Characterization of pro-apoptotic and matrix-degradative gene expression following induction of osteoarthritis in mature and aged rabbits.
ABSTRACT The genetic and molecular changes leading to the distinctive alterations of aged cartilage and its propensity for developing osteoarthritis (OA) are unknown. We hypothesized that pro-apoptotic and matrix-degradative gene expression in a rabbit model of induced OA using mature and aged animals might elucidate this relationship.
Groups of six mature and aged rabbits underwent anterior cruciate ligament transection (ACLT) and were sacrificed 4 weeks after surgery to create an Outerbridge grade II OA. RNA was extracted from the articular cartilage and menisci of the affected knee and was examined with regard to expression of the following genes: Caspase 8, Fas, Fas ligand (Fas-L), p53, aggrecanase, matrix metalloproteinase (MMP)-1, and MMP-3-MMP-13. A second cohort of mature and aged animals was sacrificed with no intervention to the joint and gene expression was assessed in a similar manner.
Fas and Caspase 8 showed significantly increased expression in the cartilage of mature animals with induced OA when compared to unoperated controls while induction of OA in aged rabbits did not significantly increase expression of any of the apoptosis genes. Among unoperated animals, the aged cohort showed significantly increased expression of MMP-1 and aggrecanase in cartilage when compared to mature animals. MMP-13 expression was upregulated in aged cartilage following induction of OA. Although ACLT animals showed gross thinning and irregularities within the meniscus, only the expression of Caspase 8 in the aged rabbits was significantly increased after induction of OA.
Aging of articular cartilage shares some qualities with the development of OA, as seen in the parallel increases in gene expression of Caspase 8 and Fas. Although this may imply a common mechanism of cartilage degeneration in aging and OA or even a spectrum of disease, both are complex processes requiring further study.
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ABSTRACT: The purpose of this study was to assess apoptosis, the expression of MMP-1, MMP-3 and TIMP-2, as well as the mechanical and biochemical properties of fresh rabbit medial meniscus after 2 weeks stored under tissue culture conditions. The study material included 26 rabbit's medial menisci. Fourteen menisci were stored for 2 weeks under tissue culture conditions. Thirteen menisci were subjected to immunohistochemistry tests. Apoptosis (TUNEL method) and the expression of MMP-1 (collagenase-1), MMP-3 (stromelysin-2) and TIMP-2 (tissue inhibitor of metalloproteinases-2) were estimated semiquantitatively. The remaining menisci were tested mechanically and biochemically. The mechanical properties were assessed by the degree of elasticity. Biochemical composition was based on the content analysis of water, total collagen and glycosaminoglycans. As in the control group, the conducted study did not reveal any apoptosis in the stored menisci. The study group showed a slight expression of MMP-1 (0.27 ±0.19), MMP-3 (0.30 ±0.20) and TIMP-2 (0.33 ±0.20) - no statistically significant difference from controls. The degree of elasticity was 28.51 ±1.53 in the study group, and this did not statistically differ from the control group. No significant biochemical differences were identified in any other monitored parameter. The conducted in vitro study did not show any negative influence of a 2-week storage period under tissue culture conditions on the apoptosis and expression of MMP-1, MMP-3 and TIMP-2 in rabbit fresh menisci, nor any impact on their mechanical and biochemical properties.Archives of Medical Science 02/2014; 10(1):167-73. DOI:10.5114/aoms.2014.40276 · 1.89 Impact Factor
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ABSTRACT: Objective. Autophagy is a potential protective mechanism that is involved in several degenerative diseases. Nitric oxide (NO) is associated with programmed cellular death in meniscal cells, but whether it can induce autophagy is still undetermined. This study aims to investigate the interaction between autophagy and NO in normal human meniscal cells.Methods. Normal meniscal cells were harvested from female patients. NO donors and NO synthase inhibitors were used to regulate the level of NO. Changes in the incidence of autophagy and apoptosis were examined using flow cytometry, western blot and immunofluorescence methods. The effects of NO-mediated autophagy regulation of the expression of MMPs and aggrecanases (ADAMTS-4 and -5) were analysed by real-time PCR.Results. NO donors inhibited autophagy as well as augmented apoptosis in human meniscal cells with serum deprivation. Conversely, treatment with NOS inhibitors resulted in up-regulation of the autophagy level while repressing apoptosis. NOS inhibitor treatment also resulted in down-regulation of MMPs and aggrecanase mRNA expression. This effect of NOS inhibitor was also blocked by autophagy inhibitors. Our results also showed that NOS inhibitor enhanced Jun-N-terminal kinase (JNK) activation. Furthermore, SP600125, a selective JNK inhibitor, blocked up-regulation of autophagy by NOS inhibitor.Conclusions. Our results demonstrated that NO augmented serum deprivation-induced apoptosis of meniscal cells via inhibition of autophagy through inactivation of JNK. Up-regulation of autophagy may be a potential approach in the treatment of meniscal tissue degeneration.Rheumatology (Oxford, England) 02/2014; 53(6). DOI:10.1093/rheumatology/ket471 · 4.44 Impact Factor