Interferon-beta affects mitochondrial activity in CD4+ lymphocytes: Implications for mechanism of action in multiple sclerosis.

BACKGROUND: Whereas cellular immune function depends on energy supply and mitochondrial function, little is known on the impact of immunotherapies on cellular energy metabolism. OBJECTIVE: The objective of this paper is to assess the effects of interferon-beta (IFN-ß) on mitochondrial function of CD4(+) T cells. METHODS: Intracellular adenosine triphosphate (iATP) in phytohemagglutinin (PHA)-stimulated CD4(+) cells of multiple sclerosis (MS) patients treated with IFN-ß and controls were analyzed in a luciferase-based assay. Mitochondrial-transmembrane potential (ΔΨm) in IFN-ß-treated peripheral blood mononuclear cells (PBMCs) was investigated by flow cytometry. Expression of genes involved in mitochondrial oxidative phosphorylation (OXPHOS) in CD4(+) cells of IFN-ß-treated individuals and correlations between genetic variants in the key metabolism regulator PGC-1α and IFN-ß response in MS were analyzed. RESULTS: IFN-ß-treated MS patients exhibited a dose-dependent reduction of iATP levels in CD4(+) T cells compared to controls (p < 0.001). Mitochondrial effects were reflected by depolarization of ΔΨm. Expression data revealed changes in the transcription of OXPHOS-genes. iATP levels in IFN-ß-responders were reduced compared to non-responders (p < 0.05), and the major T allele of the SNP rs7665116 of PGC-1α correlated with iATP-levels. CONCLUSION: Reduced iATP-synthesis ex vivo and differential expression of OXPHOS-genes in CD4(+) T cells point to unknown IFN-ß effects on mitochondrial energy metabolism, adding to potential pleiotropic mechanisms of action.