Interestingly, in the case of EBV, we found that teriflunomide can inhibit lytic EBV DNA replication through more than one mechanism, and through on-target and off-target effects. This latter effect appears to be at least partially due to an on-target effect of the drug, since late viral protein expression is partially rescued by uridine. Perhaps the most striking finding in this study is our demonstration that clinically relevant doses of teriflunomide are quite effective for inhibiting the growth of EBV-transformed B cells in two different mouse models for EBV-LPD.
In a cord-blood humanized mouse model where EBV-infected B cells and human T cells are co-engrafted, teriflunomide treatment starting 4 days after injection of cells did not prevent the engraftment of EBV-infected B cells or human T cells, but did block the ability of the EBV-infected B cells to form large invasive lymphomas. This result is particularly notable, since we have previously shown that human T cells inhibit the growth of the EBV-infected B cells in this model. In addition, in a xenograft model for EBV-LPD, even when teriflunomide therapy was delayed until 8 days after LCL injection into mice at which point small tumors were already palpable, and could also be visualized by luciferin scanning; Figure 6 , the drug still greatly inhibited the growth of the LCL-induced lymphomas.
In this xenograft model, only the ability of teriflunomide to inhibit proliferation of latently-infected EBV-positive B cells contributes to its anti-tumor effect, since EBV cannot infect mouse cells, and all injected LCLs at the start of the experiment were already EBV-infected. In summary, our investigations here, using both in vitro as well as in vivo systems to model the effects of the FDA-approved leflunomide metabolite teriflunomide on latent and lytic EBV B-cell infection, suggest that these drugs may be surprisingly effective for treating both latent and lytic EBV infection in humans.
Nevertheless, these drugs might also be useful in rare cases of fulminant infectious mononucleosis, in which the clinical symptoms are due not only to uncontrolled proliferation of virally-infected B cells, but excessive T cell activation in response to the EBV-infected B cells.
A strength of our work is its demonstration that teriflunomide inhibits spontaneous lymphomagenesis in a human cord blood model of LPD. Limitations of our studies include the examination of only one cell line in xenografts, and the relatively short duration of the teriflunomide treatment in both mouse models. Long-term studies of the effect of leflunomide treatment on LCL growth in our animal models would help determine whether lymphomas become resistant to treatment.
We constructed a recombinant M81 strain with constitutive luciferase activity B by introducing a luciferase gene pGL4. The final DMSO concentration in control and treatment groups was 0.
Cells treated with teriflunomide in Figure 1A were given fresh drug every 24 hours. Cells were counted using trypan blue exclusion Figure 1A or relative cell titers were determined using Cell Titer Glo as instructed by the manufacturer Promega; Figure 1B. D4 LCLs were treated for 7 days with 6. Growing D4 LCLs were expanded into fresh medium supplemented with drugs as needed. The following reagents were added one hour after teriflunomide treatment to induce lytic EBV reactivation: DMSO-treated wells required expansion on day 2. The following primary anti-human antibodies were used: The secondary antibodies used were horseradish peroxidase HRP -labeled goat anti-mouse antibody Thermo Fisher Scientific, 1: Beta-actin was used as a housekeeping gene, and transcripts were quantified using the delta-delta Cq methods for each time point.
Intracellular DNA from 10 6 treated Mutu I cells treatments as indicated in the Figure legend was harvested, purified, and quantified as described [ 60 ]. The light produced by the luciferase was quantified using Living Image software PerkinElmer. Infectious viral particles were produced from cell lines stably infected with the M81 virus [ 56 ] or the MLuc virus following transfection with EBV BZLF1 and GP expression vectors as previously described [ 62 ].
Cord blood was initially exposed to the virus in vitro for 1. Mice were euthanized on day 35 Experiment 1 or 28 Experiment 2. Tumor size was quantitated by dissecting and weighing grossly visible tumor tissue. Following euthanasia of EBV-infected humanized mice, multiple different organs including the lungs, spleen, pancreas, liver, gall bladder, and mesenteric fat were formalin fixed.
Epstein-Barr Virus and Human Disease * 1988
For tumor formation comparison, the p value was calculated using a two-tailed Fisher exact test. The epidemiology of EBV and its association with malignant disease.
Biology, Therapy, and Immunoprophylaxis. Cambridge University Press; [cited Dec 9]. N Engl J Med. The Epstein-Barr virus lytic program is controlled by the co-operative functions of two transactivators. Posttransplant lymphoproliferative disease following liver transplantation. Curr Opin Organ Transplant. Epstein-barr virus-infected resting memory B cells, not proliferating lymphoblasts, accumulate in the peripheral blood of immunosuppressed patients. Prevention and preemptive therapy of postransplant lymphoproliferative disease in pediatric liver recipients.
Efficacy and safety of valganciclovir in liver-transplanted children infected with Epstein-Barr virus. Tse E, Kwong YL. Epstein Barr virus-associated lymphoproliferative diseases: Clinical pharmacokinetics of leflunomide. Chacko B, John GT. Leflunomide therapy for BK virus allograft nephropathy after pediatric kidney transplantation. Teriflunomide for multiple sclerosis. Cochrane Database Syst Rev. Importance of ribonucleotide availability to proliferating T-lymphocytes from healthy humans.
Disproportionate expansion of pyrimidine pools and contrasting effects of de novo synthesis inhibitors. Targeting the hexosamine biosynthetic pathway and O-linked N-acetylglucosamine cycling for therapeutic and imaging capabilities in diffuse large B-cell lymphoma. The immunosuppressive metabolite of leflunomide, A77 , affects murine T cells through two biochemical mechanisms. In vitro and in vivo antitumor activity of a novel immunomodulatory drug, leflunomide: Novel mechanism of inhibition of cytomegalovirus by the experimental immunosuppressive agent leflunomide.
Leflunomide induces apoptosis in fludarabine-resistant and clinically refractory CLL cells. Case Studies in Microbiology Linda Young. I Contain Multitudes Ed Yong. Microbiology Flash Cards Sahar Nissim. Candida Albicans Leon Chaitow.
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Membrane Fluidity Arnisa Kuksis. Retroviruses and Human Pathology Oliviero E. Macromolecular Biorecognition Emilia Chiancone. The Epstein-Barr virus EBV , isolated in , continues to draw worldwide attention as an important human pathogen. Its impor- tance is largely related to the continuing accumulation of evidence that implicates EBV as an etiological factor for certain types of human cancer. More recent investigations on this virus have focused on the identity of the viral genes responsible for the different disease mani- festations observed following viral infection.
It is hoped that by thorough investigation of this virus, clues to how cancer develops from a normal cell will surface.