Lectin-like oxidized low density lipoprotein receptor 1 (LOX-1) expression in human articular chondrocytes.
OBJECTIVE
To investigate the involvement of oxidized low density lipoprotein (ox-LDL) and the expression of its receptor lectin-like oxidized low density lipoprotein receptor 1 (LOX-1) in osteoarthritis, by determining the ox-LDL in synovial fluid and the expression of LOX-1 mRNA and protein in osteoarthritic as well as normal cartilage. In addition, the effect of ox-LDL on chondrocyte viability and the effect of ascorbic acid (a well-known anti-oxidant) on LOX-1 expression were studied.


METHODS
Fifteen patients were included in the study. Osteoarthritic articular cartilage was obtained from two distinct locations in the knee (n = 10) and hip (n = 5), specifically from weight-bearing and non-weight-bearing areas of the same joints. Five individuals were used as controls. mRNA and protein expression were studied by RT-PCR and immunofluorescence, respectively. Ox-LDL was measured in the synovial fluid and in paired serum samples from the patients using the ELISA method.


RESULTS
Ox-LDL was detected in the synovial fluid and its receptor LOX-1 was detected in cartilage from both weight-bearing and non-weight-bearing areas, whereas no LOX-1 expression was found in normal cartilage. Ox-LDL reduced chondrocyte viability in cell cultures, while the addition of ascorbic acid to osteoarthritic chondrocytes resulted in a decrease in LOX-1 mRNA expression.


CONCLUSIONS
The detection of LOX-1 mRNA and protein expression in osteoarthritic cartilage drawn from both weight-bearing and non-weight-bearing regions of the same patients suggest that LOX-1 may be involved in the progression and pathogenesis of osteoarthritis.
Simopoulou
T
T
Laboratory of Cytogenetics and Medical Genetics, University of Thessalia, Larissa, Greece.
Malizos
K N
KN
Tsezou
A
A
D000368:Aged; D000369:Aged, 80 and over; D001205:Ascorbic Acid / Q000494:pharmacology; D002358:Cartilage, Articular / Q000737:chemistry / Q000166:cytology; D002470:Cell Survival; D019902:Chondrocytes / Q000737:chemistry*; D005260:Female; D005455:Fluorescent Antibody Technique; D006801:Humans; D008077:Lipoproteins, LDL / Q000032:analysis* / Q000494:pharmacology; D008297:Male; D008875:Middle Aged; D010003:Osteoarthritis / Q000378:metabolism; D012333:RNA, Messenger / Q000032:analysis; D020133:Reverse Transcriptase Polymerase Chain Reaction; D051127:Scavenger Receptors, Class E / Q000032:analysis* / Q000235:genetics / Q000502:physiology; D013582:Synovial Fluid / Q000737:chemistry
D008077:Lipoproteins, LDL; C495137:OLR1 protein, human; D012333:RNA, Messenger; D051127:Scavenger Receptors, Class E; C099252:oxidized low density lipoprotein; D001205:Ascorbic Acid