Site specific changes in gene expression and cartilage metabolism during early experimental osteoarthritis.
OBJECTIVE
To characterize the molecular events underlying cartilage injury in the early phase of mono-iodoacetate-induced osteoarthritis (OA) in rats.


METHODS
Experimental osteoarthritis was induced by intra-articular injection of 0.03mg mono-iodoacetate (MIA) in Wistar rats. Animals were killed 2, 5, 10, 15 and 20 days post-injection. Synovial tissue and standardized biopsies from different areas of knee cartilage were examined. Proteoglycan synthesis ((35)S incorporation) and gelatinase activities (zymography), semi-quantitative RT-PCR and immunohistochemistry for IL1beta, iNOS, COX2 and PPARgamma, were performed on these samples.


RESULTS
Changes in proteoglycan synthesis and gelatinase activities were time and site-dependent. Proteoglycan synthesis inhibition was maximal by day 2 while the highest gelatinase activities were observed at day 5. Central part of patella and posterior plateaus and condyles, i.e. the weight-bearing cartilage areas, were the most affected. IL1beta and iNOS transcripts were induced early in cartilage at time of maximal proteoglycan synthesis inhibition, especially in weight-bearing areas. COX-2 was slightly up-regulated whereas PPARgamma gene expression remained unchanged. Gene expression profile in synovium paralleled that of cartilage, except for PPARgamma which was up-regulated at day 15 and 20. Immunostaining for IL1beta and iNOS showed that proteins were located in diseased cartilage areas at early stage of the experimental OA (day 2). At later time-points (day 20), IL1beta and iNOS were expressed in perilesional areas whereas immunostaining became below control level for COX-2 and PPARgamma.


CONCLUSIONS
Time-dependent degradation of cartilage after injection of low dose of MIA (0.03mg) into rat knee joint can be related to early loss of proteoglycan anabolism, increased gelatinase activities and expression of IL1beta and downstream inflammatory genes. Increased susceptibility to MIA in weight-bearing areas of cartilage further indicate that MIA-induced experimental OA is a relevant model to study not only metabolical but also biomechanical aspects of human OA.
Dumond
H
H
Laboratoire de Pharmacologie et Physiopathologie articulaires, UMR CNRS-UHP 7561, Faculté de Médecine, Avenue de la Forêt de Haye, BP 184, 54505 Vandoeuvre-lès-Nancy, France.
Presle
N
N
Pottie
P
P
Pacquelet
S
S
Terlain
B
B
Netter
P
P
Gepstein
A
A
Livne
E
E
Jouzeau
J-Y
JY
D000818:Animals; D002358:Cartilage, Articular / Q000378:metabolism*; D051546:Cyclooxygenase 2; D004791:Enzyme Inhibitors; D018093:Gelatinases / Q000378:metabolism; D015870:Gene Expression / Q000235:genetics*; D007150:Immunohistochemistry / Q000379:methods; D007375:Interleukin-1 / Q000032:analysis; D019807:Iodoacetic Acid; D007527:Isoenzymes / Q000032:analysis; D008297:Male; D019001:Nitric Oxide Synthase / Q000032:analysis; D052247:Nitric Oxide Synthase Type II; D010003:Osteoarthritis / Q000235:genetics* / Q000378:metabolism; D011451:Prostaglandin-Endoperoxide Synthases / Q000032:analysis; D011509:Proteoglycans / Q000096:biosynthesis; D012333:RNA, Messenger / Q000032:analysis; D051381:Rats; D017208:Rats, Wistar; D018160:Receptors, Cytoplasmic and Nuclear / Q000032:analysis; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods; D013997:Time Factors; D014157:Transcription Factors / Q000032:analysis
D004791:Enzyme Inhibitors; D007375:Interleukin-1; D007527:Isoenzymes; D011509:Proteoglycans; D012333:RNA, Messenger; D018160:Receptors, Cytoplasmic and Nuclear; D014157:Transcription Factors; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II; C496318:Nos2 protein, rat; D051546:Cyclooxygenase 2; D011451:Prostaglandin-Endoperoxide Synthases; D018093:Gelatinases; D019807:Iodoacetic Acid