scholarly journals Elucidating the Biomechanics of Leukocyte Transendothelial Migration by Quantitative Imaging

2021 ◽  
Vol 9 ◽  
Author(s):  
Amy B. Schwartz ◽  
Obed A. Campos ◽  
Ernesto Criado-Hidalgo ◽  
Shu Chien ◽  
Juan C. del Álamo ◽  
...  
Keyword(s):  
Vascular Endothelial Cells ◽  
Inflammatory Diseases ◽  
Leukocyte Adhesion ◽  
Decisive Role ◽  
Transendothelial Migration ◽  
Physical Contact ◽  
Cell Junctions ◽  
Force Transmission ◽  
Recent Advances ◽  
Leukocyte Transendothelial Migration

Leukocyte transendothelial migration is crucial for innate immunity and inflammation. Upon tissue damage or infection, leukocytes exit blood vessels by adhering to and probing vascular endothelial cells (VECs), breaching endothelial cell-cell junctions, and transmigrating across the endothelium. Transendothelial migration is a critical rate-limiting step in this process. Thus, leukocytes must quickly identify the most efficient route through VEC monolayers to facilitate a prompt innate immune response. Biomechanics play a decisive role in transendothelial migration, which involves intimate physical contact and force transmission between the leukocytes and the VECs. While quantifying these forces is still challenging, recent advances in imaging, microfabrication, and computation now make it possible to study how cellular forces regulate VEC monolayer integrity, enable efficient pathfinding, and drive leukocyte transmigration. Here we review these recent advances, paying particular attention to leukocyte adhesion to the VEC monolayer, leukocyte probing of endothelial barrier gaps, and transmigration itself. To offer a practical perspective, we will discuss the current views on how biomechanics govern these processes and the force microscopy technologies that have enabled their quantitative analysis, thus contributing to an improved understanding of leukocyte migration in inflammatory diseases.

scholarly journals TRPC6 is the endothelial calcium channel that regulates leukocyte transendothelial migration during the inflammatory response

2015 ◽  
Vol 212 (11) ◽  
pp. 1883-1899 ◽  
Author(s):  
Evan W. Weber ◽  
Fei Han ◽  
Mohammad Tauseef ◽  
Lutz Birnbaumer ◽  
Dolly Mehta ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Inflammatory Response ◽  
Calcium Channel ◽  
Transient Receptor Potential ◽  
Leukocyte Adhesion ◽  
Transendothelial Migration ◽  
Dominant Negative ◽  
Ion Concentration ◽  
Free Calcium ◽  
Leukocyte Transendothelial Migration

Leukocyte transendothelial migration (TEM) is a tightly regulated, multistep process that is critical to the inflammatory response. A transient increase in endothelial cytosolic free calcium ion concentration (↑[Ca2+]i) is required for TEM. However, the mechanism by which endothelial ↑[Ca2+]i regulates TEM and the channels mediating this ↑[Ca2+]i are unknown. Buffering ↑[Ca2+]i in endothelial cells does not affect leukocyte adhesion or locomotion but selectively blocks TEM, suggesting a role for ↑[Ca2+]i specifically for this step. Transient receptor potential canonical 6 (TRPC6), a Ca2+ channel expressed in endothelial cells, colocalizes with platelet/endothelial cell adhesion molecule-1 (PECAM) to surround leukocytes during TEM and clusters when endothelial PECAM is engaged. Expression of dominant-negative TRPC6 or shRNA knockdown in endothelial cells arrests neutrophils apically over the junction, similar to when PECAM is blocked. Selectively activating endothelial TRPC6 rescues TEM during an ongoing PECAM blockade, indicating that TRPC6 functions downstream of PECAM. Furthermore, endothelial TRPC6 is required for trafficking of lateral border recycling compartment membrane, which facilitates TEM. Finally, mice lacking TRPC6 in the nonmyeloid compartment (i.e., endothelium) exhibit a profound defect in neutrophil TEM with no effect on leukocyte trafficking. Our findings identify endothelial TRPC6 as the calcium channel mediating the ↑[Ca2+]i required for TEM at a step downstream of PECAM homophilic interactions.

TNF-induced endothelial barrier disruption: beyond actin and Rho

2014 ◽  
Vol 112 (12) ◽  
pp. 1088-1102 ◽  
Author(s):  
Beatriz Marcos-Ramiro ◽  
Diego García-Weber ◽  
Jaime Millán
Keyword(s):  
Endothelial Cell ◽  
Barrier Function ◽  
Endothelial Permeability ◽  
Transendothelial Migration ◽  
Cell Junctions ◽  
Endothelial Barrier ◽  
Endothelial Barrier Function ◽  
Adhesion Receptors ◽  
Barrier Disruption ◽  
Leukocyte Transendothelial Migration

SummaryThe decrease of endothelial barrier function is central to the long-term inflammatory response. A pathological alteration of the ability of endothelial cells to modulate the passage of cells and solutes across the vessel underlies the development of inflammatory diseases such as atherosclerosis and multiple sclerosis. The inflammatory cytokine tumour necrosis factor (TNF) mediates changes in the barrier properties of the endothelium. TNF activates different Rho GTPases, increases filamentous actin and remodels endothelial cell morphology. However, inhibition of actin-mediated remodelling is insufficient to prevent endothelial barrier disruption in response to TNF, suggesting that additional molecular mechanisms are involved. Here we discuss, first, the pivotal role of Rac-mediated generation of reactive oxygen species (ROS) to regulate the integrity of endothelial cell-cell junctions and, second, the ability of endothelial adhesion receptors such as ICAM-1, VCAM-1 and PECAM-1, involved in leukocyte transendothelial migration, to control endothelial permeability to small molecules, often through ROS generation. These adhesion receptors regulate endothelial barrier function in ways both dependent on and independent of their engagement by immune cells, and orchestrate the crosstalk between leukocyte transendothelial migration and endothelial permeability during inflammation.

scholarly journals Endothelial CD99 signals through soluble adenylyl cyclase and PKA to regulate leukocyte transendothelial migration

2015 ◽  
Vol 212 (7) ◽  
pp. 1021-1041 ◽  
Author(s):  
Richard L. Watson ◽  
Jochen Buck ◽  
Lonny R. Levin ◽  
Ryan C. Winger ◽  
Jing Wang ◽  
...  
Keyword(s):  
Adenylyl Cyclase ◽  
Membrane Trafficking ◽  
Leukocyte Adhesion ◽  
Transendothelial Migration ◽  
Cellular Adhesion ◽  
Soluble Adenylyl Cyclase ◽  
Signaling Complex ◽  
Leukocyte Transendothelial Migration

CD99 is a critical regulator of leukocyte transendothelial migration (TEM). How CD99 signals during this process remains unknown. We show that during TEM, endothelial cell (EC) CD99 activates protein kinase A (PKA) via a signaling complex formed with the lysine-rich juxtamembrane cytoplasmic tail of CD99, the A-kinase anchoring protein ezrin, and soluble adenylyl cyclase (sAC). PKA then stimulates membrane trafficking from the lateral border recycling compartment to sites of TEM, facilitating the passage of leukocytes across the endothelium. Pharmacologic or genetic inhibition of EC sAC or PKA, like CD99 blockade, arrests neutrophils and monocytes partway through EC junctions, in vitro and in vivo, without affecting leukocyte adhesion or the expression of relevant cellular adhesion molecules. This is the first description of the CD99 signaling pathway in TEM as well as the first demonstration of a role for sAC in leukocyte TEM.

scholarly journals Selective Targeting of Epigenetic Readers and Histone Deacetylases in Autoimmune and Inflammatory Diseases: Recent Advances and Future Perspectives

2021 ◽  
Vol 11 (5) ◽  
pp. 336
Author(s):  
Mohammed Ghiboub ◽  
Ahmed M. I. Elfiky ◽  
Menno P. J. de Winther ◽  
Nicola R. Harker ◽  
David F. Tough ◽  
...  
Keyword(s):  
Histone Deacetylases ◽  
Inflammatory Diseases ◽  
Selective Inhibition ◽  
In Vivo Studies ◽  
Beneficial Effects ◽  
Domain Specific ◽  
Recent Advances ◽  
Autoimmune And Inflammatory Diseases

Histone deacetylases (HDACs) and bromodomain-containing proteins (BCPs) play a key role in chromatin remodeling. Based on their ability to regulate inducible gene expression in the context of inflammation and cancer, HDACs and BCPs have been the focus of drug discovery efforts, and numerous small-molecule inhibitors have been developed. However, dose-limiting toxicities of the first generation of inhibitors, which typically target multiple HDACs or BCPs, have limited translation to the clinic. Over the last decade, an increasing effort has been dedicated to designing class-, isoform-, or domain-specific HDAC or BCP inhibitors, as well as developing strategies for cell-specific targeted drug delivery. Selective inhibition of the epigenetic modulators is helping to elucidate the functions of individual epigenetic proteins and has the potential to yield better and safer therapeutic strategies. In accordance with this idea, several in vitro and in vivo studies have reported the ability of more selective HDAC/BCP inhibitors to recapitulate the beneficial effects of pan-inhibitors with less unwanted adverse events. In this review, we summarize the most recent advances with these strategies, discussing advantages and limitations of these approaches as well as some therapeutic perspectives, focusing on autoimmune and inflammatory diseases.

Glycocalyx modulates the motility and proliferative response of vascular endothelium to fluid shear stress

2007 ◽  
Vol 293 (2) ◽  
pp. H1023-H1030 ◽  
Author(s):  
Yu Yao ◽  
Aleksandr Rabodzey ◽  
C. Forbes Dewey
Keyword(s):  
Endothelial Cells ◽  
Vascular Endothelium ◽  
Fluid Shear Stress ◽  
Vascular Endothelial Cells ◽  
Surface Profile ◽  
Cell Junctions ◽  
Vascular Endothelial ◽  
Fluid Shear ◽  
New Perspective ◽  
Cell Cell

Flow-induced mechanotransduction in vascular endothelial cells has been studied over the years with a major focus on putative connections between disturbed flow and atherosclerosis. Recent studies have brought in a new perspective that the glycocalyx, a structure decorating the luminal surface of vascular endothelium, may play an important role in the mechanotransduction. This study reports that modifying the amount of the glycocalyx affects both short-term and long-term shear responses significantly. It is well established that after 24 h of laminar flow, endothelial cells align in the direction of flow and their proliferation is suppressed. We report here that by removing the glycocalyx by using the specific enzyme heparinase III, endothelial cells no longer align under flow after 24 h and they proliferate as if there were no flow present. In addition, confluent endothelial cells respond rapidly to flow by decreasing their migration speed by 40% and increasing the amount of vascular endothelial cadherin in the cell-cell junctions. These responses are not observed in the cells treated with heparinase III. Heparan sulfate proteoglycans (a major component of the glycocalyx) redistribute after 24 h of flow application from a uniform surface profile to a distinct peripheral pattern with most molecules detected above cell-cell junctions. We conclude that the presence of the glycocalyx is necessary for the endothelial cells to respond to fluid shear, and the glycocalyx itself is modulated by the flow. The redistribution of the glycocalyx also appears to serve as a cell-adaptive mechanism by reducing the shear gradients that the cell surface experiences.

scholarly journals Brick Strex: a robust device built of LEGO bricks for mechanical manipulation of cells

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Elina Mäntylä ◽  
Teemu O. Ihalainen
Keyword(s):  
Molecular Mechanisms ◽  
Compressive Force ◽  
Tissue Mechanics ◽  
Cell Junctions ◽  
Physical Factors ◽  
Force Transmission ◽  
Cell Nuclei ◽  
Microscopy Imaging ◽  
Robust Solution ◽  
Mechanical Manipulation

AbstractCellular forces, mechanics and other physical factors are important co-regulators of normal cell and tissue physiology. These cues are often misregulated in diseases such as cancer, where altered tissue mechanics contribute to the disease progression. Furthermore, intercellular tensile and compressive force-related signaling is highlighted in collective cell behavior during development. However, the mechanistic understanding on the role of physical forces in regulation of cellular physiology, including gene expression and signaling, is still lacking. This is partly because studies on the molecular mechanisms of force transmission require easily controllable experimental designs. These approaches should enable both easy mechanical manipulation of cells and, importantly, readouts ranging from microscopy imaging to biochemical assays. To achieve a robust solution for mechanical manipulation of cells, we developed devices built of LEGO bricks allowing manual, motorized and/or cyclic cell stretching and compression studies. By using these devices, we show that $$\upbeta$$ β -catenin responds differentially to epithelial monolayer stretching and lateral compression, either localizing more to the cell nuclei or cell–cell junctions, respectively. In addition, we show that epithelial compression drives cytoplasmic retention and phosphorylation of transcription coregulator YAP1. We provide a complete part listing and video assembly instructions, allowing other researchers to build and use the devices in cellular mechanics-related studies.

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