Aberrant activation of latent transforming growth factor-β initiates the onset of temporomandibular joint osteoarthritis

There is currently no effective medical treatment for temporomandibular joint osteoarthritis(TMJ-OA) due to a limited understanding of its pathogenesis. This study was undertaken to investigate the key role of transforming growth factor-β(TGF-β)signalling in the cartilage and subchondral bone of the TMJ using a temporomandibular joint disorder(TMD) rat model, an ageing mouse model and a Camurati–Engelmann disease(CED) mouse model. In the three animal models, the subchondral bone phenotypes in the mandibular condyles were evaluated by μCT, and changes in TMJ condyles were examined by TRAP staining and immunohistochemical analysis of Osterix and p-Smad2/3. Condyle degradation was confirmed by Safranin O staining, the Mankin and OARSI scoring systems and type X collagen(Col X), p-Smad2/3 a and Osterix immunohistochemical analyses. We found apparent histological phenotypes of TMJ-OA in the TMD, ageing and CED animal models, with abnormal activation of TGF-βsignalling in the condylar cartilage and subchondral bone. Moreover, inhibition of TGF-β receptor I attenuated TMJ-OA progression in the TMD models. Therefore, aberrant activation of TGF-β signalling could be a key player in TMJ-OA development.

Treatment of condylar osteophyte in temporomandibular joint osteoarthritis with muscle balance occlusal splint and long-term follow-up:A case report

BACKGROUND Condylar osteophytes,a remodeling form of temporomandibular joint osteoarthritis(TMJ OA),mainly manifest as marginal angular outgrowths of the condyle.Previous researchers have advocated surgical removal of condylar osteophytes.Reports on the effect of occlusal splint on TMJ OA patients’joints have mostly focused on treatment with this splint,which can reduce the absorption of the affected condyle and promote repair and regeneration.However,the effect of the splint on the dissolution of condylar osteophytes has not yet been reported.CASE SUMMARY A 68-year-old female patient suffered from occlusal discomfort with left facial pain for 2 years.Cone beam computed tomography showed a rare osteophyte on top of her left condyle.She was finally diagnosed with TMJ OA.The patient refused surgical treatment and received conservative treatment with a muscle balance occlusal splint.The pain experienced by the patient on the left side of her face was relieved,and her chewing ability recovered after treatment.The osteophyte dissolved,and the condylar cortex remained stable during long-term follow-up observations.CONCLUSION The muscle balance occlusal splint could be a noninvasive means of treating condylar osteophytes in TMJ OA patients.

Poly(p-coumaric acid)nanoparticles alleviate temporomandibular joint osteoarthritis by inhibiting chondrocyte ferroptosis

Oxidative stress and inflammation are key drivers of osteoarthritis(OA)pathogenesis and disease progression.Herein we report the synthesis of poly(p-coumaric)nanoparticles(PCA NPs)from p-courmaic acid(p-CA),a naturally occurring phytophenolic acid,to be a multifunctional and drug-free therapeutic for temporomandibular joint osteoarthritis(TMJOA).Compared to hyaluronic acid(HA)that is clinically given as viscosupplementation,PCA NPs exhibited long-term efficacy,superior anti-oxidant and anti-inflammatory properties in alleviating TMJOA and repairing the TMJ cartilage and subchondral bone in a rat model of TMJOA.Notably,TMJ repair mediated by PCA NPs could be attributed to their anti-oxidant and anti-inflammatory properties in enhancing cell proliferation and matrix synthesis,while reducing inflammation,oxidative stress,matrix degradation,and chondrocyte ferroptosis.Overall,our study demonstrates a multifunctional nanoparticle,synthesized from natural p-coumaric acid,that is stable and possess potent antioxidant,anti-inflammatory properties and ferroptosis inhibition,beneficial for treatment of TMJOA.