Enterovirus 71 Induces Exosome Secretion To Promote The Permeability Of Brain Microvascular Endothelial Cells

Enterovirus 71(Enterovirus 71,EV71)is a member of the species human enterovirus,belonging to picornaviridae family.It is one of the main pathogens causing hand-foot-and-mouth disease(HFMD)in infants.Most patients have mild symptoms,but some can develop severe central neural system(CNS)diseases,such as aseptic meningitis and acute flaccid paralysis and even death.EV71 can infect infants or young children worldwide and may cause serious neurological diseases,the neurotropic characteristics of EV71 is highly concerned.Previous studies reveal that the infection of target cells with various viruses,including enteroviruses,can induce the production of exosomes.Exosome is a kind of extracellular vesicle with a diameter of 30-150 nm,carrying nucleic acids and proteins for cell communications and material exchange in different micro-environments and organs.The secretion of exosomes plays an important role in the life cycle of enterovirus infection and the host immune response.However,the mechanism underlying that EV71 induces exosomes by infecting peripheral cells,thereby promoting the permeability of the blood-brain-barrier(BBB)remains elusive.In this study,we applied an established in vitro model of BBB in transwell device with Brain microvascular endothelial cells(BMEC),the main component of BBB.In this system,BMECs were co-cultured with EV71-infected colon cancer cells(HT29)or rhabdomyosarcoma cells(RD),and then subjected to transepithelial electrical resistance(TEER)detection.The TEER values were obviously reduced,suggesting the promotion of BMEC permeability.In further analysis of the expression of cell adhesion factors in BMECs,we found that the supernatant of EV71-infected HT29 or RD directly promoted the permeability of BMEC instead of EV71 alone.To determine whether the increase of BMEC permeability was mediated by EV71-induced exosomes,the exosomes derived from the supernatants of HT29 and RD cells infected with EV71 were extracted and identified.The neutralization of antibody against exosomes,gradient augment of exosomes,and small molecule inhibitor of exosomes further separately confirmed that EV71-induced exosomes could significantly increase the permeability of BMEC cells.Based on this,we proposed that exosomes induced by EV71-infected peripheral cells mediate the invasion and injury of CNS.Here,we uncover a novel mechanism by which EV71 enhances the permeability of the BMEC via inducing the production of exosomes by infecting peripheral cells.Our study reveals a new manner of EV71 invasion into the CNS,which provides a theoretical basis and clinical value for the prevention and treatment of neurological diseases upon EV71 infection.