Friebe Daniela, Yang Tao, Schmidt Timo, Borg Nadine, Steckel Bodo, Ding Zhaoping, Schrader Jürgen
Department of Molecular Cardiology, Heinrich-Heine-University Düsseldorf, Düsseldorf, Germany.
Department of Molecular Cardiology, Heinrich-Heine-University Düsseldorf, Düsseldorf, Germany; Department of Anesthesiology and Intensive Care Medicine, Changhai Hospital, Second Military Medical University, Shanghai, PR China.
PLoS One. 2014 Apr 18;9(4):e95382. doi: 10.1371/journal.pone.0095382. eCollection 2014.
Extracellular nucleotides and nucleosides have been implicated as important signaling molecules in the pathogenesis of acute lung injury (ALI). While adenosine is known to inhibit T cell activation, little information is available as to ATP and NAD degrading enzymes, the expression of ATP and adenosine receptors/transporters in different T cell subsets. ALI was induced by challenging mice with intra-tracheal instillation of 60 µl (3 µg/g) LPS. After 3 d and 7 d blood, lung tissue and bronchoalveolar lavage was collected and immune cells were analyzed using flow cytometry. The transcriptional phenotype of T helper cells, cytotoxic and regulatory T cells sorted by FACS was assessed by measuring the expression profile of 28 genes related to purinergic signaling using TaqMan Array Micro Fluidic Cards. Catabolism of ATP, NAD and cAMP by activated CD4+ T cells was evaluated by HPLC. CD73 was found to be highly abundant on lymphoid cells with little abundance on myeloid cells, while the opposite was true for CD39. After ALI, the abundance of CD39 and CD73 significantly increased on all T cell subsets derived from lung tissue and bronchoalveolar space. Expression analysis in T cell subsets of the lung revealed ATP (Cd39, Cd73) and NAD (Cd38, Cd157, Cd296, Pc-1) degrading enzymes. However, only transcription of Cd38, Cd39, Cd73, Ent1 and A2a receptor was significantly upregulated after ALI in T helper cells. CD4+ T cells from injured lung rapidly metabolized extracellular ATP to AMP and adenosine but not NAD or cAMP. These findings show that lung T cells--the dominant cell fraction in the later phase of ALI--exhibit a unique expression pattern of purinergic signaling molecules. Adenosine is formed by T cells at an enhanced rate from ATP but not from NAD and together with upregulated A2a receptor is likely to modulate the healing process after acute lung injury.
细胞外核苷酸和核苷被认为是急性肺损伤（ALI）发病机制中的重要信号分子。虽然已知腺苷可抑制T细胞活化，但关于ATP和NAD降解酶以及不同T细胞亚群中ATP和腺苷受体/转运体的表达情况，目前所知甚少。通过气管内滴注60 μl（3 μg/g）脂多糖（LPS）刺激小鼠诱导ALI。3天和7天后，采集血液、肺组织和支气管肺泡灌洗液，并用流式细胞术分析免疫细胞。通过使用TaqMan Array微流控芯片测量28个与嘌呤能信号相关基因的表达谱，评估通过荧光激活细胞分选术（FACS）分选的辅助性T细胞、细胞毒性T细胞和调节性T细胞的转录表型。通过高效液相色谱法（HPLC）评估活化的CD4⁺ T细胞对ATP、NAD和cAMP的分解代谢。发现CD73在淋巴细胞上高度丰富，而在髓细胞上含量很少，而CD39则相反。ALI后，肺组织和支气管肺泡间隙来源的所有T细胞亚群上CD39和CD73的丰度显著增加。肺T细胞亚群的表达分析显示存在ATP（Cd39、Cd73）和NAD（Cd38、Cd157、Cd296、Pc-1）降解酶。然而，ALI后仅辅助性T细胞中Cd38、Cd39、Cd73、Ent1和A2a受体的转录显著上调。来自受损肺的CD4⁺ T细胞迅速将细胞外ATP代谢为AMP和腺苷，但不代谢NAD或cAMP。这些发现表明，肺T细胞（ALI后期的主要细胞成分）表现出嘌呤能信号分子的独特表达模式。腺苷由T细胞以更快的速率从ATP而非NAD形成，并且与上调的A2a受体一起可能调节急性肺损伤后的愈合过程。
