Endothelial CD47 interaction with SIRPgamma is required for human T-cell transendothelial migration under shear flow
Michael Stefanidakis1, Gail Newton, Winston Y Lee
1Department of Pathology, Center for Excellence in Vascular Biology, Brigham and Women's Hospital and Harvard Medical School, Boston, MA 02115, USA.
Abstract:
Leukocyte transendothelial migration (TEM) is a critical event during inflammation. CD47 has been implicated in myeloid cell migration across endothelium and epithelium. CD47 binds to signal regulatory protein (SIRP), SIRPalpha and SIRPgamma. So far, little is known about the role of endothelial CD47 in T-cell TEM in vivo or under flow conditions in vitro. Fluorescence-activated cell sorting and biochemical analysis show that CD3(+) T cells express SIRPgamma but not SIRPalpha, and fluorescence microscopy showed that CD47 was enriched at endothelial junctions. These expression patterns suggested that CD47 plays a role in T-cell TEM through binding interactions with SIRPgamma. We tested, therefore, whether CD47-SIRPgamma interactions affect T-cell transmigration using blocking mAb against CD47 or SIRPgamma in an in vitro flow model. These antibodies inhibited T-cell TEM by 70% plus or minus 6% and 82% plus or minus 1%, respectively, but had no effect on adhesion. In agreement with human mAb studies, transmigration of murine wild-type T helper type 1 cells across TNF-alpha-activated murine CD47(-/-) endothelium was reduced by 75% plus or minus 2% even though murine T cells appear to lack SIRPgamma. Nonetheless, these findings suggest endothelial cell CD47 interacting with T-cell ligands, such as SIRPgamma, play an important role in T-cell transendothelial migration.
Insights
Endothelial CD47 (Cluster of Differentiation 47) is crucial for T-cell transendothelial migration (TEM) during inflammation. Blocking CD47 or its ligand SIRPgamma significantly inhibits T-cell TEM, highlighting their role in immune responses.
Area of Science:
- Immunology
- Cell Biology
- Vascular Biology
Background:
- Leukocyte transendothelial migration (TEM) is vital for inflammatory responses.
- CD47 is known to mediate myeloid cell migration.
- The role of endothelial CD47 in T-cell TEM remains largely unexplored, especially under flow conditions.
Purpose of the Study:
- To investigate the role of endothelial CD47 in T-cell TEM.
- To determine the interaction between CD47 and T-cell ligands like SIRPgamma.
- To assess the impact of CD47-SIRPgamma blockade on T-cell transmigration in vitro.
Main Methods:
- Utilized fluorescence-activated cell sorting and biochemical analysis to determine protein expression on T cells.
- Employed fluorescence microscopy to visualize CD47 localization on endothelial cells.
- Established an in vitro flow model using blocking monoclonal antibodies (mAbs) against CD47 and SIRPgamma to study T-cell TEM.
- Examined T-cell transmigration across CD47(-/-) endothelium.
Main Results:
- CD3(+) T cells express SIRPgamma but not SIRPalpha.
- CD47 is enriched at endothelial junctions.
- Blocking mAbs against CD47 and SIRPgamma significantly inhibited T-cell TEM by 70-82% without affecting adhesion.
- Transmigration of T cells across CD47(-/-) endothelium was reduced by 75%.
Conclusions:
- Endothelial CD47 plays a significant role in T-cell transendothelial migration.
- CD47-SIRPgamma interactions are important for T-cell TEM.
- These findings suggest therapeutic potential for targeting CD47 in inflammatory diseases.
