Regulation of Tenascin-C Expression by Tumor Necrosis Factor-a in Cultured Human Osteoarthritis Chondrocytes

YUTAKA NAKOSHI, MASAHIRO HASEGAWA, AKIHIRO SUDO, TOSHIMICHI YOSHIDA, and ATSUMASA UCHIDA

ABSTRACT.

Objective. Expression of tenascin-C reappears in articular cartilage of persons with osteoarthritis (OA), while it is almost abolished in normal mature cartilage. Tumor necrosis factor-a (TNF-a), a proinflammatory cytokine, is upregulated in OA cartilage and is involved in the progression of OA, and stimulates tenascin-C expression in other types of cells. We investigated regulation of tenascin-C expression by TNF-a through nuclear factor-kB (NF-kB) in OA cartilage in vivo and in vitro.

Methods. Human articular cartilages were obtained from patients with OA and immunofluorescence examination of tenascin-C and the activated RelA subunit was performed. Cultured chondrocytes isolated from human OA cartilage were treated with TNF-a and with SN50. Activation of RelA subunit of NF-kB was examined by immunolabeling. Changes in tenascin-C protein concentrations were determined by immunofluorescence of cells after monensin treatment and Western blot analysis of the cell lysates, and mRNA levels were analyzed by quantitative real-time polymerase chain reaction.

Results. Increased intensity of tenascin-C staining was observed in the damaged cartilage compared with normal cartilage. Activated RelA staining in chondrocyte nuclei was prominent in tenascin-C-positive areas of OA cartilage. Treatment of cultured chondrocytes by TNF-a induced translocation of activated RelA to the nuclei, followed by upregulation of tenascin-C expression in both mRNA and protein. Treatment with SN50 inhibited increases of RelA and tenascin-C expression in chondrocytes.

Conclusion. TNF-a stimulated tenascin-C expression through NF-kB signaling with RelA activation in cultured OA chondrocytes, suggesting involvement of tenascin-C in OA cartilage remodeling. (First Release Dec 1 2007; J Rheumatol 2008;35:147-52)

Key Indexing Terms:

TENASCIN-C
TUMOR NECROSIS FACTOR-a
OSTEOARTHRITIS
CHONDROCYTES

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From the Department of Orthopedic Surgery and Department of Pathology and Matrix Biology, Mie University Graduate School of Medicine, Mie, Japan.

Y. Nakoshi, MD; M. Hasegawa MD, PhD; A. Sudo, MD, PhD, Department of Orthopedic Surgery; T. Yoshida, MD, PhD, Department of Pathology and Matrix Biology; A. Uchida, MD, PhD, Department of Orthopedic Surgery.

Address reprint requests to Dr. M. Hasegawa, Department of Orthopedic Surgery, Mie University Graduate School of Medicine, 2-174 Edobashi, Tsu City, Mie 514-8507, Japan. E-mail: masahase@clin.medic.mie-u.ac.jp

Accepted for publication August 23, 2007.

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