Beirne Christopher, Delahay Richard, Hares Michelle, Young Andrew
Centre for Ecology and Conservation, College of Life and Environmental Sciences, University of Exeter, Penryn Campus, Cornwall, United Kingdom.
National Wildlife Management Centre, Animal Health and Veterinary Laboratories Agency, Woodchester Park, Nympsfield, Gloucestershire, United Kingdom.
PLoS One. 2014 Sep 30;9(9):e108964. doi: 10.1371/journal.pone.0108964. eCollection 2014.
Immunosenescence, the deterioration of immune system capability with age, may play a key role in mediating age-related declines in whole-organism performance, but the mechanisms that underpin immunosenescence are poorly understood. Biomedical research on humans and laboratory models has documented age and disease related declines in the telomere lengths of leukocytes ('immune cells'), stimulating interest their having a potentially general role in the emergence of immunosenescent phenotypes. However, it is unknown whether such observations generalise to the immune cell populations of wild vertebrates living under ecologically realistic conditions. Here we examine longitudinal changes in the mean telomere lengths of immune cells in wild European badgers (Meles meles). Our findings provide the first evidence of within-individual age-related declines in immune cell telomere lengths in a wild vertebrate. That the rate of age-related decline in telomere length appears to be steeper within individuals than at the overall population level raises the possibility that individuals with short immune cell telomeres and/or higher rates of immune cell telomere attrition may be selectively lost from this population. We also report evidence suggestive of associations between immune cell telomere length and bovine tuberculosis infection status, with individuals detected at the most advanced stage of infection tending to have shorter immune cell telomeres than disease positive individuals. While male European badgers are larger and show higher rates of annual mortality than females, we found no evidence of a sex difference in either mean telomere length or the average rate of within-individual telomere attrition with age. Our findings lend support to the view that age-related declines in the telomere lengths of immune cells may provide one potentially general mechanism underpinning age-related declines in immunocompetence in natural populations.
免疫衰老，即免疫系统功能随年龄增长而衰退，可能在介导与年龄相关的整体生物体性能下降中起关键作用，但免疫衰老背后的机制却知之甚少。对人类和实验室模型的生物医学研究记录了白细胞（“免疫细胞”）端粒长度与年龄和疾病相关的下降，引发了人们对其在免疫衰老表型出现中可能具有普遍作用的兴趣。然而，尚不清楚这些观察结果是否适用于生活在生态现实条件下的野生脊椎动物的免疫细胞群体。在这里，我们研究了野生欧洲獾（Meles meles）免疫细胞平均端粒长度的纵向变化。我们的研究结果首次证明了野生脊椎动物个体内免疫细胞端粒长度与年龄相关的下降。端粒长度与年龄相关的下降速率在个体内似乎比在总体种群水平上更陡峭，这增加了免疫细胞端粒短和/或免疫细胞端粒磨损率高的个体可能从该种群中被选择性淘汰的可能性。我们还报告了证据表明免疫细胞端粒长度与牛结核病感染状况之间存在关联，处于感染最晚期的个体往往比疾病呈阳性的个体具有更短的免疫细胞端粒。虽然雄性欧洲獾体型更大，年死亡率高于雌性，但我们没有发现平均端粒长度或个体内端粒随年龄磨损的平均速率存在性别差异的证据。我们的研究结果支持了这样一种观点，即免疫细胞端粒长度与年龄相关的下降可能是自然种群中免疫能力与年龄相关下降的一种潜在普遍机制。
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