digoxin and Multiple-Sclerosis

The transcription factor retinoid-related orphan receptor gamma t (RORγt) has emerged as an exciting target for inflammatory diseases. Xiao et al. (2014) show that a new class of RORγt antagonists can inhibit the inflammatory function of T helper 17 cells without altering RORγt occupancy on its target genes.

Topics: Animals; Benzeneacetamides; Benzhydryl Compounds; Digoxin; Encephalomyelitis, Autoimmune, Experimental; Gene Regulatory Networks; Heterocyclic Compounds, 4 or More Rings; Humans; Multiple Sclerosis; Nuclear Receptor Subfamily 1, Group F, Member 3; T-Lymphocyte Subsets; Th17 Cells

We identified three retinoid-related orphan receptor gamma t (RORγt)-specific inhibitors that suppress T helper 17 (Th17) cell responses, including Th17-cell-mediated autoimmune disease. We systemically characterized RORγt binding in the presence and absence of drugs with corresponding whole-genome transcriptome sequencing. RORγt acts as a direct activator of Th17 cell signature genes and a direct repressor of signature genes from other T cell lineages; its strongest transcriptional effects are on cis-regulatory sites containing the RORα binding motif. RORγt is central in a densely interconnected regulatory network that shapes the balance of T cell differentiation. Here, the three inhibitors modulated the RORγt-dependent transcriptional network to varying extents and through distinct mechanisms. Whereas one inhibitor displaced RORγt from its target loci, the other two inhibitors affected transcription predominantly without removing DNA binding. Our work illustrates the power of a system-scale analysis of transcriptional regulation to characterize potential therapeutic compounds that inhibit pathogenic Th17 cells and suppress autoimmunity.

Topics: Androstenols; Animals; Benzeneacetamides; Benzhydryl Compounds; Cell Differentiation; Cell Line, Tumor; Cell Lineage; Cytokines; Digoxin; Encephalomyelitis, Autoimmune, Experimental; Gene Regulatory Networks; Heterocyclic Compounds, 4 or More Rings; Humans; Mice; Mice, Inbred C57BL; Mice, Knockout; Multiple Sclerosis; Myelin-Oligodendrocyte Glycoprotein; Nuclear Receptor Subfamily 1, Group F, Member 3; Peptide Fragments; Protein Binding; Structure-Activity Relationship; Systems Biology; T-Lymphocyte Subsets; Th17 Cells; Transcription, Genetic; Transcriptional Activation

Two substances which are products of the isoprenoid pathway, can participate in lipid peroxidation. One is digoxin, which by inhibiting membrane Na(+)-K+ ATPase, causes increase in intracellular Ca2+ and depletion of intracellular Mg2+, both effects contributing to increase in lipid peroxidation. Ubiquinone, another products of the pathway is a powerful membrane antioxidant and its deficiency can also result in defective electron transport and generation of reactive oxygen species. In view of this and also in the light of some preliminary reports on alteration in lipid peroxidation in neuropsychiatric disorders, a study was undertaken on the following aspects in some of these disorders (primary generalised epilepsy, schizophrenia, multiple sclerosis, Parkinson's disease and CNS glioma)--1) concentration of digoxin, ubiquinone, activity of HMG CoA reductase and RBC membrane Na(+)-K+ ATPase 2) activity of enzymes involved in free radical scavenging 3) parameters of lipid peroxidation and 4) antioxidant status. The result obtained indicates an increase in the concentration of digoxin and activity of HMG CoA reductase, decrease in ubiquinone levels and in the activity of membrane Na(+)-K+ ATPase. There is increased lipid peroxidation as evidenced from the increase in the concentration of MDA, conjugated dienes, hydroperoxides and NO with decreased antioxidant protection as indicated by decrease in ubiquinone, vit E and reduced glutathione in schizophrenia, Parkinson's disease and CNS glioma. The activity of enzymes involved in free radical scavenging like SOD, catalase, glutathione peroxidase and glutathione reductase is decreased in the above diseases. However, there is no evidence of any increase in lipid peroxidation in epilepsy or MS. The role of increased operation of the isoprenoid pathway as evidenced by alteration in the concentration of digoxin and ubiquinone in the generation of free radicals and protection against them in these disorders is discussed.

Topics: Central Nervous System Neoplasms; Digoxin; Epilepsy, Generalized; Free Radicals; Glioma; Humans; Lipid Peroxidation; Multiple Sclerosis; Nervous System Diseases; Parkinson Disease; Schizophrenia; Ubiquinone

Topics: Animals; Digoxin; Humans; Multiple Sclerosis

Digitalis has been shown to reverse conduction block in demyelinated nerve fibers in experimental animals. In the search for a symptomatic treatment of multiple sclerosis, digoxin (0.02 mg per kilogram of body weight) was given intravenously to 7 patients with probable or clinically definite multiple sclerosis. All of these patients had temperature-dependent symptoms. In 3 patients, improvement of clinical deficits was observed concurrent with significant changes in evoked potential findings. Digitalis derivatives may be useful in ameliorating symptoms in selected patients with multiple sclerosis.

Topics: Adult; Digoxin; Evoked Potentials; Female; Humans; Male; Middle Aged; Multiple Sclerosis; Neural Conduction; Temperature