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细胞在类风湿性关节炎（RA）（免疫）发病机制中的作用被认为是微不足道的。然而，我们的团队和其他人最近进行的研究，专注于来自RA患者或慢性多关节炎动物模型的样本中的CD8 + T细胞，已经挑战了这些教条，并表明RA中的CD8 + T细胞具有显着的促炎性细胞毒性效应表型，因此可能在RA的起始，维持和/或复发中发挥主导作用。外周血、滑液和滑膜中存在这种效应CD8 + T细胞（如其他研究小组所报告的那样）表明，它们必须适应自身代谢，以维持在氧合良好和缺氧环境中对效应功能的能量需求。在我们最近在常氧条件下对CD8 + T细胞进行的体外研究中，使用稳定同位素代谢示踪剂[U-13 C]葡萄糖，我们检测到静息状态下RA细胞的有氧糖酵解速率很高，这是通过细胞培养基中[U-13 C]乳酸水平的异常升高来测量的，并且在刺激后这些速率显著增加，这与这些细胞中糖酵解代谢的普遍性相一致，即使在充分充氧的环境中。当与来自健康对照、强直性脊柱炎（SpA）和银屑病关节炎（PsA）患者的CD8 + T细胞相比时，这些变化似乎对RA细胞具有相当特异性。因此，我们将当前提案的主要目标设定为：A）与其他慢性炎性自身免疫性关节炎患者相比，表征来自RA的CD8 + T细胞中的代谢过程; B）探索这些CD8 + T细胞代谢过程作为RA中新的诊断工具和/或治疗靶点的潜力。结合免疫学参数的定量和1H-plus 13C-NMR分析将集中于：1）与SpA、PsA、多发性硬化和健康对照相比，RA CD8 + T细胞中独特代谢指纹的鉴定和表征。2)通过MALDI-TOF成像质谱法与骨关节炎相比，浸润RA滑膜的CD 8 + T细胞的表型、功能和代谢特征。3)RA中体外调节CD8 + T细胞应答的代谢靶点的选择和验证。为了在RA小鼠模型中转移人类数据，我们计划验证自发性慢性多关节炎K/BxN小鼠模型中CD8 + T细胞的代谢指纹。我们的第一个数据提示在RA的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和创新的治疗选择。

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.