Inflammation: Mechanisms, Costs, and Natural Variation

Inflammation is a pervasive phenomenon that operates during severe perturbations of homeostasis, such as infection, injury, and exposure to contaminants, and is triggered by innate immune receptors that recognize pathogens and damaged cells. Among vertebrates, the inflammatory cascade is a complex network of immunological, physiological, and behavioral events that are coordinated by cytokines, immune signaling molecules. Although the molecular basis of inflammation is well studied, its role in mediating the outcome of host-parasite interactions has received minimal attention by ecologists. This review provides a synopsis of vertebrate inflammation, its life-history modulation, and its effects upon host-pathogen dynamics as well as host-commensal microbiota interactions in the gut. What emerges is evidence for phenotypic plasticity of inflammatory responses despite the apparently invariant and redundant nature of the immunoregulatory networks that regulate them.