THE MODIFICATION OF ALVEOLAR BONE PROTEOGLYCANS BY REACTIVE OXYGEN SPECIES IN-VITRO

Reactive oxygen species (ROS) are being increasingly implicated in the connective tissue degradation associated with chronic inflammatory co nditions, such as periodontal disease. The present study investigated the effects of ROS on the proteoglyans (PG) of alveolar bone which are important structural components within the periodontium. PG were isol ated from ovine alveolar bone and exposed to increasing concentrations of hydrogen peroxide (H2O2) or to a hydroxyl radical ((OH)-O-.) flux for 1h or 24h, and the degradation products examined for depolymerisat ion and chemical modification of the PG structure, ROS were demonstrat ed to be capable of degrading alveolar bone PG in vitro, the (OH)-O-. species resulting in greater modification than H2O2, The degradative e ffects observed included cleavage of the protein core and depolymerisa tion of the GAG chains. The core proteins were more susceptible to deg radation than the GAG chains in the presence of H2O2 alone, although b oth the core proteins and the GAG chains were extensively degraded in the presence of a (OH)-O-. flux for bath 1h and 24h, Exposure of the P G to (OH)-O-. for 24h resulted in significant modification to the amin o acid composition with decreases in the proportion of leucine and the complete loss of proline, tyrosine and phenylalanine evident. The res ults highlight the potential role of ROS as an important mechanism in considering the pathology of periodontal tissue destruction.