The Study On Chemotherapy Drugs And Immunosuppressants Activates Hepatitis B Virus Replication In Vitro

Background: Reactivation of hepatitis B is a common complicationhappens in patients with HBV infection who have received cytotoxicchemotherapy or immunosuppressive therapy. The symbolic sign ofreactivation of hepatitis B is the reoccurrence of HBV DNA in the serum ofcured or non-activity patients, often accompanied with inflammation activityin the liver, which could happen spontaneously but mostly occurs during orafter cytotoxic chemotherapy or immunosuppressive therapy,which couldlead to acute hepatitis, liver failure,even death. Nevertheless, most cases arenot clinically significant or not been discovered until it has developed to activehepatitis which leads to the interruption of cytotoxic chemotherapy orimmunosuppressive therapy which is bad for prognosis. Clinical observationalso suggested that under the risk of reactivation of hepatitis B usingnucleoside analogues could prevent it efficiently.Reactivation of hepatitis B started from the enhancement of HBVreplication, this phenomenon occurs shortly after cytotoxic chemotherapy orimmunosuppressive therapy, the mechanism of this phenomenon is not clearso far. Precedent study has already confirmed that glucocorticoids such asDexamethasone could activate Hepatitis B Virus replication in vitro, we alsohypothesized that whether cytotoxic chemotherapy drugs andimmunosuppressants could directly stimulate HBV to enhance HBVreplication in vitro, other than their immunosuppression.Objective: To observe whether cytotoxic chemotherapy drugs andimmunosuppressants can directly stimulate the replication and expression ofHBV in vitro. Methods:1Using the Dexamethasone as positive control and employing theHepG2.2.15cells as vitro replicating model to eliminate related immunefactors, using Native Western blot and Native Southern blot to test the effectsof chemotherapy drugs, such as Epirubicin, Mitomycin,5-Fluorouracil, andimmunosuppressants, such as leflunomide, mycophenolic acid, on replicationand expression of HBV.2Our lab has successfully constructed cells HepG2HBV-secNluc, whichwas stably transfected by the replication-competent HBV viral vectors withtracer, this cell line can secret HBV particles with carrying luciferase reportgenes. Treating HepG2HBV-secNluc with cytotoxic chemotherapy drugs,such as Epirubicin, Mitomycin,5-Fluorouracil, and immunosuppre-ssants,such as Leflunomide, Mycophenolic acid, and glucocorticoids such asDexamethasone, testing the changes of secretory luciferase in the cellsupernament.3Using Native Southern blot to observe whether Lamivudine can inhibitthe activation of HBV replication induced by cytotoxic chemotherapy drugs,such as Epirubicin, Mitomycin,5-Fluorouracil, and immunosuppre-ssants,such as Leflunomide, Mycophenolic acid, Dexamethasone.Results:1The result of Native Western blot and Native Southern blot: followedby the increasing concentration of cytotoxic chemotherapy drugs, such asEpirubicin, Mitomycin,5-Fluorouracil, and immunosuppressants, such asLeflunomide, Mycophenolic acid，Dexamethasone, are the increasing of thereplication and expression of HBV.2Luciferase analysis: Epirubicin, Mitomycin,5-Fluorouracil, A771726,Mycophenolic acid and Dexamethasone could improve the expression level ofluciferase in HepG2HBV-secNluc cell. The differences among eachconcentrations are of statistical significance (p<0.05).3Lamivudine can inhibit the activation of HBV replication induced byEpirubicin, Mitomycin,5-Fluorouracil, leflunomide, mycophenolic acid and Dexamethasone.Conclusions: Cytotoxic chemotherapy drugs and immunosuppressantshave the effects of stimulating HBV to enhance replication besides theirimmunosuppressive effects with could be inhibited by Nucleoside analogues.The cells HepG2HBV-secNluc, which our lab has already successfullyconstructed, is a simple model that could be used as anti-viral drugs screening.