Crosstalk between mitochondria and NOX2 in vitamin D3-induced differentiation in PLB-985 myeloid cells

To elucidate the role of reactive oxygen species (ROS) in immune enhancement, we focused on the redox signaling in vitamin D3-induced monocytic differentiation of leukemia cells. ROS generation in the cells was analyzed with ESR spin-trapping method. As a spin trap, 5,5-dimethyl-1-pyrroline-N-oxide (DMPO) was used. Human myeloid PLB-985 cells were stimulated with 200 nM vitamin D3 and/or 100 nM phorbol 12-myristate 13-acetate. Immediately after vitamin D3-stimulation, ESR-spin trapping indicated the spectrum of DMPO-OH adduct. Flow cytometry showed the expression of CD11b/Mac1–alpha in the cells incubated with vitamin D3 for three days. Diphenyleneiodonium (NOX2 inhibitor:100 uM) and actinomycin A (mitochondrial electron transport chain complex III inhibitor:10 uM) have suppressed vitamin D3-induced the expression of CD11b and ROS generation. Our results indicate that vitamin D3-induced expression of CD11b have occurred through a close interaction between NOX2 and mitochondria.