TNF Induction of NF-κB RelB Enhances RANKL-Induced Osteoclastogenesis by Promoting Inflammatory Macrophage Differentiation but also Limits It through Suppression of NFATc1 Expression.
TNF Induction of NF-κB RelB Enhances RANKL-Induced Osteoclastogenesis by Promoting Inflammatory Macrophage Differentiation but also Limits It through Suppression of NFATc1 Expression.
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TNF 诱导 NF-κB RelB 通过促进炎症巨噬细胞分化来增强 RANKL 诱导的破骨细胞生成，但也通过抑制 NFATc1 表达来限制它
DOI：
10.1371/journal.pone.0135728
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发表时间：
2015
期刊：
影响因子：
3.7
通讯作者：
Yao Z
中科院分区：
文献类型：
--
作者：
Zhao Z;Hou X;Yin X;Li Y;Duan R;Boyce BF;Yao Z
TNF通过直接或间接促进破骨细胞的形成而引起常见骨疾病中的骨丢失，但它也通过诱导NF-κB p100的表达而限制破骨细胞的形成。破骨细胞前体（OCP）来源于M1（炎性）和M2（驻留）巨噬细胞。然而，目前尚不清楚TNF是否通过调节M1或M2分化刺激或限制破骨细胞形成，或者是否涉及p100的伴侣RelB。为了研究这些问题，我们用M-CSF单独或与TNF组合处理骨髓细胞（BMCs）以富集OCPs，我们分别将其称为M-OCPs和T-OCPs。我们发现，TNF将CD 11b +F4/80+ M-OCP从Ly 6C-Gr 1- M2转换为Ly 6C + Gr 1-CD 11 c+和Ly 6C-Gr 1-CD 11 c + M1细胞。RANKL诱导Ly 6C + Gr 1-和Ly 6C-Gr 1-T-OCP形成破骨细胞，但仅诱导Ly 6C + Gr 1-M-OCP形成破骨细胞，其形成的破骨细胞显著少于T-OCP。重要的是，与Ly 6C-Gr 1-细胞相比，来自M-和T-OCP的Ly 6C + Gr 1-细胞的M1标志物基因、iNOS、TNF、IL-1β和TGFβ1的表达增加，来自T-OCP的Ly 6C-Gr 1-细胞的iNOS和TGFβ1的表达也增加。RANKL和TNF均增加RelB mRNA表达。TNF显著增加RelB蛋白水平，但RANKL没有，因为它也诱导RelB蛋白酶体降解。TNF抑制RANKL诱导的M-OCP的NFATc 1 mRNA表达和破骨细胞形成，但不抑制T-OCP，也不诱导RelB-/-BMC的Ly 6C + Gr 1-CD 11 c+或Ly 6C-Gr 1-CD 11 c + M1巨噬细胞。此外，M-OCP中RelB的过表达减少了RANKL诱导的破骨细胞形成和NFATc 1 mRNA表达，但增加了TNF诱导的OC形成，而不影响NFATc 1水平。因此，TNF诱导RelB直接介导不依赖于NFATc 1的终末破骨细胞分化，并通过抑制NFATc 1活化限制RANKL诱导的破骨细胞生成。然而，TNF的主要作用是通过将M-CSF诱导的M2巨噬细胞分化为具有增强的破骨细胞形成潜力的M1巨噬细胞来扩大OCP池。降解RelB的策略可以阻止TNF诱导的M2/M1转换，减少破骨细胞的形成。
TNF induces bone loss in common bone diseases by promoting osteoclast formation directly and indirectly, but it also limits osteoclast formation by inducing expression of NF-κB p100. Osteoclast precursors (OCPs) are derived from M1 (inflammatory) and M2 (resident) macrophages. However, it is not known if TNF stimulates or limits osteoclast formation through regulation of M1 or M2 differentiation or if RelB, a partner of p100, is involved. To investigate these questions, we treated bone marrow cells (BMCs) with M-CSF alone or in combination with TNF to enrich for OCPs, which we called M-OCPs and T-OCPs, respectively. We found that TNF switched CD11b+F4/80+ M-OCPs from Ly6C-Gr1- M2 to Ly6C+Gr1-CD11c+ and Ly6C-Gr1-CD11c+ M1 cells. RANKL induced osteoclast formation from both Ly6C+Gr1- and Ly6C-Gr1- T-OCPs, but only from Ly6C+Gr1- M-OCPs, which formed significantly fewer osteoclasts than T-OCPs. Importantly, Ly6C+Gr1- cells from both M- and T-OCPs have increased expression of the M1 marker genes, iNOS, TNF, IL-1β and TGFβ1, compared to Ly6C-Gr1- cells, and Ly6C-Gr1- cells from T-OCPs also have increased expression of iNOS and TGFβ1 compared to cells from M-OCPs. Both RANKL and TNF increased RelB mRNA expression. TNF significantly increased RelB protein levels, but RANKL did not because it also induced RelB proteasomal degradation. TNF inhibited RANKL-induced NFATc1 mRNA expression and osteoclast formation from M-OCPs, but not from T-OCPs, and it did not induce Ly6C+Gr1-CD11c+ or Ly6C-Gr1-CD11c+ M1 macrophages from RelB-/- BMCs. Furthermore, overexpression of RelB in M-OCPs reduced RANKL-induced osteoclast formation and NFATc1 mRNA expression, but it increased TNF-induced OC formation without affecting NFATc1 levels. Thus, TNF induction of RelB directly mediates terminal osteoclast differentiation independent of NFATc1 and limits RANKL-induced osteoclastogenesis by inhibiting NFATc1 activation. However, the dominant role of TNF is to expand the OCP pool by switching the differentiation of M-CSF-induced M2 to M1 macrophages with enhanced osteoclast forming potential. Strategies to degrade RelB could prevent TNF-induced M2/M1 switching and reduce osteoclast formation.