RESUMEN
OBJECTIVE: 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. METHODS: 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. RESULTS: 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. CONCLUSION: The miR-34a carried by ADEs reduced the polarization of M1-type macrophages by targeting macrophage NLRP3 during Ti particle-induced osteolysis.
Asunto(s)
Adipocitos/metabolismo , Exosomas/metabolismo , Terapia Genética/métodos , Macrófagos , MicroARNs/administración & dosificación , Osteólisis/terapia , Células 3T3 , Animales , Polaridad Celular , Ratones , Proteína con Dominio Pirina 3 de la Familia NLR/metabolismo , Nanopartículas , Osteólisis/inducido químicamente , Células RAW 264.7 , Titanio , Regulación hacia Arriba/efectos de los fármacosRESUMEN
It remains unclear why obese persons displayed a slower wound healing rate than the normal. In this study, we found that has_circ_0075932, a single-exon circular RNA, was outstandingly expressed in human normal adipose tissue and overexpressed in burned skin of obese persons compared with that of non-obese persons. Circ_0075932 overexpression or silencing in dermal keratinocytes had no obvious effect on cell behaviors, unless dozens of times overexpression, since its basal expression level in keratinocytes is too low. However, the exosome released from circ_0075932-overexpressing adipocytes displayed a significantly promoting effect on inflammation and apoptosis in dermal keratinocytes. Then, in our mechanism exploration, we found that circ_0075932 directly bound with the RNA-binding protein PUM2, which was reported to positively regulated AuroraA kinase, thus activating the NF-κB pathway. Moreover, either silencing PUM2, silencing AuroraA, or blockade of NF-κB activation, could abrogate the promoting effect of adipocyte-derived exosomal circ_0075932 on cell inflammation and apoptosis.