Extract
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Rheumatoid arthritis (RA) is a serious medical problem
that affects approximately 1% of the world¡¯s population.
|Although palliative treatments (nonsteroidal
anti-inflammatory drugs; NSAIDs) are widely prescribed, there are
currently only a few treatments that can modify the progression
of the disease (disease-modifying antirheumatic drugs;
DMARDs). A major obstacle to the development of
treatment strategies is that the disease mechanisms remain largely
unknown, but clues may come from studying experimental
models of arthritis[1,2].
RA is autoimmune in nature and is characterized by
chronic inflammation of the synovial tissues in multiple joints,
which leads to joint destruction. The characteristic
pathological findings of RA synovitis are aberrant proliferation of
synoviocytes. It has been reported that the majority of
rheumatoid synovial cells, regardless of morphology, consist of
3 different cell types: fibroblast-like synoviocytes (FLS),
dendritic-like synoviocytes (DLS) and macrophage-like
synoviocytes (MLS)[3]. There are few reports about the
relationships and interactions between different types of
synoviocytes.
IL-1 mediates bone resorption, cartilage destruction and
inflammation in RA. IL-1 receptor antagonist (IL-1ra)
selectively inhibits IL-1 by competing for the IL-1 receptor on all
surfaces of the synovium. Treatment of rheumatoid patients
with IL-1ra leads to an improvement in different clinical and
biological parameters and to a reduction in the radiological
signs of joint erosion. Encouraging results have also been
reported in experimental animal models of arthritis through
using other strategies designed to block the effects of
IL-1[4,5]. However, the effects of IL-1ra on different types of
synoviocytes in vivo are poorly understood.
Adjuvant arthritis (AA) in rats is an experimental model
that shares some features with human RA, including swelling,
cartilage degradation and loss of joint
function[6]. One of the most important features of AA is chronic synovitis,
including inflammatory cell infiltration, pannus formation,
destruction of cartilage, and bone
erosion[7].
The goal of the present study was to investigate the
mechanism of IL-1ra in the treatment of AA. We
investigated the effects and mechanisms of IL-1ra on the
ultrastructure of synoviocytes and pro-inflammatory cytokine
production by MLS in AA rats. In addition, we also wanted
to investigate mitogen-activated protein kinase (MAPK)
phosphorylation and cell proliferation in FLS induced by the
culture supernatants of MLS in AA rats treated with IL-1ra.
Materials and methods
Animals Male Sprague-Dawley (SD) rats (180±20 g) and
C57BL/6J mice (20±2 g) were purchased from Shanghai BK
Experimental Animal Center (Grade II, Certificate
No D-65). All rats were acclimatized under standard laboratory
conditions. During the experimental period, all rats were
housed 5 per cage and given water and standard laboratory
chow. They were kept in a 12-h dark/12-h light cycle at a
constant temperature of 20-25 °C. All experimental
protocols described in the present study were approved by the
Ethics Review Committee for Animal Experimentation of the
Institute of Clinical Pharmacology, Anhui Medical University.
Materials and reagents Rabbit anti-JNK1/2, rabbit
anti-phospho-JNK1/2
(pThr183/pTyr185), rabbit anti-p38 kinase,
rabbit anti-phospho-p38 kinase
(pThr180/pTyr182), rabbit
anti-ERK-1/2 and rabbit anti-phospho-ERK1/2
(pThr202/pTyr 204) antibodies were purchased from Sigma (St Louis, MO, USA).
SuperSignal West Femto Maximum Sensitivity Substrate was
obtained from Pierce (Rockford, IL, USA). The
125I-TNF-a radioimmunoassay (RIA) kit was the product of Beijing
Biotinge Biomedicine Company (Beijing, China). The
125I-PGE2 RIA kit was the product of Suzhou Medical College
(Suzhou, China). Bacillus-Calmette-Guerin (BCG)
vaccine was obtained from Shanghai Biochemical Factory (Shanghai,
China). Collagenase type IA, trypsin, lipopolysaccharide
(LPS),
3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H
tetrazolium bromide (MTT) and all chemicals with analytical purity
were purchased from Sigma. The RPMI-1640 medium from
Gibco (CA, USA; pH=7.2) was supplemented with 100 U/mL
penicillin, 100 g/L streptomycin, 2 mmol/L
L-glutamine, 5×10-5 mol/L 2-mercaptoethanol and 25 mmol/L N-2
hydroxyethyl-piperazine-N-2-ethanesulfonic acid (HEPES).
Drugs IL-1ra (Amgen, Thousand Oaks, CA, batch
number 20030701) occurs as white crystals or crystalline powder.
The compound was dissolved in phosphate buffered saline
(PBS; Pierce, Rockford IL).
Induction and treatment of AA Freund¡¯s complete
adjuvant (FCA) was prepared by suspending heat-killed BCG in
liquid paraffin at 10 mg/mL. AA was induced by a single
intradermal injection of 100 µL FCA into the left hind
metatarsal footpads of rats. The onset and severity of disease
were monitored daily and evaluated by 2 observers who were
blinded to the treatment. At d 0, 5, 9, 13, 17 and 21 after
immunization, the right hind paw volume was determined by
using a MK-550 volume meter (Muromachi Kikai, Tokyo,
Japan). Paw swelling (mL) was calculated by subtracting the
paw volume at d 0 from that at d 5, 9, 13, 17 and 21. Our data
indicated that paw swelling occurred on d 13 after
immuniza-tion. Before the onset of arthritis, animals were divided into
5 groups randomly. On d 14 after immunization, rats were
given an intracutaneous injection of IL-1ra (2.5, 10, 40
mg/kg, 3 times per day) from d 14 to d 21. For the controls and
AA models, rats were given an equal volume of vehicle.
Ultrastructure of synoviocytes Rats were killed on d 22
after immunization. Synovial tissues were fixed with 4%
paraformaldehyde solution overnight and were washed with
PBS after fixing with 1% osmic acid for 2 h. After being
embedded in an Epon/Araldite (Sigma, Saint Louis, USA)
mixture and stained with uranyl acetate and lead citrate, the
synoviocytes were observed under a 1230-type
transmission electron microscope (Electron, Yokohama, Kanagawa,
Japan) and photographed.
Culture of MLS Synoviocytes from hind paws were excised and dispersed with sequential incubation with 0.4
mg/mL collagenase and 0.25 mg/mL trypsin. In brief, small
minced synovial membranes were digested in RPMI-1640
medium containing 5% fetal bovine serum (FBS; Sigma) and
0.4 mg/mL collagenase type IA at 37 ºC, at 5%
CO2. Two hours later, adherent cells were discarded and non-adherent
tissues were incubated in serum-starved RPMI-1640 medium
containing 0.25 mg/mL trypsin for 1 h. After incubation, the
tissue was pipetted through sterile
108-mm2 nylon mesh into a sterile centrifuge tube. Cells were then washed 3 times
with RPMI-1640 plus 5% FBS and added to 20 mL
flat-bottomed culture bottles (Sumitomo Bakelite, Tokyo, Japan) and
incubated with RPMI-1640 plus 10% FBS at 37 ºC, 5%
CO2, for 24 h. After cells became adherent, the cultures were
replaced and synoviocytes were resuspended in RPMI-1640
medium containing 10% heat-inactivated FBS. The
round-shaped cells (Figure 1A) were cultured with 5 mg/L LPS in
24-well flat-bottomed culture plates (Sumitomo Bakelite) at a
final concentration of 1×106 cells/1 mL per well. After
incubation at 37 ºC in a 5 % CO2 atmosphere for 48 h, the
supernatant containing IL-1, tumor necrosis factor alpha
(TNF-a) and prostaglandin E2
(PGE2) was collected and stored at -20 ºC.
RIA of TNFa and PGE2 One hundred microliters of
supernatant containing TNF-a and PGE2 were measured
according to the procedures outlined in the TNF-a and
PGE2 125I RIA kit.
Analysis of IL-1 activity IL-1 activity was measured by
using the ConA-induced thymocyte proliferation in
C57BL/6J mice assay. Fifty microliters of a thymocyte suspension
(5×109 cells/L) taken from C57BL/6J mice were distributed
over a flat-bottomed 96-well microtiter plate (Sumitomo
Bakelite). Then, 100 µL supernatant samples of MLS containing IL-1 and 50 µL ConA (with a final concentration of 5
mg/L) were added and incubated. IL-1 activity was
measured by using a thymocytes proliferation assay. Briefly,
the cells were incubated at 37 ºC in a 5 %
CO2 atmosphere for 48 h. MTT (5 g/L, 10 µL) was added to each well. After being
incubated at 37 ºC for an additional 2 h, the cells were
centrifuged at 760×g for 10 min and all the supernatants were
discarded. Formazan crystals were dissolved in 120 µL
isobutanol (containing 0.04 mol/L HCl) and the absorbance
was read at 570 nm using an EJ301 (Bio-Tek Instruments,
Winooski, Vermont) enzyme-linked immunosorbent assay
(ELISA) Microwell reader. The results are presented as the
average absorbance (A) and expressed as the mean of
triplicate samples.
FLS culture and protein sample preparation
Synovial tissues were isolated from hind paws by removing the skin,
muscle, fatty tissues, bone, and tendons, then were
homogenized to yield approximately 1 mg protein/mL for the
detection of MAPK phosphorylation. For other samples,
synovial tissues obtained from the hind paws of AA rats were
minced and digested by collagenase type IA for 3 h, filtered,
extensively washed, and then cultured in RPMI-1640
medium (pH 7.2) containing 20% heat-inactivated FBS at 37 °C
in a humidified atmosphere of 5 % CO2. At confluence,
adherent cells were trypsinized, split in a 1:3 ratio, and recultured
in medium. The spindle-shaped cells were used from
passages 3 through to 9 in these experiments, during which time
they were a homogeneous population of FLS (Figure
1B-1D). After that, cells were washed with PBS, distributed in 20
mL flat-bottomed culture bottles at a concentration of
2×106 cells per bottle and kept in 2 mL serum-starved RPMI-1640
medium (containing 0.5% FBS) for 24 h. Then 1 mL
supernatant of MLS was added to each well and the plates were
incubated for 30 min (for measurement of MAPK
phos-phorylation). When the reaction was stopped, cell cultures
were washed twice with PBS, monolayers were detached from
the plastic by using a tissue scraper, and cells were
suspended in PBS (pH 7.4). Samples were sedimented for 10 min
at 3000×g (4 °C) and the pellets were then suspended in 10
mL lysis buffer (20 mmol/L HEPES, 2 mmol/L
MgCl2, 1 mmol/L EDTA, 2 mmol/L DTT, pH 7.4) followed by
homogenization in a glass-Teflon Potter homogenizer at 4 °C. The
homogenate was centrifuged at 3000×g for 4 min and the resulting
supernatants spun at 20 000×g for 30 min. Supernatants
obtained were diluted into 1 mg protein/mL for measurement
of MAPK phosphorylation. Protein content was determined
with bovine serum albumin (BSA) as a standard according
to the Bradford method[8].
Western blot analysis Protein samples (20 µg/lane) from
FLS were run on 12% sodium dodecylsulfate
(SDS)-polyacrylamide gel electrophoresis and transferred onto
polyvinylidene fluoride (PVDF) microporous membranes
(Millipore, Beijing, China) at 50 mA in transfer buffer
containing 25 mmol/L Tris-base, 192 mmol/L glycine, 20%
methanol. Western blot analysis was performed. Briefly,
blots were blocked with PBS saline plus 0.05% Tween 20 and
5% BSA for 1 h and then were incubated with appropriate
antibodies at 4 °C overnight. The membranes were washed
4-6 times and incubated with horseradish
peroxidase-conjugated secondary antibody for 2 h at room temperature. The
proteins were visualized by chemiluminescence using
hydrogen peroxide and luminol as a substrate using Kodak
X-AR film. All the experiments reported in the present study
were performed 3 times and the results were reproducible.
FLS proliferation assay AA FLS were isolated
according to the method outlined earlier and were cultured with
0.5% FBS-RPMI-1640 for 24 h. Then cells were resuspended
in 100 mL 10% FBS-RPMI-1640 medium containing 10 mg/L
LPS and 100 mL supernatant of MLS at a concentration of
2×1010 cell/L in 96-well flat-bottomed culture plates. The
cultures were incubated at 37 °C, 5%
CO2 for 48 h. A 10 mL sample of MTT (5 g/L) was added to each well, and the plates
were oscillated for 1 min on an oscillator and incubated at 37 °C for 2 h and 5% CO2. After incubation, the cultures were
centrifuged (760×g, 10 min). The
supernatants were aspirated, 120 µL of isopropanol (containing 0.04 mol/L HCl) was added
to each well and the mixture was oscillated for 30 s again.
Absorbance (A) was measured on an EJ301 ELISA Microwell
Reader at 570 nm. The results are presented as the average
absorbance and expressed as the mean of triplicate samples.
Statistical analysis Data are expressed as mean±SD.
Analysis of variance and the t-test were used to determine
significant differences between groups. P values less than
0.05 were considered to be significant.
Results
Effects of IL-1ra on secondary inflammatory
reaction Inflammatory polyarthritis was induced in all immunized
rats. The paw swelling occurred on d 13 after immunization.
Treatment with IL-1ra (10 and 40 mg/kg per d, ic, d 14-21)
diminished the swelling of the right hind paw measured on d 17
and d 21 after immunization (P<0.01, Figure 2).
Effect of IL-1ra on ultrastructure of synoviocytes
Intracellular changes were observed in AA rats. In type A
synoviocytes we observed reduction and curling of Golgi
bodies, swelling of mitochondria with decreased ridges and
increased vacuoles, and in type B synoviocytes we observed
accumulation of extracellular matrix and collagen, and
dilation of rough endoplasmic reticulum (RER). IL-1ra alleviated
these changes to some extent (Figure 3).
Effects of IL-1ra on cytokine production by MLS from
AA rats MLS from AA rats stimulated by LPS produced
more cytokines, including IL-1, PGE2, and
TNF-a, compared with the controls. The administration of IL-1ra (10 and 40
mg/kg, ic, d 14-21) decreased the production of IL-1,
PGE2, and TNF-a stimulated by LPS in MLS from AA
(P<0.01).
IL-1ra (2.5 mg/kg) also decreased the production of
PGE2 (P<0.01) and TNF-a (P<0.05) stimulated by MLS (Table 1).
Effects of IL-1ra on phosphorylation of JNK, ERK and
p38 MAPK in the synovial membrane of AA rats JNK, ERK,
and p38 phosphorylation increased in the synovial
membrane of AA rats. IL-1ra (40 and 10 mg/kg, ic, d 14-21)
inhibited the phosphorylation of MAPK, whereas IL-1ra (2.5 mg/kg) had no significant effect on MAPK phosphorylation
in the synovial membrane of AA rats (Figure 4).
Effects of supernatant of MLS from AA rats treated with
IL-1ra on JNK, ERK and p38 phosphorylation in AA
FLS Supernatant of MLS from AA rats induced more
phosphorylation of MAPK, including JNK, ERK, and p38, in AA FLS
than that from control rats. The supernatant of MLS from
AA rats treated with IL-1ra (40 and 10 mg/kg, ic, d 14-21)
induced less phosphorylation of MAPK in AA FLS than
that from AA rats (Figure 5).
Effects of supernatant of MLS from AA rats treated with
IL-1ra on FLS proliferation Compared with supernatant of
MLS from control rats, the supernatant of MLS from AA rats
increased cell proliferation in AA FLS. The supernatant of
MLS from AA rats treated with IL-1ra (40 or 10 mg/kg, ic, d
14-21) decreased cell proliferation in AA FLS more than that
from AA rats (Table 2).
Discussion
In the present study, we found that IL-1ra inhibited
second inflammatory reactions and modulated the
ultrastructure of synoviocytes in AA rats. Furthermore, we showed
that IL-1ra modulated the production of pro-inflammatory
mediators by MLS and inhibited the phosphorylation of
MAPK in FLS.
The characteristic pathological findings of RA synovitis
are aberrant proliferation of synovial lining cells,
neova-scularization by small vessels, accumulation of
inflammatory cells in the synovium, and subsequent degradation of
cartilage matrix. In particular, this cartilage degradation has
long been explained by the actions of extracellularly secreted
matrix metalloproteinases released from synoviocytes and
chondrocytes stimulated by several cytokines, including
IL-1 and TNF-a[9,10]. It has been reported that the majority of
rheumatoid synovial cells consist of 3 different cell types:
spindle-shaped FLS (Thy-1+), dendritic-like synoviocytes
(DLS), and large, round MLS (CD68+). FLS is a major part of
the invasive pannus, a vascular and fibrous granulation
tissue arising from the joint recesses and extending onto the
surface of cartilage. Activation of FLS in
vitro generates several functional responses that may considerably
contribute to joint pathology in RA; that is, the production of matrix
components, soluble mediators, or matrix-degrading
enzymes[3,11]. There are 2 types of synoviocytes, divided on the basis of
their ultrastructure. Type A synoviocytes are derived from
MLS and type B synoviocytes derive from FLS. Golgi
bodies in type A synoviocytes mainly take part in secretory
functions, whereas the mitochondrion is the energy provider
for cell metabolism. In type B synoviocytes, however, the
rough endoplasmic reticulum is where proteins are processed
and secreted. We also found that the morphology of type A
synoviocytes and type B synoviocytes from rats with AA
was changed, accompanying an increase in the level of IL-1,
TNF-a, and PGE2 produced by synoviocytes in these rats[12]. In the present study we showed that the secretion
and metabolism of synoviocytes from AA rats became
hyperfunctional and IL-1ra amended the morphological changes
in synoviocytes. It is well known that the activation of
monocytes/macrophages plays a critical role in inducing
inflammatory responses, including AA. Macrophages and
macrophage-like synoviocytes stimulated by LPS or other
inflammatory factors release large quantities of various
proinflammatory cytokines including TNF, IL-1,
PGE[12-14]. p38 and ERK play important roles in LPS-induced signaling
in macrophages[15]. Results from the present study also
showed that MLS in vitro produced excessive amounts of
pro-inflammatory cytokines, including IL-1, TNF-a, and
PGE2 stimulated by LPS, and that those cytokines could be
inhibited by IL-1ra.
In vitro, MLS and FLS are major sources of several
pro-inflammatory cytokines, such as IL-1, IL-6,
TNF-a, which promote the induction of adhesion molecules and
proteinase gene expression, and play a major role in the progression
of joint destruction and synovial
proliferation[16]. It has been reported that culture supernatants from synoviocytes
obtained from patients with RA have mitogenic
activity[17]. Recent reports have shown that Ras-MAPK signaling
pathways are involved in the activation of FLS and the
destruction of bone in arthritic joints induced by
IL-1[18]. MAPK activation is detected in synovial tissue from RA. ERK activation is localized around synovial microvessels, JNK
activation is localized around and within mononuclear cell
infiltrates, and p38 MAPK activation is observed in the
synovial lining layer and in synovial endothelial
cells[19]. Signaling through stress- and mitogen-activated protein kinase
(SAPK/MAPK) pathways in synoviocytes, which is induced
by IL-1 and TNF-a, is a typical feature of chronic synovitis
in RA[19,20]. However, during signal transduction of IL-1 in
RA FLS, tyrosine phosphorylation is increased transiently,
and the MAPK cascade is activated in a few
minutes[21].
It has been reported that IL-1a, IL-1b, and IL-1ra are
present in fresh and cultured synovial cell samples of
synovium from RA. However, the IL-1ra:IL-1 ratios ranged
from 1.2 to 3.6, which is below the 10-100-fold excess of
IL-1ra needed to inhibit IL-1
bioactivity[22]. Hence the induced endogenous production of IL-1ra, in the presence of RA
synovitis, is too low to compete with the high affinity of
IL-1 for the cell receptors. Therefore, the presence of IL-1ra should
result in very effective prevention of IL-1 signal transduction,
particularly in the inflammatory site. In laboratory and
animal studies, inhibition of IL-1 by either antibodies to IL-1 or
IL-1ra proved beneficial to the
outcome[23]. It has been reported that FR167653, an inhibitor of IL-1 and TNF, inhibits
the phosphorylation of p38 MAPK[24]. However, there is
little information about the effects of IL-1ra on MAPK
phosphorylation in the synovial membrane in RA or AA.
In the present study, the phosphorylation of ERK, JNK,
and p38 was enhanced not only in the synovial membranes
of AA rats but also in AA FLS stimulated by supernatant of
MLS from AA rats. Accordingly, the proliferation of FLS
activated by supernatant of MLS from AA rats was also
enhanced. IL-1ra decreased the phosphorylation of ERK,
JNK, and p38 in the synovial membrane of AA rats. In
addition, the supernatant of MLS that came from AA rats
treated with IL-1ra and contained fewer proinflammatory
cytokines induced less MAPK phosphorylation and cell
proliferation in AA FLS. The results of the present study
indicate that IL-1ra inhibits AA through suppression of the
cytokine-signaling pathways between different types of
synoviocytes.
In summary, a variety of signals generated by cytokines
may play an important role in the development of AA. From
the present study, we conclude that IL-1ra exerts an
anti-inflammatory effect by modulating the ultrastructure of
synoviocytes, decreasing the production of proinflammatory
mediators by MLS, and inhibiting the phosphorylation of
MAPK in FLS.
References
1 Tehranzadeh J, Ashikyan O, Dascalos J, Dennehey C. Advanced
imaging of early rheumatoid arthritis. Magn Reson Imaging Clin
N Am 2004; 12: 707-26.
2 Hunter D, Allaire S. Combination disease-modifying
antirheumatic drug therapy reduced work disability in early rheumatoid
arthritis. Arthritis Rheum 2004; 50: 55-62.
3 Zimmermann T, Kunisch E, Pfeiffer R, Hirth A, Stahl HD, Sack
U, et al. Isolation and characterization of rheumatoid arthritis
synovial fibroblasts from primary culture: primary culture cells
markedly differ from fourth-passage cells. Arthritis Res 2001; 3:
72-6.
4 Gabay C, Arend WP. Treatment of rheumatoid arthritis with
IL-1 inhibitors. Springer Semin Immunopathol 1998; 20: 229-46.
5 Schiff MH. Role of interleukin 1 and interleukin 1 receptor
antagonist in the mediation of rheumatoid arthritis. Ann Rheum
Dis 2000; 59: 103-8.
6 Jacobson PB, Morgan SJ, Wilcox DM, Nguyen
P, Ratajczak CA, Carlson RP, et
al. A new spin on an old model: in
vivo evaluation of disease progression by magnetic resonance imaging with
respect to standard inflammatory parameters and histopathology
in the adjuvant arthritic rat. Arthritis Rheum 1999; 42: 2060-73.
7 Ding CH, Li Q, Xiong ZY, Zhou AW, Jones G, Xu SY. Oral
administration of type II collagen suppresses pro-inflammatory
mediators production by synoviocytes in rats with adjuvant
arthritis. Clin Exp Immunol 2003; 132: 416-23
8 Bradford MM. A rapid and sensitive method for quantitation of
microgram quantities of protein utilizing the principle of
protein-dye binding. Anal Biochem 1976; 72: 248-54.
9 Walakovits LA, Moore VL, Bhardwaj N, Gallick GS, Lark MW.
Detection of stromelysin and collagenase in synovial fluid from
patients with rheumatoid arthritis and posttraumatic knee injury.
Arthritis Rheum 1992; 35: 35-42.
10 Langdon C, Leith J, Smith F, Richard CD. Oncostatin M
stimulates monocyte chemoattractant protein-1- and
interleukin-1-induced matrix metalloproteinase-1 production by human
synovial fibroblasts in vitro. Arthritis Rheum 1997; 40:
2139-46.
11 Neidhart M, Seemayer CA, Hummel KM, Michel BA, Gay RE,
Gay S. Functional characterization of adherent synovial fluid
cells in rheumatoid arthritis: destructive potential
in vitro and in vivo. Arthritis Rheum 2003; 48: 1873-80.
12 Dai M, Wei W, Shen YX, Zheng YQ. Glucosides of
Chaenomeles speciosa remit rat adjuvant arthritis by inhibiting synoviocyte
activities. Acta Pharmacol Sin 2003; 24: 1161-6.
13 Xu SJ, Gao WJ, Cong B, Yao YX, Gu ZY. Effect of
lipopolysaccharide on expression and characterization of cholecystokinin
receptors in rat pulmonary interstitial macrophages. Acta
Pharmacol Sin 2004; 25: 1347-53.
14 Li WD, Ran GX, Teng HL, Lin ZB. Dynamic effects of
leflunomide on IL-1, IL-6, and TNF-a activity produced from
peritoneal macrophages in adjuvant arthritis rats. Acta Pharmacol
Sin 2002; 23: 752-6.
15 Olsson S, Sundler R. The role of lipid rafts in LPS-induced
signaling in a macrophage cell line. Mol Immunol 2005; 16: [Epub
ahead of print]
16 Nanki T, Nagasaka K, Hayashida K, Saita Y, Miyasaka N.
Chemokines regulate IL-6 and IL-8 production by fibroblast-like
synoviocytes from patients with rheumatoid arthritis. J Immunol
2001; 167: 5381-5.
17 Melnyk VO, Shipley GD, Sternfeld MD, Sherman L, Rosenbaum
JT. Synoviocytes synthesize, bind, and respond to basic
fibroblast growth factor. Arthritis Rheum 1990; 33: 493-500.
18 Yamamoto A, Fukuda A, Seto H. Suppression of arthritic bone
destruction by adenovirus-mediated dominant-negative
Ras gene transfer to synoviocytes and osteoclasts. Arthritis Rheum 2003;
48: 2682-92.
19 Schett G, Tohidast-Akrad M, Smolen JS, Schmid BJ, Steiner CW,
Bitzan P, et al. Activation, differential localization, and
regulation of the stress-activated protein kinases, extracellular
signal-regulated kinase, c-JUN N-terminal kinase, and p38
mitogen-activated protein kinase, in synovial tissue and cells in
rheumatoid arthritis. Arthritis Rheum 2000; 43: 2501-12.
20 Foster ML, Halley F, Souness JE. Potential of p38 inhibitors in
the treatment of rheumatoid arthritis. Drug News Perspect 2000;
13: 488-97.
21 Lu H, Sun T, Yao L, Zhang Y. Role of protein tyrosine kinase in
IL-1 beta induced activation of mitogen-activated protein
kinase in fibroblast-like synoviocytes of rheumatoid arthritis. Chin
Med J 2000; 113: 872-6.
22 Firestein GS, Boyle DL, Yu C, Paine MM, Whisenand TD,
Zvaifler NJ, et al. Synovial interleukin-1 receptor antagonist
and interleukin-1 balance in rheumatoid arthritis. Arthritis Rheum
1994; 37: 644-52.
23 Cutolo M. IL-1 Ra: its role in rheumatoid arthritis. Reumatism
2004; 56: 41-5.
24 Yao HW, Yue L, Chen JQ. Effects and mechanisms of FR167653,
a dual inhibitor of interleukin-1 and tumor necrosis factor, on
adjuvant arthritis in rats. Int Immunopharmacol 2004; 4:
1625-32.
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