[Basic mechanisms of action of fingolimod in relation to multiple sclerosis]
Fingolimod has recently been approved for the therapy of relapsing multiple sclerosis. This drug binds to different sphingosine-1-phosphate receptors. To analyze basic mechanisms of action that can account for the efficacy of this drug in multiple sclerosis. Fingolimod acts as an inverse agonist on sphingosine-1-phosphate receptors, inducing degradation of receptors. On lymphoid circulation, this effect causes retention in lymph nodes of naive and central memory T cells, including Th17 T lymphocytes, bearing CCR7 and CD62L receptors. As a result, the level of circulating T cells is markedly decreased. B ell circulation is impaired and complex effects on other immune cells are also induced. Fingolimod enters the central nervous system and binds to receptors on glial cells and neurons. In experimental autoimmune encephalomyelitis, the therapeutic efficacy of fingolimod is not only associated with a reduced entry of inflammatory cells into the nervous system, but also with a direct effect mostly on astroglial cells. In multiple sclerosis patients, the available evidence indicates that fingolimod efficacy is directly associated with impairment of circulation of several T cell subsets and possibly B cells. Animal studies raise the possibility that an additional effect on glial cells might also contribute to the clinical efficacy.