Metabolism in synovial macrophages are reprogrammed by synovial fibroblasts under inflammatory condition. Metabolism in synovial macrophages are reprogrammed by synovial fibroblasts under inflammatory condition

Macrophages have plasticity to adapt microenvironment. In joint tissue, synovial macrophages (SM) and synovial fibroblasts (SF) are maintained in the homeostasis. In Rheumatoid arthritis, crosstalk between SM and SF via inflammatory response induce abnormal activation in respective cells and contribute to disease progression. However, the activation mechanisms in SM which are encouraged by SF are largely unclear. Here, we demonstrated metabolic reprogramming and immunological activation in SM by secretary stimulations from SF using primary culture synovial cell derived from arthritis model mice. To analyze interaction between SM and SF, primary culture of murine synovial cells was performed, respectively. RNA-seq analysis showed SF express abundant secretion-related gene. Thus, we investigated whether conditioned medium from SF (SF-CM) affects biological activity in SM. As the results, SF-CM condition induced both glycolysis and mitochondrial respiration to SM with increased uptake of glucose and glutamine at least, accompanied with cell survival. In addition, several inflammation markers were also upregulated in SM by SF-CM condition. Taken together, these results suggest that metabolic reprogramming were induced in SM by secretory stimulations from SF, followed by activated inflammatory response and long-live. These indicate that such phenotypes of SM may contribute to chronic inflammation in Rheumatoid arthritis Overall design: mRNA profiles of primary synovial macrophages and synovial fibroblasts obtained from swollen ankle in CAIA mice were generated by deep sequencing, in triplicate, using Illumina Miseq.

巨噬细胞具备适应微环境的可塑性。在关节组织中，滑膜巨噬细胞（synovial macrophages, SM）与滑膜成纤维细胞（synovial fibroblasts, SF）维持稳态。在类风湿关节炎（rheumatoid arthritis, RA）中，SM与SF通过炎症应答产生的相互作用，可诱导两类细胞发生异常活化，进而推动疾病进展。然而，SF介导SM活化的具体机制在很大程度上仍未明确。本研究利用关节炎模型小鼠的原代滑膜细胞，证实SF可通过分泌刺激诱导SM发生代谢重编程与免疫活化。为解析SM与SF之间的相互作用，我们分别对小鼠原代滑膜细胞进行了体外培养。RNA测序（RNA-seq）分析显示，SF可高表达大量分泌相关基因。据此，我们探究了SF条件培养基（SF-conditioned medium, SF-CM）是否会影响SM的生物学活性。实验结果表明，SF-CM处理可同时激活SM的糖酵解与线粒体呼吸通路，至少可促进其对葡萄糖与谷氨酰胺的摄取，并伴随细胞存活能力提升。此外，SF-CM处理还可上调SM中多种炎症标志物的表达。综上，本研究结果显示，SF的分泌刺激可诱导SM发生代谢重编程，进而激活炎症应答并延长细胞存活时长。上述结果提示，SM的此类表型可能参与类风湿关节炎的慢性炎症进程。实验整体设计：从胶原诱导性关节炎（collagen-induced arthritis, CAIA）模型小鼠肿胀踝关节中分离得到的原代滑膜巨噬细胞与滑膜成纤维细胞，采用Illumina Miseq平台进行三次生物学重复的深度测序，以获取其mRNA表达谱。