Volume 50, Issue 11 pp. 3495-3503
Research Article

Lectin-like oxidized low-density lipoprotein receptor 1 mediates matrix metalloproteinase 3 synthesis enhanced by oxidized low-density lipoprotein in rheumatoid arthritis cartilage

Takumi Kakinuma

Takumi Kakinuma

Kyoto University Graduate School of Medicine, Kyoto, Japan, and National Cardiovascular Center Research Institute, Osaka, Japan

Search for more papers by this author
Tadashi Yasuda

Corresponding Author

Tadashi Yasuda

Kyoto University Graduate School of Medicine, Kyoto, Japan, and Faculty of Health, Budo, and Sports Studies, Tenri University, Tenri, Japan

Department of Orthopaedic Surgery, Kyoto University Graduate School of Medicine, 54 Kawahara-cho, Shogoin, Sakyo-ku, Kyoto 606-8507, JapanSearch for more papers by this author
Takefumi Nakagawa

Takefumi Nakagawa

Kyoto University Graduate School of Medicine, Kyoto, Japan

Search for more papers by this author
Teruko Hiramitsu

Teruko Hiramitsu

Kyoto University Graduate School of Medicine, Kyoto, Japan

Search for more papers by this author
Miki Akiyoshi

Miki Akiyoshi

Kyoto University Graduate School of Medicine, Kyoto, Japan

Search for more papers by this author
Masao Akagi

Masao Akagi

Kinki University School of Medicine, Osaka, Japan

Search for more papers by this author
Tatsuya Sawamura

Tatsuya Sawamura

National Cardiovascular Center Research Institute, Osaka, Japan

Search for more papers by this author
Takashi Nakamura

Takashi Nakamura

Kyoto University Graduate School of Medicine, Kyoto, Japan

Search for more papers by this author
First published: 04 November 2004
Citations: 40

Abstract

Objective

To investigate for the presence of oxidized low-density lipoprotein (ox-LDL) and lectin-like oxidized LDL receptor 1 (LOX-1) in cartilage specimens from rheumatoid arthritis (RA) joints and to determine whether the interaction of ox-LDL with LOX-1 can induce matrix metalloproteinase 3 (MMP-3) in articular cartilage explant culture.

Methods

Human articular cartilage specimens obtained from patients with RA, osteoarthritis (OA), and femoral neck fractures were examined for LOX-1 and ox-LDL by confocal fluorescence microscopy. The association between ox-LDL and LOX-1 was evaluated by immunofluorescence analysis. Articular cartilage specimens from patients with femoral neck fractures were incubated with ox-LDL, with or without preincubation with neutralizing anti–LOX-1 antibody. MMP-3 synthesis by chondrocytes in explant cartilage was evaluated by immunofluorescence, and protein secretion into conditioned medium was monitored by immunoblotting and enzyme-linked immunosorbent assay.

Results

The majority of the RA chondrocytes stained positively with both anti–LOX-1 and anti–ox-LDL antibodies; however, no positive cells were found in OA and normal cartilage specimens. Anti–LOX-1 antibody suppressed the binding of DiI-labeled ox-LDL to chondrocytes in explant culture, suggesting that the interaction was mediated by LOX-1. In contrast to native LDL, ox-LDL induced MMP-3 synthesis by articular chondrocytes in association with the induction of LOX-1, which resulted in enhanced secretion of MMP-3 into the culture medium. Anti–LOX-1 antibody reversed ox-LDL–stimulated MMP-3 synthesis to control levels.

Conclusion

Ox-LDL, principally mediated by LOX-1, enhanced MMP-3 production in articular chondrocytes. Increased accumulation of ox-LDL with elevated expression of LOX-1 in RA cartilage indicates a specific role of the receptor–ligand interaction in cartilage pathology in RA.

The full text of this article hosted at iucr.org is unavailable due to technical difficulties.

click me