SLC27A2, a critical metabolic regulator of T cellular inflammation in juvenile idiopathic arthritis and beyond?

幼年特发性关节炎（JIA）是一种起源不明的疾病，其中先天性免疫系统以及包括T细胞在内的适应性免疫系统的细胞发挥核心作用。T细胞的功能和命运决定关键取决于能量特性，包括糖酵解或氧化磷酸化。脂肪酸是氧化磷酸化最重要的能量来源之一。在我们的初步数据中，我们显示1. JIA患者滑液（SF）CD 4 + T细胞中游离脂肪酸的摄取增强，2. SLC 27 A2/FATP 2在SF CD 4 + T细胞中的表达增加。 在用抗-CD 3/CD 28刺激后，血液来源的CD 4+记忆T细胞中SLC 27 A2的表达和游离脂肪酸的摄取增强，4. 在抗-CD 3/CD 28-刺激的CD 4 + T细胞中游离脂肪酸的摄取可以用SLC 27 A2和5的特异性抑制剂lipofermata阻断。 我们的数据提供了强有力的证据表明，SLC 27 A2可能是JIA记忆T细胞增殖和炎症倾向所必需的关键脂肪酸转运蛋白。这表明SLC 27 A2是JIA和其他自身免疫性疾病的新治疗靶点。从上述数据中产生了几个问题：A）SF T细胞中脂肪酸摄取的功能后果是什么，这是否改变了细胞内的炎症线索？我们将使用质谱法鉴定SF中的脂肪酸组成，并在JIA T细胞中摄取脂肪酸后进行代谢物分析。我们将在与lipofermata孵育并用抗CD 3/CD 28刺激后对记忆T细胞和JIA SF T细胞进行RNAseq。B）T细胞分化和功能受SLC 27 A2表达影响吗？在存在/不存在脂质体以及针对SLC 27 A2的siRNA的情况下，人和鼠幼稚CD 4 T细胞将分化成Th 1/Th 2/Th 17/Treg细胞。我们将产生CD 4CRESLC 27 A2 fl/fl小鼠并分析它们的T细胞区室、代谢、转录和功能。C）JIA记忆T细胞中SLC 27 A2上调的原因是什么？ATACseq将在SF T细胞以及刺激和未刺激的记忆T细胞中进行，以破译染色质可及性并鉴定启动子/增强子区域内的转录因子结合位点。我们将在CD 4CRESLC 27 A2 fl/fl小鼠和对照中进行胶原诱导的关节炎模型以及使用脂质体作为治疗干预的T细胞介导的转移关节炎模型。 我们的项目将阐明SLC 27 A2在JIA中CD 4+记忆T细胞能量需求中的作用。如果我们的初步数据是正确的，我们将在CD 4+记忆T细胞中确定脂肪酸摄取和代谢的新概念，并有机会在炎症性疾病中特异性靶向它。

Juvenile idiopathic arthritis (JIA) is a disease of unknown origin in which cells of the innate immune system as well as of the adaptive immune system including T cells play central roles. T cellular function and fate decision critically depends on energetic properties including glycolysis or oxidative phosphorylation. Fatty acids are one of the most important sources of energy for oxidative phosphorylation. Within our preliminary data we show that1. the uptake of free fatty acids is enhanced in synovial fluid (SF) CD4+ T cells of patients with JIA, 2. the expression of SLC27A2/FATP2 is increased in SF CD4+ T cells, 3. the expression of SLC27A2 and uptake of free fatty acids is enhanced in blood derived CD4+ memory T cells after stimulation with anti-CD3/CD28, 4. the uptake of free fatty acids in anti-CD3/CD28-stimulated CD4+ T cells can be blocked with lipofermata, a specific inhibitor of SLC27A2 and5. the blockade with lipofermata inhibits T cell proliferation, IFNy production and mitochondrial respiration.Our data provide strong evidence that SLC27A2 might act as a critical fatty acid transport protein which is necessary for the proliferation and inflammatory propensities of memory T cells in JIA. This suggests that SLC27A2 is a novel therapeutic target in JIA and other autoimmune diseases. Several questions arise from the above-mentioned data:A)What are the functional consequences of fatty acid uptake in SF T cells and does this alter inflammatory cues within the cells? We will identify the fatty acid composition in SF using mass-spectrometry and perform metabolite analyzes after fatty acid uptake in JIA T cells. We will perform RNAseq of memory T cells and JIA SF T cells after incubation with lipofermata and stimulation with anti-CD3/CD28. B)Is T cell differentiation and function affected by SLC27A2 expression? Human and murine naïve CD4 T cells will be differentiated into Th1/Th2/Th17/Treg cells in the presence/absence of lipofermata as well as siRNA for SLC27A2. We will generate CD4CRESLC27A2fl/fl mice and analyze them with regard to T cell compartments, metabolism, transcriptional and function.C)What is the reason for SLC27A2 upregulation in JIA memory T cells? ATACseq will be performed in SF T cells as well as in stimulated and unstimulated memory T cells to decipher chromatin accessibility and to identify transcription factor binding sites within the promoter/enhancer regions.D)Can blockade of SLC27A2 prevent experimental arthritis? We will perform a Collagen- induced arthritis model in CD4CRESLC27A2fl/fl mice and controls as well as a T cell-mediated transfer arthritis model using lipofermata as therapeutic intervention. Our project will clarify the role of SLC27A2 for the energetic demands of CD4+ memory T cells in JIA. If our preliminary data hold true, we would have identified a novel concept of fatty acid uptake and metabolism in CD4+ memory T cells with the chance to specifically target it in inflammatory diseases.