siRNA knockdown of ADAM-10, but not ADAM-17, significantly reduces fractalkine shedding following pro-inflammatory cytokine treatment in a human adult brain endothelial cell line

Fractalkine shedding is believed to occur constitutively and following induction via the activity of two membrane-bound enzymes, ADAM-10 and ADAM-17, respectively. However, our previous work suggested that ADAM-17 is not involved in the proteolytic release of fractalkine under TNF treatment of a human adult brain endothelial cell line, hCMEC/D3. The pro-inflammatory cytokine, TNF, has previously been shown to be expressed in the perivascular cuffs in multiple sclerosis. Here we sought to identify, using siRNAs to silence the expression of ADAM-10 and ADAM-17, whether ADAM-10 is responsible for TNF-induced shedding of fractalkine from the cell membrane in hCMEC/D3. Our findings suggest that ADAM-10, and not ADAM-17, is the major protease involved in fractalkine release under pro-inflammatory conditions in this human adult brain endothelial cell model.