PEROXIDASE IN SALIVA AND PREVENTION OF ORAL DISEASE

乳过氧化物酶（LP）、过氧化氢（H2 O2）和硫氰酸根离子（SCN-） 在人类唾液中形成抑菌系统。 口服“乳酸 细菌释放H2 O2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 也产生H2 O2和分泌过氧化物酶。 过氧化物酶催化 SCN-被H2 O2氧化生成次硫氰酸根离子（OSCN-）， 与次硫氰酸（HOSCN）的酸碱平衡。 HOSCN氧化 细菌酶和转运系统的必需巯基， 导致代谢和生长的抑制。 某些口腔细菌 如S.变形菌对抑制具有有限的抵抗力， 所有的细菌都可以恢复和恢复新陈代谢和生长， OSCN-通过稀释或还原除去。 OSCN的浓度- 在中性pH值下，人类唾液中发现的蛋白质对人体细胞没有毒性。 第一个目的是评价LP系统相对于 H_2O_2对微生物（S. mutans、E. coli、S. aureus，C.白色念珠菌）和 体外培养人成纤维细胞，从而确定是否具有主要作用。 LP系统用于产生微生物抑制剂或保护宿主 组织对H2 O2毒性。 第二个目标是确定 髓过氧化物酶和嗜酸性粒细胞过氧化物酶 唾液的H2 O2依赖性抗菌活性。 的量和 将在唾液中测量白细胞酶的活性， 添加更多的酶对抗菌活性的影响将是 测定 第三个目的是研究亚硝酸盐的作用， 口腔微生物生态学中的活性氮氧化物，并检查其 与LP系统的互动。 假设是亚硝酸盐 在低pH值下，由于唾液中产生的 一氧化氮（NO），并可能提供选择性优势，口服 通过更有效地抑制其他链球菌的能量代谢， 微生物的 亚硝酸盐也可能增强LP系统的毒性 通过HOSCN和NO对微生物的协同攻击， 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.