T cells reorganize their metabolic profiles after being activated, but the systemic metabolic effect of sustained activation of the immune system has remained unexplored. Here we report that augmented T cell responses in Pdcd1^-/- mice, which lack the inhibitory receptor PD-1, induced a metabolic serum signature characterized by depletion of amino acids. We found that the depletion of amino acids in serum was due to the accumulation of amino acids in activated Pdcd1^-/- T cells in the lymph nodes. A systemic decrease in tryptophan and tyrosine led to substantial deficiency in the neurotransmitters serotonin and dopamine in the brain, which resulted in behavioral changes dominated by anxiety-like behavior and exacerbated fear responses. Together these data indicate that excessive activation of T cells causes a systemic metabolomic shift with consequences that extend beyond the immune system.

中文翻译：

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PD-1缺陷小鼠中T细胞的系统活化引起的代谢转变扰乱了脑单胺和情绪行为。

T细胞在被激活后会重新组织其代谢特征，但免疫系统持续激活的全身性代谢作用尚未得到探索。在这里我们报告说，缺乏抑制受体PD-1的Pdcd1 ^-/-小鼠中增强的T细胞反应诱导了以氨基酸耗竭为特征的代谢血清特征。我们发现血清中氨基酸的消耗是由于活化的Pdcd1 ^-/-中氨基酸的积累淋巴结中的T细胞。色氨酸和酪氨酸的系统性减少导致大脑神经递质血清素和多巴胺的大量缺乏，从而导致以焦虑样行为为主的行为改变并加剧了恐惧反应。这些数据一起表明，T细胞的过度活化会导致全身代谢组学转变，其后果超出了免疫系统。