Vitamin D3 Treatment Protects Motor Neuron Cells from Oxidative Stress and ALS-Related SOD1 Mutation (P2.062)

OBJECTIVE: Study effects of 1,25-dihydroxycholecalciferol (vitamin D3) on NSC34 cells expressing either wild-type SOD1 or mutated SOD1 associated with amyotrophic lateral sclerosis (ALS), and to investigate dose-dependent effects of vitamin D3 treatment, towards establishing dosing in humans. BACKGROUND: Vitamin D3 influences distinct pathways that are potentially important in ALS physiopathology. The most studied mechanism is the up-regulation of calcium binding proteins in motor neurons, which increases calcium buffering capacity, and confers resistance to cytotoxicity in cell culture and mouse models of ALS. DESIGN/METHODS:Effects of vitamin D3 were assessed in differentiated neuroblastoma-spinal cord NSC34 cells. Familial ALS pathology was modeled in NSC34 cells transfected with mutant SOD1. Sporadic ALS etiology was represented in wild-type SOD1 transfected cells under acute oxidative stress(100 μM H2O2) with an approximate density of 1.0 x 105 cells/cm2. Dose-dependence of vitamin D3 was observed in transformed NSC34 cells with treatments of 0, 0.1, 10, and 100 nM, after six-hour exposure. Viability was assessed through increased fluorescence from glucose-6-phosphate dehydrogenase leaked from non-viable cells reacting with resazurin. Intracellular calcium levels were observed with ratiometric indicator dye fura 2-AM. RESULTS: Vitamin D3 (100 nM) rescued 30[percnt] of cells transfected with wild-type SOD1 and challenged with 100 μM H2O2 for 400 minutes (p < 0.001) and 40[percnt] of cells over-expressing toxic SOD1A4V and challenged with 100 μM H2O2 for 400 minutes (p < 0.0.001). Vitamin D3 dosing rescued viability in a dose-dependent manner. Calcium fluctuations were less dramatic in vitamin D3-treated cells, with a 37[percnt] decrease in peak measurement 400 minutes after acute H2O2 dosing (p < 0.01). CONCLUSIONS: Vitamin D3 reduced the amplitude of calcium fluctuations and delayed cell death in cells over-expressing either SOD1wt or SOD1A4V mutant, with dose-dependency. Further analysis regarding the potency of vitamin D analogues and target serum vitamin D3 levels in humans will follow.