Oxidized LDL binding to LOX-1 enhances MCP-1 expression in cultured human articular chondrocytes.
OBJECTIVE
It has been suggested that oxidized low-density lipoprotein (ox-LDL) has some roles in progression of osteoarthritis. The purpose of this study is to investigate whether ox-LDL binding to lectin-like ox-LDL receptor 1 (LOX-1) enhances monocyte chemoattractant protein 1 (MCP-1) expression in cultured human articular chondrocytes (HACs).


METHODS
The time course and dose response of MCP-1 mRNA expression and MCP-1 protein release into medium following ox-LDL stimulation were investigated using quantitative Real time PCR (delta-delta Ct method) and enzyme-linked immunosorbent assay (ELISA), respectively. To examine the receptor specificity of ox-LDL action, HACs were preincubated with anti-human LOX-1 monoclonal antibody (TS92).


RESULTS
A time-course study revealed that MCP-1 mRNA expression increased 5.09+/-0.86 fold 12h after ox-LDL stimulation compared to time-0. ox-LDL stimulation increased MCP-1 protein level in conditioned medium in a time-dependent manner. Increased MCP-1 level was evident 6h after stimulation, reaching 830+/-91 pg/ml at 24h (33+/-8 pg/ml at time-0). Dose responses of MCP-1 expression were also evident in mRNA and protein levels. Pretreatment with TS92 markedly suppressed these stimulating effects of ox-LDL, although that with non-specific IgG did not. Native LDL did not affect MCP-1 expression.


CONCLUSIONS
Our results suggest that ox-LDL enhances MCP-1 expression in HACs and supports the hypothesis that ox-LDL is involved in cartilage degeneration.
Akagi
M
M
Department of Orthopaedic Surgery, Kinki University School of Medicine, Osaka-Sayama City, Osaka, Japan. makagi@med.kindai.ac.jp
Ueda
A
A
Teramura
T
T
Kanata
S
S
Sawamura
T
T
Hamanishi
C
C
D002358:Cartilage, Articular / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D002478:Cells, Cultured; D018932:Chemokine CCL2 / Q000235:genetics / Q000378:metabolism*; D019902:Chondrocytes / Q000187:drug effects / Q000378:metabolism*; D017077:Culture Media, Conditioned; D004305:Dose-Response Relationship, Drug; D015870:Gene Expression; D006801:Humans; D053583:Interleukin-1beta / Q000494:pharmacology; D008077:Lipoproteins, LDL / Q000378:metabolism* / Q000494:pharmacology; D012333:RNA, Messenger / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods; D051127:Scavenger Receptors, Class E / Q000235:genetics / Q000378:metabolism*
C111835:CCL2 protein, human; D018932:Chemokine CCL2; D017077:Culture Media, Conditioned; D053583:Interleukin-1beta; D008077:Lipoproteins, LDL; C495137:OLR1 protein, human; D012333:RNA, Messenger; D051127:Scavenger Receptors, Class E; C099252:oxidized low density lipoprotein