Vascular matrix metalloproteinase-2-dependent cleavage of calcitonin gene-related peptide promotes vasoconstriction

Matrix metalloproteinase (MMP)-2 has been historically associated with the process of vascular remodeling through the cleavage of extracellular matrix proteins. However, we recently found that MMP-2 also cleaves the endothelium-derived peptide big endothelin-l, ET-l[1-38] and yields the novel vasoconstrictor ET-l[1-32,]. We therefore investigated the effects of MMP-2 inhibitors as potential vasodilators, MMP inhibition with orthophenanthroline (0.3 to 30 mu mol/L) induced vasorelaxation of isolated rat mesenteric arteries (maximum of relaxation=74.5+/-27.6% at 30 mu mol/L). However, phosphoramidon (0.3 to 30 mu mol/L), which inhibits some metalloenzymes, but not MMP-2, did not dilate the arteries. Selective inhibition of endogenous MMP-2 with the novel tissue-permeable cyclic peptide CTTHWGFTLC (CTT, 10 mu mol/L) also caused vasorelaxation (by 85+/-6%), whereas STTHWGFTLS (10 mu mol/L), an inactive CTT analogue, did not dilate the arteries. Interestingly, the vasorelaxation that results from MMP-2 inhibition was endothelium-independent. Thus, we examined whether MMP-2 acted on peptides derived from the smooth muscle or the perivascular nerves, Recombinant human MMP-2 cleaved calcitonin gene-related peptide (CGRP) specifically at the Gly(14)-Leu(15) peptide bond and reduced the vasodilatory potency of CGRP by 20-fold. Inhibition of MMP-2 increased the amount of intact CGRP in arteries and enhanced vasorelaxation induced by anandamide, which stimulates CGRP release. Vasorelaxation in response to MMP-2 inhibition was abolished by CGRP[8-37], a selective CGRP receptor antagonist, and by capsaicin, which depletes arterial perivascular nerves of CGRP. We conclude that vascular MMP-2 cleaves endogenous CGRP and promotes vasoconstriction, These data suggest a novel mechanism of regulating the vasoactive and, possibly, the neurohormonal actions of CGRP and establish MMP-2 as a modulator of vascular function.