Synovial Histopathology Research Articles

Single injection of intra-articular autologous protein solution in horses with acute interleukin-1B-induced synovitis decreases joint pathology scores.

Autologous protein solution (APS) has been shown to decrease lameness in horses with osteoarthritis (OA). Synovitis is an early driver of OA, providing an opportunity to intervene in the progression of disease via intra-articular (IA) therapeutics. The objective of this study was to investigate the effects of a single IA APS injection in horses with interleukin-1β (IL-1β)-induced synovitis. We hypothesised that APS would decrease joint swelling and lameness, improve synovial fluid parameters and improve joint pathology scores in horses compared with untreated controls. Randomised controlled in vivo experiment. Synovitis was induced with IL-1β (65 ng) in one randomly selected tarsocrural joint. Twenty-four hours later, joints were treated with APS (Pro-Stride®) (n = 12) or left as untreated controls (n = 6). Lameness examinations and joint circumference measurements were performed on Days 0 (prior to IL-1β), 1 (prior to APS), 2, 4, 7 and 14. Synovial fluid, obtained on the same days, was analysed for protein concentration, nucleated cell count, and cytokine (IL-1β, TNF-α, IFN-γ, IL-6, IL-10) and prostaglandin E2 (PGE2) concentrations. Gross pathology and synovial membrane histopathology scoring was performed on APS-treated (n = 5), untreated control (n = 4) and normal (n = 9) tarsocrural joints. APS did not decrease lameness or joint circumference compared with untreated controls. Synovial fluid parameters were not different between treatment groups. APS treatment did significantly decrease gross and histopathology scores. Main limitations included the use of an induced model of the synovitis, inter-horse variability in the response to IL-1β and likely variability in the constituents of APS from individual horses. APS treatment of tarsocrural joints with synovitis did not significantly improve lameness or alter synovial fluid parameters. APS did lead to significant improvement in gross joint appearance and synovial membrane histology suggesting that APS may have disease-modifying effects.

A standardized approach to evaluation and reporting of synovial histopathology in two surgically induced murine models of osteoarthritis

ObjectiveSynovial pathology has been linked to osteoarthritis (OA) pain in patients. Microscopic grading systems for synovial changes in human OA have been described, but a standardized approach for murine models of OA is needed. We sought to develop a reproducible approach and set of minimum recommendations for reporting of synovial histopathology in mouse models of OA. MethodsCoronal and sagittal sections from male mouse knee joints subjected to destabilization of medial meniscus (DMM) or partial meniscectomy (PMX) were collected as part of other studies. Stains included Hematoxylin and Eosin (H&E), Toluidine Blue (T-Blue) and Safranin O/Fast Green (Saf-O). Four blinded readers graded pathological features (hyperplasia, cellularity, and fibrosis) at specific anatomic locations. Inter-reader agreement of each feature score was determined. ResultsThere was acceptable to very good agreement when using 3-4 individual readers. After DMM and PMX, expected medial predominant changes in hyperplasia and cellularity were observed, with fibrosis noted at 12 weeks post-PMX. Synovial changes were consistent from section to section in the mid-joint area. When comparing stains, H&E and T-blue resulted in better agreement compared to Saf-O stain. ConclusionsTo account for the pathologic and anatomic variability in synovial pathology and allow for a more standardized evaluation that can be compared across studies, we recommend evaluating a minimum set of 3 pathological features at standardized anatomic areas. Further, we suggest reporting individual feature scores separately before relying on a single summed “synovitis” score. H&E or T-blue are preferred, inter-reader agreement for each feature should be considered.

Axl and MerTK regulate synovial inflammation and are modulated by IL-6 inhibition in rheumatoid arthritis

The TAM tyrosine kinases, Axl and MerTK, play an important role in rheumatoid arthritis (RA). Here, using a unique synovial tissue bioresource of patients with RA matched for disease stage and treatment exposure, we assessed how Axl and MerTK relate to synovial histopathology and disease activity, and their topographical expression and longitudinal modulation by targeted treatments. We show that in treatment-naive patients, high AXL levels are associated with pauci-immune histology and low disease activity and inversely correlate with the expression levels of pro-inflammatory genes. We define the location of Axl/MerTK in rheumatoid synovium using immunohistochemistry/fluorescence and digital spatial profiling and show that Axl is preferentially expressed in the lining layer. Moreover, its ectodomain, released in the synovial fluid, is associated with synovial histopathology. We also show that Toll-like-receptor 4-stimulated synovial fibroblasts from patients with RA modulate MerTK shedding by macrophages. Lastly, Axl/MerTK synovial expression is influenced by disease stage and therapeutic intervention, notably by IL-6 inhibition. These findings suggest that Axl/MerTK are a dynamic axis modulated by synovial cellular features, disease stage and treatment.

Identifying Inflammation in Knee Osteoarthritis: Relationship of Synovial Fluid White Blood Cell Count to Effusion-Synovitis on Magnetic Resonance Imaging.

Inflammation is a potential pain generator and treatment target in knee osteoarthritis (OA). Inflammation can be detected on magnetic resonance imaging (MRI) and by synovial fluid white blood cell count (WBC). However, the performance characteristics of synovial fluid WBC for the detection of synovitis have not been established. This study was undertaken to determine the sensitivity and specificity of synovial fluid WBC in identifying inflammation in knee OA using MRI effusion-synovitis as the gold standard. We identified records of patients seen at an academic center with a diagnosis code for knee OA, a procedural code for knee aspiration, and a laboratory order for synovial fluid WBC in the same encounter, as well as an MRI within 12 months of the aspiration. MRIs were read for effusion-synovitis using the MRI OA Knee Score (MOAKS). We dichotomized effusion-synovitis as 1) none or small, or 2) medium or large. We calculated the sensitivity and specificity of synovial fluid WBC using MRI effusion-synovitis (medium/large) as the gold standard. We used the Youden index to identify the best cut point. We included 75 patients. Mean ± SD age was 63 ± 12 years, and 69% were female. The synovial fluid WBC was higher in the medium/large effusion-synovitis group (median 335 [interquartile range (IQR) 312]) than in the none/small group (median 194 [IQR 272]). The optimal cut point was 242, yielding a sensitivity of 71% (95% confidence interval [95% CI] 56-83%) and specificity of 63% (95% CI 41-81%). The sensitivity and specificity of synovial fluid WBC in identifying effusion-synovitis on MRI were limited. Further research is needed to better understand the association between MRI and effusion-synovitis measured by synovial fluid and to determine which measure more strongly relates to synovial histopathology and patient outcomes.

Bone Marrow Mesenchymal Stem Cells Release miR-378a-5p-Carried Extracellular Vesicles to Alleviate Rheumatoid Arthritis

This study investigates whether bone marrow mesenchymal stem cell (BMSC)-derived extracellular vesicles (EVs) can affect rheumatoid arthritis (RA) by delivering microRNA (miR)-378a-5p to regulate the interferon regulatory factor 1/signal transducer and transcription 1 (IRF1/STAT1) axis. We identified RA-associated miRNAs using the GEO microarray dataset GSE121894. We found the most important miRNAs in RA synovial tissues using RT-qPCR. BMSC-derived EVs were ultracentrifuged and cocultured with human synovial microvascular endothelial cells (HSMECs) in vitro. Dual-luciferase and RNA immunoprecipitation studies examined miR-378a-5p’s specific binding to IRF1. We also measured angiogenesis, migration, and proliferation using CCK-8, Transwell, and tube formation assays. Collagen-induced arthritis (CIA) mice models were created by inducing arthritis and scoring it. RA synovial tissues had low miR-378a-5p expression, whereas BMSC-derived EVs had high levels. The transfer of miR-378a-5p by BMSC-derived EVs to HSMECs boosted proliferation, migration, and angiogenesis. miR-378a-5p inhibited IRF1. MiR-378a-5p-containing BMSC-derived EVs decreased STAT1 phosphorylation and HSMEC IRF1 expression. EVs with miR-378a-5p mimic promoted HSMEC proliferation, migration, and angiogenesis, whereas dexmedetomidine inhibited STAT1 phosphorylation. In CIA mice, BMSC-derived EVs containing miR-378a-5p enhanced synovial vascular remodeling and histopathology. Thus, miR-378a-5p from BMSC-derived EVs promotes HSMEC proliferation, migration, and angiogenesis, inactivating the IRF1/STAT1 axis and preventing RA.

Functional Role of Novel Anthranilic Acid Derivatives as Anti-inflammatory Agents

Abstract: Background: The discovery of new cyclooxygenase (COX) inhibitors with high efficacy and safety would be a great achievement in developing anti-inflammatory drugs. This study evaluated the anti-inflammatory activity and the expected side effect of two synthesized anthranilic acid derivatives (JS-3 and JS-4). Materials and Methods: The COX selectivity of compounds was assessed in a whole blood assay. The results were confirmed by molecular docking studies. In vivo anti-inflammatory activity was tested in complete Freund’s adjuvant (CFA)-induced rheumatoid arthritis (RA) in rats. The safety profile was determined by administering a dose three times the therapeutic dose. Results: In vitro COX-2 selectivity of JS-4 was higher than JS-3 (13.70 vs. 5.56). Docking studies supported the higher selectivity of both derivatives against COX-2 than mefenamic acid. Treatment of CFA-arthritic rats with both compounds showed significant (P < 0.01) decreases in paw volume, paw thickness, arthritic index, and inflammatory parameters such as rheumatoid factor, interleukin (IL)-1β, IL-6, prostaglandin (PG) E2, PGI2, and TXB2 compared to untreated RA animals. JS-3 and JS-4 improved synovial joint histopathology and protected against RA-induced pathological changes: splenomegaly, thymomegaly, and cardiomyopathy. Both derivatives produced minimal effects on liver and renal functions, without any ulcerogenic effects. Conclusion: These results suggest that JS-4 is a potential and safe candidate for managing RA without renal, liver, gastrointestinal, or cardiovascular toxicity. Keywords: Cyclooxygenase inhibitors, Anthranilic acid derivatives, Mefenamic acid, Rheumatoid arthritis, Anti-inflammatory, Safety evaluation, Molecular docking.

Anti-inflammatory and Hepatoprotective Effects of Quercetin in an Experimental Model of Rheumatoid Arthritis.

Rheumatoid arthritis (RA) is an autoimmune disease characterized by inflammation in the joints. Although methotrexate (MX) is the first-line treatment, side effects are common. This study aimed to investigate the effects of quercetin (QT) and/or MX on inflammation and systemic toxicity in a rat model of RA. Male Wistar rats were divided into control (C), RA, QT, MX, and QT + MX groups (n=6). The RA induction consisted of three intra-articular injections of methylated bovine serum albumin (1×/week) in the temporomandibular joint (TMJ). QT (25 mg/kg) and/or MX (0.75 mg) administration occurred by oral gavage daily. We performed mechanical hyperalgesia in TMJ, leukocyte recruitment in synovial fluid, histopathology, and immunohistochemistry (TNF-α, IL-17, and IL-10) in synovial membrane and toxicity parameters. The RA showed a reduction in the nociceptive threshold (p<0.001), increase in leukocyte recruitment in synovial fluid (p<0.001), intense inflammatory infiltrate (p<0.001), and intense immunoexpression of TNF-α, IL-17, and IL-10 in the synovial membrane (p<0.001) compared to C (p<0.001). QT and/or MX therapy reduced inflammatory parameters (p<0.001). However, downregulation of IL-10 was observed only in the groups that received MX (p<0.001). Leukocytosis was seen in RA (p<0.05), but QT and/or MX reversed it (p<0.05). MX was associated with pathological changes in the liver and higher levels of transaminases when compared to the other groups (p<0.05). QT co-administered with MX reversed this hepatotoxicity (p<0.05). There were no alterations in the kidney between the groups (p>0.05). QT has potential to support MX therapy, showing anti-inflammatory and hepatoprotective effects in this model.

Biological measures of synovial inflammation predict pain, symptoms, and ultrasound measures of synovitis in knee OA

Purpose: Synovial inflammation (synovitis or effusion-synovitis) measured via clinical imaging (i.e., magnetic resonance imaging (MRI), ultrasound (US)) has been shown to be related to worse outcomes in people with knee OA, including worse pain, higher risk of OA incidence and progression, and increased risk of requiring a total knee arthroplasty (TKA). Recent studies have shown associations between synovial histopathology and structural features of knee OA and MRI measures of synovitis. However, the relationship between histopathology and patient symptoms remains unclear. Histopathology measures of synovial inflammation represent a set of measures that are related to biological disease activity in OA. Therefore, the aim of this study was to establish the link between synovial inflammation and clinical outcomes. Methods: Patients were recruited from the Western Ontario Registry for Early Osteoarthritis (WOREO): Knee Study. Ninety-two people with severe symptoms and radiographic damage (Kellgren-Lawrence (KL) grades 3 or 4) undergoing surgery for end-stage knee OA were included. Patients completed the Knee Injury and Osteoarthritis Outcome Score (KOOS) questionnaire specific to each knee and a self-reported patient global assessment (PGA). An investigator global assessment (IGA) was also completed for each patient. Musculoskeletal-US was used to measure effusion-synovitis in suprapatellar mid-line, lateral, and medial windows (0-3; None-Severe; summed (0-9) and maximum effusion depth (mm). Power Doppler signal was also assessed as absent or present (0 or 1). Lateral suprapatellar synovial biopsies were obtained at time of surgery. Routine histopathology was scored in six domains, on 5 slides per patient; mean scores were binned into categories 0, 0.5-1.5, and 2-3 (none, mild, moderate-severe). Composite histopathology scores were created based on previously published literature, principal component analysis (Eigen values ≥ 1.0), and biological rationale. We fitted a series of multivariate linear or logistic regression models to evaluate the association of histopathology (individual and composite) scores with clinical outcomes and US imaging measures of synovitis. All analyses were adjusted for age, sex, and body mass index (BMI). Robust sandwich estimators were used. Results include unstandardized β coefficients or odds ratios (OR) with 95% confidence intervals (CIs). All analyses completed using StataIC 15.1. Results: A total of 92 patients were included (Table 1). Of the 6 histopathology domains, more severe perivascular edema was most strongly associated with lower (worse) KOOS pain, ADL, and QoL subscale scores (Table 2). Synovial lining and sub-synovial infiltrate scores were significantly associated with more severe effusion-synovitis measured by US grading and maximum effusion depth (Table 3). Vascularization was associated with higher synovitis score, while more severe fibrosis was associated with high QoL scores (Table 2) and lower US synovitis score (Table 3). Synovial histopathology principal components accounted for approximately 70% of the variance in the dataset but there were minimal associations with clinical and imaging outcomes (Table 4). The histopathology inflammatory composite scores were most strongly associated with KOOS subscale scores (Table 4). Conclusions: Inflammation measured with synovial histopathology is associated with knee-specific pain, symptoms and US imaging measures of inflammation in patients with end-stage knee OA. These findings may help us to better understand OA overall. We provide biological evidence supporting the known relationship between knee inflammation and OA outcomes, which is largely based on imaging assessment in the literature.View Large Image Figure ViewerDownload Hi-res image Download (PPT)View Large Image Figure ViewerDownload Hi-res image Download (PPT)View Large Image Figure ViewerDownload Hi-res image Download (PPT)

Effects of Catalpa Alcohol From Rehmannia glutinosa on Calcium-Binding Protein, Interleukin-1β, and Galectin-3 in Synovial Tissues of Rats With Knee Osteoarthritis

Objectives We aimed to evaluate the effects of catalpa alcohol from Rehmannia glutinosa on the expressions of calcium-binding protein (S100A12), interleukin-1β (IL-1β), and galectin-3 in the synovium of rats with early knee osteoarthritis (KOA). Methods Fifty-two adult male Wistar rats aged 3 to 8 weeks were divided into normal control (n = 16), model (n = 12), low-dose (n = 12), and high-dose groups (n = 12). On the 10th day after modeling, 6 rats in normal control group and 6 in the other 3 groups were randomly selected. X-ray and 3-dimensional computed tomography (3D CT) images of the left knee joint were taken under live anesthesia. The joint cavity of sacrificed rats was opened to observe cartilage surface. After 28 consecutive days of administration, the synovial tissue of left knee joint was collected. Results The S100A12, IL-1β, and galectin-3 levels in synovial tissue were detected by immunohistochemistry and ELISA. There were articular cartilage defects in left knees. Radiologic examination showed significant joint space narrowing and hyperplasia, and 3D CT joint space value decreased (P &amp;lt; 0.05). The Mankins and OARSI scores of synovial histopathology were significantly different (P &amp;lt; 0.05). The S100A12, IL-1β, and galectin-3 levels in synovial tissue of the model group significantly exceeded those of the normal control group (P &amp;lt; 0.01). Compared with the model group, such levels of low-dose (P &amp;lt; 0.05) and high-dose groups (P &amp;lt; 0.01) were significantly lower. Conclusions The S100A12, IL-1β and galectin-3 levels in synovium tissue decreased with rising concentration of catalpa alcohol from R. glutinosa. Therefore, this drug is potentially suitable for inhibiting an inflammatory response to delay the progression of KOA.

A Pauci-Immune Synovial Pathotype Predicts Inadequate Response to TNFα-Blockade in Rheumatoid Arthritis Patients.

Objectives: To assess whether the histopathological features of the synovium before starting treatment with the TNFi certolizumab-pegol could predict clinical outcome and examine the modulation of histopathology by treatment.Methods: Thirty-seven RA patients fulfilling UK NICE guidelines for biologic therapy were enrolled at Barts Health NHS trust and underwent synovial sampling of an actively inflamed joint using ultrasound-guided needle biopsy before commencing certolizumab-pegol and after 12-weeks. At 12-weeks, patients were categorized as responders if they had a DAS28 fall >1.2. A minimum of 6 samples was collected for histological analysis. Based on H&E and immunohistochemistry (IHC) staining for CD3 (T cells), CD20 (B cells), CD138 (plasma cells), and CD68 (macrophages) patients were categorized into three distinct synovial pathotypes (lympho-myeloid, diffuse-myeloid, and pauci-immune).Results: At baseline, as per inclusion criteria, DAS28 mean was 6.4 ± 0.9. 94.6% of the synovial tissue was retrieved from the wrist or a metacarpophalangeal joint. Histological pathotypes were distributed as follows: 58% lympho-myeloid, 19.4% diffuse-myeloid, and 22.6% pauci-immune. Patients with a pauci-immune pathotype had lower levels of CRP but higher VAS fatigue compared to lympho- and diffuse-myeloid. Based on DAS28 fall >1.2, 67.6% of patients were deemed as responders and 32.4% as non-responders. However, by categorizing patients according to the baseline synovial pathotype, we demonstrated that a significantly higher number of patients with a lympho-myeloid and diffuse-myeloid pathotype in comparison with pauci-immune pathotype [83.3% (15/18), 83.3 % (5/6) vs. 28.6% (2/7), p = 0.022) achieved clinical response to certolizumab-pegol. Furthermore, we observed a significantly higher level of post-treatment tender joint count and VAS scores for pain, fatigue and global health in pauci-immune in comparison with lympho- and diffuse-myeloid patients but no differences in the number of swollen joints, ESR and CRP. Finally, we confirmed a significant fall in the number of CD68+ sublining macrophages post-treatment in responders and a correlation between the reduction in the CD20+ B-cells score and the improvement in the DAS28 at 12-weeks.Conclusions: The analysis of the synovial histopathology may be a helpful tool to identify among clinically indistinguishable patients those with lower probability of response to TNFα-blockade.

The relationship between synovial inflammation, structural pathology, and pain in post-traumatic osteoarthritis: differential effect of stem cell and hyaluronan treatment

BackgroundSynovitis is implicated in the severity and progression of pain and structural pathology of osteoarthritis (OA). Increases in inflammatory or immune cell subpopulations including macrophages and lymphocytes have been reported in OA synovium, but how the particular subpopulations influence symptomatic or structural OA disease progression is unclear. Two therapies, hyaluronan (HA) and mesenchymal stem cells (MSCs), have demonstrated efficacy in some clinical settings: HA acting as device to improve joint function and provide pain relief, while MSCs may have immunomodulatory and disease-modifying effects. We used these agents to investigate whether changes in pain sensitization or structural damage were linked to modulation of the synovial inflammatory response in post-traumatic OA.MethodsSkeletally mature C57BL6 male mice underwent medial-meniscal destabilisation (DMM) surgery followed by intra-articular injection of saline, a hyaluronan hexadecylamide derivative (Hymovis), bone marrow-derived stem cells (MSCs), or MSC + Hymovis. We quantified the progression of OA-related cartilage, subchondral bone and synovial histopathology, and associated pain sensitization (tactile allodynia). Synovial lymphocytes, monocyte/macrophages and their subpopulations were quantified by fluorescent-activated cell sorting (FACS), and the expression of key inflammatory mediators and catabolic enzyme genes quantified by real-time polymerase chain reaction (PCR).ResultsMSC but not Hymovis significantly reduced late-stage (12-week post-DMM) cartilage proteoglycan loss and structural damage. Allodynia was initially reduced by both treatments but significantly better at 8 and 12 weeks by Hymovis. Chondroprotection by MSCs was not associated with specific changes in synovial inflammatory cell populations but rather regulation of post-injury synovial Adamts4, Adamts5, Mmp3, and Mmp9 expression. Reduced acute post-injury allodynia with all treatments coincided with decreased synovial macrophage and T cell numbers, while longer-term effect on pain sensitization with Hymovis was associated with increased M2c macrophages.ConclusionsThis therapeutic study in mice demonstrated a poor correlation between cartilage, bone or synovium (histo)pathology, and pain sensitization. Changes in the specific synovial inflammatory cell subpopulations may be associated with chronic OA pain sensitization, and a novel target for symptomatic treatment.

Amplifying the concept of psoriatic arthritis: The role of autoimmunity in systemic psoriatic disease.

Psoriatic arthritis (PsA) is a chronic inflammatory arthritis that may be present in near 30% of patients affected by psoriasis (PsO), clinically characterized by inflammation of periarticular (e.g., enthesis) and articular structures. Recently, an autoimmune footprint of PsA pathogenesis has been demonstrated with the presence of autoantigens and related autoantibodies in PsA patients' sera. In this context, histological features of PsA synovitis supports the relevance of an autoimmune pathogenesis of the disease. Since there is no currently validated test for PsA, the analysis of PsA synovial tissue revealed pathognomonic characteristics of PsA that may support the clinician in the clinical practice. PsA synovitis is characterized by a sublining infiltrate with T and B cells, vascular proliferation and a relative thin lining layer of proliferating intimal synoviocytes. PsA synovial histopathology shows that ectopic lymphoid-neogenesis with an increase of IL-23 expression. These new pathogenetics features and the systemic nature of the disease raised the concept of a Systemic Psoriatic Disease (SysPsD), characterized by multiple extra-cutaneous and -articular manifestations, highlightening the great heterogeneity of this condition. SyPsD represents a heterogeneous chronic inflammatory condition with a wide spectrum of phenotypical manifestations. The purpose of this review is to describe the new pathogenetic mechanisms and the different clinical pictures of SysPsD, with the ultimate goal of improving the knowledge of this heterogeneous chronic inflammatory condition.

Effect of biological agents on synovial tissues from patients with rheumatoid arthritis

Objectives: To compare the inflammation of synovium before and after biological agents in the patients with rheumatoid arthritis (RA) and to investigate the association between synovial histopathology and disease activity.Methods: Synovial tissues were obtained during operations from 34 patients before and after treatment with biological agents. The synovial tissue was evaluated using hematoxylin and eosin staining. Synovial histopathology was evaluated by Rooney score.Results: The Rooney score was also significantly decreased after treatment with biological agents in all items (p < .001). After the treatment with biological agents, Moderate disease activity group had significantly higher scores of focal aggregates of lymphocytes (p = .02), diffuse infiltrates of lymphocytes (p = .019), and the Rooney total scores (p = .002) than remission and low disease activity groups.Conclusion: Our results demonstrated that biological agents significantly decreased the RA synovial inflammation and synovial histopathology in sublining layer reflected disease activity.

What does power Doppler signal indicate in rheumatoid synovitis? A point of view from synovial histopathology

To clarify the nature of power Doppler (PD) signals in rheumatoid synovium and to establish the connection between PD signals and active inflammation using synovial histopathology. Ten adult patients (median age 57.0 years, 9 women and one man) with rheumatoid arthritis (RA) were enrolled and received ultrasound (US) examinations. US-guided synovial biopsies using core needle were performed in 7 knees, 2 wrists and one elbow. Each patient had one joint biopsied. In total, 11 synovial specimens were obtained for hematoxylin and eosin staining and histopathologic examinations. The US examinations revealed prominent synovial hypertrophy in all biopsied joints. Six synovial specimens were PD-positive (from 3 knees, 2 wrists and 1 elbow) while 5 synovial specimens were PD-negative (from 5 knees). In comparison with the PD-negative synovial specimens, the PD-positive synovial specimens had significantly more lymphocyte infiltration, vessel proliferation and lining hyperplasia on histologic examination. There was no significant difference in fibrin exudate and stromal fibrosis between the PD-positive and the PD-negative synovial specimens. PD signals in rheumatoid synovium indicate active inflammation and vascularization supported by synovial histopathology. Our study establishes the connection between synovial PD signals and active synovitis in RA.

Differential effects of IL-6 blockade tocilizumab and TNF inhibitors on angiogenesis in synovial tissues from patients with rheumatoid arthritis

Objective: To compare the influences of tocilizumab (TCZ) and TNF inhibitors (TNFi) on the angiogenesis in synovial tissues of rheumatoid arthritis (RA).Methods: Synovial tissues were obtained during joint operations from 13 RA patients treated with TCZ for at least 4 months with or without previous use of TNFi, from 13 RA patients with TNFi alone and from 10 RA patients with only conventional synthetic DMARDs (csDMARDs). Synovial tissues were evaluated by hematoxylin and eosin stain as well as by immunohistological staining with anti-CD31 in which the microvessel densities (MVD) were quantitated. Synovial histopathology was scored for various components.Results: The most remarkable change in the synovium with TCZ was reduced angiogenesis as well as degeneration of lining layers irrespective of the previous use of TNFi. Thus, MVD in patients treated with TCZ with or without previous TNFi were significantly decreased compared with those in patients with TNFi alone or with csDMARDs. Moreover, MVD was significantly correlated with lining layer proliferation, but not with synovial stromal proliferation or inflammatory changes.Conclusions: These results demonstrated that inhibition of angiogenesis is a unique action of TCZ. Moreover, the data also suggest that lining layers proliferation might be closely associated with angiogenesis.

Intra-articular interleukin-1 receptor antagonist (IL1-ra) microspheres for posttraumatic osteoarthritis: in vitro biological activity and in vivo disease modifying effect.

BackgroundInterleukin-1 receptor antagonist (IL-1 ra) can be disease-modifying in posttraumatic osteoarthritis (PTOA). One limitation is its short joint residence time. We hypothesized that IL-1 ra encapsulation in poly (lactide-co-glycolide) (PLGA) microspheres reduces IL-1 ra systemic absorption and provides an enhanced anti-PTOA effect.MethodsIL-1 ra release kinetics and biological activity: IL-1 ra encapsulation into PLGA microsphere was performed using double emulsion solvent extraction. Lyophilized PLGA IL-1 ra microspheres were resuspended in PBS and supernatant IL-1 ra concentrations were assayed. The biological activity of IL-1 ra from PLGA IL-1 ra microspheres was performed using IL-1 induced lymphocyte proliferation and bovine articular cartilage degradation assays. Systemic absorption of IL-1 ra following intra-articular (IA) injection of PLGA IL-1 ra or IL-1 ra: At 1, 3, 6, 12 and 24 h following injection of 50 μl PLGA IL-1 ra (n = 6) or IL-1 ra (n = 6), serum samples were collected and IL-1 ra concentrations were determined. Anterior cruciate ligamenttransection (ACLT) and IA dosing: ACLT was performed in 8–10 week old male Lewis rats (n = 42). PBS (50 μl; n = 9), IL-1 ra (50 μl; 5 mg/ml; n = 13), PLGA IL-1 ra (50 μl; equivalent to 5 mg/ml IL-1 ra; n = 14) or PLGA particles (50 μl; n = 6) treatments were performed on days 7, 14, 21 and 28 following ACLT. Cartilage and synovial histopathology: On day 35, animal ACLT joints were harvested and tibial cartilage and synovial histopathology scoring was performed.ResultsPercent IL-1 ra content in the supernatant at 6 h was 13.44 ± 9.27 % compared to 34.16 ± 12.04 %, 47.89 ± 12.71 %, 57.14 ± 11.71 %, and 93.90 ± 8.50 % at 12, 24, 48 and 72 h, respectively. PLGA IL-1 ra inhibited lymphocyte proliferation and cartilage degradation similar to IL-1 ra. Serum IL-1 ra levels were significantly lower at 1, 3, and 6 h following PLGA IL-1 ra injection compared to IL-1 ra. Cartilage and synovial histopathology scores were significantly lower in the PLGA IL-1 ra group compared to PBS and PLGA groups (p < 0.001).ConclusionsIL-1 ra encapsulation in PLGA microspheres is feasible with no alteration to IL-1 ra biological activity. PLGA IL-1 ra exhibited an enhanced disease-modifying effect in a PTOA model compared to similarly dosed IL-1 ra.

Alpha-1-anti-trypsin-Fc fusion protein ameliorates gouty arthritis by reducing release and extracellular processing of IL-1β and by the induction of endogenous IL-1Ra

ObjectivesIn the present study, we generated a new protein, recombinant human alpha-1-anti-trypsin (AAT)-IgG1 Fc fusion protein (AAT-Fc), and evaluated its properties to suppress inflammation and interleukin (IL)-1β in a mouse...

Towards a stratified targeted approach with biologic treatments in rheumatoid arthritis: role of synovial pathobiology.

Rheumatoid Arthritis (RA) is a chronic, inflammatory, autoimmune disease affecting diarthrodial joints and extra-articular tissues; in the absence of an effective treatment, it is characterized by persistent symmetrical and erosive synovitis which leads to structural joint damage and lifelong disability. Several autoantibodies have been associated with RA such as rheumatoid factor (RF) and anti-citrullinated protein antibodies (ACPA). B cells have been shown to play a crucial role in the pathogenesis of RA by producing autoantibodies and promoting synovial inflammation through antigen presentation, T cells activation and cytokines production [1]. Although biologic agents have notably improved disease outcome and patients' quality of life, currently around 30-40% of subjects do not respond to treatment and the mechanisms leading to resistance are still not known [2]. For this reason, new prognostic biomarkers and predictors of response are needed. We and others have postulated that the development of biomarkers for patients' stratification prior therapeutic intervention may be possible through a better understanding of the different histopathological patterns present both in early and established individual RA patient and the related underlying cellular and molecular mechanisms. To date, Tumor Necrosis Factor (TNF)-α has been shown to be one of the master elements of inflammation in RA; however, even though therapies aimed at blocking this key cytokine have emerged as a major tool in the treatment of RA, a large proportion of patients (approximately 30-40%) do not achieve a meaningful clinical response assessed by either the American College of Rheumatology (ACR) or the European League Against Rheumatism (EULAR) criteria. The same limitation can be applied to the use of rituximab, a chimeric monoclonal antibody directed against CD20, which is uniquely expressed by all B-lymphocytes during the maturation process from late stage pro-B cells to memory cells. The clinical efficacy of rituximab has been proved by several clinical studies [3] but it is highly variable. Currently, NICE guidelines recommend rituximab in patients with inadequate response to a first-line biologic therapy, including at least one anti-TNFα agent independently of their pre-treatment chance to respond. In all cases, whether considering biologics used for several years in RA patients (anti-TNFα or rituximab) or relatively newer biologics in clinical use (i.e. tocilizumab, an anti-interleukin (IL) -6 receptor blocking monoclonal antibody or abatacept, a CTLA4 inhibitor fusion protein designed to target the T cell co-stimulatory signal mediated through the CD28-CD80/86 pathway), no validated biomarkers predictive of clinical response currently exist. Consequently, to date a "trial-and-error" approach is used in the prescription of biologics in RA, which has the obvious disadvantage of potentially exposing patients to drugs that they may not respond, with potential unnecessary side-effects, delaying use of an effective treatment and causing a significant economic burden to society. Therefore, identifying pre-treatment predictors of response with a customized stratification approach would be of invaluable importance in RA, also in consideration of the large number of biologics in development targeting novel pathways currently being tested in clinical trials. In this manuscript, we review existing data and provide future perspectives with regard to the role of synovial histopathology as a potential prognostic biomarker for patient stratification in RA, in particular regarding the use of specific biologic therapies.

Intramuscular hemangioma mimicking synovial sarcoma on fine-needle aspiration cytology

A 13-year-old boy presented to our hospital with clinical complaint of lump in knee joint and associated pain for 6 years. Fine-needle aspiration cytology was done and cytology smears showed biphasic pattern composed of spindle cells, epithelial elements, and numerous mast cells. Hence, it was reported as synovial sarcoma and histopathology was advised. Lump was excised successfully. Histopathological sections showed numerous capillary sized blood vessels, cavernous blood vessels, thick walled blood vessels present between skeletal muscle, and adipose tissue. Hence, the diagnosis of intramuscular haemangioma was made. Follow-up was done for 1 year. No recurrence or complications were seen.

Rheumatoid Arthritis: Etiology and Pathogenesis

Rheumatoid arthritis (RA) is among the most common forms of chronic inflammatory arthritis. It affects approximately 1% of adults and is two to three times more prevalent in women than in men. There are no specific laboratory tests for RA; diagnosis depends on a constellation of signs and symptoms that can be supported by serology and radiographs. The disease evolves over many years as a consequence of repeated environmental stress causing inflammation and immune activation followed by a breakdown of tolerance in individuals with a specific genetic background. This review describes the definition of RA; its etiology, including genetics, infections, the role of smoking and citrullination of proteins, and epigenetic mechanisms; and its pathogenesis, including synovial histopathology, bone and cartilage damage, adaptive and innate immunity, and the role of cytokines and intracellular signaling. Tables include the 1987 American Rheumatism Association criteria for the classification of RA and the 2010 American College of Rheumatology/European League Against Rheumatism classification for RA. Figures show citrullinated proteins in airway cells, a section of a proliferative synovium from a patient with a classic RA, and scalloped regions of erosion at the junction between a proliferative inflamed rheumatoid synovium and the bone. This review contains 3 highly rendered figures, 2 tables, and 71 references.