Effects of a metalloproteinase inhibitor on osteochondral angiogenesis, chondropathy and pain behavior in a rat model of osteoarthritis.
OBJECTIVE
To investigate the effects of a matrix metalloproteinase (MMP) inhibitor on joint pathology and pain behavior in the rat meniscal transection (MNX) model of osteoarthritis (OA) and evaluate which aspects of structural disease modification contribute to symptom improvement.


METHODS
OA pathology was induced in male Lewis rats, by transecting the medial collateral ligament with (MNX) or without (SHAM) a full thickness cut through the meniscus. MNX animals were orally administered an equipotent MMP 2, 8, 9, 12, 13 inhibitor (0.25, 1 and 5 mg/kg/day) or vehicle from day 1. Chondropathy, osteophytosis, osteochondral vascularity were assessed from toluidine blue stained coronal sections of the total knee joint and weight-bearing asymmetry by incapacitance. Group differences were evaluated using 1-way analysis of variance (ANOVA) and associations as Spearman's correlation coefficients.


RESULTS
Treatment with the MMP inhibitor reduced weight-bearing asymmetry from day 14 onwards, and attenuated chondropathy (both P<0.05). Osteochondral vascularity was elevated in MNX compared with SHAM-operated animals (P<0.001) and reduced, dose-dependently, by MMP inhibitor treatment (r=-0.89, P<0.05). Reduced osteochondral vascularity and chondropathy were associated with the amelioration of weight-bearing asymmetry (both P<0.05).


CONCLUSIONS
Here we show that treatment with a MMP inhibitor reduces joint damage, osteochondral angiogenesis and behavioral evidence of pain. The association between osteochondral angiogenesis and pain behavior may be explained by perivascular nerve growth or stimulation of subchondral nerves following loss of osteochondral integrity. Our data suggest that targeting angiogenesis may have utility in the treatment of pain associated with structural damage in OA.
Mapp
P I
PI
Academic Rheumatology, University of Nottingham, Clinical Sciences Building, City Hospital, Nottingham NG5 1PB, UK. Paul.Mapp@Nottingham.ac.uk
Walsh
D A
DA
Bowyer
J
J
Maciewicz
R A
RA
D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects; D002358:Cartilage, Articular / Q000473:pathology*; D004195:Disease Models, Animal; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D007719:Knee Joint / Q000187:drug effects* / Q000473:pathology; D008297:Male; D061965:Matrix Metalloproteinase Inhibitors; D008592:Menisci, Tibial / Q000601:surgery; D009389:Neovascularization, Pathologic / Q000473:pathology*; D010003:Osteoarthritis / Q000188:drug therapy* / Q000503:physiopathology; D010146:Pain / Q000503:physiopathology*; D051381:Rats; D011917:Rats, Inbred Lew; D016474:Weight-Bearing / Q000502:physiology
D004791:Enzyme Inhibitors; D061965:Matrix Metalloproteinase Inhibitors