The roles of the immune system in Women's reproduction: Evolutionary constraints and life history trade‐offs

Abstract

Life history theory posits that, as long as survival is assured, finite resources are available for reproduction, maintenance, and growth/storage. To maximize lifetime reproductive success, resources are subject to trade-offs both within individuals and between current and future investment. For women, reproducing is costly and time-consuming; the bulk of available resources must be allocated to reproduction at the expense of more flexible systems like immune function. When reproducing women contract infectious diseases, the resources required for immune activation can fundamentally shift the patterns of resource allocation. Adding to the complexity of the reproductive-immune trade-offs in women are the pleiotropic effects of many immune factors, which were modified to serve key roles in mammalian reproduction. In this review, we explore the complex intersections between immune function and female reproduction to situate proximate immunological processes within a life history framework. After a brief overview of the immune system, we discuss some important physiological roles of immune factors in women's reproduction and the conflicts that may arise when these factors must play dual roles. We then discuss the influence of reproductive-immune trade-offs on the patterning of lifetime reproductive success: (1) the effect of immune activation/infectious disease on the timing of life history events; (2) the role of the immune system, immune activation, and infectious disease on resource allocation within individual reproductive events, particularly pregnancy; and (3) the role of the immune system in shaping the offspring's patterns of future life history trade-offs. We close with a discussion of future directions in reproductive immunology for anthropologists.

Immune function in Amazonian horticulturalists

“…reduced productivity) (Stieglitz et al, 2015b). Across species, mounting an immune response decreases growth and reproduction, as resources used for immunity are not available for these competing demands (Sheldon and Verhulst, 1996; Klein and Nelson, 1999; Uller et al, 2006; Blackwell et al, 2010; Abrams and Miller, 2011). Since different aspects of immune defense have their own costs and benefits, across species natural selection will have acted on patterns of responsiveness, determining the relative proportions and strengths of responses to employ.…”

Changes in DNA Methylation from Age 18 to Pregnancy in Type 1, 2, and 17 T Helper and Regulatory T-Cells Pathway Genes

“…Immune responses have been divided into two patterns—the innate and the adaptive immune system [1,8]. The innate immune responses provide an immediate defense against pathogens, whereas the adaptive immune system reacts to specific antigens [9].…”

“…Adaptive immune responses are mediated by T and B lymphocytes. B cells and their antibodies initiate humoral immunity; T cells primarily provide cell-mediated immunity [8,10]. T cells represent a subset of T helper (CD4+) cells which have been subdivided into Th1, Th2, Th17, and regulatory T cells (Treg).…”

“…T cells represent a subset of T helper (CD4+) cells which have been subdivided into Th1, Th2, Th17, and regulatory T cells (Treg). The Th1 response is characterized by pro-inflammatory cytokines, whereas the Th2 response is anti-inflammatory [1,8]. The Th17 pathway plays an important role in inducing inflammation [11,12]; Treg cells inhibit inflammation and are responsible for immune regulation.…”

Helminth infection during pregnancy: insights from evolutionary ecology

“…Helminths and pregnancy both require nutritional and energetic resources such as iron, glucose, lipids, and other molecules critical for fetal growth and development. Organisms face trade-offs in allocating resources between competing demands, such as survival, reproduction, and somatic maintenance,24,25 and these trade-offs may be especially exacerbated by the dual demands of simultaneous helminth infection and pregnancy. Moreover, helminth infections often occur in the context of coinfection with other parasites and pathogens, such as HIV, malaria, and giardia,26 and are most prevalent in areas where resources are scarce and nutrition may be limited 1,27…”