Possible role of translocator protein 18 ku on sepsis associated encephalopathy by mediat⁃ing neuroinflammation

OBJECTIVE To clarify the role of translocator protein 18 ku(TSPO)on cecum liga⁃tion and puncture(CLP)induced sepsis associat⁃ed encephalopathy(SAE)mice,which consis⁃tently demonstrated astrocyte activation and neu⁃roinflammation.Background SAE,a brain dys⁃function,caused by systemic infection without clinical or laboratory evidence of direct infection.Most patients have symptoms such as long-term cognitive dysfunction.As the pathogenesis of SAE is very complex,neuroinflammation for SAE is one of the causes of the disease.TSPO as a marker of neuroinflammation that has the poten⁃tial to regulate neuroinflammation and SAE.METHODS The animal model of SAE was in⁃duced by CLP.TSPO ligands and TSPO knock⁃out mice were used for behavioral and molecular biology research.Survival rate of mice within 120 h on CLP mice was observed.The changes of cog⁃nitive function in mice were observed by Morris water maze and open field test.The changes of proinflammatory factors(IL-1β,TNF-α,IL-6)in hippocampus were observed by ELISA;Astro⁃cyte activation,marked by GFAP,in hippocam⁃pal was analyzed by tissue immunofluorescence and Western blotting.RESULTS Pretreatment with the TSPO ligands,XBD173 or PK11195,sig⁃nificantly improved the survival rate of CLP mice.The results of Morris water maze showed that TSPO ligands significantly increased the number of crossing the platform and the target quadrant time on CLP mice,suggesting that TSPO ligands may improve the learning and memory ability of CLP mice.Subsequent experiments revealed that TSPO ligands can reduce the inflammatory factors(IL-1β,TNF-α,IL-6)and astrocyte activa⁃tion in hippocampus of CLP mice.Similar results were also confirmed in TSPO knockout CLP mice,suggesting intervention of TSPO can reduce neuroinflammatory response and play a protec⁃tive role on SAE mice.CONCLUSION TSPO may play a critical role on SAE mice.Targeting TSPO by pharmacological means may improve the survival rate and cognitive function on CLP mice,which may through inhibiting astrocyte acti⁃vation and neuroinflammation in hippocampal.