Ihalin R, Loimaranta V, Lenander-Lumikari M, Tenovuo J
Institute of Dentistry, University of Turku, Finland.
J Periodontal Res. 1998 Oct;33(7):421-7. doi: 10.1111/j.1600-0765.1998.tb02338.x.
Actinobacillus actinomycetemcomitans is a Gram-negative bacterium which has an important role in localized juvenile and in progressive periodontitis. It is sensitive to killing by the myeloperoxidase (MP)-hydrogen peroxide (H2O2)-chloride system which is part of the innate host defense mediated by polymorphonuclear leukocytes. Since it has been recently suggested that thiocyanate, instead of chloride, could serve as a main substrate for MP as for lactoperoxidase (LP) and salivary peroxidase, we investigated in this study the effect of both LP and MP systems on A. actinomycetemcomitans with different (pseudo)halide substrates, thiocyanate, chloride and iodide. The concentrations of the substrates were physiological for oral fluids, as was the concentration range of H2O2. Both peroxidases produced end products with identical antibacterial activity with thiocyanate and iodide. The oxidation of iodide resulted in the highest antimicrobial efficiency followed by chloride and thiocyanate. Addition of thiocyanate into either MP-H2O2-chloride or MP/LP-H2O2-iodide system abolished the bactericidal activity of the oxidized halide. However, the chloride did not affect the bactericidality of the MP-H2O2-iodide system, but when all 3 (pseudo)halide substrates were present no antimicrobial effect was recorded. Our study shows that the presence of thiocyanate in physiological amounts is able to prevent the bactericidal activity of halide-peroxidase systems in low H2O2 concentrations. These results explain why thiocyanate-peroxidase systems of either innate origin (saliva, crevicular fluid) or introduced by commercial oral hygiene products are most probably ineffective against A. actinomycetemcomitans in vivo. Further studies of halide/thiocyanate ratio are needed to develop products which are also effective against oral anaerobes.
伴放线放线杆菌是一种革兰氏阴性菌，在局限性青少年牙周炎和进展性牙周炎中起重要作用。它对髓过氧化物酶（MP）-过氧化氢（H2O2）-氯化物系统介导的杀伤敏感，该系统是多形核白细胞介导的固有宿主防御的一部分。由于最近有人提出，硫氰酸盐而非氯化物可作为MP的主要底物，就像乳过氧化物酶（LP）和唾液过氧化物酶一样，因此我们在本研究中调查了LP和MP系统对伴放线放线杆菌的影响，使用了不同的（拟）卤化物底物，即硫氰酸盐、氯化物和碘化物。底物浓度与口腔液的生理浓度相同，H2O2的浓度范围也是如此。两种过氧化物酶与硫氰酸盐和碘化物产生的终产物具有相同的抗菌活性。碘化物的氧化导致最高的抗菌效率，其次是氯化物和硫氰酸盐。在MP-H2O2-氯化物或MP/LP-H2O2-碘化物系统中添加硫氰酸盐会消除氧化卤化物的杀菌活性。然而，氯化物并不影响MP-H2O2-碘化物系统的杀菌能力，但当所有三种（拟）卤化物底物都存在时，未观察到抗菌效果。我们的研究表明，生理量的硫氰酸盐的存在能够在低H2O2浓度下阻止卤化物过氧化物酶系统的杀菌活性。这些结果解释了为什么无论是先天来源（唾液、龈沟液）还是商业口腔卫生产品引入的硫氰酸盐过氧化物酶系统在体内很可能对伴放线放线杆菌无效。需要进一步研究卤化物/硫氰酸盐比率，以开发对口腔厌氧菌也有效的产品。
