This thesis will be organized into three chapters discussing the mechanism underlying the onset and progression of osteoarthritis (OA) in the temporomandibular joint (TMJ). Understanding the mechanism of OA development in the TMJ helps in understanding how OA progresses and how to treat this disease. The goal of this investigation is to examine the process of cartilage degeneration and OA biomarker expression in the TMJ to understand their role in TMJ OA onset and development.Chapter one covers mechanisms that are altered in TMJ OA during disease progression. Using animal models with different stressors such as mechanical disturbances, direct injury, and changes in the extracellular matrix composition revealed the role of the different mechanisms that are up-regulated and down regulated during cartilage destruction. Chapter two will cover a paper I wrote that introduces a novel non-invasive technique applied to mice, which induces an early onset of OA in the TMJ. I developed this technique with the aim to provide a new mouse model where the onset and progression of OA more closely mimic the natural TMJ OA progression in humans. The histopathological analysis of the cartilage demonstrates that onset of OA starts at 2 weeks after treatment induction and is aggravated by week eight. This data demonstrated the effectiveness of our technique in inducing OA in the TMJ. Chapter three will cover a second paper I wrote on the association of RAGE with the progression of OA in the TMJ of mice by using mice with and without RAGE expression. RAGE has been show to contribute to the progression of OA by releasing several pro-inflammatory and catalytic cytokines. Additionally, RAGE has been shown to modulate the expression of specific OA biomarkers, including HtrA-1, Mmp-13, and Tgf-β1 in knee cartilage. The objective of this study was to study the effect of knocking out RAGE on the expression of Mmp-1 3, HtrA-1, and Tgf-β1 in the TMJ. After histophatological and quantitative analysis of biomarkers expression, the results demonstrated for the first time that absence of RAGE expression in the TMJ provides a protective effect against development of TMJ OA in mice.



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Life Sciences; Physiology and Developmental Biology



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