Zhang Xuan, Hu Bo, Sun Jicheng, Li Jie, Liu Shan, Song Jinlin
College of Stomatology, Chongqing Medical University, Chongqing, China.
Chongqing Key Laboratory for Oral Diseases and Biomedical Sciences, Chongqing, China.
J Ultrasound Med. 2017 Dec;36(12):2419-2429. doi: 10.1002/jum.14239. Epub 2017 Jun 10.
Low-intensity pulsed ultrasound (US) has been reported to promote periodontal tissue regeneration and reduce inflammation in soft tissues and in bone infectious diseases. Here we investigated the effect of low-intensity pulsed US on the expression of lipopolysaccharide (LPS)-induced inflammatory factors in U937 macrophage cells.
U937 cells were stimulated with different concentrations of LPS and exposed to different intensities of low-intensity pulsed US. Cell viability and apoptosis of U937 cells were determined by cell-counting kit assays and flow cytometry. A real-time polymerase chain reaction and an enzyme-linked immunosorbent assay were used to test the expression of inflammatory factors. The expression levels of toll-like receptor 4, p65, p-IκBα, and IκBα were assessed by western blots.
Tumor necrosis factor α began to increase in U937 cells on induction with 1-μg/mL LPS. Low-intensity pulsed US at the intensity of 60 mW/cm was more effective in reducing interleukin 8 (IL-8) expression. Furthermore, LPS inhibited the viability and increased apoptosis of U937 cells, whereas low-intensity pulsed US significantly reversed these effects (P < .05). Low-intensity pulsed US reduced the protein expression of IL-6 and IL-8 at both gene and protein levels in U937 cells. The western blot and immunofluorescence showed that low-intensity pulsed US primarily suppressed the degradation and phosphorylation of IκBα and the translocation of p65 into the nuclei.
Low-intensity pulsed US alleviated the expression of inflammatory factors induced by LPS in U937 cells. This process was modulated by suppressing the toll-like receptor 4-nuclear factor κB signaling pathway. Therefore, low-intensity pulsed US might be a potential immunomodulatory therapy for the treatment of periodontitis.
据报道，低强度脉冲超声（US）可促进牙周组织再生，并减轻软组织和骨感染性疾病中的炎症。在此，我们研究了低强度脉冲超声对脂多糖（LPS）诱导的U937巨噬细胞中炎症因子表达的影响。
用不同浓度的LPS刺激U937细胞，并使其暴露于不同强度的低强度脉冲超声下。通过细胞计数试剂盒检测和流式细胞术测定U937细胞的活力和凋亡情况。采用实时聚合酶链反应和酶联免疫吸附测定法检测炎症因子的表达。通过蛋白质印迹法评估Toll样受体4、p65、p-IκBα和IκBα的表达水平。
用1μg/mL LPS诱导后，U937细胞中的肿瘤坏死因子α开始增加。强度为60 mW/cm的低强度脉冲超声在降低白细胞介素8（IL-8）表达方面更有效。此外，LPS抑制U937细胞的活力并增加其凋亡，而低强度脉冲超声可显著逆转这些作用（P < 0.05）。低强度脉冲超声在基因和蛋白质水平上均降低了U937细胞中IL-6和IL-8的蛋白质表达。蛋白质印迹和免疫荧光显示，低强度脉冲超声主要抑制IκBα的降解和磷酸化以及p65向细胞核的转位。
低强度脉冲超声减轻了LPS诱导的U937细胞中炎症因子的表达。这一过程是通过抑制Toll样受体4-核因子κB信号通路来调节的。因此，低强度脉冲超声可能是治疗牙周炎的一种潜在免疫调节疗法。
