High-throughput technologies have led to advances in the recognition of disease pathways and their underlying mechanisms. To investigate the impact of micro-RNAs on the disease process in
multiple sclerosis, a prototypic inflammatory
neurological disorder, we examined cerebral white matter from patients with or without the disease by
micro-RNA profiling, together with confirmatory reverse transcription-polymerase chain reaction analysis, immunoblotting and gas chromatography-mass spectrometry. These observations were verified using the in vivo
multiple sclerosis model,
experimental autoimmune encephalomyelitis. Brains of patients with or without
multiple sclerosis demonstrated differential expression of multiple micro-RNAs, but expression of three
neurosteroid synthesis
enzyme-specific micro-RNAs (miR-338, miR-155 and miR-491) showed a bias towards induction in patients with
multiple sclerosis (P < 0.05). Analysis of the neurosteroidogenic pathways targeted by micro-RNAs revealed suppression of
enzyme transcript and
protein levels in the white matter of patients with
multiple sclerosis (P < 0.05). This was confirmed by firefly/
Renilla luciferase micro-RNA target knockdown experiments (P < 0.05) and detection of specific micro-RNAs by in situ hybridization in the brains of patients with or without
multiple sclerosis. Levels of important
neurosteroids, including
allopregnanolone, were suppressed in the white matter of patients with
multiple sclerosis (P < 0.05). Induction of the murine micro-RNAs, miR-338 and miR-155, accompanied by diminished expression of neurosteroidogenic
enzymes and
allopregnanolone, was also observed in the brains of mice with
experimental autoimmune encephalomyelitis (P < 0.05).
Allopregnanolone treatment of the
experimental autoimmune encephalomyelitis mouse model limited the associated neuropathology, including
neuroinflammation, myelin and axonal injury and reduced neurobehavioral deficits (P < 0.05). These multi-platform studies point to impaired neurosteroidogenesis in both
multiple sclerosis and
experimental autoimmune encephalomyelitis. The findings also indicate that
allopregnanolone and perhaps other
neurosteroid-like compounds might represent potential
biomarkers or
therapies for
multiple sclerosis.