The endothelial cell receptor stabilin-2 regulates VWF-FVIII complex half-life and immunogenicity
Laura L. Swystun, … , Paula D. James, David Lillicrap
Laura L. Swystun, … , Paula D. James, David Lillicrap
Published August 20, 2018
Citation Information: J Clin Invest. 2018;128(9):4057-4073. https://doi.org/10.1172/JCI96400.
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Research Article Genetics Hematology

The endothelial cell receptor stabilin-2 regulates VWF-FVIII complex half-life and immunogenicity

Abstract

Quantitative abnormalities of the von Willebrand factor–factor VIII (VWF-FVIII) complex associate with inherited bleeding or thrombotic disorders. Receptor-mediated interactions between plasma VWF-FVIII and phagocytic or immune cells can influence their hemostatic and immunogenic activities. Genetic association studies have demonstrated that variants in the STAB2 gene, which encodes the scavenger receptor stabilin-2, associate with plasma levels of VWF-FVIII. However, the mechanistic basis and pathophysiological consequences of this association are unknown. We have demonstrated that stabilin-2–expressing cells bind and internalize human VWF and FVIII in a VWF-dependent manner, and stabilin-2–deficient mice displayed prolonged human VWF-FVIII half-life compared with controls. The stabilin-2 variant p.E2377K significantly decreased stabilin-2 expression and impaired VWF endocytosis in a heterologous expression system, and common STAB2 variants associated with plasma VWF levels in type 1 von Willebrand disease patients. STAB2-deficient mice displayed a decreased immunogenic response to human VWF-FVIII complex, while coinfusion of human VWF-FVIII with the stabilin-2 ligand hyaluronic acid attenuated the immune response to exogenous FVIII. Collectively, these data suggest that stabilin-2 functions as both a clearance and an immunoregulatory receptor for VWF-FVIII, making stabilin-2 a novel molecular target for modification of the half-life of VWF-FVIII and the immune response to VWF-FVIII concentrates.

Authors

Laura L. Swystun, Jesse D. Lai, Colleen Notley, Ilinca Georgescu, A. Simonne Paine, Jeff Mewburn, Kate Nesbitt, Kai Schledzewski, Cyrill Géraud, Julia Kzhyshkowska, Sergij Goerdt, Wilma Hopman, Robert R. Montgomery, Paula D. James, David Lillicrap

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Figure 4

Stabilin-2–expressing cells bind and internalize VWF in vivo and in vitro.

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Stabilin-2–expressing cells bind and internalize VWF in vivo and in vitr...
(A–F) The influence and association between stabilin-2 and VWF were characterized in the murine liver and spleen. (A) Association of infused human pdVWF (green) with stabilin-2–expressing cells (red) in the liver of a VWF-KO mouse (scale bar: 20 μm). (B and C) Association of human pdVWF (green) with LSECs (CD31, red) in VWF-KO (B) and VWF/STAB2 DKO (C) mice (scale bars: 100 μm). (D) Association of infused human pdVWF (green) with stabilin-2–expressing cells (red) in the murine spleen (scale bar: 20 μm). (E and F) Association of VWF (green) with splenic endothelial cells (CD31, red) in VWF-KO (E) and VWF/STAB2 DKO (F) mice (scale bars: 20 μm). All images are representative of n = 3 independent experiments. (G–L) IF of isolated VWF-KO murine LSECs cultured ex vivo. (G) Expression of CD31 (green) and stabilin-2 (red). (H–L) IF of LSECs exposed to 2 U/ml VWF and/or FVIII for 1 hour. (H) Binding of human pdVWF (hpdVWF, green) to CD31-expressing LSECs (red). (I–K) Binding of hpdVWF (I) (orthogonal view inset), human recombinant VWF (hrVWF) (J), and murine recombinant VWF (mrVWF, red) (K) to stabilin-2–expressing LSECS (red). (L) Binding of human pdFVIII (+VWF) [hpdFVIII (+VWF)] (green) to stabilin-2–expressing LSECs (red). Scale bars: 20 μm. (M–R) IF of HEK 293 cells transfected with the human and murine stabilin-2 cDNA and exposed to 2 U/ml VWF and/or FVIII for 1 hour. (M and N) Binding of hpdVWF (M, green) and hpdFVIII (+VWF) (N, green) to human stabilin-2–expressing (red) HEK 293 cells. (O) Colocalization of VWF (green) and FVIII (red) on stabilin-2–expressing HEK 293 cells. (P–R) Binding of hpdVWF (green) (P), hrVWF (green) (Q), and mrVWF (green) (R) to murine stabilin-2–expressing (red) HEK 293 cells. For all images, blue indicates DAPI; and yellow, colocalization. Scale bars: 20 μm. All images are representative of n ≥ 3 independent experiments.