Visit our Expo - Redox and Inflammation signaling 2012

VIII. Inflammation specific signaling Poster VIII, 12
Molecular characterization of synovial fibroblasts from rheumatoid arthritis and their
reponse to diverse anti-inflammatory drugs
Valerie Gossye1, Karolien De Bosscher1, Dirk Elewaut2 and Guy Haegeman1
1Laboratory for Eukaryotic Gene Expression and Signal Transduction (LEGEST),
Department of Molecular Biology, Ghent University, Gent, Belgium. E-mail:
valerie.gossye@ugent.be, karolien.debosscher@ugent.be, guy.haegeman@ugent.be;
2Laboratory for Molecular Immunology and Inflammation, Department of
Rheumatology, Ghent University Hospital, Gent, Belgium. E-mail:
dirk.elewaut@ugent.be
Objective. Inflammation is a central feature of many chronically developing inflammatory and
immune diseases, including rheumatoid arthritis (RA). Although the cause of RA is at present not
completely understood, previous studies have shown that fibroblast-like synoviocytes (FLS) as part of
a complex cellular network, are crucial for disease progression as well as for joint destruction.
To date, the goal of treatment is to reduce joint inflammation and pain, maximize joint function, and
prevent joint destruction and deformity. However, current treatment regimens suffer major drawbacks.
For instance, the usage of glucocorticoids (GCs) is overshadowed by severe side effects, such as
diabetes, glaucoma and osteoporosis. Furthermore, occurrences of resistance to the therapeutic effects
of corticosteroids, as well as disease reactivation after cessation of GC therapy, have been reported.
Therefore, there is a particular need for the development of a new generation of drugs to treat these
diseases.
Hence, we undertook a detailed study of the molecular characteristics of primary FLS isolated
from the inflamed synovium of RA patients and investigated whether anti-inflammatory drugs, such as
GCs and Compound A (CpdA), a fully dissociated compound of plant origin for inflammatory gene
repression (see De Bosscher et al. PNAS, 102, 15827-15832, 2005), exert their anti-inflammatory
effects on these effector cells and examined their putative mode of action.
Results and Conclusions
1. Immunofluorescence studies demonstrate that, upon dexamethasone (DEX) or CpdA stimulation for
1 hour, the glucocorticoid receptor (GR) shifts from the cytoplasm to the nucleus, indicating that GR
translocation proceeds normally.
2. RT-PCR results showed that in FLS93 and FLS118 TNF-induced Interleukin-6 mRNA expression
levels were repressed by DEX more adequately than by CpdA, but vice versa in FLS120. Along the
same line, CpdA was found to be more effective in downregulating RANTES in FLS93 and FLS120,
whilst in FLS118 DEX appeared to be more effective. These data suggest that different patients show
a different response/sensitivity towards different therapeutics. Furthermore, we can also conclude that
in the same FLS different cytokines are differently modulated by either therapeutic agent.
3. Finally, we observed in all investigated FLS a fast ‘homologous’ down-regulation of GR, already
apparent after 7 hours of DEX induction. In addition, Western blot analysis results showed that
induction of FLS with TNF, in combination with DEX, results in downregulation of IkappaB-alpha
protein expression, as opposed to the TNF-only condition. We thus confirmed previous results of our
group, demonstrating that in L929sA fibroblasts DEX stimulation does not lead to upregulation of
IkappaB-alpha protein expression (De Bosscher et al., PNAS, 94, 13504-13509, 1997).
Altogether, these findings highlight the complexity of molecular signaling cascades suitable for
therapeutic intervention that underly the chronic inflammatory and destructive processes in RA.
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