Mandibular condylar chondrocyte apoptosis is mainly responsible for the development and progression of temporomandibular joint osteoarthritis (TMJ-OA). Interleukin-1β (IL-1β) generally serves an agent that induces chondrocyte apoptosis. Hyperbaric oxygen (HBO) treatment increases proteoglycan synthesis in vivo.
We explore the protective effect of HBO on IL-1β-induced mandibular condylar chondrocyte apoptosis in rats and the potential molecular mechanisms. Methods: Chondrocytes were isolated from the TMJ of 3-4-week old SpragueDawley rats. The Cell Counting Kit-8 (CCK-8) assay was used to determine cell viability. The phosphorylated phosphoinositide-3 kinase (p-PI3K), phosphorylated AKT (p-Akt), type II collagen (COL2), and aggrecan (AGG) content was detected by immunofluorescence, immunocytochemistry and western blotting. The expression of Pi3k, Akt, Col2 and Agg mRNA was measured using real-time quantitative polymerase chain reaction (RT-qPCR).
HBO inhibited the cytotoxicity and apoptosis induced by IL-1β (10 ng/mL) in the mandibular condylar chondrocytes. HBO also decreased the IL-1β activity that decreased p-PI3K and p-AKT levels, and increased COL2 and AGG expression, with the net effect of suppressing extracellular matrix degradation. Conclusions: These data suggest that HBO may protect mandibular condylar chondrocytes against IL-1β-induced apoptosis via the PI3K/AKT signaling pathway, and that it may promote the expression of mandibular condylar chondrocyte extracellular matrix through the PI3K/AKT signaling pathway. In summary, our results confirm that HBO inhibits chondrocyte apoptosis induced by IL-1β and promotes extracellular matrix synthesis in rat OA mandibular condylar chondrocytes via the PI3K/AKT signaling pathway. These findings suggest that HBO has a potential therapeutic function for treating TMJ-OA.
Hang Chen, Gaoyi Wu3, Qi Sun, Yabing Dong, Huaqiang Zhao, College of Stomatology, Shandong University, Jinan City, Shandong, China; 2Shandong Provincial Key Laboratory of Oral Tissue Regeneration, Shandong, China; Department of Stomatology, Jinan Military General Hospital, Shandong, China. Am J Transl Res 2016; 8(11):5108-5117 www.ajtr.org /ISSN:1943-8141/AJTR0035333