ADAMTS13 modulates atherosclerotic plaque progression in mice via a VWF-dependent mechanism.

BACKGROUND

ADAMTS13 reduces the adhesiveness of hyperactive ultra-large von Willebrand factor (ULVWF) multimers by cleaving them into smaller, less active multimers. Recently, we and others have demonstrated that ADAMTS13 reduces atherosclerosis in hypercholesteremic apolipoprotein E (ApoE-/-) deficient mice. It is not known whether ADAMTS13 modulates atherosclerosis directly or indirectly by cleaving ULVWF multimers.

OBJECTIVE

We generated triple knockout Adamts13-/-/Vwf-/-/ApoE-/- mice to determine whether ADAMTS13 modulates atherosclerosis through its proteolytic effects on VWF or other potential mechanisms.

METHODS

Female mice were fed a high-fat Western diet beginning at 6 weeks of age until they were sacrificed at 4 months. We compared the extent of atherosclerosis in the serial cross-sections of the aortic sinus using the Verhoeff-Van Gieson stain. Macrophage and neutrophil infiltration were quantified by immunohistochemistry. Under plain polarized light interstitial collagen content in the serial cross-sections of the aortic sinus was quantified using picrosirius red stain.

RESULTS

Deficiency of VWF in Adamts13-/-/ApoE-/- mice (Adamts13-/-/Vwf-/-/ApoE-/-) completely reversed exacerbated atherosclerosis (P < 0.05 vs. Adamts13-/-/ApoE-/- mice). The lesion size, macrophage and neutrophil infiltration in the aortic sinus of Adamts13-/-/Vwf-/-/ApoE-/- mice were significantly decreased compared with Adamts13-/-/ApoE-/- mice (P < 0.05), but similar to Vwf-/-/ApoE-/- mice. Additionally, interstitial collagen content in the aortic sinus of Adamts13-/-/Vwf-/-/ApoE-/- mice was significantly reduced compared with Adamts13-/-/ApoE-/- mice (P < 0.05), but similar to Vwf-/-/ApoE-/- mice. Total cholesterol and triglyceride levels were similar among groups.

CONCLUSIONS

ADAMTS13 modulates inflammatory plaque progression in hypercholesterolemic mice through a VWF-dependent mechanism. These findings provide further evidence on the pathophysiological role for the ADAMTS13/VWF axis in atherosclerosis.