PEROXIDASE IN SALIVA AND PREVENTION OF ORAL DISEASE

乳过氧化物酶(LP)、过氧化氢(H_2O_2)和硫氰酸盐离子(SCN-) 在人类唾液中形成抑菌系统。口服“乳酸片” 细菌“释放过氧化氢，作为碳水化合物代谢的副产品。 唾液腺、口腔粘膜和唾液中受刺激的白细胞可能 还会产生过氧化氢并分泌过氧化物酶。过氧化物酶催化 用H_2O_2氧化SCN-生成次硫氰酸根离子(OSCN-) 次硫氰酸(HOSCN)的酸碱平衡。HOSCN氧化 细菌酶和运输系统的基本巯基， 从而抑制新陈代谢和生长。某些口腔细菌 例如变形链球菌对抑制的抵抗力有限，但被抑制 在酸性pH条件下。在以下情况下，所有细菌都能恢复并恢复新陈代谢和生长 OSCN-通过稀释或还原去除。OSCN的浓度- 在中性pH条件下，在人类唾液中发现的这些物质对人体细胞似乎没有毒性。 第一个目标是评估LP系统相对于 过氧化氢对微生物(变形链球菌、大肠杆菌、金黄色葡萄球菌、白色念珠菌)和 从而确定人成纤维细胞在体外是否起主要作用 LP系统是为了生产微双稳制剂或保护宿主 组织抗过氧化氢毒性。第二个目的是确定 白血球过氧化物酶、髓过氧化物酶和嗜酸性粒细胞过氧化物酶 唾液中依赖H_2O_2的抗菌活性。金额和 白细胞酶的活性将在唾液中进行测量， 添加更多的酶对抗菌活性的影响将是 下定决心。第三个目标是研究亚硝酸盐和 口腔微生物生态中的活性氮氧化物及其检测 与LP系统的交互。假设是亚硝酸盐 在唾液中产生的在低pH时变得微小的双稳态 一氧化氮(NO)，并可能为口服提供选择性优势 链球菌通过更有效地抑制其他细菌的能量代谢 微生物。亚硝酸盐也可能增强LP系统的毒性 低pH条件下HOSCN和NO对微生物的协同作用 巯基。该项目的目标是实现更大的 了解氧化剂在口腔健康和疾病中的作用。

Lactoperoxidase (LP), hydrogen peroxide (H2O2) and thiocyanate ion (SCN-) form a bacteriostatic system in human saliva. The oral "lactic-acid bacteria" release H2O2 as a by-product of carbohydrate metabolism. Stimulated leukocytes in the salivary glands, oral mucosa, and saliva may also produce H2O2 and secrete peroxidase enzymes. Peroxidases catalyze the oxidation of SCN- by H2O2 to yield hypothiocyanite ion (OSCN-), which is in acid-base equilibrium with hypothiocyanous acid (HOSCN). HOSCN oxidizes essential sulfhydryl groups of bacterial enzymes and transport systems, resulting in inhibition of metabolism and growth. Certain oral bacteria such as S. mutans have a limited resistance to inhibition but are inhibited at acid pH. All bacteria can recover and resume metabolism and growth when OSCN- is removed by dilution or reduction. The concentrations of OSCN- found in human saliva do not appear toxic to human cells at neutral pH. The first aim is to evaluate the toxicity of the LP system relative to that of H2O2 to microorganisms (S. mutans, E. coli, S. aureus, C. albicans) and human fibroblasts in vitro, so as to determine whether the primary role of the LP system is to produce a microbistatic agent or to protect host tissues against H2O2 toxicity. The second aims is determine the role of leukocyte peroxidase enzymes myeloperoxidase and eosinophil peroxidase in the H2O2-dependent antimicrobial activity of saliva. The amount and activity of the leukocyte enzymes will be measured in saliva, and the effect of adding more of the enzymes on antibacterial activity will be determined. The third aim is to investigate the role of nitrite and reactive nitrogen-oxides in oral microbial ecology and examine their interactions with the LP system. The hypothesis is that the nitrite produced in saliva becomes microbistatic at low pH due to the formation of nitric oxide (NO ) and may provide a selective advantage to oral streptococci by more effectively inhibiting the energy metabolism of other microorganisms. Nitrite may also potentiate the toxicity of the LP system at low pH through a cooperative attack of HOSCN and NO on microbial sulfhydryl groups. The goal of the project is to achieve a greater understanding of the role of oxidizing agents in oral health and disease.