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1.  CD4+CD25+/highCD127low/- regulatory T cells are enriched in rheumatoid arthritis and osteoarthritis joints—analysis of frequency and phenotype in synovial membrane, synovial fluid and peripheral blood 
CD4+CD25+/highCD127low/- regulatory T cells (Tregs) play a crucial role in maintaining peripheral tolerance. Data about the frequency of Tregs in rheumatoid arthritis (RA) are contradictory and based on the analysis of peripheral blood (PB) and synovial fluid (SF). Because Tregs exert their anti-inflammatory activity in a contact-dependent manner, the analysis of synovial membrane (SM) is crucial. Published reports regarding this matter are lacking, so we investigated the distribution and phenotype of Tregs in concurrent samples of SM, SF and PB of RA patients in comparison to those of osteoarthritis (OA) patients.
Treg frequency in a total of 40 patients (18 RA and 22 OA) matched for age and sex was assessed by flow cytometry. Functional status was assessed by analysis of cell surface markers representative of activation, memory and regulation.
CD4+ T cells infiltrate the SM to higher frequencies in RA joints than in OA joints (P = 0.0336). In both groups, Tregs accumulate more within the SF and SM than concurrently in PB (P < 0.0001). Relative Treg frequencies were comparable in all compartments of RA and OA, but Treg concentration was significantly higher in the SM of RA patients (P = 0.025). Both PB and SM Tregs displayed a memory phenotype (CD45RO+RA-), but significantly differed in activation status (CD69 and CD62L) and markers associated with Treg function (CD152, CD154, CD274, CD279 and GITR) with only minor differences between RA and OA.
Treg enrichment into the joint compartment is not specific to inflammatory arthritis, as we found that it was similarly enriched in OA. RA pathophysiology might not be due to a Treg deficiency, because Treg concentration in SM was significantly higher in RA. Synovial Tregs represent a distinct phenotype and are activated effector memory cells (CD62L-CD69+), whereas peripheral Tregs are resting central memory cells (CD62L+CD69-).
PMCID: PMC4060198  PMID: 24742142
2.  TH-17 cells in rheumatoid arthritis 
The aim of this study was to quantify the number of T-helper (TH)-17 cells present in rheumatoid arthritis (RA) synovial fluid (SF) and to determine the level of interleukin (IL)-17 cytokine in RA, osteoarthritis (OA) and normal synovial tissue, as well as to examine SF macrophages for the presence of IL-23, IL-27 and interferon (IFN)-γ.
Peripheral blood (PB) mononuclear cells from normal and RA donors and mononuclear cells from RA SF were examined either without stimulation or after pretreatment with IL-23 followed by stimulation with phorbol myristate acetate (PMA) plus ionomycin (P/I). The abundance of TH-17 cells in RA SF was determined by flow cytometry. IL-17 levels were quantified in synovial tissue from RA, OA and normal individuals by ELISA and IL-23 was identified in SFs by ELISA. RA SF and control in vitro differentiated macrophages were either untreated or treated with the toll-like receptor (TLR) 2 ligand peptidoglycan, and then IL-23, IL-27 and IFN-γ mRNA levels were quantified by real-time polymerase chain reaction (RT-PCR).
Treatment with P/I alone or combined with IL-23 significantly increased the number of TH-17 cells in normal, RA PB and RA SF. With or without P/I plus IL-23, the percentage of TH-17 cells was higher in RA SF compared with normal and RA PB. IL-17 levels were comparable in OA and normal synovial tissues, and these values were significantly increased in RA synovial tissue. Although IL-17 was readily detected in RA SFs, IL-23 was rarely identified in RA SF. However, IL-23 mRNA was significantly increased in RA SF macrophages compared with control macrophages, with or without TLR2 ligation. IL-27 mRNA was also significantly higher in RA SF compared with control macrophages, but there was no difference in IL-27 levels between RA and control macrophages after TLR2 ligation. IFN-γ mRNA was also detectable in RA SF macrophages but not control macrophages and the increase of IFN-γ mRNA following TLR2 ligation was greater in RA SF macrophages compared with control macrophages.
These observations support a role for TH-17 cells in RA. Our observations do not strongly support a role for IL-23 in the generation of TH-17 cells in the RA joint, however, they suggest strategies that enhance IL-27 or IFN-γ might modulate the presence of TH-17 cells in RA.
PMCID: PMC2575607  PMID: 18710567
3.  T Regulatory Cell Numbers and Function in Patients with Antibiotic-Refractory or Antibiotic-Responsive Lyme Arthritis 
Arthritis and rheumatism  2010;62(7):2127-2137.
In a murine model of antibiotic-refractory Lyme arthritis, the numbers of T regulatory cells (Treg) are dramatically reduced. Our goal was to examine Treg numbers and function in human patients with antibiotic-refractory Lyme arthritis.
CD4+ T cell subsets were enumerated in peripheral blood (PB) and synovial fluid (SF) in 12 patients with antibiotic-refractory arthritis and 6 with antibiotic-responsive arthritis. Treg function was examined using Borrelia-specific and non-specific Treg proliferation assays.
In both patient groups, IFN-γ+ TH1 cells in SF were abundant and enriched (~50% of CD4+ T cells). In patients with antibiotic-refractory arthritis, the median percentages of FoxP3+ Treg were significantly higher in SF than PB (12% versus 6%) (P<0.01) or in SF in patients with antibiotic-responsive arthritis (12% versus 5%) (P=0.04). Moreover, in the refractory group, a higher percentage of Treg in SF correlated with a shorter duration to resolution of arthritis (r = −0.74, P = 0.006). In contrast, patients with fewer Treg had suboptimal responses to DMARDs and longer duration of arthritis after antibiotics, and they often required synovectomies for arthritis resolution. In each group, Treg in SF dampened B. burgdorferi-specific proliferative responses, and in 2 patients with refractory arthritis, Treg were functional in non-specific suppression assays.
Treg were functional in patients with antibiotic-refractory arthritis, and in some patients, large numbers of these cells in SF appeared to participate in arthritis resolution. However, as in the murine model, patients with refractory arthritis and low numbers of Treg seemed unable to resolve synovial inflammation.
PMCID: PMC2913315  PMID: 20506317
4.  Cytokines in chronic inflammatory arthritis. II. Granulocyte-macrophage colony-stimulating factor in rheumatoid synovial effusions. 
Journal of Clinical Investigation  1989;83(3):876-882.
A liquid culture technique was used to study 23 synovial fluids (SF) (21 from inflammatory joint diseases and 2 noninflammatory SF) and supernatants of two cultured rheumatoid arthritis (RA) synovial tissues for colony-stimulating factor (CSF). The proliferative responses of human peripheral blood macrophage-depleted non-T cells treated with synovial fluids, supernatants of synovial tissue explants, and recombinant granulocyte-macrophage (rGM)-CSF were compared. Aggregates of cells that formed in long-term cultures (15 d) were similar for each applied agent and consisted of macrophages, eosinophils, and large blasts. Tritiated thymidine incorporation was proportional to the concentration of rGM-CSF and was accompanied by an increase in number and size of cellular aggregates formed in the cultures. CSF activity was observed in inflammatory SF, with tritiated thymidine uptake of 3,501 +/- 1,140 cpm in the presence of RA samples (n = 15) compared to 1,985 +/- 628 for non-RA inflammatory SF (n = 7) (P less than 0.05) and 583 +/- 525 for medium (n = 6) (P less than 0.01). The proliferative response to RA SF was often more apparent when the samples were diluted, because at higher concentrations the RA SF was inhibitory. Two RA SF were fractionated by Sephadex G100 column chromatography; low levels of CSF activity were detected in fractions corresponding to Mr of 70-100 kD, but the major CSF activity was found in the 20-24-kD fractions. A polyclonal rabbit anti-GM-CSF antibody eliminated the stimulating activity from both rGM-CSF and RA SF. Finally, a specific RIA identified significant levels of GM-CSF (40-140 U/ml) in the culture supernatants of 3 additional RA synovial tissues. These data document the local production of GM-CSF in rheumatoid synovitis and are the first description of this cytokine at a site of disease activity.
PMCID: PMC303761  PMID: 2646320
5.  Characterization of CCL19 and CCL21 in Rheumatoid Arthritis 
Arthritis and rheumatism  2011;63(4):914-922.
The aim was to characterize the expression of CCL19 and CCL21 in rheumatoid arthritis (RA) synovial tissue and to examine their regulation and pathogenic role in macrophages and RA synovial tissue fibroblasts.
Expression of CCL19 and CCL21 was demonstrated in RA and normal (NL) synovial tissues employing immunohistochemistry. CCL19 and CCL21 levels were quantified in fluids from osteoarthritis (OA), juvenile idiopathic arthritis (JIA), psoriatic arthritis (PsA) and RA using ELISA. Regulation of CCL19 and CCL21 expression was determined in RA peripheral blood in vitro differentiated macrophages as well as RA synovial tissue fibroblasts by real-time RT-PCR. CCL19 and CCL21 activated peripheral blood in vitro differentiated macrophages and RA synovial tissue fibroblasts were examined for proangiogenic factor production employing ELISA.
CCL19 and CCL21 were elevated in RA synovial tissue compared to NL controls. Levels of CCL19 and CCL21 were greatly increased in RA and PsA synovial fluid versus OA synovial fluid. In RA macrophages and fibroblasts, expression of CCL19 was increased by LPS, TNF-α and IL-1β stimulation. However, CCL21 expression was modulated by IL-1β in RA fibroblasts as well as TNF-α and RA synovial fluid in RA macrophages. CCL19 and CCL21 activation induced VEGF and Ang-1 production from RA synovial tissue fibroblasts and secretion of IL-8 and Ang-1 from macrophages.
We identify, for the first time, regulators of CCL19 and CCL21 in RA fibroblasts and RA peripheral blood in vitro differentiated macrophages and we document a novel role of CCL19/21 in RA angiogenesis.
PMCID: PMC3079365  PMID: 21225692
CCL19; CCL21; RA synovial tissue fibroblast; macrophages and proangiogenic factors
6.  Interaction with activated monocytes enhances cytokine expression and suppressive activity of human CD4+CD45RO+CD25+CD127low regulatory T cells 
Arthritis and rheumatism  2013;65(3):627-638.
Despite the high frequency of CD4+ T cells with a regulatory phenotype (CD25+CD127lowFoxP3+) in the joints of patients with rheumatoid arthritis (RA), inflammation persists. One possible explanation is that human Tregs are converted into pro-inflammatory IL-17-producing cells by inflammatory mediators and thereby lose their suppressive function. We investigated whether activated monocytes, which are potent producers of inflammatory cytokines and abundantly present in the rheumatic joint, induce pro-inflammatory cytokine expression in human Tregs and impair their regulatory function.
The presence and phenotype of CD4+CD45RO+CD25+CD127low T cells (memory Tregs) and CD14+ monocytes in the peripheral blood (PB) and synovial fluid (SF) from patients with RA was investigated by flow cytometry. FACS-sorted memory Tregs from healthy controls were co-cultured with autologous activated monocytes and stimulated with anti-CD3 monoclonal antibody. Intracellular cytokine expression, phenotype and function of cells were determined by flow cytometry, ELISA and proliferation assays.
Patients with RA showed higher frequencies of CD4+CD45RO+CD25+CD127low Tregs and activated CD14+ monocytes in SF relative to PB. In vitro-activated monocytes induced an increase in the percentage of IL-17+, IFNγ+ and TNF-α+, but also IL-10+ Tregs. The observed increase in IL-17+ and IFNγ+ Tregs was driven by monocyte-derived IL-1β, IL-6 and TNF-α and was mediated by both CD14+CD16− and CD14+CD16+ monocyte subsets. Despite enhanced cytokine expression, cells maintained their CD25+FoxP3+CD39+ Treg phenotype and showed enhanced capacity to suppress proliferation and IL-17 production by effector T cells.
Tregs exposed to a pro-inflammatory environment show increased cytokine expression as well as enhanced suppressive activity.
PMCID: PMC3947722  PMID: 23280063
7.  Spontaneous production of fibroblast-activating factor(s) by synovial inflammatory cells. A potential mechanism for enhanced tissue destruction 
A characteristic feature of rheumatoid arthritis is hyperplasia of the synovial lining cells and fibroblasts, the source of tissue-degrading mediators, in association with the appearance and persistence of lymphocytes in affected joints. Diseased synovial tissue obtained at arthroscopy from 10 of 12 rheumatoid arthritis patients was found to release a factor(s) that could stimulate quiescent fibroblasts to proliferate in vitro. Mononuclear cells isolated from this synovial tissue and from the synovial fluid spontaneously produced fibroblast- activating factor(s) (FAF). In contrast, synovial tissue from patients with noninflammatory joint disease did not release FAF. By gel filtration, FAF was detected in two peaks (40,000 and 15,000 mol wt) that were consistent with the previously described peripheral blood T lymphocyte- and monocyte-derived factors with identical activity. The mononuclear cells were predominantly OKT3+/Leu-1+ T lymphocytes and OKM1+ cells of monocyte/macrophage lineage that expressed HLA-DR antigens, suggesting prior activation of these cells. Mononuclear cells isolated from the peripheral blood of these patients did not spontaneously secrete FAF. Lymphocytes and monocytes from the site of synovial inflammation appear to be activated in situ to produce factors that may contribute to the hyperplasia and overgrowth of the synovial membrane in rheumatoid arthritis.
PMCID: PMC2187543  PMID: 3968518
8.  Elevated autoantibody content in rheumatoid arthritis synovia with lymphoid aggregates and the effect of rituximab 
Arthritis Research & Therapy  2008;10(5):R105.
The purpose of this study was to quantitatively evaluate the contribution of synovial lymphoid aggregates to autoantibody (rheumatoid factor [RF] and anti-cyclic citrullinated peptide [anti-CCP]) and total immunoglobulin (IgG and IgM) production in rheumatoid arthritis (RA) patients and the effect thereon of the B-cell-depleting antibody, rituximab, in the ARISE (Assessment of Rituximab's Immunomodulatory Synovial Effects) trial.
Autoantibodies as well as total IgM and IgG were quantified by enzyme-linked immunosorbent assay in extracts of synovial tissues and matched serum from patients with RA or osteoarthritis (OA). Synovial biopsies and serum were obtained at baseline and 8 weeks following rituximab therapy in 14 RA patients. A synovial/serum index (SSI) was calculated as the ratio of synovial to serum antibody/albumin, with values above 1 representing synovial enrichment. Lymphoid aggregates were evaluated histologically.
Anti-CCP IgG, but not RF-IgM, was significantly enriched in RA synovia compared with serum. Total IgM and IgG were also enriched in RA, but not in OA. SSI correlated significantly with mRNA content for both IgM and IgG, demonstrating that it reflected synovial immunoglobulin production. RA synovia with lymphocyte aggregates contained significantly elevated RF-IgM and anti-CCP IgG compared with tissues with diffuse lymphoid infiltration. Rituximab treatment did not affect synovial autoantibody or total immunoglobulin SSI overall. However, in aggregate-containing tissues, rituximab significantly reduced total IgM and IgG SSI as well as IgM and IgG1 mRNA. Surprisingly, RF-IgM and anti-CCP IgG SSIs were unchanged by rituximab in aggregate-containing synovia.
Combined with earlier observations that synovial lymphoid aggregates are unaltered by rituximab treatment, these data suggest that lymphoid aggregates may provide a protective niche for autoantibody-producing cells.
Trial Registration
The ARISE trial is registered at as number NCT00147966.
PMCID: PMC2592782  PMID: 18761748
9.  Epithelial neutrophil activating peptide-78: a novel chemotactic cytokine for neutrophils in arthritis. 
Journal of Clinical Investigation  1994;94(3):1012-1018.
We and others have shown that cells obtained from inflamed joints of rheumatoid arthritis (RA) patients produce interleukin-8, a potent chemotactic cytokine for neutrophils (PMNs). However, IL-8 accounted for only 40% of the chemotactic activity for PMNs found in these synovial fluids. Currently, we have examined the production of the novel PMN chemotactic cytokine, epithelial neutrophil activating peptide-78 (ENA-78), using peripheral blood, synovial fluid, and synovial tissue from 70 arthritic patients. RA ENA-78 levels were greater in RA synovial fluid (239 +/- 63 ng/ml) compared with synovial fluid from other forms of arthritis (130 +/- 118 ng/ml) or osteoarthritis (2.6 +/- 1.8 ng/ml) (P < 0.05). RA peripheral blood ENA-78 levels (70 +/- 26 ng/ml) were greater than normal peripheral blood levels (0.12 +/- 0.04 ng/ml) (P < 0.05). Anti-ENA-78 antibodies neutralized 42 +/- 9% (mean +/- SE) of the chemotactic activity for PMNs found in RA synovial fluids. Isolated RA synovial tissue fibroblasts in vitro constitutively produced significant levels of ENA-78, and this production was further augmented when stimulated with tumor necrosis factor-alpha (TNF-alpha). In addition RA and osteoarthritis synovial tissue fibroblasts as well as RA synovial tissue macrophages were found to constitutively produce ENA-78. RA synovial fluid mononuclear cells spontaneously produced ENA-78, which was augmented in the presence of lipopolysaccharide. Immunohistochemical localization of ENA-78 from the synovial tissue of patients with arthritis or normal subjects showed that the predominant cellular source of this chemokine was synovial lining cells, followed by macrophages, endothelial cells, and fibroblasts. Synovial tissue macrophages and fibroblasts were more ENA-78 immunopositive in RA than in normal synovial tissue (P < 0.05). These results, which are the first demonstration of ENA-78 in a human disease state, suggest that ENA-78 may play an important role in the recruitment of PMNs in the milieu of the inflamed joint of RA patients.
PMCID: PMC295150  PMID: 8083342
10.  Dendritic cell-lymphocyte clusters that form spontaneously in rheumatoid arthritis synovial effusions differ from clusters formed in human mixed leukocyte reactions. 
Journal of Clinical Investigation  1988;82(5):1731-1745.
Lymphocytes cluster about dendritic cells (DC) spontaneously in 48 h cultures of rheumatoid arthritis synovial fluid (RA SF) mononuclear cells and in peripheral blood autologous or allogeneic mixed leukocyte reactions. In the latter case, the clusters are predominantly CD4+ T cells (T4/T8 greater than 5) and with time progress in blastic cells that express IL-2 (Tac) and/or transferrin (T9) receptors. In contrast, the clusters in RA SF cultures have a T4/T8 ratio of less than 1 and a majority of the T8 cells coexpress the Leu 7 marker. T cells in these clusters remain inert and with time the clusters disintegrate. Addition of IL-1, IL-2, or IFN-gamma alone or in combination had no effect on RA SF clusters but T cells became blastic when exposed to 10% RA SF. Mixing experiments using RA SF DC with normal T cells and RA T cells with normal DC show that both RA SF DC and T cells are immunofunctional. In addition, clusters of RA SF from a patient with active tuberculosis proliferated vigorously to PPD. Therefore, the unique RA SF cluster profile may reflect the memory nature of the RA SF T cells resulting in a paucity of T cells that are responsive to autologous stimulation. However, an immunosuppressive role for the double-labeled (CD8 and Leu 7) cells has not been excluded.
PMCID: PMC442744  PMID: 2972742
11.  Natural killer (NK) cell activity of peripheral blood, synovial fluid, and synovial tissue lymphocytes from patients with rheumatoid arthritis and juvenile rheumatoid arthritis. 
Annals of the Rheumatic Diseases  1982;41(5):490-494.
Natural killer (NK) cell activity was investigated in peripheral blood, synovial fluid, and synovial tissue lymphocytes from patients with rheumatoid arthritis (RA) and juvenile rheumatoid arthritis (JRA). Unfractionated lymphocytes, T lymphocytes, and non-T lymphocytes from the 3 compartments of JRA patients had reduced activity compared with that of normal peripheral blood lymphocytes (with p values usually between 0.05 and 0.1). Unfractionated synovial tissue lymphocytes of RA patients also showed reduced cytotoxicity (0.05 less than p less than 0.1), whereas peripheral blood lymphocytes exerted normal NK cell activity. The NK activity was exerted by cells both with and without Fc gamma receptors. The highest cytotoxicity was observed in Fc gamma receptor-positive cells, both in peripheral blood and synovial fluid, since more than 70% reduction in NK activity was found after depletion of Fc gamma receptor-positive cells. No evidence of lymphocytotoxic antibodies or other factors with influence on NK cells was observed in the patients' sera.
PMCID: PMC1001029  PMID: 6181746
12.  Mosaic chromosomal aberrations in synovial fibroblasts of patients with rheumatoid arthritis, osteoarthritis, and other inflammatory joint diseases 
Arthritis Research  2001;3(5):319-330.
Chromosomal aberrations were comparatively assessed in nuclei extracted from synovial tissue, primary-culture (P-0) synovial cells, and early-passage synovial fibroblasts (SFB; 98% enrichment; P-1, P-4 [passage 1, passage 4]) from patients with rheumatoid arthritis (RA; n = 21), osteoarthritis (OA; n = 24), and other rheumatic diseases. Peripheral blood lymphocytes (PBL) and skin fibroblasts (FB) (P-1, P-4) from the same patients, as well as SFB from normal joints and patients with joint trauma (JT) (n = 4), were used as controls. Analyses proceeded by standard GTG-banding and interphase centromere fluorescence in situ hybridization. Structural chromosomal aberrations were observed in SFB (P-1 or P-4) from 4 of 21 RA patients (19%), with involvement of chromosome 1 [e.g. del(1)(q12)] in 3 of 4 cases. In 10 of the 21 RA cases (48%), polysomy 7 was observed in P-1 SFB. In addition, aneusomies of chromosomes 4, 6, 8, 9, 12, 18, and Y were present. The percentage of polysomies was increased in P-4. Similar chromosomal aberrations were detected in SFB of OA and spondylarthropathy patients. No aberrations were detected in i) PBL or skin FB from the same patients (except for one OA patient with a karyotype 45,X[10]/46,XX[17] in PBL and variable polysomies in long-term culture skin FB); or ii) synovial tissue and/or P-1 SFB of normal joints or of patients with joint trauma. In conclusion, qualitatively comparable chromosomal aberrations were observed in synovial tissue and early-passage SFB of patients with RA, OA, and other inflammatory joint diseases. Thus, although of possible functional relevance for the pathologic role of SFB in RA, these alterations probably reflect a common response to chronic inflammatory stress in rheumatic diseases.
PMCID: PMC64845  PMID: 11549374
osteoarthritis; rheumatoid arthritis; spondylarthropathy; synovial fibroblasts; trisomy/polysomy 7
13.  Interleukin-17–producing T cells are enriched in the joints of children with arthritis, but have a reciprocal relationship to regulatory T cell numbers 
Arthritis and Rheumatism  2008;58(3):875-887.
To identify interleukin-17 (IL-17)–producing T cells from patients with juvenile idiopathic arthritis (JIA), and investigate their cytokine production, migratory capacity, and relationship to Treg cells at sites of inflammation, as well as to test the hypothesis that IL-17+ T cell numbers correlate with clinical phenotype in childhood arthritis.
Flow cytometry was used to analyze the phenotype, cytokine production, and chemokine receptor expression of IL-17–producing T cells in peripheral blood and synovial fluid mononuclear cells from 36 children with JIA, in parallel with analysis of forkhead box P3 (FoxP3)–positive Treg cells. Migration of IL-17+ T cells toward CCL20 was assessed by a Transwell assay. Synovial tissue was analyzed by immunohistochemistry for IL-17 and IL-22.
IL-17+ T cells were enriched in the joints of children with JIA as compared with the blood of JIA patients (P = 0.0001) and controls (P = 0.018) and were demonstrated in synovial tissue. IL-17+ T cell numbers were higher in patients with extended oligoarthritis, the more severe subtype of JIA, as compared with patients with persistent oligoarthritis, the milder subtype (P = 0.046). Within the joint, there was an inverse relationship between IL-17+ T cells and FoxP3+ Treg cells (r = 0.61, P = 0.016). IL-17+,CD4+ T cells were uniformly CCR6+ and migrated toward CCL20, but synovial IL-17+ T cells had variable CCR4 expression. A proportion of IL-17+ synovial T cells produced IL-22 and interferon-γ.
This study is the first to define the frequency and characteristics of “Th17” cells in JIA. We suggest that these highly proinflammatory cells contribute to joint pathology, as indicated by relationships with clinical phenotypes, and that the balance between IL-17+ T cells and Treg cells may be critical to outcome.
PMCID: PMC2675006  PMID: 18311821
14.  Peripheral blood but not synovial fluid natural killer T cells are biased towards a Th1-like phenotype in rheumatoid arthritis 
Arthritis Research & Therapy  2005;7(3):R493-R502.
Natural killer T (NKT) cells have been implicated in the regulatory immune mechanisms that control autoimmunity. However, their precise role in the pathogenesis of rheumatoid arthritis (RA) remains unclear. The frequency, cytokine profile and heterogeneity of NKT cells were studied in peripheral blood mononuclear cells (PBMCs) from 23 RA patients and 22 healthy control individuals, including paired PBMC–synovial fluid samples from seven and paired PBMC–synovial tissue samples from four RA patients. Flow cytometry revealed a decreased frequency of NKT cells in PBMCs from RA patients. NKT cells were present in paired synovial fluid and synovial tissue samples. Based on the reactivity of PBMC-derived NKT cells toward α-galactosylceramide, RA patients could be divided into responders (53.8%) and nonresponders (46.2%). However, NKT cells isolated from synovial fluid from both responders and nonresponders expanded upon stimulation with α-galactosylceramide. Analysis of the cytokine profile of CD4+ and CD4- PBMC derived NKT cell lines from RA patients revealed a significantly reduced number of IL-4 producing cells. In contrast, synovial fluid derived NKT cell lines exhibited a Th0-like phenotype, which was comparable to that in healthy control individuals. This suggests that synovial fluid NKT cells are functional, even in patients with nonresponding NKT cells in their blood. We conclude that, because the number of Vα24+Vβ11+CD3+ NKT cells is decreased and the cytokine profile of blood-derived NKT cells is biased toward a Th1-like phenotype in RA patients, NKT cells might be functionally related to resistance or progression of RA. Providing a local boost to the regulatory potential of NKT cells might represent a useful candidate therapy for RA.
PMCID: PMC1174940  PMID: 15899036
15.  Synovial microparticles from arthritic patients modulate chemokine and cytokine release by synoviocytes 
Arthritis Research & Therapy  2005;7(3):R536-R544.
Synovial fluid from patients with various arthritides contains procoagulant, cell-derived microparticles. Here we studied whether synovial microparticles modulate the release of chemokines and cytokines by fibroblast-like synoviocytes (FLS). Microparticles, isolated from the synovial fluid of rheumatoid arthritis (RA) and arthritis control (AC) patients (n = 8 and n = 3, respectively), were identified and quantified by flow cytometry. Simultaneously, arthroscopically guided synovial biopsies were taken from the same knee joint as the synovial fluid. FLS were isolated, cultured, and incubated for 24 hours in the absence or presence of autologous microparticles. Subsequently, cell-free culture supernatants were collected and concentrations of monocyte chemoattractant protein-1 (MCP-1), IL-6, IL-8, granulocyte/macrophage colony-stimulating factor (GM-CSF), vascular endothelial growth factor (VEGF) and intracellular adhesion molecule-1 (ICAM-1) were determined. Results were consistent with previous observations: synovial fluid from all RA as well as AC patients contained microparticles of monocytic and granulocytic origin. Incubation with autologous microparticles increased the levels of MCP-1, IL-8 and RANTES in 6 of 11 cultures of FLS, and IL-6, ICAM-1 and VEGF in 10 cultures. Total numbers of microparticles were correlated with the IL-8 (r = 0.91, P < 0.0001) and MCP-1 concentrations (r = 0.81, P < 0.0001), as did the numbers of granulocyte-derived microparticles (r = 0.89, P < 0.0001 and r = 0.93, P < 0.0001, respectively). In contrast, GM-CSF levels were decreased. These results demonstrate that microparticles might modulate the release of chemokines and cytokines by FLS and might therefore have a function in synovial inflammation and angiogenesis.
PMCID: PMC1174949  PMID: 15899040
16.  Blockade of Toll-like receptor 2 prevents spontaneous cytokine release from rheumatoid arthritis ex vivo synovial explant cultures 
The aim of this study was to examine the effect of blocking Toll-like receptor 2 (TLR2) in rheumatoid arthritis (RA) synovial cells.
RA synovial tissue biopsies, obtained under direct visualization at arthroscopy, were established as synovial explant cultures ex vivo or snap frozen for immunohistology. Mononuclear cell cultures were isolated from peripheral blood and synovial fluid of RA patients. Cultures were incubated with the TLR1/2 ligand, Pam3CSK4 (200 ng, 1 and 10 μg/ml), an anti-TLR2 antibody (OPN301, 1 μg/ml) or an immunoglobulin G (IgG) (1 μg/ml) matched control. The comparative effect of OPN301 and adalimumab (anti-tumour necrosis factor alpha) on spontaneous release of proinflammatory cytokines from RA synovial explants was determined using quantitative cytokine MSD multiplex assays or ELISA. OPN301 penetration into RA synovial tissue explants cultures was assessed by immunohistology.
Pam3CSK4 significantly upregulated interleukin (IL)-6 and IL-8 in RA peripheral blood mononuclear cells (PBMCs), RA synovial fluid mononuclear cells (SFMCs) and RA synovial explant cultures (P < 0.05). OPN301 significantly decreased Pam3CSK4-induced cytokine production of tumour necrosis factor alpha (TNF-α), IL-1β, IL-6, interferon (IFN)-γ and IL-8 compared to IgG control in RA PBMCs and SFMCs cultures (all P < 0.05). OPN301 penetration of RA synovial tissue cultures was detected in the lining layer and perivascular regions. OPN301 significantly decreased spontaneous cytokine production of TNF-α, IL-1β, IFN-γ and IL-8 from RA synovial tissue explant cultures (all P < 0.05). Importantly, the inhibitory effect of OPN on spontaneous cytokine secretion was comparable to inhibition by anti-TNFα monoclonal antibody adalimumab.
These findings further support targeting TLR2 as a potential therapeutic agent for the treatment of RA.
PMCID: PMC3241377  PMID: 21345222
17.  Rheumatoid synovial CD4+ T cells exhibit a reduced capacity to differentiate into IL-4-producing T-helper-2 effector cells 
Arthritis Research  2000;3(1):54-64.
CD4+ memory T cells (Tm) from rheumatoid arthritis peripheral blood (RAPB) or peripheral blood from normal donors produced IL-2, whereas fewer cells secreted IFN-γ or IL-4 after a brief stimulation. RAPB Tm contained significantly more IFN-γ producers than normal cells. Many rheumatoid arthritis (RA) synovial Tm produced IFN-γ alone (40%) and fewer cells produced IL-2 or IL-4. An in vitro model was employed to generate polarized T-helper (Th) effectors. Normal and RAPB Tm differentiated into both IFN-γ- and IL-4-producing effectors. RA synovial fluid (RASF) Tm demonstrated defective responsiveness, exhibiting diminished differentiation of IL-4 effectors, whereas RA synovial tissue (RAST) Tm exhibited defective generation of IFN-γ and IL-4 producers.
PMCID: PMC17825  PMID: 11178127
CD4+ T-helper cells; cytokines; rheumatoid arthritis
18.  Differential expression and functional behaviour of the αv and β3 integrin subunits in cytokine stimulated fibroblast-like cells derived from synovial tissue of rheumatoid arthritis and osteoarthritis in vitro 
Annals of the Rheumatic Diseases  1997;56(12):729-736.
OBJECTIVE—The aim of this study was to investigate in situ the expression of the classic vitronectin (VN) receptor consisting of the αv and β3 subunits in synovial lining cells (SLC) of chronic synovitis occurring in osteoarthritis (OA) and in rheumatoid arthritis (RA). The expression and function of αv and β3 as VN receptor in cultured fibroblast-like synoviocytes (FBS) derived from patients with OA and RA was also compared.
METHODS—Expression of αv and β3 was examined immunohistochemically in normal synovial tissue and in synovial tisssue from patients with OA and RA. The effect of proinflammatory cytokines and of a synovial fluid of a patient with RA on the expression of the αv and β3 subunits of cultured FBS was determined by flow cytometry. Binding of OA and RA-FBS to VN was quantified using adhesion assays and the effect of interleukin 1β (IL1β) and tumour necrosis factor α (TNFα) on adhesion was measured. The specifity of the adhesion was tested by inhibition studies using monoclonal antibodies to integrin subunits.
RESULTS—In in situ studies normal SLC showed a parallel distribution of αv and β3 subunits. OA-SLC strongly and uniformly expressed αv whereas RA-SLC showed heterogeneous expression of αv. In situ both OA-SLC and RA-SLC lacked the expression of the integrin subunit β3. In in vitro studies, OA-FBS and RA-FBS did not differ as regards expression of αv and β3, and VN attachment. Binding of RA-FBS to VN was partially blocked by antibodies against αv, β1, and β3 subunits, whereas only antibodies against αv and β3 inhibited the binding of OA-FBS to VN. The proinflammatory cytokines TNFα and IL1β increased the expression of αv and β3, and the VN binding of OA-FBS, whereas αv and β3 expression, and VN binding were downregulated in RA-FBS. Similar effects were found when the synovial fluid of an RA patient was used.
CONCLUSION—The integrin subunit β3 seems to be one partner but not the major one with which the subunit αv forms functional vitronectin receptors in OA-FBS and RA-FBS. The interaction between synovial cells and inflammatory cytokines seems to be different for OA and RA; the basis for this difference, however, remains to be established.

PMCID: PMC1752301  PMID: 9496152
19.  Human Regulatory T Cell Suppressive Function Is Independent of Apoptosis Induction in Activated Effector T Cells 
PLoS ONE  2009;4(9):e7183.
CD4+CD25+FOXP3+ Regulatory T cells (Treg) play a central role in the immune balance to prevent autoimmune disease. One outstanding question is how Tregs suppress effector immune responses in human. Experiments in mice demonstrated that Treg restrict effector T cell (Teff) responses by deprivation of the growth factor IL-2 through Treg consumption, resulting in apoptosis of Teff.
Principal Findings
In this study we investigated the relevance of Teff apoptosis induction to human Treg function. To this end, we studied naturally occurring Treg (nTreg) from peripheral blood of healthy donors, and, to investigate Treg function in inflammation in vivo, Treg from synovial fluid of Juvenile Idiopathic Arthritis (JIA) patients (SF-Treg). Both nTreg and SF-Treg suppress Teff proliferation and cytokine production efficiently as predicted. However, in contrast with murine Treg, neither nTreg nor SF-Treg induce apoptosis in Teff. Furthermore, exogenously supplied IL-2 and IL-7 reverse suppression, but do not influence apoptosis of Teff.
Our functional data here support that Treg are excellent clinical targets to counteract autoimmune diseases. For optimal functional outcome in human clinical trials, future work should focus on the ability of Treg to suppress proliferation and cytokine production of Teff, rather than induction of Teff apoptosis.
PMCID: PMC2746309  PMID: 19779623
20.  Macrophage migration inhibitory factor enhances osteoclastogenesis through upregulation of RANKL expression from fibroblast-like synoviocytes in patients with rheumatoid arthritis 
Macrophage migration inhibitory factor (MIF) is one of key regulators in acute and chronic immune-inflammatory conditions including rheumatoid arthritis (RA). We examined the effect of MIF on osteoclastogenesis, which is known to play a crucial role in bone destruction in RA.
The concentration of MIF and receptor activator of nuclear factor-κB ligand (RANKL) in the synovial fluid was measured by ELISA. MIF-induced RANKL expression of RA synovial fibroblasts was determined by real-time PCR and western blot. Osteoclastogenesis was analyzed in culture of human peripheral blood mononuclear cells (PBMC) with MIF. Osteoclastogenesis was also determined after co-cultures of rhMIF-stimulated RA synovial fibroblasts with human PBMC.
Synovial fluid MIF concentration in RA patients was significantly higher than in osteoarthritis (OA) patients. The concentration of RANKL correlated with that of MIF in RA synovial fluids (r = 0.6, P < 0.001). MIF stimulated the expression of RANKL mRNA and protein in RA synovial fibroblasts, which was partially reduced by blocking of interleukin (IL)-1β. Osteoclasts were differentiated from PBMC cultures with MIF and M-CSF, even without RANKL. Osteoclastogenesis was increased after co-culture of MIF-stimulated RA synovial fibroblasts with PBMC and this effect was diminished by RANKL neutralization. Blocking of PI3 kinase, p38 MAP kinase, JAK-2, NF-κB, and AP-1 also led to a marked reduction in RANKL expression and osteoclastogenesis.
The interactions among MIF, synovial fibroblasts, osteoclasts, RANKL, and IL-1β have a close connection in osteoclastogenesis and they could be a potential gateway leading to new therapeutic approaches in treating bone destruction in RA.
PMCID: PMC3132025  PMID: 21401926
21.  Quantitative biomarker analysis of synovial gene expression by real-time PCR 
Arthritis Research & Therapy  2003;5(6):R352-R360.
Synovial biomarker analysis in rheumatoid arthritis can be used to evaluate drug effect in clinical trials of novel therapeutic agents. Previous studies of synovial gene expression for these studies have mainly relied on histological methods including immunohistochemistry and in situ hybridization. To increase the reliability of mRNA measurements on small synovial tissue samples, we developed and validated real time quantitative PCR (Q-PCR) methods on biopsy specimens. RNA was isolated from synovial tissue and cDNA was prepared. Cell-based standards were prepared from mitogen-stimulated peripheral blood mononuclear cells. Real time PCR was performed using TaqMan chemistry to quantify gene expression relative to the cell-based standard. Application of the cellular standard curve method markedly reduced intra- and inter-assay variability and corrected amplification efficiency errors compared with the C(t) method. The inter-assay coefficient of variation was less than 25% over time. Q-PCR methods were validated by demonstrating increased expression of IL-1β and IL-6 expression in rheumatoid arthritis synovial samples compared with osteoarthritis synovium. Based on determinations of sampling error and coefficient of variation, twofold differences in gene expression in serial biopsies can be detected by assaying approximately six synovial tissue biopsies from 8 to 10 patients. These data indicate that Q-PCR is a reliable method for determining relative gene expression in small synovial tissue specimens. The technique can potentially be used in serial biopsy studies to provide insights into mechanism of action and therapeutic effect of new anti-inflammatory agents.
PMCID: PMC333415  PMID: 14680510
arthritis; biomarker; rheumatoid; synovium
22.  The cytotoxicity of leukocytes and lymphocytes from patients with rheumatoid arthritis for synovial cells. 
Journal of Clinical Investigation  1976;58(3):690-698.
Unseparated peripheral blood leukocytes obtained from patients with rheumatoid arthritis (RA) were cytotoxic for synovial cells. The cytotoxic reactions produced by RA leukocytes were more frequent and of greater magnitude than cytotoxicity induced by leukocytes from normal persons and patients with other diseases, primarily connective tissue diseases. Furthermore, the cytotoxic activity of RA leukocytes was greater for RA synovial cells than for nonrheumatoid synovial cells, in contrast to the cytotoxicity of other leukocytes, which did not discriminate between synovial cells according to their origin. Tests with purified lymphocytes showed that the cytotoxicity of unseparated leukocytes directed against RA synovial cells was due to lymphocyte cytotoxicity. These data are consistent with the possibility that sensitized lymphocytes from patients with RA recognize a distinctive antigen present on rheumatoid synovial cells.
PMCID: PMC333227  PMID: 956395
23.  Cytotoxic activity of rheumatoid and normal lymphocytes against allogeneic and autologous synovial cells in vitro. 
Journal of Clinical Investigation  1976;58(3):613-622.
The possibility that lymphocytes from patients with rheumatoid arthritis (RA) might be sensitized to RA synovial cell antigens was investigated with a 51Cr release cytotoxicity assay. Peripheral blood lymphocytes from rheumatoid and normal donors were tested for cytotoxic activity against their own synovial cells and against allogeneic rheumatoid and nonrhemuatoid synovial cells. In the allogeneic studies, the degree of cytotoxicity was significantly influenced by the age in culture (passage number) of the synovial target cells (P less than 0.001). When the passage number of the target cells was considered in the analysis, rheumatoid lymphocytes were found to have greater cytotoxic activity than normal lymphocytes against young cultures (low passage number) of both RA and non-RA synovial cells (P = 0.0042). Differences in susceptibility to lysis between RA and non-RA synovial cells were more susceptible to both RA and normal lymphocyte-induced lysis than were non-RA synovial cells (P = 0.0048). No evidence of cytotoxicity was detected when lymphocytes from nine RA patients and two osteoarthritis patients were reacted against their own synovial cells. Although the data demonstrated an increased cytotoxic activity of peripheral blood lymphocytes from some RA patients against allogeneic synovial cells, the fact that this reactivity was seen against both non-RA and RA synovial cells and was not demonstrated against autologous synovial cells argues against the presence of an immunospecific response of RA lymphocytes to RA synovial cell antigens.
PMCID: PMC333220  PMID: 956390
24.  TWEAK and Fn14 expression in the pathogenesis of joint inflammation and bone erosion in rheumatoid arthritis 
TNF-like weak inducer of apoptosis (TWEAK) has been proposed as a mediator of inflammation and bone erosion in rheumatoid arthritis (RA). This study aimed to investigate TWEAK and TWEAK receptor (Fn14) expression in synovial tissue from patients with active and inactive rheumatoid arthritis (RA), osteoarthritis (OA) and normal controls and assess soluble (s)TWEAK levels in the synovial fluids from patients with active RA and OA. Effects of sTWEAK on osteoclasts and osteoblasts were investigated in vitro.
TWEAK and Fn14 expression were detected in synovial tissues by immunohistochemistry (IHC). Selected tissues were dual labelled with antibodies specific for TWEAK and lineage-selective cell surface markers CD68, Tryptase G, CD22 and CD38. TWEAK mRNA expression was examined in human peripheral blood mononuclear cells (PBMC) sorted on the basis of their expression of CD22. sTWEAK was detected in synovial fluid from OA and RA patients by ELISA. The effect of sTWEAK on PBMC and RAW 264.7 osteoclastogenesis was examined. The effect of sTWEAK on cell surface receptor activator of NF Kappa B Ligand (RANKL) expression by human osteoblasts was determined by flow cytometry.
TWEAK and Fn14 expression were significantly higher in synovial tissue from all patient groups compared to the synovial tissue from control subjects (P < 0.05). TWEAK was significantly higher in active compared with inactive RA tissues (P < 0.05). TWEAK expression co-localised with a subset of CD38+ plasma cells and with CD22+ B-lymphocytes in RA tissues. Abundant TWEAK mRNA expression was detected in normal human CD22+ B cells. Higher levels of sTWEAK were observed in synovial fluids isolated from active RA compared with OA patients. sTWEAK did not stimulate osteoclast formation directly from PBMC, however, sTWEAK induced the surface expression of RANKL by human immature, STRO-1+ osteoblasts.
The expression of TWEAK by CD22+ B cells and CD38+ plasma cells in RA synovium represents a novel potential pathogenic pathway. High levels of sTWEAK in active RA synovial fluid and of TWEAK and Fn14 in active RA tissue, together with the effect of TWEAK to induce osteoblastic RANKL expression, is consistent with TWEAK/Fn14 signalling being important in the pathogenesis of inflammation and bone erosion in RA.
PMCID: PMC3132040  PMID: 21435232
25.  Divergent effects of methotrexate on the clonal growth of T and B lymphocytes and synovial adherent cells from patients with rheumatoid arthritis. 
Annals of the Rheumatic Diseases  1996;55(4):237-242.
OBJECTIVE: To define the mechanisms whereby methotrexate (MTX) manifests its effects in patients with rheumatoid arthritis. METHODS: T and B cells from peripheral blood and rheumatoid synovial tissues, synovial adherent cells, and the human fibrosarcoma cell line HT1080 and its mutant (defective in an enzyme in the nucleotide salvage pathway) were tested for clonal growth when cultured with MTX. Normal human fibroblasts and those with a deficiency in a salvage pathway were cultured with MTX in the presence or absence of purine and pyrimidine bases. RESULTS: Clonal growth of T and B cells, but not synovial cells, was inhibited by clinically relevant concentrations of MTX. Slowly proliferating fibroblast lines were resistant to MTX, whereas their rapidly proliferating counterparts were not. However, mutant fibroblast lines deficient in a salvage pathway were sensitive to MTX despite slow proliferation. Similarly, while skin fibroblasts were resistant to MTX, germline mutant fibroblasts deficient in a salvage pathway were sensitive to small concentrations of MTX. CONCLUSION: T and B lymphocytes, but not synovial cells, may be the target of MTX in vivo. Resistance to MTX may be associated with slow proliferation and the ability to synthesise nucleotides via salvage pathways. MTX can inhibit proliferation of even slowly growing cells by restricting the supply of nucleotides obtained via a salvage pathway, by removal of purine and pyrimidine bases, or by inducing a deficiency in a salvage pathway. It may be possible to manipulate the therapeutic effect of MTX by adjusting the amounts of purines and pyrimidines available to the cells in vivo.
PMCID: PMC1010144  PMID: 8733440

Results 1-25 (661795)