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1.  Characterisation of a dendritic cell subset in synovial tissue which strongly expresses Jak/STAT transcription factors from patients with rheumatoid arthritis 
Annals of the Rheumatic Diseases  2007;66(8):992-999.
To characterise the phenotype of the putative dendritic cells strongly expressing Jak3 and STAT4, which have been previously identified in the synovial tissue of patients with active rheumatoid arthritis (RA).
Synovial biopsy specimens were obtained at arthroscopy from 30 patients with active RA (42 synovial biopsies). Immunohistological analysis was performed using monoclonal antibodies to detect dendritic cell subsets, including activation markers and cytokines relevant to dendritic cell function. Co‐localisation of cell surface markers and cytokines was assessed primarily using sequential sections, with results confirmed by dual immunohistochemistry and immunofluorescence with confocal microscopy.
The dendritic cells identified in RA synovial tissue that strongly express Jak3 also strongly express STAT4 and STAT 6 and are correlated with the presence of serum rheumatoid factor. These cells are not confined to a single dendritic cell subset, with cells having phenotypes consistent with both myeloid‐ and plasmacytoid‐type dendritic cells. The activation status of these dendritic cells suggests that they are maturing or mature dendritic cells. These dendritic cells produce IL12 as well as interferon α and γ.
The close correlation of these dendritic cells with the presence of serum rheumatoid factor, a prognostic factor for worse disease outcome, and the strong expression by these cells of components of the Jak/STAT transcription factor pathway suggest a potential therapeutic target for the treatment of RA.
PMCID: PMC1954703  PMID: 17223651
rheumatoid arthritis; myeloid dendritic cells; plasmacytoid dendritic cells; IL12; interferon alpha; interferon gamma
2.  Changes in synovial tissue Jak‐STAT expression in rheumatoid arthritis in response to successful DMARD treatment 
Annals of the Rheumatic Diseases  2006;65(12):1558-1564.
Modulation of Jak‐STAT signalling may provide an effective therapeutic strategy in inflammatory arthritis (IA).
To examine the effect of successful disease‐modifying antirheumatic drug (DMARD) treatment on the expression of Jak‐STAT in a cohort of patients with active rheumatoid arthritis.
Synovial tissue biopsy specimens from 16 patients with active rheumatoid arthritis, taken before and after initiation of DMARD treatment, were examined for the presence of janus kinase (Jak)3, signal transducer and activator of transcription (STAT)1, STAT4 and STAT6 expression using immunohistochemistry.
Successful treatment with DMARDs results in reduction in STAT1 expression in the lining, and STAT1 and STAT6 in the sublining of rheumatoid arthritis synovial tissue. Although the overall expression of STAT4 and Jak3 was not significantly altered by DMARD treatment, there was a significant reduction in the expression of the STAT4 and Jak3 bright cells, thought to be an activated dendritic cell subpopulation.
Results show that Jak3, STAT1, STAT4 expression and STAT6 sublining expression decrease in response to successful treatment of rheumatoid arthritis with standard DMARDs. Therefore, altering the expression of these pathways may represent an alternative treatment option, either through promoting up‐regulation of inhibitory pathways, or suppressing inflammatory paths.
PMCID: PMC1798468  PMID: 16760256
3.  Expression of Jak3, STAT1, STAT4, and STAT6 in inflammatory arthritis: unique Jak3 and STAT4 expression in dendritic cells in seropositive rheumatoid arthritis 
Annals of the Rheumatic Diseases  2005;65(2):149-156.
Modulation of Jak‐STAT signalling may provide an effective therapeutic strategy in inflammatory arthritis.
To document Jak‐STAT expression in a cohort of patients with active rheumatoid arthritis (RA), spondyloarthritis (SpA), and osteoarthritis (OA) and compare these subsets with normal synovial tissue.
Synovial tissue biopsy specimens from patients with RA, OA, and SpA and histologically normal tissue (n = 10 in each arthritis group) were examined for the presence of Jak3, STAT1, STAT4, and STAT6 expression using immunohistochemistry. Phenotyping was performed using immunohistochemistry and immunofluorescence. Clinical and serological characteristics of patients with RA expressing Jak3‐STAT4 were assessed.
STAT1, STAT4, and Jak3 protein expression was generally increased in inflammatory arthritis. In contrast, STAT6 expression was relatively heterogeneous. A subpopulation of CD1a positive dendritic cells unique to seropositive patients with RA was detected. These cells showed intense protein expression for Jak3, STAT4, and STAT6.
CD1a positive dendritic cells intensely express Jak3, STAT4, and STAT6 in seropositive RA tissue and may be an alternative marker for dendritic cells in their early stages of activation as well as providing a tool for identifying RA at the level of the synovium. Jak3 inhibition may be a potential therapeutic target to prevent dendritic cell maturation in RA. STAT1 expression is increased in inflammatory arthritis, suggesting that its pro‐apoptotic and anti‐inflammatory effects cannot effectively counteract inflammation. STAT6 expression is heterogeneous in synovium, suggesting a possible homoeostatic role in addition to any anti‐inflammatory effects.
PMCID: PMC1798020  PMID: 16096332
dendritic cells; rheumatoid arthritis; transcription factors
4.  T cells, fibroblast-like synoviocytes, and granzyme B+ cytotoxic cells are associated with joint damage in patients with recent onset rheumatoid arthritis 
Annals of the Rheumatic Diseases  2004;63(5):483-488.
Objective: To determine immunohistological markers in synovial tissue of patients with early rheumatoid arthritis (RA) which are associated with unfavourable disease outcome.
Methods: Synovial tissue was obtained from 36 patients with RA within 1 year after the initial symptoms and before starting disease modifying antirheumatic drug treatment. Clinical, laboratory, and radiological assessments (Larsen score) were performed at the time of the biopsy and at the end of follow up (mean 58 months, range 38–72). Immunohistological analysis was performed to detect T cells, B cells, plasma cells, fibroblast-like synoviocytes (FLS), macrophages, and granzyme B+ cytotoxic cells. The sections were evaluated by digital image analysis.
Results: Patients were divided into two groups based upon the radiological progression per year of follow up: group I with mild progression (n = 20; Larsen <2 points/year); group II with more severe progression (n = 16; Larsen ⩾2 points/year). Regression analysis with a univariate model showed that the numbers of granzyme B+ cytotoxic cells (relative risk (RR) = 12, p = 0.003), T cells (RR = 11, p = 0.013), and FLS (RR = 10, p = 0.020) discriminated between groups I and II. A multivariate model demonstrated that the numbers of T cells (RR = 1.2, p = 0.015) and FLS (RR = 1.4, p = 0.013) were independent discriminators between groups I and II.
Conclusion: The numbers of granzyme B+ cytotoxic cells, T cells, and FLS in synovial tissue of patients with RA are related to the severity of joint damage. The data suggest a pathogenetic role for these cells in the process of joint damage.
PMCID: PMC1755001  PMID: 15082476
5.  Microarchitecture and protective mechanisms in synovial tissue from clinically and arthroscopically normal knee joints 
Annals of the Rheumatic Diseases  2003;62(4):303-307.
Background: Synovial biopsies are used to study synovial immunopathology and are increasingly applied for the evaluation of new therapeutic strategies in chronic arthritis. Therefore, it is essential to be informed on the complete spectrum of synovial immunopathology.
Objective: To describe the cellular content, cytokine and cell adhesion molecule expression in synovial tissue from clinically and arthroscopically normal knees.
Methods: Synovial tissue was obtained from 20 normal subjects at the time of knee joint arthroscopy for unexplained knee pain. Tissue sections were studied for basic histopathology and for a range of cell surface markers, cytokines, and cell adhesion molecules by immunoperoxidase staining. Stained sections were evaluated by semiquantitative scoring and digital image analysis.
Results: Normal synovial tissue is composed predominantly of fibrofatty areolar tissue, with a variable thickness of intimal lining, composed of both CD68 positive macrophages and CD55 positive fibroblast-like synoviocytes. Interleukin 1 receptor antagonist (IL1Ra) was frequently detected in the synovial membrane of normal subjects (mean (SD) integrated optical density (IOD)=3809.6 (3893.9)), but both tumour necrosis factor α (TNFα) and interleukin 1ß (IL1ß) were rarely detected. In addition, cell adhesion molecules were rarely detected in the normal synovial membrane, with the exception of intercellular cell adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1). Osteoprotegerin (OPG) expression was abundant on synovial lining macrophages (mean (SD) IOD=5276 (4716) as well as endothelial cells (mean (SD) IOD=557 (226)), but receptor activator of nuclear factor κ ligand (RANKL) expression was rarely seen.
Conclusions: The normal synovial membrane has a variable architecture, including thickness of the lining and the subintimal cell infiltrate, with little inflammatory cytokine production or expression of cell adhesion molecules. The excess of OPG expression over RANKL and IL1Ra over IL1 may be important for protection against joint damage
PMCID: PMC1754505  PMID: 12634226
6.  Receptor activator NF-κB ligand (RANKL) expression in synovial tissue from patients with rheumatoid arthritis, spondyloarthropathy, osteoarthritis, and from normal patients: semiquantitative and quantitative analysis 
Annals of the Rheumatic Diseases  2002;61(12):1047-1054.
Objectives: To compare receptor activator of NF-κB ligand (RANKL) production in the synovial tissue from patients with active rheumatoid arthritis (RA), inactive RA, spondyloarthropathies (SpA), osteoarthritis, and from normal subjects. In addition, to establish the cell lineages expressing RANKL in these tissues.
Methods: Immunohistological analysis of frozen synovial tissue biopsy specimens was performed using a monoclonal antibody (mAb) to detect RANKL. Sections were evaluated by computer assisted image analysis and semiquantitative analysis to compare RANKL expression between groups. Dual and sequential labelling with mAb RANKL and cell lineage specific monoclonal antibodies were used to determine the types of cells expressing RANKL.
Results: Higher levels of RANKL were expressed in tissues from patients with active RA and SpA than in tissues from patients with inactive RA, osteoarthritis, and from normal subjects. RANKL protein was associated with CD3 antigen-positive lymphocytes and some macrophages. RANKL was predominantly associated with activated, memory T cells (CD45Ro positive cells) in patients with active RA and spondyloarthropathy (SpA).
Conclusions: The highest levels of RANKL were detected in patients with RA with active synovitis and in some patients with SpA. An increase in RANKL in the inflamed joint of patients with RA, produced by infiltrating activated T cells and macrophages, is likely to be an important cause of joint erosions in RA.
PMCID: PMC1753975  PMID: 12429533
7.  Measurement of cytokine and adhesion molecule expression in synovial tissue by digital image analysis 
Annals of the Rheumatic Diseases  2001;60(3):296-298.
OBJECTIVE—Digital image analysis (DIA) offers the opportunity to quantify the stained area and staining intensity when synovial tissue (ST) is investigated by immunohistochemical analysis. This study aimed at determining the sensitivity of DIA compared with semiquantitative analysis (SQA).
METHODS—Paired ST samples were obtained from the knee joint of 10 patients with rheumatoid arthritis (RA) with active disease and after follow up when complete clinical remission was achieved. ST samples of 10 subjects with non-inflammatory knee pain served as controls. Immunohistochemistry with antibodies against interleukin 1β (IL1β) and vascular cell adhesion molecule 1 (VCAM-1) was applied using two staining protocols with 3-amino-9-ethylcarbazole (AEC) or p-diethylaminobenzaldehyde (DAB) as dye. All sections were analysed semiquantitatively (0-4) and DIA of up to a maximum of 60 high power fields (HPF). The average integrated optical density was calculated as the product of the stained area (corrected for total tissue area) and the optical density.
RESULTS—Both SQA and DIA enabled the assessment of differences in IL1β and VCAM-1 expression between ST from active RA, RA in remission, and controls. SQA and DIA showed excellent correlations (IL1β rs=0.867; p<0.0001: VCAM-1 rs=0.828; p<0.0001). A limited analysis of one region with six HPF still allowed adequate discrimination compared with an extended analysis of three regions with a total of 60 HPF. In general, the red dye (AEC) resulted in better discrimination than the brown (DAB) staining.
CONCLUSION—DIA offers a reliable, reproducible, and sensitive analysis of ST sections stained for cytokines and adhesion molecules.

PMCID: PMC1753569  PMID: 11171698

Results 1-7 (7)