Modulatory effects of inflammation and therapy on GDF-5 expression in rheumatoid arthritis synovium.
OBJECTIVE
Growth differentiation factor-5 (GDF-5), a member of the transforming growth factor (TGF)-beta family, is involved in joint development during embryogenesis and has the potential to regenerate cartilage in adult animals. As progression of chronic joint diseases is influenced by cytokines of the synovial tissue, we examined the expression and effects of GDF-5 in this tissue.


METHODS
Microarray experiments were investigated for differential expression of GDF-5 in synovial tissues, synovial fibroblasts, and peripheral blood cells. GDF-5 expression was validated by semiquantitative reverse transcriptase polymerase chain reaction (RT-PCR), immunohistochemistry, double immunofluorescence, and in situ hybridization in synovial tissue of normal donors (ND) and patients with osteoarthritis (OA) and rheumatoid arthritis (RA). Effects of inflammation and therapy were investigated in RA and OA fibroblasts after stimulation with interleukin (IL)-1beta, tumour necrosis factor (TNF)-alpha, methotrexate (MTX), and prednisolone. The influence of GDF-5 on macrophages was studied by chemotaxis assay.


RESULTS
Microarray analysis and immunostaining revealed expression predominantly in synovial fibroblasts. Compared to patients without immunomodulating drugs, expression of GDF-5 was decreased significantly in patients receiving glucocorticoids and/or disease-modifying antirheumatic drugs (DMARDs) (p = 0.007), but did not differ between the total group of ND, OA, and RA. Stimulation with prednisolone and TNFalpha reduced GDF-5 expression in OA and RA fibroblasts, whereas MTX and IL-1beta revealed minor or no relevant change. GDF-5 also reduced cell migration of macrophages (p<0.001).


CONCLUSIONS
GDF-5 is expressed in synovial fibroblasts and may counteract macrophage infiltration. Its modulation by inflammation and therapy suggests that glucocorticoids play a conflicting role by suppressing not only inflammation but also putative mechanisms of repair.
Bramlage
C P
CP
Department of Medicine, Nephrology and Rheumatology, Georg-August-University Gottingen, Gottingen. c.bramlage@med.uni-goettingen.de
Kaps
C
C
Ungethüm
U
U
Bramlage
P
P
Koziolek
M
M
Wessels
J
J
Krenn
V
V
Pruss
A
A
Müller
G A
GA
Strutz
F
F
Burmester
G-R
GR
Häupl
T
T
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D018501:Antirheumatic Agents / Q000494:pharmacology / Q000627:therapeutic use*; D001172:Arthritis, Rheumatoid / Q000188:drug therapy / Q000378:metabolism*; D016022:Case-Control Studies; D054442:Cell Migration Assays, Macrophage; D016207:Cytokines / Q000494:pharmacology; D015536:Down-Regulation; D005347:Fibroblasts / Q000187:drug effects / Q000378:metabolism; D015870:Gene Expression; D005938:Glucocorticoids / Q000494:pharmacology / Q000627:therapeutic use*; D055428:Growth Differentiation Factor 5 / Q000378:metabolism*; D006801:Humans; D007150:Immunohistochemistry; D007165:Immunosuppression Therapy; D017403:In Situ Hybridization; D008727:Methotrexate / Q000494:pharmacology / Q000627:therapeutic use; D008875:Middle Aged; D020411:Oligonucleotide Array Sequence Analysis; D011239:Prednisolone / Q000494:pharmacology / Q000627:therapeutic use; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013583:Synovial Membrane / Q000187:drug effects / Q000378:metabolism*; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology
D018501:Antirheumatic Agents; D016207:Cytokines; D005938:Glucocorticoids; D055428:Growth Differentiation Factor 5; D014409:Tumor Necrosis Factor-alpha; D011239:Prednisolone; D008727:Methotrexate