Department of Orthopedics, The Affiliated Hospital of Xuzhou Medical University, Xuzhou, China.
J Biomed Mater Res A. 2021 Jun;109(6):994-1003. doi: 10.1002/jbm.a.37088. Epub 2020 Sep 13.
After bone prosthesis replacement, M1-type macrophage polarization can be induced by titanium (Ti) particles and produce inflammatory, leading to osteolysis. Adipocyte-derived exosomes (ADEs) exert immune-modulatory impact on the macrophage, while whether it can inhibit the macrophage polarization induced by Ti is unclear. This study focuses on the M1-type macrophage and aims to determine the effect of ADEs on Ti-induced M1-type macrophage polarization in osteolytic mice and the involved mechanism.
Ti particle-induced osteolysis mouse model was established and macrophages were isolated from the osteolysis site. The levels of NLRP3 and specific markers for M1-type macrophage were determined. ADEs isolated from adipocyte cell line 3T3-L1, or conditioned ADEs with low-expressed miR-34a isolated from 3T3-L1 transfected with miR-34a inhibitor were co-cultured with RAW 264.7 to determine their impact on the polarization of macrophage.
ADEs reduced the M1-type macrophage polarization and caused the upregulation of miR-34a in macrophage of the osteolysis site of the osteolysis mouse model. Also, the level of miR-34a in ADEs was higher than that in the adipocyte. The conditioned ADEs expressed a low level of miR-34a and boosted the Ti-induced M1-type polarization. MiR-34a could target NLRP3 and negatively regulated its expression. Moreover, NLRP3 knockdown in macrophage restricted the conditioned ADEs to promote macrophage towards to Ti-induced M1-type polarization. The inhibitory function of ADEs on M1-type macrophage polarization was abolished by miR-34a silencing in the mouse osteolysis model.
The miR-34a carried by ADEs reduced the polarization of M1-type macrophages by targeting macrophage NLRP3 during Ti particle-induced osteolysis.
钛（Ti）颗粒可诱导 M1 型巨噬细胞极化，并产生炎症，导致骨溶解。脂肪细胞衍生的外泌体（ADE）对巨噬细胞具有免疫调节作用，但不清楚它是否能抑制 Ti 诱导的巨噬细胞极化。本研究聚焦于 M1 型巨噬细胞，旨在确定 ADE 对 Ti 诱导的破骨溶解小鼠 M1 型巨噬细胞极化的影响及其机制。
建立 Ti 颗粒诱导的骨溶解小鼠模型，从骨溶解部位分离巨噬细胞。测定 NLRP3 水平和 M1 型巨噬细胞的特异性标志物。将来自脂肪细胞系 3T3-L1 的 ADE 或用 miR-34a 抑制剂转染的 3T3-L1 中低表达 miR-34a 的条件 ADE 与 RAW 264.7 共培养，以确定它们对巨噬细胞极化的影响。
ADE 减少了 M1 型巨噬细胞极化，并导致骨溶解小鼠模型骨溶解部位巨噬细胞中 miR-34a 的上调。此外，ADE 中的 miR-34a 水平高于脂肪细胞。条件 ADE 表达低水平的 miR-34a，并促进 Ti 诱导的 M1 型极化。miR-34a 可靶向 NLRP3 并负调控其表达。此外，巨噬细胞中 NLRP3 的敲低限制了条件 ADE 促进巨噬细胞向 Ti 诱导的 M1 型极化。在小鼠骨溶解模型中，miR-34a 的沉默消除了 ADE 对 M1 型巨噬细胞极化的抑制作用。
在 Ti 颗粒诱导的骨溶解过程中，ADE 携带的 miR-34a 通过靶向巨噬细胞 NLRP3 减少 M1 型巨噬细胞的极化。
