Research Center for Sport and Physical Activity, Faculty of Sport Sciences and Physical Education, University of Coimbra, Coimbra, Portugal.
Eur J Appl Physiol. 2013 Apr;113(4):859-68. doi: 10.1007/s00421-012-2490-x. Epub 2012 Sep 19.
Immune changes and increased susceptibility to infection are often reported in elite athletes. Infectious episodes can often impair training and performance with consequences for health and sporting success. This study monitored the occurrence of episodes of upper respiratory symptoms (URS) and the variation in circulating NK cells, CD56(bright) and CD56(dim) NK cells subpopulations, over a winter swimming season. Nineteen national elite swimmers and 11 non-athlete controls participated in this study. URS episodes were monitored using daily log books. Blood samples were taken at rest at four time points during the season: before the start of the season (t1--middle September), after 7 weeks of an initial period of gradually increasing training load (t2--early November), after 6 weeks of an intense training cycle (t3--late February) and 48 h after the main competition (t4--early April) and from the controls at three similar time points (t1--early November; t2--late February; t3--early April). In the swimmers, the occurrence of URS clustered around the periods of elevated training load (67 %). No URS were reported at equivalent time points in the non-athletes. Athletes showed a decrease in the percentage (t2 = 21 %; t3 = 27 %; t4 = 17 %) and absolute counts of circulating NK cells (t2 = 35 %; t3 = 22 %; t4 = 22 %), coinciding with the periods of increased training load, never recovering to the initial values observed at the start of the season. The reduction in the CD56(dim) and an increase in the CD56(bright) NK cell subpopulations were significant at t2 and t3 (p < 0.05). Concomitant with the fall in values of NK cells, in athletes that shown more than three URS episodes, a moderate correlation (r = 0.493; p = 0.036) was found between CD56(bright)/CD56(dim) ratio and the number of URS episodes after the more demanding training phase (t3). At t3, a lower value of CD56 cell counts was found in the group who reported three or more URS episodes (t = 2.239; p = 0.032). A progressive significant decrease in the expression of CD119, the receptor for IFN-γ, on the CD56(dim) cells was found over the season and an elevation in Granzyme B expression was coincident with the more demanding training phases. Periods of highly demanding training seem to have a negative impact on innate immunity mediated by NK cell subsets, which could partially explain the higher frequency of URS observed during these training phases.
精英运动员常报告免疫改变和易感染。感染发作常可影响训练和运动表现，对健康和运动成绩产生影响。本研究监测了冬季游泳赛季中，上呼吸道症状（URS）发作和循环自然杀伤（NK）细胞、CD56（bright）和 CD56（dim）NK 细胞亚群变化的发生情况。19 名国家精英游泳运动员和 11 名非运动员对照参加了这项研究。使用每日日志本监测 URS 发作。在赛季的四个时间点在休息时采集血样：赛季开始前（t1-9 月中旬）、最初逐渐增加训练负荷 7 周后（t2-11 月初）、剧烈训练周期 6 周后（t3-2 月底）和主要比赛后 48 小时（t4-4 月初），并从对照中在三个类似的时间点采集血样（t1-11 月初；t2-2 月底；t3-4 月初）。在运动员中，URS 的发生集中在训练负荷增加的时期（67%）。非运动员在相应时间点没有报告 URS。运动员的循环 NK 细胞百分比（t2=21%；t3=27%；t4=17%）和绝对计数（t2=35%；t3=22%；t4=22%）下降，与训练负荷增加时期一致，从未恢复到赛季开始时观察到的初始值。CD56（dim）减少和 CD56（bright）NK 细胞亚群增加在 t2 和 t3 时显著（p<0.05）。与 NK 细胞值下降同时，在显示超过三个 URS 发作的运动员中，在更具挑战性的训练阶段（t3）后，CD56（bright）/CD56（dim）比值与 URS 发作次数之间发现中度相关性（r=0.493；p=0.036）。在 t3 时，报告三个或更多 URS 发作的组发现 CD56 细胞计数较低（t=2.239；p=0.032）。在整个赛季中，发现 CD56（dim）细胞上 IFN-γ受体 CD119 的表达呈进行性显著下降，而颗粒酶 B 的表达升高与更具挑战性的训练阶段一致。高要求的训练阶段似乎对 NK 细胞亚群介导的固有免疫产生负面影响，这可以部分解释在这些训练阶段观察到的 URS 更高频率。
