Moir Hannah, Hughes Michael G, Potter Stephen, Sims Craig, Butcher Lee R, Davies Nia A, Verheggen Kenneth, Jones Kenneth P, Thomas Andrew W, Webb Richard
Cardiff School of Health Sciences, University of Wales Institute, Cardiff CF5 2YB, UK.
J Appl Physiol (1985). 2010 May;108(5):1284-92. doi: 10.1152/japplphysiol.00737.2009. Epub 2010 Feb 18.
We previously proposed 5'-AMP-activated protein kinase (AMPK) dephosphorylation within immune cells as an intracellular mechanism linking exercise and immunosuppression. In this study, AMPK phosphorylation underwent transient (<1 h) decreases (53.8+/-7.2% basal) immediately after exercise (45 min of cycling at 70% VO2max) in a cohort of 16 adult male participants. Similar effects were seen with running. However, because exercise-induced inactivation of AMPK was previously shown to occur in an AMP-independent manner, the means by which AMPK is inactivated in this context is not yet clear. To investigate the hypothesis that exercise-induced inactivation of AMPK is mediated via signaling mechanisms distinct from changes in cellular AMP-to-ATP ratios, reactive oxygen species (ROS) and intracellular Ca2+ signaling were investigated in mononuclear cells before and after exercise and in cultured monocytic MM6 cells. In in vitro studies, treatment with an antioxidant (ascorbic acid, 4 h, 50 microM) decreased MM6 cell intracellular ROS levels (88.0+/-5.2% basal) and induced dephosphorylation of AMPK (44.7+/-17.6% basal). By analogy, the fact that exercise decreased mononuclear cell ROS content (32.8+/-16.6% basal), possibly due to downregulation (43.4+/-8.0% basal) of mRNA for NOX2, the catalytic subunit of the cytoplasmic ROS-generating enzyme NADPH oxidase, may provide an explanation for the AMPK-dephosphorylating effect of exercise. In contrast, exercise-induced Ca2+ signaling events did not seem to be coupled to changes in AMPK activity. Thus we propose that the exercise-induced decreases in both intracellular ROS and AMPK phosphorylation seen in this study constitute evidence supporting a role for ROS in controlling AMPK, and hence immune function, in the context of exercise-induced immunosuppression.
我们之前提出，免疫细胞内5'-AMP激活的蛋白激酶（AMPK）去磷酸化是一种将运动与免疫抑制联系起来的细胞内机制。在本研究中，16名成年男性参与者在进行运动（以70%最大摄氧量进行45分钟骑行）后，AMPK磷酸化立即出现短暂（<1小时）下降（降至基础水平的53.8±7.2%）。跑步时也观察到类似效果。然而，由于之前已证明运动诱导的AMPK失活是以不依赖AMP的方式发生的，因此在这种情况下AMPK失活的方式尚不清楚。为了研究运动诱导的AMPK失活是通过不同于细胞内AMP与ATP比值变化的信号机制介导的这一假设，我们在运动前后的单核细胞以及培养的单核细胞系MM6细胞中研究了活性氧（ROS）和细胞内Ca2+信号传导。在体外研究中，用抗氧化剂（抗坏血酸，4小时，50微摩尔）处理可降低MM6细胞内ROS水平（降至基础水平的88.0±5.2%）并诱导AMPK去磷酸化（降至基础水平的44.7±17.6%）。类似地，运动可能通过下调细胞质ROS生成酶NADPH氧化酶的催化亚基NOX2的mRNA（降至基础水平的43.4±8.0%），从而降低单核细胞ROS含量（降至基础水平的32.8±16.6%），这可能为运动对AMPK的去磷酸化作用提供了解释。相比之下，运动诱导的Ca2+信号事件似乎与AMPK活性的变化无关。因此，我们提出，本研究中观察到的运动诱导的细胞内ROS和AMPK磷酸化水平降低，构成了支持ROS在运动诱导的免疫抑制背景下控制AMPK进而影响免疫功能的证据。
