Dr. Adams' Alabama Headache Blog

NF-kB plays a pivotal role in pathogenesis in general arthritis. However, the participation of NF-kB in inflammation of the temporomandibular joint (TMJ) is poorly understood. We examined NF-kB expression in rat TMJs with synovitis induced by condyle hypermobility. By immunohistochemistry, NF-kB immunoreactivity was found mainly in the cytoplasm, not the nucleus, of the synovial lining cells of induced synovitis and control TMJs. Southwestern histochemistry, a new method for detecting transcription factors, showed greater NF-kB expression in the nucleus of the synovial lining in the hypertrophic synovium than in the control synovium. Increased levels of the synovial lining cells with immunoreactivity for inducible nitric oxide synthase (iNOS), which is transcriptionally regulated by NF-kB, were also seen in the inflamed synovium. These findings indicated that excess mechanical stress increases NF-kB activation in the TMJ and suggest that active NF-kB is incolved in the progression of the TMJ inflammation.