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TNF Accelerates Death of Mandibular Condyle Chondrocytes in Rats with Biomechanical Stimulation-Induced Temporomandibular Joint Disease.

Yang H, Zhang M, Wang X, Zhang H, Zhang J, Jing L, Liao L, Wang M - PLoS ONE (2015)

Bottom Line: TNF stimulated apoptosis of the isolated chondrocytes and up-regulated caspase-8 expression, but did not change caspase-9 expression levels.Local injection of TNF inhibitor down-regulated caspase-8 expression and reduced TUNEL-positive cell number, but did not reverse cartilage thickness reduction, caspase-9 up-regulation or cytochrome c release.However, anti-TNF therapy does not prevent cartilage loss in this model of temporomandibular joint.

View Article: PubMed Central - PubMed

Affiliation: State Key Laboratory of Military Stomatology, Department of Oral Anatomy and Physiology and TMD, School of Stomatology, the Fourth Military Medical University, 145 Changle West Road, Xi'an, China.

ABSTRACT

Objective: To determine if temporomandibular joint chondrocyte apoptosis is induced in rats with dental biomechanical stimulation and what a role TNF takes.

Methods: Thirty-two rats were divided into 4 groups (n = 8/group) and exposed to incisor mal-occlusion induced by unilateral anterior crossbite biomechanical stimulation. Two groups were sampled at 2 or 4 weeks. The other two groups were treated with local injections of a TNF inhibitor or PBS into the temporomandibular joints area at 2 weeks and then sampled at 4 weeks. Twenty-four rats either served as unilateral anterior crossbite mock operation controls (n = 8/group) with sampling at 2 or 4 weeks or received a local injection of the TNF inhibitor at 2 weeks with sampling at 4 weeks. Chondrocytes were isolated from the temporomandibular joints of 6 additional rats and treated with TNF in vitro. Joint samples were assessed using Hematoxylin&eosin, Safranin O, TUNEL and immunohistochemistry staining, real-time PCR, fluorogenic activity assays and Western blot analyses. The isolated chondrocytes were also analyzed by flow cytometry.

Results: Unilateral anterior crossbite stimulation led to temporomandibular joint cartilage degradation, associated with an increase in TUNEL-positive chondrocytes number, caspase-9 expression levels, and the release of cytochrome c from mitochondria at 2 weeks without changes in TNF and caspase-8 levels until after 4 weeks. TNF stimulated apoptosis of the isolated chondrocytes and up-regulated caspase-8 expression, but did not change caspase-9 expression levels. Local injection of TNF inhibitor down-regulated caspase-8 expression and reduced TUNEL-positive cell number, but did not reverse cartilage thickness reduction, caspase-9 up-regulation or cytochrome c release.

Conclusions: Unilateral anterior crossbite stimulation induces mitochondrion-mediated apoptosis of articular chondrocytes. TNF accelerated the unilateral anterior crossbite induced chondrocytes apoptosis via death-receptor pathway. However, anti-TNF therapy does not prevent cartilage loss in this model of temporomandibular joint.

No MeSH data available.


Related in: MedlinePlus

The mRNA and protein levels of apoptotic pathway components in vivo.A comparison of the apoptotic activity in the mandibular condylar cartilage between the 2-week Control (2w Control), 2-week UAC (2w UAC), 4-week Control (4w Control), 4-week UAC (4w UAC), UAC+Inhibitor (UAC+Inhib), Control+Inhibitor (Control+Inhib) and UAC+PBS (UAC+PBS) groups. The mRNA expression levels of caspase-8 (a) and caspase-9 (b). The activities of caspase-8 (c) and caspase-9 (d) units. Western blot for the release of cytochrome c from the mitochondria into the cytoplasm (e) and its quantification (f). The data are expressed as the means and 95% CIs. n = 3.
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pone.0141774.g006: The mRNA and protein levels of apoptotic pathway components in vivo.A comparison of the apoptotic activity in the mandibular condylar cartilage between the 2-week Control (2w Control), 2-week UAC (2w UAC), 4-week Control (4w Control), 4-week UAC (4w UAC), UAC+Inhibitor (UAC+Inhib), Control+Inhibitor (Control+Inhib) and UAC+PBS (UAC+PBS) groups. The mRNA expression levels of caspase-8 (a) and caspase-9 (b). The activities of caspase-8 (c) and caspase-9 (d) units. Western blot for the release of cytochrome c from the mitochondria into the cytoplasm (e) and its quantification (f). The data are expressed as the means and 95% CIs. n = 3.

Mentions: In the TMJ cartilage of the control group, there were only a few scattered TUNEL-positive chondrocytes. However, in both the 2-week UAC and 4-week UAC groups, the numbers of TUNEL-positive cells were increased (p = 0.02 and p = 0.008, respectively). The TUNEL-positive cells were located mainly in the proliferative and hypertrophic layers of the condylar cartilage (Fig 5). The mRNA expression of caspase-9 was up-regulated at 2 weeks (p = 0.002 for the 2-week group; p = 0.014 for the 4-week group) (Fig 6b). However, the mRNA expression level of caspase-8 was not up-regulated until 4 weeks (p = 0.002) (Fig 6a). Furthermore, fluorogenic analysis revealed that the level of active caspase-9 units was increased at both 2 and 4 weeks (both p = 0.003) (Fig 6c and 6d), whereas the level of active caspase-8 units was not increased until 4 weeks (2-week group: p = 0.384, 4-week group: p = 0.002). The level of cytochrome c release from the mitochondria into the cytosol was also increased at both 2 and 4 weeks (p = 0.042 and p = 0.002, respectively) (Fig 6e and 6f).


TNF Accelerates Death of Mandibular Condyle Chondrocytes in Rats with Biomechanical Stimulation-Induced Temporomandibular Joint Disease.

Yang H, Zhang M, Wang X, Zhang H, Zhang J, Jing L, Liao L, Wang M - PLoS ONE (2015)

The mRNA and protein levels of apoptotic pathway components in vivo.A comparison of the apoptotic activity in the mandibular condylar cartilage between the 2-week Control (2w Control), 2-week UAC (2w UAC), 4-week Control (4w Control), 4-week UAC (4w UAC), UAC+Inhibitor (UAC+Inhib), Control+Inhibitor (Control+Inhib) and UAC+PBS (UAC+PBS) groups. The mRNA expression levels of caspase-8 (a) and caspase-9 (b). The activities of caspase-8 (c) and caspase-9 (d) units. Western blot for the release of cytochrome c from the mitochondria into the cytoplasm (e) and its quantification (f). The data are expressed as the means and 95% CIs. n = 3.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4631347&req=5

pone.0141774.g006: The mRNA and protein levels of apoptotic pathway components in vivo.A comparison of the apoptotic activity in the mandibular condylar cartilage between the 2-week Control (2w Control), 2-week UAC (2w UAC), 4-week Control (4w Control), 4-week UAC (4w UAC), UAC+Inhibitor (UAC+Inhib), Control+Inhibitor (Control+Inhib) and UAC+PBS (UAC+PBS) groups. The mRNA expression levels of caspase-8 (a) and caspase-9 (b). The activities of caspase-8 (c) and caspase-9 (d) units. Western blot for the release of cytochrome c from the mitochondria into the cytoplasm (e) and its quantification (f). The data are expressed as the means and 95% CIs. n = 3.
Mentions: In the TMJ cartilage of the control group, there were only a few scattered TUNEL-positive chondrocytes. However, in both the 2-week UAC and 4-week UAC groups, the numbers of TUNEL-positive cells were increased (p = 0.02 and p = 0.008, respectively). The TUNEL-positive cells were located mainly in the proliferative and hypertrophic layers of the condylar cartilage (Fig 5). The mRNA expression of caspase-9 was up-regulated at 2 weeks (p = 0.002 for the 2-week group; p = 0.014 for the 4-week group) (Fig 6b). However, the mRNA expression level of caspase-8 was not up-regulated until 4 weeks (p = 0.002) (Fig 6a). Furthermore, fluorogenic analysis revealed that the level of active caspase-9 units was increased at both 2 and 4 weeks (both p = 0.003) (Fig 6c and 6d), whereas the level of active caspase-8 units was not increased until 4 weeks (2-week group: p = 0.384, 4-week group: p = 0.002). The level of cytochrome c release from the mitochondria into the cytosol was also increased at both 2 and 4 weeks (p = 0.042 and p = 0.002, respectively) (Fig 6e and 6f).

Bottom Line: TNF stimulated apoptosis of the isolated chondrocytes and up-regulated caspase-8 expression, but did not change caspase-9 expression levels.Local injection of TNF inhibitor down-regulated caspase-8 expression and reduced TUNEL-positive cell number, but did not reverse cartilage thickness reduction, caspase-9 up-regulation or cytochrome c release.However, anti-TNF therapy does not prevent cartilage loss in this model of temporomandibular joint.

View Article: PubMed Central - PubMed

Affiliation: State Key Laboratory of Military Stomatology, Department of Oral Anatomy and Physiology and TMD, School of Stomatology, the Fourth Military Medical University, 145 Changle West Road, Xi'an, China.

ABSTRACT

Objective: To determine if temporomandibular joint chondrocyte apoptosis is induced in rats with dental biomechanical stimulation and what a role TNF takes.

Methods: Thirty-two rats were divided into 4 groups (n = 8/group) and exposed to incisor mal-occlusion induced by unilateral anterior crossbite biomechanical stimulation. Two groups were sampled at 2 or 4 weeks. The other two groups were treated with local injections of a TNF inhibitor or PBS into the temporomandibular joints area at 2 weeks and then sampled at 4 weeks. Twenty-four rats either served as unilateral anterior crossbite mock operation controls (n = 8/group) with sampling at 2 or 4 weeks or received a local injection of the TNF inhibitor at 2 weeks with sampling at 4 weeks. Chondrocytes were isolated from the temporomandibular joints of 6 additional rats and treated with TNF in vitro. Joint samples were assessed using Hematoxylin&eosin, Safranin O, TUNEL and immunohistochemistry staining, real-time PCR, fluorogenic activity assays and Western blot analyses. The isolated chondrocytes were also analyzed by flow cytometry.

Results: Unilateral anterior crossbite stimulation led to temporomandibular joint cartilage degradation, associated with an increase in TUNEL-positive chondrocytes number, caspase-9 expression levels, and the release of cytochrome c from mitochondria at 2 weeks without changes in TNF and caspase-8 levels until after 4 weeks. TNF stimulated apoptosis of the isolated chondrocytes and up-regulated caspase-8 expression, but did not change caspase-9 expression levels. Local injection of TNF inhibitor down-regulated caspase-8 expression and reduced TUNEL-positive cell number, but did not reverse cartilage thickness reduction, caspase-9 up-regulation or cytochrome c release.

Conclusions: Unilateral anterior crossbite stimulation induces mitochondrion-mediated apoptosis of articular chondrocytes. TNF accelerated the unilateral anterior crossbite induced chondrocytes apoptosis via death-receptor pathway. However, anti-TNF therapy does not prevent cartilage loss in this model of temporomandibular joint.

No MeSH data available.


Related in: MedlinePlus