Rolling and adhesion of apoptotic monocytes is impaired by loss of functional cell surface‐expressed P‐selectin glycoprotein ligand‐1

Abstract

To cite this article: van Genderen H, Wielders SJH, Lindhout T, Reutelingsperger CPM. Rolling and adhesion of apoptotic monocytes is impaired by loss of functional cell surface-expressed P-selectin glycoprotein ligand-1. J Thromb Haemost 2006; 4: 1611-7.Summary. Background: Apoptosis induces cellular membrane changes that are thought to be linked to thrombotic processes, for example, surface exposure of procoagulant phosphatidylserine (PtdSer), upregulation of tissue factor (TF), and microvesicle formation. The latter, though, could downregulate this cellular response by shedding prothrombotic membrane elements, for example, integrins and TF. To test this hypothesis, etoposide-treated, apoptotic, monocytic cells (human monocytic leukemia cell line [THP-1]) were examined for rolling and adhesion on adherent platelets and for TF expression. Methods and results: Etoposide treatment did not result in a significant change in TF antigen expression. However, TF activity, measured in a continuous factor Xa generation assay, was increased fivefold concomitantly with increased exposure of PtdSer. Laminar flow adhesion assays specific for interaction between P-selectin and P-selectin glycoprotein ligand-1 (PSGL-1) revealed that in contrast to non-treated cells, apoptotic cells did not roll or firmly attach on adherent platelets. Lack of apoptotic THP-1 platelet interaction could be attributed to both a loss of cell surface-expressed PSGL-1 and loss of functional PSGL-1 as a result of disruption of the binding of PSGL-1 with the cytoskeleton. Conclusion: Etoposide-induced apoptosis in THP-1 cells evokes a procoagulant response by increasing TF activity associated with an increased PtdSer exposure. However, in contrast to TF, PSGL-1 shedding and loss of function, makes that apoptotic monocytes are unlikely involved in a thrombotic action because of their inability to adhere to an injured vessel wall or developing thrombus.

Novel insights into the inhibitory effects of Galectin-1 on neutrophil recruitment under flow

“…The mechanism responsible for PSGL-1 shedding is distinct from that of L-selectin shedding [24], which may account for the differing effects on these two adhesion molecules. Although the full functional impact of PSGL-1 shedding is not clear, it has been linked to a decrease in leukocyte rolling and adhesion [24,28]. The lack of an effect on PSGL-1 shedding in naïve neutrophils suggests that this is an unlikely mechanism for Gal-1 inhibition of neutrophil rolling in the flow chamber.…”

Soluble Siglec-5 associates to PSGL-1 and displays anti-inflammatory activity

“…Perfusions were performed using THP1 cells (which express both PSGL1 and Siglec-51048) or primary leukocytes. Perfusions were performed using the VenaFlux-perfusion system (Cellix Ltd, Dublin, Ireland) or an in-house developed perfusion system49.…”

Analytical cell adhesion chromatography reveals impaired persistence of metastatic cell rolling adhesion to P-selectin

“…6E). This suggests that a biophysical mechanism underpins this metric of adhesivity, a concept supported by the lower percentage binding time (as well as a higher v avg /v inst ratio) to P-selectin exhibited by HL-60 relative to THP-1 cells despite P-selectin glycoprotein ligand-1 functioning as the predominant P-selectin ligand on both cell subtypes (Norman et al, 1995;van Genderen et al, 2006). However, the underlying mechanism of this adhesive behavior remains to be elucidated.…”