ARC Centre of Excellence in Cognition and its Disorders, School of Psychology, University of Western Australia, 35 Stirling Hwy, Crawley, Western Australia, 6009, Australia.
Centre for Evolutionary Biology, School of Animal Biology, University of Western Australia, 35 Stirling Hwy, Crawley, Western Australia, 6009, Australia.
Biol Rev Camb Philos Soc. 2017 Feb;92(1):551-571. doi: 10.1111/brv.12243. Epub 2016 Jan 22.
The effects of sex hormones on immune function have received much attention, especially following the proposal of the immunocompetence handicap hypothesis. Many studies, both experimental and correlational, have been conducted to test the relationship between immune function and the sex hormones testosterone in males and oestrogen in females. However, the results are mixed. We conducted four cross-species meta-analyses to investigate the relationship between sex hormones and immune function: (i) the effect of testosterone manipulation on immune function in males, (ii) the correlation between circulating testosterone level and immune function in males, (iii) the effect of oestrogen manipulation on immune function in females, and (iv) the correlation between circulating oestrogen level and immune function in females. The results from the experimental studies showed that testosterone had a medium-sized immunosuppressive effect on immune function. The effect of oestrogen, on the other hand, depended on the immune measure used. Oestrogen suppressed cell-mediated immune function while reducing parasite loads. The overall correlation (meta-analytic relationship) between circulating sex hormone level and immune function was not statistically significant for either testosterone or oestrogen despite the power of meta-analysis. These results suggest that correlational studies have limited value for testing the effects of sex hormones on immune function. We found little evidence of publication bias in the four data sets using indirect tests. There was a weak and positive relationship between year of publication and effect size for experimental studies of testosterone that became non-significant after we controlled for castration and immune measure, suggesting that the temporal trend was due to changes in these moderators over time. Graphical analyses suggest that the temporal trend was due to an increased use of cytokine measures across time. We found substantial heterogeneity in effect sizes, except in correlational studies of testosterone, even after we accounted for the relevant random and fixed factors. In conclusion, our results provide good evidence that testosterone suppresses immune function and that the effect of oestrogen varies depending on the immune measure used.
性激素对免疫功能的影响受到了广泛关注，尤其是在提出免疫能力障碍假说之后。许多实验和相关性研究都已经进行，以测试免疫功能与男性睾丸酮和女性雌激素等性激素之间的关系。然而，结果却参差不齐。我们进行了四项跨物种荟萃分析，以研究性激素与免疫功能之间的关系：（i）睾丸酮处理对男性免疫功能的影响，（ii）男性循环睾丸酮水平与免疫功能的相关性，（iii）雌激素处理对女性免疫功能的影响，以及（iv）女性循环雌激素水平与免疫功能的相关性。实验研究的结果表明，睾丸酮对免疫功能具有中等程度的免疫抑制作用。另一方面，雌激素的作用取决于所使用的免疫措施。雌激素抑制细胞介导的免疫功能，同时降低寄生虫负荷。尽管荟萃分析的功效很高，但循环性激素水平与免疫功能之间的总体相关性（荟萃分析关系）对于睾丸酮或雌激素均无统计学意义。这些结果表明，相关性研究对于测试性激素对免疫功能的影响的价值有限。我们使用间接测试在四个数据集发现几乎没有证据表明存在发表偏倚。对于睾丸酮的实验研究，发表年份与效应大小之间存在微弱的正相关关系，但在控制去势和免疫措施后，这种相关性变得不显著，这表明这种时间趋势是由于这些调节剂随时间的变化所致。图形分析表明，这种时间趋势是由于随着时间的推移，细胞因子测量的使用增加所致。我们发现，除了睾丸酮的相关性研究外，效应大小存在很大的异质性，即使在我们考虑了相关的随机和固定因素之后也是如此。总之，我们的结果提供了很好的证据，表明睾丸酮抑制免疫功能，而雌激素的作用取决于所使用的免疫措施。
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