Investigating the immunological and life history consequences of early life adversity

Schneider-Crease India, Durham NC

Investigators

Abstract

This award was provided as part of NSF's Social, Behavioral and Economic Sciences Postdoctoral Research Fellowships (SPRF) program. The goal of the SPRF program is to prepare promising, early career doctoral-level scientists for scientific careers in academia, industry or private sector, and government. SPRF awards involve two years of training under the sponsorship of established scientists and encourage Postdoctoral Fellows to perform independent research. NSF seeks to promote the participation of scientists from all segments of the scientific community, including those from underrepresented groups, in its research programs and activities; the postdoctoral period is considered to be an important level of professional development in attaining this goal. Each Postdoctoral Fellow must address important scientific questions that advance their respective disciplinary fields. This postdoctoral fellowship award supports a rising scholar in the investigation of how early life adversity triggers trade-offs in immunological development in a nonhuman primate model, the gelada. Trauma during infancy, the most vulnerable period of life, affects both immediate and long-term health. The negative consequences of adversity during early life may arise, in part, from tradeoffs that occur when limited resources are preferentially allocated to the most important developmental processes. One such tradeoff is thought to be between investment in the two primary components of the immune system: the innate and acquired immune responses. Innate immunity is thought to be energetically cheap relative to acquired immunity; thus, adversity in early life is expected to stimulate increased investment in innate immunity. The prioritization of innate immunity and the de-prioritization of acquired immunity may facilitate the immediate survival of infants exposed to early life adversity, but may also make these infants more vulnerable to certain diseases in adulthood. Understanding the link between early life adversity and immune development is thus central to endeavors to protect the health of vulnerable populations. Geladas are an exceptional model species for this investigation because some infants are exposed to early life adversity in the form of attacks from adult males during infanticide attempts. This research fills critical gaps in the current understanding of the mechanisms and evolution of human social experience and health, and thus provides information that is imperative to efforts to mediate the consequences of childhood adversity. Furthermore, this fellowship comes at an exciting time in the development of powerful tools in genomics and eco-immunology that can be applied in studies of wild populations. The funded research thus plays an important role in advancing the use of these techniques for research on both human and non-human animal populations. Early life adversity plays an essential role in shaping the trajectory of survival, health, and reproductive success in adulthood. The long-lasting consequences of early life adversity may be due to trade-offs between physiologically costly processes - often a zero-sum game in the face of limited resources. The two arms of the immune response are prime candidates for trade-offs given that immunity is both costly and necessary for survival, and such trade-offs are expected to affect the ability of organisms to effectively combat pathogens. Organisms may therefore react to adversity by prioritizing the development of one component of the immune system at the expense of another. The innate immune response, which acts as a generalized "first-responder" to pathogens, is hypothesized to carry lower costs than the acquired immune response, which acts in long-term pathogen recognition and combat. Cues of adversity are thus expected to stimulate increased investment in innate immunity relative to acquired immunity. The present research investigates the impact of early life adversity on immunological development in geladas. Two characteristics of geladas (Theropithecus gelada) make them an excellent system in which to examine how early life adversity affects immune activation and disease susceptibility: (1) A high percentage of infants experience early life adversity in the form of the threat of infanticide from new immigrant males, which should select for adaptive plasticity in infants that allows them to preferentially allocate energetic resources to enhance immediate survival; (2) Geladas are infected by two sets of pathogens, each of which triggers distinct immune activity. The present study addresses two questions in this system: (1) Are there tradeoffs between innate and acquired immunity for infants that experience early life adversity? and (2) What are the long-term consequences of immunological tradeoffs during development? This research takes an interdisciplinary approach to answering these questions, using novel tools in eco-immunology and genomics to non-invasively quantify immune activation and disease risk in geladas under long-term study in the wild. These health data will be paired with longitudinal life history data to evaluate the impact of adversity in early life on immunological development and adult health and fitness. By quantifying variation in components of health, immune function, and reproductive success in these geladas, this research examines the evolutionary basis of the physiological consequences of early life adversity.