Reactivation of latent Epstein-Barr virus by methotrexate: a potential contributor to methotrexate-associated lymphomas.
BACKGROUND
Patients with rheumatoid arthritis or polymyositis treated with methotrexate (MTX) develop Epstein-Barr virus (EBV)-positive lymphomas more frequently than patients treated with other, equally immunosuppressive regimens. Here we determined whether MTX, in contrast to other commonly used medications for rheumatoid arthritis or polymyositis, is unique in its ability to induce the release of infectious EBV from latently infected cells.


METHODS
The effect of MTX and other immunosuppressant drugs on EBV replication in vitro was assessed using latently infected EBV-positive lymphoblastoid and gastric carcinoma cell lines. Inhibitors of signal transduction pathways were used to define requirements for induction of lytic infection. Drug effects on transcription of the two EBV immediate-early promoters (BRLF1 and BZLF1) and on promoter constructs lacking cis-acting sequences required for activation by other effectors was examined using reporter gene assays. EBV viral load in rheumatoid arthritis and polymyositis patients receiving MTX was compared with that in patients receiving other immunosuppressive medications. Statistical tests were two-sided.


RESULTS
MTX activated the release of infectious EBV from latently infected cell lines in vitro, and MTX treatment was associated with activation of the two viral immediate-early promoters in reporter gene assays. Induction of lytic EBV infection by MTX required the p38 MAP kinase, PI3 kinase, and MEK pathways and specific cis-acting motifs in the two viral immediate-early promoters. Patients treated with MTX-containing regimens had statistically significantly higher mean EBV loads in their blood than patients treated with immunosuppressing regimens that did not include MTX (40 EBV copies per 10(6) cellular genomes versus 5.1 copies; geometric mean fold difference in copies = 10.8, 95%, confidence interval = 3.0 to 38; P = .011).


CONCLUSIONS
MTX may promote EBV-positive lymphomas in rheumatoid arthritis and polymyositis patients by its immunosuppressive properties as well as by reactivating latent EBV.
Feng
Wen-hai
WH
Department of Medicine and Microbiology and Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill 27599-7295, USA.
Cohen
Jeffrey I
JI
Fischer
Steven
S
Li
Li
L
Sneller
Michael
M
Goldbach-Mansky
Raphael
R
Raab-Traub
Nancy
N
Delecluse
Henri-Jacques
HJ
Kenney
Shannon C
SC
D001172:Arthritis, Rheumatoid / Q000188:drug therapy; D045744:Cell Line, Tumor; D004279:DNA, Viral / Q000032:analysis / Q000187:drug effects*; D020031:Epstein-Barr Virus Infections / Q000150:complications / Q000175:diagnosis; D015972:Gene Expression Regulation, Neoplastic; D015967:Gene Expression Regulation, Viral / Q000187:drug effects*; D004854:Herpesvirus 4, Human / Q000187:drug effects* / Q000235:genetics; D006801:Humans; D007166:Immunosuppressive Agents / Q000008:administration & dosage / Q000009:adverse effects*; D008223:Lymphoma / Q000821:virology*; D020930:MAP Kinase Kinase Kinases / Q000378:metabolism; D008727:Methotrexate / Q000008:administration & dosage / Q000009:adverse effects*; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D016133:Polymerase Chain Reaction; D017285:Polymyositis / Q000188:drug therapy; D011401:Promoter Regions, Genetic; D015398:Signal Transduction / Q000187:drug effects; D019562:Viral Load; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism
D004279:DNA, Viral; D007166:Immunosuppressive Agents; D019869:Phosphatidylinositol 3-Kinases; D048051:p38 Mitogen-Activated Protein Kinases; D020930:MAP Kinase Kinase Kinases; D008727:Methotrexate