A determination of tumor necrosis factor expression in TMJ inflammation with the use of microarray analysis

Many different factors can lead to inflammatory changes within temporomandibular joint tissues. This investigation examined if the expression of TNF-alpha and its receptors was altered in TMJ tissues during inflammation. Adult male rats were injected bilaterally with complete Freund's adjuvant (CFA) into the TMJ or served as uninjected controls and were killed two days after CFA treatment. TMJ tissues were removed, and expression of TNF-alpha and its receptors was examined via gene microarray analysis, RT-PCR, Western blot, and ELISA. Gene microarray analysis provided evidence for changes in gene expression, notably that TNF-alpha and TNF-R1, but not TNF-R2, were significantly elevated in CFA-treated TMJ tissues. However, protein levels of TNF-alpha, TNF-R1, and TNF-R2 were all significantly increased in CFA-treated TMJ tissues. These results indicate that the pro-inflammatory cytokine TNF-alpha may play a significant role in the onset of inflammatory conditions associated with adjuvant-induced arthritis of the TMJ.