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Shear stress affects migration behavior of polymorphonuclear cells arrested on endothelium
J Kitayama1, A Hidemura, H Saito
1Department of Surgery, The Surgical Center, The University of Tokyo, Hongo 7-3-1, Bunkyo-ku, Tokyo, 113, Japan.
Abstract:
Polymorphonuclear cell (PMN) transmigration across the TNF-alpha-stimulated endothelial cell (HUVEC) monolayer in the presence of shear flow was monitored with time-lapse videotapes. More than half of the PMN that arrested on HUVEC transmigrated through endothelial cell junctions within the following 15 min. The kinetics of transmigration was significantly faster than that of PMN placed under static conditions. Once PMN crept into the subendothelial space, they showed random migration beneath the HUVEC monolayer. PMN that did not transmigrate moved on the apical surface of HUVEC in the direction of flow downstream. Anti-beta1 integrin mAb (4B4) and RGD peptide inhibited the transmigration more effectively than anti-beta2 integrin mAb (TS1/18) and almost totally abrogated transmigration. When HUVEC were cultured on fibronectin or laminin, the transmigration was significantly inhibited by anti-alpha5 or alpha6 integrin mAbs, respectively. Our data clearly indicate that shear stress affects the migration behavior of PMN arrested on endothelium and suggest that binding to subendothelial extracellular matrix via beta1 integrins is another essential step in leukocyte extravasation.
Insights
Shear stress accelerates polymorphonuclear cell (PMN) transmigration across endothelial cells. Beta-1 integrins are crucial for PMN binding to the subendothelial matrix during leukocyte extravasation.
Area of Science:
- Cellular Biology
- Immunology
- Biophysics
Background:
- Leukocyte extravasation is a critical process in inflammation.
- Endothelial cells form a barrier that polymorphonuclear cells (PMNs) must traverse.
- Understanding the dynamics of PMN transmigration under flow is essential.
Purpose of the Study:
- To investigate the effect of shear flow on PMN transmigration across TNF-alpha-stimulated endothelial cells.
- To identify the molecular mechanisms, particularly integrin involvement, in PMN transmigration.
- To elucidate the role of the subendothelial extracellular matrix in PMN migration.
Main Methods:
- Time-lapse videotaping to monitor PMN transmigration across human umbilical vein endothelial cell (HUVEC) monolayers under shear flow.
- Inhibition studies using anti-integrin monoclonal antibodies (mAbs) and RGD peptide.
- HUVEC culture on fibronectin or laminin to assess matrix interactions.
Main Results:
- Shear flow significantly accelerated PMN transmigration compared to static conditions.
- Anti-beta1 integrin mAb (4B4) and RGD peptide were potent inhibitors of transmigration.
- Binding to fibronectin and laminin via alpha5 and alpha6 integrins, respectively, was also shown to be important.
Conclusions:
- Shear stress dynamically influences PMN migration behavior on the endothelium.
- Beta-1 integrin-mediated binding to the subendothelial extracellular matrix is a key step in leukocyte extravasation.
- Targeting beta-1 integrins may offer therapeutic strategies for inflammatory diseases.