Neutrophil Activation of Endothelial Cell-Expressed TRPM2 Mediates Transendothelial Neutrophil Migration and Vascular Injury
Rationale: TRPM2 (Transient Receptor Potential Melastatin-2) expressed in endothelial cells (ECs) is a cation channel mediating Ca2+ entry in response to intracellular generation of adenosine diphosphoribose (ADPR), the TRPM2 ligand.
Objective: Because polymorphonuclear leukocytes (PMN) interaction with endothelial cells (ECs) generates ROS, we addressed the possible role of TRPM2 expressed in ECs in the mechanism of transendothelial migration of PMNs.
Methods and Results: We observed defective PMN transmigration in response to LPS challenge in adult mice in which the EC expressed TRPM2 is conditionally deleted (Trpm2iΔEC). PMN interaction with ECs induced the entry of Ca2+ in ECs via the EC-expressed TRPM2. Prevention of generation of ADPR in ECs significantly reduced Ca2+ entry in response to PMN activation of TRPM2 in ECs. PMNs isolated from gp91phox-/- mice significantly reduced Ca2+ entry in ECs via TRPM2 as compared to WT PMNs and failed to induce PMN transmigration. Overexpression of the ADPR insensitive TRPM2 mutant channel (C1008→A) in ECs suppressed the Ca2+ entry response. Further the forced expression of TRPM2 C1008→A mutant channel or silencing of PARP-1 in ECs of mice prevented PMN transmigration.
Conclusions: Thus, endotoxin-induced transmigration of PMNs was secondary to TRPM2-activated Ca2+ signaling and VE-cadherin phosphorylation resulting in the disassembly of adherens junctions and opening of the paracellular pathways. These results suggest blocking TRPM2 activation in ECs is a potentially important means of therapeutically modifying PMN-mediated vascular inflammation.
- PMN Transmigration
- Acute Lung Injury
- polymorphonuclear leukocyte adhesion
- Received July 20, 2017.
- Revision received August 4, 2017.
- Accepted August 8, 2017.