title: Reactive oxygen species participation in experimentally induced arthritis of the temporomandibular joint in rats.
abstract: In the temporomandibular joint (TMJ), it has been hypothesized that mechanical stresses lead to the oxidative stress of articular tissues. It has also been postulated that cells pertinent to arthritis-including endothelial cells and synovial cells-when stimulated by mechanical stresses and/or pro-inflammatory cytokines, promote oxidative damage. To determine the involvement of reactive oxygen species (ROS) in the diseased joint, we studied the generation of ROS in synovial fluid (SF) from interleukin-1alpha (IL-1alpha)-induced TMJ arthritis by electron spin resonance (ESR) spectroscopy, using the spin trap 5,5-dimethyl-1-pyrroline N-oxide (DMPO). The TMJ arthritis was experimentally induced in rats by the injection of human recombinant IL-1alpha into the TMJ; control rats were treated with normal saline solution. We found that the detected radicals in the collected SF were identified as a 1:2:2:1 quartet, characteristic of the hydroxyl radical-DMPO spin adduct. The ESR signal intensity of the hydroxyl radical-DMPO spin adduct in the SF from IL-1-treated rats was significantly higher than that from the control rats (P < 0.01). The results of ESR study also showed that hydroxyl radical (HO*) was increased in a time-dependent fashion in the presence of superoxide anion radical (O2*-) scavenger superoxide dismutase (SOD); the formation of DMPO-HO* was strongly inhibited by the iron chelater deferoxamine. We could measure higher levels of free iron (Fe2- and Fe3-) in the SF from TMJ arthritis than in that from controls (P < 0.05). Analysis of the data obtained from the present study suggests that the HO* radical detected in SF from IL-1-induced TMJ arthritis is generated via a modified Haber-Weiss reaction (biological Fenton reaction) in which O2*- can subsequently result in the production of H2O2 through dismutation reaction by SOD. Thus, HO* may be generated from the reaction of resultant H2O2 with free iron ions. The results presented here provide the first evidence of involvement of ROS in IL-1-induced TMJ arthritis.
authors.affiliation: Second Department of Oral and Maxillofacial Surgery, Kanagawa Dental College, Yokosuka, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Kawai
authors.forename: E
authors.initials: E
authors.lastname: Kubota
authors.forename: E
authors.initials: E
authors.lastname: Okabe
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D004195:Disease Models, Animal; D004578:Electron Spin Resonance Spectroscopy / Q000379:methods; D006801:Humans; D017665:Hydroxyl Radical / Q000378:metabolism; D007375:Interleukin-1; D007501:Iron / Q000378:metabolism; D008297:Male; D010003:Osteoarthritis / Q000139:chemically induced / Q000378:metabolism*; D018384:Oxidative Stress; D051381:Rats; D017208:Rats, Wistar; D017382:Reactive Oxygen Species / Q000378:metabolism*; D011994:Recombinant Proteins; D018709:Statistics, Nonparametric; D013582:Synovial Fluid / Q000378:metabolism; D013705:Temporomandibular Joint Disorders / Q000378:metabolism*
chemical_list: D007375:Interleukin-1; D017382:Reactive Oxygen Species; D011994:Recombinant Proteins; D017665:Hydroxyl Radical; D007501:Iron