A drug that is being developed to treat multiple sclerosis (MS) by damping down the immune system may also have the potential to treat viral infections. A study published in the journal, Nature, showed that mice treated with the drug FTY-720 (fingolimod) were able to clear a viral meningitis infection that persisted in untreated mice.
It is, at first sight, surprising that a drug developed to suppress the immune response in MS patients can help to fight a viral infection.
FTY720-P is an agonist of the sphingosine-1-phosphate receptor and causes lymphopenia by preventing egress of lymphocytes from the lymph nodes. The new finding builds on the observation that more easily cleared strains of the virus also cause lymphocytes to become sequestered in lymph nodes. The reason why trapping circulating lymphocytes allows a more robust response to infection is not clear, but may be linked to the fact the lymph nodes are where the immune response is primed. Clearance of the virus does not occur when CD4 T cells are absent at the time of treatment, indicating that the drug is not exerting direct antiviral effects. Some viruses, including HIV, replicate at high levels in lymph nodes and the team plan to test the effect of FTY720 on infection with other viruses.
FTY720 is currently in Phase III clinical trials to test its safety and efficacy as a disease modifying therapy for relapsing-remitting MS.