Tumor necrosis factor inhibition modulates thrombospondin-1 expression in human inflammatory joint disease through altered NR4A2 activity.
We examined thrombospondin-1 (THBS1, alias TSP-1) expression in human synovial tissue (ST) during the resolution phase of chronic inflammation and elucidated its transcriptional regulation by the orphan receptor 4A2 (NR4A2). In vivo, rheumatoid arthritis (RA) serum and ST revealed altered expression levels and tissue distribution of TSP-1. After anti-tumor necrosis factor therapy, a reciprocal relationship between TSP-1 and NR4A2 expression levels was measured in patients with clinical and ST responses to biological treatment. In vitro, primary RA fibroblast-like synoviocytes (FLSs) expressed minimal TSP-1 mRNA levels with high transcript levels of NR4A2, vascular endothelial growth factor (VEGF), and IL-8 measured. Hypoxic modulation of RA FLSs resulted in inverse expression levels of TSP-1 compared with NR4A2, IL-8, and VEGF. Ectopic NR4A2 expression led to reduced TSP-1 mRNA and protein levels with concomitant increases in proangiogenic mediators. NR4A2 transcriptional activity, independent of DNA binding, repressed the hTSP-1 promoter leading to reduced mRNA and protein release in immortalized K4IM FLSs. Bioinformatic and deletion studies identified a 5' region of the TSP-1 promoter repressed by NR4A2 and proangiogenic transcription factors, including NF-κB and Ets1/2. Stable depletion of NR4A2 levels resulted in a shift in the TSP-1/VEGF expression ratio. Thus, modulation of TSP-1 expression is achieved through anti-tumor necrosis factor therapy effects on specific transcriptional networks, suggesting that enhanced TSP-1 expression may help restore tissue homeostasis during resolution of inflammation.
UCD Veterinary Sciences Centre, University College Dublin, Belfield, Ireland.
Jason P
JP
McMorrow
UCD Veterinary Sciences Centre, University College Dublin, Belfield, Ireland.
Daniel
D
Crean
UCD Veterinary Sciences Centre, University College Dublin, Belfield, Ireland.
Martina
M
Gogarty
UCD Veterinary Sciences Centre, University College Dublin, Belfield, Ireland.
Aisling
A
Smyth
Conway Institute for Biomolecular and Biomedical Research, University College Dublin, Belfield, Ireland; Department of Rheumatology, St. Vincent's University Hospital, University College Dublin, Dublin, Ireland.
Mary
M
Connolly
Conway Institute for Biomolecular and Biomedical Research, University College Dublin, Belfield, Ireland.
Eoin
E
Cummins
Conway Institute for Biomolecular and Biomedical Research, University College Dublin, Belfield, Ireland; Department of Rheumatology, St. Vincent's University Hospital, University College Dublin, Dublin, Ireland.
Douglas
D
Veale
Conway Institute for Biomolecular and Biomedical Research, University College Dublin, Belfield, Ireland; Department of Rheumatology, St. Vincent's University Hospital, University College Dublin, Dublin, Ireland.
Ursula
U
Fearon
Division of Clinical Immunology and Rheumatology, Academic Medical Center/University of Amsterdam, Amsterdam, The Netherlands.
Paul P
PP
Tak
Conway Institute for Biomolecular and Biomedical Research, University College Dublin, Belfield, Ireland; Department of Rheumatology, St. Vincent's University Hospital, University College Dublin, Dublin, Ireland.
Oliver
O
Fitzgerald
UCD Veterinary Sciences Centre, University College Dublin, Belfield, Ireland; Conway Institute for Biomolecular and Biomedical Research, University College Dublin, Belfield, Ireland. Electronic address: evelyn.murphy@ucd.ie.
Evelyn P
EP
Murphy
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D043925:Angiogenesis Inducing Agents / Q000378:metabolism; D001172:Arthritis, Rheumatoid / Q000235:genetics* / Q000473:pathology*; D002478:Cells, Cultured; D004247:DNA / Q000378:metabolism; D005347:Fibroblasts / Q000378:metabolism / Q000473:pathology; D005786:Gene Expression Regulation; D006801:Humans; D007249:Inflammation / Q000473:pathology*; D007596:Joints / Q000473:pathology*; D008875:Middle Aged; D057126:Nuclear Receptor Subfamily 4, Group A, Member 2 / Q000097:blood / Q000235:genetics / Q000378:metabolism*; D011401:Promoter Regions, Genetic / Q000235:genetics; D011485:Protein Binding / Q000235:genetics; D013583:Synovial Membrane / Q000378:metabolism / Q000473:pathology; D019700:Thrombospondin 1 / Q000097:blood / Q000235:genetics*; D014158:Transcription, Genetic; D014409:Tumor Necrosis Factor-alpha / Q000037:antagonists & inhibitors* / Q000378:metabolism; D042461:Vascular Endothelial Growth Factor A / Q000378:metabolism
D043925:Angiogenesis Inducing Agents; C539882:NR4A2 protein, human; D057126:Nuclear Receptor Subfamily 4, Group A, Member 2; D019700:Thrombospondin 1; D014409:Tumor Necrosis Factor-alpha; D042461:Vascular Endothelial Growth Factor A; D004247:DNA