Differential Expression of Superoxide Dismutase Isoforms in Inflammatory Periodontal Disease

Objectives: It has been claimed the imbalances in levels of free radicals and reactive oxygen species with antioxidants may play an important role in the onset and development of several inflammatory oral pathologies. Recently, it was found oxidative damage in the chronic inflammatory periodontal diseases. Among the diverse endogenous antioxidant defence mechanisms, superoxide dismutase (SOD) form the primary defence against the deleterious effects of reactive oxygen species (ROS), ensuring that O2 is efficiently converted to H2O2. There are three major forms of SOD in human: cytoplasmic copper-zinc superoxide dismutase (Cu/Zn-SOD), mitochondrial manganese superoxide dismutase (Mn-SOD), and extracellular superoxide dismutase (EC-SOD). This study aims to assess the degree of oxidative stress in patients with periodontitis by detecting their levels of enzymatic antioxidants, SOD. Methods: It was conducted on 53 chronic periodontitis patients of Department of Periodontics in Chonnam University Hospital. All specimens staining with haematoxylin and eosin were divided into four groups by intensity of inflammation: healthy, mild, moderate and severe periodontitis. Immunohistochemistry with Cu/Zn-SOD, Mn-SOD and EC-SOD (at a dilution of 1:800, 1:400, 1:100, respectively) was performed using the labeled avidin-biotinylated enzyme complex kit. Results: It was observed that mild to moderate inflammatory infiltration in the clinically healthy gingival tissue. The periodontitis patients had a significantly higher SOD expression, especially Cu/Zn-SOD and Mn-SOD, than the healthy subjects. In inflammatory gingiva, Cu/Zn-SOD was expressed in the basal layer and Mn-SOD is markedly increased in the granular and keratinized layer as well as connective tissue near rete peg with intensity of inflammation. All SOD isoforms were specific for the endothelial cells and EC-SOD was expressed only in the walls of small capillaries regardless of inflammation. Conclusion: This study indicated that enhanced activities of SOD in the gingival tissues could be related to a greater degree of oxidative stress in patients with periodontitis.