METHODS: Rat models of periapical inflammation were established in 28 normal SD rats by opening the pulp cavity of the mandibular first molars, followed by injection of normal saline and Akt2 inhibitor into the left and right medullary cavities, respectively. Four rats without any treatment served as the healthy control group. At 7, 14, 21 and 28 days after modeling, 7 rat models and 1 control rat were randomly selected for observation of inflammatory infiltration in the periapical tissues by X-ray and HE staining. Immunohistochemistry was used to detect the expression and localization of Akt2, macrophages and the inflammatory mediators. RT-PCR was performed to detect the mRNA expressions of Akt2, CD86, CD163, inflammatory mediators, miR-155-5p and C/EBPβ to analyze the changes in macrophage polarization.
RESULTS: X-ray and HE staining showed that periapical inflammation was the most obvious at 21 days after modeling in the rats. Immunohistochemistry and RT-PCR showed that compared with those in the control rats, the expressions of Akt2, CD86, CD163, miR-155-5p, C/EBPβ, and IL-10 increased significantly in the rat models at 21 days (P < 0.05). Compared with saline treatment, treatment with the Akt2 inhibitor significantly decreased the expression levels of Akt2, CD86, miR-155-5p and IL-6 and the ratio of CD86+M1/CD163+M2 macrophages (P < 0.05) and increased the expression levels of CD163, C/EBPβ and IL-10 in the rat models (P < 0.05).
CONCLUSIONS: Inhibition of Akt2 can delay the progression of periapical inflammation in rats and promote M2 macrophage polarization in the periapical inflammatory microenvironment possibly by reducing miR-155-5p expression and activating the expression of C/EBPβ in the Akt signaling pathway.
方法:28只正常SD大鼠通过打开下颌第一磨牙牙髓腔建立根尖周炎大鼠模型,然后注射生理盐水和Akt2抑制剂进入左、右髓腔,分别。4只未经任何治疗的大鼠作为健康对照组。在建模后7、14、21和28天,随机选择7只大鼠模型和1只对照大鼠,通过X射线和HE染色观察根尖周组织的炎性浸润。免疫组化检测Akt2、巨噬细胞和炎症介质的表达和定位。RT-PCR检测Akt2、CD86、CD163、炎症介质、miR-155-5p和C/EBPβ分析巨噬细胞极化的变化。
结果:X线和HE染色显示,大鼠在造模后21天,根尖周炎最明显。免疫组织化学和RT-PCR显示,与对照组大鼠相比,Akt2,CD86,CD163,miR-155-5p,C/EBPβ,在第21天,大鼠模型中IL-10明显升高(P<0.05)。与生理盐水治疗相比,Akt2抑制剂治疗可显著降低Akt2、CD86、miR-155-5p和IL-6的表达水平和CD86+M1/CD163+M2巨噬细胞的比例(P<0.05),增加CD163、C/EBPβ和IL-10的表达水平(P<0.05)。
结论:抑制Akt2可以延缓大鼠根尖周炎性反应的进展,促进M2巨噬细胞在根尖周炎性微环境中的极化,可能是通过降低miR-155-5p的表达,激活Akt信号通路中C/EBPβ的表达。