The TASK1 channel inhibitor A293 shows efficacy in a mouse model of multiple sclerosis.

The two-pore domain potassium channel TASK1 (KCNK3) has recently emerged as an important modulator in autoimmune CNS inflammation. Previously, it was shown that T lymphocytes obtained from TASK1(-/-) mice display impaired T cell effector functions and that TASK1(-/-) mice show a significantly reduced disease severity in myelin oligodendrocyte glycoprotein (MOG(35-55)) peptide induced experimental autoimmune encephalomyelitis (EAE), an animal model of multiple sclerosis. We here evaluate a potent and specific TASK1 channel inhibitor, A293, which caused a dose-dependent reduction of T cell effector functions (cytokine production and proliferation). This effect was abolished in CD4(+) T cells from TASK1(-/-) mice but not in cells from TASK3(-/-) mice. In electrophysiological measurements, A293 application induced a significant reduction of the outward current of wildtype T lymphocytes, while there was no effect in TASK1(-/-) cells. Preventive and therapeutic application of A293 significantly ameliorated the EAE disease course in wildtype mice while it had no significant effect in TASK1(-/-) mice and was still partly effective in TASK3(-/-) mice. In summary, our findings support the concept of TASK1 as an attractive drug target for autoimmune disorders.