paraffin-embedded tissue sections. The phenotype of GFP-labelled cells was determined by co-staining for the haematopoietic marker CD16/CD32 and the MSC/fibroblast marker platelet-derived growth factor receptor α (Pdgfrα).ResultsCFU-F assay and phenotypic analysis demonstrated successful bone marrow mesenchymal lineage chimerism in mice that underwent transplants. Bone marrow reconstitution preceded the detection of GFP-labelled cells in synovium. The percentage of GFP+ cells in synovium increased significantly in response to injury, while the proportion of GFP+ cells that were labelled with the proliferation marker CldU did not increase, suggesting that the expansion of the GFP+ cell population in synovium was due mainly to bone marrow cell infiltration. In contrast, proliferation of host slow-cycling cells was significantly increased in the hyperplastic synovium. In both control and injured knee joints, the majority of marrow-derived GFP+ cells in the synovium were haematopoietic (CD16/32+), while a minority of cells expressed the pan-fibroblast/MSC marker Pdgfrα.ConclusionsOur findings indicate that synovial hyperplasia following joint surface injury involves proliferation of resident slow-cycling cells, with a contribution from infiltrating bone marrow-derived cells. Understanding the process of synovial hyperplasia may reveal ways to restore homeostasis in injured joints and prevent secondary osteoarthritis.

Ultrasound-guided synovial biopsy.

Ultrasound-guided needle biopsy of synovium is an increasingly performed procedure with a high diagnostic yield. In this review, we discuss the normal synovium, as well as the indications, technique, tissue handling and clinical applications of ultrasound-guided synovial biopsy.

Multi-lineage differentiation and angiogenesis potentials of pigmented villonodular synovitis derived mesenchymal stem cells--pathological implication.

Pigmented villonodular synovitis (PVNS) is a benign tissue proliferation characterized by its hyper-vascularity within the lesion. The true etiology and cell source of this disease entity still remain unclear. Mesenchymal stem cells (MSCs) exist in various tissues of human body. However, it has not been clarified whether MSCs could be isolated from tissue of PVNS. Here, we isolated MSCs from PVNS (PVNS-SCs), and by comparing to the MSCs from normal synovium (Syn-SCs) of the same individual, we investigated whether PVNS-SCs differed in the capacity for multi-differentiation and inducing angiogenesis. We first demonstrated that PVNS-SCs existed in the lesion of PVNS of three individuals. Moreover, we showed PVNS-SCs had better osteogenic differentiation potential than Syn-SCs, whereas Syn-SCs had better capacity for adipogenic and chondrogenic differentiation. By genome-wide analysis of gene expression profile using a complementary DNA microarray and comparing to Syn-SCs, we identified in PVNS-SCs a distinct gene expression profile characterized by up-regulation of genes involved in angiogenesis. In vitro and in vivo studies further confirmed that PVNS-SCs had better capacities for promoting angiogenesis. In summary, the identification of PVNS-SCs in PVNS tissue and their distinct angiogenic potential may help elucidate the underlying etiology of this disease.

Alteration of the RANKL/RANK/OPG System in Periprosthetic Osteolysis with Septic Loosening.

The pathogenesis of periprosthetic osteolysis with septic loosening remains incompletely understood. The purpose of this study was to investigate whether expression of the RANKL/RANK/OPG system is altered in septic interface membranes (SIMs). Seventeen cases with a SIM, 26 cases with an aseptic interface membrane (AIM), and 12 cases with a normal synovium (NS) were assessed. Scanning and transmission electron microscopy (SEM and TEM, respectively) were used to observe the microscopic morphology of three tissue conditions. Differences in RANKL, RANK, and OPG expression at the mRNA level were assessed by real-time quantitative PCR, and differences at the protein level were assessed by immunohistochemical staining and Western blotting. SEM showed wear debris widely distributed on the AIM surface, and TEM showed Bacillus activity in the SIM. RANKL expression and the RANKL/OPG ratio were significantly increased in SIMs. Imbalance in the RANKL/RANK/OPG system is related to periprosthetic osteolysis with septic loosening but is not the only possible pathogenic mechanism.

Effects over time of two platelet gel supernatants on growth factor, cytokine and hyaluronan concentrations in normal synovial membrane explants challenged with lipopolysaccharide.

BackgroundPlatelet-rich plasma (PRP) preparations are a common treatment in osteoarthritis (OA) and inflammatory synovitis. However, there is ambiguity regarding the ideal concentration of leukocytes and platelets in these preparations necessary to induce an adequate anti-inflammatory and anabolic response in joint tissues, such as the synovial membrane. This research aimed to study, in normal synovial membrane explants (SME) challenged with lipopolysaccharide (LPS), the temporal effects (at 48 and 96h) of leukocyte- and platelet-rich gel (L-PRG) and pure platelet-rich gel (P-PRG) supernatants on the production and degradation of platelet associated growth factors (GF) (platelet derived GF isoform BB (PDGF-BB) and transforming growth factor beta-1 (TGF-β1)), pro-inflammatory (tumour necrosis factor alpha (TNF-α)) and anti-inflammatory cytokines (interleukin 4 (IL-4) and IL-1 receptor antagonists (IL-1ra)) and hyaluronan (HA).MethodsSynovial membrane explants (SMEs) from 6 horses were challenged with LPS and cultured for 96h with L-PRG and P-PRG supernatants at concentrations of 25 and 50 %, respectively. The SME culture medium was changed every 48h and used for determination by ELISA of PDGF-BB, TGF-β1, TNF-α, IL-4, IL-1ra and HA. These molecules were also determined in synovial fluid from the horses.ResultsBoth the 25 and 50 % PRG supernatants produced a molecular profile in the culture media unlike that of the SME challenged with LPS only. They presented GF, cytokine and HA concentrations very near to the concentrations of these molecules in normal synovial fluid when compared with the SME control groups (either with LPS or without LPS). However, in comparison with the rest of the SME treated groups, the 25 % L-PRG produced the most IL-1ra, and the 50 % P-PRG induced the sustained production of IL-4 and HA.ConclusionsThese in vitro findings suggest that anabolic and anti-inflammatory joint responses depend on the leukocyte and platelet concentration of the PRP preparation and on the volume of this substance injected. Moreover, it is possible, that leukoreduced PRP preparations are more effective for the medical treatment of patients with OA and inflammatory synovitis.

15-hydroxyprostaglandin dehydrogenase is upregulated by hydroxychloroquine in rheumatoid arthritis fibroblast-like synoviocytes.

15-Hydroxyprostaglandin dehydrogenase (HPGD) is the key enzyme responsible for the metabolic inactivation of prostaglandin E2 (PGE2) catabolism. PGE2 is one of the predominant catabolic factors involved in rheumatoid arthritis (RA). However, the expression and regulation of HPGD in RA fibroblast-like synoviocyte (FLS) remain to be elucidated. Disease-modifying anti-rheumatic drugs (DMARDs) are the most important anti-arthritic drugs, which reduce the effect of joint injury. The aim of the present study was to assess the expression of HPGD in RA tissues and cells, and normal synovial tissues and cells. The effect of the most popular DMARDs, hydroxychloroquine, on the expression of HPGD in RA-FLS was also investigated. Western blotting and immuno-histochemical analysis demonstrated that the expression levels of HPGD in human synovium were lower in RA synovium compared with the normal and OA synovium. In RA-FLS, the expression of HPGD was increased following treatment with several DMARDs, including sulfasalazine, methotrexate, and hydroxychloroquine. Hydroxychloroquine (10 µM) treatment induced the phosphorylation of ERK, SAPK/JNK and p38. Hydroxychloroquine induced a decrease in the release of PGE2, which was restored by mitogen-activated protein (MAP) kinase pathway inhibitors. Hydroxychloroquine may therefore, affect the pathogenesis of RA through the MAP kinase pathway by regulating the expression of HPGD.

Articular ankle fracture results in increased synovitis, synovial macrophage infiltration, and synovial fluid concentrations of inflammatory cytokines and chemokines.

The inflammatory response following an articular fracture is thought to play a role in the development of posttraumatic arthritis (PTA) but has not been well characterized. The objective of this study was to characterize the acute inflammatory response, both locally and systemically, in joint synovium, synovial fluid (SF), and serum following articular fracture of the ankle. We hypothesized that intraarticular fracture would alter the synovial environment and lead to increased local and systemic inflammation. Synovial tissue biopsy specimens, SF samples, and serum samples were collected from patients with an acute articular ankle fracture (n = 6). Additional samples (normal, ankle osteoarthritis [OA], and knee OA [n = 6 per group]) were included for comparative analyses. Synovial tissue was assessed for synovitis and macrophage count. SF and serum were assessed for cytokines (interferon-γ [IFNγ], interleukin-1β [IL-1β], IL-6, IL-8, IL-10, IL-12p70, and tumor necrosis factor α) and chemokines (eotaxin, eotaxin 3, IFNγ-inducible 10-kd protein, monocyte chemotactic protein 1 [MCP-1], MCP-4, macrophage-derived chemokine, macrophage inflammatory protein 1β, and thymus and activation-regulated chemokine). Synovitis scores were significantly higher in ankle fracture tissue compared with normal ankle tissue (P = 0.007), and there was a trend toward an increased abundance of CD68+ macrophages in ankle fracture synovium compared with normal knee synovium (P = 0.06). The concentrations of all cytokines and chemokines were elevated in the SF of patients with ankle fracture compared with those in SF from OA patients with no history of trauma. Only the concentration of IL-6 was significantly increased in the serum of patients with ankle fracture compared with normal serum (P = 0.027). Articular fracture of the ankle increased acute local inflammation, as indicated by increased synovitis, increased macrophage infiltration into synovial tissue, and increased SF concentrations of biomarkers of inflammation. Characterizing the acute response to articular fracture provides insight into the healing process and may help to identify patients who may be at greater risk of PTA.

Platelet-Rich Gel Supernatants Stimulate the Release of Anti-Inflammatory Proteins on Culture Media of Normal Equine Synovial Membrane Explants.

The aims were as follows: (1) to evaluate the effects at 48 and 96 h of two concentrations (25 and 50%) of leukocyte and platelet-rich gel (L-PRG) and pure PRG (P-PRG) supernatants on the production/degradation in normal equine synovial membrane explants (SME) of platelet derived growth factor isoform BB, transforming growth factor beta-1, tumor necrosis factor alpha, interleukin (IL-) 4 (IL-4), IL-1 receptor antagonist (IL-1ra), and hyaluronan (HA) synthesis and (2) to correlate these molecules with their respective PRG supernatant treatments. SME from 6 horses were cultured for 96 h with L-PRG and P-PRG supernatants at 25 and 50% concentrations, respectively. SME culture media were changed each 48 h and used for determination by ELISA of the molecules, which were also determined in synovial fluid. 25% L-PRG supernatant produced a sustained release over time of IL-1ra and a gradual release of HA, whereas 50% L-PRG supernatant produced a sustained increase over time of IL-4 and HA. 50% P-PRG supernatant produced an increased and sustained production of IL-1ra and IL-4. The cellular composition and the articular concentration (volume) of a platelet-rich plasma preparation could affect the anti-inflammatory and anabolic joint responses in horses with osteoarthritis.

AB0093 Angiopoietin-Like 4 is Over–Expressed in Rheumatoid Arthritis: A Potential Role in Pathological Bone Resorption

BackgroundIn contrast to normal synovial tissue, rheumatoid synovium is hypoxic, and expresses the hypoxia-inducible transcription factors HIF-1α and HIF-2α, which allow the transcription of genes involved in angiogenesis, inflammation, apoptosis...

Manual labor occupations increase the short-term incidence of knee osteoarthritis in japanese, but not caucasian subjects

s / Osteoarthritis and Cartilage 22 (2014) S57–S489 S398 matrix remodeling process induced by an inflammatory microenvironment suggested by the presence of synovial hypervascularization. Figure 1. Prolidase protein expression: A) Hipertrophy synovial of patient with OA B) Normal synovium 710 MANUAL LABOR OCCUPATIONS INCREASE THE SHORT-TERM INCIDENCE OF KNEE OSTEOARTHRITIS IN JAPANESE, BUT NOT CAUCASIAN SUBJECTS K.M. Leyland y, M.T. Sanchez-Santos y, S. Muraki z, A. Judge y, T.D. Spector x, D.J. Hart x, J. Newton y, C. Cooper ky, N. Yoshimura z, N.K. Arden yk. yUniv. of Oxford, Oxford, United Kingdom; zUniv. of Tokyo, Tokyo, Japan; x St. Thomas’ Hosp., London, United Kingdom; kUniv. of Southampton, Southampton, United Kingdom Purpose: To determine the interacting role of occupation and obesity on the risk of incident knee osteoarthritis (OA) among Caucasian and Japanese women. Methods: We used data from women in two prospective communitybased cohorts, the UK based Chingford study and the Japanese Research on Osteoarthritis/osteoporosis Against Disability (ROAD) study. Incident radiographic knee osteoarthritis (RKOA) was defined as having Kellgren and Lawrence (K/L) grade 0 or 1 in both knees at baseline and a K/L grade 2 or greater at follow up. Follow-up x-rays were taken after a median of 4 years after baseline for Chingford and 3 years in ROAD. The cut-off for a normal BMI was 25 kg/m2 for the Caucasian subjects and 23 kg/m2 for the Japanese subjects. Occupation was divided into manual versus non-manual (i.e. sedentary/moderate activity) for both populations based on self-assessment. Multivariable logistic regression models assessed of risk of obesity, occupation and their interaction on incident RKOA, controlling for age, hand grip strength, walking distance, smoking and alcohol intake. Results: 12.4% of Caucasian and 14.5% of Japanese women developed incident RKOA in at least one knee. Being overweight/obese was associated with an increased risk of incident RKOA in both populations (Caucasian OR 1.7 [95% CI 1.0, 2.8]; Japanese OR 2.5 [95% CI 1.3, 4.9]), however having a manual labour occupation was only significantly associated with incident RKOA in the Japanese subjects (OR 2.8 [95% CI 1.3, 5.8]). No significant interaction between BMI category and occupation was found for either population (Chingford p1⁄40.070; ROAD p1⁄40.291), however the Japanese population showed a slight increase in risk for manual labour occupations in the overweight/obese category Table 1 Profile of Participants by presence or absence of back pain

The Effect of Platelet-Rich Plasma Formulations and Blood Products on Human Synoviocytes

Background: The effect of platelet-rich plasma (PRP) on chondrocytes has been studied in cell and tissue culture, but considerably less attention has been given to the effect of PRP on synoviocytes. Fibroblast-like synoviocytes (FLS) compose 80% of the normal human synovium and produce cytokines and matrix metalloproteinases that can mediate cartilage catabolism. Purpose: To compare the effects of leukocyte-rich PRP (LR-PRP), leukocyte-poor PRP (LP-PRP), red blood cell (RBC) concentrate, and platelet-poor plasma (PPP) on human FLS to determine whether leukocyte and erythrocyte concentrations of PRP formulations differentially affect the production of inflammatory mediators. Study Design: Controlled laboratory study. Methods: Peripheral blood was obtained from 4 donors and processed to create LR-PRP, LP-PRP, RBCs, and PPP. Human synoviocytes were cultured for 96 hours with the respective experimental conditions using standard laboratory conditions. Cell viability and inflammatory mediator production were then evaluated. Results: Treatment with LR-PRP resulted in significantly greater synoviocyte death (4.9% ± 3.1%) compared with LP-PRP (0.72% ± 0.70%; P = .035), phosphate-buffered saline (PBS) (0.39% ± 0.27%; P = .018), and PPP (0.26% ± 0.30%; P = .013). Synoviocytes treated with RBC concentrate demonstrated significantly greater cell death (12.5% ± 6.9%) compared with PBS (P < .001), PPP (P < .001), LP-PRP (P < .001), and LR-PRP (4.9% ± 3.1%; P < .001). Interleukin (IL)–1β content was significantly higher in cultures treated with LR-PRP (1.53 ± 0.86 pg/mL) compared with those treated with PBS (0.22 ± 0.295 pg/mL; P < .001), PPP (0.11 ± 0.179 pg/mL; P < .001), and RBCs (0.64 ± 0.58 pg/mL; P = .001). IL-6 content was also higher with LR-PRP (32,097.82 ± 22,844.300 pg/mL) treatment in all other groups (P < .001). Tumor necrosis factor–α levels were greatest in LP-PRP (9.97 ± 3.110 pg/mL), and this was significantly greater compared with all other culture conditions (P < .001). Interferon-γ levels were greatest in RBCs (64.34 ± 22.987 pg/mL) and significantly greater than all other culture conditions (P < .001). Conclusion: Treatment of synovial cells with LR-PRP and RBCs resulted in significant cell death and proinflammatory mediator production. Clinical Relevance: Clinicians should consider using leukocyte-poor, RBC-free formulations of PRP when administering intra-articularly.

Normal sheep synovium has similar appearances and constitutive expression of inflammatory cytokines within and between knee joints: a baseline histological and molecular analysis

Clinical evidence suggests that synovium can add to adjacent articular cartilage damage, potentially contributing to the development of osteoarthritis (OA). Inflammation of the synovium (synovitis) is dependent on the type of injury sustained, the time after injury and concomitant changes in other joint tissues. To define the role of synovitis in OA development, there is a need for baseline measures that can reliably distinguish synovial inflammation from normal synovium both within and between joints. This study tested the hypothesis that normal synovium from distinct anatomical locations in young and adult sheep is homogeneous with respect to consistently low molecular expression of the inflammatory mediators – tumour necrosis factor alpha (TNF-α) and interleukins (IL) such as IL-1β, IL-1Ra, IL-6 and IL-8. Additionally, maturation will not influence the expression of these select inflammatory biomarkers. Samples of synovium from four anatomic locations (medial and lateral margins, suprapatellar pouch (patella region), posterior to the posterior cruciate ligament, from each joint of 5 adult and 4 immature animals were graded histologically or analyzed for mRNA expression of inflammatory cytokines. Histologically, no evidence of synovitis was noted although some variance in sub-intimal fibrosis was observed between sample locations in mature sheep. Molecular expression of all inflammatory mediators was low and homogeneously expressed at constitutive levels in all sample locations. These findings confirm the hypothesis that the normal sheep synovium is a homogeneous tissue throughout the joint and establishes the baseline expression levels for several pro-inflammatory mediators in both immature and mature sheep.

Expression and significance of MMP3 in synovium of knee joint at different stage in osteoarthritis patients

ObjectiveTo investigate the expression and significance of MMP-3 in synovium of knee joint at different stage in osteoarthritis (OA) patients. MethodsKnee synovial tissue were collected in 90 OA patients (the OA group). Patients in the OA group was divided into 3 subgroups: grade I subgroup (n=30), grade II subgroup (n=30), grade III; subgroup (n=30). Thirty patients served as control group. Immunohistochemical assay was used to detect the expression of MMP-3 protein in the knee synovial tissue. ResultsMMP-3 protein was detected in all knee synovial tissue. The expression of MMP-3 protein in the OA group was significantly higher that in the normal synovium (P<0.05), and the MMP-3 protein was mainly located in the cytoplasm. There was significant difference in the expression of MMP-3 protein between the grade I subgroup and the grade II, grade III subgroups (all P<0.05). The expression of MMP-3 protein was positively related to the severity of OA (r=0.912, P<0.05). ConclusionsThe expression of MMP-3 protein are closely related to pathogenic mechanism of OA. It may be an important indicator of early diagnosis and the activity of the disease of osteoarthritis.