The effect of the pro-inflammatory cytokine tumor necrosis factor-alpha on human joint capsule myofibroblasts.
BACKGROUND
Previous studies have shown that the number of myoblastically differentiated fibroblasts known as myofibroblasts (MFs) is significantly increased in stiff joint capsules, indicating their crucial role in the pathogenesis of post-traumatic joint stiffness. Although the mode of MFs' function has been well defined for different diseases associated with tissue fibrosis, the underlying mechanisms of their regulation in the pathogenesis of post-traumatic joint capsule contracture are largely unknown.


METHODS
In this study, we examined the impact of the pro-inflammatory cytokine tumor necrosis factor-alpha (TNF-alpha) on cellular functions of human joint capsule MFs. MFs were challenged with different concentrations of TNF-alpha with or without both its specifically inactivating antibody infliximab (IFX) and cyclooxygenase-2 (COX2) inhibitor diclofenac. Cell proliferation, gene expression of both alpha-smooth muscle actin (alpha-SMA) and collagen type I, the synthesis of prostaglandin derivates E2, F1A, and F2A, as well as the ability to contract the extracellular matrix were assayed in monolayers and in a three-dimensional collagen gel contraction model. The alpha-SMA and COX2 protein expressions were evaluated by immunofluorescence staining and Western blot analysis.


RESULTS
The results indicate that TNF-alpha promotes cell viability and proliferation of MFs, but significantly inhibits the contraction of the extracellular matrix in a dose-dependent manner. This effect was associated with downregulation of alpha-SMA and collagen type I by TNF-alpha application. Furthermore, we found a significant time-dependent upregulation of prostaglandin E2 synthesis upon TNF-alpha treatment. The effect of TNF-alpha on COX2-positive MFs could be specifically prevented by IFX and partially reduced by the COX2 inhibitor diclofenac.


CONCLUSIONS
Our results provide evidence that TNF-alpha specifically modulates the function of MFs through regulation of prostaglandin E2 synthesis and therefore may play a crucial role in the pathogenesis of joint capsule contractures.
Mattyasovszky
Stefan G
SG
Department of Trauma and Orthopaedic Surgery, Johannes Gutenberg University School of Medicine, Langenbeckstr, 1, 55101 Mainz, Germany. Stefan.Mattyasovszky@gmx.de
Hofmann
Alexander
A
Brochhausen
Christoph
C
Ritz
Ulrike
U
Kuhn
Sebastian
S
Wollstädter
Jochen
J
Schulze-Koops
Hendrik
H
Müller
Lars P
LP
Watzer
Bernhard
B
Rommens
Pol M
PM
D000199:Actins / Q000096:biosynthesis; D000368:Aged; D000911:Antibodies, Monoclonal / Q000494:pharmacology; D018501:Antirheumatic Agents / Q000494:pharmacology; D015153:Blotting, Western; D049109:Cell Proliferation / Q000187:drug effects; D002478:Cells, Cultured; D024042:Collagen Type I / Q000096:biosynthesis; D003286:Contracture / Q000378:metabolism*; D051546:Cyclooxygenase 2 / Q000096:biosynthesis; D052246:Cyclooxygenase 2 Inhibitors / Q000494:pharmacology; D016207:Cytokines / Q000378:metabolism; D004008:Diclofenac / Q000494:pharmacology; D015237:Dinoprost / Q000096:biosynthesis; D015232:Dinoprostone / Q000096:biosynthesis; D004551:Elbow Joint / Q000473:pathology; D005109:Extracellular Matrix / Q000378:metabolism; D005260:Female; D005347:Fibroblasts / Q000187:drug effects / Q000378:metabolism*; D005455:Fluorescent Antibody Technique; D015870:Gene Expression / Q000187:drug effects; D006621:Hip Joint; D006801:Humans; D007150:Immunohistochemistry; D018836:Inflammation Mediators / Q000378:metabolism; D000069285:Infliximab; D017746:Joint Capsule / Q000378:metabolism* / Q000473:pathology; D008297:Male; D008875:Middle Aged; D011460:Prostaglandins F / Q000096:biosynthesis; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism*
D000199:Actins; D000911:Antibodies, Monoclonal; D018501:Antirheumatic Agents; D024042:Collagen Type I; D052246:Cyclooxygenase 2 Inhibitors; D016207:Cytokines; D018836:Inflammation Mediators; D011460:Prostaglandins F; D014409:Tumor Necrosis Factor-alpha; D004008:Diclofenac; D000069285:Infliximab; D015237:Dinoprost; D051546:Cyclooxygenase 2; D015232:Dinoprostone; C100006:prostaglandin F1