Cytokine Interferon-γ suppresses the function of capsule myofibroblasts and induces cell apoptosis.
Myofibroblasts (MFs), a contractile subset of fibroblasts, play a pivotal role in physiological wound healing and in the development of many fibroconnective disorders. The complex cytokine network regulating the function of MFs in joint stiffness is still poorly understood. In this in vitro study, we investigated the effect of the cytokine Interferon-gamma (IFN-γ) on MFs isolated from human joint capsules. MFs were cultivated either in the presence of increasing concentrations of IFN-γ alone or in combination with IFN-γ neutralizing antibodies. Cell viability, cytotoxicity, apoptosis, and mRNA gene expression of the MF markers alpha-smooth muscle actin (α-SMA) and collagen type I were analyzed in MF cultures. Contraction potential was analyzed in an established collagen gel contraction assay simulating the extracellular matrix. Using immunofluorescence staining, we could verify that MFs express IFN-γ-receptor (R)-1 on their membrane. IFN-γ decreased MF viability and significantly elevated the apoptosis rate in a dose-dependent manner. IFN-γ down-regulated α-SMA and collagen type I mRNA expression which was associated with a diminished MF mediated contraction of the gel matrices. These effects were suppressed by simultaneous treatment of cells with a neutralizing IFN-γ antibody. Our experiments confirm the hypothesis that the cytokine IFN-γ is a crucial component of the regulatory network of capsule MFs. IFN-γ notably influences the ability of MFs to contract collagen matrices by suppressing α-SMA gene expression. IFN-γ is toxic for MFs in high concentrations and may negatively regulate the number of pro-fibrotic MFs during the healing process via induction of cell apoptosis. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:2524-2533, 2017.
Department of Orthopaedics and Traumatology, University Medical Centre of the Johannes Gutenberg-University of Mainz, Mainz, Germany.
Stefan G
SG
Mattyasovszky
Department of Orthopaedics and Traumatology, University Medical Centre of the Johannes Gutenberg-University of Mainz, Mainz, Germany.
Stefan
S
Mausbach
Department of Orthopaedics and Traumatology, University Medical Centre of the Johannes Gutenberg-University of Mainz, Mainz, Germany.
Ulrike
U
Ritz
Department of Orthopaedics and Traumatology, University Medical Centre of the Johannes Gutenberg-University of Mainz, Mainz, Germany.
Jochen
J
Wollstädter
Institute for Medical Biometry, Epidemiology and Computer Science, University Medical Centre of the Johannes Gutenberg-University of Mainz, Mainz, Germany.
Irene
I
Schmidtmann
Department of Orthopaedics and Traumatology, University Medical Centre of the Johannes Gutenberg-University of Mainz, Mainz, Germany.
Andreas
A
Baranowski
Department of Orthopaedics and Traumatology, University Medical Centre of the Johannes Gutenberg-University of Mainz, Mainz, Germany.
Phillipp
P
Drees
Department of Orthopaedics and Traumatology, University Medical Centre of the Johannes Gutenberg-University of Mainz, Mainz, Germany.
Pol M
PM
Rommens
Department of Orthopaedics and Traumatology, University Medical Centre of the Johannes Gutenberg-University of Mainz, Mainz, Germany.
Alexander
A
Hofmann
D000199:Actins / Q000378:metabolism; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D017209:Apoptosis; D024042:Collagen Type I; D005260:Female; D006801:Humans; D007371:Interferon-gamma / Q000502:physiology*; D017746:Joint Capsule / Q000166:cytology / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D058628:Myofibroblasts / Q000502:physiology*; D061251:Primary Cell Culture; D017471:Receptors, Interferon / Q000378:metabolism; D000096743:Interferon gamma Receptor
D000199:Actins; D024042:Collagen Type I; D007371:Interferon-gamma; D017471:Receptors, Interferon; D000096743:Interferon gamma Receptor; C541116:ACTA2 protein, human
interferon-γ; joint capsule; joint stiffness; myofibroblast