Alendronate protects against articular cartilage erosion by inhibiting subchondral bone loss in ovariectomized rats

State Key Laboratory of Oral Diseases and Center of Orthognathic and temporomandibular Joint Surgery, West China College of Stomatology, Sichuan University, Chengdu, 610041, China.
Bone (Impact Factor: 3.97). 01/2013; 53(2). DOI: 10.1016/j.bone.2012.12.044
Source: PubMed


Osteoporosis (OP) and osteoarthritis (OA) are major health problems in the increasing elderly population, particularly in postmenopausal women, but their relationship remains unclear. The present study investigated whether alendronate (ALN), a potent inhibitor of bone resorption, could protect articular cartilage from degeneration in a combined animal model of OP and OA induced by ovariectomy (OVX). Seventy-eight seven-month-old female Sprague-Dawley rats were assigned into five experimental groups: (1) sham-operated with vehicle treatment, (2) sham-operated with ALN treatment, (3) OVX with vehicle treatment, (4) ALN treatment starting at OVX, and (5) ALN treatment starting at eight weeks after OVX. Histological and micro-CT analyses, together with urine collagen degradation markers, indicated that early ALN treatment completely prevented both subchondral bone loss and cartilage surface erosion induced by OVX. Although late ALN treatment also inhibited subchondral bone loss and significantly reduced cartilage erosion in the OVX rats, these tissues did not completely recover even after 10-weeks of ALN treatment. Quantitative RT-PCR analyses showed that the protective effect of ALN correlated with increased ratio of OPG/RANKL in both subchondral bone and cartilage. Moreover, whereas OVX caused upregulation of expression of matrix metalloproteinases MMP-13 and MMP-9 in the articular cartilage and chondrocytes in the interface between the articular cartilage and subchondral bone, respectively, early ALN treatment blocked whereas late ALN treatment attenuated the upregulation of these catabolic enzymes in the corresponding tissues. Together, these data indicate that the subchondral bone loss plays an important role in OA pathogenesis in the combined OP and OA model and suggest that treatment timing is an important factor for the effectiveness of anti-resorptive drugs therapy of combined OP and OA.

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    • "In preclinical models, the inhibition of NF-κB or active proteinases has been shown to slow joint degeneration[11,12]. Proteinases include but are not limited to matrix metalloproteinases (MMPs), particularly MMP-13[14,15], and aggrecanases, such as a disintegrin and metalloproteinase with thrombospondin motifs 4 and 5 (ADAMTS4 and ADAMTS5, respectively)[12,16]. Subchondral bone changes associated with OA are driven largely by the nonclassical NF-κB-related receptor activator of nuclear factor κB ligand (RANKL) pathway[17,18], activation of which may lead to both inflamma- tion[10]and pain[19]. RANKL, a member of the tumor necrosis factor (TNF) superfamily, is produced by synovial tissue and binds to the receptor activator of NF-κB found on immune cells and osteoclasts[20]. "
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