Microglia: Neuroimmune-sensors of stress

Abstract

Exposure to stressors disrupts homeostasis and results in the release of stress hormones including glucocorticoids, epinepherine and norepinepherine. Interestingly, stress also has profound affects on microglia, which are tissue-resident macrophages in the brain parenchyma. Microglia express a diverse array of receptors, which also allows them to respond to stress hormones derived from peripheral as well as central sources. Here, we review studies of how exposure to acute and chronic stressors alters the immunophenotype and function of microglia. Further, we examine a causal for stress hormones in these effects of stress on microglia. We propose that microglia serve as immunosensors of the stress response, which puts them in the unique position to sense and respond rapidly to alterations in homeostasis and integrate the neural response to threats.

Keywords: Innate immunity; Microglia; Neuroinflammation; Stress.

Figure 1.

Microglia as immunosensors of the stress response. Acute and chronic stressors induce a spectrum of alterations in microglia function and immunophenotype. These alterations are mediated, in part, via stress hormones/transmitters including GCs and NE. We propose that, given the diverse functional capacity of microglia, these innate immune cells serve as immunosensors of perturbations in homeostasis, which allows them to respond to a spectrum of peripherally and centrally derived signals. In doing so, microglia play a pivotal role in shaping the neural and thus the behavioral response to stress in threat appraisal regions in the brain.