Early-life immune expression profiles predict later-life health and fitness in a wild rodent

Individuals differ in the nature of the immune responses they produce, affecting disease susceptibility and ultimately health and fitness. These differences have been hypothesized to have an origin in events experienced early in life that then affect trajectories of immune development and responsiveness. Here, we investigate how early-life immune expression profiles influence life history outcomes in a natural population of field voles, Microtus agrestis, in which we are able to monitor variation between and within individuals through time by repeat sampling of individually marked animals. We analysed the co-expression of 20 immune genes in early life to create a correlation network consisting of three main clusters, one of which (containing Gata3, Il10 and Il17) was associated with later-life reproductive success and susceptibility to chronic bacterial (Bartonella) infection. More detailed analyses supported associations between early-life expression of Il17 and reproductive success later in life, and of Il10 expression early in life and later infection with Bartonella. We also found significant association between an Il17 genotype and the early-life expression of Il10. Our results demonstrate that immune expression profiles can be manifested during early life with effects that persist through adulthood and that shape the variability among individuals in susceptibility to infection and fitness widely seen in natural populations.

Automated summary

Individuals vary in their immune responses, which affects their susceptibility to diseases and their overall health and fitness. These differences are thought to be influenced by early-life experiences that affect immune development. In this study, we examined how immune expression profiles in early life impact life history outcomes in a population of field voles. By analyzing the co-expression of immune genes, we found that certain clusters of genes were associated with reproductive success and susceptibility to bacterial infection later in life. Our findings highlight the long-lasting effects of early-life immune profiles on disease susceptibility and fitness in natural populations.