Biological and Environmental Sciences, University of Stirling, Stirling, FK9 4LA, United Kingdom.
Sci Rep. 2017 Sep 5;7(1):10417. doi: 10.1038/s41598-017-11021-6.
Animal immune systems change dramatically during the ageing process, often accompanied by major increases in pathogen susceptibility. However, the extent to which senescent elevations in infection mortality are causally driven by deteriorations in canonical systemic immune processes is unclear. We studied Drosophila melanogaster and compared the relative contributions of impaired systemic immune defences and deteriorating barrier defences to increased pathogen susceptibility in aged flies. To assess senescent changes in systemic immune response efficacy we injected one and four-week old flies with the entomopathogenic fungus Beauveria bassiana and studied subsequent mortality; whereas to include the role of barrier defences we infected flies by dusting the cuticle with fungal spores. We show that the processes underlying pathogen defence senescence differ between males and females. Both sexes became more susceptible to infection as they aged. However, we conclude that for males, this was principally due to deterioration in barrier defences, whereas for females systemic immune defence senescence was mainly responsible. We discuss the potential roles of sex-specific selection on the immune system and behavioural variation between males and females in driving these different senescent trends.
动物的免疫系统在衰老过程中会发生显著变化，通常伴随着病原体易感性的大幅增加。然而，衰老导致的感染死亡率升高在多大程度上是由经典的系统性免疫过程恶化所引起的，目前还不清楚。我们研究了黑腹果蝇，并比较了系统性免疫防御受损和屏障防御恶化对老龄果蝇病原体易感性增加的相对贡献。为了评估系统性免疫反应功效的衰老变化，我们给一周龄和四周龄的果蝇注射了昆虫病原真菌球孢白僵菌，并研究了随后的死亡率；而要包括屏障防御的作用，我们通过用真菌孢子粉撒粉来感染果蝇。我们表明，病原体防御衰老的过程在雌雄果蝇之间存在差异。随着年龄的增长，两性都更容易受到感染。然而，我们得出的结论是，对于雄性来说，这主要是由于屏障防御的恶化，而对于雌性来说，系统性免疫防御的衰老主要是罪魁祸首。我们讨论了性别特异性选择和雄性和雌性之间的行为变异在驱动这些不同衰老趋势方面的潜在作用。
