To assess the influence of intra-articular injection of hyaluronan (HA) on expression of matrix metalloproteinase-3 (MMP-3), interleukin-1beta(IL-1beta), and tissue inhibitor of metalloproteinase-1 (TIMP-1) in cartilage and synovium during the process of osteoarthritis (OA).
Eighteen mature New Zealand white rabbits underwent unilateral anterior cruciate ligament transection (ACLT) and were divided into two groups. The first group (HA injection group) received 0.3 ml of intra-articular HA injections into the ACLT knees 4 weeks after transection, once a week for 5 weeks as per clinical treatment presently utilized. The animals in the second group (no injection group) were not injected after ACLT. At death, 9 weeks following surgery, synovium and cartilage were harvested and total RNA was extracted. Gene expressions of MMP-3, IL-1beta and TIMP-1 were analyzed using reverse transcription-polymerase chain reaction (RT-PCR) for each subgroup created according to morphological grade of OA.
The extent and grade of cartilage damage in the HA injection group was less severe than in the no injection group. In synovium, expression of MMP-3 and IL-1beta mRNA was suppressed in the mild grades of OA in the HA injection group. HA treatment had either no effect on MMP-3 expression in cartilage at all grades of OA or on enhanced MMP-3 and IL-1beta expression in synovium at a progressed grade. No effect of HA treatment on TIMP-1 expression was observed in either cartilage or synovium.
These results suggest that one of the mechanism of therapeutic effect of HA is down-regulation of MMP-3 and IL-1beta in synovium during early development of OA.