The Mechanism Of HMGB1 Involved In Central Nervous System Invasion And Blood-brain Barrier Disruption During Japanese Encephalitis Virus Infection

Japanese encephalitis virus(JEV),a mosquito-borne zoonotic pathogen,is the main causative agent of Japanese encephalitis(JE).Infection with JEV leads to neuroinflammation and BBB(Blood-brain barrier,BBB)breakdown,causing permanent neurological sequelae.The mechanisms of JEV central nervous system(CNS)invasion and the blood-brain barrier disruption are still unclear.The infiltration of immune cells into the CNS may facilitate to viral clearance,however,it may facilitate the dissemination of JEV in the brain.JEV infection induced the release of HMGB1 from brain microvascular endothelial cells(BMECs),promoting leukocytes-endothelium adhesion and leukocytes transmigration,and exacerbating BBB disruption during JEV infection.EGFP-JEV was used to track JEV-carried immune cells transmigration on BBB monolayer model in vitro,which mimics the process of viral neuroinfection.The presence of virus-carrying immune cells in the CNS promoted viral intracerebral dissemination,led to the acceleration onset of JE,and illustrated that the“Trojan horse”pathway is involved in JEV neuroinvasion.As an important component of the BBB,astrocytes are closely associated with the stability of the BBB.JEV infection induced the translocation of HMGB1 in astrocytes,and promoted the release of HMGB1.We also found that astrocytes are not the only source of HMGB1 in the CNS.Extracellular HMGB1 acts as a DAMP positively feedback regulating the HMGB1 production in astrocytes.It was also found that HMGB1 is involved in the increase of BBB doublelayer model permeability,whereas HMGB1 knockout(Crispr-Cas9)slows down the BBB disruption.Extracellular HMGB1 caused an increase of intercellular Ca2~+in astrocytes,inducing Ca M upregulation and Ca MKII phosphorylation,promoting membrane translocation of AQP4,involving in the process of HMGB1-induced BBB disruption.In conclusion,JEV infection induced HMGB1 release from the BMECs,contributed leukocytes-endothelium adhesion,promoted JEV-infected leukocytes transmigration.JEV-carried leukocytes acted as"Trojan horses",promoting viral brain dissemination and accelerating the timing of JE onset.The JEV that have invaded the CNS induced the activation of astrocytes and the secretion of HMGB.HMGB1brought on an increase of intracellular Ca2~+in astrocytes,promoting AQP4subcellular translocation,involving in the disruption of the BBB.Elucidating the roles of HMGB1 in JEV neuroinvasion and BBB disruption,might reveal potential therapeutic targets for the treatment of JE.