The Role of Microglia in Perioperative Neurocognitive Disorders

Abstract

Perioperative neurocognitive disorder (PND) is a common phenomenon associated with anesthesia and surgery and has been frequently described in the elderly and susceptible individuals. Microglia, which are the brain's major resident immune cells, play critical roles in maintaining neuronal homeostasis and synaptic plasticity. Accumulating evidence suggests microglial dysfunction occurring after anesthesia and surgery might perturb neuronal function and induce PND. This review aims to provide an overview of the involvement of microglia in PND to date. Possible cellular and molecular mechanisms regarding the connection between microglial activation and PND are discussed.

Keywords: anesthesia; microglia; neuroinflammation; perioperative neurocognitive disorder; surgery.

Figure 1

Schematic overview of microglial mechanisms involved in perioperative neurocognitive disorder (PND). Surgery and anesthesia induce a systemic inflammatory response. The increased pro-inflammatory mediators (cytokines, chemokines, alarmins, etc.) may compromise blood-brain barrier integrity, resulting in the infiltration of peripheral cells/factors into the brain parenchyma. Microglia are activated and initiate a cascade of inflammatory events that further activate other microglia and astrocyte. These processes contribute to neuronal damage and dysfunction and perioperative neurocognitive disorder. HMGB1, high-mobility group box 1 protein; IL, interleukin; TNF, tumor necrosis factor.