Role of CD40 and ADAMTS13 in von Willebrand factor-mediated endothelial cell–platelet–monocyte interaction

Abstract

Monocyte extravasation into the vessel wall is a key step in atherogenesis. It is still elusive how monocytes transmigrate through the endothelial cell (EC) monolayer at atherosclerosis predilection sites. Platelets tethered to ultra-large von Willebrand factor (ULVWF) multimers deposited on the luminal EC surface following CD40 ligand (CD154) stimulation may facilitate monocyte diapedesis. Human ECs grown in a parallel plate flow chamber for live-cell imaging or Transwell permeable supports for transmigration assay were exposed to fluid or orbital shear stress and CD154. Human isolated platelets and/or monocytes were superfused over or added on top of the EC monolayer. Plasma levels and activity of the ULVWF multimer-cleaving protease ADAMTS13 were compared between coronary artery disease (CAD) patients and controls and were verified by the bioassay. Two-photon intravital microscopy was performed to monitor CD154-dependent leukocyte recruitment in the cremaster microcirculation of ADAMTS13-deficient versus wild-type mice. CD154-induced ULVWF multimer-platelet string formation on the EC surface trapped monocytes and facilitated transmigration through the EC monolayer despite high shear stress. Two-photon intravital microscopy revealed CD154-induced ULVWF multimer-platelet string formation preferentially in venules, due to strong EC expression of CD40, causing prominent downstream leukocyte extravasation. Plasma ADAMTS13 abundance and activity were significantly reduced in CAD patients and strongly facilitated both ULVWF multimer-platelet string formation and monocyte trapping in vitro. Moderate ADAMTS13 deficiency in CAD patients augments CD154-mediated deposition of platelet-decorated ULVWF multimers on the luminal EC surface, reinforcing the trapping of circulating monocytes at atherosclerosis predilection sites and promoting their diapedesis.

Von Willebrand factor and cancer; metastasis and coagulopathies

“… 47 For example, a number of independent studies have reported that leukocytes bind directly to VWF through β 2‐integrins and P‐selectin glycoprotein ligand‐1 (PSGL‐1) under conditions of shear stress. Work by Bernardo et al and Popa et al revealed that platelet‐decorated UL‐VWF multimers, secreted from activated ECs, facilitate the adhesion and transendothelial migration of leukocytes under high shear stress 48,49 . Taken together these results clearly demonstrate that VWF serves as an adhesive surface on activated ECs to tether and sequester leukocytes.…”

Novel Approaches to Fine-Tune Therapeutic Targeting of Platelets in Atherosclerosis: A Critical Appraisal

“…20 After binding and activation of endothelial CD40 by CD40L, ultralarge VWF-platelet strings arise and facilitate monocyte diapedesis. 21 In conjunction with a reduced activity of ADAMTS13, which cleaves ultralarge VWF, and consequently higher amounts of ultralarge VWF in plasma of patients with CAD, this mechanism has been proposed to contribute to enhanced monocyte recruitment at atherosclerotic predilection sites. 21 Elevated VWF levels in humans are strongly associated with an increased risk of ischemic cardiovascular events.…”

“…21 In conjunction with a reduced activity of ADAMTS13, which cleaves ultralarge VWF, and consequently higher amounts of ultralarge VWF in plasma of patients with CAD, this mechanism has been proposed to contribute to enhanced monocyte recruitment at atherosclerotic predilection sites. 21 Elevated VWF levels in humans are strongly associated with an increased risk of ischemic cardiovascular events. Whether this relation is causal or whether increased VWF levels just reflect disturbances of endothelial function remains to be elucidated.…”

Whole Blood Based Multiparameter Assessment of Thrombus Formation in Standard Microfluidic Devices to Proxy In Vivo Haemostasis and Thrombosis

“…When establishing an in vitro endothelial model system, the choice of the cell line is important. Most frequently used in microfluidic studies are human umbilical vein endothelial cells (HUVEC) [54,55,56,57,58,59,60,61,62]. As essentially primary cells, when applied at low passage numbers, HUVEC-covered surfaces have served to study several aspects of vascular function, with as advantages a high experimental reproducibility and a lack of contamination of non-endothelial cells.…”

“…For instance, BOEC derived from patients with type 3 von Willebrand disease (a congenital deficiency in endothelial-derived VWF expression) appeared to be dysfunctional in the release of large VWF multimers that capture platelets under flow conditions [68]. An approach to use HUVEC in a clinically relevant manner is by subjecting these to blood or plasma samples with a reduction in ADAMTS-13 (which cleaves and inactivates the ultra-large VWF multimers), obtained from patients with coronary artery disease [60]. A particular observation was that, under flow, the recruitment of monocytes to adhered platelets is enforced by an endothelial release of large VWF multimers, a process that is exacerbated by a moderate ADAMT-13 deficiency.…”