Synovitis in rheumatoid arthritis: scoring of characteristic histopathological features

Rhein methotrexate-decorated solid lipid nanoparticles altering adjuvant arthritis progression through endoplasmic reticulum stress-mediated apoptosis

Methotrexate (MTX) and diacerein (DIA) are two of the most potent disease-modifying anti-rheumatic drugs used for the treatment of rheumatoid arthritis (RA). DIA has reflected some GIT and hepatobiliary manifestations in numerous cases. It undergoes biotransformation in the liver into the active metabolite rhein (RH) which is characterized by its excellent anti-inflammatory activity and lower side effects. However, RH's hydrophobic nature and low bioavailability do not encourage its use in RA. The current study aims to use RH in combination with MTX in targeted solid lipid nanoparticles (RH-MTX-SLNs) for better effectiveness and shadowing light on its possible mechanistic pathways. RH-MTX-SLNs were prepared and assessed for their quality attributes. The effect of the formulation was assessed in-vivo in an adjuvant arthritis animal model investigating the role of the endoplasmic reticulum stress (ERS)-induced apoptosis. Results revealed that RH-MTX-SLNs were in the suitable nanosized range with high negative zeta potential indicating good stability. In-vivo, RH-MTX-SLNs significantly improved all measured inflammatory and arthritic markers, confirmed by electron microscopy and histology examination of the joints. Besides, the formulation was able to alter the ERS-mediated apoptosis. In conclusion, RH-MTX-SLNs can represent a promising therapeutic approach for RA showing significant anti-arthritic activity.

Is histopathological synovitis score a predictor of postoperative requirement for additional or alternative drug treatment in the patients with rheumatoid arthritis?

OBJECTIVES

Histopathological synovitis scoring is useful for assessing activity in patients with rheumatoid arthritis (RA) at sampling, but it is unclear whether it can be a predictor of future drug treatment. The purpose of this study was to examine whether histopathological synovitis score is a predictor of postoperative requirement for additional or alternative drug treatment after total knee arthroplasty (TKA).

METHODS

Thirty patients with RA in whom synovial samples were obtained during TKA were included. Patients were divided into the drug treatment enhanced group (EG), which included patients who needed additional or alternative drug treatment within 1 year after TKA, and the drug treatment maintenance group (MG). The Rooney synovitis score (RSS) was compared between groups. Logistic regression analysis was performed to clarify prognostic factors for postoperative drug treatment change.

RESULTS

The total RSS was significantly higher in the EG than in the MG (29.3 vs 15.1; P < .001). Multivariate analysis showed that total RSS and swollen joint counts were independent variable associated with postoperative requirement for additional or alternative drug treatment (P < .05).

CONCLUSIONS

Histopathological synovitis scoring may predict requirement for additional or alternative drug treatment in patients with RA after TKA.

Synergistic and receptor-mediated targeting of arthritic joints via intra-articular injectable smart hydrogels containing leflunomide-loaded lipid nanocarriers

Intra-articular drug delivery represents a tempting strategy for local treatment of rheumatoid arthritis. Targeting drugs to inflamed joints bypasses systemic-related side effects. Albeit, rapid drug clearance and short joint residence limit intra-articular administration. Herein, injectable smart hydrogels comprising free/nanoencapsulated leflunomide (LEF) were developed. Nanostructured lipid carriers (NLCs), 200-300 nm, were coated with either chondroitin sulfate (CHS), hyaluronic acid (HA), or chitosan (CS) to provide joint targetability. Coated NLCs were incorporated in either hyaluronic/pluronic (HP) or chitosan/β-glycerophosphate (CS/βGP) hydrogels. Optimized systems ensured convenient gelation time (14-100 s), injectability (5-15 s), formulation-dependent mechanical strength, and extended LEF release up to 51 days. In vivo intra-articular injection in induced arthritis rat model revealed that rats treated with HA-coated NLCs showed the fastest recovery. Histopathological examination demonstrated perfect joint healing in case of HA-coated LEF-NLCs in CS/βGP thermogel manifested as minor erosion of subchondral bone, improved intensity of extracellular matrix, cartilage thickness, and chondrocyte number. Both HA- and CHS-coated NLCs reduced TNF-α level 4-5-fold relative to positive control. The feat would be achieved via active targeting to CD44 receptors overexpressed in the articular tissue, limiting chondrocyte apoptosis together with innate synergistic targetability by promoting chondrocyte proliferation and neovascularization, inhibiting the production of pro-inflammatory cytokines, thus enhancing cartilaginous tissue repair.

On-demand treatment with the iron chelator deferasirox is ineffective in preventing blood-induced joint damage in haemophilic mice

INTRODUCTION

Early intervention in the devastating process of haemophilic arthropathy (HA) is highly desirable, but no disease-modifying therapy is currently available. Considering the pivotal role of iron in the development of HA, iron chelation is considered a promising therapeutic approach. A previous study in haemophilic mice demonstrated that treatment with the iron chelator deferasirox (DFX) 8 weeks before joint bleed induction, attenuated cartilage damage upon blood exposure. However, in haemophilia patients this approach is not opportune given the unpredictable occurrence of hemarthroses.

AIM

To evaluate the effectiveness of on-demand DFX treatment, initiated immediately after joint bleed induction.

METHODS

A joint bleed was induced in 66 factor VIII-deficient mice by infra-patellar needle puncture. Mice were randomly assigned to treatment with either placebo (drinking water) or DFX (dissolved in drinking water) throughout the study. Five weeks after joint bleed induction, inflammation and cartilage damage were assessed histologically. Joints of ten bleed naive haemophilic mice served as controls.

RESULTS

A joint bleed resulted in significant inflammation and cartilage damage in the blood-exposed joint compared with those of control animals, in both the placebo and DFX group (all p = <.05). No differences in tibiofemoral or patellar inflammation (p = .305 and p = .787, respectively) nor cartilage damage (p = .265 and p = .802, respectively) were found between the blood-exposed joints of both treatment groups.

CONCLUSION

On-demand treatment with DFX does not prevent joint damage following blood exposure in haemophilic mice. DFX seems unable to reach the joint in time to exert its effect before the irreversible harmful process is initiated.

Wutou decoction ameliorates experimental rheumatoid arthritis via regulating NF-kB and Nrf2: Integrating efficacy-oriented compatibility of traditional Chinese medicine

BACKGROUND

Thousands of years of clinical application of Wutou decoction (WTD) support its reliable efficacy and safety in treating rheumatoid arthritis (RA). However, the underlying molecular mechanism remains unclear, and the synergistic involvement of assistant herbs in WTD in enhancing the sovereign herb in treating RA is unknown.

PURPOSE

This study aimed to investigate the efficacy-oriented compatibility of five herbs in WTD and the underlying mechanisms.

METHODS

The anti-arthritic effects of WTD and the compatibilities of the five herbs in WTD were studied in vivo with adjuvant-induced arthritis (AIA) rat model and in vitro with LPS-induced RAW264.7 macrophage. Network pharmacology analysis was conducted to identify the dominant pathways involved in the anti-arthritis mechanisms of WTD and how the five herbs work synergistically. The results were further verified by in vivo and in vitro experiments.

RESULTS

Our data revealed that the five herbs in WTD exert synergistic anti-arthritic effects on RA. Moreover, Radix Aconite (AC) is the principal anti-inflammatory component in WTD according to the extent of therapeutic effects exerted on the AIA rats. In vivo and in vitro experiments demonstrated that WTD inhibited NF-κB phosphorylation and simultaneously increased the expression of Nrf2, which were the major pathways identified by the network pharmacology analysis. The major assistant component, Herba Ephedrae (EP), evidently inhibited NF-κB mediated inflammatory response. The other assistant component, Radix Astragali (AS), considerably enhanced the expression of Nrf2 when used alone or in combination with AC. These combinations improved the anti-arthritis effects on the AIA rats better than that of AC alone. Nevertheless, WTD always achieved the best effects than any combinations both in vivo and in vitro.

CONCLUSION

The ministerial herbs EP and AS intensify the anti-arthritic effects of AC by regulating the NF-κB-mediated inflammatory pathway and the Nrf2-mediated anti-oxidation pathway which are the major pathways of WTD for alleviating the symptoms of RA.

Intra-Articular Dual Drug Delivery for Synergistic Rheumatoid Arthritis Treatment

Systemic rheumatoid arthritis (RA) regimens fail to attain effective drug level at the affected joints and are associated with serious side effects. Herein, an attempt made to improve therapeutic outcomes of both leflunomide (LEF) which is a disease modifying antirheumatic and dexamethasone (Dex) through local delivery of combination therapy by intra-articular route. LEF and Dex were encapsulated in nanostructured lipid carriers (NLCs) and PLGA nanoparticles (NPs), respectively. Both nanocarriers were loaded into chitosan/β glycerophosphate (CS/βGP) thermo-sensitive hydrogels and injected intra-articularly in adjuvant induced RA rat model. Particle size of LEF NLCs and selected Dex NPs formulations were 200 and 119 nm, respectively. Dex NPs and LEF NLCs showed a sustained release profile for up to 58 and 17 days, respectively. After 14 days of treatment remarkable joint healing was observed for groups treated with Dex NPs in combination with either free LEF or LEF NLCs in CS/βGP hydrogel. Joint diameter measurements, TNF α levels and histopathological examination of dissected joints showed comparable values to the negative control group. This might be attributed to the synergistic effect of drug combination besides the ability of nanocarriers loaded hydrogel to prolong joint residence time and enhance joint healing potential.

Folic acid decorated chitosan-coated solid lipid nanoparticles for the oral treatment of rheumatoid arthritis

Background: Systemic treatment of rheumatoid arthritis has been accompanied with several side effects. This study attempts to reduce leflunomide systemic side effects besides increasing its joint healing outcomes via formulation of layer-by-layer coated, leflunomide-loaded solid lipid nanoparticles (SLNs). Methods: SLNs were coated with chitosan (CS) followed by folic acid (FA). FA-CS-SLNs were about 284.9 nm and carried negative surface charge. Results & conclusion: FA-CS-SLNs showed sustained release profile for 168 h. Results of oral administration of FA-CS-SLNs in rats with adjuvant-induced arthritis revealed improved joint healing and reduced hepatotoxicity compared with leflunomide suspension. This may be attributed to the ability of FA-CS-SLNs to actively target FA receptors that are overexpressed in inflamed rheumatic joints in addition to innate joint healing properties of CS.

Monoarticular synovitis of knee: dealing with the dilemma

Introduction: Chronic synovitis involving a single large joint remains a diagnostic dilemma. We present 61 cases of chronic synovitis of the knee, followed prospectively for 2 years. The study focuses on the diagnosis, management, and histopathological correlation. Methods: We prospectively studied 61 patients with chronic mono-articular synovitis of the knee joint, between July 2016 and September 2017. All patients underwent plain radiographs, magnetic resonance imaging, and arthroscopic examination with synovial biopsy. Further treatment was based on findings of histopathological examination. Results: The average duration of symptoms was 7.72 ± 4.34 months. The mean age at presentation was 29.93 ± 15.56 years. Results of histopathological examination showed chronic nonspecific inflammation in 28 patients (46%), features suggesting tubercular infection in 19 patients (31%), pigmented villonodular synovitis in seven patients (11.5%), rheumatoid arthritis in three (5%) patients, acute inflammation in three (5%) patients and findings suggestive of synovial chondromatosis in one (1.5%) patient. Treatment was based on histopathological results. Intra-articular injections of methylprednisolone (80 mg depot preparation) were given to all patients with nonspecific synovitis and rheumatoid arthritis. Anti-tubercular treatment was started for patients with tubercular synovitis. Complete arthroscopic/open synovectomy followed by radiotherapy was carried out for patients with pigmented villonodular synovitis. Non-steroidal anti-inflammatory drugs are used for patients with acute on chronic inflammation. All patients had symptomatic relief and functional improvement in further follow-up. Discussion: Histopathological reporting remains the mainstay for diagnosis. The various differentials should always be kept in mind when approaching patients with chronic mono-articular synovitis. Specific treatment can be started once the diagnosis is confirmed.

Chlamydia pecorum-Induced Arthritis in Experimentally and Naturally Infected Sheep

Chlamydia pecorum is an obligate intracellular pathogen with a wide host range including livestock such as sheep, cattle, goats, and pigs as well as wildlife species such as koalas. Chlamydial polyarthritis is an economically important disease resulting in swollen joints, lameness, stiffness, and weight loss in young sheep. In the present study, tissues from sheep experimentally or naturally infected with Chlamydia pecorum were assessed by histopathology and immunohistochemistry. Carpal, hock, and stifle joints as well as spleen, liver, kidney, lymph nodes, lung, and brain of 35 sheep from different inoculation groups were available. Two different C. pecorum strains (IPA and E58), different routes of administration (intraarticular or intravenous), UVA-irradiated IPA strain, and corresponding noninfected control groups were investigated. Similar investigations on tissues from 5 naturally infected sheep were performed. The most obvious inflammatory lesions were observed in synovial tissues and, notably, in the renal pelvis from the experimentally infected group and naturally infected animals. This resulted in chronic or chronic-active arthritis and pyelitis. Intralesional chlamydial inclusions could be demonstrated by immunohistochemistry in both tissues. Immunohistochemical evaluation of the presence and distribution of macrophages, T and B cells in synovial tissues revealed macrophages as the most prevalent inflammatory cell population. Previous observations indicated that C. pecorum isolates can infect circulating monocytes. Together with the finding of the histological lesions in synovial tissues and internal organs alongside the presence of C. pecorum DNA, these observations suggest chlamydial arthritis in lambs is the result of hematogeneous spread of C. pecorum.

Pathological features of established osteoarthritis with hydrathrosis are similar to rheumatoid arthritis

OBJECTIVES

The prevalence of rheumatoid arthritis (RA) and knee osteoarthritis (OA) is increasing with our aging society. Some reports suggest that OA with effusion synovitis develops into RA and early OA patients with effusion are pathologically similar to those with RA. The purpose of this study was to examine the relationship between histological features of established knee OA with or without effusion and RA.

METHODS

Seventy-nine patients in which synovial specimens were obtained during total knee arthroplasty were included. Patients were divided into an RA group, OA with effusion (OA+) group, and OA without effusion (OA-) group. The Rooney synovitis score and serum matrix metalloproteinase (MMP)-3 levels were compared among groups. We also examined the correlation between the Rooney synovitis score and its sub-scores with MMP-3 levels.

RESULTS

The total Rooney score was significantly higher in the RA group than in the OA+ and OA- groups (25.4 vs 17.1, p < 0.01; 25.4 vs 13.5, p < 0.001, respectively). This score also was significantly higher in the OA+ group than in the OA- group (p < 0.05). The proliferating blood vessels score, perivascular infiltrates of lymphocytes score, focal aggregates of lymphocytes score, and diffuse infiltrates of lymphocytes score were significantly higher in the RA group than in the OA- group (7.05 vs 3.29, 4.95 vs 3.43, 3.29 vs 1.46, and 2.26 vs 1.18, respectively; p < 0.05), but not compared with the OA+ group. The total Rooney score demonstrated a significantly positive correlation with serum MMP-3 levels in the RA group (r = 0.61; 95% CI: 0.28 to 0.81; p < 0.01) and in the OA+ group (r = 0.57; 95% CI: 0.24 to 0.78; p < 0.01).

CONCLUSIONS

Previous reports showed the histological similarity between RA and early OA with effusion. We confirmed this histological similarity, in particular the distribution of lymphocytes, between RA and established OA with effusion. It is possible that cases diagnosed as OA with effusion might progress to overt RA.

KEY POINTS

• Histological similarity was observed between RA and established OA with effusion.

15 years of the histopathological synovitis score, further development and review: A diagnostic score for rheumatology and orthopaedics

The histopathological synovitis score evaluates the immunological and inflammatory changes of synovitis in a graduated manner generally customary for diagnostic histopathological scores. The score results from semiquantitative evaluation of the width of the synovial surface cell layer, the cell density of the stroma and the density of the inflammatory infiltration into 4 semiquantitative levels (normal 0, mild 1, moderate 2, severe 3). The addition of these values results in a final score of 0-9 out of 9. On the basis of this summation the condition is divided into low-grade synovitis and high-grade synovitis: A synovitis score of 1 to≤4 is called low-grade synovitis (arthrosis-associated/OA synovitis, posttraumatic synovitis, meniscopathy-associated synovitis and synovitis with haemochromatosis). A synovitis score of≥5 to 9 is called high-grade synovitis (rheumatoid arthritis, psoriatic arthritis, Lyme arthritis, postinfection/reactive arthritis and peripheral arthritis with Bechterew's disease). By means of the synovitis score it is therefore possible to distinguish between degenerative/posttraumatic diseases (low-grade synovitis) and inflammatory rheumatic diseases (high-grade synovitis) with a sensitivity of 61.7% and a specificity of 96.1%. The diagnostic accuracy according to ROC analysis (AUC: 0.8-0.9) is good. Since the first publication (2002) and an associated subsequent publication (2006), the synovitis score has nationally and internationally been accepted for histopathological assessment of the synovitis. In a PubMed data analysis (status: 14.02.2017), the following citation rates according to Cited by PubMed Central articles resulted for the two synovitis score publications: For DOI: 10.1078/0344-0338-5710261 there were 29 Cited by PubMed Central articles and for the second extended publication DOI:10.1111/j.1365-2559.2006.02508 there were 44 Cited by PubMed Central articles. Therefore a total of 73 PubMed citations are observed over a period of 15 years, which demonstrates an international acceptance of the score. This synovitis score provides for the first time a diagnostic, standardised and reproducible histopathological evaluation method enabling a contribution to the differential diagnosis of chronic inflammatory general joint diseases. This is particularly the case by incorporation into the joint pathology algorithm. To specify the synovitis score an immunohistochemical determination of various inflammation-relevant CD antigens is proposed to enable a risk stratification of high-grade synovitis (e.g.: progression risk and sensitivity for biologicals).

Pilot study on 18 F-FDG PET/CT for detection of inflammatory changes in blood-induced knee arthropathy in a rabbit model

RATIONALE

¹⁸ F-FDG-PET/CT has a potential role in the early detection of haemophilic arthritis, at a time when treatment may still avoid further joint degeneration. The purposes of this pilot study were to determine the ability of ¹⁸ F-FDG-PET/CT to detect inflammatory changes associated with blood-induced arthropathy in knees of a rabbit model.

METHODS

Ten juvenile rabbits were imaged at baseline and weeks 5 and 17 post intraarticular autologous blood injections (ABI). Five rabbits in group 1 (G1) had ABI into the same knee joint every 2 weeks (total, eight injections). Five rabbits in group 2 (G2) had only two injections into the same knee, at weeks 5 and 17. Images were assessed visually and semi-quantitatively by measuring maximal standardized uptake values (SUVmax) and standardized uptake ratio (SUR = SUVmax in affected knee/SUVmax in non-affected knee).

RESULTS

More rabbits in G1 than G2 presented with positive chronic inflammatory synovial scores at week 17. Mean iron staining scores in injected knees were greater for G1 than for G2 (P = 0.049). No increased uptake was identified in the injected knees in any of the rabbits at baseline or at week 5. At week 17, all G1 rabbits demonstrated increased uptake in their affected knees with higher mean SUVmax (1.5) than normal knees (1.0) (P < 0.02). None of the G2 rabbits showed asymmetric increased uptake. The SUR of G1 was higher at week 17 compared to baseline (P < 0.01) and week 5 (P < 0.01). The SUR at week 17 was higher for G1 than for G2 (1.13) rabbits (P < 0.01).

CONCLUSION

¹⁸ F-FDG-PET is able to detect the inflammatory changes associated with haemophilic arthropathy in this experimental model.

NLRP3 Inflammasome Plays an Important Role in the Pathogenesis of Collagen-Induced Arthritis

Objective. To investigate the relationship between NLRP3 and the pathogenesis of collagen-induced arthritis. Methods. We used the collagen-induced arthritis (CIA) mouse model. The mice were divided into two groups: the model group (CIA, n = 16) and the control group (Normal, n = 8). The mice were sacrificed seven weeks after immunization. The arthritis score and imaging evaluation (X-rays, Micro-CT, and MRI) were performed. Synovial tissue NLRP3 expression and peripheral blood cytokine levels were analyzed. Results. The arthritis score (6.00 ± 2.52), imaging score (4.63 ± 0.92), and synovial tissue NLRP3 expression (4.00 ± 2.03) significantly increased in the CIA mice. The expression of synovial NLRP3 was positively correlated with arthritis clinical and radiographic scores (r = 0.792 and r = 0.669, resp.). Conclusions. The synovial NLRP3 expression increased at the early onset of RA. Synovial NLRP3 expression level was correlated with the clinical arthritis severity and extent of radiological destruction, suggesting that NLRP3 is involved in the pathogenesis of RA.

Characterization of multinucleated giant cells in synovium and subchondral bone in knee osteoarthritis and rheumatoid arthritis

Background

Multinucleated giant cells have been noticed in diverse arthritic conditions since their first description in rheumatoid synovium. However, their role in the pathogenesis of osteoarthritis (OA) or rheumatoid arthritis (RA) still remains broadly unknown. We aimed to study the presence and characteristics of multinucleated giant cells (MGC) both in synovium and in subchondral bone tissues of patients with OA or RA.

Methods

Knee synovial and subchondral bone samples were from age-matched patients undergoing total joint replacement for OA or RA, or non-arthritic post mortem (PM) controls. OA synovium was stratified by histological inflammation grade using index tissue sections. Synovitis was assessed by Krenn score. Histological studies employed specific antibodies against macrophage markers or cathepsin K, or TRAP enzymatic assay.

Results

Inflamed OA and RA synovia displayed more multinucleated giant cells than did non-inflamed OA and PM synovia. There was a significant association between MGC numbers and synovitis severity. A TRAP negative/cathepsin K negative Langhans-like subtype was predominant in OA, whereas both Langhans-like and TRAP-positive/cathepsin K-negative foreign-body-like subtypes were most commonly detected in RA. Plasma-like and foam-like subtypes also were observed in OA and RA synovia, and the latter was found surrounding adipocytes. TRAP positive/cathepsin K positive osteoclasts were only identified adjacent to subchondral bone surfaces. TRAP positive osteoclasts were significantly increased in subchondral bone in OA and RA compared to PM controls.

Conclusions

Multinucleated giant cells are associated with synovitis severity, and subchondral osteoclast numbers are increased in OA, as well as in RA. Further research targeting multinucleated giant cells is warranted to elucidate their contributions to the symptoms and joint damage associated with arthritis.

Electronic supplementary material

The online version of this article (doi:10.1186/s12891-015-0664-5) contains supplementary material, which is available to authorized users.

Physiologic characterization of inflammatory arthritis in a rabbit model with BOLD and DCE MRI at 1.5 Tesla

OBJECTIVE

Our aim was to test the feasibility of blood oxygen level dependent magnetic resonance imaging (BOLD MRI) and dynamic contrast-enhanced (DCE) MRI to monitor periarticular hypoxic/inflammatory changes over time in a juvenile rabbit model of arthritis.

METHODS

We examined arthritic and contralateral nonarthritic knees of 21 juvenile rabbits at baseline and days 1,14, and 28 after induction of arthritis by unilateral intra-articular injection of carrageenin with BOLD and DCE MRI at 1.5 Tesla (T). Nine noninjected rabbits served as controls. Associations between BOLD and DCE-MRI and corresponding intra-articular oxygen pressure (PO2) and blood flow [blood perfusion units (BPU)] (polarographic probes, reference standards) or clinical-histological data were measured by correlation coefficients.

RESULTS

Percentage BOLD MRI change obtained in contralateral knees correlated moderately with BPU on day 0 (r = -0.51, p = 0.02) and excellently on day 28 (r = -0.84, p = 0.03). A moderate correlation was observed between peak enhancement DCE MRI (day 1) and BPU measurements in arthritic knees (r = 0.49, p = 0.04). In acute arthritis, BOLD and DCE MRI highly correlated (r = 0.89, p = 0.04; r = 1.0, p < 0.0001) with histological scores in arthritic knees.

CONCLUSION

The proposed techniques are feasible to perform at 1.5 T, and they hold potential as surrogate measures to monitor hypoxic and inflammatory changes over time in arthritis at higher-strength MRI fields.

KEY POINTS

• BOLD and DCE MRI detect interval perisynovial changes in a rabbit knee • BOLD and DCE MRI act as surrogate markers of physiologic changes in arthritis • BOLD MRI signal represents oxygen extraction compared with intra-articular PO 2 • DCE MRI measurements estimate physiologic periarticular vascular properties • In rabbit knees with acute arthritis, BOLD/DCE MRI highly correlated with histological scores.

Serum matrix metalloproteinase-3 as a noninvasive biomarker of histological synovitis for diagnosis of rheumatoid arthritis

Objective. To explore the correlation between matrix metalloproteinase- (MMP-) 3 and histological synovitis in rheumatoid arthritis (RA). Methods. Serum MMP-3 of 62 patients with active RA was detected by ELISA. Serial synovial tissue sections from all RA patients, 13 osteoarthritis, and 10 orthopedic arthropathies patients were stained with hematoxylin and eosin and immunohistochemically for MMP-3, CD3, CD20, CD38, CD68, and CD15. Results. The percentage of lining MMP3+ cells was significantly higher in RA patients especially with high grade synovitis and it was significantly correlated with Krenn's synovitis score (r = 0.574, P < 0.001) and sublining inflammatory cells. Multivariate stepwise linear regression analysis revealed that the association of the percentage of lining MMP3+ cells with activation of synovial stroma, sublining CD68+ macrophages, and CD15+ neutrophils was stronger than other histological indicators. The percentage of lining MMP3+ cells was significantly correlated with serum MMP-3 in RA (r = 0.656, P < 0.001). Serum MMP-3 was higher in RA patients with high grade synovitis than that of low grade synovitis and significantly correlated with synovitis score and activation of synovial stroma subscore (all P < 0.05). Conclusion. Serum MMP-3 may be an alternative noninvasive biomarker of histological synovitis and RA diagnosis.

Systematic protocol for assessment of the validity of BOLD MRI in a rabbit model of inflammatory arthritis at 1.5 tesla

BACKGROUND

Blood-oxygen-level-dependent (BOLD) MRI has the potential to identify regions of early hypoxic and vascular joint changes in inflammatory arthritis. There is no standard protocol for analysis of BOLD MRI measurements in musculoskeletal disorders.

OBJECTIVE

To optimize the following BOLD MRI reading parameters: (1) statistical threshold values (low, r > 0.01 versus high, r > 0.2); (2) summary measures of BOLD contrast (percentage of activated voxels [PT%] versus percentage signal difference between on-and-off signal intensities [diff_on_off]); and (3) direction of BOLD response (positive, negative and positive + negative).

MATERIALS AND METHODS

Using BOLD MRI protocols at 1.5 T, arthritic (n = 21) and contralateral (n = 21) knees of 21 juvenile rabbits were imaged at baseline and on days 1, 14 and 28 after a unilateral intra-articular injection of carrageenan. Nine non-injected rabbits served as external control knees (n = 18). By comparing arthritic to contralateral knees, receiver operating characteristic curves were used to determine diagnostic accuracy.

RESULTS

Using diff_on_off and positive + negative responses, a threshold of r > 0.01 was more accurate than r > 0.2 (P = 0.03 at day 28). Comparison of summary measures yielded no statistically significant difference (P > 0.05). Although positive + negative (AUC = 0.86 at day 28) and negative responses (AUC = 0.90 at day 28) for PT% were the most diagnostically accurate, positive + negative responses for diff_on_off (AUC = 0.78 at day 28) also had acceptable accuracy.

CONCLUSIONS

The most clinically relevant reading parameters included a lower threshold of r > 0.01 and a positive + negative BOLD response. We propose that diff_on_off is a more clinically relevant summary measure of BOLD MRI, while PT% can be used as an ancillary measure.

Erosive arthritis and hepatic granuloma formation induced by peptidoglycan polysaccharide in rats is aggravated by prasugrel treatment

Administration of the thienopyridine P2Y12 receptor antagonist, clopidogrel, increased the erosive arthritis induced by peptidoglycan polysaccharide (PG-PS) in rats or by injection of the arthritogenic K/BxN serum in mice. To determine if the detrimental effects are caused exclusively by clopidogrel, we evaluated prasugrel, a third-generation thienopyridine pro-drug, that contrary to clopidogrel is mostly metabolized into its active metabolite in the intestine. Prasugrel effects were examined on the PG-PS-induced arthritis rat model. Erosive arthritis was induced in Lewis rats followed by treatment with prasugrel for 21 days. Prasugrel treated arthritic animals showed a significant increase in the inflammatory response, compared with untreated arthritic rats, in terms of augmented macroscopic joint diameter associated with significant signs of inflammation, histomorphometric measurements of the hind joints and elevated platelet number. Moreover, fibrosis at the pannus, assessed by immunofluorescence of connective tissue growth factor, was increased in arthritic rats treated with prasugrel. In addition to the arthritic manifestations, hepatomegaly, liver granulomas and giant cell formation were observed after PG-PS induction and even more after prasugrel exposure. Cytokine plasma levels of IL-1 beta, IL-6, MIP1 alpha, MCP1, IL-17 and RANTES were increased in arthritis-induced animals. IL-10 plasma levels were significantly decreased in animals treated with prasugrel. Overall, prasugrel enhances inflammation in joints and liver of this animal model. Since prasugrel metabolites inhibit neutrophil function ex-vivo and the effects of both clopidogrel and prasugrel metabolites on platelets are identical, we conclude that the thienopyridines metabolites might exert non-platelet effects on other immune cells to aggravate inflammation.

Synovial inflammation, immune cells and their cytokines in osteoarthritis: a review

OBJECTIVE

Although osteoarthritis (OA) is considered a non-inflammatory condition, it is widely accepted that synovial inflammation is a feature of OA. However, the role of immune cells and their cytokines in OA is largely unknown. This narrative systematic review summarizes the knowledge of inflammatory properties, immune cells and their cytokines in synovial tissues (STs) of OA patients.

DESIGN

Broad literature search in different databases was performed which resulted in 100 articles.

RESULTS

Of 100 articles 33 solely investigated inflammation in OA ST with or without comparison with normal samples; the remaining primarily focussed on rheumatoid arthritis (RA) ST. Studies investigating different severity stages or cellular source of cytokines were sparse. OA ST displayed mild/moderate grade inflammation when investigated by means of haematoxylin and eosin (H&E) staining. Most frequently found cells types were macrophages, T cells and mast cells (MCs). Overall the number of cells was lower than in RA, although the number of MCs was as high as or sometimes even higher than in RA ST. Cytokines related to T cell or macrophage function were found in OA ST. Their expression was overall higher than in normal ST, but lower than in RA ST. Their cellular source remains largely unknown in OA ST.

CONCLUSION

Inflammation is common in OA ST and characterized by immune cell infiltration and cytokine secretion. This inflammation seems quantitatively and qualitatively different from inflammation in RA. Further research is needed to clarify the role of inflammation, immune cells and their cytokines in the pathogenesis of OA.

Correlative BOLD MR imaging of stages of synovitis in a rabbit model of antigen-induced arthritis

BACKGROUND

Because of the ability of blood-oxygen-level-dependent (BOLD) MRI to assess blood oxygenation changes within the microvasculature, this technique holds potential for evaluating early perisynovial changes in inflammatory arthritis.

OBJECTIVE

To evaluate the feasibility of BOLD MRI to detect interval perisynovial changes in knees of rabbits with inflammatory arthritis.

MATERIALS AND METHODS

Rabbit knees were injected with albumin (n=9) or saline (n=6) intra-articularly, or were not injected (control knees, n=9). Except for two rabbits (albumin-injected, n=2 knees; saline-injected, n=2 knees) that unexpectedly died on days 7 and 21 of the experiment, respectively, all other animals were scanned with BOLD MRI on days 0, 1, 7, 14, 21 and 28 after induction of arthritis. T2*-weighted gradient-echo MRI was performed during alternate 30 s of normoxia/hyperoxia. BOLD MRI measurements were compared with clinical, laboratory and histological markers.

RESULTS

Percentage of activated voxels was significantly greater in albumin-injected knees than in contralateral saline-injected knees (P=0.04). For albumin-injected knees (P<0.05) and among different categories of knees (P=0.009), the percentage of activated BOLD voxels varied over time. A quadratic curve for on-and-off BOLD difference was delineated for albumin- and saline-injected knees over time (albumin-injected, P=0.047; saline-injected, P=0.009). A trend toward a significant difference in synovial histological scores between albumin-injected and saline-injected knees was noted only for acute scores (P=0.07).

CONCLUSION

As a proof of concept, BOLD MRI can depict perisynovial changes during progression of experimental arthritis.

Clopidogrel, a P2Y12 receptor antagonist, potentiates the inflammatory response in a rat model of peptidoglycan polysaccharide-induced arthritis

The P2Y12 receptor plays a crucial role in the regulation of platelet activation by several agonists, which is irreversibly antagonized by the active metabolite of clopidogrel, a widely used anti-thrombotic drug. In this study, we investigated whether reduction of platelet reactivity leads to reduced inflammatory responses using a rat model of erosive arthritis. We evaluated the effect of clopidogrel on inflammation in Lewis rats in a peptidoglycan polysaccharide (PG-PS)-induced arthritis model with four groups of rats: 1) untreated, 2) clopidogrel-treated, 3) PG-PS-induced, and 4) PG-PS-induced and clopidogrel-treated. There were significant differences between the PG-PS+clopidogrel group when compared to the PG-PS group including: increased joint diameter and clinical manifestations of inflammation, elevated plasma levels of pro-inflammatory cytokines (IL-1 beta, interferon (IFN) gamma, and IL-6), an elevated neutrophil blood count and an increased circulating platelet count. Plasma levels of IL-10 were significantly lower in the PG-PS+clopidogrel group compared to the PG-PS group. Plasma levels of platelet factor 4 (PF4) were elevated in both the PG-PS and the PG-PS+clopidogrel groups, however PF4 levels showed no difference upon clopidogrel treatment, suggesting that the pro- inflammatory effect of clopidogrel may be due to its action on cells other than platelets. Histology indicated an increase in leukocyte infiltration at the inflammatory area of the joint, increased pannus formation, blood vessel proliferation, subsynovial fibrosis and cartilage erosion upon treatment with clopidogrel in PG-PS-induced arthritis animals. In summary, animals treated with clopidogrel showed a pro-inflammatory effect in the PG-PS-induced arthritis animal model, which might not be mediated by platelets. Elucidation of the mechanism of clopidogrel-induced cell responses is important to understand the role of the P2Y12 receptor in inflammation.

Binding immunoglobulin protein resolves rheumatoid synovitis: a xenogeneic study using rheumatoid arthritis synovial membrane transplants in SCID mice

INTRODUCTION

Binding immunoglobulin protein (BiP) has previously shown powerful anti-inflammatory properties in the collagen-induced arthritis (CIA) model, where a single dose of BiP has proved to be both a long-term prophylactic and therapeutic. In both CIA and human in vitro studies, BiP induced regulatory T cells. The present investigation looked at the anti-inflammatory effect of BiP on inflamed human synovial tissue transplanted into severe combined immunodeficient mice (SCID), a chimaeric in vivo model previously used to test the efficacy of biologic therapies.

METHODS

Rheumatoid arthritis synovial membrane (RASM) was engrafted into SCID mice. Following successful engraftment, mice were intravenously injected with BiP or human serum albumin in the presence or absence of anti-IL-10 mAb. Twelve days later the grafts were removed for analysis and human cytokines in the sera were quantified by ELISA. The extent of residual inflammatory cellular infiltrate in the synovial explants was determined by weight of the explants.

RESULTS

The RASM transplants from mice treated with BiP showed visual reduction in cellular infiltrate and downregulation of all quantifiable features of inflammation as assessed by the Koizumi or Rooney histological criteria. Also downregulated were HLA-DR, CD86, IL-6 and TNFα expression as assessed by immunohistology. ELISA detected significantly less human IL-6 circulating in the BiP-treated mouse serum. After removal of transplanted tissue 12 days post administration of BiP, the RASM explants from the BiP-treated SCID mice weighed significantly less, indicating a suppression of tissue inflammation. Mice given concomitant neutralising anti-IL-10 antibody and BiP showed no such suppression.

CONCLUSIONS

BiP has anti-inflammatory properties partially dependent on the downregulation of HLA-DR and co-stimulatory molecules and the predominant production of IL-10.

Utility of synovial biopsy

Synovial biopsies, gained either by blind needle biopsy or minimally invasive arthroscopy, offer additional information in certain clinical situations where routine assessment has not permitted a certain diagnosis. In research settings, synovial histology and modern applications of molecular biology increase our insight into pathogenesis and enable responses to treatment with new therapeutic agents to be assessed directly at the pathophysiological level. This review focuses on the diagnostic usefulness of synovial biopsies in the light of actual developments.

High oxygen tension prolongs the survival of osteoclast precursors via macrophage colony-stimulating factor

The oxygen tension affects the function, differentiation, and transformation of various cells, including bone cells. In pathological conditions such as rheumatoid arthritis (RA), rapidly destructive arthropathy, and primary or metastatic tumors, severe bone destruction or osteolysis occurs. Abundant blood vessels are often observed around these destructive lesions. At such sites, we have confirmed the increased production of reactive oxygen species (ROS) induced by a high oxygen tension and/or oxidative stress, as well as numerous osteoclasts detectable by immunohistochemistry. These findings suggest that osteoclasts are influenced by the high oxygen tension in pathological bone lesions because the zone around blood vessels has a relatively high oxygen tension. In this study, we investigated the effects of oxygen tension on osteoclastogenesis by culturing human CD14-positive cells (osteoclast precursors) with or without osteoblast-like supporting cells (Saos-4/3 cells) under a normal oxygen tension (20% O(2)) or a high oxygen tension (40% O(2)). A high oxygen tension markedly prolonged the duration of osteoclast precursor formation in the presence of supporting cells, and also markedly and persistently increased the production of macrophage colony stimulating factor (M-CSF) by supporting cells. Furthermore, we found an increase of cells expressing M-CSF and cells positive for tartrate-resistant acid phosphatase (TRAP) in hypervascular destructive bone lesions of RA patients where ROS were also abundant.

[Synovitis score: value of histopathological diagnostics in unclear arthritis. Case reports from rheumatological pathological practice]

Histopathological assessment of synovial biopsies has an established value. The value for inflammatory joint diseases without standardized rating mechanisms was, however, unknown until recently. The exemplary use of the synovitis score in four cases all including recurrent bruises of the knee joint portrays its value for diagnosis and therapy. Usage of the score includes assessing the enlargement of the lining layer, cellular density of synovial stroma and leucocyte infiltration by giving each a score of 0-3 points and adding them. Presence of high-grade synovitis (>or=4 points) in all cases displayed the reason for the joint bruises within a primarily inflammatory, rheumatoid circle. In this report we show the broad variety of uses for the synovitis score dealing with cases of Lyme arthritis, rheumatoid arthritis, seronegative monarthritis and HLA-B27-positive peripheral arthritis.

Immunohistological assessment of the synovial tissue in small joints in rheumatoid arthritis: validation of a minimally invasive ultrasound-guided synovial biopsy procedure

The aim of the present study was to perform an immunohistological assessment of the synovial tissue from involved small joints in rheumatoid arthritis (RA) and to explore the reliability of a mini-invasive ultrasound (US)-guided technique of small joint synovial biopsy for the histopathological assessment. Synovial tissue collected during arthrotomic surgery of small joints in nine patients served as the gold standard for the validation of the histological assessment. Small hand-joint synovial biopsies from an additional nine patients with erosive RA were obtained by a mini-invasive US-guided procedure, performed percutaneously by the portal and rigid forceps technique. Using digital image analysis, the area fractions of synovial macrophages (CD68 cells), T cells (CD3 cells) and B cells (CD20 cells) were measured in all high-power fields of every sample at different cutting levels. The representative sample was defined as the minimal number of high-power fields whose mean area fraction would reflect the overall mean area fraction within a percentage mean difference of 10%. For each patient, a range of three to five large samples for surgical biopsies and a range of 8–12 samples for US-guided biopsies were collected and analysed. In arthrotomic samples, the analysis of a randomly selected tissue area of 2.5 mm² was representative of the overall value for CD68, CD3 and CD20 cells. US-guided samples allowed histological evaluation in 100% of cases, with a mean valid area of 18.56 mm² (range 7.29–38.28 mm²). The analysis of a cumulative area of 2.5 mm² from eight randomly selected sections (from different samples or from different cutting levels) allowed to reduce the percentage mean difference to less than 10% for CD68, CD3 and CD20 cells. In conclusion, US-guided synovial biopsy represents a reliable tool for the assessment of the histopathological features of RA patients with a mini-invasive approach.

High levels of Lymphotoxin-Beta (LT-Beta) gene expression in rheumatoid arthritis synovium: clinical and cytokine correlations

Lymphotoxin-Beta (LT-Beta) is implicated in lymphoid follicle development, production of pro-inflammatory cytokines, and can enhance the proliferation of fibroblasts and synoviocytes. The objective of this study was to investigate LT-Beta and LT-BetaReceptor (LT-BetaR) gene expression in RA patient synovium and blood samples compared with control individuals, and correlate with LT-Alpha and TNF-Alpha gene expression and disease parameters. RT-PCR was used to investigate the gene expression of LT-Beta, LT-BetaR, TNF-Alpha and LT-Alpha in the blood and synovium of RA patients and a control group of individuals. LT-Beta gene expression was significantly higher in RA patient synovium compared to control synovium (P = 0.005). There was a significant positive correlation between LT-Beta and LT-Alpha gene expression in both the synovium (P = 0.001) and blood (P = 0.002) of RA patients. LT-Beta gene expression was significantly higher in RA patient synovial samples that were inflamed to a moderately severe degree compared to those inflamed to a minimal degree (P = 0.02). Analysis of clinical variables revealed a significant positive correlation between LT-BetaR gene expression in RA patient synovium and Pain VAS Score (P = 0.01) and also HAQ Score (P = 0.01). Increased LT-Beta gene expression occurs in RA synovium and correlates with the degree of inflammation. LT-Beta may play a role in RA disease pathogenesis by contributing to a more intense inflammatory reaction in the synovium.

Expression of BAFF and BAFF-R in the synovial tissue of patients with rheumatoid arthritis

OBJECTIVE

The elevated expression of B-cell-activating factor belonging to the TNF family (BAFF) is associated with systemic autoimmune disease, including rheumatoid arthritis (RA). The present study was undertaken to determine the distribution of BAFF and its receptor BAFF-R in the cells residing in the rheumatoid synovium.

METHODS

The expression of BAFF and BAFF-R in synovial tissues obtained from 12 RA patients was examined by immunohistochemistry and flow cytometry. The mRNA expression of these molecules was determined by reverse transcriptase polymerase chain reaction (RT-PCR). Soluble BAFF levels were measured with an enzyme-linked immunosorbent assay (ELISA). Fibroblast-like synoviocytes (FLS) purified from the RA (RA-FLS) were co-cultured with peripheral B cells. The degree of apoptosis in the B cells was measured to assess the effects on the viability of the B cells.

RESULTS

The RA synovium showed focal or diffuse infiltration of mononuclear cells (MNCs), and one specimen showed germinal centre (GC)-like structures. Synovial sublining cells, but not lining cells, expressed BAFF. These sublining cells were negative for BAFF-R. BAFF and BAFF-R were expressed in B and T cells extracted from the RA synovium. Notably, RA-FLS spontaneously expressed cytoplasmic BAFF after 4-6 passages; however, they did not express BAFF or BAFF-R on their cell surface. RA-FLS could support the survival of B cells by preventing their apoptosis, but its effect on B cells might not be BAFF dependent.

CONCLUSIONS

BAFF and BAFF-R are widely expressed in the RA synovium. The cells residing in the RA synovium might affect each other through BAFF.

Histological changes in murine haemophilic synovitis: a quantitative grading system to assess blood-induced synovitis

Haemophilia is a congenital disorder that results in frequent bleeding into joints, in which a chronic and debilitating arthritis develops. The presence of blood evokes an inflammatory and proliferative synovial reaction. Although the molecular mechanisms and biochemical pathways which underlie this disorder are not known, significant advances have been made by studying a murine model of human haemophilic synovitis. In order to better understand and correlate the pathological, molecular and biochemical changes, it has become necessary to grade the histological changes observed. Despite a search of the literature and review of relevant publications, none of the currently utilized schemes were appropriate, and therefore a novel grading scheme was developed. After review of over 1000 histological sections, six characteristic changes were identified: (i) synovial hyperplasia; (ii) vascularity; (iii) discolouration by haemosiderin; (iv) the presence of blood (erythrocytes); (v) villus formation; and (vi) cartilage erosion. Synovial hyperplasia and vascularity were present in variable amounts and were quantitatively scored (0-3), while the other changes were qualitatively scored as absent or present (0 or 1). Application of the grading scheme was tested and a high interobserver correlation (greater than 80%) was found. The scheme was easy to learn even by novices, with no prior experience. The availability of the histological grading scheme for murine synovitis will allow for precise evaluation of the pathological changes following joint bleeding, and facilitate correlations with molecular and biochemical changes that lead to these changes.

Contrast-enhanced triggered harmonic sonography for assessment of periarticular hemodynamic changes in experimental arthritis

BACKGROUND

Objective quantification is critical for assessment of functional sonography in inflammatory arthritis. To create a microbubble contrast-enhanced image of vessels that lie below the resolution of a standard US system, a technique is required that detects preferentially the contrast agent echo, rejecting that from background tissue: harmonic imaging.

OBJECTIVES

To investigate the ability of contrast-enhanced triggered harmonic sonography (CETHS) to evaluate periarticular hemodynamic changes over the course of experimental arthritis and to discriminate presence and absence of arthritis based on measurement values obtained at specific time-points.

MATERIALS AND METHODS

Arthritis was induced in rabbits knees by intra-articular injection of serum bovine albumin, which acted as an antigen. A total of 11 rabbits (8 with unilateral arthritis and 3 control animals) were imaged at 0, 1, 7, 14, 21 and 28 days of antigen-induced arthritis and euthanized at 28 days. A continuous infusion protocol was performed (triggering times 30.0, 20.0, 10.0, 5.0, 2.0, 1.0, and 0.5 s). Hemodynamic indices of synovial microvasculature (vascular volume, mean velocity and flow rate) were obtained and compared with clinical, laboratory, and histological surrogate markers.

RESULTS

Although interval CETHS changes were noted for flow rate (P=0.007) and vascular volume (P=0.003) ratios in albumin-injected knees, no significant differences in ratios were identified over time between albumin-injected and non-injected knees for flow rate (P=0.52), vascular volume (P=0.23) and mean velocity (P=0.19). Flow rate most accurately differentiated between presence and absence of arthritis according to clinical measurements in early (day 1) arthritis, and mean velocity in mid-term arthritis (day 14; both P=0.02).

CONCLUSION

Although the measurement properties of CETHS indices were poor in the evaluation of hemodynamic differences over time in albumin-injected knees compared with non-injected knees, they enabled discrimination between presence and absence of arthritis at specific time-points in different stages.

Synovitis score: discrimination between chronic low-grade and high-grade synovitis

AIMS

To standardize the histopathological assessment of synovial membrane specimens in order to contribute to the diagnostics of rheumatic and non-rheumatic joint diseases.

METHODS AND RESULTS

Three features of chronic synovitis (enlargement of lining cell layer, cellular density of synovial stroma, leukocytic infiltrate) were semiquantitatively evaluated (from 0, absent to 3, strong) and each feature was graded separately. The sum provided the synovitis score, which was interpreted as follows: 0-1, no synovitis; 2-4, low-grade synovitis; 5-9, high-grade synovitis. Five hundred and fifty-nine synovectomy specimens were graded by two independent observers. Clinical diagnoses were osteoarthrosis (n=212), post-traumatic arthritis (n=21), rheumatoid arthritis (n=246), psoriatic arthritis (n=22), reactive arthritis (n=9), as well as controls (n=49) from autopsies of patients without joint damage. Median synovitis scores when correlated with clinical diagnoses were: controls 1.0, osteoarthritis 2.0, post-traumatic arthritis 2.0, psoriatic arthritis 3.5, reactive arthritis 5.0 and rheumatoid arthritis 5.0. The scores differed significantly between most disease groups, especially between degenerative and rheumatic diseases. A high-grade synovitis was strongly associated with rheumatic joint diseases (P<0.001, sensitivity 61.7%, specificity 96.1%). The correlation between the two observers was high (r=0.941).

CONCLUSION

The proposed synovitis score is based on well-defined, reproducible histopathological criteria and may contribute to diagnosis in rheumatic and non-rheumatic joint diseases.

[Low-grade-/high-grade-synovitis: synovitis-score as a gold standard?]

BACKGROUND

Synovectomy specimens represent important material submitted from the orthopedist to the pathologist. However, no consistent histopathological grading system for chronic synovitis has been established so far.

PATIENTS AND METHODS

The three compartments of chronic synovitis (enlargement of lining cell layer, density of synovial stroma cells, leukocytic infiltrate) are graded semiquantitatively (from 0=absent to 3=strong), and the points for each compartment add up to the synovitis score: 0-1 = no synovitis, 2-4 = low-grade synovitis, 5-9 = high-grade synovitis. A total of 618 synovial specimens (resections n=559, biopsies n=59) from degenerative and inflammatory joint diseases were graded by two independent observers.

RESULTS

Median synovitis scores when correlated to clinical diagnoses were: 1, control; 2, osteoarthritis and post-traumatic arthritis; 3, psoriatic arthritis; 5, reactive and rheumatoid arthritis. The differences between rheumatic and non-rheumatic diseases were significant (p<0.001). The correlation between the two observers was high (p<0.001).

CONCLUSIONS

The proposed synovitis score enables stratification of chronic synovitis into low-grade (score 2-4) and high-grade (score >4), which is correlated to the nature of the disease (low-grade to non-rheumatic, high-grade to rheumatic), and it therefore contributes to the diagnosis of rheumatic and non-rheumatic joint diseases.

The synovial membrane as a prognostic tool in rheumatoid arthritis

The ability to effectively treat patients with rheumatoid arthritis (RA) has become increasingly feasible with the use of powerful treatment regimens early on in the disease. The use of such regimens has, however, created a pressing requirement for better prognostic markers to allow the targeting of these treatments to those most at need, hence minimizing expense and toxicity. As the synovial membrane has been ever more recognised as the primary pathogenetic site in RA its role as a prognostic indicator has been explored. As yet no reliable single prognostic marker has been identified. This article discusses the range of pathological variables already examined and those markers holding most potential.

LST1 and NCR3 expression in autoimmune inflammation and in response to IFN-gamma, LPS and microbial infection

Many genes in the central region of the major histocompatibility complex (MHC) encode proteins involved in immune and inflammatory responses. In this study, we have further characterized two genes in the MHC class IV region, leucocyte-specific transcript (LST) 1 and natural cytotoxicity-triggering receptor 3 (NCR3) (also known as 1C7 and natural killer (NK)p30). The specific function of LST1 is not known, although expression analysis and functional data suggest an immunomodulatory role. The LST1 gene undergoes extensive alternative splicing, giving rise to both membrane-bound (encoded by exon 3) and soluble isoforms. The NCR3 protein is involved in NK-mediated cytotoxicity and plays a role in NK/dendritic cell crosstalk. Expression of these genes was examined, by real-time reverse transcriptase-polymerase chain reaction, in autoimmune-induced inflammation, specifically rheumatoid-arthritis-affected blood and synovium, and in response to stimulation with inflammatory mediators and bacterial agents. The expression of LST1, specifically splice variants encoding soluble isoforms and NCR3, was increased in rheumatoid-arthritis-affected blood and synovium and was associated with more severe inflammation in the synovium. Furthermore, both genes were significantly up-regulated in response to lipopolysaccharide, interferon (IFN)-gamma and bacterial infection. These findings suggest that NCR3 and soluble isoforms of LST1 may play a role in inflammatory and infectious diseases.

[Synovialitis score: histopathological grading system for chronic rheumatic and non-rheumatic synovialitis]

Standardization of the histopathological assessment of synovial membrane specimens might facilitate the diagnosis of chronic rheumatic and non-rheumatic joint diseases. We would like to propose a histological graduation scheme ("synovialitis score"), which is applicable to all forms of synovitis, irrespective of its etiology. This score evaluates the three compartments of chronic synovialitis [enlargement of lining cell layer, activation of synovial stroma (i. e. resident cells), leukocytic infiltrate] semiquantitatively (from 0=absent to 3=strong). Each compartment is graded separately, and the sum resembles the synovialitis score, which is interpreted as follows: 0-1: no synovialitis, 2- 3: slight synovialitis, 4-6: moderate synovialitis, 7-9: strong synovialitis (for sample photos see also www.charite.de/ch/patho/Webpage/pages/forschung/arbeitsgruppen/ag-krenn/index.htm). A total of 483 synovial specimens (resections n=462, biopsies n=21) were graded by two independent observers. Clinical diagnoses were osteoarthrosis (OA; n=153), posttraumatic arthritis (PtA; n=31), rheumatoid arthritis (RA; n=239), psoriatic arthritis (PsA; n=32), reactive arthritis (ReA; n=7), and controls (Co, n=21) from necropsies of patients without joint damage. The correlation between two observers was high (p<0.001). The correlation coefficient between the different samples from the same joint in n=112 cases was between 0.86 and 0.95. Median synovialitis scores when correlated with clinical diagnoses were: Co 0.5, OA 2, PtA 3, PsA 3, ReA 4, RA 5. The differences in scores between Co and all other groups were highly significant (p<0.001). A synovialitis score of 4 points and more was strongly associated with rheumatic joint diseases (sensitivity 73%, specificity 86%). Validation of the synovialitis score by gene expression data showed good correlations for the lining cell enlargement with MMP1 (0.685), for the leukocytic infiltrate with CD3 (0.754) and CD138 (0.744) and for the stroma activation with CD14 (0.744). The proposed synovialitis score is based on well definable histopathologic criteria and contributes to the diagnosis of rheumatic and non-rheumatic joint diseases.

Characterization of histopathology and gene-expression profiles of synovitis in early rheumatoid arthritis using targeted biopsy specimens

The disease category of early rheumatoid arthritis (RA) has been limited with respect to clinical criteria. Pathological manifestations of synovitis in patients whose disease is clinically classified as early RA seem to be heterogeneous, with regular variations. To clarify the relation between the molecular and histopathological features of the synovitis, we analyzed gene-expression profiles in the synovial lining tissues to correlate them with histopathological features. Synovial tissues were obtained from knee joints of 12 patients with early RA by targeted biopsy under arthroscopy. Surgical specimens of long-standing RA (from four patients) were examined as positive controls. Each histopathological parameter characteristic of rheumatoid synovitis in synovial tissues was scored under light microscopy. Total RNAs from synovial lining tissues were obtained from the specimens selected by laser capture microdissection and the mRNAs were amplified by bacteriophage T7 RNA polymerase. Their cDNAs were analyzed in a cDNA microarray with 23,040 cDNAs, and the levels of gene expression in multilayered lining tissues, compared with those of normal-like lining tissues in specimens from the same person, were determined to estimate gene-expression profiles characteristic of the synovial proliferative lesions in each case. Based on cluster analysis of all cases, gene-expression profiles in the lesions in early RA fell into two groups. The groups had different expression levels of genes critical for proliferative inflammation, including those encoding cytokines, adhesion molecules, and extracellular matrices. One group resembled synovitis in long-standing RA and had high scores for some histopathological features – involving accumulations of lymphocytes and plasma cells – but not for other features. Possible differences in the histopathogenesis and prognosis of synovitis between the two groups are discussed in relation to the candidate genes and histopathology.

Bone marrow cells carrying the env-pX transgene play a role in the severity but not prolongation of arthritis in human T-cell leukaemia virus type-I transgenic rats: a possible role of articular tissues carrying the transgene in the prolongation of arthritis

Transgenic rats carrying the env-pX gene of human T-cell leukaemia virus type-I (env-pX rats) were immunized with type II collagen (CII), and chronological alterations of arthritis were compared with findings of collagen-induced arthritis (CIA) in wildtype Wistar-King-Aptekman-Hokudai (WKAH) rats. Arthritis induced by CII in env-pX rats was more severe and persisted longer than CIA in WKAH rats. To determine whether the phenomenon is caused mainly by the transgene-carrying lymphocytes or articular tissues, we immunized lethally irradiated env-pX and WKAH rats with reciprocal bone marrow cell (BMC) transplantation. A severe but transient arthritis was induced by CII in WKAH rats reconstituted by env-pX BMC (w/tB/CII rats). On the other hand, in env-pX rats reconstituted by WKAH BMC, arthritis persisted longer than in w/tB/CII rats, although the degree was less at an early phase after CII immunization. These findings suggest that articular tissues rather than the BMCs carrying the env-pX transgene play a role in the prolongation of arthritis in env-pX rats, although BMCs carrying the transgene are associated with the severity of arthritis. When inflammatory cytokines in synovial cells isolated from env-pX rats before they developed arthritis were examined, interleukin-6 (IL-6) was detected at a higher level than in synovial cells from WKAH rats, thus suggesting the critical role of IL-6 in env-pX arthritis.

A monoclonal antibody to high-molecular weight kininogen is therapeutic in a rodent model of reactive arthritis

We reported that high-molecular weight kininogen is proangiogenic by releasing bradykinin and that a monoclonal antibody to high-molecular weight kininogen, C11C1, blocked its binding to endothelial cells. We now test if this antibody can prevent arthritis and systemic inflammation in a Lewis rat model. We studied 32 animals for 16 days. Group I (negative control) received saline intraperitoneally. Group II (disease-treated) received peptidoglycan-polysaccharide simultaneously with C11C1. Group III (disease-untreated) received peptidoglycan-polysaccharide simultaneously with isotype-matched mouse IgG. Group IV (disease-free-treated) and group V (disease-free isotype-treated) received saline and C11C1 or mouse IgG. Analysis of joint diameter changes showed a decrease in the C11C1 disease-treated group compared to the disease-untreated group. The hind paw inflammatory score showed a decrease in the intensity and extent of inflammation between the disease-untreated and the C11C1 disease-treated group. Prekallikrein, high-molecular weight kininogen, factor XI, and factor XII were decreased in the disease-untreated group compared to the C11C1 disease-treated group. T-kininogen was increased in the disease-untreated group when compared with the C11C1 disease-treated group. Disease-free groups IV and V did not show any sign of inflammation at any time. This study shows that monoclonal antibody C11C1 attenuates plasma kallikrein-kinin system activation, local and systemic inflammation, indicating therapeutic potential in reactive arthritis.

Neoantigens in osteoarthritic cartilage

PURPOSE OF REVIEW

Osteoarthritis has been considered a degenerative disease. However, recent evidence supports involvement of immunologic mechanisms in this pathophysiology: for example, inflammation of synovial tissue is observed in osteoarthritis. In osteoarthritis, the proinflammatory cytokine interleukin-1, which is produced by activated synoviocytes and mononuclear cells and has catabolic effects on chondrocytes, is one of the most involved. The immune reaction would require driving antigens. This review describes autoantigens in osteoarthritis and discusses their roles in triggering and/or perpetuating synovitis and joint cartilage destruction in osteoarthritis.

RECENT FINDINGS

Several autoantigens/autoantibodies have been reported in osteoarthritis, such as the cartilage intermediate layer protein. Furthermore, recent comprehensive proteomic surveillance has revealed that comparable numbers of autoantigens were detected in osteoarthritis and rheumatoid arthritis, and that some of them were recognized predominantly in osteoarthritis rather than in rheumatoid arthritis. In addition, it was revealed that the cartilage intermediate layer protein immunization of mice developed calcification of tendons, thus indicating that autoimmunity modulates functions of target molecules.

SUMMARY

Osteoarthritis-specific autoantigens may drive chronic synovitis and may thereby contribute to production of cytokines to upregulate proteases, which lead to chondrocyte and cartilage damage. In addition, autoimmunity may damage joint components by modulating functions of the target molecules.

Proteomic surveillance of autoimmunity in osteoarthritis: identification of triosephosphate isomerase as an autoantigen in patients with osteoarthritis

OBJECTIVE

Autoimmunity to proteins, such as type II collagen and cartilage intermediate layer protein, that are produced by chondrocytes has been reported in patients with osteoarthritis (OA) as well as in patients with rheumatoid arthritis (RA). However, it remains to be determined whether the overall specificities of the autoimmunity differ between OA and RA patients. This study sought to clarify the differences by applying proteomic surveillance for the detection of autoantigens comprehensively.

METHODS

Serum samples were obtained from 20 patients with OA, 20 patients with RA, and 20 healthy volunteers. Human chondrocyte proteins were separated from the sera by 2-dimensional electrophoresis, and antigenic protein spots were detected by Western blotting. The antigenic proteins were then identified by mass fingerprinting. The antigenicity of the identified proteins was confirmed and the prevalence of the autoantibodies in the OA, RA, and other disease groups was determined with the use of recombinant proteins. In addition, autoepitopes were mapped on the antigens.

RESULTS

Nineteen protein spots were recognized only by the OA sera, but not by the RA sera. One of these proteins was identified as triosephosphate isomerase (TPI). IgG-type anti-TPI autoantibodies were detected in 24.7% of the serum samples and 24.1% of the synovial fluid samples from the patients with OA, whereas <6% of the RA and systemic lupus erythematosus samples were positive for anti-TPI. In addition, multiple autoepitopes were identified on TPI.

CONCLUSION

The overall profile of autoimmunity in OA differs from that in RA, which may reflect the OA-specific pathologic role of autoimmunity. The autoantibody to TPI, detected predominantly in the OA samples and produced by the antigen-driven mechanism, has the potential to be used as a diagnostic marker for OA.

Radiologic findings of the lumbar spine in patients with rheumatoid arthritis, and a review of pathologic mechanisms

We have analyzed the radiologic findings on the lumbar spine and the clinical symptoms in patients with rheumatoid arthritis (RA). A total of 106 patients who fulfilled the revised criteria of the American Rheumatism Association were subjected. All of the patients were asked to fill out a questionnaire about the existence of low back pain, leg pain, and leg numbness. Radiologic features of the lumbar spine, including scoliosis, spondylolisthesis, disc space narrowing, endplate erosion, osteophyte, and osteoporosis, were checked. Radiographs of the cervical spine were also taken. The clinical background of RA, such as mutilating disease or not, was assessed. Forty-two patients (40%) had the symptoms of low back pain. Abnormal radiologic findings in lumbar spine were detected in 57%. The prevalence of clinical symptoms tended to be higher in the patients with endplate erosion. Forty-two percent of the patients had both lumbar and cervical lesions. The prevalence of lumbar lesion was not high in the mutilating type of RA, except for facet erosion and severe osteoporosis. The patients with pulse steroid therapy revealed a higher prevalence of vertebral fracture. From these results, we concluded that lumbar lesions were frequently observed in patients with RA. The possibility of lumbar lesions as well as the lesions in the cervical spine and peripheral joints should be examined in patients with RA.

Urokinase, a constitutive component of the inflamed synovial fluid, induces arthritis

Urokinase plasminogen activator (uPA) is an important regulator of fibrinolysis in synovial fluid. An increase of uPA activity and expression of its receptor have been reported in joints of patients with rheumatoid arthritis (RA). The aim of the present study was to assess the arthritogenic capacity of uPA and the mechanisms by which this effect is mediated. uPA was injected into the knee joints of healthy mice, and morphological signs of arthritis were assessed 4 days after the injection. The prerequisite of different leukocyte populations for the development of uPA-triggered arthritis was assessed by selective cell depletion. The inflammatory capacity of uPA was assessed in vitro. Finally, levels of uPA were measured in 67 paired blood and synovial fluid samples from RA patients. The synovial fluid from RA patients displayed higher levels of uPA compared with blood samples. Morphological signs of arthritis were found in 72% of uPA-injected joints compared with in only 18% of joints injected with PBS (P < 0.05). Synovitis was characterised by infiltration of CD4-Mac-1+ mononuclear cells, by the formation of pannus and by occasional cartilage destruction. The absence of monocytes and lymphocytes diminished the frequency of synovitis (P < 0.01), indicating an arthritogenic role of both these leukocyte populations. Synthetic uPA inhibitor downregulated the incidence of uPA-triggered arthritis by 50%. uPA induced arthritis, stimulating the release of proinflammatory cytokines IL-6, IL-1beta and tumour necrosis factor alpha. Accumulation of uPA locally in the joint cavity is a typical finding in erosive RA. uPA exerts potent arthritogenic properties and thus may be viewed as one of the essential mediators of joint inflammation.

Relationship between histological findings and clinical findings in rheumatoid arthritis

The aim of the present study was to compare histological findings and clinical symptoms of patients with advanced stages of rheumatoid arthritis (RA). Synovial tissue specimens were obtained during reconstructive knee surgery from 93 RA patients (18 men; 75 women). The histological assessments of specimens were evaluated using two histological scoring systems reported by Rooney and Koizumi. Clinical symptoms (duration of morning stiffness, joint score, grip strength), laboratory data (erythrocyte sedimentation ratio, C-reactive protein (CRP), rheumatoid factor), X-ray findings (Larsen score) and drug usage were assessed before surgery. Significant statistical correlations between both histological scoring systems were observed; however, there was no significant correlation between the clinical findings and the histological scoring systems. A statistically significant correlation was found between the levels of CRP and Koizumi's scoring system. In addition, Koizumi score correlated significantly to X-ray findings. Rooney's scoring system had an inverse correlation to methotrexate history. Histological findings do not correlate to simultaneous clinical symptoms in advanced RA patients. However, our data indicate that observed histological changes reflect X-ray damage.

The role of TNF-alpha in the pathogenesis of inflammation and joint destruction in rheumatoid arthritis (RA): a study using a human RA/SCID mouse chimera

OBJECTIVE

In order to elucidate which cytokine preferentially stimulates the synovium in patients with rheumatoid arthritis (RA), we investigated the roles of tumour necrosis factor alpha (TNF-alpha) and interleukin 6 (IL-6) using SCID mice engrafted with human RA tissue (SCID-HuRAg).

METHODS

The SCID-HuRAg mice were prepared according to our previously described method. First, SCID-HuRAg mice were treated with chimeric anti-TNF-alpha monoclonal antibody (mAb, 100 microg/mouse) and histological changes were examined 4 weeks after the initial treatment. Secondly, a total of 100 microg of recombinant TNF-alpha or IL-6 (0.6 microg/h) was administered daily to mice using an osmium pump. The histological changes and serum cytokine levels were examined 4 weeks after the initial administration. Human immunoglobulin G (IgG) was administered to mice as a control.

RESULTS

Synovial inflammatory cells were significantly decreased after the anti-TNF-alpha mAb treatment; conversely, the degree of synovial inflammation was significantly exacerbated by TNF-alpha administration. The levels of both IL-6 and TNF-alpha in sera were significantly increased by recombinant TNF-alpha administration, while TNF-alpha levels were unchanged by IL-6 administration. This suggests that TNF-alpha controls IL-6 production. Despite the profound changes in inflammation, we found no effects on bone and no articular cartilage damage was produced by TNF-alpha.

CONCLUSION

This study provides strong evidence that TNF-alpha is a key molecule in the control of the inflammatory changes that occur in the RA synovium. In addition, TNF-alpha regulates IL-6 production. However, other inflammatory pathways independent of TNF-alpha may contribute to the bone and cartilage damage seen in RA.