Objective. To investigate the effects of cerium dioxide (CeO₂) nanoparticles on the inflammatory response of peritonitis rats induced by Staphylococcus epidermidis infection. Methods. Green tea polyphenol CeO2 nanoparticles were synthesized and characterized by transmission microscopy, ultraviolet-visible spectroscopy, FT-IR, and powder diffractometer. 40 male adult SD rats were randomly divided into 4 groups (n = 10 each): a control group, a model group, a CeO2 group, and a CeO2 + model group. Staphylococcus epidermidis solution was injected intraperitoneally with 10⁷ CFU/ml of bacterial solution in the model group, while the control group was injected intraperitoneally with the same amount of normal saline, and the CeO2 and CeO2 + model groups were injected with 0.5 mg/kg CeO2 nanoparticles through the tail vein for 2 h and then injected with saline or bacterial solution for 2 h, respectively. After 0 h, 3 h, 12 h, 24 h, and 48 h of model construction, rats were sacrificed, and serum and peritoneal lavage fluid were collected. The total number of leukocytes and the percentage of each type of leukocytes in the peritoneal lavage fluid were determined. Enzyme-linked immunosorbent assay (ELISA) was used to detect the level of inflammatory factor TNF-α in serum and peritoneal lavage fluid, and myeloperoxidase (MPO) activity in peritoneal tissue was also measured. In addition, real-time fluorescence quantitative PCR (RT-PCR) was used to measure the expression of TLR2 and TLR4 in peritoneal tissue, and western blotting was used to detect the expression of TLR2, TLR4, and the activation of NF-κB signaling pathways as well. Results. The CeO2 has an average size of 37 ± 3 nm with binding activity to proteins, phenolic compounds, and alkaloids. After counting the white blood cells in the peritoneal lavage fluid, it was found that the total number of white blood cells and the percentage of neutrophils in the model group were significantly increased (both ), and CeO2 treatment significantly reversed the above changes (both ). The ELISA results showed that compared with the control group, the TNF-α in the peritoneal lavage fluid and serum of the model group increased in a time-dependent manner (all ); however, there was no significant change in the CeO2 group (); at the same time in the CeO2 + model group, the TNF-α content was significantly reduced (all ). Detection of MPO activity in peritoneal tissue revealed that MPO activity was significantly increased under peritonitis (all ), and CeO2 treatment could mitigate that increase (all ). RT-PCR results showed that compared with the control group, the expression of TLR2 and TLR4 mRNA levels in the peritoneum of the model group were increased in a time-dependent manner (all ), and there was no significant change in the CeO2 group (); however, TLR2 and TLR4 mRNA levels were significantly reduced in the CeO2 + model group (all ). Western blotting test was performed on the peritoneal tissue collected after 48 h of the model establishment. Compared with the control group, the levels of TLR2, TLR4, p–NF–κB, and p-IκBα protein in the model group were significantly increased (all ), while CeO2 group showed no significant changes () and administration of CeO2 before model construction can significantly reverse the above protein activation (all ). Conclusion. CeO2 nanoparticles have anti-inflammatory effects in peritonitis caused by Staphylococcus epidermidis infection.

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二氧化铈纳米颗粒对表皮葡萄球菌感染所致大鼠腹膜炎的抗炎作用

目标。研究二氧化铈（CeO ₂）纳米颗粒对表皮葡萄球菌感染引起的腹膜炎大鼠炎症反应的影响。方法。合成了绿茶多酚CeO2纳米粒子，并通过透射显微镜，紫外可见光谱，FT-IR和粉末衍射仪进行了表征。将40只成年雄性SD大鼠随机分为4组（每组n  = 10）：对照组，模型组，CeO2组和CeO2 +模型组。表皮葡萄球菌溶液腹腔注射10 ⁷ 模型组CFU / ml细菌溶液，对照组腹腔注射等量生理盐水，CeO2和CeO2 +模型组通过尾静脉注射0.5 mg / kg CeO2纳米颗粒2 h。然后分别注射生理盐水或细菌溶液2 h。在模型构建的0小时，3小时，12小时，24小时和48小时后，处死大鼠，并收集血清和腹膜灌洗液。测定腹膜灌洗液中白细胞的总数和每种类型的白细胞的百分比。酶联免疫吸附试验（ELISA）用于检测炎症因子TNF- α的水平在血清和腹膜灌洗液中，还测量了腹膜组织中的髓过氧化物酶（MPO）活性。此外，实时荧光定量PCR（RT-PCR）来测定TLR2和TLR4在腹膜组织的表达，用Western印迹法检测TLR2，TLR4的表达，和NF-的活化κ乙信号通路。结果。CeO2的平均大小为37±3 nm，对蛋白质，酚类化合物和生物碱具有结合活性。计数腹腔灌洗液中的白细胞后，发现模型组中白细胞总数和中性粒细胞百分比显着增加（两者均），CeO2处理可显着逆转上述变化（均）。ELISA结果表明，模型组腹腔灌洗液和血清中的TNF- α与对照组相比呈时间依赖性增加（全部）。但是，CeO2组没有明显变化（）；同时，在CeO2 +模型组中，TNF- α含量显着降低（全部）。腹膜组织中MPO活性的检测显示，腹膜炎下MPO活性显着增加（全部），而CeO2处理可以减轻这种增加（全部）。RT-PCR结果显示，与对照组相比，模型组腹膜中TLR2和TLR4 mRNA的表达呈时间依赖性增加（全部），而CeO2组无明显变化（）; 但是，在CeO2 +模型组中，TLR2和TLR4 mRNA水平显着降低（全部）。在建立模型48小时后，对收集的腹膜组织进行蛋白质印迹试验。与对照组，TLR2，TLR4，对NF-的水平相比κ B，等电点κ乙α模型组蛋白均显著增加（所有），而氧化铈组比较无显著变化（）在模型构建之前使用CeO2可以显着逆转上述蛋白质激活（全部）。结论。CeO2纳米颗粒在表皮葡萄球菌感染引起的腹膜炎中具有抗炎作用。