Ponce José Burgos, Midena Raquel Zanin, Pinke Karen Henriette, Weckwerth Paulo Henrique, Andrade Flaviana Bombarda de, Lara Vanessa Soares
a Department of Surgery, Stomatology, Pathology and Radiology, Bauru School of Dentistry , University of São Paulo , Bauru , Brazil.
b Department of Operative Dentistry, Endodontics and Dental Materials, Bauru School of Dentistry , University of São Paulo , Bauru , Brazil.
Acta Odontol Scand. 2019 Mar;77(2):158-163. doi: 10.1080/00016357.2018.1533142. Epub 2019 Jan 8.
Monocyte-derived macrophages (MDMs) ability to phagocytize and produce nitric oxide (NO) was tested against root-canal strains of Enterococcus faecalis submitted to alkaline stress. Root-canal strains were also compared with urine Enterococci.
Enterococcus faecalis were stressed with alkaline-BHI broth and incubated in vitro at a cell/bacteria ratio of 1:5. Phagocytosis was analyzed by fluorescence microscopy using acridine orange stain, and NO concentration was measured in supernatants.
Alkaline-stress significantly impaired MDMs phagocytosis of E. faecalis strains analyzed, except in ATCC4083 isolated from a pulpless tooth, but NO production was unchanged. Comparison of different strains showed the urine isolate had higher NO levels than root canal strains. Alterations in the bacterial cell wall structures after alkaline-stress possibly made bacteria less recognizable and phagocytized by MDMs but did not affect their ability to activate NO production. Furthermore, root canal strains elicited different responses by immune cells compared with strains from urine. Clinically, impaired phagocytosis of E. faecalis could contribute to their persistence in root canal systems previously treated with calcium hydroxide.
测试单核细胞衍生的巨噬细胞（MDMs）对经受碱性应激的粪肠球菌根管菌株的吞噬能力和产生一氧化氮（NO）的能力。还将根管菌株与尿液肠球菌进行了比较。
用碱性脑心浸液肉汤对粪肠球菌进行应激处理，并以1:5的细胞/细菌比例在体外培养。使用吖啶橙染色通过荧光显微镜分析吞噬作用，并测定上清液中的NO浓度。
碱性应激显著损害了所分析的粪肠球菌菌株的MDMs吞噬作用，但从无髓牙分离的ATCC4083除外，不过NO的产生没有变化。不同菌株的比较表明，尿液分离株的NO水平高于根管菌株。碱性应激后细菌细胞壁结构的改变可能使细菌更难被MDMs识别和吞噬，但不影响它们激活NO产生的能力。此外，与尿液菌株相比，根管菌株引发免疫细胞的反应不同。临床上，粪肠球菌吞噬作用受损可能导致它们在先前用氢氧化钙治疗的根管系统中持续存在。
