Bile salt–dependent lipase interacts with platelet CXCR4 and modulates thrombus formation in mice and humans
Laurence Panicot-Dubois, … , Dominique Lombardo, Christophe Dubois
Laurence Panicot-Dubois, … , Dominique Lombardo, Christophe Dubois
Published November 21, 2007
Citation Information: J Clin Invest. 2007;117(12):3708-3719. https://doi.org/10.1172/JCI32655.
View: Text | PDF
Research Article Hematology

Bile salt–dependent lipase interacts with platelet CXCR4 and modulates thrombus formation in mice and humans

Abstract

Bile salt–dependent lipase (BSDL) is an enzyme involved in the duodenal hydrolysis and absorption of cholesteryl esters. Although some BSDL is transported to blood, the role of circulating BSDL is unknown. Here, we demonstrate that BSDL is stored in platelets and released upon platelet activation. Because BSDL contains a region that is structurally homologous to the V3 loop of HIV-1, which binds to CXC chemokine receptor 4 (CXCR4), we hypothesized that BSDL might bind to CXCR4 present on platelets. In human platelets in vitro, both BSDL and a peptide corresponding to its V3-like loop induced calcium mobilization and enhanced thrombin-mediated platelet aggregation, spreading, and activated αIIbβ3 levels. These effects were abolished by CXCR4 inhibition. BSDL also increased the production of prostacyclin by human endothelial cells. In a mouse thrombosis model, BSDL accumulated at sites of vessel wall injury. When CXCR4 was antagonized, the accumulation of BSDL was inhibited and thrombus size was reduced. In BSDL–/– mice, calcium mobilization in platelets and thrombus formation were attenuated and tail bleeding times were increased in comparison with those of wild-type mice. We conclude that BSDL plays a role in optimal platelet activation and thrombus formation by interacting with CXCR4 on platelets.

Authors

Laurence Panicot-Dubois, Grace M. Thomas, Barbara C. Furie, Bruce Furie, Dominique Lombardo, Christophe Dubois

×

Figure 2

Effect of BSDL or V3-like loop peptides on platelet spreading and platelet activation.

Options: View larger image (or click on image) Download as PowerPoint
Effect of BSDL or V3-like loop peptides on platelet spreading and platel...
(A) Spreading of resting or thrombin-activated platelets treated with BSDL. Platelets were fluorescently labeled with Alexa Fluor 647–conjugated anti-mouse CD41 Fab fragment. Original magnification, ×600. (B) The mean fluorescence intensity of 15 representative microscopic fields of spread platelets at 3 time points after activation and addition of BSDL was calculated. White bars, resting platelets; black bars, resting platelets in the presence of hBSDL; light gray bars, thrombin-activated platelets; dark gray bars, thrombin-activated platelets in the presence of hBSDL. **P < 0.001. (C) Fluorescence intensity of PAC-1 FITC-labeled antibodies (directed against activated αIIbβ3) bound to resting or thrombin-activated platelets in the presence or absence of human BSDL (5 μg), V3 peptide (1 μg), V3Lscr peptide (1 μg), or V3Lsal peptide (1 μg) (n = 9; **P < 0.001). (D) Platelets were loaded with 3 μM fura-2/AM for 30 minutes at 37°C. Intracellular Ca2+ levels were monitored as the ratio of fluorescence emission intensity at 510 nm after excitation at 340 to that after excitation at 380 nm as described in Methods. Platelets were stimulated with 0.1 U/ml thrombin, 0.5 μg BSDL in the absence or presence of the blocking anti-CXCR4 antibody 12G5, or 0.1 μg/ml of V3 peptide.