[Research progress on the changes of blood-brain barrier in sepsis-associated encephalopathy]

Sepsis-associated encephalopathy (SAE) is the most common neurological complication of sepsis, with an incidence of up to 70% in sepsis, and contributes to the increased mortality and disability in sepsis. To date, the exact pathogenesis of SAE is not clear. Most of current researches indicated that blood-brain barrier (BBB) dysfunction, active neuroinflammation, glial cell over activation as well as cerebral microcirculation dysfunction contributed to the pathophysiology of SAE. BBB, as a complex cellular structure between the central nervous system and the peripheral system, strictly controls the entrance and discharge of substances and plays an important role in maintaining the balance between biochemical system and immune system of central system. During the progress of sepsis, inflammatory cytokines and reactive oxygen species resulting from peripheral system directly or indirectly resulted in the damage to the integrity and structure of BBB, which helped above species easily enter into the central system. Above these damages caused glial cell activation (microglia and astrocyte), the imbalance of neurotransmitters, mitochondrial dysfunction and neural apoptosis, which also reversely contributed to the damage to the integrity and permeability of BBB via decreasing the expression of tight junctional protein between cells. Therefore, this review focuses on the structural and functional changes of BBB in SAE, and how these changes lead to the development of SAE, in order to seek a BBB-targeted therapy for SAE.