Center on Aging, UConn Health, Farmington, Connecticut, USA.
Center for Molecular Oncology, UConn Health, Farmington, Connecticut, USA.
J Cell Physiol. 2024 Aug;239(8):e31299. doi: 10.1002/jcp.31299. Epub 2024 May 19.
Osteoclasts are the cells primarily responsible for inflammation-induced bone loss, as is particularly seen in rheumatoid arthritis. Increasing evidence suggests that osteoclasts formed under homeostatic versus inflammatory conditions may differ in phenotype. While microRNA-29-3p family members (miR-29a-3p, miR-29b-3p, miR-29c-3p) promote the function of RANKL-induced osteoclasts, the role of miR-29-3p during inflammatory TNF-α-induced osteoclastogenesis is unknown. We used bulk RNA-seq, histology, qRT-PCR, reporter assays, and western blot analysis to examine bone marrow monocytic cell cultures and tissue from male mice in which the function of miR-29-3p family members was decreased by expression of a miR-29-3p tough decoy (TuD) competitive inhibitor in the myeloid lineage (LysM-cre). We found that RANKL-treated monocytic cells expressing the miR-29-3p TuD developed a hypercytokinemia/proinflammatory gene expression profile in vitro, which is associated with macrophages. These data support the concept that miR-29-3p suppresses macrophage lineage commitment and may have anti-inflammatory effects. In correlation, when miR-29-3p activity was decreased, TNF-α-induced osteoclast formation was accentuated in an in vivo model of localized osteolysis and in a cell-autonomous manner in vitro. Further, miR-29-3p targets mouse TNF receptor 1 (TNFR1/Tnfrsf1a), an evolutionarily conserved regulatory mechanism, which likely contributes to the increased TNF-α signaling sensitivity observed in the miR-29-3p decoy cells. Whereas our previous studies demonstrated that the miR-29-3p family promotes RANKL-induced bone resorption, the present work shows that miR-29-3p dampens TNF-α-induced osteoclastogenesis, indicating that miR-29-3p has pleiotropic effects in bone homeostasis and inflammatory osteolysis. Our data supports the concept that the knockdown of miR-29-3p activity could prime myeloid cells to respond to an inflammatory challenge and potentially shift lineage commitment toward macrophage, making the miR-29-3p family a potential therapeutic target for modulating inflammatory response.
破骨细胞是主要负责炎症诱导的骨丢失的细胞，类风湿关节炎中尤其如此。越来越多的证据表明，在稳态与炎症条件下形成的破骨细胞在表型上可能不同。虽然 microRNA-29-3p 家族成员（miR-29a-3p、miR-29b-3p、miR-29c-3p）促进 RANKL 诱导的破骨细胞的功能，但 miR-29-3p 在炎症性 TNF-α 诱导的破骨细胞生成中的作用尚不清楚。我们使用批量 RNA-seq、组织学、qRT-PCR、报告基因测定和 Western blot 分析检查了雄性小鼠的骨髓单核细胞培养物和组织，其中 miR-29-3p 家族成员的功能通过在髓系（LysM-cre）中表达 miR-29-3p 坚韧诱饵（TuD）竞争性抑制剂而降低。我们发现，在用 RANKL 处理的表达 miR-29-3p TuD 的单核细胞中，体外培养物中表现出高细胞因子血症/促炎基因表达谱，与巨噬细胞相关。这些数据支持 miR-29-3p 抑制巨噬细胞谱系分化并可能具有抗炎作用的概念。相关地，当 miR-29-3p 活性降低时，TNF-α 诱导的破骨细胞形成在局部骨溶解的体内模型中和体外细胞自主方式中被增强。此外，miR-29-3p 的靶标是鼠 TNF 受体 1（TNFR1/Tnfrsf1a），这是一种进化保守的调节机制，可能导致在 miR-29-3p 诱饵细胞中观察到的 TNF-α 信号敏感性增加。虽然我们之前的研究表明 miR-29-3p 家族促进 RANKL 诱导的骨吸收，但目前的工作表明 miR-29-3p 抑制 TNF-α 诱导的破骨细胞生成，表明 miR-29-3p 在骨稳态和炎症性骨溶解中具有多效性作用。我们的数据支持这样一种概念，即 miR-29-3p 活性的敲低可以使髓细胞对炎症挑战做出反应，并可能使谱系分化向巨噬细胞倾斜，使 miR-29-3p 家族成为调节炎症反应的潜在治疗靶标。
