Inhibition of caspase-9 reduces chondrocyte apoptosis and proteoglycan loss following mechanical trauma

Huser, Camille; Peacock, M.; Davies, Malcolm

doi:10.1016/j.joca.2006.03.012

Cited by 41 publications

(39 citation statements)

References 63 publications

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“…The latter finding was also confirmed in a study by Heyde et al who analyzed intradiscal changes in spine trauma patients undergoing discectomy and instrumented fusion [21]. Apart from in disc research, the involvement of the caspase pathway and a potential beneficial effect of therapeutic caspase inhibition was demonstrated in the area of joint cartilage injury studies [11,14,25].…”

Section: Discussionmentioning

confidence: 56%

Vertebral endplate trauma induces disc cell apoptosis and promotes organ degeneration in vitro

et al. 2007

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There is a major controversy whether spinal trauma with vertebral endplate fractures can result in posttraumatic disc degeneration. Intervertebral discs, which are adjacent to burst endplates, are frequently removed and an intercorporal spondylodesis is performed. In any case, the biological effects within the discs following endplate factures are poorly elucidated to date. The aim of our investigations was therefore to establish a novel disc/endplate trauma culture model to reproducibly induce endplate fractures and investigate concurrent disc changes in vitro. This model is based on a full-organ disc/endplate culture system, which has been validated by the authors before. Intervertebral disc/endplate specimens were isolated from Burgundy rabbits and cultured in standard media (DMEM/ F12, 10%FCS). Burst endplate fractures were induced in half of the specimens with a custom-made fracture device and subsequently cultured for 9 days. The biological effects such as necrotic or apoptotic cell death and the expression of pro-apoptotic genes and other genes involved in organ degeneration, e.g. matrix metalloproteinases (MMPs) were analyzed. Cell damage was assessed by quantification of the lactate dehydrogenase (LDH) activity in the supernatant. The expression of genes involved in the cellular apoptotic pathway (caspase 3) and the pro-apoptotic proteins FasL and TNF-a were monitored. The results demonstrate that LDH levels increased significantly post trauma compared to the control and remained elevated for 3 days. Furthermore, a constant up-regulation of the caspase 3 gene in both disc compartments was present. The pro-apoptotic proteins FasL and TNF-a were up regulated predominantly in the nucleus whereas the MMP-1 and -13 transcripts (collagenases) were increased in both disc structures. From this study we can conclude that endplate burst fractures result in both necrotic and apoptotic cell death in nucleus and annulus tissue. Moreover, FasL and TNF-a expression by nucleus cells may lead to continued apoptosis induced by Fas-and TNF-a receptor bearing cells. In addition TNF-a over-expression has potentially deleterious effects on disc metabolism such as overexpression of matrix proteinases. Taken together, the short term biological response of the disc following endplate fracture exhibits characteristics, which may initiate the degeneration of the organ.

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Section: Discussionmentioning

confidence: 56%

Vertebral endplate trauma induces disc cell apoptosis and promotes organ degeneration in vitro

et al. 2007

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“…The involvement of caspases 3 and 9 in chondrocyte apoptosis (6,34) and the role of chondrocyte apoptosis in the development of OA (34,35) have been previously documented. The results presented herein indicate a role of mitochondrial dysfunction in impactinduced chondrocyte death in cartilage explants.…”

Section: Discussionmentioning

confidence: 94%

“…Cartilage explants were placed with the articular surface facing downward, and a single impact was applied with a 500-gm weight dropped from a height of 50 mm (0.245J) using a drop-tower device as previously described (6,30). This impact protocol gives rise to secondary OA-like cartilage damage and induces an OA-like phenotype, including death of a proportion of chondrocytes in the superficial zone of the cartilage (6,30). Some explants were not subjected to impact, and these served as controls.…”

Section: Methodsmentioning

confidence: 99%

“…DMMB assay. The DMMB dye binding assay was used to quantify the amount of glycosaminoglycan (GAG), a component of proteoglycans, released from the cartilage explants into the culture medium, as previously described (6). Shark chondroitin sulfate C standards (Sigma-Aldrich) were prepared at concentrations ranging from 0 to 150 g/ml.…”

Section: Methodsmentioning

confidence: 99%

“…Caspase-dependent apoptosis has been identified as a major event in the initiation of traumatic OA, although the mechanistic connection between mechanical trauma and cell death remains unknown (4)(5)(6). A link has been established between calcium overload, ER stress, apoptosis deregulation, and disease development in many degenerative diseases, such as brain ischemia, Figure 1.…”

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confidence: 99%

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Calcium signaling leads to mitochondrial depolarization in impact‐induced chondrocyte death in equine articular cartilage explants

Huser¹,

Davies²

2007

Arthritis & Rheumatism

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Objective. Chondrocyte apoptosis is an important factor in the progression of osteoarthritis. This study aimed to elucidate the mechanisms involved upstream of caspase 9 activation and, in particular, calcium signaling and mitochondrial depolarization.Methods. Articular cartilage explants obtained from healthy horses were subjected to a single impact load (500-gm weight dropped from a height of 50 mm) and cultured in vitro for up to 48 hours. Chondrocyte death was quantified by the TUNEL method. Release of proteoglycans was determined by the dimethylmethylene blue assay. Weight change was measured, and mitochondrial depolarization was determined using JC-1 staining. To assess the role of calcium signaling in impact-induced chondrocyte death, explants were preincubated in culture medium containing various concentrations of calcium. Inhibitors were used to assess the role of individual signaling components in impactinduced chondrocyte death.Results. Calcium quenching, inhibitors of calpains, calcium/calmodulin-regulated kinase II (CaMKII), and mitochondrial depolarization reduced impact-induced chondrocyte death after 48 hours in culture. Transient mitochondrial depolarization was observed 3-6 hours following a single impact load. Mitochondrial depolarization was prevented by calcium quenching, inhibitors of calpain, CaMKII, permeability transition pore formation, ryanodine receptor, and the mitochondrial uniport transporter. Cathepsin B did not appear to be involved in impact-induced chondrocyte death. The calpain inhibitor prevented proteoglycan loss, but the percentage weight gain and proteoglycan loss were unaffected by all treatments used.Conclusion. Following a single impact load, calcium is released from the endoplasmic reticulum via the ryanodine receptor and is taken up by the mitochondria via the uniport transporter, causing mitochondrial depolarization and caspase 9 activation. In addition, calpains and CaMKII play important roles in causing mitochondrial depolarization.

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Cyclic loading increases friction and changes cartilage surface integrity in lubricin‐mutant mouse knees

Drewniak

Jay

Fleming

et al. 2012

Arthritis & Rheumatism

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Objective To investigate the effects of lubricin gene dosage and cyclic loading on whole joint coefficient of friction (CoF) and articular cartilage surface integrity in mouse knee joints. Methods Joints from mice with two (Prg4+/+), one (Prg4+/−), and no (Prg4−/−) functioning lubricin alleles were subjected to 26 hours of cyclic loading using a custom-built pendulum. CoF values were measured at multiple time points. Contra-lateral control joints were kept unloaded. Following testing, joints were examined for histological evidence of damage and cell viability. Results At baseline, Prg4−/− CoF values were significantly higher than Prg4+/+ and Prg4+/− values (p<0.001). Cyclic loading continuously increased CoF in Prg4−/− joints. In contrast, Prg4+/− and Prg4+/+ joints had no CoF increases during the first 4 hours of loading. After 26 hours of loading, joints from all genotypes had increased CoF values compared to baseline and unloaded controls. Significantly greater increases occurred in Prg4−/− and Prg4+/− joints compared to Prg4+/+ joints. CoF values were not significantly associated with histological evidence of damage or loss of cell viability. Conclusion Mice lacking lubricin have increased baseline CoF values and are not protected from further increases caused by loading. Prg4+/− mice are indistinguishable from Prg4+/+ mice at baseline, but have significantly greater CoF values following 26 hours of loading. Lubricin dosage affects joint properties during loading, and may have clinical implications in patients for whom injury or illness alters lubricin abundance.

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Inhibition of caspase-9 reduces chondrocyte apoptosis and proteoglycan loss following mechanical trauma

Abstract: These results suggest that impact trauma-induced chondrocyte death is predominantly due to caspase-9-dependent apoptosis and is linked to cartilage degeneration.

Cited by 41 publications

References 63 publications

Vertebral endplate trauma induces disc cell apoptosis and promotes organ degeneration in vitro

Vertebral endplate trauma induces disc cell apoptosis and promotes organ degeneration in vitro

Calcium signaling leads to mitochondrial depolarization in impact‐induced chondrocyte death in equine articular cartilage explants

Cyclic loading increases friction and changes cartilage surface integrity in lubricin‐mutant mouse knees

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