To assess the impact of a new anti-BMP small molecule (SM) as oral EAE treatment, studying its effects on disease disability, myelination, axonal integrity, astrogenesis, in vitro BMP signaling and pharmacokinetics

Demyelinated MS lesions contain oligodendrocyte precursor cells, but insufficient differentiation leads to nonfunctional astroglial scars. Anti-BMP therapy enhances oligodendrogenesis and remyelination. 

Different doses of a new oral anti-BMP small molecule (SM) were administered daily to EAE-induced SJL mice between days 9-38, compared to a control group (n=12 per group). Clinical signs (scored 0-5), immunohistochemical analysis (Olig2, FDGRFα, CC1, GFAP, CD45, BrdU, pSMAD), fluoromyelin (FM), and neurofilament (NF) staining were examined via confocal microscopy. In vitro, the SM's impact on BMP2,-4,-5,-7 signaling was assessed in NIH3T3 cell lines using western blot. SM pharmacokinetics was analyzed using LC-MS/MS.

Oral administration of 750 mg or 1500 mg daily of SM significantly improved EAE scores from days 14-30 (p<0.05) and reduced cumulative scores (44.7±2.9, p=0.032 and 50.3±6.6, p=0.05 respectively vs. 72.3±12.7 in the vehicle). SM lowered p-SMAD1/5/8 expression in astrocytes (15.0±4.9 vs. 43.8±4.2 cells/mm2, p=0.001) and oligodendrocytes (14.5±6.9 vs. 41.4±4.5 cells/mm2, p=0.009). It promoted pro-oligodendrocyte (26.0±2.6 vs. 2.8±2.3 cells/mm2, p<0.001) and mature oligodendrocyte numbers (25.0±5.2 vs. 5.2±2.4 cells/mm2, p=0.015), reduced astrocyte numbers (16.9±1.6 vs. 34.8±2.6 cells/mm2, p<0.001), increased FM-stained area (78.3±2.1% vs. 59.8±1.7%, p<0.001), and increased NF-stained area (90.1±3.3% vs. 62.8±2.2%, p<0.001) in the lumbar spinal cord. In vitro, SM inhibited p-SMAD, p-P38, and p-ERK1,2 expressions upon BMP5 exposure and p-P38 upon BMP2 and BMP4 exposure. Its T1/2=6 hours for both IP and oral administration, with IC50 = 1.54mM. Oral bioavailability was 68.6%.

Daily oral SM from onset has therapeutic potential for demyelinating disorders such as multiple sclerosis. It promotes remyelinization driven by oligodendrogenesis, preserves axons, by inhibiting the canonical and non-canonical signaling of BMPs with a favorable bioavailability and half-life.