Ena/VASP proteins regulate activated T-cell trafficking by promoting diapedesis during transendothelial migration

Abstract

Vasodilator-stimulated phosphoprotein (VASP) and Ena-VASP-like (EVL) are cytoskeletal effector proteins implicated in regulating cell morphology, adhesion, and migration in various cell types. However, the role of these proteins in T-cell motility, adhesion, and in vivo trafficking remains poorly understood. This study identifies a specific role for EVL and VASP in T-cell diapedesis and trafficking. We demonstrate that EVL and VASP are selectively required for activated T-cell trafficking but are not required for normal T-cell development or for naïve T-cell trafficking to lymph nodes and spleen. Using a model of multiple sclerosis, we show an impairment in trafficking of EVL/VASP-deficient activated T cells to the inflamed central nervous system of mice with experimental autoimmune encephalomyelitis. Additionally, we found a defect in trafficking of EVL/VASP double-knockout (dKO) T cells to the inflamed skin and secondary lymphoid organs. Deletion of EVL and VASP resulted in the impairment in α4 integrin (CD49d) expression and function. Unexpectedly, EVL/VASP dKO T cells did not exhibit alterations in shear-resistant adhesion to, or in crawling on, primary endothelial cells under physiologic shear forces. Instead, deletion of EVL and VASP impaired T-cell diapedesis. Furthermore, T-cell diapedesis became equivalent between control and EVL/VASP dKO T cells upon α4 integrin blockade. Overall, EVL and VASP selectively mediate activated T-cell trafficking by promoting the diapedesis step of transendothelial migration in a α4 integrin-dependent manner.A ctivated T-cell trafficking across the vascular endothelium is essential for ongoing immune surveillance of tissues and for effective immune responses to conditions such as infection and cancer. Conversely, in situations of immune dysregulation, inhibition of self-reactive T-cell trafficking represents a promising target for therapeutic immunomodulation. Disruption of these pathways, such as by antibody blockade of α4 integrins, is a highly effective approach to immunomodulation (1, 2). However, the molecular mechanisms by which chemokine receptor and adhesion molecule signaling induce the T-cell cytoskeletal machinery to promote extravasation are not yet fully elucidated.Transendothelial migration (TEM), the process by which T cells extravasate from the blood into tissues, is characterized by four distinct steps: rolling along the vascular wall, arrest or adhesion, intravascular crawling, and diapedesis across the endothelial barrier (3). Surface adhesion molecules play well-characterized roles in each step of the process. For example, the initial rolling step of TEM is facilitated by interactions between T-cell and endothelial selectins, whereas the adhesion, intravascular crawling, and diapedesis steps of TEM are mainly regulated by chemokineand shear force-stimulated modulation of lymphocyte functionassociated antigen 1 (LFA-1, αLβ2 integrin, CD11a/CD18) and very late antigen 4 (VLA-4, α4β1 integrin, CD49d/CD29) interactions with intracellular adhesion molecule 1 ...

Effector and Regulatory T Cells Roll at High Shear Stress by Inducible Tether and Sling Formation

“…The role of cytoskeleton in tethers and slings is poorly understood. One recent study showed that the cytoskeletal regulatory proteins vasodilator-stimulated phosphoprotein (VASP) and Ena-VASP–like (EVL) are involved in effector, but not naïve, T cell homing to inflamed sites (Estin et al, 2017). This suggests that cytoskeletal molecules might be involved in tether and sling formation.…”

The Formin mDia1 Regulates Acute Lymphoblastic Leukemia Engraftment, Migration, and Progression in vivo

“…Phase contrast and fluorescent images were acquired every 15–25 s using a 20X Phase-2 objective for 30 min long time-lapses using a Spinning Disk confocal microscope with environmental control (Intelligent Imaging Innovations) and Slidebook imaging software (Intelligent Imaging Innovations). Using similar criteria as previously described ( 11 , 29 ), a cell was scored as having undergone transendothelial when it lost its white phase ring in a step-wise process during the course of the time-lapse.…”

Impaired miRNA degradation by post-transcriptional addition of 3’ cytosine and adenine in T cell activation

“…Ena/VASP proteins are part of a complex that connects signaling from TCR receptor to actin remodeling (Krause et al 2000). A previous study used a double knock out mouse to demonstrate that EVL (Ena-VASP-like) and VASP are involved in activated T-cell trafficking into inflammation sites and secondary lymphoid tissues, particularly promoting diapedesis (Estin et al 2017). In light of these effects, the strong effort of T cells for up-regulating miR-1281 and miR-4455, respectively, earlier and higher than any other miRNA, might be related with generating a negative feedback for the control of T cell activation.…”