Effects of immunosuppressive treatment on microsomal prostaglandin E synthase 1 and cyclooxygenases expression in muscle tissue of patients with polymyositis or dermatomyositis
- M Korotkova1,
- S Barbasso Helmers1,
- I Loell1,
- H Alexanderson1,
- C Grundtman1,
- C Dorph1,
- I E Lundberg1,
- P-J Jakobsson2
- 1Department of Medicine, Rheumatology Unit, Karolinska Institutet/Karolinska University Hospital, Solna, Stockholm, Sweden
- 2Department of Medicine, Rheumatology Unit and Karolinska Biomic Center, Karolinska Institutet, Stockholm, Sweden
- I E Lundberg, Rheumatology Unit, Department of Medicine, Karolinska Institutet, SE-17176 Stockholm, Sweden; Ingrid.Lundberg{at}ki.se
- Accepted 2 December 2007
- Published Online First 18 December 2007
Abstract
Objectives: To investigate the expression of microsomal prostaglandin E (PGE) synthase 1 (mPGES-1) and cyclooxygenase (COX) in muscle biopsies from patients with polymyositis or dermatomyositis before and after conventional immunosuppressive treatment.
Methods: mPGES-1 and COX expression was evaluated by immunohistochemistry in muscle tissue from healthy individuals and from patients with polymyositis or dermatomyositis before and after conventional immunosuppressive treatment. The number of inflammatory cell infiltrates, T lymphocytes and macrophages was estimated before and after treatment. To localise the mPGES-1 expression double immunofluorescence was performed with antibodies against mPGES-1, CD3, CD68, CD163 and a fibroblast marker. A functional index was used to assess muscle function.
Results: In patients with myositis, mPGES-1, COX-2 and COX-1 expression was significantly higher compared to healthy individuals and associated with inflammatory cells. Double immunofluorescence demonstrated a predominant expression of mPGES-1 in macrophages. Conventional immunosuppressive treatment resulted in improved but still lower muscle function than normal. A decreased number of CD68-positive macrophages and reduced COX-2 expression in muscle tissue was also seen. By contrast, following the same treatment no significant changes were observed in muscle tissue regarding number of infiltrates, T lymphocytes, CD163-positive macrophages or mPGES-1 protein levels.
Conclusions: Increased expression of mPGES-1, COX-1 and COX-2 at protein level was observed in muscle tissue from patients with myositis compared to healthy individuals. Conventional immunosuppressive treatment led to a significant downregulation of COX-2 in myositis muscle tissue. However, the expression of mPGES-1 and COX-1 remained unchanged indicating a role of these enzymes in the chronicity of these diseases.
Footnotes
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Funding: This study was supported by grants from King Gustaf V 80 Years Foundation, The Swedish Society of Medicine, The Swedish Rheumatism Association, The Swedish Research Council 2005-74X-14045-02A and 2004–5259, Professor Nanna Svartz Foundation, Magnus Bergvall Foundation, Börje Dahlin Foundation, Karolinska Institutet Foundation and Foundation Clas Groschinskys Minnesfond.
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Competing interests: None.
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Ethics approval: The approval was granted by the Ethics Committee at the Karolinska University Hospital, Stockholm and all patients and controls gave their informed consent to participate in the study.
