Follicular helper T cells express a metabolic and cell signaling gene signature in a lupus-prone murine model

Systemic lupus erythematosus (SLE) is an autoimmune disease in which autoreactive follicular helper T (Tfh) cells license high-affinity autoantibody production. Strikingly, the frequency of circulating Tfh is correlated with disease activity in SLE patients. As such, understanding the molecular mechanisms responsible for the aberrant Tfh cell generation and activation in lupus is of fundamental significance. We previously demonstrated that expanded Tfh cells in the B6.Sle1.Sle2.Sle3 (TC for triple congenic) lupus model exhibit high glycolysis and oxidative metabolism, which can be constrained by inhibiting glycolysis with 2-deoxyglucose (2DG). We performed RNA-seq analyses of splenic Tfh and naïve CD4+ T cells (Tn) comparing between TC and B6 mice. First, data revealed a large number of shared gene signatures in Tfh and Tn comparing between TC and B6 group, implicating that the aberrant development of Tfh initiates as early as Tn state. Further alignment of the Tfh transcriptome obtained from RNA-seq and earlier microarray assays demonstrated concerted alterations in numerous gene signatures of overactivation of T cells including dysregulated tyrosine kinase signaling and MAPK signaling pathways. Gene set enrichment analyses (GSEA) further revealed altered metabolic pathways (e.g., oxidative phosphorylation and pyruvate metabolism) among splenic TC Tfh cells. Overall design: Splenic CD4+CD44+CD162lo/-PD-1+ Tfh cells and CD4+CD44- Tn cells from B6.NZM-Sle1NZM2410/AegSle2NZM2410/AegSle3NZM2410/Aeg/LmoJ (TC) congenic mice and B6 control at the matched ages of 8 months old were sorted for RNA-seq analysis.

系统性红斑狼疮（Systemic lupus erythematosus, SLE）是一种自身免疫性疾病，患者体内自身反应性滤泡辅助性T（follicular helper T, Tfh）细胞可介导高亲和力自身抗体的产生。值得关注的是，循环Tfh细胞的频率与SLE患者的疾病活动度呈显著相关。因此，阐明狼疮中Tfh细胞异常生成与活化的分子机制具有重要的基础研究价值。我们此前的研究证实，在B6.Sle1.Sle2.Sle3（TC，即三基因嵌合型）狼疮模型中，扩增的Tfh细胞呈现高水平糖酵解与氧化代谢特征，且该代谢表型可通过2-脱氧葡萄糖（2-deoxyglucose, 2DG）抑制糖酵解加以阻断。我们对TC小鼠与B6小鼠的脾脏Tfh细胞及初始CD4+T细胞（naïve CD4+ T cells, Tn）开展了RNA测序分析。首先，相较于B6对照组，TC组的Tfh细胞与Tn细胞存在大量共有的基因特征谱，这提示Tfh细胞的异常发育早在Tn细胞阶段就已启动。进一步将本次RNA测序获得的Tfh细胞转录组与此前的基因芯片检测结果进行比对，发现二者在诸多T细胞过度活化相关的基因特征谱上存在协同改变，包括酪氨酸激酶信号通路失调及丝裂原活化蛋白激酶（MAPK）信号通路异常。基因集富集分析（Gene set enrichment analyses, GSEA）进一步揭示，TC小鼠脾脏Tfh细胞中存在代谢通路的异常改变，例如氧化磷酸化与丙酮酸代谢通路。整体实验设计：将8月龄匹配年龄的B6.NZM-Sle1NZM2410/AegSle2NZM2410/AegSle3NZM2410/Aeg/LmoJ（TC）嵌合小鼠与B6对照小鼠的脾脏CD4+CD44+CD162低表达/阴性PD-1+ Tfh细胞及CD4+CD44- Tn细胞进行分选，随后开展RNA测序分析。