Metabolic processes in rheumatoid arthritis CD8+T cells: exploring their diagnostic value and potential as therapeutic targets

长期以来，与CD4+T细胞或B细胞相比，CD8+T细胞在类风湿关节炎（RA）的（免疫）发病机制中的作用被认为可以忽略不计。然而，最近由我们的团队和其他人进行的研究，关注来自RA患者或慢性多发性关节炎动物模型样本的CD8+T细胞，挑战了这些教条，并表明RA中的CD8+T细胞具有显着的促炎，细胞毒性效应表型，因此可能在RA的开始，维持和/或复发中发挥重要作用。这种效应CD8+T细胞存在于外周血、滑膜液和其他研究小组报道的滑膜中，这表明它们必须调整自己的代谢，以维持在良好氧合和缺氧环境中对效应功能的能量需求。在我们最近对正常氧下CD8+T细胞的体外研究中，使用稳定的同位素代谢示踪剂[U-13C]葡萄糖，我们检测到RA细胞在静止状态下的有氧糖酵解率很高，通过细胞培养基中[U-13C]乳酸水平的异常升高来测量，并且这些速率在刺激下显着增加，这与这些细胞中糖酵解代谢的普遍存在一致，即使在良好的氧合环境中。与健康对照、强直性脊柱炎（SpA）和银屑病关节炎（PsA）患者的CD8+ T细胞相比，这些变化似乎对RA细胞具有特异性。因此，我们将当前提案的主要目标设定为：A)与其他慢性炎症性自身免疫性关节炎患者相比，RA CD8+T细胞代谢过程的表征；B)探索这些CD8+T细胞代谢过程作为RA新的诊断工具和/或治疗靶点的潜力。结合定量免疫参数和1H- + 13C-NMR分析将重点关注：1)与SpA、PsA、多发性硬化症和健康对照相比，RA CD8+T细胞中独特代谢指纹的鉴定和表征。2) MALDI-TOF成像质谱法检测RA滑膜浸润CD8+T细胞的表型、功能和代谢特征。3)体外调节RA中CD8+T细胞反应的代谢靶点的选择和验证。为了将人类数据转移到RA小鼠模型中，我们计划在自发性慢性多发性关节炎K/BxN小鼠模型中验证CD8+T细胞的代谢指纹。我们的第一个数据提示在RA动物模型中也有类似的代谢变化。然后，我们将能够在自发性慢性多发性关节炎的K/BxN小鼠模型中治疗性地调节CD8+T细胞代谢，以测试代谢的改变是否提供了一种新的创新治疗选择。

For a long time, the role of CD8+T cells in the (immuno)pathogenesis of rheumatoid arthritis (RA) was considered negligible when compared to CD4+T cells or B cells. However, recent studies carried out by our team and others, focusing on CD8+T cells from either samples from RA patients or animal models of chronic polyarthritis, have challenged those dogmas, and have shown that CD8+T cells in RA have a marked pro-inflammatory, cytotoxic effector phenotype and may, therefore, play a preponderant role in RA initiation, maintenance and/or relapse. The presence of such effector CD8+T cells in the peripheral blood, in the synovial fluid and -as reported by other teams- in the synovial membrane, suggests that they have to adapt their metabolism to sustain their energetic demands for the effector functions in both well oxygenated and in oxygen-deprived environments. In our recent in vitro studies on CD8+T cells under normoxia and using the stable isotope metabolic tracer [U-13C]glucose, we detected high rates of aerobic glycolysis in RA cells at rest, as measured by the extraordinary rise in [U-13C]lactate levels in cell culture media, and a significant increase of those rates upon stimulation, coherent with the prevalence of a glycolytic metabolism in these cells even in a well oxygenated environment. When compared to CD8+ T cells from healthy controls, ankylosing spondylitis (SpA) and psoriatic arthritis (PsA) patients, these changes seem to be rather specific for RA cells. Therefore, we have set as the main objectives of the current proposal: A) Characterization of the metabolic processes in CD8+T cells from RA comparing to other chronic inflammatory autoimmune arthritis patients; B) Explore the potential of those CD8+T cell metabolic processes as new diagnostic tool and/or therapeutic targets in RA. Combining quantification of immunological parameters and 1H- plus 13C-NMR analysis will focus on: 1) Identification and characterization of distinctive metabolic fingerprints in RA CD8+T cells, as compared to SpA, PsA, multiple sclerosis and healthy controls. 2) Phenotypic, functional and metabolic characterization of CD8+T cells infiltrating the RA synovial membrane in comparison to osteoarthritis by MALDI-TOF imaging mass spectrometry. 3) Selection and validation of metabolic targets for in vitro modulation of CD8+T cell responses in RA. In order to transfer the human data in a mouse model of RA, we have planned to validate the metabolic fingerprints from CD8+T cells in the K/BxN mouse model of spontaneous chronic polyarthritis. Our first data hint towards similar metabolic changes also in this animal model of RA. We then will be able to therapeutically modulate CD8+T cell metabolism in the K/BxN mouse model of spontaneous chronic polyarthritis to test whether alteration of metabolism offers a new and innovative therapeutic option.