Role of Superoxide Dismutase in the Resistance of Periodontopathic Bacteria to Killing by Neutrophils

在本研究中，我们评估了超氧化物歧化酶对中性粒细胞杀死黑色口腔厌氧棒的影响，该酶通过诱导其合成或外源添加而变化。SOD活性较高的牙龈卟啉单胞菌381对中性粒细胞的杀伤作用不敏感。而在黑色口腔厌氧棒中SOD活性最低、氧敏感性最高的齿状普雷沃特菌ATCC 33185被吞噬后立即死亡。分别从厌氧维持或曝气的牙龈假单胞菌381的提取物中纯化出SOD_s（厌氧sod和曝气sod）。纯化后的酶具有相同的分子量和等电点。此外，这两种酶具有完全相同的氨基酸-序列。然而，两种酶的金属含量和光谱分析表明，厌氧sod具有FE-SOD的特征，而气动sod具有MnSOD的特征。研究了外源添加的aero-SOD和anaers-SOD对牙龈卟啉单胞菌抗中性粒细胞杀伤的影响。两种SOD_s对细菌杀灭均有抑制作用，但两种酶的抑制作用没有差异。通过曝气或在培养基中添加硝酸钾诱导牙龈卟啉卟啉381合成SOD。当P. gingivalis 381在硝酸盐和曝气条件下的SOD比活性分别提高2.3倍和2.0倍时，细菌对中性粒细胞杀伤的抵抗力显著高于对照。这些结果表明，SOD可能是一种防御机制的一部分，有助于保护牙龈卟啉卟啉菌免受中性粒细胞的杀伤。

In this study, we assessed the influence of superoxide dismutase, which was varied by inducing its synthesis or by adding it exogenously, on killing of black-pigmented oral anaerobic rods by neutrophils. Porphyromonas gingivalis 381 which had a high SOD activity was not highly sensitive to the killing effect of neutrophils. However, Prevotella denticola ATCC 33185 which showed the lowest activity of SOD and was also the highest oxygen sensitivity among the black-pigmented oral anaerobic rods tested was immediately killed after phagocytosis.SOD_s were purified from extracts of either anaerobically maintained or aerated P. gingivalis 381 (anaers-SOD and aero-SOD, respectively). Each-purified enzyme showed same molecular weight and isoelectric points. Furthermore, the two enzymes had completely identical amino acid, -sequences. However, metal contents and spectral analysis of both enzymes showed that anaers-SOD had the characteristic of FE-SOD and that aero-SOD had that of MnSOD. The effect of aero-SOD or anaers-SOD added exogenously on resistance of P. gingivalis to killing by neutrophils was examined. Both SOD_s inhibited bacterial killing, but there was no difference in the inhibitory effects between these two enzymes.Induction of the synthesis of SOD in P. gingivalis 381 was performed by an aeration or by the addition of potassium nitrate to the growth medium. When the specific activities of SOD in P. gingivalis 381 increased 2.3-fold and 2.0-fold by growth in the presence of nitrate and by aeration, respectively, the resistances of the bacterium to killing by the neutrophils were significantly greater than that of control. These results suggest that SOD may form part of a defence mechanism that helps protect P. gingivalis from killing by neutrophils.