C-Reactive Protein Knock Out Attenuate Temporomandibular Joint Inflammation in Rats

Abstract

Background: C-reactive protein (CRP), a biomarker of inflammation, is highly expressed in osteoarthritis (OA)-related diseases, but its exact role remains unknown. In this study, we evaluated the biological effect of CRP on temporomandibular joint (TMJ) inflammation.Methods: Freund’s complete adjuvant (CFA) was used to induce TMJ inflammation in CRP-knockout (CRP-/-) and control rats. Degenerative changes in the TMJ were compared to elucidate the role of CRP in TMJ inflammation. In addition, inflammatory cytokines, macrophage activation and osteoclast differentiation were evaluated by real-time quantitative polymerase chain reaction, immunohistochemistry and tartrate-resistant phosphatase staining to explore the potential regulatory mechanism.Results: Compared to the control, CFA induced TMJ inflammation, which increased systemic and local CRP expression. Furthermore, CRP-/- rats exhibited less severe inflammatory symptoms. The downregulation of proinflammatory cytokines (interleukin (IL)-1β and IL-6) and upregulation of the anti-inflammatory cytokine IL-10 were detected in CRP-/- rats, which also exhibited reduced macrophage activation and osteoclast differentiation.Conclusion: These results indicated that controlling the highly elevated levels of CRP during inflammation could modify the cytokine profile, macrophage activation and osteoclast differentiation, thus providing beneficial effects for TMJ-OA prevention and treatment.

C-Reactive Protein Knockout Attenuates Temporomandibular Joint Inflammation in Rats

“…We thank Ms. Bei Zhang for help with the sample processing and PCR analysis, Dr. Jie Xu for help with the intra-articular injection and TMJ structure measurement training. A preprint has previously been published in research square by the same authors [ 42 ]. This work was supported by the National Natural Science Foundation of China (31800786 and 31971282), Special support for postdoctoral of Chongqing (XmT2018079), and municipal graduate tutor team construction project (dstd201903).…”