Role of microglia in sepsis-associated encephalopathy pathogenesis: an update

Abstract

Sepsis-associated encephalopathy (SAE) is a serious complication of sepsis, which is characterized by cognitive dysfunction, a poor prognosis, and high incidences of morbidity and mortality. Substantial levels of systemic inflammatory factors induce neuroinflammatory responses during sepsis, ultimately disrupting the central nervous system's (CNS) homeostasis. This disruption results in brain dysfunction through various underlying mechanisms, contributing further to SAE’s development. Microglia, the most important macrophage in the CNS, can induce neuroinflammatory responses, brain tissue injury, and neuronal dysregulation, resulting in brain dysfunction. They serve an important regulatory role in CNS homeostasis and can be activated through multiple pathways. Consequently, activated microglia are involved in several pathogenic mechanisms related to SAE and play a crucial role in its development. This article discusses the role of microglia in neuroinflammation, dysfunction of neurotransmitters, disruption of the blood-brain barrier (BBB), abnormal control of cerebral blood flow, mitochondrial dysfunction, and reduction in the number of good bacteria in the gut as main pathogenic mechanisms of SAE, and focuses on studies targeting microglia to ameliorate SAE to provide a theoretical basis for targeted microglial therapy for SAE.