Histological and Molecular Assessment of Anti-inflammatory Effect of Different Concentrations of Hyaluronic Acid Injected in Inflamed Rabbit’s Tempromandibular Joint

Introduction: Several studies indicated that Hyaluronic acid (HA) has anti-inflammatory role through suppressing mediators of inflammation involved in the osteoarthritic disease state. Aim: Investigating the anti-inflammatory effect of different concentrations of hyaluronic acid on experimentally induced inflammatory changes in rabbits temporomandibular joint (TMJ). Material and Methods: Forty male rabbits were prepared and randomly divided into 5 groups each group formed of 8 rabbits as follow: Group (1): 8 animals injected with saline only served a negative control group. Group (2): 8 animals injected with formalin served as positive control. Group (3): 8 animals injected with 0.1ml of formalin once, followed by 2.5mg/0.5ml /week of HA for three weeks. Group (4): formed of 8 animals injected with 0.1ml of formalin once, followed by 5mg/0.5ml /week of HA for three weeks. Group (5): 8 animals injected with 0.1ml of formalin once, followed by 7.5mg/0.5ml /week of HA for three weeks. Eventually blood samples were collected and animals were euthanized. Evaluation in this study included measuring pro inflammatory markers IL-6, IL-1β and CRP by ELISA. Histological evaluation of TMJ tissues to detect changes in the muscles, ligaments, and bones. Results: all animals injected with HA showed a significant reduction in levels of IL-6, IL-1β and CRP in addition to improvement in tissue structure. Animals in G4 and G5 showed significantly better results than G3. Conclusion : there is a statistically significant anti-inflammatory effect of HA on TMJ at different concentrations.