Effect of Toll-Like Receptor 4 on Synovial Injury of Temporomandibular Joint in Rats Caused by Occlusal Interference.

Jingjing Kong,Yingying Yang,Jianli Xie,Xuefen Lin,Ping Ji,Shuzhen Sun

doi:10.1155/2016/7694921

Jingjing Kong, Yingying Yang + Show 4 more

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https://doi.org/10.1155/2016/7694921

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Abstract

Synovitis is an important disease that causes intractable pain in TMJ. Some investigations suggested that the increasing expression of IL-1β secreted by synovial lining cells plays an important role in synovial inflammation and cartilage destruction in TMJ. In our previous research, the results demonstrated that TLR4 is involved in the expression of IL-1β in SFs from TMJ with lipopolysaccharide stimulation. However, the inflammatory response that occurred in synovial membrane is not caused by bacterial infection. In the current study, we investigated whether or not TLR4 participates in the inflammatory responses and the expression of IL-1β in synovial membrane of rats induced by occlusal interference. The results showed that obvious inflammation changes were observed in the synovial membranes and the expression of TLR4 and IL-1β was increased at both mRNA and protein levels in the occlusal interference rats. In addition, the inflammation reactions and the increased expression of IL-1β could be restrained by treatment with TAK-242, a blocker of TLR4 signaling. The results prompted us that the activation of TLR4 may be involved in the inflammatory reactions and increased expression of IL-1β in patients with synovitis and participate in the mechanisms of the initiation and development of synovial injury by regulating the expression of inflammatory mediators like IL-1β in synovial membranes.

Highlights

Temporomandibular disorder (TMD) is one of common and frequently occurring diseases in department of stomatology
IL-1β was reported to be expressed by synovial lining cells and endothelial cells of blood vessels [10], and it is suggested that the increasing expression of IL-1β plays an important role in synovial inflammation and cartilage destruction [11, 12]
In the occlusal interference group (Figure 1(b)), obvious inflammation changes were observed in the synovial membranes, such as apparent hyperplasia of synovial lining cells, dilated blood vessels, proliferation of blood vessels, and fibrin deposition

Summary

Introduction

Temporomandibular disorder (TMD) is one of common and frequently occurring diseases in department of stomatology. The patients can experience some symptoms that seriously affect human normal life and work, for example, pain in Temporomandibular Joint (TMJ) and masticatory muscle and limited mouth opening. The mechanisms of the initiation and development of this disease are complicated and not completely clear, and a lot of etiologic factors may be attributed to the onset of disorder, as biomedical and psychological as well as psychosocial impact factors and occlusal interferences [2,3,4]. Synovitis is an inflammation mainly occurs in synovial membrane and joint capsule of TMJ. A series of investigations [5, 6] on TMD has revealed the occurrence of inflammation in the synovial membrane. IL-1β was reported to be expressed by synovial lining cells and endothelial cells of blood vessels [10], and it is suggested that the increasing expression of IL-1β plays an important role in synovial inflammation and cartilage destruction [11, 12]

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