Departamento de Clínica Infantil, Faculdade de Odontologia de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, SP, Brasil.
Departamento de Análises Clínicas, Toxicológicas e Bromatológicas, Faculdade de Ciências Farmacêuticas de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, SP, Brasil.
J Appl Oral Sci. 2020;28:e20190699. doi: 10.1590/1678-7757-2019-0699. Epub 2020 May 11.
Purpose To evaluate the kinetics of apical periodontitis development in vivo , induced either by contamination of the root canals by microorganisms from the oral cavity or by inoculation of bacterial lipopolysaccharide (LPS) and the regulation of major enzymes and receptors involved in the arachidonic acid metabolism. Methodology Apical periodontitis was induced in C57BL6 mice (n=96), by root canal exposure to oral cavity (n=48 teeth) or inoculation of LPS (10 µL of a suspension of 0.1 µg/µL) from E. coli into the root canals (n= 48 teeth). Healthy teeth were used as control (n=48 teeth). After 7, 14, 21 and 28 days the animals were euthanized and tissues removed for histopathological and qRT-PCR analyses. Histological analysis data were analyzed using two-way ANOVA followed by Sidak's test, and qRT-PCR data using two-way ANOVA followed by Tukey's test (α=0.05). Results Contamination by microorganisms led to the development of apical periodontitis, characterized by the recruitment of inflammatory cells and bone tissue resorption, whereas inoculation of LPS induced inflammatory cells recruitment without bone resorption. Both stimuli induced mRNA expression for cyclooxygenase-2 and 5-lipoxygenase enzymes. Expression of prostaglandin E 2 and leukotriene B 4 cell surface receptors were more stimulated by LPS. Regarding nuclear peroxisome proliferator-activated receptors (PPAR), oral contamination induced the synthesis of mRNA for PPARδ, differently from inoculation of LPS, that induced PPARα and PPARγ expression. Conclusions Contamination of the root canals by microorganisms from oral cavity induced the development of apical periodontitis differently than by inoculation with LPS, characterized by less bone loss than the first model. Regardless of the model used, it was found a local increase in the synthesis of mRNA for the enzymes 5-lipoxygenase and cyclooxygenase-2 of the arachidonic acid metabolism, as well as in the surface and nuclear receptors for the lipid mediators prostaglandin E2 and leukotriene B4.
目的 评估由口腔微生物污染根管或接种细菌脂多糖（LPS）引起的体内根尖周炎发展的动力学，并调节参与花生四烯酸代谢的主要酶和受体。
方法 通过根管暴露于口腔（n=48 牙）或将来自大肠杆菌的 LPS（10 µL 浓度为 0.1 µg/µL 的悬浮液）接种到根管中（n=48 牙），在 C57BL6 小鼠（n=96）中诱导根尖周炎。健康牙齿用作对照（n=48 牙）。7、14、21 和 28 天后，处死动物并取出组织进行组织病理学和 qRT-PCR 分析。使用双向方差分析（ANOVA）和 Sidak 检验分析组织学分析数据，使用双向 ANOVA 和 Tukey 检验（α=0.05）分析 qRT-PCR 数据。
结果 微生物污染导致根尖周炎的发展，其特征为炎症细胞募集和骨组织吸收，而 LPS 接种仅引起炎症细胞募集而无骨吸收。两种刺激均诱导环氧合酶-2 和 5-脂氧合酶酶的 mRNA 表达。LPS 更刺激前列腺素 E2 和白三烯 B4 细胞表面受体的表达。关于核过氧化物酶体增殖物激活受体（PPAR），口腔污染诱导 PPARδ 的 mRNA 合成，与 LPS 接种不同，其诱导 PPARα 和 PPARγ 的表达。
结论 口腔微生物污染根管引起的根尖周炎发展与 LPS 接种不同，其特征为比第一种模型骨丢失较少。无论使用哪种模型，均发现局部花生四烯酸代谢的 5-脂氧合酶和环氧合酶-2 酶以及前列腺素 E2 和白三烯 B4 脂类介质的表面和核受体的 mRNA 合成增加。
