Social history and exposure to pathogen signals modulate social status effects on gene regulation in rhesus macaques.

Social experience is an important predictor of disease susceptibility and survival in humans and other social mammals. Chronic social stress is thought to generate a proinflammatory state characterized by elevated antibacterial defenses and reduced investment in antiviral defense. Here we manipulated long-term social status in female rhesus macaques to show that social subordination alters the gene expression response to ex vivo bacterial and viral challenge. As predicted by current models, bacterial lipopolysaccharide polarizes the immune response such that low status corresponds to higher expression of genes in NF-κB-dependent proinflammatory pathways and lower expression of genes involved in the antiviral response and type I IFN signaling. Counter to predictions, however, low status drives more exaggerated expression of both NF-κB- and IFN-associated genes after cells are exposed to the viral mimic Gardiquimod. Status-driven gene expression patterns are linked not only to social status at the time of sampling, but also to social history (i.e., past social status), especially in unstimulated cells. However, for a subset of genes, we observed interaction effects in which females who fell in rank were more strongly affected by current social status than those who climbed the social hierarchy. Taken together, our results indicate that the effects of social status on immune cell gene expression depend on pathogen exposure, pathogen type, and social history-in support of social experience-mediated biological embedding in adulthood, even in the conventionally memory-less innate immune system.

Social processes and disease in nonhuman primates: introduction to the special section.

Most nonhuman primate species are remarkably social, but their social nature presents many challenges, including increased opportunities for pathogen transmission and development of disease (both physical and psychological). An interdisciplinary symposium was convened at the 2010 annual meeting of the American Society of Primatologists on the topic of social processes and disease in nonhuman primates, and four articles from that session, as well as a fifth that was separately solicited, appear in this special section. The articles reflect a variety of disciplines and perspectives that highlight the many ways that social processes can impact disease processes (and vice versa) in this highly social taxon. This is an increasingly active area of research interest as a consequence of technological developments and the availability of long-term field data. The continuing loss of primate habitat in the wild, climate change, and the need to manage high densities of primates in captivity, however, all add urgency to our need to better understand the bidirectional relationship between social factors and disease processes.

Self-harm in laboratory-housed primates: where is the evidence that the Animal Welfare Act amendment has worked?

The 1985 amendment to the United States Animal Welfare Act (AWA) to promote psychological well being of primates in the laboratory represents an acknowledgment of an important welfare problem concerning nonhuman animals. How effective has this amendment been? Perhaps the best-known contributor to psychological distress in primates in the laboratory is nonsocial housing; yet, available analyses suggest that little progress has been made in avoiding single-caging of these animals. Another way to assess psychological well being is to examine rates of self-abusive behavior in laboratory primates. If the AWA has been effective, then post-AWA self-harm rates might be lower than pre-AWA rates. However, when we attempted to determine those rates from published studies, data were too sparse to allow a rigorous statistical analysis; of 139 studies reporting primate self-harming behavior, only 9 contained data allowing estimation of self-harming behavior rates. We conclude that the current system of laboratory animal care and record keeping is inadequate to properly assess AWA impacts on primate psychological well being and that more is required to ensure the psychological well being of primates.